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Sample records for acid etching dental

  1. Dental zirconia can be etched by hydrofluoric acid.

    Science.gov (United States)

    Sriamporn, Tool; Thamrongananskul, Niyom; Busabok, Chumphol; Poolthong, Sushit; Uo, Motohiro; Tagami, Junji

    2014-01-01

    The surface morphology and crystal structure change of dental zirconia after hydrofluoric acid (HF) etching were evaluated. Four groups of sintered zirconia specimens were 1) control group, 2) immersion in 9.5%HF at 25°C for 1, 2, 3, or 24 h, 3) immersion in 9.5%HF at 80°C for 1, 3, 5, or 30 min and 4) immersion in 48%HF at 25°C for 30 or 60 min. The specimens were evaluated under SEM and XRD. The SEM analysis revealed changes in surface topography for all the HF-etched zirconia specimens. The irregularities surface increased with increasingly longer immersion times and higher etching solution temperatures. The XRD analysis of the HFetched zirconia specimens revealed the presence of a crystalline monoclinic phase along with a tetragonal form. It was concluded HF can etch dental zirconia ceramic, creating micro-morphological changes. Tetragonal-to-monoclinic phase transformation was induced on the etched zirconia surface.

  2. Dental enamel roughness with different acid etching times: Atomic force microscopy study

    OpenAIRE

    2012-01-01

    Objective: An important characteristic of human dental enamel not yet studied in detail is its surface roughness in mesoscopic scale. This study evaluated quantitatively and qualitatively the surface topography of acid etched enamel with different etching times. Materials and Methods: Ninety-six human maxillary bicuspids were randomly distributed into three groups (n=32): T0 (control), pumiced; T15, 35% phosphoric acid etched enamel for 15 s; T30, 35% phosphoric acid etched enamel for 30 s. R...

  3. Dental enamel roughness with different acid etching times: Atomic force microscopy study

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    Bruno Bochnia Cerci

    2012-01-01

    Full Text Available Objective: An important characteristic of human dental enamel not yet studied in detail is its surface roughness in mesoscopic scale. This study evaluated quantitatively and qualitatively the surface topography of acid etched enamel with different etching times. Materials and Methods: Ninety-six human maxillary bicuspids were randomly distributed into three groups (n=32: T0 (control, pumiced; T15, 35% phosphoric acid etched enamel for 15 s; T30, 35% phosphoric acid etched enamel for 30 s. Roughness measurements Ra, Rz and root mean square (RMS and 3D images of enamel′s topography were obtained with atomic force microscopy (AFM, which is a powerful technique to obtain direct measurements on microscale features. Results and Conclusions: Roughness variables Ra, Rz and RMS presented statistically significant differences to all groups (P<0.000, with values increasing with etching time. This increase was greater from T0 to T15 than from T15 to T30. Enamel surface alterations T15 to T30 occur mainly due to increase in height and deepening of prisms central region.

  4. Cell Adhesion and in Vivo Osseointegration of Sandblasted/Acid Etched/Anodized Dental Implants

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    Mu-Hyon Kim

    2015-05-01

    Full Text Available The authors describe a new type of titanium (Ti implant as a Modi-anodized (ANO Ti implant, the surface of which was treated by sandblasting, acid etching (SLA, and anodized techniques. The aim of the present study was to evaluate the adhesion of MG-63 cells to Modi-ANO surface treated Ti in vitro and to investigate its osseointegration characteristics in vivo. Four different types of Ti implants were examined, that is, machined Ti (control, SLA, anodized, and Modi-ANO Ti. In the cell adhesion study, Modi-ANO Ti showed higher initial MG-63 cell adhesion and induced greater filopodia growth than other groups. In vivo study in a beagle model revealed the bone-to-implant contact (BIC of Modi-ANO Ti (74.20% ± 10.89% was much greater than those of machined (33.58% ± 8.63%, SLA (58.47% ± 12.89, or ANO Ti (59.62% ± 18.30%. In conclusion, this study demonstrates that Modi-ANO Ti implants produced by sandblasting, acid etching, and anodizing improve cell adhesion and bone ongrowth as compared with machined, SLA, or ANO Ti implants. These findings suggest that the application of Modi-ANO surface treatment could improve the osseointegration of dental implant.

  5. Comparison of bond strength and surface morphology of dental enamel for acid and Nd-YAG laser etching

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    Parmeswearan, Diagaradjane; Ganesan, Singaravelu; Ratna, P.; Koteeswaran, D.

    1999-05-01

    Recently, laser pretreatment of dental enamel has emerged as a new technique in the field of orthodontics. However, the changes in the morphology of the enamel surface is very much dependent on the wavelength of laser, emission mode of the laser, energy density, exposure time and the nature of the substance absorbing the energy. Based on these, we made a comparative in vitro study on laser etching with acid etching with reference to their bond strength. Studies were conducted on 90 freshly extracted, non carious, human maxillary or mandibular anteriors and premolars. Out of 90, 60 were randomly selected for laser irradiation. The other 30 were used for conventional acid pretreatment. The group of 60 were subjected to Nd-YAG laser exposure (1060 nm, 10 Hz) at differetn fluences. The remaining 30 were acid pretreated with 30% orthophosphoric acid. Suitable Begg's brackets were selected and bound to the pretreated surface and the bond strength were tested using Instron testing machine. The bond strength achieved through acid pretreatment is found to be appreciably greater than the laser pretreated tooth. Though the bond strength achieved through the acid pretreated tooth is found to be significantly greater than the laser pretreated specimens, the laser pretreatement is found to be successful enough to produce a clinically acceptable bond strength of > 0.60 Kb/mm. Examination of the laser pre-treated tooth under SEM showed globule formation which may produce the mechanical interface required for the retention of the resin material.

  6. Surface Topographical Changes of a Failing Acid-Etched Long-Term in Function Retrieved Dental Implant.

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    Monje, Alberto; González-García, Raúl; Fernández-Calderón, María Coronada; Hierro-Oliva, Margarita; González-Martín, María Luisa; Del Amo, Fernando Suarez-Lopez; Galindo-Moreno, Pablo; Wang, Hom-Lay; Monje, Florencio

    2016-02-01

    The aim of the present study was to report the main topographical and chemical changes of a failing 18-year in function retrieved acid-etching implant in the micro- and nanoscales. A partially edentulous 45 year old rehabilitated with a dental implant at 18 years of age exhibited mobility. After careful examination, a 3.25 × 13-mm press-fit dental implant was retrieved. Scanning electron microscope (SEM) analysis was carried out to study topographical changes of the retrieved implant compared with an unused implant with similar topographical characteristics. Moreover, X-ray photoelectron spectroscopy (XPS) analysis was used to study the surface composition of the retrieved failing implant. Clear changes related to the dual dioxide layer are present as visible in ≥×500 magnification. In addition, it was found that, for the retrieved implant, the surface composition consisted mainly of Ti2p, O1s, C1s, and Al2p. Also, a meaningful decrease of N and C was noticed, whereas the peaks of Ti2p, Al2p, and O1s increased when analyzing deeper (up to ×2000s) in the sample. It was shown that the superficial surface of a retrieved press-fit dual acid-etched implant 18 years after placement is impaired. However, the causes and consequences for these changes cannot be determined.

  7. The Effect of Hydrofluoric Acid Etching Duration on the Surface Micromorphology, Roughness, and Wettability of Dental Ceramics

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    Ramakrishnaiah, Ravikumar; Alkheraif, Abdulaziz A.; Divakar, Darshan Devang; Matinlinna, Jukka P.; Vallittu, Pekka K.

    2016-01-01

    The current laboratory study is evaluating the effect of hydrofluoric acid etching duration on the surface characteristics of five silica-based glass ceramics. Changes in the pore pattern, crystal structure, roughness, and wettability were compared and evaluated. Seventy-five rectangularly shaped specimens were cut from each material (IPS e-max™, Dentsply Celtra™, Vita Suprinity™, Vita mark II™, and Vita Suprinity FC™); the sectioned samples were finished, polished, and ultrasonically cleaned. Specimens were randomly assigned into study groups: control (no etching) and four experimental groups (20, 40, 80 and 160 s of etching). The etched surfaces’ microstructure including crystal structure, pore pattern, pore depth, and pore width was studied under a scanning electron microscope, and the surface roughness and wettability were analyzed using a non-contact surface profilometer and a contact angle measuring device, respectively. The results were statistically analyzed using one-way analysis of variance (ANOVA) and the post hoc Tukey’s test. The results showed a significant change in the pore number, pore pattern, crystal structure, surface roughness, and wettability with increased etching duration. Etching for a short time resulted in small pores, and etching for longer times resulted in wider, irregular grooves. A significant increase in the surface roughness and wettability was observed with an increase in the etching duration. The findings also suggested a strong association between the surface roughness and wettability. PMID:27240353

  8. The Effect of Hydrofluoric Acid Etching Duration on the Surface Micromorphology, Roughness, and Wettability of Dental Ceramics

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    Ravikumar Ramakrishnaiah

    2016-05-01

    Full Text Available The current laboratory study is evaluating the effect of hydrofluoric acid etching duration on the surface characteristics of five silica-based glass ceramics. Changes in the pore pattern, crystal structure, roughness, and wettability were compared and evaluated. Seventy-five rectangularly shaped specimens were cut from each material (IPS e-max™, Dentsply Celtra™, Vita Suprinity™, Vita mark II™, and Vita Suprinity FC™; the sectioned samples were finished, polished, and ultrasonically cleaned. Specimens were randomly assigned into study groups: control (no etching and four experimental groups (20, 40, 80 and 160 s of etching. The etched surfaces’ microstructure including crystal structure, pore pattern, pore depth, and pore width was studied under a scanning electron microscope, and the surface roughness and wettability were analyzed using a non-contact surface profilometer and a contact angle measuring device, respectively. The results were statistically analyzed using one-way analysis of variance (ANOVA and the post hoc Tukey’s test. The results showed a significant change in the pore number, pore pattern, crystal structure, surface roughness, and wettability with increased etching duration. Etching for a short time resulted in small pores, and etching for longer times resulted in wider, irregular grooves. A significant increase in the surface roughness and wettability was observed with an increase in the etching duration. The findings also suggested a strong association between the surface roughness and wettability.

  9. The Effect of Hydrofluoric Acid Etching Duration on the Surface Micromorphology, Roughness, and Wettability of Dental Ceramics.

    Science.gov (United States)

    Ramakrishnaiah, Ravikumar; Alkheraif, Abdulaziz A; Divakar, Darshan Devang; Matinlinna, Jukka P; Vallittu, Pekka K

    2016-05-27

    The current laboratory study is evaluating the effect of hydrofluoric acid etching duration on the surface characteristics of five silica-based glass ceramics. Changes in the pore pattern, crystal structure, roughness, and wettability were compared and evaluated. Seventy-five rectangularly shaped specimens were cut from each material (IPS e-max™, Dentsply Celtra™, Vita Suprinity™, Vita mark II™, and Vita Suprinity FC™); the sectioned samples were finished, polished, and ultrasonically cleaned. Specimens were randomly assigned into study groups: control (no etching) and four experimental groups (20, 40, 80 and 160 s of etching). The etched surfaces' microstructure including crystal structure, pore pattern, pore depth, and pore width was studied under a scanning electron microscope, and the surface roughness and wettability were analyzed using a non-contact surface profilometer and a contact angle measuring device, respectively. The results were statistically analyzed using one-way analysis of variance (ANOVA) and the post hoc Tukey's test. The results showed a significant change in the pore number, pore pattern, crystal structure, surface roughness, and wettability with increased etching duration. Etching for a short time resulted in small pores, and etching for longer times resulted in wider, irregular grooves. A significant increase in the surface roughness and wettability was observed with an increase in the etching duration. The findings also suggested a strong association between the surface roughness and wettability.

  10. Ultrastructure of the surface of dental enamel with molar incisor hypomineralization (MIH) with and without acid etching.

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    Bozal, Carola B; Kaplan, Andrea; Ortolani, Andrea; Cortese, Silvina G; Biondi, Ana M

    2015-01-01

    The aim of the present work was to analyze the ultrastructure and mineral composition of the surface of the enamel on a molar with MIH, with and without acid etching. A permanent tooth without clinical MIH lesions (control) and a tooth with clinical diagnosis of mild and moderate MIH, with indication for extraction, were processed with and without acid etching (H3PO4 37%, 20") for observation with scanning electron microscope (SEM) ZEISS (Supra 40) and mineral composition analysis with an EDS detector (Oxford Instruments). The control enamel showed normal prismatic surface and etching pattern. The clinically healthy enamel on the tooth with MIH revealed partial loss of prismatic pattern. The mild lesion was porous with occasional cracks. The moderate lesion was more porous, with larger cracks and many scales. The mineral composition of the affected surfaces had lower Ca and P content and higher O and C. On the tooth with MIH, even on normal looking enamel, the demineralization does not correspond to an etching pattern, and exhibits exposure of crystals with rods with rounded ends and less demineralization in the inter-prismatic spaces. Acid etching increased the presence of cracks and deep pores in the adamantine structure of the enamel with lesion. In moderate lesions, the mineral composition had higher content of Ca, P and Cl. Enamel with MIH, even on clinically intact adamantine surfaces, shows severe alterations in the ultrastructure and changes in ionic composition, which affect the acid etching pattern and may interfere with adhesion.

  11. Adult stem cells properties in terms of commitment, aging and biological safety of grit-blasted and Acid-etched ti dental implants surfaces.

    Science.gov (United States)

    Gardin, Chiara; Ferroni, Letizia; Bressan, Eriberto; Calvo-Guirado, José L; Degidi, Marco; Piattelli, Adriano; Zavan, Barbara

    2014-01-01

    Titanium (Ti) is one of the most widely used biomaterials for manufacturing dental implants. The implant surface properties strongly influence osseointegration. The aim of the present study was to in vitro investigate the characteristics of Ti dental implants in terms of mutagenicity, hemocompatibility, biocompatibility, osteoinductivity and biological safety. The Ames test was used to test the mutagenicity of the Ti dental implants, and the hemolysis assay for evaluating their hemocompatibility. Human adipose - derived stem cells (ADSCs) were then seeded onto these implants in order to evaluate their cytotoxicity. Gene expression analyzing with real-time PCR was carried out to investigate the osteoinductivity of the biomaterials. Finally, the genetic stability of the cells cultured onto dental implants was determined by karyotyping. Our results demonstrated that Ti dental implants are not mutagenic, do not cause hemolysis, and are biocompatible. The MTT assay revealed that ADSCs, seeded on Ti dental implants, proliferate up to 30 days in culture. Moreover, ADSCs loaded on Ti dental implants show a substantial expression of some osteoblast specific markers, such as COL1A1, OPN, ALPL, and RUNX2, as well as chromosomal stability after 30 days of culture in a medium without osteogenic factors. In conclusion, the grit-blasted and acid-etched treatment seems to favor the adhesion and proliferation of ADSCs and improve the osteoinductivity of Ti dental implant surfaces.

  12. Prospective clinical evaluation of 273 modified acid-etched dental implants: 1- to 5- year results

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    Michele De Franco

    2012-03-01

    Full Text Available Aim: The aim of this study was to evaluate the implant survival and the implant-crown success of implants with surface treated with organic acids. Materials and methods: A total of 273 implants (Implus®, Leader-Novaxa, Milan, Italy were inserted in 63 patients, from June 2006 to June 2010, in a single clinical centre. In each annual follow up session, clinical, radiographic and prosthetic parameters were evaluated. The implant-crown success criteria included the absence of pain, suppuration and clinical mobility, a distance between the implant shoulder and the first visible bone contact (DIB <2.0 mm from the surgery and the absence of prosthetic complications at the implantabutment interface. Prosthetic restorations were 32 fixed partial prostheses, 48 single crowns and 16 fixed full arches. Results: The cumulative survival rate was 95.70% (93.81 maxilla, 98.24% mandible. Among the surviving implants, the implant-crown success was 96.07%. At the 5-year control, the mean DIB was 1.2 mm (± 0.5. Conclusion: Implants with surface treated with organic acids seem to represent a good solution for the prosthetic rehabilitation of partially and completely edentulous patients.

  13. Modification of etching patterns in bovine dental enamel.

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    Lees, S; Trombly, P L; Skobe, Z; Gariepy, E E; Trull, A F

    1979-08-01

    It is presumed that the etching pattern is controlled by the residual organic content of dental enamel. Pretreatment with 1.ON NaOH sould remove the organic material and modify the etching pattern. SEM studies and other tests for physical and chemical properties show that the predicted modification of the etching pattern, when the tooth surface is pretreated with NaOH solution, occurs apparently without other changes or properties.

  14. 磨除后酸蚀对氟斑牙正畸托槽脱落率的影响%Effects of bonding after microabrasion with normal acid etching time on losing ratio of orthodontic brackets to dental fluorosis

    Institute of Scientific and Technical Information of China (English)

    董晶; 张哲湛

    2016-01-01

    越高.对于中、重度氟斑牙的临床矫治,磨除后酸蚀法治疗效果优于延长酸蚀时间法.%Objective To investigate the effects of losing ratio of orthodontic brackets bonding after prolonged etching time (prolonged etching time method) and microabrasion with normal acid etching time (etching after microabrasion method) to different degree of dental fluorosis.Methods A total of 30 patients with dental fluorosis were selected from the cases treated in the Department of Stomatology,Lianyungang Hospital of Traditional Chinese Medicine.They were classified as 3 groups from mild to severe degree according to Dean's criteria,10 people per group.Patients within each group were randomly assigned to 2 subgroups,5 people per subgroup;prolonged etching time method and etching after microabrasion method were used,respectively,in each subgroup.The total and first losing ratios of brackets at five time points (1,2,4,12 and 24 weeks) were observed.The losing ratio differences of orthodontic brackets between the two disposing measures bonding to different degree of dental fluorosis were analyzed.Resuts The total bracket loss rates were 38.3% (46/120) and 21.4% (25/117),respectively,in severe dental fluorosis disposed by prolonged etching time method and etching after microabrasion method.It was significantly higher than that of the same processing method of mild and moderate dental fluorosis groups,in which the total bracket loss rates were 12.5% (15/120),18.1% (21/116),7.6% (9/118) and 5.8% (7/120),respectively,and the differences were statistically significant (x2 =21.12,11.87,8.96,12.24,all P < 0.01).The total loss rate of etching after microabrasion method was lower than that of prolonged etching time method in mild dental fluorosis group,the difference was not statistically significant (x2 =1.56,P > 0.05).The total loss rates of etching after microabrasion method were lower than that of prolonged etching time method in moderate and severe

  15. AFM and SEM study of the effects of etching on IPS-Empress 2 TM dental ceramic

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    Luo, X.-P.; Silikas, N.; Allaf, M.; Wilson, N. H. F.; Watts, D. C.

    2001-10-01

    The aim of this study was to investigate the effects of increasing etching time on the surface of the new dental material, IPS-Empress 2 TM glass ceramic. Twenty one IPS-Empress 2 TM glass ceramic samples were made from IPS-Empress 2 TM ingots through lost-wax, hot-pressed ceramic fabrication technology. All samples were highly polished and cleaned ultrasonically for 5 min in acetone before and after etching with 9.6% hydrofluoric acid gel. The etching times were 0, 10, 20, 30, 60, 90 and 120 s respectively. Microstructure was analysed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) was used to evaluate the surface roughness and topography. Observations with SEM showed that etching with hydrofluoric acid resulted in preferential dissolution of glass matrix, and that partially supported crystals within the glass matrix were lost with increasing etching time. AFM measurements indicated that etching increased the surface roughness of the glass-ceramic. A simple least-squares linear regression was used to establish a relationship between surface roughness parameters ( Ra, RMS), and etching time, for which r2>0.94. This study demonstrates the benefits of combining two microscopic methods for a better understanding of the surface. SEM showed the mode of action of hydrofluoric acid on the ceramic and AFM provided valuable data regarding the extent of surface degradation relative to etching time.

  16. STUDY ON THE EFFECTS OF ACID ETCHING ON AFFECTED ENAMEL

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    Simona Stoleriu

    2011-12-01

    Full Text Available The purpose of the study was to establish and compare the effects of ortophosphoric and hydrochloric acids on the enamel affected by incipient carious lesions with different evolution. Materials and method. 20 teeth with acute and chronic non-cavitary carious lesions were considered for the study. The teeth were sectioned in two halves through the middle of the non-cavitary lesions. The halves of 5 white spot-type lesions and of 5 brown spot-type ones were analyzed as to their surface roughness, on an atomic force microscope (AFM. 5 halves with white spot-type lesions and 5 halves with brown spot-type ones were subjected to acid etching with 37% ortophosphoric acid (Scotchbond etchant gel, 3M ESPE, and an equal number of samples was subjected to the action of 15% hydrochloric acid (ICON-etch, DMG Dental Products Ltd for 2 min, then washed with water and analyzed by AFM. Results. The initial surface roughness of the enamel was higher in the white spot–type carious lesions, comparatively with the brown spot-type ones. For both types of carious non-cavitary lesions, acid etching with phosphoric and hydrochloric acid significantly increased the surface roughness of the enamel, comparatively with the status of the enamel surface prior to etching. The hydrochloric acid led to a surface roughness significantly higher than in the case of ortophosphoric acid, in both acute and chronic non-cavitary carious lesions. The roughness values obtained through etching with ortophosphoric and hydrochloric acid were higher in the white spot-type carious lesions, comparatively with the brown spot-type ones. Conclusions. Both the 37% ortophosphoric acid and the 15% hydrochloric acid determined a significantly higher surface roughness of the enamel affected by acute and chronic non-cavitary carious lesions. The surface condition of the brown spot-type carious lesions was less significantly modified, comparatively with that of the white spot-type lesions, by the

  17. Effect of phosphoric acid etching on the shear bond strength of two self-etch adhesives

    OpenAIRE

    SABATINI, Camila

    2013-01-01

    Objective To evaluate the effect of optional phosphoric acid etching on the shear bond strength (SBS) of two self-etch adhesives to enamel and dentin. Material and Methods Ninety-six bovine mandibular incisors were ground flat to obtain enamel and dentin substrates. A two-step self-etch adhesive (FL-Bond II) and a one-step self-etch adhesive (BeautiBond) were applied with and without a preliminary acid etching to both the enamel and dentin. The specimens were equally and randomly assigned t...

  18. The research on conformal acid etching process of glass ceramic

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    Wang, Kepeng; Guo, Peiji

    2014-08-01

    A series of experiments have been done to explore the effect of different conditions on the hydrofluoric acid etching. The hydrofluoric acid was used to etch the glass ceramic called "ZERODUR", which is invented by SCHOTT in Germany. The glass ceramic was processed into cylindrical samples. The hydrofluoric acid etching was done in a plastic beaker. The concentration of hydrofluoric acid and the etching time were changed to measure the changes of geometric tolerance and I observed the surface using a microscope in order to find an appropriate condition of hydrofluoric acid etching.

  19. Bond strengths of all-ceramics: acid vs laser etching.

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    Gökçe, B; Ozpinar, B; Dündar, M; Cömlekoglu, E; Sen, B H; Güngör, M A

    2007-01-01

    Various applications of dental lasers on dental materials have been proposed for surface modifications. This study evaluated whether laser etching could be an alternative to hydrofluoric acid (HF) etching. One hundred and ten lithia-based all-ceramic specimens (Empress 2) (R: 4 mm, h: 4 mm) were prepared and divided into five groups (n = 22/group). The untreated specimens served as the control, while one of the experimental groups was treated with 9.5% HF for 30 seconds. Three remaining test groups were treated with different laser (Er:YAG laser wavelength:2940 nm, OpusDent) power settings: 300 mJ, 600 mJ and 900 mJ. Ten specimens in each group were luted to the other 10 specimens by a dual-curing cement (Variolink II), and shear-bond strength (SBS) tests were performed (Autograph, crosshead speed: 0.5 mm/minute). The results were statistically analyzed (Kruskal Wallis and Mann Whitney-U, alpha = .05). Mean SBS (MPa) were 31.9 +/- 4.0, 41.4 +/- 4.3, 42.8 +/- 6.2, 29.2 +/- 4.5 and 27.4 +/- 3.8 for the control and HF, 300, 600 and 900 mJ groups, respectively. SEM evaluations revealed different surface morphologies depending on the laser parameters. The differences between HF acid and 300 mJ, when compared with the control, 600 and 900 mJ groups, were significant (p < .05). The 300 mJ laser group exhibited the highest shear-bond strength values, indicating that laser etching could also be used for surface treatments.

  20. Atomic force microscopy observation of the enamel roughness and depth profile after phosphoric acid etching.

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    Loyola-Rodriguez, Juan Pablo; Zavala-Alonso, Veronica; Reyes-Vela, Enrique; Patiño-Marin, Nuria; Ruiz, Facundo; Anusavice, Kenneth J

    2010-01-01

    The aim was to compare the enamel surface roughness (ESR) and absolute depth profile (ADP) (mean peak-to-valley height) by atomic force microscopy (AFM) before and after using four different phosphoric acids. A total of 160 enamel samples from 40 upper premolars were prepared. The inclusion criterion was that the teeth have healthy enamel. Exclusion criteria included any of the following conditions: facial restorations, caries lesions, enamel hypoplasia and dental fluorosis. Evaluations of the ESR and ADP were carried out by AFM. The Mann-Whitney U-test was used to compare continuous variables and the Wilcoxon test was used to analyze the differences between before and after etching. There were statistically significant differences (P roughness and absolute depth before and after using four different phosphoric acids in healthy enamel; Etch-37 and Scotchbond Etching Gel showed higher profiles after etching (P roughness and ADP before and after using four different phosphoric acids in healthy enamel. However, consistently Etch-37 and Scotchbond Etching Gel showed the highest increase regarding the ESR and ADP after etching healthy enamel. AFM was a useful tool to study site-specific structural topography changes in enamel after phosphoric acid etching.

  1. Effect of Phosphoric Acid on the Self Etching Primer Bond Strength and its Relation to Oral Health Status

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    E Yassini

    2005-06-01

    Full Text Available Self etching primers, due to ease of manipulation, have been extensively used in recent years. These self etching primers containing a relatively weak acid, may not provide an optimal bond strength. The purpose of the present in-vitro investigation was to evaluate the effects of 37% phosphoric acid application prior to applying self etching primers on composite bond strength. In this experimental study a total of 48 premolar and molar teeth, free of caries, filling, abrasion, crack or other dental defects were selected. The extracted teeth were immediately stored in physiologic serum and divided randomly into two equal groups (n=24.Each group was also divided into two subgroups of twelve teeth each as follows: Subgroup A: enamel was not acid-etched, subgroup B: enamel was acid-etched (group I.Subgroup C: dentin was not acid- etched, subgroup D: dentin was acid-etched (group II.In acid-conditioned groups, water rinsing was followed by the application of a bonding agent (Etch & Primer 3, however for non-acid-treated groups, just the bonding agent was used. Then composite resin blocks (1.5×2 mm and 2.5 mm in diameter were formed and light cured at all directions for 40 seconds, following this the specimens were placed in an Instron universal testing machine to determine shear bond strength. The data were analyzed by t-test. Results showed that no statistically significant differences were between the mean values of etch and un-etch enamel (P=0.232, similarly those of etch and un-etch dentin (P=0.148. In this investigation we concluded that acidic components employed in self-etching primers were of weak type, but self-etching primers could be used without phosphoric acid conditioning.

  2. Effect of phosphoric acid etching on the shear bond strength of two self-etch adhesives

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    Camila SABATINI

    2013-01-01

    Full Text Available Objective To evaluate the effect of optional phosphoric acid etching on the shear bond strength (SBS of two self-etch adhesives to enamel and dentin. Material and Methods Ninety-six bovine mandibular incisors were ground flat to obtain enamel and dentin substrates. A two-step self-etch adhesive (FL-Bond II and a one-step self-etch adhesive (BeautiBond were applied with and without a preliminary acid etching to both the enamel and dentin. The specimens were equally and randomly assigned to 4 groups per substrate (n=12 as follows: FL-Bond II etched; FL-Bond II un-etched; BeautiBond etched; BeautiBond un-etched. Composite cylinders (Filtek Z100 were bonded onto the treated tooth structure. The shear bond strength was evaluated after 24 hours of storage (37°C, 100% humidity with a testing machine (Ultra-tester at a speed of 1 mm/min. The data was analyzed using a two-way ANOVA and post-hoc Tukey's test with a significance level of p<0.05. A field emission scanning electron microscope was used for the failure mode analysis. Results Both adhesives evidenced a significant decrease in the dentin SBS with the use of an optional phosphoric acid-etching step (p<0.05. Preliminary phosphoric acid etching yielded significantly higher enamel SBS for FL-Bond II (p<0.05 only, but not for BeautiBond. FL-Bond II applied to un-etched dentin demonstrated the highest mean bond strength (37.7±3.2 MPa and BeautiBond applied to etched dentin showed the lowest mean bond strength (18.3±6.7 MPa among all tested groups (p<0.05. Conclusion The use of a preliminary acid-etching step with 37.5% phosphoric acid had a significant adverse effect on the dentin bond strength of the self-etch adhesives evaluated while providing improvement on the enamel bond strength only for FL-Bond II. This suggests that the potential benefit that may be derived from an additional etching step with phosphoric acid does not justify the risk of adversely affecting the bond strength to dentin.

  3. SEM analysis of the acid-etched enamel patterns promoted by acidic monomers and phosphoric acids Avaliação em MEV do padrão de condicionamento do esmalte dental promovido por monômeros ácidos e o ácido fosfórico

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    Mirela Sanae Shinohara

    2006-12-01

    Full Text Available ABSTRACT OBJECTIVE: Although self-etching bonding systems (SES are indicated to prepare dental enamel for bonding, concerns have been expressed regarding their effectiveness. The aim of this study was to analyze the etching pattern (EP of nine SES in comparison with 35% and 34% phosphoric acid etchants (FA on intact (IN and ground (GR enamel surface. MATERIALS AND METHODS: Twenty-two human third molars were sectioned in mesial-distal and buccal-lingual directions, and four dental fragments were obtained from each tooth. Half of the fragments were ground using 600-grit SiC paper and the other half remained intact. The fragments were randomly assigned into 22 groups, according to the texture of enamel surface (IN and GR and the technique to etch the enamel (34% FA, 35% FA, AdheSE primer; Brush & Bond; Clearfil Protect Bond primer; iBond; One-up Bond F; OptiBond Solo Plus primer; Tyrian SPE primer; Unifil Bond primer and Xeno III. Conditioners were applied to IN and GR enamel surfaces, according to the manufacturer's instructions. Specimens etched with phosphoric acids were washed with water, while the surfaces treated with SES were submitted to alternate rinsing with alcohol and acetone. The specimens were dried, sputter-coated and examined under a scanning electron microscope. RESULTS: For both IN and GR enamel surfaces, the EP of 34 and 35% FA was deeper and more homogeneous in comparison to EP of SES, except for Tyrian SPE. The acidic monomer action of self-etching systems was more effective on GR enamel. CONCLUSION: Most of the SES are less aggressive than phosphoric acid etchants and their etching effects were reduced on intact enamel surfaces.OBJETIVO: Apesar dos sistemas adesivos autocondicionantes (SAA serem indicados para aplicação no esmalte dental, preocupação tem sido relatada com relação a sua efetividade. O objetivo deste estudo foi avaliar o padrão de condicionamento ácido (PCA promovido por nove SAA e comparar ao PCA

  4. Comparison of Self-Etch Primers with Conventional Acid Etching System on Orthodontic Brackets

    Science.gov (United States)

    Zope, Amit; Zope-Khalekar, Yogita; Chitko, Shrikant S.; Kerudi, Veerendra V.; Patil, Harshal Ashok; Jaltare, Pratik; Dolas, Siddhesh G

    2016-01-01

    Introduction The self-etching primer system consists of etchant and primer dispersed in a single unit. The etching and priming are merged as a single step leading to fewer stages in bonding procedure and reduction in the number of steps that also reduces the chance of introduction of error, resulting in saving time for the clinician. It also results in smaller extent of enamel decalcification. Aim To compare the Shear Bond Strength (SBS) of orthodontic bracket bonded with Self-Etch Primers (SEP) and conventional acid etching system and to study the surface appearance of teeth after debonding; etching with conventional acid etch and self-etch priming, using stereomicroscope. Materials and Methods Five Groups (n=20) were created randomly from a total of 100 extracted premolars. In a control Group A, etching of enamel was done with 37% phosphoric acid and bonding of stainless steel brackets with Transbond XT (3M Unitek, Monrovia, California). Enamel conditioning in left over four Groups was done with self-etching primers and adhesives as follows: Group B-Transbond Plus (3M Unitek), Group C Xeno V+ (Dentsply), Group D-G-Bond (GC), Group E-One-Coat (Coltene). The Adhesive Remnant Index (ARI) score was also evaluated. Additionally, the surface roughness using profilometer were observed. Results Mean SBS of Group A was 18.26±7.5MPa, Group B was 10.93±4.02MPa, Group C was 6.88±2.91MPa while of Group D was 7.78±4.13MPa and Group E was 10.39±5.22MPa respectively. In conventional group ARI scores shows that over half of the adhesive was remaining on the surface of tooth (score 1 to 3). In self-etching primer groups ARI scores show that there was no or minor amount of adhesive remaining on the surface of tooth (score 4 and 5). SEP produces a lesser surface roughness on the enamel than conventional etching. However, statistical analysis shows significant correlation (p<0.001) of bond strength with surface roughness of enamel. Conclusion All groups might show clinically

  5. Crystal growth vs. conventional acid etching: A comparative evaluation of etch patterns, penetration depths, and bond strengths

    Directory of Open Access Journals (Sweden)

    Devanna Raghu

    2008-01-01

    Full Text Available The present study was undertaken to investigate the effect on enamel surface, penetration depth, and bond strength produced by 37% phosphoric acid and 20% sulfated polyacrylic acid as etching agents for direct bonding. Eighty teeth were used to study the efficacy of the etching agents on the enamel surface, penetration depth, and tensile bond strength. It was determined from the present study that a 30 sec application of 20% sulfated polyacrylic acid produced comparable etching topography with that of 37% phosphoric acid applied for 30 sec. The 37% phosphoric acid dissolves enamel to a greater extent than does the 20% sulfated polyacrylic acid. Instron Universal testing machine was used to evaluate the bond strengths of the two etching agents. Twenty percent sulfated polyacrylic acid provided adequate tensile bond strength. It was ascertained that crystal growth can be an alternative to conventional phosphoric acid etching as it dissolves lesser enamel and provides adequate tensile bond strength.

  6. Hydrogen content in titanium and a titanium-zirconium alloy after acid etching.

    Science.gov (United States)

    Frank, Matthias J; Walter, Martin S; Lyngstadaas, S Petter; Wintermantel, Erich; Haugen, Håvard J

    2013-04-01

    Dental implant alloys made from titanium and zirconium are known for their high mechanical strength, fracture toughness and corrosion resistance in comparison with commercially pure titanium. The aim of the study was to investigate possible differences in the surface chemistry and/or surface topography of titanium and titanium-zirconium surfaces after sand blasting and acid etching. The two surfaces were compared by X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, scanning electron microscopy and profilometry. The 1.9 times greater surface hydrogen concentration of titanium zirconium compared to titanium was found to be the major difference between the two materials. Zirconium appeared to enhance hydride formation on titanium alloys when etched in acid. Surface topography revealed significant differences on the micro and nanoscale. Surface roughness was increased significantly (pzirconium alloy. High-resolution images showed nanostructures only present on titanium zirconium.

  7. Improved Resin–Zirconia Bonding by Room Temperature Hydrofluoric Acid Etching

    Directory of Open Access Journals (Sweden)

    Mun-Hwan Lee

    2015-03-01

    Full Text Available This in vitro study was conducted to evaluate the shear bond strength of “non-self-adhesive” resin to dental zirconia etched with hydrofluoric acid (HF at room temperature and to compare it to that of air-abraded zirconia. Sintered zirconia plates were air-abraded (control or etched with 10%, 20%, or 30% HF for either 5 or 30 min. After cleaning, the surfaces were characterized using various analytical techniques. Three resin cylinders (Duo-Link were bonded to each treated plate. All bonded specimens were stored in water at 37 °C for 24 h, and then half of them were additionally thermocycled 5000 times prior to the shear bond-strength tests (n = 12. The formation of micro- and nano-porosities on the etched surfaces increased with increasing concentration and application time of the HF solution. The surface wettability of zirconia also increased with increasing surface roughness. Higher concentrations and longer application times of the HF solution produced higher bond-strength values. Infiltration of the resin into the micro- and nano-porosities was observed by scanning electron microscopy. This in vitro study suggests that HF slowly etches zirconia ceramic surfaces at room temperature, thereby improving the resin–zirconia bond strength by the formation of retentive sites.

  8. Can previous acid etching increase the bond strength of a self-etching primer adhesive to enamel?

    Directory of Open Access Journals (Sweden)

    Ana Paula Morales Cobra Carvalho

    2009-06-01

    Full Text Available Because a greater research effort has been directed to analyzing the adhesive effectiveness of self etch primers to dentin, the aim of this study was to evaluate, by microtensile testing, the bond strength to enamel of a composite resin combined with a conventional adhesive system or with a self-etching primer adhesive, used according to its original prescription or used with previous acid etching. Thirty bovine teeth were divided into 3 groups with 10 teeth each (n= 10. In one of the groups, a self-etching primer (Clearfil SE Bond - Kuraray was applied in accordance with the manufacturer's instructions and, in the other, it was applied after previous acid etching. In the third group, a conventional adhesive system (Scotchbond Multipurpose Plus - 3M-ESPE was applied in accordance with the manufacturer's instructions. The results obtained by analysis of variance revealed significant differences between the adhesive systems (F = 22.31. The self-etching primer (Clearfil SE Bond presented lower enamel bond strength values than the conventional adhesive system (Scotchbond Multipurpose Plus (m = 39.70 ± 7.07 MPa both when used according to the original prescription (m = 27.81 ± 2.64 MPa and with previous acid etching (m = 25.08 ± 4.92 MPa.

  9. Influence of pH, bleaching agents, and acid etching on surface wear of bovine enamel

    Directory of Open Access Journals (Sweden)

    Ana Flávia Soares

    2016-02-01

    Full Text Available ABSTRACT Development of new materials for tooth bleaching justifies the need for studies to evaluate the changes in the enamel surface caused by different bleaching protocols. Objective The aim of this study was to evaluate the bovine dental enamel wear in function of different bleaching gel protocols, acid etching and pH variation. Material and Methods Sixty fragments of bovine teeth were cut, obtaining a control and test areas. In the test area, one half received etching followed by a bleaching gel application, and the other half, only the bleaching gel. The fragments were randomly divided into six groups (n=10, each one received one bleaching session with five hydrogen peroxide gel applications of 8 min, activated with hybrid light, diode laser/blue LED (HL or diode laser/violet LED (VHL (experimental: Control (C; 35% Total Blanc Office (TBO35HL; 35% Lase Peroxide Sensy (LPS35HL; 25% Lase Peroxide Sensy II (LPS25HL; 15% Lase Peroxide Lite (LPL15HL; and 10% hydrogen peroxide (experimental (EXP10VHL. pH values were determined by a pHmeter at the initial and final time periods. Specimens were stored, subjected to simulated brushing cycles, and the superficial wear was determined (μm. ANOVA and Tukey´s tests were applied (α=0.05. Results The pH showed a slight decrease, except for Group LPL15HL. Group LPS25HL showed the highest degree of wear, with and without etching. Conclusion There was a decrease from the initial to the final pH. Different bleaching gels were able to increase the surface wear values after simulated brushing. Acid etching before bleaching increased surface wear values in all groups.

  10. A comparative study of shear bond strength of orthodontic bracket after acid-etched and Er:YAG treatment on enamel surface

    Science.gov (United States)

    Leão, Juliana C.; Mota, Cláudia C. B. O.; Cassimiro-silva, Patricia F.; Gomes, Anderson S. L.

    2016-02-01

    This study aimed to evaluate the shear bond strength (SBS) of teeth prepared for orthodontic bracket bonding with 37% phosphoric acid and Er:YAG laser. Forty bovine incisors were divided into two groups. In Group I, the teeth were conditioned with 37% phosphoric acid and brackets were bonded with Transbond XT; in Group II, the teeth were irradiated with Er:YAG and bonding with Transbond XT. After SBS test, the adhesive remnant index was determined. Adhesion to dental hard tissues after Er:YAG laser etching was inferior to that obtained after acid etching but exceeded what is believed to be clinically sufficient strength, and therefore can be used in patients.

  11. Bonding to enamel/dentin etched with phosphoric and hydrofluoric acids.

    Science.gov (United States)

    Barghi, Nassar; Covington, Kendra; Fischer, Dan E; Herbold, Edward T

    2004-10-01

    Repairing porcelain intraorally allows clinicians to provide their patients with a conservative means of treating fractured or debonded restorations. This requires, however, the etching of both porcelain and tooth structure with etching solutions. It is thus relevant to understand the effect that different etching procedures have on shear bond strengths of composite resins to both dentin and enamel structures. Based on the results of this investigation, the authors recommend isolation of tooth structures and the etching of porcelain with hydrofluoric acid.

  12. Hydrogen content in titanium and a titanium–zirconium alloy after acid etching

    Energy Technology Data Exchange (ETDEWEB)

    Frank, Matthias J.; Walter, Martin S. [Department of Biomaterials, Institute for Clinical Dentistry, University of Oslo, P.O. Box 1109, Blindern, NO-0317 Oslo (Norway); Institute of Medical and Polymer Engineering, Chair of Medical Engineering, Technische Universität München, Boltzmannstrasse 15, 85748 Garching (Germany); Lyngstadaas, S. Petter [Department of Biomaterials, Institute for Clinical Dentistry, University of Oslo, P.O. Box 1109, Blindern, NO-0317 Oslo (Norway); Wintermantel, Erich [Institute of Medical and Polymer Engineering, Chair of Medical Engineering, Technische Universität München, Boltzmannstrasse 15, 85748 Garching (Germany); Haugen, Håvard J., E-mail: h.j.haugen@odont.uio.no [Department of Biomaterials, Institute for Clinical Dentistry, University of Oslo, P.O. Box 1109, Blindern, NO-0317 Oslo (Norway)

    2013-04-01

    Dental implant alloys made from titanium and zirconium are known for their high mechanical strength, fracture toughness and corrosion resistance in comparison with commercially pure titanium. The aim of the study was to investigate possible differences in the surface chemistry and/or surface topography of titanium and titanium–zirconium surfaces after sand blasting and acid etching. The two surfaces were compared by X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, scanning electron microscopy and profilometry. The 1.9 times greater surface hydrogen concentration of titanium zirconium compared to titanium was found to be the major difference between the two materials. Zirconium appeared to enhance hydride formation on titanium alloys when etched in acid. Surface topography revealed significant differences on the micro and nanoscale. Surface roughness was increased significantly (p < 0.01) on the titanium–zirconium alloy. High-resolution images showed nanostructures only present on titanium zirconium. - Highlights: ► TiZr alloy showed increased hydrogen levels over Ti. ► The alloying element Zr appeared to catalyze hydrogen absorption in Ti. ► Surface roughness was significantly increased for the TiZr alloy over Ti. ► TiZr alloy revealed nanostructures not observed for Ti.

  13. Histological structures and acidic etching sensitivities of the enamels at the occlusal pit parts in the deciduous and permanent teeth

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Masashi [Department of Dental Hygiene, Nippon Dental University College at Niigata, Niigata 951-8580 (Japan)]. E-mail: masashi@ngt.ndu.ac.jp; Zheng, Jinhua [Department of Oral Anatomy, School of Dentistry at Niigata, Nippon Dental University, Niigata 951-8580 (Japan); Mori, Kazuhisa [Department of Oral Surgery, School of Dentistry at Niigata, Nippon Dental University, Niigata 951-8580 (Japan); Mataga, Izumi [Department of Oral Surgery, School of Dentistry at Niigata, Nippon Dental University, Niigata 951-8580 (Japan); Kobayashi, Kan [Department of Oral Anatomy, School of Dentistry at Niigata, Nippon Dental University, Niigata 951-8580 (Japan)

    2006-05-15

    The purpose of this study is to compare the histological structures and acidic etching sensitivities of the enamels at the occlusal pit parts between the deciduous molars and permanent molars. They were observed by the polarizing and scanning electron microscopies. The enamel rods were less made slender by EDTA etching and the outlines of the apatite crystals, constituting the enamel rods, were clearer at the occlusal pit part of the deciduous molar than that of the permanent molar in reverse of that at the cusp part. It is thought that the enamel at the occlusal pit part of the permanent molar is more easily decayed by the dental caries than that of the deciduous molar because the former is more easily decayed by the acidic etching than the latter in reverse at the cusp part. It is considered that the thin superficialmost layer of the enamel at the occlusal pit part of the permanent molar has originally higher degree of resistance to the dental caries.

  14. Growth of carbon nanotubes on Si/SiO{sub 2} wafer etched by hydrofluoric acid under different etching durations

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Lling-Lling [Chemical Engineering Discipline, School of Engineering, Monash University, Jalan Lagoon Selatan, 46150 Bandar Sunway, Selangor (Malaysia); Chai, Siang-Piao, E-mail: chai.siang.piao@monash.edu [Chemical Engineering Discipline, School of Engineering, Monash University, Jalan Lagoon Selatan, 46150 Bandar Sunway, Selangor (Malaysia); Mohamed, Abdul Rahman [School of Chemical Engineering, Universiti Sains Malaysia, Engineering Campus, Seri Ampangan, 14300 NibongTebal, Pulau Pinang (Malaysia)

    2012-05-15

    The preparation of SiO{sub 2} nanoparticles for the metal-free catalyst growth of carbon nanotubes (CNTs) was investigated. SiO{sub 2} nanoparticles were generated by etching Si/SiO{sub 2} wafers with 48-50% hydrofluoric acid. Etching duration was varied to study its effects on the generation of the SiO{sub 2} nanoparticles. Atomic force microscopy characterization showed that etching at 1 min was the most effective considering the significant numbers of SiO{sub 2} nanoparticles obtained under this condition. The wafer etched at 1 min after chemical vapor deposition at 900 Degree-Sign C for 1 h demonstrated a low I{sub D}/I{sub G} from Raman analysis which establishes that CNTs with highly ordered graphitic structures were grown. Raman analysis also showed a strong radial breathing mode peak in the low-frequency range for the substrate following the 1 min etching process after the reaction.

  15. Nanostructural effect of acid-etching and fluoride application on human primary and permanent tooth enamels

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, Youjin [Department of Biomedical Engineering and Healthcare Industry Research Institute, College of Medicine, Kyung Hee University, Seoul (Korea, Republic of); Choi, Samjin [Department of Biomedical Engineering and Healthcare Industry Research Institute, College of Medicine, Kyung Hee University, Seoul (Korea, Republic of); Department of Orthodontics, College of Dental Medicine, Kyung Hee University, Seoul (Korea, Republic of); Kim, So Jung [Department of Pediatric Dentistry, College of Dental Medicine, Kyung Hee University, Seoul (Korea, Republic of); Park, Hun-Kuk, E-mail: sigmoidus@khu.ac.kr [Department of Biomedical Engineering and Healthcare Industry Research Institute, College of Medicine, Kyung Hee University, Seoul (Korea, Republic of); Program of Medical Engineering, Kyung Hee University, Seoul (Korea, Republic of)

    2012-07-01

    This study examined the nanostructural effects of fluoride application and the acid-etching time with respect to the time elapsed after fluoride application on the primary and permanent tooth enamel layers using atomic force microscopy (AFM) and scanning electron microscopy (SEM). 192 non-carious teeth were assigned to sixteen experimental groups (n = 12) including primary (1 to 8) and permanent (9 to 16) teeth, based on the timing of acid-etching with 37% phosphoric acid after an acidulated phosphate fluoride (APF) pre-treatment. The APF pre-treatment led to a decrease in surface roughness in both the primary and permanent teeth. After the APF treatment, the roughness in both primary and permanent teeth increased with the time elapsed. An acid-etching time of 40 s led to increased nanostructural changes in the enamel surfaces compared to the conventional acid-etching time of 20 s. This acid-etching process led to a higher roughness changes in the primary teeth than in the permanent teeth. To obtain proper enamel adhesion of a sealant after APF pre-treatment, it is important to apply acid-etching two weeks after pre-treatment. In addition, the acid-etching time should be prolonged to apply etching more quickly than two weeks, regardless of the primary and permanent teeth. Highlights: Black-Right-Pointing-Pointer APF pre-treatment led to decreased surface roughness in the enamel. Black-Right-Pointing-Pointer After APF treatment, the more roughness increased with increasing time elapsed. Black-Right-Pointing-Pointer Acid-etching should be performed two weeks after fluoride application.

  16. Rolled-Up Nanotech: Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers

    Directory of Open Access Journals (Sweden)

    Costescu Ruxandra

    2009-01-01

    Full Text Available Abstract The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up InGaAs/GaAs bilayers was studied. For thicknesses of AlAs below 10 nm, there were two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The “etch suppression” area is well defined by the illumination spot, a feature that can be used to create heterogeneously etched regions with a high degree of control, shown here on patterned samples. Together with the studied self-limitation effect, the technique offers a way to determine the position of rolled-up micro- and nanotubes independently from the predefined lithographic pattern.

  17. Rolled-Up Nanotech: Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers

    Science.gov (United States)

    Costescu, Ruxandra M.; Deneke, Christoph; Thurmer, Dominic J.; Schmidt, Oliver G.

    2009-12-01

    The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up InGaAs/GaAs bilayers was studied. For thicknesses of AlAs below 10 nm, there were two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The “etch suppression” area is well defined by the illumination spot, a feature that can be used to create heterogeneously etched regions with a high degree of control, shown here on patterned samples. Together with the studied self-limitation effect, the technique offers a way to determine the position of rolled-up micro- and nanotubes independently from the predefined lithographic pattern.

  18. Resin Adaptation of Radicular Dentin Tubules after Endodontic Instrumentation and Acid Etching.

    Science.gov (United States)

    1983-02-01

    the manuscript. DISCLAIMERS The statements, opinions, and advertisements in the Journal of Endodontics are solely those of the individual authors...I RD-Ai26 872 RESIN ADAPTATION OF RADICULAR DENTIN TUBULES AFTER / I ENDODONTIC INSTRUMENTATION AND ACID ETCHING(U) WALTER I REED ARMY INST OF...Adaptation to Radicular Dentin Tubules SbisoofpeAfter Endodontic Instrumentation and Acid Etching 1982-1983 6. PERFORMING ORG. REPORTNUMBER -, AUTHOR(a) S

  19. Study of wet etching thin films of indium tin oxide in oxalic acid by monitoring the resistance

    Energy Technology Data Exchange (ETDEWEB)

    Mammana, Suelene S., E-mail: ssmammana@abinfo.com.br [Brazilian Association for Informatics - ABINFO, Rua Deusdete Martins Gomes 163, CEP 13084-723, Campinas, SP (Brazil); Greatti, Alessandra; Luiz, Francis H.; Costa, Francisca I. da; Mammana, Alaide P. [Brazilian Association for Informatics - ABINFO, Rua Deusdete Martins Gomes 163, CEP 13084-723, Campinas, SP (Brazil); Calligaris, Guilherme A.; Cardoso, Lisandro P. [Institute of Physics Gleb Wataghin, State University of Campinas-UNICAMP, CEP 13083-859, Campinas, SP (Brazil); Mammana, Carlos I.Z.; Engelsen, Daniel den [Brazilian Association for Informatics - ABINFO, Rua Deusdete Martins Gomes 163, CEP 13084-723, Campinas, SP (Brazil)

    2014-09-30

    We describe a study on wet etching of thin films of indium tin oxide (ITO) using a simple method by monitoring the resistance of the thin film in aqueous solutions of oxalic acid and hydrochloric acid. Generally three different regimes can be distinguished during etching ITO in acids: (1) initial etching, which is slow, (2) a fast etching phase and (3) slow etching stage at the end. These regimes are explained in terms of a porosity–roughness model. This porosity model has been confirmed largely by X-ray reflection measurements at grazing incidence, roughness measurements and scanning electron microscopy (SEM). A reliable method for monitoring the resistance during etching has been developed. This method is based on a 2-strips measuring jig with a very low series contact resistance. The activation energy of the etch rate of ITO films was found to be 80 ± 5 kJ/mol for oxalic acid and 56 ± 5 kJ/mol for HCl. SEM analyses in the final stage of the etching process indicate an enrichment of Sn in the residual film material. These observations are explained in terms of preferential etching of In{sub 2}O{sub 3}. X-ray analyses showed that the density of the ITO film decreased by etching. By adding ferric chloride to the oxalic acid solution we could accelerate the etch rate substantially. - Highlights: • Etching of indium tin oxide thin films by monitoring the resistance. • Oxalic acid has 2–3 times lower etch rate than concentrated HCl. • The etch rate in oxalic acid can be accelerated substantially by adding FeCl{sub 3}. • The proposed etching model for indium tin oxide was confirmed by X-ray analysis and scanning electron microscopy. • Energy Dispersive X-ray Spectroscopy analyses showed preferential etching of In{sub 2}O{sub 3}, enriching the film with SnO{sub 2}.

  20. Comparison of shear bond strength of reattached incisor fragment using Er,Cr:YSGG laser etching and conventional acid etching: An in vitro study

    Science.gov (United States)

    Kumar, Gyanendra; Goswami, Mridula; Dhillon, Jatinder Kaur

    2016-01-01

    Aim: The aim of this invitro study is to evaluate the shear bond strength of reattached fractured incisor fragments using Er,Cr:YSGG laser and conventional acid etching without additional tooth preparation. Materials and methods: Forty extracted human teeth were divided in two groups of 20 each (Groups A and B). In Group A, fractured surface was treated by an Er, Cr: YSGG laser system (Waterlase MD, Biolase Technology Inc., San Clemente, CA, USA) operating at a wavelength of 2,780 nm and frequency of 20 Hz. In Group B, fractured surface was etched using 37% phosphoric acid (Scotchbond, 3M). In both the groups, further subdivision with 10 sample each was made based on horizontal and oblique fracture. After laser or acid etching, all the samples were reattached using flowable composite resin and light cured. The samples were tested for shear bond strength. Results: Mean shear bond strength for Group A (94.70±39.158) was lower as compared to Group B (121.25±49.937), although the difference was not statistically significant(p value=0.121). Similarly no statistical significant difference was observed amongst the subgroups. (p>0.05) Conclusion: Er,Cr:YSGG laser etching in reattachment of fractured incisor fragment is a good alternative to conventional acid etching. Er,Cr:YSGG showed comparable efficiency in rebonding of fractured teeth fragment as acid etching. PMID:27721563

  1. Evaluating EDTA as a substitute for phosphoric acid-etching of enamel and dentin.

    Science.gov (United States)

    Imbery, Terence A; Kennedy, Matthew; Janus, Charles; Moon, Peter C

    2012-01-01

    Matrix metalloproteinases (MMPs) are proteolytic enzymes released when dentin is acid-etched. The enzymes are capable of destroying unprotected collagen fibrils that are not encapsulated by the dentin adhesive. Chlorhexidine applied after etching inhibits the activation of released MMPs, whereas neutral ethylenediamine tetra-acetic acid (EDTA) prevents the release of MMPs. The purpose of this study was to determine if conditioning enamel and dentin with EDTA can be a substitute for treating acid-etching enamel and dentin with chlorhexidine. A column of composite resin was bonded to enamel and dentin after conditioning. Shear bond strengths were evaluated after 48 hours and after accelerated aging for three hours in 12% sodium hypochlorite. Shear bond strengths ranged from 15.6 MP a for accelerated aged EDTA enamel specimens to 26.8 MPa for dentin conditioned with EDTA and tested after 48 hours. A three-way ANOVA and a Tukey HSD test found statistically significant differences among the eight groups and the three independent variables (P EDTA was successfully substituted for phosphoric acid-etched enamel and dentin treated with chlorhexidine. Interactions of conditioning agent and aging were significant for dentin but not for enamel. In an effort to reduce the detrimental effects of MMPs, conditioning enamel and dentin with EDTA is an alternative to treating acid-etched dentin and enamel with chlorhexidine.

  2. Instrumentation With Ultrasonic Scalers Facilitates Cleaning of the Sandblasted and Acid-Etched Titanium Implants.

    Science.gov (United States)

    Park, Jun-Beom; Lee, Sung-Hoon; Kim, NamRyang; Park, Seojin; Jin, Seong-Ho; Choi, Bong-Kyu; Kim, Kack-Kyun; Ko, Youngkyung

    2015-08-01

    Mechanical instrumentation is widely used to debride dental implants, but this may alter the surface properties of titanium, which in turn may influence bacterial adhesion and make it more difficult to remove the biofilm. This in vitro study was performed (1) to assess the amount of biofilm formation on a sand-blasted and acid-etched titanium fixture treated with ultrasonic scalers with metal, plastic, and carbon tips and (2) to evaluate how this treatment of titanium surfaces affects implant cleaning by brushing with dentifrice. The titanium fixtures were treated with various ultrasonic scaler tips, and surface roughness parameters were measured by confocal microscopy. Biofilm was formed on the treated fixtures by using pooled saliva from 10 subjects, and the quantity of the adherent bacteria was compared with crystal violet assay. The fixture surfaces with biofilm were brushed for total of 30 seconds with a toothbrush with dentifrice. The bacteria remaining on the brushed fixture surfaces were quantified by scanning electron microscopy. Surface changes were evident, and the changes of the surfaces were more discernible when metal tips were used. A statistically significant decrease in roughness value (arithmetic mean height of the surface) was seen in the 2 metal-tip groups and the single plastic-tip group. After brushing with dentifrice, the treated surfaces in all the treatment groups showed significantly fewer bacteria compared with the untreated surfaces in the control group, and the parts of the surfaces left untreated in the test groups. Within the limits of this study, treatment of titanium fixture surfaces with ultrasonic metal, plastic, or carbon tips significantly enhanced the bacterial removal efficacy of brushing. Thorough instrumentation that smooths the whole exposed surface may facilitate maintenance of the implants.

  3. Effect of self-etching primer vs phosphoric acid etchant on bonding to bur-prepared dentin.

    Science.gov (United States)

    Ogata, M; Harada, N; Yamaguchi, S; Nakajima, M; Tagami, J

    2002-01-01

    This study evaluated the effect of dentin conditioner on tensile bond strength to dentin prepared with different types of burs. A self-etching primer system, Mac-Bond II (MB, Tokuyama Dental) and a phosphoric acid etching system, Single Bond (SB, 3M) were used for conditioning. Twenty-four extracted intact human molars were ground flat to expose occlusal dentin. After the dentin surfaces were polished with #600 SiC paper, the teeth were randomly divided into a control group and three experimental groups according to the bur grits used: #600 SiC paper only as the control, fine cut steel bur (SB600), crosscut steel bur (SB703) and regular grit diamond bur (DB) mounted in a dental handpiece utilizing water cooling. The dentin surfaces were treated with one of two adhesive systems, then composite buildups were done with Clearfil AP-X (Kuraray Medical). After soaking the bond specimens for 24 hours in 37 degrees C water, multiple vertical serial sections (0.7 mm thick, 7-8 slices per one tooth) were made, trimmed to form an hour-glass shape with a 1.0 mm2 cross-section and tensile bond strengths were determined at a crosshead speed of 1 mm/minute. Statistical analysis was made using one and two-way ANOVA and Fisher's PLSD test (pbond strength (TBS) among the groups that received bur preparation, and there were no statistical differences among SB600, SB703 and the control. For SB, the TBS of SB703 was the highest, and there were no statistical differences among the other groups and the control. The influence of the method used to prepare dentin for micro-tensile bond strength testing was dependent on the adhesive system used.

  4. Effect of acid etching of glass ionomer cement surface on the microleakage of sandwich restorations.

    Science.gov (United States)

    Bona, Alvaro Della; Pinzetta, Caroline; Rosa, Vinícius

    2007-06-01

    The purposes of this study were to evaluate the sealing ability of different glass ionomer cements (GICs) used for sandwich restorations and to assess the effect of acid etching of GIC on microleakage at GIC-resin composite interface. Forty cavities were prepared on the proximal surfaces of 20 permanent human premolars (2 cavities per tooth), assigned to 4 groups (n=10) and restored as follows: Group CIE - conventional GIC (CI) was applied onto the axial and cervical cavity walls, allowed setting for 5 min and acid etched (E) along the cavity margins with 35% phosphoric acid for 15 s, washed for 30 s and water was blotted; the adhesive system was applied and light cured for 10 s, completing the restoration with composite resin light cured for 40 s; Group CIN - same as Group CIE, except for acid etching of the CI surface; Group RME - same as CIE, but using a resin modified GIC (RMGIC); Group RMN - same as Group RME, except for acid etching of the RMGIC surface. Specimens were soaked in 1% methylene blue dye solution at 24 degrees C for 24 h, rinsed under running water for 1 h, bisected longitudinally and dye penetration was measured following the ISO/TS 11405-2003 standard. Results were statistically analyzed by Kruskal-Wallis and chi-square tests (a=0.05). Dye penetration scores were as follow: CIE - 2.5; CIN - 2.5; RME - 0.9; and RMN - 0.6. The results suggest that phosphoric acid etching of GIC prior to the placement of composite resin does not improve the sealing ability of sandwich restorations. The RMGIC was more effective in preventing dye penetration at the GIC-resin composite-dentin interfaces than CI.

  5. Effect of acid etching of glass ionomer cement surface on the microleakage of sandwich restorations

    Directory of Open Access Journals (Sweden)

    Álvaro Della Bona

    2007-06-01

    Full Text Available The purposes of this study were to evaluate the sealing ability of different glass ionomer cements (GICs used for sandwich restorations and to assess the effect of acid etching of GIC on microleakage at GIC-resin composite interface. Forty cavities were prepared on the proximal surfaces of 20 permanent human premolars (2 cavities per tooth, assigned to 4 groups (n=10 and restored as follows: Group CIE - conventional GIC (CI was applied onto the axial and cervical cavity walls, allowed setting for 5 min and acid etched (E along the cavity margins with 35% phosphoric acid for 15 s, washed for 30 s and water was blotted; the adhesive system was applied and light cured for 10 s, completing the restoration with composite resin light cured for 40 s; Group CIN - same as Group CIE, except for acid etching of the CI surface; Group RME - same as CIE, but using a resin modified GIC (RMGIC; Group RMN - same as Group RME, except for acid etching of the RMGIC surface. Specimens were soaked in 1% methylene blue dye solution at 24ºC for 24 h, rinsed under running water for 1 h, bisected longitudinally and dye penetration was measured following the ISO/TS 11405-2003 standard. Results were statistically analyzed by Kruskal-Wallis and chi-square tests (a=0.05. Dye penetration scores were as follow: CIE - 2.5; CIN - 2.5; RME - 0.9; and RMN - 0.6. The results suggest that phosphoric acid etching of GIC prior to the placement of composite resin does not improve the sealing ability of sandwich restorations. The RMGIC was more effective in preventing dye penetration at the GIC-resin composite-dentin interfaces than CI.

  6. The initial behaviour of freshly etched copper in modertely acid, aerated chloride solutions

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers; Jaskula, M.; Chorkendorff, Ib;

    2002-01-01

    When freshly etched samples of various types of copper were exposed in moderately acid, aerated chloride solutions, two phenomena were observed. First the corrosion potential and the pH of the solution decreased over a shorter time, then the potential increased over a long period (600-1500 min), ...

  7. Acid-etched microtexture for enhancement of bone growth into porous-coated implants.

    Science.gov (United States)

    Hacking, S A; Harvey, E J; Tanzer, M; Krygier, J J; Bobyn, J D

    2003-11-01

    We designed an in vivo study to determine if the superimposition of a microtexture on the surface of sintered titanium beads affected the extent of bone ingrowth. Cylindrical titanium intramedullary implants were coated with titanium beads to form a porous finish using commercial sintering techniques. A control group of implants was left in the as-sintered condition. The test group was etched in a boiling acidic solution to create an irregular surface over the entire porous coating. Six experimental dogs underwent simultaneous bilateral femoral intramedullary implantation of a control implant and an acid etched implant. At 12 weeks, the implants were harvested in situ and the femora processed for undecalcified, histological examination. Eight transverse serial sections for each implant were analysed by backscattered electron microscopy and the extent of bone ingrowth was quantified by computer-aided image analysis. The extent of bone ingrowth into the control implants was 15.8% while the extent of bone ingrowth into the etched implants was 25.3%, a difference of 60% that was statistically significant. These results are consistent with other research that documents the positive effect of microtextured surfaces on bone formation at an implant surface. The acid etching process developed for this study represents a simple method for enhancing the potential of commonly available porous coatings for biological fixation.

  8. Phosphoric acid-etching promotes bond strength and formation of acid-base resistant zone on enamel.

    Science.gov (United States)

    Li, N; Nikaido, T; Alireza, S; Takagaki, T; Chen, J-H; Tagami, J

    2013-01-01

    This study examined the effect of phosphoric acid (PA) etching on the bond strength and acid-base resistant zone (ABRZ) formation of a two-step self-etching adhesive (SEA) system to enamel. An etch-and-rinse adhesive (EAR) system Single Bond (SB) and a two-step SEA system Clearfil SE Bond (SE) were used. Human teeth were randomly divided into four groups according to different adhesive treatments: 1) SB; 2) SE; 3) 35% PA etching→SE primer→SE adhesive (PA/SEp+a); (4) 35% PA etching→SE adhesive (PA/SEa). Microshear bond strength to enamel was measured and then statistically analyzed using one-way analysis of variance and the Tukey honestly significant difference test. The failure mode was recorded and analyzed by χ( 2 ) test. The etching pattern of the enamel surface was observed with scanning electron microscope (SEM). The bonded interface was exposed to a demineralizing solution (pH=4.5) for 4.5 hours and then 5% sodium hypochlorite with ultrasonication for 30 minutes. After argon-ion etching, the interfacial ultrastructure was observed using SEM. The microshear bond strength to enamel of the SE group was significantly lower (p<0.05) than that of the three PA-etched groups, although the latter three were not significantly different from one another. The ABRZ was detected in all the groups. In morphological observation, the ABRZ in the three PA-etched groups were obviously thicker compared with the SE group with an irregular wave-shaped edge.

  9. Assessment of antibacterial activity of self-etching dental adhesive systems: An in vitro study

    Directory of Open Access Journals (Sweden)

    Hegde Mithra

    2008-01-01

    Full Text Available Aim: To evaluate and compare the antibacterial activity of polymerized, two-step, self-etching and one-step, self-etching adhesive systems by using the direct contact test after one, seven, and fourteen days. Materials and Methods: The direct contact test was used to evaluate the antibacterial activity of Clearfil Protect Bond, Adper SE Plus, Clearfil SE Bond, and Adper Easy One on Streptococcus mutans after aging the samples in phosphate-buffered saline for one, seven, and fourteen days. Statistical analysis included the one-way Anova and Tukey′s multiple comparison tests. Results: Among the tested materials, Clearfil Protect Bond exhibited an antibacterial effect for seven days when in contact with S. mutans . None of the adhesive systems exhibited any antibacterial effect after 14 days. Conclusion: The incorporation of antibacterial agents into dentine-bonding agents may become an essential factor in inhibiting residual bacteria in the cavity following a cavity disinfection procedure, and it could be recommended in situations where total disinfection of cavity is not accomplished due to lack of accessibility.

  10. Effect of EDTA and Phosphoric Acid Pretreatment on the Bonding Effectiveness of Self-Etch Adhesives to Ground Enamel

    Science.gov (United States)

    Ibrahim, Ihab M.; Elkassas, Dina W.; Yousry, Mai M.

    2010-01-01

    Objectives: This in vitro study determined the effect of enamel pretreatment with phosphoric acid and ethylenediaminetetraacetic acid (EDTA) on the bond strength of strong, intermediary strong, and mild self-etching adhesive systems. Methods: Ninety sound human premolars were used. Resin composite cylinders were bonded to flat ground enamel surfaces using three self-etching adhesive systems: strong Adper Prompt L-Pop (pH=0.9–1.0), intermediary strong AdheSE (pH=1.6–1.7), and mild Frog (pH=2). Adhesive systems were applied either according to manufacturer instructions (control) or after pretreatment with either phosphoric acid or EDTA (n=10). After 24 hours, shear bond strength was tested using a universal testing machine at a cross-head speed of 0.5 mm/minute. Ultra-morphological characterization of the surface topography and resin/enamel interfaces as well as representative fractured enamel specimens were examined using scanning electron microscopy (SEM). Results: Neither surface pretreatment statistically increased the mean shear bond strength values of either the strong or the intermediary strong self-etching adhesive systems. However, phosphoric acid pretreatment significantly increased the mean shear bond strength values of the mild self-etching adhesive system. SEM examination of enamel surface topography showed that phosphoric acid pretreatment deepened the same etching pattern of the strong and intermediary strong adhesive systems but converted the irregular etching pattern of the mild self-etching adhesive system to a regular etching pattern. SEM examination of the resin/enamel interface revealed that deepening of the etching pattern was consistent with increase in the length of resin tags. EDTA pretreatment had a negligible effect on ultra-morphological features. Conclusions: Use of phosphoric acid pretreatment can be beneficial with mild self-etching adhesive systems for bonding to enamel. PMID:20922162

  11. In vitro short-term bonding performance of zirconia treated with hot acid etching and primer conditioning etching and primer conditioning.

    Science.gov (United States)

    Xie, Haifeng; Chen, Chen; Dai, Wenyong; Chen, Gang; Zhang, Feimin

    2013-01-01

    This study aimed to investigate and compare the resin bond strengths of zirconia conditioned as follows: alumina sandblasting; alumina sandblasting+application of 10-MDP-containing primer; alumina sandblasting+application of Z-Prime Plus or Metal/Zirconia Primer (new zirconia primers); tribochemical silica coating+silanization; hot acid etching in three different combinations [H2SO4/(NH4)2SO4, HF/HNO3, H2SO4/HF/HNO3]+application of 10-MDP-containing primer. Shear bond strengths (SBS) after water storage for 24 h and 40 days were measured to assess resin bonding performance. Surface and chemical properties of conditioned zirconia surfaces and primers were characterized using scanning electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, and atomic force microscopy. Surface roughness ranked in descending order was: hot acid etching > tribochemical silica coating > alumina sandblasting. Combination of tribochemical silica coating and silanization showed the highest initial SBS (12.46±2.13 MPa) (P<0.01). Etching with H2SO4/(NH4)2SO4 (13.15±3.24 MPa) and HF/HNO3 (13.48±2.15 MPa) showed significantly better bond durability (P<0.01). Hot acid etching seemed to be a promising surface roughening treatment to improve resin-zirconia bonding.

  12. 37% Phosphoric Acid Induced Stronger Matrix Metalloproteinase-8 Expression of the Dental Pulp than 19% Ethylene Diamine Tetraacetic Acid

    Directory of Open Access Journals (Sweden)

    Nadie Fatimatuzzahro

    2014-11-01

    Full Text Available Etching agents such as ethylene diamine tetraacetic acid (EDTA and phosphoric acid which are widely used in adhesive restoration system aimed to increase for retention of restorative materials, may act a chemical irritant that induce inflammation of dental pulp. Inflammation is a body response against irritant and infectious agents. Matrix metalloproteinase-8, the major collagenolytic enzyme, degrades collagen type 1. This enzyme is expressed in low level in normal condition, however, the expression will increase during inflammation. The purpose of the present research was to study the effect of 19% EDTA and 37% phosphoric acid application as an etching agents on the MMP-8 expression of dental pulp. Forty-five male Sprague Dawley rats were divided into 3 groups. Cavity preparation was made on the occlusal surface of maxillary first molar using a round diamond bur. 19% EDTA, 37% phosphoric acid, and distilled water were applied on the surface of the cavity of the teeth in group I, II, and III subsequently. The cavity then filed by glass ionomer cements. The rats were sacrified at 1, 3, 5, 7, and 14 days after the treatment (n=3 for each day. The specimens were then processed histologically. Immunohistochemical (IHC analysis was performed using rabbit anti rat MMP-8 polyclonal antibody to examine MMP-8 expression and HE (Hematoxylen Eosin staining to observe the number of macrophages. The results showed 37% phosphoric acid application induced stronger expression of MMP-8 and higher number of macrophages than 19% EDTA. The strongest expression of MMP-8 seems on 5 days after the treatment where the highest number of macrophages were also found.

  13. Marginal microleakage in vitro study on class V cavities prepared with Er:YAG laser and etched with acid or etched with Er:YAG laser and acid; Estudo in vitro da microinfiltracao marginal em cavidades classe V preparadas com laser de Er:YAG e condicionadas com acido ou com laser de Er:YAG e acido

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, Henrique Dutra Simoes

    2001-07-01

    Microleakage at the interface between the teeth and the restorative materials remains a problem with composite resin restorations. Microleakage at the gingival margins of class V cavities restorations still challenge as they are usually placed in dentin and/or cementum. Previous studies have shown that the cavity preparation with Er:YAG laser is possible. It has been reported that Er:YAG laser has ability to create irregular surface providing micromechanical retention for adhesive dental restorative materials and to improve marginal sealing. The purpose of this in vitro study was to evaluate the marginal microleakage on class V cavities prepared with Er:YAG laser and etched with acid or with Er:YAG laser and acid, in compared to those prepared and etched conventionally. Thirty human molars were divided into three groups, namely: group I - prepared with Er:YAG laser (KaVo KEY Laser II - Germany) and etched with 37% phosphoric acid; group II - prepared with Er:YAG laser and etched with Er:YAG laser and 37% phosphoric acid; group III (control group) - prepared with high speed drill and etched with 37% phosphoric acid. All cavities were treated with same adhesive system (Single Bond - 3M) and restored with the composite resin (Z100 - 3M), according to the manufacturer's instructions. The specimens were stored at 37 deg C in water for 24 hours, polished with Sof-Lex discs (3M), thermally stressed, sealed with a nail polish coating except for the area of the restoration and 1 mm around it, and immersed in a 50% aqueous solution of silver nitrate for 24 hours. After that, the specimens were rinsed in water, soaked in a photodeveloping solution and exposed to a fluorescent light for 8 hours. The teeth were embedded in an autopolymerizing resin and sectioned longitudinally using a diamond saw microtome under running water. The sections were photographed. The microleakage at the occlusal cavity and at the gingival margins of each specimen was evaluated with scores (0

  14. Effect of acid-etching on remineralization of enamel white spot lesions.

    Science.gov (United States)

    Al-Khateeb, S; Exterkate, R; Angmar-Månsson, B; ten Cate, J M; ten Cate, B

    2000-02-01

    This in vitro study aimed at investigating whether full remineralization would occur in white spot lesions when the surface porosity was increased by acid-etching. The effect of fluoride was also investigated. Enamel blocks with in vitro produced white spot lesions were used. Group A was exposed to a remineralizing solution only. In group B, the lesions were etched with 35% phosphoric acid for 30 s, then treated as in group A. Group C was treated as group A + daily treatment with a fluoride toothpaste slurry (1,000 ppm) for 5 min. Group D was treated as group B + the daily fluoride treatment of group C. The remineralization was measured weekly with Quantitative Light-induced Fluorescence during the experimental period. After 10 weeks of remineralization, mineral profiles were assessed with transverse microradiography. The enamel fluorescence was partly regained. There were significant differences in the lesion depth, mineral content at the surface layer, and integrated mineral loss between the groups. Addition of fluoride accelerated the remineralization only in the beginning; in later stages the process leveled out and even reached a plateau in all the groups. It was concluded that full remineralization was not achieved by etching, by the addition of fluoride, nor by the combination of both treatments in this in vitro study.

  15. Shear bond strength and debonding characteristics of metal and ceramic brackets bonded with conventional acid-etch and self-etch primer systems: An in-vivo study

    Science.gov (United States)

    Mirzakouchaki, Behnam; Sharghi, Reza; Shirazi, Samaneh; Moghimi, Mahsan; Shahrbaf, Shirin

    2016-01-01

    Background Different in-vitro studies have reported various results regarding shear bond strength (SBS) of orthodontic brackets when SEP technique is compared to conventional system. This in-vivo study was designed to compare the effect of conventional acid-etching and self-etching primer adhesive (SEP) systems on SBS and debonding characteristics of metal and ceramic orthodontic brackets. Material and Methods 120 intact first maxillary and mandibular premolars of 30 orthodontic patients were selected and bonded with metal and ceramic brackets using conventional acid-etch or self-etch primer system. The bonded brackets were incorporated into the wire during the study period to simulate the real orthodontic treatment condition. The teeth were extracted and debonded after 30 days. The SBS, debonding characteristics and adhesive remnant indices (ARI) were determined in all groups. Results The mean SBS of metal brackets was 10.63±1.42 MPa in conventional and 9.38±1.53 MPa in SEP system, (P=0.004). No statistically significant difference was noted between conventional and SEP systems in ceramic brackets. The frequency of 1, 2 and 3 ARI scores and debonding within the adhesive were the most common among all groups. No statistically significant difference was observed regarding ARI or failure mode of debonded specimens in different brackets or bonding systems. Conclusions The SBS of metal brackets bonded using conventional system was significantly higher than SEP system, although the SBS of SEP system was clinically acceptable. No significant difference was found between conventional and SEP systems used with ceramic brackets. Total SBS of metal brackets was significantly higher than ceramic brackets. Due to adequate SBS of SEP system in bonding the metal brackets, it can be used as an alternative for conventional system. Key words:Shear bond strength, Orthodontic brackets, Adhesive remnant index, self-etch. PMID:26855704

  16. Nitric-phosphoric acid etching effects on the surface chemical composition of CdTe thin film.

    Science.gov (United States)

    Irfan, Irfan; Ding, Huanjun; Xia, Wei; Lin, Hao; Tang, Ching W.; Gao, Yongli

    2009-03-01

    Nitric-phosphoric (NP) acid etching has been regarded as one of the most successful methods for the formation of low resistance back contact with the metal electrode in CdTe based solar cells. We report back surface chemical composition for eight different durations of NP etching of CdTe polycrystalline thin film. We studied the surfaces with x-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), inverse photoemission spectroscopy (IEPS) and atomic force microscopy (AFM). Etching dependence on the back surface composition and electronic structure was observed. Valence and conduction band shifts relative to the Fermi level of the system with different etching duration were analyzed. The sample was left in open ambient condition for three weeks and XPS data were obtained again in order to study the difference in surface chemical composition with the pristine CdTe film. Unetched and highly etched part of the sample were sputtered and the depth profile analyzed.

  17. Effect of hydrofluoric acid etching duration on the roughness and flexural strength of a lithium disilicate-based glass ceramic.

    Science.gov (United States)

    Zogheib, Lucas Villaça; Bona, Alvaro Della; Kimpara, Estevão Tomomitsu; McCabe, John F

    2011-01-01

    The aim of this study was to examine the effect of different acid etching times on the surface roughness and flexural strength of a lithium disilicate-based glass ceramic. Ceramic bar-shaped specimens (16 mm x 2 mm x 2 mm) were produced from ceramic blocks. All specimens were polished and sonically cleaned in distilled water. Specimens were randomly divided into 5 groups (n=15). Group A (control) no treatment. Groups B-E were etched with 4.9% hydrofluoric acid (HF) for 4 different etching periods: 20 s, 60 s, 90 s and 180 s, respectively. Etched surfaces were observed under scanning electron microscopy. Surface profilometry was used to examine the roughness of the etched ceramic surfaces, and the specimens were loaded to failure using a 3-point bending test to determine the flexural strength. Data were analyzed using one-way ANOVA and Tukey's test (?=0.05). All etching periods produced significantly rougher surfaces than the control group (p<0.05). Roughness values increased with the increase of the etching time. The mean flexural strength values were (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; and E=314 ± 62. HF etching significantly reduced the mean flexural strength as the etching time increased (p=0.003). In conclusion, the findings of this study showed that the increase of HF etching time affected the surface roughness and the flexural strength of a lithium disilicate-based glass ceramic, confirming the study hypothesis.

  18. Oxidation and etching behaviors of the InAs surface in various acidic and basic chemical solutions

    Science.gov (United States)

    Na, Jihoon; Lee, Seunghyo; Lim, Sangwoo

    2017-04-01

    Indium arsenide (InAs) is the candidate of choice as a new channel material for application in future technologies beyond the Si-based electronic devices because it has a much higher electron mobility than silicon. In this study, the oxidation and etching behaviors of InAs (100) in various acidic and basic solutions, such as HF, HCl, H2SO4, NaOH, KOH, and NH4OH, were investigated. In addition, the effect of pH on the oxidation and etching reactions taking place on the InAs surface was studied using solutions with a pH ranging from 1 to 13. It was observed that the oxidation of the InAs surface was hindered in acidic solutions, which was attributed to the dissolution of the oxidized surface layer. In particular, the treatment of the InAs surface using a strongly acidic solution with a pH of less than 3 produced an oxide-free surface due to the predominant etching of the InAs surface. The addition of H2O2 to the acidic solutions greatly increased the etching rate of the InAs surface, which suggests that the oxidation process is the rate-limiting step in the sequence of reactions that occur during the etching of the InAs surface in acidic solutions. The etching of InAs was suppressed in neutral solutions, which resulted in the formation of a relatively thicker oxide layer on the surface, and mild etching of the InAs surface took place in basic solutions. However, in basic solutions, the addition of H2O2 did not significantly contribute to the increase of the oxidation state of the InAs surface; thus, its effect on the etching rate of InAs was smaller than in acidic solutions.

  19. Shear Bond Strength of an Etch-and-rinse Adhesive to Er:YAG Laser- and/or Phosphoric Acid-treated Dentin

    Science.gov (United States)

    Davari, Abdolrahim; Sadeghi, Mostafa; Bakhshi, Hamid

    2013-01-01

    Background and aims. Er:YAG laser irradiation has been claimed to improve the adhesive properties of dentin; therefore, it has been proposed as an alternative to acid etching. The aim of this in vitro study was to investigate the shear bond strength of an etch-and-rinse adhesive system to dentin surfaces following Er:YAG laser and/or phosphoric acid etching. Materials and methods. The roots of 75 sound maxillary premolars were sectioned below the CEJ and the crowns were embedded in auto-polymerizing acrylic resin with the buccal surfaces facing up. The buccal surfaces were ground using a diamond bur and polished until the dentin was exposed; the samples were randomly divided into five groups (n=15) according to the surface treatment: (1) acid etching; (2) laser etching; (3) laser etching followed by acid etching; (4) acid etching followed by laser etching and (5) no acid etching and no laser etching (control group). Composite resin rods (Point 4, Kerr Co) were bonded to treated dentin surfaces with an etch-and-rise adhesive system (Optibond FL, Kerr Co) and light-cured.After storage for two weeks at 37°C and 100% humidity and then thermocycling, bond strength was measured with a Zwick Universal Testing Machine at a crosshead speed of 1 mm/min. Data was analyzed using parametric and non-parametric tests (P<0.05). Results. Mean shear bond strength for acid etching (20.1±1.8 MPa) and acid+laser (15.6±3.5 MPa) groups were significantly higher than those for laser+acid (15.6±3.5 MPa), laser etching (14.1±3.4 MPa) and control (8.1±2.1 MPa) groups. However, there were no significant differences between acid etching and acid+laser groups, and between laser+acid and laser groups. Conclusion. When the cavity is prepared by bur, it is not necessary to etch the dentin surface by Er:YAG laser following acid etching and acid etching after laser etching. PMID:23875083

  20. Improvement of enamel bond strengths for conventional and resin-modified glass ionomers: acid-etching vs. conditioning*

    Science.gov (United States)

    Zhang, Ling; Tang, Tian; Zhang, Zhen-liang; Liang, Bing; Wang, Xiao-miao; Fu, Bai-ping

    2013-01-01

    Objective: This study deals with the effect of phosphoric acid etching and conditioning on enamel micro-tensile bond strengths (μTBSs) of conventional and resin-modified glass ionomer cements (GICs/RMGICs). Methods: Forty-eight bovine incisors were prepared into rectangular blocks. Highly-polished labial enamel surfaces were either acid-etched, conditioned with liquids of cements, or not further treated (control). Subsequently, two matching pre-treated enamel surfaces were cemented together with one of four cements [two GICs: Fuji I (GC), Ketac Cem Easymix (3M ESPE); two RMGICs: Fuji Plus (GC), RelyX Luting (3M ESPE)] in preparation for μTBS tests. Pre-treated enamel surfaces and cement-enamel interfaces were analyzed by scanning electron microscopy (SEM). Results: Phosphoric acid etching significantly increased the enamel μTBS of GICs/RMGICs. Conditioning with the liquids of the cements produced significantly weaker or equivalent enamel μTBS compared to the control. Regardless of etching, RMGICs yielded stronger enamel μTBS than GICs. A visible hybrid layer was found at certain enamel-cement interfaces of the etched enamels. Conclusions: Phosphoric acid etching significantly increased the enamel μTBSs of GICs/RMGICs. Phosphoric acid etching should be recommended to etch the enamel margins before the cementation of the prostheses such as inlays and onlays, using GICs/RMGICs to improve the bond strengths. RMGICs provided stronger enamel bond strength than GICs and conditioning did not increase enamel bond strength. PMID:24190447

  1. Evaluation of human dental loss caused by carbamide peroxide bleacher compared with phosphoric acid conditioning - radioactive method; Avaliacao da perda dental humana com o uso do clareador peroxido de carbamida comparado ao condicionamento com acido fosforico - metodo radiometrico

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, Eduardo Makoto; Yousseff, Michel Nicolau [Sao Paulo Univ., SP (Brazil). Faculdade de Odontologia. Dept. de Dentistica; Saiki, Mitiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Lab. de Analise por Ativacao Neutronica

    2002-07-01

    The radiometric method was applied to the evaluation of dental loss caused by carbamide peroxide when it is applied on the surface layers of enamel and dentin tissues. Also the dental loss caused by the etching with 37% phosphoric acid procedure used in aesthetic restoration was assessed for comparison with those results obtained. The tooth samples irradiated with a P standard in a thermal neutron flux of the nuclear reactor were placed in contact with 10% carbamide peroxide or with 37% phosphoric acid solution. The radioactivity of {sup 32} P transferred from the radioactive teeth to the bleaching gel or to etching acid was measured using a Geiger Muller detector to calculate the mass of P removed in this treatment and losses were calculated after obtaining their P concentrations. Results obtained indicated that enamel and dentin exposed to carbamide peroxide bleaching agent lose phosphorus. The extent of enamel loss was smaller than that obtained for dentin. In the case of acid etching, there was no difference between the results obtained for enamel and dentin loss. Also the dentin loss obtained after a treatment of 30 applications of 10% carbamide peroxide was the same magnitude of that one application of 37% phosphoric acid. (author)

  2. Acid etching and plasma sterilization fail to improve osseointegration of grit blasted titanium implants

    DEFF Research Database (Denmark)

    Mortensen, Mikkel Saksø; Jakobsen, Stig Storgaard; Saksø, Henrik;

    2012-01-01

    Interaction between implant surface and surrounding bone influences implant fixation. We attempted to improve the bone-implant interaction by 1) adding surface micro scale topography by acid etching, and 2) removing surface-adherent pro-inflammatory agents by plasma cleaning. Implant fixation...... was evaluated by implant osseointegration and biomechanical fixation.The study consisted of two paired animal sub-studies where 10 skeletally mature Labrador dogs were used. Grit blasted titanium alloy implants were inserted press fit in each proximal tibia. In the first study grit blasted implants were...

  3. Influence of Acid Etching on Wettability of Ion-exchanged Aluminosilicate Float Glass

    Directory of Open Access Journals (Sweden)

    LI Xiaoyu

    2016-12-01

    Full Text Available The influence of acid etching time on wettability of ion-exchanged aluminosilicate float glass was investigated. The contact angle, roughness and surface composition were measured. The results show that the contact angle increases to a maximum value in the first 7 min and then decreases with the corrosion time. The main reason that cause the change of the contact angle is the change of surface roughness and the content of fluorine atom. The contact angle on the tin side is always larger than that on the air side which is caused by the tin ions on the tin side.

  4. Histologic and biomechanical evaluation of alumina-blasted/acid-etched and resorbable blasting media surfaces.

    Science.gov (United States)

    Bonfante, Estevam A; Marin, Charles; Granato, Rodrigo; Suzuki, Marcelo; Hjerppe, Jenni; Witek, Lukasz; Coelho, Paulo G

    2012-10-01

    This study evaluated the early biomechanical fixation and bone-to-implant contact (BIC) of an alumina-blasted/acid-etched (AB/AE) compared with an experimental resorbable blasting media (RBM) surface in a canine model. Higher texturization was observed for the RBM than for the AB/AE surface, and the presence of calcium and phosphorus was only observed for the RBM surface. Time in vivo and implant surface did not influence torque. For both surfaces, BIC significantly increased from 2 to 4 weeks.

  5. In situ chemical functionalization of gallium nitride with phosphonic acid derivatives during etching.

    Science.gov (United States)

    Wilkins, Stewart J; Greenough, Michelle; Arellano, Consuelo; Paskova, Tania; Ivanisevic, Albena

    2014-03-04

    In situ functionalization of polar (c plane) and nonpolar (a plane) gallium nitride (GaN) was performed by adding (3-bromopropyl) phosphonic acid or propyl phosphonic acid to a phosphoric acid etch. The target was to modulate the emission properties and oxide formation of GaN, which was explored through surface characterization with atomic force microscopy, X-ray photoelectron spectroscopy, photoluminescence (PL), inductively coupled plasma-mass spectrometry, and water contact angle. The use of (3-bromopropyl) phosphonic acid and propyl phosphonic acid in phosphoric acid demonstrated lower amounts of gallium oxide formation and greater hydrophobicity for both sample sets, while also improving PL emission of polar GaN samples. In addition to crystal orientation, growth-related factors such as defect density in bulk GaN versus thin GaN films residing on sapphire substrates were investigated as well as their responses to in situ functionalization. Thin nonpolar GaN layers were the most sensitive to etching treatments due in part to higher defect densities (stacking faults and threading dislocations), which accounts for large surface depressions. High-quality GaN (both free-standing bulk polar and bulk nonpolar) demonstrated increased sensitivity to oxide formation. Room-temperature PL stands out as an excellent technique to identify nonradiative recombination as observed in the spectra of heteroepitaxially grown GaN samples. The chemical methods applied to tune optical and physical properties of GaN provide a quantitative framework for future novel chemical and biochemical sensor development.

  6. In vitro remineralization of acid-etched human enamel with Ca 3SiO 5

    Science.gov (United States)

    Dong, Zhihong; Chang, Jiang; Deng, Yan; Joiner, Andrew

    2010-02-01

    Bioactive and inductive silicate-based bioceramics play an important role in hard tissue prosthetics such as bone and teeth. In the present study, a model was established to study the acid-etched enamel remineralization with tricalcium silicate (Ca 3SiO 5, C 3S) paste in vitro. After soaking in simulated oral fluid (SOF), Ca-P precipitation layer was formed on the enamel surface, with the prolonged soaking time, apatite layer turned into density and uniformity and thickness increasingly from 250 to 350 nm for 1 day to 1.7-1.9 μm for 7 days. Structure of apatite crystals was similar to that of hydroxyapatite (HAp). At the same time, surface smoothness of the remineralized layer is favorable for the oral hygiene. These results suggested that C 3S treated the acid-etched enamel can induce apatite formation, indicating the biomimic mineralization ability, and C 3S could be used as an agent of inductive biomineralization for the enamel prosthesis and protection.

  7. Comparison between phosphoric acid and hydrochloric acid in microabrasion technique for the treatment of dental fluorosis

    OpenAIRE

    Mahshid Mohammadi Bassir; Golnaz Bagheri

    2013-01-01

    Purpose: To compare the effectiveness of phosphoric acid (H 3 PO 4 )-pumice compound with conventional hydrochloric acid (HCl)-pumice compound in treating different severities of dental fluorosis with the microabrasion technique. Materials and Methods: Sixty-seven anterior teeth from seven patients with different severities of dental fluorosis were treated. In each patient, half of the teeth were treated with HCl-pumice compound and the other half with H 3 PO 4 -pumice compound (split-mou...

  8. Fabrication of Alumina Nanowires from Porous Alumina Membranes by Etching in Phosphoric Acid Solution

    Science.gov (United States)

    Wang, Xuehua; Li, Chengyong; Ma, Lianjiao; Cao, Hong; Zhang, Baohua

    Alumina nanowires (ANWs) with high aspect ratios were synthesized by the chemical etching of porous alumina membranes (PAMs) in phosphoric acid solution. The morphology and structure of ANWs were analyzed by SEM and XRD, respectively. The results showed that the typical features of ANWs are around 35 nm in diameter and around 20 μm in length, the crystalline structure of the ANWs was amorphous, which was in accordance with that of the PAMs. Furthermore, the morphology of the PAMs was characterized by AFM and SEM in detail. On the basis of AFM and SEM observations, a possible formation mechanism of ANWs was discussed, and the inhomogeneous of the dissolution between the triple points and the side walls was considered to be the essential factor deciding the formation of ANWs.

  9. A selective etching phenomenon on {001} faceted anatase titanium dioxide single crystal surfaces by hydrofluoric acid.

    Science.gov (United States)

    Wang, Yun; Zhang, Haimin; Han, Yanhe; Liu, Porun; Yao, Xiangdong; Zhao, Huijun

    2011-03-14

    A selective etching phenomenon on {001} faceted anatase TiO(2) single crystal surfaces by HF and associated etching mechanism are reported. Density functional theory (DFT) calculations reveal that HF stabilizes the grown {001} facets at low concentrations, but selectively destroys the grown {001} facets at high concentrations.

  10. Inactivation of Matrix-bound MMPs by Cross-linking Agents in Acid Etched Dentin

    Science.gov (United States)

    Scheffel, Débora Lopes Salles; Hebling, Josimeri; Scheffel, Régis Henke; Agee, Kelly A.; Turco, Gianluca; de Souza Costa, Carlos Alberto; Pashley, David H.

    2014-01-01

    Objectives Published TEM analysis of in vivo resin-dentin bonds shows that in 44 months almost 70% of collagen fibrils from the hybrid layer disappear. Matrix metalloproteinases (MMPs) play an important role in that process and are thought to be the main factor responsible for the solubitization of dentin collagen. Therefore, this study aimed to evaluate the inactivation of matrix-bound MMPs by carbodiimide (EDC) or proanthocyanidin (PA) both cross-linking agents, or the MMP-inhibitor, chlorhexidine (CHX), on acid-etched dentin using a simplified MMP assay method. Methods Dentin beams (1×1×6mm) were obtained from mid-coronal dentin of sound third molars and randomly divided into 6 groups (G) according to the dentin treatment: G1: Deionized water (control), G2: 0.1M EDC, G3: 0.5M EDC, G4: 0.5M EDC+35% HEMA, G5: 5% Proanthocyanidin (PA) and G6: 2% CHX. The beams were etched for 15s with 37% phosphoric acid, rinsed and then immersed for 60s in one of the treatment solutions. The total MMP activity of dentin was analyzed for 1 h by colorimetric assay (Sensolyte). Data were submitted to Wilcoxon non-parametric test and Mann-Whitney tests (p>0.05). Results All experimental cross-linking solutions significantly reduced MMP activity compared to control, except 0.1M EDC (53.6% ±16.1). No difference was observed between cross-linking agents and 2% CHX 0.5M EDC + 35% HEMA (92.3% ±8.0) was similar to 0.5M EDC (89.1% ±6.4), 5% PA (100.8% ±10.9) and 2% CHX (83.4% ±10.9). Conclusion Dentin treatment with cross-linking agents is effective to significantly reduce MMP activity. Mixing 0.5M EDC and 35% HEMA did not influence EDC inhibitor potential. PMID:23786610

  11. COMPARATIVE STUDY OF THE SHEAR BOND STRENGTH OF COMPOSITE RESIN TO DENTAL ENAMEL CONDITIONED WITH PHOSPHORIC ACID OR Nd: YAG LASER

    Directory of Open Access Journals (Sweden)

    EDUARDO Carlos de Paula

    1997-01-01

    Full Text Available This study has been focused on a comparison between the shear bond strength of a composite resin attached to dental enamel surface, after a 35% phosphoric acid etching and after a Nd:YAG laser irradiation with 165.8 J/cm2 of energy density per pulse. After etching and attaching resin to these surfaces, the specimens were thermocycled and then underwent the shearing bond strength tests at a speed of 5 mm/min. The results achieved, after statistical analysis with Student's t-test, showed that the adhesion was significantly greater in the 35% phosphoric acid treated group than in the group treated with the Nd:YAG laser, thus demonstrating the need for developing new studies to reach the ideal parameters for an effective enamel surface conditioning as well as specific adhesives and composite resins when Nd:YAG laser is used

  12. Shear bond strength between porcelain and nano filler composite resin with or without 9% hydrofluoric acid etching

    Directory of Open Access Journals (Sweden)

    Kun Ismiyatin

    2009-06-01

    Full Text Available Background: Reparation technique on restorations with broken or damaged porcelain which are still attached with the teeth are difficult, because it is very hard to remove the porcelain restoration without damaging it, and it needs a long time. Various ways have been developed to repair the broken porcelain, one of them is the use of composite resin as the material for the restoration of fractured porcelain. Repairing porcelain inside the mouth without removing the restoration of the damaged porcelain using light cured composite resins material seems to be an advantageous option because it is relatively simple, has low risks, good esthetically and cheap. Purpose: The objective of this study was to find out the difference of shear bond strength in porcelain reparation using nano filler composite resin with or without 9% hydrofluoric acid etching by using Autograph measuring device. Methods: Twenty pieces of the porcelain samples devided into 2 groups. Group I: etching process using 9% hydrofluoric acid, and group II : without etching process. Result: The data was analyzed using t test in a p value of 0.0001 (p≤0.05, which means there is a significant different of shear bond strength between treated group I and II. The biggest shear bond strength was in treatment group I. Conclusion: The use of 9% hydrofluoric acid on the surface of porcelain can increase the shear bond strength between porcelain and nano filler composite resin.

  13. Micro/nanofabrication of poly({sub L}-lactic acid) using focused ion beam direct etching

    Energy Technology Data Exchange (ETDEWEB)

    Oyama, Tomoko Gowa; Nagasawa, Naotsugu; Taguchi, Mitsumasa [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Hinata, Toru; Washio, Masakazu [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Oshima, Akihiro; Tagawa, Seiichi [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2013-10-14

    Micro/nanofabrication of biocompatible and biodegradable poly({sub L}-lactic acid) (PLLA) using focused Ga ion beam direct etching was evaluated for future bio-device applications. The fabrication performance was determined with different ion fluences and fluxes (beam currents), and it was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat. Focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds. Controlled micro/nanostructures of PLLA were fabricated with C=C bond-rich surfaces expected to have good cell attachment properties.

  14. Sphingoid bases inhibit acid-induced demineralization of hydroxyapatite

    NARCIS (Netherlands)

    Valentijn-Benz, M.; van 't Hof, W.; Bikker, F.J.; Nazmi, K.; Brand, H.S.; Sotres, J.; Lindh, L.; Arnebrant, T.; Veerman, E.C.I.

    2015-01-01

    Calcium hydroxyapatite (HAp), the main constituent of dental enamel, is inherently susceptible to the etching and dissolving action of acids, resulting in tooth decay such as dental caries and dental erosion. Since the prevalence of erosive wear is gradually increasing, there is urgent need for agen

  15. Influence of duration of phosphoric acid pre-etching on bond durability of universal adhesives and surface free-energy characteristics of enamel.

    Science.gov (United States)

    Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Watanabe, Hidehiko; Johnson, William W; Latta, Mark A; Miyazaki, Masashi

    2016-08-01

    The purpose of this study was to evaluate the influence of duration of phosphoric acid pre-etching on the bond durability of universal adhesives and the surface free-energy characteristics of enamel. Three universal adhesives and extracted human molars were used. Two no-pre-etching groups were prepared: ground enamel; and enamel after ultrasonic cleaning with distilled water for 30 s to remove the smear layer. Four pre-etching groups were prepared: enamel pre-etched with phosphoric acid for 3, 5, 10, and 15 s. Shear bond strength (SBS) values of universal adhesive after no thermal cycling and after 30,000 or 60,000 thermal cycles, and surface free-energy values of enamel surfaces, calculated from contact angle measurements, were determined. The specimens that had been pre-etched showed significantly higher SBS and surface free-energy values than the specimens that had not been pre-etched, regardless of the aging condition and adhesive type. The SBS and surface free-energy values did not increase for pre-etching times of longer than 3 s. There were no significant differences in SBS values and surface free-energy characteristics between the specimens with and without a smear layer. The results of this study suggest that phosphoric acid pre-etching of enamel improves the bond durability of universal adhesives and the surface free-energy characteristics of enamel, but these bonding properties do not increase for phosphoric acid pre-etching times of longer than 3 s.

  16. Acid production in dental plaque after exposure to probiotic bacteria

    Directory of Open Access Journals (Sweden)

    Keller Mette K

    2012-10-01

    Full Text Available Abstract Background The increasing interest in probiotic lactobacilli in health maintenance has raised the question of potential risks. One possible side effect could be an increased acidogenicity in dental plaque. The aim of this study was to investigate the effect of probiotic lactobacilli on plaque lactic acid (LA production in vitro and in vivo. Methods In the first part (A, suspensions of two lactobacilli strains (L. reuteri DSM 17938, L. plantarum 299v were added to suspensions of supragingival dental plaque collected from healthy young adults (n=25. LA production after fermentation with either xylitol or fructose was analyzed. In the second part (B, subjects (n=18 were given lozenges with probiotic lactobacilli (L. reuteri DSM 17938 and ATCC PTA 5289 or placebo for two weeks in a double-blinded, randomized cross-over trial. The concentration of LA in supragingival plaque samples was determined at baseline and after 2 weeks. Salivary counts of mutans streptococci (MS and lactobacilli were estimated with chair-side methods. Results Plaque suspensions with L. reuteri DSM 17938 produced significantly less LA compared with L. plantarum 299v or controls (p Conclusion Lactic acid production in suspensions of plaque and probiotic lactobacilli was strain-dependant and the present study provides no evidence of an increase in plaque acidity by the supply of selected probiotic lactobacilli when challenged by fructose or xylitol. The study protocol was approved by The Danish National Committee on Biomedical Research Ethics (protocol no H-2-2010-112. Trial registration NCT01700712

  17. Influence of acid-etching and ceramic primers on the repair of a glass ceramic.

    Science.gov (United States)

    Queiroz, J R C; Souza, Rodrigo O A; Nogueira Junior, L; Ozcan, M; Bottino, M A

    2012-01-01

    The objective of this study was to evaluate the influence of different primers on the microtensile bond strength (μTBS) between a feldspathic ceramic and two composites. Forty blocks (6.0 x 6.0 x 5.0 mm³) were prepared from Vita Mark II . After polishing, they were randomly divided into 10 groups according to the surface treatment: Group 1, hydrofluoric acid 10% (HF) + silane; Group 2, CoJet + silane; Group 3, HF + Metal/Zirconia Primer; Group 4, HF + Clearfil Primer; Group 5, HF + Alloy Primer; Group 6, HF + V-Primer; Group 7, Metal/Zirconia Primer; Group 8, Clearfil Primer; Group 9, Alloy Primer; Group 10, V-Primer. After each surface treatment, an adhesive was applied and one of two composite resins was incrementally built up. The sticks obtained from each block (bonded area: 1.0 mm² ± 0.2 mm) were stored in distilled water at 37 degrees C for 30 days and submitted to thermocycling (7,000 cycles; 5 degrees C/55 degrees C ± 1 degree C). The μTBS test was carried out using a universal testing machine (1.0 mm/min). Data were analyzed using ANOVA and a Tukey test (a = 0.05). The surface treatments significantly affected the results (P 0.05). The bond strength means (MPa) were as follows: Group 1a = 29.6; Group 1b = 33.7; Group 2a = 28.9; Group 2b = 27.1; Group 3a = 13.8; Group 3b = 14.9; Group 4a = 18.6; Group 4b = 19.4; Group 5a = 15.3; Group 5b = 16.5; Group 6a = 11; Group 6b = 18; Groups 7a to 10b = 0. While the use of primers alone was not sufficient for adequate bond strengths to feldspathic ceramic, HF etching followed by any silane delivered higher bond strength.

  18. Dental erosion in workers exposed to sulfuric acid in lead storage battery manufacturing facility.

    Science.gov (United States)

    Suyama, Yuji; Takaku, Satoru; Okawa, Yoshikazu; Matsukubo, Takashi

    2010-01-01

    Dental erosion, and specifically its symptoms, has long been studied in Japan as an occupational dental disease. However, in recent years, few studies have investigated the development of this disease or labor hygiene management aimed at its prevention. As a result, interest in dental erosion is comparatively low, even among dental professionals. Our investigation at a lead storage battery factory in 1991 found that the work environmental sulfuric acid density was above the tolerable range (1.0mg/m(3)) and that longterm workers had dental erosion. Therefore, workers handling sulfuric acid were given an oral examination and rates of dental erosion by tooth type, rates of erosion by number of working years and rates of erosion by sulfuric acid density in the work environment investigated. Where dental erosion was diagnosed, degree of erosion was identified according to a diagnostic criterion. No development of dental erosion was detected in the maxillary teeth, and erosion was concentrated in the anterior mandibular teeth. Its prevalence was as high as 20%. Rates of dental erosion rose precipitously after 10 working years. The percentages of workers with dental erosion were 42.9% for 10-14 years, 57.1% for 15-19 years and 66.7% for over 20 years with 22.5% for total number of workers. The percentages of workers with dental erosion rose in proportion to work environmental sulfuric acid density: 17.9% at 0.5-1.0, 25.0% at 1.0-4.0 and 50.0% at 4.0-8.0mg/m(3). This suggests that it is necessary to evaluate not only years of exposure to sulfuric acid but also sulfuric acid density in the air in factory workers.

  19. Dental unit waterlines disinfection using hypochlorous acid-based disinfectant

    OpenAIRE

    Irfana Fathima Shajahan; Kandaswamy, D; Padma Srikanth; L Lakshmi Narayana; R Selvarajan

    2016-01-01

    Objective: The purpose of the study was to investigate the efficacy of a new disinfectant to disinfect the dental unit waterlines. Materials and Methods: New dental unit waterlines were installed in 13 dental chairs, and biofilm was allowed to grow for 10 days. Disinfection treatment procedure was carried out in the 12 units, and one unit was left untreated. The dental unit waterlines were removed and analyzed using the scanning electron microscope (SEM) (TESCAN VEGA3 SBU). Result: On examina...

  20. Bond strength of composite to dentin: effect of acid etching and laser irradiation through an uncured self-etch adhesive system

    Science.gov (United States)

    Castro, F. L. A.; Carvalho, J. G.; Andrade, M. F.; Saad, J. R. C.; Hebling, J.; Lizarelli, R. F. Z.

    2014-08-01

    This study evaluated the effect on micro-tensile bond strength (µ-TBS) of laser irradiation of etched/unetched dentin through an uncured self-etching adhesive. Dentinal surfaces were treated with Clearfil SE Bond Adhesive (CSE) either according to the manufacturer’s instructions (CSE) or without applying the primer (CSE/NP). The dentin was irradiated through the uncured adhesive, using an Nd:YAG laser at 0.75 or 1 W power settings. The adhesive was cured, composite crowns were built up, and the teeth were sectioned into beams (0.49 mm2) to be stressed under tension. Data were analyzed using one-way ANOVA and Tukey statistics (α = 5%). Dentin of the fractured specimens and the interfaces of untested beams were observed under scanning electron microscopy (SEM). The results showed that non-etched irradiated surfaces presented higher µ-TBS than etched and irradiated surfaces (p 0.05). SEM showed solidification globules on the surfaces of the specimens. The interfaces were similar on irradiated and non-irradiated surfaces. Laser irradiation of dentin through the uncured adhesive did not lead to higher µ-TBS when compared to the suggested manufacturer’s technique. However, this treatment brought benefits when performed on unetched dentin, since bond strengths were higher when compared to etched dentin.

  1. Acid etching process for fabrication of Bi2Sr2CaCu2O8+x stack

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jie; CHEN Jian; WU JingBo; KANG Lin; XU WeiWei; WU PeiHeng

    2007-01-01

    We adopted a new method, acid etching process, to fabricate the intrinsic Josephson junctions based on the Bi2Sr2CaCu2O8+x single crystals. By soaking the crystals into the dilute hydrochloric acid, we fabricated a junction stack successfully, and meantime made the surrounding area insulated. A certain concentration of hydrochloric acid was used to maintain the roughness of the modified layer. The current-voltage characteristic was achieved through the four terminal measurement. We could control the junctions' number by changing the concentration and the soaking time. We also found that the thickness of the stack was equal to the average height of the insulation layer. Such a simple, convenient and controllable fabrication method with a high yield might widen the applications of the intrinsic Josephson junctions.

  2. Current Uses of Poly(lactic-co-glycolic acid in the Dental Field: A Comprehensive Review

    Directory of Open Access Journals (Sweden)

    Maria Justina Roxana Virlan

    2015-01-01

    Full Text Available Poly(lactic-co-glycolic acid or PLGA is a biodegradable polymer used in a wide range of medical applications. Specifically PLGA materials are also developed for the dental field in the form of scaffolds, films, membranes, microparticles, or nanoparticles. PLGA membranes have been studied with promising results, either alone or combined with other materials in bone healing procedures. PLGA scaffolds have been used to regenerate damaged tissues together with stem cell-based therapy. There is solid evidence that the development of PLGA microparticles and nanoparticles may be beneficial to a wide range of dental fields such as endodontic therapy, dental caries, dental surgery, dental implants, or periodontology. The aim of the current paper was to review the recent advances in PLGA materials and their potential uses in the dental field.

  3. Relation between etch-pit morphology and step retreat velocity on a calcite surface in aspartic acid solution

    Science.gov (United States)

    Yoshino, Toru; Kagi, Hiroyuki; Kamiya, Natsumi; Kokawa, Ryohei

    2010-04-01

    Effects of L-aspartic acid ( L-Asp) on dissolution of calcite were investigated. The step retreat velocity and dissolution rate of calcite were measured simultaneously using an AFM flow-through system. The etch-pit morphology of calcite was observed using confocal laser scanning microscopy. Results show that the etch-pit morphologies changed drastically depending on the L-Asp concentration ([ L-Asp]) in the order of rhomboidal, pentagonal, and triangular (not perfectly, but retaining an extra step). The change in obtuse step directions and appearance of the [0 1 0] step triggered these morphological changes. Addition of L-Asp accelerated all step retreats at [ L-Asp]0.01 M, L-Asp inhibited the retreats of obtuse steps and [0 1 0] step, although the retreat velocities of acute steps were constant irrespective of [ L-Asp]. These results suggest that the directional changes and the inhibition of retreat velocities of obtuse steps were attributed to the generation of [ 4 1 1] and [4 5 1] steps caused by L-Asp. Moreover, we confirmed the preferential effects of L-Asp on the [4 8 1] + to [ 4 4 1] ± step edge, and proposed the preferential effects of L-Asp on the [ 4 1 1] to [4 5 1] step edge.

  4. Combinatorial localized dissolution analysis: Application to acid-induced dissolution of dental enamel and the effect of surface treatments.

    Science.gov (United States)

    Parker, Alexander S; Al Botros, Rehab; Kinnear, Sophie L; Snowden, Michael E; McKelvey, Kim; Ashcroft, Alexander T; Carvell, Mel; Joiner, Andrew; Peruffo, Massimo; Philpotts, Carol; Unwin, Patrick R

    2016-08-15

    A combination of scanning electrochemical cell microscopy (SECCM) and atomic force microscopy (AFM) is used to quantitatively study the acid-induced dissolution of dental enamel. A micron-scale liquid meniscus formed at the end of a dual barrelled pipette, which constitutes the SECCM probe, is brought into contact with the enamel surface for a defined period. Dissolution occurs at the interface of the meniscus and the enamel surface, under conditions of well-defined mass transport, creating etch pits that are then analysed via AFM. This technique is applied to bovine dental enamel, and the effect of various treatments of the enamel surface on acid dissolution (1mM HNO3) is studied. The treatments investigated are zinc ions, fluoride ions and the two combined. A finite element method (FEM) simulation of SECCM mass transport and interfacial reactivity, allows the intrinsic rate constant for acid-induced dissolution to be quantitatively determined. The dissolution of enamel, in terms of Ca(2+) flux ( [Formula: see text] ), is first order with respect to the interfacial proton concentration and given by the following rate law: [Formula: see text] , with k0=0.099±0.008cms(-1). Treating the enamel with either fluoride or zinc ions slows the dissolution rate, although in this model system the partly protective barrier only extends around 10-20nm into the enamel surface, so that after a period of a few seconds dissolution of modified surfaces tends towards that of native enamel. A combination of both treatments exhibits the greatest protection to the enamel surface, but the effect is again transient.

  5. Effect of hydrofluoric acid concentration on the evolution of photoluminescence characteristics in porous silicon nanowires prepared by Ag-assisted electroless etching method

    KAUST Repository

    Najar, Adel

    2012-01-01

    We report on the structural and optical properties of porous silicon nanowires (PSiNWs) fabricated using silver (Ag) ions assisted electroless etching method. Silicon nanocrystallites with sizes <5 nm embedded in amorphous silica have been observed from PSiNW samples etched using the optimum hydrofluoric acid (HF) concentration. The strongest photoluminescence (PL) signal has been measured from samples etched with 4.8 M of HF, beyond which a significant decreasing in PL emission intensity has been observed. A qualitative model is proposed for the formation of PSiNWs in the presence of Ag catalyst. This model affirms our observations in PL enhancement for samples etched using HF <4.8 M and the eventual PL reduction for samples etched beyond 4.8 M of HF concentration. The enhancement in PL signals has been associated to the formation of PSiNWs and the quantum confinement effect in the Si nanocrystallites. Compared to PSiNWs without Si-O x, the HF treated samples exhibited significant blue PL peak shift of 100 nm. This effect has been correlated to the formation of defect states in the surface oxide. PSiNWs fabricated using the electroless etching method can find useful applications in optical sensors and as anti-reflection layer in silicon-based solar cells. © 2012 American Institute of Physics.

  6. Comparison of shear bond strength and surface structure between conventional acid etching and air-abrasion of human enamel.

    Science.gov (United States)

    Olsen, M E; Bishara, S E; Damon, P; Jakobsen, J R

    1997-11-01

    Recently, air-abrasion technology has been examined for potential applications within dentistry, including the field of orthodontics. The purpose of this study was to compare the traditional acid-etch technique with an air-abrasion surface preparation technique, with two different sizes of abrading particles. The following parameters were evaluated: (a) shear bond strength, (b) bond failure location, and (c) enamel surface preparation, as viewed through a scanning electron microscope. Sixty extracted human third molars were pumiced and divided into three groups of 20. The first group was etched with a 37% phosphoric acid gel for 30 seconds, rinsed for 30 seconds, and dried for 20 seconds. The second and third groups were air-abraded with (a) a 50 microm particle and (b) a 90 microm particle of aluminum oxide, with the Micro-etcher microabrasion machine (Danville Engineering Inc.). All three groups had molar stainless steel orthodontic brackets bonded to the buccal surface of each tooth with Transbond XT bonding system (3M Unitek). A Zwick Universal Testing Machine (Calitek Corp.) was used to determine shear bond strengths. The analysis of variance was used to compare the three groups. The Adhesive Remnant Index (ARI) was used to evaluate the residual adhesive on the enamel after bracket removal. The chi square test was used to evaluate differences in the ARI scores among the groups. The significance for all tests was predetermined at p shear bond strength among the three groups (p = 0.0001). The Duncan Multiple Range test showed a significant decrease in shear bond strength in the air-abraded groups. The chi square test revealed significant differences among the ARI scores of the acid-etched group and the air-abraded groups (chi(2) = 0.0001), indicating no adhesive remained on the enamel surface after debonding when air-abrasion was used. In conclusion, the current findings indicate that enamel surface preparation using air-abrasion results in a significant lower

  7. UV-induced graft polymerization of acrylic acid in the sub-micronchannels of oxidized PET track-etched membrane

    Energy Technology Data Exchange (ETDEWEB)

    Korolkov, Ilya V.; Mashentseva, Anastassiya A. [The L.N. Gumilyov Eurasian National University, Satpayev str., 2, 010008 Astana (Kazakhstan); Institute of Nuclear Physics Republic of Kazakhstan, 050032, Ibragimov str., 1, Almaty (Kazakhstan); Güven, Olgun [Department of Chemistry, Hacettepe University, 06800 Beytepe, Ankara (Turkey); Taltenov, Abzal A. [The L.N. Gumilyov Eurasian National University, Satpayev str., 2, 010008 Astana (Kazakhstan)

    2015-12-15

    In this article, we report on functionalization of track-etched membrane based on poly(ethylene terephthalate) (PET TeMs) oxidized by advanced oxidation systems and by grafting of acrylic acid using photochemical initiation technique for the purpose of increasing functionality thus expanding its practical application. Among advanced oxidation processes (H{sub 2}O{sub 2}/UV) system had been chosen to introduce maximum concentration of carboxylic acid groups. Benzophenone (BP) photo-initiator was first immobilized on the surfaces of cylindrical pores which were later filled with aq. acrylic acid solution. UV-irradiation from both sides of PET TeMs has led to the formation of grafted poly(acrylic acid) (PAA) chains inside the membrane sub-micronchannels. Effect of oxygen-rich surface of PET TeMs on BP adsorption and subsequent process of photo-induced graft polymerization of acrylic acid (AA) were studied by ESR. The surface of oxidized and AA grafted PET TeMs was characterized by UV–vis, ATR-FTIR, XPS spectroscopies and by SEM.

  8. Amino acid derivative-mediated detoxification and functionalization of dual cure dental restorative material for dental pulp cell mineralization.

    Science.gov (United States)

    Minamikawa, Hajime; Yamada, Masahiro; Iwasa, Fuminori; Ueno, Takeshi; Deyama, Yoshiaki; Suzuki, Kuniaki; Yawaka, Yasutaka; Ogawa, Takahiro

    2010-10-01

    Current dental restorative materials are only used to fill the defect of hard tissues, such as dentin and enamel, because of their cytotoxicity. Therefore, exposed dental pulp tissues in deep cavities must be first covered by a pulp capping material like calcium hydroxide to form a layer of mineralized tissue. However, this tissue mineralization is based on pathological reaction and triggers long-lasting inflammation, often causing clinical problems. This study tested the ability of N-acetyl cysteine (NAC), amino acid derivative, to reduce cytotoxicity and induce mineralized tissue conductivity in resin-modified glass ionomer (RMGI), a widely used dental restorative material having dual cure mechanism. Rat dental pulp cells were cultured on untreated or NAC-supplemented RMGI. NAC supplementation substantially increased the percentage of viable cells from 46.7 to 73.3% after 24-h incubation. Cell attachment, spreading, proliferative activity, and odontoblast-related gene and protein expressions increased significantly on NAC-supplemented RMGI. The mineralization capability of cells, which was nearly suppressed on untreated RMGI, was induced on NAC-supplemented RMGI. These improved behaviors and functions of dental pulp cells on NAC-supplemented RMGI were associated with a considerable reduction in the production of intracellular reactive oxygen species and with the increased level of intracellular glutathione reserves. These results demonstrated that NAC could detoxify and functionalize RMGIs via two different mechanisms involving in situ material detoxification and antioxidant cell protection. We believe that this study provides a new approach for developing dental restorative materials that enables mineralized tissue regeneration.

  9. An In Vitro Comparison of the Bond Strength of Composite to Superficial and Deep Dentin, Treated With Er:YAG Laser Irradiation or Acid-Etching

    Science.gov (United States)

    Alaghehmand, Homayoon; Nezhad Nasrollah, Fatemeh; Nokhbatolfoghahaei, Hanieh; Fekrazad, Reza

    2016-01-01

    Introduction: The aim of this study was to compare the micro-shear bond strength of composite resin on superficial and deep dentin after conditioning with phosphoric acid and Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser. Methods: Thirty human molars were selected, roots were removed and crowns were bisected to provide a total of 60 half-crowns. Specimens were ground to expose superficial and deep dentin. Samples were assigned to six groups: (1) AS (acid etching of superficial dentin); (2) AD (acid etching of deep dentin); (3) LS (Er:YAG laser irradiation on superficial dentin); (4) LD (Er:YAG laser irradiation on deep dentin); (5) LAS (Er:YAG laser irradiation on superficial dentin followed by acid etching); (6) LAD (Er:YAG laser irradiation on deep dentin followed by acid etching) The adhesive protocol was performed. Samples were thermocycled and micro-shear bond strength was tested to failure. The data were submitted to statistical analysis with one-way analysis of variance (ANOVA) and Tukey post hoc test. Results: The AS group, demonstrated the greatest amount of micro-shear bond strength. Statistical analysis showed a decrease in bond strength in laser-treated groups which was more significant for deep dentin. Conclusion: Preparation of dentin with laser did not improve bonding to superficial and deep dentin. PMID:28144437

  10. Evaluation of the effectiveness of peracetic acid in the sterilization of dental equipment

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    Ceretta R

    2008-01-01

    Full Text Available Purpose: To evaluate the effectiveness of peracetic acid in the microbiological sterilisation of dental materials. Methods: Peracetic acid solution was evaluated at concentrations of 800, 1500 and 2500 ppm. At these concentrations, it was determined whether peracetic acid caused corrosion to dental instruments and induced cellular mutagenicity and cytotoxicidity. In addition, the minimum inhibitory concentration (MIC, the minimum bactericidal concentration (MBC, agar diffusion and diffusion by well method, were also verified. Results: The corrosion rate, calculated from potentiodynamic assays was 10 -6 cm/year, indicating that the product does not damage equipment. The sterilisation capacity of peracetic acid at 2500 ppm was the best. The comet assay indicated genotoxic activity at 2500 ppm. Conclusions: This study demonstrated the effectiveness of peracetic acid for sterilizing dental equipment, providing another alternative for the prevention of infections in clinics.

  11. Copper release from dental prosthetic crowns, dental materials, and human teeth into acetic acid.

    Science.gov (United States)

    Kalicanin, Biljana M; Nikolić, Ruzica S

    2010-01-01

    This article examines the dilution of the ion of copper from human teeth and dental prosthetic crowns in 4% CH(3)COOH during a period of 24 hr at room temperature. The content of the diluted copper in an acetate extract, as well as the overall content of this metal in the samples, was determined by means of a potentiometric stripping analysis. The comparative measurements were carried out using the furnace atomic absorption spectrophotometry technique, which is recommended by the International Standards (ISO 6872:2008; ISO 24234:2004) as a method for quality control of dental-prosthetic material (dental ceramic, metal restorative materials, dental amalgams) in the process of checking for heavy metals. During a 24-hr period in 4% CH(3)COOH at a temperature of 25 degrees C, approximately 72% of the overall copper was released from the tooth. The percentage of the released copper from baby teeth is higher, ranging from 88 to 92%, which is probably a consequence of the bone tissue being in development, its infirmity, and inadequate stability. On these conditions, approximately 72% of the overall copper was released from the dental-ceramic prosthetic crowns.

  12. Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films

    Science.gov (United States)

    Hankins, Matthew G.

    2009-10-06

    Etchant solutions comprising a redox buffer can be used during the release etch step to reduce damage to the structural layers of a MEMS device that has noble material films. A preferred redox buffer comprises a soluble thiophosphoric acid, ester, or salt that maintains the electrochemical potential of the etchant solution at a level that prevents oxidation of the structural material. Therefore, the redox buffer preferentially oxidizes in place of the structural material. The sacrificial redox buffer thereby protects the exposed structural layers while permitting the dissolution of sacrificial oxide layers during the release etch.

  13. Micro-shear bond strength and surface micromorphology of a feldspathic ceramic treated with different cleaning methods after hydrofluoric acid etching

    Directory of Open Access Journals (Sweden)

    Henrique Caballero STEINHAUSER

    2014-04-01

    Full Text Available Objective: The aim of this study was to evaluate the effect of feldspathic ceramic surface cleaning on micro-shear bond strength and ceramic surface morphology. Material and Methods: Forty discs of feldspathic ceramic were prepared and etched with 10% hydrofluoric acid for 2 minutes. The discs were randomly distributed into five groups (n=8: C: no treatment, S: water spray + air drying for 1 minute, US: immersion in ultrasonic bath for 5 minutes, F: etching with 37% phosphoric acid for 1 minute, followed by 1-minute rinse, F+US: etching with 37% phosphoric acid for 1 minute, 1-minute rinse and ultrasonic bath for 5 minutes. Composite cylinders were bonded to the discs following application of silane and hydrophobic adhesive for micro-shear bond strength testing in a universal testing machine at 0.5 mm/min crosshead speed until failure. Stereomicroscopy was used to classify failure type. Surface micromorphology of each treatment type was evaluated by scanning electron microscopy at 500 and 2,500 times magnification. Results: One-way ANOVA test showed no significant difference between treatments (p=0.3197 and the most common failure types were cohesive resin cohesion followed by adhesive failure. Micro-shear bond strength of the feldspathic ceramic substrate to the adhesive system was not influenced by the different surface cleaning techniques. Absence of or less residue was observed after etching with hydrofluoric acid for the groups US and F+US. Conclusions: Combining ceramic cleaning techniques with hydrofluoric acid etching did not affect ceramic bond strength, whereas, when cleaning was associated with ultrasound, less residue was observed.

  14. Requirement for development of dental adhesives

    OpenAIRE

    2016-01-01

    Alan Boyde and his colleagues first described smear layers-covered dental hard tissues. Later, David Eick and his group examined smear layer-covered dentin and showed how acid-labile are smear layers. A superior bond strength has come to be provided for the resin-dentin interface in the current dental adhesive systems as a result that the acid-etching treatment for the enamel/dentin was examined to remove smear layers. Moreover, latest adhesive systems which gave top priority to convenience i...

  15. Correlation between ISQ and Insertion Torque values using double acid-etched implants

    Directory of Open Access Journals (Sweden)

    Sebastián Gallardo

    2016-12-01

    Full Text Available Aim The purpose of this study was threefold: (1 to consider whether there was a correlation between stability quotient values (ISQ and insertion torque values (IT at implant placement (2; to determine which of these values were more related to success or failure; and (3 to determine the influence of bone type and implant length, diameter and shape in the study results. Materials and methods A retrospective clinical study was carried out between June 2012 and June 2014. The insertion torque and resonance frequency values of 279 double achid etched implants (Osseotite, Biomet 3i, Implant Innovations Inc., Palm Beach Gardens, USA, with conical and parallel walls, and of different diameters and lengths, were tested at the moment of insertion in 90 patients of different age (18-82 years of age/ average: 60.89 years and of both genders (58 females and 32 males. Collected data were processed and subjected to statistical analysis. Results The mean ISQ value was 70.54, showing no statistical significance between successful and unsuccessful implants. The mean IT value was 44.18. In this case, the values obtained showed a difference between successful and unsuccessful implants, yet not statistically significant (p> 0.05. However, statistically significant differences were found in relation to bone type, shape and length of the implants in IT as well as ISQ values. In the former case (IT values, the differences were only related to diameter. Conclusion There was a correlation between ISQ and IT values; with no significant difference concerning success or failure. The variables analyzed showed statistical differences, except for diameter, which was only significant for IT.

  16. Nitrogen dioxide-dependent oxidation of uric acid in the human oral cavity under acidic conditions: implications for its occurrence in acidic dental plaque.

    Science.gov (United States)

    Takahama, Umeo; Hirota, Sachiko

    2010-06-21

    The pH in dental plaque falls to below 5 after the ingestion of foods, and it may remain low if acid-tolerant bacteria grow in the plaque. Certain nitrate-reducing bacteria in the oral cavity can proliferate in dental plaque at low pH, and nitrite is detected in such plaque. In acidic dental plaque, NO(2) can be produced by self-decomposition of nitrous acid and also by peroxidase-catalyzed oxidation of nitrite, and it may oxidize uric acid, a major antioxidant in the oral cavity. Under experimental conditions that simulate oral cavity, the oxidation of uric acid by nitrite and by nitrite/peroxidase systems was much more rapid at pH 5 than at pH 7, suggesting the more rapid production of NO(2) in dental plaque at lower pH. We propose that if the pH of plaque developed in a dental crevice decreased, NO(2) and other nitrogen oxides produced in the plaque would diffuse into the adjoining gingival tissues. The results of this study seem to contribute to the understanding of the induction of periodontal diseases in the context of nitrite-dependent production of nitrogen oxides in acidic dental plaque.

  17. Comparison of Shear Bond Strength of Orthodontic Brackets Bonded to Enamel Prepared By Er:YAG Laser and Conven-tional Acid-Etching

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    M.H. Hosseini

    2012-01-01

    Full Text Available Introduction: The purpose of this study was to compare shear bond strength (SBS of orthodontic brackets bonded to enamel prepared by Er:YAG laser with two different powers and conventional acid-etching.Materials and Methods: Forty-five human premolars extracted for orthodontic purposes were randomly assigned to three groups based on conditioning method: Group 1- conventional etching with 37% phosphoric acid; Group 2- irradiation with Er:YAG laser at 1 W; and Group 3- irradiation with Er:YAG laser at 1.5 W. Metal brackets were bonded on prepared enamel using a light-cured composite. All groups were subjected to thermocycling process. Then, the specimens mounted in auto-cure acryle and shear bond strength were measured using a universal testing machine with a crosshead speed of 0.5 mm per second. After debonding, the amount of resin remaining on the teeth was determined using the adhesive remnant index (ARI scored 1 to 5. One-way analysis of variance was used to compare shear bond strengths and the Kruskal-Wallis test was performed to evaluate differences in the ARI for different etching types.Results: The mean and standard deviation of conventional acid-etch group, 1W laser group and 1.5W laser group was 3.82 ± 1.16, 6.97 ± 3.64 and 6.93 ± 4.87, respectively.Conclusion: The mean SBS obtained with an Er:YAG laser operated at 1W or 1.5W is approximately similar to that of conventional etching. However, the high variability of values in bond strength of irradiated enamel should be considered to find the appropriate parameters for applying Er:YAG laser as a favorable alternative for surface conditioning.

  18. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Science.gov (United States)

    Provine, J.; Schindler, Peter; Kim, Yongmin; Walch, Steve P.; Kim, Hyo Jin; Kim, Ki-Hyun; Prinz, Fritz B.

    2016-06-01

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD) of silicon nitride (SiNx), particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER) in hydrofluoric (HF) acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD) of SiNx and evaluate the film's WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  19. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Directory of Open Access Journals (Sweden)

    J. Provine

    2016-06-01

    Full Text Available The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD of silicon nitride (SiNx, particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER in hydrofluoric (HF acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD of SiNx and evaluate the film’s WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  20. Effect of an Indirect Composite Resin Surface Treatment with Two Types of Lasers: Nd: YAG, Er:YAG and Acid Etching on the Microshear Bond Strength of a Resin Cement

    OpenAIRE

    2014-01-01

    Introduction: In order to increase the bonding strength of the composite resin cements to the indirect composites, experiments such as the creation of surface roughness with sandblasting, acid-etching, silane application, laser, etc. have been carried out. However, there is no consensus about the results. Therefore, the purpose of this study was to investigate the effect of Er: YAG and Nd: YAG lasers and acid etching on microshear bond strength of an indirect composite resin. Methods: Aft...

  1. Modulated regeneration of acid-etched human tooth enamel by a functionalized dendrimer that is an analog of amelogenin.

    Science.gov (United States)

    Chen, Mei; Yang, Jiaojiao; Li, Jiyao; Liang, Kunneng; He, Libang; Lin, Zaifu; Chen, Xingyu; Ren, Xiaokang; Li, Jianshu

    2014-10-01

    In the bioinspired repair process of tooth enamel, it is important to simultaneously mimic the organic-matrix-induced biomineralization and increase the binding strength at the remineralization interface. In this work, a fourth-generation polyamidoamine dendrimer (PAMAM) is modified by dimethyl phosphate to obtain phosphate-terminated dendrimer (PAMAM-PO3H2) since it has a similar dimensional scale and peripheral functionalities to that of amelogenin, which plays important role in the natural development process of enamel. Its phosphate group has stronger affinity for calcium ion than carboxyl group and can simultaneously provide strong hydroxyapatite (HA)-binding capability. The MTT assay demonstrates the low cytotoxicity of PAMAM-PO3H2. Adsorption tests indicate that PAMAM-PO3H2 can be tightly adsorbed on the human tooth enamel. Scanning electron microscopy and X-ray diffraction are used to analyze the remineralization process. After being incubated in artificial saliva for 3weeks, there is a newly generated HA layer of 11.23μm thickness on the acid-etched tooth enamel treated by PAMAM-PO3H2, while the thickness for the carboxyl-terminated one (PAMAM-COOH) is only 6.02μm. PAMAM-PO3H2 can regulate the remineralization process to form ordered new crystals oriented along the Z-axis and produce an enamel prism-like structure that is similar to that of natural tooth enamel. The animal experiment also demonstrates that PAMAM-PO3H2 can induce significant HA regeneration in the oral cavity of rats. Thus PAMAM-PO3H2 shows great potential as a biomimetic restorative material for human tooth enamel.

  2. Micro-PIXE and micro-RBS characterization of micropores in porous silicon prepared using microwave-assisted hydrofluoric acid etching.

    Science.gov (United States)

    Ahmad, Muthanna; Grime, Geoffrey W

    2013-04-01

    Porous silicon (PS) has been prepared using a microwave-assisted hydrofluoric acid (HF) etching method from a silicon wafer pre-implanted with 5 MeV Cu ions. The use of microbeam proton-induced X-ray emission (micro-PIXE) and microbeam Rutherford backscattering techniques reveals for the first time the capability of these techniques for studying the formation of micropores. The porous structures observed from micro-PIXE imaging results are compared to scanning electron microscope images. It was observed that the implanted copper accumulates in the same location as the pores and that at high implanted dose the pores form large-scale patterns of lines and concentric circles. This is the first work demonstrating the use of microwave-assisted HF etching in the formation of PS.

  3. Plasma-Enhanced Atomic Layer Deposition of SiN-AlN Composites for Ultra Low Wet Etch Rates in Hydrofluoric Acid.

    Science.gov (United States)

    Kim, Yongmin; Provine, J; Walch, Stephen P; Park, Joonsuk; Phuthong, Witchukorn; Dadlani, Anup L; Kim, Hyo-Jin; Schindler, Peter; Kim, Kihyun; Prinz, Fritz B

    2016-07-13

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposited (ALD) of hydrofluoric acid (HF) etch resistant and electrically insulating films for sidewall spacer processing. Silicon nitride (SiN) has been the prototypical material for this need and extensive work has been conducted into realizing sufficiently lower wet etch rates (WERs) as well as leakage currents to meet industry needs. In this work, we report on the development of plasma-enhanced atomic layer deposition (PEALD) composites of SiN and AlN to minimize WER and leakage current density. In particular, the role of aluminum and the optimum amount of Al contained in the composite structures have been explored. Films with near zero WER in dilute HF and leakage currents density similar to pure PEALD SiN films could be simultaneously realized through composites which incorporate ≥13 at. % Al, with a maximum thermal budget of 350 °C.

  4. Silicone sealers, acetic acid vapours and dental erosion: a work-related risk?

    Science.gov (United States)

    Johansson, Ann-Katrin; Johansson, Anders; Stan, Vlaicu; Ohlson, Carl-Göran

    2005-01-01

    The aim of the present study was to investigate whether the acetic acid released by some silicone sealers during the curing process poses an increased risk for dental erosion, thus constituting an occupational hazard to exposed individuals. The material comprised 13 individuals (x=30 years, 10 men and 3 women) who had been exposed to an average of 4.2 years' (range 0.6-10 years) of working with silicone. Each had comprehensive medical and dental examinations carried out. A sex- and aged-matched group of 20 healthy, unexposed workers from the same company served as controls for the medical examination, while study models from randomly selected sex- and age-matched individuals were used as controls for assessing the severity of erosion. Using a questionnaire, an assessment of the role of various possible factors related to oral and general health, and to dental erosion in particular, was made for each participant in the exposed group. Clinical examination included recordings of severity of dental erosion, presence of "cuppings", DMFT, salivary secretion rate and buffer capacity, visible plaque index and gingival bleeding index. In addition, bitewing radiographs, study casts and intraoral colour transparencies were obtained for each individual. The severity of dental erosion was significantly higher in those exposed to silicone compared to controls. There was also a significant correlation between the period of exposure to silicone in the workplace and severity of erosion. Medical problems, especially with regard to upper respiratory tract symptoms, were significantly more common among exposed individuals than controls. In conclusion, a relationship between occupational exposure to acetic acid vapours from silicone sealers and development of dental erosion would appear to exist.

  5. Folic acid in cleft lip, alveolus and palate prevention: Awareness among dental professionals

    Directory of Open Access Journals (Sweden)

    Elavenil P

    2010-01-01

    Full Text Available Objectives : To determine the awareness amongst dental students, practitioners and maxillofacial surgeons the role of folic acid in the prevention of CLAP and its clinical use. Materials and Methods : Questionnaire based study involving a sample base of 1100, comprising of dental students, practitioners and specialist maxillofacial surgeons. Results : hundred percent of the sample population were aware of CLAP disorders, of which 9.5 % believed that CLAP could be prevented. 3.8 % of the population were able to correlate folic acid to CLAP while a negligible 0.03 % could provide the dosage. Conclusion : Educating healthcare providers and, in turn, the prospective parents on benefits folic acid would not only help in reducing the incidence of CLAP but also significantly influence the economics of the patients afflicted with CLAP disorders.

  6. Effect of acidic agents on surface roughness of dental ceramics

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    Boonlert Kukiattrakoon

    2011-01-01

    Conclusion: Acidic agents used in this study negatively affected the surface of ceramic materials. This should be considered when restoring the eroded tooth with ceramic restorations in patients who have a high risk of erosive conditions.

  7. Optical investigation of the intergrowth structure and accessibility of Brønsted acid sites in etched SSZ-13 zeolite crystals by confocal fluorescence microscopy.

    Science.gov (United States)

    Sommer, Linn; Svelle, Stian; Lillerud, Karl Petter; Stöcker, Michael; Weckhuysen, Bert M; Olsbye, Unni

    2010-11-02

    Template decomposition followed by confocal fluorescence microscopy reveals a tetragonal-pyramidal intergrowth of subunits in micrometer-sized nearly cubic SSZ-13 zeolite crystals. In order to accentuate intergrowth boundaries and defect-rich areas within the individual large zeolite crystals, a treatment with an etching NaOH solution is applied. The defective areas are visualized by monitoring the spatial distribution of fluorescent tracer molecules within the individual SSZ-13 crystals by confocal fluorescence microscopy. These fluorescent tracer molecules are formed at the inner and outer crystal surfaces by utilizing the catalytic activity of the zeolite in the oligomerization reaction of styrene derivatives. This approach reveals various types of etching patterns that are an indication for the defectiveness of the studied crystals. We can show that specially one type of crystals, denoted as core-shell type, is highly accessible to the styrene molecules after etching. Despite the large crystal dimensions, the whole core-shell type SSZ-13 crystal is utilized for catalytic reaction. Furthermore, the confocal fluorescence microscopy measurements indicate a nonuniform distribution of the catalytically important Brønsted acid sites underlining the importance of space-resolved measurements.

  8. Effect of acid vapor etching on morphological and opto-electric properties of flat silicon and silicon nanowire arrays: A comparative study

    Science.gov (United States)

    Amri, Chohdi; Ouertani, Rachid; Hamdi, Abderrahmen; Ezzaouia, Hatem

    2016-03-01

    In this paper, we report a comparative study between porous silicon (pSi) and porous silicon nanowires (pSiNWs). Acid Vapor Etching (AVE) treatment has been used to perform porous structure on flat Si and SiNWs array substrates respectively. SiNW structure is prepared by the widely used Silver catalyzed etching method. SEM and TEM images show that AVE treatment induces porous structure in the whole Si wafer and the SiNW sidewall. Comparatively to pSi, pSiNWs exhibit a low reflectivity in the whole spectral range which decreases with etching duration. However, the reflectivity of pSi changes with porous layer thickness. Both pSi and pSiNWs exhibit a significant PL peak situated at 2 eV. PL peaks are attributed to the quantum confinement effect in the silicon nanocrystallites (SiNCs). We discussed the significant enhancement in the peak intensities and a shift toward lower energy displayed in Raman spectra for both pSi and pSiNWs. We reported a correlative study of the AVE treatment effect on the minority carrier life time of flat silicon and SiNW arrays with the passivation effect of chemical induced silicon oxides highlighted by FTIR spectra.

  9. Effect of the Acidic Dental Resin Monomer 10-methacryloyloxydecyl Dihydrogen Phosphate on Odontoblastic Differentiation of Human Dental Pulp Cells.

    Science.gov (United States)

    Kim, Eun-Cheol; Park, Haejin; Lee, Sang-Im; Kim, Sun-Young

    2015-11-01

    Although 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) is frequently used as an acidic resin monomer in dental adhesives, its effect on dental pulp cells (DPCs) has been rarely reported. The purpose of this study was to examine the effects of 10-MDP on the inflammatory response and odontoblastic differentiation of DPCs at minimally toxic concentrations. We found that 10-MDP caused the release of inflammatory cytokines including NO, PGE2, iNOS, COX-2, TNF-α, IL-1β, IL-6 and IL-8 in a concentration-dependent manner. In addition, 10-MDP reduced alkaline phosphatase activity, mineralization nodule formation and mRNA expression of odontoblastic differentiation markers such as dentin sialophosphoprotein, dentin matrix protein-1, osterix and Runx2 in a concentration-dependent manner with low toxicity. In addition, 10-MDP induced activation of nuclear factor-E2-related factor 2 (Nrf2) and its target gene, haeme oxygenase-1 (HO-1). We evaluated whether the effect of 10-MDP was related to the induction of HO-1 and found that treatment with a selective inhibitor of HO-1 reversed the production of 10-MDP-mediated pro-inflammatory cytokines and the inhibition of differentiation markers. Pre-treatment with either a GSH synthesis inhibitor or antioxidants blocked 10-MDP-induced mitogen-activated protein kinases (MAPKs), Nrf2 and NF-κB pathways. Taken together, the results of this study showed that minimally toxic concentrations of 10-MDP promoted an inflammatory response and suppressed odontoblastic differentiation of DPCs by activating Nrf2-mediated HO-1 induction through MAPK and NF-κB signalling.

  10. Effect of erbium-doped: yttrium, aluminium and garnet laser irradiation on the surface microstructure and roughness of sand-blasted, large grit, acid-etched implants

    OpenAIRE

    2011-01-01

    Purpose The present study was performed to evaluate the effect of erbium-doped: yttrium, aluminium and garnet (Er:YAG) laser irradiation on sand-blasted, large grit, acid-etched (SLA) implant surface microstructure according to varying energy levels and application times of the laser. Methods The implant surface was irradiated by the Er:YAG laser under combined conditions of 100, 140, or 180 mJ/pulse and an application time of 1 minute, 1.5 minutes, or 2 minutes. Scanning electron microscopy ...

  11. Surface Treatments and Functional Coatings for Biocompatibility Improvement and Bacterial Adhesion Reduction in Dental Implantology

    Directory of Open Access Journals (Sweden)

    Pietro Mandracci

    2016-01-01

    Full Text Available Surface modification of dental implants is a key process in the production of these medical devices, and especially titanium implants used in the dental practice are commonly subjected to surface modification processes before their clinical use. A wide range of treatments, such as sand blasting, acid etching, plasma etching, plasma spray deposition, sputtering deposition and cathodic arc deposition, have been studied over the years in order to improve the performance of dental implants. Improving or accelerating the osseointegration process is usually the main goal of these surface processes, but the improvement of biocompatibility and the prevention of bacterial adhesion are also of considerable importance. In this review, we report on the research of the recent years in the field of surface treatments and coatings deposition for the improvement of dental implants performance, with a main focus on the osseointegration acceleration, the reduction of bacterial adhesion and the improvement of biocompatibility.

  12. Effects of Acid Treatment on Dental Zirconia: An In Vitro Study.

    Directory of Open Access Journals (Sweden)

    Haifeng Xie

    Full Text Available The aim of this study was to evaluate the effects of hydrofluoric (HF acid, acetic acid, and citric acid treatments on the physical properties and structure of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP at ambient temperature. In total, 110 bar-shaped zirconia specimens were randomly assigned to 11 groups. The specimens in the control group (C received no surface treatment, while those in the Cage group were hydrothermally aged at 134°C and 0.2 MPa for 20 h. Ten specimens each were immersed at ambient temperature in 5% and 40% HF acid for 2 h (40HF0, 1 day (5HF1, 40HF1, and 5 days (5HF5, 40HF5, while 10 each were immersed at ambient temperature in 10% acetic acid and 20% citric acid for 7 (AC7, CI7 and 14 days (AC14, CI14. X-ray diffraction (XRD was used to quantitatively estimate the monoclinic phase. Furthermore, flexural strength, surface roughness, and surface Vickers hardness were measured after treatment. Scanning electron microscopy (SEM was used to characterize the surface morphology. The Cage group specimens exhibited an increased monoclinic phase and flexural strength. Furthermore, 40% HF acid immersion decreased the flexural strength and surface hardness and deteriorated the surface finish, while 5% HF acid immersion only decreased the surface hardness. All the HF acid-immersed specimens showed an etched surface texture on SEM observations, while the other groups did not. These findings suggest that the treatment of Y-TZP with 40% HF acid at ambient temperature causes potential damage, while treatment with 5% HF acid, acetic acid, and citric acid is safe.

  13. Effects of a newly designed HEMA-free, multi-purpose, single-bottle, self-etching adhesive on bonding to dental hard tissues, zirconia-based ceramics, and gold alloy.

    Science.gov (United States)

    Ikemura, Kunio; Jogetsu, Yoshiyuki; Shinno, Kazuya; Nakatsuka, Toshiyuki; Endo, Takeshi; Kadoma, Yoshinori

    2011-01-01

    This study investigated the bonding effectiveness of newly designed self-etching adhesives to four types of adherends--enamel, dentin, zirconia, and gold (Au) alloy. Five experimental adhesives were prepared, which contained 3.0-5.0 wt% 6-methacryloyloxyhexyl phosphonoacetate (6-MHPA) or 6-methacryloyloxyhexyl 3-phosphonopropionate (6-MHPP), 3.0 wt% 4-acryloyloxyethoxycarbonylphthalic acid (4-AET) or 17.0 wt% 4-methacryloyloxyethoxycarbonylphthalic acid (4-MET), 0-0.5 wt% 6-methacryloyloxyhexyl 6,8-dithiooctanoate (6-MHDT) or 10-methacryloyloxydecyl 6,8-dithiooctanoate (10-MDDT), and varying contents of Bis-GMA, dimethacrylate monomers, water, acetone, and a photoinitiator system. After 2,000 times of thermal cycling, shear bond strengths (SBSs) between a resin composite (Beautifil II, Shofu Inc., Japan) and the four adherends, bonded using the experimental adhesives, were measured at 1.0 mm/min. No statistically significant differences in SBS for bonding to ground enamel, dentin, sandblasted zirconia and Au alloy (p>0.05) were found between experimental adhesives which contained 6-MHPA and/or 6-MHPP, 4-MET or 4-AET, 6-MHDT and/or 10-MDDT, Bis-GMA, and dimethacrylates. An adhesive layer of less than 5.0 µm thickness, by scanning electron microscopy observation, revealed strong adhesion to the four adherends. Therefore, the newly designed multi-purpose, self-etching adhesive strongly adhered to all the four adherend materials tested.

  14. Adhesion studies on dental enamel surfaces irradiated by a rapidly scanned carbon dioxide laser

    Science.gov (United States)

    Chang, Kwang K.; Staninec, Michal; Chan, Kenneth H.; Fried, Daniel

    2011-03-01

    In this study, we investigated the influence of different laser scanning patterns on the adhesive strength of laser irradiated enamel surfaces both with and without post ablation acid etching. Previous studies of dental enamel surfaces ablated by a rapidly scanned carbon dioxide laser indicated that the highly uniform smooth surfaces produced by the scanned laser beam yielded low bond strength and acid etching was required in order to attain a high bond strength. However, since the enamel surface after ablation by CO2 lasers is more resistant to acid dissolution it is desirable to avoid acid etching before bonding. The overlap between adjacent laser spots was varied to modify the effective surface roughness. In addition, small retention holes were drilled at higher laser intensity with varying spacing to increase the adhesive strength without acid etching. Varying the degree of overlap between adjacent laser spots did not significantly influence the bond strength with post ablation acid etching. The bond strength was significantly higher without acid etching with retention holes spaced 250-μm apart.

  15. Adhesive dentistry: the development of immediate dentin sealing/selective etching bonding technique.

    Science.gov (United States)

    Helvey, Gregg A

    2011-01-01

    A major objective of dental research over the past 60 years has been a search for the "dream-team" of dental adhesives. In fact, a recent Medline search produced more than 6,500 papers on dentin bonding and its techniques. Adhesive systems are designed to retain direct and indirect restorations, minimize leakage at the margin, and be simple to place while producing consistent results. The development of materials and techniques has an interesting history; some have recirculated from the past and are being used in some form today. Buonocore used the etchant phosphoric acid at the beginning of the adhesive revolution. Though not accepted for many years it eventually became the "gold standard" for etching enamel. Technique sensitivity moved it out of favor and, through the development of self-etching acidic primers, was eliminated from some adhesive systems. Although these primers may have successfully addressed postoperative sensitivity, adhesion was compromised. The bond strength of these systems has now been improved with the incorporation of phosphoric acid-etch to condition enamel prior to using the adhesive system. This article will trace the history of adhesive techniques and materials and how it has led to the creation of a new technique that combines two bonding methods.

  16. Quantificational Etching of AAO Template

    Institute of Scientific and Technical Information of China (English)

    Guojun SONG; Dong CHEN; Zhi PENG; Xilin SHE; Jianjiang LI; Ping HAN

    2007-01-01

    Ni nanowires were prepared by electrodeposition in porous anodized aluminum oxide (AAO) template from a composite electrolyte solution. Well-ordered Ni nanowire arrays with controllable length were then made by the partial removal of AAO using a mixture of phosphoric acid and chromic acid (6 wt pct H3PO4:1.8 wt pct H3CrO4). The images of Ni nanowire arrays were studied by scanning electron microscopy (SEM) to determine the relationship between etching time and the length of Ni nanowire arrays. The results indicate that the length of nanowires exposed from the template can be accurately controlled by controlling etching time.

  17. Morphology of resin-dentin interfaces after Er,Cr:YSGG laser and acid etching preparation and application of different bonding systems.

    Science.gov (United States)

    Beer, Franziska; Buchmair, Alfred; Körpert, Wolfram; Marvastian, Leila; Wernisch, Johann; Moritz, Andreas

    2012-07-01

    The goal of this study was to show the modifications in the ultrastructure of the dentin surface morphology following different surface treatments. The stability of the adhesive compound with dentin after laser preparation compared with conventional preparation using different bonding agents was evaluated. An Er,Cr:YSGG laser and 36% phosphoric acid in combination with various bonding systems were used. A total of 100 caries-free human third molars were used in this study. Immediately after surgical removal teeth were cut using a band saw and 1-mm thick dentin slices were created starting at a distance of 4 mm from the cusp plane to ensure complete removal of the enamel. The discs were polished with silicon carbide paper into rectangular shapes to a size of 6 × 4 mm (±0,2 mm).The discs as well as the remaining teeth stumps were stored in 0.9% NaCl at room temperature. The specimens were divided into three main groups (group I laser group, group II etch group, group III laser and etch group) and each group was subdivided into three subgroups which were allocated to the different bonding systems (subgroup A Excite, subgroup B Scotchbond, subgroup C Syntac). Each disc and the corresponding tooth stump were treated in the same way. After preparation the bonding composite material was applied according to the manufacturers' guidelines in a hollow tube of 2 mm diameter to the disc as well as to the corresponding tooth stump. Shear bond strength testing and environmental scanning electron microscopy were used to assess the morphology and stability of the resin-dentin interface. The self-etching bonding system showed the highest and the most constant shear values in all three main groups, thus enabling etching with phosphoric acid after laser preparation to be avoided. Thus we conclude that laser preparation creates a surface texture that allows prediction of the quality of the restoration without the risk of negative influences during the following treatment steps. This

  18. Análisis del Grabado Dental Utilizando el Microscopio Metalográfico y el Software AnalySIS Analysis of Dental Etching Using the Metallographic Microscope and AnalySIS Software

    OpenAIRE

    Consuelo Flores-Yáñez; Javier Martínez-Juárez; Mario Palma-Guzmán; Jorge Yáñez-Santos

    2009-01-01

    Se muestra que el microscopio metalográfico y el software AnalySIS representan técnicas adecuadas para el análisis del grabado dental ácido. Se grabó la superficie vestibular de 25 dientes humanos permanentes, de reciente extracción y libres de caries, se observaron al microscopio (100X) y se procesaron con el software AnalySIS. Se determinó el diámetro de poros seleccionados aleatoriamente y se evaluaron diferentes concentraciones de ácido fosfórico variando el tiempo de exposición. Los resu...

  19. Copper-assisted, anti-reflection etching of silicon surfaces

    Science.gov (United States)

    Toor, Fatima; Branz, Howard

    2014-08-26

    A method (300) for etching a silicon surface (116) to reduce reflectivity. The method (300) includes electroless deposition of copper nanoparticles about 20 nanometers in size on the silicon surface (116), with a particle-to-particle spacing of 3 to 8 nanometers. The method (300) includes positioning (310) the substrate (112) with a silicon surface (116) into a vessel (122). The vessel (122) is filled (340) with a volume of an etching solution (124) so as to cover the silicon surface (116). The etching solution (124) includes an oxidant-etchant solution (146), e.g., an aqueous solution of hydrofluoric acid and hydrogen peroxide. The silicon surface (116) is etched (350) by agitating the etching solution (124) with, for example, ultrasonic agitation, and the etching may include heating (360) the etching solution (124) and directing light (365) onto the silicon surface (116). During the etching, copper nanoparticles enhance or drive the etching process.

  20. Effect of cavity preparation method on microtensile bond strength of a self-etching primer vs phosphoric acid etchant to enamel.

    Science.gov (United States)

    de Souza-Zaroni, Wanessa Christine; Delfino, Carina Sinclér; Ciccone-Nogueira, Juliane Cristina; Palma-Dibb, Regina Guenka; Corona, Silmara Aparecida Milori

    2007-10-01

    This study evaluated the effect of cavity preparation using air abrasion or carbide bur on bond strength to enamel treated with a self-etching primer (Tyrian SPE) or a phosphoric acid etchant. Twenty-four molars were divided into three groups: high-speed; standard handpiece (ST air abrasion) or supersonic handpiece (SP air abrasion) of the same air-abrasive system. The enamel surfaces were treated with one of the two etchants and the same adhesive agent One Step Plus, and then composite buildups were done with Filtek Z250. After 24 h at 37 degrees C, beams (0.8 mm2) were obtained and subjected to tensile stress in a universal testing machine (0.5 mm/min). The data were submitted to analysis of variance and Tukey's test (P cavity preparation method was dependent on the conditioning system used, only when using carbide-bur preparation technique.

  1. Effect of bulk microstructure of commercially pure titanium on surface characteristics and fatigue properties after surface modification by sand blasting and acid-etching.

    Science.gov (United States)

    Medvedev, A E; Ng, H P; Lapovok, R; Estrin, Y; Lowe, T C; Anumalasetty, V N

    2016-04-01

    Surface modification techniques are widely used to enhance the biological response to the implant materials. These techniques generally create a roughened surface, effectively increasing the surface area thus promoting cell adhesion. However, a negative side effect is a higher susceptibility of a roughened surface to failure due to the presence of multiple stress concentrators. The purpose of the study reported here was to examine the effects of surface modification by sand blasting and acid-etching (SLA) on the microstructure and fatigue performance of coarse-grained and ultrafine-grained (UFG) commercially pure titanium. Finer grain sizes, produced by equal channel angular pressing, resulted in lower values of surface roughness in SLA-processed material. This effect was associated with greater resistance of the UFG structure to plastic deformation. The fatigue properties of UFG Ti were found to be superior to those of coarse-grained Ti and conventional Ti-6Al-4V, both before and after SLA-treatment.

  2. Etching of Crystalline ZnO Surfaces upon Phosphonic Acid Adsorption: Guidelines for the Realization of Well-Engineered Functional Self-Assembled Monolayers.

    Science.gov (United States)

    Ostapenko, Alexandra; Klöffel, Tobias; Eußner, Jens; Harms, Klaus; Dehnen, Stefanie; Meyer, Bernd; Witte, Gregor

    2016-06-01

    Functionalization of metal oxides by means of covalently bound self-assembled monolayers (SAMs) offers a tailoring of surface electronic properties such as their work function and, in combination with its large charge carrier mobility, renders ZnO a promising conductive oxide for use as transparent electrode material in optoelectronic devices. In this study, we show that the formation of phosphonic acid-anchored SAMs on ZnO competes with an unwanted chemical side reaction, leading to the formation of surface precipitates and severe surface damage at prolonged immersion times of several days. Combining atomic force microscopy (AFM), X-ray diffraction (XRD), and thermal desorption spectroscopy (TDS), the stability and structure of the aggregates formed upon immersion of ZnO single crystal surfaces of different orientations [(0001̅), (0001), and (101̅0)] in phenylphosphonic acid (PPA) solution were studied. By intentionally increasing the immersion time to more than 1 week, large crystalline precipitates are formed, which are identified as zinc phosphonate. Moreover, the energetics and the reaction pathway of this transformation have been evaluated using density functional theory (DFT), showing that zinc phosphonate is thermodynamically more favorable than phosphonic acid SAMs on ZnO. Precipitation is also found for phosphonic acids with fluorinated aromatic backbones, while less precipitation occurs upon formation of SAMs with phenylphosphinic anchoring units. By contrast, no precipitates are formed when PPA monolayer films are prepared by sublimation under vacuum conditions, yielding smooth surfaces without noticeable etching.

  3. Etch Figure on a Garnet Crystal Formed by Alkaline Reagents and Its Difference from That Formed by Acid Solution%石榴子石晶体碱腐蚀像及其与酸腐蚀像的对比

    Institute of Scientific and Technical Information of China (English)

    刘河清; 赵珊茸; 徐畅; 李坤

    2011-01-01

    In this paper, NaOH-KOH mixture of melt and KOH solution were used to corrode a garnet crystal. The etch figures on faces (or sections) with different crystallographic directions were observed, and a stereographic model of etch figures were established. The difference between the etch figures formed by HF solution and alkaline reagents on the same crystal face or section was also analyzed. It is indicated that both alkaline etching and acid etching can reflect the characteristics of the crystal symmetry. Comparison shows that alkaline etching figure is the same as acid etching figure on { 100 } and {110} , but alkaline etching figure is different from acid etching figure on { 120} , {221}、{ 111} and {211}. The study can be used for the crystallography orientation of garnet group minerals, and it is also be used to reveal the pH geological environment for garnet formation.%本文采用NaOH-KOH混合熔融物和KOH溶液对石榴子石晶体各种不同的结晶学方向的晶面(切面)进行腐蚀实验,建立了石榴子石碱腐蚀像的立体模型,并与酸(HF溶液)腐蚀像模型进行对比.研究发现碱腐蚀像与酸腐蚀像一样能很好的反映晶体的对称特点,并发现在{ 100}、{110}晶面(切面)上碱腐蚀像与酸腐蚀像相同,而在{120}、{221}、{111}、{211}晶面(切面)上,碱腐蚀像与酸腐蚀像不同.该研究可以用来对石榴子石族矿物进行结晶学定向,同时具有揭示矿物所处地质环境酸碱性的指示意义.

  4. Effects of xylitol on the acid production activity from sorbitol by Streptococcus mutans and human dental plaque.

    Science.gov (United States)

    Sasaki, N; Topitsoglou, V; Frostell, G

    1983-01-01

    -A method for the determination of acid production from 20-25 mg (wet weight) of Streptococcus mutans and 12-33 mg (wet weight) of human dental plaque is described. After endogenous acid production had been followed, either sorbitol or xylitol or a mixture of sorbitol and xylitol (2:1) was added. After about ten minutes glucose, sucrose or Palatinose were added for a vitality test. Addition of xylitol to the bacterial suspension caused inhibition of acid production from sorbitol by Streptococcus mutans grown on sorbitol or a mixture of sorbitol and glucose. It was also observed that it had a similar effect on acid production from sorbitol in suspensions of dental plaque with few exceptions. On the other hand, Streptococcus mutans cells grown on glucose, sucrose and xylitol media, produced no or insignificant amounts of acid from sorbitol. Streptococcus mutans cells grown on media containing glucose, sucrose, sorbitol and a mixture of sorbitol and glucose generally formed a large amount of acid from glucose and sucrose after the addition of sorbitol and xylitol. However, Streptococcus mutans cells grown on a medium containing xylitol and the mixture of sorbitol and xylitol formed less acid from glucose. The acid production activity from sorbitol in suspensions of dental plaque after the xylitol addition was somewhat lower than the acid production from sorbitol alone (p less than 0.02).

  5. Light-Cured Self-Etch Adhesives Undergo Hydroxyapatite-Triggered Self-Cure.

    Science.gov (United States)

    Liu, Y; Bai, X; Liu, Y W; Wang, Y

    2016-03-01

    Light cure is a popular mode of curing for dental adhesives. However, it suffers from inadequate light delivery when the restoration site is less accessible, in which case a self-cure mechanism is desirable to salvage any compromised polymerization. We previously reported a novel self-cure system mediated by ethyl 4-(dimethylamino)-benzoate (4E) and hydroxyapatite (HAp). The present work aims to investigate if such self-cure phenomenon takes place in adhesives that underwent prior inadequate light cure and to elucidate if HAp released from the dental etching process is sufficient to trigger it. Model self-etch adhesives were formulated with various components, including bis[2-methacryloyloxy)ethyl]-phosphate (2MP) as acidic monomer and trimethylbenzoyl-diphenylphosphine oxide (TPO) as photoinitiator. In vitro evolution of degree of conversion (DC) of HAp-incorporated adhesives was monitored by infrared spectroscopy during light irradiation and dark storage. Selected adhesives were allowed to etch and extract HAp from enamel, light-cured in situ, and stored in the dark, after which Raman line mapping was used to obtain spatially resolved DC across the enamel-resin interface. Results showed that TPO+4E adhesives reached DC similar to TPO-only counterparts upon completion of light irradiation but underwent another round of initiation that boosted DC to ~100% regardless of HAp level or prior light exposure. When applied to enamel, TPO-only adhesives had ~80% DC in resin, which gradually descended to ~50% in enamel, whereas TPO+4E adhesives consistently scored ~80% DC across the enamel-resin interface. These observations suggest that polymerization of adhesives that underwent insufficient light cure is salvaged by the novel self-cure mechanism, and such salvaging effect can be triggered by HAp released from dental substrate during the etching process.

  6. Comparison of alkaline phosphatase activity of MC3T3-E1 cells cultured on different Ti surfaces: modified sandblasted with large grit and acid-etched (MSLA), laser-treated, and laser and acid-treated Ti surfaces

    Science.gov (United States)

    Li, Lin-Jie; Kim, So-Nam

    2016-01-01

    PURPOSE In this study, the aim of this study was to evaluate the effect of implant surface treatment on cell differentiation of osteoblast cells. For this purpose, three surfaces were compared: (1) a modified SLA (MSLA: sand-blasted with large grit, acid-etched, and immersed in 0.9% NaCl), (2) a laser treatment (LT: laser treatment) titanium surface and (3) a laser and acid-treated (LAT: laser treatment, acid-etched) titanium surface. MATERIALS AND METHODS The MSLA surfaces were considered as the control group, and LT and LAT surfaces as test groups. Alkaline phosphatase expression (ALP) was used to quantify osteoblastic differentiation of MC3T3-E1 cell. Surface roughness was evaluated by a contact profilometer (URFPAK-SV; Mitutoyo, Kawasaki, Japan) and characterized by two parameters: mean roughness (Ra) and maximum peak-to-valley height (Rt). RESULTS Scanning electron microscope revealed that MSLA (control group) surface was not as rough as LT, LAT surface (test groups). Alkaline phosphatase expression, the measure of osteoblastic differentiation, and total ALP expression by surface-adherent cells were found to be highest at 21 days for all three surfaces tested (P.05). CONCLUSION This study suggested that MSLA and LAT surfaces exhibited more favorable environment for osteoblast differentiation when compared with LT surface, the results that are important for implant surface modification studies. PMID:27350860

  7. Morphological changes produced by acid dissolution in Er:YAG laser irradiated dental enamel.

    Science.gov (United States)

    Manuela Díaz-Monroy, Jennifer; Contreras-Bulnes, Rosalía; Fernando Olea-Mejía, Oscar; Emma Rodríguez-Vilchis, Laura; Sanchez-Flores, Ignacio

    2014-06-01

    Several scientific reports have shown the effects of Er:YAG laser irradiation on enamel morphology. However, there is lack of information regarding the morphological alterations produced by the acid attack on the irradiated surfaces. The aim of this study was to evaluate the morphological changes produced by acid dissolution in Er:YAG laser irradiated dental enamel. Forty-eight enamel samples were divided into four groups (n = 12). GI (control); Groups II, III, and IV were irradiated with Er:YAG at 100 mJ (12.7 J/cm(2) ), 200 mJ (25.5 J/cm(2) ), and 300 mJ (38.2 J/cm(2) ), respectively, at 10 Hz without water irrigation. Enamel morphology was evaluated before-irradiation, after-irradiation, and after-acid dissolution, by scanning electron microscopy (SEM). Sample coating was avoided and SEM analysis was performed in a low-vacuum mode. To facilitate the location of the assessment area, a reference point was marked. Morphological changes produced by acid dissolution of irradiated enamel were observed, specifically on laser-induced undesired effects. These morphological changes were from mild to severe, depending on the presence of after-irradiation undesired effects.

  8. Effect evaluation of phosphoric acid etching combined with flowable composite resin in pit and fissure sealant of young per-manent molars%磷酸酸蚀结合流动树脂对年轻恒牙窝沟封闭的疗效分析

    Institute of Scientific and Technical Information of China (English)

    谢妮娜; 宋文婷; 魏路明; 刘宗响

    2015-01-01

    Objective After the teeth were etched with 35%phosphoric acid,the first permanent molars were sealed by 3M flowable composite resin and common pit and fissure sealant so as to compare the retention rate and caries prevalence rate of dental caries by the two kinds of sealing material.Methods 240 permanent mandibular first molars with deep fissures and with no caries among 120 chil-dren of 7-9 years old were selected.The self export control method was used.According to the result of coin tossing,one side was cho-sen as the phosphoric acid +3M flowable resin group,and the other side the phosphoric acid etching +3M pit and fissure sealant group.After 3 months,6 months,12 months,and 24 months,pit and fissure sealant retention and caries rates were respectively exam-ined.Results In the 3rd and 6th months,pit and fissure sealant retention,and caries decrease rate between two groups were different with no statistical significance (P>0.05).In the 12th and 24th months,retention and caries decrease rates in the flowable composite resin group were higher than those in the pit and fissure sealant group,while caries incidence rate was lower than that in the pit and fis-sure sealant group.The differences were statistically significant (P<0.05).Conclusions The clinical effect of the phosphoric acid etching combined with flowable composite resin is better than that of phosphoric acid etching combined with pit and fissure sealant.The former method can increase retention rate of sealing materials,thus lowering prevalence rate of dental caries.%目的:比较3M流动树脂和3M窝沟封闭剂为第一恒磨牙行窝沟封闭术,2种材料窝沟封闭的保留率及龋病发生率情况。方法选择7~9岁120例240颗窝沟较深无龋的下颌第一恒磨牙,采用自身半口对照方法,掷币法随机选择一侧为3M流动树脂组,另一侧则为3M窝沟封闭剂组。于术后3、6、12、24个月复查,检查两组窝沟封闭材料的保留率和封闭后牙

  9. Effect of pre-etching on sealing ability of two current self-etching adhesives

    Directory of Open Access Journals (Sweden)

    K Khosravi

    2005-05-01

    Full Text Available Background: We evaluated the effect of phosphoric acid etching on microleakage of two current self-etching adhesives on enamel margins in comparison to a conventional total- etch system. Methods: Sixty buccal class V cavities were made at the cemento-enamel junction with beveled enamel margins of extracted human premolar teeth and randomly divided into five groups (12 specimens in each group. Group 1 was applying with Clearfil SE bond, Group 2 with 35% phosphoric acid etching of enamel margins plus Clearfil SE bond, Group3 with I bond, Group 4 with 35% phosphoric acid etching of enamel margins plus I bond and Group5 with Scotchbond multi-purpose. All groups restored with a composite resins. After 24 hours storage with 100% humidity, the samples were thermocycled, immersed in a dye solution and sectioned buccoligually and enamel margins microleakage were evaluated on a scale of 0 to 2. Results: The differences between Groups 1 & 3 and Groups 3 & 4 were significant (P<0.05 but no significant differences between Groups1 & 2 or 1 & 5 were observed. Conclusion: The findings suggest that all-in-one adhesive systems need pre-etching enamel margins with phosphoric acid for effectively seal. Key words: Self-Etching Adhesives, Microleakage, Enamel, Total-Etch system

  10. Novel Dental Cement to Combat Biofilms and Reduce Acids for Orthodontic Applications to Avoid Enamel Demineralization

    Directory of Open Access Journals (Sweden)

    Ning Zhang

    2016-05-01

    Full Text Available Orthodontic treatments often lead to biofilm buildup and white spot lesions due to enamel demineralization. The objectives of this study were to develop a novel bioactive orthodontic cement to prevent white spot lesions, and to determine the effects of cement compositions on biofilm growth and acid production. 2-methacryloyloxyethyl phosphorylcholine (MPC, nanoparticles of silver (NAg, and dimethylaminohexadecyl methacrylate (DMAHDM were incorporated into a resin-modified glass ionomer cement (RMGI. Enamel shear bond strength (SBS was determined. Protein adsorption was determined using a micro bicinchoninic acid method. A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate metabolic activity, colony-forming units (CFU and lactic acid production. Incorporating 3% of MPC, 1.5% of DMAHDM, and 0.1% of NAg into RMGI, and immersing in distilled water at 37 °C for 30 days, did not decrease the SBS, compared to control (p > 0.1. RMGI with 3% MPC + 1.5% DMAHDM + 0.1% NAg had protein amount that was 1/10 that of control. RMGI with triple agents (MPC + DMAHDM + NAg had much stronger antibacterial property than using a single agent or double agents (p < 0.05. Biofilm CFU on RMGI with triple agents was reduced by more than 3 orders of magnitude, compared to commercial control. Biofilm metabolic activity and acid production were also greatly reduced. In conclusion, adding MPC + DMAHDM + NAg in RMGI substantially inhibited biofilm viability and acid production, without compromising the orthodontic bracket bond strength to enamel. The novel bioactive cement is promising for orthodontic applications to hinder biofilms and plaque buildup and enamel demineralization.

  11. Acid demineralization susceptibility of dental enamel submitted to different bleaching techniques and fluoridation regimens.

    Science.gov (United States)

    Salomão, Dlf; Santos, Dm; Nogueira, Rd; Palma-Dibb, Rg; Geraldo-Martins, Vr

    2014-01-01

    The aim of the current study was to assess the acid demineralization susceptibility of bleached dental enamel submitted to different fluoride regimens. One hundred bovine enamel blocks (6×6×3 mm) were randomly divided into 10 groups (n=10). Groups 1 and 2 received no bleaching. Groups 3 to 6 were submitted to an at-home bleaching technique using 6% hydrogen peroxide (HP; G3 and G4) or 10% carbamide peroxide (CP; G5 and G6). Groups 7 to 10 were submitted to an in-office bleaching technique using 35% HP (G7 and G8) or 35% CP (G9 and G10). During bleaching, a daily fluoridation regimen of 0.05% sodium fluoride (NaF) solution was performed on groups 3, 5, 7, and 9, while weekly fluoridation with a 2% NaF gel was performed on groups 4, 6, 8, and 10. The samples in groups 2 to 10 were pH cycled for 14 consecutive days. The samples from all groups were then assessed by cross-sectional Knoop microhardness at different depths from the outer enamel surface. The average Knoop hardness numbers (KHNs) were compared using one-way analysis of variance and Tukey tests (α=0.05). The comparison between groups 1 and 2 showed that the demineralization method was effective. The comparison among groups 2 to 6 showed the same susceptibility to acid demineralization, regardless of the fluoridation method used. However, the samples from groups 8 and 10 showed more susceptibility to acid demineralization when compared with group 2 (penamel to acid demineralization. However, the use of 35% HP and 35% CP must be associated with a daily fluoridation regimen, otherwise the in-office bleaching makes the bleached enamel more susceptible to acid demineralization.

  12. Autogenous bone graft combined with polylactic polyglycolic acid polymer for treatment of dehiscence around immediate dental implants.

    Science.gov (United States)

    Hassan, Khalid S

    2009-11-01

    The use of composite bone grafts in dehiscence defects around immediate dental implants are aimed at improving the outcome of the regenerative process. The present study was designed to evaluate the efficacy of combinations of autogenous bone graft with a synthetic copolymer polylactic and polyglycolic acid (Fisiograft) on bone healing of buccal dehiscence defects around immediate dental implants. Sixteen adult male patients who each received an immediate implant for a single tooth replacement at a maxillary anterior or premolar site were included in this study. Patients were divided into 2 groups. One group received immediate dental implants augmented with autogenous bone graft combined with Fisiograft. The other group received immediate dental implants augmented with autogenous bone graft alone. The results revealed that both treatment modalities led to significant improvements for the primary outcome regarding bone fill as well as a significant reduction of probing pocket depth and gain of attachment level. Moreover, there were slightly statistically significant differences between the groups. In conclusion, the combination of autogenous bone graft and Fisiograft showed a slight superiority to autogenous bone graft alone, suggesting that it could be an optimum bone substitute for treatment of dehiscence around immediate dental implant.

  13. Catalyst-referred etching of silicon

    Directory of Open Access Journals (Sweden)

    Hideyuki Hara et al

    2007-01-01

    Full Text Available A Si wafer and polysilicon deposited on a Si wafer were planarized using catalyst-referred etching (CARE. Two apparatuses were produced for local etching and for planarization. The local etching apparatus was used to planarize polysilicon and the planarization apparatus was used to planarize Si wafers. Platinum and hydrofluoric acid were used as the catalytic plate and the source of reactive species, respectively. The processed surfaces were observed by optical interferometry, atomic force microscopy (AFM and scanning electron microscopy (SEM. The results indicate that the CARE-processed surface is flat and undamaged.

  14. State of the art etch-and-rinse adhesives

    OpenAIRE

    Pashley, David H.; Tay, Franklin R.; Breschi, Lorenzo; Tjäderhane, Leo; Carvalho, Ricardo M.; Carrilho, Marcela; Tezvergil-Mutluay, Arzu

    2010-01-01

    Etch-and-rinse adhesive systems are the oldest of the multi-generation evolution of resin bonding systems. In the 3-step version, they involve acid-etching, priming and application of a separate adhesive. Each step can accomplish multiple goals. This review explores the therapeutic opportunities of each separate step. Acid-etching, using 32-37% phosphoric acid (pH 0.1-0.4) not only simultaneously etches enamel and dentin, but the low pH kills many residual bacteria. Some etchants include anti...

  15. Effect of Etching Time and Preparation on Push-Out Bond Strength of Composite to Intracanal Dentin of Primary Anterior Teeth

    Directory of Open Access Journals (Sweden)

    Shahram Mosharrafian

    2016-12-01

    Full Text Available Objectives: This in-vitro study aimed to compare the push-out bond strength of composite to prepared and unprepared intracanal dentin using a 5th generation bonding agent in primary anterior teeth after etching for seven and 15 seconds.Materials and Methods: Sixty primary anterior teeth were randomly divided into four groups. In groups one and two, intracanal dentin remained intact while in groups three and four it was prepared using a #5 round bur and low-speed handpiece. Single Bond 2 was used in groups one and three after 15 seconds and in groups two and four after seven seconds of etching with phosphoric acid. After restoring with composite resin and incubation, the specimens were subjected to push-out bond strength test. Data were analyzed using two-way ANOVA and Kaplan Meier curves.Results: The mean bond strength was not significantly different between seven and 15 seconds etching times (P=0.198. Dentin preparation had no significant effect on the mean bond strength (P=0.838. The interaction effect of etching time and dentin preparation was not significant either (P=0.680.Conclusions: Decreasing the etching time from 15 to seven seconds and preparation of intracanal dentin had no significant effect on push-out bond strength of composite to intracanal dentin of primary anterior teeth. Keywords: Dental Etching; Composite Resins; Dentin; Tooth, Deciduous

  16. Resistance to fracture of endodontically treated premolars restored with glass ionomer cement or acid etch composite resin: An in vitro study

    Directory of Open Access Journals (Sweden)

    B Ranga

    2010-01-01

    Full Text Available Aim: Due to the weakness of endodontically treated posterior teeth requires more strengthened restoration to withstand occlusal forces. The purpose of the present study was to determine and compare the resistance to fracture of endodontically treated maxillary 1 st premolars restored with different materials in mesio-occluso-distal (MOD cavity preparations. Materials and Methods: MOD cavity preparations in 80 endodontically treated maxillary 1 st premolars were restored using four different methods. Fiber rings were filled with stone plaster and the teeth were placed into the plaster up to the level of cemento-enamel junction. The teeth were grouped according to restorative method, mounted in an Instrom T.T. machine, and the buccal walls subjected to a slowly increasing compressive force until fracture occurred. Result: The force of fracture of the walls of each tooth was recorded and the results in the various groups compared. All teeth fractured in a similar manner irrespective of the restorative method used. Conclusion: The resistance to the fracture of the teeth was the same when they were stored with glass ionomer cement as a base over which composite resin was placed. When the entire cavities were filled with glass ionomer cement, the resistance to fracture of the teeth decreased significantly compared with the acid etch resin technique.

  17. Effects of rhBMP-2 on Sandblasted and Acid Etched Titanium Implant Surfaces on Bone Regeneration and Osseointegration: Spilt-Mouth Designed Pilot Study

    Directory of Open Access Journals (Sweden)

    Nam-Ho Kim

    2015-01-01

    Full Text Available This study was conducted to evaluate effects of rhBMP-2 applied at different concentrations to sandblasted and acid etched (SLA implants on osseointegration and bone regeneration in a bone defect of beagle dogs as pilot study using split-mouth design. Methods. For experimental groups, SLA implants were coated with different concentrations of rhBMP-2 (0.1, 0.5, and 1 mg/mL. After assessment of surface characteristics and rhBMP-2 releasing profile, the experimental groups and untreated control groups (n = 6 in each group, two animals in each group were placed in split-mouth designed animal models with buccal open defect. At 8 weeks after implant placement, implant stability quotients (ISQ values were recorded and vertical bone height (VBH, mm, bone-to-implant contact ratio (BIC, %, and bone volume (BV, % in the upper 3 mm defect areas were measured. Results. The ISQ values were highest in the 1.0 group. Mean values of VBH (mm, BIC (%, and BV (% were greater in the 0.5 mg/mL and 1.0 mg/mL groups than those in 0.1 and control groups in buccal defect areas. Conclusion. In the open defect area surrounding the SLA implant, coating with 0.5 and 1.0 mg/mL concentrations of rhBMP-2 was more effective, compared with untreated group, in promoting bone regeneration and osseointegration.

  18. Radiation induced deposition of copper nanoparticles inside the nanochannels of poly(acrylic acid)-grafted poly(ethylene terephthalate) track-etched membranes

    Science.gov (United States)

    Korolkov, Ilya V.; Güven, Olgun; Mashentseva, Anastassiya A.; Atıcı, Ayse Bakar; Gorin, Yevgeniy G.; Zdorovets, Maxim V.; Taltenov, Abzal A.

    2017-01-01

    Poly(ethylene terephthalate) PET, track-etched membranes (TeMs) with 400 nm average pore size were UV-grafted with poly(acrylic acid) (PAA) after oxidation of inner surfaces by H2O2/UV system. Carboxylate groups of grafted PAA chains were easily complexed with Cu2+ ions in aqueous solutions. These ions were converted into metallic copper nanoparticles (NPs) by radiation-induced reduction of copper ions in aqueous-alcohol solution by gamma rays in the dose range of 46-250 kGy. Copper ions chelating with -COOH groups of PAA chains grafted on PET TeMs form polymer-metal ion complex that prevent the formation of agglomerates during reduction of copper ions to metallic nanoparticles. The detailed analysis by X-Ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the deposition of copper nanoparticles with the average size of 70 nm on the inner surface of nanochannels of PET TeMs. Samples were also investigated by FTIR, ESR spectroscopies to follow copper ion reduction.

  19. Early bone response to machined, sandblasting acid etching (SLA) and novel surface-functionalization (SLAffinity) titanium implants: characterization, biomechanical analysis and histological evaluation in pigs.

    Science.gov (United States)

    Chiang, Hsi-Jen; Hsu, Heng-Jui; Peng, Pei-Wen; Wu, Ching-Zong; Ou, Keng-Liang; Cheng, Han-Yi; Walinski, Christopher J; Sugiatno, Erwan

    2016-02-01

    The purpose of the present study was to examine early tissue response and osseointegration in the animal model. The surface morphologies of SLAffinity were characterized using scanning electron microscopy and atomic force microscopy. The microstructures were examined by X-ray diffraction, and hardness was measured by nanoindentation. Moreover, the safety and toxicity properties were evaluated using computer-aided programs and cell cytotoxicity assays. In the animal model, implants were installed in the mandibular canine-premolar area of 12 miniature pigs. Each pig received three implants: machine, sandblasted, large grit, acid-etched, and SLAffinity-treated implants. The results showed that surface treatment did affect bone-to-implant contact (BIC) significantly. At 3 weeks, the SLAffinity-treated implants were found to present significantly higher BIC values than the untreated implants. The SLAffinity treatments enhanced osseointegration significantly, especially at early stages of bone tissue healing. As described above, the results of the present study demonstrate that the SLAffinity treatment is a reliable surface modification method.

  20. Screening of a model for the distribution of dye in dye-encapsulated silica through the gradual etching of the outermost silica layer using hydrofluoric acid.

    Science.gov (United States)

    Wi, Rinbok; Lee, Kyoung G; Yoon, Sun Hong; Lee, Sang Geun; Imran, Muhammad; Kim, Do Hyun

    2011-07-01

    Monodispersed spherical silica particles emitting blue light were prepared by incorporating 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene (BBOT) into a silica matrix. The morphological and photoluminescent properties were investigated to confirm the proper incorporation of BBOT into the silica matrix, using an electron microscope and a fluorescence spectrometer. Four possible models representing the distribution of the dye molecules in a dye-encapsulated silica particle were proposed. To analyze the distribution of the BBOT dye in the BBOT-encapsulated silica, the fluorescent emission intensity was measured while reducing the particle diameter by etching the outermost silica layer with hydrofluoric acid with 0-0.5 wt.% concentrations. The distribution of BBOT in a silica particle was investigated based on the relationship between the changes in particle diameter and the changes in emission intensity. The emission intensity of the BBOT-encapsulated silica particle oscillated with the decreasing particle diameter. This result supported the multilayered model. Information regarding the distribution of the dye in the silica matrix will provide valuable information for understanding the formation mechanism of dye-encapsulated silica.

  1. Improve the Properties of p-i-n α-Si:H Thin-Film Solar Cells Using the Diluted Hydrochloric Acid-Etched GZO Thin Films

    Directory of Open Access Journals (Sweden)

    Fang-Hsing Wang

    2013-01-01

    Full Text Available Gallium-doped zinc oxide (GZO thin films were deposited on glass, and the process parameters are RF power of 50 W and working pressure of 5 mTorr, and the substrate temperature was changed from room temperature to 300°C. At first, the thickness was around 300 nm by controlling the deposition time. The effects of substrate temperature on the crystallinity, lattice constant (c, carrier mobility, carrier concentration, resistivity, and optical transmission rate of the GZO thin films were studied. The 200°C-deposited GZO thin films had the best crystallinity, the larger carrier concentration and carrier mobility, and the lowest resistivity. For that, the thickness of the GZO thin films was extended to around 1000 nm. Hydrochloric (HCl acid solutions with different concentrations (0.1%, 0.2%, and 0.5% were used to etch the surfaces of the GZO thin films, which were then used as the substrate electrodes to fabricate the p-i-n α-Si:H thin-film solar cells. The haze ratio of the GZO thin films increased with increasing HCl concentration, and that would effectively enhance light trapping inside the absorber material of solar cells and then improve the efficiency of the fabricated thin-film solar cells.

  2. Er:YAG laser radiation etching of enamel

    Science.gov (United States)

    Dostalova, Tatjana; Jelinkova, Helena; Krejsa, Otakar; Hamal, Karel; Kubelka, Jiri; Prochazka, Stanislav

    1996-12-01

    This study compares the effects of acid treatment and Er:YAG laser radiation on the enamel. The permanent human molars were used. Oval cavities in the buccal surface were prepared and the edges of cavities were irradiated by Er:YAG radiation. The energy of laser was 105 mJ and repetition rate 1 Hz. The radiation was focused by CaF2 lens and the sample was placed in the focus. Ten samples were etched by 35 percent phosphoric acid during 60 s. Than cavities were filled with composite resin following manufacturers directions. By laser etching the structure enamel in section was rougher. The optimal connection between the enamel and composite resin was achieved in 75 percent by acid etching and in 79.2 percent by Er:YAG laser etching. Er:YAG laser etching could be alternative method for etching of enamel.

  3. 24% Indigenously Prepared Ethylene Diamine Tetra Acetic Acid Compared to Self-Etching Adhesives and their Effect on Shear Bond Strength of Composites in Primary Teeth: An In-vitro Study

    OpenAIRE

    Nagar, Priya; Tandil, Yogesh L.; T.P., Chandru; Gupta, Anamika; Kalaria, Devendra; Kumar, Prafful

    2015-01-01

    Background: Over the years, it has been known that 34% phosphoric acid is the benchmark in etchants with the best shear bond strength shown with composites in primary teeth. However, with latest technological advancements and innovations, in order to reduce the number of steps and less damage to the tooth structure, non-rinse conditioner (NRC) & Single-Etch and various other etchants have been tried and tested. These etchants have been found to have shear bond strength comparable to phosphori...

  4. Regulation of Osteoblast Differentiation by Acid-Etched and/or Grit-Blasted Titanium Substrate Topography Is Enhanced by 1,25(OH)2D3 in a Sex-Dependent Manner.

    Science.gov (United States)

    Olivares-Navarrete, Rene; Hyzy, Sharon L; Boyan, Barbara D; Schwartz, Zvi

    2015-01-01

    This study assessed contributions of micron-scale topography on clinically relevant titanium (Ti) to differentiation of osteoprogenitor cells and osteoblasts; the interaction of this effect with 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3); and if the effects are sex-dependent. Male and female rat bone marrow cells (BMCs) were cultured on acid-etched (A, R a = 0.87 μm), grit-blasted (GB, R a = 3.90 μm), or grit-blasted/acid-etched (SLA, R a = 3.22 μm) Ti. BMCs were sensitive to surface topography and underwent osteoblast differentiation. This was greatest on SLA; acid etching and grit blasting contributed additively. Primary osteoblasts were also sensitive to SLA, with less effect from individual structural components, demonstrated by enhanced local factor production. Sex-dependent responses of BMCs to topography varied with parameter whereas male and female osteoblasts responded similarly to surface treatment. 1α,25(OH)2D3 enhanced cell responses on all surfaces similarly. Effects were sex-dependent and male cells grown on a complex microstructured surface were much more sensitive than female cells. These results indicate that effects of the complex SLA topography are greater than acid etching or grit blasting alone on multipotent BMCs and committed osteoblasts and that individual parameters are sex-specific. The effect of 1α,25(OH)2D3 was sex dependent. The results also suggest that levels of 1α,25(OH)2D3 in the patient may be important in osseointegration.

  5. Nanoparticle-based etching of silicon surfaces

    Science.gov (United States)

    Branz, Howard; Duda, Anna; Ginley, David S.; Yost, Vernon; Meier, Daniel; Ward, James S.

    2011-12-13

    A method (300) of texturing silicon surfaces (116) such to reduce reflectivity of a silicon wafer (110) for use in solar cells. The method (300) includes filling (330, 340) a vessel (122) with a volume of an etching solution (124) so as to cover the silicon surface 116) of a wafer or substrate (112). The etching solution (124) is made up of a catalytic nanomaterial (140) and an oxidant-etchant solution (146). The catalytic nanomaterial (140) may include gold or silver nanoparticles or noble metal nanoparticles, each of which may be a colloidal solution. The oxidant-etchant solution (146) includes an etching agent (142), such as hydrofluoric acid, and an oxidizing agent (144), such as hydrogen peroxide. Etching (350) is performed for a period of time including agitating or stirring the etching solution (124). The etch time may be selected such that the etched silicon surface (116) has a reflectivity of less than about 15 percent such as 1 to 10 percent in a 350 to 1000 nanometer wavelength range.

  6. Plasma etching an introduction

    CERN Document Server

    Manos, Dennis M

    1989-01-01

    Plasma etching plays an essential role in microelectronic circuit manufacturing. Suitable for researchers, process engineers, and graduate students, this book introduces the basic physics and chemistry of electrical discharges and relates them to plasma etching mechanisms. Throughout the volume the authors offer practical examples of process chemistry, equipment design, and production methods.

  7. Improvement of multicrystalline silicon wafer solar cells by post-fabrication wet-chemical etching in phosphoric acid

    Indian Academy of Sciences (India)

    A Mefoued; M Fathi; J Bhatt; A Messaoud; B Palahouane; N Benrekaa

    2011-12-01

    In this study, we have improved electrical characteristics such as the efficiency () and the fill factor (FF) of finished multicrystalline silicon (-Si) solar cells by using a new chemical treatment with a hot phosphoric (H3PO4) acidic solution. These -Si solar cells were made by a standard industrial process with screen-printed contacts and a silicon nitride (SiN) antireflection coating. We have deposited SiN thin layer (80 nm) on -type -Si substrate by the mean of plasma enhanced chemical vapour deposition (PECVD) technique. The reactive gases used as precursors inside PECVD chamber are a mixture of silane (SiH4) and ammonia (NH3) at a temperature of 380°C. The developed H3PO4 chemical surface treatment has improved from 5.4 to 7.7% and FF from 50.4 to 70.8%, this means a relative increase of up to 40% from the initial values of and FF. In order to explain these improvements, physical (AFM, EDX), chemical (FTIR) and optical (spectrophotometer) analyses were done.

  8. Characterization of Dentine to Assess Bond Strength of Dental Composites

    Directory of Open Access Journals (Sweden)

    Saad Liaqat

    2015-04-01

    Full Text Available This study was performed to develop alternating dentine adhesion models that could help in the evaluation of a self-bonding dental composite. For this purpose dentine from human and ivory was characterized chemically and microscopically before and after acid etching using Raman and SEM. Mechanical properties of dentine were determined using 3 point bend test. Composite bonding to dentine, with and without use of acid pre-treatment and/or the adhesive, were assessed using a shear bond test. Furthermore, micro gap formation after restoration of 3 mm diameter cavities in dentine was assessed by SEM. Initial hydroxyapatite level in ivory was half that in human dentine. Surface hydroxyapatites decreased by approximately half with every 23 s of acid etch. The human dentine strength (56 MPa was approximately double that of ivory, while the modulus was almost comparable to that of ivory. With adhesive use, average shear bond strengths were 30 and 26 MPa with and without acid etching. With no adhesive, average bond strength was 6 MPa for conventional composites. This, however, increased to 14 MPa with a commercial flowable “self–bonding” composite or upon addition of low levels of an acidic monomer to the experimental composite. The acidic monomer additionally reduced micro-gap formation with the experimental composite. Improved bonding and mechanical properties should reduce composite failures due to recurrent caries or fracture respectively.

  9. Inhibition of matrix metalloproteinases expression in human dental pulp cells by all-trans retinoic acid

    Institute of Scientific and Technical Information of China (English)

    Jin Man Kim; Sang Wook Kang; Su-Mi Shin; Duck Su Kim; Kyong-Kyu Choi; Eun-Cheol Kim; Sun-Young Kim

    2014-01-01

    All-trans retinoic acid (ATRA) inhibits matrix metalloproteinase (MMP)-2 and MMP-9 in synovial fibroblasts, skin fibroblasts, bronchoalveolar lavage cells and cancer cells, but activates MMP-9 in neuroblast and leukemia cells. Very little is known regarding whether ATRA can activate or inhibit MMPs in human dental pulp cells (HDPCs). The purpose of this study was to determine the effects of ATRA on the production and secretion of MMP-2 and-9 in HDPCs. The productions and messenger RNA (mRNA) expressions of MMP-2 and-9 were accessed by gelatin zymography and real-time polymerase chain reaction (PCR), respectively. ATRA was found to decrease MMP-2 level in a dose-dependent manner. Significant reduction in MMP-2 mRNA expression was also observed in HDPCs treated with 25 mmol?L21 ATRA. However, HDPCs treated with ATRA had no effect on the pattern of MMP-9 produced or secreted in either cell extracts or conditioned medium fractions. Taken together, ATRA had an inhibitory effect on MMP-2 expression in HDPCs, which suggests that ATRA could be a candidate as a medicament which could control the inflammation of pulp tissue in vital pulp therapy and regenerative endodontics.

  10. Weaker dental enamel explains dental decay.

    Science.gov (United States)

    Vieira, Alexandre R; Gibson, Carolyn W; Deeley, Kathleen; Xue, Hui; Li, Yong

    2015-01-01

    Dental caries continues to be the most prevalent bacteria-mediated non-contagious disease of humankind. Dental professionals assert the disease can be explained by poor oral hygiene and a diet rich in sugars but this does not account for caries free individuals exposed to the same risk factors. In order to test the hypothesis that amount of amelogenin during enamel development can influence caries susceptibility, we generated multiple strains of mice with varying levels of available amelogenin during dental development. Mechanical tests showed that dental enamel developed with less amelogenin is "weaker" while the dental enamel of animals over-expressing amelogenin appears to be more resistant to acid dissolution.

  11. Chemical etching of deformation sub-structures in quartz

    Science.gov (United States)

    Wegner, M. W.; Christie, J. M.

    1983-02-01

    Chemical etching of dislocations has been studied in natural and synthetic quartz single crystals, in deformed synthetic quartz and in naturally and experimentally deformed quartzites. The ability of different etchants to produce polished or preferentially etched surfaces on quartz is described. Dislocation etching was achieved on all crystal planes examined by using a saturated solution of ammonium bifluoride as the etchant. Appropriate etching times were determined for etching quartzites for grain size, subgrain boundaries, deformation lamellae, dislocations and twins. Growth and polished surfaces of synthetic single crystal quartz were similarly etched and dislocation etch pits, characteristic of various orientations were found. The use of ammonium bifluoride proved to be expecially advantageous for the basal plane, producing a polished surface with etch pits, suitable for dislocation etch pit counting. “Double” etch pits have been found on Dauphiné twin boundaries on the basal plane and the first order prism, using this etchant. Slip lines and deformation bands were suitably etched on deformed synthetic crystal surfaces for identification of the slip planes. Other acidic etchants have been explored and their application to the study of deformation structures in quartz crystals is discussed.

  12. Theoretical models of mercury dissolution from dental amalgams in neutral and acidic flows

    Science.gov (United States)

    Keanini, Russell G.; Ferracane, Jack L.; Okabe, Toru

    2001-06-01

    This article reports an experimental and theoretical investigation of mercury dissolution from dental amalgams immersed in neutral (noncorrosive) and acidic (corrosive) flows. Atomic absorption spectrophotometric measurements of Hg loss indicate that in neutral flow, surface oxide films formed in air prior to immersion persist and effectively suppress significant mercury release. In acidic (pH 1) flows, by contrast, oxide films are unstable and dissolve; depending on the amalgam’s material composition, particularly its copper content, two distinct mercury release mechanisms are initiated. In low copper amalgam, high initial mercury release rates are observed and appear to reflect preferential mercury dissolution from unstable Sn8Hg ( γ 2) grains within the amalgam matrix. In high copper amalgam, mercury release rates are initially low, but increase with time. Microscopic examination suggests that this feature reflects corrosion of copper from grains of Cu6Sn5 ( η') and consequent exposure of Ag2Hg3 ( γ 1) grains; the latter serve as internal mercury release sites and become more numerous as corrosion proceeds. Three theoretical models are proposed in order to explain observed dissolution characteristics. Model I, applicable to high and low copper amalgams in neutral flow, assumes that mercury dissolution is mediated by solid diffusion within the amalgam, and that a thin oxide film persists on the amalgam’s surface and lumps diffusive in-film transport into an effective convective boundary condition. Model II, applicable to low copper amalgam in acidic flow, assumes that the amalgam’s external oxide film dissolves on a short time scale relative to the experimental observation period; it neglects corrosive suppression of mercury transport. Model III, applicable to high copper amalgam in acidic flow, assumes that internal mercury release sites are created by corrosion of copper in η' grains and that corrosion proceeds via an oxidation-reduction reaction

  13. A macro- and nanostructure evaluation of a novel dental implant.

    Science.gov (United States)

    Tetè, Stefano; Mastrangelo, Filiberto; Traini, Tonino; Vinci, Raffaele; Sammartino, Gilberto; Marenzi, Gaetano; Gherlone, Enrico

    2008-09-01

    Success in implant dentistry also comes from the implant macrodesign and nanostructure of its surface. Titanium implant surface treatments have been shown to enhance osseointegration, maximize bone healing, and bone-to-implant contact for predictable clinical results. The aim of the study, was to evaluate the geometric macrodesign and the surface nanostructure of a novel dental implant full contact covering (FCC) obtained by electrochemical procedures. FCC implants were analyzed by scanning electronic microscope, profilometer, and x-ray photoelectron spectroscopy and compared with commercial sandblasted and sandblasted, large-grit acid-etched dental implants. Sample analysis allowed to distinguish the different implant macrodesigns, the step and the profile of the coils that cover the fixture, and the surface characteristics. FCC implant showed novel macro-characteristic of crestal module, coils, and apical zone compared with sandblasted and sandblasted and acid-etched dental implants. Moreover, the FCC nanostructure surface showed roughness values statistically higher than the 2 other surfaces, with a more homogeneity in a peaks and valleys arrangement. Finally, the x-ray photoelectron spectroscopy analysis detected differences between the examined surfaces, with the presence of several contaminants according to the different treatment procedures. Research on new macrostructures and nano morphology should result in a better qualitative and quantitative osseointegration response, with a predictability of the clinical results and long-term success of the implants.

  14. Etching in microsystem technology

    CERN Document Server

    Kohler, Michael

    2008-01-01

    Microcomponents and microdevices are increasingly finding application in everyday life. The specific functions of all modern microdevices depend strongly on the selection and combination of the materials used in their construction, i.e., the chemical and physical solid-state properties of these materials, and their treatment. The precise patterning of various materials, which is normally performed by lithographic etching processes, is a prerequisite for the fabrication of microdevices.The microtechnical etching of functional patterns is a multidisciplinary area, the basis for the etching p

  15. Dry etching for microelectronics

    CERN Document Server

    Powell, RA

    1984-01-01

    This volume collects together for the first time a series of in-depth, critical reviews of important topics in dry etching, such as dry processing of III-V compound semiconductors, dry etching of refractory metal silicides and dry etching aluminium and aluminium alloys. This topical format provides the reader with more specialised information and references than found in a general review article. In addition, it presents a broad perspective which would otherwise have to be gained by reading a large number of individual research papers. An additional important and unique feature of this book

  16. Feasibility of hydrofluoric acid etched sand particles for enrichment and determination of polychlorinated biphenyls at trace levels in environmental water samples.

    Science.gov (United States)

    Xing, Han-Zhu; Chen, Xiang-Feng; Wang, Xia; Wang, Ming-Lin; Zhao, Ru-Song

    2014-06-01

    This study aims to investigate the feasibility of etched sand particles being used as solid-phase extraction adsorbents to enrich polychlorinated biphenyls (PCBs), which are typical persistent organic pollutants in the environment, at trace levels. Gas chromatography-tandem mass spectrometry was selected to detect the compounds. Etched sand particles exhibited excellent merits on the enrichment of PCBs. Related important factors affecting extraction efficiencies were investigated and optimized in detail. Under optimized conditions, low limits of detection (0.42 to 3.69 ng L(-1)), wide linear range (10 to 1,000 ng L(-1)), and high repeatability (1.9 to 8.2%) were achieved. The developed method was validated with several real water samples, and satisfactory results were obtained. All of these findings indicate that etched sand particles would be useful for the enrichment and determination of organic pollutants at trace levels in water samples.

  17. ent-Kaurenoic acid-rich extract from Mikania glomerata: In vitro activity against bacteria responsible for dental caries.

    Science.gov (United States)

    Moreira, Monique Rodrigues; Souza, Ariana Borges; Soares, Sandra; Bianchi, Thamires Chiquini; de Souza Eugênio, Daniele; Lemes, Danieli Cristina; Martins, Carlos Henrique Gomes; da Silva Moraes, Thaís; Tavares, Denise Crispim; Ferreira, Natália Helen; Ambrósio, Sergio Ricardo; Veneziani, Rodrigo Cassio Sola

    2016-07-01

    Many studies have reported that medicinal plant extracts can inhibit oral pathogen growth or adhesion to surfaces and therefore reduce dental caries formation. The addition of these extracts to oral products like mouthwashes and dentifrices is considered an important strategy in caries control. In this sense, we have developed a Mikania glomerata extract with high ent-kaurenoic acid content (KAMg). So, this work describes the preparation of such extract and the development of a validated HPLC-DAD method to determine its ent-kaurenoic acid (KA) content. Herein it is also described the KAMg in vitro antibacterial evaluation against several cariogenic bacteria in comparison with KA and the investigation of further aspects of the KAMg activity. Toxicological aspects of the developed extract were evaluated by assessing its cytotoxicity and genotoxicity. KA and a KA-rich extract like KAMg showed to inhibit the growth of microorganisms responsible for dental caries at relatively low MIC (Minimum inhibitory concentration) values, albeit not as low as the MIC value obtained for chlorhexidine digluconate (CHD), the golden anticariogenic standard approved by the American Dental Association Council on Dental Therapeutics. However, KAMg was more effective to inhibit the formation of a Streptococcus mutans biofilm with four times lower MICB50 (minimum inhibitory concentration that reduces 50% of the biofilm) value as compared with CHD. Taking into account all these data and considering the absence of genotoxic and cytotoxic activity under the tested conditions, it is suggested that KAMg is a natural product to be considered as active ingredient in oral care products.

  18. Dentin diffusion of HEMA released from etch-and-rinse and self-etch bonding systems.

    Science.gov (United States)

    Rathke, Andreas; Alt, Andreas; Gambin, Nadin; Haller, Bernd

    2007-12-01

    The aim of this in vitro study was to determine the diffusion of 2-hydroxyethyl methacrylate (HEMA) released from different bonding systems (BS) through dentin. Occlusal cavities with a remaining dentin thickness (RDT) of 0.5 mm (n=90) and 0.25 mm (n=80), respectively, were prepared in dentin discs of non-carious human molars. Artificial pulp chambers were attached to the pulpal side of each dentin disc. Bonding systems were applied with (Clearfil SE Bond, OptiBond FL, OptiBond Solo Plus) or without (AdheSE, Adper Prompt L-Pop, Clearfil SE Bond, OptiBond FL, OptiBond Solo Plus Self Etch, Xeno III) prior phosphoric acid etching. HEMA was detected by gas chromatography/mass spectrometry (n=10 per BS and RDT). The highest mean HEMA concentration was found in the 0.25 mm RDT group treated with OptiBond FL (13.3 microg) and the lowest mean HEMA concentration was detected in the 0.5 mm RDT group treated with AdheSE (0.5 microg). At 0.25 mm RDT the quantities of HEMA recovered in the artificial pulp chambers were significantly higher than at 0.5 mm RDT, except for Clearfil SE Bond. Etching with phosphoric acid increased the detected HEMA quantities compared with self-etch BS. In deep cavity preparations, etching with phosphoric acid should be avoided in favor of the use of self-etch BS.

  19. Dental Amalgam

    Science.gov (United States)

    ... and Medical Procedures Dental Devices Dental Amalgam Dental Amalgam Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Dental amalgam is a dental filling material which is used ...

  20. Optimization of roughness, reflectance and photoluminescence for acid textured mc-Si solar cells etched at different HF/HNO{sub 3} concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Diaz, B. [Departamento de Fisica Basica, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Guerrero-Lemus, R. [Departamento de Fisica Basica, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Fundacion de Estudios de Economia Aplicada. Catedra Focus-Abengoa. Jorge Juan, 46, 28001 Madrid (Spain)], E-mail: rglemus@ull.es; Diaz-Herrera, B.; Marrero, N. [Departamento de Fisica Basica, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Mendez-Ramos, J.; Borchert, Dietmar [Departamento de Fisica Fundamental, Experimental Electronica y Sistemas, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Labour und Servicecentre, Institut fuer Solare Energiesysteme, Fraunhofer Institut, Auf der Reihe 2, 45884 Gelsenkirchen (Germany)

    2009-03-15

    The surface structure of multi-crystalline silicon (mc-Si) etched in HF/HNO{sub 3} at different HF/HNO{sub 3} concentrations is optimized for being applied in solar cells. The resulting texture, which determines the efficiency of solar cells, was characterized by means of scanning electron microscopy (SEM) and optical spectroscopy. The roughness of the surface increases and the reflectance decreases when the content of HNO{sub 3} in the etching solution is increased to a limit. The produced etched pits on the surface have been identified by SEM and the surface mean roughness has been characterized by atomic force microscopy (AFM). Also, depending on the concentration of the electrolyte, the mc-Si samples exhibit photoluminescence in the VIS range under UV excitation. The PL reveals the presence of nanocrystals on the surface of the etched samples. The surface structure is also optimized for an adequate placement of the metallic contact on top. Finally the solar cells were performed in order to investigate the dependence of the roughness, reflectance and photoluminescence to the solar efficiency.

  1. Microleakage after Thermocycling of Three Self-Etch Adhesives under Resin-Modified Glass-Ionomer Cement Restorations

    Directory of Open Access Journals (Sweden)

    Sabine O. Geerts

    2010-01-01

    Full Text Available This study was designed to evaluate microleakage that appeared on Resin-Modified Glass-Ionomer Cement (RMGIC restorations. Sixty class V cavities (h×w×l=2mm×2mm×3mm were cut on thirty extracted third molars, which were randomly allocated to three experimental groups. All the buccal cavities were pretreated with polyacrylic acid, whereas the lingual cavities were treated with three one-step Self-Etch adhesives, respectively, Xeno III (Dentsply Detrey GmbH, Konstanz, Germany, iBond exp (Heraeus Kulzer gmbH & Co. KG, Hanau, Germany, and Adper Prompt-L-Pop (3M ESPE AG, Dental products Seefeld, Germany. All cavities were completely filled with RMGIC, teeth were thermocycled for 800 cycles, and leakage was evaluated. Results were expressed as means ± standard deviations (SDs. Microleakage scores were analysed by means of generalized linear mixed models (GLMMs assuming an ordinal logistic link function. All results were considered to be significant at the 5% critical level (<.05. The results showed that bonding RMGIC to dentin with a Self-Etch adhesive rather than using polyacrylic acid did not influence microleakage scores (=.091, except for one tested Self-Etch adhesive, namely, Xeno III (<.0001. Nevertheless, our results did not show any significant difference between the three tested Self-Etch adhesive systems. In conclusion, the pretreatment of dentin with Self-Etch adhesive system, before RMGIC filling, seems to be an alternative to the conventional Dentin Conditioner for the clinicians as suggested by our results (thermocycling and others (microtensile tests.

  2. Los implantes de titanio con superficie grabada con ácidos: Un seguimiento clínico a 2 años Titanium implants with acid etched surface: A 2-year clinical follow-up

    Directory of Open Access Journals (Sweden)

    E. Velasco Ortega

    2004-12-01

    Full Text Available Introducción. La tecnologia implantológica está mejorando la experiencia clínica de los implantes oseointegrados, con nuevos diseños y composición en su superficie. El estudio muestra la evaluación de los implantes oseointegrados de titanio con superficie grabada con ácidos y carga precoz en pacientes con pérdida dental unitaria, parcial y total. Métodos. 35 pacientes fueron tratados con 100 implantes TSA Defcon®, 53 en la mandibula y 47 en el maxilar superior. Todos los implantes fueron insertados en 1 fase quirúrgica. Los implantes fueron cargados funcionalmente tras un periodo de tiempo de 6 semanas (mandibula y de 8 semanas (maxilar superior. Los hallazgos clínicos (implantológicos y prostodóncicos se han seguido durante 2 años. Resultados. Tras la cicatrización (6-8 semanas, 19pacientes fueron restaurados con coronas unitarias (54,3%,9 pacientes con sobre dentaduras (25,7% y 7 pacientes con puentes fijos (20%, respectivamente. Se observaron complicaciones precoces, durante el periodo de cicatrización libre de carga funcional, en 3 implantes que fueron extraidos por movilidad. Estos resultados indican una supervivencia y éxito de los implantes, de 97%. Conclusiones. Los hallazgos clínicos del presente estudio sugieren que la utilización de los implantes de titanio con superficie grabada al ácido pueden obtener la oseointegración y ser cargados precozmente, representando un procedimiento técnico con éxito en los pacientes con pérdida de dientes.Introduction. Implant technology is improving the clinical experience of osseointegrated implants with new designs and compositions of their surfaceso This study reports the results of evaluation of titanium implants with acid-etched surface and early loading in patients with unitary, partially and fully tooth loss. Methods. 100 TSA Defcon® implants were inserted in 36 patients. 63 implants were placed in the mandible and 47 in the maxilla. All implants were inserted in one

  3. Impact of Dental Implant Surface Modifications on Osseointegration

    Science.gov (United States)

    Smeets, Ralf; Stadlinger, Bernd; Schwarz, Frank; Beck-Broichsitter, Benedicta; Jung, Ole; Precht, Clarissa; Kloss, Frank; Gröbe, Alexander; Heiland, Max

    2016-01-01

    Objective. The aim of this paper is to review different surface modifications of dental implants and their effect on osseointegration. Common marketed as well as experimental surface modifications are discussed. Discussion. The major challenge for contemporary dental implantologists is to provide oral rehabilitation to patients with healthy bone conditions asking for rapid loading protocols or to patients with quantitatively or qualitatively compromised bone. These charging conditions require advances in implant surface design. The elucidation of bone healing physiology has driven investigators to engineer implant surfaces that closely mimic natural bone characteristics. This paper provides a comprehensive overview of surface modifications that beneficially alter the topography, hydrophilicity, and outer coating of dental implants in order to enhance osseointegration in healthy as well as in compromised bone. In the first part, this paper discusses dental implants that have been successfully used for a number of years focusing on sandblasting, acid-etching, and hydrophilic surface textures. Hereafter, new techniques like Discrete Crystalline Deposition, laser ablation, and surface coatings with proteins, drugs, or growth factors are presented. Conclusion. Major advancements have been made in developing novel surfaces of dental implants. These innovations set the stage for rehabilitating patients with high success and predictable survival rates even in challenging conditions. PMID:27478833

  4. Impact of Dental Implant Surface Modifications on Osseointegration

    Directory of Open Access Journals (Sweden)

    Ralf Smeets

    2016-01-01

    Full Text Available Objective. The aim of this paper is to review different surface modifications of dental implants and their effect on osseointegration. Common marketed as well as experimental surface modifications are discussed. Discussion. The major challenge for contemporary dental implantologists is to provide oral rehabilitation to patients with healthy bone conditions asking for rapid loading protocols or to patients with quantitatively or qualitatively compromised bone. These charging conditions require advances in implant surface design. The elucidation of bone healing physiology has driven investigators to engineer implant surfaces that closely mimic natural bone characteristics. This paper provides a comprehensive overview of surface modifications that beneficially alter the topography, hydrophilicity, and outer coating of dental implants in order to enhance osseointegration in healthy as well as in compromised bone. In the first part, this paper discusses dental implants that have been successfully used for a number of years focusing on sandblasting, acid-etching, and hydrophilic surface textures. Hereafter, new techniques like Discrete Crystalline Deposition, laser ablation, and surface coatings with proteins, drugs, or growth factors are presented. Conclusion. Major advancements have been made in developing novel surfaces of dental implants. These innovations set the stage for rehabilitating patients with high success and predictable survival rates even in challenging conditions.

  5. Relevant aspects in the surface properties in titanium dental implants for the cellular viability.

    Science.gov (United States)

    Velasco-Ortega, E; Alfonso-Rodríguez, C A; Monsalve-Guil, L; España-López, A; Jiménez-Guerra, A; Garzón, I; Alaminos, M; Gil, F J

    2016-07-01

    Roughness and topographical features are the most relevant of the surface properties for a dental implant for its osseointegration. For that reason, we studied the four surfaces more used in titanium dental implants: machined, sandblasted, acid etching and sandblasted plus acid etching. The roughness and wettability (contact angle and surface free energy) was studied by means 3D-interferometric microscope and sessile drop method. Normal human gingival fibroblasts (HGF) were obtained from small oral mucosa biopsies and were used for cell cultures. To analyze cell integrity, we first quantified the total amount of DNA and LDH released from dead cells to the culture medium. Then, LIVE/DEAD assay was used as a combined method assessing cell integrity and metabolism. All experiments were carried out on each cell type cultured on each Ti material for 24h, 48h and 72h. To evaluate the in vivo cell adhesion capability of each Ti surface, the four types of discs were grafted subcutaneously in 5 Wistar rats. Sandblasted surfaces were significantly rougher than acid etching and machined. Wettability and surface free energy decrease when the roughness increases in sand blasted samples. This fact favors the protein adsorption. The DNA released by cells cultured on the four Ti surfaces did not differ from that of positive control cells (p>0.05). The number of cells per area was significantly lower (pimplants is able to significantly increase bone contact and bone growth with very good osseointegration results in vivo.

  6. Dental erosion, summary.

    Science.gov (United States)

    ten Cate, J M; Imfeld, T

    1996-04-01

    Although reports on dental erosion have always appeared in the dental literature, there is currently a growing interest among researchers and clinicians. Potential risk factors for dental erosion are changed lifestyle and eating patterns, with increased consumption of acidic foods and beverages. Various gastrointestinal and eating disorders expose the dentition to frequent contacts with very acidic gastric content, which may lead to erosion. Whether these factors indeed lead, on a population scale, to a higher prevalence and incidence of erosion is yet to be established. This article summarizes the different aspects of the prevalence, pathology, etiology, assessment, prevention and treatment of dental erosion, and concludes with recommendations for future research.

  7. Surface Modifications and Their Effects on Titanium Dental Implants

    Directory of Open Access Journals (Sweden)

    A. Jemat

    2015-01-01

    Full Text Available This review covers several basic methodologies of surface treatment and their effects on titanium (Ti implants. The importance of each treatment and its effects will be discussed in detail in order to compare their effectiveness in promoting osseointegration. Published literature for the last 18 years was selected with the use of keywords like titanium dental implant, surface roughness, coating, and osseointegration. Significant surface roughness played an important role in providing effective surface for bone implant contact, cell proliferation, and removal torque, despite having good mechanical properties. Overall, published studies indicated that an acid etched surface-modified and a coating application on commercial pure titanium implant was most preferable in producing the good surface roughness. Thus, a combination of a good surface roughness and mechanical properties of titanium could lead to successful dental implants.

  8. Surface Modifications and Their Effects on Titanium Dental Implants.

    Science.gov (United States)

    Jemat, A; Ghazali, M J; Razali, M; Otsuka, Y

    2015-01-01

    This review covers several basic methodologies of surface treatment and their effects on titanium (Ti) implants. The importance of each treatment and its effects will be discussed in detail in order to compare their effectiveness in promoting osseointegration. Published literature for the last 18 years was selected with the use of keywords like titanium dental implant, surface roughness, coating, and osseointegration. Significant surface roughness played an important role in providing effective surface for bone implant contact, cell proliferation, and removal torque, despite having good mechanical properties. Overall, published studies indicated that an acid etched surface-modified and a coating application on commercial pure titanium implant was most preferable in producing the good surface roughness. Thus, a combination of a good surface roughness and mechanical properties of titanium could lead to successful dental implants.

  9. Dry etching technology for semiconductors

    CERN Document Server

    Nojiri, Kazuo

    2015-01-01

    This book is a must-have reference to dry etching technology for semiconductors, which will enable engineers to develop new etching processes for further miniaturization and integration of semiconductor integrated circuits.  The author describes the device manufacturing flow, and explains in which part of the flow dry etching is actually used. The content is designed as a practical guide for engineers working at chip makers, equipment suppliers and materials suppliers, and university students studying plasma, focusing on the topics they need most, such as detailed etching processes for each material (Si, SiO2, Metal etc) used in semiconductor devices, etching equipment used in manufacturing fabs, explanation of why a particular plasma source and gas chemistry are used for the etching of each material, and how to develop etching processes.  The latest, key technologies are also described, such as 3D IC Etching, Dual Damascene Etching, Low-k Etching, Hi-k/Metal Gate Etching, FinFET Etching, Double Patterning ...

  10. Effect of Ethylene diamine tetra acetic acid and sodium hypochlorite solution conditioning on microtensile bond strength of one-step self-etch adhesives

    Science.gov (United States)

    Kasraei, Shahin; Azarsina, Mohadese; Khamverdi, Zahra

    2013-01-01

    Background: Attempts to improve bond strength of self-etch adhesives can enhance the durability of composite restorations. Aims: The aim of the present study was to evaluate the effect of collagen and smear layer removal with sodium hypochlorite solution (NaOCl) and EDTA on micro-tensile bond strength (μTBS) of self-etch adhesives to dentin. Settings and Design: It was an in-vitro study. Materials and Methods: Seventy-two teeth were divided into eight groups and their crowns were ground perpendicular to their long axis to expose dentin. The teeth were polished with silicon-carbide papers. The groups were treated as follows: No conditioning, 0.5-M EDTA conditioning, 2.5% NaOCl conditioning, NaOCl + EDTA conditioning. The surfaces were rinsed and blot-dried. Clearfil S3 and I-Bond were applied according to manufacturers’ instructions and restored with Z100 composite. After 500 cycles of thermo-cycling between 5°C and 55°C, the samples were sectioned and tested for μTBS. Statistical Analysis: Data were analyzed by two-way ANOVA and Tukey-HSD test. Results: The highest μTBS was recorded with Clearfil S3 + NaOCl + EDTA, and the lowest was recorded with I-Bond without conditioning. μTBS in EDTA-and EDTA + NaOCl-treated groups was significantly higher than the control and NaOCl-conditioned groups. Conclusions: Application of EDTA or EDTA + NaOCl before one-step self-etch adhesives increased μTBS. PMID:23833459

  11. Synthesis of a proline-modified acrylic acid copolymer in supercritical CO2 for glass-ionomer dental cement applications.

    Science.gov (United States)

    Moshaverinia, Alireza; Roohpour, Nima; Darr, Jawwad A; Rehman, Ihtesham U

    2009-06-01

    Supercritical (sc-) fluids (such as sc-CO(2)) represent interesting media for the synthesis of polymers in dental and biomedical applications. Sc-CO(2) has several advantages for polymerization reactions in comparison to conventional organic solvents. It has several advantages in comparison to conventional polymerization solvents, such as enhanced kinetics, being less harmful to the environment and simplified solvent removal process. In our previous work, we synthesized poly(acrylic acid-co-itaconic acid-co-N-vinylpyrrolidone) (PAA-IA-NVP) terpolymers in a supercritical CO(2)/methanol mixture for applications in glass-ionomer dental cements. In this study, proline-containing acrylic acid copolymers were synthesized, in a supercritical CO(2) mixture or in water. Subsequently, the synthesized polymers were used in commercially available glass-ionomer cement formulations (Fuji IX commercial GIC). Mechanical strength (compressive strength (CS), diametral tensile strength (DTS) and biaxial flexural strength (BFS)) and handling properties (working and setting time) of the resulting modified cements were evaluated. It was found that the polymerization reaction in an sc-CO(2)/methanol mixture was significantly faster than the corresponding polymerization reaction in water and the purification procedures were simpler for the former. Furthermore, glass-ionomer cement samples made from the terpolymer prepared in sc-CO(2)/methanol exhibited higher CS and DTS and comparable BFS compared to the same polymer synthesized in water. The working properties of glass-ionomer formulations made in sc-CO(2)/methanol were comparable and better than the values of those for polymers synthesized in water.

  12. Fibrin adhesive implant in wound healing repair of dental sockets with topical application of epsilon aminocaproic acid: histological analysis.

    Science.gov (United States)

    Padovan, Luis Eduardo M; Okamoto, Tetuo; Rezende, Maria Cristina Rossifini Alves; Curvêllo, Victor Prado; Nicolielo, Daniela; Matsumoto, Mariza Akemi

    2005-05-01

    The aim of the study was to evaluate wound healing repair of dental sockets after topical application of 5% epsilon-aminocaproic acid (EACA) and the use of fibrin adhesive implant in rats under anticoagulant therapy with warfarin. Sixty Albinus wistar rats were used, divided into three groups of 20. In Group I, the animals were given 0.1 mL/100 mg of 0.9% saline solution per day, beginning 6 days before dental extraction and continuing throughout the experimental period. In Group II, the animals received 0.03 mL of sodium warfarin daily, beginning 6 days before the surgery and continuing until the day of sacrifice; after tooth extractions, the sockets were filled with fibrin adhesive material. In Group III the animals were treated as in Group II, and after extractions, the sockets were irrigated with 5 mL of 5% EACA and filled with the same fibrin adhesive material. All groups presented biological phases of wound healing repair, the differences being evident only in the chronology. The results obtained in Group III were very similar to those of Group I in the last period of wound repair, whereas Group II presented a late chronology compared to the other groups.

  13. Immunisation of rhesus monkeys with Streptococcus mutans, Lactobacillus acidophilus and lipoteichoic acid for protection against dental caries.

    Science.gov (United States)

    Caldwell, J; Lehner, T

    1982-08-01

    An attempt was made to protect rhesus monkeys from dental caries by immunisation with Streptococcus mutans, Lactobacillus acidophilus and lipoteichoic acid (LTA). The vaccine composed of S. mutans gave significant protection against caries, a decrease in the number of S. mutans, an increase in IgG antibodies and a moderate increase in complement-fixing antibodies to LTA. When LTA was used as immunogen, there was only a small reduction in caries, without any detectable antibodies to LTA and a slight increase in IgG antibodies to cell of S. mutans. Vaccines of L. acidophilus or L. fermentum gave no protection. A combined vaccine of S. mutans and L. acidophilus did not reduce the incidence of caries but the antibody titre to cells of S. mutans was raised to a level comparable with that in the S. mutans-immunised monkeys. The results of this investigation in a subhuman primate confirm that immunisation with S. mutans induces protection against caries, unlike the attempt to immunise with two selected strains of lactobacilli. More studies are required to establish the role of specific serotypes of lactobacilli in the development of dental caries.

  14. Investigating the effect of patulin, penicillic acid and EDTA on biofilm formation of isolates from dental unit water lines.

    Science.gov (United States)

    Liaqat, Iram; Bachmann, Robert Th; Sabri, Anjum Nasim; Edyvean, Robert G J; Biggs, Catherine A

    2008-11-01

    This study investigated the effect of patulin and penicillic acid, two known quorum-sensing inhibitors, and the common biocide ethylenediaminetetraacetic acid (EDTA) on the biofilm formation and auto-inducer (AI)-2 production of three isolates from dental unit water lines, Klebsiella sp., Bacillus subtilis and Bacillus cereus. Penicillic acid on its own had no effect on the biofilm formation of all isolates, whereas in combination with EDTA, it enhanced biofilm formation significantly in Klebsiella sp. and B. cereus. EDTA at concentrations greater than 10 microM promoted biofilm formation in B. cereus and B. subtilis. Patulin was found to promote biofilm formation in B. cereus up to 25 microM. A significant increase in biofilm formation was observed in B. cereus and B. subtilis at concentrations greater than 10 microM of patulin when combined with EDTA. The Vibrio harveyi BB170 AI-2 bioassay showed a positive response for Klebsiella sp. AI-2 production with a maximum fold induction at the late exponential growth phase. Addition of glucose prolonged the AI-2 production phase considerably. No significant effect of patulin, penicillic acid alone as well as in combination with EDTA was observed on AI-2 production by Klebsiella sp. The findings have important implications for the design of biofilm prevention and eradication strategies.

  15. Inhibitory effect of sorbitol on sugar metabolism of Streptococcus mutans in vitro and on acid production in dental plaque in vivo.

    Science.gov (United States)

    Takahashi-Abbe, S; Abbe, K; Takahashi, N; Tamazawa, Y; Yamada, T

    2001-04-01

    This study was conducted to find out whether sorbitol inhibits the sugar metabolism of Streptococcus mutans in vitro and the acid production in dental plaque in vivo. S. mutans NCIB 11723 was anaerobically grown in sorbitol-containing medium. The rate of acid production from sugars was estimated with a pH stat. The rate of acid production from glucose or sucrose was not changed at various concentrations of oxygen. By the addition of sorbitol to sugar, however, the acid production was decreased with increasing levels of oxygen. Intracellular NADH/NAD+ ratio and (dihydroxyacetone-phosphate+glyceraldehyde-phosphate)/3-phosphoglycerate ratio were high whenever the acid production was inhibited by sorbitol. Sorbitol also inhibited the acid production in dental plaque in vivo. These results suggest that the increased NADH/NAD+ ratio during sorbitol metabolism through the inactivation of pyruvate formate-lyase by oxygen inhibited glyceraldehyde-phosphate dehydrogenase and then the acid production of S. mutans and the one in dental plaque.

  16. The effect of erbium-doped: yttrium, aluminium and garnet laser irradiation on the surface microstructure and roughness of double acid-etched implants

    OpenAIRE

    2011-01-01

    Purpose One of the most frequent complications related to dental implants is peri-implantitis, and the characteristics of implant surfaces are closely related to the progression and resolution of inflammation. Therefore, a technical modality that can effectively detoxify the implant surface without modification to the surface is needed. The purpose of this study was to evaluate the effect of erbium-doped: yttrium, aluminium and garnet (Er:YAG) laser irradiation on the microstructural changes ...

  17. Orthodox etching of HVPE-grown GaN

    Energy Technology Data Exchange (ETDEWEB)

    Weyher, J.L.; Lazar, S.; Macht, L.; Liliental-Weber, Z.; Molnar,R.J.; Muller, S.; Nowak, G.; Grzegory, I.

    2006-08-10

    Orthodox etching of HVPE-grown GaN in molten eutectic of KOH + NaOH (E etch) and in hot sulfuric and phosphoric acids (HH etch) is discussed in detail. Three size grades of pits are formed by the preferential E etching at the outcrops of threading dislocations on the Ga-polar surface of GaN. Using transmission electron microscopy (TEM) as the calibration tool it is shown that the largest pits are formed on screw, intermediate on mixed and the smallest on edge dislocations. This sequence of size does not follow the sequence of the Burgers values (and thus the magnitude of the elastic energy) of corresponding dislocations. This discrepancy is explained taking into account the effect of decoration of dislocations, the degree of which is expected to be different depending on the lattice deformation around the dislocations, i.e. on the edge component of the Burgers vector. It is argued that the large scatter of optimal etching temperatures required for revealing all three types of dislocations in HVPE-grown samples from different sources also depends upon the energetic status of dislocations. The role of kinetics for reliability of etching in both etches is discussed and the way of optimization of the etching parameters is shown.

  18. Spatial variation of the etch rate for deep etching of silicon by reactive ion etching

    DEFF Research Database (Denmark)

    Andersen, Bo Asp Møller; Hansen, Ole; Kristensen, Martin

    1997-01-01

    The macroscopic uniformity of deep etching into silicon by reactive ion etching (RIE) with a SF6-O-2 plasma was studied. The spatial variation of the etch rate across a 4 inch wafer in a single wafer system is a function of the process parameters and the configuration of the etch chamber. It was ......The macroscopic uniformity of deep etching into silicon by reactive ion etching (RIE) with a SF6-O-2 plasma was studied. The spatial variation of the etch rate across a 4 inch wafer in a single wafer system is a function of the process parameters and the configuration of the etch chamber....... It was found that, for a constant load of silicon exposed to the plasma, the etch rate variation can be controlled through the applied rf power, the chamber pressure, and the gas mixture. It was also found that the etch rate uniformity varies with the load of silicon exposed to the plasma. The result...... is a balance between the flux of neutral radicals and the flux of energetic ions to the surface. This balance is due to the RIE etch mechanism, which involves synergism between the two fluxes. (C) 1997 American Vacuum Society....

  19. In vitro bioactivity assessment of composite membrane containing antimicrobial lauric acid for guided bone regeneration in dental application

    Science.gov (United States)

    Suleiman, Muhammad Jabir; Kalitheertha, Jamuna Thevi; Sabri, Siti Noorzidah

    2015-07-01

    The manuscript reflect research work in fabrication of a triple layered composite membrane and to perform an in vitro bioactivity evaluation on composite membrane containing antimicrobial lauric acid. Poly(lactic-co-glycolic acid) (PLGA) matrix was incorporated with various amounts of nanoapatite (NAp) and lauric acid (LA) to form a triple-layered composite membrane. This membrane was prepared using a single step fabrication technique comprising of solvent casting, thermally induced phase separation and solvent leaching processes. Apatite mineralization was detected on the composite membranes within 30 days of exposure to simulated body fluid (SBF) and showed increased apatite formation at 30-60wt% of NAp content in the PLGA matrix on layer 3 (L3), that has the highest amount of NAp compared with layer 1 (L1) and layer 2 (L2) of the membrane. However, apatite mineralization was not detected on pure PLGA membrane. In addition, incorporation of LA on L1 and L2 has no influence on apatite mineral formation as none detected on these surfaces. The presence of NAp determines the formation of apatite crystals on the composite membrane. These membranes with triple layered design and bioactive properties showed potential use for guided bone regeneration purposes in dental application.

  20. A Comparative Evaluation of the Efficacy of Etching by the Total Etch and Self-etch Dentin Bonding Systems in the Primary Teeth: An in vitro Study

    Science.gov (United States)

    Chaugule, Vishwas; Katge, Farhin; Poojari, Manohar; Pujari, Prashant; Pammi, Thejokrishna

    2015-01-01

    ABSTRACT Objective: Early childhood caries is now affecting the children in dangerous proportions. There is a wide spread loss of the tooth material irrespective of the type of the carious lesion. Restoration of such lesions with a strong permanent bond between the dental tissues and the restorative dental materials would be a highly desirable requisite. Ultramorphological characterizations show that the interfacial morphology and the chemical characterization of the bonding systems appear to be strongly associated with each other and, therefore, observing and understanding the interfacial phenomenon and its quality would be of great importance in the selection of a dental adhesive for its use in pediatric restorative dentistry. Study design: Human primary molars, which were indicated for extraction, for an array of reasons like caries, normal exfoliation, pathological root resorption, over-retained and serial extraction, were collected for the study purpose. Total number of teeth was then equally distributed into two subgroups, each namely A1 (Prime and Bond NT) and A2 (Xeno III). Results: The type of etching pattern that was observed in group A1 (Prime and Bond NT) of Silverstone’s type II compared to the Silverstone’s type III observed in group A2 (Xeno III). Conclusion: Results of this study indicate that the use of an etchant separately followed by the application of the bonding system–Prime and Bond NT–would provide a better quality of adhesion thus improving the quality and longevity of the restoration done within the limits of enamel in primary dentition. How to cite this article: Mithiborwala SH, Chaugule V, Katge F, Poojari M, Pujari P, Pammi T. A Comparative Evaluation of the Efficacy of Etching by the Total Etch and Self-etch Dentin Bonding Systems in the Primary Teeth: An in vitro Study. Int J Clin Pediatr Dent 2015;8(1):30-36. PMID:26124578

  1. Influência da dieta líquida ácida no desenvolvimento de erosão dental Influence of the liquid acid diet on the development of dental erosion

    Directory of Open Access Journals (Sweden)

    Maria Angela Pita SOBRAL

    2000-12-01

    Full Text Available O objetivo deste trabalho foi estudar a importância do pH da dieta líquida na etiologia e prevenção das lesões de erosão dental, bem como conhecer o pH de algumas bebidas e sucos, supostamente ácidos, mais consumidos em nosso meio, para que fosse possível estabelecer uma comparação destes valores a fim de controlar a dieta dos pacientes portadores de lesões de erosão dental. Um único exemplar de cada fruta madura foi processado puro de modo a ser liquefeito e o pH foi medido utilizando-se um pH-metro, imediatamente e depois de 30 minutos. Posteriormente, a amostra de suco foi diluída em água na proporção de 1:2 e novas medidas foram tomadas. Para as bebidas industrializadas, as medidas de pH foram realizadas imediatamente após a abertura do frasco e depois de 30 minutos. As bebidas e sucos analisados mostraram valores abaixo do pH crítico de dissolução da estrutura dental, sugerindo a possibilidade de favorecerem a desmineralização. A orientação quanto à dieta ácida parece ser um fator importante no tratamento e prevenção das lesões de erosão dental.The aim of this paper was to evaluate the importance of the liquid diet pH in the etiology and prevention of dental erosion, so as to give dietary orientation to patients who present with these lesions, as well as to know the pH of the most consumed Brazilian fruit juices and industrialized beverages, which are supposably acid. A sample of each mature fruit was processed to be liquefied, and the pH was obtained through a pHmeter appliance, immediately after the juices were obtained and 30 minutes later. Afterward the juices were diluted in potable water in a 1:2 proportion and new pH values were obtained. For the industrialized beverages, pH measurements were carried out immediately after opening the bottles and 30 minutes later. The beverages and juices analyzed showed pH values below the critical pH for dental tissue dissolution (5.5. Therefore, they are expected to

  2. Unveiling the wet chemical etching characteristics of polydimethylsiloxane film for soft micromachining applications

    Science.gov (United States)

    Kakati, A.; Maji, D.; Das, S.

    2017-01-01

    Micromachining of a polydimethylsiloxane (PDMS) microstructure by wet chemical etching is explored for microelectromechanical systems (MEMS) and microfluidic applications. A 100 µm thick PDMS film was patterned with different microstructure designs by wet chemical etching using a N-methyl-2-pyrrolidone (C16H36FN) and tetra-n-butylammonium fluoride (C5H9NO) mixture solution with 3:1 volume ratio after lithography for studying etching characteristics. The patterning parameters, such as etch rate, surface roughness, pH of etchant solution with time, were thoroughly investigated. A detailed study of surface morphology with etching time revealed nonlinear behaviour of the PDMS surface roughness and etch rate. A maximum rate of 1.45 µm min-1 for 10 min etching with surface roughness of 360 nm was achieved. A new approach of wet chemical etching with pH controlled doped etchant was introduced for lower surface roughness of etched microstructures, and a constant etch rate during etching. Variation of the etching rate and surface roughness by pH controlled etching was performed by doping 5-15 gm l-1 of silicic acid (SiO2x H2O) into the traditional etchant solution. PDMS etching by silicic acid doped etchant solution showed a reduction in surface roughness from 400 nm to 220 nm for the same 15 µm etching. This study is beneficial for micromachining of various MEMS and microfluidic structures such as micropillars, microchannels, and other PDMS microstructures.

  3. Cariogenic bacteria degrade dental resin composites and adhesives.

    Science.gov (United States)

    Bourbia, M; Ma, D; Cvitkovitch, D G; Santerre, J P; Finer, Y

    2013-11-01

    A major reason for dental resin composite restoration replacement is related to secondary caries promoted by acid production from bacteria including Streptococcus mutans (S. mutans). We hypothesized that S. mutans has esterase activities that degrade dental resin composites and adhesives. Standardized specimens of resin composite (Z250), total-etch (Scotchbond Multipurpose, SB), and self-etch (Easybond, EB) adhesives were incubated with S. mutans UA159 or uninoculated culture medium (control) for up to 30 days. Quantification of the BisGMA-derived biodegradation by-product, bishydroxy-propoxy-phenyl-propane (BisHPPP), was performed by high-performance liquid chromatography. Surface analysis of the specimens was performed by scanning electron microscopy (SEM). S. mutans was shown to have esterase activities in levels comparable with those found in human saliva. A trend of increasing BisHPPP release throughout the incubation period was observed for all materials and was more elevated in the presence of bacteria vs. control medium for EB and Z250, but not for SB (p < .05). SEM confirmed the increased degradation of all materials with S. mutans UA159 vs. control. S. mutans has esterase activities at levels that degrade resin composites and adhesives; degree of degradation was dependent on the material's chemical formulation. This finding suggests that the resin-dentin interface could be compromised by oral bacteria that contribute to the progression of secondary caries.

  4. Effect of Ethylene diamine tetra acetic acid and sodium hypochlorite solution conditioning on microtensile bond strength of one-step self-etch adhesives

    Directory of Open Access Journals (Sweden)

    Shahin Kasraei

    2013-01-01

    Settings and Design: It was an in-vitro study. Materials and Methods: Seventy-two teeth were divided into eight groups and their crowns were ground perpendicular to their long axis to expose dentin. The teeth were polished with silicon-carbide papers. The groups were treated as follows: No conditioning, 0.5-M EDTA conditioning, 2.5% NaOCl conditioning, NaOCl + EDTA conditioning. The surfaces were rinsed and blot-dried. Clearfil S3 and I-Bond were applied according to manufacturers′ instructions and restored with Z100 composite. After 500 cycles of thermo-cycling between 5±C and 55±C, the samples were sectioned and tested for μTBS. Statistical Analysis: Data were analyzed by two-way ANOVA and Tukey-HSD test. Results: The highest μTBS was recorded with Clearfil S3 + NaOCl + EDTA, and the lowest was recorded with I-Bond without conditioning. μTBS in EDTA-and EDTA + NaOCl-treated groups was significantly higher than the control and NaOCl-conditioned groups. Conclusions: Application of EDTA or EDTA + NaOCl before one-step self-etch adhesives increased μTBS.

  5. Dental Emergencies

    OpenAIRE

    Domb, Ivor

    1982-01-01

    Emergency dental problems can result from trauma, dental pathology, or from dental treatment itself. While the physician can treat many instances of dental trauma, the patient should see a dentist as soon as possible so that teeth can be saved. Emergency treatment of dental pathology usually involves relief of pain and/or swelling. Bleeding is the most frequent post-treatment emergency. The physician should be able to make the patient comfortable until definitive dental treatment can be avail...

  6. Dental Procedures.

    Science.gov (United States)

    Ramponi, Denise R

    2016-01-01

    Dental problems are a common complaint in emergency departments in the United States. There are a wide variety of dental issues addressed in emergency department visits such as dental caries, loose teeth, dental trauma, gingival infections, and dry socket syndrome. Review of the most common dental blocks and dental procedures will allow the practitioner the opportunity to make the patient more comfortable and reduce the amount of analgesia the patient will need upon discharge. Familiarity with the dental equipment, tooth, and mouth anatomy will help prepare the practitioner for to perform these dental procedures.

  7. An investigation using atomic force microscopy nanoindentation of dental enamel demineralization as a function of undissociated acid concentration and differential buffer capacity

    Science.gov (United States)

    Barbour, Michele E.; Shellis, R. Peter

    2007-02-01

    Acidic drinks and foodstuffs can demineralize dental hard tissues, leading to a pathological condition known as dental erosion, which is of increasing clinical concern. The first step in enamel dissolution is a demineralization of the outer few micrometres of tissue, which results in a softening of the structure. The primary determinant of dissolution rate is pH, but the concentration of undissociated acid, which is related to buffer capacity, also appears to be important. In this study, atomic force microscopy nanoindentation was used to measure the first initial demineralization (softening) induced within 1 min by exposure to solutions with a range of undissociated acid concentration and natural pH of 3.3 or with an undissociated acid concentration of 10 mmol l-1 and pH adjusted to 3.3. The results indicate that differential buffering capacity is a better determinant of softening than undissociated acid concentration. Under the conditions of these experiments, a buffer capacity of >3 mmol l-1 pH-1 does not have any further effect on dissolution rate. These results imply that differential buffering capacity should be used for preference over undissociated acid concentration or titratable acidity, which are more commonly employed in the literature.

  8. Effect of tannic acid solution on collagen structures for dental restoration.

    Science.gov (United States)

    Natsir, N; Wakasa, K; Yoshida, Y; Satou, N; Shintani, H

    1999-08-01

    This study examined the effect of tannic acid solution on dissolution of dentine collagen and morphological aspects of tendon collagen. Using root dentine, which was cut off from bovine anterior tooth, dentine powders were obtained by the pulverization and lyophilization. They were subject to an application of 1, 3, 5 or 10% tannic acid (TA) solution for 1, 3, 6, 12 or 24 h. TA-treated dentine powders were treated with 40% phosphoric acid (PA) for 30 s at 20 degrees C and additionally with trypsin. Released hydroxyproline in Woessner's assay after a hydrolysis in 6 N HCl at 110 degrees C for 20 h was assumed to be dissolved dentine collagen. Released hydroxyproline in a control sample without acid treatment decreased from 100 to about 60% with increased TA concentration of 1 to 10%, and decreased with increased incubation times of 1 to 24 h when applied by 5% TA solution. Scanning electron microscopy results established the morphological effect of their surface characteristics due to such treatments as 40% PA for 30 s and 5% TA for 6 h, or 40% PA after 5% TA treatment, yielding collagen structures protected by TA to attack from phosphoric acid.

  9. 四种自酸蚀粘接剂牙本质粘接界面纳米渗漏比较%Nanoleakage at the resin-dental interface of four self-etching adhesives

    Institute of Scientific and Technical Information of China (English)

    廖志清; 欧阳勇; 杨剑珍

    2011-01-01

    目的 比较4种自酸蚀粘接剂牙本质粘接界面纳米渗漏及微观形态。方法 选取16颗无龋人离体第三磨牙,制备统一的牙本质玷污层,分别用4种自酸蚀粘接剂A( Adper Prompt)、B( iBond)、C(XenoⅢ)及D(SE Bond)按使用说明进行粘接处理,垂直粘接面切成0.9 mmx4.0 mm试件,避光贮存于氨化硝酸银溶液中24 h,经显影固定脱矿后,切成90 nm超薄切片,铀、铅染色后于透射电镜下观察银离子的渗入情况及界面相关结构。结果4种粘接剂形成的混合层及粘接层薄厚不同:粘接剂A、C混合层较B、D厚,粘接层较B、D簿。4种粘接剂粘接界面均有不同程度纳米渗漏:A(45.02 ±9.49);B(43.97±8.55);C(27.02±10.86);D(12.94±2.07)。粘接剂D组纳米渗漏较小,与其他3种粘接剂间差异有统计学意义(P<0.05)。结论4种自酸蚀粘接剂混合层和粘接层厚度存在差异,粘接界面的纳米渗漏率不同,一步法自酸蚀粘接系统纳米渗漏较两步法系统明显。%Objective To evaluate the nanoleakage and ultramorphology of four self-etching adhesives. Methods Sixteen freshly extracted, caries-free human third molars were selected. A flat dentin surface was exposed by removing occlusal enamel. All teeth were randomly divided into four groups acorrding to four different self-etch adhesive: Adper Prompt( A), iBond(B) , Xeno Ⅲ (C) and SE Bond (D). The dentin were bonded with dentin adhesive system according to manufacturer's directions. Composite layers were built up incrementally. The specimens were sectioned longitudinally across the resin-dentin interface into 4. 0 mm × 0. 9 mm sticks and then traced with ammoniacal silver .solution. Epoxy resin-embedded sections were prepared for transmission electron microscope( TEM ) to observe nanoleakage. The images were qualitatively compared by NIH software, and data was analyzed by SPSS. Results Different thickness of hybrid layer and adhesives layer

  10. Effects of surface treatment on bond strength between dental resin agent and zirconia ceramic.

    Science.gov (United States)

    Moradabadi, Ashkan; Roudsari, Sareh Esmaeily Sabet; Yekta, Bijan Eftekhari; Rahbar, Nima

    2014-01-01

    This paper presents the results of an experimental study to understand the dominant mechanism in bond strength between dental resin agent and zirconia ceramic by investigating the effects of different surface treatments. Effects of two major mechanisms of chemical and micromechanical adhesion were evaluated on bond strength of zirconia to luting agent. Specimens of yttrium-oxide-partially-stabilized zirconia blocks were fabricated. Seven groups of specimens with different surface treatment were prepared. 1) zirconia specimens after airborne particle abrasion (SZ), 2) zirconia specimens after etching (ZH), 3) zirconia specimens after airborne particle abrasion and simultaneous etching (HSZ), 4) zirconia specimens coated with a layer of a Fluorapatite-Leucite glaze (GZ), 5) GZ specimens with additional acid etching (HGZ), 6) zirconia specimens coated with a layer of salt glaze (SGZ) and 7) SGZ specimens after etching with 2% HCl (HSGZ). Composite cylinders were bonded to airborne-particle-abraded surfaces of ZirkonZahn specimens with Panavia F2 resin luting agent. Failure modes were examined under 30× magnification and the effect of surface treatments was analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). SZ and HSZ groups had the highest and GZ and SGZ groups had the lowest mean shear bond strengths among all groups. Mean shear bond strengths were significantly decreased by applying a glaze layer on zirconia surfaces in GZ and SGZ groups. However, bond strengths were improved after etching process. Airborne particle abrasion resulted in higher shear bond strengths compared to etching treatment. Modes of failure varied among different groups. Finally, it is concluded that micromechanical adhesion was a more effective mechanism than chemical adhesion and airborne particle abrasion significantly increased mean shear bond strengths compared with another surface treatments.

  11. Effect of acidity upon attrition-corrosion of human dental enamel.

    Science.gov (United States)

    Wu, Yun-Qi; Arsecularatne, Joseph A; Hoffman, Mark

    2015-04-01

    Attrition-corrosion is a synthesized human enamel wear process combined mechanical effects (attrition) with corrosion. With the rising consumption of acidic food and beverages, attrition-corrosion is becoming increasingly common. Yet, research is limited and the underlying mechanism remains unclear. In this study, in vitro wear loss of human enamel was investigated and the attrition-corrosion process and wear mechanism were elucidated by the analysis of the wear scar and its subsurface using focused ion beam (FIB) sectioning and scanning electron microscopy (SEM). Human enamel flat-surface samples were prepared with enamel cusps as the wear antagonists. Reciprocating wear testing was undertaken under load of 5N at the speed of 66 cycle/min for 2250 cycles with lubricants including citric acid (at pH 3.2 and 5.5), acetic acid (at pH 3.2 and 5.5) and distilled water. All lubricants were used at 37°C. Similar human enamel flat-surface samples were also exposed to the same solutions as a control group. The substance loss of enamel during wear can be linked to the corrosion potential of a lubricant used. Using a lubricant with very low corrosion potential (such as distilled water), the wear mechanism was dominated by delamination with high wear loss. Conversely, the wear mechanism changed to shaving of the softened layer with less material loss in an environment with medium corrosion potential such as citric acid at pH 3.2 and 5.5 and acetic acid at pH 5.5. However, a highly corrosive environment (e.g., acetic acid at pH 3.2) caused the greatest loss of substance during wear.

  12. Effects of surface treatment on bond strength between dental resin agent and zirconia ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Moradabadi, Ashkan [Department of Electrochemistry, Universität Ulm, Ulm (Germany); Roudsari, Sareh Esmaeily Sabet [Department of Optoelectonics, Universität Ulm, Ulm (Germany); Yekta, Bijan Eftekhari [School of Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Rahbar, Nima, E-mail: nrahbar@wpi.edu [Department of Civil and Environmental Engineering, Worcester Polytechnic Institute, Worcester, MA 01609 (United States)

    2014-01-01

    This paper presents the results of an experimental study to understand the dominant mechanism in bond strength between dental resin agent and zirconia ceramic by investigating the effects of different surface treatments. Effects of two major mechanisms of chemical and micromechanical adhesion were evaluated on bond strength of zirconia to luting agent. Specimens of yttrium-oxide-partially-stabilized zirconia blocks were fabricated. Seven groups of specimens with different surface treatment were prepared. 1) zirconia specimens after airborne particle abrasion (SZ), 2) zirconia specimens after etching (ZH), 3) zirconia specimens after airborne particle abrasion and simultaneous etching (HSZ), 4) zirconia specimens coated with a layer of a Fluorapatite-Leucite glaze (GZ), 5) GZ specimens with additional acid etching (HGZ), 6) zirconia specimens coated with a layer of salt glaze (SGZ) and 7) SGZ specimens after etching with 2% HCl (HSGZ). Composite cylinders were bonded to airborne-particle-abraded surfaces of ZirkonZahn specimens with Panavia F2 resin luting agent. Failure modes were examined under 30 × magnification and the effect of surface treatments was analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). SZ and HSZ groups had the highest and GZ and SGZ groups had the lowest mean shear bond strengths among all groups. Mean shear bond strengths were significantly decreased by applying a glaze layer on zirconia surfaces in GZ and SGZ groups. However, bond strengths were improved after etching process. Airborne particle abrasion resulted in higher shear bond strengths compared to etching treatment. Modes of failure varied among different groups. Finally, it is concluded that micromechanical adhesion was a more effective mechanism than chemical adhesion and airborne particle abrasion significantly increased mean shear bond strengths compared with another surface treatments. - Highlights: • Understanding the dominant mechanism of bonding

  13. Dental Diseases of Acid Factory Workers Globally-Narrative Review Article.

    Directory of Open Access Journals (Sweden)

    Sanadhya Sudhanshu

    2014-01-01

    Full Text Available Background Industrial growth is occurring exponentially, for unimpeded growth, industrial workers are recruited on a large scale globally. There are various sectors of industries present for which laborers are trained in accordance to their requirements. As workers possess the general health risk of occupational hazards, various labor laws, schemes and policies are undertaken by the government which are implemented by industries, but very few attention for oral health is being given because of which laborers are more progressing towards hidden adverse oral effects which can affect their working efficacy. Various studies on different sector workers were carried out focusing their oral health status but for acid factory workers it is neglected and therefore unrevealed to the society. For this purpose, in this article, though, paucity of literature, still, tries to enlighten the oral health status in acid factory industrial workers with available resources.

  14. Dental Diseases of Acid Factory Workers Globally-Narrative Review Article.

    Science.gov (United States)

    Sudhanshu, Sanadhya; Pankaj, Aapaliya; Sorabh, Jain; Nidhi, Sharma

    2014-01-01

    Background Industrial growth is occurring exponentially, for unimpeded growth, industrial workers are recruited on a large scale globally. There are various sectors of industries present for which laborers are trained in accordance to their requirements. As workers possess the general health risk of occupational hazards, various labor laws, schemes and policies are undertaken by the government which are implemented by industries, but very few attention for oral health is being given because of which laborers are more progressing towards hidden adverse oral effects which can affect their working efficacy. Various studies on different sector workers were carried out focusing their oral health status but for acid factory workers it is neglected and therefore unrevealed to the society. For this purpose, in this article, though, paucity of literature, still, tries to enlighten the oral health status in acid factory industrial workers with available resources.

  15. Microinfiltração em dentes decíduos em função de materiais restauradores e condicionamento ácido Microleakage in primary teeth related to restorative materials and acid etching

    Directory of Open Access Journals (Sweden)

    Sandra Kalil BUSSADORI

    1999-12-01

    Full Text Available A pesquisa teve como objetivo avaliar a microinfiltração em restaurações de quatro materiais (Dyract, Vitremer, Z100 e Fuji II LC, em dentes decíduos, realizando ou não condicionamento ácido. Foram feitas dez restaurações (5 OM e 5 OD para cada condição experimental. As cavidades tinham as dimensões (mm: 4 de altura, 3 de largura e 2 de profundidade. Os materiais foram manipulados conforme instruções dos fabricantes. Os dentes restaurados, após sete dias de armazenagem foram submetidos à ciclagem térmica (700 ciclos a 5 e 55ºC, com um minuto em cada banho. Em seqüência os corpos-de-prova foram preparados para a imersão em azul de metileno a 0,5%, pH 7,2, por quatro horas, após o que foram preparados para a avaliação do grau de infiltração. Os resultados permitiram concluir que: foi grande a diferença de escores entre materiais (de infiltração nula, 0, a 4 máxima; médias de 0,1 (Dyract a 4,0 (Fuji II LC; os materiais Vitremer e Z100 não diferiram entre si e se encontraram com valores entre os outros dois; o condicionamento ácido influiu apenas com o material Fuji II LC.The purpose of this research was to evaluate microleakage on proximal restorations of primary teeth, using four materials (Dyract, Vitremer, Z100 and Fuji II LC. Acid etching was performed in only one group. Proximal cavities were prepared with the following measures (mm: height, 4; width, 3; depth, 2. Restoring was performed according to manufacturer’s instructions, and specimens were stored in distilled water for seven days, at 37ºC. Afterwards, thermal cycling was performed (700 cycles at 5 and 55ºC, for one minute in each temperature. Specimens were then immersed in 0.5% methylene blue solution, and prepared for evaluation. The results led to the following conclusions: there were great differences of scores between materials, 0.1 (Dyract and 4.0 (Fuji II LC; Vitremer and Z100 presented similar values (respectively, in scores, 1.7 and 1

  16. ZERODUR: bending strength data for etched surfaces

    Science.gov (United States)

    Hartmann, Peter; Leys, Antoine; Carré, Antoine; Kerz, Franca; Westerhoff, Thomas

    2014-07-01

    In a continuous effort since 2007 a considerable amount of new data and information has been gathered on the bending strength of the extremely low thermal expansion glass ceramic ZERODUR®. By fitting a three parameter Weibull distribution to the data it could be shown that for homogenously ground surfaces minimum breakage stresses exist lying much higher than the previously applied design limits. In order to achieve even higher allowable stress values diamond grain ground surfaces have been acid etched, a procedure widely accepted as strength increasing measure. If surfaces are etched taking off layers with thickness which are comparable to the maximum micro crack depth of the preceding grinding process they also show statistical distributions compatible with a three parameter Weibull distribution. SCHOTT has performed additional measurement series with etch solutions with variable composition testing the applicability of this distribution and the possibility to achieve further increase of the minimum breakage stress. For long term loading applications strength change with time and environmental media are important. The parameter needed for prediction calculations which is combining these influences is the stress corrosion constant. Results from the past differ significantly from each other. On the basis of new investigations better information will be provided for choosing the best value for the given application conditions.

  17. [Effect of dental alloys on salivary alkaline and acid phosphatase, alpha amylase K+, Na+, and Cl-].

    Science.gov (United States)

    Todorov, I; Saprjanova, M

    1977-04-01

    Comparative studied were performed in healthy subjects without metals in their oral cavities and in individuals having different metal alloys (gold, steel, amalgam) in their mouths and presenting with various complaints such as xerostomia, burning mucosa, etc. It was found that the contents of alkaline and acid phosphatases, alpha-amylase, K+, Na+ and Cl- in saliva increased significantly with the increase in total corrosion potential when non-precious metal alloys, especially different types of alloys, were present. Parallel to this, the frequency and the intensity of the complaints increased.

  18. Parabens do not increase fluoride uptake by dental enamel

    Directory of Open Access Journals (Sweden)

    Vanessa Silva Tramontino

    2010-04-01

    Full Text Available Objective: To evaluate whether methylparaben and propylparaben, which present a similar chemical structure, increase fluoride uptake by demineralized dental enamel when present in buffered solutions. Methods: The study comprised an in vitro experiment using blocks of bovine dental enamel with artificial carious lesions. Enamel blocks were exposed to the following treatment (n=12: fluoride solution (200 ppm fluoride - control; solution containing fluoride and 13 mM methylparaben; solution containing fluoride and 13 mM propylparaben in 35% propylene glycol; solution containing fluoride in 35% propylene glycol. All solutions were buffered (0.01 M cacodilate and the pH was adjusted to 6.27. The blocks were exposed to the treatment solutions in the proportion of 2 ml per mm2 of exposed enamel area and fluoride formed was estimated after removing an enamel layer by acid etching. Fluoride extracted was determined by ion specific electrode and the amount of enamel removed was estimated by phosphorus analysis. ANOVA followed by Tukey’s test were used for statistical analysis, with significance level at 5%. Results: The dental blocks of treatment groups containing both parabens and the control group presented similar fluoride concentration in enamel and no statistical difference was observed among them (p>0.05. The dental blocks of treatment group containing fluoride and propylene glycol showed the lowest value of fluoride present in enamel, which was significantly different from the control and fluoride and methylparaben groups (p<0.05. Conclusion: Methyl and propylparaben in a buffered solution do not enhance fluoride uptake by demineralized dental enamel.

  19. SWELLING AND WETTABILITY OF LIGHT-CURED METHACRYLATE-BASED DENTAL RESINS PREPARED FROM CHOLIC ACID

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    2 '-methacryloxy-3α, 7α 12α- trimethacryloyl cholic acid ethyl ester (CAGE4MA) has been prepared from cholic acid. Photo-polymeric resins were prepared from CAGE4MA. 2,2-bis[4-(2-hydroxy-3-methacrylyloxypropoxy)phenyl]propane (bis-GMA) was used for comparison, triethyleneglycol dimethacrylate (TEGDMA) was used as diluent. The polymerization was initiated by camphoroquinone (CQ)/N, N-dimethylaminoethyl methacrylate (DMAEMA) system. The conversion of CAGE4MA was 39% when the reaction time is 60s, which is lower than bis-GMA and TEGDMA.The swelling value of CAGE4MA resin was 0.41% in distilled water, which is much lower than those of bis-GMA resin (2.04%) and TEGDMA resin (4.77%) under the same conditions. Copolymers from CAGE4MA and TEGDMA have been prepared. With the increase of TEGDMA in mixture, the degree of conversion of CA GE4MA and swelling value increased. The swelling values of photocured resins in 0. 1mol/L HCl were also measured.

  20. Comparative study of etched enamel and dentin for the adhesion of composite resins with the Er:YAG 2,94 {mu}m laser and CO{sub 2} 9,6 {mu}m laser: morphological (SEM) and tensile bond strength analysis; Estudo comparativo do condicionamento do esmalte e dentina para a adesao de resinas compostas com os lasers Er:YAG 2,94 {mu}m e com o laser CO{sub 2} de 9,6 {mu}m: analise morfologica e de resistencia a tracao

    Energy Technology Data Exchange (ETDEWEB)

    Marraccini, Tarso Mugnai

    2002-07-01

    The aim of this study was to evaluate and compare the tensile bond strength of a composite resin adhered to the enamel and dentin which have received superficial irradiation with an Er:YAG laser (2.94 {mu}m) or with CO{sub 2} laser ( 9.6 {mu}m) and later on etched with the phosphoric acid at 35%. After the use of the adhesive system, resin cones were made on the etched surfaces by both lasers and tensile bond strength tests were performed. All samples were observed at the SEM - there was an increase of the degree of fusion and resolidification in the irradiated enamel and dentin samples with the CO{sub 2} laser (9.6 {mu}m), creating a vitrified layer with tiny craters. With the Er:YAG laser (2.94 {mu}m) there were typical morphological explosive microablation with the exposition of the tubules in the dentin.The surface acquired by the association of the CO{sub 2} laser ( 9.6 {mu}m) plus acid etching no longer presented the aspect of fusion being this layer completely removed. There were statistical significant differences among ali three methods of etching in the treatment of the enamel and dentin surface. The tensile bond strength test showed that etching of these enamel and dentin surfaces with acid exclusively (control group) presented great values, surpassing the values of the etching acquired with the Er:YAG laser (2.94 {mu}) plus acid or the CO{sub 2} laser (9.6 {mu}m) plus acid. With the parameters used in this experiment the Er:YAG laser (2.94 {mu}m) showed to be more effective than the CO{sub 2} laser (9.6 {mu}m) for the hard dental surfaces etching procedure. (author)

  1. Bond strength with various etching times on young permanent teeth

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.N.; Lu, T.C. (School of Dentistry, National Defense Medical Center, Taipei, Taiwan (China))

    1991-07-01

    Tensile bond strengths of an orthodontic resin cement were compared for 15-, 30-, 60-, 90-, or 120-second etching times, with a 37% phosphoric acid solution on the enamel surfaces of young permanent teeth. Fifty extracted premolars from 9- to 16-year-old children were used for testing. An orthodontic composite resin was used to bond the bracket directly onto the buccal surface of the enamel. The tensile bond strengths were tested with an Instron machine. Bond failure interfaces between bracket bases and teeth surfaces were examined with a scanning electron microscope and calculated with mapping of energy-dispersive x-ray spectrometry. The results of tensile bond strength for 15-, 30-, 60-, or 90-second etching times were not statistically different. For the 120-second etching time, the decrease was significant. Of the bond failures, 43%-49% occurred between bracket and resin interface, 12% to 24% within the resin itself, 32%-40% between resin and tooth interface, and 0% to 4% contained enamel fragments. There was no statistical difference in percentage of bond failure interface distribution between bracket base and resin, resin and enamel, or the enamel detachment. Cohesive failure within the resin itself at the 120-second etching time was less than at other etching times, with a statistical significance. To achieve good retention, to decrease enamel loss, and to reduce moisture contamination in the clinic, as well as to save chairside time, a 15-second etching time is suggested for teenage orthodontic patients.

  2. Drugs that promote dental caries.

    Science.gov (United States)

    2015-02-01

    Dental caries result from erosion of tooth enamel or cementum by acidic substances produced by bacteria found in dental plaque. Caries can lead to pulp necrosis and tooth loss. Risk factors include certain dietary habits, poor oral hygiene, and dry mouth. Diabetes and Sjogren's syndrome can also promote dental caries. Psychotropic substances such as cocaine, methamphetamine, heroin and cannabis can promote dental caries. Many medicinal drugs facilitate the formation of dental caries, through various mechanisms; they include formulations with a high sugar content; drugs that cause dry mouth (especially antimuscarinics); drugs that lower the buccal pH (inhaled powders, etc.); and drugs that cause demineralisation (tetracyclines, etc.). In practice, patients (and parents) should be informed that some drugs can increase the risk of dental caries. They should be encouraged to adapt and reinforce dental hygiene, and advised to visit a dentist regularly.

  3. Silicon Deep Etching Techniques for MEMS Devices

    Institute of Scientific and Technical Information of China (English)

    WU Ying; OU Yi-hong; JIANG Yong-qing; LI Bin

    2003-01-01

    Silicon deep etching technique is the key fabrication step in the development of MEMS. The mask selectivity and the lateral etching control are the two primary factors that decide the result of deep etching process. These two factors are studied in this paper. The experimental results show that the higher selectivity can be gotten when F- gas is used as etching gas and Al is introduced as mask layer. The lateral etching problems can be solved by adjusting the etching condition, such as increasing the RF power, changing the gas composition and flow volume of etching machine.

  4. Effect of postoperative bleaching on microleakage of etch-and-rinse and self-etch adhesives

    Directory of Open Access Journals (Sweden)

    Vajihesadat Mortazavi

    2011-01-01

    Full Text Available Background: Bleaching the discoloured teeth may affect the tooth/composite interface. The aim of this in vitro experimental study was to evaluate the effect of vital tooth bleaching on microleakage of existent class V composite resin restorations bonded with three dental bonding agents. Methods : Class V cavities were prepared on buccal surfaces of 72 intact, extracted human anterior teeth with gingival margins in dentin and occlusal margins in enamel, and randomly divided into 3 groups. Cavities in the three groups were treated with Scotch bond Multi-Purpose, a total etch system and Prompt L-Pop and iBond, two self-etch adhesives. All teeth were restored with Z250 resin composite material and thermo-cycled. Each group was equally divided into the control and the bleached subgroups (n = 12. The bleached subgroups were bleached with 15% carbamide peroxide gel for 8 hours a day for 15 days. Microleakage scores were evaluated on the incisal and cervical walls. Data were analyzed using Kruskal-Wallis, Mann-Whitney and Bonferroni post-hoc tests (α = 0.05. Results: Bleaching with carbamide peroxide gel significantly increased the microleakage of composite restorations in Prompt L-Pop group at dentinal walls (P = 0.001. Bleaching had no effect on microleakage of restorations in the Scotch bond Multi-Purpose and iBond groups. Conclusion: Vital tooth bleaching with carbamide peroxide gel has an adverse effect on marginal seal of dentinal walls of existent composite resin restorations bonded with prompt L-Pop self-etch adhesive.

  5. Association of dental enamel lead levels with risk factors for environmental exposure

    Directory of Open Access Journals (Sweden)

    Kelly Polido Kaneshiro Olympio

    2010-10-01

    Full Text Available OBJECTIVE: To analyze household risk factors associated with high lead levels in surface dental enamel. METHODS: A cross-sectional study was conducted with 160 Brazilian adolescents aged 14-18 years living in poor neighborhoods in the city of Bauru, southeastern Brazil, from August to December 2008. Body lead concentrations were assessed in surface dental enamel acid-etch microbiopsies. Dental enamel lead levels were measured by graphite furnace atomic absorption spectrometry and phosphorus levels were measured by inductively coupled plasma optical emission spectrometry. The parents answered a questionnaire about their children's potential early (05 years old exposure to well-known lead sources. Logistic regression was used to identify associations between dental enamel lead levels and each environmental risk factor studied. Social and familial covariables were included in the models. RESULTS: The results suggest that the adolescents studied were exposed to lead sources during their first years of life. Risk factors associated with high dental enamel lead levels were living in or close to a contaminated area (OR = 4.49; 95% CI: 1.69;11.97; and member of the household worked in the manufacturing of paints, paint pigments, ceramics or batteries (OR = 3.43; 95% CI: 1.31;9.00. Home-based use of lead-glazed ceramics, low-quality pirated toys, anticorrosive paint on gates and/or sale of used car batteries (OR = 1.31; 95% CI: 0.56;3.03 and smoking (OR = 1.66; 95% CI: 0.52;5.28 were not found to be associated with high dental enamel lead levels. CONCLUSIONS: Surface dental enamel can be used as a marker of past environmental exposure to lead and lead concentrations detected are associated to well-known sources of lead contamination.

  6. Effect of Zirconia Dental Implant Surfaces on Bone Integration: A Systematic Review and Meta-Analysis

    Science.gov (United States)

    2017-01-01

    Background. The information available about osseointegration and the bone to implant interaction of zirconia implants with various surface modifications is still far from sufficient. Objective. The purpose of this systematic review and meta-analysis was to evaluate and compare zirconia dental implants with different surface topographies, with a focus on bone to implant contact and removal torque. Methods. The systematic review of the extracted publications was performed to compare the bone to implant contact (BIC) with removal torque (RT) values of titanium dental implants and machined and surfaced modified zirconia implants. Results. A total of fifteen articles on BIC and RT values were included in the quantitative analysis. No significant difference in the BIC values was observed between titanium and machined zirconia implants (p = 0.373; 95% CI: −0.166 to 0.443). However, a significantly better BIC values were observed for acid etched zirconia implants compared with those of titanium implants (p = 0.032; 95% CI: 0.068 to 1.461). Unmodified zirconia implants showed favorable BIC values compared to modified-surface zirconia implants (p = 0.021; 95% CI: −0.973 to −0.080). Conclusion. Acid etched zirconia implants may serve as a possible substitute for successful osseointegration. PMID:28299337

  7. About Dental Amalgam Fillings

    Science.gov (United States)

    ... Medical Procedures Dental Devices Dental Amalgam About Dental Amalgam Fillings Share Tweet Linkedin Pin it More sharing ... I have my fillings removed? What is dental amalgam? Dental amalgam is a dental filling material used ...

  8. Regenerative Electroless Etching of Silicon.

    Science.gov (United States)

    Kolasinski, Kurt W; Gimbar, Nathan J; Yu, Haibo; Aindow, Mark; Mäkilä, Ermei; Salonen, Jarno

    2017-01-09

    Regenerative electroless etching (ReEtching), described herein for the first time, is a method of producing nanostructured semiconductors in which an oxidant (Ox1 ) is used as a catalytic agent to facilitate the reaction between a semiconductor and a second oxidant (Ox2 ) that would be unreactive in the primary reaction. Ox2 is used to regenerate Ox1 , which is capable of initiating etching by injecting holes into the semiconductor valence band. Therefore, the extent of reaction is controlled by the amount of Ox2 added, and the rate of reaction is controlled by the injection rate of Ox2 . This general strategy is demonstrated specifically for the production of highly luminescent, nanocrystalline porous Si from the reaction of V2 O5 in HF(aq) as Ox1 and H2 O2 (aq) as Ox2 with Si powder and wafers.

  9. Dental trauma associated with high impact sport

    Directory of Open Access Journals (Sweden)

    Marcelo Coelho Goiato

    2015-01-01

    Full Text Available The objective of this study was to report a case of tooth fracture during the sport practice and the treatment performed for the patient. A 17-year-old male patient was subjected to an endontic treatment followed by the reattachment of the fractured teeth. Teeth were endodontically treated by conventional method. After, the acid etching with 37% phosphoric acid gel was performed and a bonding agent was applied on the dental surface. The fragments were reattachment and bonded with minimum amount of composite resin since the teeth/fragment interface was small. The occlusal contacts were adjusted in the finish line of restorations with a diamond bur and the polishing was performed with aluminum oxide discs. Positive esthetical and periodontal outcomes with no complications in the endodontic treatment were observed on radiographic examinations after twelve months of follow up. The endodontic treatment associated with the reattachment of the fractured teeth by a bonding procedure was a conservative treatment for the patient. The use of mouthguards is important to prevent such dramatic events.

  10. Detection of HEMA in self-etching adhesive systems with high performance liquid chromatography

    Science.gov (United States)

    Panduric, V.; Tarle, Z.; Hameršak, Z.; Stipetić, I.; Matosevic, D.; Negovetić-Mandić, V.; Prskalo, K.

    2009-04-01

    One of the factors that can decrease hydrolytic stability of self-etching adhesive systems (SEAS) is 2-hydroxymethylmethacrylate (HEMA). Due to hydrolytic instability of acidic methacrylate monomers in SEAS, HEMA can be present even if the manufacturer did not include it in original composition. The aim of the study was to determine the presence of HEMA because of decomposition by hydrolysis of methacrylates during storage, resulting with loss of adhesion strength to hard dental tissues of the tooth crown. Three most commonly used SEAS were tested: AdheSE ONE, G-Bond and iBond under different storage conditions. High performance liquid chromatography analysis was performed on a Nucleosil C 18-100 5 μm (250 × 4.6 mm) column, Knauer K-501 pumps and Wellchrom DAD K-2700 detector at 215 nm. Data were collected and processed by EuroCrom 2000 HPLC software. Calibration curves were made related eluted peak area to known concentrations of HEMA (purchased from Fluka). The elution time for HEMA is 12.25 min at flow rate 1.0 ml/min. Obtained results indicate that no HEMA was present in AdheSE ONE because methacrylates are substituted with methacrylamides that seem to be more stable under acidic aqueous conditions. In all other adhesive systems HEMA was detected.

  11. Effect of benzotriazole on the anisotropic electrolytic etching of copper

    Energy Technology Data Exchange (ETDEWEB)

    Papapanayiotou, D.; Deligianni, H.; Alkire, R.C. [Univ. of Illinois, Urbana, IL (United States)

    1998-09-01

    Electrolytic etching of copper foil at the base of cavities formed by patterned photoresist was investigated in 0.5 M sulfuric acid solutions which either contained 40 mM benzotriazole (BTA) or were free of BTA. It was found that undercutting (metal dissolution beneath the photoresist) was minimized by the action of surface films in both solutions. It was also found that the nature of the surface films and the mechanism by which they enhanced etch anisotropy differed. In additive-free solutions, anisotropic etching was observed under conditions of applied potential and flow for which mass transfer was suppressed in the interior corner regions of cavities. Such operating conditions in additive-free solutions displayed characteristic current transients. In BTA-containing solutions, the etch profiles were highly dependent on applied potential. In contrast to the additive-free solutions, the flow conditions in BTA-containing solutions had little effect on the current transients or on the degree of undercutting within the region of applied potential in which anisotropic etching was achievable.

  12. 丹酚酸B对人牙本质自酸蚀粘结强度的影响%Effect of Salvianolic Acid B on the Bond Strength of Self- etch Adhesive System to Human Dentin.

    Institute of Scientific and Technical Information of China (English)

    杨光; 袁柱炫

    2011-01-01

    目的:探讨丹酚酸B对牙本质自酸蚀粘结即刻及长期粘结强度的影响.方法:将10颗新鲜拔除的人下颌第三磨牙去除牙 合面牙釉质,暴露中层牙本质,打磨后制备出标准粘结面,以硬组织切片机将每颗牙均分为近中及远中两部分,自凝塑料包埋牙根,随机选取每颗实验牙的近中或远中部分共10个牙体单位于牙本质粘结面涂布两层Adper Prompt自酸蚀粘结剂(3M ESPE),光固化10 s后以Filtek Z350通用型纳米树脂(3M ESPE)堆塑5 mm高的树脂核;其余10个牙体单位则先以丹酚酸B处理牙本质粘结面,再以相同方法与材料制作树脂核.以硬组织切片机将各牙体单位切为1 mm×1 mm×8 mm的微拉伸试件,每个牙体单位选出2个试件并随机分组,最终形成A1、A2、B1、B2四组(n=10),A1设为对照组.对A1、B1组试件进行即刻微拉伸强度测试,A2、B2组试件水储6个月后进行微拉伸强度测试,评估其粘结强度.实验所得结果采用SPSS18.0软件进行ANOVA两因素方差分析和LSD多重检验.结果:丹酚酸B处理与未处理组的即刻微拉伸强度分别为(40.05±2.24) MPa、(41.58±1.98) MPa,两组即刻粘结强度无统计学差异;6个月水储后丹酚酸B处理组微拉伸强度为(18.96±2.05) MPa,高于未处理组(13.14±2.17) MPa (P<0.05).结论:丹酚酸B对牙本质自酸蚀粘结的即刻粘结强度没有明显影响,但能有效减缓长期(6个月)粘结强度的降.%Objective: To evaluate the effect of salvianolic acid B (one kind of matrix metalloproteinase inhibitor) on micro tensile bond strength (TBS) of self-etch adhesive system to human dentin.Methods: The occlusal enamal of 10 extracted lower third molars was removed to expose the flat middle coronal dentin and the dentin surfaces were grounded to standard adhesive surfaces.Each tooth was divided into mesial and distal parts equally and the roots were embedded in self-curing resin.One part of each tooth was randomly taken to be

  13. Methods for dry etching semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Todd; Gross, Andrew John; Clews, Peggy J.; Olsson, Roy H.

    2016-11-01

    The present invention provides methods for etching semiconductor devices, such aluminum nitride resonators. The methods herein allow for devices having improved etch profiles, such that nearly vertical sidewalls can be obtained. In some examples, the method employs a dry etch step with a primary etchant gas that omits BCl.sub.3, a common additive.

  14. Clinical and Radiographic Evaluation of Immediate Loaded Dental Implants With Local Application of Melatonin: A Preliminary Randomized Controlled Clinical Trial.

    Science.gov (United States)

    El-Gammal, Mona Y; Salem, Ahmed S; Anees, Mohamed M; Tawfik, Mohamed A

    2016-04-01

    Immediate loading of dental implants in situations where low bone density exist, such as the posterior maxillary region, became possible recently after the introduction of biomimetic agents. This 1-year preliminary clinical trial was carried out to clinically and radiographically evaluate immediate-loaded 1-piece implants with local application of melatonin in the osteotomy site as a biomimetic material. 14 patients with missing maxillary premolars were randomized to receive 14 implants of 1-piece type that were subjected to immediate loading after 2 weeks of initial placement. Group I included 7 implants with acid-etched surface while group II included 7 implants with acid-etched surface combined with local application of melatonin gel at the osteotomy site. Patients were recalled for follow up at 1, 3, 6, and 12 months after loading. All implants were considered successful after 12 months of follow-up. Significant difference (P implant loading when considering the implant stability. At 1 and 3 months there were significant differences in the marginal bone level between the 2 groups. These results suggest that the local application of melatonin at the osteotomy site is associated with good stability and minimal bone resorption. However, more studies for longer follow-up periods are required to confirm the effect of melatonin hormone on osseointegration of dental implants.

  15. Transcriptional profiling of suberoylanilide hydroxamic acid (SAHA regulated genes in mineralizing dental pulp cells at early and late time points

    Directory of Open Access Journals (Sweden)

    Henry F. Duncan

    2015-09-01

    Full Text Available Dental pulp tissue can be damaged by a range of irritants, however, if the irritation is removed and/or the tooth is adequately restored, pulp regeneration is possible (Mjör and Tronstad, 1974 [1]. At present, dental restorative materials limit healing by impairing mineralization and repair processes and as a result new biologically-based materials are being developed (Ferracane et al., 2010 [2]. Previous studies have highlighted the benefit of epigenetic modification by histone deacetylase inhibitor (HDACi application to dental pulp cells (DPCs, which induces changes to chromatin architecture, promoting gene expression and cellular-reparative events (Duncan et al., 2013 [3]; Paino et al., 2014 [4]. In this study a genome-wide transcription profiling in epigenetically-modified mineralizing primary DPC cultures was performed, at relatively early and late time-points, to identify differentially regulated transcripts that may provide novel therapeutic targets for use in restorative dentistry. Here we provide detailed methods and analysis on these microarray data which has been deposited in Gene Expression Omnibus (GEO: GSE67175.

  16. Post-synthetic Anisotropic Wet-Chemical Etching of Colloidal Sodalite ZIF Crystals

    Science.gov (United States)

    Avci, Civan; Ariñez-Soriano, Javier; Carné-Sánchez, Arnau; Guillerm, Vincent; Carbonell, Carlos; Imaz, Inhar; Maspoch, Daniel

    2016-01-01

    Controlling the shape of metal-organic framework (MOF) crystals is important for understanding their crystallization and useful for myriad applications. However, despite the many advances in shaping of inorganic nanoparticles, post-synthetic shape control of MOFs and, in general, molecular crystals remains embryonic. Herein we report using a simple wet-chemistry process at room temperature to control the anisotropic etching of colloidal ZIF-8 and ZIF-67 crystals. Our work enables uniform reshaping of these porous materials into unprecedented morphologies, including cubic and tetrahedral crystals, and even hollow boxes, via acid-base reaction and subsequent sequestration of leached metal ions. Etching tests on these ZIFs reveal that etching occurs preferentially in the crystallographic directions richer in metal-ligand bonds; that, among these directions, the etching rate tends to be faster on the crystal surfaces of higher dimensionality; and that the etching can be modulated by adjusting the pH of the etchant solution. PMID:26458081

  17. Note: Dissolved hydrogen detection in power transformer oil based on chemically etched fiber Bragg grating.

    Science.gov (United States)

    Jiang, Jun; Ma, Guo-ming; Song, Hong-tu; Zhou, Hong-yang; Li, Cheng-rong; Luo, Ying-ting; Wang, Hong-bin

    2015-10-01

    A fiber Bragg grating (FBG) sensor based on chemically etched cladding to detect dissolved hydrogen is proposed and studied in this paper. Low hydrogen concentration tests have been carried out in mixed gases and transformer oil to investigate the repeatability and sensitivity. Moreover, to estimate the influence of etched cladding thickness, a physical model of FBG-based hydrogen sensor is analyzed. Experimental results prove that thin cladding chemically etched by HF acid solution improves the response to hydrogen detection in oil effectively. At last, the sensitivity of FBG sensor chemically etched 16 μm could be as high as 0.060 pm/(μl/l), increased by more than 30% in comparison to un-etched FBG.

  18. Effect of acid etching and desensitization on the bonding strength of dentin and zirconia%脱敏及脱敏后酸蚀对牙本质与氧化锆粘结强度的影响

    Institute of Scientific and Technical Information of China (English)

    邓琳琳; 王璐; 邱雨; 付钢

    2014-01-01

    Objective:To evaluate the effects of acid etching and two kinds desensitizing agents on zirconia and dentin in order to provide references for clinical treatment.Methods:Fifty molars(the third molar) without caries were collected and the crowns of the molars were removed to expose the dentin.All samples were divided into control group A and experimental groups B,B1,C,C1 (n=10).All 50 molars were immersed into 1∶3 fetal bovine serum solution and were taken out 1 d after.No treatment was made in group A;molars in groups B and B 1 were coated by Gluma desensitizer; molars of groups C,and C 1 were treated by water.Before bonding,molars in groups B1 and C1 were treated by phosphoric acid for 15 seconds while no treatment was made in other groups.The dentin of specimens were bonded with zirconia with the same size at the bottom and the shear strength was determined.The results were analyzed by software of SPSS 17.0.Results:The bonding strength:A group(9.626 ± 0.318) MPa,B group(12.577 ± 0.374) MPa,B1 group (15.650 ± 0.344) MPa,C group(9.530 ± 0.391) MPa,C1 group(12.740 ± 0.310) MPa.There were statistical differences between groups(P<0.05) except comparison between group A and group C(P>0.05) and between group B and group C1 (P>0.05).Conclusion:Gluma desensitizer can enhance the bonding strength of Rely XTM Unicem on dentin.Proper phosphoric acid etching of dentin treated by water laser or Gluma desensitization can enhance the bonding strength of Rely XTM Unicem on dentin.%目的:比较2种脱敏方式及脱敏后酸蚀对氧化锆与牙本质粘结强度的影响,为其临床应用提供实验依据.方法:收集无龋完整的第三磨牙50颗,截去冠端,暴露牙本质,将其随机分成对照组A、实验组B、B1和C、C1(n=10),均浸入1∶3稀释的胎牛血清溶液备用.1d后取出,A组无处理,B、B1组涂布Gluma脱敏剂,C、C1组用水激光处理.粘结前B1、C1组磷酸酸蚀15s,其余各组不处理,各标本牙本质

  19. Effect of IRM on human dental pulp.

    Science.gov (United States)

    Möller, B; Schröder, U; Granath, L

    1983-08-01

    IRM has been shown to be superior to conventional ZnOE cements. This study is a biotechnical investigation of IRM's effect on the dental pulp with respect to its sealing capacity. Enamel-dentin test bodies with IRM fillings were used in the in vitro part, where insufficiencies in sealing were detected with compressed air. The in vivo part included 44 buccal cavities in intact premolars. In teeth in which the material effect of IRM was tested, the IRM fillings were sealed off from the saliva by acid etch and composite resin. The observation intervals were 1, 7 and 28 days. Histologic changes such as capillary dilatations and presence of inflammatory cells in the pulp adjacent to the dentinal tubules involved in the cavity preparation were registered. The in vitro test showed no leakage in five cases out of six. After extreme temperature cycling, the leakage was comparable with that of zinc-containing amalgam of traditional alloy. The pulpal changes were mild and mainly ascribed to the material effect of IRM, since no evidence was found of leakage of biologic importance.

  20. Imunohistological aspects of the tissue around dental implants

    Science.gov (United States)

    Nimigean, Victor; Nimigean, Vanda R.; Sǎlǎvǎstru, Dan I.; Moraru, Simona; BuÅ£incu, Lavinia; Ivaşcu, Roxana V.; Poll, Alexandru

    2016-03-01

    Objectives: study of soft and hard tissues around implants. Material and methods: For the immunohistochemical and histological study of the implant/soft tissue interface, we examined pieces of peri-implant mucosa harvested from 35 patients. The implant/bone interface was assessed using histologic and histomorphometric examination of hard tissues around unloaded, early loaded or delayed loaded dental implants with pre-established design, with a sandblasted and acid-etched surface, placed both in extraction sockets, or after bone healing following tooth removal. This study was performed on 9 common race dogs. Results: The histological study of the implant/soft tissue interface showed regenerative modifications and moderate chronic subepithelial inflammatory reactions. Immunohistochemical evaluation of the soft tissue biopsies revealed the presence of specific immunocompetent cells and proteins of the matrix metalloproteinase (MMP) expression. Bone-implants contacts were more obvious in the apical half of the implants and at the edges of the threads, than between them. A mature, lamelliform bone containing lacunae with osteocytes and lack of connective tissue were noticed around implants that were late placed and loaded. The new-formed bone was also abundant in the crestal zone, not only in the apical part of the implants. Conclusions: A thorough understanding of the microstructure of dental implant/soft and hard tissue interface will improve the longevity of osseointegrated implants.

  1. Addition of Grape Seed Extract Renders Phosphoric Acid a Collagen-stabilizing Etchant.

    Science.gov (United States)

    Liu, Y; Dusevich, V; Wang, Y

    2014-08-01

    Previous studies found that grape seed extract (GSE), which is rich in proanthocyanidins, could protect demineralized dentin collagen from collagenolytic activities following clinically relevant treatment. Because of proanthocyanidin's adverse interference to resin polymerization, it was believed that GSE should be applied and then rinsed off in a separate step, which in effect increases the complexity of the bonding procedure. The present study aimed to investigate the feasibility of combining GSE treatment with phosphoric acid etching to address the issue. It is also the first attempt to formulate collagen-cross-linking dental etchants. Based on Fourier-transformed infrared spectroscopy and digestion assay, it was established that in the presence of 20% to 5% phosphoric acid, 30 sec of GSE treatment rendered demineralized dentin collagen inert to bacterial collagenase digestion. Based on this positive result, the simultaneous dentin etching and collagen protecting of GSE-containing phosphoric acid was evaluated on the premise of a 30-second etching time. According to micro-Raman spectroscopy, the formulation containing 20% phosphoric acid was found to lead to overetching. Based on scanning and transmission electronic microscopy, this same formulation exhibited unsynchronized phosphoric acid and GSE penetration. Therefore, addition of GSE did render phosphoric acid a collagen-stabilizing etchant, but the preferable phosphoric acid concentration should be <20%.

  2. Study of Thermal Electrical Modified Etching for Glass and Its Application in Structure Etching

    Directory of Open Access Journals (Sweden)

    Zhan Zhan

    2017-02-01

    Full Text Available In this work, an accelerating etching method for glass named thermal electrical modified etching (TEM etching is investigated. Based on the identification of the effect in anodic bonding, a novel method for glass structure micromachining is proposed using TEM etching. To validate the method, TEM-etched glasses are prepared and their morphology is tested, revealing the feasibility of the new method for micro/nano structure micromachining. Furthermore, two kinds of edge effect in the TEM and etching processes are analyzed. Additionally, a parameter study of TEM etching involving transferred charge, applied pressure, and etching roughness is conducted to evaluate this method. The study shows that TEM etching is a promising manufacture method for glass with low process temperature, three-dimensional self-control ability, and low equipment requirement.

  3. Current dental adhesives systems. A narrative review.

    Science.gov (United States)

    Milia, Egle; Cumbo, Enzo; Cardoso, Rielson Jose A; Gallina, Giuseppe

    2012-01-01

    Adhesive dentistry is based on the development of materials which establish an effective bond with the tooth tissues. In this context, adhesive systems have attracted considerable research interest in recent years. Successful adhesive bonding depends on the chemistry of the adhesive, on appropriate clinical handling of the material as well as on the knowledge of the morphological changes caused on dental tissue by different bonding procedures. This paper outlines the status of contemporary adhesive systems, with particular emphasis on chemical characteristics and mode of interaction of the adhesives with enamel and dentinal tissues. Dental adhesives are used for several clinical applications and they can be classified based on the clinical regimen in "etch-and-rinse adhesives" and "self-etch adhesives". Other important considerations concern the different anatomical characteristics of enamel and dentine which are involved in the bonding procedures that have also implications for the technique used as well as for the quality of the bond. Etch-and-rinse adhesive systems generally perform better on enamel than self-etching systems which may be more suitable for bonding to dentine. In order to avoid a possible loss of the restoration, secondary caries or pulp damage due to bacteria penetration or due to cytotoxicity effects of eluted adhesive components, careful consideration of several factors is essential in selecting the suitable bonding procedure and adhesive system for the individual patient situation.

  4. Effect of Different Disinfection Protocols on Microbial and Biofilm Contamination of Dental Unit Waterlines in Community Dental Practices

    OpenAIRE

    2014-01-01

    Output water from dental unit waterlines (DUWLs) may be a potential source of infection for both dental healthcare staff and patients. This study compared the efficacy of different disinfection methods with regard to the water quality and the presence of biofilm in DUWLs. Five dental units operating in a public dental health care setting were selected. The control dental unit had no disinfection system; two were disinfected intermittently with peracetic acid/hydrogen peroxide 0.26% and two un...

  5. Bonding of dental porcelain to non-cast titanium with different surface treatments.

    Science.gov (United States)

    Lin, Mau-Chin; Tung, Kuo-Lung; Lin, Sheng-Chieh; Huang, Her-Hsiung

    2012-01-01

    This study investigated the bonding of dental porcelain to non-cast Ti surface with different treatments. Mechanically ground non-cast Ti strips, simulating surface conditions produced by CAD/CAM, were Al(2)O(3)-sandblasted, then subjected to different surface treatments, including immersion in HNO(3)-containing acid, NaOH-containing alkaline, and NaOH-containing alkaline then HNO(3)-containing acid. Ti-porcelain specimens preparations and their bend strength measurements were based on ISO 9693. Ti surface treatment changed not only surface roughness but also surface chemistry, leading to influence on bond strength. Bond strengths of all Ti-porcelain groups were higher than ISO 9693 minimum requirement. The sandblasted/acid-treated Ti surface showed the highest bond strength (34.60 MPa) with porcelain; no significant difference in bond strength (27.92-29.63 MPa) was found among other Tiporcelain groups. All Ti-porcelain specimens showed adhesive bond failure. Bonding between non-cast Ti and dental porcelain was strengthened by a simple and practical sandblasting/acid-etching treatment of the Ti surface prior to porcelain sintering.

  6. The inhibitory effects of chlorogenic acid on dental caries in rats%绿原酸防龋的实验研究

    Institute of Scientific and Technical Information of China (English)

    林家成; 赵玮; 卢佳璇

    2012-01-01

    Objective To observe the effect of chlorogenic acid on dental caries. Methods The antibacterial activities of chlorogenic acid on Streptococcus mutatis ATCC 10449 and Streptococcus sobrinus OMZ65 were investigated. SD rats (re =30) were fed with cariogenic forage 2000# and infected with Streptococcus mutans. The rats were divided into 3 groups, and each group was fed with chlorogenic acid, arilin chlorhexidine solutions or distilled water. The effects of chlorogenic acid on dental caries development in SD rats were measured with Keyes scoring method. Results The MIC of the Streptococcus mutans ATCC 10449 and Streptococcus sobrinus OMZ65 were 2. 5 mg/mL. The MBC of the Streptococcus mutans ATCC 10449 and Streptococcus sobrinus OMZ65 were 7.5 mg/mL and 5 mg/mL, respectively. According to the Keyes method, at E,Ds,Dm and Dx level,the scores were lower in chlorogenic acid-treated group when compared with the distilled water control group,but there was no significant difference between the chlorogenic acid- and arilin chlorhexidine solutions-treated groups. Conclusion Chlorogenic acid may inhibit the growth of Streptococcus mutans and Streptococcus sobrinus, and the development of dental caries in SD rats.%目的 研究绿原酸对龋病发生发展的抑制效果.方法 制备不同浓度绿原酸,采用液体稀释法检测其体外抑制变形链球菌和远缘链球菌的效果;建立SD大鼠人工龋模型,分别用绿原酸溶液、甲硝唑洗必泰溶液和蒸馏水给大鼠施药,采用Keyes记分法观察绿原酸对大鼠口腔内龋齿发生发展的抑制效果.结果 绿原酸溶液对变形链球菌ATCC10449株和远缘链球菌OMZ65株的最小抑菌浓度均为2.5 mg/mL,最小杀菌浓度分别为7.5 mg/mL和5 mg/mL.在人工龋大鼠模型中,与蒸馏水相比,绿原酸组龋齿计分明显降低,而与甲硝唑洗必泰组相近.结论 绿原酸对变形链球菌和远缘链球菌生长有明显抑制作用,并可有效抑制大鼠龋齿的发生发展.

  7. 唑来膦酸促进口腔种植体骨结合的研究现状%Zoledronic acid promotes osseointegration of dental implant

    Institute of Scientific and Technical Information of China (English)

    谢淑娟; 占柳

    2012-01-01

    种植体的骨整合是目前口腔学界种植义齿的研究热点.改善种植体的骨结合,增加种植体周围的骨量,可以较好的提高种植体的稳定性,从而提高种植体成功率和延长种植体使用寿命.双磷酸盐( bisphosphonate,BPs)类药物的新生力量——唑来膦酸( Zoledronic acid),以其在BPs类药物中具有最强效的抗骨质吸收能力吸引了众多关注,在临床成功应用后,口腔专家进一步研究其在种植体方面的良好效应,通过多项实验项目观察发现其具有改善种植体骨结合的效用,并且与其他药物联合应用时可以得到更好的效果,有望投入临床,应用前景不可小觑.%Osseointegration is now the focus of research on dental implant. It can improve the stability of the implant, and hence increase its success rate and prolong its life. Bisphosphonates-zoledronic acid, with its most powerful anti-bone resorption ability among bisphosphonates (BPs) , has attracted a lot of attention to the very success in its clinical application. Recently, dental experts have further studied its good effects in tooth implant by a number of pilot projects. Experiments show that it can improve osseointegration and produce better effect when combined with other drugs.

  8. Bacteriostatic and anti-collagenolytic dental materials through the incorporation of polyacrylic acid modified CuI nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Renne, Walter George; Mennito, Anthony Samuel; Schmidt, Michael Gerard; Vuthiganon, Jompobe; Chumanov, George

    2015-05-19

    Provided are antibacterial and antimicrobial surface coatings and dental materials by utilizing the antimicrobial properties of copper chalcogenide and/or copper halide (CuQ, where Q=chalcogens including oxygen, or halogens, or nothing). An antimicrobial barrier is created by incorporation of CuQ nanoparticles of an appropriate size and at a concentration necessary and sufficient to create a unique bioelectrical environment. The unique bioelectrical environment results in biocidal effectiveness through a multi-factorial mechanism comprising a combination of the intrinsic quantum flux of copper (Cu.sup.0, Cu.sup.1+, Cu.sup.2+) ions and the high surface-to-volume electron sink facilitated by the nanoparticle. The result is the constant quantum flux of copper which manifests and establishes the antimicrobial environment preventing or inhibiting the growth of bacteria. The presence of CuQ results in inhibiting or delaying bacterial destruction and endogenous enzymatic breakdown of the zone of resin inter-diffusion, the integrity of which is essential for dental restoration longevity.

  9. Sistemas adhesivos autograbadores en esmalte: ventajas e inconvenientes Self-etching adhesive systems on enamel: advantages and disadvantages

    Directory of Open Access Journals (Sweden)

    M.A Gomes Moreira

    2004-08-01

    Full Text Available Se mide la resistencia adhesiva de cinco sistemas adhesivos autograbadores y se compara con dos monocomponentes, en esmalte bovino, utilizando cuatro protocolos de aplicación diferentes (según fabricante, con ácido, dos tiempos y dos capas. Asimismo se evalúan con MEB los patrones de grabado ácido de estos sistemas adhesivos, muy heterogéneos en los autograbadores. Todos los sistemas autograbadores presentan valores aceptables de resistencia adhesiva.The bond strength to bovine enamel of five self-etching adhesive systems was measured comparing to two total etch adhesive systems and using different application modes (following manufacturers' instructions, with a previous acid etching, duplicating priming time and doubling the number of adhesives' layers. The etching patterns were analized with scanning electron microscopy showing the self-etching adhesives different aggressiveness. All self-etching systems showed reliable bond strength values.

  10. Dental erosion and sulfuric ion exposure levels in individuals working with sulfuric acid in lead storage battery manufacturing plant measured with mouth-rinse index.

    Science.gov (United States)

    Suyama, Yuji; Takaku, Satoru; Okawa, Yoshikazu; Matsukubo, Takashi

    2010-01-01

    To investigate dental erosion in employees working with sulfuric acid at a lead storage battery manufacturing plant and level of personal exposure to sulfuric ions, we measured sulfuric ion concentrations in the mouth rinse of those employees. We also measured exposure levels from air samples obtained from 2 employees from the same plant who did not work with sulfuric acid using a portable air sampler. At the same time, we collected and compared their mouth rinses with those from other employees. More specifically, we measured and compared sulfuric ion, calcium, and magnesium concentrations, along with pH levels from the mouth rinse of these two groups. Positive correlations were found between sulfuric ion and calcium concentrations (r=0.61, p<0.005), calcium and magnesium concentrations (r=0.61, p<0.005), Ca/Mg and calcium concentrations (r=0.64, p<0.005), and sulfuric ion and magnesium concentrations (r=0.55, p<0.005). Negative correlations were found between sulfuric ion concentrations and pH levels (r=-0.31, p<0.01), and magnesium concentrations and pH levels (r=-0.32, p<0.01). This suggests that mouth rinse from employees working with sulfuric acid could function as an indicator of sulfuric ion concentration in the work environment. Furthermore, this could lead to the development of a more accurate indicator of individual exposure.

  11. Dental OCT

    Science.gov (United States)

    Wilder-Smith, Petra; Otis, Linda; Zhang, Jun; Chen, Zhongping

    This chapter describes the applications of OCT for imaging in vivo dental and oral tissue. The oral cavity is a diverse environment that includes oral mucosa, gingival tissues, teeth and their supporting structures. Because OCT can image both hard and soft tissues of the oral cavity at high resolution, it offers the unique capacity to identity dental disease before destructive changes have progressed. OCT images depict clinically important anatomical features such as the location of soft tissue attachments, morphological changes in gingival tissue, tooth decay, enamel thickness and decay, as well as the structural integrity of dental restorations. OCT imaging allows for earlier intervention than is possible with current diagnostic modalities.

  12. Etching of glass microchips with supercritical water.

    Science.gov (United States)

    Karásek, Pavel; Grym, Jakub; Roth, Michal; Planeta, Josef; Foret, František

    2015-01-07

    A novel method of etching channels in glass microchips with the most tunable solvent, water, was tested as an alternative to common hydrogen fluoride-containing etchants. The etching properties of water strongly depend on temperature and pressure, especially in the vicinity of the water critical point. The chips were etched at the subcritical, supercritical and critical temperature of water, and the resulting channel shape, width, depth and surface morphology were studied by scanning electron microscopy and 3D laser profilometry. Channels etched with the hot water were compared with the chips etched with standard hydrogen fluoride-containing solution. Depending on the water pressure and temperature, the silicate dissolved from the glass could be re-deposited on the channel surface. This interesting phenomenon is described together with the conditions necessary for its utilization. The results illustrate the versatility of pure water as a glass etching and surface morphing agent.

  13. Etching.

    Science.gov (United States)

    1980-09-01

    4U c Z . CC 0.0 V 0-01w.0 OCMCC.Ca 0 II 4- 00 La-1 e - .- 0 04’ . £0 tO4 -u 41 ’ Dato C 5-4-00LLi1 c-1 C- - E-1 4-C0 V) -OU1 I~ rC ŔE 0 *z 0 LW 04 c...Z&.. 4.-c o x *C L )P0 A0 0 a54. U * 0 3 i;- L )I.. l C C -44.0 0 2 o; c 0. ama a- .u OE Voz 0 UL 0f ja - .a r DC L _j4 5c .,R r- C *.-* 0 - )W- . 0

  14. Selective etching of silicon carbide films

    Science.gov (United States)

    Gao, Di; Howe, Roger T.; Maboudian, Roya

    2006-12-19

    A method of etching silicon carbide using a nonmetallic mask layer. The method includes providing a silicon carbide substrate; forming a non-metallic mask layer by applying a layer of material on the substrate; patterning the mask layer to expose underlying areas of the substrate; and etching the underlying areas of the substrate with a plasma at a first rate, while etching the mask layer at a rate lower than the first rate.

  15. Dental sealants

    Science.gov (United States)

    ... few quick steps. There is no drilling or scraping of the molars. Your dentist will: Clean the ... Dental sealants. Updated October 19, 2016. ADA.org Web site. www.ada.org/en/member-center/oral- ...

  16. Silicon germanium mask for deep silicon etching

    KAUST Repository

    Serry, Mohamed

    2014-07-29

    Polycrystalline silicon germanium (SiGe) can offer excellent etch selectivity to silicon during cryogenic deep reactive ion etching in an SF.sub.6/O.sub.2 plasma. Etch selectivity of over 800:1 (Si:SiGe) may be achieved at etch temperatures from -80 degrees Celsius to -140 degrees Celsius. High aspect ratio structures with high resolution may be patterned into Si substrates using SiGe as a hard mask layer for construction of microelectromechanical systems (MEMS) devices and semiconductor devices.

  17. Black Germanium fabricated by reactive ion etching

    Science.gov (United States)

    Steglich, Martin; Käsebier, Thomas; Kley, Ernst-Bernhard; Tünnermann, Andreas

    2016-09-01

    A reactive ion etching technique for the preparation of statistical "Black Germanium" antireflection surfaces, relying on self-organization in a Cl2 etch chemistry, is presented. The morphology of the fabricated Black Germanium surfaces is the result of a random lateral distribution of pyramidal etch pits with heights around (1450 ± 150) nm and sidewall angles between 80° and 85°. The pyramids' base edges are oriented along the crystal directions of Germanium, indicating a crystal anisotropy of the etching process. In the Vis-NIR, the tapered Black Germanium surface structure suppresses interface reflection to structure in optoelectronics and IR optics.

  18. Dry etching technologies for reflective multilayer

    Science.gov (United States)

    Iino, Yoshinori; Karyu, Makoto; Ita, Hirotsugu; Kase, Yoshihisa; Yoshimori, Tomoaki; Muto, Makoto; Nonaka, Mikio; Iwami, Munenori

    2012-11-01

    We have developed a highly integrated methodology for patterning Extreme Ultraviolet (EUV) mask, which has been highlighted for the lithography technique at the 14nm half-pitch generation and beyond. The EUV mask is characterized as a reflective-type mask which is completely different compared with conventional transparent-type of photo mask. And it requires not only patterning of absorber layer without damaging the underlying multi reflective layers (40 Si/Mo layers) but also etching multi reflective layers. In this case, the dry etch process has generally faced technical challenges such as the difficulties in CD control, etch damage to quartz substrate and low selectivity to the mask resist. Shibaura Mechatronics ARESTM mask etch system and its optimized etch process has already achieved the maximal etch performance at patterning two-layered absorber. And in this study, our process technologies of multi reflective layers will be evaluated by means of optimal combination of process gases and our optimized plasma produced by certain source power and bias power. When our ARES™ is used for multilayer etching, the user can choose to etch the absorber layer at the same time or etch only the multilayer.

  19. Marginal microleakage of resin-modified glass-ionomer and composite resin restorations: Effect of using etch-and-rinse and self-etch adhesives

    Directory of Open Access Journals (Sweden)

    Maryam Khoroushi

    2012-01-01

    Full Text Available Objectives: Previous studies have shown that dental adhesives increase the bond strength of resin-modified glass-ionomer (RMGI restorative materials to dentin. This in vitro study has evaluated the effect of etch-and-rinse and self-etch bonding systems v/s cavity conditioner, and in comparison to similar composite resin restorations on maintaining the marginal sealing of RMGI restorations. Materials and Methods: 98 rectangular cavities (2.5×3×1.5 mm were prepared on buccal and palatal aspects of 49 human maxillary premolars, randomly divided into 7 groups (N=14. The cavities in groups 1, 2 and 3 were restored using a composite resin (APX. The cavities in groups 4, 5, 6 and 7 were restored using a resin-modified glass-ionomer (Fuji II LC. Before restoring, adhesive systems (Optibond FL = OFL, three-step etch-and-rinse; One Step Plus = OSP, two-step etch-and-rinse; Clearfil Protect Bond = CPB, two-step self-etch were used as bonding agents in groups 1-6 as follow: OFL in groups 1 and 4, OSP in groups 2 and 5, and CPB in groups 3 and 6, respectively. The specimens in group 7 were restored with GC cavity conditioner and Fuji II LC. All the specimens were thermo-cycled for 1000 cycles. Microleakage scores were determined using dye penetration method. Statistical analyzes were carried out with Kruskal-Wallis and Mann-Whitney U tests (α=0.05. Results: There were significant differences in microleakage scores at both enamel and dentinal margins between the study groups (P<0.05. The lowest microleakage scores at enamel and dentin margins of RMGI restorations were observed in group 6. Conclusion: Use of two-step self-etch adhesive, prior to restoring cervical cavities with RMGIC, seems to be more efficacious than the conventional cavity conditioner in decreasing marginal microleakage.

  20. Restoration of obliterated engraved marks on steel surfaces by chemical etching reagent.

    Science.gov (United States)

    Song, Qingfang

    2015-05-01

    Chemical etching technique is widely used for restoration of obliterated engraved marks on steel surface in the field of public security. The consumed thickness of steel surface during restoration process is considered as a major criterion for evaluating the efficiency of the chemical etching reagent. The thinner the consumed thickness, the higher the restoration efficiency. According to chemical principles, maintaining the continuous oxidative capabilities of etching reagents and increasing the kinetic rate difference of the reaction between the engraved and non-engraved area with the chemical etching reagent can effectively reduce the consumed steel thickness. The study employed steel surface from the engine case of motorcycle and the car frame of automobile. The chemical etching reagents are composed of nitric acid as the oxidizer, hydrofluoric acid as the coordination agent and mixed with glacial acetic acid or acetone as the solvents. Based on the performance evaluation of three different etching reagents, the one composed of HNO3, HF and acetone gave the best result.

  1. Infant dental care (image)

    Science.gov (United States)

    ... sugar water. As the child grows, establishing proper dental hygiene will promote healthy teeth and gums which are essential to overall good health. Poor dental development, dental disease, and dental trauma can result ...

  2. Etch Pits and Threading Dislocations in GaN Films Grown by Metal-Organic Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    陆敏; 常昕; 黎子兰; 杨志坚; 张国义; 章蓓

    2003-01-01

    High quality epitaxial GaN films on (0001) sapphire substrates were grown by a commercial metal-organic chemical vapour deposition system. The, etch pits and threading dislocations in GaN films is studied by a scanning electron microscope (SEM) and a transmission-electron microscope (TEM). The SEM images of GaN films, etched in mixed acid solution (H3PO4:H2SO4 = 1: 3) and molten KOH exhibit notably different, etching pit densities of 5 × 108/cm2 and 4 × 107/cm2, respectively, which probably indicate that more kinds of, etching pits were revealed when, etched in mixed acid solution (H3PO4:H2SO4 = 1: 3). Cross section TEM of GaN films with different g vectors showed the portions of different threading dislocations. Theoretical calculation indicates that the lattice and thermal expansion coefficient mismatch may be the main origins of pure edge threading dislocations.

  3. In vitro study of 980nm diode laser in dental implant disinfection

    Directory of Open Access Journals (Sweden)

    Fábio Gonçalves

    2009-12-01

    Full Text Available Objective: To evaluate the potential of 980nm diode laser to reduce bacteria after irradiation of three different dental implant surfaces contaminated with Enterococcus faecalis and Porphyromonas gingivalis, as well as the possible changes in the irradiated implant surfaces.Methods: Seventy two implants with machined surfaces, airborne particle abraded with titanium oxide and acid-etched surfaces were exposed to Enterococcus faecalis and Porphyromonas gingivalis cultures and irradiated with 980nm diode laser with power of 2.5 and 3,0W. After laser treatments, the number of remaining colony-forming units was studied and implant surface morphology was analyzed by scanning electron microscopy. Results: The results showed 100% reduction of the bacteria on the implants irradiated with 3.0W. Moreover, 100% reduction of bacteria was also achieved on the implant surfaces contaminated with Porphyromonas gingivalis when irradiated with 2.5W and 3.0W. Bacteria reduction was not complete for the implants contaminated with Enterococcus faecalis, irradiated with 2.5W and surfaces treated with TiO2 airborne particle abrasion (78.6% and acid etching (49.4%.The scanning electron microscopy analysis showed that at the power settings used, no implant surface changes were found. Conclusion: The 980nm diode laser was effective in decontaminating the Enterococcus faecalis and Porphyromonas gingivalis without promoting surface alteration in the implants.

  4. Stereo imaging and cytocompatibility of a model dental implant surface formed by direct laser fabrication.

    Science.gov (United States)

    Mangano, Carlo; Raspanti, Mario; Traini, Tonino; Piattelli, Adriano; Sammons, Rachel

    2009-03-01

    Direct laser fabrication (DLF) allows solids with complex geometry to be produced by sintering metal powder particles in a focused laser beam. In this study, 10 Ti6Al4V alloy model dental root implants were obtained by DLF, and surface characterization was carried out using stereo scanning electron microscopy to produce 3D reconstructions. The surfaces were extremely irregular, with approximately 100 microm deep, narrow intercommunicating crevices, shallow depressions and deep, rounded pits of widely variable shape and size, showing ample scope for interlocking with the host bone. Roughness parameters were as follows: R(t), 360.8 microm; R(z), 358.4 microm; R(a), 67.4 microm; and R(q), 78.0 microm. Disc specimens produced by DLF with an identically prepared surface were used for biocompatibility studies with rat calvarial osteoblasts: After 9 days, cells had attached and spread on the DLF surface, spanning across the crevices, and voids. Cell density was similar to that on a commercial rough microtextured surface but lower than on commercial smooth machined and smooth-textured grit-blasted, acid-etched surfaces. Human fibrin clot extension on the DLF surface was slightly improved by inorganic acid etching to increase the microroughness. With further refinements, DLF could be an economical means of manufacturing implants from titanium alloys.

  5. The effects of three different food acids on the attrition-corrosion wear of human dental enamel

    Science.gov (United States)

    Zhang, Yichi; Arsecularatne, Joseph A.; Hoffman, Mark

    2015-07-01

    With increased consumption of acidic drinks and foods, the wear of human teeth due to attrition in acidic environments is an increasingly important issue. Accordingly, the present paper investigates in vitro the wear of human enamel in three different acidic environments. Reciprocating wear tests in which an enamel cusp slides on an enamel flat surface were carried out using acetic, citric and lactic acid lubricants (at pH 3-3.5). Distilled water was also included as a lubricant for comparison. Focused ion beam milling and scanning electron microscopy imaging were then used to investigate the enamel subsurfaces following wear tests. Nanoindentation was used to ascertain the changes in enamel mechanical properties. The study reveals crack generation along the rod boundaries due to the exposure of enamel to the acidic environments. The wear mechanism changes from brittle fracture in distilled water to ploughing or shaving of the softened layer in acidic environments, generating a smooth surface with the progression of wear. Moreover, nanoindentation results of enamel samples which were exposed to the above acids up to a duration of the wear tests show decreasing hardness and Young’s modulus with exposure time.

  6. Anisotropic textured silicon obtained by stain-etching at low etching rates

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-DIaz, B [Departamento de Fisica Basica, Universidad de La Laguna, Avda, AstrofIsico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Guerrero-Lemus, R [Departamento de Fisica Basica, Universidad de La Laguna, Avda, AstrofIsico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Marrero, N [Departamento de Fisica Basica, Universidad de La Laguna, Avda, AstrofIsico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Hernandez-RodrIguez, C [Departamento de Fisica Basica, Universidad de La Laguna, Avda, AstrofIsico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Ben-Hander, F A [Departamento de Fisica Aplicada, C-XII, Universidad Autonoma de Madrid, 28049 Madrid (Spain); MartInez-Duart, J M [Departamento de Fisica Aplicada, C-XII, Universidad Autonoma de Madrid, 28049 Madrid (Spain)

    2006-02-21

    The structure, luminescence and etching kinetics for porous silicon stain-etched at different temperatures are studied. The results reveal that for temperatures below 10 deg. C and for short etching times, a novel anisotropic structure based on surface roughness preferentially oriented in the (100) direction is observed. At temperatures higher than 10 deg. C or large etching times, typical macropores and mesopores with non-preferential pore wall orientation are detected. The luminescence spectra of the samples with preferential surface roughness orientation are red-shifted with respect to the samples with typical isotropic orientation. The results are interpreted in terms of average etching rates and pore growth.

  7. Note: electrochemical etching of sharp iridium tips.

    Science.gov (United States)

    Lalanne, Jean-Benoît; Paul, William; Oliver, David; Grütter, Peter H

    2011-11-01

    We describe an etching procedure for the production of sharp iridium tips with apex radii of 15-70 nm, as determined by scanning electron microscopy, field ion microscopy, and field emission measurements. A coarse electrochemical etch followed by zone electropolishing is performed in a relatively harmless calcium chloride solution with high success rate.

  8. Etch selectivity of a wet chemical formulation for premetal cleaning

    Science.gov (United States)

    Epton, Jeremy W.; Jarrett, Deborah L.; Doohan, Ian J.

    2001-04-01

    This paper examines the relative etching rates of doped and thermal silicon dioxide when using NSSL etchant, comprising of a mixture of ammonium fluoride, water and ammonium dihydrogen phosphate [(NH4)H2PO4] and investigates their dependence on both temperature and mixture composition. The possible reaction mechanism is discussed and compared with the known mechanism for standard buffered oxide etchants (BOE). The observed etch selectivity and mechanisms of BOE and NSSL are also compared with the behavior of a third chemical formulation, referred to as mixed oxide etchant, which comprises of ammonium fluoride (NH4F) solution, diammonium hydrogen phosphate [(NH4)2HPO4] and orthophosphoric acid (H3PO4). It is concluded that no major change in oxide selectivity is observed if either BOE or NSSL etchants are used in the metal pre-clean process.

  9. Etching Behavior of Aluminum Alloy Extrusions

    Science.gov (United States)

    Zhu, Hanliang

    2014-11-01

    The etching treatment is an important process step in influencing the surface quality of anodized aluminum alloy extrusions. The aim of etching is to produce a homogeneously matte surface. However, in the etching process, further surface imperfections can be generated on the extrusion surface due to uneven materials loss from different microstructural components. These surface imperfections formed prior to anodizing can significantly influence the surface quality of the final anodized extrusion products. In this article, various factors that influence the materials loss during alkaline etching of aluminum alloy extrusions are investigated. The influencing variables considered include etching process parameters, Fe-rich particles, Mg-Si precipitates, and extrusion profiles. This study provides a basis for improving the surface quality in industrial extrusion products by optimizing various process parameters.

  10. Graphene nanoribbons: Relevance of etching process

    Energy Technology Data Exchange (ETDEWEB)

    Simonet, P., E-mail: psimonet@phys.ethz.ch; Bischoff, D.; Moser, A.; Ihn, T.; Ensslin, K. [Solid State Physics Laboratory, ETH Zurich, Zurich 8093 (Switzerland)

    2015-05-14

    Most graphene nanoribbons in the experimental literature are patterned using plasma etching. Various etching processes induce different types of defects and do not necessarily result in the same electronic and structural ribbon properties. This study focuses on two frequently used etching techniques, namely, O{sub 2} plasma ashing and O{sub 2 }+ Ar reactive ion etching (RIE). O{sub 2} plasma ashing represents an alternative to RIE physical etching for sensitive substrates, as it is a more gentle chemical process. We find that plasma ashing creates defective graphene in the exposed trenches, resulting in instabilities in the ribbon transport. These are probably caused by more or larger localized states at the edges of the ashed device compared to the RIE defined device.

  11. In Vitro Acid-Mediated Initial Dental Enamel Loss Is Associated with Genetic Variants Previously Linked to Caries Experience

    Science.gov (United States)

    Vieira, Alexandre R.; Bayram, Merve; Seymen, Figen; Sencak, Regina C.; Lippert, Frank; Modesto, Adriana

    2017-01-01

    We have previously shown that AQP5 and BTF3 genetic variation and expression in whole saliva are associated with caries experience suggesting that these genes may have a functional role in protecting against caries. To further explore these results, we tested ex vivo if variants in these genes are associated with subclinical dental enamel mineral loss. DNA and enamel samples were obtained from 53 individuals. Enamel samples were analyzed for Knoop hardness of sound enamel, integrated mineral loss after subclinical carious lesion creation, and change in integrated mineral loss after remineralization. DNA samples were genotyped for single nucleotide polymorphisms using TaqMan chemistry. Chi-square and Fisher's exact tests were used to compare individuals above and below the mean sound enamel microhardness of the cohort with alpha of 0.05. The A allele of BTF3 rs6862039 appears to be associated with harder enamel at baseline (p = 0.09), enamel more resistant to demineralization (p = 0.01), and enamel that more efficiently regain mineral and remineralize (p = 0.04). Similarly, the G allele of AQP5 marker rs3759129 and A allele of AQP5 marker rs296763 are associated with enamel more resistant to demineralization (p = 0.03 and 0.05, respectively). AQP5 and BTF3 genetic variations influence the initial subclinical stages of caries lesion formation in the subsurface of enamel. PMID:28275354

  12. Selective enamel etching: effect on marginal adaptation of self-etch LED-cured bond systems in aged Class I composite restorations.

    Science.gov (United States)

    Souza-Junior, E J; Prieto, L T; Araújo, C T P; Paulillo, L A M S

    2012-01-01

    The aim of this study was to evaluate the influence of previous enamel etch and light emitting diode (LED) curing on gap formation of self-etch adhesive systems in Class I composite restorations after thermomechanical aging (TMA). Thus, on 192 human molars, a box-shaped Class I cavity was prepared maintaining enamel margins. Self-etch adhesives (Clearfil SE and Clearfil S3) were used to restore the preparation with a microhybrid composite. Before application of the adhesives, half of the teeth were enamel etched for 15 seconds with 37% phosphoric acid; the other half were not etched. For the photoactivation of the adhesives and composite, three light-curing units (LCUs) were used: one polywave (Ultra-Lume LED 5, UL) and two single-peak (FlashLite 1401, FL and Radii-cal, RD) LEDs. After this, epoxy resin replicas of the occlusal surface were made, and the specimens were submitted to TMA. New replicas were made from the aged specimens for marginal adaptation analysis by scanning electron microscopy. Data were submitted to Kruskal-Wallis and Wilcoxon tests (α=0.05). Before TMA, when enamel was etched before the application of S3, no gap formation was observed; however, there were gaps at the interface for the other tested conditions, with a statistical difference (p≤0.05). After TMA, the selective enamel etching previous to the S3 application, regardless of the LCU, promoted higher marginal adaptation compared to the other tested groups (p≤0.05). Prior to TMA, higher marginal integrity was observed, in comparison with specimens after TMA (p≤0.05). With regard to Clearfil SE and Clearfil Tri-S cured with FL, no differences of gap formation were found between before and after aging (5.3 ± 3.8 and 7.4 ± 7.5, respectively), especially when the Clearfil Tri-S was used in the conventional protocol. When cured with RD or UL and not etched, Clearfil Tri-S presented the higher gap formation. In conclusion, additional enamel etching promoted better marginal integrity

  13. Surface passivation of silicon nanowires based metal nano-particle assisted chemical etching for photovoltaic applications

    Science.gov (United States)

    Ben Rabha, Mohamed; Khezami, Lotfi; Jemai, Abdelbasset Bessadok; Alhathlool, Raed; Ajbar, Abdelhamid

    2017-03-01

    Metal Nano-particle Assisted Chemical Etching (MNpACE) is an extraordinary developed wet etching method for producing uniform semiconductor nanostructure (silicon nanowires) from patterned metallic film on crystalline silicon surface. The metal films facilitate the etching in HF and H2O2 solution and produce silicon nanowires (SiNWs).The creation of different SiNWs morphologies by changing the etching time and its effects on optical and optoelectronic properties was investigated. The combination effect of formed SiNWs and stain etching treatment in acid (HF/HNO3/H2O) solution on the surface morphology of Si wafers as well as on the optical and optoelectronic properties especially a PL response at 640 nm are presented. As a results, the effective lifetime (τeff) and surface recombination velocity (Seff) evolution of SiNWs after stain etching treatment showed significant improvements and less than 1% reflectance was achieved over the wavelength range of 400-800 nm and more than 36% reduction was observed compared to untreated surface. It has, thus, been demonstrated that all these factors may lead to improved energy efficiency from 8% to nearly 14.2% for a cell with SiNWs treated in acid (HF/HNO3/H2O) solution.

  14. Wet etching of InSb surfaces in aqueous solutions: Controlled oxide formation

    Energy Technology Data Exchange (ETDEWEB)

    Aureau, D., E-mail: damien.aureau@chimie.uvsq.fr [Institut Lavoisier UVSQ-CNRS UMR 8180, 45 avenue des Etats Unis, Versailles, 78035 (France); Chaghi, R.; Gerard, I. [Institut Lavoisier UVSQ-CNRS UMR 8180, 45 avenue des Etats Unis, Versailles, 78035 (France); Sik, H.; Fleury, J. [Sagem Defense Sécurité, 72-74, rue de la tour Billy, 95101, Argenteuil Cedex (France); Etcheberry, A. [Institut Lavoisier UVSQ-CNRS UMR 8180, 45 avenue des Etats Unis, Versailles, 78035 (France)

    2013-07-01

    This paper investigates the wet etching of InSb surfaces by two different oxidant agents: Br{sub 2} and H{sub 2}O{sub 2} and the consecutive oxides generation onto the surfaces. The strong dependence between the chemical composition of the etching baths and the nature of the final surface chemistry of this low band-gap III–V semiconductor will be especially highlighted. One aqueous etching solution combined hydrobromic acid and Bromine (HBr–Br{sub 2}:H{sub 2}O) with adjusted concentrations. The other solution combines orthophosphoric and citric acids with hydrogen peroxide (H{sub 3}PO{sub 4}–H{sub 2}O{sub 2}:H{sub 2}O). Depending on its composition, each formulation gave rise to variable etching rate. The dosage of Indium traces in the etching solution by atomic absorption spectroscopy (AAS) gives the kinetic variation of the dissolution process. The variations on etching rates are associated to the properties and the nature of the formed oxides on InSb surfaces. Surface characterization is specifically performed by X-ray photoelectron spectroscopy (XPS). A clear evidence of the differences between the formed oxides is highlighted. Atomic force microscopy is used to monitor the surface morphology and pointed out that very different final morphologies can be reached. This paper presents new results on the strong variability of the InSb oxides in relation with the InSb reactivity toward environment interaction.

  15. Effect of wet etching process on the morphology and transmittance of fluorine doped tin oxide (FTO)

    Science.gov (United States)

    Triana, S. L.; Kusumandari; Suryana, R.

    2016-11-01

    Wet etching process was performed on the surface of FTO. The FTO coated glasses subtrates with size of 2×2 cm covered by screen were patterned using zinc powder and concentrated hydrochloric acid (1 M). The substrates were then cleaned in ultrasonic baths of special detergent(helmanex) diluted in deionized water and isopropanol in sequence. The screens with various of hole size denotes by T32, T49 and T55 were used in order to create a pattern of surface textured. The atomic force microscopy (AFM) image revealed that wet etching process changes the morphology of FTO. It indicates that texturization occured. Moreover, from the UV-Vis Spectrophotometer measurement, the transmittance of FTO increase after wet etching process. The time of etching and pattern of screen were affect to the morphology and the transmittance of FTO.

  16. Optimal conditions for the preparation of superhydrophobic surfaces on al substrates using a simple etching approach

    Science.gov (United States)

    Ruan, Min; Li, Wen; Wang, Baoshan; Luo, Qiang; Ma, Fumin; Yu, Zhanlong

    2012-07-01

    Many methods have been proposed to develop the fabrication techniques for superhydrophobic surfaces. However, such techniques are still at their infant stage and suffer many shortcomings. In this paper, the superhydrophobic surfaces on an Al substrate were prepared by a simple etching method. Effects of etching time, modifiers, and modification concentration and time were investigated, and optimal conditions for the best superhydrophobicity were studied. It was demonstrated that for etching the aluminum plate in Beck's dislocation, if the etching time was 15 s, modifier was Lauric acid-ethanol solution, and modification concentration and time was 5% and 1.5 h, respectively, the surface exhibited a water contact angle as high as 167.5° and a contact angle hysteresis as low as 2.3°.

  17. Wet Etching of Heat Treated Atomic Layer Chemical Vapor Deposited Zirconium Oxide in HF Based Solutions

    Science.gov (United States)

    Balasubramanian, Sriram; Raghavan, Srini

    2008-06-01

    Alternative materials are being considered to replace silicon dioxide as gate dielectric material. Of these, the oxides of hafnium and zirconium show the most promise. However, integrating these new high-k materials into the existing complementary metal-oxide-semiconductor (CMOS) process remains a challenge. One particular area of concern is the wet etching of heat treated high-k dielectrics. In this paper, work done on the wet etching of heat treated atomic layer chemical vapor deposited (ALCVD) zirconium oxide in HF based solutions is presented. It was found that heat treated material, while refractory to wet etching at room temperature, is more amenable to etching at higher temperatures when methane sulfonic acid is added to dilute HF solutions. Selectivity over SiO2 is still a concern.

  18. Silver ion mediated shape control of platinum nanoparticles: Removal of silver by selective etching leads to increased catalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Grass, Michael E.; Yue, Yao; Habas, Susan E.; Rioux, Robert M.; Teall, Chelsea I.; Somorjai, G.A.

    2008-01-09

    A procedure has been developed for the selective etching of Ag from Pt nanoparticles of well-defined shape, resulting in the formation of elementally-pure Pt cubes, cuboctahedra, or octahedra, with a largest vertex-to-vertex distance of {approx}9.5 nm from Ag-modified Pt nanoparticles. A nitric acid etching process was applied Pt nanoparticles supported on mesoporous silica, as well as nanoparticles dispersed in aqueous solution. The characterization of the silica-supported particles by XRD, TEM, and N{sub 2} adsorption measurements demonstrated that the structure of the nanoparticles and the mesoporous support remained conserved during etching in concentrated nitric acid. Both elemental analysis and ethylene hydrogenation indicated etching of Ag is only effective when [HNO{sub 3}] {ge} 7 M; below this concentration, the removal of Ag is only {approx}10%. Ethylene hydrogenation activity increased by four orders of magnitude after the etching of Pt octahedra that contained the highest fraction of silver. High-resolution transmission electron microscopy of the unsupported particles after etching demonstrated that etching does not alter the surface structure of the Pt nanoparticles. High [HNO{sub 3}] led to the decomposition of the capping agent, polyvinylpyrollidone (PVP); infrared spectroscopy confirmed that many decomposition products were present on the surface during etching, including carbon monoxide.

  19. Dental Calculus Arrest of Dental Caries

    Science.gov (United States)

    Keyes, Paul H.; Rams, Thomas E.

    2016-01-01

    Background An inverse relationship between dental calculus mineralization and dental caries demineralization on teeth has been noted in some studies. Dental calculus may even form superficial layers over existing dental caries and arrest their progression, but this phenomenon has been only rarely documented and infrequently considered in the field of Cariology. To further assess the occurrence of dental calculus arrest of dental caries, this study evaluated a large number of extracted human teeth for the presence and location of dental caries, dental calculus, and dental plaque biofilms. Materials and methods A total of 1,200 teeth were preserved in 10% buffered formal saline, and viewed while moist by a single experienced examiner using a research stereomicroscope at 15-25× magnification. Representative teeth were sectioned and photographed, and their dental plaque biofilms subjected to gram-stain examination with light microscopy at 100× magnification. Results Dental calculus was observed on 1,140 (95%) of the extracted human teeth, and no dental carious lesions were found underlying dental calculus-covered surfaces on 1,139 of these teeth. However, dental calculus arrest of dental caries was found on one (0.54%) of 187 evaluated teeth that presented with unrestored proximal enamel caries. On the distal surface of a maxillary premolar tooth, dental calculus mineralization filled the outer surface cavitation of an incipient dental caries lesion. The dental calculus-covered carious lesion extended only slightly into enamel, and exhibited a brown pigmentation characteristic of inactive or arrested dental caries. In contrast, the tooth's mesial surface, without a superficial layer of dental calculus, had a large carious lesion going through enamel and deep into dentin. Conclusions These observations further document the potential protective effects of dental calculus mineralization against dental caries. PMID:27446993

  20. 氢氟酸处理时间对可切削玻璃陶瓷粘接后断裂强度的影响%The influence of hydrofluoric acid etching time on fracture strength of cemented machinable glass ceramic

    Institute of Scientific and Technical Information of China (English)

    黄宏; 张鹏; 黎日照

    2015-01-01

    目的:研究氢氟酸凝胶处理时间对可切削玻璃陶瓷粘接后断裂强度的影响。方法收集人离体磨牙50颗,垂直牙长轴磨除牙合面釉质;将CEREC Blocs可切削玻璃陶瓷瓷块加工成片状试件后,随机分成5组,每组10片,用质量分数9.5%的氢氟酸凝胶进行处理,处理时间分别为30 s( B组)、60 s( C组)、120 s( D组)、240 s ( E组),A组为对照组,不用氢氟酸凝胶处理;用Variolink® N粘接系统将处理后的瓷片与离体牙进行粘接,万能试验机上测试瓷片的断裂载荷,对数据进行单因素方差分析和LSD检验。结果 A组、B组、C组、D组、E组试件断裂载荷值分别为(1774±153) N、(2190±180) N、(2336±173) N、(2097±174) N、(2075±202) N。5组试件断裂载荷均数间的差异有统计学意义(F=13.5,P<0.001)。 LSD检验结果显示A组断裂载荷值均小于其余各组,差异均有统计学意义(P<0.05);C组载荷值大于D、E组,差异有统计学意义(P<0.05)。结论氢氟酸处理可提高试件粘接后的断裂强度,处理时间超过120 s后断裂强度下降,但仍高于不作氢氟酸处理组。%Objective To evaluate the fracture strength of cemented machinable glass ceramic after being etched with hydrofluoric acid for different time periods and provide guides for clinical hydrofluoric etching. Methods 50 human mo-lars were collected, and occlusal enamel was removed. Sirona CEREC Blocs were processed into plate-shape, divided in-to 5 groups and etched with hydrofluoric acid for 30 s ( Group B) , 60 s ( Group C) , 120 s ( Group D) and 240 s ( Group E) respectively, while Group A remained untreated. Then all specimens were cemented onto the collected molars with Variolink® N cement system. Fracture loads were measured with a universal testing machine. The results were analyzed by one-way ANOVA and LSD test. Results Fracture loads of Group A to E were ( 1 774 ± 153) N, ( 2 190 ± 180) N, ( 2 336 ± 173) N, ( 2 097 ± 174) N, ( 2

  1. An In Vitro Evaluation of Leakage of Two Etch and Rinse and Two Self-Etch Adhesives after Thermocycling

    Directory of Open Access Journals (Sweden)

    Sabine Geerts

    2012-01-01

    interfaces. In our experiment Etch and Rinse adhesives remain better than Self-Etch adhesives at enamel interface. In addition, there was no statistical difference between 1-step (ADSE-1 and 2-step (ADSE Self-Etch adhesives.

  2. Effect of hydrofluoric acid etching time on the topography and surface roughness of lithium disilicate glass ceramic%氢氟酸处理对二硅酸锂玻璃陶瓷表面形貌及粗糙度的影响

    Institute of Scientific and Technical Information of China (English)

    任冬锋; 骆小平

    2013-01-01

    目的 探讨氢氟酸处理时间对二硅酸锂玻璃陶瓷表面形貌及粗糙度的影响,拟为与之相关的玻璃陶瓷机械强度和树脂粘接强度做出初步解释.方法 采用失蜡铸造法制作直径10 mm、厚1 mm的玻璃陶瓷片状试件15个,打磨抛光之后随机分为5组,每组3个.陶瓷表面分别接受9.5%的氢氟酸凝胶酸蚀处理0、20、40、60和120 s.使用原子力显微镜(AFM)测量表面粗糙度参数和酸蚀深度,观测其表面三维形貌,并结合使用场发射扫描电子显微镜(FE-SEM)对陶瓷表面微观结构进行观察分析.结果 FE-SEM观察显示,陶瓷表面的玻璃基质首先被氢氟酸侵蚀溶解,随着酸蚀时间的延长,玻璃基质进一步被侵蚀,部分晶体结构也从陶瓷表面脱落、消失.AFM测量酸蚀表面得出,对照组、20、40、60和120 s氢氟酸处理组陶瓷片表面粗糙度Ra[分别为(17.2±1.6)、(241.8±23.6)、(290.6±38.2)、(322.6±19.6)和(371.3 ± 43.0) nm]随氢氟酸酸蚀时间的延长而显著增加(P<0.05),且与酸蚀时间成正相关.结论 氢氟酸处理可显著增加二硅酸锂陶瓷表面粗糙度.结合使用FE-SEM和AFM能够更好地对玻璃陶瓷的酸蚀表面微观形貌结构进行分析评价.%Objective To analyze the effect of hydrofluoric acid (HFA) etching time on the surface roughness and the topography of lithium disilicate glass ceramic.Methods Fifteen glass ceramic disks (10 mm in diameter and 1 mm in thickness) were made from IPS e.max(R) Press ingots by lost-wax,hot-pressed ceramic fabrication technology,and then divided randomly into five groups (three per group) after polishing.The ceramic surfaces of different groups were etched by 9.5% hydrofluoric acid gel for 0,20,40,60,and 120 s,respectively.Atomic force microscope (AFM) was used to evaluate the surface roughness and the 3D topography.Microstructure was also analyzed by the field emission scanning electron microscope (FE-SEM).Results The result showed

  3. Association between dental-oral health in young adults and salivary glutathione, lipid peroxidation and sialic acid levels and carbonic anhydrase activity

    Directory of Open Access Journals (Sweden)

    L.K. Öztürk

    2008-11-01

    Full Text Available The aim of the present study was to evaluate the relationship between salivary oxidative stress and dental-oral health. Healthy young adults, matched for gender and age, with (N = 21, 10 men, mean age: 20.3 ± 1 years and without (N = 16, 8 men, mean age: 21.2 ± 1.8 years caries were included in this study. The World Health Organization (WHO caries diagnostic criteria were used for determining the decayed, missing, filled teeth (DMFT index. The oral hygiene and gingival status were assessed using the simplified oral hygiene index and gingival index, respectively. Unstimulated salivary total protein, glutathione (GSH, lipid peroxidation and total sialic acid levels, carbonic anhydrase activity, and salivary buffering capacity were determined by standard methods. Furthermore, salivary pH was measured with pH paper and salivary flow rate was calculated. Simplified oral hygiene index and gingival index were not significantly different between groups but DMFT scores were significant (P < 0.01. Only, GSH values were significantly different (P < 0.05 between groups (2.2 and 1.6 mg/g protein in young adults without caries and with caries, respectively. There was a significant negative correlation between DMFT and GSH (r = -0.391; P < 0.05; Pearson's correlation coefficient. Our results suggest that there is an association between caries history and salivary GSH levels.

  4. Isolate-specific effects of patulin, penicillic Acid and EDTA on biofilm formation and growth of dental unit water line biofilm isolates.

    Science.gov (United States)

    Liaqat, Iram; Bachmann, Robert Thomas; Sabri, Anjum Nasim; Edyvean, Robert G J

    2010-08-01

    Dental unit water line (DUWL) contamination by opportunistic pathogens has its significance in nosocomial infection of patients, health care workers, and life-threatening infections to immunocompromized persons. Recently, the quorum sensing (QS) system of DUWL isolates has been found to affect their biofilm-forming ability, making it an attractive target for antimicrobial therapy. In this study, the effect of two quorum-sensing inhibitory compounds (patulin; PAT, penicillic acid; PA) and EDTA on planktonic growth, AI-2 signalling and in vitro biofilm formation of Pseudomonas aeruginosa, Achromobacter xylosoxidans and Achromobacter sp. was monitored. Vibrio harveyi BB170 bioassay and crystal violet staining methods were used to detect the AI-2 monitoring and biofilm formation in DUWL isolates, respectively. The V. harveyi BB170 bioassay failed to induce bioluminescence in A. xylosoxidans and Achromobacter sp., while P. aeruginosa showed AI-2 like activity suggesting the need of some pretreatments prior to bioassay. All strains were found to form biofilms within 72 h of incubation. The QSIs/EDTA combination have isolate-specific effects on biofilm formation and in some cases it stimulated biofilm formation as often as it was inhibited. However, detailed information about the anti-biofilm effect of these compounds is still lacking.

  5. Electroless epitaxial etching for semiconductor applications

    Science.gov (United States)

    McCarthy, Anthony M.

    2002-01-01

    A method for fabricating thin-film single-crystal silicon on insulator substrates using electroless etching for achieving efficient etch stopping on epitaxial silicon substrates. Microelectric circuits and devices are prepared on epitaxial silicon wafers in a standard fabrication facility. The wafers are bonded to a holding substrate. The silicon bulk is removed using electroless etching leaving the circuit contained within the epitaxial layer remaining on the holding substrate. A photolithographic operation is then performed to define streets and wire bond pad areas for electrical access to the circuit.

  6. Effect of surface etching on condensing heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Seok, Sung Chul; Park, Jae Won; Jung, Jiyeon; Choi, Chonggun; Choi, Gyu Hong; Hwang, Seung Sik; Chung, Tae Yong; Shin, Donghoon [Kookmin University, Seoul (Korea, Republic of); Kim, Jin Jun [Hoseo University, Asan (Korea, Republic of)

    2016-02-15

    This study conducted experiments on humid air condensation during heat transfer in an air preheating exchanger attached to a home condensing boiler to improve thermal efficiency. An etchant composed of sulfuric acid and sodium nitrate was used to create roughness on the heat exchanger surface made from STS430J1L. A counter flow heat exchanger was fabricated to test the performance of heat transfer. Results showed that the overall heat transfer coefficients of all specimens treated with etchant improved with respect to the original specimens (not treated with etchant), and the overall heat transfer coefficient of the 60 s etching specimen increased by up to 15%. However, the increasing rate of the heat transfer coefficient was disproportional to the etching time. When the etching time specifically increased above 60 s, the heat transfer coefficient decreased. This effect was assumed to be caused by surface characteristics such as contact angle. Furthermore, a smaller contact angle or higher hydrophilicity leads to higher heat transfer coefficient.

  7. Dental Training Films.

    Science.gov (United States)

    Veterans Administration Medical Center, Washington, DC.

    This dental training films catalog is organized into two sections. Section I is a category listing of the films by number and title, indexed according to generalized headings; categories are as follow: anatomy, articulator systems, complete dentures, dental assisting, dental laboratory technology, dental materials, dental office emergencies,…

  8. CHANGES IN VALUES MEASURED WITH DIAGNOdent FOR ENAMEL AND DENTIN OF DECIDUOUS TEETH ETCHED FOR DIFFERENT TIME INTERVALS.

    Directory of Open Access Journals (Sweden)

    Vladimir E. Panov

    2014-09-01

    Full Text Available Introduction: Dental caries continues to affect a large percentage of children and currently advises that if diagnosed at an early stage can be reversed with minimally invasive treatments. There a large number of methods for early diagnostics. Purpose: The aim of the presented in vitro study was to evaluate the effectiveness of the laser fluorescent device DIAGNOdent pen in measuring changes in the level of mineralization of intact deciduous teeth enamel surfaces etched for different intervals and of intact dentin etched for 30 seconds. Material and methods: The study was performed on extracted children teeth. DIAGNOdent was used to measure the values of laser fluorescence of intact enamel and dentinal surfaces. Samples were treated with 37% H2PO3 etched for 5 sec., 30 sec. and 60 sec. for enamel surfaces and 30 sec. for dentinal. Teeth were rinsed, dried and measured again with DIAGNOdent. Results: After etching the enamel surfaces for 5 sec., 30 sec. and 60 sec. an average increase of 1.55 (0.85-2.2 was detected. The detected average values of increase of laser fluorescence for the enamel were 0.85 for 5 sec. ethching; 1.6 for 30 sec. and 2.2 for 60 sec. The average increase in the dentine was 3.5. Conclusions: Based on the limitations of the conducted study it may be concluded that the changes in the degree of mineralization of deciduous tooth structures can be detected by DIAGNOdent. Enamel etching for 5 sec., 30 sec. and 60 sec. lead to a comparative degree of change in the laser fluorescence. The obtained values after 30 sec. of etching revealed almost a double increase compared to 5 sec. etching and 3-fold for those at the 60 sec. The measured changes after etching in the dentin were better expressed than those in the enamel.

  9. Freeze fracture and freeze etching.

    Science.gov (United States)

    Chandler, Douglas E; Sharp, William P

    2014-01-01

    Freeze fracture depends on the property of frozen tissues or cells, when cracked open, to split along the hydrophobic interior of membranes, thus revealing broad panoramas of membrane interior. These large panoramas reveal the three-dimensional contours of membranes making the methods well suited to studying changes in membrane architecture. Freshly split membrane faces are visualized by platinum or tungsten shadowing and carbon backing to form a replica that is then cleaned of tissue and imaged by TEM. Etching, i.e., removal of ice from the frozen fractured specimen by sublimation prior to shadowing, can also reveal the true surfaces of the membrane as well as the extracellular matrix and cytoskeletal networks that contact the membranes. Since the resolution of detail in the metal replicas formed is 1-2 nm, these methods can also be used to visualize macromolecules or macromolecular assemblies either in situ or displayed on a mica surface. These methods are available for either specimens that have been chemically fixed or specimens that have been rapidly frozen without chemical intervention.

  10. Effects of etching and adhesive applications on the bond strength between composite resin and glass-ionomer cements

    Directory of Open Access Journals (Sweden)

    Tijen Pamir

    2012-12-01

    Full Text Available OBJECTIVE: This study determined the effects of various surface treatment modalities on the bond strength of composite resins to glass-ionomer cements. MATERIAL AND METHODS: Conventional (KetacTM Molar Quick ApplicapTM or resin-modified (PhotacTM Fil Quick AplicapTM glass-ionomer cements were prepared. Two-step etch-rinse & bond adhesive (AdperTM Single Bond 2 or single-step self-etching adhesive (AdperTM PromptTM L-PopTM was applied to the set cements. In the etch-rinse & bond group, the sample surfaces were pre-treated as follows: (1 no etching, (2 15 s of etching with 35% phosphoric acid, (3 30 s of etching, and (4 60 s of etching. Following the placement of the composite resin (FiltekTM Z250, the bond strength was measured in a universal testing machine and the data obtained were analyzed with the two-way analysis of variance (ANOVA followed by the Tukey's HSD post hoc analysis (p=0.05. Then, the fractured surfaces were examined by scanning electron microscopy. RESULTS: The bond strength of the composite resin to the conventional glass-ionomer cement was significantly lower than that to the resin-modified glass-ionomer cement (p0.05. However, a greater bond strength was obtained with 30 s of phosphoric acid application. CONCLUSIONS: The resin-modified glass-ionomer cement improved the bond strength of the composite resin to the glass-ionomer cement. Both etch-rinse & bond and self-etching adhesives may be used effectively in the lamination of glass-ionomer cements. However, an etching time of at least 30 s appears to be optimal.

  11. Semiconductor structure and recess formation etch technique

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Bin; Sun, Min; Palacios, Tomas Apostol

    2017-02-14

    A semiconductor structure has a first layer that includes a first semiconductor material and a second layer that includes a second semiconductor material. The first semiconductor material is selectively etchable over the second semiconductor material using a first etching process. The first layer is disposed over the second layer. A recess is disposed at least in the first layer. Also described is a method of forming a semiconductor structure that includes a recess. The method includes etching a region in a first layer using a first etching process. The first layer includes a first semiconductor material. The first etching process stops at a second layer beneath the first layer. The second layer includes a second semiconductor material.

  12. Influence of the LED curing source and selective enamel etching on dentin bond strength of self-etch adhesives in class I composite restorations.

    Science.gov (United States)

    Souza-Junior, Eduardo José; Araújo, Cíntia Tereza Pimenta; Prieto, Lúcia Trazzi; Paulillo, Luís Alexandre Maffei Sartini

    2012-11-01

    The aim of this study was to evaluate the influence of the LED curing unit and selective enamel etching on dentin microtensile bond strength (μTBS) for self-etch adhesives in class I composite restorations. On 96 human molars, box-shaped class I cavities were made maintaining enamel margins. Self-etch adhesives (Clearfil SE - CSE and Clearfil S(3) - S3) were used to bond a microhybrid composite. Before adhesive application, half of the teeth were enamel acid-etched and the other half was not. Adhesives and composites were cured with the following light curing units (LCUs): one polywave (UltraLume 5 - UL) and two single-peak (FlashLite 1401 - FL and Radii Cal - RD) LEDs. The specimens were then submitted to thermomechanical aging and longitudinally sectioned to obtain bonded sticks (0.9 mm(2)) to be tested in tension at 0.5 mm/min. The failure mode was then recorded. The μTBS data were submitted to a three-way ANOVA and Tukey's (α = 0.05). For S3, the selective enamel-etching provided lower μTBS values (20.7 ± 2.7) compared to the non-etched specimens (26.7 ± 2.2). UL yielded higher μTBS values (24.1 ± 3.2) in comparison to the photoactivation approach with FL (18.8 ±3.9) and RD (19.9 ±1.8) for CSE. The two-step CSE was not influenced by the enamel etching (p ≥ 0.05). Enamel acid etching in class I composite restorations affects the dentin μTBS of the one-step self-etch adhesive Clearfil S(3), with no alterations for Clearfil SE bond strength. The polywave LED promoted better bond strength for the two-step adhesive compared to the single-peak ones.

  13. Investigation of defects and surface polarity in GaN using hot wet etching together with microscopy and diffraction techniques

    Energy Technology Data Exchange (ETDEWEB)

    Visconti, P.; Huang, D.; Reshchikov, M.A.; Yun, F.; Cingolani, R.; Smith, D.J.; Jasinski, J.; Swider, W.; Liliental-Weber, Z.; Morkoc, H.

    2002-04-08

    The availability of reliable and quick methods to determine defect density and polarity in GaN films is of great interest. We have used photo-electrochemical (PEC) and hot wet etching using H{sub 3}PO{sub 4} and molten KOH to estimate the defect density in GaN films grown by hydride vapor phase epitaxy (HVPE) and molecular beam epitaxy (MBE). Free-standing whiskers and hexagonal etch pits are formed by PEC and wet etching respectively. Using Atomic Force Microscopy (AFM), we found the whisker density to be similar to etch pit densities for samples etched under precise conditions. Additionally Transmission Electron Microscopy (TEM) observations confirmed dislocation densities obtained by etching which increased our confidence in the consistency of methods used. Hot wet etching was used also to investigate the polarity of GaN films together with Convergent Beam Electron Diffraction (CBED) and AFM imaging. We found that hot H{sub 3}PO{sub 4} etches N-polarity GaN films very quickly resulting in the complete removal or drastic change of surface morphology as revealed by AFM or optical microscopy. On the contrary, the acid attacks only defect sites in Ga-polarity films producing nanometer-scale pits but leaving the defect-free GaN intact and the morphology unchanged. Additionally, the polarity assignments were related to the as-grown morphology and to the growth conditions of the buffer layer and the subsequent GaN layer.

  14. Plasma/Neutral-Beam Etching Apparatus

    Science.gov (United States)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

    1989-01-01

    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  15. Improved thrombogenicity on oxygen etched Ti6Al4V surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Riedel, Nicholas A. [Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523 (United States); Smith, Barbara S. [School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523 (United States); Williams, John D. [Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523 (United States); Popat, Ketul C., E-mail: ketul.popat@colostate.edu [Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523 (United States); School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523 (United States)

    2012-07-01

    Thrombus formation on blood contacting biomaterials continues to be a key factor in initiating a critical mode of failure in implantable devices, requiring immediate attention. In the interest of evaluating a solution for one of the most widely used biomaterials, titanium and its alloys, this study focuses on the use of a novel surface oxidation treatment to improve the blood compatibility. This study examines the possibility of using oblique angle ion etching to produce a high quality oxide layer that enhances blood compatibility on medical grade titanium alloy Ti6Al4V. An X-ray photoelectron spectroscopy (XPS) analysis of these oxygen-rich surfaces confirmed the presence of TiO{sub 2} peaks and also indicated increased surface oxidation as well as a reduction in surface defects. After 2 h of contact with whole human plasma, the oxygen etched substrates demonstrated a reduction in both platelet adhesion and activation as compared to bare titanium substrates. The whole blood clotting behavior was evaluated for up to 45 min, showing a significant decrease in clot formation on oxygen etched substrates. Finally, a bicinchoninic acid (BCA) total protein assay and XPS were used to evaluate the degree of key blood serum protein (fibrinogen, albumin, immunoglobulin G) adsorption on the substrates. The results showed similar protein levels for both the oxygen etched and control substrates. These results indicate that oblique angle oxygen etching may be a promising method to increase the thrombogenicity of Ti6Al4V. - Highlights: Black-Right-Pointing-Pointer Oblique angle oxygen ion etching creates a high quality, uniform oxide surface. Black-Right-Pointing-Pointer Oxygen etched substrates showed fewer adhered platelets. Black-Right-Pointing-Pointer Platelet activation was reduced by the improved oxide surface. Black-Right-Pointing-Pointer Oxygen etched substrates exhibited increased whole blood clotting times. Black-Right-Pointing-Pointer Although clotting reductions were

  16. RNA of tobacco etch virus contains poly(A)

    Energy Technology Data Exchange (ETDEWEB)

    Hari, V.; Siegel, A.; Rozek, C.; Timberlake, W.E.

    1979-01-30

    The RNA of tobacco etch virus was extracted and found to have a molecular weight of 3.2 x 10/sup 6/ based on an extrapolation from polyacrylamide-gel electrophoresis mobility. The RNA from the virus could be separated into two classes, one containing and one lacking polyadenylate isostichs of sufficient length to bind to polyuridylic-acid-agarose. The two classes were present in variable amounts depending on the batch of virus used for isolation of RNA and both classes were infectious.

  17. Dental Holography

    Science.gov (United States)

    Dirtoft, Ingegerd

    1983-12-01

    Ten years have passed since the first articles appeared in this new field. The qualities of the laser light together with the need of contactless 3-D measurements for different dental purposes seemed to be extremely promising, but still just a few scientists have used the method and mostly for laboratory studies. For some reason there has been a preponderance for orthodontic measurements. This seems to be a bit peculiar from holographic view compared with measurements for engineering purposes, which usually are made on metals. So naturally holography can become a clinical tool for measurements in the field of fixed bridges, removable partial dentures and implants. One of the problems is that the need for holography in dental research must be fulfilled in collaboration with physicists. Only a two-way communication during an entire experiment can balance both technical and odontological demands and thus give practical and clinical important results. The need for an easy way of handling the evaluation to get all required information is another problem and of course the holographic equipment must be converted to a box easy to handle for everyone. At last the position of dental holography today is going to be carefully examined together with an attempt to look into the hopefully exciting and not to utopic future for this research field.

  18. Development of Localized Plasma Etching System for Failure Analyses in Semiconductor Devices: (3)Etching-Monitoring Using Quadrupole Mass Spectrometry

    Science.gov (United States)

    Takahashi, Satoshi; Horie, Tomoyuki; Shirayama, Yuya; Yokosuka, Shuntaro; Kashimura, Kenta; Hayashi, Akihiro; Iwase, Chikatsu; Shimbori, Shun'ichiro; Tokumoto, Hiroshi; Naitoh, Yasuhisa; Shimizu, Tetsuo

    Quadrupole mass spectrometry (QMS) has been applied to monitor the etching processes in a localized plasma etching system. An inward plasma was employed for etching in which the etching gas was discharged in the narrow gap between the etched sample and the entrance of an evacuating capillary tube. As the etching products are immediately evacuated through the capillary, a QMS system equipped at the capillary exit is able to analyze the products without any loss in concentration via diffusion into the chamber. Two kinds of samples, thermally grown SiO2 on Si and spin-coated polyimide film on Si, were etched, and the chemical species in the evacuated etching gas were analyzed with QMS, which enables monitoring of the composition of the surface being etched. Samples of thermal SiO2 were etched with CF4 plasma. The peak height of the SiF3+ signal during the SiO2 etching was lower than that observed during etching of the silicon substrate, leading to endpoint detection. The endpoint detection of the polyimide film etching was conducted using two etching gases: pure O2 and pure CF4. When O2 was used, the endpoint was detected by the decrease of the mass peak attributed to CO. When CF4 was employed, the plasma was able to etch both the polyimide film and Si substrate. Then the endpoint was detected by the increase of the mass peak of SiF3+ produced by the etching of the Si substrate.

  19. Danish dental education:

    DEFF Research Database (Denmark)

    Moore, Rod

    1985-01-01

    The effects of Danish cultural traditions on dental education in Denmark are described, as well as the system's current structure and developing issues. Some Danish ideas for future exports of dental education programs and dental personnel are also discussed.......The effects of Danish cultural traditions on dental education in Denmark are described, as well as the system's current structure and developing issues. Some Danish ideas for future exports of dental education programs and dental personnel are also discussed....

  20. American Dental Hygienists' Association

    Science.gov (United States)

    ... Health Student Resources National Exam Student Advisor Resources Dental Hygiene Programs Scholarships and Grants Research Center Transforming Dental Hygiene Education Advocacy Practice Issues Direct Access Scope of ...

  1. Peculiarities of latent track etching in SiO2/Si structures irradiated with Ar, Kr and Xe ions

    Science.gov (United States)

    Al'zhanova, A.; Dauletbekova, A.; Komarov, F.; Vlasukova, L.; Yuvchenko, V.; Akilbekov, A.; Zdorovets, M.

    2016-05-01

    The process of latent track etching in SiO2/Si structures irradiated with 40Ar (38 MeV), 84Kr (59 MeV) and 132Xe (133 and 200 MeV) ions has been investigated. The experimental results of SiO2 etching in a hydrofluoric acid solution have been compared with the results of computer simulation based on the thermal spike model. It has been confirmed that the formation of a molten region along the swift ion trajectory with minimum radius of 3 nm can serve as a theoretical criterion for the reproducible latent track etching tracks in SiO2.

  2. Functional expression of dental plaque microbiota.

    Science.gov (United States)

    Peterson, Scott N; Meissner, Tobias; Su, Andrew I; Snesrud, Erik; Ong, Ana C; Schork, Nicholas J; Bretz, Walter A

    2014-01-01

    Dental caries remains a significant public health problem and is considered pandemic worldwide. The prediction of dental caries based on profiling of microbial species involved in disease and equally important, the identification of species conferring dental health has proven more difficult than anticipated due to high interpersonal and geographical variability of dental plaque microbiota. We have used RNA-Seq to perform global gene expression analysis of dental plaque microbiota derived from 19 twin pairs that were either concordant (caries-active or caries-free) or discordant for dental caries. The transcription profiling allowed us to define a functional core microbiota consisting of nearly 60 species. Similarities in gene expression patterns allowed a preliminary assessment of the relative contribution of human genetics, environmental factors and caries phenotype on the microbiota's transcriptome. Correlation analysis of transcription allowed the identification of numerous functional networks, suggesting that inter-personal environmental variables may co-select for groups of genera and species. Analysis of functional role categories allowed the identification of dominant functions expressed by dental plaque biofilm communities, that highlight the biochemical priorities of dental plaque microbes to metabolize diverse sugars and cope with the acid and oxidative stress resulting from sugar fermentation. The wealth of data generated by deep sequencing of expressed transcripts enables a greatly expanded perspective concerning the functional expression of dental plaque microbiota.

  3. Functional Expression of Dental Plaque Microbiota

    Directory of Open Access Journals (Sweden)

    Scott Norman Peterson

    2014-08-01

    Full Text Available Dental caries remains a significant public health problem and is considered pandemic worldwide. The prediction of dental caries based on profiling of microbial species involved in disease and equally important, the identification of species conferring dental health has proven more difficult than anticipated due to high interpersonal and geographical variability of dental plaque microbiota. We have used RNA-Seq to perform global gene expression analysis of dental plaque microbiota derived from 19 twin pairs that were either concordant (caries-active or caries-free or discordant for dental caries. The transcription profiling allowed us to define a functional core microbiota consisting of nearly 60 species. Similarities in gene expression patterns allowed a preliminary assessment of the relative contribution of human genetics, environmental factors and caries phenotype on the microbiota’s transcriptome. Correlation analysis of transcription allowed the identification of numerous functional networks, suggesting that inter-personal environmental variables may co-select for groups of genera and species. Analysis of functional role categories allowed the identification of dominant functions expressed by dental plaque biofilm communities, that highlight the biochemical priorities of dental plaque microbes to metabolize diverse sugars and cope with the acid and oxidative stress resulting from sugar fermentation. The wealth of data generated by deep sequencing of expressed transcripts enables a greatly expanded perspective concerning the functional expression of dental plaque microbiota.

  4. Polymerization monitoring in plasma etching systems

    Science.gov (United States)

    Kim, Jinsoo

    1999-11-01

    In plasma etching processes, the polymers used to enhance etch anisotropy and selectivity also deposit on various parts of the reaction chamber. This polymerization on reactor surface not only strongly affects the concentration of reactants in the plasma discharge, eventually changing the etching characteristics, but also can produce particulates which lower yield. This thesis explores the development of a direct in-situ polymerization monitoring sensor to minimize the drifts in plasma etching processes. In addition, polymerization dependencies on basic processing parameters and polymerization effects on etching characteristics have been explored for the first time using a direct in-situ sensor. The polymer buildup process is a strong function of parameters such as power, base pressure, and flow rate, and is also dependent on the reactor materials used, temperature, and the hydrogen/oxygen concentrations present. Experiments performed in an Applied Materials 8300 plasma etcher show a significant increase in polymerization with increased pressure and flow rates and a decrease as a function of power. These experiments provide insight into how the chamber state changes under the different processing recipes used for etching specific material layers and also suggest how the chamber seasoning process can best be carried out. The reactor surface, which serves as both a source and a sink for reactive gas species, not only strongly affects the concentration of reactants in the plasma discharge, eventually changing the etching characteristics, but also can produce particulates which lower yield. The etch rate and selectivity variations for specific silicon dioxide and silicon nitride etching recipes have been explored as a function of the polymer thickness on the reactor walls. The etch rates of nitride and polysilicon decrease dramatically with polymer thickness up to a thickness of 60nm, while the oxide etch rate remains virtually constant due to the polymerization

  5. Dental students--dental advocates.

    Science.gov (United States)

    Bensch, Brittany

    2010-01-01

    Student advocacy and involvement in the political process is built into the structure of the American Student Dental Association (ASDA), especially in its Legislative Grassroots Network and an internal communication network among students to ensure political awareness. Students are concerned with such issues as a universally accepted, non-patient-based licensure process, mid-level providers, loan availability and tax deductibility, financial support for schools, and service early in one's professional career (giving forward rather than giving back). Through collaboration with the American Dental Education Association and with many state associations, students participate in lobbying, awareness campaigns, and behind the scenes as legislative aids. Although students share the same love for the profession that animates established practitioners, they are perceived by legislators as being different. Students are involved in the legislative process because it represents their future.

  6. Effect of helium ion beam treatment on the etching rate of silicon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Yu.V., E-mail: y.petrov@spbu.ru; Sharov, T.V.; Baraban, A.P.; Vyvenko, O.F.

    2015-04-15

    We investigated the effect of the helium ion implantation on the etching rate of silicon nitride in hydrofluoric acid. 30 keV helium ions were implanted into a 500-nm-thick silicon nitride film on silicon. Ion fluences from 10{sup 15} to 10{sup 17} cm{sup −2} were used. Etching was performed in a hydrofluoric acid solution. All samples were investigated with a scanning electron microscope and atomic force microscope. It was found that helium ion implantation can increase the etching rate by a factor of three. This results in the formation of a well in the implanted area after etching. The maximum depth of the well is about 180 nm and is limited by the penetration depth of 30 keV helium ions. Two possible reasons for enhanced etching are suggested: enhancement by ion-induced defects and electrostatic interaction of ions of the etchant with ion-induced space charge of silicon nitride. The recombination of ion-induced defects is also discussed.

  7. 基于丙烯酸-丙烯酰胺共聚物的氧化铟锡蚀刻油墨的制备与性能%Preparation and Properties of Indium Tin Oxide Etching Ink Based on Acrylic Acid-Acrylamide Copolymer

    Institute of Scientific and Technical Information of China (English)

    钟英立; 杨鑫; 孙金媛; 陈建忠; 刘英菊; 杨卓鸿

    2012-01-01

    The low viscosity poly (acrylic acid-acrylamide) (P (AA-co-AM)) resin was synthesized by solution polymerization using acrylicacid and acrylamide as the monomers. The properties of the resin were characterized by rotational viscometer and thermogravimetric analyser. A new type of indium tin oxide (ITO) etching ink was prepared using P(AA-co-AM) resin as connection material. The water retention property, pH change and etched image resolution of the ink were evaluated. Results showed that the suit- able resin can be prepared by optimizing the synthesis process. The so prepared resin didn't decompose beneath 150 ℃. The water loss rate of the ink was range 3.68% and 5.34%after exposing to air for 3 h. The image resolution used this ink was better than the commercially available ink after storing 60 d. More over, the etching capability did not decline and pH value almost did not change.%以丙烯酸(AA)、丙烯酰胺(AM)为单体,采用水溶液聚合法制备了低黏度聚(丙烯酸-丙烯酰胺)P(AA—Co—AM)树脂。使用旋转黏度计和热重分析仪等测试了树脂的性质,并以该树脂为连接料,制备了新型水性氧化铟锡(ITO)蚀刻油墨。探讨了该油墨的保水性、pH变化和蚀刻图像解析度等。结果表明:通过优化合成工艺可制备分子量适宜的P(AA—CO—AM)树脂,它在150℃以下无分解现象;油墨在使用3h后失水率仅为3.68%-5.34%,存放60d后pH基本无变化,且丝网印刷效果明显好于市售油墨。

  8. DENTAL CARIES- A WIDELY GROWING DISEASE OF TEETH

    OpenAIRE

    2012-01-01

    Dental caries called as tooth decay is basically a disease in which bacterial processes changes carbohydrate to acid. This acid then dematerializes the hard tooth structure. They are produced when demineralization amount exceeds the remineralization amount. Streptococcus mutans and Lactobacillus are the bacteria responsible for the dental caries. This article throws light on the dental caries disease, its sign and symptoms, treatment, prevention and risk factors associated with it. A review o...

  9. An etching mask and a method to produce an etching mask

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention relates to an etching mask comprising silicon containing block copolymers produced by self-assembly techniques onto silicon or graphene substrate. Through the use of the etching mask, nanostructures having long linear features having sub-10 nm width can be produced....

  10. Dry etched SiO2 Mask for HgCdTe Etching Process

    Science.gov (United States)

    Chen, Y. Y.; Ye, Z. H.; Sun, C. H.; Deng, L. G.; Zhang, S.; Xing, W.; Hu, X. N.; Ding, R. J.; He, L.

    2016-09-01

    A highly anisotropic etching process with low etch-induced damage is indispensable for advanced HgCdTe (MCT) infrared focal plane array (IRFPA) detectors. The inductively coupled plasma (ICP) enhanced reactive ion etching technique has been widely adopted in manufacturing HgCdTe IRFPA devices. An accurately patterned mask with sharp edges is decisive to accomplish pattern duplication. It has been reported by our group that the SiO2 mask functions well in etching HgCdTe with high selectivity. However, the wet process in defining the SiO2 mask is limited by ambiguous edges and nonuniform patterns. In this report, we patterned SiO2 with a mature ICP etching technique, prior to which a thin ZnS film was deposited by thermal evaporation. The SiO2 film etching can be terminated at the auto-stopping point of the ZnS layer thanks to the high selectivity of SiO2/ZnS in SF6 based etchant. Consequently, MCT etching was directly performed without any other treatment. This mask showed acceptable profile due to the maturity of the SiO2 etching process. The well-defined SiO2 pattern and the etched smooth surfaces were investigated with scanning electron microscopy and atomic force microscope. This new mask process could transfer the patterns exactly with very small etch-bias. A cavity with aspect-ratio (AR) of 1.2 and root mean square roughness of 1.77 nm was achieved first, slightly higher AR of 1.67 was also get with better mask profile. This masking process ensures good uniformity and surely benefits the delineation of shrinking pixels with its high resolution.

  11. Facet selective etching of Au microcrystallites

    Institute of Scientific and Technical Information of China (English)

    Gangaiah Mettela and Giridhar U. Kulkarni

    2015-01-01

    High-symmetry crystals exhibit isotropic properties. Inducing anisotropy, e.g., by facet selective etching, is considered implausible in face-centered cubic (FCC) metals, particularly gold, which, in addition to being an FCC, is noble. We report for the first time the facet selective etching of Au microcrystals obtained in the form of cuboctahedra and pentagonal rods from the thermolysis of a gold- organic precursor. The selective etching of {111} and {100} facets was achieved using a capping method in which tetraoctylammonium cations selectively cap the {111} facets while Br- ions protect the {100} facets. The exposed facets are oxidized by O2/C1-, yielding a variety of interesting geometries. The facet selective etching of the Au microcrystallites is governed only by the nature of the facets; the geometry of the microcystallite does not appear to play a significant role. The etched surfaces appear rough, but a closer examination reveals well-defined corrugations that are indexable to high hkl values. Such surfaces exhibit enhanced Raman activity.

  12. Photoelectrochemistry and Etching of SiC: a Comparison with Si

    NARCIS (Netherlands)

    Kelly, J.J.; van Dorp, D.H.; Weyher, J.L.

    2007-01-01

    The anodic electrochemistry and etching of the group IV compound semiconductor SiC was studied in both KOH and acidic fluoride solutions. The results for p-type and n-type electrodes are compared with those obtained for the group IV elemental semiconductor Si. We point out a number of interesting ap

  13. Biomechanical and histomorphometric analysis of etched and non-etched resorbable blasting media processed implant surfaces: an experimental study in dogs.

    Science.gov (United States)

    Marin, Charles; Granato, Rodrigo; Suzuki, Marcelo; Janal, Malvin N; Gil, Jose N; Nemcovsky, Carlos; Bonfante, Estevam A; Coelho, Paulo G

    2010-07-01

    This study characterized the interplay between topography/chemistry and early bone response of etched and no-etched resorbable blasted media (RBM) processed surfaces. Screw-root form Ti-6Al-4V implants treated with alumina blasting/acid-etching (AB/AE), RBM alone (RBM), and RBM + acid-etching (RBMa) were evaluated. The surface was characterized by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Implants placed in the tibia of dogs remained 3 and 5 weeks in vivo. Following euthanasia, half of the specimens were torqued to interface failure and the remaining subjected to bone-to-implant contact (BIC) and bone area fraction occupied (BAFO) between threads evaluation. The AB/AE surface was rougher than the RBM and RBMa. Higher levels of calcium and phosphorous were observed for the RBM surface compared to the RBMa. No significant differences were observed in torque, BIC, and BAFO between surfaces. Woven bone formation at 3 weeks and its initial replacement by lamellar bone at 5 weeks were observed around all implants' surfaces.

  14. Sphingoid bases inhibit acid-induced demineralization of hydroxyapatite.

    Science.gov (United States)

    Valentijn-Benz, Marianne; van 't Hof, Wim; Bikker, Floris J; Nazmi, Kamran; Brand, Henk S; Sotres, Javier; Lindh, Liselott; Arnebrant, Thomas; Veerman, Enno C I

    2015-01-01

    Calcium hydroxyapatite (HAp), the main constituent of dental enamel, is inherently susceptible to the etching and dissolving action of acids, resulting in tooth decay such as dental caries and dental erosion. Since the prevalence of erosive wear is gradually increasing, there is urgent need for agents that protect the enamel against erosive attacks. In the present study we studied in vitro the anti-erosive effects of a number of sphingolipids and sphingoid bases, which form the backbone of sphingolipids. Pretreatment of HAp discs with sphingosine, phytosphingosine (PHS), PHS phosphate and sphinganine significantly protected these against acid-induced demineralization by 80 ± 17%, 78 ± 17%, 78 ± 7% and 81 ± 8%, respectively (p measurement revealed that HAp discs treated with PHS were almost completely and homogeneously covered by patches of PHS. This suggests that PHS and other sphingoid bases form layers on the surface of HAp, which act as diffusion barriers against H(+) ions. In principle, these anti-erosive properties make PHS and related sphingosines promising and attractive candidates as ingredients in oral care products.

  15. 柠檬酸对腐蚀铝箔高压阳极氧化膜微观结构与电化学性能的影响%Effect of citric acid on microstructure and electrochemical characteristics of high voltage anodized alumina film formed on etched Al Foils

    Institute of Scientific and Technical Information of China (English)

    班朝磊; 何业东; 邵鑫

    2011-01-01

    将高压铝电解电容器用腐蚀铝箔与沸水反应,然后再在硼酸溶液或硼酸-柠檬酸混合酸溶液中进行530 V高压阳极氧化制得耐压薄膜,应用透射电镜(TEM)、X射线衍射(XRD)研究不同电解液所形成的高压阳极氧化膜的微观结构与结晶程度,利用电化学交流阻抗(EIS)、LCR数字电桥与小电流充电测试阳极氧化膜的电化学性能.结果表明:高压阳极氧化膜具有明显层状结构,内层结晶程度较高、外层结晶程度较低;与单纯硼酸溶液所形成的氧化膜相比,混合酸液所形成的阳极氧化膜的外层结晶程度与晶粒平均尺寸较大,抗电场强度与比电容均比较高,但相变使得氧化膜外层微观缺陷密度增多,氧化膜比电阻与耐电压值有所降低.%Aluminum capacitor foils with a tunnel etch structure were reacted with boiling water and then anodized at 530 V in boric acid solution or boric acid+citric acid mixed solution. The microstructure and crystallinity of the resulting anodized film were examined by TEM and XRD. The special capacitance, resistance and withstanding voltage of the film were explored with electrochemical impedance spectroscopy (EIS), LCR meter and small-current charging. The results show that the high voltage anodized oxide film consists of an inner layer with high crystallinity and an outer layer with low crystallinity. However, the crystallinity of the film formed in boric acid+citric acid mixed solution is higher than that of the film formed in only boric acid solution, leading to an increase in film's field strength and special capacitance. Meanwhile, there are more defects from phase transformation in the out layer of the film formed in boric acid+citric acid mixed solution than in that of film formed in only boric acid solution, leading to a decrease in film's resistance and withstanding voltage.

  16. Child Indicators: Dental Health.

    Science.gov (United States)

    Lewit, Eugene M.; Kerrebrock, Nancy

    1998-01-01

    Reviews measures of dental health in children and the evidence on child dental health. Although children's dental health has improved over the past two decades, many poor children do not receive necessary dental health services, and reasons for this failure are summarized. (SLD)

  17. American Dental Education Association

    Science.gov (United States)

    ... applicant. ... Learn more ADEA DHCAS Applicants The ADEA Dental Hygiene Centralized Application Service (DHCAS®) is the centralized applic... Learn more ADEA DHCAS Program Directors For programs interested in participating... Learn more ... Publications & Data Official Guide to Dental Schools Bulletin of Dental Education Journal of Dental ...

  18. Analytical model of plasma-chemical etching in planar reactor

    Science.gov (United States)

    Veselov, D. S.; Bakun, A. D.; Voronov, Yu A.; Kireev, V. Yu; Vasileva, O. V.

    2016-09-01

    The paper discusses an analytical model of plasma-chemical etching in planar diode- type reactor. Analytical expressions of etch rate and etch anisotropy were obtained. It is shown that etch anisotropy increases with increasing the ion current and ion energy. At the same time, etch selectivity of processed material decreases as compared with the mask. Etch rate decreases with the distance from the centre axis of the reactor. To decrease the loading effect, it is necessary to reduce the wafer temperature and pressure in the reactor, as well as increase the gas flow rate through the reactor.

  19. Single beam determination of porosity and etch rate in situ during etching of porous silicon

    Science.gov (United States)

    Foss, S. E.; Kan, P. Y. Y.; Finstad, T. G.

    2005-06-01

    A laser reflection method has been developed and tested for analyzing the etching of porous silicon (PS) films. It allows in situ measurement and analysis of the time dependency of the etch rate, the thickness, the average porosity, the porosity profile, and the interface roughness. The interaction of an infrared laser beam with a layered system consisting of a PS layer and a substrate during etching results in interferences in the reflected beam which is analyzed by the short-time Fourier transform. This method is used for analysis of samples prepared with etching solutions containing different concentrations of HF and glycerol and at different current densities and temperatures. Variations in the etch rate and porosity during etching are observed, which are important effects to account for when optical elements in PS are made. The method enables feedback control of the etching so that PS films with a well-controlled porosity are obtainable. By using different beam diameters it is possible to probe interface roughness at different length scales. Obtained porosity, thickness, and roughness values are in agreement with values measured with standard methods.

  20. Etching patterns on the micro‐ and nanoscale

    DEFF Research Database (Denmark)

    Michael-Lindhard, Jonas; Herstrøm, Berit; Stöhr, Frederik;

    2014-01-01

    in a liquid reacts with material from the substrate is the ability to fine‐tune the etch process. In wet processing the removal of material generally occurs indiscriminately of direction in the substrate ‐ hence in all directions. This puts a strong limitation on what may be achieved in terms of designs...... and polymer injection molding. High precision patterns of, for instance microfluidic devices, are etched intosilicon which is then electroplated with nickel that will serve as a stamp in the polymer injection molding tool where thousands of devices may be replicated. In addition to silicon and its derived...

  1. Effects of chlorhexidine in self-etching adhesive: 24 hours results.

    Science.gov (United States)

    Nishitani, Yoshihiro; Hosaka, Keiichi; Hoshika, Tomohiro; Yoshiyama, Masahiro; Pashley, David H

    2013-01-01

    It is known that chlorhexidine (CHX) does not inhibit micro-tensile bond strengths (MTBS) when it is used in etch-and-rinse adhesives. In that technique, CHX is applied to dentin as a primer after phosphoric acid-etching before bonding with Single Bond. It would be more convenient if it is possible to incorporate CHX into the adhesive. The purpose of this study was to compare the MTBS and the FT-IR percent conversion of an all-in-one self-etching adhesives contained varying concentration of CHX. Extracted human third molars were bonded with a control all-in-one adhesive or experimental versions containing 0.5, 1, 2 or 5% CHX. The MTBS and the percent conversion of experimental adhesives containing up to 1% CHX were not significantly CHX-free control adhesives. However, addition of 2 or especially 5% CHX experimental adhesives produced significant reductions in both the MTBS and the percent conversion.

  2. Nanometer scale high-aspect-ratio trench etching at controllable angles using ballistic reactive ion etching

    Energy Technology Data Exchange (ETDEWEB)

    Cybart, Shane; Roediger, Peter; Ulin-Avila, Erick; Wu, Stephen; Wong, Travis; Dynes, Robert

    2012-11-30

    We demonstrate a low pressure reactive ion etching process capable of patterning nanometer scale angled sidewalls and three dimensional structures in photoresist. At low pressure the plasma has a large dark space region where the etchant ions have very large highly-directional mean free paths. Mounting the sample entirely within this dark space allows for etching at angles relative to the cathode with minimal undercutting, resulting in high-aspect ratio nanometer scale angled features. By reversing the initial angle and performing a second etch we create three-dimensional mask profiles.

  3. Polymer masks for structured surface and plasma etching

    Energy Technology Data Exchange (ETDEWEB)

    Vital, Alexane [Centre de Recherche sur la Matière Divisée (CRMD), 1b rue de la Férollerie, F45071 Orléans Cedex (France); Groupe de Recherches sur l’Énergétique des Milieux Ionisés (GREMI), Polytech’Orléans, 14 rue d’Issoudun, B.P. 6744, F45067 Orléans Cedex 2 (France); Vayer, Marylène, E-mail: marylene.vayer@univ-orleans.fr [Centre de Recherche sur la Matière Divisée (CRMD), 1b rue de la Férollerie, F45071 Orléans Cedex (France); Sinturel, Christophe [Centre de Recherche sur la Matière Divisée (CRMD), 1b rue de la Férollerie, F45071 Orléans Cedex (France); Tillocher, Thomas; Lefaucheux, Philippe; Dussart, Rémi [Groupe de Recherches sur l’Énergétique des Milieux Ionisés (GREMI), Polytech’Orléans, 14 rue d’Issoudun, B.P. 6744, F45067 Orléans Cedex 2 (France)

    2015-03-30

    Graphical abstract: - Highlights: • Sub-micrometric silicon structures were prepared by cryogenic plasma etching. • Polymer templates based on phase-separated films of PS/PLA were used. • Silica structured masks were prepared by filling the polymer templates. • Etching of underlying silicon through silica templates gave original structures. - Abstract: Silica and silicon structures have been prepared at the sub-micrometer length-scale, using laterally phase-separated thin films of poly(styrene) (PS) and poly(lactic acid) (PLA) homopolymer blends. The selective removal of one polymer and the filling of the released space by silica precursor solution led, after calcination, to silica structures on silicon such as arrays of bowl-shape features or pillars, layers with through or non-through cylindrical holes, which has not been observed for some of them. The control of the morphology of the initial polymer film was a key point to achieve such type of structures. Particularly relevant was the use of solvent vapor annealing (vs thermal annealing) of the initial spin-coated films that favored and stabilized laterally phase-separated morphologies. Characteristic dimension of the domains were shown to be coupled with the thickness of the film, thinner films giving smaller domain sizes. Despite a relatively high incompatibility of the two polymers, a macro-phase separation was prevented in all the studied conditions. Sub-micrometric domains were formed, and for the thinner films, nanometric domains as small as 74 nm in size can be obtained. The silica structures formed by the infiltration of the polymer templates were used as hard masks for the cryogenic etching of underlying silicon. New structured surfaces, arrays of silicon pillars which can be plain or hollow at the upper part or arrays of cylindrical holes were formed. A selectivity as high as 21 was obtained using this type of mask for 1.5 μm deep holes having a typical diameter of 200 nm.

  4. Evaluation of Cu Ion Concentration Effects on Cu Etching Rate in Chemical-Mechanical Polishing Slurry

    Science.gov (United States)

    Nishizawa, Hideaki; Sugiura, Osamu; Matsumura, Yoshiyuki; Kinoshita, Masaharu

    2007-04-01

    The effects of Cu ion concentration of the different solutions on Cu etching rate were investigated. From the dipping experiment of Cu substrates in different solutions of malic acid, hydrogen peroxide (H2O2), benzotriazole (BTA), and Cu ions, it was revealed that Cu etching rate is increased if the concentration of Cu(II) ions added in the solution is high. This is considered to be caused by the effect of Cu(II) ions on H2O2 molecules. In the solution of pH 7, the Cu etching rate increased markedly between 1.7× 10-4 and 3.4× 10-4 M Cu(II) ion concentrations. The maximum increase in the etching rate was from 990 to 2200 nm/min at a H2O2 concentration of 2 wt %. In the solution of pH 3, a marked change in the etching rate was not observed. Our results show that the concentration of Cu ions on the polishing pad in chemical-mechanical polishing (CMP) process is very important.

  5. Effectiveness of an Er:YAG laser in etching the enamel surface for orthodontic bracket retention.

    Science.gov (United States)

    Kim, Jung-Ho; Kwon, Oh-Won; Kim, Hyung-Il; Kwon, Yong Hoon

    2005-12-01

    The purpose of this study was to test the effectiveness of an Er:YAG laser in etching the enamel surface for orthodontic treatment. Bovine incisors were either acid-etched or laser-treated. An orthodontic bracket was attached on each treated surface using one-step dentin adhesive and self-curing resin. Tensile bond strength was then evaluated. In addition, the surface morphology of specimens treated with phosphoric acid/laser and self-etching primer, as well as the cross-section of enamel-primer-resin interfaces, were observed. One-Up Bond F-treated specimens after Er:YAG laser ablation showed statistically similar tensile bond strength (9.9 +/- 1.3 MPa) to that of phosphoric acid-etched specimens (11.8 +/- 1.7 MPa). Surface roughness and thickness of the enamel-primer-resin interfaces did not much affect the tensile bond strength of the tested specimens. In conclusion, Er:YAG laser ablation achieved clinically acceptable level of tensile bond strength when used with One-Up Bond F.

  6. Dental erozyon

    NARCIS (Netherlands)

    Özen, B.; Yönel, N.; Çetiner, S.

    2015-01-01

    Dental erozyon, plak içermeyen diş yüzeyleri üzerinde içsel ve dışsal asitlerin veya şelatların etkileriyle oluşan kimyasal bir aşınmadır. İçsel ve/veya dışsal kaynaklar nedensel faktörler olarak tanımlanırken tükürük ve pelikıl gibi biyolojik faktörler, yeme ve içme alışkanlıkları ve ağız hijyeni g

  7. ANALYSIS OF THE RADIO-OPACITY OF A SELF-ETCH ADHESIVE

    Directory of Open Access Journals (Sweden)

    Mona Ionaş

    2012-12-01

    Full Text Available Introduction. At present, self-etch adhesive systems are employed on large scale in the offices of dental medicine due to their simple application technique. Their radioopacity is important for the identification of this material in paraclinical examinations. Scope. The study describes a technique of radioopacity analysis on a self-etching type adhesive material. Materials and method. Class V cavities have been made on the teeth extracted from orthodontic causes. The dental adhesive was applied on the surface of the cavities, followed by their obturation with a composite material. The teeth were sliced, radiographed, the resulting digital images being analyzed with a specialized software. Results and discussion. The radio-opacity of this adhesive system, lower than that of the enamel, varies, comparatively with that of dentin. Conclusions. Having no filling, the here discussed adhesive system has a relative optical density slightly lower than that of dentin, which makes difficult its radiological identification. Consequently, some problems of differential diagnosis may appear, with the marginal secondary caries or with caries recurrence

  8. A Dental Education Perspective on Dental Health Policy.

    Science.gov (United States)

    Morris, Alvin L.

    1985-01-01

    Two issues related to dental health policy are examined: the contribution of dental education to the process by which dental health policy is established, and the nature of dental education's response to established policies. (MLW)

  9. Review of micromachining of ceramics by etching

    Institute of Scientific and Technical Information of China (English)

    H.T.TING; K.A.ABOU-EL-HOSSEIN; H.B.CHUA

    2009-01-01

    In the last two decades, there has been an enormous surge in interest in ceramic materials and, as a result, there have been significant advances in their development and applications. Their inherent properties, such as capability of operating at temperatures far above metals, high level of hardness and toughness, low coefficient of thermal expansion and high thermal conductivity rendered ceramics to be one of the leading engineering materials. Many research works have been conducted in the past few years on machining of advanced ceramics using different processing methods in order to obtain a better surface roughness, higher material removal rate and improved tool life. Micromachining using chemical etching is one of those methods that do not involve the problem of tool life and direct tool-work piece contact. However, only a few research works have been done on micromachining of ceramics using chemical etching. Hence, study of chemical machining of advanced ceramics is still needed as the process has found wide application in the industry because of its relative low operating costs. In this work, we summarize the recent progresses in machining of different types of advanced ceramics, material processing methods such as wet etching and dry etching, and finally the prospects for control of material removal rate and surface quality in the process of ceramic micromachining.

  10. COMMUNITY DENTAL HEALTH SURVEY TRAINING TO DENTAL HEALTH PERSONNEL

    OpenAIRE

    Sandra Fikawati; Ita Yulita

    2015-01-01

    Dentist and dental nurse as dental health personnel in community health center are spearheads in community dental health service. The effectiveness and efficacy of community dental health service needs updated adequate dental health knowledge and skill. One effort to assure the fulfillment of those needs is by providing community dental health survey training. This training aims at improving the skill and capability of dental health personnel to conduct dental health survey. The training cons...

  11. Localized mechanics of dentin self-etching adhesive system

    Directory of Open Access Journals (Sweden)

    Rodolfo Bruniera Anchieta

    2007-08-01

    Full Text Available The bond strength of composite resins (CRs to dentin is influenced by the interfacial microstructure of the hybrid layer (HL and the resin tags (TAG. The contemporary self-etching primer adhesive systems overcame the inconvenient of the etch-and-rinse protocol. Studies, however, have demonstrated that HL thickness and TAG length vary according to the wetting time and additional use of acid-etching prior to self-etching primers. This study investigated the localized stress distribution in the HL and the dentin/adhesive interface. Two HL thicknesses (3 or 6 µm, two TAG lengths (13 or 17 µm and two loading conditions (perpendicular and oblique-25º were investigated by the finite element (FE analysis. Five two-dimensional FE models (M of a dentin specimen restored with CR (38 x 64 µm were constructed: M1 - no HL and no TAG; M2 - 3 µm of HL and 13 µm of TAG; M3 - 3 µm of HL and 17 µm of TAG; M4 - 6 µm of HL and 13 µm of TAG; and M5 - 6 µm of HL and 17 µm of TAG. Two distributed loadings (L (20N were applied on CR surface: L1 - perpendicular, and L2 - oblique (25º. Fixed interfacial conditions were assigned on the border of the dentin specimen. Ansys 10.0 (Ansys®, Houston, PA, USA software was used to calculate the stress fields. The peak of von Mises (sigmavM and maximum principal stress (sigmamax was higher in L2 than in L1. Microstructures (HL and TAG had no effect on local stresses for L1. Decreasing HL decreased sigmavM and sigmamax in all structures for L2, but the TAG length had influence only on the peributular dentin. The thickness of HL had more influence on the sigmavM and sigmamax than TAG length. The peritubular dentin and its adjacent structures showed the highest sigmavM and sigmamax, mainly in the oblique loading.

  12. Superhydrophobic coatings for aluminium surfaces synthesized by chemical etching process

    Directory of Open Access Journals (Sweden)

    Priya Varshney

    2016-10-01

    Full Text Available In this paper, the superhydrophobic coatings on aluminium surfaces were prepared by two-step (chemical etching followed by coating and one-step (chemical etching and coating in a single step processes using potassium hydroxide and lauric acid. Besides, surface immersion time in solutions was varied in both processes. Wettability and surface morphologies of treated aluminium surfaces were characterized using contact angle measurement technique and scanning electron microscopy, respectively. Microstructures are formed on the treated aluminium surfaces which lead to increase in contact angle of the surface (>150°. Also on increasing immersion time, contact angle further increases due to increase in size and depth of microstructures. Additionally, these superhydrophobic coatings show excellent self-cleaning and corrosion-resistant behavior. Water jet impact, floatation on water surface, and low temperature condensation tests assert the excellent water-repellent nature of coatings. Further, coatings are to be found mechanically, thermally, and ultraviolet stable. Along with, these coatings are found to be excellent regeneration ability as verified experimentally. Although aforesaid both processes generate durable and regenerable superhydrophobic aluminium surfaces with excellent self-cleaning, corrosion-resistant, and water-repellent characteristics, but one-step process is proved more efficient and less time consuming than two-step process and promises to produce superhydrophobic coatings for industrial applications.

  13. Wettability investigating on the wet etching textured multicrystalline silicon wafer

    Science.gov (United States)

    Liu, Xiangju; Niu, Yuchao; Zhai, Tongguang; Ma, Yuying; Zhen, Yongtai; Ma, Xiaoyu; Gao, Ying

    2016-02-01

    In order to investigate the wettability properties of multicrystalline silicon (mc-Si), the different surface structures were fabricated on the as-cut p-type multi-wire slurry sawn mc-Si wafers, such as as-cut, polished and etched in various acid solutions. The contact angles and the XRD spectra of these samples were measured. It was noted that both the surface structures and the use of surfactant, such as Tween 80, made a stronger effect on wettability of the Si wafer. Due to the lipophilic groups of Tween 80 combined with the Si atoms while the hydrophilic groups of it were outward, a lipophilic surface of Si changed into a hydrophilic one and the rougher the surface, the stronger the hydrophily. Thus, it is feasible to add an appropriate surfactant into the etching solution during black-Si wafer fabrication for solar cells. In addition, different crystal plains of Si had different dangling bond density, so that their surface energies were different. A surface with higher surface energy could attract more water atoms and its wettability was better. However, the effect of crystal plain on the surface wettability was much weaker than surface morphology.

  14. Advanced dry etching studies for micro- and nano-systems

    DEFF Research Database (Denmark)

    Rasmussen, Kristian Hagsted

    used for structuring of a magnetic device containing four different materials in nine layers. The materials, tantalum, tantalum oxide, iridiummanganese, and permalloy, can all be etched by reactive ion etching, however the thin layers and the need to etch all layers in one process makes ion beam...

  15. Dopant Selective Reactive Ion Etching of Silicon Carbide

    Science.gov (United States)

    Okojie, Robert (Inventor)

    2016-01-01

    A method for selectively etching a substrate is provided. In one embodiment, an epilayer is grown on top of the substrate. A resistive element may be defined and etched into the epilayer. On the other side of the substrate, the substrate is selectively etched up to the resistive element, leaving a suspended resistive element.

  16. Microtensile bond strength of etch and rinse versus self-etch adhesive systems.

    Science.gov (United States)

    Hamouda, Ibrahim M; Samra, Nagia R; Badawi, Manal F

    2011-04-01

    The aim of this study was to compare the microtensile bond strength of the etch and rinse adhesive versus one-component or two-component self-etch adhesives. Twelve intact human molar teeth were cleaned and the occlusal enamel of the teeth was removed. The exposed dentin surfaces were polished and rinsed, and the adhesives were applied. A microhybride composite resin was applied to form specimens of 4 mm height and 6 mm diameter. The specimens were sectioned perpendicular to the adhesive interface to produce dentin-resin composite sticks, with an adhesive area of approximately 1.4 mm(2). The sticks were subjected to tensile loading until failure occurred. The debonded areas were examined with a scanning electron microscope to determine the site of failure. The results showed that the microtensile bond strength of the etch and rinse adhesive was higher than that of one-component or two-component self-etch adhesives. The scanning electron microscope examination of the dentin surfaces revealed adhesive and mixed modes of failure. The adhesive mode of failure occurred at the adhesive/dentin interface, while the mixed mode of failure occurred partially in the composite and partially at the adhesive/dentin interface. It was concluded that the etch and rinse adhesive had higher microtensile bond strength when compared to that of the self-etch adhesives.

  17. Characterization of electric discharge machining, subsequent etching and shot-peening as a surface treatment for orthopedic implants

    Science.gov (United States)

    Stráský, Josef; Havlíková, Jana; Bačáková, Lucie; Harcuba, Petr; Mhaede, Mansour; Janeček, Miloš

    2013-09-01

    Presented work aims at multi-method characterization of combined surface treatment of Ti-6Al-4V alloy for biomedical use. Surface treatment consists of consequent use of electric discharge machining (EDM), acid etching and shot peening. Surface layers are analyzed employing scanning electron microscopy and energy dispersive X-ray spectroscopy. Acid etching by strong Kroll's reagent is capable of removing surface layer of transformed material created by EDM. Acid etching also creates partly nanostructured surface and significantly contributes to the enhanced proliferation of the bone cells. The cell growth could be positively affected by the superimposed bone-inspired structure of the surface with the morphological features in macro-, micro- and nano-range. Shot peening significantly improves poor fatigue performance after EDM. Final fatigue performance is comparable to benchmark electropolished material without any adverse surface effect. The proposed three-step surface treatment is a low-cost process capable of producing material that is applicable in orthopedics.

  18. Development and evaluation of an interactive dental video game to teach dentin bonding.

    Science.gov (United States)

    Amer, Rafat S; Denehy, Gerald E; Cobb, Deborah S; Dawson, Deborah V; Cunningham-Ford, Marsha A; Bergeron, Cathia

    2011-06-01

    Written and clinical tests compared the change in clinical knowledge and practical clinical skill of first-year dental students watching a clinical video recording of the three-step etch-and-rinse resin bonding system to those using an interactive dental video game teaching the same procedure. The research design was a randomized controlled trial with eighty first-year dental students enrolled in the preclinical operative dentistry course. Students' change in knowledge was measured through written examination using a pre-test and a post-test, as well as clinical tests in the form of a benchtop shear bond strength test. There was no statistically significant difference between teaching methods in regards to change in either knowledge or clinical skills, with one minor exception relating to the wetness of dentin following etching. Students expressed their preference for an interactive self-paced method of teaching.

  19. A review of the developments of multi-purpose primers and adhesives comprising novel dithiooctanoate monomers and phosphonic acid monomers.

    Science.gov (United States)

    Ikemura, Kunio; Endo, Takeshi; Kadoma, Yoshinori

    2012-02-01

    This paper reviews the developments of dithiooctanoate monomers and acidic adhesive monomers, and their roles in multi-purpose primers and adhesives in promoting adhesion to multiple substrate materials. Novel dithiooctanoate monomers exhibited excellent bonding to precious metals and alloys when compared against conventional sulfur-containing monomers. Newly developed phosphonic acid monomers, endowed with a water-soluble nature, enabled sufficient demineralization of dental hard tissues and thus improved bonding to both ground enamel and dentin. The optimal combination for bonding to dental hard tissues and precious and non-precious metals and alloys was 5.0 wt% 10-methacryloyloxydecyl 6,8-dithiooctanoate (10-MDDT) and 1.0 wt% 6-methacryloyloxyhexyl phosphonoacetate (6-MHPA). For bonding to dental porcelain, alumina, zirconia, and gold (Au) alloy, a ternary combination of silane coupling agent, acidic adhesive monomers, and dithiooctanoate monomers seemed promising. The latest development was a single-bottle, multi-purpose, self-etching adhesive which contained only acidic adhesive monomers and dithiooctanoate monomers but which produced strong adhesion to ground enamel and dentin, sandblasted zirconia, and Au alloy.

  20. Comparative evaluation of antibacterial activity of total-etch and self-etch adhesive systems: An ex vitro study

    Directory of Open Access Journals (Sweden)

    Swathi Amin

    2014-01-01

    Full Text Available Aim: The aim of this ex vivo study was to compare the antibacterial activity of total-etch and self-etch adhesive systems against Streptococcus mutans, Lactobacillus acidophilus, and Actinomyces viscosus through disk diffusion method. Materials and Methods: The antibacterial effects of Single Bond (SB and Adper Prompt (AP and aqueous solution of chlorhexidine 0.2% (positive control were tested against standard strain of S. mutans, L. acidophilus, and A. viscosus using the disk diffusion method. The diameters of inhibition zones were measured in millimeters. Data was analyzed using Kruskal-Wallis test. Mann-Whitney U test was used for pairwise comparison. Result: Of all the materials tested, AP showed the maximum inhibitory action against S. mutans and L. acidophilus. Aqueous solution of chlorhexidine 0.2% showed the maximum inhibitory action against A. viscosus. Very minimal antibacterial effect was noted for SB. Conclusion: The antibacterial effects observed for the tested different dentin bonding systems may be related to the acidic nature of the materials.

  1. Four-year water degradation of a total-etch and two self-etching adhesives bonded to dentin

    NARCIS (Netherlands)

    A.I. Abdalla; A.J. Feilzer

    2008-01-01

    Objectives: To evaluate effect of direct and indirect water storage on the microtensile dentin bond strength of one total-etch and two self-etching adhesives. Methods: The adhesive materials were: one total-etch adhesive; ‘Admira Bond’ and two selfetch adhesives; ‘Clearfil SE Bond’ and ‘Hybrid Bond’

  2. Effectiveness of Two Self-Etchings Bonded Clinically in Caries Affected Dentin with Homogeneous Smear Layer

    Directory of Open Access Journals (Sweden)

    Roberto Pinna

    2015-01-01

    Full Text Available Aim. To examine the interface of two self-etchings in carious affected dentin (CAD, under clinical conditions. Materials and Methods. Class I cavities were prepared in 21 carious premolars, refining them by the use of a fine diamond bur in order to create similar smear layer interference. The mild self-etching Clearfil SE Bond (CSE, pH = 2.0, and the strong Tyrian SPE-One Step Plus (TSO, pH = 0.5, were applied followed by a composite. Teeth were extracted and processed for TEM. The primer’s osmolarity of the self-etchings was also calculated using a microosmometer. Results. CSE hybrid layer retained smear layer residues and scattered crystallites as an effect of the mild acidity. A high presence of hydroxyapatite still protected the affected fibres within the hybrid layer. CSE primer demonstrated values of 3220 mOsm/kg. TSO interdiffusion showed strong demineralization. Resin tags were not formed in the dentinal tubules which remained obstructed by crystals. However, dissolution of peritubular dentin and porosities were observed in the intertubular regions. The osmolarity of TSO was 8200 mOsm/kg. Conclusion. Increasing the acidity and osmolarity of the self-etchings increases interference in the homogeneous reinforcement of CAD, which may predispose the hybrid layer to instability and hydrolytic degradation overtime.

  3. SU-8 etching in inductively coupled oxygen plasma

    DEFF Research Database (Denmark)

    Rasmussen, Kristian Hagsted; Keller, Stephan Sylvest; Jensen, Flemming

    2013-01-01

    Structuring or removal of the epoxy based, photo sensitive polymer SU-8 by inductively coupled plasma reactive ion etching (ICP-RIE) was investigated as a function of plasma chemistry, bias power, temperature, and pressure. In a pure oxygen plasma, surface accumulation of antimony from the photo......-initiator introduced severe roughness and reduced etch rate significantly. Addition of SF6 to the plasma chemistry reduced the antimony surface concentration with lower roughness and higher etch rate as an outcome. Furthermore the etch anisotropy could be tuned by controlling the bias power. Etch rates up to 800 nm...

  4. Hierarchical micro-nano structured Ti6Al4V surface topography via two-step etching process for enhanced hydrophilicity and osteoblastic responses.

    Science.gov (United States)

    Moon, Byeong-Seok; Kim, Sungwon; Kim, Hyoun-Ee; Jang, Tae-Sik

    2017-04-01

    Hierarchical micro-nano (HMN) surface structuring of dental implants is a fascinating strategy for achieving fast and mechanically stable fixation due to the synergetic effect of micro- and nano-scale surface roughness with surrounding tissues. However, the introduction of a well-defined nanostructure on a microstructure having complex surface geometry is still challenging. As a means of fabricating HMN surface on Ti6Al4V-ELI, target-ion induced plasma sputtering (TIPS) was used onto a sand-blasted, large-grit and acid-etched substrate. The HMN surface topography was simply controlled by adjusting the tantalum (Ta) target power of the TIPS technique, which is directly related to the Ta ion flux and the surface chemical composition of the substrate. Characterization using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and laser scanning microscopy (LSM) verified that well-defined nano-patterned surface structures with a depth of ~300 to 400nm and a width of ~60 to 70nm were uniformly distributed and followed the complex micron-sized surface geometry. In vitro cellular responses of pre-osteoblast cells (MC3T3-E1) were assessed by attachment and proliferation of cells on flat, nano-roughened, micro-roughened, and an HMN surface structure of Ti6Al4V-ELI. Moreover, an in vivo dog mandible defect model study was used to investigate the biological effect of the HMN surface structure compared with the micro-roughened surface. The results showed that the surface nanostructure significantly increased the cellular activities of flat and micro-roughened Ti, and the bone-to-implant contact area and new bone volume were significantly improved on the HMN surface structured Ti. These results support the idea that an HMN surface structure on Ti6Al4V-ELI alloy has great potential for enhancing the biological performance of dental implants.

  5. 不同表面酸蚀处理对纤维桩与树脂黏结强度影响的实验研究%Effects of different acid etching methods on the bond strength between fiber post and resin

    Institute of Scientific and Technical Information of China (English)

    李磊; 张兴乐; 苏哲君; 时静华; 马莉; 葛志华

    2011-01-01

    目的:观察不同表面酸蚀处理对纤维桩与树脂黏结强度的影响.方法:直径1.25 mm的玻璃纤维桩24根随机分为4组,用300 mL/L过氧化氢(H)、40g/L氢氟酸(F)、320g/L磷酸(P)和蒸馏水(对照组)对纤维桩进行表面处理,并于表面涂布树脂黏结剂后用树脂水门汀将其黏结于树脂模具中.试件在万能材料试验机上进行推出实验.结果:F组黏结强度均值最高(30.28±2.36) MPa,其次为H组(26.15±1.56)MPa,P组(23.71±3.47) MPa,对照组(C组)最小(22.39±2.48) MPa.单因素方差分析及多重比较显示:F组与H组、P组、C组之间有统计学差异(P<0.05);H组与P组、C组之间有统计学差异(P<0.05);P组与C组之间无统计学差异(p>0.05).结论:用300mL/L过氧化氢、40g/L氢氟酸对纤维桩表面进行处理,可有效提高纤维桩与树脂黏结强度.%ABM: To evaluate the effects of different acid etching on the bond strength between fiber postand resin. METHODS: Twenty-four glass fiber posts were divided into 4 groups and were treated with 30% methyl-ene chloride (H), 4% hydrofluoric acid (F) and 32% phosphoretic acid (P) respectively, and then bonded to resin blocks. Push-out tests were performed in a universal testing machine and the bond strength was evaluated. RESULTS: F group showed the highest mean bond strength (30.28 ±2.36)Mpa, which was significantly higher than H group (26.15±1.56)Mpa, P group (23.71 ±3.47)Mpa and C group (22. 39 ±2.48)Mpa (P0. 05). CONCLUSION; Etching by 4% hydrofluoric acid and 30% methylene chloride can significantly enhances bond strength between glass fiber post and resin.

  6. Patterning of platinum (Pt) thin films by chemical wet etching in Aqua Regia

    Science.gov (United States)

    Köllensperger, P. A.; Karl, W. J.; Ahmad, M. M.; Pike, W. T.; Green, M.

    2012-06-01

    The chemical and physical properties of platinum (Pt) make it a useful material for microelectromechanical systems and microfluidic applications such as lab-on-a-chip devices. Platinum thin-films are frequently employed in applications where electrodes with high chemical stability, low electrical resistance or a high melting point are needed. Due to its chemical inertness it is however also one of the most difficult metals to pattern. The gold standard for patterning is chlorine RIE etching, a capital-intensive process not available in all labs. Here we present simple fabrication protocols for wet etching Pt thin-films in hot Aqua Regia based on sputtered Ti/Pt/Cr and Cr/Pt/Cr metal multilayers. Chromium (Cr) or titanium (Ti) is used as an adhesion layer for the Pt. Cr is used as a hard masking layer during the Pt etch as it can be easily and accurately patterned with photoresist and withstands the Aqua Regia. The Cr pattern is transferred into the Pt and the Cr mask later removed. Only standard chemicals and cleanroom equipment/tools are required. Prior to the Aqua Regia etch any surface passivation on the Pt is needs to be removed. This is usually achieved by a quick dip in dilute hydrofluoric acid (HF). HF is usually also used for wet-etching the Ti adhesion layer. We avoid the use of HF for both steps by replacing the HF-dip with an argon (Ar) plasma treatment and etching the Ti layer with a hydrogen peroxide (H2O2) based etchant.

  7. Dental Encounter System (DES)

    Data.gov (United States)

    Department of Veterans Affairs — Dental Encounter System (DES) is an automated health care application designed to capture critical data about the operations of VA Dental Services. Information on...

  8. Dental education in Malaysia.

    Science.gov (United States)

    Komabayashi, Takashi; Razak, Abdul Aziz Abdul; Bird, William F

    2007-12-01

    There was only one dental school in Malaysia until 1997 but five new schools have been established since 1998. This review provides information about dental education in Malaysia including; the history of dental education, the current dental school system and curriculum, and dental licensure. There are four public and two private dental schools in Malaysia. High school graduates are required to take the nationwide matriculation entrance examination or the Higher School Certificate (HSC) to apply for a dental degree programme. A five-year dental programme leads to the BDS or the DDS degree. National or state examinations are not required to practise dentistry. Currently, there are approximately 2,500 dentists, with a ratio of 1 dentist for every 10,000 people.

  9. Surface engineering of SiC via sublimation etching

    Science.gov (United States)

    Jokubavicius, Valdas; Yazdi, Gholam R.; Ivanov, Ivan G.; Niu, Yuran; Zakharov, Alexei; Iakimov, Tihomir; Syväjärvi, Mikael; Yakimova, Rositsa

    2016-12-01

    We present a technique for etching of SiC which is based on sublimation and can be used to modify the morphology and reconstruction of silicon carbide surface for subsequent epitaxial growth of various materials, for example graphene. The sublimation etching of 6H-, 4H- and 3C-SiC was explored in vacuum (10-5 mbar) and Ar (700 mbar) ambient using two different etching arrangements which can be considered as Si-C and Si-C-Ta chemical systems exhibiting different vapor phase stoichiometry at a given temperature. The surfaces of different polytypes etched under similar conditions are compared and the etching mechanism is discussed with an emphasis on the role of tantalum as a carbon getter. To demonstrate applicability of such etching process graphene nanoribbons were grown on a 4H-SiC surface that was pre-patterned using the thermal etching technique presented in this study.

  10. 75 FR 33169 - Dental Devices: Classification of Dental Amalgam, Reclassification of Dental Mercury, Designation...

    Science.gov (United States)

    2010-06-11

    ...-AG21 Dental Devices: Classification of Dental Amalgam, Reclassification of Dental Mercury, Designation of Special Controls for Dental Amalgam, Mercury, and Amalgam Alloy; Technical Amendment AGENCY: Food... classified dental amalgam as a class II device, reclassified dental mercury from class I to class II,...

  11. Denitrification in human dental plaque

    Directory of Open Access Journals (Sweden)

    Verstraete Willy

    2010-03-01

    Full Text Available Abstract Background Microbial denitrification is not considered important in human-associated microbial communities. Accordingly, metabolic investigations of the microbial biofilm communities of human dental plaque have focused on aerobic respiration and acid fermentation of carbohydrates, even though it is known that the oral habitat is constantly exposed to nitrate (NO3- concentrations in the millimolar range and that dental plaque houses bacteria that can reduce this NO3- to nitrite (NO2-. Results We show that dental plaque mediates denitrification of NO3- to nitric oxide (NO, nitrous oxide (N2O, and dinitrogen (N2 using microsensor measurements, 15N isotopic labelling and molecular detection of denitrification genes. In vivo N2O accumulation rates in the mouth depended on the presence of dental plaque and on salivary NO3- concentrations. NO and N2O production by denitrification occurred under aerobic conditions and was regulated by plaque pH. Conclusions Increases of NO concentrations were in the range of effective concentrations for NO signalling to human host cells and, thus, may locally affect blood flow, signalling between nerves and inflammatory processes in the gum. This is specifically significant for the understanding of periodontal diseases, where NO has been shown to play a key role, but where gingival cells are believed to be the only source of NO. More generally, this study establishes denitrification by human-associated microbial communities as a significant metabolic pathway which, due to concurrent NO formation, provides a basis for symbiotic interactions.

  12. Block copolymer templated etching on silicon.

    Science.gov (United States)

    Qiao, Yinghong; Wang, Dong; Buriak, Jillian M

    2007-02-01

    The use of self-assembled polymer structures to direct the formation of mesoscopic (1-100 nm) features on silicon could provide a fabrication-compatible means to produce nanoscale patterns, supplementing conventional lithographic techniques. Here we demonstrate nanoscale etching of silicon, applying standard aqueous-based fluoride etchants, to produce three-dimensional nanoscale features with controllable shapes, sizes, average spacing, and chemical functionalization. The block copolymers serve to direct the silicon surface chemistry by controlling the spatial location of the reaction as well as concentration of reagents. The interiors of the resulting etched nanoscale features may be selectively functionalized with organic monolayers, metal nanoparticles, and other materials, leading to a range of ordered arrays on silicon.

  13. Development of Wet-Etching Tools for Precision Optical Figuring

    Energy Technology Data Exchange (ETDEWEB)

    Rushford, M C; Dixit, S N; Hyde, R; Britten, J A; Nissen, J; Aasen, M; Toeppen, J; Hoaglan, C; Nelson, C; Summers, L; Thomas, I

    2004-01-27

    This FY03 final report on Wet Etch Figuring involves a 2D thermal tool. Its purpose is to flatten (0.3 to 1 mm thickness) sheets of glass faster thus cheaper than conventional sub aperture tools. An array of resistors on a circuit board was used to heat acid over the glass Optical Path Difference (OPD) thick spots and at times this heating extended over the most of the glass aperture. Where the acid is heated on the glass it dissolves faster. A self-referencing interferometer measured the glass thickness, its design taking advantage of the parallel nature and thinness of these glass sheets. This measurement is used in close loop control of the heating patterns of the circuit board thus glass and acid. Only the glass and acid were to be moved to make the tool logistically simple to use in mass production. A set of 4-circuit board, covering 80 x 80-cm aperture was ordered, but only one 40 x 40-cm board was put together and tested for this report. The interferometer measurement of glass OPD was slower than needed on some glass profiles. Sometimes the interference fringes were too fine to resolve which would alias the sign of the glass thickness profile. This also caused the phase unwrapping code (FLYNN) to struggle thus run slowly at times taking hours, for a 10 inch square area. We did extensive work to improve the speed of this code. We tried many different phase unwrapping codes. Eventually running (FLYNN) on a farm of networked computers. Most of the work reported here is therefore limited to a 10-inch square aperture. Researched into fabricating a better interferometer lens from Plexiglas so to have less of the scattered light issues of Fresnel lens groves near field scattering patterns, this set the Nyquest limit. There was also a problem with the initial concept of wetting the 1737 glass on its bottom side with acid. The wetted 1737 glass developed an Achromatic AR coating, spoiling the reflection needed to see glass thickness interference fringes. In response

  14. Characterization of stain etched p-type silicon in aqueous HF solutions containing HNO{sub 3} or KMnO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Mogoda, A.S., E-mail: awad_mogoda@hotmail.com [Department of Chemistry, Faculty of Science, Cairo University, Giza (Egypt); Ahmad, Y.H.; Badawy, W.A. [Department of Chemistry, Faculty of Science, Cairo University, Giza (Egypt)

    2011-04-15

    Research highlights: {yields} Stain etching of p-Si in aqueous HF solutions containing HNO{sub 3} or KMnO{sub 4} was investigated. {yields} The electrical conductivity of the etched Si surfaces was measured using impedance technique. {yields} Scanning electron microscope and energy disperse X-ray were used to analyze the etched surfaces. {yields} Etching in aqueous HF solution containing HNO{sub 3} led to formation of a porous silicon layer. {yields} The formation of the porous silicon layer in HF/KMnO{sub 4} was accompanied by deposition of K{sub 2}SiF{sub 6} on the pores surfaces. - Abstract: Stain etching of p-type silicon in hydrofluoric acid solutions containing nitric acid or potassium permanganate as an oxidizing agent has been examined. The effects of etching time, oxidizing agent and HF concentrations on the electrochemical behavior of etched silicon surfaces have been investigated by electrochemical impedance spectroscopy (EIS). An electrical equivalent circuit was used for fitting the impedance data. The morphology and the chemical composition of the etched Si surface were studied using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques, respectively. A porous silicon layer was formed on Si etched in HF solutions containing HNO{sub 3}, while etching in HF solutions containing KMnO{sub 4} led to the formation of a porous layer and simultaneous deposition of K{sub 2}SiF{sub 6} inside the pores. The thickness of K{sub 2}SiF{sub 6} layer increases with increasing the KMnO{sub 4} concentration and decreases as the concentration of HF increases.

  15. Characterization of aluminum surfaces: Sorption and etching

    Science.gov (United States)

    Polkinghorne, Jeannette Clera

    Aluminum, due to its low density and low cost, is a key material for future lightweight applications. However, like other structural materials, aluminum is subject to various forms of corrosion damage that annually costs the United States approximately 5% of its GNP [1]. The main goal is to investigate the effects of various solution anions on aluminum surfaces, and specifically probe pit initiation and inhibition. Using surface analysis techniques including X-ray photoelectron spectroscopy, Auger electron spectroscopy, and scanning electron microscopy, results have been correlated with those obtained from electrochemical methods and a radiolabeling technique developed in the Wieckowski laboratory. Analysis of data has indicated that important variables include type of anion, solution pH, and applied electrode potential. While aggressive anions such as chloride are usually studied to elucidate corrosion processes to work ultimately toward inhibition, its corrosive properties can be successfully utilized in the drive for higher energy and smaller-scale storage devices. Fundamental information gained regarding anion interaction with the aluminum surface can be applied to tailor etch processes. Standard electrochemical techniques and SEM are respectively used to etch and analyze the aluminum substrate. Aluminum electrolytic capacitors are comprised of aluminum anode foil covered by an anodically grown aluminum oxide dielectric film, electrolytic paper impregnated with electrolyte, and aluminum cathode foil. Two main processes are involved in the fabrication of aluminum electrolytic capacitors, namely etching and anodic oxide formation. Etching of the anode foil results in a higher surface area (up to 20 times area enlargement compared to unetched foil) that translates into a higher capacitance gain, permitting more compact and lighter capacitor manufacture. Anodic oxide formation on the anode, creates the required dielectric to withstand high voltage operation. A

  16. Synthesis and Characterization of Chemically Etched Nanostructured Silicon

    KAUST Repository

    Mughal, Asad Jahangir

    2012-05-01

    Silicon is an essential element in today’s modern world. Nanostructured Si is a more recently studied variant, which has currently garnered much attention. When its spatial dimensions are confined below a certain limit, its optical properties change dramatically. It transforms from an indirect bandgap material that does not absorb or emit light efficiently into one which can emit visible light at room temperatures. Although much work has been conducted in understanding the properties of nanostructured Si, in particular porous Si surfaces, a clear understanding of the origin of photoluminescence has not yet been produced. Typical synthesis approaches used to produce nanostructured Si, in particular porous Si and nanocrystalline Si have involved complex preparations used at high temperatures, pressures, or currents. The purpose of this thesis is to develop an easier synthesis approach to produce nanostructured Si as well as arrive at a clearer understanding of the origin of photoluminescence in these systems. We used a simple chemical etching technique followed by sonication to produce nanostructured Si suspensions. The etching process involved producing pores on the surface of a Si substrate in a solution containing hydrofluoric acid and an oxidant. Nanocrystalline Si as well as nanoscale amorphous porous Si suspensions were successfully synthesized using this process. We probed into the phase, composition, and origin of photoluminescence in these materials, through the use of several characterization techniques. TEM and SEM were used to determine morphology and phase. FT-IR and XPS were employed to study chemical compositions, and steady state and time resolved optical spectroscopy techniques were applied to resolve their photoluminescent properties. Our work has revealed that the type of oxidant utilized during etching had a significant impact on the final product. When using nitric acid as the oxidant, we formed nanocrystalline Si suspensions composed of

  17. Improved osseointegration of dental titanium implants by TiO2 nanotube arrays with recombinant human bone morphogenetic protein-2: a pilot in vivo study

    Science.gov (United States)

    Lee, Jae-Kwan; Choi, Dong-Soon; Jang, Insan; Choi, Won-Youl

    2015-01-01

    TiO2 nanotube arrays on the surface of dental implants were fabricated by two-step anodic oxidation. Their effects on bone-implant contact were researched by a pilot in vivo study. The implants were classified into four groups. An implant group with TiO2 nanotube arrays and recombinant human bone morphogenetic protein-2 (rhBMP-2) was compared with various surface implants, including machined surface, sandblasted large-grit and acid-etched surface, and TiO2 nanotube array surface groups. The diameter of the TiO2 nanotube window and TiO2 nanotube were ~70 nm and ~110 nm, respectively. The rhBMP-2 was loaded into TiO2 nanotube arrays and elution was detected by an interferometric biosensing method. A change in optical thickness of ~75 nm was measured by flow cell testing for 9 days, indicating elution of rhBMP-2 from the TiO2 nanotube arrays. For the in vivo study, the four groups of implants were placed into the proximal tibia of New Zealand White rabbits. In the implant group with TiO2 nanotube arrays and rhBMP-2, the bone-to-implant contact ratio was 29.5% and the bone volume ratio was 77.3%. Bone remodeling was observed not only in the periosteum but also in the interface between the bone and implant threads. These values were higher than in the machined surface, sandblasted large-grit and acid-etched surface, and TiO2 nanotube array surface groups. Our results suggest that TiO2 nanotube arrays could potentially be used as a reservoir for rhBMP-2 to reinforce osseointegration on the surface of dental implants. PMID:25709438

  18. [Dental records and responsibility

    NARCIS (Netherlands)

    Brands, W.G.

    2006-01-01

    Dental records are more than a small part of the bookkeeping. In most dental practises, keeping records is the task of a dental assistant. In civil court, the dentist is in most countries liable for the mistakes of his employees. In disciplinary court however there may be doubt whether the dentist i

  19. Stress Among Dental Students

    NARCIS (Netherlands)

    A.M. Alzahem (Abdullah)

    2015-01-01

    markdownabstractAbstract Dental students are facing many stressors in dental education, causing many negative outcomes. The most common are the exams and the clinical requirements. We suggest exposing the dental students to patient care as early as possible in their curriculum. This can help to bal

  20. Transport through track etched polymeric blend membrane

    Indian Academy of Sciences (India)

    Kamlendra Awasthi; Vaibhav Kulshreshtha; B Tripathi; N K Acharya; M Singh; Y K Vijay

    2006-06-01

    Polymer blends of polycarbonate (PC) and polysulphone (PSF) having thickness, 27 m, are prepared by solution cast method. The transport properties of pores in a blend membrane are examined. The pores were produced in this membrane by a track etching technique. For this purpose, a thin polymer membrane was penetrated by a single heavy ion of Ni7+ of 100 MeV, followed by preferential chemical etching of the ion track. Ion permeation measurements show that pores in polymeric membrane are charged or neutralized, which depends upon the variation in concentration of the solvent. The – curve at concentration, N/10, shows that the pores are negatively charged, whereas at concentration, N/20, the linear nature of – curve indicates that the pores approach towards neutralized state and on further concentration, N/40, the pores become fully neutralized, consequently the rectifier behaviour of pores has been omitted. The gas permeability of hydrogen and carbon dioxide of this membrane was measured with increasing etching time. The permeability was measured from both the sides. Permeability at the front was larger than the permeability at the back which shows asymmetric behaviour of membranes.

  1. Crystallographic orientation dependent etching of graphene layers

    Energy Technology Data Exchange (ETDEWEB)

    Nemes-Incze, Peter; Biro, Laszlo Peter [Research Institute for Technical Physics and Materials Science, PO. Box 49, 1525 Budapest (Hungary); Magda, Gabor [Budapest University of Technology and Economics (BME), PO Box 91, 1521 Budapest (Hungary); Kamaras, Katalin [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, PO Box 49, 1525, Budapest (Hungary)

    2010-04-15

    Graphene has gripped the scientific community ever since its discovery in 2004, with very promising electronic properties and hopes to integrate graphene into nanoelectronic devices. For graphene to make its way into electronic devices, two major obstacles have to be overcome: reproducible preparation of large area graphene samples and patterning techniques to obtain functional components. In this paper we present a graphene etching technique, which is crystallographic orientation selective and allows for the patterning of graphene layers using a chemical reduction process. The process involves the reduction of the SiO{sub 2} support by the carbon in the graphene itself. This reaction only occurs at the sample edges and does not result in the degradation of the graphene crystal lattice itself. However, we have observed evidence of strong hole doping in our etched samples. This etching technique opens up new possibilities in graphene patterning and modification. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Non-thermal Atmospheric Plasma Treatment for Deactivation of Oral Bacteria and Improvement of Dental Composite Restoration

    Science.gov (United States)

    Yu, Qing Song; Li, H.; Ritts, A. C.; Yang, B.; Chen, M.; Hong, L.; Xu, C.; Yao, X.; Wang, Y.

    This paper reviews our recent research results of using non-thermal ­atmospheric plasmas for oral bacterial deactivation and for composite restoration improvement. Oral bacteria of Streptococcus mutans (S. mutans) and Lactobacillus acidophilus (L. acidophilus) with an initial bacterial population density between 1.0 × 108 and 5.0 × 108 cfu/ml were seeded on various media and their survivability with plasma exposure was examined. The plasma exposure time for a 99.9999% cell reduction was less than 15 s for S. mutans and within 5 min for L. acidophilus. To evaluate the dentin/composite interfacial bonding, extracted unerupted human third molars were used by removing the crowns and etching the exposed dentin surfaces with 35% phosphoric acid gel. After dental composite application and light curing, the teeth were then sectioned into micro-bars as the specimens for microtensile test. Student Newman Keuls (SNK) tests showed that the bonding strength of the composite restoration to peripheral dentin was significantly increased (by 64%) after 30 s plasma treatment of the dentin surfaces. These findings indicated that non-thermal atmospheric plasma technology is very promising for dental clinical applications.

  3. Importance of the Roughness and Residual Stresses of Dental Implants on Fatigue and Osseointegration Behavior. In Vivo Study in Rabbits.

    Science.gov (United States)

    Velasco, Eugenio; Monsalve-Guil, Loreto; Jimenez, Alvaro; Ortiz, Iván; Moreno-Muñoz, Jesús; Nuñez-Marquez, Enrique; Pegueroles, Marta; Pérez, Román A; Gil, Francisco Javier

    2016-12-01

    This study focuses on the fatigue behavior and bone-implant attachment for the more usual surfaces of the different CP-titanium dental implants. The implants studied were: as-received (CTR), acid etching (AE), spark-anodization (SA), and with a grit-blasted surface (GB). Residual stresses were determined by means of X-ray diffraction. The fatigue tests were carried out at 37°C on 160 dental implants, and the stress-failure (S-N) curve was determined. The fatigue tests showed that the grit-blasting process improved fatigue life. This is a consequence of the layer of compressive residual stresses that the treatment generates in titanium surfaces. Further, our aim was to assess and compare the short- and midterm bone regenerative potential and mechanical retention of the implants in bone of New Zealand rabbits. The mechanical retention after 4 and 10 weeks of implantation was evaluated with histometric and pull-out tests, respectively, as a measure of the osseointegration of the implants. The results demonstrated that the GB treatment produced microrough that accelerated bone tissue regeneration and increased mechanical retention in the bone bed at short periods of implantation in comparison with all other implants tested. The GB surface produced an improvement in mechanical long-time behavior and improved bone growth. These types of treated implants can have great potential in clinical applications, as evidenced by the outcomes of the current study.

  4. Two-Layer Microstructures Fabricated by One-Step Anisotropic Wet Etching of Si in KOH Solution

    Directory of Open Access Journals (Sweden)

    Han Lu

    2016-01-01

    Full Text Available Anisotropic etching of silicon in potassium hydroxide (KOH is an important technology in micromachining. The residue deposition from KOH etching of Si is typically regarded as a disadvantage of this technology. In this report, we make use of this residue as a second masking layer to fabricate two-layer complex structures. Square patterns with size in the range of 15–150 μm and gap distance of 5 μm have been designed and tested. The residue masking layer appears when the substrate is over-etched in hydrofluoric acid (HF solution over a threshold. The two-layer structures of micropyramids surrounded by wall-like structures are obtained according to the two different masking layers of SiO2 and residue. The residue masking layer is stable and can survive over KOH etching for long time to achieve deep Si etching. The process parameters of etchant concentration, temperature, etching time and pattern size have been investigated. With well-controlled two-layer structures, useful structures could be designed for applications in plasmonic and microfluidic devices in the future.

  5. Effect of a functional monomer (MDP) on the enamel bond durability of single-step self-etch adhesives.

    Science.gov (United States)

    Tsuchiya, Kenji; Takamizawa, Toshiki; Barkmeier, Wayne W; Tsubota, Keishi; Tsujimoto, Akimasa; Berry, Thomas P; Erickson, Robert L; Latta, Mark A; Miyazaki, Masashi

    2016-02-01

    The present study aimed to determine the effect of the functional monomer, 10-methacryloxydecyl dihydrogen phosphate (MDP), on the enamel bond durability of single-step self-etch adhesives through integrating fatigue testing and long-term water storage. An MDP-containing self-etch adhesive, Clearfil Bond SE ONE (SE), and an experimental adhesive, MDP-free (MF), which comprised the same ingredients as SE apart from MDP, were used. Shear bond strength (SBS) and shear fatigue strength (SFS) were measured with or without phosphoric acid pre-etching. The specimens were stored in distilled water for 24 h, 6 months, or 1 yr. Although similar SBS and SFS values were obtained for SE with pre-etching and for MF after 24 h of storage in distilled water, SE with pre-etching showed higher SBS and SFS values than MF after storage in water for 6 months or 1 yr. Regardless of the pre-etching procedure, SE showed higher SBS and SFS values after 6 months of storage in distilled water than after 24 h or 1 yr. To conclude, MDP might play an important role in enhancing not only bond strength but also bond durability with respect to repeated subcritical loading after long-term water storage.

  6. Etiology and pathogenesis of dental erosion.

    Science.gov (United States)

    Kanzow, Philipp; Wegehaupt, Florian J; Attin, Thomas; Wiegand, Annette

    2016-04-01

    The condition of dental erosion is defined as acid-related loss of tooth structure which does not involve microorganisms. Depending on the origin of the acid, extrinsic (usually caused by acids in food) and intrinsic (caused by endogenous acid) erosion can be distinguished. The presence and severity of erosive defects depend on various parameters such as nutrition, saliva, general diseases, and mechanical stress by abrasion and attrition. As an example, dietary habits which involve frequent intake of acidic food and beverages, occupational acid exposure, as well as certain drugs or diseases that affect saliva flow rate are accompanied by an increased risk of erosive dental hard tissue defects. By a thorough clinical examination and an accurate anamnesis, various erosion-related risk factors can be identified and strategies to reduce or eliminate these factors be identified.

  7. In vivo evaluation of micro-rough and bioactive titanium dental implants using histometry and pull-out tests.

    Science.gov (United States)

    Aparicio, Conrado; Padrós, Alejandro; Gil, Francisco-Javier

    2011-11-01

    We report on the in vivo histological and mechanical performance of titanium dental implants with a new surface treatment (2Step) consisting of an initial grit-blasting process to produce a micro-rough surface, followed by a combined chemical and thermal treatment that produces a potentially bioactive surface, i.e., that can form an apatitic layer when exposed to biomimetic conditions in vitro. Our aim was to assess the short- and mid-term bone regenerative potential and mechanical retention of 2Step implants in mandible and maxilla of minipigs and compare them with micro-rough grit-blasted, micro-rough acid-etched, and smooth as-machined titanium implants. The percent of bone-to-implant contact after 2, 4, 6, and 10 weeks of implantation as well as the mechanical retention after 4, and 6 weeks of implantation were evaluated with histometric and pull-out tests, respectively, as a measure of the osseointegration of the implants. We also aimed to assess the bioactive nature of 2Step surfaces in vivo. Our results demonstrated that the 2Step treatment produced micro-rough and bioactive implants that accelerated bone tissue regeneration and increased mechanical retention in the bone bed at short periods of implantation in comparison with all other implants tested. This was mostly attributed to the ability of 2Step implants to form in vivo a layer of apatitic mineral that coated the implant and could rapidly stimulate (a) bone nucleation directly on the implant surface, and (b) bone growing from the implant surface. We also proved that roughness values of Ra≈4.5 μm favoured osseointegration of dental implants at short- and mid-term healing periods, as grit-blasted implants and 2Step implants had higher retention values than as machined and acid-etched implants. The surface quality resulting from the 2Step treatment applied on cpTi provided dental implants with a unique combination of rapid bone regeneration and high mechanical retention.

  8. Micromorphology of ceramic etching pattern for two CAD-CAM and one conventional feldspathic porcelain and need for post-etching cleaning.

    Science.gov (United States)

    Onisor, Ioana; Rocca, Giovanni Tommaso; Krejci, Ivo

    2014-01-01

    The aim of this in vitro study was to observe the effect of hydrofluoric acid (HF) on the surface of two glass ceramics for Cerec and to compare it with the effect on a conventional glass ceramic. Discs were cut from a feldspathic ceramic block (VitaMKII) and from a leucite reinforced glass ceramic (IPS EMPRESS CAD) for Cerec. 5% and 9% HF concentrations were used during 1 min and 2 min each. Afterwards samples were thoroughly water rinsed for 30 s. Half of the 9% HF 1 min samples were subsequently submitted to a complex post-etching cleaning. All samples were observed under a scanning electron microscope (SEM). The conventional feldspathic ceramic samples were built up on a refractory die and a platinum foil. They were treated with 9% HF for 2 min and water rinsed for 30 s. Half of the samples were submitted to the same post-etching cleaning protocol. All samples were examined under SEM and EDX. The Cerec ceramic samples and the platinum foil ones were clean and free of any precipitate after 30 s of water rinsing. Acid concentration, times of application and the postetching cleaning treatment did not influence the cleanliness of the samples. A thick layer of deposit was observed only on the refractory die samples. This was only diminished after the post-etching treatment. The EDX analysis detected the presence of fluoride (F) only on the refractory die samples.

  9. Study on the effects of enamel treatments on losing ratio of orthodontic brackets bonding to different degree of dental fluorosis%不同氟斑牙程度及临床处理方法对正畸托槽脱落率的影响研究

    Institute of Scientific and Technical Information of China (English)

    董晶

    2015-01-01

    Objective To investigate the effects of different enamel treatments on losing ratio of orthodontic brackets bonding to different degree of dental fluorosis. Methods A total of 30 patients with fluorosis were selected.They were divided into mild,moderate and severe degree groups according to Dean's criteria.Patients within each group were randomly assigned to 2 subgroup. Different methods including bonding after extending the etching time and bonding after microabrasion and normal acid etching were used respectively in the 2 subgroups of each group.The losing ratio of brackets was observed.The main effect and interaction effect of the degree of fluorosis and enamel treatments on losing ratio were analyzed. Results There was significant difference in the losing ratio between severe dental fluorosis and mild,moderate dental fluorosis in both treatments.The losing ratio of severe dental fluorosis was higher.There was no significant difference in the losing ratio between two treatments in the condition of mild dental fluorosis.There was significant difference in the losing ratio between two treatments in the condition of moderate and severe dental fluorosis.The method of bonding after microabrasion and normal acid etching was superior to the method of bonding after extending the etching time in the condition of moderate and severe dental fluorosis. Conclusion The main effect and interaction effect of the degree of fluorosis and enamel treatments on losing ratio are significant.The specific degree of dental fluorosis should be considered during the course of selecting appropriate treatment methods.%目的:探讨不同氟斑牙程度及处理方法对临床正畸托槽脱落率的影响.方法:选择需进行正畸治疗的氟斑牙患者共30例,按Dean氏法分为轻度、中度、重度3个组,各组内随机分为2个分组,分别采用延长酸蚀时间后粘结和磨除后常规酸蚀粘结的临床操作方法.观察托槽脱落率,并分析氟斑程度和处理

  10. HF-based etching processes for improving laser damage resistance of fused silica optical surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Suratwala, T I; Miller, P E; Bude, J D; Steele, R A; Shen, N; Monticelli, M V; Feit, M D; Laurence, T A; Norton, M A; Carr, C W; Wong, L L

    2010-02-23

    The effect of various HF-based etching processes on the laser damage resistance of scratched fused silica surfaces has been investigated. Conventionally polished and subsequently scratched fused silica plates were treated by submerging in various HF-based etchants (HF or NH{sub 4}F:HF at various ratios and concentrations) under different process conditions (e.g., agitation frequencies, etch times, rinse conditions, and environmental cleanliness). Subsequently, the laser damage resistance (at 351 or 355 nm) of the treated surface was measured. The laser damage resistance was found to be strongly process dependent and scaled inversely with scratch width. The etching process was optimized to remove or prevent the presence of identified precursors (chemical impurities, fracture surfaces, and silica-based redeposit) known to lead to laser damage initiation. The redeposit precursor was reduced (and hence the damage threshold was increased) by: (1) increasing the SiF{sub 6}{sup 2-} solubility through reduction in the NH4F concentration and impurity cation impurities, and (2) improving the mass transport of reaction product (SiF{sub 6}{sup 2-}) (using high frequency ultrasonic agitation and excessive spray rinsing) away from the etched surface. A 2D finite element crack-etching and rinsing mass transport model (incorporating diffusion and advection) was used to predict reaction product concentration. The predictions are consistent with the experimentally observed process trends. The laser damage thresholds also increased with etched amount (up to {approx}30 {micro}m), which has been attributed to: (1) etching through lateral cracks where there is poor acid penetration, and (2) increasing the crack opening resulting in increased mass transport rates. With the optimized etch process, laser damage resistance increased dramatically; the average threshold fluence for damage initiation for 30 {micro}m wide scratches increased from 7 to 41 J/cm{sup 2}, and the statistical

  11. [Restoration of composite on etched stainless steel crowns. (1)].

    Science.gov (United States)

    Goto, G; Zang, Y; Hosoya, Y

    1990-01-01

    Object of investigation The retention of composite resin to etched stainless steel crowns was tested as a possible method for restoring primary anterior teeth. Method employed 1) SEM observation Stainless steel crowns (Sankin Manufacture Co.) were etched with an aqua resia to create surface roughness and undercut to retain the composite resin to the crowns. Etching times were 1, 2, 3, 5, 8, 10 and 20 minutes, then washed in a 70% alcohol solution using an ultrasonic washer and dried. A total of 96 etched samples and non etched control samples were observed through the scanning electron microscope (Hitachi 520). 2) Shear bond strength test Stainless steel crowns were etched in an aqua resia from 1 to 20 minutes, then washed and dried. Composite resin (Photo Clearfil A, Kuraray Co.) with the bonding agent was placed on the crowns and the shear bond strength was tested in 56 samples using an Autograph (DCS-500, Shimazu). Results 1) SEM observation showed that the etching surface of stainless steel crowns created surface roughness and undercut. The most desirable surface was obtained in the 3 to 5 minute etching time specimens. 2) The highest bond strength was obtained in a 3 minute etching specimen. It was 42.12 MPa, although 29.26 MPa in mean value. Conclusion Etching with an aqua resia increased the adherence of composite resin to the surface of stainless steel crowns.

  12. Histologic Evaluation of Human Pulp Response to Total Etch and Self Etch Adhesive Systems

    OpenAIRE

    Malekipour, Mohammad Reza; Razavi, Sayed Mohammad; Khazaei, Saber; Kazemi, Shantia; Behnamanesh, Maryam; Shirani, Farzaneh

    2013-01-01

    Background To investigate pulp response to the application of two types adhesive systems (total-etch and self-etch) in human premolar teeth. Materials and Methods Cavities limited to enamel walls in all margins with 2.5 mm depth were prepared on buccal surfaces of thirty three human premolars. The cavities were treated with the following adhesive. Single Bond (SB) and Prompt L-Pop (PLP). The teeth were extracted after 30 days and prepared due to histological technique. Results Pulp responses ...

  13. Growth, etching, and stability of sputtered ZnO:Al for thin-film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Owen, Jorj Ian

    2011-07-01

    Aluminum-doped zinc oxide (ZnO:Al) can fulfill many requirements in thin-film solar cells, acting as (1) a transparent contact through which the incident light is transmitted, (2) part of the back reflector, and (3) a source of light scattering. Magnetron sputtered ZnO:Al thin-films are highly transparent, conductive, and are typically texturized by post-deposition etching in a dilute hydrochloric acid (HCl) solution to achieve light scattering. The ZnO:Al thin-film electronic and optical properties, as well as the surface texture after etching, depend on the deposition conditions and the post-deposition treatments. Despite having been used in thin-film solar cells for more than a decade, many aspects regarding the growth, effects of heat treatments, environmental stability, and etching of sputtered ZnO:Al are not fully understood. This work endeavors to further the understanding of ZnO:Al for the purpose improving silicon thin-film solar cell efficiency and reducing ZnO:Al production costs. With regard to the growth of ZnO:Al, the influence of various deposition conditions on the resultant electrical and structural properties and their evolution with film thickness were studied. The surface electrical properties extracted from a multilayer model show that while carrier concentration of the surface layer saturates already at film thickness of 100 nm, the surface mobility continues to increases with film thickness, and it is concluded that electronic transport across grain boundaries limits mobility in ZnO:Al thin films. ZnO:Al deposited onto a previously etched ZnO:Al surface grows epitaxially, preserving both the original orientation and grain structure. Further, it is determined that a typical ZnO:Al used in thin-film silicon solar cells grows Zn-terminated on glass substrates. Concerning the affects of heat treatments and stability, it is demonstrated that a layer of amorphous silicon can protect ZnO:Al from degradation during annealing, and the mobility of Zn

  14. Influence of microhybrid resin and etching times on bleached enamel for the bonding of ceramic brackets.

    Science.gov (United States)

    Firoozmand, Leily Macedo; Brandão, Juliana Viana Pereira; Fialho, Melissa Proença Nogueira

    2013-01-01

    The aim of this study was to evaluate the shear bond strength (SBS) of polycrystalline ceramic brackets (PCB) bonded after bleaching treatment using different composite resins and enamel etching times. A total of 144 bovine incisors were randomly divided into two study groups (n = 72, each) as follows: G1, enamel bleached with 35% hydrogen peroxide, and G2 (control group), enamel unbleached. After the bleaching treatment, the samples were stored in artificial saliva for 14 days. These groups were further divided into two subgroups (n = 36, each) as follows: GA, brackets bonded with Transbond XT (3M) and GB, brackets bonded with Filtek Z250 (3M). For each resin used, three different etching times with 37% phosphoric acid (15, 30 and 60 seconds) were tested. SBS tests were performed using a universal testing machine (EMIC), and the adhesive remnant index (ARI) score was verified. Significant differences among the three experimental conditions and interactions between the groups were observed. The type of composite resin accounted for 24% of the influence on the bond strength, whereas the etching time and bleaching treatment accounted for 14.5% and 10% of the influence on bond strength, respectively. The ARI revealed that the most common area of adhesion failure was at the composite resin-bracket interface. The type of composite resin, etching time and external bleaching significantly influenced the SBS of PCB on enamel, even after 14 days of saliva storage.

  15. Influence of microhybrid resin and etching times on bleached enamel for the bonding of ceramic brackets

    Directory of Open Access Journals (Sweden)

    Leily Macedo Firoozmand

    2013-04-01

    Full Text Available The aim of this study was to evaluate the shear bond strength (SBS of polycrystalline ceramic brackets (PCB bonded after bleaching treatment using different composite resins and enamel etching times. A total of 144 bovine incisors were randomly divided into two study groups (n = 72, each as follows: G1, enamel bleached with 35% hydrogen peroxide, and G2 (control group, enamel unbleached. After the bleaching treatment, the samples were stored in artificial saliva for 14 days. These groups were further divided into two subgroups (n = 36, each as follows: GA, brackets bonded with Transbond XT (3M and GB, brackets bonded with Filtek Z250 (3M. For each resin used, three different etching times with 37% phosphoric acid (15, 30 and 60 seconds were tested. SBS tests were performed using a universal testing machine (EMIC, and the adhesive remnant index (ARI score was verified. Significant differences among the three experimental conditions and interactions between the groups were observed. The type of composite resin accounted for 24% of the influence on the bond strength, whereas the etching time and bleaching treatment accounted for 14.5% and 10% of the influence on bond strength, respectively. The ARI revealed that the most common area of adhesion failure was at the composite resin-bracket interface. The type of composite resin, etching time and external bleaching significantly influenced the SBS of PCB on enamel, even after 14 days of saliva storage.

  16. The Bond Strength of Composite Resin to Dental Casting Alloys Using an Electro-Chemical Tin Plating System.

    Science.gov (United States)

    1985-06-01

    orthodontic wire (Rocky Mountain Dental Products, Denver, CO) (Figure 4). All surfaces except the one centimeter square faces to be etched were masked with...Miller, A.J. 1962. Inlays, Crowns, and Bridles. An Atlas of Clinical Procedures. Philadelphia, W.B. Saunders Co., p. 127. Mitchem, J.C. and Gronas

  17. Extreme ultraviolet lithography mask etch study and overview

    Science.gov (United States)

    Wu, Banqiu; Kumar, Ajay; Chandrachood, Madhavi; Sabharwal, Amitabh

    2013-04-01

    An overview of extreme ultraviolet lithography (EUVL) mask etch is presented and a EUVL mask etch study was carried out. Today, EUVL implementation has three critical challenges that hinder its adoption: extreme ultraviolet (EUV) source power, resist resolution-line width roughness-sensitivity, and a qualified EUVL mask. The EUVL mask defect challenges result from defects generated during blank preparation, absorber and multilayer deposition processes, as well as patterning, etching and wet clean processes. Stringent control on several performance criteria including critical dimension (CD) uniformity, etch bias, micro-loading, profile control, defect control, and high etch selectivity requirement to capping layer is required during the resist pattern duplication on the underlying absorber layer. EUVL mask absorbers comprise of mainly tantalum-based materials rather than chrome- or MoSi-based materials used in standard optical masks. Compared to the conventional chrome-based absorbers and phase shift materials, tantalum-based absorbers need high ion energy to obtain moderate etch rates. However, high ion energy may lower resist selectivity, and could introduce defects. Current EUVL mask consists of an anti-reflective layer on top of the bulk absorber. Recent studies indicate that a native oxide layer would suffice as an anti-reflective coating layer during the electron beam inspection. The absorber thickness and the material properties are optimized based on optical density targets for the mask as well as electromagnetic field effects and optics requirements of the patterning tools. EUVL mask etch processes are modified according to the structure of the absorber, its material, and thickness. However, etch product volatility is the fundamental requirement. Overlapping lithographic exposure near chip border may require etching through the multilayer, resulting in challenges in profile control and etch selectivity. Optical proximity correction is applied to further

  18. Time-varying wetting behavior on copper wafer treated by wet-etching

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Sheng-Hung; Wu, Chuan-Chang [Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan, ROC (China); Wu, Hsing-Chen [Advanced Technology Materials Inc, Hsinchu 310, Taiwan, ROC (China); Cheng, Shao-Liang [Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan, ROC (China); Sheng, Yu-Jane, E-mail: yjsheng@ntu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan, ROC (China); Tsao, Heng-Kwong, E-mail: hktsao@cc.ncu.edu.tw [Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan, ROC (China)

    2015-06-30

    Graphical abstract: - Highlights: • A thin oxide layer always remains on surfaces of Cu wafers after aqueous etching. • A pure Cu wafer is obtained by the HAc treatment and the water CA is about 45°. • The oxide layer and CA grow with time after the Cu wafer is exposed to air. • Surface roughness and hydrophobicity of pure Cu wafers grow rapidly in vacuum. - Abstract: The wet cleaning process in semiconductor fabrication often involves the immersion of the copper wafer into etching solutions and thereby its surface properties are significantly altered. The wetting behavior of a copper film deposited on silicon wafer is investigated after a short dip in various etching solutions. The etchants include glacial acetic acid and dilute solutions of nitric acid, hydrofluoric acid, and tetramethylammonium hydroxide. It was found that in most cases a thin oxide layer still remains on the surface of as-received Cu wafers when they are subject to etching treatments. However, a pure Cu wafer can be obtained by the glacial acetic acid treatment and its water contact angle (CA) is about 45°. As the pure Cu wafer is placed in the ambient condition, the oxide thickness grows rapidly to the range of 10–20 Å within 3 h and the CA on the hydrophilic surface also rises. In the vacuum, it is surprising to find that the CA and surface roughness of the pure Cu wafer can grow significantly. These interesting results may be attributed to the rearrangement of surface Cu atoms to reduce the surface free energy.

  19. Cosmogenic and implanted radionuclides studied by selective etching of lunar soils

    CERN Document Server

    Jull, A J T; McHargue, L R; Burr, G S; Donahue, D J

    2000-01-01

    We have made new measurements of the concentrations of sup 1 sup 4 C and sup 1 sup 0 Be in lunar surface soils. We discuss the results of these new studies based on different acid etching methods, which provide useful information for future experiments. We also discuss the implications of these results for the production of these radionuclides by galactic and solar cosmic radiation, and the direct implantation of solar-energetic particles into lunar surface material.

  20. Dental biothermophotonics: How photothermal methods are winning the race with X-rays for dental caries diagnostic needs of clinical dentistry

    Science.gov (United States)

    Mandelis, A.; Jeon, R.; Matvienko, A.; Abrams, S. H.; Amaechi, B. T.

    2008-01-01

    Recent trends in biothermophotonics of teeth are presented. The presentation is centered on the development of clinical-level frequency-domain photothermal radiometry and modulated luminescence to address issues associated with the early diagnosis of demineralization caries in human teeth. Biothermophotonic principles and applications to the detection of the carious state in human teeth as embodied by laser photothermal radiometry are presented and further supported by modulated luminescence. The emphasis is on recent developments with regard to abilities of these techniques to diagnose interproximal lesions between teeth, etching with phosphoric acid and with an artificial demineralization gel in order to simulate early demineralization, as well as demineralization and remineralization of dental crown enamel and root dentin. These are lesions which normally go undetected by X-ray radiographs. Comparisons with X rays, Micro-Computed Tomography (μ-CT) and Transverse Micro-Radiography (TMR) are discussed. A theoretical model involving coupled diffuse photon density and thermal-wave fields is developed and applied to frequency scans from demineralized artificial lesions to produce quantitative values for optical and thermophysical parameters of teeth as well as the thickness of the induced lesion.

  1. Dislocation Etching Solutions for Mercury Cadmium Selenide

    Science.gov (United States)

    2014-09-01

    be obtained in order to develop better etching solutions. 13 6. References 1. Brill G, Chen Y, Wijewarnasuriya P. J. Elect. Mater. 2011;40...PJ, Jacobs RN, Markunas JK, Jaime-Vasquez M, Almeida LA, Stoltz AJ, Wijewarnasuriya PS, Brill G, Chen Y, Lee U, Vilela MF, Peterson J, Johnson SM...Elect. Mater. 1995;24:505. 5. Doyle K, Swartz CH, Dinan JH, Myers TH, Brill G, Chen Y, VanMil BL, Wijewarnasuriya P. J. Vac. Sci. Technol. B 2013;31

  2. Dental caries vaccine

    Directory of Open Access Journals (Sweden)

    Shivakumar K

    2009-01-01

    Full Text Available Dental caries is one of the most common diseases in humans. In modern times, it has reached epidemic proportions. Dental caries is an infectious microbiologic disease of the teeth that results in localized dissolution and destruction of the calcified tissue. Dental caries is a mulitifactorial disease, which is caused by host, agent, and environmental factors. The time factor is important for the development and progression of dental caries. A wide group of microorganisms are identified from carious lesions of which S. mutans , Lactobacillus acidophilus , and Actinomyces viscosus are the main pathogenic species involved in the initiation and development of dental caries. In India, surveys done on school children showed caries prevalence of approximately 58%. Surveys among the U.S. population showed an incidence of 45.3% in children and 93.8% in adults with either past or present coronal caries. Huge amounts of money and time are spent in treating dental caries. Hence, the prevention and control of dental caries is the main aim of public health, eventually the ultimate objective of public health is the elimination of the disease itself. Recently, dental caries vaccines have been developed for the prevention of dental caries. These dental caries vaccines are still in the early stages.

  3. What is dental ecology?

    Science.gov (United States)

    Cuozzo, Frank P; Sauther, Michelle L

    2012-06-01

    Teeth have long been used as indicators of primate ecology. Early work focused on the links between dental morphology, diet, and behavior, with more recent years emphasizing dental wear, microstructure, development, and biogeochemistry, to understand primate ecology. Our study of Lemur catta at the Beza Mahafaly Special Reserve, Madagascar, has revealed an unusual pattern of severe tooth wear and frequent tooth loss, primarily the result of consuming a fallback food for which these primates are not dentally adapted. Interpreting these data was only possible by combining our areas of expertise (dental anatomy [FC] and primate ecology [MS]). By integrating theoretical, methodological, and applied aspects of both areas of research, we adopted the term "dental ecology"-defined as the broad study of how teeth respond to the environment. Specifically, we view dental ecology as an interpretive framework using teeth as a vehicle for understanding an organism's ecology, which builds upon earlier work, but creates a new synthesis of anatomy and ecology that is only possible with detailed knowledge of living primates. This framework includes (1) identifying patterns of dental pathology and tooth use-wear, within the context of feeding ecology, behavior, habitat variation, and anthropogenic change, (2) assessing ways in which dental development and biogeochemical signals can reflect habitat, environmental change and/or stress, and (3) how dental microstructure and macro-morphology are adapted to, and reflect feeding ecology. Here we define dental ecology, provide a short summary of the development of this perspective, and place our new work into this context.

  4. Influence of a pulsed CO2 laser operating at 9.4 μm on the surface morphology, reflectivity, and acid resistance of dental enamel below the threshold for melting

    Science.gov (United States)

    Kim, Jin Wan; Lee, Raymond; Chan, Kenneth H.; Jew, Jamison M.; Fried, Daniel

    2017-02-01

    Below the threshold for laser ablation, the mineral phase of enamel is converted into a purer phase hydroxyapatite with increased acid resistance. Studies suggest the possibility of achieving the conversion without visible surface alteration. In this study, changes in the surface morphology, reflectivity, and acid resistance were monitored with varying irradiation intensity. Bovine enamel specimens were irradiated using a CO2 laser operating at 9.4 μm with a Gaussian spatial beam profile-1.6 to 3.1 mm in diameter. After laser treatment, samples were subjected to demineralization to simulate the acidic intraoral conditions of dental decay. The resulting demineralization and erosion were assessed using polarization-sensitive optical coherence tomography, three-dimensional digital microscopy, and polarized light microscopy. Distinct changes in the surface morphology and the degree of inhibition were found within the laser-treated area in accordance with the laser intensity profile. Subtle visual changes were noted below the melting point for enamel that appear to correspond to thresholds for denaturation of the organic phase and thermal decomposition of the mineral phase. There was significant protection from laser irradiation in areas in which the reflectivity was not increased significantly, suggesting that aesthetically sensitive areas of the tooth can be treated for caries prevention.

  5. In vitro analysis of riboflavin-modified, experimental, two-step etch-and-rinse dentin adhesive: Fourier transform infrared spectroscopy and micro-Raman studies

    OpenAIRE

    Daood, Umer; Swee Heng, Chan; Neo Chiew Lian, Jennifer; Fawzy, Amr S

    2014-01-01

    To modify two-step experimental etch-and-rinse dentin adhesive with different concentrations of riboflavin and to study its effect on the bond strength, degree of conversion, along with resin infiltration within the demineralized dentin substrate, an experimental adhesive-system was modified with different concentrations of riboflavin (m/m, 0, 1%, 3%, 5% and 10%). Dentin surfaces were etched with 37% phosphoric acid, bonded with respective adhesives, restored with restorative composite–resin,...

  6. Microleakage of composite resin restoration in cavities prepared by Er,Cr:YSGG laser irradiation and etched bur cavities in primary teeth.

    Science.gov (United States)

    Hossain, Mozammal; Nakamura, Yukio; Yamada, Yoshishige; Murakami, Yoshiko; Matsumoto, Koukichi

    2002-01-01

    In this in vitro study, the surface alterations of enamel and dentin in cavities prepared by Er,Cr:YSGG laser irradiation was investigated by scanning electron microscopy and compared to the microleakage degree after composite resin restoration with etched bur cavities in human primary teeth. The results confirmed that laser cavity surface facilitated a good adhesion with the restorative materials; the acid etch step can be easily avoided with the laser treatment.

  7. Dental hygiene in Slovakia.

    Science.gov (United States)

    Luciak-Donsberger, C; Krizanová, M

    2004-08-01

    This article reports on the development of the dental hygiene profession in Slovakia from a global perspective. The aim is to inform about current developments and to examine, how access to qualified dental hygiene care might be improved and how professional challenges might be met. For an international study on dental hygiene, secondary source data were obtained from members of the House of Delegates of the International Federation of Dental Hygienists (IFDH) or by fax and e-mail from experts involved in the national professional and educational organization of dental hygiene in non-IFDH member countries, such as Slovakia. Responses were followed-up by interviews, e-mail correspondence, visits to international universities, and a review of supporting studies and reference literature. Results show that the introduction of dental hygiene in Slovakia in 1992 was inspired by the delivery of preventive care in Switzerland. Initiating local dentists and dental hygienists strive to attain a high educational level, equitable to that of countries in which dental hygiene has an established tradition of high quality care. Low access to qualified dental hygiene care may be a result of insufficient funding for preventive services, social and cultural lack of awareness of the benefits of preventive care, and of limitations inherent in the legal constraints preventing unsupervised dental hygiene practice. These may be a result of gender politics affecting a female-dominated profession and of a perception that dental hygiene is auxiliary to dental care. International comparison show that of all Eastern European countries, the dental hygiene profession appears most advanced in Slovakia. This is expressed in high evidence-based academic goals, in extensive work with international consultants from the Netherlands and Switzerland, in annual congresses of high professional quality, and in the establishment of a profession, which has not been introduced in all Western EU countries.

  8. Lateral electrochemical etching of III-nitride materials for microfabrication

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jung

    2017-02-28

    Conductivity-selective lateral etching of III-nitride materials is described. Methods and structures for making vertical cavity surface emitting lasers with distributed Bragg reflectors via electrochemical etching are described. Layer-selective, lateral electrochemical etching of multi-layer stacks is employed to form semiconductor/air DBR structures adjacent active multiple quantum well regions of the lasers. The electrochemical etching techniques are suitable for high-volume production of lasers and other III-nitride devices, such as lasers, HEMT transistors, power transistors, MEMs structures, and LEDs.

  9. INCREASING THE PHOTOLUMINESCENCE INTENSITY OF Ge ISLANDS BY CHEMICAL ETCHING

    Institute of Scientific and Technical Information of China (English)

    高斐; 黄昌俊; 黄大定; 李建平; 孔梅影; 曾一平; 李晋闽; 林兰英

    2001-01-01

    Self-assembled Ge islands were grown on Si(100) substrate by Si2H6-Ge molecular beam epitaxy. After beingsubjected to chemical etching, it is found that the photoluminescence from the etched Ge islands became more intense and shifted to the higher-energy side compared to that of the as-deposited Ge islands. This behaviour was explained by the effect of chemical etching on the morphology of the Ge islands. Our results demonstrate that chemical etching can be a way to change the luminescence property of the as-deposited islands.

  10. Ancient DNA analysis of dental calculus.

    Science.gov (United States)

    Weyrich, Laura S; Dobney, Keith; Cooper, Alan

    2015-02-01

    Dental calculus (calcified tartar or plaque) is today widespread on modern human teeth around the world. A combination of soft starchy foods, changing acidity of the oral environment, genetic pre-disposition, and the absence of dental hygiene all lead to the build-up of microorganisms and food debris on the tooth crown, which eventually calcifies through a complex process of mineralisation. Millions of oral microbes are trapped and preserved within this mineralised matrix, including pathogens associated with the oral cavity and airways, masticated food debris, and other types of extraneous particles that enter the mouth. As a result, archaeologists and anthropologists are increasingly using ancient human dental calculus to explore broad aspects of past human diet and health. Most recently, high-throughput DNA sequencing of ancient dental calculus has provided valuable insights into the evolution of the oral microbiome and shed new light on the impacts of some of the major biocultural transitions on human health throughout history and prehistory. Here, we provide a brief historical overview of archaeological dental calculus research, and discuss the current approaches to ancient DNA sampling and sequencing. Novel applications of ancient DNA from dental calculus are discussed, highlighting the considerable scope of this new research field for evolutionary biology and modern medicine.

  11. Fabrication of silicon nanowire arrays by macroscopic galvanic cell-driven metal catalyzed electroless etching in aerated HF solution.

    Science.gov (United States)

    Liu, Lin; Peng, Kui-Qing; Hu, Ya; Wu, Xiao-Ling; Lee, Shuit-Tong

    2014-03-05

    Macroscopic galvanic cell-driven metal catalyzed electroless etching (MCEE) of silicon in aqueous hydrofluoric acid (HF) solution is devised to fabricate silicon nanowire (SiNW) arrays with dissolved oxygen acting as the one and only oxidizing agent. The key aspect of this strategy is the use of a graphite or other noble metal electrode that is electrically coupled with silicon substrate.

  12. A new concept for spatially divided Deep Reactive Ion Etching with ALD-based passivation

    NARCIS (Netherlands)

    Roozeboom, F.; Kniknie, B.J.; Lankhorst, A.M.; Winands, G.; Knaapen, R.; Smets, M.; Poodt, P.W.G.; Dingemans, G.; Keuning, W.; Kessels, W.M.M.

    2012-01-01

    Conventional Deep Reactive Ion Etching (DRIE) is a plasma etch process with alternating half-cycles of 1) Si-etching with SF6 to form gaseous SiFx etch products, and 2) passivation with C4F8 that polymerizes as a protecting fluorocarbon deposit on the sidewalls and bottom of the etched features. In

  13. The wettability between etching solutions and the surface of multicrystalline silicon wafer during metal-assisted chemical etching process

    Science.gov (United States)

    Niu, Y. C.; Liu, Z.; Liu, X. J.; Gao, Y.; Lin, W. L.; Liu, H. T.; Jiang, Y. S.; Ren, X. K.

    2017-01-01

    In order to investigate the wettability of multicrystalline silicon (mc-Si) with the etching solutions during metal-assisted chemical etching process, different surface structures were fabricated on the p-type multi-wire slurry sawn mc-Si wafers, such as as-cut wafers, polished wafers, and wafers etched in different solutions. The contact angles of different etching solutions on the surfaces of the wafers were measured. It was noted that all contact angles of etching solutions were smaller than the corresponding ones of deionized water, but the contact angles of different etching solutions were quite different. Among the contact angles of the etching solutions of AgNO3-HF, H2O2-HF, TMAH and HNO3-HF, the contact angle of TMAH solution was much larger than the others and that of HNO3-HF solution was much smaller. It is suggested that the larger contact angle may lead to an unevenly etching of silicon wafer due to the long retention of big bubbles on the wafers in the etching reaction, which should be paid attention to and overcome.

  14. Admittance spectroscopy of CdTe/CdS solar cells subjected to varied nitric-phosphoric etching conditions.

    OpenAIRE

    2007-01-01

    In this work we investigate the electric and structural properties of CdTe/CdS solar cells subjected to a nitric-phosphoric (NP) acid etching procedure, employed for the formation of a Te-rich layer before back contacting. The etching time is used as the only variable parameter in the study, while admittance spectroscopy is employed for the characterization of the cells' electric properties as well as for the analysis of the defect energy levels. Particular attention was also given to the cha...

  15. Effect of Ceramic Surface Treatments After Machine Grinding on the Biaxial Flexural Strength of Different CAD/CAM Dental Ceramics

    Science.gov (United States)

    Bagheri, Hossein; Aghajani, Farzaneh

    2015-01-01

    Objectives: This study aimed to evaluate the effect of different ceramic surface treatments after machining grinding on the biaxial flexural strength (BFS) of machinable dental ceramics with different crystalline phases. Materials and Methods: Disk-shape specimens (10mm in diameter and 1.3mm in thickness) of machinable ceramic cores (two silica-based and one zirconia-based ceramics) were prepared. Each type of the ceramic surfaces was then randomly treated (n=15) with different treatments as follows: 1) machined finish as control, 2) machined finish and sandblasting with alumina, and 3) machined finish and hydrofluoric acid etching for the leucite and lithium disilicate-based ceramics, and for the zirconia; 1) machined finish and post-sintered as control, 2) machined finish, post-sintered, and sandblasting, and 3) machined finish, post-sintered, and Nd;YAG laser irradiation. The BFS were measured in a universal testing machine. Data based were analyzed by ANOVA and Tukey’s multiple comparisons post-hoc test (α=0.05). Results: The mean BFS of machined finish only surfaces for leucite ceramic was significantly higher than that of sandblasted (P=0.001) and acid etched surfaces (P=0.005). A significantly lower BFS was found after sandblasting for lithium disilicate compared with that of other groups (P<0.05). Sandblasting significantly increased the BFS for the zirconia (P<0.05), but the BFS was significantly decreased after laser irradiation (P<0.05). Conclusions: The BFS of the machinable ceramics was affected by the type of ceramic material and surface treatment method. Sandblasting with alumina was detrimental to the strength of only silica-based ceramics. Nd:YAG laser irradiation may lead to substantial strength degradation of zirconia. PMID:27148372

  16. Anisotropy of synthetic diamond in catalytic etching using iron powder

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Junsha [College of Materials Science and Engineering, Hunan University, Hunan 410082 (China); Department of Mechanical Engineering, Keio University, Yokohama 223-8522 (Japan); Wan, Long, E-mail: wanlong1799@163.com [College of Materials Science and Engineering, Hunan University, Hunan 410082 (China); Chen, Jing [College of Materials Science and Engineering, Hunan University, Hunan 410082 (China); Yan, Jiwang [Department of Mechanical Engineering, Keio University, Yokohama 223-8522 (Japan)

    2015-08-15

    Highlights: • Synthetic diamond crystallites were etched using iron without requiring hydrogen. • The effect of temperature on the etching behaviour was demonstrated. • The anisotropy of etching on different crystal planes was investigated. • The extent of etching on diamond surface was examined quantitatively. • A schematic model for diamond etching by iron is being proposed. - Abstract: This paper demonstrated a novel technique for catalytic etching of synthetic diamond crystallites using iron (Fe) powder without flowing gas. The effect of temperature on the etching behaviour on different crystal planes of diamond was investigated. The surface morphology and surface roughness of the processed diamond were examined by scanning electron microscope (SEM) and laser-probe surface profiling. In addition, the material composition of the Fe-treated diamond was characterized using micro-Raman spectroscopy and the distribution of chemical elements and structural changes on Fe-loaded diamond surfaces were analyzed by energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), respectively. Results showed that at the same temperature the {1 0 0} plane was etched faster than the {1 1 1} plane, and that the etching rate of both {1 0 0} and {1 1 1} plane increased with temperature. The etch pits on {1 0 0} plane were reversed pyramid with flat {1 1 1} walls, while the etch holes on {1 1 1} plane were characterized with flat bottom. It was also demonstrated that graphitization of diamond and subsequent carbon diffusion in molten iron were two main factors resulting in the removal of carbon from the diamond surface.

  17. Dental Implant Systems

    Directory of Open Access Journals (Sweden)

    Yoshiki Oshida

    2010-04-01

    Full Text Available Among various dental materials and their successful applications, a dental implant is a good example of the integrated system of science and technology involved in multiple disciplines including surface chemistry and physics, biomechanics, from macro-scale to nano-scale manufacturing technologies and surface engineering. As many other dental materials and devices, there are crucial requirements taken upon on dental implants systems, since surface of dental implants is directly in contact with vital hard/soft tissue and is subjected to chemical as well as mechanical bio-environments. Such requirements should, at least, include biological compatibility, mechanical compatibility, and morphological compatibility to surrounding vital tissues. In this review, based on carefully selected about 500 published articles, these requirements plus MRI compatibility are firstly reviewed, followed by surface texturing methods in details. Normally dental implants are placed to lost tooth/teeth location(s in adult patients whose skeleton and bony growth have already completed. However, there are some controversial issues for placing dental implants in growing patients. This point has been, in most of dental articles, overlooked. This review, therefore, throws a deliberate sight on this point. Concluding this review, we are proposing a novel implant system that integrates materials science and up-dated surface technology to improve dental implant systems exhibiting bio- and mechano-functionalities.

  18. Biocompatibility of dental alloys

    Energy Technology Data Exchange (ETDEWEB)

    Braemer, W. [Heraeus Kulzer GmbH and Co. KG, Hanau (Germany)

    2001-10-01

    Modern dental alloys have been used for 50 years to produce prosthetic dental restorations. Generally, the crowns and frames of a prosthesis are prepared in dental alloys, and then veneered by feldspar ceramics or composites. In use, the alloys are exposed to the corrosive influence of saliva and bacteria. Metallic dental materials can be classified as precious and non-precious alloys. Precious alloys consist of gold, platinum, and small amounts of non-precious components such as copper, tin, or zinc. The non-precious alloys are based on either nickel or cobalt, alloyed with chrome, molybdenum, manganese, etc. Titanium is used as Grade 2 quality for dental purposes. As well as the dental casting alloys, high purity electroplated gold (99.8 wt.-%) is used in dental technology. This review discusses the corrosion behavior of metallic dental materials with saliva in ''in vitro'' tests and the influence of alloy components on bacteria (Lactobacillus casei and Streptococcus mutans). The test results show that alloys with high gold content, cobalt-based alloys, titanium, and electroplated gold are suitable for use as dental materials. (orig.)

  19. Growing and Etching MoS2 on Carbon Nanotube Film for Enhanced Electrochemical Performance

    Directory of Open Access Journals (Sweden)

    Weiyu Xu

    2016-09-01

    Full Text Available In this work we directly synthesized molybdenum disulfide (MoS2 nanosheets on carbon nanotube film (MoS2@CNT via a two-step chemical vapor deposition method (CVD. By etching the obtained MoS2@CNT into 10% wt HNO3, the morphology of MoS2 decorated on CNT bundles was modulated, resulting in more catalytic active MoS2 edges being exposed for significantly enhanced electrochemical performance. Our results revealed that an 8 h acid etching sample exhibited the best performance for the oxygen evolution reaction, i.e., the current density reached 10 mA/cm2 under 375 mV over-potential, and the tafel slope was as low as 94 mV/dec. The enhanced behavior was mainly originated from the more catalytic sites in MoS2 induced by the acid etching treatment and the higher conductivity from the supporting CNT films. Our study provides a new route to produce two-dimensional layers on CNT films with tunable morphology, and thus may open a window for exploring its promising applications in the fields of catalytic-, electronic-, and electrochemical-related fields.

  20. Optical and Electrical Performance of ZnO Films Textured by Chemical Etching

    Directory of Open Access Journals (Sweden)

    Shiuh-Chuan HER

    2015-11-01

    Full Text Available Zinc oxide (ZnO films were prepared by radio frequency (RF magnetron sputtering on the glass substrate as transparent conductive oxide films. For silicon solar cells, a proper surface texture is essential to introduce light scattering and subsequent light trapping to enhance the current generation. In this study, the magnetron-sputtered ZnO films were textured by wet-chemical etching in diluted hydrochloric acid (HCl for better light scattering. The diffuse transmittance of the surface textured ZnO films was measured to evaluate the light scattering. The influence of hydrochloric acid concentration on the morphology, optical and electrical properties of the surface-textured ZnO film was investigated. The ZnO film etched in 0.05M HCl solution for 30 s exhibited average diffuse transmittance in the visible wavelength range of 9.52 % and good resistivity of 1.10 x 10-3 W×cm while the as-deposited ZnO film had average diffuse transmittance of 0.51 % and relatively high resistivity of 5.84 x 10-2 W×cm. Experimental results illustrated that the optical and electrical performance of ZnO films can be significantly improved by introducing the surface texture through the wet-chemical etching process.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9624

  1. Electronegativity-dependent tin etching from thin films

    NARCIS (Netherlands)

    Pachecka, M.; Sturm, J.M.; Kruijs, van de R.W.E.; Lee, C.J.; Bijkerk, F.

    2016-01-01

    The influence of a thin film substrate material on the etching of a thin layer of deposited tin (Sn) by hydrogen radicals was studied. The amount of remaining Sn was quantified for materials that cover a range of electronegativities. We show that, for metals, etching depends on the relative electron

  2. Reactive ion etching of quartz and Pyrex for microelectronic applications

    Science.gov (United States)

    Zeze, D. A.; Forrest, R. D.; Carey, J. D.; Cox, D. C.; Robertson, I. D.; Weiss, B. L.; Silva, S. R. P.

    2002-10-01

    The reactive ion etching of quartz and Pyrex substrates was carried out using CF4/Ar and CF4/O2 gas mixtures in a combined radio frequency (rf)/microwave (μw) plasma. It was observed that the etch rate and the surface morphology of the etched regions depended on the gas mixture (CF4/Ar or CF4/O2), the relative concentration of CF4 in the gas mixture, the rf power (and the associated self-induced bias) and microwave power. An etch rate of 95 nm/min for quartz was achieved. For samples covered with a thin metal layer, ex situ high resolution scanning electron microscopy and atomic force microscopy imaging indicated that, during etching, surface roughness is produced on the surface beneath the thin metallic mask. Near vertical sidewalls with a taper angle greater than 80° and smooth etched surfaces at the nanometric scale were fabricated by carefully controlling the etching parameters and the masking technique. A simulation of the electrostatic field distribution was carried out to understand the etching process using these masks for the fabrication of high definition features.

  3. Chronic fluoride toxicity: dental fluorosis.

    Science.gov (United States)

    Denbesten, Pamela; Li, Wu

    2011-01-01

    Dental fluorosis occurs as a result of excess fluoride ingestion during tooth formation. Enamel fluorosis and primary dentin fluorosis can only occur when teeth are forming, and therefore fluoride exposure (as it relates to dental fluorosis) occurs during childhood. In the permanent dentition, this would begin with the lower incisors, which complete mineralization at approximately 2-3 years of age, and end after mineralization of the third molars. The white opaque appearance of fluorosed enamel is caused by a hypomineralized enamel subsurface. With more severe dental fluorosis, pitting and a loss of the enamel surface occurs, leading to secondary staining (appearing as a brown color). Many of the changes caused by fluoride are related to cell/matrix interactions as the teeth are forming. At the early maturation stage, the relative quantity of amelogenin protein is increased in fluorosed enamel in a dose-related manner. This appears to result from a delay in the removal of amelogenins as the enamel matures. In vitro, when fluoride is incorporated into the mineral, more protein binds to the forming mineral, and protein removal by proteinases is delayed. This suggests that altered protein/mineral interactions are in part responsible for retention of amelogenins and the resultant hypomineralization that occurs in fluorosed enamel. Fluoride also appears to enhance mineral precipitation in forming teeth, resulting in hypermineralized bands of enamel, which are then followed by hypomineralized bands. Enhanced mineral precipitation with local increases in matrix acidity may affect maturation stage ameloblast modulation, potentially explaining the dose-related decrease in cycles of ameloblast modulation from ruffle-ended to smooth-ended cells that occur with fluoride exposure in rodents. Specific cellular effects of fluoride have been implicated, but more research is needed to determine which of these changes are relevant to the formation of fluorosed teeth. As further

  4. The effect of exposure duration of self etch dentin bonding on the toxicity of human gingival fibroblast of cell culture

    Directory of Open Access Journals (Sweden)

    Sri Lestari

    2008-06-01

    Full Text Available Self etch dentin bonding created to make light easily activate the application of composite resin on tooth surface. The monomer content has acid effect that could irritate tooth pulp. The purpose of this study was to evaluate the effect of light exposure duration of self etch dentin bonding on toxicity of human gingival fibroblast of cell culture by MTT assay. Self etch dentin bonding was used as on experimental unit and the sample was exposed by visible light curing in different duration: 10, 20, 30 seconds and immerged in artificial saliva in pH 7 for 24 hours. 100 µl artificial saliva was exposed to human gingival fibroblast of cell culture 20.000 cells/100 µl RPMI for 24 hours. Toxicity was evaluated by MTT assay, optical density was measured using 550 nm spectrophotometer. The data was analyzed using Kruskal Wallis in 5% degree of significance. The result showed that increasing exposure duration (10, 20, 30 seconds of self etch dentin bonding will reduce the toxicity of human gingival fibroblast of cell culture. It is concluded that 30 seconds-exposure of self etch dentin bonding will reduce the toxicity of human gingival fibroblast of cell culture.

  5. Comparative scanning electron microscopic study of the effect of different dental conditioners on dentin micromorphology.

    Science.gov (United States)

    Susin, Alexandre Henrique; Alves, Luana Severo; Melo, Gliciana Piovesan de; Lenzi, Tathiane Larissa

    2008-01-01

    This study evaluated comparatively by scanning electron microscopy (SEM) the effect of different dental conditioners on dentin micromorphology, when used according to the same protocol. Forty dentin sticks were obtained from 20 caries-free third human molars and were assigned to 4 groups corresponding to 3 conditioners (phosphoric acid 37%, Clearfil SE Bond and iBond) and an untreated control group. After application of the conditioners, the specimens were immersed in 50% ethanol solution during 10 s, chemically fixed and dehydrated to prepare them to SEM analysis. In the control group, dentin surface was completely covered by smear layer and all dentinal tubules were occluded. In the phosphoric acid-etched group, dentin surface was completely clean and presented exposed dentinal tubule openings; this was the only group in which the tubules exhibited the funnel-shaped aspect. In the groups conditioned with Clearfil SE Bond primer and iBond, which are less acidic than phosphoric acid, tubule openings were occluded or partially occluded, though smear layer removal was observed. SE Bond was more efficient in removing the smear layer than iBond. In the Clearfil SE Bond group, the cuff-like aspect of peritubular dentin was more evident. It may be concluded all tested conditioners were able to change dentin morphology. However, it cannot be stated that the agent aggressiveness was the only cause of the micromorphological alterations because a single morphological pattern was not established for each group, but rather an association of different aspects, according to the aggressiveness of the tested conditioner.

  6. Comparative scanning electron microscopic study of the effect of different dental conditioners on dentin micromorphology

    Directory of Open Access Journals (Sweden)

    Alexandre Henrique Susin

    2008-04-01

    Full Text Available This study evaluated comparatively by scanning electron microscopy (SEM the effect of different dental conditioners on dentin micromorphology, when used according to the same protocol. Forty dentin sticks were obtained from 20 caries-free third human molars and were assigned to 4 groups corresponding to 3 conditioners (phosphoric acid 37%, Clearfil SE Bond and iBond and an untreated control group. After application of the conditioners, the specimens were immersed in 50% ethanol solution during 10 s, chemically fixed and dehydrated to prepare them to SEM analysis. In the control group, dentin surface was completely covered by smear layer and all dentinal tubules were occluded. In the phosphoric acid-etched group, dentin surface was completely clean and presented exposed dentinal tubule openings; this was the only group in which the tubules exhibited the funnel-shaped aspect. In the groups conditioned with Clearfil SE Bond primer and iBond, which are less acidic than phosphoric acid, tubule openings were occluded or partially occluded, though smear layer removal was observed. SE Bond was more efficient in removing the smear layer than iBond. In the Clearfil SE Bond group, the cuff-like aspect of peritubular dentin was more evident. It may be concluded all tested conditioners were able to change dentin morphology. However, it cannot be stated that the agent aggressiveness was the only cause of the micromorphological alterations because a single morphological pattern was not established for each group, but rather an association of different aspects, according to the aggressiveness of the tested conditioner.

  7. Fast pore etching on high resistivity n-type silicon via photoelectrochemistry

    Institute of Scientific and Technical Information of China (English)

    Bao Xiao-Qing; Ge Dao-Han; Zhang Sheng; Li Jin-Peng; Zhou Ping; Jiao Ji-Wei; Wang Yue-Lin

    2009-01-01

    In this paper, five factors, namely the HF (hydrofluoric acid) concentration, field strength, illumination intensity as well as the oxidizing-power and conductivity of electrolytes were found to strongly affect the fast pore etching. The oxidizing power of aqueous HF electrolyte of different concentrations was especially measured and analysed. A positive correlation between optimal bias and HF concentration was generally observed and the relationship was semi-quantitatively interpreted. Pore density notably increased with enhanced HF-concentration or bias even on patterned substrates where 2D (two-dimensional) nuclei were densely pre-textured. The etch rate can reach 400μm/h and the aspect ratio of pores can be readily driven up to 250.

  8. Chemical Composition of Nanoporous Layer Formed by Electrochemical Etching of p-Type GaAs

    Science.gov (United States)

    Bioud, Youcef A.; Boucherif, Abderraouf; Belarouci, Ali; Paradis, Etienne; Drouin, Dominique; Arès, Richard

    2016-10-01

    We have performed a detailed characterization study of electrochemically etched p-type GaAs in a hydrofluoric acid-based electrolyte. The samples were investigated and characterized through cathodoluminescence (CL), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). It was found that after electrochemical etching, the porous layer showed a major decrease in the CL intensity and a change in chemical composition and in the crystalline phase. Contrary to previous reports on p-GaAs porosification, which stated that the formed layer is composed of porous GaAs, we report evidence that the porous layer is in fact mainly constituted of porous As2O3. Finally, a qualitative model is proposed to explain the porous As2O3 layer formation on p-GaAs substrate.

  9. Fabrication of honeycomb texture on poly-Si by laser interference and chemical etching

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Bogeum; Lee, Myeongkyu, E-mail: myeong@yonsei.ac.kr

    2013-11-01

    In this paper, we present a laser-interference method to fabricate honeycomb textures on poly-Si wafer for reflection reduction. When exposed to three interfering pulsed laser beams at 532 nm, the Si surface was periodically melted in accordance with the interference pattern. As a result, concave holes were generated on the surface because the melted material overflowed and condensed at the periphery. Subsequent acid etching revealed uniform and clean honeycomb textures. The texture depth could be controlled by varying the irradiation condition and a minimum reflectance of 10% was obtained. Transmission electron microscopy analysis showed that no irradiation-induced damage remained after etching. This approach can be a cost-effective alternative to lithographic processes for fabricating high-efficiency poly-Si solar cells.

  10. Education About Dental Hygienists' Roles in Public Dental Prevention Programs: Dental and Dental Hygiene Students' and Faculty Members' and Dental Hygienists' Perspectives.

    Science.gov (United States)

    Pervez, Anushey; Kinney, Janet S; Gwozdek, Anne; Farrell, Christine M; Inglehart, Marita R

    2016-09-01

    In 2005, Public Act No. 161 (PA 161) was passed in Michigan, allowing dental hygienists to practice in approved public dental prevention programs to provide services for underserved populations while utilizing a collaborative agreement with a supervising dentist. The aims of this study were to assess how well dental and dental hygiene students and faculty members and practicing dental hygienists have been educated about PA 161, what attitudes and knowledge about the act they have, and how interested they are in additional education about it. University of Michigan dental and dental hygiene students and faculty members, students in other Michigan dental hygiene programs, and dental hygienists in the state were surveyed. Respondents (response rate) were 160 dental students (50%), 63 dental hygiene students (82%), 30 dental faculty members (26%), and 12 dental hygiene faculty members (52%) at the University of Michigan; 143 dental hygiene students in other programs (20%); and 95 members of the Michigan Dental Hygienists' Association (10%). The results showed that the dental students were less educated about PA 161 than the dental hygiene students, and the dental faculty members were less informed than the dental hygiene faculty members and dental hygienists. Responding dental hygiene faculty members and dental hygienists had more positive attitudes about PA 161 than did the students and dental faculty members. Most of the dental hygiene faculty members and dental hygienists knew a person providing services in a PA 161 program. Most dental hygiene students, faculty members, and dental hygienists wanted more education about PA 161. Overall, the better educated about the program the respondents were, the more positive their attitudes, and the more interested they were in learning more.

  11. Silicon nanowire photodetectors made by metal-assisted chemical etching

    Science.gov (United States)

    Xu, Ying; Ni, Chuan; Sarangan, Andrew

    2016-09-01

    Silicon nanowires have unique optical effects, and have potential applications in photodetectors. They can exhibit simple optical effects such as anti-reflection, but can also produce quantum confined effects. In this work, we have fabricated silicon photodetectors, and then post-processed them by etching nanowires on the incident surface. These nanowires were produced by a wet-chemical etching process known as the metal-assisted-chemical etching, abbreviated as MACE. N-type silicon substrates were doped by thermal diffusion from a solid ceramic source, followed by etching, patterning and contact metallization. The detectors were first tested for functionality and optical performance. The nanowires were then made by depositing an ultra-thin film of gold below its percolation thickness to produce an interconnected porous film. This was then used as a template to etch high aspect ratio nanowires into the face of the detectors with a HF:H2O2 mixture.

  12. Composition/bandgap selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, C.I.H.; Dishman, J.L.

    1985-10-11

    Disclosed is a method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg/sub 1/ in the presence of a second semiconductor material of a different composition and direct bandgap Eg/sub 2/, wherein Eg/sub 2/ > Eg/sub 1/, said second semiconductor material substantially not being etched during said method. The method comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg/sub 1/ but less than Eg/sub 2/, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

  13. Composition/bandgap selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, Carol I. H. (Edgewood, NM); Dishman, James L. (Albuquerque, NM)

    1987-01-01

    A method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg.sub.1 in the presence of a second semiconductor material of a different composition and direct bandgap Eg.sub.2, wherein Eg.sub.2 >Eg.sub.1, said second semiconductor material substantially not being etched during said method, comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg.sub.1 but less than Eg.sub.2, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

  14. Composition/bandgap selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, C.I.H.; Dishman, J.L.

    1987-03-10

    A method is described of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap E/sub g1/ in the presence of a second semiconductor material of a different composition and direct bandgap E/sub g2/, wherein E/sub g2/>E/sub g1/. The second semiconductor material is not substantially etched during the method, comprising subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where the etchant would be ineffective for chemical etching of either material where the photons are not present, the photons being of an energy greater than E/sub g1/ but less than E/sub g2/, whereby the first semiconductor material is photochemically etched and the second material is substantially not etched.

  15. Optimize Etching Based Single Mode Fiber Optic Temperature Sensor

    Directory of Open Access Journals (Sweden)

    Ajay Kumar

    2014-02-01

    Full Text Available This paper presents a description of etching process for fabrication single mode optical fiber sensors. The process of fabrication demonstrates an optimized etching based method to fabricate single mode fiber (SMF optic sensors in specified constant time and temperature. We propose a single mode optical fiber based temperature sensor, where the temperature sensing region is obtained by etching its cladding diameter over small length to a critical value. It is observed that the light transmission through etched fiber at 1550 nm wavelength optical source becomes highly temperature sensitive, compared to the temperature insensitive behavior observed in un-etched fiber for the range on 30ºC to 100ºC at 1550 nm. The sensor response under temperature cycling is repeatable and, proposed to be useful for low frequency analogue signal transmission over optical fiber by means of inline thermal modulation approach.

  16. Dental implant surface treatments for osseointegration improvement: presentation and comparisonof methods

    Directory of Open Access Journals (Sweden)

    Faidra KAPOPOULOU

    2014-08-01

    Full Text Available The growing use of dental implants and the increase in requirements directed scientists to search for the implant surface which will ensure the greater bone to implant contact (BIC. Nowadays, implants are acid- etched (HCl, H 2 S Ο 4 promoting the osteoconductive ac- tivity or are grit-blasted with alumina particles, titanium oxide or calcium phosphates or finally they undergo dual treatment (combination of the two previous methods, which seems to have the better results as a method until now. Anodization is another method of treating the tita- nium implant surface and increased osseointegration is reported for implants coated with hydroxyapatite or ti- tanium plasma. The use of fluoride or wettability of im- plant surface in saline solution are also methods which have been used for treating the implant surface with low rates of osseointegration. Finally, new techniques made their appearance such as the use of laser, the use of drugs and specifically those of bisphosphonates and the use of BMPs. The last methods are very promising and their re- sults are still under research.

  17. Thermal neutron dosimetry using electrochemical etching

    Energy Technology Data Exchange (ETDEWEB)

    Su, S.J.; Sanders, M.E.; Morgan, K.Z.

    1979-07-10

    This study demonstrates the feasibility of using high LET particle radiators to determine the thermal neutron dose by reaction particle registration in low background polycarbonate foils using electrochemical etching. When used in conjunction with the already proven fast neutron recoil particle track registration technique, a viable fast and thermal neutron dosimeter is realized with the advantages of being: non-fading, insensitive to low LET radiation reactions, inexpensive in both processing and materials, useable over a wide dose range, a permanant record and good reproducibility, highly sensitive, and tissue equivalent and a dose equivalent response over a wide range. Most importantly, it finally provides a simple and reliable dosimeter for both the fast and thermal neutron components.

  18. Dental Charting. Student's Manual.

    Science.gov (United States)

    Weaver, Trudy Karlene; Apfel, Maura

    This manual is part of a series dealing with skills and information needed by students in dental assisting. The individualized student materials are suitable for classroom, laboratory, or cooperative training programs. This student manual contains four units covering the following topics: dental anatomical terminology; tooth numbering systems;…

  19. Adhesion of indirect MOD resin composite inlays luted with self-adhesive and self-etching resin cements.

    Science.gov (United States)

    Inukai, T; Abe, T; Ito, Y; Pilecki, P; Wilson, R F; Watson, T F; Foxton, R M

    2012-01-01

    This study investigated the effect of loading on the bond strength to dentin and microleakage of MOD indirect composite restorations bonded with self-adhesive and self-etching resin cements with or without acid etching of the proximal enamel margins. Class II MOD cavities were prepared in 48 molar teeth into dentin and divided into three groups of 16 teeth. Impressions were taken and indirect composite inlays fabricated (Estenia C & B). The enamel margins of the proximal boxes of half the specimens were phosphoric acid etched, and the inlays were cemented with one of three cements (Panavia F 2.0, SA Cement, or Rely X Unicem). After luting, eight teeth in each cement group were mechanically loaded at 2.5 cycles/s for 250,000 cycles. Unloaded teeth acted as controls. Teeth were stored in Rhodamine B solution for 24 hours, sectioned buccolingually at the proximal boxes to examine microleakage using confocal microscopy, and further sectioned for μTBS testing of the resin-dentin interface. Analysis of variance was performed to assess the effect of loading and acid etching on microleakage and bond strength. Acid etching had no effect on microleakage. No significant difference in the dentin bond strengths between the three cements existed after loading. Panavia F 2.0 exhibited a significant reduction in bond strength. With regard to microleakage at the proximal boxes, loading had no effect on dye penetration at the cavity floor. However, at the axial walls, loading had a significant deleterious effect on Panavia F 2.0. No difference in microleakage existed between the three cements at both sites before and after loading. In conclusion, the two tested self-adhesive cements exhibited similar bond strengths before and after loading to the self-etching resin cement. Loading reduced dentin bond strengths and increased microleakage at the resin-dentin interface. However, acid etching of the enamel margins had no significant effect on microleakage in the approximal regions of

  20. Anodic etching of GaN based film with a strong phase-separated InGaN/GaN layer: Mechanism and properties

    Science.gov (United States)

    Gao, Qingxue; Liu, Rong; Xiao, Hongdi; Cao, Dezhong; Liu, Jianqiang; Ma, Jin

    2016-11-01

    A strong phase-separated InGaN/GaN layer, which consists of multiple quantum wells (MQW) and superlattices (SL) layers and can produce a blue wavelength spectrum, has been grown on n-GaN thin film, and then fabricated into nanoporous structures by electrochemical etching method in oxalic acid. Scanning electron microscopy (SEM) technique reveals that the etching voltage of 8 V leads to a vertically aligned nanoporous structure, whereas the films etched at 15 V show branching pores within the n-GaN layer. Due to the low doping concentration of barriers (GaN layers) in the InGaN/GaN layer, we observed a record-low rate of etching (partial relaxation of compressive stress due to the increased light-extracting surface area and light-guiding effect. Such a compressive stress relaxation can be further confirmed by Raman spectra.

  1. Formation of Micro- and Nanostructures on the Nanotitanium Surface by Chemical Etching and Deposition of Titania Films by Atomic Layer Deposition (ALD

    Directory of Open Access Journals (Sweden)

    Denis V. Nazarov

    2015-12-01

    Full Text Available In this study, an integrated approach was used for the preparation of a nanotitanium-based bioactive material. The integrated approach included three methods: severe plastic deformation (SPD, chemical etching and atomic layer deposition (ALD. For the first time, it was experimentally shown that the nature of the etching medium (acidic or basic Piranha solutions and the etching time have a significant qualitative impact on the nanotitanium surface structure both at the nano- and microscale. The etched samples were coated with crystalline biocompatible TiO2 films with a thickness of 20 nm by Atomic Layer Deposition (ALD. Comparative study of the adhesive and spreading properties of human osteoblasts MG-63 has demonstrated that presence of nano- and microscale structures and crystalline titanium oxide on the surface of nanotitanium improve bioactive properties of the material.

  2. E-beam inspection of EUV mask defects: To etch or not to etch?

    Science.gov (United States)

    Bonam, Ravi; Tien, Hung-Yu; Park, Chanro; Halle, Scott; Wang, Fei; Corliss, Daniel; Fang, Wei; Jau, Jack

    2014-04-01

    EUV Lithography is aimed to be inserted into mainstream production for sub-20nm pattern fabrication. Unlike conventional optical lithography, frequent defectivity monitors (adders, repeaters etc.) are required in EUV lithography. Due to sub-20nm pattern and defect dimensions e-beam inspection of critical pattern areas is essential for yield monitor. In previous work we showed sub-10nm defect detection sensitivity1 on patterned resist wafers. In this work we report 8-10× improvement in scan rates of etched patterns compared to resist patterns without loss in defect detection sensitivity. We observed good etch transfer of sub-10nm resist features. A combination of smart scan strategies with improved etched pattern scan rates can further improve throughput of e-beam inspection. An EUV programmed defect mask with Line/Space, Contact patterns was used to evaluate printability of defects and defect detection (Die-Die and Die-Database) capability of the e-beam inspection tool. Defect inspection tool parameters such as averaging, threshold value were varied to assess its detection capability and were compared to previously obtained results on resist patterns.

  3. Evaluation of an experimental dental porcelain.

    Science.gov (United States)

    Hamouda, Ibrahim M; El-Waseffy, Noha A; Hasan, Ahmed M; El-Falal, Abeer A

    2010-11-01

    The aim of this study was to evaluate fracture toughness, hardness, ceramic/metal bond strength and microstructure of experimental dental porcelain and compare it with commercial type. Specimens of specific dimensions were prepared. Fracture toughness was assessed by a three-point bending test. The Vickers hardness was measured using a microhardness tester. The ceramometal bond strength was measured using a universal testing machine. The load was applied at the porcelain/metal interface via a chisel edged blade with a crosshead speed of 2.0 mm/min until fracture. The polished specimens of dental porcelain were chemically etched and the microstructure was analyzed with a scanning electron microscope. The results showed comparable fracture toughness and bond strength for both materials, while the experimental porcelain exhibited higher hardness. The experimental porcelain showed uniform cohesive failure while the commercial type showed mixed mode of failure. The microstructure of the experimental porcelain was tetragonal leucite crystals dispersed randomly in a glass matrix. The leucite crystals exist in two forms, acicular and rod like structures. It was concluded that the experimental porcelain has adequate fracture toughness and ceramic/metal bond strength that can resist the rapid crack propagation and its consequent catastrophic failure, which indicates a material serviceability in the oral cavity.

  4. Optimized condition for etching fused-silica phase gratings with inductively coupled plasma technology.

    Science.gov (United States)

    Wang, Shunquan; Zhou, Changhe; Ru, Huayi; Zhang, Yanyan

    2005-07-20

    Polymer deposition is a serious problem associated with the etching of fused silica by use of inductively coupled plasma (ICP) technology, and it usually prevents further etching. We report an optimized etching condition under which no polymer deposition will occur for etching fused silica with ICP technology. Under the optimized etching condition, surfaces of the fabricated fused silica gratings are smooth and clean. Etch rate of fused silica is relatively high, and it demonstrates a linear relation between etched depth and working time. Results of the diffraction of gratings fabricated under the optimized etching condition match theoretical results well.

  5. Detection of Common Dental Diseases by Dental Hygiene-Therapists

    OpenAIRE

    Macey, Richard John

    2016-01-01

    Thesis submitted to the University of Manchester by Richard Macey for the Degree of Doctor of Philosophy entitled “Detection of Common Dental Diseases by Dental Hygiene-Therapists”, February 2016.Many adult patients that attend NHS dental practices on a regular basis are asymptomatic and do not need any further treatment other than a routine dental examination (“check-up”). As the oral health of the adult population is predicted to improve further, using the General Dental Practitioner to und...

  6. Health Instruction Packages: Permanent Teeth, Dental Deposits, and Dental Instruments. Dientes Permanentes, Depositos Dentales y Instrumentos Dentales.

    Science.gov (United States)

    Lind, Patricia; Germano, Catherine

    These five learning modules use text interspersed with illustrations and reinforcement exercises to instruct dental aide and dental hygiene students about jaw bones and gums, dental deposits, and dental instruments. The first four modules were prepared by Patricia Lind in both Spanish and English. "The Gum and Bone of Permanent Teeth"…

  7. In vitro and in vivo studies of ultrafine-grain Ti as dental implant material processed by ECAP

    Energy Technology Data Exchange (ETDEWEB)

    An, Baili; Li, Zhirui; Diao, Xiaoou [State Key Laboratory of Military Stomatology, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi' an 710032 (China); National Clinical Research Center for Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi' an 710032 (China); Shannxi Key Laboratory of Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi' an 710032 (China); Xin, Haitao, E-mail: xhthmj@fmmu.edu.cn [State Key Laboratory of Military Stomatology, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi' an 710032 (China); National Clinical Research Center for Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi' an 710032 (China); Shannxi Key Laboratory of Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi' an 710032 (China); Zhang, Qiang; Jia, Xiaorui; Wu, Yulu; Li, Kai [State Key Laboratory of Military Stomatology, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi' an 710032 (China); National Clinical Research Center for Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi' an 710032 (China); Shannxi Key Laboratory of Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi' an 710032 (China); Guo, Yazhou [School of Aeronautics, Northwestern Polytechnical University, Xi' an 710032 (China)

    2016-10-01

    The aim of this study was to investigate the surface characterization of ultrafine-grain pure titanium (UFG-Ti) after sandblasting and acid-etching (SLA) and to evaluate its biocompatibility as dental implant material in vitro and in vivo. UFG-Ti was produced by equal channel angular pressing (ECAP) using commercially pure titanium (CP-Ti). Microstructure and yield strength were investigated. The morphology, wettability and roughness of the specimens were analyzed after they were modified by SLA. MC3T3-E1 osteoblasts were seeded onto the specimens to evaluate its biocompatibility in vitro. For the in vivo study, UFG-Ti implants after SLA were embedded into the femurs of New Zealand rabbits. Osseointegration was investigated though micro-CT analysis, histological assessment and pull-out test. The control group was CP-Ti. UFG-Ti with enhanced mechanical properties was produced by four passes of ECAP in B{sub C} route at room temperature. After SLA modification, the hierarchical porous structure on its surface exhibited excellent wettability. The adhesion, proliferation and viability of cells cultured on the UFG-Ti were superior to that of CP-Ti. In the in vivo study, favorable osseointegration occurred between the implant and bone in CP and UFG-Ti groups. The combination intensity of UF- Ti with bone was higher according to the pull-out test. This study supports the claim that UFG-Ti has grain refinement with outstanding mechanical properties and, with its excellent biocompatibility, has potential for use as dental implant material. - Highlights: • Yield strength and Vickers hardness of Ti are improved significantly after it is grain-refined by ECAP process. • The hierarchical micro-porous structure with superior wettability could be formed on the surface of ECAP Ti after SLA. • The results in vitro exhibited excellent cell biocompatibility of UFG-Ti after sandblasting and acid-etching. • The osseointegration between UFG-Ti implant and surrounding bone could

  8. Particle precipitation in connection with KOH etching of silicon

    DEFF Research Database (Denmark)

    Nielsen, Christian Bergenstof; Christensen, Carsten; Pedersen, Casper

    2004-01-01

    This paper considers the precipitation of iron oxide particles in connection with the KOH etching of cavities in silicon wafers. The findings presented in this paper suggest that the source to the particles is the KOH pellets used for making the etching solution. Experiments show that the precipi...... of the change in free energy of adsorption, the Pourbaix diagram, the electrochemical double- layer thickness and silicon dopant type, and concentration. (C) 2004 The Electrochemical Society.......This paper considers the precipitation of iron oxide particles in connection with the KOH etching of cavities in silicon wafers. The findings presented in this paper suggest that the source to the particles is the KOH pellets used for making the etching solution. Experiments show...... that the precipitation is independent of KOH etching time, but that the amount of deposited material varies with dopant type and dopant concentration. The experiments also suggest that the precipitation occurs when the silicon wafers are removed from the KOH etching solution and not during the etching procedure. When...

  9. Dry etching technologies for the advanced binary film

    Science.gov (United States)

    Iino, Yoshinori; Karyu, Makoto; Ita, Hirotsugu; Yoshimori, Tomoaki; Azumano, Hidehito; Muto, Makoto; Nonaka, Mikio

    2011-11-01

    ABF (Advanced Binary Film) developed by Hoya as a photomask for 32 (nm) and larger specifications provides excellent resistance to both mask cleaning and 193 (nm) excimer laser and thereby helps extend the lifetime of the mask itself compared to conventional photomasks and consequently reduces the semiconductor manufacturing cost [1,2,3]. Because ABF uses Ta-based films, which are different from Cr film or MoSi films commonly used for photomask, a new process is required for its etching technology. A patterning technology for ABF was established to perform the dry etching process for Ta-based films by using the knowledge gained from absorption layer etching for EUV mask that required the same Ta-film etching process [4]. Using the mask etching system ARES, which is manufactured by Shibaura Mechatronics, and its optimized etching process, a favorable CD (Critical Dimension) uniformity, a CD linearity and other etching characteristics were obtained in ABF patterning. Those results are reported here.

  10. Zirconia as a Dental Biomaterial

    Directory of Open Access Journals (Sweden)

    Alvaro Della Bona

    2015-08-01

    Full Text Available Ceramics are very important in the science of dental biomaterials. Among all dental ceramics, zirconia is in evidence as a dental biomaterial and it is the material of choice in contemporary restorative dentistry. Zirconia has been applied as structural material for dental bridges, crowns, inserts, and implants, mostly because of its biocompatibility, high fracture toughness, and radiopacity. However, the clinical success of restorative dentistry has to consider the adhesion to different substrates, which has offered a great challenge to dental zirconia research and development. This study characterizes zirconia as a dental biomaterial, presenting the current consensus and challenges to its dental applications.

  11. Solid polymer electrolyte composite membrane comprising plasma etched porous support

    Science.gov (United States)

    Liu, Han; LaConti, Anthony B.

    2010-10-05

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 0.1 to 5 microns, are made by plasma etching and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  12. Evaluation of shear bond strength of metallic and ceramic brackets bonded to enamel prepared with self-etching primer.

    Science.gov (United States)

    Uysal, Tancan; Ustdal, Ayca; Kurt, Gokmen

    2010-04-01

    The aim of this in vitro study was to evaluate the shear bond strength (SBS) of different metallic and ceramic bracket bonding combinations using self-etching primers (SEPs). Eighty freshly extracted human premolar teeth were randomly divided into four equal groups for bonding with ceramic or metallic brackets as follows: group 1, metallic brackets bonded with conventional acid etching; group 2, metallic brackets bonded with Transbond Plus Self-Etching primer (TPSEP); group 3, ceramic brackets bonded as per group 1; group 4, ceramic brackets bonded as per group 2. The SBS of these brackets was measured and recorded in megapascals (MPa). The adhesive remnant index (ARI) scores were determined after bracket failure. Data were analyzed with the analysis of variance, Tukey, and chi-square tests. The bond strength of group 3 (mean: 36.7 +/- 11.8 MPa) was significantly higher than group 4 (mean: 26.6 +/- 8.9 MPa; P 0.05). Compared with conventional acid etching, SEPs significantly decreased the SBS of ceramic orthodontic brackets.

  13. Parametric study on the solderability of etched PWB copper

    Energy Technology Data Exchange (ETDEWEB)

    Hosking, F.M.; Stevenson, J.O.; Hernandez, C.L.

    1996-10-01

    The rapid advancement of interconnect technology has resulted in a more engineered approach to designing and fabricating printed wiring board (PWB) surface features. Recent research at Sandia National Laboratories has demonstrated the importance of surface roughness on solder flow. This paper describes how chemical etching was used to enhance the solderability of surfaces that were normally difficult to wet. The effects of circuit geometry, etch concentration, and etching time on solder flow are discussed. Surface roughness and solder flow data are presented. The results clearly demonstrate the importance of surface roughness on the solderability of fine PWB surface mount features.

  14. Fabrication of Pure Silica Core Multimode Ultraviolet Optical Fibre Probes by Tube Etching

    Institute of Scientific and Technical Information of China (English)

    HUO Xin; PAN Shi; WU Shi-Fa

    2007-01-01

    As a light wave-guide component for transmitting ultraviolet (UV) laser pulses, pure silica core UV fibre probes have attracted a great deal of attention in the near-field optical data storage and bio-medical studies. We fabricate UV fibre probes with tips in dimension of about 2-5μm and taper angle 16° by the tube etching method, using 40% HF acid as etching solution and xylene as overlayer. Probes produced have curvy configuration with smooth surface. The yield of fine probes is rather high and etching operation greatly simplified. With higher damage threshold, pure silica core multimode UV fibre probes can be coupled into more laser power. In addition, using UV light reduces the cutoff wavelength of the fibre probes, which is in favour of increasing the transmission efficiency of the probe. Furthermore, the larger tip dimension helps to enhance the light throughput either. The advances of fabrication technique of UV optical fibre probe may further support the studies of UV light data storage, pulsed laser biosurgery and UV photolithography.

  15. Silicon solar cells textured by reactive ion etching and processed with screen printing

    Energy Technology Data Exchange (ETDEWEB)

    Burgers, A.R.; Tool, C.J.J.; Hylton, J.D.; Weeber, A.W. [ECN Solar and Wind, Netherlands Energy Research Foundation ECN, Petten (Netherlands); Verholen, A.G.B.J.; Gardeniers, J.G.E.; De Boer, M.J.; Elwenspoek, M.C. [MESA Research Institute for Micro Electronics, Materials- and Molecular Engineering, and Sensors and Actuators, University of Twente, Enschede (Netherlands)

    1998-07-01

    Reactive Ion Etching (RIE) can texture multicrystalline silicon wafers very well. RIE has the advantage over alkaline etches that it is not sensitive to the crystallographic orientation. RIE has the advantage over acid etches that it can be controlled much better. This work describes multicrystalline silicon solar cells textured by RIE and processed with an industrial process sequence consisting of mainly screen-printing steps. We also made mini-modules of the RIE textured cells. The RIE texturing parameters can be varied to give different textures. Care must be taken that the texture is sufficiently rough to give a low encapsulated reflectance but not so rough that carriers generated by light absorbed in the texture recombine at the surface and cannot be collected at the p-n junction. The screen printing on RIE textured cells was successful. We were able to make cells with both low reflectance and good quantum efficiency. Due to encapsulation problems we were not able to demonstrate an efficiency gain yet. 10 refs.

  16. Ultrasensitive Visual Sensing of Molybdate Based on Enzymatic-like Etching of Gold Nanorods.

    Science.gov (United States)

    Zhang, Zhiyang; Chen, Zhaopeng; Chen, Lingxin

    2015-08-25

    Here, we have developed a novel approach to the visual detection of molybdate with high sensitivity and selectivity in aqueous media based on the combination of catalytic formation of iodine and iodine-mediated etching of gold nanorods. In weak acid solution, like peroxidase, molybdate can catalyze the reaction between H2O2 and I(-) to produce I2, a moderate oxidant, which then etches gold nanorods preferentially along the longitudinal direction in the presence of hexadecyltrimethylammonium bromide. The etching results in the longitudinal localized surface plasmon resonance extinction peak shifts to short wavelength, accompanied by a color change from blue to red. Under optimal conditions, this sensor exhibits good sensitivity with a detection limit of 1.0 nM. The approach is highlighted by its high selectivity and tolerance to interference, which enables the sensor to detect molybdate directly in real samples, such as tap water, drinking water, and seawater. In addition, perhaps the proposed sensing strategy can be also used for other targets that can selectively regulate the formation of I2 under given conditions.

  17. Nanoporous Gallium Nitride Through Anisotropic Metal-Assisted Electroless Photochemical Wet Etching Technique

    Science.gov (United States)

    Perumal, R.; Hassan, Z.

    2016-12-01

    Nanoporous gallium nitride (GaN) has many potential applications in light-emitting diodes (LEDs), photovoltaics, templates and chemical sensors. This article reports the porosification of GaN through UV enhanced metal-assisted electroless photochemical wet etching technique using three different acid-based etchants and platinum served as catalyst for porosification. The etching process was conducted at room temperature for a duration of 90min. The morphological, structural, spectral and optical features of the developed porous GaN were studied with appropriate characterization techniques and the obtained results were presented. Field emission scanning electron micrographs exhibited the porosity nature along with excellent porous network of the etched samples. Structural studies confirmed the mono crystalline quality of the porous nanostructures. Raman spectral analyzes inferred the presenting phonon modes such as E2 (TO) and A1 (LO) in fabricated nanoporous structures. The resulted porous nanostructures hold the substantially enhanced photoluminescence intensity compared with the pristine GaN epitaxial film that is interesting and desirable for several advances in the applications of Nano-optoelectronic devices.

  18. Equine dental advances.

    Science.gov (United States)

    Greene, S K

    2001-08-01

    The reintroduction and development of safe motorized instruments, the increased availability of continuing education, and the understanding and implementation of appropriate procedures allow practitioners to provide better dental care. Veterinarians realize that sedation, analgesia, a full-mouth speculum, and proper instrumentation are necessary to provide these services. Continued instrument design, future research, and new treatment and prophylactic protocols should have a positive impact on the future of equine dental health. New and rediscovered procedures for equilibrating equine occlusion are allowing horses to masticate more efficiently, carry a bit more comfortably, and experience improved performance. The horse, the horse owner, and the veterinary profession all benefit from providing complete equine dental care.

  19. Dental pulp stem cells

    DEFF Research Database (Denmark)

    Ashri, N. Y.; Ajlan, S. A.; Aldahmash, Abdullah M.

    2015-01-01

    scaffold, and guided through signaling molecules. Dental pulp stem cells have been used in an increasing number of studies in dental tissue engineering. Those cells show mesenchymal (stromal) stem cell-like properties including self-renewal and multilineage differentiation potentials, aside from...... an updated review on dental pulp stem cells and their applications in periodontal regeneration, in combination with different scaffolds and growth factors.......Inflammatory periodontal disease is a major cause of loss of tooth-supporting structures. Novel approaches for regeneration of periodontal apparatus is an area of intensive research. Periodontal tissue engineering implies the use of appropriate regenerative cells, delivered through a suitable...

  20. Feline dental disease.

    Science.gov (United States)

    Frost, P; Williams, C A

    1986-09-01

    Periodontal disease and chronic gingivitis/stomatitis are the most common feline dental diseases. With routine dental care and increased emphasis on home oral hygiene, these diseases can be controlled. Cats can be seen with a number of other dental disorders, and improved treatment methods such as restorations of early subgingival resorptive lesions, endodontic therapy, and orthodontic therapy can be performed successfully. More study and research are necessary about the gingivitis/stomatitis syndrome and subgingival resorptive lesions so that improved prevention and treatment recommendations can be made.

  1. Investigation of electrochemical etch differences in AlGaAs heterostructures using Cl{sub 2} ion beam assisted etching

    Energy Technology Data Exchange (ETDEWEB)

    Anglin, Kevin, E-mail: kevin.r.anglin@gmail.com; Goodhue, William D. [Massachusetts Institute of Technology Lincoln Laboratory, 244 Wood St., Lexington, Massachusetts 02420 and Department of Physics and Applied Physics, University of Massachusetts Lowell, 1 University Ave., Lowell, Massachusetts 01854 (United States); Swint, Reuel B.; Porter, Jeanne [Massachusetts Institute of Technology Lincoln Laboratory, 244 Wood St., Lexington, Massachusetts 02420 (United States)

    2015-03-15

    A deeply etched, anisotropic 45° and 90° mirror technology is developed for Al{sub x}Ga{sub 1−x}As heterostructures using a Cl{sub 2} ion beam assisted etching system. When etching vertically, using a conductive low-erosion Ni mask, electrochemical etch differences between layers with various Al mole fractions caused nonuniform sidewall profiles not seen in semi-insulating GaAs test samples. These variations, based on alloy composition, were found to be negligible when etching at a 45°. A Si{sub 3}N{sub 4}-Ni etch mask is designed in order to electrically isolate charge buildup caused by the incoming Ar{sup +} ion beam to the Ni layer, preventing conduction to the underlying epitaxial layers. This modification produced smoothly etched facets, up to 8 μm in depth, enabling fabrication of substrate–surface-emitting slab-coupled optical waveguide lasers and other optoelectronic devices.

  2. Depletion of water molecules during ethanol wet-bonding with etch and rinse dental adhesives

    Energy Technology Data Exchange (ETDEWEB)

    Gregoire, Genevieve, E-mail: gregoire@cict.fr [Department of Biomaterials, Faculty of Odontology, University Toulouse III, 31062, Toulouse (France); Sharrock, Patrick [Medical and Spatial Imaging Laboratory, University Toulouse III, Ave. Pompidou, 81104, Castres (France); Delannee, Mathieu [Department of Biomaterials, Faculty of Odontology, University Toulouse III, 31062, Toulouse (France); Delisle, Marie-Bernadette [Faculty of Medicine, University Toulouse III, 31062, Toulouse (France)

    2013-01-01

    The treatment of demineralized dentin with ethanol has been proposed as a way to improve hydrophobic monomer penetration into otherwise water saturated collagen fibrils. The ethanol rinse is expected to preserve the fibrils from collapsing while optimizing resin constituent infiltration for better long term adhesion. The physico-chemical investigations of demineralized dentin confirmed objectively these working hypotheses. Namely, Differential Scanning Calorimetry (DSC) measurements of the melting point of water molecules pointed to the presence of free and bound water states. Unfreezable water was the main type of water remaining following a rinsing step with absolute ethanol. Two different liquid water phases were also observed by Magic Angle Spinning (MAS) solid state Nuclear magnetic Resonance (NMR) spectroscopy. Infrared spectra of ethanol treated specimens illustrated differences with the fully hydrated specimens concerning the polar carbonyl vibrations. Optical microscopy observations as well as scanning electron microscopy showed an improved dentin-adhesive interface with ethanol wet bonding. The results indicate that water can be confined to strongly bound structural molecules when excess water is removed with ethanol prior to adhesive application. This should preserve collagen from hydrolysis upon aging of the hybrid layer. - Highlights: Black-Right-Pointing-Pointer Non-freezable water exists in demineralized dentine. Black-Right-Pointing-Pointer Free water can be removed by ethanol rinse of the demineralized collagen. Black-Right-Pointing-Pointer Ethanol wet bonding leads to a homogeneous hybrid layer free of defects.

  3. Effectiveness of immediate bonding of etch-and-rinse adhesives to simplified ethanol-saturated dentin

    Directory of Open Access Journals (Sweden)

    Leandro Afonso Guimarães

    2012-04-01

    Full Text Available This study examined the immediate bond strength of etch-and-rinse adhesives to demineralized dentin saturated with either water or absolute ethanol. The research hypothesis was that there would be no difference in bond strength to dentin between water or ethanol wet-bonding techniques. The medium dentin of 20 third molars was exposed (n = 5. The dentin surface was then acid-etched, left moist and randomly assigned to be saturated via either water wet-bonding (WBT or absolute ethanol wet-bonding (EBT. The specimens were then treated with one of the following etch-and-rinse adhesive systems: a 3-step, water-based system (Adper Scotchbond Multipurpose, or SBMP or a 2-step, ethanol/water-based system (Adper Single Bond 2, or SB. Resin composite build-ups were then incrementally constructed. After water storage for 24 h at 37°C, the tensile strength of the specimens was tested in a universal testing machine (0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey's test (a = 5%. The failure modes were verified using a stereomicroscope (40'. For both adhesives, no significant difference in bond strength was observed between WBT and EBT (p > 0.05. The highest bond strength was observed for SB, regardless of the bonding technique (p < 0.05. No significant interaction between adhesives and bonding techniques was noticed (p = 0.597. There was a predominance of adhesive failures for all tested groups. The EBT and WBT displayed similar immediate bond strength means for both adhesives. The SB adhesive exhibited higher means for all conditions tested. Further investigations are needed to evaluate long-term bonding to dentin mediated by commercial etch-and-rinse adhesives using the EBT approach.

  4. Galvanic corrosion of Cu coupled to Au on a print circuit board; Effects of pretreatment solution and etchant concentration in organic solderability preservatives soft etching solution

    Science.gov (United States)

    Oh, SeKwon; Kim, YoungJun; Shon, MinYoung; Kwon, HyukSang

    2016-09-01

    In present study, we quantitatively define the galvanic corrosion phenomenon of Cu electrically coupled to Au on Print Circuit Board in Organic Solderability Preservatives (OSP) pretreatment (pickling and soft etching) solutions. As a result of polarization and ZRA test, galvanic corrosion rate of Cu in soft etching solution was about 3000 times higher than that of pickling solution. The oxone in OSP soft etching solution was acted as strong oxidant for Cu on PCB substrate. And the galvanic corrosion of Cu in OSP soft etching solution was examined with the change of etchants (oxone (KHSO5), sulfuric acid (H2SO4)) concentration. The galvanic corrosion rate of Cu was increased by the increase of the oxone and sulfuric acid concentrations, which lead to the increase of cathodic reactant such as HSO 5 - and H+ ions. And the degree of galvanic corrosion rate of Cu (Δisoft etching = icouple, (Cu-Au) - icorr, Cu) decreased with the decrease of the oxone and sulfuric acid concentrations.

  5. Erbium doped stain etched porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Diaz, B. [Departamento de Fisica Basica, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Diaz-Herrera, B. [Departamento de Energia Fotovoltaica, Instituto Tecnologico de Energias Renovables (ITER), Poligono Industrial de Granadilla, 38611 S/C Tenerife (Spain); Guerrero-Lemus, R. [Departamento de Fisica Basica, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain)], E-mail: rglemus@ull.es; Mendez-Ramos, J.; Rodriguez, V.D. [Departamento de Fisica Fundamental, Experimental Electronica y Sistemas, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Hernandez-Rodriguez, C. [Departamento de Fisica Basica, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Martinez-Duart, J.M. [Departamento de Fisica Aplicada, C-XII, Universidad Autonoma de Madrid, 28049 Cantoblanco, Madrid (Spain)

    2008-01-15

    In this work a simple erbium doping process applied to stain etched porous silicon layers (PSLs) is proposed. This doping process has been developed for application in porous silicon solar cells, where conventional erbium doping processes are not affordable because of the high processing cost and technical difficulties. The PSLs were formed by immersion in a HF/HNO{sub 3} solution to properly adjust the porosity and pore thickness to an optimal doping of the porous structure. After the formation of the porous structure, the PSLs were analyzed by means of nitrogen BET (Brunauer, Emmett and Teller) area measurements and scanning electron microscopy. Subsequently, the PSLs were immersed in a saturated erbium nitrate solution in order to cover the porous surface. Then, the samples were subjected to a thermal process to activate the Er{sup 3+} ions. Different temperatures and annealing times were used in this process. The photoluminescence of the PSLs was evaluated before and after the doping processes and the composition was analyzed by Fourier transform IR spectroscopy.

  6. Marginal permeability of self-etch and total-etch adhesive systems.

    Science.gov (United States)

    Owens, Barry M; Johnson, William W; Harris, Edward F

    2006-01-01

    This study evaluated microleakage in vitro of self-etch and multi-step, total-etch adhesive systems. Ninety-six extracted non-carious human molars were randomly assigned to eight groups (n=12) and restored with different adhesive systems: Optibond Solo Plus, iBond, Adper Prompt L-Pop, Xeno III, Simplicity, Nano-Bond, Adper Scotchbond Multi-Purpose and Touch & Bond. Each group was treated following the manufacturer's instructions. Class V cavities were prepared on the facial or lingual surfaces of each tooth with coronal margins in enamel and apical margins in cementum (dentin). The teeth were restored with Z-100 resin composite. After polishing with Sof-Lex disks, the teeth were thermocycled for 1000 cycles and coated with nail varnish to within 1.0 mm of the restoration. The teeth were stained in 1% methylene blue dye for 24 hours and sectioned from the facial to lingual surface. Dye penetration (microleakage) was examined with a 20x binocular microscope. Enamel and dentin margin leakage was scored on a 0 to 3 ordinal scale. Data were analyzed using Kruskal-Wallis Analysis of Variance and Mann-Whitney U tests. Comparison of the adhesive groups at the enamel margin revealed: 1) Adper Scotchbond Multi-Purpose exhibited significantly less leakage than the other adhesive groups (except iBond); 2) among the self-etch adhesive groups, iBond exhibited significantly less leakage than Nano-Bond and 3) the other adhesive groups clustered intermediately. In contrast, there were no significant differences among the adhesive groups when the dentin margin was evaluated. A Wilcoxin signed rank test showed significantly less leakage at the enamel margins compared to the dentin margins of the eight adhesive systems tested. All data were submitted to statistical analysis at p<0.05 level of significance.

  7. Summary of Chalcogenide Glass Processing: Wet-Etching and Photolithography

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Brian J.; Sundaram, S. K.; Johnson, Bradley R.; Saraf, Laxmikant V.

    2006-12-01

    This report describes a study designed to explore the different properties of two different chalcogenide materials, As2S3 and As24S38Se38, when subjected to photolithographic wet-etching techniques. Chalcogenide glasses are made by combining chalcogen elements S, Se, and Te with Group IV and/or V elements. The etchant was selected from the literature and was composed of sodium hydroxide, isopropyl alcohol, and deionized water and the types of chalcogenide glass for study were As2S3 and As24S38Se38. The main goals here were to obtain a single variable etch rate curve of etch depth per time versus NaOH overall solution concentration in M and to see the difference in etch rate between a given etchant when used on the different chalcogenide stoichiometries. Upon completion of these two goals, future studies will begin to explore creating complex, integrated photonic devices via these methods.

  8. GaN Nanowires Synthesized by Electroless Etching Method

    KAUST Repository

    Najar, Adel

    2012-01-01

    Ultra-long Gallium Nitride Nanowires is synthesized via metal-electroless etching method. The morphologies and optical properties of GaN NWs show a single crystal GaN with hexagonal Wurtzite structure and high luminescence properties.

  9. Cryogenic rf test of the first plasma etched SRF cavity

    CERN Document Server

    Upadhyay, J; Popović, S; Valente-Feliciano, A -M; Im, D; Phillips, L; Vušković, L

    2016-01-01

    Plasma etching has a potential to be an alternative processing technology for superconducting radio frequency (SRF) cavities. An apparatus and a method are developed for plasma etching of the inner surfaces of SRF cavities. To test the effect of the plasma etching on the cavity rf performance, a 1497 MHz single cell SRF cavity is used. The single cell cavity is mechanically polished, buffer chemically etched afterwards and rf tested at cryogenic temperatures for a baseline test. This cavity is then plasma processed. The processing was accomplished by moving axially the inner electrode and the gas flow inlet in a step-wise manner to establish segmented plasma processing. The cavity is rf tested afterwards at cryogenic temperatures. The rf test and surface condition results are presented.

  10. Polishing of quartz by rapid etching in ammonium bifluoride.

    Science.gov (United States)

    Vallin, Orjan; Danielsson, Rolf; Lindberg, Ulf; Thornell, Greger

    2007-07-01

    The etch rate and surface roughness of polished and lapped AT-cut quartz subjected to hot (90, 110, and 130 degrees C), concentrated (50, 65, 80 wt %) ammonium bi-fluoride have been investigated. Having used principal component analysis to verify experimental solidity and analyze data, we claim with confidence that this parameter space does not, as elsewhere stated, allow for a polishing effect or even a preserving setting. Etch rates were found to correlate well, and possibly logarithmically, with temperature except for the hottest etching applied to lapped material. Roughness as a function of temperature and concentration behaved well for the lapped material, but lacked systematic variation in the case of the polished material. At the lowest temperature, concentration had no effect on etch rate or roughness. Future efforts are targeted at temperatures and concentrations closer to the solubility limit.

  11. Xilitol and dental caries.

    NARCIS (Netherlands)

    Smits, Marten Titus

    1987-01-01

    Dental caries is a widespread multifactoral disease. The main sympthons are minaral loss from tooth enemal and dentine, eventually leading to total destruction of the teeth, pain, impairment of mastication and problems with facial esthetics. ... Zie: Summary

  12. Dental Treatment Considerations

    Science.gov (United States)

    ... ask about Dental Treatment Considerations www.myasthenia.org Myasthenia gravis (MG) is an autoimmune neuromuscular disorder that presents ... diagnosis and optimal care of individuals affected by myasthenia gravis and closely related disorders and to improve their ...

  13. Dental Care in Scleroderma

    Science.gov (United States)

    ... a side effect • Avoid the spiral of depression – depression causes worse oral health and poor oral health worsens depression. Suggestions for your dental appointments: • Tell the dentist ...

  14. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells.

    Science.gov (United States)

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao

    2016-12-01

    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time.

  15. Surface modification with alumina blasting and H2SO4-HCl etching for bonding two resin-composite veneers to titanium.

    Science.gov (United States)

    Taira, Yohsuke; Egoshi, Takafumi; Kamada, Kohji; Sawase, Takashi

    2014-02-01

    The purpose of this study was to investigate the effect of an experimental surface treatment with alumina blasting and acid etching on the bond strengths between each of two resin composites and commercially pure titanium. The titanium surface was blasted with alumina and then etched with 45wt% H2SO4 and 15wt% HCl (H2SO4-HCl). A light- and heat-curing resin composite (Estenia) and a light-curing resin composite (Ceramage) were used with adjunctive metal primers. Veneered specimens were subjected to thermal cycling between 4 and 60°C for 50,000 cycles, and the shear bond strengths were determined. The highest bond strengths were obtained for Blasting/H2SO4-HCl/Estenia (30.2 ± 4.5 MPa) and Blasting/Etching/Ceramage (26.0 ± 4.5 MPa), the values of which were not statistically different, followed by Blasting/No etching/Estenia (20.4 ± 2.4 MPa) and Blasting/No etching/Ceramage (0.8 ± 0.3 MPa). Scanning electron microscopy observations revealed that alumina blasting and H2SO4-HCl etching creates a number of micro- and nanoscale cavities on the titanium surface, which contribute to adhesive bonding.

  16. Bond efficacy and interface morphology of self-etching adhesives to ground enamel

    NARCIS (Netherlands)

    Abdalla, A.I.; El Zohairy, A.A.; Mohsen, M.M.A.; Feilzer, A.J.

    2010-01-01

    Purpose: This study compared the microshear bond strengths to ground enamel of three one-step self-etching adhesive systems, a self-etching primer system and an etch-and-rinse adhesive system. Materials and Methods: Three self-etching adhesives, Futurabond DC (Voco), Clearfil S Tri Bond (Kuraray) an

  17. Dry etching of single crystal PMN-PT piezoelectric material.

    OpenAIRE

    Agnus, Joël; Alexandru Ivan, Ioan; Queste, Samuel

    2011-01-01

    International audience; During the last decade, the applications of PMN-PT spread significantly. Unlike PZT, the appropriate microtechnologies for PMN-PT Piezo-MEMS aren't fully documented in the literature. This paper deals with the PMN-PT etching by inductively coupled plasma (ICP) technique, also known as DRIE. The paper quantitatively presents the etching parameters of PMN-PT by the Ar/C4F8 gas combination and reports some related useful experience.

  18. Quantum-size-controlled photoelectrochemical etching of semiconductor nanostructures

    Science.gov (United States)

    Fischer, Arthur J.; Tsao, Jeffrey Y.; Wierer, Jr., Jonathan J.; Xiao, Xiaoyin; Wang, George T.

    2016-03-01

    Quantum-size-controlled photoelectrochemical (QSC-PEC) etching provides a new route to the precision fabrication of epitaxial semiconductor nanostructures in the sub-10-nm size regime. For example, quantum dots (QDs) can be QSC-PEC-etched from epitaxial InGaN thin films using narrowband laser photoexcitation, and the QD sizes (and hence bandgaps and photoluminescence wavelengths) are determined by the photoexcitation wavelength.

  19. Etching zircon age standards for fission-track analysis

    Energy Technology Data Exchange (ETDEWEB)

    Garver, J.I. E-mail: garverj@union.edu

    2003-02-01

    Nineteen laboratories that routinely measure fission-track ages in zircon were surveyed as to their principal methodology used for track revelation using chemical attack and counting procedures. The survey results show the following: (a) researchers in most labs count fission tracks with a optical microscope using at a total magnification between 1250x and 1600x ({approx}80%) with about an equal number using either a dry or oil objective (b) the majority of laboratories etch zircon with a KOH:NaOH eutectic heated in an oven between temperatures of 210 deg. C and 230 deg. C; (c) ag standards in zircon analysis do not have uniformly accepted etch times. Etching times for the widely used 28 Ma Fish Canyon Tuff (FCT) (4-60 h) and the lesser-used 16 Ma Buluk Tuff (13-55 h) vary significantly from lab to lab. Between {approx}220 deg. C and 230 deg. C, the principal range fo etching times for the FCT is between 20 and 30 h, and the mode for the Buluk Tuff is between 30 and 55 h. Three or fewer labs report etching times for the Tardee Rhyolite (22-40 h), the Bishop Tuff (10-46 h), and the Mt. Dromedary Banite (5-24 h). Variation in etching times may result in a bias in U-content which affects counting statistics. If etching is successful, strict criteria must be followed to ensure that the analyst only counts well-etched grains and that all tracks are successfully identified.

  20. Influence of copper foil polycrystalline structure on graphene anisotropic etching

    Science.gov (United States)

    Sharma, Kamal P.; Mahyavanshi, Rakesh D.; Kalita, Golap; Tanemura, Masaki

    2017-01-01

    Anisotropic etching of graphene and other two dimensional materials is an important tool to understand the growth process as well as enabling fabrication of various well-defined structures. Here, we reveal the influence of copper foil polycrystalline structure on anisotropic etching process of as-synthesized graphene. Graphene crystals were synthesized on the polycrystalline Cu foil by a low-pressure chemical vapor deposition (LPCVD) system. Microscopic analysis shows difference in shape, size and stripes alignment of graphene crystals with dissimilar nucleation within closure vicinity of neighboring Cu grains. Post-growth etching of such graphene crystals also significantly affected by the crystallographic nature of Cu grains as observed by the field emission scanning electron microscope (FE-SEM) and electron back scattered diffraction (EBSD) analysis. Hexagonal hole formation with anisotropic etching is observed to be independent of the stripes and wrinkles in the synthesized graphene. We also observed variation in etched pattern of the graphene depending on the base Cu grain orientations, attributing to difference in nucleation and growth process. The findings can facilitate to understand the nature of microscopic etched pattern depending on metal catalyst crystallographic structure.

  1. Etching of germanium-tin using ammonia peroxide mixture

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Yuan; Ong, Bin Leong; Wang, Wei; Gong, Xiao; Liang, Gengchiau; Yeo, Yee-Chia, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Zhang, Zheng; Pan, Jisheng [Institute of Material Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, #08-03, Innovis, Singapore 138634 (Singapore); Tok, Eng-Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

    2015-12-28

    The wet etching of germanium-tin (Ge{sub 1-x}Sn{sub x}) alloys (4.2% < x < 16.0%) in ammonia peroxide mixture (APM) is investigated. Empirical fitting of the data points indicates that the etch depth of Ge{sub 1-x}Sn{sub x} is proportional to the square root of the etch time t and decreases exponentially with increasing x for a given t. In addition, X-ray photoelectron spectroscopy results show that increasing t increases the intensity of the Sn oxide peak, whereas no obvious change is observed for the Ge oxide peak. This indicates that an accumulation of Sn oxide on the Ge{sub 1-x}Sn{sub x} surface decreases the amount of Ge atoms exposed to the etchant, which accounts for the decrease in etch rate with increasing etch time. Atomic force microscopy was used to examine the surface morphologies of the Ge{sub 0.918}Sn{sub 0.082} samples. Both root-mean-square roughness and undulation periods of the Ge{sub 1-x}Sn{sub x} surface were observed to increase with increasing t. This work provides further understanding of the wet etching of Ge{sub 1-x}Sn{sub x} using APM and may be used for the fabrication of Ge{sub 1-x}Sn{sub x}-based electronic and photonic devices.

  2. Etching Rate of Silicon Dioxide Using Chlorine Trifluoride Gas

    Science.gov (United States)

    Miura, Yutaka; Kasahara, Yu; Habuka, Hitoshi; Takechi, Naoto; Fukae, Katsuya

    2009-02-01

    The etching rate behavior of silicon dioxide (SiO2, fused silica) using chlorine trifluoride (ClF3) gas is studied at substrate temperatures between 573 and 1273 K at atmospheric pressure in a horizontal cold-wall reactor. The etching rate increases with the ClF3 gas concentration, and the overall reaction is recognized to be of the first order. The change of the etching rate with increasing substrate temperature is nonlinear, and the etching rate tends to approach a constant value at temperatures exceeding 1173 K. The overall rate constant is estimated by numerical calculation, taking into account the transport phenomena in the reactor, including the chemical reaction at the substrate surface. The activation energy obtained in this study is 45.8 kJ mol-1, and the rate constant is consistent with the measured etching rate behavior. A reactor system in which there is minimum etching of the fused silica chamber by ClF3 gas can be achieved using an IR lamp heating unit and a chamber cooling unit to maintain a sufficiently low temperature of the chamber wall.

  3. Spontaneous Differentiation of Dental Pulp stem cells on Dental polymers

    Science.gov (United States)

    Bherwani, Aneel; Suarato, Giulia; Qin, Sisi; Chang, Chung-Cheh; Akhavan, Aaron; Spiegel, Joseph; Jurukovski, Vladimir; Rafailovich, Miriam; Simon, Marcia

    2012-02-01

    Dental pulp stem cells were plated on two dentally relevant materials i.e. PMMA commonly used for denture and Titanium used for implants. In both cases, we probed for the role of surface interaction and substrate morphology. Different films of PMMA were spun cast directly onto Si wafers; PMMA fibers of different diameters were electro spun onto some of these substrates. Titanium metal was evaporated onto Si surfaces using an electron beam evaporator. In addition, on some surfaces, P4VP nanofibers were spun cast. DPSC were grown in alpha-MEM supplemented with 10% fetal bovine serum, 0.2mM L-ascorbic acid 2-phosphate, 2mm glutamine and 10mM beta-glycerol phosphate either with or without 10nM dexamethasone. After 21 days samples were examined using confocal microscopy of cells and by scanning electron microscopy (SEM) and Energy dispersive X-ray Analysis (EDAX). In the case of Titanium biomineralization was observed independent of dexamethasone, where the deposits were templated along the fibers. Minimal biomineralization was observed on flat Titanium and PMMA samples. Markers of osteogenesis and specific signaling pathways are being evaluated by RT-PCR, which are up regulated on each surface, to understand the fundamental manner in which surfaces interact with cell differentiation.

  4. Dental patients' use of the Internet.

    LENUS (Irish Health Repository)

    2009-12-19

    To determine the use of the Internet by patients attending a range of dental clinics to search for information regarding dental procedures, and also to investigate their interest in online dental consultations and \\'dental tourism\\'.

  5. Methods of removal of defects arising at liquid etching of polycrystalline silicon

    Directory of Open Access Journals (Sweden)

    Ivanchykou A. E.

    2008-02-01

    Full Text Available The paper presents a model of generation of defects having the form of spots on the surface of the polycrystalline silicon during processing of semiconductor wafers with hydrofluoric acid based etchant, and a model of removal of such defects in chemical solutions. The authors investigate how the centrifuge speed during drying and the relief of structures, produced on the plate, effect the number of defects. It is shown that there is a possibility to remove defects by chemical treatment in the peroxide-ammonia solutions (PAS and also by sequence of chemical cleaning in Karo mixture, SiO2 etching and treatment in PAS.

  6. Etched glass self-assembles into micron-size hollow platonic solids

    KAUST Repository

    Boukhalfa, Sofiane

    2012-10-03

    The interaction between the spreading of a hydrofluoric acid-based drop on a glass surface and its etching rate gives rise to hollow crystals of various shapes, including cubes, triangles, and icosahedra. These geometries are dependent on their position with respect to the contact line, where a rim forms by agglutination, similar to the formation of a coffee stain. Atomic force microscopy indentation and transmission electron microscopy observations revealed that these crystals are hollow ammonium-fluosilicate-based cryptohalite shells. © 2012 American Chemical Society.

  7. Effect of Etching Parameter on Pore Size and Porosity of Electrochemically Formed Nanoporous Silicon

    Directory of Open Access Journals (Sweden)

    Pushpendra Kumar

    2007-01-01

    Full Text Available The most common fabrication technique of porous silicon (PS is electrochemical etching of a crystalline silicon wafer in a hydrofluoric (HF acid-based solution. The electrochemical process allows for precise control of the properties of PS such as thickness of the porous layer, porosity, and average pore diameter. The control of these properties of PS was shown to depend on the HF concentration in the used electrolyte, the applied current density, and the thickness of PS. The change in pore diameter, porosity, and specific surface area of PS was investigated by measuring nitrogen sorption isotherms.

  8. Comparison of the Schaake and Benson Etches to Delineate Dislocations in HgCdTe Layers

    Science.gov (United States)

    Farrell, S.; Rao, Mulpuri V.; Brill, G.; Chen, Y.; Wijewarnasuriya, P.; Dhar, N.; Benson, J. D.; Harris, K.

    2013-11-01

    The morphology and classification of etch pits in molecular beam epitaxy-grown (211) HgCdTe/CdTe/Si layers were investigated using the Schaake and Benson etch pit density (EPD) etches. The two EPD etches were compared and shown to have a 1:1 correlation in the etch pits that were produced. Close examination of the shape of the etch pits via scanning electron microscopy shows that several distinguishable classifications of etch pits are revealed using both etches. Samples subjected to thermal cycle annealing (TCA) treatment show a nonuniform reduction in etch pit populations according to the classification defined in this study. In particular, a class of etch pits called "fish shaped" are completely absent after TCA and can account for up to one-third of the total reduction in EPD.

  9. A comparison of the resin tag penetration of the total etch and the self-etch dentin bonding systems in the primary teeth: An in vitro study

    Science.gov (United States)

    Mithiborwala, Sajjad; Chaugule, Vishwas; Munshi, A. K.; Patil, Vishwas

    2012-01-01

    Background and Objective: Restoration of carious lesions with a strong permanent bond would be a highly desirable requisite. Ultra morphological characterization shows that observing and understanding the interfacial phenomenon and its quality would be of great importance in the selection of a dental adhesive for its use in pediatric restorative dentistry. Study design: Human primary molars, indicated for extraction, for reasons like caries, normal exfoliation, pathological root resorption, over-retained and serial extraction, were collected. Teeth were then equally distributed into 2 subgroups each namely B1 - Prime and Bond NT & B2 - Xeno III. Results: The resin tags seen in the samples of group B2 were both qualitatively and quantitatively advanced as compared to group B1. This reveals that the quality of the penetration of the resin was better in group B2. Conclusion: Reduction in the technique sensitivity of any bonding system would always be a preferred factor in pediatric restorative dentistry. Thus the inclination towards the selection of adhesive system may lean towards the self-etching bonding system at this juncture. PMID:22919214

  10. A comparison of the resin tag penetration of the total etch and the self-etch dentin bonding systems in the primary teeth: An in vitro study

    Directory of Open Access Journals (Sweden)

    Sajjad Mithiborwala

    2012-01-01

    Full Text Available Background and Objective : Restoration of carious lesions with a strong permanent bond would be a highly desirable requisite. Ultra morphological characterization shows that observing and understanding the interfacial phenomenon and its quality would be of great importance in the selection of a dental adhesive for its use in pediatric restorative dentistry. Study design : Human primary molars, indicated for extraction, for reasons like caries, normal exfoliation, pathological root resorption, over-retained and serial extraction, were collected. Teeth were then equally distributed into 2 subgroups each namely B1 - Prime and Bond NT & B2 - Xeno III. Results : The resin tags seen in the samples of group B2 were both qualitatively and quantitatively advanced as compared to group B1. This reveals that the quality of the penetration of the resin was better in group B2. Conclusion : Reduction in the technique sensitivity of any bonding system would always be a preferred factor in pediatric restorative dentistry. Thus the inclination towards the selection of adhesive system may lean towards the self-etching bonding system at this juncture.

  11. The influence of H2O2 concentration to the structure of silicon nanowire growth by metal-assisted chemical etching

    Science.gov (United States)

    Omar, Hafsa; Jani, Abdul Mutalib Md.; Rusop, Mohamad; Abdullah, Saifollah

    2016-07-01

    A simple and low cost method to produce well aligned silicon nanowires at large areas using Ag-assisted chemical etching at room temperature were presented. The structure of silicon nanowires growth by metal-assisted chemical etching was observed. Prior to the etching, the silicon nanowires were prepared by electroless metal deposited (EMD) in solution containing hydrofluoric acid and hydrogen peroxide in Teflon vessel. The silver particle was deposited on substrate by immersion in hydrofluoric acid and silver nitrate solution for sixty second. The silicon nanowires were growth in different hydrogen peroxide concentration which are 0.3M, 0.4M, 0.5M and 0.6M and 0.7M.The influence of hydrogen peroxide concentration to the formation of silicon nanowires was studied. The morphological properties of silicon nanowires were investigated using field emission scanning electron microscopy (FESEM) and Energy Dispersive X-Ray Spectroscopy (EDS).

  12. History of dental hygiene research.

    Science.gov (United States)

    Bowen, Denise M

    2013-01-01

    Dental hygiene is defined as the science and practice of the recognition, treatment and prevention of oral diseases. The history of dental hygiene research is considered in the context of the development of the discipline and an emerging infrastructure. Research-related events supporting the growth and maturation of the profession are considered from the early years to the most recent. The benefits of preventive oral health services provided by dental hygienists have been supported by research, and the practice of dental hygiene has expanded as a result of research findings since its inception 100 years ago. Dental hygienists' engagement in research, however, did not begin until the 1960s as research associates or administrators, primarily with dental researchers as primary investigators. The Journal of Dental Hygiene (JDH) has provided information for dental hygiene practice since 1927, and has been the primary venue for dissemination of dental hygiene research since 1945. Graduate education in dental hygiene at the master's degree level and the work of early dental hygiene researchers led to the first conference on dental hygiene research in 1982. Over 30 years later, dental hygiene has established a meta-paradigm and defined conceptual models, built an initial infrastructure to support research endeavors and contributed much to the development of dental hygiene as a unique discipline. A doctoral degree in the discipline, continued theory-based research, initiatives to foster collaborations between dental hygiene and other researchers and enhanced capabilities to attract funding to support large scale studies are goals that must be attained through the efforts of future researchers to address the needs for additional development in the discipline of dental hygiene. Dental hygiene research supports the growing discipline and its value to society.

  13. Efficient visible luminescence of nanocrystalline silicon prepared from amorphous silicon films by thermal annealing and stain etching

    Directory of Open Access Journals (Sweden)

    Nikulin Valery

    2011-01-01

    Full Text Available Abstract Films of nanocrystalline silicon (nc-Si were prepared from hydrogenated amorphous silicon (a-Si:H by using rapid thermal annealing. The formed nc-Si films were subjected to stain etching in hydrofluoric acid solutions in order to passivate surfaces of nc-Si. The optical reflectance spectroscopy revealed the nc-Si formation as well as the high optical quality of the formed films. The Raman scattering spectroscopy was used to estimate the mean size and volume fraction of nc-Si in the annealed films, which were about 4 to 8 nm and 44 to 90%, respectively, depending on the annealing regime. In contrast to as-deposited a-Si:H films, the nc-Si films after stain etching exhibited efficient photoluminescence in the spectral range of 600 to 950 nm at room temperature. The photoluminescence intensity and lifetimes of the stain etched nc-Si films were similar to those for conventional porous Si formed by electrochemical etching. The obtained results indicate new possibilities to prepare luminescent thin films for Si-based optoelectronics.

  14. Method for Fabricating Textured High-Haze ZnO:Al Transparent Conduction Oxide Films on Chemically Etched Glass Substrates.

    Science.gov (United States)

    Park, Hyeongsik; Nam, Sang-Hun; Shin, Myunghun; Ju, Minkyu; Lee, Youn-Jung; Yu, Jung-Hoon; Jung, Junhee; Kim, Sunbo; Ahn, Shihyun; Boo, Jin-Hyo; Yi, Junsin

    2016-05-01

    We developed a technique for forming textured aluminum-doped zinc oxide (ZnO:Al) transparent conductive oxide (TCO) films on glass substrates, which were etched using a mixture of hydrofluoric (HF) and hydrochloric (HCl) acids. The etching depth and surface roughness increased with an increase in the HF content and the etching time. The HF-based residues produced insoluble hexafluorosilicate anion- and oxide impurity-based semipermeable films, which reduced the etching rate. Using a small amount of HCl dissolved the Ca compounds, helping to fragment the semipermeable film. This formed random, complex structures on the glass substrates. The angled deposition of three layers of ZnO:Al led to the synthesis of multiscaled ZnO:Al textures on the glass substrates. The proposed approach resulted in textured ZnO:Al TCO films that exhibited high transmittance (-80%) and high haze (> 40%) values over wavelengths of 400-1000 nm, as well as low sheet resistances (ZnO:Al textured TCO films exhibited photocurrents and cell efficiencies that were 40% higher than those of cells with conventional TCO films.

  15. Effects of etching time on the bottom surface morphology of ultrathin porous alumina membranes for use as masks

    Science.gov (United States)

    Yang, Sun A.; Choi, Yong Chan; Bu, Sang Don

    2012-11-01

    We investigated the effect of etching time on the bottom surface morphologies of ultrathin porous alumina membranes (UT-PAMs) anodized in oxalic and phosphoric acid. The morphology of the bottom surface clearly changed and a unique surface undulation was observed during the etching process. Such an undulation regarding the bottom surface is attributed to the different etching rates between the dome-shaped barrier layer and the hexagonal cell walls. The results suggest that the bottom morphology of UT-PAMs formed after the barrier layer is opened significantly affects the contact area of the bottom side with the substrate. During the initial stage of the opening process for the barrier layer, the porous section will contact the substrate rather than the walls. However, as the etching time increases, the height of the porous section becomes considerably lower than that of the walls, which means that the walls will contact the substrate with a gap between the pores and the substrate. Based on our experimental results, we propose a possible schematic diagram describing the effects of UT-PAMs with differently-shaped bottom surfaces on the shapes of fabricated nanodots when the UT-PAMs are used as masks.

  16. Environmental scanning electron microscopy of hydrated conditioned/etched dentine.

    Science.gov (United States)

    de Wet, F A; van der Vyver, P J; Eick, J D; Dusevich, V M

    2000-11-01

    Various etchants/conditioners are used during dental treatment to affect or remove the smear layer. The purpose of this study was to evaluate the effect of different treatments on moist dentine, using a field emission environmental scanning electron microscope (FE-ESEM). Twenty freshly extracted, human molar teeth were utilised. The roots and pulps were removed, and the crowns horizontally sectioned with a low speed diamond saw (Isomet) (with cooling in a saline solution) in order to expose superficial dentine. A smear layer was created on these surfaces by using 600 grit silicone carbide paper. Test surfaces were then treated in one of the following ways: 1. 37% phosphoric acid liquid 2. 37% phosphoric acid gel 3. NRC (non-rinse conditioner) without rinsing 4. NRC with rinsing. Shallow grooves were cut on the untreated sides, using a thin diamond bur. This enabled the samples to be split in half when pressure was applied in the grooves. Samples were maintained moist throughout specimen preparation. Samples were examined in the FE-ESEM (Philips XL 30) in such a way that the effect of the treatment could be viewed occlusally, as well as perpendicular to the treated interface. Phosphoric acid liquid and gel removed the smear layer, and demineralised the dentine for approximately 5-10 micrometers. NRC penetrated the smear layer and modified it to a lesser degree. However, washing of the NRC treated surface removed part of the smear layer, and opened up some dentinal tubules. Excellent resolution was possible with the FE-ESEM in both the wet and dry modes.

  17. DENTAL HOT-COLD SENSITIVITY AND TRAUMATIC DENTAL INJURIES

    OpenAIRE

    Traebert, Jefferson; Martins,Luiz Gustavo Teixeira; Traebert, Eliane Silva de Azevedo; Bortoluzzi, Marcelo Carlos

    2014-01-01

    AIM: Although several studies have indicated negative impacts of traumatic dental injuries on children’s quality of life, virtually none of them have explored the possible association between them and the occurrence and dental hot-cold sensitivity. The aim of this study was to study the possible association of hot-cold dental sensitivity and history of traumatic dental injuries. MATERIAL AND METHODS: A cross-sectional study involving a representative sample of 11- to 14-year-old schoolchildre...

  18. In vitro and in vivo studies of ultrafine-grain Ti as dental implant material processed by ECAP.

    Science.gov (United States)

    An, Baili; Li, Zhirui; Diao, Xiaoou; Xin, Haitao; Zhang, Qiang; Jia, Xiaorui; Wu, Yulu; Li, Kai; Guo, Yazhou

    2016-10-01

    The aim of this study was to investigate the surface characterization of ultrafine-grain pure titanium (UFG-Ti) after sandblasting and acid-etching (SLA) and to evaluate its biocompatibility as dental implant material in vitro and in vivo. UFG-Ti was produced by equal channel angular pressing (ECAP) using commercially pure titanium (CP-Ti). Microstructure and yield strength were investigated. The morphology, wettability and roughness of the specimens were analyzed after they were modified by SLA. MC3T3-E1 osteoblasts were seeded onto the specimens to evaluate its biocompatibility in vitro. For the in vivo study, UFG-Ti implants after SLA were embedded into the femurs of New Zealand rabbits. Osseointegration was investigated though micro-CT analysis, histological assessment and pull-out test. The control group was CP-Ti. UFG-Ti with enhanced mechanical properties was produced by four passes of ECAP in BC route at room temperature. After SLA modification, the hierarchical porous structure on its surface exhibited excellent wettability. The adhesion, proliferation and viability of cells cultured on the UFG-Ti were superior to that of CP-Ti. In the in vivo study, favorable osseointegration occurred between the implant and bone in CP and UFG-Ti groups. The combination intensity of UF- Ti with bone was higher according to the pull-out test. This study supports the claim that UFG-Ti has grain refinement with outstanding mechanical properties and, with its excellent biocompatibility, has potential for use as dental implant material.

  19. Comparison of acidulated phosphate fluoride gel and hydrofluoric acid etchants for porcelain-composite repair.

    Science.gov (United States)

    Tylka, D F; Stewart, G P

    1994-08-01

    Hydrofluoric acid etches porcelain to produce a porous surface visible under scanning electron microscopy when compared to an acidulated phosphate fluoride gel. Some investigators have suggested the greater porosity of the hydrofluoric acid etch produces a greater composite-to-porcelain bond. This investigation tested that assumption with two common fluoride etchants. The etched surfaces were first viewed under scanning electron microscopy to ensure that a characteristic etch was achieved. Both etchants yielded bond strengths that produced cohesive failure of all samples. This suggested that the intraoral use of hydrofluoric acid is no more effective than the less dangerous acidulated phosphate fluoride gel.

  20. A high efficiency industrial polysilicon solar cell with a honeycomb-like surface fabricated by wet etching using a photoresist mask

    Science.gov (United States)

    Zhang, Hong; Ding, Bin; Chen, Tianhang

    2016-11-01

    In this paper, an effective and low cost method of texturization was introduced into the fabrication process for industrial multicrystalline silicon solar cell production. The purpose of the method was to reduce reflectance by creating a honeycomb-like textured surface using a masked wet etching process. A negative photoresist film was selected as an etching mask. Although large surface roughness of wafer was considered to affect the adhesion and acid resistance of etching mask, a honeycomb-like textured surface with a pitch of 18 μm was fabricated successfully. The etched pits had a nearly smooth spherical segment surface, an average aperture of 15.1 μm, and a depth of 6.5 μm. This regular textured surface had a low light reflectivity of approximately 20.5% and greatly increased the carrier lifetime. Compared with multicrystalline silicon solar cells textured by conventional acid etching, the average short circuit current increased by 2.2% and the average efficiency increased from 17.41% to 17.75%, a net gain of 0.34%. And a high throughput above 2400 pieces per hour was obtained. This texturing technique is expected to promote the application of diamond-wire cut multicrystalline silicon wafers with the low saw-damage in the future.

  1. Range and etching behaviour of swift heavy ions in polymers

    Science.gov (United States)

    Singh, Lakhwant; Singh, Mohan; Samra, Kawaljeet Singh; Singh, Ravinder

    Aliphatic (CR-39) and aromatic (Lexan polycarbonate) polymers have been irradiated with a variety of heavy ions such as 58Ni, 93Nb, 132Xe, 139La, 197Au, 208Pb, 209Bi, and 238U having energy ranges of 5.60-8.00 MeV/n in order to study the range and etching kinetics of heavy ion tracksE The ion fluence (range ˜104-105 ions/cm2) was kept low to avoid the overlapping of etched tracks. The measured values of maximum etched track length were corrected due to bulk etching and over etching to obtain the actual range. The experimental results of range profiles were compared with those obtained by the most used procedures employed in obtaining range and stopping power. The range values of present ions have been computed using the semiempirical codes (SRIM-98, SRIM-2003.26, and LISE++:0-[Hub90]) in order to check their accuracy. The merits and demerits of the adopted formulations have been highlighted in the present work. It is observed that the range of heavy ions is greater in aromatic polymers (Lexan polycarbonate) as compared to the aliphatic polymers (CR-39) irradiated with similar ions having same incident energies. The SRIM-98 and SRIM2003.26 codes don't show any significant trend in deviations, however, LISE++:0-[Hub90] code provides overall good agreement with the experimental values. The ratio of track etch rate (along projectile trajectory) to the bulk etch rate has also been studied as a function of energy loss of heavy ions in these polymers.

  2. Chemical etching to dissolve dislocation cores in multicrystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Gregori, N.J. [Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH (United Kingdom); Murphy, J.D., E-mail: john.murphy@materials.ox.ac.uk [Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH (United Kingdom); Sykes, J.M.; Wilshaw, P.R. [Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH (United Kingdom)

    2012-08-01

    Multicrystalline silicon wafers are used for approximately half of all solar cells produced at present. These wafers typically have dislocation densities of up to {approx}10{sup 6} cm{sup -2}. Dislocations and associated impurities act as strong recombination centres for electron-hole pairs and are one of the major limiting factors in multicrystalline silicon substrate performance. In this work we have explored the possibility of using chemical methods to etch out the cores of dislocations from mc-Si wafers. We aim to maximise the aspect ratio of the depth of the etched structure to its diameter. We first investigate the Secco etch (1K{sub 2}Cr{sub 2}O{sub 7} (0.15 M): 2HF (49%)) as a function of time and temperature. This etch removes material from dislocation cores much faster than grain boundaries or the bulk, and produces tubular holes at dislocations. Aspect ratios of up to {approx}7:1 are achieved for {approx}15 {mu}m deep tubes. The aspect ratio decreases with tube depth and for {approx}40 {mu}m deep tubes is just {approx}2:1, which is not suitable for use in bulk multicrystalline silicon photovoltaics. We have also investigated a range of etches based on weaker oxidising agents. An etch comprising 1I{sub 2} (0.01 M): 2HF (49%) attacked dislocation cores, but its etching behaviour was extremely slow (<0.1 {mu}m/h) and the pits produced had a low aspect ratio (<2:1).

  3. Bulimia and Anorexia Nervosa in Dental and Dental Hygiene Curricula.

    Science.gov (United States)

    Gross, Karen B. W.; And Others

    1990-01-01

    Dentists and dental hygienists are in a unique position to identify an eating disorder patient from observed oral manifestations and to refer the patient for psychological therapy. The inclusion of information on general and oral complications of bulimia and anorexia nervosa in dental and dental hygiene curriculum was examined. (MLW)

  4. Blood Thinners and Dental Care

    Science.gov (United States)

    ... a Doctor Patient Condition Information Publications & News OOOO Journal Newsroom Clinicians’ Guides Clinical Practice Statements Newsletters Latest ... Meeting Orlando, FL Our Partners Blood Thinners and Dental Care Many dental patients are taking “blood thinner” ...

  5. Dental modification in the past

    DEFF Research Database (Denmark)

    Bennike, Pia; Alexandersen, Verner

    2003-01-01

    Skeleton remains from Denmark, Greenland, Faeroe Islands, dental care, drillling in the past, tooth extraction......Skeleton remains from Denmark, Greenland, Faeroe Islands, dental care, drillling in the past, tooth extraction...

  6. 77 FR 4469 - Dental Conditions

    Science.gov (United States)

    2012-01-30

    ... purposes. This amendment clarifies that principles governing determinations by VA's Veterans Benefits Administration (VBA) for service connection of dental conditions for the purpose of establishing eligibility for dental treatment by VA's Veterans Health Administration (VHA), apply only when VHA requests...

  7. Panoramic Dental X-Ray

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Panoramic Dental X-ray Panoramic dental x-ray uses a ... Your e-mail address: Personal message (optional): Bees: Wax: Notice: RadiologyInfo respects your privacy. Information entered here ...

  8. Dental Care - Medicaid and Chip

    Data.gov (United States)

    U.S. Department of Health & Human Services — Dental health is an important part of peoples overall health. States are required to provide dental benefits to children covered by Medicaid and the Childrens Health...

  9. Anisotropic fluorocarbon plasma etching of silicon/silicon germanide heterostructures and plasma etching-induced sidewall damage

    Science.gov (United States)

    Ding, Ruhang

    Plasma etching is a critical tool in the fabrication of Si/SiGe heterostructure quantum devices, but with challenges addressed herein, including (1) control of etch profiles and (2) damage to etched feature sidewalls that affects device performance. (1) Fluorocarbon-based plasma etching often results in device profiles with undercuts due to preferential etching of SiGe over silicon. A C4F8/N2/Ar etch plasma gas mixture introduced here has been successfully used to achieve straight sidewalls through heterostructure layers by formation of a fluorocarbon inhibitor film on feature sidewalls to prevent undercutting. (2) Chemical and structural changes in the semiconductor at feature sidewalls associated with plasma-surface interactions are considered damage, as they affect band structure and electrical conduction in the active region of the device, known as the 2-dimensional electron gas (2DEG). In experiments designed to better understand the mechanisms of plasma-induced sidewall damage, damage to straight wires was characterized both by the width of a non-conductive "sidewall depletion" region at the device sidewall, and by the noise level factor, gamma H/N, determined from spectra of low frequency noise. Observed increases in sidewall depletion width with increasing etch depth are tentatively attributed to the increase in total number of defects with increased plasma exposure time. Excess negative charge incorporated into the fluorocarbon inhibitor film could be another contributing factor. Other factors considered, including defects at the bottom of etched features as well as leakage current bypassing the wire, are ruled out as their contribution is expected to diminish as the distance between the 2DEG and feature bottom increases. The noise level factor, gammaH /N, shows a maximum with increasing etch depth, possibly the result of two competing effects: increasing ion dose and decreasing leakage current. The noise level shows a minimum at an ion bombardment energy

  10. Recovery of silver residues from dental amalgam

    Directory of Open Access Journals (Sweden)

    Heloísa Aparecida Barbosa da Silva Pereira

    2010-04-01

    Full Text Available Dental amalgam residues are probably the most important chemical residues generated from clinical dental practice because of the presence of heavy metals among its constituents, mainly mercury and silver. OBJECTIVE: The purpose of this study was to develop an alternative method for the recovery of silver residues from dental amalgam. MATERIAL AND METHODS: The residue generated after vacuum distillation of dental amalgam for the separation of mercury was initially diluted with 32.5% HNO3, followed by precipitation with 20% NaCl. Sequentially, under constant heating and agitation with NaOH and sucrose, the sample was reduced to metallic silver. However, the processing time was too long, which turned this procedure not viable. In another sequence of experiments, the dilution was accomplished with concentrated HNO3 at 90ºC, followed by precipitation with 20% NaCl. After washing, the pellet was diluted with concentrated NH4OH, water and more NaCl in order to facilitate the reaction with the reducer. RESULTS: Ascorbic acid was efficiently used as reducer, allowing a fast reduction, thus making the procedure viable. CONCLUSIONS: The proposed methodology is of easy application and does not require sophisticated equipment or expensive reagents.

  11. Characterization of electric discharge machining, subsequent etching and shot-peening as a surface treatment for orthopedic implants

    Energy Technology Data Exchange (ETDEWEB)

    Stráský, Josef, E-mail: josef.strasky@gmail.com [Charles University, Department of Physics of Materials (Czech Republic); Havlíková, Jana; Bačáková, Lucie [Institute of Physiology, Academy of Sciences of the Czech Republic (Czech Republic); Harcuba, Petr [Charles University, Department of Physics of Materials (Czech Republic); Mhaede, Mansour [Clausthal University of Technology, Institute of Materials Science and Engineering (Germany); Faculty of Engineering, Zagazig University (Egypt); Janeček, Miloš [Charles University, Department of Physics of Materials (Czech Republic)

    2013-09-15

    Presented work aims at multi-method characterization of combined surface treatment of Ti–6Al–4V alloy for biomedical use. Surface treatment consists of consequent use of electric discharge machining (EDM), acid etching and shot peening. Surface layers are analyzed employing scanning electron microscopy and energy dispersive X-ray spectroscopy. Acid etching by strong Kroll's reagent is capable of removing surface layer of transformed material created by EDM. Acid etching also creates partly nanostructured surface and significantly contributes to the enhanced proliferation of the bone cells. The cell growth could be positively affected by the superimposed bone-inspired structure of the surface with the morphological features in macro-, micro- and nano-range. Shot peening significantly improves poor fatigue performance after EDM. Final fatigue performance is comparable to benchmark electropolished material without any adverse surface effect. The proposed three-step surface treatment is a low-cost process capable of producing material that is applicable in orthopedics.

  12. Zirconia as a Dental Biomaterial

    OpenAIRE

    Alvaro Della Bona; Pecho, Oscar E.; Rodrigo Alessandretti

    2015-01-01

    Ceramics are very important in the science of dental biomaterials. Among all dental ceramics, zirconia is in evidence as a dental biomaterial and it is the material of choice in contemporary restorative dentistry. Zirconia has been applied as structural material for dental bridges, crowns, inserts, and implants, mostly because of its biocompatibility, high fracture toughness, and radiopacity. However, the clinical success of restorative dentistry has to consider the adhesion to different subs...

  13. Oriented and Ordered Biomimetic Remineralization of the Surface of Demineralized Dental Enamel Using HAP@ACP Nanoparticles Guided by Glycine

    Science.gov (United States)

    Wang, Haorong; Xiao, Zuohui; Yang, Jie; Lu, Danyang; Kishen, Anil; Li, Yanqiu; Chen, Zhen; Que, Kehua; Zhang, Qian; Deng, Xuliang; Yang, Xiaoping; Cai, Qing; Chen, Ning; Cong, Changhong; Guan, Binbin; Li, Ting; Zhang, Xu

    2017-01-01

    Achieving oriented and ordered remineralization on the surface of demineralized dental enamel, thereby restoring the satisfactory mechanical properties approaching those of sound enamel, is still a challenge for dentists. To mimic the natural biomineralization approach for enamel remineralization, the biological process of enamel development proteins, such as amelogenin, was simulated in this study. In this work, carboxymethyl chitosan (CMC) conjugated with alendronate (ALN) was applied to stabilize amorphous calcium phosphate (ACP) to form CMC/ACP nanoparticles. Sodium hypochlorite (NaClO) functioned as the protease which decompose amelogenin in vivo to degrade the CMC-ALN matrix and generate HAP@ACP core-shell nanoparticles. Finally, when guided by 10 mM glycine (Gly), HAP@ACP nanoparticles can arrange orderly and subsequently transform from an amorphous phase to well-ordered rod-like apatite crystals to achieve oriented and ordered biomimetic remineralization on acid-etched enamel surfaces. This biomimetic remineralization process is achieved through the oriented attachment (OA) of nanoparticles based on non-classical crystallization theory. These results indicate that finding and developing analogues of natural proteins such as amelogenin involved in the biomineralization by natural macromolecular polymers and imitating the process of biomineralization would be an effective strategy for enamel remineralization. Furthermore, this method represents a promising method for the management of early caries in minimal invasive dentistry (MID).

  14. Oriented and Ordered Biomimetic Remineralization of the Surface of Demineralized Dental Enamel Using HAP@ACP Nanoparticles Guided by Glycine

    Science.gov (United States)

    Wang, Haorong; Xiao, Zuohui; Yang, Jie; Lu, Danyang; Kishen, Anil; Li, Yanqiu; Chen, Zhen; Que, Kehua; Zhang, Qian; Deng, Xuliang; Yang, Xiaoping; Cai, Qing; Chen, Ning; Cong, Changhong; Guan, Binbin; Li, Ting; Zhang, Xu

    2017-01-01

    Achieving oriented and ordered remineralization on the surface of demineralized dental enamel, thereby restoring the satisfactory mechanical properties approaching those of sound enamel, is still a challenge for dentists. To mimic the natural biomineralization approach for enamel remineralization, the biological process of enamel development proteins, such as amelogenin, was simulated in this study. In this work, carboxymethyl chitosan (CMC) conjugated with alendronate (ALN) was applied to stabilize amorphous calcium phosphate (ACP) to form CMC/ACP nanoparticles. Sodium hypochlorite (NaClO) functioned as the protease which decompose amelogenin in vivo to degrade the CMC-ALN matrix and generate HAP@ACP core-shell nanoparticles. Finally, when guided by 10 mM glycine (Gly), HAP@ACP nanoparticles can arrange orderly and subsequently transform from an amorphous phase to well-ordered rod-like apatite crystals to achieve oriented and ordered biomimetic remineralization on acid-etched enamel surfaces. This biomimetic remineralization process is achieved through the oriented attachment (OA) of nanoparticles based on non-classical crystallization theory. These results indicate that finding and developing analogues of natural proteins such as amelogenin involved in the biomineralization by natural macromolecular polymers and imitating the process of biomineralization would be an effective strategy for enamel remineralization. Furthermore, this method represents a promising method for the management of early caries in minimal invasive dentistry (MID). PMID:28079165

  15. Effect of Self-etch Adhesives on Self-sealing Ability of High-Copper Amalgams

    Directory of Open Access Journals (Sweden)

    Saied Mostafa Moazzami

    2016-12-01

    Full Text Available Statement of the Problem: Similar to conventional amalgam, high-copper amalgam alloy may also undergo corrosion, but it takes longer time for the resulting products to reduce microleakage by sealing the micro-gap at the tooth/amalgam interface. Purpose: The aim of this study was to evaluate the effect of self-etch adhesives with different pH levels on the interfacial corrosion behavior of high-copper amalgam restoration and its induction potential for self-sealing ability of the micro-gap in the early hours after setting by means of Electro-Chemical Tests (ECTs. Materials and Method: Thirty cylindrical cavities of 4.5mm x 4.7mm were prepared on intact bicuspids. The samples were divided into five main groups of application of Adhesive Resin (AR/ liner/ None (No, on the cavity floor. The first main group was left without an AR/ liner (No. In the other main groups, the types of AR/ liner used were I-Bond (IB, Clearfil S3 (S3, Single Bond (SB and Varnish (V. Each main group (n=6 was divided into two subgroups (n=3 according to the types of the amalgams used, either admixed ANA 2000 (ANA or spherical Tytin (Tyt. The ECTs, Open Circuit Potential (OCP, and the Linear Polarization Resistance (LPR for each sample were performed and measured 48 hours after the completion of the samples. Results: The Tyt-No and Tyt-IB samples showed the highest and lowest OCP values respectively. In LPR tests, the Rp values of ANA-V and Tyt-V were the highest (lowest corrosion rate and contrarily, the ANA-IB and Tyt-IB samples, with the lowest pH levels, represented the lowest Rp values (highest corrosion rates. Conclusion: Some self-etch adhesives may increase interfacial corrosion potential and self-sealing ability of high-copper amalgams. Keywords ● Electrochemical Test ● Dental Amalgam ● Corrosion ● Self-etch adhesive;

  16. Dental ethics and emotional intelligence.

    Science.gov (United States)

    Rosenblum, Alvin B; Wolf, Steve

    2014-01-01

    Dental ethics is often taught, viewed, and conducted as an intell enterprise, uninformed by other noncognitive factors. Emotional intelligence (EQ) is defined distinguished from the cognitive intelligence measured by Intelligence Quotient (IQ). This essay recommends more inclusion of emotional, noncognitive input to the ethical decision process in dental education and dental practice.

  17. Dental operatory design and equipment.

    Science.gov (United States)

    Floyd, M

    1993-08-01

    Improving and expanding the dental services of a practice can involve purchasing new equipment and even modifying or expanding the physical plant. Operatory design is important to the efficiency with which dental procedures can be performed. Equipment purchases to outfit the dental operatory should be made based on the specific needs and functions of a practice.

  18. Dental Hygiene Realpolitik Affecting Education.

    Science.gov (United States)

    Bader, James D.

    1991-01-01

    Current conditions in dental hygiene influencing professional education are discussed. Workplace/practice issues include dental hygiene care as a component of dental practice, content, effects, and quality of care, hygienist supply and demand, and job satisfaction. Professional issues include the knowledge base, definitions of practice, and…

  19. Performance of a universal adhesive on etched and non-etched surfaces: Do the results match the expectations?

    Energy Technology Data Exchange (ETDEWEB)

    Grégoire, Geneviève, E-mail: genevieve.gregoire@univ-tlse3.fr [Department of Biomaterials, Faculty of Odontology, University Toulouse III, 31062 Toulouse (France); Sharrock, Patrick, E-mail: patrick.sharrock@gmail.com [CNRS UMR 5302, University Toulouse III, Mines-Albi, 81013 Albi (France); Prigent, Yann, E-mail: prigent@chimie.ups-tlse.fr [Institut de Chimie de Toulouse (ICT) – FR 2599, Faculté des Sciences et de l' Ingénierie, University Toulouse III, 31062 Toulouse (France)

    2016-09-01

    A universal adhesive was applied to human dentin in both the etched and rinsed state and the normal non etched state, to compare the resulting properties and detect any significant differences. The study focused on observations of the hybrid layer by scanning electron microscopy and on fluid permeation measurements as a function of time. Spectroscopic characterizations included infrared and differential calorimetric curves of the samples. The results obtained show non-statistically significant fluid permeability between the two sample types. Both the etched and rinsed samples and the non-etched ones showed similar homogeneous hybrid layers that reduced the fluid flow, and corresponded to well spread polymer coatings. The infrared results illustrated the spectra obtained on going from the outside adhesive layer to the inside portion of the dentin-polymer interface and did not reveal any intermediate zone resembling demineralized collagen that would be water saturated and not infiltrated with adhesive. The Differential Scanning Calorimetry (DSC) curves corresponded to the curves obtained with ethanol wet bonding in that free water (melting at 0 °C) was removed by the universal adhesive, and that no collagen melting was observed for the non-etched samples. The Diffusion-Ordered Spectroscopy Nuclear Magnetic Resonance (DOSY NMR) spectrum of the virgin adhesive showed the presence of water and ethanol solvents and indicated that several monomer or prepolymer molecules were present with multiple acrylic functional groups with diffusion coefficients related to molecular weights. Overall, the results show that universal adhesive can be used in the milder self-etch mode and that more aggressive etch and rinse procedure can be reserved for the occasions with sclerotic dentin or enamel regions more difficult to treat.

  20. Effect of different disinfection protocols on microbial and biofilm contamination of dental unit waterlines in community dental practices.

    Science.gov (United States)

    Dallolio, Laura; Scuderi, Amalia; Rini, Maria S; Valente, Sabrina; Farruggia, Patrizia; Sabattini, Maria A Bucci; Pasquinelli, Gianandrea; Acacci, Anna; Roncarati, Greta; Leoni, Erica

    2014-02-18

    Output water from dental unit waterlines (DUWLs) may be a potential source of infection for both dental healthcare staff and patients. This study compared the efficacy of different disinfection methods with regard to the water quality and the presence of biofilm in DUWLs. Five dental units operating in a public dental health care setting were selected. The control dental unit had no disinfection system; two were disinfected intermittently with peracetic acid/hydrogen peroxide 0.26% and two underwent continuous disinfection with hydrogen peroxide/silver ions (0.02%) and stabilized chlorine dioxide (0.22%), respectively. After three months of applying the disinfection protocols, continuous disinfection systems were more effective than intermittent systems in reducing the microbial contamination of the water, allowing compliance with the CDC guidelines and the European Council regulatory thresholds for drinking water. P. aeruginosa, Legionella spp, sulphite-reducing Clostridium spores, S. aureus and β-haemolytic streptococci were also absent from units treated with continuous disinfection. The biofilm covering the DUWLs was more extensive, thicker and more friable in the intermittent disinfection dental units than in those with continuous disinfection. Overall, the findings showed that the products used for continuous disinfection of dental unit waterlines showed statistically better results than the intermittent treatment products under the study conditions.

  1. Effect of Different Disinfection Protocols on Microbial and Biofilm Contamination of Dental Unit Waterlines in Community Dental Practices

    Directory of Open Access Journals (Sweden)

    Laura Dallolio

    2014-02-01

    Full Text Available Output water from dental unit waterlines (DUWLs may be a potential source of infection for both dental healthcare staff and patients. This study compared the efficacy of different disinfection methods with regard to the water quality and the presence of biofilm in DUWLs. Five dental units operating in a public dental health care setting were selected. The control dental unit had no disinfection system; two were disinfected intermittently with peracetic acid/hydrogen peroxide 0.26% and two underwent continuous disinfection with hydrogen peroxide/silver ions (0.02% and stabilized chlorine dioxide (0.22%, respectively. After three months of applying the disinfection protocols, continuous disinfection systems were more effective than intermittent systems in reducing the microbial contamination of the water, allowing compliance with the CDC guidelines and the European Council regulatory thresholds for drinking water. P. aeruginosa, Legionella spp, sulphite-reducing Clostridium spores, S. aureus and β-haemolytic streptococci were also absent from units treated with continuous disinfection. The biofilm covering the DUWLs was more extensive, thicker and more friable in the intermittent disinfection dental units than in those with continuous disinfection. Overall, the findings showed that the products used for continuous disinfection of dental unit waterlines showed statistically better results than the intermittent treatment products under the study conditions.

  2. A novel restricted-flow etching method for glass

    Institute of Scientific and Technical Information of China (English)

    Hai-bo XIE; Yi ZHENG; Yu-run FAN; Xin FU; Hua-yong YANG

    2009-01-01

    This paper presents a novel micro fabrication method based on the laminar characteristics of micro-scale flows. Therein the separator and etchant are alternatively arranged in micro channels to form multiple laminar streams, and the etchant is located at the site where the reaction is supposed to occur. This new micro fabrication process can be used for the high aspect ratio etching inside a microchannel on glass substrates. Furthermore, the topography of microstructure patterned by this method can be controlled by changing the flow parameters of the separator and etchant. Experiments on the effects of flow parameters on the aspect ratio, side wall profile and etching rate were carried out on a glass substrate. The effect of flow rates on the etching rate and the micro topography was analyzed, in addition, experiments with dynamical changes of the flow rate ratio of the separator and etchant showed that the verticality of the side walls of microstructures can be significantly improved. The restricted flowing etching technique not only abates the isotropic effect in the traditional wet etching but also significantly reduces the dependence on expensive photolithographic equipment.

  3. Singular Sheet Etching of Graphene with Oxygen Plasma

    Institute of Scientific and Technical Information of China (English)

    Haider Al-Mumen; Fubo Rao; Wen Li; Lixin Dong

    2014-01-01

    This paper reports a simple and controllable post-synthesis method for engineering the number of graphene layers based on oxygen plasma etching. Singular sheet etching (SSE) of graphene was achieved with the optimum process duration of 38 seconds. As a demonstration of this SSE process, monolayer graphene films were produced from bilayer graphenes. Experimental investigations verified that the oxygen plasma etching removes a single layer graphene sheet in an anisotropic fashion rather than anisotropic mode. In addition, etching via the oxygen plasma at the ground electrodes introduced fewer defects to the bottom graphene layer compared with the conventional oxygen reactive ion etching using the powered electrodes. Such defects can further be reduced with an effective annealing treatment in an argon environment at 900-1000◦C. These results demonstrate that our developed SSE method has enabled a microelectronics manufacturing compatible way for single sheet precision subtraction of graphene layers and a potential technique for producing large size graphenes with high yield from multilayer graphite materials.

  4. Innovative, Inexpensive Etching Technique Developed for Polymer Electro- Optical Structures

    Science.gov (United States)

    Nguyen, Hung D.

    1999-01-01

    Electro-optic, polymer-based integrated optic devices for high-speed communication and computing applications offer potentially significant advantages over conventional inorganic electro-optic crystals. One key area of integrated optical technology--primary processing and fabrication--may particularly benefit from the use of polymer materials. However, as efforts concentrate on the miniaturization of electro-integrated circuit pattern geometries, the ability to etch fine features and smoothly sloped sidewalls is essential to make polymers useful for electro-integrated circuit applications. There are many existing processes available to etch polymer materials, but they all yield nearly vertical sidewalls. Vertical sidewalls are too difficult to reliably cover with a metal layer, and incomplete metalization degrades microwave performance, particularly at high frequency. However, obtaining a very sloped sidewall greatly improves the deposition of metal on the sidewall, leading to low-loss characteristics, which are essential to integrating these devices in highspeed electro-optic modulators. The NASA Lewis Research Center has developed in-house an inexpensive etching technique that uses a photolithography method followed by a simple, wet chemical etching process to etch through polymer layers. In addition to being simpler and inexpensive, this process can be used to fabricate smoothly sloped sidewalls by using a commercial none rodible mask: Spin-On-Glass. A commercial transparent material, Spin-On-Glass, uses processes and equipment similar to that for photoresist techniques.

  5. Environmental photostability of SF6-etched silicon nanocrystals

    Science.gov (United States)

    Liptak, R. W.; Yang, J.; Kramer, N. J.; Kortshagen, U.; Campbell, S. A.

    2012-10-01

    We report on the long-term environmental stability of the photoluminescent (PL) properties of silicon nanocrystals (SiNCs). We prepared sulfur hexafluoride (SF6) etched SiNCs in a two-stage plasma reactor and investigated their PL stability against UV irradiation in air. Unlike SiNCs with hydrogen-passivated surfaces, the SF6-etched SiNCs exhibit no photobleaching upon extended UV irradiation despite surface oxidation. Furthermore, the PL quantum yield also remains stable upon heating the SF6-etched SiNCs up to 160 °C. The observed thermal and UV stability of SF6-etched SiNCs combined with their PL quantum yields of up to ˜50% make them attractive candidates for UV downshifting to enhance the efficiency of solar cells. Electron paramagnetic spin resonance indicates that the SF6-etched SiNCs have a lowered density of defect states, both as-formed and after room temperature oxidation in air.

  6. Dental amalgam: An update

    Directory of Open Access Journals (Sweden)

    Bharti Ramesh

    2010-01-01

    Full Text Available Dental amalgam has served as an excellent and versatile restorative material for many years, despite periods of controversy. The authors review its history, summarize the evidence with regard to its performance and offer predictions for the future of this material. The PubMed database was used initially; the reference list for dental amalgam featured 8641 articles and 13 publications dealing with recent advances in dental amalgam. A forward search was undertaken on selected articles and using some author names. For the present, amalgam should remain the material of choice for economic direct restoration of posterior teeth. When esthetic concerns are paramount, tooth-colored materials, placed meticulously, can provide an acceptable alternative. All alternative restorative materials and procedures, however, have certain limitations.

  7. Dental Implant Complications.

    Science.gov (United States)

    Liaw, Kevin; Delfini, Ronald H; Abrahams, James J

    2015-10-01

    Dental implants have increased in the last few decades thus increasing the number of complications. Since many of these complications are easily diagnosed on postsurgical images, it is important for radiologists to be familiar with them and to be able to recognize and diagnose them. Radiologists should also have a basic understanding of their treatment. In a pictorial fashion, this article will present the basic complications of dental implants which we have divided into three general categories: biomechanical overload, infection or inflammation, and other causes. Examples of implant fracture, loosening, infection, inflammation from subgingival cement, failure of bone and soft tissue preservation, injury to surround structures, and other complications will be discussed as well as their common imaging appearances and treatment. Lastly, we will review pertinent dental anatomy and important structures that are vital for radiologists to evaluate in postoperative oral cavity imaging.

  8. Dental Trauma Guide

    DEFF Research Database (Denmark)

    Andreasen, Jens Ove; Lauridsen, Eva; Gerds, Thomas Alexander

    2012-01-01

    Diagnosis and treatment for traumatic dental injuries are very complex owing to the multiple trauma entities represented by six luxation types and nine fracture types affecting both the primary and the permanent dentition. When it is further considered that fracture and luxation injuries are often...... combined, the result is that more than 100 trauma scenarios exist, when the two dentitions are combined. Each of these trauma scenarios has a specific treatment demand and prospect for healing. With such a complexity in diagnosis and treatment, it is obvious that even experienced practitioners may have...... problems in selecting proper treatment for some of these trauma types. To remedy this situation, an Internet-based knowledge base consisting of 4000 dental trauma cases with long-term follow up is now available to the public and the professions on the Internet using the address http://www.DentalTrauma...

  9. Dental formulations for the prevention of dental erosion

    DEFF Research Database (Denmark)

    2010-01-01

    The invention relates to a therapeutic method for preventing and/or inhibiting dental erosion in a mammalian subject, and the provision of a dental care product for performing the method. The dental care product of the invention comprises a starch-degrading enzyme of E. C. 3.2.1.1, wherein said...... product comprises less than 1 wt.% ionic surfactant, and preferably is substantially free of endoprotease and/or lipase. The properties of the dental care product serve to prevent and/or inhibit dental erosion in a subject that typically results from repeated exposure of the patient's tooth surfaces...

  10. Atomistic simulations of surface coverage effects in anisotropic wet chemical etching of crystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Gosalvez, M.A.; Foster, A.S.; Nieminen, R.M

    2002-12-30

    Atomistic simulations of anisotropic wet chemical etching of crystalline silicon have been performed in order to determine the dependence of the etch rates of different crystallographic orientations on surface coverage and clustering of OH radicals. We show that the etch rate is a non-monotonic function of OH coverage and that there always exists a coverage value at which the etch rate reaches a maximum. The dependence of the anisotropy of the etching process on coverage, including the dependence of the fastest-etched plane orientation, is implicitly contained in the model and predictions of convex corner under-etching structures are made. We show that the whole etching process is controlled by only a few surface configurations involving a particular type of next-nearest neighbours. The relative value of the removal probabilities of these confitions determines the balance in the occurrence of step propagation and etch pitting for all surface orientations.

  11. Microscopic monitoring of extracellular pH in dental biofilms

    DEFF Research Database (Denmark)

    Schlafer, Sebastian; Garcia, Javier; Greve, Matilde

    pH in dental biofilm is a key virulence factor for the development of caries lesions. The complex three-dimensional architecture of dental biofilms leads to steep gradients of nutrients and metabolites, including organic acids, across the biofilm. For decades, measuring pH in dental biofilm has...... been limited to monitoring bulk pH with electrodes. Although pH microelectrodes with a better spatial resolution have been developed, they do not permit to monitor horizontal pH gradients in real-time. Quantitative fluorescent microscopic techniques, such as fluorescence lifetime imaging or pH...... ratiometry, can be employed to map the pH landscape in dental biofilm with more detail. However, when pH sensitive fluorescent probes are used to visualize pH in biofilms, it is crucial to differentiate between extracellular and intracellular pH. Intracellular microbial pH and pH in the extracellular matrix...

  12. [Hardening of dental instruments].

    Science.gov (United States)

    Gerasev, G P

    1981-01-01

    The possibility of prolonging the service life of stomatological instruments by the local hardening of their working parts is discussed. Such hardening should be achieved by using hard and wear-resistant materials. The examples of hardening dental elevators and hard-alloy dental drills are given. New trends in the local hardening of instruments are the treatment of their working parts with laser beams, the application of coating on their surface by the gas-detonation method. The results of research work and trials are presented.

  13. Epilepsy in dental practice.

    Science.gov (United States)

    Fitzpatrick, J J; McArdle, N S; Wilson, M H; Stassen, L F A

    2008-01-01

    Epilepsy is a neurological condition characterised by seizure activity. It has an approximate incidence of 1%. General dental practitioners will encounter these patients in practice. This article discusses the types of epilepsy, the medical management and considerations in dental management of epileptic patients. General recommendations are made, based on current evidence, with respect to prescribing of medications. The management of an epileptic seizure is discussed. Status epilepticus is a rare but serious complication of epileptic seizures. An easy-to-follow algorithm is provided to assist the practitioner in managing seizures.

  14. Dental caries: Strategies to control this preventable disease

    Directory of Open Access Journals (Sweden)

    Andrew Rugg-Gunn

    2013-11-01

    Full Text Available Objective. To provide a brief commentary review of strategies to control dental caries. Dental decay is one of man’s most prevalent diseases. In many counties, severity increased in parallel with importation of sugar, reaching its zenith about 1950s and 1960s. Since then, severity has declined in many countries, due to the wide use of fluoride especially in toothpaste, but dental caries remains a disease of medical, social and economic importance. Within the EU in 2011, the cost of dental treatment was estimated to be €79 billion. The pathogenesis is well understood: bacteria in dental plaque (biofilm metabolise dietary sugars to acids which then dissolve dental enamel and dentine. Possible approaches to control caries development, therefore, involve: removal of plaque, reducing the acidogenic potential of plaque, reduction in sugar consumption, increasing the tooth’s resistance to acid attack, and coating the tooth surface to form a barrier between plaque and enamel. At the present time, only three approaches are of practical importance: sugar control, fluoride, and fissure sealing. The evidence that dietary sugars are the main cause of dental caries is extensive, and comes from six types of study. Without sugar, caries would be negligible. Fluoride acts in several ways to aid caries prevention. Ways of delivering fluoride can be classed as: ‘automatic’, ‘home care’ and ‘professional care’: the most important of these are discussed in detail in four articles in this issue of the Acta Medica Academica. Conclusion. Dental caries is preventable – individuals, communities and countries need strategies to achieve this.

  15. Selective Plasma Etching of Polymeric Substrates for Advanced Applications

    Directory of Open Access Journals (Sweden)

    Harinarayanan Puliyalil

    2016-06-01

    Full Text Available In today’s nanoworld, there is a strong need to manipulate and process materials on an atom-by-atom scale with new tools such as reactive plasma, which in some states enables high selectivity of interaction between plasma species and materials. These interactions first involve preferential interactions with precise bonds in materials and later cause etching. This typically occurs based on material stability, which leads to preferential etching of one material over other. This process is especially interesting for polymeric substrates with increasing complexity and a “zoo” of bonds, which are used in numerous applications. In this comprehensive summary, we encompass the complete selective etching of polymers and polymer matrix micro-/nanocomposites with plasma and unravel the mechanisms behind the scenes, which ultimately leads to the enhancement of surface properties and device performance.

  16. Surface Modification of Nitinol by Chemical and Electrochemical Etching

    Science.gov (United States)

    Yang, Zhendi; Wei, Xiaojin; Cao, Peng; Gao, Wei

    2013-07-01

    In this paper, Nitinol, an equiatomic binary alloy of nickel and titanium, was surface modified for its potential biomedical applications by chemical and electrochemical etching. The main objective of the surface modification is to reduce the nickel content on the surface of Nitinol and simultaneously to a rough surface microstructure. As a result, better biocompatibility and better cell attachment would be achieved. The effect of the etching parameters was investigated, using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometry (EDX) and X-ray photoelectron spectrometry (XPS). The corrosion property of modified Nitinol surfaces was investigated by electrochemical work station. After etching, the Ni content in the surface layer has been reduced and the oxidation of Ti has been enhanced.

  17. Etched track radiometers in radon measurements: a review

    CERN Document Server

    Nikolaev, V A

    1999-01-01

    Passive radon radiometers, based on alpha particle etched track detectors, are very attractive for the assessment of radon exposure. The present review considers various devices used for measurement of the volume activity of radon isotopes and their daughters and determination of equilibrium coefficients. Such devices can be classified into 8 groups: (i) open or 'bare' detectors, (ii) open chambers, (iii) sup 2 sup 2 sup 2 Rn chambers with an inlet filter, (iv) advanced sup 2 sup 2 sup 2 Rn radiometers, (v) multipurpose radiometers, (vi) radiometers based on a combination of etched track detectors and an electrostatic field, (vii) radiometers based on etched track detectors and activated charcoal and (viii) devices for the measurement of radon isotopes and/or radon daughters by means of track parameter measurements. Some of them such as the open detector and the chamber with an inlet filter have a variety of modifications and are applied widely both in geophysical research and radon dosimetric surveys. At the...

  18. Novel diamantane polymer platform for enhanced etch resistance

    Science.gov (United States)

    Padmanaban, Munirathna; Chakrapani, Srinivasan; Lin, Guanyang; Kudo, Takanori; Parthasarathy, Deepa; Rahman, Dalil; Anyadiegwu, Clement; Antonio, Charito; Dammel, Ralph R.; Liu, Shenggao; Lam, Frederick; Waitz, Anthony; Yamagchi, Masao; Maehara, Takayuki

    2007-03-01

    The dominant current 193 nm photoresist platform is based on adamantane derivatives. This paper reports on the use of derivatives of diamantane, the next higher homolog of adamantane, in the diamondoid series, as monomers in photoresists. Due to their low Ohnishi number and incremental structural parameter (ISP), such molecules are expected to enhance dry etch stability when incorporated into polymers for resist applications. Starting from the diamantane parent, cleavable and non-cleavable acrylate/methacrylate derivatives of diamantane were obtained using similar chemical steps as for adamantane derivatization. This paper reports on the lithographic and etch performance obtained with a number of diamantane-containing monomers, such as 9-hydroxy-4-diamantyl methacrylate (HDiMA), 2-ethyl-2- diamantyl methacrylate (EDiMA), and 2-methyl-2-diamantyl methacrylate (MDiMA). The etch advantage, dry and wet lithographic performance of some of the polymers obtained from these diamantane-containing polymers are discussed.

  19. Profile etching for prefiguring X-ray mirrors.

    Science.gov (United States)

    Liu, Chian; Qian, Jun; Assoufid, Lahsen

    2015-03-01

    A method to pre-shape mirror substrates through etching with a broad-beam ion source and a contoured mask is presented. A 100 mm-long elliptical cylinder substrate was obtained from a super-polished flat Si substrate with a 48 nm root-mean-square (r.m.s.) figure error and a 1.5 Å r.m.s. roughness after one profile-etching process at a beam voltage of 600 V without iteration. A follow-up profile coating can be used to achieve a final mirror. Profile etching and profile coating combined provide an economic way to make X-ray optics, such as nested Kirkpatrick-Baez mirrors.

  20. Effect of thermocycling on the durability of etch-and-rinse and self-etch adhesives on dentin.

    Science.gov (United States)

    Sangwichit, Ketkamon; Kingkaew, Ruksaphon; Pongprueksa, Pong; Senawongse, Pisol

    2016-01-01

    The objective was to compare bond strengths of adhesives with/without thermocycling and to analyze the micromorphology of resindentin interfaces. Flat dentin surfaces were prepared and divided into eight groups to bond with four etch-and-rinse adhesives (Optibond FL, Adper Scotchbond Multi-Purpose, Optibond Solo Plus, and Single Bond 2) and four self-etch adhesives (Clearfil SE Bond, Adper SE Plus, Clearfil S(3) Bond and Adper Easy Bond). Specimens were further divided into two subgroups subjected for with/without thermocycling and then subjected to both micro-tensile test and resin-dentin interface evaluation. The results revealed that there were significant differences in bond strength between the groups with and without thermocycling for all etch-and-rinse groups and for the Adper Easy Bond self-etch group (pBond demonstrated highly durable bond strengths. Furthermore, more silver ion uptake was observed at the resin-dentin interfaces for all etch-and-rinse adhesives and Adper SE Plus and Adper Easy Bond after thermocycling.