WorldWideScience

Sample records for tensile bond strength

  1. Analysis of tensile bond strengths using Weibull statistics.

    Science.gov (United States)

    Burrow, Michael F; Thomas, David; Swain, Mike V; Tyas, Martin J

    2004-09-01

    Tensile strength tests of restorative resins bonded to dentin, and the resultant strengths of interfaces between the two, exhibit wide variability. Many variables can affect test results, including specimen preparation and storage, test rig design and experimental technique. However, the more fundamental source of variability, that associated with the brittle nature of the materials, has received little attention. This paper analyzes results from micro-tensile tests on unfilled resins and adhesive bonds between restorative resin composite and dentin in terms of reliability using the Weibull probability of failure method. Results for the tensile strengths of Scotchbond Multipurpose Adhesive (3M) and Clearfil LB Bond (Kuraray) bonding resins showed Weibull moduli (m) of 6.17 (95% confidence interval, 5.25-7.19) and 5.01 (95% confidence interval, 4.23-5.8). Analysis of results for micro-tensile tests on bond strengths to dentin gave moduli between 1.81 (Clearfil Liner Bond 2V) and 4.99 (Gluma One Bond, Kulzer). Material systems with m in this range do not have a well-defined strength. The Weibull approach also enables the size dependence of the strength to be estimated. An example where the bonding area was changed from 3.1 to 1.1 mm diameter is shown. Weibull analysis provides a method for determining the reliability of strength measurements in the analysis of data from bond strength and tensile tests on dental restorative materials.

  2. Evaluation of microtensile and tensile bond strength tests ...

    African Journals Online (AJOL)

    Objectives: The aim of the present study was to compare two different bond strength test methods (tensile and microtensile) in investing the influence of erbium, chromium: yttrium‑scandium‑gallium‑garnet (Er, Cr: YSGG) laser pulse frequency on resin‑enamel bonding. Materials and Methods: One‑hundred and twenty‑five ...

  3. Tensile bond strength of metal bracket bonding to glazed ceramic surfaces with different surface conditionings.

    Science.gov (United States)

    Akhoundi, Ms Ahmad; Kamel, M Rahmati; Hashemi, Sh Mahmood; Imani, M

    2011-01-01

    The objective of this study was to compare the tensile bond strength of metal brackets bonding to glazed ceramic surfaces using three various surface treatments. Forty two glazed ceramic disks were assigned to three groups. In the first and second groups the specimens were etched with 9.5% hydrofluoric acid (HFA). Subsequently in first group, ceramic primer and adhesive were applied, but in second group a bonding agent alone was used. In third group, specimens were treated with 35% phosphoric acid followed by ceramic primer and adhesive application. Brackets were bonded with light cure composites. The specimens were stored in distilled water in the room temperature for 24 hours and thermocycled 500 times between 5°C and 55°C. The universal testing machine was used to test the tensile bond strength and the adhesive remenant index scores between three groups was evaluated. The data were subjected to one-way ANOVA, Tukey and Kruskal-Wallis tests respectively. The tensile bond strength was 3.69±0.52 MPa forfirst group, 2.69±0.91 MPa for second group and 3.60±0.41 MPa for third group. Group II specimens showed tensile strength values significantly different from other groups (Pbrackets to the glazed ceramic restorations with enough tensile bond strength.

  4. Tensile Bond Strength of Metal Bracket Bonding to Glazed Ceramic Surfaces With Different Surface Conditionings

    Directory of Open Access Journals (Sweden)

    M. Imani

    2011-12-01

    Full Text Available Objective: The objective of this study was to compare the tensile bond strength of metal brackets bonding to glazed ceramic surfaces using three various surface treatments.Materials and Methods: Forty two glazed ceramic disks were assigned to three groups. In the first and second groups the specimens were etched with 9.5% hydrofluoric acid (HFA. Subsequently in first group, ceramic primer and adhesive were applied, but in second group a bonding agent alone was used. In third group, specimens were treated with 35% phosphoric acid followed by ceramic primerand adhesive application. Brackets were bonded with light cure composites. The specimens were stored in distilled water in the room temperature for 24 hours and thermocycled 500 times between 5°C and 55°C. The universal testing machine was used to test the tensile bond strength and the adhesive remenant index scores between three groups was evaluated. The data were subjected to one-way ANOVA, Tukey and Kruskal-Wallis tests respectively.Results: The tensile bond strength was 3.69±0.52 MPa forfirst group, 2.69±0.91 MPa for second group and 3.60±0.41 MPa for third group. Group II specimens showed tensile strength values significantly different from other groups (P<0.01.Conclusion: In spite of limitations in laboratory studies it may be concluded that in application of Scotch bond multipurpose plus adhesive, phosphoric acid can be used instead of HFA for bonding brackets to the glazed ceramic restorations with enough tensile bond strength.

  5. Flexural and tensile bond strength, related via a stochastic numerical approach

    NARCIS (Netherlands)

    Pluijm, R. van der

    1998-01-01

    The flexural strength of masonry parallel to the bed joint depends on the geometry of the cross section, tensile bond strength, fracture energy, stiffness of units and of mortar joints. In experiments, tensile bond strength and fracture energy determined on relatively small specimens, show a large

  6. Evaluation of microtensile and tensile bond strength tests ...

    African Journals Online (AJOL)

    2015-11-03

    Nov 3, 2015 ... improve the bonding effectiveness of adhesive resin systems to laser‑irradiated dental hard tissues, ... bond strength of self‑etch adhesive resin to enamel using two different bond tests: μTBS and TBS. ..... surface as possible as without resulting in any cavitation. It was observed that laser irradiation for 45 s ...

  7. Concrete under Impact Loading, Tensile Strength and Bond

    NARCIS (Netherlands)

    Reinhardt, H.W.

    1982-01-01

    Uniaxial impact tensile tests on plain concrete were carried out with the aid of Split Hopkinson Bar equipment with stress rates of up to 60000 N/mm2. s. Various concrete mixes were investigated under. dry and wet conditions. All the concretes showed an increase in strength with increasing stress

  8. Assessing tablet bond types from structural features that affect tablet tensile strength.

    Science.gov (United States)

    Olsson, H; Nyström, C

    2001-02-01

    The aim of this article was to study the possibility of assessing the structural features affecting tablet tensile strength to obtain information on the dominating bond types, i.e. interparticulate attractions, in tablets. The features of the internal tablet structure considered to be important for tablet tensile strength were assessed using a simple tablet model for tablets made from seven materials: potassium chloride, sodium chloride, sodium bicarbonate, lactose, sucrose, microcrystalline cellulose, and ascorbic acid. Tablet porosity and particle size (measured as external specific surface area by permeametry) were the structural features that best correlated with tablet tensile strength. These features were described by a "structural factor," which was combined with tablet tensile strength, as an "interaction factor," to reflect the dominating bond types in tablets. The qualitative results gave dominating bond types in the tablets studied that matched the results of earlier studies, thus supporting the applicability of the method.

  9. The effect of pretreatment with fluoride on the tensile strength of orthodontic bonding

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.N.; Sheen, D.H. (National Defense Medical Center, Taipei, Taiwan (China))

    White spot decalcifications and caries occurring adjacent to bonded orthodontic brackets have long been a concern to orthodontists. One procedure suggested to overcome this problem is fluoride treatment prior to bonding. The purpose of this study was to compare the tensile bond strength of orthodontic self-cured resin from Concise on teeth rinsed 4 minutes in 1.23% APF with untreated controls. Measurements were made on an Instron machine. Debonding interfaces were observed with a scanning electron microscope and energy dispersive x-ray spectrometry. Distributions were calculated. The tensile bond strengths of the fluoride-treated teeth and the untreated teeth were not significantly different. The debonding interfaces between resin and bracket base, within the resin itself, and between enamel and resin were similar in the two experimental groups. However, greater enamel detachment was seen within the fluoride pretreatment group. So while fluoride pretreatment does not significantly affect tensile bond strength, it may cause enamel detachment after debonding.

  10. Influence of disinfectant solutions on the tensile bond strength of a fourth generation dentin bonding agent

    Directory of Open Access Journals (Sweden)

    BOCANGEL Jorge Saldivar

    2000-01-01

    Full Text Available The purpose of the present study was to evaluate the influence of different disinfectant solutions on the tensile bond strength of a fourth generation dentin bonding agent. Forty non carious human molars were selected. Teeth were embedded in acrylic resin and ground until the exposure of a flat superficial dentin surface. Teeth were randomly divided in 4 groups and treated as follows: Group 1 - 2.5% NaOCl for 40 seconds; Group 2 - 2% chlorhexidine for 40 seconds; Group 3 - 1.23% acidulated fluoride for 4 minutes; and Group 4 - control (without disinfectant solution. Following treatments, Scotchbond Multipurpose Plus® (3M was used according to the manufacturer's instructions. After that, the test specimens were built with composite resin (Z100®-3M, using a standard Teflon matrix. The specimens were stored in distilled water for 24 hours at a temperature of 37ºC. The tensile strength test was performed using a Mini Instrom testing machine. The mean values obtained for each group, in MPa, were: Group 1 - 7.37 (± 2.51; Group 2 - 11.25 (± 4.65; Group 3 - 9.80 (± 3.11; and Group 4 - 10.96 (± 3.37. The results were submitted to statistical analysis using the ANOVA test, and no statistical significant differences among the groups were found. It can be concluded that the different disinfectant substances used in this research do not adversely affect dentin adhesion.

  11. Estimation and comparison of tensile bond strengths at resin-dentin ...

    African Journals Online (AJOL)

    Objective: To estimate and compare the Tensile Bond Strengths and to observe the resindentin interface of total-etch and self-etch bonding systems to dentin of primary and permanent molar teeth. Method: Thirty non-carious exfoliated primary human molars and thirty extracted permanent molars were randomly assigned to ...

  12. Tensile bond strength of hydroxyethyl methacrylate dentin bonding agent on dentin surface at various drying techniques

    Directory of Open Access Journals (Sweden)

    Kun Ismiyatin

    2010-06-01

    Full Text Available Background: There are several dentin surface drying techniques to provide a perfect resin penetration on dentin. There are two techniques which will be compared in this study. The first technique was by rubbing dentin surface gently using cotton pellet twice, this technique is called blot dry technique. The second technique is by air blowing dentin surface for one second and continued by rubbing dentin surface gently using moist cotton. Purpose: This experiment was aimed to examine the best dentin surface drying techniques after 37% phosphoric acid etching to obtain the optimum tensile bond strength between hydroxyethyl methacrylate (HEMA and dentin surface. Method: Bovine teeth was prepared flat to obtain the dentin surface and than was etched using 37% phosphoric acid for 15 seconds. After etching the dentin was cleaned using 20 cc plain water and dried with blot dry techniques (group I, or dried with air blow for one second (group II, or dried with air blow for one second, and continued with rubbing gently using moist cotton pellet (group III, and without any drying as control group (group IV. After these drying, the dentin surfaces were applied with resin dentin bonding agent and put into plunger facing the composite mould. The antagonist plunger was filled with composite resin. After 24 hours, therefore bond strength was measured using Autograph. Result: Data obtained was analyzed using One-Way ANOVA with 95% confidence level and continued with LSD test on p≤0.05. The result showed that the highest tensile bond strength was on group I, while the lowest on group IV. Group II and IV, III and IV, II and III did not show signigicant difference (p>0.05. Conclusion: Dentin surface drying techniques through gentle rubbing using cotton pellet twice (blot dry technique gave the greatest tensile bond strength.Latar belakang masalah: Tehnik pengeringan permukaan dentin agar resin dapat penetrasi dengan sempurna adalah dengan cara pengusapan secara

  13. Shore hardness and tensile bond strength of long-term soft denture lining materials.

    Science.gov (United States)

    Kim, Bong-Jun; Yang, Hong-So; Chun, Min-Geoung; Park, Yeong-Joon

    2014-11-01

    Reduced softness and separation from the denture base are the most significant problems of long-term soft lining materials. The purpose of this study was to evaluate the durometer Shore A hardness and tensile bond strength of long-term soft denture lining materials and to investigate the correlation between these 2 properties. A group of 7 soft lining materials, 6 silicone based (Dentusil, GC Reline Soft, GC Reline Ultrasoft, Mucopren Soft, Mucosoft, Sofreliner Tough) and 1 acrylic resin based (Durabase), were evaluated for durometer Shore A hardness and tensile bond strength to heat-polymerized denture base resin (Lucitone 199). A specially designed split mold and loading assembly with a swivel connector were used for the durometer Shore A hardness test and tensile bond strength test to improve accuracy and facilitate measurement. Three specimens of each product were stored in a 37°C water bath, and durometer Shore A hardness tests were carried out after 24 hours and 28 days. A tensile bond strength test was carried out for 10 specimens of each product, which were stored in a 37°C water bath for 24 hours before the test. Repeated-measures ANOVA, the Kruskal-Wallis and Duncan multiple range tests, and the Spearman correlation were used for statistical analyses. The repeated-measures ANOVA found significant durometer Shore A hardness differences for the materials (Phardness (21.30 ±0.29 for 24 hours, 34.73 ±0.47 for 28 days), and GC Reline Soft showed the highest mean durometer Shore A hardness (50.13 ±0.48 for 24 hours, 57.20 ±0.28 for 28 days). The Kruskal-Wallis test found a significant difference in the mean tensile bond strength values (Phardness showed a statistically insignificant moderate positive correlation (r=0.571, P=.180 for Shore A hardness 24 hours versus tensile bond strength; r=0.607, P=.148 for Shore A hardness 28 days versus tensile bond strength). Within the limitations of this study, significant differences were found in durometer Shore A

  14. The effect of thermocycling on tensile bond strength of two soft liners.

    Science.gov (United States)

    Geramipanah, Farideh; Ghandari, Masoumeh; Zeighami, Somayeh

    2013-09-01

    Failure of soft liners depends mostly on separation from the denture base resin; therefore measurement of the bond strength is very important. The purpose of this study was to compare the tensile bond strength of two soft liners (Acropars, Molloplast-B) to denture base resin before and after thermocycling. Twenty specimens fromeach of the two different soft liners were processed according to the manufacturer's instructions between two polymethyl methacrylate (PMMA) sheets. Ten specimens in each group were maintained in 37°C water for 24 hours and 10 were thermocycled (5000 cycles) among baths of 5° and 55°C. The tensile bond strength was measured using a universal testing machine at a crosshead speed of 5 mm/min. Mode of failure was determined with SEM (magnification ×30). Two-way ANOVA was used to analyze the data. The mean and standard deviation of tensile bond strength of Acropars and Molloplast-B before thermocycling were 6.59±1.85 and1.51±0.22 MPa, respectively and 5.89±1.52 and1.37±0.18 MPa, respectively after thermocycling. There was no significant difference before and after thermocycling. Mode of failure in Acropars and Molloplast-B were adhesive and cohesive, respectivley. The bond strength of Acropars was significantly higher than Molloplast-B (P<0.05).

  15. The Effect of Thermocycling on Tensile Bond Strength of Two Soft Liners

    Directory of Open Access Journals (Sweden)

    Farideh Geramipanah

    2013-01-01

    Full Text Available Objective: Failure of soft liners depends mostly on separation from the denture base resin; therefore measurement of the bond strength is very important. The purpose of this study was to compare the tensile bond strength of two soft liners (Acropars, Molloplast-B to denture base resin before and after thermocycling.Materials and Methods: Twenty specimens from each of the two different soft liners were processed according to the manufacturer’s instructions between two polymethyl methacrylate (PMMA sheets. Ten specimens in each group were maintained in 37°C water for 24 hours and 10 were thermocycled (5000 cycles among baths of 5° and 55°C. The tensile bond strength was measured using a universal testing machine at a crosshead speed of 5 mm/min. Mode of failure was determined with SEM (magnification ×30. Two-way ANOVA was used to analyze the data.Results: The mean and standard deviation of tensile bond strength of Acropars and Molloplast-B before thermocycling were 6.59±1.85 and 1.51±0.22 MPa, respectively and 5.89±1.52 and 1.37±0.18 MPa, respectively after thermocycling. There was no significant difference before and after thermocycling. Mode of failure in Acropars and Molloplast-B were adhesive and cohesive, respectivley.Conclusion: The bond strength of Acropars was significantly higher than Molloplast-B (P<0.05.

  16. Effect of surface treatment of titanium posts on the tensile bond strength

    NARCIS (Netherlands)

    Schmage, P; Sohn, J; Ozcan, M; Nergiz, [No Value

    Objectives. Retention of composite resins to metal can be improved when metal surfaces are conditioned. The purpose of this investigation was to investigate the effect of two conditioning treatments on the tensile bond strength of four resin-based luting cements and zinc phosphate cement to titanium

  17. Tensile Bond Strength of Self Adhesive Resin Cement After Various Surface Treatment of Enamel

    Science.gov (United States)

    Sekhri, Sahil; Garg, Sandeep

    2016-01-01

    Introduction In self adhesive resin cements adhesion is achieved to dental surface without surface pre-treatment, and requires only single step application. This makes the luting procedure less technique-sensitive and decreases postoperative sensitivity. Aim The purpose of this study was to evaluate bond strength of self adhesive resin after surface treatment of enamel for bonding base metal alloy. Materials and Methods On the labial surface of 64 central incisor rectangular base metal block of dimension 6 mm length, 5mm width and 1 mm height was cemented with RelyX U200 and Maxcem Elite self adhesive cements with and without surface treatment of enamel. Surface treatment of enamel was application of etchant, one step bonding agent and both. Tensile bond strength of specimen was measured with universal testing machine at a cross head speed of 1mm/min. Results Least tensile bond strength (MPa) was in control group i.e. 1.33 (0.32) & 1.59 (0.299), Highest bond strength observed when enamel treated with both etchant and bonding agent i.e. 2.72 (0.43) & 2.97 (0.19) for Relyx U200 and Elite cement. When alone etchant and bonding agent were applied alone bond strength is 2.19 (0.18) & 2.24 (0.47) for Relyx U200, and 2.38 (0.27) 2.49 (0.16) for Max-cem elite. Mean bond strength was higher in case of Max-cem Elite as compared to RelyX U200 resin cement, although differences were non–significant (p > 0.05). Conclusion Surface treatment of enamel increases the bond strength of self adhesive resin cement. PMID:26894165

  18. In vitro Comparative Evaluation of Tensile Bond Strength of 6th, 7th and 8th Generation Dentin Bonding Agents

    OpenAIRE

    Kamble, Suresh S; Kandasamy, Baburajan; Thillaigovindan, Ranjani; Goyal, Nitin Kumar; Talukdar, Pratim; Seal, Mukut

    2015-01-01

    Background: Newer dentin bonding agents were developed to improve the quality of composite restoration and to reduce time consumption in its application. The aim of the present study was to evaluate tensile bond strength of 6th, 7th and 8th generation bonding agents by in vitro method. Materials and Methods: Selected 60 permanent teeth were assigned into 20 in each group (Group I: 6th generation bonding agent-Adper SE plus 3M ESPE, Group II: 7th generation bonding agent-G-Bond GC Corp Japan a...

  19. Evaluation of flexural, diametral tensile, and shear bond strength of composite repairs.

    Science.gov (United States)

    Imbery, T A; Gray, T; DeLatour, F; Boxx, C; Best, A M; Moon, P C

    2014-01-01

    Repairing composite restorations may be a more conservative treatment than replacing the entire restoration. The objective of this in vitro study was to determine the best repair method by measuring flexural, diametral tensile, and shear bond strength of repaired composites in which the surfaces were treated with chemical primers (Add & Bond or Silane Bond Enhancer), a bonding agent (Optibond Solo Plus [OBSP]), or mechanical retention with a bonding agent. Filtek Supreme Ultra shade B1B was placed in special molds to fabricate specimens that served to test the flexural, diametral tensile, or shear strength of the inherent resin substrate. The same molds were modified to make specimens for testing repair strength of the resin. Repairs were made immediately or after aging in deionized water at 37°C for seven days. All repair sites were finished with coarse Sof-Lex discs to simulate finishing new restorations or partially removing aged restorations. Repair surfaces were treated with one of the following: 1) phosphoric-acid etching and OBSP; 2) Add & Bond; 3) phosphoric-acid etching, Silane Bond Enhancer, and OBSP; or 4) quarter round bur, phosphoric-acid etching, and OBSP. Specimens were placed back in the original molds to fabricate specimens for diametral tensile or flexural testing or in an Ultradent jig to make specimens for shear bond testing. Composite resin in shade B5B was polymerized against the treated surfaces to make repairs. Two negative control groups for the three testing methods consisted of specimens in which repairs were made immediately or after aging without any surface treatments. Controls and experimental repairs were aged (water 37°C, 24 hours) before flexural, diametral tensile, or shear testing in an Instron Universal testing machine at a crosshead speed of 0.5 mm/min. Experimental flexural repair strengths ranged from 26.4% to 88.6% of the inherent substrate strength. Diametral tensile repair strengths ranged from 40% to 80% of the inherent

  20. An Ex-vivo Shear and tensile bond strengths of orthodontic molar tubes bonded using different techniques

    Science.gov (United States)

    Alwahadni, Ahed

    2017-01-01

    Background Molar bonding procedures need continuous improvement to be widely accepted clinically and eventually replace molar bands. Material and Methods The purpose of this study was to determine the effects of enamel micro-abrasion and silane coating of the base of molar tubes on shear and tensile bond strengths of orthodontic molar tubes. A total of 200 third molars were randomly allocated into five groups of 40 teeth as follows: group 1: molar tubes bonded to etched teeth (37% phosphoric acid gel; control group); group 2: molar tubes bonded to etched teeth (37% phosphoric acid) with the addition of silane to the base of molar tubes; group 3: molar tubes bonded to teeth pre-treated with 18% hydrochloric acid and pumice (micro-abrasion); group 4: molar tubes bonded to teeth pre-treated with microabrasion with the addition of silane to the base of molar tubes; group 5: molar tubes bonded to teeth pre-treated with microabrasion before conventional acid etching combined with the addition of silane to the base of molar tubes. The bond strength testing was performed using a computer control electromechanical universal testing machine. Results The highest mean shear and tensile bond strengths were recorded in group 5 (13.81±2.54MPa and 13.97±2.29 MPa, respectively). Micro-abrasion alone (group 3) and the combination of enamel micro-abrasion and the addition of silane (group 4) produced bond strength values comparable to the control. Conclusions Enamel surface pre-treatment (micro abrasion) before conventional acid etching combined with the addition of silane to the base of the molar tube produced the highest bond strengths among all tested groups. Key words:Molar, shear strength, tensile strength, orthodontic appliances. PMID:28298990

  1. An Ex-vivo Shear and tensile bond strengths of orthodontic molar tubes bonded using different techniques.

    Science.gov (United States)

    Abu-Alhaija, Elham; Jaradat, Mohammad; Alwahadni, Ahed

    2017-03-01

    Molar bonding procedures need continuous improvement to be widely accepted clinically and eventually replace molar bands. The purpose of this study was to determine the effects of enamel micro-abrasion and silane coating of the base of molar tubes on shear and tensile bond strengths of orthodontic molar tubes. A total of 200 third molars were randomly allocated into five groups of 40 teeth as follows: group 1: molar tubes bonded to etched teeth (37% phosphoric acid gel; control group); group 2: molar tubes bonded to etched teeth (37% phosphoric acid) with the addition of silane to the base of molar tubes; group 3: molar tubes bonded to teeth pre-treated with 18% hydrochloric acid and pumice (micro-abrasion); group 4: molar tubes bonded to teeth pre-treated with microabrasion with the addition of silane to the base of molar tubes; group 5: molar tubes bonded to teeth pre-treated with microabrasion before conventional acid etching combined with the addition of silane to the base of molar tubes. The bond strength testing was performed using a computer control electromechanical universal testing machine. The highest mean shear and tensile bond strengths were recorded in group 5 (13.81±2.54MPa and 13.97±2.29 MPa, respectively). Micro-abrasion alone (group 3) and the combination of enamel micro-abrasion and the addition of silane (group 4) produced bond strength values comparable to the control. Enamel surface pre-treatment (micro abrasion) before conventional acid etching combined with the addition of silane to the base of the molar tube produced the highest bond strengths among all tested groups. Key words:Molar, shear strength, tensile strength, orthodontic appliances.

  2. Effect of laser welding on the titanium ceramic tensile bond strength

    Directory of Open Access Journals (Sweden)

    Rodrigo Galo

    2011-08-01

    Full Text Available Titanium reacts strongly with elements, mainly oxygen at high temperature. The high temperature of titanium laser welding modifies the surface, and may interfere on the metal-ceramic tensile bond strength. OBJECTIVE: The influence of laser welding on the titanium-ceramic bonding has not yet been established. The purpose of this in vitro study was to analyze the influence of laser welding applied to commercially pure titanium (CpTi substructure on the bond strength of commercial ceramic. The influence of airborne particle abrasion (Al2O3 conditions was also studied. MATERIAL AND METHODS: Forty CpTi cylindrical rods (3 mm x 60 mm were cast and divided into 2 groups: with laser welding (L and without laser welding (WL. Each group was divided in 4 subgroups, according to the size of the particles used in airborne particle abrasion: A - Al2O3 (250 µm; B - Al2O3 (180 µm; C - Al2O3 (110 µm; D - Al2O3 (50 µm. Ceramic rings were fused around the CpTi rods. Specimens were invested and their tensile strength was measured at fracture with a universal testing machine at a crosshead speed of 2.0 mm/min and 200 kgf load cell. Statistical analysis was carried out with analysis of variance and compared using the independent t test (p<0.05. RESULTS: Significant differences were found among all subgroups (p<0.05. The highest and the lowest bond strength means were recorded in subgroups WLC (52.62 MPa and LD (24.02 MPa, respectively. CONCLUSION: Airborne particle abrasion yielded significantly lower bond strength as the Al2O3 particle size decreased. Mechanical retention decreased in the laser-welded specimens, i.e. the metal-ceramic tensile bond strength was lower.

  3. The difference of tensile bond strength between total and self etch adhesive systems in dentin

    Directory of Open Access Journals (Sweden)

    Selly Yusalina

    2010-03-01

    Full Text Available Total etch adhesive system has been widely used in teeth conservation area as an adhesive agent before implicating composite resin restoration agent. The aim of this research is to prove the difference of tensile bond strength between total etch (Single Bond and self etch adhesive system (Adper prompt L-Pop on dentin surface in vitro. The extracted and non carries maxillary premolar teeth were used in this research and were divided into 2 groups. The first group comprised 15 specimen teeth etched in phosphoric acid and was applicated with the Single Bond adhesive agent. The second group comprised 15 specimen teeth, applicated with the Adper Prompt-L-Pop. The composite resin (Z 350, 3M was applied incrementally and each of the layers was rayed for 20 seconds. The specimens were stored in physiologic solution before they were tested. Tensile bond strength was measured by LRX Plus Lloyd Instrument, with 1 N load and 1 mm/minute speed, and the measurement result was in Mpa unit. The result was evaluated statistically by the Student t-test with α = 0.05. Single Bond (the 5th generation showed a better bond strength compared to the Adper Prompt-L-Pop (the 6th generation.

  4. Tensile bond strength of ceramic crowns to dentin using resin cements.

    Science.gov (United States)

    Simon, James F; de Rijk, Waldemar G; Hill, Jennifer; Hill, Nathaniel

    2011-01-01

    This study measured the bond strength of the self-adhesive resin cements and a bonded resin cement for crowns bonded to extracted teeth with preparations having a total taper greater than 30 degrees. A crown pull-off test was used with direction of pull along the path of insertion. The CAD/CAM system Cerec was used to create crowns with the pull-off loop as an integral part of the crown structure. One hundred extracted human molars were prepared for all-ceramic crowns with a 1.5-mm shoulder, greater than 30-degree axial wall convergence, a flat occlusal surface and 3 to 5 mm occlusal/ gingival height. All-ceramic crowns were cemented with five different self-adhesive cements (Rely X Unicem, Maxcem Elite, BisCem, SmartCem 2, and G-Cem) and one bonded resin cement (Multilink). Forfour cements (excluding GCem and Multilink) there were 2 groups, one with HF etching and one without ceramic surface treatment. The crowns were then subject to tensile stress until either the crown fractured or the crown was lifted off from the tooth. For several cements, the bond strength exceeded the tensile strength of the all-ceramic crown; thus, the crown fractured, leaving the cemented part of the crown on the tooth. The effect of ceramic surface etching was not statistically significant at p = 0.05; however, for each cement, the treated crowns showed a lower coefficient of variance (COV). For this study, the COV ranged from 24.9 % to 97.9 %. Loads ranged from 41.3 to 190.3 N. Some of the new self-etching resin cements can create bonds to non-retentive crown preparations that are stronger than the strength of a ceramic crown; however, these high bond strengths may not be able to be achieved consistently.

  5. Tensile Bond Strengths of Two Adhesives on Irradiated and Nonirradiated Human Dentin

    Directory of Open Access Journals (Sweden)

    Cécile Bernard

    2015-01-01

    Full Text Available The aim of this study was to assess the effect of radiotherapy on bond efficiency of two different adhesive systems using tensile bond strength test. Twenty extracted teeth after radiotherapy and twenty nonirradiated extracted teeth were used. The irradiation was applied in vivo to a minimal dose of 50 Gy. The specimens of each group were randomly assigned to two subgroups to test two different adhesive systems. A three-step/etch-and-rinse adhesive system (Optibond FL and a two-steps/self-etch adhesive system (Optibond XTR were used. Composite buildups were performed with a nanohybrid composite (Herculite XTR. All specimens were submitted to thermocycling ageing (10000 cycles. The specimens were sectioned in 1 mm2 sticks. Microtensile bond strength tests were measured. Nonparametric statistical analyses were performed due to nonnormality of data. Optibond XTR on irradiated and nonirradiated teeth did not show any significant differences. However, Optibond FL bond strength was more effective on nonirradiated teeth than on irradiated teeth. Within the limitations of an in vitro study, it can be concluded that radiotherapy had a significant detrimental effect on bond strength to human dentin. However, it seems that adhesive choice could be adapted to the substrata. According to the present study, the two-steps/self-etch (Optibond XTR adhesive system tested could be more effective on irradiated dentin compared to three-steps/etch-and-rinse adhesive system (Optibond FL.

  6. Bond strength and ultimate tensile strength of resin composite filled into dentine cavity; effect of bulk and incremental filling technique.

    Science.gov (United States)

    Nayif, Ma'an M; Nakajima, Masatoshi; Foxton, Richard M; Tagami, Junji

    2008-03-01

    The aim of this study was to evaluate the relationship between micro-tensile bond strength (muTBS) and ultimate tensile strength (UTS) of resin composite restorations in cavities filled by a bulk or incremental technique using the micro-tensile test. Class I cavities (4mm long, 3mm wide, 3mm deep) were prepared into dentine of sixteen human molars. All cavities were bonded with Clearfil SE Bond and restored with AP-X composite with either a bulk or incremental technique. After storage in water for 24h, the teeth were vertically sectioned to yield two slabs. Each slab was sectioned into three sticks. Sticks of one slab were trimmed into an hourglass of 0.7 mm2 area at resin-dentine interface for bond strength measurement while the other sticks were trimmed at the centre of the restoration for UTS measurement. Specimens were tested in tension at 1mm/min until failure. The results obtained were statistically analysed using two-way ANOVA and post hoc test (alpha=0.05). Pearson's correlation test was used to identify any correlation between muTBS and UTS for each filling method. Both muTBS and UTS of resin composite decreased towards the bottom of the cavity (pvariables. There was a relationship between muTBS and UTS of resin composite filled into dentin cavity in bulk technique.

  7. Effect of thermal aging on the tensile bond strength at reduced areas of seven current adhesives.

    Science.gov (United States)

    Baracco, Bruno; Fuentes, M Victoria; Garrido, Miguel A; González-López, Santiago; Ceballos, Laura

    2013-07-01

    The purpose of this study was to determine the micro-tensile bond strength (MTBS) to dentin of seven adhesive systems (total and self-etch adhesives) after 24 h and 5,000 thermocycles. Dentin surfaces of human third molars were exposed and bonded with two total-etch adhesives (Adper Scotchbond 1 XT and XP Bond), two two-step self-etch adhesives (Adper Scotchbond SE and Filtek Silorane Adhesive System) and three one-step self-etch adhesives (G-Bond, Xeno V and Bond Force). All adhesive systems were applied following manufacturers' instructions. Composite buildups were constructed and the bonded teeth were then stored in water (24 h, 37 °C) or thermocycled (5,000 cycles) before being sectioned and submitted to MTBS test. Two-way ANOVA and subsequent comparison tests were applied at α = 0.05. Characteristic de-bonded specimens were analyzed using scanning electron microscopy (SEM). After 24 h water storage, MTBS values were highest with XP Bond, Adper Scotchbond 1 XT, Filtek Silorane Adhesive System and Adper Scotchbond SE and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. After thermocycling, MTBS values were highest with XP Bond, followed by Filtek Silorane Adhesive System, Adper Scotchbond SE and Adper Scotchbond 1 XT and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. Thermal aging induced a significant decrease in MTBS values with all adhesives tested. The resistance of resin-dentin bonds to thermal-aging degradation was material dependent. One-step self-etch adhesives obtained the lowest MTBS results after both aging treatments, and their adhesive capacity was significantly reduced after thermocycling.

  8. Tensile bond strength of different universal adhesive systems to lithium disilicate ceramic.

    Science.gov (United States)

    Passia, Nicole; Lehmann, Frank; Freitag-Wolf, Sandra; Kern, Matthias

    2015-10-01

    Today, many adhesive systems with different coupling agents for tooth structures and restorative materials are available. The purpose of this in vitro study was to evaluate the tensile bond strength (TBS) of different universal adhesive systems to etched lithium disilicate ceramic. The authors etched and bonded 96 disk-like lithium disilicate ceramic specimens (IPS e.max CAD, Ivoclar Vivadent) with 4 different adhesive bonding systems to Plexiglas tubes filled with a composite resin. The authors stored the specimens in water at 37°C for 3 days without thermal cycling or for 30 or 150 days with 7,500 or 37,500 thermal cycles between 5°C and 55°C, respectively. Then, all specimens underwent TBS testing. The authors performed statistical analysis by using Kruskal-Wallis and Wilcoxon tests with a Bonferroni-Holm correction for multiple testing. Initially, all adhesive systems exhibited considerable TBS, but some showed a significant reduction after 30 days of storage. After 3, 30, and 150 days, the Monobond Plus and Multilink Automix (Ivoclar Vivadent) silane-containing adhesive system showed significantly higher bond strengths to lithium disilicate ceramic than did the other universal adhesive systems, some of which do not contain silanes. The bond strength to lithium disilicate ceramic is affected significantly by the adhesive bonding system used. Universal adhesive systems that do not contain a silane should be avoided for bonding lithium disilicate ceramic restorations because of their inferior bond strength. Copyright © 2015 American Dental Association. Published by Elsevier Inc. All rights reserved.

  9. Effect of Numbers of Load Cycling on the Micro Tensile Bond Strength of Total Etch Adhesives to Dentin

    Directory of Open Access Journals (Sweden)

    AR Daneshkazemi

    2013-06-01

    Full Text Available Introduction: Today load cycling is used for similarity of invitro and invivo studies, though different results were reported in different studies. Therefore, this study aimed to investigate the effect of load cycling on micro tensile bond strength of two total etch adhesives to dentin. Methods: Enamel of 48 molar teeth were removed to expose the superficial dentin. The teeth were randomly divided into two equal groups, and were restored with Single bond (SB, ExciTE and Synergy composite. Then the teeth of each group were divided to 4 equal sub groups. Moreover, load cycling of 0, 50, 100, 200 k load cycle with 50 newton load was used. In each sub group, 12 hour glass slabs with 1mm2 thickness were made. Then the samples were loaded by Dartec testing machine (Model HC/10 with 1 mm/min cross head speed to make the fracture occur. Data were analyzed by ANOVA, t-test, Bonferroni tests. Results: The most micro tensile bond strength belonged to ExciTE without load cycling and lowest refered to SB with 200 k. There was a significant difference between the groups (p ExciTE= 0.0001, p SB = 0.001. Micro tensile bond strength in SB group was significantly lower than ExciTE (p= 0.001. Moreover, load cycling had negative effect on micro tensile bond strength. Conclusion: By increasing load cycling, micro tensile bond strength of both bondings decreased significantly

  10. Tensile strength and bonding in compacts: a comparison of diametral compression and three-point bending for plastically deforming materials.

    Science.gov (United States)

    Amin, Mohd C I; Fell, John T

    2002-08-01

    The tensile strength of tablets is frequently used as a measure of the bonding achieved during compaction. Tablets from two plastically deforming materials and one brittle material have been subjected to tensile strength testing using diametral compression and three-point bending. The plastically deforming materials exhibited marked inhomogeneities, with the surfaces of the tablets considerably more compact than the inner material. The results from the two tests were different, with the three-point bending test giving higher results for tensile strength. The rate of change of tensile strength with overall tablet porosity was, however, the same for the two tests. Diametral compression would thus appear to give a reasonable estimate of bonding despite the non-homogenous nature of tablets prepared from plastically deforming materials.

  11. Tensile bond strength of veneering resins to PEEK: impact of different adhesives.

    Science.gov (United States)

    Stawarczyk, Bogna; Keul, Christine; Beuer, Florian; Roos, Malgorzata; Schmidlin, Patrick R

    2013-01-01

    This study tested tensile bond strength (TBS) between veneering resins and polyetheretherketone (PEEK) after pre-treatment with adhesive systems. Five-hundred-seventy-six PEEK disks were fabricated, air-abraded and divided into six pre-treatment groups (n=96/group): Z-Prime Plus, Ambarino P60, Monobond Plus, Visio.link, Signum PEEK Bond, and control group without pre-treatment. Each group was divided into three subgroups of different veneering resins (n=32): Sinfony, GC Gradia and VITA VM LC. After specimen preparation with a bond area of 6.6 mm(2), half of each subgroup (n=16) was tested initially, and the other half was thermo-cycled. TBS measurements were analysed by three-way and one-way ANOVA, t-test and Weibull statistics. Groups without pre-treatment and groups pre-treated by Z-Prime Plus and Ambarino P60 showed no TBS. Pre-treatment with Monobond Plus increased the TBS values. The highest TBS before and after thermo-cycling between PEEK and all tested veneering resins was observed for groups pre-treated with Visio.link and Signum PEEK Bond.

  12. Effect of Saliva on the Tensile Bond Strength of Different Generation Adhesive Systems: An In-Vitro Study

    Science.gov (United States)

    Tripathi, Abhay Mani; Saha, Sonali; Dhinsa, Kavita; Garg, Aarti

    2015-01-01

    Background Newer development of bonding agents have gained a better understanding of factors affecting adhesion of interface between composite and dentin surface to improve longevity of restorations. Objective The present study evaluated the influence of salivary contamination on the tensile bond strength of different generation adhesive systems (two-step etch-and-rinse, two-step self-etch and one-step self-etch) during different bonding stages to dentin where isolation is not maintained. Materials and Methods Superficial dentin surfaces of 90 extracted human molars were randomly divided into three study Groups (Group A: Two-step etch-and-rinse adhesive system; Group B: Two-step self-etch adhesive system and Group C: One-step self-etch adhesive system) according to the different generation of adhesives used. According to treatment conditions in different bonding steps, each Group was further divided into three Subgroups containing ten teeth in each. After adhesive application, resin composite blocks were built on dentin and light cured subsequently. The teeth were then stored in water for 24 hours before sending for testing of tensile bond strength by Universal Testing Machine. The collected data were then statistically analysed using one-way ANOVA and Tukey HSD test. Results One-step self-etch adhesive system revealed maximum mean tensile bond strength followed in descending order by Two-step self-etch adhesive system and Two-step etch-and-rinse adhesive system both in uncontaminated and saliva contaminated conditions respectively. Conclusion Unlike One-step self-etch adhesive system, saliva contamination could reduce tensile bond strength of the two-step self-etch and two-step etch-and-rinse adhesive system. Furthermore, the step of bonding procedures and the type of adhesive seems to be effective on the bond strength of adhesives contaminated with saliva. PMID:26393214

  13. PEEK surface treatment effects on tensile bond strength to veneering resins.

    Science.gov (United States)

    Stawarczyk, Bogna; Jordan, Peter; Schmidlin, Patrick R; Roos, Malgorzata; Eichberger, Marlis; Gernet, Wolfgang; Keul, Christine

    2014-11-01

    Polyetheretherketone (PEEK) can be used as a framework material for fixed dental prostheses. However, information about the durable bond to veneering resins is still scarce. The purpose of this study was to investigate the effect of chemical treatments of PEEK on tensile bond strength (TBS) to veneering resins with special emphasis on surface free energy (SFE) and surface roughness (SR). Seven-hundred fifty PEEK specimens were fabricated and divided into the following 3 pretreatment groups (n=250/group): etching with sulfuric acid for 60 seconds, etching with piranha acid for 30 seconds, and an unetched control. After pretreatment, SFE was determined by using contact angle measurements and SR with a profilometer (n=10/group). The topography of pretreated PEEK surfaces was examined with scanning electron microscopy. Remaining specimens (n=240 per group) were conditioned with visio.link or Signum PEEK Bond, or were left untreated as the control group. Half of each group was veneered with Sinfony or VITA VM LC (n=40/group), and TBS was measured after storage in distilled water at 37°C for either 24 hours or 60 days. Data were analyzed by 4-way and 1-way ANOVA followed by the Scheffé post hoc test and chi-square test (α=.05). PEEK specimens etched with sulfuric acid resulted in higher SFE and SR than specimens without pretreatment or etching with piranha acid. Etching with sulfuric acid or piranha acid led to no general recommendations with respect to TBS. Conditioning with visio.link or Signum PEEK Bond significantly increased the TBS (Pveneered with Sinfony showed significantly higher TBS values than those veneered with VITA VM LC (Pveneering resin can only be achieved when additional adhesive materials were applied. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  14. Comparative evaluation of tensile bond strength of silicone-based denture liners after thermocycling and surface treatment

    Directory of Open Access Journals (Sweden)

    Harsimran Kaur

    2015-01-01

    Full Text Available Purpose: To examine, evaluate, and compare the tensile bond strength of two silicone-based liners; one autopolymerizing and one heat cured, when treated with different chemical etchants to improve their adhesion with denture base resin. Materials and Methods: Hundred and sixty test specimens of heat-cured polymethyl methacrylate (PMMA were fabricated; out of which 80 specimens were tested for tensile bond strength after bonding it to autopolymerizing resilient liner (Ufigel P and rest 80 to heat-cured resilient liner (Molloplast B. Each main group was further divided into four subgroups of 20 specimens each, one to act as a control and three were subjected to surface treatment with different chemical etchants namely dichloromethane, MMA monomer, and chloroform. The two silicone-based denture liners were processed between 2 PMMA specimens (10 mm × 10 mm × 40 mm in the space provided by a spacer of 3 mm, thermocycled (5-55°C for 500 cycles, and then their tensile strength measurements were done in the universal testing machine. Results: One-way ANOVA technique showed a highly significant difference in the mean tensile bond strength values for all the groups. The Student′s t-test computed values of statistics for the compared groups were greater than the critical values both at 5% and at 1% levels. Conclusion: Surface treatment of denture base resin with chemical etchants prior to the application of silicone-based liner (Ufigel P and Molloplast-B increased the tensile bond strength. The increase was the highest with specimens subjected to 180 s of MMA surface treatment and the lowest with control group specimens.

  15. An investigation into the effects of metal primer and surface topography on the tensile bond strength between cobalt chromium alloy and composite resin.

    Science.gov (United States)

    Newsum, David; Juszczyk, Andrzej; Clark, Robert K F; Radford, David R

    2011-03-01

    This study examined the influence of surface preparation and metal primer on the tensile bond strength between cobalt chromium alloy and composite resin. The bond strength between 168 cobalt chromium alloy dumb-bells with one of three test surfaces (beaded, machined or sandblasted) to composite resin were tested. Half of each group were treated with metal primer. The weakest bond strength was produced by the unprimed machined surface, many specimens failing before testing. The metal primer increased the bond strengths of all groups tested. The greatest bond strengths were achieved with the primed beaded and sandblasted surfaces. Within the limits of the study it has been shown that the surface preparation of the cobalt-chromium alloy did influence tensile bond strengths with composite resin and Metal Primer II increased the tensile bond strengths for all groups tested. The sandblasted surface treated with Metal Primer II is recommended for the bonding of composite resin to cobalt chromium alloy.

  16. The Disulfide Bonds within BST-2 Enhance Tensile Strength during Viral Tethering.

    Science.gov (United States)

    Du Pont, Kelly E; McKenzie, Aidan M; Kokhan, Oleksandr; Sumner, Isaiah; Berndsen, Christopher E

    2016-02-16

    Human BST-2/tetherin is a host factor that inhibits the release of enveloped viruses, including HIV-1, HIV-2, and SIV, from the cell surface by tethering viruses to the host cell membrane. BST-2 has an α-helical ectodomain that forms disulfide-linked dimers between two monomers forming a coiled coil. The ectodomain contains three cysteine residues that can participate in disulfide bond formation and are critical for viral tethering. The role of the disulfides in viral tethering is unknown but proposed to be for maintaining the dimer. We explored the role of the disulfides in the structure of BST-2 using experimental, biophysical methods. To understand the role of the disulfides in viral tethering, we used a new approach in viral tethering, steered molecular dynamics. We find that the disulfides coordinate the unfolding of the BST-2 monomers, which adds tensile strength to the coiled coil. Structural differences between oxidized and reduced BST-2 are apparent during unfolding, showing the monomers slide past each other in the absence of the disulfides. We found no evidence to support dissociation of the dimer upon reduction of the disulfide bonds. Moreover, the structure of BST-2 in the absence of the disulfides is similar to that of the oxidized form of BST-2, supporting previous X-ray crystallography and cellular work that showed the disulfides are not required for expression of BST-2. These data provide new insights into viral tethering by using novel techniques in the analysis of BST-2 to give amino acid level insight into functions of BST-2.

  17. Effect of 2-hydroxyethyl methacrylate pre-treatment on micro-tensile bond strength of resin composite to demineralized dentin.

    Science.gov (United States)

    Doi, J; Itota, T; Torii, Y; Nakabo, S; Yoshiyama, M

    2004-11-01

    The purpose of this study was to evaluate the effect of 2-hydroxyethyl methacrylate (HEMA) application on the micro-tensile bond strength of resin composite to demineralized dentin. Artificially demineralized lesions were formed on bovine dentin surfaces and treated with 10, 30, 50, 70 and 100 wt% HEMA aqueous solution. The surfaces were then applied and covered with SE Bond and AP-X according to the manufacturer's instruction. After immersion in 37 degrees C water for 24 h, bond strength were measured using a universal testing machine. Bond strengths to both demineralized dentin and normal dentin, without HEMA application, were also measured. Scanning electron microscopic (SEM) observation and confocal laser scanning microscopy (CLSM) analysis at the resin-dentin interface were also performed. The bond strength data were statistically compared with anova and Scheffe's test (P < 0.05). Bond strength to demineralized dentin treated with over 30 wt% HEMA aqueous solution were significantly higher than that to demineralized dentin without HEMA application, but significantly lower than that to normal dentin. SEM observation revealed that the hybrid layer and resin-tags thickened and lengthened with HEMA application. In CLSM, the diffusion of adhesive primer into demineralized dentin increased with HEMA application. These results indicated that HEMA application might increase the bond strength to demineralized dentin by the enhancement of resin monomer penetration of HEMA.

  18. Tensile Bond Strength of So-called Universal Primers and Universal Multimode Adhesives to Zirconia and Lithium Disilicate Ceramics.

    Science.gov (United States)

    Elsayed, Adham; Younes, Feras; Lehmann, Frank; Kern, Matthias

    2017-01-01

    To test the bond strength and durability after artificial aging of so-called universal primers and universal multimode adhesives to lithium disilicate or zirconia ceramics. A total of 240 ceramic plates, divided into two groups, were produced and conditioned: 120 acid-etched lithium disilicate plates (IPS e.max CAD) and 120 air-abraded zirconia plates (Zenostar T). Each group was divided into five subgroups (n = 24), and a universal restorative primer or multimode universal adhesive was used for each subgroup to bond plexiglas tubes filled with a composite resin to the ceramic plate. The specimens were stored in water at 37°C for 3 days without thermal cycling, or for 30 or 150 days with 7500 or 37,500 thermal cycles between 5°C and 55°C, respectively. All specimens then underwent tensile bond strength testing. Initially, all bonding systems exhibited high TBS, but some showed a significant reduction after 30 and 150 days of storage. After 3, 30, and 150 days, Monobond Plus, which contains silane and phosphate monomer, showed significantly higher bond strengths than the other universal primer and adhesive systems. The bond strength to lithium disilicate and zirconia ceramic is significantly affected by the bonding system used. Using a separate primer containg silane and phosphate monomer provides more durable bonding than do silanes incorporated in universal multimode adhesives. Only one of five so-called universal primers and adhesives provided durable bonding to lithium disilicate and zirconia ceramic.

  19. Micro-tensile bond strength of solely self-cured composite cement onto dentin

    OpenAIRE

    Suzuki, Thais Yumi Umeda; Santos, PH; de Munck, Jan; Van Meerbeek, Bart

    2016-01-01

    To evaluate bonding effectiveness of a new experimental composite cement to dentin in terms of microtensile bond strength (μTBS) after 1week (‘immediate’) and 6month (‘aged’) artificial aging. Flat ground dentin of 32 human molars was prepared using 600-grit SiC paper. Selfmade composite blocks (Clearfil AP-X,Kuraray Noritake) were bonded to flat dentin surfaces using 4 composite cements: Exp. HPC100 (Kuraray Noritake), Multilink (Ivoclar Vivadent), RelyX Unicem 2 and RelyX Ultimate ...

  20. Glass Fiber Post/Composite Core Systems Bonded to Human Dentin: Analysis of Tensile Load vs Calculated Tensile Strength of Various Systems Using Pull-out Tests.

    Science.gov (United States)

    Keul, Christine; Köhler, Patrick; Hampe, Rüdiger; Roos, Malgorzata; Stawarczyk, Bogna

    Pull-out testing was used to determine the tensile load (TL) and tensile strength (TS) of five different fiber post systems bonded to human intracanal dentin. 120 caries-free premolars, canines, and maxillary central incisors were divided into 5 different groups for 5 fiber post systems (n = 24): 1. RelyX Fiber Post 3D (RX3D); 2. RelyX Fiber Post (RX); 3. Luxa- Post (LP); 4. FibreKleer 4X Tapered Post (FK); 5. ParaPost Taper Lux (PP). The teeth were prepared and posts inserted. Core buildups were performed with the corresponding product's resin composite. All specimens were stored in water for 24 h at 37°C. TL and TS were tested on half of the specimens (n = 12/group). The remaining samples were thermocycled (10,000 x 5°C/55°C) before testing. TL was directly measured and TS was calculated using the bonding surface. Failure modes were identified using a stereomicroscope. Data were analyzed using twoway ANOVA with the post-hoc Scheffé test, as well as the chi-squared test (p post plus core buildup from the tooth; all other systems mainly demonstrated detachment of the core from the posts. PP, RX, and RX3D together with an adhesive core buildup yielded the highest bond strength to human dentin. Parameters TL and TS showed the same tendencies and statistical evidence.

  1. Effect of Re-Application of Microbrush on Micro Tensile Bond Strength of an Adhesive to Dentin

    Directory of Open Access Journals (Sweden)

    Seied Majid Mosavi Nasab

    2013-02-01

    Full Text Available Background and Aims: Re-application of microbrush may affect the micro tensile bond strength of adhesives to dentin. The aim of this study was to evaluate the effect of re-application of microbrushes on the micro tensile bond strength of an adhesive to dentin.Materials and Methods: Thirty freshly extracted molars teeth were collected and enamel of occlusal surface were removed to expose superficial dentin. Then superficial dentin was etched, washed and partially air dried.According to the times of application of microbrush, teeth were divided into two test groups. In group 1, newmicrobrushs were used, but in group 2, the ones that were already used for twice were included. Ambar dentin bonding agent (FGM/Brazil was applied to the etched dentin with microbrushes according to the manufacturer’s instructions. Then the crown of teeth was built up with LLiss (FGM/Brazil composite resin. The teeth were sectioned in buccolingual direction to obtain 1mm slabs. Then 50 hourglass- shape samples were made from 30 teeth (25 Specimens per group. The microtensile bond strength of the specimens was tested using MTD500 (SD Mechatronik, Germany. The data were statistically analyzed by T-test.Results: The mean values for the microtensile bond strength were 30.49±7.18 and 23.61±9.06 MPa±SD for the first and second groups, respectively. There was significant difference between the groups (P=0.005.Conclusion: Microbrushes should not be used for more than one cavity preparation.

  2. Evaluation of micro-tensile bond strength of caries-affected human dentine after three different caries removal techniques.

    Science.gov (United States)

    Sirin Karaarslan, E; Yildiz, E; Cebe, M A; Yegin, Z; Ozturk, B

    2012-10-01

    This study evaluated the effect that different techniques for removing dental caries had on the strength of the microtensile bond to caries-affected human dentine created by three bonding agents. Forty-five human molar teeth containing carious lesions were randomly divided into three groups according to the technique that would be used to remove the caries: a conventional bur, an Er:YAG laser or a chemo-mechanical Carisolv(®) gel (n=15). Next, each of the three removal-technique groups was divided into three subgroups according to the bonding agents that would be used: Clearfil(®) SE Bond, G-Bond(®), or Adper(®) Single Bond 2 (n=5). Three 1mm(2) stick-shaped microtensile specimens from each tooth were prepared with a slow-speed diamond saw sectioning machine fitted with a diamond-rim blade (n=15 specimens). For each removal technique one dentine sample was analysed using scanning electron microscopy. There were statistically significant differences in the resulting tensile strength of the bond among the techniques used to remove the caries and there were also statistically significant differences in the strength of the bond among the adhesive systems used. The etch-and-rinse adhesive system was the most affected by the technique used to remove the caries; of the three techniques tested, the chemo-mechanical removal technique worked best with the two-step self etch adhesive system. The bond strength values of the etch-and-rinse adhesive system were affected by the caries removal techniques used in the present study. However, in the one- and two-step self etch adhesive systems, bond strength values were not affected by the caries removal techniques applied. While a chemo-mechanical caries removal technique, similar to Carisolv(®), may be suggested with self etch adhesive systems, in caries removal techniques with laser, etch-and-rinse systems might be preferred. Caries removal methods may lead to differences in the characteristics of dentine surface. Dentine

  3. Tensile bond strength of a light-cured glass ionomer cement when used for bracket bonding under different conditions: an in vitro study.

    Science.gov (United States)

    Kirovski, I; Madzarova, S

    2000-12-01

    The purpose of this study was to investigate the tensile bond strength of a new light-cured resin reinforced glass ionomer cement (Fuji Ortho LC), following the bonding of stainless steel brackets to 40 extracted human premolar teeth under four different enamel surface conditions: (1) non-etched, moistened with water; (2) etched, moistened with water; (3) etched, moistened with human saliva; and (4) etched, moistened with human plasma. The etched surface produced a higher bond strength than the non-etched surface when contaminated with distilled water. Contamination with human saliva resulted in a further increase in bond strength whilst plasma contamination produced an even higher strength. However, one-way analysis of variance showed no statistically significant difference between the various groups. After debonding, enamel and bracket base surfaces were examined for residual adhesive. The location of the adhesive also indicated improved bonding to etched enamel. This investigation shows that regardless of enamel surface pretreatment or environment, Fuji Ortho LC provides an adequate strength for bonding of orthodontic brackets.

  4. Tensile bond strength of indirect composites luted with three new self-adhesive resin cements to dentin

    Directory of Open Access Journals (Sweden)

    Cafer Türkmen

    2011-08-01

    Full Text Available OBJECTIVE: The aims of this study were to evaluate the tensile bond strengths between indirect composites and dentin of 3 recently developed self-adhesive resin cements and to determine mode of failure by SEM. MATERIAL AND METHODS: Exposed dentin surfaces of 70 mandibular third molars were used. Teeth were randomly divided into 7 groups: Group 1 (control group: direct composite resin restoration (Alert with etch-and-rinse adhesive system (Bond 1 primer/adhesive, Group 2: indirect composite restoration (Estenia luted with a resin cement (Cement-It combined with the same etch-and-rinse adhesive, Group 3: direct composite resin restoration with self-etch adhesive system (Nano-Bond, Group 4: indirect composite restoration luted with the resin cement combined with the same self-etch adhesive, Groups 5-7: indirect composite restoration luted with self-adhesive resin cements (RelyX Unicem, Maxcem, and Embrace WetBond, respectively onto the non-pretreated dentin surfaces. Tensile bond strengths of groups were tested with a universal testing machine at a constant speed of 1 mm/min using a 50 kgf load cell. Results were statistically analyzed by the Student's t-test. The failure modes of all groups were also evaluated. RESULTS: The indirect composite restorations luted with the self-adhesive resin cements (groups 5-7 showed better results compared to the other groups (p0.05. The surfaces of all debonded specimens showed evidence of both adhesive and cohesive failure. CONCLUSION: The new universal self-adhesive resins may be considered an alternative for luting indirect composite restorations onto non-pretreated dentin surfaces.

  5. A Comparative Evaluation of the Effect of Bonding Agent on the Tensile Bond Strength of Two Pit and Fissure Sealants Using Invasive and Non-invasive Techniques: An in–vitro Study

    Science.gov (United States)

    Singh, Shamsher; Adlakha, Vivek; Babaji, Prashant; Chandna, Preetika; Thomas, Abi M.; Chopra, Saroj

    2013-01-01

    Background: Newer technologies and the development of pit and fissure sealants have shifted the treatment philosophy from ‘drill and fill’ to that of ‘seal and heal’. Aims: The purpose of this in–vitro study was to evaluate the effects of bonding agents on the tensile bond strengths of two pit and fissure sealants by using invasive and non-invasive techniques. Study Design and Methods: One hundred and twenty bicuspids were collected and teeth were divided into two groups: Group-I (Clinpro) and Group-II (Conseal f) with 60 teeth in each group. For evaluating tensile bond strengths, occlusal surfaces of all the teeth were flattened by reducing buccal and lingual cusps without disturbing fissures. Standardised polyvinyl tube was bonded to occlusal surfaces with respective materials. Sealants were applied, with or without bonding agents, in increments and they were light cured. Tensile bond strengths were determined by using Universal Testing Machine. Statistical Analysis: Data were then statistically analysed by using Student t–test for comparison. Results: A statistically significant difference was found in tensile bond strength in invasive with bonding agent group than in non-invasive with bonding agent group. Conclusion: This study revealed that invasive techniques increase the tensile bond strengths of sealants as compared to non- invasive techniques and that the use of a bonding agent as an intermediate layer between the tooth and fissure sealant is beneficial for increasing the bond strength. PMID:24298525

  6. Effect of reactive adhesives on the tensile bond strength of polyvinyl siloxane impression materials to methyl methacrylate tray material.

    Science.gov (United States)

    Ona, Masahiro; Takahashi, Hidekazu; Sato, Masayuki; Igarashi, Yoshimasa; Wakabayashi, Noriyuki

    2010-05-01

    The effect of new adhesives on the bond strength of elastomeric impression materials to acrylic trays was evaluated. Two polyvinyl siloxane impression materials (Fusion and Imprinsis) with reactive adhesives and one (Examix) with a conventional adhesive were tested. Flat, double-sided plates of auto-polymerizing methyl methacrylate (10 x 10 x 2.5 mm) were prepared with one of the adhesives. Five specimens were prepared by injecting each impression material into a 2-mm gap between the two plates. Tensile tests were conducted until separation failure occurred. The mean bond strengths of Fusion (1.0 MPa) and Imprinsis (0.8 MPa) were significantly greater than that of Examix (0.2 MPa). On the contrary, one of five Fusion showed adhesive failure mode while all the Imprinsis exhibited mixed failure. The conflicting results were presumably attributed to the mean tear strength of Fusion (0.8 N/mm) being higher than that of Imprinsis (0.5 N/mm).

  7. Degradation of Peel and Tensile Strength of Bonded Panels Exposed to High Humidity

    National Research Council Canada - National Science Library

    Rider, Andrew

    2001-01-01

    .... The work presented in this report summarizes honeycomb studies undertaken in AIR task 98/186 that were designed to examine the influence that environmental exposure would have on the peel and tensile...

  8. Effect of luting agents on the tensile bond strength of glass fiber posts: An in vitro study.

    Science.gov (United States)

    Aleisa, Khalil; Al-Dwairi, Ziad N; Alghabban, Rawda; Goodacre, Charles J

    2013-09-01

    Fiber posts can fail because of loss of retention; and it is unknown which luting agent provides the highest bond strength. The purpose of this study was to investigate the tensile bond strength of glass fiber posts luted to premolar teeth with 6 resin composite luting agents. Ninety-six single-rooted extracted human mandibular premolars were sectioned 2 mm coronal to the most incisal point of the cementoenamel junction. Root canals were instrumented and obturated with laterally condensed gutta percha and root canal sealer (AH26). Gutta percha was removed from the canals to a depth of 8 mm and diameter post spaces with a 1.5 mm were prepared. The specimens were divided into the following 6 groups according to the luting agent used (n=16): Group V, Variolink II; Group A, RelyX ARC; Group N, Multilink N; Group U, RelyX Unicem; Group P, ParaCore; Group F, MultiCore Flow. Each specimen was secured in a universal testing machine and a separating load was applied at a rate of 0.5 mm/min. The forces required to dislodge the posts were recorded. A 1-way analysis of variance (ANOVA) was applied to the mean retentive strengths of various cement materials (α=.05). Significant differences were recorded among the 6 cement types (PFiber posts luted with RelyX Unicem, Paracore, and MultiCore Flow demonstrated significantly higher bond strengths. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  9. Comparative evaluation of tensile bond strengths of total-etch adhesives and self-etch adhesives with single and multiple consecutive applications: An in vitro study

    OpenAIRE

    Mandava, Deepthi; P, Ajitha; Narayanan, L Lakshmi

    2009-01-01

    Aim: This study evaluates the effect of single and multiple consecutive applications of adhesives on the tensile bond strength. The currently available adhesives follow either the total-etch or the self-etch concept. However, in both techniques the uniformity and thickness of the adhesive layer plays a significant role in the development of a good bond. Materials and Methods: Sixty composite-dentin bonded specimens were prepared using a total-etch adhesive (Gluma) and another 60 using a self-...

  10. The Tensile and Shear Bond Strengths of Poly (Methyl Methacrylate) Processed on Electrolytically Etched Ticonium.

    Science.gov (United States)

    1986-05-01

    developed a technique for retention of resin veneers on complete crowns by using a pitting corrosion of the nickel-chromium copper alloy. McLaughlin (1981...bridges. Pediatr Dent. 4: 38-43. 98. Thompson, V.P., K. Grolman, and R. Liao. 1984. Electrolytic etching of Co-Cr alloys for resin bonded restorations...CLASSIFICATION OF THIS PAGE (4ihen Data Entered) , .. ’ .’ " -’, , :-.. ~ -., , I .. 2 INTRODUCTION The rtention of acrylic denture resins to metal based

  11. Long-term tensile bond strength of differently cemented nanocomposite CAD/CAM crowns on dentin abutment.

    Science.gov (United States)

    Stawarczyk, Bogna; Stich, Nicola; Eichberger, Marlis; Edelhoff, Daniel; Roos, Malgorzata; Gernet, Wolfgang; Keul, Christine

    2014-03-01

    To test the tensile bond strength of luted composite computer aided design/computer aided manufacturing (CAD/CAM) crowns after use of different adhesive systems combined with different resin composite cements on dentin abutments. Human molars (n=200) were embedded in acrylic resin, prepared in a standardized manner and divided into 20 groups (n=10). The crowns were treated as follows: (i) Monobond Plus/Heliobond (MH), (ii) Ambarino P60 (AM), (iii) Visio.link (VL), (iv) VP connect (VP), and (v) non-treated as control groups (CG) and luted with Variolink II (VAR) or Clearfil SA Cement (CSA). Tensile bond strength (TBS) was measured initially (24h water, 37°C) and after aging (5000 thermal cycles, 5/55°C). The failure types were evaluated after debonding. TBS values were analyzed using three-way and one-way ANOVA, followed by post hoc Scheffé-test, and two-sample Student's t-tests. Among VAR and after aging, CG presented significantly higher TBS (p=0.007) than groups treated with MH, AM and VP. Other groups showed no impact of pre-treatment. A decrease of TBS values after thermal aging was observed within CSA: CG (p=0.002), MH (p<0.001), VL (p<0.001), AM (p=0.002), VP (p<0.001) and within VAR: MH (p=0.002) and AM (p=0.014). Groups cemented with VAR showed significantly higher TBS then groups cemented with CSA: non-aged groups: CG (p<0.001), and after thermal aging: CG (p=0.003), MH (p<0.001), VL (p=0.005), VP (p=0.010). According to the study results nano-composite CAD/CAM crowns should be cemented with VAR. Pre-treatment is not necessary if the tested resin composite cements are used. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  12. Correlative analysis of cement-dentin interfaces using an interfacial fracture toughness and micro-tensile bond strength approach.

    Science.gov (United States)

    Souza, Evelise M; De Munck, Jan; Pongprueksa, Pong; Van Ende, Annelies; Van Meerbeek, Bart

    2016-12-01

    To determine the interfacial fracture toughness (iFT) and micro-tensile strength (μTBS) of composite cements bonded to dentin. Fifty feldspar ceramic blocks (Vita Mark II, Vita Zahnfabrik) were luted onto dentin using two self-adhesive (G-CEM LinkAce, GC; SpeedCEM, Ivoclar Vivadent), two self-etch (Multilink Primer & Multilink Automix, Ivoclar Vivadent; Scotchbond Universal & RelyX Ultimate, 3 M ESPE), and one etch-and-rinse (Excite F DSC & Variolink II, Ivoclar Vivadent) composite cement (n=10). After 48h in 100% relative humidity at 37°C, one half of each tooth was sectioned in sticks with a chevron notch at the cement-dentin interface and tested in a 4-point bending test setup (iFT). The remaining half of the tooth was sectioned in micro-specimens and stressed in tension until failure (μTBS). The mode of failure was determined with a stereomicroscope at 50× magnification. Data were submitted to Weibull analysis and Pearson's correlation (α=0.05). At 10% probability of failure, no significant differences could be found using iFT, while the etch-and-rinse composite cement Variolink II presented a significantly higher μTBS at this level. At 63.2% probability of failure, the self-adhesive composite cement G-CEM LinkAce revealed a significantly lower μTBS and iFT, and the self-etch cement Multilink Automix also revealed a significantly lower μTBS than all other cements. The correlation found between iFT and μTBS was moderate and not significant (r(2)=0.618, p=0.11). Overall, the etch-and-rinse and 'universal' self-etch composite cements performed best. The micro-tensile bond strength and interfacial fracture toughness tests did not correlate well. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  13. INFLUENCE OF SILANE HEAT TREATMENT ON THE TENSILE BOND STRENGTH BETWEEN EX-3 SYNTHETIC VENEERING PORCELAIN AND COMPOSITE RESIN USING FIVE DIFFERENT ACTIVATION TEMPERATURES

    Directory of Open Access Journals (Sweden)

    Spartak Yanakiev

    2017-02-01

    Full Text Available Purpose: The purpose of the present study is to assess the effect of five different silane activation temperatures and eight activation methods on the tensile bond strength between one veneering porcelain and one composite resin material. Material and methods: A total of 81 ceramic rods were made of EX-3 veneering ceramic (Kuraray Noritake Dental, Japan. Sintered ceramic bars were grinded with diamond disks to size 10x2x2mm ± 0,05mm. The front part of each bar was polished. After ultrasonic cleaning in distilled water, the specimens were divided into nine groups. Silane was activated with air at room temperature, 38º С, 50º С, 100º С, 120º С using a custom made blow drier. In a silicone mold, a composite resin Z250 (3М ESPE, St. Paul, USA was condensed toward the bond ceramic surface. A total of 81 specimens approximately 2,0 cm long were prepared for tensile bond testing. One way ANOVA, followed by Bonferroni and Games-Howell tests were used for statistical analysis. Results: The lowest tensile bond strength was observed in the control group (3,51MPa. Group 2 yielded the highest bond strength among all groups (19,54MPa. Silane heat treatment enhanced the bond strength for all treatment methods. Within the polished specimens, the highest bond strength was yielded with warm air at 120ºС (11,31MPa. Conclusion: The most effective method for bonding Z250 composite resin to EX-3 veneering ceramic includes HF etching, silane, and adhesive resin. The most effective heat treatment method for bonding is hot air at 120ºС.

  14. Academy of Dental Materials guidance on in vitro testing of dental composite bonding effectiveness to dentin/enamel using micro-tensile bond strength (μTBS) approach.

    Science.gov (United States)

    Armstrong, Steve; Breschi, Lorenzo; Özcan, Mutlu; Pfefferkorn, Frank; Ferrari, Marco; Van Meerbeek, Bart

    2017-02-01

    An ideal dental adhesive should provide retentive strength, marginal seal, be relatively simple to achieve and demonstrate clinical durability. Future improvements in adhesive bonding to tooth structure require in vitro test methods that provide reliable data for materials development and/or evaluation of experimental variables. The objective of this project was to identify a test method that is relatively easy to perform, repeatable and ultimately useful for predicting clinical outcomes. The Academy of Dental Materials initiated a project to develop and distribute guidance documents on laboratory test methods that are useful for the evaluation of dental adhesives and cements, composite resins and ceramics. The dental adhesive sub-group has identified the micro-tensile bond strength test, especially after subjecting the specimens to a durability challenge, as currently the best practical surrogate measure of dental composite restoration retention. The following μTBS guidance is meant to aid the researcher in conducting the μTBS test. The authors, while recognizing the limitations of a static, strength-based test method, welcome comments and suggestions for improvements of this guidance document in future revisions. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  15. To evaluate and compare the effect of different Post Surface treatments on the Tensile Bond Strength between Fiber Posts and Composite Resin.

    Science.gov (United States)

    Shori, Deepa; Pandey, Swapnil; Kubde, Rajesh; Rathod, Yogesh; Atara, Rahul; Rathi, Shravan

    2013-10-01

    Fiber posts are widely used for restoration of mutilated teeth that lack adequate coronal tooth structure to retain a core for definitive restoration, bond between the fiber post and composite material depends upon the chemical reaction between the post surface and the resin material used for building up the core. In attempt to maximize the resin bonding with fiber post, different post surface conditioning is advocated. Therefore the purpose of the study is to examine the interfacial strength between fiber post and composite, as core build-up material after different surface treatments of fiber posts. Twenty fiber posts were split into four groups off five each according to different surface treatments viz. Group I-(Negative Control), Group II-Silanization (Positive control), Group III-(37% Phosphoric Acid & Silanization) ,Group IV- (10% Hydrogen Peroxide and Silanization). With the preformed plastic mould, a core of dual cure composite resin around the fiber post having the uniform thickness was created. Tensile bond strength of each specimen was measured under Universal Testing Machine (UTM) at the cross head speed of 3mm/min. The results achieved with 10% Hydrogen peroxide had a marked effect on micro tensile bond strength values between the tested materials. Immense enhancement in the silanization efficiency of quartz fiber phase was observed with different surface chemical treatment of the resin phase of fiber posts with the marked increase in the micro-tensile bond strength between fiber post and composite core. Shori D, Pandey S, Kubde R, Rathod Y, Atara R, Rathi S. To evaluate and compare the effect of different Post Surface treatments on the Tensile Bond Strength between Fiber Posts and Composite Resin. J Int Oral Health 2013; 5(5):27-32.

  16. Evaluation of pH, ultimate tensile strength, and micro-shear bond strength of two self-adhesive resin cements

    Directory of Open Access Journals (Sweden)

    Luciana Artioli COSTA

    2014-01-01

    Full Text Available The aim of this study was to evaluate the pH, ultimate tensile strength (UTS, and micro-shear bond strength (µSBS of two self-adhesive resin cements to enamel and dentin. Sound bovine incisors (n = 10 and two self-adhesive resin cements (i.e., RelyX U-100 and seT PP were used. The pH of the resin cements was measured using a pH-indicator paper (n = 3. Specimens for UTS were obtained from an hourglass-shaped mold. For µSBS, cylinders with internal diameter of 0.75 mm and height of 0.5 mm were bonded to the flat enamel and dentin surfaces. Bonded cylinders were tested in the shear mode using a loop wire. The fracture mode was also evaluated. The cement seT PP showed a low pH; U-100 showed significantly higher UTS (49.9 ± 2.0 than seT PP (40.0 ± 2.1 (p < 0.05 and high µSBS to enamel (10.7 ± 3.7. The lowest µSBS was found for seT PP to dentin (0.7 ± 0.6; seT PP to enamel (4.8 ± 1.7, and for U-100 to dentin (7.2 ± 1.9, showing an intermediate µSBS value (p < 0.05. Adhesive failure was the most frequently observed failure mode. The resin cement that presented the lowest pH and UTS also presented the lowest micro-shear bond strength to enamel and dentin.

  17. Effects of surface treatments and storage times on the tensile bond strength of adhesive cements to noble and base metal alloys.

    Science.gov (United States)

    Burmann, Paulo Afonso; Santos, Jose Fortunato Ferreira; May, Liliana Gressler; Pereira, Joao Eduardo da Silva; Cardoso, Paulo Eduardo Capel

    2008-01-01

    This work evaluated two resin cements and a glass-ionomer cement and their bond strength to gold-palladium (Au-Pd), silver-palladium (Ag-Pd), and nickel-chromium-beryllium (Ni-Cr-Be) alloys, utilizing three surface treatments over a period of six months. Eight hundred ten pieces were cast (in a button shape flat surfaces) in one of three alloys. Each alloy group was assigned to three other groups, based on the surface treatment utilized. Specimens were fabricated by bonding similar buttons in using one of three adhesive cements. The 405 pairs were thermocycled and stored in saline solution (0.9% NaCl) at 37 degrees C. The tensile bond strengths were measured in a universal testing machine after storage times of 2, 90, or 180 days. The highest mean bond strength value was obtained with the base metal alloy (10.9 +/- 8.6 MPa). In terms of surface treatment, oxidation resulted in the highest mean bond strength (13.7 +/- 7.3 MPa), followed by sandblasting (10.3 +/- 5.5 MPa) and polishing (3.0 +/- 6.4 MPa). Panavia Ex (13.2 +/- 9.3 MPa) showed significantly higher bond strengths than the other two cements, although the storage time reduced all bond strengths significantly.

  18. Microstructure, Tensile Adhesion Strength and Thermal Shock Resistance of TBCs with Different Flame-Sprayed Bond Coat Materials Onto BMI Polyimide Matrix Composite

    Science.gov (United States)

    Abedi, H. R.; Salehi, M.; Shafyei, A.

    2017-10-01

    In this study, thermal barrier coatings (TBCs) composed of different bond coats (Zn, Al, Cu-8Al and Cu-6Sn) with mullite top coats were flame-sprayed and air-plasma-sprayed, respectively, onto bismaleimide matrix composites. These polyimide matrix composites are of interest to replace PMR-15, due to concerns about the toxicity of the MDA monomer from which PMR-15 is made. The results showed that pores and cracks appeared at the bond coat/substrate interface for the Al-bonded TBC because of its high thermal conductivity and diffusivity resulting in transferring of high heat flux and temperature to the polymeric substrate during top coat deposition. The other TBC systems due to the lower conductivity and diffusivity of bonding layers could decrease the adverse thermal effect on the polymer substrate during top coat deposition and exhibited adhesive bond coat/substrate interfaces. The tensile adhesion test showed that the adhesion strength of the coatings to the substrate is inversely proportional to the level of residual stress in the coatings. However, the adhesion strength of Al bond-coated sample decreased strongly after mullite top coat deposition due to thermal damage at the bond coat/substrate interface. TBC system with the Cu-6Sn bond coat exhibited the best thermal shock resistance, while Al-bonded TBC showed the lowest. It was inferred that thermal mismatch stresses and oxidation of the bond coats were the main factors causing failure in the thermal shock test.

  19. Influence of chemical irrigants on the tensile bond strength of an adhesive system used to cement glass fiber posts to root dentin.

    Science.gov (United States)

    Pelegrine, Rina Andréa; De Martin, Alexandre Sigrist; Cunha, Rodrigo Sanches; Pelegrine, André Antonio; da Silveira Bueno, Carlos Eduardo

    2010-11-01

    The aim of this study was to evaluate the influence of endodontic irrigants on the tensile bond strength of an adhesive system used to cement glass fiber posts to dentin. Fifty bovine roots were divided into 5 groups according to the solution used during instrumentation: G1, 0.9% NaCl (control); G2, 1.0% NaOCl; G3, 2.5% NaOCl; G4, 5.25% NaOCl; G5, 2% chlorhexidine gel + 0.9% NaCl. The root canals were obturated with gutta-percha and AH Plus sealer, and the glass fiber posts were cemented with Clearfil SE Bond/RelyX ARC. The specimens were submitted to tensile strength testing and the results were analyzed by analysis of variance. There were no statistically significant differences regarding the irrigant solution factor (P > .70). It was concluded that the different irrigant solutions did not affect the tensile bond strength of the fixation system used to cement the intraradicular glass fiber posts to dentin. Copyright © 2010 Mosby, Inc. All rights reserved.

  20. Tensile bond strength of resin-modified glass-ionomer cement to microabraded and silica-coated or tin-plated high noble ceramic alloy.

    Science.gov (United States)

    Swartz, J M; Davis, R D; Overton, J D

    2000-12-01

    The purpose of this study was to evaluate the influence of alloy surface microabrasion, silica coating, or microabrasion plus tin plating on the tensile bond strengths between a resin-modified glass-ionomer luting cement and a high-noble alloy. Bond strength between the microabraded alloy specimens and conventional glass-ionomer cement or resin cement were included for comparison. One hundred twenty uniform size, disk-shaped specimens were cast in a noble metal alloy and divided into 6 groups (n = 10 pairs/group). The metal surfaces of the specimens in each group were treated and cemented as follows. Group 1: No surface treatment (as cast, control), cemented with a resin-modified glass-ionomer cement. Group 2: Microabrasion with 50-microm aluminum oxide particles, resin-modified glass-ionomer cement. Group 3: A laboratory microabrasion and silica coating system, resin-modified glass-ionomer cement. Group 4: Microabrasion and tin-plating, resin-modified glass-ionomer cement. Group 5: Microabrasion only, conventional glass-ionomer cement. Group 6: Microabrasion and tin-plating, conventional resin cement. The uniaxial tensile bond strength for each specimen pair was determined using an Instron Universal Testing Machine (Instron Corp, Canton, MA). Results were analyzed using a one-way analysis of variance (alpha = 0.05) and a Tukey post-hoc analysis. Mean bond strength: Group 1: 3.6 (+/- 1.5) MPa. Group 2: 4.2 (+/-0.5) MPa. Group 3: 6.7 (+/- 0.9) MPa. Group 4: 10.6 (+/- 1.8) MPa. Group 5: 1.1 (+/- 0.4) MPa. Group 6: 14.6 (+/- 2.3) MPa. Group 6 was significantly stronger than Group 4. The bond strength of specimens cemented with the resin-modified glass-ionomer cement using microabrasion and tin-plating (Group 4) was significantly stronger than all other groups except the resin cement with microabrasion and tin-plating (Group 6). Microabraded and tin-plated alloy specimens luted with the resin-modified glass-ionomer cement resulted in the greatest mean tensile strengths

  1. Effects of pulsed Nd:YAG laser on tensile bond strength and caries resistance of human enamel.

    Science.gov (United States)

    Wen, X; Zhang, L; Liu, R; Deng, M; Wang, Y; Liu, L; Nie, X

    2014-01-01

    This study aims to evaluate the effects of pulsed Nd:YAG laser on the tensile bond strength (TBS) of resin to human enamel and caries resistance of human enamel. A total of 201 human premolars were used in this in vitro study. A flat enamel surface greater than 4 × 4 mm in area was prepared on each specimen using a low-speed cutting machine under a water coolant. Twenty-one specimens were divided into seven groups for morphology observations with no treatment, 35% phosphoric acid etching (30 seconds), and laser irradiation (30 seconds) of pulsed Nd:YAG laser with five different laser-parameter combinations. Another 100 specimens were used for TBS testing. They were embedded in self-cured acrylic resin and randomly divided into 10 groups. After enamel surface pretreatments according to the group design, resin was applied. The TBS values were tested using a universal testing machine. The other 80 specimens were randomly divided into eight groups for acid resistance evaluation. Scanning electron microscope (SEM) results showed that the enamel surfaces treated with 1.5 W/20 Hz and 2.0 W/20 Hz showed more etching-like appearance than those with other laser-parameter combinations. The laser-parameter combinations of 1.5 W/15 Hz and 1.5 W/20 Hz were found to be efficient for the TBS test. The mean TBS value of 14.45 ± 1.67 MPa in the laser irradiated group was significantly higher than that in the untreated group (3.48 ± 0.35 MPa) but lower than that in the 35% phosphoric acid group (21.50 ± 3.02 MPa). The highest mean TBS value of 26.64 ± 5.22 MPa was identified in the combination group (laser irradiation and then acid etching). Acid resistance evaluation showed that the pulsed Nd:YAG laser was efficient in preventing enamel demineralization. The SEM results of the fractured enamel surfaces, resin/enamel interfaces, and demineralization depths were consistent with those of the TBS test and the acid resistance evaluation. Pulsed Nd:YAG laser as an enamel surface

  2. Assessment of Tensile Bond Strength of Fiber-Reinforced Composite Resin to Enamel Using Two Types of Resin Cements and Three Surface Treatment Methods

    Directory of Open Access Journals (Sweden)

    Tahereh Ghaffari

    2015-10-01

    Full Text Available Background: Resin-bonded bridgework with a metal framework is one of the most conservative ways to replace a tooth with intact abutments. Visibility of metal substructure and debonding are the complications of these bridgeworks. Today, with the introduction of fiber-reinforced composite resins, it is possible to overcome these complications. The aim of this study was to evaluate the bond strength of fiber-reinforced composite resin materials (FRC to enamel. Methods: Seventy-two labial cross-sections were prepared from intact extracted teeth. Seventy-two rectangular samples of cured Vectris were prepared and their thickness was increased by adding Targis. The samples were divided into 3 groups for three different surface treatments: sandblasting, etching with 9% hydrofluoric acid, and roughening with a round tapered diamond bur. Each group was then divided into two subgroups for bonding to etched enamel by Enforce and Variolink II resin cements. Instron universal testing machine was used to apply a tensile force. The fracture force was recorded and the mode of failure was identified under a reflective microscope. Results: There were no significant differences in bond strength between the three surface treatment groups (P=0.53. The mean bond strength of Variolink II cement was greater than that of Enforce (P=0.04. There was no relationship between the failure modes (cohesive and adhesive and the two cement types. There was some association between surface treatment and failure mode. There were adhesive failures in sandblasted and diamond-roughened groups and the cohesive failure was dominant in the etched group. Conclusion: It is recommended that restorations made of fiber-reinforced composite resin be cemented with VariolinkII and surface-treated by hydrofluoric acid.   Keywords: Tensile bond strength; surface treatment methods; fiber-reinforced composite resin

  3. The effect of different pretreatment methods of PMMA-based crowns on the long-term tensile bond strength to dentin abutments.

    Science.gov (United States)

    Keul, Christine; Kohen, Daliah; Eichberger, Marlis; Roos, Malgorzata; Gernet, Wolfgang; Stawarczyk, Bogna

    2015-01-01

    The objective of the study was to test the effect of different pretreatments on tensile bond strength (TBS) of adhesively bonded CAD/CAM-generated polymethyl methacrylate (PMMA) crowns to dentin. Two hundred human molars were prepared and divided into 20 groups (n = 10/group). PMMA crowns were pretreated thusly: Monobond Plus/Heliobond (MH), Visio.link (VL), Ambarino P60 (AM), VP connect (VP), and nontreated as control groups (CG). Two resin cements were used for cementation of crowns: Clearfil SA Cement (CSA) and Variolink II (VAR). TBS was measured initially (24 h water storage, 37 °C) and after aging (5,000 thermal cycles, 5/55 °C). TBS was analyzed using one-way ANOVA with Scheffé post hoc, unpaired Student t, Mann-Whitney U, Kruskal-Wallis H, and chi-squared tests. Within CSA, pretreatment with MH and VL showed higher initial TBS compared with AM-treated groups. All other groups showed no statistical differences. For MH, VL, AM, and VP in combination with CSA, a negative impact of aging was observed (p < 0.001), whereas in all VAR groups, no impact was measured. Pretreatment with MH (p = 0.001) and VP (p = 0.008) presented higher initial TBS for CSA than for VAR. After aging, MH (p = 0.025) and VL (p = 0.034) cemented with VAR showed higher results than CSA. All tested groups showed very low TBS values. Pretreatments with MH, VL, and VP have minimally improved the tensile strength after aging. Although the tensile strength results were low, crowns adhesively cemented with pretreatments with MH, VL, and VP showed, after aging, a higher tensile strength than nontreated groups.

  4. Comparative evaluation of tensile bond strengths of total-etch adhesives and self-etch adhesives with single and multiple consecutive applications: An in vitro study

    OpenAIRE

    Mandava Deepthi; Ajitha P; Narayanan L

    2009-01-01

    Aim: This study evaluates the effect of single and multiple consecutive applications of adhesives on the tensile bond strength. The currently available adhesives follow either the total-etch or the self-etch concept. However, in both techniques the uniformity and thickness of the adhesive layer plays a significant role in the development of a good bond. Materials and Methods: Sixty composite-dentin bonded specimens were prepared using a total-etch adhesive (Gluma) and another 60 using a sel...

  5. Unexpectedly low tensile strength in concrete structures

    NARCIS (Netherlands)

    Siemes, A.J.M.; Han, N.; Visser, J.H.M.

    2002-01-01

    During an extensive investigation of some 25 concrete bridges and other structures suffering from alkali-silica reaction it has been found that the uniaxial tensile strength of the concrete was extremely low in relation to both the compressive strength and the splitting tensile strength. It is known

  6. Comparative study on the tensile bond strength and marginal fit of complete veneer cast metal crowns using various luting agents: An in vitro study

    Directory of Open Access Journals (Sweden)

    B Devi Parameswari

    2016-01-01

    Full Text Available Introduction: Several commercially available luting agents are used to cement the dental restorations such as intra-coronal, extra-coronal, and fixed partial dentures. Tensile bond strength (TBS and accurate marginal fit are the essential factors to determine the good clinical results in fixed prosthesis. The retentivity of the luting cements is assessed by their adhesive capacity over the tooth surface and metal surface. Generally, the adhesive ability has been evaluated with in vitro testing, with tensile bond tests. The failure of fixed prosthesis may be happened as a result of incomplete seating during cementation. Most research on cementation of crowns relates seating failure to the thickness of the cement film. Materials and Methods: The study is divided into four groups with 10 samples for each of the luting cement taken up for testing TBS and four groups with 5 samples for each luting agent chosen for assessing marginal fit. The results were tabulated and statistically analyzed. Results: In this in vitro study, the TBS of luting cements, and marginal fit in relation to luting cements were tested by using appropriate testing devices. The TBS of cement is measured using universal testing machine, and the results are tabulated. The marginal gap that exists between the margin of the cast metal crown, and the finish line is measured using travelling microscope before and after cementation. The difference between these two values gives the discrepancy that is due to the film thickness of cement used for luting the restoration. Summary and Conclusion: The TBS value of zinc phosphate cement and glass ionomer cement were found to be almost same. The chemical adhesiveness of the glass ionomer with calcium ions of enamel and dentin may be the attributed reason (ionic bonding. In this study, the polycarboxylate is the one that showed low TBS, and it may be attributed to the weakness of the cement due to reduced film thickness, though this cement has

  7. Effects of interacting variables on the tensile strength and the ...

    African Journals Online (AJOL)

    ... which represented the “high” level, was used as binding agent at concentrations of 0.5% and 4%w/w in a paracetamol tablet formulation. The tensile strength, which is a measure of the bond strength of tablets, and the release properties of the tablets- measured by the disintegration and the dissolution times, were used as ...

  8. Surfactant effects on soil aggregate tensile strength

    Science.gov (United States)

    Little is known regarding a soil aggregate's tensile strength response to surfactants that may be applied to alleviate soil water repellency. Two laboratory investigations were performed to determine surfactant effects on the tensile strength of 1) Ap horizons of nine wettable, agricultural soils co...

  9. The effect of air abrasion of metal implant abutments on the tensile bond strength of three luting agents used to cement implant superstructures: an in vitro study.

    Science.gov (United States)

    Jugdev, Jasvinder; Borzabadi-Farahani, Ali; Lynch, Edward

    2014-01-01

    To assess the effect of airborne particle abrasion of metal implant abutments on tensile bond strength (TBS) of TempBond, Retrieve, and Premier implant cements. Specimens were designed to replicate a single metal implant crown cemented to both smooth and airborne particle-abraded Osteo-Ti implant abutments with zero degrees of taper. Twenty castings were fabricated and cemented to either a smooth surface abutment (SSA) or to an airborne particle-abraded abutment (AAA). TBS was measured with a 50-kg load and a crosshead speed of 0.5 cm/min in a universal testing machine. Each cement was tested 10 times on both abutment types. The mean TBS values (standard deviations, 95% confidence intervals) of SSAs for TempBond, Retrieve, and Premier cements were 115.89 N (26.44, 96.98-134.81), 134.43 N (36.95, 108.25-160.60), and 132.51 N (55.10, 93.09-171.93), respectively. The corresponding values for AAAs were 129.69 N (30.39, 107.95-151.43), 298.67 N (80.36, 241.19-356.16), and 361.17 N (133.23, 265.86-456.48), respectively. There was no significant difference in TBS among the dental cements when used with an SSA. Air abrasion of abutments did not increase the TBS of TempBond but significantly increased crown retention with Retrieve and Premier. For SSAs, all failures were adhesive on the abutment surface; for AAAs, mostly cohesive cement failures occurred. The retention of copings cemented with Retrieve or Premier to zero-degree-taper abutments was significantly increased after airborne particle abrasion of the abutments. However, this was not significant when TempBond was used. Airborne particle abrasion of abutments and the use of Retrieve or Premier can be recommended for nonretrievable prostheses. Although TempBond functioned similarly to the two other cements in SSAs, it is advisable to limit its use to provisional prostheses; its long-term performance needs to be assessed clinically.

  10. Tensile bond strength and SEM analysis of enamel etched with Er:YAG laser and phosphoric acid: a comparative study in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Luis H.; Tanaka, Celso Shin-Ite [Bandeirante University of Sao Paulo, Sao Paulo, SP (Brazil). Dept. of Prosthodontics; Lobo, Paulo D.C.; Villaverde, Antonio B.; Moriyama, Eduardo H.; Brugnera Junior, Aldo [University of Vale do Paraba, Sao Jose dos Campos, SP (Brazil). Inst. of Research and Development]. E-mail: abrugnera@uol.com.br; Moriyama, Yumi [Ontario Cancer Institute, Toronto, ON (Canada). Div. of Biophysics and Bioimaging; Watanabe, Ii-Sei [University of Sao Paulo (USP), SP (Brazil). Inst. of Biomedical Sciences

    2008-01-15

    Er:YAG laser has been studied as a potential tool for restorative dentistry due to its ability to selectively remove oral hard tissue with minimal or no thermal damage to the surrounding tissues. The purpose of this study was to evaluate in vitro the tensile bond strength (TBS) of an adhesive/composite resin system to human enamel surfaces treated with 37% phosphoric acid, Er:YAG laser ({lambda}=2.94 {mu}m) with a total energy of 16 J (80 mJ/pulse, 2Hz, 200 pulses, 250 ms pulse width), and Er:YAG laser followed by phosphoric acid etching. Analysis of the treated surfaces was performed by scanning electron microscopy (SEM) to assess morphological differences among the groups. TBS means (in MPa) were as follows: Er:YAG laser + acid (11.7 MPa) > acid (8.2 MPa) > Er:YAG laser (6.1 MPa), with the group treated with laser+acid being significantly from the other groups (p=0.0006 and p= 0.00019, respectively). The groups treated with acid alone and laser alone were significantly different from each other (p=0.0003). The SEM analysis revealed morphological changes that corroborate the TBS results, suggesting that the differences in TBS means among the groups are related to the different etching patterns produced by each type of surface treatment. The findings of this study indicate that the association between Er:YAG laser and phosphoric acid can be used as a valuable resource to increase bond strength to laser-prepared enamel. (author)

  11. Comparative evaluation of tensile bond strength of a polyvinyl acetate-based resilient liner following various denture base surface pre-treatment methods and immersion in artificial salivary medium: An in vitro study

    Directory of Open Access Journals (Sweden)

    Jacob M Philip

    2012-01-01

    Full Text Available Background and Aim: This study was formulated to evaluate and estimate the influence of various denture base resin surface pre-treatments (chemical and mechanical and combinations upon tensile bond strength between a poly vinyl acetate-based denture liner and a denture base resin. Materials and Methods: A universal testing machine was used for determining the bond strength of the liner to surface pre-treated acrylic resin blocks. The data was analyzed by one-way analysis of variance and the t-test (α =.05. Results: This study infers that denture base surface pre-treatment can improve the adhesive tensile bond strength between the liner and denture base specimens. The results of this study infer that chemical, mechanical, and mechano-chemical pre-treatments will have different effects on the bond strength of the acrylic soft resilient liner to the denture base. Conclusion: Among the various methods of pre-treatment of denture base resins, it was inferred that the mechano-chemical pre-treatment method with air-borne particle abrasion followed by monomer application exhibited superior bond strength than other methods with the resilient liner. Hence, this method could be effectively used to improve bond strength between liner and denture base and thus could minimize delamination of liner from the denture base during function.

  12. Making High-Tensile-Strength Amalgam Components

    Science.gov (United States)

    Grugel, Richard

    2008-01-01

    Structural components made of amalgams can be made to have tensile strengths much greater than previously known to be possible. Amalgams, perhaps best known for their use in dental fillings, have several useful attributes, including room-temperature fabrication, corrosion resistance, dimensional stability, and high compressive strength. However, the range of applications of amalgams has been limited by their very small tensile strengths. Now, it has been discovered that the tensile strength of an amalgam depends critically on the sizes and shapes of the particles from which it is made and, consequently, the tensile strength can be greatly increased through suitable choice of the particles. Heretofore, the powder particles used to make amalgams have been, variously, in the form of micron-sized spheroids or flakes. The tensile reinforcement contributed by the spheroids and flakes is minimal because fracture paths simply go around these particles. However, if spheroids or flakes are replaced by strands having greater lengths, then tensile reinforcement can be increased significantly. The feasibility of this concept was shown in an experiment in which electrical copper wires, serving as demonstration substitutes for copper powder particles, were triturated with gallium by use of a mortar and pestle and the resulting amalgam was compressed into a mold. The tensile strength of the amalgam specimen was then measured and found to be greater than 10(exp 4) psi (greater than about 69 MPa). Much remains to be done to optimize the properties of amalgams for various applications through suitable choice of starting constituents and modification of the trituration and molding processes. The choice of wire size and composition are expected to be especially important. Perusal of phase diagrams of metal mixtures could give insight that would enable choices of solid and liquid metal constituents. Finally, whereas heretofore, only binary alloys have been considered for amalgams

  13. Tensile strength of bilayered ceramics and corresponding glass veneers.

    Science.gov (United States)

    Anunmana, Chuchai; Champirat, Tharee; Jirajariyavej, Bundhit

    2014-06-01

    To investigate the microtensile bond strength between two all-ceramic systems; lithium disilicate glass ceramic and zirconia core ceramics bonded with their corresponding glass veneers. Blocks of core ceramics (IPS e.max® Press and Lava™ Frame) were fabricated and veneered with their corresponding glass veneers. The bilayered blocks were cut into microbars; 8 mm in length and 1 mm(2) in cross-sectional area (n = 30/group). Additionally, monolithic microbars of these two veneers (IPS e.max® Ceram and Lava™ Ceram; n = 30/group) were also prepared. The obtained microbars were tested in tension until fracture, and the fracture surfaces of the microbars were examined with fluorescent black light and scanning electron microscope (SEM) to identify the mode of failure. One-way ANOVA and the Dunnett's T3 test were performed to determine significant differences of the mean microtensile bond strength at a significance level of 0.05. The mean microtensile bond strength of IPS e.max® Press/IPS e.max® Ceram (43.40 ± 5.51 MPa) was significantly greater than that of Lava™ Frame/Lava™ Ceram (31.71 ± 7.03 MPa)(Pveneer layer. Furthermore, the bond strength of Lava™ Frame/Lava™ Ceram was comparable to the tensile strength of monolithic glass veneer of Lava™ Ceram, while the bond strength of bilayered IPS e.max® Press/IPS e.max® Ceram was significantly greater than tensile strength of monolithic IPS e.max® Ceram. Because fracture site occurred mostly in the glass veneer and most failures were away from the interfacial zone, microtensile bond test may not be a suitable test for bonding integrity. Fracture mechanics approach such as fracture toughness of the interface may be more appropriate to represent the bonding quality between two materials.

  14. Influence of de/remineralization of enamel on the tensile bond strength of etch-and-rinse and self-etching adhesives.

    Science.gov (United States)

    Farias de Lacerda, Ana Julia; Ferreira Zanatta, Rayssa; Crispim, Bruna; Borges, Alessandra Bühler; Gomes Torres, Carlos Rocha; Tay, Franklin R; Pucci, Cesar Rogério

    2016-10-01

    To evaluate the bonding behavior of resin composite and different adhesives applied to demineralized or remineralized enamel. Bovine tooth crowns were polished to prepare a 5 mm2 enamel bonding area, and divided into five groups (n= 48) according to the surface treatment: CONT (sound enamel control), DEM (demineralized with acid to create white spot lesions), REMS (DEM remineralized with artificial saliva), REMF (DEM remineralized with sodium fluoride) and INF (DEM infiltrated with Icon resin infiltrant). The surface-treated teeth were divided into two subgroups (n= 24) according to adhesive type: ER (etch-and-rinse; Single Bond Universal) and SE (self-etching; Clearfill S3 Bond), and further subdivided into two categories (n= 12) according to aging process: Thermo (thermocycling) and NA (no aging). Composite blocks were made over bonded enamel and sectioned for microtensile bond strength (MTBS) testing. Data were analyzed with three-way ANOVA and post-hoc Tukey's test (α= 0.05). Significant differences were observed for enamel surface treatment (Padhesive type (Padhesive type and surface treatment condition. The predominant failure mode was mixed for all groups. Enamel surface infiltrated with Icon does not interfere with adhesive resin bonding procedures. Treatment of enamel surface containing white spot lesions or cavities with cavosurface margins in partially-demineralized enamel can benefit from infiltration with a low viscosity resin infiltrant prior to adhesive bonding of resin composites.

  15. Water's Hydrogen Bond Strength

    CERN Document Server

    Chaplin, Martin

    2007-01-01

    Water is necessary both for the evolution of life and its continuance. It possesses particular properties that cannot be found in other materials and that are required for life-giving processes. These properties are brought about by the hydrogen bonded environment particularly evident in liquid water. Each liquid water molecule is involved in about four hydrogen bonds with strengths considerably less than covalent bonds but considerably greater than the natural thermal energy. These hydrogen bonds are roughly tetrahedrally arranged such that when strongly formed the local clustering expands, decreasing the density. Such low density structuring naturally occurs at low and supercooled temperatures and gives rise to many physical and chemical properties that evidence the particular uniqueness of liquid water. If aqueous hydrogen bonds were actually somewhat stronger then water would behave similar to a glass, whereas if they were weaker then water would be a gas and only exist as a liquid at sub-zero temperature...

  16. Effect of discrete fibre reinforcement on soil tensile strength

    Directory of Open Access Journals (Sweden)

    Jian Li

    2014-04-01

    Full Text Available The tensile behaviour of soil plays a significantly important role in various engineering applications. Compacted soils used in geotechnical constructions such as dams and clayey liners in waste containment facilities can suffer from cracking due to tensile failure. In order to increase soil tensile strength, discrete fibre reinforcement technique was proposed. An innovative tensile apparatus was developed to determine the tensile strength characteristics of fibre reinforced soil. The effects of fibre content, dry density and water content on the tensile strength were studied. The results indicate that the developed test apparatus was applicable in determining tensile strength of soils. Fibre inclusion can significantly increase soil tensile strength and soil tensile failure ductility. The tensile strength basically increases with increasing fibre content. As the fibre content increases from 0% to 0.2%, the tensile strength increases by 65.7%. The tensile strength of fibre reinforced soil increases with increasing dry density and decreases with decreasing water content. For instance, the tensile strength at a dry density of 1.7 Mg/m3 is 2.8 times higher than that at 1.4 Mg/m3. It decreases by 30% as the water content increases from 14.5% to 20.5%. Furthermore, it is observed that the tensile strength of fibre reinforced soil is dominated by fibre pull-out resistance, depending on the interfacial mechanical interaction between fibre surface and soil matrix.

  17. Prediction of Tensile Strength of Nano-short-fiber-reinforced Rubber Composites

    Directory of Open Access Journals (Sweden)

    Zhu Da Sheng

    2016-01-01

    Full Text Available The tensile strength of nano-short-fiber-reinforced rubber composites (NFRC was studied. A new model for predicting the tensile strength of NFRC was put forward based on the mixture law. The influences of the volume content and mechanical performances of main components, short fiber critical aspect ratio, short fiber length and orientation distributions on the tensile strength of composites were investigated. The tensile strengths predicted by the model in this paper are in good agreement with experimental data. Furthermore, the mechanism of tensile fracture of SFRE was discussed. It is found that the tensile fracture of the composites depends largely on the bonding strength of fiber-matrix interface and the length of reinforcing short fibers.

  18. Tensile bond strength of resin composite repair in vitro using different surface preparation conditionings to an aged CAD/CAM resin nanoceramic.

    Science.gov (United States)

    Stawarczyk, Bogna; Krawczuk, Andreas; Ilie, Nicoleta

    2015-03-01

    This study was conducted in order to assess the pretreatment method (air abrasion, both wet and dry, and Al2O3 grinder), the conditioning method (comprised of different adhesive systems), the repair resin composite (low and high modulus of elasticity), the contamination of CoJet air-abraded surfaces with water, and the effect phosphoric acid on the macrotensile bond strength (TBS) to aged CAD/CAM resin nanoceramic (RNC). Aged RNC substrates (LAVA Ultimate, 3M ESPE; N = 900; 10,000 cycles, 5 °C/55 °C) were air-abraded (CoJet 3M ESPE) with and without water contamination or treated with an Al2O3 grinder (Cimara, Voco). Immediately after pretreatment, half of the specimens were additionally cleaned with phosphoric acid, while the rest were only rinsed with water. Four intermediate agents (Futurabond U/VOCO, Scotchbond Universal/3M ESPE, One Coat Bond/Coltène Whaledent, visio.link/bredent) were selected for conditioning the surface, while no conditioned specimens acted as control groups. Specimens were thereafter repaired using two direct resin composites (Arabesk Top and GrandioSo, VOCO), stored for 24 h at 37 °C in H2O, and thermally aged for 10,000 cycles (5 °C/55 °C; n = 15/subgroup). TBS and failure types were determined and evaluated with four- and one-way ANOVA and χ (2) test (p visio.link and Scotchbond Universal performed slightly better than Futurabond U. Phosphoric acid or water contamination of the air-abraded surface does not affect the repair bond strength.

  19. Strength of Chemical Bonds

    Science.gov (United States)

    Christian, Jerry D.

    1973-01-01

    Students are not generally made aware of the extraordinary magnitude of the strengths of chemical bonds in terms of the forces required to pull them apart. Molecular bonds are usually considered in terms of the energies required to break them, and we are not astonished at the values encountered. For example, the Cl2 bond energy, 57.00 kcal/mole, amounts to only 9.46 x 10(sup -20) cal/molecule, a very small amount of energy, indeed, and impossible to measure directly. However, the forces involved in realizing the energy when breaking the bond operate over a very small distance, only 2.94 A, and, thus, f(sub ave) approx. equals De/(r - r(sub e)) must be very large. The forces involved in dissociating the molecule are discussed in the following. In consideration of average forces, the molecule shall be assumed arbitrarily to be dissociated when the atoms are far enough separated so that the potential, relative to that of the infinitely separated atoms, is reduced by 99.5% from the potential of the molecule at the equilibrium bond length (r(sub e)) for Cl2 of 1.988 A this occurs at 4.928 A.

  20. Tensile bond strength of adhesive systems: effects of primer and thermocycling Resistência à tração de sistemas adesivos: efeitos do “ primer” e dos ciclos térmicos

    Directory of Open Access Journals (Sweden)

    Luciana Tibiriçá AGUILAR

    2002-03-01

    Full Text Available The objective of this study was to evaluate the effects of primer and thermocycling on the bond strength of multi-purpose adhesive systems applied to enamel, under tensile stress. The following bonding systems were applied, according to the manufacturers' instructions, on unground enamel buccal surfaces of 96 premolars, with or without the application of primer: Scotchbond MP, OptiBond FL, Amalgambond Plus and OptiBond (dual-cure. A composite resin (Z100, 3M was applied and light-cured in a cast metal hollow cone, which was previously fixed to the enamel surfaces. Half of the sample was subjected to 3,000 thermocycles (5-37ºC; 37-55ºC, dwell time of 60 s, and the other half was stored in water at 37ºC for the same period. The data were treated by means of ANOVA and no significant effects were detected, which indicates that tensile bond strength was not affected by the adhesive systems, application of primer or thermocycling.O objetivo desta pesquisa foi o de verificar o efeito do "primer" e dos ciclos térmicos na resistência da união entre adesivos multiuso e esmalte dental, sob ensaios de tração. Os seguintes sistemas adesivos foram aplicados, de acordo com as instruções dos fabricantes, na superfície vestibular (sem desgaste de 96 pré-molares com ou sem a aplicação prévia do "primer": Scotchbond MP, OptiBond FL, Amalgambond Plus e OptiBond - "dual cure". Após a aplicação do sistema adesivo, foi confeccionado um cone de resina composta (Z100, 3M, e fotoativado dentro de um molde metálico. Metade do total de espécimes foi submetida a 3.000 ciclos térmicos (5-37ºC; 37-55ºC, 60 s de imersão; a outra metade permaneceu imersa em água a 37ºC pelo mesmo tempo dispensado no procedimento anterior. Os dados foram submetidos a uma análise de variância (p = 0,05 e nenhum efeito significante foi detectado, indicando que a resistência de união não foi afetada pelo sistema adesivo, pela aplicação do "primer" ou pelos ciclos térmicos.

  1. Testing Tensile and Shear Epoxy Strength at Cryogenic Temperatures

    Science.gov (United States)

    Alberts, S. J.; Doehne, C. J.; Johnson, W. L.

    2017-01-01

    This paper covers cryogenic, tensile testing and research completed on a number of epoxies used in cryogenic applications. Epoxies are used in many different applications; however, this research focused on the use of epoxy used to bond MLI standoffs to cryogenic storage tanks and the loads imparted to the tank through the MLI. To conduct testing, samples were made from bare stainless steel, aluminum and primed aluminum. Testing involved slowly cooling test samples with liquid nitrogen then applying gradually increasing tensile loads to the epoxy. The testing evaluated the strength and durability of epoxies at cryogenic temperatures and serves as a base for future testing. The results of the tests showed that some epoxies withstood the harsh conditions while others failed. The two epoxies yielding the best results were Masterbond EP29LPSP and Scotch Weld 2216. For all metal surfaces tested, both epoxies had zero failures for up to 11.81 kg of mass.

  2. Relation between incremental lines and tensile strength of coronal dentin.

    Science.gov (United States)

    Inoue, Toshiko; Saito, Makoto; Yamamoto, Masato; Nishimura, Fumio; Miyazaki, Takashi

    2012-01-01

    In one aspect, this study examined the tensile strength of coronal dentin, as a function of the location of incremental lines, in two types of teeth: human molar versus bovine incisor. In another aspect, tensile strength in coronal dentin was examined with tensile loading in two different orientations to the incremental lines: parallel versus perpendicular. There were four experimental groups in this study: HPa, human molar dentin with tensile orientation parallel to the incremental lines; HPe, human molar dentin with tensile orientation perpendicular to the incremental lines; BPa, bovine incisor dentin with tensile orientation parallel to the incremental lines; BPe, bovine incisor dentin with tensile orientation perpendicular to the incremental lines. Tensile strengths of the parallel group (HPa and BPa) were significantly higher (pdentin. However, there were no differences in anisotropy effect between the two tooth types.

  3. Dataset of tensile strength development of concrete with manufactured sand

    Directory of Open Access Journals (Sweden)

    Shunbo Zhao

    2017-04-01

    Full Text Available This article presents 755 groups splitting tensile strength tests data of concrete with manufactured sand (MSC in different curing age ranged from 1 day to 388 days related to the research article “Experimental study on tensile strength development of concrete with manufactured sand” (Zhao et al., 2017 [1]. These data were used to evaluate the precision of the prediction formulas of tensile strength of MSC, and can be applied as dataset for further studies.

  4. Hybrid filler composition optimization for tensile strength of jute fibre ...

    Indian Academy of Sciences (India)

    The effect of weight content of bagasse fibre, carbon black and calcium carbonate on tensile strength of pultruded GFRP composite is evaluated and the optimum hybrid filler composition for maximizing the tensile strength is determined. Different compositions of hybrid filler are prepared by mixing three fillers using Taguchi ...

  5. Sterilization effects on tensile strength of non-conventional suture ...

    African Journals Online (AJOL)

    An experiment was carried out to determine the tensile strength of embroidery, braiding, cobbler's thread and nylon mono-filament fishing line (NMFL) use as non-conventional suture material. Their tensile strength were determined pre- sterilization using various calibrated weights (50gm, 100gm, 500gm).

  6. Effect of Temperature on the Tensile Strength and Thermoelectric ...

    African Journals Online (AJOL)

    The tensile strength and thermoelectric e.m.f. values of 6063 aluminum alloy quenched at different temperatures from 2500C to 6000C were investigated. The result empirically confirmed that a perfect correlation exists between the tensile strength and thermoelectric e.m.f. values with concurrent minimum temperature ...

  7. Tensile Strength of Water Exposed to Pressure Pulses

    DEFF Research Database (Denmark)

    Andersen, Anders Peter; Mørch, Knud Aage

    2012-01-01

    at an extended water-solid interface by imposing a tensile stress pulse which easily causes cavitation. Next, a compressive pulse of duration ~1 ms and a peak intensity of a few bar is imposed prior to the tensile stress pulse. A dramatic increase of the tensile strength is observed immediately after...... the compressive pulse, but the effect is shortlived. We presume that diffusion of non-condensable gas from the cavitation nuclei into the liquid at compression, and back again later, is responsible for the changes of tensile strength....

  8. Tensile bond strength of glass fiber posts luted with different cements Resistência à tração de pinos de fibra de vidro cimentados com diferentes materiais

    Directory of Open Access Journals (Sweden)

    Gerson Bonfante

    2007-06-01

    Full Text Available Proper selection of the luting agent is fundamental to avoid failure due to lack of retention in post-retained crowns. The objective of this study was to investigate the tensile bond strength and failure mode of glass fiber posts luted with different cements. Glass fiber posts were luted in 40 mandibular premolars, divided into 4 groups (n = 10: Group 1 - resin-modified glass ionomer RelyX Luting; Group 2 - resin-modified glass ionomer Fuji Plus; Group 3 - resin cement RelyX ARC; Group 4 - resin cement Enforce. Specimens were assessed by tensile strength testing and light microscopy analysis for observation of failure mode. The tensile bond strength values of each group were compared by ANOVA and Tukey test. The significance level was set at 5%. The failure modes were described as percentages. The following tensile strength values were obtained: Group 1 - 247.6 N; Group 2 - 256.7 N; Group 3 - 502.1 N; Group 4 - 477.3 N. There was no statistically significant difference between Groups 1 and 2 or between Groups 3 and 4, yet the resin cements presented significantly higher tensile bond strength values than those presented by the glass ionomer cements. Group 1 displayed 70% of cohesive failures, whereas Groups 2, 3 and 4 exhibited 70% to 80% of adhesive failures at the dentin-cement interface. We concluded that resin cements and glass ionomer cements are able to provide clinically sufficient retention of glass fiber posts, and that glass ionomer cements may be especially indicated when the application of adhesive techniques is difficult.A seleção adequada do agente cimentante é essencial para evitar falhas por perda de retenção em coroas retidas por núcleos. O objetivo deste estudo foi investigar a resistência à tração e o tipo de falha de pinos de fibra de vidro cimentados com diferentes materiais. Cimentaram-se pinos de fibra de vidro em 40 pré-molares inferiores, divididos em 4 grupos (n = 10: Grupo 1 - ionômero de vidro modificado

  9. Infliximab treatment reduces tensile strength in intestinal anastomosis

    DEFF Research Database (Denmark)

    Jensen, Jonas Sanberg; Petersen, Nacie Bello; Biagini, Matteo

    2015-01-01

    :1) to receive either repeated IFX treatment or placebo. On day 15, three separate end-to-end anastomoses were performed on the jejunum. On postoperative day 5, tensile strength and bursting pressure for the anastomoses were tested and histologic changes examined. RESULTS: We found a significantly reduced...... tensile strength in the IFX group (1.94 +/- 0.44 N) compared with the placebo group (3.33 +/- 0.39 N), (P tensile strength and serum values of IFX (coefficient = -0.63; P = 0.003) as well...... as number of sutures in the tested anastomosis (coefficient = 0.51; P = 0.024). The general histologic score was significantly higher in the placebo group (5.00 +/- 1.26 versus 3.31 +/- 1.65, P = 0.03). CONCLUSIONS: Repeated high-dose IFX treatment reduces tensile strength significantly in rabbits...

  10. Tensile strength of glulam laminations of Nordic spruce

    DEFF Research Database (Denmark)

    Hoffmeyer, Preben; Bräuner, Lise; Boström, Lars

    1999-01-01

    Design of glulam according to the European timber code Eurocode 5 is based on the standard document prEN1194 , according to which glulam beam strength is to be established either by full scale testing or by calculation. The calculation must be based on a knowledge of lamination tensile strength....... This knowledge may be obtained either by adopting a general rule that the characteristic tensile strength is sixty percent of the characteristic bending strength, or by performing tensile tests on an adequate number of laminations representative of the whole population. The present paper presents...... an investigation aimed at establishing such an adequate experimental background for the assignment of strength classes for glulam made of visually strength graded laminations from Nordic sawmills. The investigation includes more than 1800 boards (laminations) of Norway spruce (Picea abies) sampled from eight...

  11. Various conditioning methods for root canals influencing the tensile strength of titanium posts

    NARCIS (Netherlands)

    Schmage, P.; Sohn, J.; Nergiz, I.; Ozcan, M.; Nergiz, [No Value

    2004-01-01

    Conditioning the root canal is frequently advised to achieve high post-retention when resin composite luting cements are used. However, Manufacturers’ instructions for this purpose differ widely from one another. The aim of this study was to compare the tensile bond strengths of passive, tapered,

  12. Compressive and Tensile Strength of Expanded Polystyrene Beads Concrete

    OpenAIRE

    Subhan, Tengku Fitriani L

    2005-01-01

    Penelitian ini betujuan untuk mempelajari property dari beton ringan yang mengandung expanded polystyrene beads, yaitu kuat tekan (compressive strength) dan kuat tarik (tensile strength). Property tersebut kemudian dibandingkan dengan beton normal (beton tanpa expanded polystyrene beads) sebagai campuran pengontrol. Hasil penelitian ini menunjukkan bahwa jumlah polystyrene beads yang dimasukkan sebagai campuran beton mempengaruhi property beton; yaitu dapat menurunkan kuat tekan beton. Tetapi...

  13. Effect of water storage on ultimate tensile strength and mass changes of universal adhesives.

    Science.gov (United States)

    Bahrololumi, Nazanin; Beglou, Amirreza; Najafi-Abrandabadi, Ahmad; Sadr, Alireza; Sheikh-Al-Eslamian, Seyedeh-Mahsa; Ghasemi, Amir

    2017-01-01

    The aim of the present study was to evaluate the influence of water storage on micro tensile strength (µTS) and mass changes (MC) of two universal adhesives. 10 disk-shaped specimens were prepared for each adhesive; Scotchbond Universal (SCU) All-Bond Universal (ABU) and Adper Single Bond 2 (SB2). At the baseline and after 1 day and 28 days of water storage, their mass were measured and compared to estimate water sorption and solubility. For µTS test, 20 dumbbell shaped specimens were also prepared for each adhesive in two subgroups of 1 day and 28 days water storage. MC was significantly lower for SCU and ABU than SB2 (P water; both universal adhesives showed less water sorption and higher values of µTS than the control group. Key words:Absorption, dental adhesives, dentin-bonding agents, solubility, tensile strength.

  14. Covalent Crosslinking of Carbon Nanotube Materials for Improved Tensile Strength

    Science.gov (United States)

    Baker, James S.; Miller, Sandi G.; Williams, Tiffany A.; Meador, Michael A.

    2013-01-01

    Carbon nanotubes have attracted much interest in recent years due to their exceptional mechanical properties. Currently, the tensile properties of bulk carbon nanotube-based materials (yarns, sheets, etc.) fall far short of those of the individual nanotube elements. The premature failure in these materials under tensile load has been attributed to inter-tube sliding, which requires far less force than that needed to fracture individual nanotubes.1,2 In order for nanotube materials to achieve their full potential, methods are needed to restrict this tube-tube shear and increase inter-tube forces.Our group is examining covalent crosslinking between the nanotubes as a means to increase the tensile properties of carbon nanotube materials. We are working with multi-walled carbon nanotube (MWCNT) sheet and yarn materials obtained from commercial sources. Several routes to functionalize the nanotubes have been examined including nitrene, aryl diazonium, and epoxide chemistries. The functional nanotubes were crosslinked through small molecule or polymeric bridges. Additionally, electron beam irradiation induced crosslinking of the non-functional and functional nanotube materials was conducted. For example, a nanotube sheet material containing approximately 3.5 mol amine functional groups exhibited a tensile strength of 75 MPa and a tensile modulus of 1.16 GPa, compared to 49 MPa and 0.57 GPa, respectively, for the as-received material. Electron beam irradiation (2.2x 1017 ecm2) of the same amine-functional sheet material further increased the tensile strength to 120 MPa and the modulus to 2.61 GPa. This represents approximately a 150 increase in tensile strength and a 360 increase in tensile modulus over the as-received material with only a 25 increase in material mass. Once we have optimized the nanotube crosslinking methods, the performance of these materials in polymer matrix composites will be evaluated.

  15. Tensile strength of biological fibrin sealants: a comparative study.

    Science.gov (United States)

    Lacaze, Laurence; Le Dem, Nicolas; Bubenheim, Michael; Tsilividis, Basile; Mezghani, Julien; Schwartz, Lilian; Francois, Arnaud; Ertaud, Jean Yves; Bagot d'Arc, Maurice; Scotté, Michel

    2012-08-01

    Fibrin sealants are commonly used in liver surgery, although their effectiveness in routine clinical practice remains controversial. Individual sealant characteristics are based on hemostatic effects and adhesion properties that can be experimentally measured using the 'rat skin test' or the 'pig skin test'. This study used a more relevant and realistic experimental canine model to compare the differences in the adhesive properties of four fibrin sealants in hepatectomy: Tisseel/Tissucol, Tachosil, Quixil, and Beriplast. A partial hepatectomy was performed in beagle dogs under general anesthesia to obtain liver cross-sections. Fibrin sealants were allocated to dog livers using a Youden square design. The tensile strength measurement was performed using a traction system to measure the rupture stress point of a small wooden cylinder bonded to the liver cross-section. Significantly greater adhesion properties were observed with Tisseel/Tissucol compared with Quixil or Beriplast (P = 0.002 and 0.001, respectively). Similarly, Tachosil demonstrated significantly greater adhesive properties compared with Beriplast (P = 0.009) or Quixil (P = 0.014). No significant differences were observed between Tisseel/Tissucol and Tachosil or between Beriplast and Quixil. The results of this comparative study demonstrate that different fibrin sealants exhibit different adhesive properties. Tisseel/Tissucol and Tachosil provided greatest adhesion to liver cross-section in our canine model of hepatectomy. These results may enable the optimal choice of fibrin sealants for this procedure in clinical practice. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Bond strength variation of synthetic resin teeth in dentures.

    Science.gov (United States)

    Cunningham, J L; Benington, I C

    1995-01-01

    The bond strength of denture teeth to acrylic resin denture bases was determined by producing tensile test specimens from standardised and anonymously presented partial dentures. Ten dentures were produced by randomly selected commercial dental laboratories and five were produced in a university dental laboratory. The tooth debonding forces exhibited a wide range of variation both within and between dentures. The university-produced dentures showed, on average, a slightly improved tooth bond strength. This study highlights the need for further investigation of this problem and for the development of a standardised technique to provide satisfactory denture tooth bonding.

  17. Optimisation of hardness and tensile strength of friction stir welded ...

    African Journals Online (AJOL)

    DR OKE

    The present work aims to optimize the operating parameters such as rotational speed, welding speed and tool diameter for maximum Hardness and Tensile strength of the friction stir welded joint on AA6061 alloy. Three factors with five level response surface design matrix were developed by using MINITAB14 software ...

  18. Evaluation of tensile strength and fracture behavior of friction welded ...

    Indian Academy of Sciences (India)

    Friction welding; tensile strength; SEM; microhardness. 1. Introduction. Joining of the metals is one of the most essential needs of the industry (Handa & Chawla 2013a). The joining has increasingly been used in the materials technology because of the materials hav- ing different mechanical properties needs to be efficiently ...

  19. Evaluation of tensile strength and fracture behavior of friction welded ...

    Indian Academy of Sciences (India)

    In the present study an attempt was made to join austenitic stainless steel (AISI 304) with low alloy steel (AISI 1021) at five different rotational speeds ranging from 800 to 1600 rpm and at as many different axial pressures ranging from 75 MPa to 135 MPa and then determining the strength of the joint by means of tensile ...

  20. Analog Experiments on Tensile Strength of Dusty and Cometary Matter

    Science.gov (United States)

    Musiolik, Grzegorz; de Beule, Caroline; Wurm, Gerhard

    2017-11-01

    The tensile strength of small dusty bodies in the solar system is determined by the interaction between the composing grains. In the transition regime between small and sticky dust (μm) and non cohesive large grains (mm), particles still stick to each other but are easily separated. In laboratory experiments we find that thermal creep gas flow at low ambient pressure generates an overpressure sufficient to overcome the tensile strength. For the first time it allows a direct measurement of the tensile strength of individual, very small (sub)-mm aggregates which consist of only tens of grains in the (sub)-mm size range. We traced the disintegration of aggregates by optical imaging in ground based as well as microgravity experiments and present first results for basalt, palagonite and vitreous carbon samples with up to a few hundred Pa. These measurements show that low tensile strength can be the result of building loose aggregates with compact (sub)-mm units. This is in favour of a combined cometary formation scenario by aggregation to compact aggreates and gravitational instability of these units.

  1. Regional Variation in the Microscopy and Tensile Strength of the ...

    African Journals Online (AJOL)

    The linea alba (LA), a midline tendinous structure formed by the interlocking anterior abdominal wall aponeurotic fibers, acts as a passive tensile band that prevents sagging of the lower abdomen. The microstructure and the strength of these fibres would thus be expected to reflect on the forces that act on the linea alba.

  2. Optimisation of hardness and tensile strength of friction stir welded ...

    African Journals Online (AJOL)

    Optimisation of hardness and tensile strength of friction stir welded AA6061 alloy using response surface methodology coupled with grey relational analysis and principle component ... Response Surface Methodology (RSM) was adopted to develop mathematical model between the response and process parameters.

  3. Axial dynamic tensile strength of concrete under static lateral compression

    NARCIS (Netherlands)

    Weerheijm, J.

    2006-01-01

    The rate effect on concrete tensile strength can be modeled by the description of crack extension in a fictitious fracture plane [1,2].The plane represents the initial, internal damage and the geometry of the final fracture plane. In the paper, the same approach is applied to model the failure

  4. Tensile Strength of Finger Joints at Elevated Temperatures

    DEFF Research Database (Denmark)

    Nielsen, Peter C.; Olesen, Frits Bolonius

    A series of test s aimed a t establishing the effect of temperature upon the tensile strength parallel-to-grain of finger jointed laminae for glulam has been conducted in the Fire Research Laboratory at Aalborg University Centre. The objective of this report is to present the background...

  5. Split tensile strength of soilcrete blocks | Okere | Nigerian Journal of ...

    African Journals Online (AJOL)

    With the ever increasing problems associated with dredging of rivers to obtain river sand, reduced dependence on river sand should be encouraged by using alternative materials in block production. This work deals with the production of soilcrete blocks using readily available and affordable laterite. Split tensile strength of ...

  6. Possibilities of Adhesives Filling With Micro-particle Fillers – Lap-shear Tensile Strength

    Directory of Open Access Journals (Sweden)

    Petr Valášek

    2016-01-01

    Full Text Available An adhesive bonding can be ranged among technologies of materials bonding which are used in all industrial branches. It plays its important role also in an area of the construction of agricultural machines, e.g. tractors, harvestors etc. Utility properties of adhesives can be extended by using various types of fillers. These fillers increase some mechanical characteristics of adhesives and not last they can decrease resultant price. The paper focuses on a possibility to fill the adhesives showing increased lap-shear tensile strength. These adhesives are used e.g. for adhesive bonding of coach bodies in an automotive industry so that is why it is possible to apply them also in the agricultural area. Laboratory experiments describe the lap-shear tensile strength of rigid adherents which were bonded with adhesives with a variable concentration of micro-particle filler – a glass powder. T-test used for a comparison of the shear strength of the bonds created with the adhesives with 5 vol.% of the glass powder did not evidence a statistically significant difference comparing with the unfilled adhesives. This priece of knowledge opens a possible way of a material usage of the glass powder in the area of the adhesive bonding.

  7. EXPERIMENTAL INVESTIGATION ON TENSILE STRENGTH OF JACQUARD KNITTED FABRICS

    Directory of Open Access Journals (Sweden)

    BRAD Raluca

    2015-05-01

    Full Text Available An objective approach to select the best fabric for technical and home textiles consists in mechanical properties evaluation. The goal of this study is to analyze the behavior of knitted fabrics undergoing stretch stress. In this respect, three types of 2 colors Rib structure (backstripes jacquard, twillback jacquard and double-layered 3x3 rib fabric have been presented and tested for tensile strength and elongation on three directions. First, the elasticity and the behavior of knitted Rib fabrics were described The fabrics were knitted using 100% PAN yarns with Nm 1/15x2 on a E5 CMS 330 Stoll V-bed knitting machine, and have been tested using INSTROM 5587 Tensile Testing Machine in respect of standards conditions. After a relaxation period, 15 specimens were prepared, being disposed at 0°, 45 and 90 angles to the wale direction on the flat knitted panel. The tensile strength and the elongation values were recorded and mean values were computed. After strength and tensile elongation testing for 3 types of rib based knitted fabrics, one can see that the double layer knit presents the best mechanical behavior, followed by birds-eyebacking 2 colors Jacquard and then back striped Jacquard. For tensile stress in bias direction, the twillbacking Jacquard has a good breakage resistance value due to the higher number of rib sinker loops in structure that are positioned on the same direction with the tensile force. The twillbacking Jacquard structure could be considered as an alternative for the base material for decorative and home textile products.

  8. Effect of moist bonding on composite/enamel bond strength.

    Science.gov (United States)

    Moll, Karlheinz; Gärtner, Thomas; Haller, Bernd

    2002-04-01

    To evaluate the effect of moist bonding on shear bond strength of resin-based composite to enamel using different adhesive systems. Six restorative systems were selected for this study: OptiBond FL/Prodigy, Solid Bond/Charisma F, Syntac Single Component/Tetric, Prime&Bond 2.1/Spectrum TPH, Single Bond/Z100, Etch&Prime 3.0/Degufill Mineral. Flat enamel surfaces were ground on the buccal and lingual aspects of 80 extracted human molars. OptiBond FL and Solid Bond were tested with and without primer application. Prior to application of the adhesives, the enamel was either carefully dried with compressed air (dry bonding) or blot dried with a cotton pellet (moist bonding). Shear bond strength was determined with a universal testing machine after 24-hour storage in 0.9% NaCl at 37 degrees C. Moist bonding did not significantly affect shear bond strength to enamel of the adhesives tested except for Solid Bond without primer application. Primer contamination of the etched enamel did not significantly influence bond strength, neither in the dry bonding nor in the moist bonding group. Of all adhesives tested in both groups, the highest mean bond strength was observed with Prime&Bond 2.1 and the lowest with Etch&Prime 3.0.

  9. Microstructure-based simulations of the tensile strength of snow

    Science.gov (United States)

    Hagenmuller, P.; Theile, T.; Schneebeli, M.

    2012-04-01

    The mechanical behavior of snow is essential to understand the formation of snow avalanches. In particular, the failure properties of snow are determinant in snow slab avalanche release. Direct experiments on snow are difficult to conduct and to interpret. First, seasonal snow is often a very fragile material which can be easily damaged before a mechanical test is finished. Second, natural snow is generally not homogenous, but consists of many thin layers. Thus, a direct mechanical test is in this case very difficult to interpret. This motivated us to implement a numerical simulation that uses the full 3D-structure of snow. The microstructure of snow samples was captured with a micro-computer tomograph and the tensile strength of the same samples was measured. A subvolume (about 30 mm3) of the zone where the fracture occurred in the mechanical test was numerically simulated. To this purpose, the mechanical properties of monocrystalline ice were considered to model the constitutive material of snow. Because the orientation of ice grains cannot be determined in adsorption tomography, orientation-averaged properties were used as a first approximation. The results show that the average simulated tensile strength is in good agreement with the measurements for the tested snow, rounded grains at a density of about 350 kg m-3. In a second approach, a geometrical grain selection algorithm was used to associate to each ice grain a specific c-axis and the corresponding oriented anisotropic stiffness and strength. This artificial orientation of ice grains does not modify significantly the elastic stress distribution in the snow sample but decreases slightly the effective tensile strength of snow compared to the simulation using orientation-averaged properties of ice. As a conclusion, even if the size of the simulated volume remains relatively small (about 30 mm3), the direct numerical simulation of the tensile strength of snow is possible and enables the investigation of the

  10. Tensile Strength of GFRP Reinforcing Bars with Hollow Section

    Directory of Open Access Journals (Sweden)

    Young-Jun You

    2015-01-01

    Full Text Available Fiber reinforced polymer (FRP has been proposed to replace steel as a reinforcing bar (rebar due to its high tensile strength and noncorrosive material properties. One obstacle in using FRP rebars is high price. Generally FRP is more expensive than conventional steel rebar. There are mainly two ways to reduce the cost. For example, one is making the price of each composition cost of FRP rebar (e.g., fibers, resin, etc. lower than steel rebar. Another is making an optimized design for cross section and reducing the material cost. The former approach is not easy because the steel price is very low in comparison with component materials of FRP. For the latter approach, the cost could be cut down by reducing the material cost. Therefore, an idea of making hollow section over the cross section of FRP rebar was proposed in this study by optimizing the cross section design with acceptable tensile performance in comparison with steel rebar. In this study, glass reinforced polymer (GFRP rebars with hollow section and 19 mm of outer diameter were manufactured and tested to evaluate the tensile performance in accordance with the hollowness ratio. From the test results, it was observed that the tensile strength decreased almost linearly with increase of hollowness ratio and the elastic modulus decreased nonlinearly.

  11. Bond strength comparison of color change adhesives for orthodontic bonding.

    Science.gov (United States)

    Duers, Michael W; English, Jeryl D; Ontiveros, Joe C; Powers, John M; Bussa, Harry I; Frey, Gary N; Gallerano, Ronald L; Paige, Sebastian Z

    2011-03-01

    This study investigated whether three different color change light-cured orthodontic bonding adhesives have comparable shear bond strengths to a conventional light-cured orthodontic bonding adhesive. The sample of 240 bovine incisors was divided into four groups of 60 each. Each group tested one of four orthodontic bonding adhesives: 3M Unitek Transbond PLUS, Ormco Gréngloo, Ormco Blúgloo, and 3M Unitek Transbond XT (control). The four groups were further divided into two subgroups of 30 with shear bond strength tested at two different times (15 minutes and 24 hours) post-bond. The shear bond strength was measured on a universal testing machine. The data were analyzed by two-way analysis of variance and post-hoc comparisons (Fisher's PLSD) at the 0.05 level of significance. The average shear bond strength was greater at 24 hours than at 15 minutes for Transbond PLUS, Blúgloo, and Transbond XT. For Gréngloo, the average shear bond strength was greater at 15 minutes than at 24 hours. Gréngloo tested at 15 minutes had the highest average shear bond strength. Gréngloo tested at 24 hours had the lowest average shear bond strength. All four orthodontic bonding adhesives demonstrated bond strengths considered to be clinically acceptable for orthodontic purposes.

  12. Tensile rock mass strength estimated using InSAR

    KAUST Repository

    Jonsson, Sigurjon

    2012-11-01

    The large-scale strength of rock is known to be lower than the strength determined from small-scale samples in the laboratory. However, it is not well known how strength scales with sample size. I estimate kilometer-scale tensional rock mass strength by measuring offsets across new tensional fractures (joints), formed above a shallow magmatic dike intrusion in western Arabia in 2009. I use satellite radar observations to derive 3D ground displacements and by quantifying the extension accommodated by the joints and the maximum extension that did not result in a fracture, I put bounds on the joint initiation threshold of the surface rocks. The results indicate that the kilometer-scale tensile strength of the granitic rock mass is 1–3 MPa, almost an order of magnitude lower than typical laboratory values.

  13. On the tensile strength distribution of multiwalled carbon nanotubes

    Science.gov (United States)

    Barber, Asa H.; Andrews, Rodney; Schadler, Linda S.; Wagner, H. Daniel

    2005-11-01

    Individual multiwalled carbon nanotubes grown by chemical vapor deposition (CVD) were tensile tested within the chamber of an electron microscope using an atomic force microscope-based technique. Weibull-Poisson statistics could accurately model the nanotube tensile strength data. Weibull shape and scale parameters of 1.7 and 109GPa were obtained. The former reflects a wide variability in strength similar to that observed for high-modulus graphite fibers, while the latter indicates that the irregular CVD-grown tube wall structure requires, in some cases, higher breaking forces than more regular tube wall structures. This apparent strengthening mechanism is most likely caused by an enhanced interaction between the walls of the nanotube.

  14. Evidence for low tensile strength in comet nuclei

    Science.gov (United States)

    Kokotanekova, R.; Snodgrass, C.; Lacerda, P.; Lowry, S. C.; Fernández, Y. R.; Green, S. F.; Tubiana, C.; Fitzsimmons, A.; Hsieh, H. H.

    2017-09-01

    We provide an updated study of the collective properties of Jupiter Family comets (JFCs) by increasing the sample of comets with well-studied rotation periods and surface characteristics. To collect the sample, we review the properties of 35 JFCs with published rotation rates and add new lightcurves and phase functions for nine JFCs observed between 2004 and 2015. We use the extended sample of 37 comets to characterise the bulk density, tensile strength, collisional history and surface properties of JFCs. Using the model for stability of rotating solid biaxial ellipsoids by Davidsson (2001), we conclude that none of the observed JFCs require tensile strength larger than 10-25 Pa to remain stable against rotational breakup.

  15. Tensile Strength of Epoxy Composites Reinforced with Fique Fibers

    Science.gov (United States)

    Altoé, Giulio Rodrigues; Netto, Pedro Amoy; Teles, Maria Carolina Andrade; Borges, Luiz Gustavo Xavier; Margem, Frederico Muylaert; Monteiro, Sergio Neves

    Environmentally friendly composites, made from natural fibers, are among the most investigated and applied today. Natural fibers have showed advantages, such as, flexibility and toughness, if compared with synthetic fibers. This work investigates the tensile strength of epoxy composites reinforced with Fique fibers. The Fique fiber was extracted from Fique leaf presents some significant characteristic, but until now only few studies on Fique fiber were performed. Composites reinforced with up to 30% in volume of long, continuous and aligned Fique fibers were tested in an Instron machine at room temperature. The incorporation of Fique fibers increases the tensile strength of the composite. After fracture the specimens were analyzed by a SEM (scanning electron microscope).

  16. Effect of water storage on ultimate tensile strength and mass changes of universal adhesives

    OpenAIRE

    Bahrololumi, Nazanin; Beglou, Amirreza; Najafi-Abrandabadi, Ahmad; Sadr, Alireza; Sheikh-Al-Eslamian, Seyedeh-Mahsa; Ghasemi, Amir

    2017-01-01

    Background The aim of the present study was to evaluate the influence of water storage on micro tensile strength (?TS) and mass changes (MC) of two universal adhesives. Material and Methods 10 disk-shaped specimens were prepared for each adhesive; Scotchbond Universal (SCU) All-Bond Universal (ABU) and Adper Single Bond 2 (SB2). At the baseline and after 1 day and 28 days of water storage, their mass were measured and compared to estimate water sorption and solubility. For ?TS test, 20 dumbbe...

  17. THE EFFECT OF PHASE CHANGE MATERIALS ON THE TENSILE STRENGTH

    Directory of Open Access Journals (Sweden)

    HERROELEN Thomas

    2016-05-01

    Full Text Available PCM’s need some important properties to have use such as high heat storage capacity, easy availability and low cost and can have different effects such as flavour, softness or exchange of heat. They are put inside of microcapsules, so they can be inbedded inside the strain, otherwise it wouldn’t be so effective. So basically the microcapsules consist of a core that’s the PCM and a polymer shell. This shell needs to be strong enough to hold the PCM and also withstand up to a certain level of heat and mechanical damage. This study investigates the tensile strength of fabrics composed by fibres, some of these fibres have benn inbedded phase change microcapsules (PCM’s. The investigated fabrics are divided by composition and by structure. By knitting the fabrics in different structures you could be able to investigate which knitting way could be the most effective to have a high tensile strength. Tensile strength tests are performed on specimens with different structures but also with different compositions which could indicate that some strains are tougher then others and more specifically if the PCM’s have a different effect on them.

  18. Bond strength and clinical efficiency for two light guide sizes in orthodontic bracket bonding.

    Science.gov (United States)

    Frost, T; Norevall, L I; Persson, M

    1997-02-01

    The purpose of this study was to establish a possible increase in efficiency in bracket bonding with light-cured adhesive by using a larger size on the light transmitting unit. Two light guides were compared, a standard-sized 11-mm light guide and a 19-mm elliptical extra broad light guide, the latter designed to allow simultaneously curing of two adjacent brackets. Fifty extracted human premolars mounted in five phantom maxillary arches were bonded according to a standard procedure with Mini Uni-Twin stainless steel brackets. The two light guides were randomly chosen for each half of the maxillary arch. After bonding, all teeth were tested for tensile bond strength to failure. In the clinical study 30 patients were bonded according to a split mouth technique with the two light guides alternatively used randomly for each side of the jaw. Time for bonding and the occurrence of bracket failures were recorded. The results showed no statistically significant differences between the standard and elliptical light guides regarding tensile bond strength, or bracket failure frequency. However, with the larger light guide size a significantly shorter total bonding time for each patient was required. It is therefore concluded that the elliptical light guide in combination with a light transmitting unit of sufficient quality gave a similar bonding result as the standard light guide, offering the clinician a reduction in chair side time during the bonding procedure.

  19. SHORT- AND LONG-TERM BOND STRENGTHS OF A GOLD STANDARD

    Directory of Open Access Journals (Sweden)

    Safa TUNCER

    2015-04-01

    Full Text Available Purpose: The aim of this study was to investigate the micro tensile bond strength of a self-etch adhesive system following 1 year storage in water. Materials and Methods: 10 sound human molar teeth were used for micro tensile bond strength test. Twostep self-etch dentin adhesive (Clearfil SE Bond® was applied to the flat dentin surfaces according to the manufacturer’s instructions. Composite blocks (Z- 250; 3M ESPE of 5 mm in height have been prepared by using layering technique. Teeth were stored in water for 24 hours at 37°C and longitudinally sectioned to obtain dentin sticks of 1 mm2.Randomly selected samples from half of the teeth were immediately subjected to micro tensile test and. Remaining specimens were tested after 1 year storage in water. Bond strengths were calculated in megapascal (MPa. Results: Means and standard deviations of the Clearfil SE Bond® micro tensile bond strength values were, respectively, 37.31 ± 13.77 MPa and 24.78 ± 2.99 MPa after 24 h and 1 year of storage in water. The difference was statistically significant (p=0.031. Conclusion: Long-term storage in water decreased the micro tensile bond strength values of the twostep self-etch adhesive which has been accepted as the gold standard in bond strength tests.

  20. Tensile strength of bilayered ceramics and corresponding glass veneers

    OpenAIRE

    Anunmana, Chuchai; Champirat, Tharee; Jirajariyavej, Bundhit

    2014-01-01

    PURPOSE To investigate the microtensile bond strength between two all-ceramic systems; lithium disilicate glass ceramic and zirconia core ceramics bonded with their corresponding glass veneers. MATERIALS AND METHODS Blocks of core ceramics (IPS e.max® Press and Lava™ Frame) were fabricated and veneered with their corresponding glass veneers. The bilayered blocks were cut into microbars; 8 mm in length and 1 mm2 in cross-sectional area (n = 30/group). Additionally, monolithic microbars of thes...

  1. Microtensile Bond Strength of Single Bond and Adper Prompt-L-Pop Adhesives to Dentin

    Directory of Open Access Journals (Sweden)

    P. Alizadeh Oskoee

    2008-03-01

    Full Text Available Objective: The aim of this study was to evaluate the microtensile bond strength to sound and caries-affected dentin using Single Bond and Adper Prompt-L-Pop adhesives.Materials and Methods: Sixteen extracted human molars with carious lesions extended halfway through dentin were ground to expose the caries affected and the surrounding normal dentin. The samples were divided into two groups of eight samples each, including Single Bond (two-step etch and rinse and Adper Prompt-L-Pop (one step self-etch. Z-100 (3M was used for composite build-ups. The teeth were then sectioned and prepared for micro tensile bond strength test, at cross head speed of 1.5 mm/min. Data were ana-lyzed by 1- and 2-way ANOVA.Results: Bond strengths of Single Bond and Adper Prompt-L-Pop adhesives to sound den-tin were significantly higher than to the caries-affected one (P<0.001, besides, bond strength of Single Bond to dentin was generally found to be higher than Adper Prompt-L-Pop adhesive (P<0.001.The interaction effect was not significant (P=0.116Conclusion: Bond strength to caries-affected dentin was compromised when one and two step adhesives were used.

  2. Strain rate effects on tensile strength of iron green bodies

    Directory of Open Access Journals (Sweden)

    Nishida Masahiro

    2015-01-01

    Full Text Available Impact tensile strength of iron green bodies with densities of 7.2 and 7.4 g/cm3 was examined by Brazilian test using the split-Hopkinson pressure bar (Kolsky bar method. The powder material used for the experiments was a press-ready premix containing Distaloy AE, graphite, and lubricant. During dynamic compression, the failure behavior of specimens was observed using a high-speed video camera. The failure stress and failure behavior of dynamic compressive tests were compared with those of static compressive tests.

  3. Effects of conventional welding and laser welding on the tensile strength, ultimate tensile strength and surface characteristics of two cobalt-chromium alloys: a comparative study.

    Science.gov (United States)

    Madhan Kumar, Seenivasan; Sethumadhava, Jayesh Raghavendra; Anand Kumar, Vaidyanathan; Manita, Grover

    2012-06-01

    The purpose of this study was to evaluate the efficacy of laser welding and conventional welding on the tensile strength and ultimate tensile strength of the cobalt-chromium alloy. Samples were prepared with two commercially available cobalt-chromium alloys (Wironium plus and Diadur alloy). The samples were sectioned and the broken fragments were joined using Conventional and Laser welding techniques. The welded joints were subjected to tensile and ultimate tensile strength testing; and scanning electron microscope to evaluate the surface characteristics at the welded site. Both on laser welding as well as on conventional welding technique, Diadur alloy samples showed lesser values when tested for tensile and ultimate tensile strength when compared to Wironium alloy samples. Under the scanning electron microscope, the laser welded joints show uniform welding and continuous molt pool all over the surface with less porosity than the conventionally welded joints. Laser welding is an advantageous method of connecting or repairing cast metal prosthetic frameworks.

  4. [Bond strengths of customized titanium brackets manufactured by selective laser melting].

    Science.gov (United States)

    Zou, Dao-xing; Wang, Ze-min; Guo, Hong-ming; Li, Song; Bai, Yu-xing

    2013-07-01

    To investigate the bond strengths of customized titanium bracket manufactured by selective laser melting. Eighty human premolars which had been extracted for orthodontic purpose were collected and divided randomly (by random table) into two groups (customized bracket group and 3M bracket group, 40 molars in each group). The 35% phosphoric acid was used for etching and the brackets were bonded with 3M Unitek bonding adhesive. All bonded specimens were placed in saline for 24 hours at room temperature and were tested on DWD3050 electronic testing machine to determine the shear bond strength and tensile bond strength. After debonding, the adhesive remnant indexes (ARI) were recorded. The shear bond strengths of customized brackets was 6.80 (6.20, 8.32) MPa, which was significantly lower than that of the 3M brackets [10.46 (9.72, 11.48) MPa] (Z = -3.463, P < 0.05). And the tensile bond strengths of customized brackets was (6.93 ± 1.21) MPa, which was significantly higher than that of the 3M brackets [(5.88 ± 1.23) MPa] (t = 2.81, P < 0.05). No significant difference was found in the ARI between two different kinds of the brackets. The shear bond strength and tensile bond strength of both kinds of brackets were enough for clinic application.

  5. Brazilian Tensile Strength of Anisotropic Rocks: Review and New Insights

    Directory of Open Access Journals (Sweden)

    Tianshou Ma

    2018-01-01

    Full Text Available Strength anisotropy is one of the most distinct features of anisotropic rocks, and it also normally reveals strong anisotropy in Brazilian test Strength (“BtS”. Theoretical research on the “BtS” of anisotropic rocks is seldom performed, and in particular some significant factors, such as the anisotropic tensile strength of anisotropic rocks, the initial Brazilian disc fracture points, and the stress distribution on the Brazilian disc, are often ignored. The aim of the present paper is to review the state of the art in the experimental studies on the “BtS” of anisotropic rocks since the pioneering work was introduced in 1964, and to propose a novel theoretical method to underpin the failure mechanisms and predict the “BtS” of anisotropic rocks under Brazilian test conditions. The experimental data of Longmaxi Shale-I and Jixi Coal were utilized to verify the proposed method. The results show the predicted “BtS” results show strong agreement with experimental data, the maximum error is only ~6.55% for Longmaxi Shale-I and ~7.50% for Jixi Coal, and the simulated failure patterns of the Longmaxi Shale-I are also consistent with the test results. For the Longmaxi Shale-I, the Brazilian disc experiences tensile failure of the intact rock when 0° ≤ βw ≤ 24°, shear failure along the weakness planes when 24° ≤ βw ≤ 76°, and tensile failure along the weakness planes when 76° ≤ βw ≤ 90°. For the Jixi Coal, the Brazilian disc experiences tensile failure when 0° ≤ βw ≤ 23° or 76° ≤ βw ≤ 90°, shear failure along the butt cleats when 23° ≤ βw ≤ 32°, and shear failure along the face cleats when 32° ≤ βw ≤ 76°. The proposed method can not only be used to predict the “BtS” and underpin the failure mechanisms of anisotropic rocks containing a single group of weakness planes, but can also be generalized for fractured rocks containing multi-groups of weakness planes.

  6. Tensile strength of various nylon PA6 specimen modes

    Science.gov (United States)

    Raz, Karel; Zahalka, Martin

    2017-05-01

    This article explores the influence of production technique on the strength of nylon parts. Identical specimens were manufactured by various techniques. The material of specimens was nylon PA6. 3D printing and injection molding were used, with various orientations of printed layers, and various orientations of specimens in the working space of the 3D printer. The variants are described in detail. A special mold was used for the injection molding process in order to make specimens with and without a weld line. The effect of this weld line was evaluated. All specimens were tested using the standard tensile test configuration. The strength was compared. It was found that the same plastic material has very different mechanical properties depending on the production process.

  7. Evaluation of the tensile bond strength of an adhesive system self-etching in dentin irradiated with Er:YAG laser; Avaliacao da resistencia a tracao de um sistema adesivo self-etching em dentina irradiada com Er:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Mello, Andrea Malluf Dabul de

    2000-07-01

    Since Buonocore (1955), several researchers have been seeking for the best adhesive system and treatment for the enamel and dentin surfaces. The use of the acid has been presented as one of the best techniques of dentin conditioning , because this promotes the removal of the 'smear layer and exhibition of dentinal structure, for a best penetration and micro- retention of the adhesive system. However, some conditioning methods have been appearing in the literature, for the substitution or interaction with the acid substances, as the laser. The objective of this work is to evaluate the tensile bond strength of the adhesive system self-etching' associated to a composed resin, in dentin surfaces conditioned with the Er:YAG laser. For this study, freshly extracted human teeth were used and in each one the dentinal surfaces , which were treated with three sandpapers of different granulations (120,400,600), to obtain a standard of the smear layer, before the irradiation of the laser and of the restoring procedure. After these procedures the specimens were storage in distilled water at 37 deg C for 24 hours. Soon after, they were submitted to the tensile strength test .After analyzing the results, we can concluded that the use of the Er:YAG laser can substitute the drill without the need of conditioning, when using the adhesive system 'self-etching' in the dentinal surfaces because there was a decline in the strength of adhesion in the groups conditioned with the laser. (author)

  8. Rebond strength of bonded lingual wire retainers

    NARCIS (Netherlands)

    van Westing, K.; Algera, T.J.; Kleverlaan, C.J.

    2012-01-01

    There is no consensus in the literature concerning the rebonding procedure for orthodontic retainers. The aim of this in vitro study was to evaluate the bond and rebond strength of retainers bonded to enamel surfaces with and without composite remnants. The retainers were bonded with Excite and

  9. Wood structure and adhesive bond strength

    Science.gov (United States)

    Charles R. Frihart

    2006-01-01

    Much of the literature on the bonding of wood and other lignocellulosic materials has concentrated on traditional adhesion theories. This has led to misconceptions because wood is a porous material on both the macroscopic and microscopic levels. A better understanding of wood bonding can be developed by investigating the theories of adhesion and bond strength, taking...

  10. Peculiar structure and tensile strength of WB4: nonstoichiometric origin

    Directory of Open Access Journals (Sweden)

    Huiyang Gou

    2012-03-01

    Full Text Available Tungsten tetraboride (WB4 is experimentally considered as potentially superhard material and is therefore expected to have highly structural stability and enhanced resistance against plastic deformation and failure. The examinations of bond-deformation mechanism suggest a significantly soft bond-deformation pattern induced by ionic W-B bonding for nominal WB4 in experiments, largely responsible for the limitation of its strength and structural integrity. Computations on the structures and mechanical properties for WB4 show a novel thermodynamically favored MoB4-type phase with excellent mechanical properties and remarkable incompressibility along c direction. The illustrations of nonstoichiometry and x-ray diffraction spectra rationalize the experimental observation of nominal composition WB4 as defective tungsten borides (W1-xB3 (x0.25. The results provide new insight into the real structural and mechanical properties of tungsten borides.

  11. A comparison of finite element analysis with in vitro bond strength tests of the bracket-cement-enamel system

    NARCIS (Netherlands)

    Algera, T.J.; Feilzer, A.J.; Prahl-Andersen, B.; Kleverlaan, C.J.

    2011-01-01

    The aim of this study was to determine the in vitro shear bond strength (SBS) and tensile bond strength (TBS) of 45 metal brackets bonded with Transbond XT to bovine enamel. The SBS was determined by loading the short and the long sides of the bracket base. Testing took place after storage of the

  12. A new concept and finite-element study on dental bond strength tests.

    Science.gov (United States)

    Jin, Xiao-Zhuang; Homaei, Ehsan; Matinlinna, Jukka Pekka; Tsoi, James Kit Hon

    2016-10-01

    Numerous bond strength tests have been performed on dental adhesion experiments. Yet, the validity of these bond strength tests is controversial due to the name (e.g., "shear" or "tensile") may not reflect to the true and complete stress situation, i.e., assumed uniform shear or uniaxial tensile conditions. Thus, the aim of this study was to simulate and compare the stress distribution of and between shear bond strength (SBS), tensile bond strength (TBS), mold-enclosed shear bond strength (ME-SBS) and de novo lever-induced mold-enclosed shear bond strength (LIME-SBS) tests. 3-Dimensional finite element method (FEM) was used on the dental resin-bonded surfaces (i.e., titanium alloy, dentine and porcelain) interphased with adhesive layer (thickness 5μm) to simulate the mechanical tests. For ME-SBS, both polycarbonate and stainless steel molds were used. For LIME-SBS, stainless steel levers and molds with lengths of 3mm, 6mm, 12mm, 15mm and 18mm were used. The applied loads on these models were 50N, 100N and 200N. De novo LIME-SBS test was the most optimal configuration to evaluate "shear" bond strength of adhesive in regards to providing significantly high and uniform shear stress as well as eliminating tensile stress at the interface. The conventional SBS test created very high tensile stress at the load area, whereas the TBS created optimal tensile stress but shear stress indeed co-exist. The ME-SBS test could also eliminate some of the tensile stress. Similar stress distributions pattern appeared on the Ti-adhesive models, the dentine-adhesive models and porcelain-adhesive models. None of the bond strength tests could give purely "shear" or "tensile" bond strength, but LIME-SBS seems to be the best model to evaluate the bond strength under true "shear" mode. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  13. Evaluation of ultimate tensile strength using Miniature Disk Bend Test

    Science.gov (United States)

    Kumar, Kundan; Pooleery, Arun; Madhusoodanan, K.; Singh, R. N.; Chakravartty, J. K.; Shriwastaw, R. S.; Dutta, B. K.; Sinha, R. K.

    2015-06-01

    Correlations for evaluation of Ultimate Tensile Strength (UTS) using Miniature Disk Bend Test (MDBT) or Small Punch Test (SPT) has been an open issue since the development of the techniques. The larger plastic strains, in tri-axial state of stress during SPT, make the translation to the equivalent uniaxial parameter less certain. Correlations based on Pmax of load-displacement curve are also in disagreement as the point corresponding to Pmax does not represent a necking situation as in case of UTS, in a uniaxial tensile test. In present work, an attempt has been made for locating necking zone, which appears prior to Pmax, through experiments and FEM analyses. Experimental results on disk specimens from 20MnMoNi55, CrMoV ferritic steel and SS304LN materials along with FEM analyses found that load corresponding to 0.48 mm displacement is to be very close to the necking zone, and gives best fit for a UTS correlation.

  14. Effect of Fibre Hybridization on Compressive Strength, Split Tensile Strength and Water Permeability of SFRC

    Directory of Open Access Journals (Sweden)

    M P Singh

    2014-09-01

    Full Text Available The paper presents results of an investigation conducted to study the compressive strength, split tensile strength and water permeability of fibre concrete mixes containing steel fibres in mono, binary and ternary combinations. Steel fibres of different lengths i.e. 12.5 mm, 25 mm and 50 mm having constant diameter of 0.6 mm were used to obtain mono, binary and ternary combinations. A reference concrete mix with no fibres was also used for comparison purpose. The total fibre volume fraction was kept at 1.0% in all the mixes. Compressive strength, split tensile strength and water permeability tests were conducted of specimens of size 100 x 100 x 100 mm after 28 days of curing.  It has been observed that a fibre combination of 33% 12.5 mm + 33% 25 mm + 33% 50 mm long fibres can be adjudged as the most appropriate combination to be employed  in HySFRC for compressive strength, split tensile strength and water permeability.

  15. The effect of silanated and impregnated fiber on the tensile strength of E-glass fiber reinforced composite retainer

    Directory of Open Access Journals (Sweden)

    Niswati Fathmah Rosyida

    2015-12-01

    Full Text Available Background: Fiber reinforced composite (FRC is can be used in dentistry as an orthodontic retainer. FRC  still has a limitations because of to  a weak bonding between fibers and matrix. Purpose: This research was aimed to evaluate the effect of silane as coupling agent and fiber impregnation on the tensile strength of E-glass FRC. Methods: The samples of this research were classified into two groups each of which consisted of three subgroups, namely the impregnated fiber group (original, 1x addition of silane, 2x addition of silane and the non-impregnated fiber group (original, 1x addition of silane, 2x addition of silane. The tensile strength was measured by a universal testing machine. The averages of the tensile strength in all groups then were compared by using Kruskal Wallis and Mann Whitney post hoc tests. Results: The averages of the tensile strength (MPa in the impregnated fiber group can be known as follow; original impregnated fiber (26.60±0.51, 1x addition of silane (43.38±4.42, and 2x addition of silane (36.22±7.23. The averages of tensile strength (MPa in the non-impregnated fiber group can also be known as follow; original non-impregnated fiber (29.38±1.08, 1x addition of silane (29.38±1.08, 2x addition of silane (12.48±2.37. Kruskal Wallis test showed that there was a significant difference between the impregnated fiber group and the non-impregnated fiber group (p<0.05. Based on the results of post hoc test, it is also known that the addition of silane in the impregnated fiber group had a significant effect on the increasing of the tensile strength of E-glass FRC (p<0.05, while the addition of silane in the non-impregnated fiber group had a significant effect on the decreasing of the tensile strength of E-glass FRC. Conclusion: It can be concluded that the addition of silane in the non-silanated fiber group can increase the tensile strength of E-glass FRC, but the addition of silane in the silanated fiber group can

  16. Tensile strength and the mining of black holes.

    Science.gov (United States)

    Brown, Adam R

    2013-11-22

    There are a number of important thought experiments that involve raising and lowering boxes full of radiation in the vicinity of black hole horizons. This Letter looks at the limitations placed on these thought experiments by the null energy condition, which imposes a fundamental bound on the tensile-strength-to-weight ratio of the materials involved, makes it impossible to build a box near the horizon that is wider than a single wavelength of the Hawking quanta, and puts a severe constraint on the operation of "space elevators" near black holes. In particular, it is shown that proposals for mining black holes by lowering boxes near the horizon, collecting some Hawking radiation, and dragging it out to infinity cannot proceed nearly as rapidly as has previously been claimed. As a consequence of this limitation, the boxes and all the moving parts are superfluous and black holes can be destroyed equally rapidly by threading the horizon with strings.

  17. Tensile Strength of Polyester Composites Reinforced with Fique Fibers

    Science.gov (United States)

    Altoé, Giulio Rodrigues; Netto, Pedro Amoy; Teles, Maria Carolina Andrade; Daniel, Glenio; Margem, Frederico Muylaert; Monteiro, Sergio Neves

    The environmental concern is creating pressure for the substitution of high energy consumption materials for natural and sustainable ones. Compared to synthetic fibers, natural fibers have shown advantages in technical aspects such as flexibility and toughness. So there is a growing worldwide interest in the use of these fibers. Fique fiber extracted from fique plant, presents some significant characteristic, but until now only few studies on fique fiber were performed. This work aims to make the analysis of the tensile strength of polyester composites reinforced with fique fibers. The fibers were incorporated into the polyester matrix with volume fraction from 0 to 30%. After fracture the specimens were analyzed by a SEM (scanning electron microscope).

  18. Avaliação da força de tração em braquetes colados pela técnica indireta com diferentes sistemas de adesão Evaluation of tensile strength of brackets bonded by indirect technique

    Directory of Open Access Journals (Sweden)

    André Tortamano

    2007-06-01

    by direct and indirect techniques with orthodontic composite resins: group I (Control I - direct bonding using Concise (3M-Unitek-EUA; group II (Control II - direct bonding using Transbond (3M-Unitek-EUA with XT bond system; group III - indirect bonding using Concise (3M-Unitek-EUA; group IV - indirect bonding using Transbond (3M-Unitek-EUA with XT bonding system; group V - indirect bonding using Transbond with Sondhi bonding system (3M-Unitek-EUA. The Sondhi bonding system was designed specifically for indirect bonding. In the direct bonding technique brackets were placed directly on the enamel surface, in the indirect technique brackets were first bonded in a cast of the teeth and then they were transfered by means of a tray to the teeth. The samples were submitted to tensile tests (Instron 4400 and the statistical ANOVA and Tukey ( 1% tests were applied. RESULTS: The groups III and V showed lower bond strength than control groups (I and II, there was no significant difference between group IV and control groups (I and II. CONCLUSION: It was concluded that for indirect bonding technique only the Transbond XT (3M didn't show significant statistical difference when compared to the direct bonding technique.

  19. Low tensile strength in older concrete structures with alkali-silica reaction

    NARCIS (Netherlands)

    Siemes, A.J.M.; Visser, J.H.M.

    2000-01-01

    During an extensive investigation of some 25 concrete bridges and other structures suffer-ing from alkali-silica reaction it has been found that the uniaxial tensile strength of the concrete was extremely low in relation to both the compressive strength and the splitting tensile strength. It is

  20. Tensile strength of tablets containing two materials with a different compaction behaviour

    NARCIS (Netherlands)

    Van Veen, B.; van der Voort Maarschalk, Kees; Bolhuis, G.K.; Zuurman, K.; Frijlink, H.W.

    2000-01-01

    The tensile strength of tablets compressed from binary mixtures is in general not linearly related to the strength of tablets prepared from single materials; in many cases it shows a decreased tensile strength relative to interpolation. The materials used in this study, sodium chloride and

  1. 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.

  2. Bond strength of cementitious borehole plugs in welded tuff

    Energy Technology Data Exchange (ETDEWEB)

    Akgun, H.; Daemen, J.J.K. [Arizona Univ., Tucson, AZ (USA). Dept. of Mining and Geological Engineering

    1991-02-01

    Axial loads on plugs or seals in an underground repository due to gas, water pressures and temperature changes induced subsequent to waste and plug emplacement lead to shear stresses at the plug/rock contact. Therefore, the bond between the plug and rock is a critical element for the design and effectiveness of plugs in boreholes, shafts or tunnels. This study includes a systematic investigation of the bond strength of cementitious borehole plugs in welded tuff. Analytical and numerical analysis of borehole plug-rock stress transfer mechanics is performed. The interface strength and deformation are studied as a function of Young`s modulus ratio of plug and rock, plug length and rock cylinder outside-to-inside radius ratio. The tensile stresses in and near an axially loaded plug are analyzed. The frictional interface strength of an axially loaded borehole plug, the effect of axial stress and lateral external stress, and thermal effects are also analyzed. Implications for plug design are discussed. The main conclusion is a strong recommendation to design friction plugs in shafts, drifts, tunnels or boreholes with a minimum length to diameter ratio of four. Such a geometrical design will reduce tensile stresses in the plug and in the host rock to a level which should minimize the risk of long-term deterioration caused by excessive tensile stresses. Push-out tests have been used to determine the bond strength by applying an axial load to cement plugs emplaced in boreholes in welded tuff cylinders. A total of 130 push-out tests have been performed as a function of borehole size, plug length, temperature, and degree of saturation of the host tuff. The use of four different borehole radii enables evaluation of size effects. 119 refs., 42 figs., 20 tabs.

  3. Repair Bond Strength of Aged Resin Composite after Different Surface and Bonding Treatments

    Directory of Open Access Journals (Sweden)

    Michael Wendler

    2016-07-01

    Full Text Available The aim of this study was to compare the effect of different mechanical surface treatments and chemical bonding protocols on the tensile bond strength (TBS of aged composite. Bar specimens were produced using a nanohybrid resin composite and aged in distilled water for 30 days. Different surface treatments (diamond bur, phosphoric acid, silane, and sandblasting with Al2O3 or CoJet Sand, as well as bonding protocols (Primer/Adhesive were used prior to application of the repair composite. TBS of the specimens was measured and the results were analyzed using analysis of variance (ANOVA and the Student–Newman–Keuls test (α = 0.05. Mechanically treated surfaces were characterized under SEM and by profilometry. The effect of water aging on the degree of conversion was measured by means of FTIR-ATR spectroscopy. An important increase in the degree of conversion was observed after aging. No significant differences in TBS were observed among the mechanical surface treatments, despite variations in surface roughness profiles. Phosphoric acid etching significantly improved repair bond strength values. The cohesive TBS of the material was only reached using resin bonding agents. Application of an intermediate bonding system plays a key role in achieving reliable repair bond strengths, whereas the kind of mechanical surface treatment appears to play a secondary role.

  4. Effect of maleated natural rubber on tensile strength and compatibility of natural rubber/coconut coir composite

    Science.gov (United States)

    Ujianto, O.; Noviyanti, R.; Wijaya, R.; Ramadhoni, B.

    2017-07-01

    Natural rubber (NR)/coconut coir (CF) composites were fabricated using co-rotating twin screw extruder with maleated NR (MNR) used as compatibilizer. The MNR was produced at three level of maleic anhydride (MA), and analyzed qualitative and quantitatively using FTIR and titration technique. Analysis on MNR using FTIR and titration methods showed that MA was grafted on NR chain at different percentage (0.76, 2.23, 4.79%) depended on MA concentration. Tensile strength data showed the best tensile strength was produced at 7 phr of MNR with 1 phr of MA level in MNR resulting 16.4 MPa. The improvement of compatibilized samples were more than 300% compare to uncompatibilized composite attributed to better interfacial bonding. The improvement on tensile strength was significantly influenced by MNR level and amount of MA added to produce MNR, as well as their interaction. The optimum conditions for producing NR-CF composite were predicted at 6.5 phr of MNR level with 1 phr of MA concentration added in MNR production, regardless screw rotation settings. Results from verification experiments confirm that developed model was capable of describing phenomena during composite preparation. Morphology analysis using scanning electron microscopy shows smooth covered fiber in compatibilized samples than that of without MNR. The morphology also showed less voids on compatibilized samples attributed to better interfacial bonding leading to tensile strength improvement.

  5. Flexural and diametral tensile strength of composite resins

    Directory of Open Access Journals (Sweden)

    Álvaro Della Bona

    2008-03-01

    Full Text Available This study evaluated the flexural strength (sf and the diametral tensile strength (st of light-cured composite resins, testing the hypothesis that there is a positive relation between these properties. Twenty specimens were fabricated for each material (Filtek Z250- 3M-Espe; AM- Amelogen, Ultradent; VE- Vit-l-escence, Ultradent; EX- Esthet-X, Dentsply/Caulk, following ISO 4049 and ANSI/ADA 27 specifications and the manufacturers’ instructions. For the st test, cylindrical shaped (4 mm x 6 mm specimens (n = 10 were placed with their long axes perpendicular to the applied compressive load at a crosshead speed of 1.0 mm/min. The sf was measured using the 3-point bending test, in which bar shaped specimens (n = 10 were tested at a crosshead speed of 0.5 mm/min. Both tests were performed in a universal testing machine (EMIC 2000 recording the fracture load (N. Strength values (MPa were calculated and statistically analyzed by ANOVA and Tukey (a = 0.05. The mean and standard deviation values (MPa were Z250-45.06 ± 5.7; AM-35.61 ± 5.4; VE-34.45 ± 7.8; and EX-42.87 ± 6.6 for st; and Z250-126.52 ± 3.3; AM-87.75 ± 3.8; VE-104.66 ± 4.4; and EX-119.48 ± 2.1 for sf. EX and Z250 showed higher st and sf values than the other materials evaluated (p < 0.05, which followed a decreasing trend of mean values. The results confirmed the study hypothesis, showing a positive relation between the material properties examined.

  6. Dynamic rock tensile strengths of Laurentian granite: Experimental observation and micromechanical model

    Directory of Open Access Journals (Sweden)

    Kaiwen Xia

    2017-02-01

    Full Text Available Tensile strength is an important material property for rocks. In applications where rocks are subjected to dynamic loads, the dynamic tensile strength is the controlling parameter. Similar to the study of static tensile strength, there are various methods proposed to measure the dynamic tensile strength of rocks. Here we examine dynamic tensile strength values of Laurentian granite (LG measured from three methods: dynamic direct tension, dynamic Brazilian disc (BD test, and dynamic semi-circular bending (SCB. We found that the dynamic tensile strength from direct tension has the lowest value, and the dynamic SCB gives the highest strength at a given loading rate. Because the dynamic direct tension measures the intrinsic rock tensile strength, it is thus necessary to reconcile the differences in strength values between the direct tension and the other two methods. We attribute the difference between the dynamic BD results and the direct tension results to the overload and internal friction in BD tests. The difference between the dynamic SCB results and the direct tension results can be understood by invoking the non-local failure theory. It is shown that, after appropriate corrections, the dynamic tensile strengths from the two other tests can be reduced to those from direct tension.

  7. Shear bond strength of cement to zirconia

    NARCIS (Netherlands)

    Rosentritt, M.; Behr, M.; van der Zel, J.M.; Feilzer, A.J.

    2009-01-01

    This study investigated the shear bond strength (SBS) of various cements to zirconia ceramic. CoCr-cylinders were bonded to zirconia plates (20 mm × 10 mm × 2 mm; n = 8 per group) using four self-adhesive resin cements (one capsule, three hand-mixed) and four resin cements, partly in combination

  8. Strength Optimization of Thermally Bonded Spunbond Nonwovens

    OpenAIRE

    Nataliya Fedorova, Ph.D; Svetlana Verenich, Ph.D.; Behnam Pourdeyhimi, Ph.D.

    2007-01-01

    Recent research on all aspects of thermally point bonded nonwovens has led to considerable improvements in the understanding of material requirements for these nonwovens, the changes that occur during bonding and the resultant deterioration of the mechanical properties of the nonwoven materials. This paper addresses how one may use a bicomponent fiber technology to overcome the shortcomings of the thermal bonding and obtain high strength spunbond fabrics. In particular, we present the utility...

  9. Effect of post translucency on bond strength of different resin luting agents to root dentin.

    Science.gov (United States)

    Zamboni Quitero, Mayra Fidelis; Garone-Netto, Narciso; de Freitas, Patrícia Moreira; de Cerqueira Luz, Maria Aparecida Alves

    2014-01-01

    Translucent fiber posts were developed to conduct light into the root canal more effectively, thereby contributing to the polymerization of dual-polymerized resin luting agents. However, there is no consensus in the literature regarding their effectiveness. The purpose of this study was to evaluate the tensile bond strength of fiber posts with different degrees of translucency to bovine dentin with 3 types of resin luting agents. Ninety bovine roots were endodontically treated and divided into 9 groups (n=10) according to the type of post (translucent, white, and black) and resin luting agent (dual-polymerized self-adhesive; dual-polymerized + etch-and-rinse adhesive system; and autopolymerized + etch-and-rinse adhesive system). Tensile tests were performed on a universal testing machine (0.5 mm/min). To determine tensile stress, the bond area of each specimen was calculated. Data were statistically analyzed with ANOVA, Kruskal-Wallis, and Mann-Whitney tests (α=.05). Mean (standard deviation) tensile bond strength values (5.53 ± 2.29 MPa) were significantly lower for translucent posts than for white (9.51 ± 1.31 MPa) and black posts (10.12 ± 3.44 MPa) with a dual-polymerized luting agent in combination with an adhesive system (P=.012). For white (6.02 ± 1.88 MPa) and black posts (4.14 ± 0.6 MPa), the self-adhesive luting agent led to lower tensile bond strength than the dual-polymerized luting agent in combination with an adhesive system (P=.003). Irrespective of post type, the autopolymerized luting agent provided the lowest tensile bond strength (Pdentin. Post translucency did not increase the tensile bond strength of dual-polymerized resin luting agents. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  10. Tensile bond strength of self-etching versus total-etching adhesive systems under different dentinal substrate conditions Resistência de união à tração de sistemas adesivos autocondicionantes versus de condicionamento total, em diferentes condições de substrato dentinário

    Directory of Open Access Journals (Sweden)

    Alexandre Henrique Susin

    2007-03-01

    Full Text Available The use of acid etchants to produce surface demineralization and collagen network exposure, allowing adhesive monomers interdiffusion and consequently the formation of a hybrid layer, has been considered the most efficient mechanism of dentin bonding. The aim of this study was to compare the tensile bond strength to dentin of three adhesive systems, two self-etching ones (Clearfil SE Bond - CSEB and One Up Bond F - OUBF and one total-etching one (Single Bond - SB, under three dentinal substrate conditions (wet, dry and re-wet. Ninety human, freshly extracted third molars were sectioned at the occlusal surface to remove enamel and to form a flat dentin wall. The specimens were restored with composite resin (Filtek Z250 and submitted to tensile bond strength testing (TBS in an MTS 810. The data were submitted to two-way ANOVA and Tukey's test (p = 0.05. Wet dentin presented the highest TBS values for SB and CSEB. Dry dentin and re-wet produced significantly lower TBS values when using SB. OUBF was not affected by the different conditions of the dentin substrate, producing similar TBS values regardless of the surface pretreatments.O uso de condicionadores ácidos para desmineralizar a superfície dental e expor a rede de fibras colágenas para interdifusão dos monômeros adesivos e conseqüente formação da camada híbrida tem sido considerado o mais eficiente mecanismo de adesão dos agentes de união. O objetivo deste estudo foi comparar a resistência de união à dentina de três sistemas adesivos, dois autocondicionantes (Clearfil SE Bond - CSEB e One Up Bond F - OUBF e um de condicionamento total (Single Bond - SB, sob três diferentes condições de substrato dentinário (úmido, seco e reidratado. Noventa terceiros molares humanos recém-extraídos foram cortados na superfície oclusal, para se remover o esmalte e formar uma parede plana de dentina. Os espécimes foram restaurados com resina composta (Filtek Z250 e submetidos ao teste de

  11. Investigation of anistropic behavior of Montney Shale under indirect tensile strength test

    Energy Technology Data Exchange (ETDEWEB)

    Keneti, S.A.R.; Wong, R.C.K. [Calgary Univ., Calgary, AB (Canada)

    2010-07-01

    The Montney Shale Formation is located near the British Columbia and Alberta borders and is one of the largest economically feasible resource plays in North America. Hydraulic fracturing is used to enhance the gas production. Initiation and propagation of hydraulically induced fracture is controlled by in-situ stresses magnitude and orientation and the reservoir tensile strength. The tensile strength becomes one of the most important parameters in governing hydraulic fracturing of the reservoir if the in-situ stresses composing one vertical and two horizontal stresses are comparable or lie within a narrow range. Different point and line load tests were used in this study to determine the tensile strength of Montney shale cores in two perpendicular directions. The paper discussed image analysis of Montney shale cores and tensile strength tests, including Brazilian tests for measuring tensile strength in the horizontal direction and point load tests for measuring tensile strength in the vertical direction. The effect of anisotropic tensile strength on hydraulic fracturing of Montney shale was also presented. It was concluded from the test results that the Montney shale exhibits a high anisotropy in tensile strength. 11 refs., 3 tabs., 11 figs.

  12. The effect of processing on defects and tensile strength of single flax fibres

    DEFF Research Database (Denmark)

    Aslan, Mustafa; Mehmood, Shahid; Madsen, Bo

    2010-01-01

    This study is to investigate the influence of consecutive processing steps on the defects and the tensile strength of single flax fibres. It was found that each processing step leads to an increasing number of defects and larger defect sizes, as well as decreasing tensile strength of the fibres....

  13. Guidelines to come to minimized tensile strength loss upon cellulase application

    NARCIS (Netherlands)

    Lenting, H.B.M.; Lenting, H.B.M.; Warmoeskerken, Marinus

    2001-01-01

    Application of cellulase technology in the textile production process often results in a certain loss of tensile strength along with the desired performance. In this paper guidelines are given how to come to minimization or even prevention of tensile strength loss. Part of the considerations is

  14. Fluid stiction modeling for quickly separating plates considering the liquid tensile strength

    DEFF Research Database (Denmark)

    Roemer, Daniel Beck; Johansen, Per; Pedersen, Henrik C.

    2015-01-01

    the time dependent fluid stiction phenomenon, including a fluid tensile strength and cavitation effects, is proposed. The model is based on Reynolds theory, and the pressure distribution in the liquid zone is solved analytically for each time step, leading to a computationally efficient model without...... given that proper selections of liquid tensile strength and initial plate distance are made....

  15. The tensile strength properties of CFRPs and GRRPs for Unnes electric car body material

    Science.gov (United States)

    Khumaedi, Muhammad; Sumbodo, Wirawan; Widodo, Rahmat Doni

    2016-04-01

    This paper describes composite materials tensile testing of electric car body material. The UNNES electric car body must be developed using a high strength and lightweight material. A fiber-reinforced plastic composite is widely used for the concerned objective. Selection of the type of composites, variations in fiber orientation, and the number of fiber layers will affect the tensile strength of the material. Composite materials use Carbon-fiber-reinforced plastics (CFRPs) and glass-fiber-reinforced plastics (GFRPs) variation to the fiber areal weight, variations in fiber orientation and the number of fiber layers. The CFRPs areal weight consists of 230 gsm and 400 gsm. The GFRPsareal weight consists of 400 gsm and 600 gsm. Fibre orientationsconsist of 0° and 45°. Number of fiber layers consists of one layer and two layers. Various variations were then tested to figure out their tensile to get ultimate tensile strength of materials. Standard test method for tensile test was conducted using ASTM D3039. Tensile specimen geometry used a type of balanced and symmetric fiber orientation, with 25mm in width, 250 mm in length, and 2.5 mm in thickness. The result shows that the more fiber areal weight and the layer number were used, the more its tensile strength would increase, beside it increased the ultimate tensile strength of the material for both glass and carbon fiber with 0o and 45o fiber arientation. Fiber plain wave with 45o has greater tensile strength compared to any other variation.

  16. Statistical Analysis and Prediction on Tensile Strength of 316L-SS Joints at High Temperature Based on Weibull Distribution

    Science.gov (United States)

    An, Z. L.; Chen, T.; Cheng, D. L.; Chen, T. H.; Y Wang, Z.

    2017-12-01

    In this work, the prediction on average tensile strength of 316L stainless steel is statistically analyzed by Weibull distribution method. Direct diffusion bonding of 316L-SS was performed at high temperature of 550°C and 8 tension tests were carried out. The results obtained vary between 87.8MPa and 160.8MPa. The probability distribution of material failure is obtained by using the Weibull distribution.

  17. Comparison of shear bond strength of the stainless steel metallic brackets bonded by three bonding systems

    Directory of Open Access Journals (Sweden)

    Mehdi Ravadgar

    2013-09-01

    Full Text Available Introduction: In orthodontic treatment, it is essential to establish a satisfactory bond between enamel and bracket. After the self-etch primers (SEPs were introduced for the facilitation of bracket bonding in comparison to the conventional etch-and-bond system, multiple studies have been carried out on their shear bond strengths which have yielded different results. This study was aimed at comparing shear bond strengths of the stainless steel metallic brackets bonded by three bonding systems. Methods: In this experimental in vitro study, 60 extracted human maxillary premolar teeth were randomly divided into three equal groups: in the first group, Transbond XT (TBXT light cured composite was bonded with Transbond plus self-etching primer (TPSEP; in the second group, TBXT composite was bonded with the conventional method of acid etching; and in the third group, the self cured composite Unite TM bonding adhesive was bonded with the conventional method of acid etching. In all the groups, Standard edgewise-022 metallic brackets (American Orthodontics, Sheboygan, USA were used. Twenty-four hours after the completion of thermocycling, shear bond strength of brackets was measured by Universal Testing Machine (Zwick. In order to compare the shear bond strengths of the groups, the variance analysis test (ANOVA was adopted and p≤0.05 was considered as a significant level. Results: Based on megapascal, the average shear bond strength for the first, second, and third groups was 8.27±1.9, 9.78±2, and 8.92±2.5, respectively. There was no significant difference in the shear bond strength of the groups. Conclusions: Since TPSEP shear bond strength is approximately at the level of the conventional method of acid etching and within the desirable range for orthodontic brackets shear bond strength, applying TPSEP can serve as a substitute for the conventional method of etch and bond, particularly in orthodontic operations.

  18. Effect of Curing Direction on Microtensile Bond Strength of Fifth and Sixth Generation Dental Adhesives

    Directory of Open Access Journals (Sweden)

    Ali Nadaf

    2012-09-01

    Full Text Available Background and Aims: Composite restorative materials and dental adhesives are usually cured with light sources. The light direction may influence the bond strength of dental adhesives. The aim of this study was to evaluate the effect of light direction on the microtensile bond strength of fifth and sixth generation dental adhesives.Materials and Methods: Prime & Bond NT and Clearfil SE bond were used with different light directions.Sixty human incisor teeth were divided into 4 groups (n=15. In groups A and C, Clearfil SE bond with light curing direction from buccal was used for bonding a composite resin to dentin. In groups B and D, Prime & Bond NT with light curing direction from composite was used. After thermocycling the specimens were subjected to tensile force until debonding occurred and values for microtensile bond strength were recorded. The data were analyzed using two-way ANOVA and Tukey post hoc test.Results: The findings showed that the bond strength of Clearfil SE bond was significantly higher than that of Prime&Bond NT (P<0.001. There was no significant difference between light curing directions (P=0.132.Conclusion: Light curing direction did not have significant effect on the bond strength. Sixth generation adhesives was more successful than fifth generation in terms of bond strength to dentin.

  19. Correlation between flexural and indirect tensile strength of resin composite cements.

    Science.gov (United States)

    Cassina, Gianluca; Fischer, Jens; Rohr, Nadja

    2016-11-04

    To evaluate a potential correlation between flexural strength and indirect tensile strength in assessing the mechanical strength of resin composite cements. Flexural strength (n = 5) and indirect tensile strength (n = 5) of 7 resin composite cements (RelyX Unicem 2 Automix [RXU], Panavia SA [PSA], Clearfil SA [CSA], Panavia F2.0 [PF2], Multilink Implant [MLI], DuoCem [DCM], Panavia 21 [P21]) were determined. Specimens were either auto-polymerized or dual-cured (except P21) and stored in water at 37 °C for 1 day prior to measurement. Flexural and indirect tensile strength of 4 cements (RXU, PSA, PF2, MLI) was additionally measured directly after curing and after 96 h water storage at 37 °C. Except for PF2, dual-cured specimens achieved higher flexural strength than auto-polymerized specimens. In the indirect tensile strength test differences in auto-polymerized and dual-cured specimens were only detected for RXU and DCM. A general non-linear correlation was found between flexural and indirect tensile strength values. However, strength values of auto-polymerized and dual-cured specimens did not generally correlate. Flexural strength and indirect tensile strength of resin composite cements are correlated. At high strength values the indirect tensile test is less sensitive than the flexural test. The results suggest that the indirect tensile test may only be recommended as a screening test especially for low or medium strength resin composite cements.

  20. Effect of desensitizing treatments on bond strength of resin composites to dentin - an in vitro study.

    Science.gov (United States)

    Makkar, Sameer; Goyal, Meenu; Kaushal, Ashih; Hegde, Vivek

    2014-09-01

    Hypersensitivity is a common clinical multietiological problem. Many desensitizing treatments are there to overcome hypersensitivity. The aim of this study was to evaluate the effect of different dentin-desensitizing treatments on the tensile bond strength of composite restoration. Twenty-four sound human molars were used. Enamel was wet abraded to expose flat dentin surfaces, polished with sandpaper. The specimens were then divided into three groups (n = 8) based on the type of dentin-desensitizing treatment given. The first group: G1 was the control group where no desensitizing agent was used. The second group: G2 was treated with desensitizing dentifrice containing a combination of potassium nitrate, triclosan, and sodium monoflorophosphate. The third group: G3 was treated with Er:YAG laser. Afterwards, the desensitized specimens were treated with one step self-etch adhesive according to manufacturer's instructions and composite microcylinders were packed. The specimens were then examined for tensile bond strength using universal tensile machine (KMI(TM) ). Statistical analysis of the data obtained revealed the mean values for the tensile bond strengths were 10.2613 MPa, 5.9400 MPa and 6.3575 MPa for groups 1, 2 and 3, respectively. These values were statistically significantly different between groups pretreated with laser or dentifrice as compared to control group. Dentifrice and Laser pre-treated dentin has lower tensile bond strength with resin composites as compared to dentin that is untreated.

  1. Influece of the austempering temperature on the tensile strength of the austempered ductile iron (ADI samples

    Directory of Open Access Journals (Sweden)

    S. Savićević

    2017-01-01

    Full Text Available Austempered Ductile Iron (ADI is a class of ductile iron subjected to a two-step heat treatment process – austenitization and austempering. The heat treatment gives to ADI a high value of tensile strength and an especially good strength-to-weight ratio. However, designers in most cases are unfamiliar with this material that can compete favorably with steel and aluminum castings, weldments and forgings. The high tensile strength of ADI is the result of its unique ausferrite microstructure. In this paper, an investigation of the influence of the austempering temperature on the tensile strength of the ADI samples is presented.

  2. Shear Bond Strength of Orthodontic Brackets Bonded to Zirconium Crowns.

    Science.gov (United States)

    Mehmeti, Blerim; Azizi, Bleron; Kelmendi, Jeta; Iljazi-Shahiqi, Donika; Alar, Željko; Anić-Milošević, Sandra

    2017-06-01

    An increasing demand for esthetic restorations has resulted in an increased use of all-ceramic restorations, such as zirconium. However, one of the challenges the orthodontist must be willing to face is how to increase bond strength between the brackets and various ceramic restorations.Bond strength can beaffected bybracket type, by the material that bracketsaremade of, and their base surface design or retention mode. ​: Aim: of this study was to perform a comparative analysis of the shear bond strength (SBS) of metallic and ceramic orthodontic brackets bonded to all-zirconium ceramic surfaces used for prosthetic restorations, and also to evaluate the fracture mode of these two types of orthodontic brackets. Twenty samples/semi-crowns of all-zirconium ceramic, on which orthodontic brackets were bonded, 10 metallic and 10 ceramic polycrystalline brackets, were prepared for this research. SBS has been testedby Universal Testing Machine, with a load applied using a knife edged rod moving at a fixed rate of 1 mm/min, until failure occurred. The force required to debond the brackets was recorded in Newton, then SBS was calculated to MPa. In addition, the samples were analyzed using a digital camera magnifier to determine Adhesive Remnant Index (ARI). Statistical data were processed using t-test, and the level of significance was set at α = 0.05. Higher shear bond strength values were observed in metallic brackets bonded to zirconium crowns compared tothoseof ceramic brackets, with a significant difference. During the test, two of the ceramic brackets were partially or totally damaged. Metallic brackets, compared to ceramic polycrystalline brackets, seemed tocreate stronger adhesion with all-zirconium surfaces due to their better retention mode. Also, ceramic brackets showed higher fragility during debonding.

  3. Evaluation of the tensile strength of the human ureter - Preliminary results.

    Science.gov (United States)

    Shilo, Yaniv; Pichamuthu, Joseph E; Averch, Timothy D; Vorp, David A

    2014-09-15

    Introduction: Ureteral injuries such as avulsion are directly related to mechanical damage of the ureter. Understanding the tensile strength of this tissue may assist in prevention of iatrogenic injuries. Few published studies have looked at the mechanical properties of the animal ureter, and of those none have determined the tensile strength of the human ureter. Therefore, the purpose of this work was to determine the tensile strength of the human ureter. Materials and Methods: We harvested 11 human proximal ureters from patients who were undergoing nephrectomy for either kidney tumors or non-functioning kidney. The specimens were then cut into multiple circumferentially and longitudinally-oriented tissue strips for tensile testing. Strips were uniaxially stretched to failure in a tensile testing machine. The corresponding force and displacement were recorded. Finally, stress at failure was noted as the tensile strength of the sample. Circumferential tensile strength was also compared in the proximal and distal regions of the specimens. Results: The tensile strength of the ureter in circumferential and longitudinal orientations was found to be 457.52±33.74 Ncm-2 and 902.43±122.08 Ncm-2, respectively (pstrength in the proximal portion of the ureter was 409.89±35.13 Ncm-2 in comparison to 502.89±55.85 Ncm-2 in the distal portion (p=0.08). Conclusions: The circumferential tensile strength of the ureter was found to be significantly lower than the longitudinal strength. Circumferential tensile strength was also lower with more proximal parts of the ureter. This information may be important for the design of "intelligent" devices and simulators in order to prevent complications.

  4. Evaluation of the tensile strength of the human ureter--preliminary results.

    Science.gov (United States)

    Shilo, Yaniv; Pichamuthu, Joseph E; Averch, Timothy D; Vorp, David A

    2014-12-01

    Ureteral injuries such as avulsion are directly related to mechanical damage of the ureter. Understanding the tensile strength of this tissue may assist in prevention of iatrogenic injuries. Few published studies have looked at the mechanical properties of the animal ureter and, of those, none has determined the tensile strength of the human ureter. Therefore, the purpose of this work was to determine the tensile strength of the human ureter. We harvested 11 human proximal ureters from patients who were undergoing nephrectomy for either kidney tumors or nonfunctioning kidney. The specimens were then cut into multiple circumferentially and longitudinally oriented tissue strips for tensile testing. Strips were uniaxially stretched to failure in a tensile testing machine. The corresponding force and displacement were recorded. Finally, stress at failure was noted as the tensile strength of the sample. Circumferential tensile strength was also compared in the proximal and distal regions of the specimens. The tensile strength of the ureter in circumferential and longitudinal orientations was found to be 457.52±33.74 Ncm(-2) and 902.43±122.08 Ncm(-2), respectively (Pureter was 409.89±35.13 Ncm(-2) in comparison with 502.89±55.85 Ncm(-2) in the distal portion (P=0.08). The circumferential tensile strength of the ureter was found to be significantly lower than the longitudinal strength. Circumferential tensile strength was also lower with more proximal parts of the ureter. This information may be important for the design of "intelligent" devices and simulators to prevent complications.

  5. Influence of Bovine Dentin Site on the Bond Strength of Resin Cement

    OpenAIRE

    Tohru, HAYAKAWA; Hiroyuki, Mishima; Shuichi, YAMAKAWA; Mikiko, MASUDA; Masahiro, AIDA; Kimiya, NEMOTO; Yukishige, Kozawa; Department of Crown and Bridge Prosthodontics, Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo; Department of Dental Materials, Research Institute of Oral Science, Nihon Univerity School of Dentistry at Matsudo; Department of Anatomy, Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo

    2001-01-01

    The purpose of this study is to investigate the influences of types of resin cements and dentin site(crown and root part)on the adhesion of resin cement to dentin. Three types of resin cements; Super-Bond C&B, Bistite II and Scotchbond Resin Cement were used. The tensile bond strength of each resin cement to crown and root dentin of bovine incisors was measured after 24 hours immersion in water at 37℃. Super-Bond C&B showed no significant difference in bond strength between crown and root den...

  6. Resistência de união entre cimentos e liga de níquel-cromo, em função da ciclagem térmica e variações no procedimento de união Tensile bond strength between cements and nickel-chromium alloy related to thermocycling and adhesive variations

    Directory of Open Access Journals (Sweden)

    Ricardo Ruiz MARTUCI

    1999-07-01

    Full Text Available A investigação teve a finalidade de avaliar a resistência de união de uma liga de níquel-cromo com diversos agentes cimentantes frente à imersão, sem ou com termociclagem e idade. A liga usada foi a Litecast B. Os sistemas adesivos usados foram Ketac-Cem, Vitremer, Enforce com Flúor em três variações: a com primer apenas (Enforce P; b com primer e adesivo (Enforce P + A; c apenas adesivo (Enforce A. Discos metálicos, obtidos por fundição, foram cimentados entre si, constituindo os corpos de prova, que foram imersos em água destilada e submetidos ou não à ciclagem térmica. Os testes foram feitos 1 e 90 dias após a cimentação. As conclusões foram: o Ketac-Cem apresentou baixa resistência adesiva, sendo superado pelo Vitremer; o Enforce P, embora aumentasse a resistência ao longo do tempo, fez com que ela permanecesse baixa; o Enforce P + A apresentou alta resistência em um dia, que diminuiu ao longo do tempo; o Enforce A apresentou superioridade adesiva, que se manteve ao longo do tempo com ciclagem térmica; a influência da ciclagem térmica foi dependente do sistema adesivo.We evaluated tensile bond strengths between a nickel-chromium alloy and cements at different times (one and 90 days using or not thermocycling. Alloy used was Litecast B, and luting cements were Ketac-Cem, Vitremer, and Fluoride Enforce with three variations: a only primer; b with primer and bond; c only with bond. Metallic discs with 6 mm diameter were cemented together and immersed in distilled water. Half specimens were thermocycled and half one not. Conclusions were: Ketac-Cem presented low bonding strength, being that of Vitremer very higher; the material Enforce when used only with primer increased adhesion with time but yet remained relatively low after 90 days; Enforce used with bond only achieved superior adhesion, still present specially with termocycling after 90 days; influence of thermocycling depends on adhesive system.

  7. Bond strength test of acrylic artificial teeth with prosthetic base

    Directory of Open Access Journals (Sweden)

    Erna Kurnikasari

    2008-07-01

    Full Text Available Denture consists of acrylic artificial teeth and acrylic prothesis base bond chemically with a bond strength of 315 kgF/cm2. Most of the commercial acrylic artificial teeth do not specify their specifications and all of those acrylic artificial teeth do not include mechanical data (bond strength. The aim of this study is to discover which acrylic artificial teeth meet ADA specification no. 15. This study is a descriptive analytic study performed to 5 acrylic artificial teeth posterior brands commonly used by dentists and technicians. From each brand, 3 sample teeth were taken. The acrylic artificial teeth were prepared into a rectangular shape and were attached between acrylic prothesis base simulation and jigs. The sample was given tensile load using a Universal Testing Machine. The amount of force that causes the teeth to be fractured was recorded and the bond strength was calculated. The results of the study show that the average value for the five acrylic artificial teeth for the five brands were as followed: Brand A, 125.993 kgF/cm2; B, 188.457 kgF/cm2; C, 175.880 kgF/cm2; D, 153.373 kgF/cm2; E, 82.839 kgF/cm2. The data can be tested statistically by using One Way ANOVA test and Dunnett test (alpha = 0.05. From the study, it is concluded that the five acrylic artificial teeth have a bond strength below the ADA specification no. 15.

  8. Increased Tensile Strength of Carbon Nanotube Yarns and Sheets through Chemical Modification and Electron Beam Irradiation

    Science.gov (United States)

    Miller, Sandi G.; Williams, Tiffany S.; Baker, James S.; Sola, Francisco; Lebron-Colon, Marisabel; McCorkle, Linda S.; Wilmoth, Nathan G.; Gaier, James; Chen, Michelle; Meador, Michael A.

    2014-01-01

    The inherent strength of individual carbon nanotubes offers considerable opportunity for the development of advanced, lightweight composite structures. Recent work in the fabrication and application of carbon nanotube (CNT) forms such as yarns and sheets has addressed early nanocomposite limitations with respect to nanotube dispersion and loading; and has pushed the technology toward structural composite applications. However, the high tensile strength of an individual CNT has not directly translated to macro-scale CNT forms where bulk material strength is limited by inter-tube electrostatic attraction and slippage. The focus of this work was to assess post processing of CNT sheet and yarn to improve the macro-scale strength of these material forms. Both small molecule functionalization and e-beam irradiation was evaluated as a means to enhance tensile strength and Youngs modulus of the bulk CNT material. Mechanical testing results revealed a tensile strength increase in CNT sheets by 57 when functionalized, while an additional 48 increase in tensile strength was observed when functionalized sheets were irradiated; compared to unfunctionalized sheets. Similarly, small molecule functionalization increased yarn tensile strength up to 25, whereas irradiation of the functionalized yarns pushed the tensile strength to 88 beyond that of the baseline yarn.

  9. Tensile and flexural strength of commercially pure titanium submitted to laser and tungsten inert gas welds.

    Science.gov (United States)

    Atoui, Juliana Abdallah; Felipucci, Daniela Nair Borges; Pagnano, Valéria Oliveira; Orsi, Iara Augusta; Nóbilo, Mauro Antônio de Arruda; Bezzon, Osvaldo Luiz

    2013-01-01

    This study evaluated the tensile and flexural strength of tungsten inert gas (TIG) welds in specimens made of commercially pure titanium (CP Ti) compared with laser welds. Sixty cylindrical specimens (2 mm diameter x 55 mm thick) were randomly assigned to 3 groups for each test (n=10): no welding (control), TIG welding (10 V, 36 A, 8 s) and Nd:YAG laser welding (380 V, 8 ms). The specimens were radiographed and subjected to tensile and flexural strength tests at a crosshead speed of 1.0 mm/min using a load cell of 500 kgf applied on the welded interface or at the middle point of the non-welded specimens. Tensile strength data were analyzed by ANOVA and Tukey's test, and flexural strength data by the Kruskal-Wallis test (α=0.05). Non-welded specimens presented significantly higher tensile strength (control=605.84 ± 19.83) (p=0.015) and flexural strength (control=1908.75) (p=0.000) than TIG- and laser-welded ones. There were no significant differences (p>0.05) between the welding types for neither the tensile strength test (TIG=514.90 ± 37.76; laser=515.85 ± 62.07) nor the flexural strength test (TIG=1559.66; laser=1621.64). As far as tensile and flexural strengths are concerned, TIG was similar to laser and could be suitable to replace laser welding in implant-supported rehabilitations.

  10. Comparison of tensile strength of different carbon fabric reinforced epoxy composites

    OpenAIRE

    Jane Maria Faulstich de Paiva; Sérgio Mayer; Mirabel Cerqueira Rezende

    2006-01-01

    Carbon fabric/epoxy composites are materials used in aeronautical industry to manufacture several components as flaps, aileron, landing-gear doors and others. To evaluate these materials become important to know their mechanical properties, for example, the tensile strength. Tensile tests are usually performed in aeronautical industry to determinate tensile property data for material specifications, quality assurance and structural analysis. For this work, it was manufactured four different l...

  11. Fatigue strength testing of LTCC and alumina ceramics bonds

    Science.gov (United States)

    Dąbrowski, A.; Matkowski, P.; Golonka, L.

    2012-12-01

    In this paper the results of fatigue strength tests of ceramic joints are presented. These tests have been performed on the samples subjected to thermal and vibration fatigue as well as on the reference samples without any additional loads. The main goal of the investigation was to determine the strength of hybrid ceramics joints using tensile testing machine. The experiment enabled evaluation of fatigue effects in the mentioned joints. Geometry of test samples has been designed according to FEM simulations, performed in ANSYS FEM environment. Thermal stress as well as the stress induced by vibrations have been analyzed in the designed model. In the experiments two types of ceramics have been used — LTCC green tape DP951 (DuPont) and alumina ceramic tape. The samples have been prepared by joining two sintered ceramic beams made of different types of material. The bonds have been realized utilizing low temperature glass or a layer of LTCC green tape.

  12. Microtensile bond strength of different adhesive systems in dentin irradiated with Er:YAG laser

    Science.gov (United States)

    Sierpinsky, L. M. G.; Lima, D. M.; Candido, M. S. M.; Bagnato, V. S.; Porto-Neto, S. T.

    2008-07-01

    The objective this study was to evaluate in vitro the bond strength of two etch-and-rise and one self-etching adhesive system after dentin irradiation with Er:YAG (erbium: yttrium aluminum garnet) laser using microtensile test. The results revealed that the groups treated with laser Er:YAG presented less tensile bond strength, independently to the adhesive system used. The prompt L-pop adhesive presented less microtensile bond strength compared to the other adhesives evaluated. There was no difference between single bond and excite groups. The adhesive failures were predominant in all the experimental groups. The Er:YAG laser influenced negatively bond strength values of adhesive systems tested in dental substrate.

  13. Effect of panel alignment and surface finish on bond strength

    Energy Technology Data Exchange (ETDEWEB)

    Wouters, J.M.; Doe, P.J. [Los Alamos National Lab., NM (United States); Baker, W.E. [New Mexico Univ., Albuquerque, NM (United States)

    1991-10-01

    The flexural strength of bonded acrylic is tested as a function of panel alignment and bond surface finish. Bond strength was shown to be highly dependent on both parameters with only a narrow range of values yielding a high strength bond. This study was performed for the heavy water-containing acrylic vessel for the Sudbury Neutrino Observatory detector.

  14. Tensile bond strength between different glass ionomer cement and composite resin using three adhesive systems Avaliação da resistência de união interfacial entre diferentes cimentos de ionômero de vidro e resina composta, usando três sistemas adesivos

    Directory of Open Access Journals (Sweden)

    Patrícia Dias

    2005-10-01

    Full Text Available The purpose of this study was to evaluate the tensile bond strength (TBS among a Composite Resin (Filtek Z250 and six conventional Glass Ionomer Cements, three used for lining (Bioglass F, Vidrion F and Glass Ionomer L.C. and three for restorations (Ketac Fil, Vidrion R and Glass Ionomer type II etched and non etched, using three adhesive systems (Single Bond, Bond 1 and Stae. Thirty-six groups were made, ten samples for each group, totalizing 360 specimens. There were significant differences on TBS among groups. Group 31 (Glass Ionomer Cement type II showed the highest TBS (9.65 MPa in comparison to other tested groups. Group 16 (Glass Ionomer L.C presented the lowest TBS (2.72 MPa in comparison to all the other groups. Therefore, it can be concluded that the acid etching of the Glass Ionomer Cement is not necessary. Foi avaliada, ">in vitro, a resistência de união, por tração, entre uma Resina Composta micro-híbrida (Filtek Z-250 e seis Cimentos de Ionômero de Vidro (CIV convencionais: três utilizados para base/forramento (Bioglass F, Vidrion F e Glass Ionomer Lining Cement e três para restauração (Ketac Fil, Vidrion R e Glass Ionomer Cement type II, sem e com condicionamento ácido ortofosfórico a 37%, usando três sistemas adesivos (Single Bond, Bond 1 e Stae. Foram confeccionados 36 grupos de 10 corpos-de-prova cada, totalizando 360 espécimes. Para análise estatística, foi utilizado o teste de Tukey-Kramer. Dentre os três CIV de base/forramento, os grupos 2 e 5 (Bioglass F apresentaram valores mais altos de adesividade à resina (7,24 e 6,03 MPa respectivamente. Quanto aos três CIV de restauração, todos apresentaram maior resistência de união, superior aos de base/forramento, sendo que o Glass Ionomer Cement type II (Grupo 31 e Vidrion R apresentaram maior força de adesão (9,65 e 7,47 MPa à resina composta. O grupo 16 (Glass Ionomer L.C. mostrou menor adesividade à resina (2,72 MPa. Houve diferenças significantes

  15. ZrO2 nanoparticles' effects on split tensile strength of self compacting concrete

    Directory of Open Access Journals (Sweden)

    Ali Nazari

    2010-12-01

    Full Text Available In the present study, split tensile strength of self compacting concrete with different amount of ZrO2 nanoparticles has been investigated. ZrO2 nanoparticles with the average particle size of 15 nm were added partially to cement paste (Portland cement together with polycarboxylate superplasticizer and split tensile strength of the specimens has been measured. The results indicate that ZrO2 nanoparticles are able to improve split tensile strength of concrete and recover the negative effects of polycarboxylate superplasticizer. ZrO2 nanoparticle as a partial replacement of cement up to 4 wt. (% could accelerate C-S-H gel formation as a result of increased crystalline Ca(OH2 amount at the early age of hydration. The increased the ZrO2 nanoparticles' content more than 4 wt. (%, causes the reduced the split tensile strength because of unsuitable dispersion of nanoparticles in the concrete matrix.

  16. Enamel Bond Strength of New Universal Adhesive Bonding Agents.

    Science.gov (United States)

    McLean, D E; Meyers, E J; Guillory, V L; Vandewalle, K S

    2015-01-01

    Universal bonding agents have been introduced for use as self-etch or etch-and-rinse adhesives depending on the dental substrate and clinician's preference. The purpose of this study was to evaluate the shear bond strength (SBS) of composite to enamel using universal adhesives compared to a self-etch adhesive when applied in self-etch and etch-and-rinse modes over time. Extracted human third molars were used to create 120 enamel specimens. The specimens were ground flat and randomly divided into three groups: two universal adhesives and one self-etch adhesive. Each group was then subdivided, with half the specimens bonded in self-etch mode and half in etch-and-rinse mode. The adhesives were applied as per manufacturers' instructions, and composite was bonded using a standardized mold and cured incrementally. The groups were further divided into two subgroups with 10 specimens each. One subgroup was stored for 24 hours and the second for six months in 37°C distilled water and tested in shear. Failure mode was also determined for each specimen. A three-way analysis of variance (ANOVA) found a significant difference between groups based on bonding agent (p0.05). Clearfil SE in etch-and-rinse and self-etch modes had more mixed fractures than either universal adhesive in either mode. Etching enamel significantly increased the SBS of composite to enamel. Clearfil SE had significantly greater bond strength to enamel than either universal adhesive, which were not significantly different from each other.

  17. Effects of soldering methods on tensile strength of a gold-palladium metal ceramic alloy.

    Science.gov (United States)

    Ghadhanfari, Husain A; Khajah, Hasan M; Monaco, Edward A; Kim, Hyeongil

    2014-10-01

    The tensile strength obtained by conventional postceramic application soldering and laser postceramic welding may require more energy than microwave postceramic soldering, which could provide similar tensile strength values. The purpose of the study was to compare the tensile strength obtained by microwave postceramic soldering, conventional postceramic soldering, and laser postceramic welding. A gold-palladium metal ceramic alloy and gold-based solder were used in this study. Twenty-seven wax specimens were cast in gold-palladium noble metal and divided into 4 groups: laser welding with a specific postfiller noble metal, microwave soldering with a postceramic solder, conventional soldering with the same postceramic solder used in the microwave soldering group, and a nonsectioned control group. All the specimens were heat treated to simulate a normal porcelain sintering sequence. An Instron Universal Testing Machine was used to measure the tensile strength for the 4 groups. The means were analyzed statistically with 1-way ANOVA. The surface and fracture sites of the specimens were subjectively evaluated for fracture type and porosities by using a scanning electron microscope. The mean (standard deviation) ultimate tensile strength values were as follows: nonsectioned control 818 ±30 MPa, microwave 516 ±34 MPa, conventional 454 ±37 MPa, and laser weld 191 ±39 MPa. A 1-way ANOVA showed a significant difference in ultimate tensile strength among the groups (F3,23=334.5; Pgold and palladium noble metals than either conventional soldering or laser welding. Conventional soldering resulted in a higher tensile strength than laser welding. Under the experimental conditions described, either microwave or conventional postceramic soldering would appear to satisfy clinical requirements related to tensile strength. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  18. Tensile properties of machine strength graded timber for glued laminated timber

    DEFF Research Database (Denmark)

    Boström, Lars; Hoffmeyer, Preben; Solli, Kjell-Helge

    1999-01-01

    Special setting values based on tensile properties of Norway spruce are established for four different strength grading machines. The machines included are Computermatic, Cook-Bolinder, Ersson and Dynagrade.The study shows that the yield of timber to be used in tension, such as laminations...... for glulam, may be increased by basing the setting values on test results of the tensile properties rather than using the strength classes definen in EN338....

  19. Direct comparison of the bond strength results of the different test methods: a critical literature review.

    Science.gov (United States)

    Scherrer, Susanne S; Cesar, Paulo F; Swain, Mike V

    2010-02-01

    The goal of this paper is to undertake a literature search collecting all dentin bond strength data obtained for six adhesives with four tests (shear, microshear, tensile and microtensile) and to critically analyze the results with respect to average bond strength, coefficient of variation, mode of failure and product ranking. A PubMed search was carried out for the years between 1998 and 2009 identifying publications on bond strength measurements of resin composite to dentin using four tests: shear, tensile, microshear and microtensile. The six adhesive resins were selected covering three step systems (OptiBond FL, Scotch Bond Multi-Purpose Plus), two-step (Prime & Bond NT, Single Bond, Clearfil SE Bond) and one step (Adper Prompt L Pop). Pooling results from 147 references showed an ongoing high scatter in the bond strength data regardless which adhesive and which bond test was used. Coefficients of variation remained high (20-50%) even with the microbond test. The reported modes of failure for all tests still included high number of cohesive failures. The ranking seemed to be dependant on the test used. The scatter in dentin bond strength data remains regardless which test is used confirming Finite Element Analysis predicting non-uniform stress distributions due to a number of geometrical, loading, material properties and specimens preparation variables. This reopens the question whether, an interfacial fracture mechanics approach to analyze the dentin-adhesive bond is not more appropriate for obtaining better agreement among dentin bond related papers. Copyright 2009 Academy of Dental Materials. All rights reserved.

  20. General and mechanistic optimal relationships for tensile strength of doubly convex tablets under diametrical compression.

    Science.gov (United States)

    Razavi, Sonia M; Gonzalez, Marcial; Cuitiño, Alberto M

    2015-04-30

    We propose a general framework for determining optimal relationships for tensile strength of doubly convex tablets under diametrical compression. This approach is based on the observation that tensile strength is directly proportional to the breaking force and inversely proportional to a non-linear function of geometric parameters and materials properties. This generalization reduces to the analytical expression commonly used for flat faced tablets, i.e., Hertz solution, and to the empirical relationship currently used in the pharmaceutical industry for convex-faced tablets, i.e., Pitt's equation. Under proper parametrization, optimal tensile strength relationship can be determined from experimental results by minimizing a figure of merit of choice. This optimization is performed under the first-order approximation that a flat faced tablet and a doubly curved tablet have the same tensile strength if they have the same relative density and are made of the same powder, under equivalent manufacturing conditions. Furthermore, we provide a set of recommendations and best practices for assessing the performance of optimal tensile strength relationships in general. Based on these guidelines, we identify two new models, namely the general and mechanistic models, which are effective and predictive alternatives to the tensile strength relationship currently used in the pharmaceutical industry. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Prefabricated veneers - bond strengths and ultramorphological analyses.

    Science.gov (United States)

    Perdigão, Jorge; Sezinando, Ana; Muñoz, Miguel A; Luque-Martinez, Issis V; Loguercio, Alessandro D

    2014-04-01

    To measure the microshear bond strengths (μSBS) of composite resin to the intaglio surface of prefabricated indirect veneers and analyze the FE-SEM ultramorphology of the pretreated intaglio surfaces as well as the fracture modes. Three veneer systems (veneer and respective luting material) were used in this study: two prefabricated veneer types, Cerinate One-hour (CER, DenMat) and Componeer (CMP, Coltene), and a laboratory- made veneer, IPS e.max Press (IPS, Ivoclar Vivadent) used as the control. For each group, 10 veneers were used. After delimitation of the bonding area with a double-faced adhesive tape, 0.8-mm-diameter cylinders of composite luting material were bonded to the pretreated intaglio surface. After polymerization, the specimens were fractured in shear mode using the wire-loop method in a universal testing machine. The pretreated intaglio surface of two extra veneers and four fractured specimens per group were morphologically characterized using FE-SEM. CER resulted in statistically lower mean μSBS (7.1 ± 1.2 MPa) than the other two veneer systems, CMP (15.2 ± 2.5 MPa) and IPS (14.7 ± 1.7 MPa) at p veneer systems resulted in greater bond strengths than those of the CER veneer system.

  2. Strength criterion for rocks under compressive-tensile stresses and its application

    Directory of Open Access Journals (Sweden)

    Mingqing You

    2015-08-01

    Full Text Available Estimating in-situ stress with hydraulic borehole fracturing involves tensile strength of rock. Several strength criteria with three parameters result in tensile strengths with great differences, although they may describe the relation between strength of rock and confining pressure with low misfits. The exponential criterion provides acceptable magnitudes of tensile strengths for granites and over-estimates that for other rocks, but the criterion with tension cut-off is applicable to all rocks. The breakdown pressure will be lower than the shut-in pressure during hydraulic borehole fracturing, when the maximum horizontal principal stress is 2 times larger than the minor one; and it is not the peak value in the first cycle, but the point where the slope of pressure-time curve begins to decline.

  3. Non-linear Ultrasonic Bond-Strength Monitor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To date, bond strength is considered one of the ?holy grails? for NDE. Preliminary data indicates that the Luna Nonlinear Ultrasonic Bond Strength (NUBS) monitor...

  4. Halogen light versus LED for bracket bonding: shear bond strength.

    Science.gov (United States)

    Carvalho, Paulo Eduardo Guedes; dos Santos, Valdemir Muzulon; Isber, Hassan; Cotrim-Ferreira, Flávio Augusto

    2013-02-15

    LED light-curing devices seek to provide a cold light activator which allows protocols of material polymerization with shorter duration. The present study aimed to evaluate the shear bond strength of bracket bonding using three types of light-curing devices: One with halogen light (Optilight Plus - Gnatus) and two with LEDs (Optilight CL - Gnatus and Elipar Freelight - 3M/ESPE). Comparing the results by analysis of variance, the Gnatus LED device showed an inferior statistical behavior in relation to other light sources, when activated by a short time. But, when it was used for 40 seconds, the polymerization results were consistent with the other evaluated sources. The device with the best average performance was the halogen light, followed by the 3M/ESPE LED. It was concluded that the LEDs may be indicated in orthodontic practice, as long as a protocol is used for the application of light with the activation time of 40 seconds.

  5. Optimization of Tensile Strength of Phenolic-Glass Compound for Compression Molding Process

    Directory of Open Access Journals (Sweden)

    Hojjat Rajabzadeh

    2015-03-01

    Full Text Available Fiber-reinforced phenolic resins have been widely used in thermal insulation products. Processability and mechanical properties are the two important characteristics of these compounds. In this research, the flow in spiral mold and tensile strength were considered as indicators for processability and mechanical properties, respectively. B-stage curing time, fiber length and silane treatment effects on flow properties and tensile strength were studied. Spiral flow test results showed that B-stage has a significance effect on flow rates optimized at 85°C for 3 h. Under this condition, resin viscosity increased to a suitable level and improved in transferring and dispersing the fibers. Tensile strength was increased by 3.5 h heat treatment and it was dropped beyond the B-stage. Heat treatment beyond this stage weakened the possible attachment of different components together. Silane treatment increased the tensile strength and based on electron microscopy studies there was improved fiber-resin compatibility with better dispersion of the fibers. Although there were improvements observed in fiber dispersion in silane treatment as well as the B-stage curing, but the effect was greater in the latter case, such that treatment by 3.5 h B-stage produced tensile strength by 130% while the silane treatment effect resulted in 30% greater tensile strength. This may imply that for some applications the silane treatment of the fibers is not sufficient and heat treatment could be considered as a substitute. Tensile strength increased with fiber length which was related to the nature of short-fibercomposites, while the load transfer improved with longer fibers.

  6. Effects of Thermal Treatment on Tensile Strength of Laurentian Granite Using Brazilian Test

    Science.gov (United States)

    Yin, Tubing; Li, Xibing; Cao, Wenzhuo; Xia, Kaiwen

    2015-11-01

    The effect of thermal treatment on several physical properties and the tensile strength of Laurentian granite (LG) are measured in this study. Brazilian disc LG specimens are treated at temperatures of up to 850 °C. The physical properties such as grain density, relative volume change per degree, and P-wave velocity are investigated under the effect of heat treatment. The results indicate that both the density and the P-wave velocity decrease with the increase in heating temperature. However, the relative volume change per degree is not sensitive below 450 °C, while a remarkable increase appears from 450 to 850 °C. All cases are explained by the increase in both number and width of the thermally induced microcracks with the heating temperature. Brazilian tests are carried out statically with an MTS hydraulic servo-control testing system and dynamically with a modified split Hopkinson pressure bar (SHPB) system to measure both static and dynamic tensile strength of LG. The relationship between the tensile strength and treatment temperatures shows that static tensile strength decreases with temperature while the dynamic tensile strength first increases and then decreases with a linear increase in the loading rate. However, the increase in dynamic tensile strength with treatment temperatures from 25 to 100 °C is due to slight dilation of the grain boundaries as the initial thermal action, which leads to compaction of rock. When the treatment temperature rises above 450 °C, the quartz phase transition results in increased size of microcracks due to the differential expansion between the quartz grains and other minerals, which is the main cause of the sharp reduction in tensile strength.

  7. [Effects of saliva contamination on bond strength of resin-resin interfaces].

    Science.gov (United States)

    Guo, H J; Gao, C Z; Lin, F; Liu, W; Yue, L

    2017-02-18

    To estimate the bond strength between different resin composite interfaces, and to evaluate the effect of saliva contamination and management with the contamination on the bond strength. Two commercial resin composites containing different types of fillers (AP-X: barium-glass; P60: quartz) were tested in this study. The basic composite blocks were made of AP-X. After wet-ground flatted, the experimental groups were divided into three groups according to the surface treatment: (1)Direct bonding group: the bonding surface was rinsed with distilled water for 20 s, then dried with oil-free air for 20 s; (2)Saliva contamination group: the bonding surface was bathed in saliva for 30 min, then distilled water was rinsed for 20 s and dried with oil-free air for 20 s; (3)Saliva contamination and 75% ethanol wiping group: bonding surface bathed in saliva for 30 min, then wipe the surface with 75% ethanol, distilled water rinse for 20 s and dry with oil-free air for 20 s; The control group was made of the basic composite bulks of AP-X directly bonding with composite P60. Cut each resin block into 1 mm×1 mm×14 mm sticks, observing the micro-structures and detecting the micro-tensile strength of the resin composite interfaces. The bonding strength was measured using micro-tensile tester, then calculated and statistically analyzed by one-way ANOVA. Scanning electronic microscope observation revealed that the control group as well as the direct bonding subgroups, two different resin tags were in good contact with each other. The saliva contamination subgroups had lots of gaps or craters, indicating saliva might have been trapped in the composite buildup and wiping the surface with 75% ethanol had no effect. The micro-tensile bond strength of the control group was (84.07±1.57) MPa and significantly higher than all the other 3 experimental subgroups(Psaliva contamination subgroup was significant lower than the direct bonding subgroup(PSaliva contamination reduced the tensile

  8. High bonding temperatures greatly improve soy adhesive wet strength

    Science.gov (United States)

    Charles R. Frihart; Thomas Coolidge; Chera Mock; Eder Valle

    2016-01-01

    Soy wood adhesive bond strengths reported in different literature studies are difficult to compare because a variety of temperatures and other conditions have been used for the bonding and testing step. Some reports have indicated bond strengths are sensitive to bonding temperature, but the reason(s) for this has not been intensively investigated. Although these prior...

  9. Root tensile strength of 3 typical plant species and their contribution ...

    African Journals Online (AJOL)

    The effect of root reinforcement depends on the morphological characteristics of the root system, the tensile strength of individual roots, the soil-root cohesive strength, and the distribution of the root system in the soil. This research looks into Sasumua Backslope in Kenya, where a great deal of erosion is responsible for ...

  10. Characterization of Optical Fiber Strength Under Applied Tensile Stress and Bending Stress

    Energy Technology Data Exchange (ETDEWEB)

    P.E. Klingsporn

    2011-08-01

    Various types of tensile testing and bend radius tests were conducted on silica core/silica cladding optical fiber of different diameters with different protective buffer coatings, fabricated by different fiber manufacturers. The tensile tests were conducted to determine not only the average fiber strengths at failure, but also the distribution in fracture strengths, as well as the influence of buffer coating on fracture strength. The times-to-failure of fiber subjected to constant applied bending stresses of various magnitudes were measured to provide a database from which failure times of 20 years or more, and the corresponding minimum bend radius, could be extrapolated in a statistically meaningful way. The overall study was done to provide an understanding of optical fiber strength in tensile loading and in applied bending stress as related to applications of optical fiber in various potential coizfgurations for weapons and enhanced surveillance campaigns.

  11. Influence of ceramic surface treatment on shear bond strength of ceramic brackets

    Directory of Open Access Journals (Sweden)

    Tatiana Fernandes Ramos

    2012-01-01

    Full Text Available Objective: To compare four different surface treatment methods and determine which produces adequate bond strength between ceramic brackets and facets of porcelain (feldspathic, and evaluate the Adhesive Remnant Index (ARI scores. Materials and Methods: Ten facets of porcelain specimens with glazed surfaces were used for each group. The specimens were randomly assigned to one of the following treatment conditions of the porcelain surface: (1 no surface treatment (control group, (2 fine diamond bur + orthophosphoric acid gel 37%, (3 hydrofluoric acid (HFL 10%, and (4 HFL 10% + silane. Ceramic brackets were bonded with the adhesive cement Transbond XT. The shear bond strength values were measured on a universal testing machine at a crosshead speed of 0.5 mm/min. Results: There was a significant difference (P<0.05 between the control group and all other groups. There was no significant difference (P<0.05 between treated porcelain surface with diamond bur + orthophosphoric acid gel 37% (4.8 MPa and HFL 10% (6.1 MPa, but the group treated with HFL 10% had clinically acceptable bond strength values. The group treated with HFL 10% + silane (17.5 MPa resulted in a statistically significant higher tensile bond strength (P<0.05. In group 4, 20% of the porcelain facets displayed damage. Conclusion: Etching of the surface with HFL increased the bond strength values. Silane application was recommended to bond a ceramic bracket to the porcelain surface in order to achieve bond strengths that are clinically acceptable.

  12. Bond strength of composite to astringent-contaminated dentin using self-etching adhesives.

    Science.gov (United States)

    O'Keefe, Kathy L; Pinzon, Lilliam M; Rivera, Babette; Powers, John M

    2005-06-01

    To determine the effects of contamination by ferric sulfate and aluminum chloride astringents on the bond strength of composite bonded to superficial dentin using self-etching adhesives. Freshly extracted human teeth were ground to expose superficial dentin and polished to 600 grit. One of three self-etching adhesive systems and restorative composites were bonded to the specimens, with contamination by one of three astringents and five surface conditions (no contamination, moist dentin control; contaminant, air, adhesive; contaminant, water rinse, air, adhesive; contaminant, water rinse, glycolic acid scrub, rinse, adhesive; contaminant, water rinse, chlorhexadine scrub, rinse, adhesive). Composite was bonded to the surfaces in the shape of an inverted, truncated cone (n = 5, 180 specimens total). Specimens were stored in water at 37 degrees C for 24 hours, then de-bonded in tension with a testing machine at a crosshead speed of 0.5 mm/minute. Tensile bond strengths (MPa) were calculated. Means (SD) were compared using analysis of variance. Significant differences (Fisher's PLSD) were found among all variables. SE and ABF had the highest control values, but were affected most by astringent contamination. Ferric sulfate reduced bond strengths the greatest in most cases, and aluminum chloride putty reduced bond strengths the least. Chlorhexadine rinse was most effective in restoring bond strength values.

  13. The diametral tensile strength and hydrostability of polymer-ceramic nano-composite (pcnc) material prototypes

    Science.gov (United States)

    Yepez, Johanna

    Statement of the problem: There is a weak connection between the filler and the resin matrix of dental composites caused primarily by hydrolysis of silane coupling agent, therefore, jeopardizing the mechanical properties of the dental restorations. Purpose: The purpose of this study was to compare the diametral tensile strength (DTS) of a nano-mechanically bonded polymer ceramic nano composite (pcnc) versus the chemically bonding prototype polymer ceramic nano composite (pcnc) fabricated by using hydrolytically stable interphase. Materials and Methods: Composites were made with 60wt % filler, 38% triethyleneglycol dimethacrylate (TEDGMA), 1% camphorquinone (CQ) and 1% 2-(dimethylamino) ethyl methacrylate (DMAEMA). Tests for DTS were performed using a universal testing machine. The disk-shaped specimens were loaded in compression between two supporting plates at a crosshead speed of 0.5 mm/min until fracture. The samples, measuring 3 mm in height and 6 mm in diameter, were produced in a round stainless steel (SS) mold. A total of 144 samples were created. Groups of 48 samples were made for each of three different fillers. Specimens were soaked in artificial saliva at 37° for four time periods, dry(t=0), 1 day, 7 days, 28 days). At the end of each soaking time DTS tests were performed. Results: There where statistically significant differences in the DTS between the filler groups and the soaking times (p=matrix composition and bonding interphase of resin base composites promise improvements of mechanical properties, decreasing the incidence of clinical failure of posterior composite restorations, hence resulting in a more ideal restorative material for use in posterior segment. The results of this investigation showed that the deficiency of hydrostability in dental composites is a detrimental factor in the mechanical behavior. The silanation of the filler particles have a positive influence on the mechanical properties of dental composites but the hydrolysis of the

  14. 830-nm irradiation increases the wound tensile strength in a diabetic murine model.

    Science.gov (United States)

    Stadler, I; Lanzafame, R J; Evans, R; Narayan, V; Dailey, B; Buehner, N; Naim, J O

    2001-01-01

    The purpose of this study was to investigate the effects of low-power laser irradiation on wound healing in genetic diabetes. Female C57BL/Ksj/db/db mice received 2 dorsal 1 cm full-thickness incisions and laser irradiation (830 nm, 79 mW/cm(2), 5.0 J/cm(2)/wound). Daily low-level laser therapy (LLLT) occurred over 0-4 days, 3-7 days, or nonirradiated. On sacrifice at 11 or 23 days, wounds were excised, and tensile strengths were measured and standardized. Nontreated diabetic wound tensile strength was 0.77 +/- 0.22 g/mm(2) and 1.51 +/- 0.13 g/mm(2) at 11 and 23 days. After LLLT, over 0-4 days tensile strength was 1.15 +/- 0.14 g/mm(2) and 2.45 +/- 0.29 g/mm(2) (P = 0.0019). Higher tensile strength at 23 days occurred in the 3- to 7-day group (2.72 +/- 0.56 g/mm(2) LLLT vs. 1.51 +/- 0.13 g/mm(2) nontreated; P laser irradiation at 830 nm significantly enhances cutaneous wound tensile strength in a murine diabetic model. Further investigation of the mechanism of LLLT in primary wound healing is warranted. Copyright 2001 Wiley-Liss, Inc.

  15. Effect of adhesive hydrophobicity on microtensile bond strength of low-shrinkage silorane resin to dentin

    Directory of Open Access Journals (Sweden)

    So-Yeun Cho

    2011-07-01

    Full Text Available Objectives The purpose of this study was to evaluate µTBS (microtensile bond strength of current dentin bonding adhesives which have different hydrophobicity with low-shrinkage silorane resin. Materials and Methods Thirty-six human third molars were used. Middle dentin was exposed. The teeth were randomly assigned to nine experimental groups: Silorane self-etch adhesives (SS, SS + phosphoric acid etching (SS + pa, Adper easy bond (AE, AE + Silorane system bonding (AE + SSb, Clearfil SE bond (CSE, CSE + SSb, All-Bond 2 (AB2, AB2 + SSb, All-Bond 3 (AB3. After adhesive's were applied, the clinical crowns were restored with Filtek LS (3M ESPE. The 0.8 mm × 0.8 mm sticks were submitted to a tensile load using a Micro Tensile Tester (Bisco Inc.. Water sorption was measured to estimate hydrophobicity adhesives. Results µTBS of silorane resin to 5 adhesives: SS, 23.2 MPa; CSE, 19.4 MPa; AB3, 30.3 MPa; AB2 and AE, no bond. Additional layering of SSb: CSE + SSb, 26.2 MPa; AB2 + SSb, 33.9 MPa; AE + SSb, no bond. High value of µTBS was related to cohesive failure. SS showed the lowest water sorption. AE showed the highest solubility. Conclusions The hydrophobicity of adhesive increased, and silorane resin bond-strength was also increased. Additional hydrophobic adhesive layer did not increase the bond-strength to silorane resin except AB2 + SSb. All-Bond 3 showed similar µTBS & water sorption with SS. By these facts, we could reach a conclusion that All-Bond 3 is a competitive adhesive which can replace the Silorane adhesive system

  16. Evaluation on Tensile Strength and Applicability of Tapered Rolled Thread Coupler

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, Jinhwan; Choi, Hyoungsuk; Jung, Chiyoung [Pusan National Univ., Busan (Korea, Republic of); Kim, Taejin [Korea Conformity Laboratories, Busan (Korea, Republic of); Seo, Sanghwan [Sammi Precision Co. Ltd., Ulsan (Korea, Republic of)

    2014-05-15

    Various diameters of reinforcing bars, ASTM A 615 Grade 60 11, 14, and 18, are used for construction of Nuclear Power Plant structures. But due to the large diameter of these rebar, placing rebar is difficult. This study suggests a new tapered rolled thread coupler which have improved workability and fastening force. To evaluate tensile strength and applicability, the tensile test are conducted and static load-carrying capacity of rolled thread coupler are evaluated. In the both tensile tests and column tests, the good agreement of load-carrying capacity are shown. Therefore the proposed tapered rolled thread coupler can be applied to the NPP to replace conventional coupler.

  17. Effect of Dentin Wetness on the Bond Strength of Universal Adhesives

    Directory of Open Access Journals (Sweden)

    An-Na Choi

    2017-10-01

    Full Text Available The effects of dentin wetness on the bond strength and adhesive interface morphology of universal adhesives have been investigated using micro-tensile bond strength (μTBS testing and confocal laser scanning microscopy (CLSM. Seventy-two human third molars were wet ground to expose flat dentin surfaces. They were divided into three groups according to the air-drying time of the dentin surfaces: 0 (without air drying, 5, and 10 s. The dentin surfaces were then treated with three universal adhesives: G-Premio Bond, Single Bond Universal, and All-Bond Universal in self-etch or etch-and-rinse mode. After composite build up, a μTBS test was performed. One additional tooth was prepared for each group by staining the adhesives with 0.01 wt % of Rhodamine B fluorescent dye for CLSM analysis. The data were analyzed statistically using ANOVA and Tukey’s post hoc tests (α = 0.05. Two-way ANOVA showed significant differences among the adhesive systems and dentin moisture conditions. An interaction effect was also observed (p < 0.05. One-way ANOVA showed that All-Bond Universal was the only material influenced by the wetness of the dentin surfaces. Wetness of the dentin surface is a factor influencing the micro-tensile bond strength of universal adhesives.

  18. environmental effects on tensile strength and other mechanical

    African Journals Online (AJOL)

    Dr Obe

    strength) as in aerospace parts subjected to thermal spiking (rapid excursions to high temperatures) with subsequent high strain rates [3 ]. Appropriate quality control procedures and production details are employed to minimize the effects of production related defects which cannot be completely eliminated, as shown by the ...

  19. On the dynamic tensile strength of an FCC metal

    Science.gov (United States)

    Bourne, Neil; Jones, David; Fensin, Saryu; Trujillo, Carl; Martinez, Daniel; Gray, George T., III

    2017-06-01

    The tensile response of polycrystalline metals is often accompanied by the formation of pores within the structure of the material. This large deformation process is broadly identified as progressive with nucleation, growth, coalescence, and failure the physical path taken over very short periods of time. These are well known to be complex processes strongly influenced by microstructure, loading path, and the loading profile, which remains a significant challenge to represent and predict numerically. In a previous study, the influence of loading path on the damage evolution in high-purity tantalum has been presented; in this paper we present complimentary measurement on a pure FCC copper. Samples were shock loaded to three different peak shock stresses using both symmetric impact, and two different composite flyer plate configurations such that upon unloading the three samples displayed nearly identical ``pull-back'' signals as measured via rear-surface velocimetry. The damage evolution in the ``soft'' recovered copper samples was quantified using optical metallography, electron-back-scatter diffraction, and tomography. We shall compare metallurgical observations, velocimetry histories and one dimensional simulations to discuss dynamic failure mechanisms in this metal.

  20. Sealing and dentin bond strength of adhesive systems in selected areas of perfused teeth.

    Science.gov (United States)

    Escribano, N; Del-Nero, O; de la Macorra, J C

    2001-03-01

    (1) Test the sealing capacity and tensile strength of various adhesive systems: Scotch Bond 1 (Single Bond in USA)(SB1)+Z100, Syntac Sprint (SYN)+Tetric Ceram, Prime and Bond 2.1 (PB21)+TPH Spectrum, F2000 (Adhesive+Compomer) (F2000) and Optibond Solo (OPT)+Prodigy, to perfused teeth (30 cm distilled H2O), in select areas. (2) Determine the relationship between sealing ability and size of adhesive area (BA) with tensile strength (TS). Segments of human third molars (n=67) sealed with amalgam on their coronal side were connected to a perfusion system (30 cm distilled H2O), to measure the basal permeability. Access cavities were drilled through the amalgam to expose dentin (area range: 8.7-20.8 mm2) and measure the permeability of that area. Cavities were sealed with one of the test materials and permeability measured prior to tensile testing. The percentage of decrease in permeability (PPD) that occurred with the different combinations of materials was also measured. RESULTS. TENSILE STRENGTH: there were no statistically significant differences among groups. PERMEABILITY: ANOVA showed that there were statistically significant differences in the mean % decrease in permeability (PPD) among groups (p=0.018). Student-Newman-Keuls test (pvariables: a linear correlation was found defined by the formula TS=7.47+0.008 x PPD-0.23 x BA, with a significance of the model p=0.0097. None of the materials studied reduced permeability up to 100%. They all produced low tensile bond strengths (maximum mean value of groups: 5.51 MPa (OPT)).

  1. Prediction of Splitting Tensile Strength of Concrete Containing Zeolite and Diatomite by ANN

    Directory of Open Access Journals (Sweden)

    E. Gülbandılar

    2017-01-01

    Full Text Available This study was designed to investigate with two different artificial neural network (ANN prediction model for the behavior of concrete containing zeolite and diatomite. For purpose of constructing this model, 7 different mixes with 63 specimens of the 28, 56 and 90 days splitting tensile strength experimental results of concrete containing zeolite, diatomite, both zeolite and diatomite used in training and testing for ANN systems was gathered from the tests. The data used in the ANN models are arranged in a format of seven input parameters that cover the age of samples, Portland cement, zeolite, diatomite, aggregate, water and hyper plasticizer and an output parameter which is splitting tensile strength of concrete. In the model, the training and testing results have shown that two different ANN systems have strong potential as a feasible tool for predicting 28, 56 and 90 days the splitting tensile strength of concrete containing zeolite and diatomite.

  2. Tensile Adhesion Strength of Biomass Ash Deposits: Effect of the Temperature Gradient and Ash Chemistry

    DEFF Research Database (Denmark)

    Laxminarayan, Yashasvi; Nair, Akhilesh Balachandran; Jensen, Peter Arendt

    2018-01-01

    Replacing coal with biomass in power plants is a viable option for reducing net CO2 emissions and combating climate change. However, biomass combustion in boilers may exacerbate problems related to ash deposition and corrosion, demanding effective deposit removal. The tensile adhesion strength...... the deposits. After sintering, the deposits were removed using an electrically controlled arm and the corresponding tensile adhesion strength was measured.The influence of the flue gas temperature (500–700 °C), steel surface temperature (500–650 °C), and deposit composition were investigated. The results...... revealed that increasing the flue gas temperature as well as the steel surface temperature led to a sharp increase in the tensile adhesion strength of the model deposits. The sharp increase was typically observed near the melting temperature (or deformation temperature) of the investigated model deposits...

  3. Effect of preoxidation on the bond strength of titanium and porcelain.

    Science.gov (United States)

    Mahale, K M; Nagda, S J

    2014-06-01

    The purpose of this study was to investigate the effect of preoxidation on porcelain titanium- bond strength and the effect of paste bonder (adhesive) on the titanium porcelain bond strength. 11 specimens of commercially pure titanium (26 x 7 x 3 mm) were prepared by different heat treatments in programmable dental furnace. Identification of the oxides formed on the metal surface was conducted with an X-Ray diffractometer with CuKalpha radiation. Vickers hardness numbers were determine. Additional 50 specimens of commercially pure titanium were used to bond with low fusing porcelain. The bond strength was measured in a universal testing machine. X-ray diffraction analysis of the surface of pure titanium revealed that the relative peak intensity of alpha -Ti decreased and that of TiO2 increased with increasing firing temperature. The Vickers hardness number decreased initially as the temperature increased but it increased remarkably above 900 degrees C & was harder in air than vacuum. The tensile shear bond strength was highest in the green stage i.e. without preoxidation of metal, and decreased above 900 degrees C, and was the lowest in the group without paste bonder application. The difference in bond strengths was statistically highly significant for all groups. Preoxidation under vacuum before porcelain firing can effectively improve bonding. The adhesive provided with the low fusing porcelain helps in the bond between titanium & porcelain.

  4. TENSILE DEFORMATION OF HIGH-STRENGTH AND HIGH MODULUS POLYETHYLENE FIBERS

    NARCIS (Netherlands)

    VANDERWERFF, H; PENNINGS, AJ

    The influence of tensile deformation on gel-spun and hot-drawn ultrahigh molecular weight polyethylene fibers has been investigated. In high modulus polyethylene fibers no deformation energy is used to break chemical bonds during deformation, and flow is predominantly present next to elastic

  5. Push-out bond strengths of two fiber post types bonded with different dentin bonding agents.

    Science.gov (United States)

    Topcu, Fulya Toksoy; Erdemir, Ugur; Sahinkesen, Gunes; Mumcu, Emre; Yildiz, Esra; Uslan, Ibrahim

    2010-05-01

    The aim of this study was to evaluate the regional push-out bond strengths for two fiber-reinforced post types using three different dentin bonding agents. Sixty single-rooted extracted human first premolar teeth were sectioned below the cemento-enamel junction, and the roots were endodontically treated. Following standardized post space preparations, the roots were divided into two fiber-post groups (Glassix and Carbopost), and further divided into three subgroups of 10 specimens each for the bonding systems self-etching dentin bonding agents (Clearfil SE Bond and Optibond all-in-one), and total-etching dentin bonding agent (XP Bond). A dual-cure resin luting cement (Maxcem) was then placed in the post spaces and posts were then seated into the root canals polymerized through the cervical portion. The roots were then cut into 3-mm thick sections. Push-out tests were performed at a crosshead speed of 0.5 mm/min. The data were analyzed with multivariate ANOVA (alpha = 0.05). The morphology of interface between different dentin bonding agents from the cervical sections were analyzed with SEM. Glass fiber-reinforced posts demonstrated significantly higher push-out bond strengths than carbon fiber-reinforced posts (p dentin adhesive Clearfil SE Bond and total-etching dentin adhesive XP Bond demonstrated similar bond strengths values and this was significantly higher compared with the Optibond all-in-one in cervical root canal region. In conclusion, in all root segments, the glass fiber-reinforced posts provided significantly increased post retention than the carbon fiber-reinforced posts, regardless of the adhesive used. (c) 2010 Wiley Periodicals, Inc.

  6. Effect of Silver Nano-particles on Tensile Strength of Acrylic Resins

    Directory of Open Access Journals (Sweden)

    Tahereh Ghaffari

    2015-03-01

    Full Text Available Background and aims. Polymethyl methacrylate (PMMA is widely used for the fabrication of removable prostheses. Silver nano-particles (AgNps have been added to PMMA because of their antimicrobial properties, but their effect on the mechanical properties of PMMA is unknown. Theaim of this study was to investigate the effects of AgNps on the tensile strength of PMMA. Materials and methods. For this study, 12 specimens were prepared and divided into two groups. Group 1 included PMMA without AgNps and group 2 included PMMA mixed with 5 wt% of AgNps. Tensile strength of the specimens was measured by Zwick Z100 apparatus. Statistical analysis was carried out by SPSS using t-test. Statistical significance was defined at P<0.05. Results. This study showed that the mean tensile strengthof PMMA in group 2 was significantly lower than that in group 1. Therefore, the tensile strength decreased significantly after incorporation of silver nano-particles. Conclusion. Within the limitations of this study, tensile strength of acrylic resin specimens was influenced by silver nano-particles.

  7. TENSILE STRENGTH OF CIRCULAR FLAT AND CONVEX-FACED AVICEL PH102 TABLETS

    Directory of Open Access Journals (Sweden)

    I.HARIRIAN

    1999-09-01

    Full Text Available The mechanical properties of flat and convex-faced circular tablets made from a size fraction of microcrystalline cellulose (Avicel PH102, compacted under control conditions of pressures of 20 and 112 MPa have been assessed in term of tensile strength. The calculation of tensile strength (at, for flat-faced tablets was determined from the load (P in diametral compression test as described by Fell & Newton ot = 2P/ (7tDt. The material tensile strength of convex-faced tablets calculated from the observed fraction loads obtained in diametral compression testing, based on the equation derived by Pitt et al at= 10P/ [TTD2 (2.84I/D - 0.126t/W+ 3.15W/D + 0.01"1 ], where P is the fracture load, D is the tablet diameter, t is the overall tablet thickness and W is the central cylinder thickness. By comparing the tensile strength values of convex-faced tablets using porosity, tensile stress, and compaction pressure values, an optimum face-curvature in normal to unity range (D/R=0.67-1.0 and an optimum cylinder length of W/D=0.3, were found to be necessary for producing the overall strongest tablets. These optimum values varies with the formation pressure.

  8. Experimental Study On The Effect Of Micro-Cracks On Brazilian Tensile Strength

    Science.gov (United States)

    Wang, Xiangyu

    2015-12-01

    For coal mine ground control issues, it is necessary to propose a failure criteria accounting for the transversely isotropic behaviors of rocks. Hence, it is very helpful to provide experimental data for the validation of the failure criteria. In this paper, the method for preparing transversely isotropic specimens and the scheme of the Brazilian tensile strength test are presented. Results obtained from Brazilian split tests under dry and water-saturated conditions reflect the effect of the development direction β of the structural plane, such as the bedding fissure, on the tensile strength, ultimate displacement, failure mode, and the whole splitting process. The results show that the tensile strength decreases linearly with increasing β. The softening coefficient of the tensile strength shows a sinusoidal function. The values of the slope and inflection point for the curve vary at the different stages of the Brazilian test. The failure mode of the rock specimen presented in this paper generally coincides with the standard Brazilian splitting failure mode. Based on the test results, the major influencing factors for the Brazilian splitting strength are analyzed and a mathematical model for solving the Brazilian splitting strength is proposed. The findings in this paper would greatly benefit the coal mine ground control studies when the surrounding rocks of interest show severe transversely isotropic behaviors.

  9. Effect of Dentin Wetness on the Bond Strength of Universal Adhesives

    OpenAIRE

    An-Na Choi; Ji-Hye Lee; Sung-Ae Son; Kyoung-Hwa Jung; Yong Hoon Kwon; Jeong-Kil Park

    2017-01-01

    The effects of dentin wetness on the bond strength and adhesive interface morphology of universal adhesives have been investigated using micro-tensile bond strength (μTBS) testing and confocal laser scanning microscopy (CLSM). Seventy-two human third molars were wet ground to expose flat dentin surfaces. They were divided into three groups according to the air-drying time of the dentin surfaces: 0 (without air drying), 5, and 10 s. The dentin surfaces were then treated with three universal ad...

  10. SIZE EFFECTS IN THE TENSILE STRENGTH OF UNIDIRECTIONAL FIBER COMPOSITES

    Energy Technology Data Exchange (ETDEWEB)

    M. SIVASAMBU; ET AL

    1999-08-01

    Monte Carlo simulation and theoretical modeling are used to study the statistical failure modes in unidirectional composites consisting of elastic fibers in an elastic matrix. Both linear and hexagonal fiber arrays are considered, forming 2D and 3D composites, respectively. Failure is idealized using the chain-of-bundles model in terms of {delta}-bundles of length {delta}, which is the length-scale of fiber load transfer. Within each {delta}-bundle, fiber load redistribution is determined by local load-sharing models that approximate the in-plane fiber load redistribution from planar break clusters as predicted from 2D and 3D shear-lag models. As a result these models are 1D and 2D, respectively. Fiber elements have random strengths following either the Weibull or the power-law distribution with shape and scale parameters {rho} and {sigma}{sub {delta}}, respectively. Simulations of {delta}-bundle failure, reveal two regimes. When fiber strength variability is low (roughly {rho} > 2) the dominant failure mode is by growing clusters of fiber breaks up to instability. When this variability is high (roughly 0 < {rho} < 1) cluster formation is suppressed by a dispersed fiber failure mode. For these two cases, closed-form approximations to the strength distribution of a {delta}-bundle are developed under the local load-sharing model and an equal load-sharing model of Daniels, respectively. The results compare favorably with simulations on {delta}-bundles with up to 1500 fibers. The location of the transition in terms of {rho} is affected by the upper tail properties of the fiber strength distributions as well as the number of fibers.

  11. Study of root tensile strength of softwood and hardwood tree species: Implications for slope stability

    Science.gov (United States)

    Esmaiili, Marzieh; Abdi, Ehsan; Jafary, Mohammad; Majnounian, Baris

    2017-04-01

    Landslides are known as one of the major natural hazards and often incurring economics and human life losses. The role of tree roots in slope stability is very important, especially when human lives and infrastructure are at risk. The anchorage of roots and improvement of slope stability mainly depend on specific properties of root network systems, such as tensile strength. These properties of the roots which govern the degree of reinforcement are different among tree species. Although, many studies have been conducted about plant biotechnical properties of species, yet there is lack of knowledge on comparing root systems of softwood and hardwood tree species for similar site conditions. Therefore this study was conducted to assess the tensile strength of the root system of Picea abies (softwood species) and Fraxinus excelsior (hardwood species) planted on two forested hillslopes. To this aim, single root specimens were sampled for each species and their tensile strength were then measured in laboratory using a computer controlled Instron Universal Testing Machine. According to the results root tensile strength tends to decrease with diameter according to a power law for both species. Based on analysis of covariance (ANCOVA), a significant difference has been observed in the tensile strength between the two studied species. Also the results showed that the value of mean root tensile strength for Picea abies (19.31 ± 2.64 MPa) was much more than that of Fraxinus excelsior (16.98 ± 1.01 MPa) within all root diameter classes. The data presented in this study may expand the knowledge of biotechnical properties of Picea abies and Fraxinus excelsior, as biomaterial for soil bioengineering.

  12. Mechanical properties and bond strength of glass-ionomer cements.

    Science.gov (United States)

    Pereira, Lúcia Coelho; Nunes, Margareth Calvo Pessutti; Dibb, Regina Guenka Palma; Powers, John M; Roulet, Jean-François; Navarro, Maria Fidela de Lima

    2002-01-01

    The objective of this study was to evaluate the mechanical properties and bond strength of glass-ionomer cements (GICs) and resin-modified GICs (RM-GICs) that are indicated as restorative materials for the Atraumatic Restorative Treatment (ART) technique. Fifteen disk specimens for the diametral tensile strength (DTS) test and fifteen cylindrical specimens for the compressive strength (CS) test were made of each GIC: Ketac-Fil, Ketac-Molar (ESPE), Fuji IX and Fuji PLUS (GC). Forty human molars were sectioned and embedded in resin with either buccal or lingual surfaces exposed for the tensile bond strength (TBS) test. The surface was ground until a flattened area of enamel or dentin was obtained. After conditioning, inverted truncated cones of GICs were prepared on the flat tooth surfaces. The powder:liquid ratio of Fuji PLUS was adjusted for restorative purposes. Prior to testing, specimens were stored for 24 h (TBS test) and for 1 h, 24 h, and 7 days (CS and DTS tests) in deionized water at 37 degrees C. They were then loaded at a crosshead speed of 1.0 mm/min for CS and 0.5 mm/min for DTS and TBS tests until failure occurred. The data were submitted to two-way ANOVA at 0.05 level of significance, followed by a Tukey-Kramer test for multiple comparisons. The mean CS values ranged from 90.27 to 170.73 MPa and DTS means from 6.21 to 22.32, with test periods from 1 h to 7 days. The means for TBS ranged from 4.90 to 11.36 MPa and from 2.52 to 5.55 MPa in enamel and dentin, respectively. No differences were found between materials with the CS test except at 1 hour. The resin-modified GIC (RM-GIC) had the highest DTS, with no changes between the test periods, and the highest TBS for both enamel and dentin. Among the GICs tested, RM-GIC showed higher values of DTS and TBS.

  13. Indirect versus direct bonding--a shear bond strength comparison: an in vitro study.

    Science.gov (United States)

    Swetha, M; Pai, Vinaya S; Sanjay, N; Nandini, S

    2011-07-01

    The process of bonding orthodontic appliances to the enamel surface of the teeth has come to the forefront as a major improvement in bonding techniques. The purpose of this study is to compare the shear bond strength of stainless steel orthodontic brackets bonded using conventional direct bonding and indirect bonding as described by Thomas. Forty sound human premolars were divided into two groups of 20 each. Group I samples were bonded directly on the tooth surface using concise two paste adhesive system after etching and drying. Group II samples were bonded indirectly on the tooth surface according to Thomas indirect bonding technique using concise two paste adhesive system. The stored specimen was tested for shear bond strength in an Instron universal testing machine at a crosshead speed of 0.5 mm/minute. Data obtained were subjected to statistical analysis. The results showed that there was no statistically significant difference in the shear bond strength between direct and indirect bonding techniques. Chi-square test showed that there were significant differences among the adhesive remnant index scores between direct and indirect bonding groups. In vitro shear bond strength comparison between direct and indirect-bonded attachments showed no significant difference between the two groups. Bond strength obtained with Thomas indirect bonding technique was comparable with direct bonding technique. Thomas indirect bonding technique can be used for bonding of the posterior teeth, where the risk of moisture contamination is high during bonding.

  14. Effect of construction joints on the splitting tensile strength of concrete

    Directory of Open Access Journals (Sweden)

    Nagib N. Gerges

    2015-12-01

    The results suggest that the reduction in the splitting tensile strength in the presence of a construction joint is not as much as most engineers tend to believe. Due to that belief, most engineers tend to overdesign for steel reinforcement at those joints to compensate for this reduction. The objective of the study is to better the understanding of the effects of a construction joint on the splitting tensile strength. Thus provide an empirical equation to assist engineers in their design calculations, therefore reducing the amount of steel reinforcement at the construction joints. Thus also leading to cost saving on projects.

  15. Effects of direct and indirect bonding techniques on bond strength and microleakage after thermocycling

    National Research Council Canada - National Science Library

    Fırat, Öztürk; Babacan, Hasan; Nalçacı, Ruhi; Kuştarcı, Alper

    2009-01-01

    The purpose of this study was to compare the shear bond strength (SBS) of brackets and microleakage of a tooth-adhesive-bracket complex bonded with a direct and an indirect bonding technique after thermocycling...

  16. Comparison of the Tensile, Creep, and Rupture Strength Properties of Stoichiometric SiC Fibers

    Science.gov (United States)

    Yun, H. M.; DiCarlo, J. A.

    1999-01-01

    Tensile strength, creep strength, and rupture strength properties were measured for the following types of polymer-derived stoichiometric SiC fibers: Hi-Nicalon Type S from Nippon Carbon, Tyranno SA from Ube, and Sylramic from Dow Corning. Also included in this study were an earlier version of the SA fiber plus two recent developmental versions of the Sylramic fiber. The tensile strength measurements were made at room temperature on as-received fibers and on fibers after high-temperature inert exposure. The creep-rupture property data were obtained at 1400 deg C in air as well as, argon. Some fiber types showed strong effects of environment on their strength properties. These results are compared and discussed in terms of underlying mechanisms and implications for ceramic composites.

  17. Direct Tensile Strength and Characteristics of Dentin Restored with All-Ceramic, Resin-Composite, and Cast Metal Prostheses Cemented with Resin Adhesives

    Directory of Open Access Journals (Sweden)

    Morakot Piemjai

    2015-01-01

    Full Text Available A dentin-cement-prosthesis complex restored with either all-porcelain, cured resin-composite, or cast base metal alloy and cemented with either of the different resin cements was trimmed into a mini-dumbbell shape for tensile testing. The fractured surfaces and characterization of the dentin-cement interface of bonded specimens were investigated using a Scanning Electron Microscope. A significantly higher tensile strength of all-porcelain (12.5 ± 2.2 MPa than that of cast metal (9.2 ± 3.5 MPa restorations was revealed with cohesive failure in the cement and failure at the prosthesis-cement interface in Super-Bond C&B group. No significant difference in tensile strength was found among the types of restorations using the other three cements with adhesive failure on the dentin side and cohesive failure in the cured resin. SEM micrographs demonstrated the consistent hybridized dentin in Super-Bond C&B specimens that could resist degradation when immersed in hydrochloric acid followed by NaOCl solutions whereas a detached and degraded interfacial layer was found for the other cements. The results suggest that when complete hybridization of resin into dentin occurs tensile strength at the dentin-cement is higher than at the cement-prosthesis interfaces. The impermeable hybridized dentin can protect the underlying dentin and pulp from acid demineralization, even if detachment of the prosthesis has occurred.

  18. Direct Tensile Strength and Characteristics of Dentin Restored with All-Ceramic, Resin-Composite, and Cast Metal Prostheses Cemented with Resin Adhesives.

    Science.gov (United States)

    Piemjai, Morakot; Nakabayashi, Nobuo

    2015-01-01

    A dentin-cement-prosthesis complex restored with either all-porcelain, cured resin-composite, or cast base metal alloy and cemented with either of the different resin cements was trimmed into a mini-dumbbell shape for tensile testing. The fractured surfaces and characterization of the dentin-cement interface of bonded specimens were investigated using a Scanning Electron Microscope. A significantly higher tensile strength of all-porcelain (12.5 ± 2.2 MPa) than that of cast metal (9.2 ± 3.5 MPa) restorations was revealed with cohesive failure in the cement and failure at the prosthesis-cement interface in Super-Bond C&B group. No significant difference in tensile strength was found among the types of restorations using the other three cements with adhesive failure on the dentin side and cohesive failure in the cured resin. SEM micrographs demonstrated the consistent hybridized dentin in Super-Bond C&B specimens that could resist degradation when immersed in hydrochloric acid followed by NaOCl solutions whereas a detached and degraded interfacial layer was found for the other cements. The results suggest that when complete hybridization of resin into dentin occurs tensile strength at the dentin-cement is higher than at the cement-prosthesis interfaces. The impermeable hybridized dentin can protect the underlying dentin and pulp from acid demineralization, even if detachment of the prosthesis has occurred.

  19. Structural basis of the tensile strength of protein complexes mediating cell adhesion

    Science.gov (United States)

    Bayas, Marco Vinicio

    This study explores the behaviour of adhesive complexes of cell adhesion molecules undergoing forced detachment. Molecular-forces measurements combined with Steered Molecular Dynamic (SMD) simulations were used to investigate the mechanical response of the CD2 C58 and hemophilic C-cadherin bonds. The CD2-CD58 adhesive complex, important for the adaptive immune response, contains several salt-bridges in the adhesive interface. SMD simulations showed that these inter-protein salt bridges contribute independently to the tensile strength of the complex. Consistent with this, force measurements with the Surface Force Apparatus (SFA) demonstrated that the elimination of single salt bridges weakens the bond. The corresponding loss in adhesion energy of the CD2-CD58 complex correlates with the importance of the salt bridges observed in the simulations. These findings correlate closely with the effect of the elimination of single salt bridges observed in cell aggregation assays and binding measurements. On the other hand, the hemophilic C-cadherin interaction determines specific cell-cell adhesion during development in Xenopus laevis . Single molecule force spectroscopy was used to characterize the multiple bound states between C-cadherin ectodomains. The experiments showed two short-lived bound states associated with the two outermost ectodomains and two long-lived states associated with the full ectodomain. It is likely that the two short-lived states are involved in the specificity of the interaction since previous studies showed that the corresponding states in E-cadherin have different lifetimes. In addition, SMD simulations of the forced dissociation of the strand dieter of C-cadherin suggested a mechanism for the specificity of cadherin interactions.

  20. Bond strength versus dentine structure: a modelling approach.

    Science.gov (United States)

    Pashley, D H; Ciucchi, B; Sano, H; Carvalho, R M; Russell, C M

    1995-12-01

    Bond strengths of a hypothetical hydrophilic dentine-bonding agent were calculated as a function of dentine depth and resin strength to evaluate the importance of several variables in a simple model. The tested hypothesis was that the total bond strength was the sum of the strengths of resin tags, hybrid layer and surface adhesion. Each of these three variables has a range of values that can influence its relative contribution. The resulting calculations indicate the potential for higher bond strengths to deep dentine than to superficial dentine in non-vital dentine and the importance of resin strength in the development of strong bonds. Comparison of the calculated bonds with published values indicated that they were within the same order of magnitude. Such theoretical modelling of dentine bonding can identify the relative importance of variables involved in the substrate, resins and surface adhesion.

  1. Strength and leak testing of plasma activated bonded interfaces

    DEFF Research Database (Denmark)

    Visser, M.M.; Weichel, Steen; Reus, Roger De

    2002-01-01

    on detection of changes in membrane deflections. The detection limit for leak was 8E-13 mbar l/s. For comparison, strength and leak tests were also performed with regular fusion bonded wafers annealed at 1100 degreesC. The PAB was found to withstand post-processing steps such as RCA cleaning, 24 h in de......Bond strength and hermeticity of plasma activated bonded (PAB) Si-Si interfaces are reported. Bonding of 100 mm Si(1 0 0) wafers was performed. An average bond strength of 9.0+/-3.9 MPa was achieved without performing any annealing steps. Cavities bonded in vacuum were found to be hermetic based...

  2. Avaliação in vitro da força de união, através de teste de tração, de porcelana feldspática com diversos tratamentos superficiais à resina composta In vitro evaluation of the bonding strength of the composite resin to feldspathic porcelain with several surface treatments, applying a tensile strength test

    Directory of Open Access Journals (Sweden)

    Américo Mendes CARNEIRO JUNIOR

    1999-07-01

    every failure demands the restoration of the material: the possibility of a repair exists with compounded resin. This study proposed to evaluate in vitro the bonding strength of the composite resin to feldspathic porcelain with several surface treatments: roughened with diamond burs or sandblasted with aluminum oxide of 50 micra, isolated or associatedly etched with phosphoric acid for 15 seconds, or with hydrofluoric acid for 1 or 4 minutes. All the specimens were previously regularized with 220-grit silicon carbide paper. After the superficial treatments, they received the adhesive system for porcelain, Scotchbond Multi-Purpose Dental Plus Adhesive System (3M. After making the union with the composed resin (Restorative Z100, 3M, they were stored in distilled water at 37ºC, for 7 days, followed by thermocycling (600 cycles of 1 minute, between 5 and 55ºC, and submitted to a tensile strength test. With the obtained results, the conclusion was that with all the proposed treatments an improvement happened in the resistance of the tensile bonding strength (when compared to those observed in the group control without any superficial treatment. The sandblasting produced a better resistance than the roughening with a diamond bur; but, when associated to the etching with any of the selected acids, independent of the time of application, there was no statistical difference among those treatments.

  3. Correlation of high-speed tensile strength with collagen content in control and lathyritic rat skin.

    Science.gov (United States)

    Dombi, G W; Haut, R C; Sullivan, W G

    1993-01-01

    Severity of lacerative skin injury depends on the applied load and the resistance of the tissue. At low (static) rates of loading there is a high degree of correlation between skin tensile strength and the degree of collagen crosslinking, with little added strength due to collagen interactions with the glycosaminoglycan matrix. We examined the effects of high (ballistic) rates of loading in order to determine the contributions to strength made by both the degree of collagen crosslinking and the collagen-matrix interaction. Tensile failure experiments were conducted using the dorsal skin of rats 1.5-6 months of age. Test specimen orientations were cut parallel and transverse to the body axis at cephalad and caudad locations on the dorsum. Tensile strength was measured at nominal strain rates of 30%/sec (low speed) and 6000%/sec (high speed) using both control and lathyrogen fed rats. Biochemical analyses were conducted to determine the amount of total and crosslinked (insoluble) collagen. In low-speed tests, there was a significant correlation (r > or = 0.900) between collagen content and skin tensile strength measured both transverse and parallel to the spine. The degree of correlation was higher with insoluble (r = 0.973) collagen content than with total (r = 0.901) collagen. The effect of a lathyrogen diet produced a significant (P collagen content (r > or = 0.858).(ABSTRACT TRUNCATED AT 250 WORDS)

  4. High efficient and continuous surface modification of carbon fibers with improved tensile strength and interfacial adhesion

    Science.gov (United States)

    Sun, Jingfeng; Zhao, Feng; Yao, Yue; Jin, Zhen; Liu, Xu; Huang, Yudong

    2017-08-01

    Most of the surface modification technologies for carbon fibers, no matter in laboratory scale or for commercial manufacture, are accompanied by a simultaneous decrease in tensile strength. In this paper, a feasible and high efficient strategy for carbon fiber treatment which could obviously improve both tensile strength and interfacial adhesion was proposed. Continuously moving carbon fibers were treated with atmospheric helium plasma for 1 min, followed by a 5 min pyrolytic carbon deposition using ethanol as precursor at 800 °C. The effects of the new approach were characterized by SEM, AFM, nanoindentation, XPS, Raman, wettability analysis, single fiber tensile strength testing and single fiber pull-out testing. After modification, pyrolytic carbon coating was deposited on the fiber surface uniformly, and the roughness and surface energy increased significantly. The single fiber tensile testing results indicate that the resulting fiber strength increased 15.7%, rising from 3.13 to 3.62 GPa. Meanwhile, the interfacial shear strength of its epoxy composites increased from 65.3 to 83.5 MPa. The comparative studies of carbon fibers modified with commercial anodic oxidation and sizing were also carried out. The results demonstrate that the new method can be utilized in the carbon fiber manufacture process and is more efficient than the traditional approaches.

  5. Effect of Gap Distance on Tensile Strength of Preceramic Base Metal Solder Joints

    Directory of Open Access Journals (Sweden)

    Farnaz Fattahi

    2011-09-01

    Full Text Available Background and aims. In order to fabricate prostheses with high accuracy and durability, soldering techniques have been introduced to clinical dentistry. However, these prostheses always fail at their solder joints. The purpose of this study was to evaluate the effect of gap distance on the tensile strength of base metal solder joints. Materials and methods. Based on ADA/ISO 9693 specifications for tensile test, 40 specimens were fabricated from a Ni-Cr alloy and cut at the midpoint of 3-mm diameter bar and placed at desired positions by a specially designed device. The specimens were divided into four groups of 10 samples according to the desired solder gap distance: Group1: 0.1mm; Group2: 0.25mm; Group3: 0.5mm; and Group4: 0.75mm. After soldering, specimens were tested for tensile strength by a universal testing machine at a cross-head speed of 0.5mm/min with a preload of 10N. Results. The mean tensile strength values of the groups were 162, 307.8, 206.1 and 336.7 MPa, respectively. The group with 0.75-mm gap had the highest and the group with 0.1-mm gap had the lowest tensile strength. Bonferroni test showed that Group1 and Group4 had statistically different values (P=0.023, but the differences between other groups were not significant at a significance level of 0.05. Conclusion. There was no direct relationship between increasing soldering gap distance and tensile strength of the solder joints.

  6. The bond strength of different tray adhesives on vinyl polysiloxane to two tray materials: an in vitro study.

    Science.gov (United States)

    Ashwini, B L; Manjunath, S; Mathew, K Xavier

    2014-03-01

    There has been no established chemical bonding between custom tray resin and the elastomeric impression materials without the use of manufacturer's recommended specific tray adhesive. The present study was aimed to compare the bond strength of the manufacturer recommended tray adhesives with the universal tray adhesives using the medium body consistency vinyl polysiloxane (VPS) material and custom tray made of autopolymerising resin and visible light cure (VLC) resin. A total 90 cubicle specimens of autopolymerising resin and 90 specimens of VLC resin were tested for its tensile bond strength. Effectiveness of universal tray adhesive was compared with manufactured tray adhesive. Each of these specimens was then subjected to tensile load in hounsefield universal testing machine at a cross head speed of 5 mm/min and the results were compared and evaluated using one way analysis of variance and post hoc Tuckey's test. Analysis of bond strength revealed that the universal tray adhesive showed better strength and was statiscally significant when compared to the manufacture supplied tray adhesive. Comparison between both the groups, VLC resin showed better bond strength as compared to autopolymerizing resin. Universal tray adhesive had better tensile bond strength than the manufacturers recommended tray adhesive with the medium body viscosity VPS impression material for both autopolymerising and VLC tray resin.

  7. Examining the influence of injection speed and mould temperature on the tensile strength of polypropylene and ABS

    DEFF Research Database (Denmark)

    Aarøe, Esben Raahede; Blaimschein, Karl Stephan; Deker, Lasse

    This report is the final task of course “41738 Experimental Plastics Technology” in the three weeks period of June 2009 at DTU, IPL. The aim of this project has been to investigate the ultimate tensile strength behaviour of two different polymers, with different structural composition, by varying...... specimens. After production and tensile testing the specimens were examined with a microscope to underpin conclusions from the tensile test data. It was experienced that the injection speed in general increased the the tensile strength by orienting the polymeric-chains lengthwise in the specimens and thus...... increasing the strength in the tensile strength. This observation was however disturbed by the test results for small ABS specimens where an increased injection speed in general meant lower tensile strength, which though can be explained by the extremely rapid cooling that the small specimens in general were...

  8. Shear bond strength of metallic and ceramic brackets using color change adhesives

    Directory of Open Access Journals (Sweden)

    Aisha de Souza Gomes Stumpf

    2013-04-01

    Full Text Available OBJECTIVE: To determine the shear bond strength of orthodontic brackets using color change adhesives that are supposed to aid in removing excess of bonding material and compare them to a traditional adhesive. METHODS: Ninety metallic and ninety ceramic brackets were bonded to bovine incisors using two color change adhesives and a regular one. A tensile stress was applied by a universal testing machine. The teeth were observed in a microscope after debonding in order to determine the Adhesive Remnant Index (ARI. RESULTS: The statistical analysis (ANOVA, Tukey, and Kruskall-Wallis tests demonstrated that the mean bond strength presented no difference when metallic and ceramic brackets were compared but the bond resistance values were significantly different for the three adhesives used. The most common ARI outcome was the entire adhesive remaining on the enamel. CONCLUSIONS: The bond strength was similar for metallic and ceramic brackets when the same adhesive system was used. ARI scores demonstrated that bonding with these adhesives is safe even when ceramic brackets were used. On the other hand, bond strength was too low for orthodontic purposes when Ortho Lite Cure was used.

  9. High-temperature tensile strength of near-stoichiometric SiC/SiC composites

    Science.gov (United States)

    Hironaka, K.; Nozawa, T.; Hinoki, T.; Igawa, N.; Katoh, Y.; Snead, L. L.; Kohyama, A.

    2002-12-01

    In an attempt to characterize mechanical properties of near-stoichiometric SiC/SiC composites, tensile tests were conducted at room temperature in air and at elevated temperature under mild oxidizing gases atmosphere. SiC/SiC composites were fabricated by forced-flow chemical vapor infiltration method using two-dimensional fabrics of carbon coated near-stoichiometric Tyranno™SA fibers. Tensile tests were conducted on composites with two types of lay-up schemes using edge-loading small specimens. The effect of lay-up orientation on the mechanical properties and fracture behavior of composites were also examined. Tensile strength of composite was slightly decreased at 1573 K, while it retained approximately 80% of the strength at room temperature. Porosity dependence on elastic modulus was clearly exhibited.

  10. High-temperature tensile strength of near-stoichiometric SiC/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Hironaka, K. E-mail: keisuke@iae.kyoto-u.ac.jp; Nozawa, T.; Hinoki, T.; Igawa, N.; Katoh, Y.; Snead, L.L.; Kohyama, A

    2002-12-01

    In an attempt to characterize mechanical properties of near-stoichiometric SiC/SiC composites, tensile tests were conducted at room temperature in air and at elevated temperature under mild oxidizing gases atmosphere. SiC/SiC composites were fabricated by forced-flow chemical vapor infiltration method using two-dimensional fabrics of carbon coated near-stoichiometric Tyranno SA fibers. Tensile tests were conducted on composites with two types of lay-up schemes using edge-loading small specimens. The effect of lay-up orientation on the mechanical properties and fracture behavior of composites were also examined. Tensile strength of composite was slightly decreased at 1573 K, while it retained approximately 80% of the strength at room temperature. Porosity dependence on elastic modulus was clearly exhibited.

  11. Changes to Tensile Strength and Electromagnetic Shielding Effectiveness in Neutron Irradiated Carbon Nanocomposites

    Science.gov (United States)

    2013-03-01

    compatibility ( EMC ) industry uses a wave theory approach to shielding theory, which uses abstract mathematical modeling techniques to yield a value of...2012. [Online]. Available: http://www.spira_emi.com/theory.htm. [Accessed 14 11 2012]. [22] “ Shielding Theory”, Learn EMC , 2012. [Online...CHANGES TO TENSILE STRENGTH AND ELECTROMAGNETIC SHIELDING EFFECTIVENESS IN NEUTRON IRRADIATED

  12. Tensile strength comparison between peroneus longus and hamstring tendons: A biomechanical study

    Directory of Open Access Journals (Sweden)

    Rudy

    2017-01-01

    Conclusion: The tensile strength of the peroneus longus tendon, which is similar to that of hamstring, gives information that both have the same biomechanic properties. Peroneus longus should not be used as a first option in ACL reconstruction, but may be used as an alternative donor in cases involving multiple instability that require more tendon donors in the reconstruction.

  13. Roping in uncertainty – measuring the tensile strength of steel wire ropes

    CSIR Research Space (South Africa)

    Bergh, Riaan

    2016-09-01

    Full Text Available importance to enable early detection of degradation of the condition of the rope so that it may be replaced before the safety of people and equipment is endangered. To this end it is important the result of the tensile strength test is reported with known...

  14. Improvement in Tensile Strength of Bamboo Knitted Fabric by Sol-Gel Coating

    Directory of Open Access Journals (Sweden)

    Awais Khatri

    2013-07-01

    Full Text Available Textiles made of bamboo regenerated fibre are reported to have lower tensile strength than the other cellulosic fibres, due to high porosity of the fibre. This paper was aimed to modify the bamboo knitted fabric by the sol-gel coating to improve the tensile strength with minimum effect on its inherent morphology and ultimate relevant properties such as good absorbency and air permeability. The paddry- bake process was employed for the coating where tetraethyl-orthosilicate and nano-titanium-dioxide were used as the active ingredients. The treated fabrics were tested for the tensile behaviour in terms of breaking strength and elongation and the sol-gel process recipe and parameters were optimised. The absorbency, air-permeability and washing durability of the coating were also tested for the optimised process. Results showed the increase in tensile strength of the fabric by sol-gel coating, whereas absorbency and air-permeability were almost unaffected. The coating results were unaffected even after a washing treatment (equivalent to 5 industrial washings. Additionally, the wrinkle recovery angle of the coated fabric was also tested and found improved.

  15. Effect of the CO2 milliwatt laser on tensile strength of microsutures

    NARCIS (Netherlands)

    Menovsky, T.; Beek, J. F.; van Gemert, M. J.

    1997-01-01

    Laser-assisted tissue repair is often accompanied by a high dehiscence rate, which may be due to alterations in suture material after laser exposure. The goal of this study was to investigate the effect of CO2 laser irradiation on the tensile strength of microsurgical suture material. 10-0 nylon and

  16. Bonding Properties of Basalt Fiber and Strength Reduction According to Fiber Orientation.

    Science.gov (United States)

    Choi, Jeong-Il; Lee, Bang Yeon

    2015-09-30

    The basalt fiber is a promising reinforcing fiber because it has a relatively higher tensile strength and a density similar to that of a concrete matrix as well as no corrosion possibility. This study investigated experimentally the bonding properties of basalt fiber with cementitious material as well as the effect of fiber orientation on the tensile strength of basalt fiber for evaluating basalt fiber's suitability as a reinforcing fiber. Single fiber pullout tests were performed and then the tensile strength of fiber was measured according to fiber orientation. The test results showed that basalt fiber has a strong chemical bond with the cementitious matrix, 1.88 times higher than that of polyvinyl alcohol fibers with it. However, other properties of basalt fiber such as slip-hardening coefficient and strength reduction coefficient were worse than PVA and polyethylene fibers in terms of fiber bridging capacity. Theoretical fiber-bridging curves showed that the basalt fiber reinforcing system has a higher cracking strength than the PVA fiber reinforcing system, but the reinforcing system showed softening behavior after cracking.

  17. A Comparison of Shear Bond Strength of Two Different Techniques with that of Initially Bonded Brackets

    Directory of Open Access Journals (Sweden)

    Abdolhamid Zafarmand

    2014-01-01

    Conclusion: However, there was no significant difference in the shear strength responses of three groups. The results of the study showed that both techniques of rebonding of failed brackets can provide effective bonding strengths similar to the primary strength.

  18. Effect of TiO2 Nanoparticles on Tensile Strength of Dental Acrylic Resins.

    Science.gov (United States)

    Shirkavand, Saeed; Moslehifard, Elnaz

    2014-01-01

    Background and aims. Adding further fillers to dental resins may enhance their physical characteristics. The aim of this study was to evaluate the tensile strength of heat-curing acrylic resin reinforced by TiO2nanoparticles added into the resin matrix. Materials and methods. Commercially available TiO2 nanoparticles were obtained and characterized using X-ray diffrac-tion (XRD) and scanning electron microscopy (SEM) to determine their crystalline structure, particle size and morphology. TiO2-acrylic resin nanocomposite was prepared by mixing 0.5, 1 and 2 (wt%) of surface modified TiO2 nanoparticles in an amalgamator providing three groups of samples. Before curing, the obtained paste was packed into steel molds. After cur-ing, the specimens were removed from the molds. The tensile strength test samples were prepared according to ISO 1567. Results. Two crystalline phases were found in TiO2 nanoparticles including: (i) anatase as the major one, and (ii) rutile. The average particle size calculated according to the Scherrer equation was 20.4 nm, showing a normal size distribution. According to SEM images, the nanocomposite with 1wt% TiO2 nanoparticles had a better distribution compared to other groups. In addition, the group by 1wt% TiO2 exhibited higher tensile strength with a significant difference compared to other groups. ANOVA showed significant differences between the contents of TiO2 particles in acrylic resin (F = 22.19; P < 0.001). Conclusion. A considerable increase in tensile strength was observed with titania NPs reinforcement agents in 1wt% by weight. Further increase of TiO2 nanoparticles decreased the tensile strength.

  19. Effect of TiO2 Nanoparticles on Tensile Strength of Dental Acrylic Resins

    Directory of Open Access Journals (Sweden)

    Saeed Shirkavand

    2014-12-01

    Full Text Available Background and aims. Adding further fillers to dental resins may enhance their physical characteristics. The aim of this study was to evaluate the tensile strength of heat-curing acrylic resin reinforced by TiO2nanoparticles added into the resin matrix. Materials and methods. Commercially available TiO2 nanoparticles were obtained and characterized using X-ray diffrac-tion (XRD and scanning electron microscopy (SEM to determine their crystalline structure, particle size and morphology. TiO2-acrylic resin nanocomposite was prepared by mixing 0.5, 1 and 2 (wt% of surface modified TiO2 nanoparticles in an amalgamator providing three groups of samples. Before curing, the obtained paste was packed into steel molds. After cur-ing, the specimens were removed from the molds. The tensile strength test samples were prepared according to ISO 1567. Results. Two crystalline phases were found in TiO2 nanoparticles including: (i anatase as the major one, and (ii rutile. The average particle size calculated according to the Scherrer equation was 20.4 nm, showing a normal size distribution. Ac-cording to SEM images, the nanocomposite with 1wt% TiO2 nanoparticles had a better distribution compared to other groups. In addition, the group by 1wt% TiO2 exhibited higher tensile strength with a significant difference compared to other groups. ANOVA showed significant differences between the contents of TiO2 particles in acrylic resin (F = 22.19; P < 0.001. Conclusion. A considerable increase in tensile strength was observed with titania NPs reinforcement agents in 1wt% by weight. Further increase of TiO2 nanoparticles decreased the tensile strength.

  20. Comparison of tensile strength of different carbon fabric reinforced epoxy composites

    Directory of Open Access Journals (Sweden)

    Jane Maria Faulstich de Paiva

    2006-03-01

    Full Text Available Carbon fabric/epoxy composites are materials used in aeronautical industry to manufacture several components as flaps, aileron, landing-gear doors and others. To evaluate these materials become important to know their mechanical properties, for example, the tensile strength. Tensile tests are usually performed in aeronautical industry to determinate tensile property data for material specifications, quality assurance and structural analysis. For this work, it was manufactured four different laminate families (F155/PW, F155/HS, F584/PW and F584/HS using pre-impregnated materials (prepregs based on F155TM and F584TM epoxy resins reinforced with carbon fiber fabric styles Plain Weave (PW and Eight Harness Satin (8HS. The matrix F155TM code is an epoxy resin type DGEBA (diglycidil ether of bisphenol A that contains a curing agent and the F584TM code is a modified epoxy resin type. The laminates were obtained by handing lay-up process following an appropriate curing cycle in autoclave. The samples were evaluated by tensile tests according to the ASTM D3039. The F584/PW laminates presented the highest values of tensile strength. However, the highest modulus results were determined for the 8HS composite laminates. The correlation of these results emphasizes the importance of the adequate combination of the polymeric matrix and the reinforcement arrangement in the structural composite manufacture. The microscopic analyses of the tested specimens show valid failure modes for composites used in aeronautical industry.

  1. Comparative evaluation of bond strength of three contemporary self-etch adhesives: An ex vivo study

    Directory of Open Access Journals (Sweden)

    Vineeta Nikhil

    2011-01-01

    Full Text Available Aim: This study evaluated the effect of 2-hydroxymethyl methacrylate (HEMA and the type of solvent on the tensile bond strength of the following three self-etch adhesives: Adper easy one (HEMA-rich adhesive which contained ethanol, G-Bond (HEMA-free adhesive which contained acetone, and Xeno V (HEMA-free adhesive which contained butanol as a solvent. Material and Methods: Intact mandibular molars were mounted in self-cured resin and the occlusal surfaces were ground with # 600 SiC paper. Adhesives were applied on the prepared dentinal surfaces and the resin composite was condensed in the split brass mold (5 × 3 mm placed over the adhesive surface. The specimens were stored in normal saline and placed in incubator at 37°C. After 24 hours, the specimens were tested in tensile mode at a crosshead speed of 1 mm/min. Statistical analysis was done using One way ANOVA and Tukey′s HSD test. Results: The mean bond strengths of Adper easy one, G-Bond, and Xeno V were 12.41 MPa, 10.09 MPa, and 8.67 MPa, respectively. Conclusions: Comparison of contemporary adhesives in this ex vivo study revealed that the ethanol-based HEMA-rich self-etch adhesive is better than HEMA-free self-etch adhesive that contained acetone and butanol as the solvents, when compared in terms of bond strength.

  2. Comparative evaluation of bond strength of three contemporary self-etch adhesives: An ex vivo study.

    Science.gov (United States)

    Nikhil, Vineeta; Singh, Vijay; Chaudhry, Suruchi

    2011-04-01

    This study evaluated the effect of 2-hydroxymethyl methacrylate (HEMA) and the type of solvent on the tensile bond strength of the following three self-etch adhesives: Adper easy one (HEMA-rich adhesive) which contained ethanol, G-Bond (HEMA-free adhesive) which contained acetone, and Xeno V (HEMA-free adhesive) which contained butanol as a solvent. Intact mandibular molars were mounted in self-cured resin and the occlusal surfaces were ground with # 600 SiC paper. Adhesives were applied on the prepared dentinal surfaces and the resin composite was condensed in the split brass mold (5 × 3 mm) placed over the adhesive surface. The specimens were stored in normal saline and placed in incubator at 37°C. After 24 hours, the specimens were tested in tensile mode at a crosshead speed of 1 mm/min. Statistical analysis was done using One way ANOVA and Tukey's HSD test. The mean bond strengths of Adper easy one, G-Bond, and Xeno V were 12.41 MPa, 10.09 MPa, and 8.67 MPa, respectively. Comparison of contemporary adhesives in this ex vivo study revealed that the ethanol-based HEMA-rich self-etch adhesive is better than HEMA-free self-etch adhesive that contained acetone and butanol as the solvents, when compared in terms of bond strength.

  3. The influence of storage time and cutting speed on microtensile bond strength.

    Science.gov (United States)

    Reis, Alessandra; Rocha de Oliveira Carrilho, Marcela; Schroeder, Marcos; Tancredo, Luciane Lima Franco; Loguercio, Alessandro Dourado

    2004-01-01

    The aim of this study was to verify the influence of the storage time and the cutting speed during specimen preparation on the bond strength of a single-bottle adhesive to dentin. A flat dentin surface was exposed in 36 human third molars. The adhesive system (Single Bond) was applied according to the manufacturer's instructions, and composite resin crowns (Z250) were constructed incrementally. Specimens were stored for 10 min, 24 h, or 1 week in distilled water at 37 degrees C before being longitudinally sectioned in both the "x" and "y" directions at different cutting speeds (0.5, 1.6, and 2.6 m/s) to obtain sticks with a cross-sectional area of approximately 0.8 mm2. The specimens were tested in a tensile load machine (0.5 mm/min) and the fracture mode analyzed. A two-way ANOVA with storage time (3 levels) and cutting speed (3 levels) as factors was used to compare the mean microtensile bond strengths. Highly significant main effects and interaction (p bond strength was obtained with a storage time of 1 week and cutting speed of 2.6 m/s. The lowest mean was found when the specimens were prepared immediately after composite resin placement and sliced at 0.5 m/s. Both the storage time and the cutting speed may affect the bond strength results. Therefore, these variables must be controlled in microtensile bond strength tests.

  4. Shear bond strength of veneering porcelain to porous zirconia

    National Research Council Canada - National Science Library

    NAKAMURA, Takashi; SUGANO, Tsuyoshi; USAMI, Hirofumi; WAKABAYASHI, Kazumichi; OHNISHI, Hiroshi; SEKINO, Tohru; YATANI, Hirofumi

    2014-01-01

    .... Furthermore, the shear bond strength of veneering porcelain to zirconia was examined. The flexural strength of the non-layered specimens was 1,220 MPa for dense zirconia and 220 to 306 MPa for porous zirconia...

  5. Strength and sorption properties of cement-bonded composites ...

    African Journals Online (AJOL)

    Strength and sorption properties of cement-bonded composites produced from eucalyptus ( Eucalyptus tereticornis SM.) veneer waste. ... applications where sound absorption is important. Keywords: Eucalyptus, Veneer waste, Cement composite, Strength, dimensional stability. Journal of Applied Science, Engineering and ...

  6. Influence of Strain Rate on Tensile Strength of Woven Geotextile in the Selected Range of Temperature

    Directory of Open Access Journals (Sweden)

    Stępień Sylwia

    2015-06-01

    Full Text Available Investigation of geosynthetics behaviour has been carried out for many years. Before using geosynthetics in practice, the standard laboratory tests had been carried out to determine basic mechanical parameters. In order to examine the tensile strength of the sample which extends at a constant strain rate, one should measure the value of the tensile force and strain. Note that geosynthetics work under different conditions of stretching and temperatures, which significantly reduce the strength of these materials. The paper presents results of the tensile test of geotextile at different strain rates and temperatures from 20 °C to 100 °C. The aim of this study was to determine the effect of temperature and strain rate on tensile strength and strain of the woven geotextile. The article presents the method of investigation and the results. The data obtained allowed us to assess the parameters of material which should be considered in the design of the load-bearing structures that work at temperatures up to 100 °C.

  7. Water absorption and tensile strength degradation of Petung bamboo (Dendrocalamus asper) fiber—reinforced polymeric composites

    Science.gov (United States)

    Judawisastra, H.; Sitohang, R. D. R.; Rosadi, M. S.

    2017-09-01

    Bamboo fibers have attracted great interest and are believed to have the potential as natural fiber for reinforcing polymer composites. This research aims to study water absorption behavior and its effect to tensile strength of the composites made from petung bamboo fiber, which is one of the most grown bamboo species in Indonesia. Unidirectional (UD) and random composites were manufactured using wet hand lay-up method. Examinations were carried out by means of boiling water immersion test, tensile test, scanning electron microscopy and Fourier transform infrared spectroscopy. Water absorption of UD petung bamboo fiber/polyester composites is higher than that of random composites, i.e. 3.6% compared to 2.2%. This was due to higher fiber volume fraction of the UD composites. Water absorption caused irreversible tensile strength degradation on the composites. The initial properties of the composites were not recovered even after drying. The absorbed water decreased the tensile strength by 6% in UD composites and 38% in random composites. This was most likely to occur due to the permanent interfacial degradation.

  8. Validity of bond strength tests: A critical review: Part I

    Science.gov (United States)

    Sirisha, Kantheti; Rambabu, Tankonda; Shankar, Yalavarthi Ravi; Ravikumar, Pabbati

    2014-01-01

    Adhesive systems are selected based on their bond strengths achieved while testing in laboratories. These bond strengths can predict the longevity of a restoration to some extent. There were several discrepancies in the reported bond strengths. To critically review the reliability of macro-bond strength tests used to evaluate resin-tooth interface. Relevant literature published between January 1983 and May 2013 was collected from PubMed database, Google scholar, and hand-searched journals of Conservative Dentistry, Endodontics and Dental materials. Variables that influence the test outcome are categorized into substrate-related factors, factors related to specimen properties, preparation of specimens, and test methodology. Impact of these variables on the test outcome is critically analyzed. There is lack of a standard format for reporting the bond strength tests, which could lead to misinterpretation of the data and bonding abilities of adhesives. PMID:25125840

  9. Effect of diamond bur cutting efficacy on dentin bond strengths of different bonding systems

    Directory of Open Access Journals (Sweden)

    Shirani F.

    2009-03-01

    Full Text Available "nBackground and Aim: As composite-dentin bond strength is affected by cavity preparation and the bond strength of composite resin to new and used bur prepared dentin has not yet been evaluated, this study evaluated the effects of cutting dentin with different cutting efficacy (new and used of burs on composite-dentin shear bond strength using self-etching primer bonding system and total etching bonding system. "nMaterials and Methods: Sixty caries free human 3rd molar were sectioned in occlosal surface to expose dentin, then polished with silicon carbide paper and randomly divided into four groups. Each group was prepared in a depth of 0.5mm of dentin, using new diamond bur, or used diamond bur. To change into a used bur, each new rough diamond bur had to work on bovine enamel for 30 minutes, under a load of 150g. Then, each group was bonded, using a total etch adhesive (single Bond or a self etch adhesive (clearfil SE Bond So there were 4 groups : 1-SE Bond, New bur; 2-SE Bond , used bur; 3-Single Bond , New bur ; 4-Single Bond, used bur. Similar composite capsules(Filtek Z250 were bonded to dentin surface and cured. specimens were stored in physiologic saline for 48h at 370 c , then put under shearing load to define composite - dentin shear bond strength. Results were interpreted via statistical analysis (T-test & two - way variance. "nResults: Shear bond strength of each group was as follows: 1-(27.3Mpa, 2-(33.5Mpa, 3-(16.9Mpa 4-(19.3Mpa. Statistical analysis proved that shear bond strength of used diamond bur prepared groups (2,4 was more than new diamond bur prepared ones (1,3. This statistical difference, specially, was seen between SE Bond groups (1,2 but not between single Bond groups (3,4. Also, shear bond strength of (SE Bond bonded groups (1,2 were more significantly than (single Bond bonded ones (3,4. "nConclusion: This study show that Bur cutting efficiency influences composite - dentin shear bond strength especially when the

  10. Halogen light versus LED for bracket bonding: shear bond strength

    Directory of Open Access Journals (Sweden)

    Paulo Eduardo Guedes Carvalho

    2013-02-01

    Full Text Available INTRODUCTION: LED light-curing devices seek to provide a cold light activator which allows protocols of material polymerization with shorter duration. OBJECTIVE: The present study aimed to evaluate the shear bond strength of bracket bonding using three types of light-curing devices: One with halogen light (Optilight Plus - Gnatus and two with LEDs (Optilight CL - Gnatus and Elipar Freelight - 3M/ESPE. RESULTS: Comparing the results by analysis of variance, the Gnatus LED device showed an inferior statistical behavior in relation to other light sources, when activated by a short time. But, when it was used for 40 seconds, the polymerization results were consistent with the other evaluated sources. The device with the best average performance was the halogen light, followed by the 3M/ESPE LED. CONCLUSION: It was concluded that the LEDs may be indicated in orthodontic practice, as long as a protocol is used for the application of light with the activation time of 40 seconds.INTRODUÇÃO: os aparelhos de fotopolimerização por LED buscam proporcionar uma luz ativadora fria, que possibilite protocolos de polimerização do material com menor tempo de duração. OBJETIVO: avaliar a resistência à tração da colagem de braquetes, utilizando três tipos de aparelhos fotoativadores: um de luz halógena (Optilight Plus - Gnatus e outros dois de LED (Optilight CL - Gnatus; e Elipar Freelight - 3M/Espe. RESULTADOS: comparando os resultados por meio da análise de variância, o aparelho de LED Gnatus apresentou comportamento estatístico inferior em relação às outras fontes de luz, quando ativado por tempo reduzido. Já quando foi utilizado o tempo de 40 segundos, os resultados de polimerização foram compatíveis com as demais fontes avaliadas. O aparelho que apresentou melhor desempenho médio foi o de luz halógena, seguido pelo LED 3M/Espe. CONCLUSÃO: concluiu-se que os LEDs podem ser indicados na prática ortodôntica, uma vez que seja utilizado

  11. Estimating the Uncertainty of Tensile Strength Measurement for A Photocured Material Produced by Additive Manufacturing

    Directory of Open Access Journals (Sweden)

    Adamczak Stanisław

    2014-08-01

    Full Text Available The aim of this study was to estimate the measurement uncertainty for a material produced by additive manufacturing. The material investigated was FullCure 720 photocured resin, which was applied to fabricate tensile specimens with a Connex 350 3D printer based on PolyJet technology. The tensile strength of the specimens established through static tensile testing was used to determine the measurement uncertainty. There is a need for extensive research into the performance of model materials obtained via 3D printing as they have not been studied sufficiently like metal alloys or plastics, the most common structural materials. In this analysis, the measurement uncertainty was estimated using a larger number of samples than usual, i.e., thirty instead of typical ten. The results can be very useful to engineers who design models and finished products using this material. The investigations also show how wide the scatter of results is.

  12. Influencia del tiempo de tratamiento de superficie con ácido fluorhídrico de la porcelana VITA VM 13 en la resistencia de unión a cemento de resina frente a fuerzas de tracción: Estudio in vitro Influence of surface treatment time with hydrofluoric acid of VITA VM13 porcelain on tensile bond strength to a luting resin cement: In vitro study

    Directory of Open Access Journals (Sweden)

    JP Guzmán Thoms

    2012-12-01

    dimensions of 5 mm in height and 7 mm in diameter were randomly divided into 3 groups (n=10 according to the treatments received. Group I (control - no surface conditioning; Group II- recorded with 9.6% hydrofluoric acid for 1 minute; Group III - recorded with 9.6% hydrofluoric acid for 2 minutes. Their tensile bond strength was tested in a universal testing machine (Instron Model 4411, 3M. The values, expressed in MPa, were statistically analyzed at a level of significance of 5%, using Analysis of Variance (ANOVA of a factor. Results: In relation to the bond strength test, tensile strength, revealed the following values for each group: Group I (control - x=3.35 MPa, Group II - x=4.64 MPa, Group III - x=3.80 MPa. Conclusions: According to the results, it can be concluded that the surface treatment with hydrofluoric acid for 1 minute promotes microretentions, which significantly increase the values of bond strength, tensile strength. This can result in a higher clinical benefit.

  13. Tensile Strength Reliability Analysis of Cu48Zr48Al4 Amorphous Microwires

    Directory of Open Access Journals (Sweden)

    Haichao Sun

    2016-11-01

    Full Text Available Uniform Cu48Zr48Al4 amorphous microwires with a high surface quality are fabricated by a melt extraction technique. The mechanical property of microwires is evaluated via tensile tests. To estimate the strength scattering, statistical analysis of fracture strengths is conducted using logarithmic normal distribution, and two- and three-parameter Weibull analysis, severally. The results show that the tensile strengths of Cu48Zr48Al4 amorphous microwires range from 1724 to 1937 MPa with the arithmetical average value of 1836 MPa, and the arithmetical standard deviation of 56.4 MPa. The geometric mean of fracture strength is 1840 MPa using logarithmic normal distribution statistical analysis. Using two- and three-parameter Weibull analysis, the Weibull modulus and fracture threshold value are respectively calculated for 34.8 and 1483 MPa, which shows the excellent tensile mechanical properties with a high predictability of Cu48Zr48Al4 amorphous microwires and further indicates the great potential of application.

  14. Influence of dentin pretreatment on bond strength of universal adhesives.

    Science.gov (United States)

    Poggio, Claudio; Beltrami, Riccardo; Colombo, Marco; Chiesa, Marco; Scribante, Andrea

    2017-01-01

    Objective: The purpose of the present study was to compare bond strength of different universal adhesives under three different testing conditions: when no pretreatment was applied, after 37% phosphoric acid etching and after glycine application. Materials and methods: One hundred and fifty bovine permanent mandibular incisors were used as a substitute for human teeth. Five different universal adhesives were tested: Futurabond M+, Scotchbond Universal, Clearfil Universal Bond, G-Premio BOND, Peak Universal Bond. The adhesive systems were applied following each manufacturer's instructions. The teeth were randomly assigned to three different dentin surface pretreatments: no pretreatment agent (control), 37% phosphoric acid etching, glycine pretreatment. The specimens were placed in a universal testing machine in order to measure and compare bond strength values. Results: The Kruskal-Wallis analysis of variance and the Mann-Whitney test were applied to assess significant differences among the groups. Dentin pretreatments provided different bond strength values for the adhesives tested, while similar values were registered in groups without dentin pretreatment. Conclusions: In the present report, dentin surface pretreatment did not provide significant differences in shear bond strength values of almost all groups. Acid pretreatment lowered bond strength values of Futurabond and Peak Universal Adhesives, whereas glycine pretreatment increased bond strength values of G Praemio Bond adhesive system.

  15. Tensile strength of surgical knots performed with the da Vinci surgical robot.

    Science.gov (United States)

    Reynisson, Pétur; Shokri, Ebi; Bendahl, Pär-Ola; Persson, Jan

    2010-01-01

    The objective of this study was to estimate the tensile strength of surgical knots made using the da Vinci robot. Four different types of flat square knots (strand-to-strand 4 throw, strand-to-strand 6 throw, loop-to-strand 4 throw, and loop-to-strand 6 throw) were made using the da Vinci-S system by 4 different surgeons, all experienced with the system. For the knots, we used braided polyglactin 910 (Vicryl 2-0). Hand-tied, flat, square, 4-throw strand-to-strand knots were used as reference. The tensile strength was measured for all knots using the Instron 5566 system calibrated to an accuracy of + or - .5% at 4 to 10 newtons (N) and + or - .4% at greater than 10 N. Compared with reference knots, only 1 of 4 surgeons could make knots as equally strong with the robot. For all surgeons, strand-to-strand knots had a significantly higher tensile strength than loop-to-strand knots when made with the robot. Adding 2 throws to the knot did not increase the knots strength in the robot. It is possible to make equally strong surgical knots with the da Vinci robot as by hand; however, despite previous experience with the robot, only 1 of 4 surgeons managed to do so. Adding 2 throws to R4SS and R4LS knots did not increase the tensile strength significantly for any of the 4 surgeons. It is important to train and tie knots using the da Vinci system with the same care as by hand and to be aware of possible differences in knot-tying technique with the robot and manually. With the robot, strand-to-strand knots were stronger than loop-to-strand knots, and should be preferred. Copyright 2010 AAGL. All rights reserved.

  16. Effect of Bonding Application Time on Bond Strength of Composite Resin to Glass Ionomer Cement

    Directory of Open Access Journals (Sweden)

    Narges Panahandeh

    2016-08-01

    Full Text Available Objectives: This experimental study evaluated the effect of bonding application time on the microshear bond strength of composite resin to different types of glass ionomer cements (GICs.Materials and Methods: One-hundred and sixty specimens (two conventional and two resin-modified GICs were prepared and divided into 16 groups. The surface of all specimens was prepared using two different bonding systems (Frog and Stea at three different times. After setting, the composite resin (Z100 was placed over the GICs. The specimens were then stored in distilled water for 24 hours (37oC and exposed to microshear stresses at a crosshead speed of 1 mm/min. The results were analyzed using three-way ANOVA and Tukey’s test (P˂0.05.Results: In conventional GICs, bond strength was affected by the type of bonding system at different times, and bond strength was significantly higher in the Fuji II group compared to Riva Self Cure group. In the Riva Self Cure group, bond strength was significantly affected by time; whereas, the type of bonding system failed to exert a significant effect on bond strength. There was no significant correlation between the type of bonding system and the two brands of resin-modified GICs. Bond strength was not affected by the type of bonding agent; however, among the two brands of resin-modified GICs, Fuji II LC yielded a significantly stronger bond.Conclusion: It appears that the type of bonding agent does not affect the microshear bond strength, and the bonding application time affects the microshear bond strength in Riva Self Cure GICs.

  17. Novel strip-cast Mg/Al clad sheets with excellent tensile and interfacial bonding properties.

    Science.gov (United States)

    Kim, Jung-Su; Lee, Dong Ho; Jung, Seung-Pill; Lee, Kwang Seok; Kim, Ki Jong; Kim, Hyoung Seop; Lee, Byeong-Joo; Chang, Young Won; Yuh, Junhan; Lee, Sunghak

    2016-06-01

    In order to broaden industrial applications of Mg alloys, as lightest-weight metal alloys in practical uses, many efforts have been dedicated to manufacture various clad sheets which can complement inherent shortcomings of Mg alloys. Here, we present a new fabrication method of Mg/Al clad sheets by bonding thin Al alloy sheet on to Mg alloy melt during strip casting. In the as-strip-cast Mg/Al clad sheet, homogeneously distributed equi-axed dendrites existed in the Mg alloy side, and two types of thin reaction layers, i.e., γ (Mg17Al12) and β (Mg2Al3) phases, were formed along the Mg/Al interface. After post-treatments (homogenization, warm rolling, and annealing), the interfacial layers were deformed in a sawtooth shape by forming deformation bands in the Mg alloy and interfacial layers, which favorably led to dramatic improvement in tensile and interfacial bonding properties. This work presents new applications to multi-functional lightweight alloy sheets requiring excellent formability, surface quality, and corrosion resistance as well as tensile and interfacial bonding properties.

  18. The exercise-induced biochemical milieu enhances collagen content and tensile strength of engineered ligaments.

    Science.gov (United States)

    West, Daniel W D; Lee-Barthel, Ann; McIntyre, Todd; Shamim, Baubak; Lee, Cassandra A; Baar, Keith

    2015-10-15

    Exercise stimulates a dramatic change in the concentration of circulating hormones, such as growth hormone (GH), but the biological functions of this response are unclear. Pharmacological GH administration stimulates collagen synthesis; however, whether the post-exercise systemic milieu has a similar action is unknown. We aimed to determine whether the collagen content and tensile strength of tissue-engineered ligaments is enhanced by serum obtained post-exercise. Primary cells from a human anterior cruciate ligament (ACL) were used to engineer ligament constructs in vitro. Blood obtained from 12 healthy young men 15 min after resistance exercise contained GH concentrations that were ∼7-fold greater than resting serum (P Ligament constructs were treated for 7 days with medium supplemented with serum obtained at rest (RestTx) or 15 min post-exercise (ExTx), before tensile testing and collagen content analysis. Compared with RestTx, ExTx enhanced collagen content (+19%; 181 ± 33 vs. 215 ± 40 μg per construct P = 0.001) and ligament mechanical properties - maximal tensile load (+17%, P = 0.03 vs. RestTx) and ultimate tensile strength (+10%, P = 0.15 vs. RestTx). In a separate set of engineered ligaments, recombinant IGF-1, but not GH, enhanced collagen content and mechanics. Bioassays in 2D culture revealed that acute treatment with post-exercise serum activated mTORC1 and ERK1/2. In conclusion, the post-exercise biochemical milieu, but not recombinant GH, enhances collagen content and tensile strength of engineered ligaments, in association with mTORC1 and ERK1/2 activation. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

  19. Bond strength of two component injection moulded MID

    DEFF Research Database (Denmark)

    Islam, Mohammad Aminul; Hansen, Hans Nørgaard; Tang, Peter Torben

    2006-01-01

    the two different plastic materials in the MID structure require good bonding between them. This paper finds suitable combinations of materials for MIDs from both bond strength and metallisation view-point. Plastic parts were made by two-shot injection moulding and the effects of some important process...... parameters on the resulting bond strength were investigated. A simple test setup has been used to measure the bond strength of 2k moulded plastic parts. This paper expresses the test results in numerical values and suggests suitable combinations of polymers from a large number of possibilities. The results...

  20. The effect of different light-curing units on tensile strength and microhardness of a composite resin

    Directory of Open Access Journals (Sweden)

    Eduardo Batista Franco

    2007-12-01

    Full Text Available The aim of this study was to evaluate the influence of different light-curing units on the tensile bond strength and microhardness of a composite resin (Filtek Z250 - 3M/ESPE. Conventional halogen (Curing Light 2500 - 3M/ESPE; CL and two blue light emitting diode curing units (Ultraled - Dabi/Atlante; UL; Ultrablue IS - DMC; UB3 and UB6 were selected for this study. Different light intensities (670, 130, 300, and 600 mW/cm², respectively and different curing times (20s, 40s and 60s were evaluated. Knoop microhardness test was performed in the area corresponding to the fractured region of the specimen. A total of 12 groups (n=10 were established and the specimens were prepared using a stainless steel mold composed by two similar parts that contained a cone-shaped hole with two diameters (8.0 mm and 5.0 mm and thickness of 1.0 mm. Next, the specimens were loaded in tensile strength until fracture in a universal testing machine at a crosshead speed of 0.5 mm/min and a 50 kg load cell. For the microhardness test, the same matrix was used to fabricate the specimens (12 groups; n=5. Microhardness was determined on the surfaces that were not exposed to the light source, using a Shimadzu HMV-2 Microhardness Tester at a static load of 50 g for 30 seconds. Data were analyzed statistically by two-way ANOVA and Tukey's test (p<0.05. Regarding the individual performance of the light-curing units, there was similarity in tensile strength with 20-s and 40-s exposure times and higher tensile strength when a 60-s light-activation time was used. Regarding microhardness, the halogen lamp had higher results when compared to the LED units. For all light-curing units, the variation of light-exposure time did not affect composite microhardness. However, lower irradiances needed longer light-activation times to produce similar effect as that obtained with high-irradiance light-curing sources.

  1. Influence of intrapulpal pressure simulation on the bond strength of adhesive systems to dentin

    Directory of Open Access Journals (Sweden)

    Marcio Vivan Cardoso

    2008-06-01

    Full Text Available The purpose of this study was to evaluate the influence of intrapulpal pressure simulation on the bonding effectiveness of etch & rinse and self-etch adhesives to dentin. Eighty sound human molars were distributed into eight groups, according to the permeability level of each sample, measured by an apparatus to assess hydraulic conductance (Lp. Thus, a similar mean permeability was achieved in each group. Three etch & rinse adhesives (Prime & Bond NT - PB, Single Bond -SB, and Excite - EX and one self-etch system (Clearfil SE Bond - SE were employed, varying the presence or absence of an intrapulpal pressure (IPP simulation of 15 cmH2O. After adhesive and restorative procedures were carried out, the samples were stored in distilled water for 24 hours at 37°C, and taken for tensile bond strength (TBS testing. Fracture analysis was performed using a light microscope at 40 X magnification. The data, obtained in MPa, were then submitted to the Kruskal-Wallis test ( a = 0.05. The results revealed that the TBS of SB and EX was significantly reduced under IPP simulation, differing from the TBS of PB and SE. Moreover, SE obtained the highest bond strength values in the presence of IPP. It could be concluded that IPP simulation can influence the bond strength of certain adhesive systems to dentin and should be considered when in vitro studies are conducted.

  2. Bond strength between stell-concrete and between concretes with different ages in structural rehabilitation

    Directory of Open Access Journals (Sweden)

    M. R. DORIA

    Full Text Available ABSTRACTIn inspections of buildings, it is common to find structures that, well before reaching its useful life longer require repairs and reinforcements. This study examined the bond strength between concrete of different ages and between steel and concrete, focusing on the recovery of reinforced concrete structures. To analyze the bond between concrete of different ages, trials with specimens receiving three different types of treatments at the interface between the concrete were performed: brushing; brushing and mortar equal to concrete of substrate and brushing and epoxy layer. Indirect tensile tests and oblique and vertical shear tests at the interface were made . The bond stress between steel and concrete was evaluated by pull out test under the conditions of the bar inserted in the still fresh concrete and when inserted in the hardened concrete with epoxy. Results showed increased bond strength by indirect tensile stress of 15% and 37%; 4% and 12% for the adherence test by oblique shear, and 108% and 178%, for the testing of vertical shear, respectively, for the specimens whose interfaces have received, in addition to brushing, layer of mortar and epoxy bridge, compared to those who received only brushing. Insignificant loss (about 0.52% of bond stress was noticed for pull out test of steel bar when compared with test results of the specimens that had steel bar inserted in the concrete in the hardened state with epoxy adhesion bridge, with those who had inserted steel bar in fresh concrete.

  3. Tensile strength of warm and cool season forage grasses in Florida.

    Science.gov (United States)

    Weinberg, Zwi G; Fethiere, Richard; Adesogan, Adegbola; Sollenberger, Lynn

    2017-10-01

    The tensile strength (TS) of four warm-season and three cool-season forage grasses was measured with an Instron Universal machine, along with cell-wall analysis and determination of in vitro organic matter digestibility. The mean TS of the warm-season grasses was significantly higher than that of the cool season grasses (22 vs. 9 kg, respectively, p oats (12.6 vs. 6.8 and 7.5 kg, respectively, p digestibility (correlation coefficients were 0.64, 0.73. 0.41, and -0.64, respectively). Grass tensile strength may have implications on animal preference and on the energy that animals must spend during grazing, and consequently on animal performance (feed intake, daily weight gain and milk, and meat production). Information on grass TS would help to select and screen improved forage cultivars and enable to improve grassland management with better animal performance. © 2016 Wiley Periodicals, Inc.

  4. Coating of carbon nanotube fibers: variation of tensile properties, failure behavior and adhesion strength

    Science.gov (United States)

    Mäder, Edith; Liu, Jian-Wen; Hiller, Janett; Lu, Weibang; Li, Qingwen; Zhandarov, Serge; Chou, Tsu-Wei

    2015-07-01

    An experimental study of the tensile properties of CNT fibers and their interphasial behavior in epoxy matrices is reported. One of the most promising applications of CNT fibers is their use as reinforcement in multifunctional composites. For this purpose, an increase of the tensile strength of the CNT fibers in unidirectional composites as well as strong interfacial adhesion strength is desirable. However, the mechanical performance of the CNT fiber composites manufactured so far is comparable to that of commercial fiber composites. The interfacial properties of CNT fiber/polymer composites have rarely been investigated and provided CNT fiber/epoxy interfacial shear strength of 14.4 MPa studied by the microbond test. In order to improve the mechanical performance of the CNT fibers, an epoxy compatible coating with nano-dispersed aqueous based polymeric film formers and low viscous epoxy resin, respectively, was applied. For impregnation of high homogeneity, low molecular weight epoxy film formers and polyurethane film formers were used. The aqueous based epoxy film formers were not crosslinked and able to interdiffuse with the matrix resin after impregnation. Due to good wetting of the individual CNT fibers by the film formers, the degree of activation of the fibers was improved leading to increased tensile strength and Young’s modulus. Cyclic tensile loading and simultaneous determination of electric resistance enabled to characterize the fiber’s durability in terms of elastic recovery and hysteresis. The pull-out tests and SEM study reveal different interfacial failure mechanisms in CNT fiber/epoxy systems for untreated and film former treated fibers, on the one hand, and epoxy resin treated ones, on the other hand. The epoxy resin penetrated between the CNT bundles in the reference or film former coated fiber, forming a relatively thick CNT/epoxy composite layer and thus shifting the fracture zone within the fiber. In contrast to this, shear sliding along

  5. Coating of carbon nanotube fibers: variation of tensile properties, failure behavior and adhesion strength

    Directory of Open Access Journals (Sweden)

    Edith eMäder

    2015-07-01

    Full Text Available An experimental study of the tensile properties of CNT fibers and their interphasial behavior in epoxy matrices is reported. One of the most promising applications of CNT fibers is their use as reinforcement in multifunctional composites. For this purpose, an increase of the tensile strength of the CNT fibers in unidirectional composites as well as strong interfacial adhesion strength is desirable. However, the mechanical performance of the CNT fiber composites manufactured so far is comparable to that of commercial fiber composites. The interfacial properties of CNT fiber/polymer composites have rarely been investigated and provided CNT fiber/epoxy interfacial shear strength of 14.4 MPa studied by the microbond test.In order to improve the mechanical performance of the CNT fibers, an epoxy compatible coating with nano-dispersed aqueous based polymeric film formers and low viscous epoxy resin, respectively, was applied. For impregnation of high homogeneity, low molecular weight epoxy film formers and polyurethane film formers were used. The aqueous based epoxy film formers were not crosslinked and able to interdiffuse with the matrix resin after impregnation. Due to good wetting of the individual CNT fibers by the film formers, the degree of activation of the fibers was improved leading to increased tensile strength and Young’s modulus. Cyclic tensile loading and simultaneous determination of electric resistance enabled to characterize the fiber’s durability in terms of elastic recovery and hysteresis.The pull-out tests and SEM study reveal different interfacial failure mechanisms in CNT fiber/epoxy systems for untreated and film former treated fibers, on the one hand, and epoxy resin treated ones, on the other hand. The epoxy resin penetrated between the CNT bundles in the reference or film former coated fiber, forming a relatively thick CNT/epoxy composite layer and thus shifting the fracture zone within the fiber. In contrast to this

  6. Tensile strength and corrosion resistance of brazed and laser-welded cobalt-chromium alloy joints.

    Science.gov (United States)

    Zupancic, Rok; Legat, Andraz; Funduk, Nenad

    2006-10-01

    The longevity of prosthodontic restorations is often limited due to the mechanical or corrosive failure occurring at the sites where segments of a metal framework are joined together. The purpose of this study was to determine which joining method offers the best properties to cobalt-chromium alloy frameworks. Brazed and 2 types of laser-welded joints were compared for their mechanical and corrosion characteristics. Sixty-eight cylindrical cobalt-chromium dental alloy specimens, 35 mm long and 2 mm in diameter, were cast. Sixteen specimens were selected for electrochemical measurements in an artificial saliva solution and divided into 4 groups (n=4). In the intact group, the specimens were left as cast. The specimens of the remaining 3 groups were sectioned at the center, perpendicular to the long-axis, and were subsequently rejoined by brazing (brazing group) or laser welding using an X- or I-shaped joint design (X laser and I laser groups, respectively). Another 16 specimens were selected for electrochemical measurements in a more acidic artificial saliva solution. These specimens were also divided into 4 groups (n=4) as described above. Electrochemical impedance spectroscopy and potentiodynamic polarization were used to assess corrosion potentials, breakdown potentials, corrosion current densities, total impedances at lowest frequency, and polarization charge-transfer resistances. The remaining 36 specimens were used for tensile testing. They were divided into 3 groups in which specimen pairs (n=6) were joined by brazing or laser welding to form 70-mm-long cylindrical rods. The tensile strength (MPa) was measured using a universal testing machine. Differences between groups were analyzed using 1-way analysis of variance (alpha=.05). The fracture surfaces and corrosion defects were examined with a scanning electron microscope. The average tensile strength of brazed joints was 792 MPa and was significantly greater (Pcobalt-chromium alloy joints, but strength is

  7. Optimizing tensile strength of low-alloy steel joints in upset welding

    OpenAIRE

    Hamedi, M

    2006-01-01

    Purpose: Purpose In resistance upset welding, the heat is generated by resistance of the interface of abutting surfaces to the flow of electrical current in heating and post-weld heating stages. Upset welding typically results in solid-state welds with no melting at the joint. In this paper, the effect of process parameters including heating and post-weld heating power and their corresponding duration along with interference, on the tensile strength of the welded joint are experimentally inve...

  8. Optimization of tensile strength for new type acetone-urea-formaldehyde furan resin using uniform design

    Directory of Open Access Journals (Sweden)

    Lin Shengjun

    2011-02-01

    Full Text Available In this study, the 24 h tensile strength of new type acetone-urea-formaldehyde furan resin (nitrogen content 3% was investigated by uniform design optimization. Four independent variables such as acetone : formaldehyde molar ratio (mol/mol, solution pH value, reaction temperature (℃ and reaction time (min were considered in the experiments. U*13(134 uniform design was employed and the equation of 24 h tensile strength model was obtained after 13 experimentations. The 24 h tensile strength was optimized by applying single factor experiments and stepwise non-linear regression analysis. Minitab (Minitab 15 trial version and MATLAB (R2010a trial version were used for data analysis. The t-value and p-value indicate that the major impact factors include the interaction effect of solution pH value and reaction temperature (X2X3, the linear terms of acetone : formaldehyde molar ratio (X1, reaction time (X4 followed by the square effects of acetone/formaldehyde molar ratio (X1X1. The optimized results were achieved with the acetone: formaldehyde molar ratio (mol/mol at 3:1, solution pH value at 6.0, reaction temperature at 70 ℃, and reaction time at 140 min, respectively. This method can not only significantly reduce the number and cost of the tests, but also provide a good experimental design strategy for the development of furan resin. The investigation shows that the predicted results of 24 h tensile strength are consistent well with the experimental ones.

  9. Effect of Strain Rates and Pre-Twist on Tensile Strength of Kevlar KM2 Single Fiber

    Science.gov (United States)

    2013-04-01

    Tension. Polymer 2012, 53, 5568–5574. 9. Wilfong, R. E.; Zimmerman, J. Strength and Durability Characteristics of Kevlar Aramid Fiber . Journal of...Effect of Strain Rates and Pre-Twist on Tensile Strength of Kevlar KM2 Single Fiber by Brett D. Sanborn and Tusit T. Weerasooriya ARL-TR...6403 April 2013 Effect of Strain Rates and Pre-Twist on Tensile Strength of Kevlar KM2 Single Fiber Brett D. Sanborn Oak Ridge Institute

  10. Strain Rate Effect on Tensile Behavior for a High Specific Strength Steel: From Quasi-Static to Intermediate Strain Rates

    OpenAIRE

    Wei Wang; Yan Ma; Muxin Yang; Ping Jiang; Fuping Yuan; Xiaolei Wu

    2017-01-01

    The strain rate effect on the tensile behaviors of a high specific strength steel (HSSS) with dual-phase microstructure has been investigated. The yield strength, the ultimate strength and the tensile toughness were all observed to increase with increasing strain rates at the range of 0.0006 to 56/s, rendering this HSSS as an excellent candidate for an energy absorber in the automobile industry, since vehicle crushing often happens at intermediate strain rates. Back stress hardening has been ...

  11. Tensile and electrical properties of high-strength high-conductivity copper alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Eatherly, W.S. [Oak Ridge National Lab., TN (United States)

    1998-09-01

    Electrical conductivity and tensile properties have been measured on an extruded and annealed CuCrNb dispersion strengthened copper alloy which has been developed for demanding aerospace high heat flux applications. The properties of this alloy are somewhat inferior to GlidCop dispersion strengthened copper and prime-aged CuCrZr over the temperature range of 20--500 C. However, if the property degradation in CuCrZr due to joining operations and the anisotropic properties of GlidCop in the short transverse direction are taken into consideration, CuCrNb may be a suitable alternative material for high heat flux structural applications in fusion energy devices. The electrical conductivity and tensile properties of CuCrZr that was solution annealed and then simultaneously aged and diffusion bonded are also summarized. A severe reduction in tensile elongation is observed in the diffusion bonded joint, particularly if a thin copper shim is not placed in the diffusion bondline.

  12. Modification of Rule of Mixtures for Tensile Strength Estimation of Circular GFRP Rebars

    Directory of Open Access Journals (Sweden)

    Young-Jun You

    2017-12-01

    Full Text Available The rule of mixtures (ROM method is often used to estimate the tensile strength of fiber reinforced polymers (FRPs reinforcing bars (rebars. Generally, the ROM method predicts the FRP rebars’ modulus of elasticity adequately but overestimates their tensile strength. This may result from defects occurred during manufacture that prevent the used materials from exhibiting a sound performance and the shear-lag phenomenon by transmission of external forces through the surface of the rebar having a circular cross section. Due to the latter, there is a difference in fiber breaking points regarding the fibers located on the surface and fibers located at the center, and thus results in differences between the values calculated from the conventional ROM and the experimental result. In this study, for the purpose of resolving the problem, glass FRP (GFRP rebars were shaped to have a hollow section at the center of their cross sections and were further subject to tensile strength tests. The test results were further placed under regression analysis and a modified ROM within ±5% accuracy compared to the experimental value was proposed for GFRP rebars with 13, 16, and 19 mm diameters.

  13. Effect of elevated temperature on the tensile strength of Napier/glass-epoxy hybrid reinforced composites

    Science.gov (United States)

    Ridzuan, M. J. M.; Majid, M. S. Abdul; Afendi, M.; Firdaus, A. Z. Ahmad; Azduwin, K.

    2017-11-01

    The effects of elevated temperature on the tensile strength of Napier/glass-epoxy hybrid reinforced composites and its morphology of fractured surfaces are discussed. Napier/glass-epoxy hybrid reinforced composites were fabricated by using vacuum infusion method by arranging Napier fibres in between sheets of woven glass fibres. Napier and glass fibres were laminated with estimated volume ratios were 24 and 6 vol. %, respectively. The epoxy resin was used as matrix estimated to 70 vol. %. Specimens were tested to failure under tension at a cross-head speed of 1 mm/min using Universal Testing Machine (Instron) with a load cell 100 kN at four different temperatures of RT, 40°C, 60°C and 80°C. The morphology of fractured surface of hybrid composites was investigated by field emission scanning electron microscopy. The result shows reduction in tensile strength at elevated temperatures. The increase in the temperature activates the process of diffusion, and generates critical stresses which cause the damage at first-ply or at the centre of the hybrid plate, as a result lower the tensile strength. The observation of FESEM images indicates that the fracture mode is of evolution of localized damage, from fibre/matrix debonding, matric cracking, delamination and fibre breakage.

  14. Tensile strength testing for resorbable mesh fixation systems in laparoscopic ventral hernia repair.

    Science.gov (United States)

    Reynvoet, Emmelie; Berrevoet, Frederik; De Somer, Filip; Vercauteren, Griet; Vanoverbeke, Ingrid; Chiers, Koen; Troisi, Roberto

    2012-09-01

    In an attempt to improve patient outcome and quality of life after laparoscopic ventral hernia repair, resorbable fixation devices have been developed to allow adequate mesh fixation while minimizing accompanying side-effects as tack erosion and adhesion formation. In experimental set-up, 24 pigs were treated by laparoscopic mesh placement. Two different meshes (PP/ORC and PP/ePTFE) and four fixation devices were evaluated: a 6.4 mm poly(D,L: )-lactide pushpin (tack I), a 6.8 mm poly(D,L: )-lactide with blunt tip (tack II), a 4.1 mm poly(glycolide-co-L-lactide) (tack III) and one titanium tack (control tack). A first group of animals (n = 12) was euthanized after 2 weeks survival and a second group (n = 12) after 6 months. At euthanasia, a relaparoscopy was performed to assess adhesion formation followed by laparotomy with excision of the entire abdominal wall. Tensile strength of the individual fixation systems was tested with the use of a tensiometer by measuring the force to pull the tack out of the mesh. Additionally, the foreign body reaction to the fixation systems was evaluated histologically as was their potential degradation. At 2 weeks the tensile strength was significantly higher for the control tack (31.98 N/cm²) compared to the resorbable devices. Except for tack II, the tensile strength was higher when the devices were fixed in a PP/ePTFE mesh compared to the PP/ORC mesh. After 6 months only tack III was completely resorbed, while tack I (9.292 N/cm²) had the lowest tensile strength. At this time-point similar tensile strength was observed for both tack II (29.56 N/cm²) and the control tack (27.77 N/cm²). Adhesions seem to be more depending on the type of mesh, in favor of PP/ePTFE. At long term, the 4.1 mm poly(glycolide-co-L-lactide) tack was the only tack completely resorbed while the 6.8 mm poly(D,L: )-lactide tack with blunt tip reached equal strengths to the permanent tack.

  15. Evaluation and Study the Effect of Additives and Other Factors on Tensile Strength of Asphalt Paving Mixtures

    Directory of Open Access Journals (Sweden)

    Hanaa Khaleel A. Al-Baiti

    2012-03-01

    Full Text Available The resistance of asphaltic concrete to cracking is dependent upon its tensile strength and flexibility characteristics. Also the low tensile strength has recognized as a major contributor to other performance problems. The fatigue life of mixtures decreases exponentially with decreasing of tensile strength. This trend is justified by the loss in stiffness and thereby initiating cracks and stripping. The main objective of this research is intended to study the effect of different variables related with the used materials and the external conditions on the tensile strength and predict a model of indirect tensile strength in asphalt concrete paving materials under the local prevailing conditions and investigate the effect of percent of additives of (Polyestrene resins and Hydrated Lime to enhance the resistance ability of asphalt concrete mixture against distresses. The main affected factors; soaking, asphalt content, compaction, aggregate maximum size and temperature, influence on the indirect tensile strength and presented through a statistics analysis model for tensile strength in asphalt mixture

  16. Bond strength of universal adhesives: A systematic review and meta-analysis.

    Science.gov (United States)

    Rosa, Wellington Luiz de Oliveira da; Piva, Evandro; Silva, Adriana Fernandes da

    2015-07-01

    A systematic review was conducted to determine whether the etch-and-rinse or self-etching mode is the best protocol for dentin and enamel adhesion by universal adhesives. This report followed the PRISMA Statement. A total of 10 articles were included in the meta-analysis. Two reviewers performed a literature search up to October 2014 in eight databases: PubMed, Web of Science, Scopus, BBO, SciELO, LILACS, IBECS and The Cochrane Library. In vitro studies evaluating the bond strength of universal adhesives to dentin and/or enamel by the etch-and-rinse and self-etch strategies were eligible to be selected. Statistical analyses were conducted using RevMan 5.1 (The Cochrane Collaboration, Copenhagen, Denmark). A global comparison was performed with random-effects models at a significance level of puniversal adhesives (p≥0.05). However, for the ultra-mild All-Bond Universal adhesive, the etch-and-rinse strategy was significantly different than the self-etch mode in terms of dentin micro-tensile bond strength, as well as in the global analysis of enamel micro-tensile and micro-shear bond strength (p≤0.05). The enamel bond strength of universal adhesives is improved with prior phosphoric acid etching. However, this effect was not evident for dentin with the use of mild universal adhesives with the etch-and-rinse strategy. Selective enamel etching prior to the application of a mild universal adhesive is an advisable strategy for optimizing bonding. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Tensile and erosive strength of soil macro-aggregates from soils under different management system

    Directory of Open Access Journals (Sweden)

    Urbanek Emilia

    2014-12-01

    Full Text Available Reduced soil tillage practices are claimed to improve soil health, fertility and productivity through improved soil structure and higher soil organic matter contents. This study compares soil structure stability of soil aggregates under three different tillage practices: conventional, reduced and no tillage. The erosive strength of soil aggregates has been determined using the abrasion technique with the soil aggregate erosion chambers (SAE. During abrasion soil aggregates have been separated into the exterior, transitional and interior regions. The forces needed to remove the material from the aggregate were calculated as erosive strength and compared with the tensile strength of the aggregates derived from crushing tests. The relationship between aggregate strength and other soil properties such as organic carbon and hydrophobic groups’ content has also been identified.

  18. THE EFFECTS OF WOODEN BOARDS AND ADHESIVE TYPES TO DIAGONAL COMPRESSION AND TENSILE STRENGTHS ON THE BOX CONSTRUCTION

    Directory of Open Access Journals (Sweden)

    Mustafa ALTINOK

    2003-01-01

    Full Text Available The main factor for furniture manufacturing with box construction is diagonal compression or diagonal tensile strength on joint points. This strength differences according to type of wooden board joining style an glue type.In this study, the effects of lathly joining with different glue type on the different wooden board in box construction manufacturing was experimentally tested by diagonal compression and tensile test methods. Finally, it was determined that the diagonal compression and tensile strengths were lower in all lathly joining wooden board with used polyviniyl acetat glue and those were higer with used desmodur-vtka glue.

  19. Assessement of tensile strength of graphites by the Iosipescu coupon test

    Directory of Open Access Journals (Sweden)

    Luis Guilherme Borzani Manhani

    2007-09-01

    Full Text Available Polycrystalline graphites are widely used in the metallurgical, nuclear and aerospace industries. Graphites are particulated composites manufactured with a mixture of coke with pitch, and changes in relative proportions of these materials cause modifications in their mechanical properties. Uniaxial tension tests must be avoided for mechanical characterization in this kind of brittle material, due to difficulties in making the relatively long specimens and premature damages caused during testing set-up. On other types of tests, e.g. bending tests, the specimens are submitted to combined stress states (normal and transverse shear stresses. The Iosipescu shear test, is performed in a beam with two 90° opposite notches machined at the mid-length of the specimens, by applying two forces couples, so that a pure and uniform shear stress state is generated at the cross section between the two notches. When a material is isotropic and brittle, a failure at 45° in relation to the beam long axis can take place, i.e., the tensile normal stress acts parallel to the lateral surface of the notches, controls the failure and the result of the shear test is numerically equivalent to the tensile strength. This work has evaluated a graphite of the type used in rocket nozzles by the Iosipescu test and the resulted stress, ~11 MPa, was found to be equal to the tensile strength. Thus, the tensile strength can be evaluated just by a single and simple experiment, thus avoiding complicated machining of specimen and testing set-up.

  20. Bond strength of orthodontic light-cured resin-modified glass ionomer cement.

    Science.gov (United States)

    Cheng, Hsiang Yu; Chen, Chien Hsiu; Li, Chuan Li; Tsai, Hung Huey; Chou, Ta Hsiung; Wang, Wei Nan

    2011-04-01

    The purpose of this study was to compare the bond strengths and debonded interfaces achieved with light-cured resin-modified glass ionomer cement (RMGIC) and conventional light-cured composite resin. In addition, the effects of acid etching and water contamination were examined. One hundred human premolars were randomly divided into five equal groups. The mini Dyna-lock upper premolar bracket was selected for testing. The first four groups were treated with light-cured RMGIC with or without 15 per cent phosphoric acid-etching treatment and with or without water contamination preceding bracket bonding. The control samples were treated with the conventional light-cured Transbond composite resin under acid etching and without water contamination. Subsequently, the brackets were debonded by tensile force using an Instron machine. The modified adhesive remnant index (ARI) scores were assigned to the bracket base of the debonded interfaces using a scanning electron microscope. The bond strength and modified ARI scores were determined and analysed statistically by one-way analysis of variance and chi-square test. Under all four conditions, the bond strength of the light-cure RMGIC was equal to or higher than that of the conventional composite resin. The highest bond strength was achieved when using RMGIC with acid etching but without water contamination. The modified ARI scores were 2 for Fuji Ortho LC and 3 for Transbond. No enamel detachment was found in any group. Fifteen per cent phosphoric acid etching without moistening the enamel of Fuji Ortho LC provided the more favourable bond strength. Enamel surfaces, with or without water contamination and with or without acid etching, had the same or a greater bond strength than Transbond.

  1. INFLUENCE OF DIFFERENT ADHESIVE SYSTEMS ON THE PULL-OUT BOND STRENGTH OF GLASS FIBER POSTS

    Science.gov (United States)

    da Silva, Luciana Mendonça; de Andrade, Andréa Mello; Machuca, Melissa Fernanda Garcia; da Silva, Paulo Maurício Batista; da Silva, Ricardo Virgolino C.; Veronezi, Maria Cecília

    2008-01-01

    This in vitro study evaluated the tensile bond strength of glass fiber posts (Reforpost – Angelus-Brazil) cemented to root dentin with a resin cement (RelyX ARC – 3M/ESPE) associated with two different adhesive systems (Adper Single Bond - 3M/ESPE and Adper Scotchbond Multi Purpose (MP) Plus – 3M/ESPE), using the pull-out test. Twenty single-rooted human teeth with standardized root canals were randomly assigned to 2 groups (n=10): G1- etching with 37% phosphoric acid gel (3M/ESPE) + Adper Single Bond + #1 post (Reforpost – Angelus) + four #1 accessory posts (Reforpin – Angelus) + resin cement; G2- etching with 37% phosphoric acid gel + Adper Scotchbond MP Plus + #1 post + four #1 accessory posts + resin cement. The specimens were stored in distilled water at 37°C for 7 days and submitted to the pull-out test in a universal testing machine (EMIC) at a crosshead speed of 0.5 mm/min. The mean values of bond strength (kgf) and standard deviation were: G1- 29.163 ± 7.123; G2- 37.752 ±13.054. Statistical analysis (Student's t-test; α=0.05 showed no statistically significant difference (ppost space when Single Bond was used (G1). The type of adhesive system employed on the fiber post cementation did not influence the pull-out bond strength. PMID:19089224

  2. Effect of cement types on the tensile strength of metallic crowns submitted to thermocycling

    Directory of Open Access Journals (Sweden)

    Consani Simonides

    2003-01-01

    Full Text Available The relationship between metallic cast crowns and tensile strength according to cement types submitted to thermocycling was studied. Seventy-two metallic crowns were cast with Verabond II Ni-Cr alloy and cemented in standardized preparations with 10º tapering. Three types of finishing line (45-degree chamfered, 20-degree bevel shoulder and right shoulder were made with diamond burs on bovine teeth. Twenty-four metallic crowns in each group were randomly subdivided into three subgroups of 8 samples each according to the cement used: SS White zinc phosphate cement, Vitremer resin-modified glass ionomer cement, and Rely X resin cement and were submitted to thermocycling. Retention was evaluated according to tensile load required to displace the metallic cast crowns from tooth preparations with an Instron testing machine. ANOVA and Tukey's test showed a statistically significant difference among luting materials, with greater results for Rely X resin cement (24.9 kgf followed by SS White zinc phosphate cement (13.3 kgf and Vitremer resin-modified glass ionomer cement (10.1 kgf. The finishing line types did not influence the tensile resistance of the crowns fixed with the three cements. Increased tensile resistance of metallic crowns fixed on bovine teeth was obtained with resin cement, independent of the finishing line types.

  3. Evaluation of microtensile bond strength of total-etch, self-etch, and glass ionomer adhesive to human dentin: An in vitro study

    Directory of Open Access Journals (Sweden)

    Neelima Lakshmi

    2008-01-01

    Full Text Available Aim: To evaluate the microtensile bond strength of Single Bond, AdheSE, and Fuji Bond LC to human dentin. Fifteen non-carious third molars were selected for the study. The teeth were randomly divided into three groups of five teeth each. Each group was given a different bonding treatment. Group I was treated with Single Bond (3M, ESPE, group II with AdheSE (Ivoclar, Vivadent, and group III was treated with Fuji Bond LC (GC America. A T-band metal matrix was placed and composite resin bonded on to the tooth surface using appropriate bonding agents. The composite resin was packed in increments and light cured. Each tooth was sectioned to obtain 1 mm x 1 mm beams of dentin-resin samples. Tensile bond testing was done using a universal testing machine (Instron at a cross-head speed of 0.5 mm/min. Results: The mean bond strength of Single Bond (35.5 MPa was significantly higher than that of AdheSE (32.8 MPa and Fuji Bond LC (32.6 MPa. The difference between the microtensile bond strength values of AdheSE and Fuji Bond LC was statistically insignificant. Inference: Though the bond strength of AdheSE and Fuji Bond LC was above 30 MPa, it was less than that of Single Bond as evaluated by testing of microtensile bond strength.

  4. Strength, acoustic evaluation and metallurgy of diffusion bonds

    Energy Technology Data Exchange (ETDEWEB)

    Buck, O.; Ojard, G.C.

    1993-10-01

    This paper discusses our efforts on two model systems to determine the bond strength, its correlation to acoustic NDE and the metallurgy involved in the process. Results indicate that the total acoustic energy, reflected from the original interface, can differentiate between the various bond strengths achieved. However, depending on types of materials to be joined, the atomistic processes, leading to a variety of microstructures in the bond planes, can become quite complex and strongly dominate the mechanical properties of such bonds. Origin of failure initiating defects is discussed.

  5. Finite Element Modelling for Tensile Behaviour of Thermally Bonded Nonwoven Fabric

    Directory of Open Access Journals (Sweden)

    Gao Xiaoping

    2015-03-01

    Full Text Available A nonwoven fabric has been widely used in geotextile engineering in recent years; its tensile strength is an important behaviour. Since the fibre distributions in nonwoven fabrics are random and discontinuous, the unit-cell model of a nonwoven fabric cannot be developed to simulate its tensile behaviour. This article presents our research on using finite element method (FEM to study the tensile behaviour of a nonwoven fabric in macro-scale based on the classical laminate composite theory. The laminate orientation was considered with orientation distribution function of fibres, which has been obtained by analysing the data acquired from scanning electron microscopy with Hough Transform. The FE model of a nonwoven fabric was developed using ABAQUS software; the required engineering constants of a nonwoven fabric were obtained from experimental data. Finally, the nonwoven specimens were stretched along with machine direction and cross direction. The experimental stress-strain curves were compared with the results of FE simulations. The approximate agreement proves the validity of an FE model, which could be used to precisely simulate the stress relaxation, strain creep, bending and shear property of a nonwoven fabric.

  6. Improved tensile strength of glycerol-plasticized gluten bioplastic containing hydrophobic liquids.

    Science.gov (United States)

    Song, Yihu; Zheng, Qiang

    2008-11-01

    The aim of the present work has been to study the influence of hydrophobic liquids on the morphology and the properties of thermo-molded plastics based on glycerol-plasticized wheat gluten (WG). While the total amount of castor oil and glycerol was remained constant at 30 wt%, castor oil with various proportions with respect to glycerol was incorporated with WG by mixing at room temperature and the resultant mixtures were thermo-molded at 120 degrees C to prepare sheet samples. Moisture absorption, morphology, dynamic mechanical properties, and tensile properties (Young's modulus, tensile strength and elongation at break) of the plastics were evaluated. Experimental results showed that the physical properties of WG plastic were closely related to glycerol to castor oil ratio. Increasing in castor oil content reduces the moisture absorption markedly, which is accompanied with a significant improvement in tensile strength and Young's modulus. These observations were further confirmed in 24 wt% glycerol-plasticized WG plastics containing 6 wt% silicone oil or polydimethylsiloxane (PDMS) liquid rubber.

  7. Effect of Fiber Waviness on Tensile Strength of a Flax-Sliver-Reinforced Composite Material

    Directory of Open Access Journals (Sweden)

    Taweesak Piyatuchsananon

    2015-01-01

    Full Text Available Recently, a composite material made from natural fibers and biodegradable resin, “green composite,” is attracting attention as an alternative composite material for the replacement of glass fiber-reinforced plastics. Plant-based natural fibers such as kenaf and flax have already been used as composite reinforcement materials because they are more environmentally friendly and costless fibers than artificial fibers. A problem of using natural fibers is the fiber waviness, which affects the tensile properties. Fiber waviness is fluctuation in the fiber orientation that is inherent in the sliver morphology of plant-based natural fibers. This study was conducted to clarify the relation between quantified parameters of fiber waviness and a composite’s tensile strength. First, the fiber orientation angles on a flax-sliver-reinforced composite were measured. Then the angle distribution was quantified through spatial autocorrelation analysis methods: Local Moran’s I and Local Geary’s c. Finally, the relation between the resultant tensile strength and quantified parameters was discussed.

  8. Alternate Method for Determination of Glue-line Tensile Strength of Spliced Veneers in Czech Republic

    Directory of Open Access Journals (Sweden)

    Pavel Král

    2015-01-01

    Full Text Available Quality control is a crucial part of any manufacturing unit, as it assures compliance to established standards as well as maintenance of product quality for internal management purposes. Quality control of spliced veneer in Czech wood based industries is mainly based on ČSN 49 2315 and ČSN 49 2320 standards, which rely on measurement of crack length in finished product. This method has been satisfactorily used since 1985 but requirements of wood based industry has changed a lot in these years. We propose an alternate method for mesurement of tensile strength of spliced veneers. Samples of specified size spliced were taken as mentioned in details and they were subjected to tensile stength measurement. An addtional adhesive tape was used to avoid intra-material fibres disjointing, so that inter-material tensile strength can be measured for spliced veneers. This test can be used for on – site optimization of splicing machine units as well as regular quality control of spliced venners.

  9. Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling

    Science.gov (United States)

    Zinszner, Jean-Luc; Erzar, Benjamin; Forquin, Pascal

    2017-01-01

    Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 103 to 104 s-1 using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual-Forquin-Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  10. 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)

  11. Effect of Weight Fractions of Jute Fiber on Tensile Strength and Deflection Temperature of Jute Fiber/Polypropylene Composites

    Science.gov (United States)

    Nabila, S.; Juwono, A. L.; Roseno, S.

    2017-05-01

    Jute is one of eco-friendly natural fiber with relatively low cost and high volume production. This study aimed to determine the effect of weight fractions of jute fiber as a reinforcement in polypropylene (PP) to obtain an optimum properties of PP/jute fiber composites. Jute fiber was pre-treated through alkalization. The PP was initially produced by extrusion process, followed by fabricated the composites by compiling the PP matrix and jute fibers into lamina using a hot-press method. The results of tensile test and heat deflection temperature test showed that the addition of 40wt% jute fiber to the PP increased the tensile strength about 19.7 % up to (38.2±4.9)MPa, the Young modulus about 79.8 % up to (3.20±0.26)GPa, and the heat deflection temperature about 143% up to (143.3±1.14)°C compared to pristine PP. Based on Scanning Electron Microscopy observation on the fracture surfaces, it was shown that the mode of failure on the composites failure surfaces was “fiber pull-out”, which due to the poor interface bond between the fiber and the matrix.

  12. Mechanical Behavior of DP980 High Strength Steel Under Dynamic Tensile Tests

    Directory of Open Access Journals (Sweden)

    TIAN Wen-yang

    2017-03-01

    Full Text Available The mechanical behavior and fracture modes of DP980 high strength steels were studied by comparing the results of dynamic tensile tests at strain rates from 10-3s-1 to 103s-1. The results show that the strength of DP980 steel remains almost unchanged and the plasticity decreases by 7.5% as the strain rate increasing from quasi-static(10-3s-1 to 100s-1. When the strain rate increases from 100s-1 to 103s-1, the strength keeps increasing, while the plasticity increases by 14% at the strain rate ranging from 100s-1 to 102s-1, but then follows by a decrease of 24.7% in the range of 102s-1 to 103s-1. The strain rate sensitivity coefficient m increases with the increasing of the strain rate. During the plastic deformation, the multiplication reinforcement of dislocation and the motion resistance due to the acceleration of dislocation in ferrite matrix are the main reasons for the strength enhancement. The plastic deformation concentrates in the ferrite, and the microvoids and cracks propagate along the martensite-ferrite interface. In the thickness direction of specimen, the macrographs of fracture are "V" shape cups when strain rate is lower than 101s-1, but the pure sheer shape with 45° to the tensile direction when strain rate is over 101s-1.

  13. Shear bond strength of veneering porcelain to porous zirconia.

    Science.gov (United States)

    Nakamura, Takashi; Sugano, Tsuyoshi; Usami, Hirofumi; Wakabayashi, Kazumichi; Ohnishi, Hiroshi; Sekino, Tohru; Yatani, Hirofumi

    2014-01-01

    In this study, two types of porous zirconia and dense zirconia were used. The flexural strength of non-layered zirconia specimens and those of the layered zirconia specimens with veneering porcelain were examined. Furthermore, the shear bond strength of veneering porcelain to zirconia was examined. The flexural strength of the non-layered specimens was 1,220 MPa for dense zirconia and 220 to 306 MPa for porous zirconia. The flexural strength of the layered specimens was 360 MPa for dense zirconia and 132 to 156 MPa for porous zirconia, when a load was applied to the porcelain side. The shear bond strength of porcelain veneered to dense zirconia was 27.4 MPa and that of porcelain veneered to porous zirconia was 33.6 to 35.1 MPa. This suggests that the veneering porcelain bonded strongly to porous zirconia although porous zirconia has a lower flexural strength than dense zirconia.

  14. Bond strength tests between silicon wafers and duran tubes (fusion bonded fluidic interconnects)

    NARCIS (Netherlands)

    Fazal, I.; Berenschot, Johan W.; de Boer, J.H.; Jansen, Henricus V.; Elwenspoek, Michael Curt

    2005-01-01

    The fusion bond strength of glass tubes with standard silicon wafers is presented. Experiments with plain silicon wafers and those coated with silicon oxide and silicon nitride are presented. Results obtained are discussed in terms of homogeneity and strength of fusion bond. High pressure testing

  15. Evaluation of shear bond strength of orthodontic brackets bonded with Er-YAG laser etching

    Directory of Open Access Journals (Sweden)

    S Hamid Raji

    2012-01-01

    Results: The mean shear bond strength of the teeth lased with 150 mj was 12.26 ± 4.76 MPa, which was not significantly different from the group with acid etching (15.26 ± 4.16 MPa. Irradiation with 100 mj resulted in mean bond strengths of 9.05 ± 3.16 MPa, which was significantly different from that of acid etching (P < 0.001. Conclusions: laser etching at 150 and 100 mj was adequate for bond strength but the failure pattern of brackets bonded with laser etching is dominantly at adhesive - enamel interface and is not safe for enamel during debonding.

  16. Shear strength of dentin and dentin bonded composites.

    Science.gov (United States)

    Mondragon, E; Söderholm, K J

    2001-01-01

    The objective of this study was to compare the shear strength of dentin with the shear strength of dentin bonded composites, and to determine how variables such as composite strength and blade width used during shear testing influence shear strength values. Dentin test samples (n = 36) were made by milling the anatomical molar crowns to a shape similar to a composite rod bonded to a flat dentin surface. Dentin bonding was accomplished by bonding composites to flat dentin surfaces (n = 72) using Scotchbond MP and Z100 (n = 36) or Silux Plus (n = 36) composites. Shear testing was conducted using a guillotine-like device with a flat blade embracing half the dentin or composite cylinders. The blade thickness was either 0.25, 0.5, 0.75, 1.0, 1.25, or 1.50 mm. Six samples per material and blade thickness were tested. In addition to the above study, the bond strength of Z100 (n = 6) and Silux (n = 6) bonded with Scotchbond MP and tested with an orthodontic edgewire loop were also tested and compared with the bond strength of the Z100 and Silux samples tested with the 0.5 thick blade. All shear testing was done at a load rate of 0.5 mm/min. The results were analyzed using ANOVA and Duncan's multiple range test. The shear strength values when tested with the blades were: dentin = 39.7 +/- 13.0 MPa, Z100 = 29.3 +/- 7.2 MPa, and Silux = 21.1 +/- 4.9 MPa; each group had significantly different values (p bonding agent is significantly lower than the shear strength of dentin. The shear strength depends on testing method (blade vs loop) and composite material.

  17. Comparison of Shear Bond Strengths of three resin systems for a Base Metal Alloy bonded to

    Directory of Open Access Journals (Sweden)

    Jlali H

    1999-12-01

    Full Text Available Resin-bonded fixed partial dentures (F.P.D can be used for conservative treatment of partially edentulous"npatients. There are numerous studies regarding the strength of resin composite bond to base meta! alloys. Shear bond"nstrength of three resin systems were invistigated. In this study these systems consisted of: Panavia Ex, Mirage FLC and"nMarathon V. Thirty base metal specimens were prepared from rexillium III alloy and divided into three groups. Then each"ngroup was bonded to enamel of human extracted molar teeth with these systems. All of specimens were stored in water at"n37ac for 48 hours. A shear force was applied to each specimen by the instron universal testing machine. A statistical"nevaluation of the data using one-way analysis of variance showed that there was highly significant difference (P<0.01"nbetween the bond strengths of these three groups."nThe base metal specimens bonded with panavia Ex luting agent, exhibited the highest mean bond strength. Shear bond"nstrength of the specimens bonded to enamel with Mirage F1C showed lower bond strenght than panavia EX. However, the"nlowest bond strength was obtained by the specimens bonded with Marathon V.

  18. Study of three types of desensitizers in dentin bonding strength.

    Science.gov (United States)

    Cheng, L; Wang, S; Che, Y H; Qian, M

    One hundred and twenty human molars without decay (premolars and complete third molars) freshly extracted for orthodontic purposes were used in the study to explore the impact of application of three kinds of desensitizers on self-etching/all-etching bond strength of dentin. The roots were ground along the cementoenamel junction (CEJ), the residual crowns were divided into two parts along mesial and distal direction, and the enamel layer was removed. The dentin was ground into standard pieces of 3x3x3 mm and then polished using alumina waterproof abrasive paper. Two hundred and forty specimens were divided into two groups according to self-etching bond (OptiBond, iBond, XenoIV) and all-etching bond (OptiBond, iBond, Probond). Each of the two groups were subdivided into three groups with different brands, and then further subdivided into three experimental groups and a control group (10 samples in each final group). The surface of dentin coated with desensitizer was examined using scanning electron microscope. Results showed that only the shear strength of iBond + Ddes + Z100 resin group was lower compared to the control group (P 0.05). The shear strength of Optibond + Gluma, Optibond + Ddes, iBond + Ddes + Z100 resin group in all-etching bond group and the experimental groups in Probond group was lower than in the control group (P 0.05).

  19. Effect of salivary pH on diametral tensile strength of glass ionomer cement coated with coating agent

    Science.gov (United States)

    Farahdillah; Triaminingsih, S.; Eriwati, Y. K.

    2017-08-01

    The aim of this study was to analyze the effect of salivary pH to diametral tensile strength of glass ionomer cement (GIC) coated with a coating agent. GIC specimens coated with varnish and nano-filled coating agent were stored in artificial saliva at pH values of 4.5, 5.5, and 7 for 24 h at 37°C, then the diametral tensile strength was tested by universal testing machine. Results showed that there was no significant difference in the diametral tensile strength of the GIC coated with varnish and nano-filled coating agent with decreasing of salivary pH (p < 0.05). It can be concluded that salivary pH does not affect the diametral tensile strength of GIC coated by varnish or nano-filled coating agent

  20. On the Processing of Spalling Experiments. Part I: Identification of the Dynamic Tensile Strength of Concrete

    Science.gov (United States)

    Forquin, P.; Lukić, B.

    2017-11-01

    The spalling technique based on the use of a single Hopkinson bar put in contact with the tested sample has been widely adopted as a reliable method for obtaining the tensile response of concrete and rock-like materials at strain rates up-to 200 s- 1. However, the traditional processing method, based on the use of Novikov acoustic approach and the rear face velocity measurement, remains quite questionable due to strong approximations of this data processing method. Recently a new technique for deriving cross-sectional stress fields of a spalling sample filmed with an ultra-high speed camera and based on using the full field measurements and the virtual fields method (VFM) was proposed. In the present work, this topic is perused by performing several spalling tests on ordinary concrete at high acquisition speed of 1Mfps to accurately measure the tensile strength, Young's modulus, strain-rate at failure and stress-strain response of concrete at high strain-rate. The stress-strain curves contain more measurement points for a more reliable identification. The observed tensile stiffness is up-to 50% lower than the initial compressive stiffness and the obtained peak stress was about 20% lower than the one obtained by applying the Novikov method. In order to support this claim, numerical simulations were performed to show that the change of stiffness between compression and tension highly affects the rear-face velocity profile. This further suggests that the processing based only on the velocity "pullback" is quite sensitive and can produce an overestimate of the tensile strength in concrete and rock-like materials.

  1. Bulk metallic glass composite with good tensile ductility, high strength and large elastic strain limit.

    Science.gov (United States)

    Wu, Fu-Fa; Chan, K C; Jiang, Song-Shan; Chen, Shun-Hua; Wang, Gang

    2014-06-16

    Bulk metallic glasses exhibit high strength and large elastic strain limit but have no tensile ductility. However, bulk metallic glass composites reinforced by in-situ dendrites possess significantly improved toughness but at the expense of high strength and large elastic strain limit. Here, we report a bulk metallic glass composite with strong strain-hardening capability and large elastic strain limit. It was found that, by plastic predeformation, the bulk metallic glass composite can exhibit both a large elastic strain limit and high strength under tension. These unique elastic mechanical properties are attributed to the reversible B2↔B19' phase transformation and the plastic-predeformation-induced complicated stress state in the metallic glass matrix and the second phase. These findings are significant for the design and application of bulk metallic glass composites with excellent mechanical properties.

  2. Studying of Compressive, Tensile and Flexural Strength of Concrete by Using Steel Fibers

    Directory of Open Access Journals (Sweden)

    Muslim Abdul-Ameer

    2016-12-01

    Full Text Available This research aims to study the effect of adding steel fibers on the mechanical properties of concrete. Steel fiber has a very significant effect on concrete because it delays the propagation of micro cracks that generate due to loading on concrete members such as beams and slabs, therefore ,it increases the strength of concrete. The steel fiber was used in this study as a percentage of the volume of concrete. Mix proportion was 1: 2:4 (cement: sand: gravel by volume for all mixes and using 0% as (control mix,0.1 %,0.2%,0.5 % and 1.0% of steel fibers, these ratios leads to increase the compressive, tensile ,and flexural strength of concrete, where the improvement in flexural strength was significant

  3. Shear bond strength comparison between direct and indirect bonded orthodontic brackets.

    Science.gov (United States)

    Yi, Gia K; Dunn, William J; Taloumis, Louis J

    2003-11-01

    The purpose of this study was to compare the shear bond strength of orthodontic brackets bonded to teeth with either an indirect bonding technique and a new adhesive resin or a direct bonding technique and a light-activated adhesive. Fifty-four extracted premolars were mounted in acrylic blocks and randomly divided into 2 groups (n = 27). In one group, orthodontic brackets were bonded to premolars with an indirect bonding adhesive system; in the other, brackets were bonded with the direct method. Seventy-two hours later, the brackets were placed in a testing machine and subjected to a shear force with a crosshead speed of 1 mm/minute. The mean shear bond strengths for the indirect and direct groups were 11.2 and 10.9 MPa, respectively, both exceeding the minimum shear bond strength range of 5.9 to 7.8 MPa often cited in the literature for clinical success. Data were analyzed with Student t tests. No significant difference in shear bond strength between the 2 groups was detected (P =.76). Resin remnants on orthodontic bracket pads were observed with a dissecting microscope at 30x magnification and scored with a modified adhesive remnant index. There was no significant difference between groups (P >.05). There was also no correlation between shear bond strength and the percentage of adhesive resin remnants left on the orthodontic bracket. Under the conditions of this study, no evidence suggests a difference in shear bond strength of orthodontic brackets bonded to tooth enamel, whether they are bonded with the direct or indirect technique.

  4. Comparison of shear bond strength of orthodontic brackets bonded with halogen and plasma arc light curing.

    Science.gov (United States)

    Toodehzaeim, Mohammad Hossein; Kazemi, Alireza Danesh; Aghili, Hossein Agha; Barzegar, Kazem; Fallahtafti, Taranom

    2012-05-01

    Reduced time and appropriate bond strength of brackets is one of the most important aspects of orthodontic treatments. Prolonged halogen light curing for bonding of brackets is undesirable, so the purpose of this study was to compare the shear bond strength of brackets bonded with halogen light and plasma arc system. MATERIALS AND MEHODS: This was an experimental in vitro study. A total of 60 intact premolar teeth were collected and divided into four groups. Stainless steel orthodontic brackets were bonded to them. In groups 1 and 2, curing was done using halogen light given for 20 seconds from two and four angles. In groups 3 and 4, curing was carried out using the plasma arc system for 6 seconds from two and four angles. The shear bond strength was recorded by Instron. The statistics of ANOVA, Tukey's test, and T-test were used in data analysis. There was a statistically significant difference in shear bond strength among the four groups (P = 0.043) and between group 1 with group 2 (P = 0.035). Yet, there was no statistically significant difference between brackets bonded with plasma arc and those bonded with halogen light or between the two groups of plasma arc. Using the plasma arc system is superior to other methods due to reduced curing time. Also, since in using the halogen light system, an increase in curing periods from different angles resulted in a significant increase in shear bond strength; it is advisable to apply the halogen light from different angles.

  5. Influence of cast surface finishing process on metal-ceramic bond strength

    Directory of Open Access Journals (Sweden)

    Denis Vojvodić,

    2009-08-01

    Full Text Available Aim To investigate the influence of different cast surface finishingprocess on metal-ceramics bond strength.Methods Six Co-Cr alloy sample groups were cast (Wirobond C,BEGO, Bremen, Germany and randomly selected for use in oneof the six different final processing of the casting surface (oxidation,sandblasting with 110 and 250 µm Al2O3, bonding agent,hydrochloric acid solution prior to application of feldspathic ceramic(Duceram Kiss, DeguDent, Hanau-Wolfgang, Germany.The testing was carried out with a tensile testing machine (LRXwith Nexygen software, Lloyd Instr., Fareham, UK (ISO 9693.Results The highest force (66.902 N for the separation of ceramicsmeasured with the sample sandblasted with 250µm Al2O3,oxidised and repeatedly sandblasted with 250 µm, and the lowestforce (36.260 N with the sample treated with hydrochloric acidsolution. With all sample groups except the group with the bondingagent (cohesive fracture, an adhesive fracture of the mediumand an adhesive-cohesive fracture of the peripheral part of thefracture surface were observed. The oxidation, prolonged oxidationand the bonding agent do not influence the bond strength ofthe tested metal-ceramic system.Conclusion Different casting surface treatments have an importantrole on the bond strength of the ceramic-metal interface.

  6. Backbone Hydrogen Bond Strengths Can Vary Widely in Transmembrane Helices.

    Science.gov (United States)

    Cao, Zheng; Hutchison, James M; Sanders, Charles R; Bowie, James U

    2017-08-09

    Although backbone hydrogen bonds in transmembrane (TM) helices have the potential to be very strong due to the low dielectric and low water environment of the membrane, their strength has never been assessed experimentally. Moreover, variations in hydrogen bond strength might be necessary to facilitate the TM helix breaking and bending that is often needed to satisfy functional imperatives. Here we employed equilibrium hydrogen/deuterium fractionation factors to measure backbone hydrogen bond strengths in the TM helix of the amyloid precursor protein (APP). We find an enormous range of hydrogen bond free energies, with some weaker than water-water hydrogen bonds and some over 6 kcal/mol stronger than water-water hydrogen bonds. We find that weak hydrogen bonds are at or near preferred γ-secretase cleavage sites, suggesting that the sequence of APP and possibly other cleaved TM helices may be designed, in part, to make their backbones accessible for cleavage. The finding that hydrogen bond strengths in a TM helix can vary widely has implications for membrane protein function, dynamics, evolution, and design.

  7. Effects of hemostatic agents on shear bond strength of orthodontic ...

    African Journals Online (AJOL)

    Objectives: The aim of this study was to determine the effects of blood contamination and hemostatic agents on shear bond strength (SBS) of brackets and bond failure. Materials and Methods: The study material consisted of 57 freshly extracted human premolar and randomly divided into four groups: Group I, control group ...

  8. Shear bond strength of two adhesive materials to eroded enamel.

    Science.gov (United States)

    Lenzi, Tathiane; Hesse, Daniela; Guglielmi, Camila; Anacleto, Ketlin; Raggio, Daniela Procida

    2013-07-01

    To evaluate the bond strength of one etch-and-rinse adhesive system and one resin-modified glass ionomer cement to sound and eroded enamel. Forty-eight bovine incisors were embedded in acrylic resin and ground to obtain flat buccal enamel surfaces. Half of the specimens were submitted to erosion challenge with pH-cycling model (3x/cola drink for 7 days) to induce eroded enamel. After that, all specimens were randomly assigned according to adhesive material: etch-andrinse adhesive system (Adper Single Bond 2 - 3M ESPE, USA) or resin-modified glass ionomer cement (Vitro Fil LC - DFL, Brazil). The shear bond testing was performed after 24 hours water storage (0.5 mm/min). Shear bond strength means were analyzed by two-way ANOVA and Tukey post hoc tests (p Bond 2 showed the highest bond strength value to eroded enamel (p 0.05). Bond strength of etch-and-rinse adhesive system increases in eroded enamel, while no difference is verified to resin-modified glass ionomer cement. Adhesive materials may be used in eroded enamel without jeopardizing the bonding quality; however it is preferable to use etch-and-rinse adhesive system.

  9. Effect of simulated pulpal pressure on composite bond strength to ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-19

    Oct 19, 2009 ... Bonding to dentin with adhesive systems is affected by the tubular fluid flow induced by pulpal pressure. The aim of this study was to evaluate the effect of simulated pulpal pressure on the microtensile bond strength of an adhesive to dentin surface prepared by laser irradiation. Crowns of twenty human ...

  10. Comparison of bonding strengths of the sapwoods and heartwoods ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-12-17

    Dec 17, 2008 ... type, and environmental conditions affect the bonding strength of the wood material. .... Test procedure of water resistance. Conditioning procedure. Procedures. I (Control). 7 days conditioning at 20 ± 2°C and 65 ± 2% relative humidity ... important qualities of wood materials bonded with adhesives, must.

  11. Effect of simulated pulpal pressure on composite bond strength to ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-19

    Oct 19, 2009 ... adhesive system was used. Key words: Bond strength, laser treatment, pulpal pressure, resin composite. INTRODUCTION. Adhesive techniques have expanded the range of possi- bilities for operative and esthetic dentistry (Kato and. Nakabayashi, 1998). Bonding to enamel is a relatively simple procedure ...

  12. Effect of simulated pulpal pressure on composite bond strength to ...

    African Journals Online (AJOL)

    Bonding to dentin with adhesive systems is affected by the tubular fluid flow induced by pulpal pressure. The aim of this study was to evaluate the effect of simulated pulpal pressure on the microtensile bond strength of an adhesive to dentin surface prepared by laser irradiation. Crowns of twenty human extracted third ...

  13. Bracket bond strength dependence on light power density

    OpenAIRE

    Staudt, Christine Bettina; Krejci, Ivo; Mavropoulos, Anestis

    2006-01-01

    In order to reduce curing time for bracket bonding with light-cured composites, manufacturers increase the power density (PD) of light sources. The present study aims at investigating the relationship between PD and shear bond strength (SBS) at short exposure time.

  14. Investigation of influential factors on the tensile strength of cold recycled mixture with bitumen emulsion due to moisture conditioning

    Directory of Open Access Journals (Sweden)

    Mouhamed Bayane Bouraima

    2017-04-01

    Full Text Available The present study attempts to investigate the effect of moisture conditioning on the indirect tensile strength (ITS of cold recycled mixture with bitumen emulsion. Firstly, samples were prepared using a Superpave gyratory compactor. They were hence conditioned using moisture induced sensitivity tester (MIST device. Factorial design was carried out considering four factors each at two different levels. These factors were specimen thickness, air voids content, pressure and number of cycles. In the MIST device, samples are cyclically subjected to water pressure through the sample pores. The MIST conditioned samples were tested for indirect tensile strength. The analysis of two-level full-factorial designed experiments revealed that all four factors have a negative effect on tensile strength of cold recycled mixture with bitumen emulsion. Specimen thickness was the most significant factor affecting the tensile strength followed by air voids content. In two-factor interaction, specimen thickness-number of cycles, air voids content-pressure, and pressure-number of cycles were significant. The most significant three-factor interaction was specimen thickness-pressure-number of cycles. The results from the study suggest that in measuring tensile strength, the appropriate specimen thickness and air voids content should be selected to quantify the representative tensile strength for in-situ conditions.

  15. Tensile strength of type IV dental stones dried in a microwave oven.

    Science.gov (United States)

    Hersek, Nur; Canay, Senay; Akça, Kivanç; Ciftçi, Yalçin

    2002-05-01

    It is known that drying dental stones in a microwave oven can save time, but the strength of the material may be affected by different drying methods. This study evaluated the diametral tensile strength (DTS) of 5 type IV gypsum products at different time intervals using microwave and air-drying methods. . A total of 300 cylinder specimens were prepared from 5 type IV dental stones (Moldano, Amberok, Herastone, Shera-Sockel, and Fujirock; n = 60 per stone) in accordance with the manufacturers' recommendations. Half of the specimens of each stone (n = 30) were dried in open air within a temperature range of 20 +/- 2 degrees C; the other half (n = 30) underwent initial setting in a silicone rubber mold in open air for 10 minutes and then were dried in a microwave oven for 10 minutes. Within these groups, 10 specimens were tested under diametral compression at each of the following time periods: 30, 60, and 120 minutes after drying. Three-way analysis of variance and Scheffe's post hoc test were performed for statistical comparisons at a significance level of Pmicrowave oven (mean 2.99 MPa) were significantly higher (Pmicrowave oven drying had a positive effect on the diametral tensile strength of 5 type IV dental stones.

  16. Standard test method for splitting tensile strength for brittle nuclear waste forms

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1989-01-01

    1.1 This test method is used to measure the static splitting tensile strength of cylindrical specimens of brittle nuclear waste forms. It provides splitting tensile-strength data that can be used to compare the strength of waste forms when tests are done on one size of specimen. 1.2 The test method is applicable to glass, ceramic, and concrete waste forms that are sufficiently homogeneous (Note 1) but not to coated-particle, metal-matrix, bituminous, or plastic waste forms, or concretes with large-scale heterogeneities. Cementitious waste forms with heterogeneities >1 to 2 mm and 5 mm can be tested using this procedure provided the specimen size is increased from the reference size of 12.7 mm diameter by 6 mm length, to 51 mm diameter by 100 mm length, as recommended in Test Method C 496 and Practice C 192. Note 1—Generally, the specimen structural or microstructural heterogeneities must be less than about one-tenth the diameter of the specimen. 1.3 This test method can be used as a quality control chec...

  17. Experimental study of tensile strength of pharmaceutical tablets: effect of the diluent nature and compression pressure

    Science.gov (United States)

    Juban, Audrey; Briançon, Stéphanie; Puel, François; Hoc, Thierry; Nouguier-Lehon, Cécile

    2017-06-01

    In the pharmaceutical field, tablets are the most common dosage form for oral administration in the world. Among different manufacturing processes, direct compression is widely used because of its economics interest and it is a process which avoids the steps of wet granulation and drying processes. Tablets are composed of at least two ingredients: an active pharmaceutical ingredient (API) which is mixed with a diluent. The nature of the powders and the processing conditions are crucial for the properties of the blend and, consequently, strongly influence the mechanical characteristics of tablets. Moreover, tablets have to present a suitable mechanical strength to avoid crumbling or breaking when handling, while ensuring an appropriate disintegration after administration. Accordingly, this mechanical property is an essential parameter to consider. Experimental results showed that proportion of the diluent, fragmentary (DCPA) or plastic (MCC), had a large influence on the tensile strength evolution with API content as well as the compression load applied during tableting process. From these results a model was developed in order to predict the tensile strength of binary tablets by knowing the compression pressure. The validity of this model was demonstrated for the two studied systems and a comparison was made with two existing models.

  18. Experimental study of tensile strength of pharmaceutical tablets: effect of the diluent nature and compression pressure

    Directory of Open Access Journals (Sweden)

    Juban Audrey

    2017-01-01

    Full Text Available In the pharmaceutical field, tablets are the most common dosage form for oral administration in the world. Among different manufacturing processes, direct compression is widely used because of its economics interest and it is a process which avoids the steps of wet granulation and drying processes. Tablets are composed of at least two ingredients: an active pharmaceutical ingredient (API which is mixed with a diluent. The nature of the powders and the processing conditions are crucial for the properties of the blend and, consequently, strongly influence the mechanical characteristics of tablets. Moreover, tablets have to present a suitable mechanical strength to avoid crumbling or breaking when handling, while ensuring an appropriate disintegration after administration. Accordingly, this mechanical property is an essential parameter to consider. Experimental results showed that proportion of the diluent, fragmentary (DCPA or plastic (MCC, had a large influence on the tensile strength evolution with API content as well as the compression load applied during tableting process. From these results a model was developed in order to predict the tensile strength of binary tablets by knowing the compression pressure. The validity of this model was demonstrated for the two studied systems and a comparison was made with two existing models.

  19. A comparison of bond strength between direct- and indirect-bonding methods.

    Science.gov (United States)

    Linn, Brandon James; Berzins, David W; Dhuru, Virendra B; Bradley, Thomas Gerard

    2006-03-01

    The purpose of this study was to evaluate and compare the shear bond strength and the sites of bond failure for brackets bonded to teeth, using two indirect-bonding material protocols and a direct-bonding technique. Sixty extracted human premolars were collected and randomly divided into three groups. The direct-bonded group (group 1) used a light-cured adhesive and primer (Transbond XT). One indirect-bonded group (group 2) consisted of a chemical-cured primer (Sondhi Rapid Set) and light-cured adhesive (Transbond XT), whereas the other group (group 3) used a light-cured primer (Orthosolo) and adhesive (Enlight LV). Forty hours after bonding, the samples were debonded. Mean shear bond strengths were 16.27, 13.83, and 14.76 MPa for groups 1, 2, and 3, respectively. A one-way analysis of variance showed no significant difference in mean bond strength between groups (P = .21). Furthermore, a Weibull analysis showed all three groups tested provided over a 90% survival rate at normal masticatory and orthodontic force levels. For each tooth, an Adhesive Remnant Index (ARI) score was determined. Group 2 was found to have a significantly lower ARI score (P < .05) compared with groups 1 and 3. In addition, Pearson correlation coefficients indicated no strong correlation between bond strength and ARI score within or across all groups.

  20. Strength of Bond Covenants and Bond Assessment Framework

    Directory of Open Access Journals (Sweden)

    Noel Yahanpath

    2012-06-01

    Full Text Available We examine bond covenants of 29 New Zealand bond issues between 2001 and 2007.Results from the study indicate that protection provided for bondholders is weak and limited.On average, only 2-3 types of covenants are embedded with the issues and only 27% of thesecovenants provide full protection to the bondholders. However, bondholders are not compensated for taking the additional risk. We propose an alternative assessment framework that directly assesses the level of protection offered to bondholders. We calculate thecovenant quality score for the issues and classify them into four levels of protection: very high protection, moderate, low and very low. Recent legislative changes will go some way towards improving investor protection and confidence, but the effect is yet to be seen. This proposed scoring framework can be used by potential investors to complement the traditional credit ratings when making their investment decisions.

  1. Bonding of primed zirconia ceramics: evidence of chemical bonding and improved bond strengths.

    Science.gov (United States)

    Chen, Liang; Suh, Byoung In; Brown, Douglas; Chen, Xinqi

    2012-04-01

    To investigate changes of zirconia surface hydrophobicity (contact angle) following the application of a zirconia primer as a function of post-priming storage period and after exposure to harsh conditions and to analyze whether there is a chemical bond formation between a zirconia primer and zirconia ceramics. Zirconia ceramics were treated with a zirconia primer (ZPrime Plus, Bisco), left undisturbed for specific times (reaction time), followed by ultrasonic cleansing in ethanol or acetone bath, and then contact angles were measured (n = 10). The primed zirconia ceramics were also subjected to harsh conditions (strong acid or boiling water) prior to contact angle testing. The chemical change of zirconia surface with and without being primed was analyzed by time-of-flight secondary ion mass spectroscopy (TOF-SIMS). Shear bond strength (Ultradent jig method) on zirconia surface was tested using different zirconia primers. The data were statistically analyzed using one-way ANOVA and Tukey's post-hoc test with 95% confidence level. The contact angle on the primed zirconia surface (from 56 degrees to 72 degrees for different primers) was significantly higher than that of unprimed zirconia (15 degrees) (P reaction time increased within 5 minutes (increased from 58 degree at 10 seconds, to 72 degrees at 5 minutes). Exposure to harsh conditions (i.e. strong acid or boiling water) exhibited no significant change in contact angle values (P > 0.05). The TOF-SIMS detected fragmentations with mass of 549 and 411, indicating that a chemical group of phosphate monomer(P)-O-Zr existed, which indicated a chemical bond was formed between zirconia and ZPrime Plus. All of the zirconia primers tested in the study significantly improved zirconia bond strengths (4 MPa for unprimed zirconia, and 17-23 MPa for primed zirconia, P < 0.05).

  2. Evaluation of bond strength of a conventional adhesive system in irradiated teeth

    Directory of Open Access Journals (Sweden)

    Emanuel Jordan de CARVALHO

    Full Text Available Abstract Introduction One of the most common treatments of head and neck cancer patients is radiotherapy, a treatment method which uses ionizing radiation beam and destroys tumor cells, minimizing damage to neighbor cells. Purpose To evaluate the bond strength of a conventional adhesive system in irradiated teeth. Method 24 third human molars, 12 of which were randomly exposed to radiation and prepared from the removal of occlusal enamel, then exposed to a flat dentine surface. The adhesive system Stae was applied according to the manufacturer’s instructions. Next, two 2 mm increments of resin were implemented. The samples were hemi sectioned specimens, originating shapped toothpick. To evaluate the bond strength, a micro tensile test was done with 500N load and speed of 0.5 mm/minute. Result There was no statistically significant difference between the bond strength of teeth which were or were not exposed to radiation and which used a conventional adhesive system. Conclusion Although the radiation doses applied may cause some alterations in microscopic range in dental tissues, it can be concluded that these alterations do not influence in the bond strength in dentin of irradiated teeth.

  3. Bond-strength studies for 1-mil-diameter gold wires bonded to hybrid microcircuit substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kan, Y.R.; Prantil, V.C.

    1981-12-01

    Detailed studies of the failure probability for gold wires bonded to multiplexer substrates under severe acceleration in the W79 artillery shell environments were made. The studies included: the calculated resultant pull forces exerted on the bond joints due to the W79 acceleration environments; the suitability of the loop-hook pull tests and the use of the normal Gaussian distribution theory for statistical description of bond strengths; and the probability of failure for gold wires bonded to multiplexer substrates under artillery shell accelerations using fixed angle pull tests and a Weilbull distribution theory for the statistical description. Preliminary statistical analyses of the bond strength data obtained from the conventional loop-hook pull tests for a multiplexer substrate HMC, have shown that the ball bond is strong enough to withstand the 0.17 gram design limit load due to the W79 gun barrel environments with a very low probability of failure. For the wedge bond, however, the results of a statistical analysis for the bond strength agree with experience which shows that the wedge bonds are generally much weaker than ball bonds in multiplexer substrates, and the probability of failure may be high enough to cause a problem. The degradation of the wedge bond strength due to post-assembly testing is significant as indicated by the large increase in probability of failure for the post-assembly-tested wedge bonds. To illustrate this, consider a worst-case example which assumes all wires bonded to the hybrid microcircuit substrates have the same geometry and loading conditions. Assuming the W79 JTA has approximately 2760 of these bonded wires, the probabilities of failure are 0.0179% for virgin wedge bonds and 2.1% for post-assembly-tested wedge bonds.

  4. Evaluation of tensile strength resistance of different biomaterials in calvarial rats

    OpenAIRE

    Sanada,Jefferson Tomio; Ribeiro, Ingrid Webb Josephson; Ribeiro, Cristiane Machado; Kapczinski,Myriam Pereira; do VALLE, Accácio Lins

    2015-01-01

    AIM: The aim of this study was to determine the effect of different grafting materials on bone tensile strength after 6-month wound healing. MATERIAL AND METHODS: Non-critical size defects (3-mm diameter) were created in calvarium of 30 three-month-old Wistar rats. Animals were divided into 3 groups (n=10) treated with different grafting materials: GenOx® (Group 1A); GenMix® (Group 1B); no treatment (blood clot, Group 3). Six months after the surgery, rats were sacrificed; bone specimens were...

  5. Assessment of Bond Strength between Metal Brackets and Non-Glazed Ceramic in Different Surface Treatment Methods

    Directory of Open Access Journals (Sweden)

    I. Harririan

    2010-06-01

    Full Text Available Objective: The aim of this study was to evaluate the bond strength between metal brackets and non-glazed ceramic with three different surface treatment methods.Materials and Methods: Forty-two non-glazed ceramic disks were assigned into three groups. Group I and II specimens were etched with 9.5% hydrofluoric acid. Subsequently in group I, silane and adhesive were applied and in group II, bonding agent was used only.In group III, specimens were treated with 35% phosphoric acid and then silane and adhesive were applied. Brackets were bonded with light-cured composites. The specimens were stored in water in room temperature for 24 hours and then thermocycled 500 times between 5°C and 55°C.Results: The difference of tensile bond strength between groups I and III was not significant(P=0.999. However, the tensile bond strength of group II was significantly lower than groups I, and III (P<0.001. The adhesive remnant index scores between the threegroups had statistically significant differences (P<0.001.Conclusion: With the application of scotch bond multi-purpose plus adhesive, we can use phosphoric acid instead of hydrofluoric acid for bonding brackets to non-glazed ceramic restorations.

  6. Comparison of Effect of C-Factor on Bond Strength to Human Dentin Using Different Composite Resin Materials.

    Science.gov (United States)

    Singh, Thakur Veerandar; Patil, Jaya Prakash; Raju, Rvs Chakradhar; Venigalla, Bhuvan Shome; Jyotsna, S V; Bhutani, Neha

    2015-08-01

    The study was planned to assess the use of low shrinkage composites for restoring cavities with high configuration factor (C-factor) which are subjected to high stresses. The aim of the study was to evaluate the effect of C- factor on tensile bond strength to human dentin using methacrylate based nanohybrid and low shrinkage silorane composite. In this study 40 non carious human molar teeth were selected and assigned into two main groups - cavity (Class I cavity with high C-factor) and flat group (flat surface with low C-factor). Two different composite materials- methacrylate based and silorane low shrinkage composite were used to restore the teeth. Dentin surface was treated, adhesive application was done and composite was applied as per manufacturer's instructions. Samples were stored in distilled water then subjected to tensile bond strength measurement using universal testing machine. Statistical analysis was done using Independent sample t-test. The mean bond strength in methacrylate based and silorane composite was significantly higher in flat preparation (Low C-factor) than cavity preparation. The mean bond strength in both cavity (High C-factor) and flat preparation(Low C-factor) was significantly higher in silorane than in conventional methacrylate based composite. The bond strength of composites to dentin is strongly influenced by C-factor and type of composite resin material used.

  7. Shear bond strength of metallic brackets: influence of saliva contamination

    Directory of Open Access Journals (Sweden)

    Luciana Borges Retamoso

    2009-06-01

    Full Text Available OBJECTIVE: To evaluate the influence of saliva contamination on shear bond strength and the bond failure pattern of 3 adhesive systems (Transbond XT, AdheSE and Xeno III on orthodontic metallic brackets bonded to human enamel. MATERIAL AND METHODS: Seventy-two permanent human molars were cut longitudinally in a mesiodistal direction, producing seventy-two specimens randomly divided into six groups. Each system was tested under 2 different enamel conditions: no contamination and contaminated with saliva. In T, A and X groups, the adhesive systems were applied to the enamel surface in accordance with manufacturer's instructions. In TS, AS and XS groups, saliva was applied to enamel surface followed by adhesive system application. The samples were stored in distilled water at 37ºC for 24 h, and then tested for shear bond strength in a universal testing machine (Emic, DL 2000 running at a crosshead speed of 1 mm/min. After bond failure, the enamel surfaces were observed under an optical microscope at 40x magnification. RESULTS: The control and contaminated groups showed no significant difference in shear bond strength for the same adhesive system. However, shear bond strength of T group (17.03±4.91 was significantly higher than that of AS (8.58±1.73 and XS (10.39±4.06 groups (p<0.05. Regarding the bond failure pattern, TS group had significantly higher scores of no adhesive remaining on the tooth in the bonding area than other groups considering the adhesive remnant index (ARI used to evaluate the amount of adhesive left on the enamel. CONCLUSIONS: Saliva contamination showed little influence on the 24-h shear bond strength of orthodontic brackets.

  8. Chemical structures of adhesion promoting monomers for precious metals and their bond strengths to dental metals.

    Science.gov (United States)

    Kadoma, Yoshinori

    2003-09-01

    Adhesion promoting monomers for dental metals, 5-(4-vinylbenzyl)-2-thiobarbituric acid (5VS), 6- (4-vinylbenzyl-n-propyl) amino-1,3,5-triazine-2,4-dithione (VBATDT) and 9,10-epithiodecyl methacrylate (EP8MA), were synthesized and surface treatment agents were prepared by dissolving each monomer in ethanol or acetone. Four non-precious and three precious metal adherends treated with each agent were butt-jointed together with MMA-PMMA resins. After 2,000 thermal cyclings in water, tensile bond strengths were measured and the percentage of area of cohesive failure after the tensile test was determined. The bond strengths to precious metal alloys generally increased in the order of 5VSBonding durability against water based on overall failure mode analysis was improved in the following order: for precious metal alloys; 5VS

  9. Diode laser irradiation increases microtensile bond strength of dentin

    Directory of Open Access Journals (Sweden)

    Rafael Massunari MAENOSONO

    2015-01-01

    Full Text Available Laser irradiation after the immediate application of dentin bonding systems (DBSs and prior to their polymerization has been proposed to increase bond strength. The objective of this study was to evaluate the effect of diode laser irradiation (λ = 970 nm on simplified DBSs through microtensile bond strength tests. Forty healthy human molars were randomly distributed among four groups (n = 10 according to DBSs used [Adper™ SingleBond 2 (SB and Adper™ EasyOne (EO], and the respective groups were irradiated with a diode laser (SB-L and EO-L. After bonding procedures and composite resin build-ups, teeth were stored in deionized water for 7 days and then sectioned to obtain stick-shaped specimens (1.0 mm2. The microtensile test was performed at 0.5 mm/min, yielding bond strength values in MPa, which were evaluated by two-way ANOVA followed by Tukey’s test (p < 0.05 for individual comparisons. For both adhesive systems, diode laser irradiation promoted significant increases in bond strength values (SB: 33.49 ± 6.77; SB-L: 43.69 ± 8.15; EO: 19.67 ± 5.86; EO-L: 29.87 ± 6.98. These results suggest that diode laser irradiation is a promising technique for achieving better performance of adhesive systems on dentin.

  10. An Experimental Investigation of Silicone-to-Metal Bond Strength in Composite Space Docking System Seals

    Science.gov (United States)

    Gaier, James R.; Siamidis, John; Larkin, Elizabeth M. G.

    2010-01-01

    The National Aeronautics and Space Administration (NASA) is currently developing a new universal docking mechanism for future space exploration missions called the Low Impact Docking System (LIDS). A candidate LIDS main interface seal design is a composite assembly of silicone elastomer seals vacuum molded into grooves in an electroless nickel plated aluminum retainer. The strength of the silicone-tometal bond is a critical consideration for the new system, especially due to the presence of small areas of disbond created during the molding process. In the work presented herein, seal-to-retainer bonds of subscale seal specimens with different sizes of intentional disbond were destructively tensile tested. Nominal specimens without intentional disbonds were also tested. Tension was applied either uniformly on the entire seal circumference or locally in one short circumferential length. Bond failure due to uniform tension produced a wide scatter of observable failure modes and measured load-displacement behaviors. Although the preferable failure mode for the seal-to-retainer bond is cohesive failure of the elastomer material, the dominant observed failure mode under the uniform loading condition was found to be the less desirable adhesive failure of the bond in question. The uniform tension case results did not show a correlation between disbond size and bond strength. Localized tension was found to produce failure either as immediate tearing of the elastomer material outside the bond region or as complete peel-out of the seal in one piece. The obtained results represent a valuable benchmark for comparison in the future between adhesion loads under various separation conditions and composite seal bond strength.

  11. Bond strength investigation of two shot moulded polymer

    DEFF Research Database (Denmark)

    Islam, Mohammad Aminul

    This report on the project “Bond strength investigation of two shot moulded polymers” has been submitted for fulfilling the requirements for the course “Experimental Plastic Technology – 42234” at IPL-DTU. Two shot moulding is a classic manufacturing process to combine two different polymers...... in a single product and it is getting more and more importance day by day. One of the biggest challenges of two shot moulding is to achieve a reasonably good bonding between two polymers. The purpose of this project is to investigate the effects of different process, material and machine parameters...... on the bond strength of two shot moulded polymers. For the experiments two engineering polymers (PS and ABS) were used. After all the experimental work, several parameters were found which could effectively control the bond strength of two shot moulded polymers. This report also presents different aspects...

  12. Carboxyl functionalized carbon fibers with preserved tensile strength and electrochemical performance used as anodes of structural lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Mengjie [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Wang, Shubin, E-mail: shubinwang@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Yu, Yalin; Feng, Qihang; Yang, Jiping; Zhang, Boming [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

    2017-01-15

    Highlights: • Carboxyl functionalized CF is acquired by simple chemical oxidation method. • These CF have preserved the tensile strength, better electrochemical properties. • The presence of H{sub 3}PO{sub 4} prevented the turbostratic carbon from over-oxidization. • There CF can be used as anodes of multifunctional structural battery. • The preservation and improvement is result from the hindered over-oxidization. - Abstract: Carboxyl functionalized carbon fibers with preserved tensile strength and electrochemical properties were acquired through a simple chemical oxidation method, and the proposed underlying mechanism was verified. The surface of carboxyl functionalizing carbon fibers is necessary in acquiring functional groups on the surface of carbon fibers to further improve the thermal, electrical or mechanical properties of the fibers. Functionalization should preserve the tensile strength and electrochemical properties of carbon fibers, because the anodes of structural batteries need to have high strength and electrochemical properties. Functionalized with mixed H{sub 2}SO{sub 4}/HNO{sub 3} considerably reduced the tensile strength of carbon fibers. By contrast, the appearance of H{sub 3}PO{sub 4} preserved the tensile strength of functionalized carbon fibers, reduced the dispersion level of tensile strength values, and effectively increased the concentration of functional acid groups on the surface of carbon fibers. The presence of phosphoric acid hindered the over-oxidation of turbostratic carbon, and consequently preserved the tensile strength of carbon fibers. The increased proportion of turbostratic carbon on the surface of carbon fibers concurrently enhanced the electrochemical properties of carbon fibers.

  13. Shear Bond Strengths of Different Adhesive Systems to Biodentine

    OpenAIRE

    Mesut Enes Odabaş; Mehmet Bani; Resmiye Ebru Tirali

    2013-01-01

    The aim of this study was to measure the shear bond strength of different adhesive systems to Biodentine with different time intervals. Eighty specimens of Biodentine were prepared and divided into 8 groups. After 12 minutes, 40 samples were randomly selected and divided into 4 groups of 10 each: group 1: (etch-and-rinse adhesive system) Prime & Bond NT; group 2: (2-step self-etch adhesive system) Clearfil SE Bond; group 3: (1-step self-etch adhesive systems) Clearfil S3 Bond; group 4: contro...

  14. Effect of irrigation solutions on dentin bonding agents and restorative shear bond strength.

    Science.gov (United States)

    Sung, Eric C; Tai, Eddie T; Chen, Toni; Caputo, Angelo A

    2002-06-01

    The presence of irrigation solution prior to the application of dentin bonding agents may be one source of contamination and may adversely affect bond strength. The purpose of this in vitro investigation was to evaluate the effect of irrigation solutions of different purity levels on the shear bond strength of a hybrid composite to dentin. Forty extracted, intact human molars were hand-scaled. All soft tissue was removed, and the teeth were stored in room-temperature tap water for 1 week. Subsequently, each tooth was embedded in autopolymerizing acrylic resin with the coronal portion exposed. After complete polymerization of the resin, the dentin surfaces were exposed, and the crown was cut longitudinally on all 4 sides to produce flat dentin surfaces for bonding. The prepared specimens were assigned to 4 groups of irrigation solutions: tap water (control), sterile water, 0.9% NaCl irrigation solution, and filtered water. Within each irrigation group were 4 dentin bonding agent subgroups: Prime & Bond NT, One-Step, Single Bond Adhesive, and OptiBond Solo. The dentin surfaces (n = 10 per irrigation/bonding agent pair) were etched with 37% phosphoric acid, rinsed with the assigned irrigation solution for 15 seconds, and then dried. Plastic cylinders (3 mm long x 3 mm inner diameter) were filled with a hybrid composite (Herculite XRV) and bonded to the dentin. Specimens were loaded in a universal testing machine, and shear force was applied to the base of the composite cylinders, parallel to the dentin surfaces, at a crosshead speed of 0.05 in/min until fracture. Failure loads were recorded. Bond strength data were compared with analysis of variance (Pbond strengths for all dentin bonding agents tested. When other irrigation solutions were used, One-Step consistently produced significantly lower bond strengths than other dentin bonding agents (PBond or Single Bond Adhesive. However, when One-Step or Solo was used, irrigation with normal saline significantly reduced

  15. Effect of intracanal medicament on bond strength of fibre posts

    Directory of Open Access Journals (Sweden)

    Huda Melike Bayram

    2016-07-01

    Full Text Available The aim of this study was to evaluate the effect of calcium hydroxide (CH, triple antibiotic paste (TAP and double antibiotic paste (DAP on the push-out bond strengths of three different self-adhesive resin cements. Forty-eight single-rooted human maxillary central incisors were selected. The crowns were removed and the root canals were performed. After the irrigation protocols, the post space was prepared. The teeth were then randomly divided into a control group (no intracanal medicament and three medicament groups (n = 12 for each group. After three weeks, the medicaments were removed using 17% ethylenediaminetetraacetic acid, 2.5% sodium hypochlorite and EndoActivator agitation. The teeth were divided into three subgroups according to the fibre-post luting cement: Maxcem Elite, RelyX Unicem and BisCem. The specimens were sectioned and the push-out test was performed. One-way analysis of variance and Tukey's post hoc tests were used for statistical analyses. Regarding the type of cement, BisCem had significantly lower bond strength values than Maxcem and RelyX. There was no significant difference between the bond strength values of Maxcem and RelyX (p > 0.05. The TAP-RelyX group had the highest bond strength value and the DAP-BisCem group had the lowest bond strength value. RelyX and Maxcem had higher bond strength to root canal dentin than BisCem. The bond strength of BisCem, RelyX and Maxcem was not negatively affected by the use of DAP, CH and TAP as intracanal medicaments.

  16. Tensile Strength and Hardness Correlations with Microscopy in Friction welded Aluminium to Copper

    Science.gov (United States)

    Satish, Rengarajan; Seshagiri Rao, Vaddi; Ananthapadmanaban, Dattaguru; Ravi, Balappa

    2016-01-01

    Aluminium and copper are good conductors of heat and electricity, copper being the better conductor, is a costly metal indeed. On the other hand, aluminium is cheap, easily available and also has a lower density than copper. Hence, worldwide efforts are being made to partially replace copper wire. Solid state welding should be used to join aluminium to copper. This is because the use of fusion welding results in brittle phases formed in the weld interface. One of the solid state welding techniques used for joining aluminium to copper is friction welding. In this paper, an attempt has been made to join aluminium to copper by friction welding by varying the friction welding parameters, namely friction pressure, upset pressure, burn-off length and speed of rotation of the workpiece. Nine different friction welding parameter combinations were used during welding in accordance with ASTM standards and results have been reported. Tensile strength and hardness tests were carried out for each parameter combination. Optimum friction welding parameter combination was identified with respect to tensile strength. Scanning Electron Microscopy and Electron dispersive spectroanalysis were obtained to identify modes of fracture and presence of intermetallic phases for each friction welding combination with the aim to narrow down friction welding parameters that give good properties on the whole.

  17. The tensile strength test of thermoplastic materials based on poly(butylene terephtalate

    Directory of Open Access Journals (Sweden)

    Rzepecka Anna

    2017-01-01

    Full Text Available Thermoplastic composites go toward making an increasingly greater percentage of all manufacturing polymer composites. They have a lot of beneficial properties and their manufacturing using injecting and extrusion methods is a very easy and cheap process. Their properties significantly overtake the properties of traditional materials and it is the reason for their use. Scientists are continuously carrying out research to find new applications of composites materials in new industries, not only in the automotive or aircraft industry. When thermoplastic composites are manufactured a very important factor is the appropriate accommodation of tensile strength to their predestination. Scientists need to know the behaviour of these materials during the impact of different forces, and the factors of working in normal conditions too. The main aim of this article was macroscopic and microscopic analysis of the structure of thermoplastic composites after static tensile strength test. Materials which were analysed were thermoplastic materials which have poly(butylene terephthalate – PBT matrix reinforced with different content glass fibres – from 10% for 30%. In addition, research showed the necessary force to receive fracture and set their distinguishing characteristic down.

  18. VARIANCE ANALYSIS OF WOOL WOVEN FABRICS TENSILE STRENGTH USING ANCOVA MODEL

    Directory of Open Access Journals (Sweden)

    VÎLCU Adrian

    2014-05-01

    Full Text Available The paper has conducted a study on the variation of tensile strength for four woven fabrics made from wool type yarns depending on fiber composition, warp and weft yarns tensile strength and technological density using ANCOVA regression model. In instances where surveyed groups may have a known history of responding to questions differently, rather than using the traditional sharing method to address those differences, analysis of covariance (ANCOVA can be employed. ANCOVA shows the correlation between a dependent variable and the covariate independent variables and removes the variability from the dependent variable that can be accounted by the covariates. The independent and dependent variable structures for Multiple Regression, factorial ANOVA and ANCOVA tests are similar. ANCOVA is differentiated from the other two in that it is used when the researcher wants to neutralize the effect of a continuous independent variable in the experiment. The researcher may simply not be interested in the effect of a given independent variable when performing a study. Another situation where ANCOVA should be applied is when an independent variable has a strong correlation with the dependent variable, but does not interact with other independent variables in predicting the dependent variable’s value. ANCOVA is used to neutralize the effect of the more powerful, non-interacting variable. Without this intervention measure, the effects of interacting independent variables can be clouded

  19. Morphology, Tensile Strength and Oil Resistance of Gum Rubber Sheets Prepared from Lignin Modified Natural Rubber

    Directory of Open Access Journals (Sweden)

    Asrul M.

    2014-07-01

    Full Text Available The paper describes the preparation of lignin filled natural rubber latex composite and its subsequent use to obtain lignin modified rubber. Two types of lignin i.e.: rubber wood and commercial alkali lignin were used as rubber filler. Gum rubber sheets were prepared from the lignin modified rubber and their properties were compared to Standard Malaysian Rubber (SMR 20 and a type of rubber obtained from the coagulation of high ammonia latex. Rubber morphology was investigated using Scanning Electron Microscope on the cross-sectional area of cryo-fractured samples. Oil resistance of the rubber sheets was determined by measuring the mass change before and after ASTM IRM 903 oil immersion, while the tensile strengths were determined according to ASTM D412 standard. Low values of tensile strength obtained for the commercial alkali lignin modified rubber sheet relative to the rest of the rubber samples was attributed to poor lignin dispersion. This occurrence was substantiated by the SEM analysis of cryo-fractured samples where crazes and inhomogeneity was observed. Nonetheless, both lignin modified rubbers exhibited higher level of oil resistance compared to SMR 20. This is due to the nature of lignin as a hydrophilic component and its presence in the rubber matrix complicates the oil diffusion process into rubber.

  20. Tensile strength of glass fiber posts submitted to different surface treatments.

    Science.gov (United States)

    Faria, Maria Isabel A; Gomes, Érica Alves; Messias, Danielle Cristine; Silva Filho, João Manoel; Souza Filho, Celso Bernardo; Paulino, Silvana Maria

    2013-01-01

    The aim of this in vitro study was to evaluate the tensile strength of glass fiber posts submitted to different surface treatments. Forty-eight maxillary canines had their crowns sectioned and root canals endodontically treated. The roots were embedded in acrylic resin and distributed into 3 groups according to the surface treatment: Group I: the posts were treated with silane agent for 30 s and adhesive; Group II: the posts were cleaned with alcohol before treatment with silane agent and adhesive; Group III: the posts were submitted to conditioning with 37% phosphoric acid for 30 s before treatment with silane agent and adhesive. Each group was divided into 2 subgroups for adhesive polymerization or not before insertion into the canal: A - adhesive was not light cured and B - adhesive was light cured. All posts were cemented with Panavia F and the samples were subjected to tensile strength test in a universal testing machine at crosshead speed of 1 mm/min. Data were submitted to one-way ANOVA and Tukey's test at 5% significance level. There was statistically significant difference (p0.05). It was concluded that the products used for cleaning the posts influenced the retention regardless of adhesive light curing.

  1. Effect of High Temperature on Mineralogy, Microstructure, Shear Stiffness and Tensile Strength of Two Australian Mudstones

    Science.gov (United States)

    Liu, Xianfeng; Zhang, Chonglei; Yuan, Shengyang; Fityus, Stephen; Sloan, Scott William; Buzzi, Olivier

    2016-09-01

    This study aims at providing quality experimental data on the effects of temperature on tensile strength and small strain shear stiffness of two Australian mudstones. The objective is to provide multiscale data in view of developing a numerical model that can capture and simulate the complex multiphysics of underground coal fire propagation. Two mudstones were collected in the Hunter Valley, close to a known underground coal fire, referred to as "Burning Mountain." The rock specimens were heated to a range of temperatures (maximum of 900 °C) for 24 h, and the materials were comprehensively characterized by X-ray diffraction, thermal gravimetric analyses, optical microscopy and scanning electron microscopy. In addition, mercury intrusion porosimetry was used in order to track changes in pore size distribution with temperature. Investigations at microscale were complemented by testing at the macroscale. In particular, the paper focuses on the evolution of the tensile strength and small strain shear stiffness as the materials are subjected to heating treatment. Results show that both parameters evolve in a non-monotonic manner with temperature. The observed mechanical responses are fully explained and corroborated by microstructural observations.

  2. Application of ANFIS for analytical modeling of tensile strength of functionally graded steels

    Directory of Open Access Journals (Sweden)

    Ali Nazari

    2012-06-01

    Full Text Available In the present study, the tensile strength of ferritic and austenitic functionally graded steels produced by electroslag remelting has been modeled. To produce functionally graded steels, two slices of plain carbon steel and austenitic stainless steels were spot welded and used as electroslag remelting electrode. Functionally graded steel containing graded layers of ferrite and austenite may be fabricated via diffusion of alloying elements during remelting stage. Vickers microhardness profile of the specimen has been obtained experimentally and modeled with adaptive network-based fuzzy inference systems (ANFIS. To build the model for graded ferritic and austenitic steels, training, testing and validation using respectively 174 and 120 experimental data were conducted. According to the input parameters, in the ANFIS model, the Vickers microhardness of each layer was predicted. A good fit equation which correlates the Vickers microhardness of each layer to its corresponding chemical composition was achieved by the optimized network for both ferritic and austenitic graded steels. Afterwards; the Vickers microhardness of each layer in functionally graded steels was related to the yield stress of the corresponding layer and by assuming Holloman relation for stress-strain curve of each layer, they were acquired. Finally, by applying the rule of mixtures, tensile strength of functionally graded steels configuration was found through a numerical method. The obtained results from the proposed model are in good agreement with those acquired from the experiments.

  3. Effect of Preparation Methods on Crystallization Behavior and Tensile Strength of Poly(vinylidene fluoride) Membranes

    Science.gov (United States)

    Liu, Jie; Lu, Xiaolong; Wu, Chunrui

    2013-01-01

    Poly(vinylidene fluoride) (PVDF) membranes were prepared by non solvent induced phase separation (NIPS), melt spinning and the solution-cast method. The effect of preparation methods with different membrane formation mechanisms on crystallization behavior and tensile strength of PVDF membranes was investigated. Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and X-ray diffraction (XRD) were employed to examine the crystal form of the surface layers and the overall membranes, respectively. Spherulite morphologies and thermal behavior of the membranes were studied by polarized light optical microscopy (PLO) and differential scanning calorimetry (DSC) separately. It was found that the crystallization behavior of PVDF membranes was closely related to the preparation methods. For membranes prepared by the NIPS method, the skin layers had a mixture of α and β phases, the overall membranes were predominantly α phase, and the total crystallinity was 60.0% with no spherulite. For melt spinning membranes, the surface layers also showed a mixture of α and β phases, the overall membranes were predominantly α phase. The total crystallinity was 48.7% with perfect spherulites. Whereas the crystallization behavior of solution-cast membranes was related to the evaporation temperature and the additive, when the evaporation temperature was 140 °C with a soluble additive in the dope solution, obvious spherulites appeared. The crystalline morphology of PVDF exerted a great influence on the tensile strength of the membranes, which was much higher with perfect spherulites. PMID:24957064

  4. Bond strength of a dental leucite-based glass ceramic to a resin cement using different silane coupling agents.

    Science.gov (United States)

    Hooshmand, Tabassom; Matinlinna, Jukka P; Keshvad, Alireza; Eskandarion, Solmaz; Zamani, Fereshteh

    2013-01-01

    To evaluate the effect of different types of novel silane coupling agents with two concentrations on the micro-tensile bond strength of a dental glass ceramic with leucite crystals to a dual-cured resin cement using an optimized method of silane application. Leucite-reinforced feldspathic ceramic blocks were fabricated, wet ground and cleansed. The bonding ceramic surfaces were treated with different organosilane solutions as follows: Control silane: Monobond S; methacryloxypropyltrimethoxy silane and experimental silanes with two concentrations (1.0 and 2.5 vol%): amino, isocyanate, styryl, and acrylate silanes. The silane application method consisted of brush application, hot air drying followed by rinsing with hot water and drying. Then a thin layer of an unfilled resin and a dual-cured resin cement was light-cured on the ceramic surfaces. The resin-ceramic blocks were stored in distilled water at 37°C for 24 h and sectioned to produce beam specimens (n=17) with a 1.0 mm(2) cross-sectional area. Specimens were then subjected to thermocycling and tested in a micro-tensile tester device. Data were analyzed using analysis of variance and Tamhane post-hoc test. The mean micro-tensile bond strength value for the styryl silane was significantly higher (P0.05). The micro-tensile bond strength of the leucite-based dental glass ceramic to a resin cement was affected by the type of silane coupling agent and not by the concentration of silane solutions. The best bond strength overall was achieved by methacryloxypropyltrimethoxysilane and experimental styryl silane solutions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Initial and fatigue bond strengths of nanofilled and conventional composite bonding adhesives.

    Science.gov (United States)

    BenGassem, Afnan A; Georgiou, George; Jones, Steven Peter

    2013-06-01

    To compare the initial and fatigue shear bond strengths of a nanofilled adhesive with a conventional light-cured adhesive in an ex vivo laboratory study. Fifty hydroxyapatite discs were prepared by cold pressing. Using a standardized bonding protocol, 100 Victory series upper left central incisor brackets were bonded to discs with Transbond™ Supreme LV nanofilled composite resin and 100 brackets were bonded to discs with Transbond XT. Fifty brackets from each group were subjected to cyclic loading (5000 cycles at 2 Hz) at 50% of the mean bond strength in a Dartec Series HC10 Testing Machine. Initial (unfatigued) and fatigued bond strengths were determined by applying a shear force at the bracket/substrate interface using a custom-made metal jig in an Instron Universal Testing Machine. RESULTS AND STATISTICAL ANALYSIS: One-way analysis of variance showed that Transbond Supreme LV exhibited higher initial mean bond strength than Transbond XT (P = 0·001). No statistically significant difference was found between the fatigue bond strengths of Transbond Supreme LV and Transbond XT (P = 0·323). Two-way analysis of variance demonstrated statistically significant differences when the effect of the composite resin (P = 0·013) and fatigue (P = 0·017) were considered individually. However, when considered in combination there was no statistical significance (P = 0·09). Kaplan-Meier survival analysis showed superior survival of unfatigued brackets with Transbond Supreme LV, but there was no significant difference between the adhesives after fatiguing. The initial bond strength of Transbond Supreme LV was significantly higher than Transbond XT, while the fatigue bond strengths of both resins were comparable. Overall, Transbond Supreme LV demonstrated superior survival under loading than Transbond XT. However, while this was statistically significant for the initial loading, it was not significant after fatiguing. Although these laboratory findings are

  6. Evaluation of shear bond strength of orthodontic brackets bonded with Er-YAG laser etching

    Science.gov (United States)

    Raji, S. Hamid; Birang, Reza; Majdzade, Fateme; Ghorbanipour, Reza

    2012-01-01

    Background: Based on contradictory findings concerning the use of lasers for enamel etching, the purpose of this study was to investigate the shear bond strength of teeth prepared for bonding with Er-YAG laser etching and compare them with phosphoric acid etching. Materials and Methods: In this in vitro study forty – eight premolars, extracted for orthodontic purposes were randomly divided in to three groups. Thirty-two teeth were exposed to laser energy for 25 s: 16 teeth at 100 mj setting and 16 teeth at 150 mj setting. Sixteen teeth were etched with 37% phosphoric acid. The shear bond strength of bonded brackets with the Transbond XT adhesive system was measured with the Zwick testing machine. Descriptive statistics, Kolmogorov–Smirnov test, of homogeneity of variances, one- way analysis of variances and Tukey's test and Kruskal Wallis were used to analyze the data. Results: The mean shear bond strength of the teeth lased with 150 mj was 12.26 ± 4.76 MPa, which was not significantly different from the group with acid etching (15.26 ± 4.16 MPa). Irradiation with 100 mj resulted in mean bond strengths of 9.05 ± 3.16 MPa, which was significantly different from that of acid etching (P laser etching at 150 and 100 mj was adequate for bond strength but the failure pattern of brackets bonded with laser etching is dominantly at adhesive – enamel interface and is not safe for enamel during debonding. PMID:23087733

  7. Shear bond strength of orthodontic brackets bonded to various esthetic pontic materials.

    Science.gov (United States)

    Maryanchik, Igor; Brendlinger, Eric J; Fallis, Drew W; Vandewalle, Kraig S

    2010-05-01

    In this in-vitro study, we compared the shear bond strengths of orthodontic brackets bonded to various commonly used esthetic pontic materials. Prefabricated denture teeth (acrylic resin, Trubyte, Dentsply, York, Pa) and samples made from Integrity (bis-acryl composite resin, Dentsply Caulk, Milford, Del) and Alike (polymethylmethacrylate resin, GC America, Alsip, Ill) were used to represent the more common esthetic provisional materials. Each material group contained 30 samples; a total of 90 samples were bonded in the same fashion with APC PLUS maxillary lateral incisor brackets (3M Unitek, Monrovia, Calif). Each material group was then divided into 2 testing subgroups. One subgroup was tested for shear bond strength 24 hours after bonding, and the other subgroup was tested after bonding and storage in distilled water at 37 degrees C for a week. Each bracket was loaded perpendicularly in a universal testing machine at a crosshead speed of 1.0 mm per minute until bonding failure. The mean shear bond strength and standard deviation were determined for each group. Analysis of variance (ANOVA, 2-factor and 1-factor) with Tukey HSD post-hoc tests, Student t tests, and Mann-Whitney U tests were used to test the main effects of pontic materials and time of loading (alpha = 0.05). The data were stratified, and 1-way ANOVA tests were performed with the Bonferroni adjustment (alpha = 0.01) to examine the effect of the pontic material on shear bond strength after either 1 day or 7 days of storage. Significant differences were found based on pontic material and time (P material had a significantly higher mean shear bond strength than both Alike and the denture tooth materials (P shear bond strengths compared with the prefabricated denture tooth (P dental practitioner, indications for clinical use are evident with direct applications to multi-disciplinary treatment modalities. Copyright (c) 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights

  8. Influence of Patch Parameters on Adhesively Bonded Composite Repair Under Uniaxial Tensile Loading

    Directory of Open Access Journals (Sweden)

    WANG Yue

    2017-04-01

    Full Text Available A three-dimensional finite element model of the repaired structure was established, by which the impact of patch parameters on effect of one-side boned repaired structure under uniaxial tensile loading was analyzed based on the stress concentration factor (SCF and deflection. The results show that the repair effect is better when the crack length is 3.5 times of the hole diameter, the thickness is 60% to 80% of the hole depth and the lay-up is 0°/90°. Then the finite element results were subjected to the uniaxial tension tests. The failure strength of the repaired plate increases by 10.1% compared with that of the unrepaired plate.

  9. Bond Strength of Composite Resin to Pulp Capping Biomaterials after Application of Three Different Bonding Systems

    Directory of Open Access Journals (Sweden)

    Zahra Jaberi-Ansari

    2013-08-01

    Full Text Available Background and aims. Bonding of composite resin filling materials to pulp protecting agents produces an adhesive joint which is important for the quality of filling as well as success of restoration. We aimed to assess the bond strength of composite resin to three pulp capping biomaterials: Pro Root mineral trioxide aggregate (PMTA, Root MTA (RMTA and calcium enriched mixture (CEM cement, using three bonding systems [a total-etch (Single Bond and two self-etch systems (Protect bond and SE Bond]. Materials and methods. Ninety acrylic molds, each containing a 6×2-mm hole, were divided into 3 groups and filled with PMTA, RMTA and CEM cements. The samples in each experimental group were then randomly divided into 3 subgroups; Single Bond, Protect Bond and SE Bond bonding systems were applied to the tested materials. Cylindrical forms of composite resin (Z100, 2×2 mm were placed onto the samples and cured. Shear bond strength values were measured for 9 subgroups using a universal testing machine. Data were analyzed using two-way ANOVA. Results. The average shear bond strengths of Z100 composite resin after application of Single Bond, Protect Bond and SE Bond systems were as follows; PMTA: 5.1±2.42, 4.56±1.96 and 4.52±1.7; RMTA: 4.71±1.77, 4.31±0.56 and 4.79±1.88; and CEM cement: 4.75±1.1, 4.54±1.59 and 4.64±1.78 MPa, respectively. The type of pulp capping material, bonding system and their interacting effects did not have a significant effect on the bond strengths of composite resin to pulp capping biomaterials. Conclusion. Within the limitations of this in vitro study, bond strength of composite resin to two types of MTA as well as CEM cement were similar following application of the total-etch or self-etch bonding systems.

  10. Effect of Flux Composition on the Percentage Elongation and Tensile Strength of Welds in Submerged Arc Welding

    Directory of Open Access Journals (Sweden)

    Singh Brijpal

    2016-09-01

    Full Text Available This experimental study reveals the effects of CaF2, FeMn and NiO additions to the base fluxes on tensile strength and percentage elongation of the weld metal. The aim of this study is to develop suitable flux for mild steel for high tensile strength, impact strength and ductility. Bead on plate welds were made using submerged arc welding process. Mathematical model for percentage elongation and UTS of mild steel welds were made. The elements transfer to the welds have been correlated with the above mechanical performance characteristics. The effect of oxygen content on weld elongation and UTS also has been deduced. This study shows that CaF2 and NiO are the significant factors for tensile strength while FeMn is not significant for tensile strength. However, for elongation besides CaF2, the interaction of CaF2 and FeMn was also found significant. The effects of basicity index of the flux and carbon equivalent of the welds on tensile strength and percentage elongation of the welds have also been evaluated.

  11. Symbiosis of Arbuscular Mycorrhizal Fungi and Robinia pseudoacacia L. Improves Root Tensile Strength and Soil Aggregate Stability.

    Science.gov (United States)

    Zhang, Haoqiang; Liu, Zhenkun; Chen, Hui; Tang, Ming

    2016-01-01

    Robinia pseudoacacia L. (black locust) is a widely planted tree species on Loess Plateau for revegetation. Due to its symbiosis forming capability with arbuscular mycorrhizal (AM) fungi, we explored the influence of arbuscular mycorrhizal fungi on plant biomass, root morphology, root tensile strength and soil aggregate stability in a pot experiment. We inoculated R. pseudoacacia with/without AM fungus (Rhizophagus irregularis or Glomus versiforme), and measured root colonization, plant growth, root morphological characters, root tensile force and tensile strength, and parameters for soil aggregate stability at twelve weeks after inoculation. AM fungi colonized more than 70% plant root, significantly improved plant growth. Meanwhile, AM fungi elevated root morphological parameters, root tensile force, root tensile strength, Glomalin-related soil protein (GRSP) content in soil, and parameters for soil aggregate stability such as water stable aggregate (WSA), mean weight diameter (MWD) and geometric mean diameter (GMD). Root length was highly correlated with WSA, MWD and GMD, while hyphae length was highly correlated with GRSP content. The improved R. pseudoacacia growth, root tensile strength and soil aggregate stability indicated that AM fungi could accelerate soil fixation and stabilization with R. pseudoacacia, and its function in revegetation on Loess Plateau deserves more attention.

  12. Shear bond strength of four commercial bonding systems to cp Ti.

    Science.gov (United States)

    Fujishima, A; Fujishima, Y; Ferracane, J L

    1995-03-01

    The purpose of this study was to evaluate the bond strength of veneering composite to commercially pure titanium (cp Ti) using several different bonding systems and a post-cure heat treatment. Four commercial bonding systems (Cesead, Kuraray; New Metacolor, Sun Medical; Silicaoater MD, Kulzer; Termoresin LC II, GC) were evaluated. Bonding was attempted with the opaque resin provided by each bonding system as well as with the New Metacolor opaque resin. New Metacolor resin composite was used for the veneering composite. Half of the specimens were subjected to a post-cure heat treatment at 100 degrees C for 30 min. The shear bond strengths were tested after aging the specimens in water at 37 degrees C for 1 d and also after thermocycling for 16.5 d (20,000 cycles). Strong bonds, exceeding 20 MPa, were achieved with all of the bonding systems with the exception of Thermoresin LC II, which is designed for noble metals. Bond strengths were only increased by the post-cure heat treatment for the New Metacolor system. Thermocycling caused a significant reduction in bond strength for the New Metacolor adn the Thermoresin LC II systems. The use of the New Metacolor opaque resin produced increased bonding for the Silicoater MD and the opaque resin produced increased bonding for the Silicoater MD and the Cesead systems, but the effect was eliminated after thermocycling. Strong, durable bonds can be achieved between composite and sandblasted cp Ti, thus enhancing the usefulness of this metal for esthetic resin-veneered crowns and other fixed prosthetics.

  13. Comparison of shear bond strength of aesthetic restorative materials

    Directory of Open Access Journals (Sweden)

    B P Suryakumari Nujella

    2012-01-01

    Full Text Available Aim : The present study was conducted to determine and compare the shear bond strengths of Conventional glass ionomer; Resin-modified glass ionomer; Polyacid-modified composite and Composite Resin, and to assess and determine the mode of failure (adhesive, cohesive, mixed. Materials and Methods : Occlusal dentin of 40 extracted human teeth were randomly divided into four groups of ten teeth, each based on the restorative materials tested as follows: Group I: Conventional Glass Ionomer Cement (Control; Group II: Resin-modified Glass Ionomer Cement; Group III: Polyacid-modified Composite Resin; Group IV: Hybrid Composite Resin. The bonded materials were subjected to shear bond strength (SBS testing in a Instron Universal Testing Machine (UTM at a crosshead speed of 0.5 mm/min. The bond failure location was examined by the use of a stereomicroscope at 10× magnification. The mean SBS of Groups I-IV obtained was 3.81, 9.71, 11.96 and 18.16 MPa, respectively. Comparison of mean shear bond strengths of all groups was done by one way ANOVA test and comparison of means in between groups by the Student′s t test. Conclusion : It is concluded that the compomer restorative materials show higher shear bond strength than conventional glass-ionomer and resin-modified glass-ionomer, but less than composite resin.

  14. Effect of Dentin Wetness on the Bond Strength of Universal Adhesives

    Science.gov (United States)

    Lee, Ji-Hye; Son, Sung-Ae; Jung, Kyoung-Hwa; Kwon, Yong Hoon

    2017-01-01

    The effects of dentin wetness on the bond strength and adhesive interface morphology of universal adhesives have been investigated using micro-tensile bond strength (μTBS) testing and confocal laser scanning microscopy (CLSM). Seventy-two human third molars were wet ground to expose flat dentin surfaces. They were divided into three groups according to the air-drying time of the dentin surfaces: 0 (without air drying), 5, and 10 s. The dentin surfaces were then treated with three universal adhesives: G-Premio Bond, Single Bond Universal, and All-Bond Universal in self-etch or etch-and-rinse mode. After composite build up, a μTBS test was performed. One additional tooth was prepared for each group by staining the adhesives with 0.01 wt % of Rhodamine B fluorescent dye for CLSM analysis. The data were analyzed statistically using ANOVA and Tukey’s post hoc tests (α = 0.05). Two-way ANOVA showed significant differences among the adhesive systems and dentin moisture conditions. An interaction effect was also observed (p adhesives. PMID:29068404

  15. Effect of human urine on the tensile strength of sutures used for hypospadias surgery.

    Science.gov (United States)

    Kerstein, Ryan L; Sedaghati, Tina; Seifalian, Alexander M; Kang, Norbert

    2013-06-01

    Hypospadias is the most common congenital condition affecting between 1 in 250 and 300 live births. Even in experienced hands, surgery to repair this congenital defect can have a high complication rate. Wound dehiscence is reported to occur in 5% and fistula formation in 6%-40% depending on technique. The choice of suture material has been shown to affect the complication rate although there is (currently) no consensus about the best suture material to use. Ideally, the sutures used for urethroplasty should be absorbable while maintaining sufficient mechanical strength to support the wounds until they are self-supporting and able to resist urinary flow. Previous studies have compared the effects of human urine on different suture materials especially catgut. However, catgut is now banned in Europe. Our study examined the tensile and breaking strength as well as rate of degradation for four types of absorbable suture now commonly used for hypospadias repairs in the UK. We examined the effect of prolonged storage (up to 27 days) in human urine on 6/0 gauge Vicryl, Vicryl Rapide, Monocryl and polydioxanone (PDS) sutures. These four suture materials are commonly used by the senior plastic consultant surgeon (NK) for hypospadias repairs. 50 mm sections of these suture materials were stored in either urine or saline as control. At specified time points, each suture was placed in a uniaxial load testing machine to assess the stress-strain profile and the mechanical load required to break the suture was measured. Exposure to urine reduced the tensile and breaking strength of all the suture materials tested. PDS demonstrated the greatest resilience. Vicryl Rapide was the weakest suture and degraded completely by day 6. Vicryl and Monocryl had similar degradation profiles, but Vicryl retained more of its tensile strength for longer. There is a balance to be struck between the duration that a suture material must remain in any surgical wound and the risk that it causes

  16. Limitations of push-out test in bond strength measurement.

    Science.gov (United States)

    Chen, Weng-Pin; Chen, Yen-Yin; Huang, Shih-Hao; Lin, Chun-Pin

    2013-02-01

    The push-out test has been widely performed to measure the bond strength of intracanal materials in dentistry. However, it is difficult to compare equitably the bond strengths from different testing specimens. The aim of this study was to investigate how a specimen's geometric parameters and the elastic moduli of dentin and intracanal filling materials may affect the bond strength measurement. Finite element analysis was used to simulate a push-out test. A base model was established, and 3 parameters were modified: the diameter of the pin, the specimen's thickness, and the elastic modulus of the intracanal filler. The analytic stress results and the calculated bond strengths derived from the original formula for the push-out test were compared at the interfaces. Specifically, the following observations were made: the interfacial stress distributions are mostly unaffected when the ratio of the pin diameter to the specimen's diameter is less than 0.85, and the ratio of the specimen's thickness to the specimen's diameter is greater than 0.6. Two correction factors were suggested for fillers with diverse elastic moduli with respect to the dentin modulus. Two modified formulas for the push-out bond strength test for the test specimens using different bonded composite materials were proposed. The results showed that geometric parameters and materials have certain effects on the push-out bond strength. A more rigorous standard for the push-out test can be established for future applications. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  17. Effect of surface conditioning with airborne-particle abrasion on the tensile strength of polymeric CAD/CAM crowns luted with self-adhesive and conventional resin cements.

    Science.gov (United States)

    Stawarczyk, Bogna; Basler, Tobias; Ender, Andreas; Roos, Malgorzata; Ozcan, Mutlu; Hämmerle, Christoph

    2012-02-01

    Adhesively bonded, industrially polymerized resins have been suggested as definitive restorative materials. It is claimed that such resins present similar mechanical properties to glass ceramic. The purpose of this study was to assess the tensile strength of polymeric crowns after conditioning with 2 different protocols: luted with self-adhesive or with conventional resin cements to dental abutments. Human teeth were prepared for crowns and divided into 13 groups (N=312, n=24 per group). Polymeric crowns were CAD/CAM fabricated and divided into 3 groups depending on different surface conditioning methods: A) No treatment, B) airborne-particle abrasion with 50 μm alumina, and C) airborne-particle abrasion with 110 μm alumina. Thereafter, the crowns were luted on dentin abutments with the following cements: 1) RXU (RelyX Unicem, self-adhesive), 2) GCM (G-Cem, self-adhesive), 3) ACG (artCem GI, conventional), and 4) VAR (Variolink II, conventional). Glass ceramic crowns milled and cemented with dual-polymerized resin cement (Variolink II) served as the control group. The tensile strength was measured initially (n=12) and after aging by mechanical thermocycling loading (1 200 000 cycles, 49 N, 5°C to 50°C) (n=12). The tensile strength (MPa) of all crowns was determined by the pull-off test (Zwick/Roell Z010; Ulm, Germany, 1mm/min). Subsequently, the failure types were classified. Data were analyzed with 2-way and 1-way ANOVA followed by a post hoc Scheffé test and t test (α=.05). No adhesion of the tested cements was observed on unconditioned polymeric CAD/CAM crowns and those luted with VAR. Among the tested cements, GCM showed significantly higher values after airborne-particle abrasion with 110 μm (initial: 2.8 MPa; after aging: 1 MPa) than 50 μm alumina (initial: 1.4 MPa; after aging: 0 MPa). No significant effect was found between 50 and 110 μm particle size alumina in combination with the other 2 cements. After aging, the tensile strength of the crowns

  18. Effects of replacement of binder content on bond strength of mortars

    Directory of Open Access Journals (Sweden)

    E. B. C. Costa

    Full Text Available The reduction of binder content in cementitious systems is an effective way to mitigate environmental impacts without increasing costs. The main purpose of this study is to evaluate the effect of content binder on bond strength of mortar-brick interface. For thus, it was studied mortars produced with two limestone fines with different particle size distribution. The limestone fines were added at rates of 0% to 60% at increments of 15% as partial volume replacement of binder. Mortars were prepared in proportion of 1:3 (binder + limestone: sand in volume. The water content was kept constant and equal to 18% in relation to total weight of solids. The mechanical property of mortars was evaluated by tensile strength and the performance of interface by bond strength tests at 14 days. Results indicate that is possible make mortars with 45% less than binder without reducing bond strength. Thus, the use of appropriate particles of limestone can produce more environmentally friendly concrete and rendering mortars by reducing its binder factor without affecting its performance.

  19. Desensitizing bioactive agents improves bond strength of indirect resin-cemented restorations: preliminary results

    Directory of Open Access Journals (Sweden)

    Fernanda de Carvalho Panzeri Pires-de-Souza

    2007-04-01

    Full Text Available OBJECTIVE: The aim of this study was to assess the bond strength of indirect composite restorations cemented with a resin-based cement associated with etch-and-rinse and self-etching primer adhesive systems to dentin treated or not with a bioactive material. MATERIALS AND METHOD: Twenty bovine incisor crowns had the buccal enamel removed and the dentin ground flat. The teeth were assigned to 4 groups (n=5: Group I: acid etching + Prime & Bond NT (Dentsply; Group II: application of a bioactive glass (Biosilicato®+ acid etching + Prime & Bond NT; Group III: One-up Bond F (J Morita; Group IV: Biosilicato® + One-up Bond F. Indirect composite resin (Artglass, Kulzer cylinders (6x10mm were fabricated and cemented to the teeth with a dual-cure resin-based cement (Enforce, Dentsply. After cementation, the specimens were stored in artificial saliva at 37ºC for 30 days and thereafter tested in tensile strength in a universal testing machine (EMIC with 50 kgf load cell at a crosshead speed of 1 mm/min. Failure modes were assessed under scanning electron microscopy. Data were analyzed statistically by ANOVA and Tukey's test (95% level of confidence. RESULTS: Groups I, II and III had statistically similar results (p>0.05. Group IV had statistically significant higher bond strength means (p<0.05 than the other groups. The analysis of the debonded surfaces showed a predominance of adhesive failure mode for Group III and mixed failure mode for the other groups. CONCLUSION: The use of desensitizing agent did not affect negatively the bonding of the indirect composite restorations to dentin, independently of the tested adhesive systems.

  20. Influence of different adhesive systems on the pull-out bond strength of glass fiber posts

    Directory of Open Access Journals (Sweden)

    Luciana Mendonça da Silva

    2008-06-01

    Full Text Available This in vitro study evaluated the tensile bond strength of glass fiber posts (Reforpost - Angelus-Brazil cemented to root dentin with a resin cement (RelyX ARC - 3M/ESPE associated with two different adhesive systems (Adper Single Bond - 3M/ESPE and Adper Scotchbond Multi Purpose (MP Plus - 3M/ESPE, using the pull-out test. Twenty single-rooted human teeth with standardized root canals were randomly assigned to 2 groups (n=10: G1- etching with 37% phosphoric acid gel (3M/ESPE + Adper Single Bond + #1 post (Reforpost - Angelus + four #1 accessory posts (Reforpin - Angelus + resin cement; G2- etching with 37% phosphoric acid gel + Adper Scotchbond MP Plus + #1 post + four #1 accessory posts + resin cement. The specimens were stored in distilled water at 37°C for 7 days and submitted to the pull-out test in a universal testing machine (EMIC at a crosshead speed of 0.5 mm/min. The mean values of bond strength (kgf and standard deviation were: G1- 29.163 ± 7.123; G2- 37.752 ±13.054. Statistical analysis (Student's t-test; a=0.05 showed no statistically significant difference (p<0.05 between the groups. Adhesive bonding failures between resin cement and root canal dentin surface were observed in both groups, with non-polymerized resin cement in the apical portion of the post space when Single Bond was used (G1. The type of adhesive system employed on the fiber post cementation did not influence the pull-out bond strength.

  1. Influence of different adhesive systems on the pull-out bond strength of glass fiber posts.

    Science.gov (United States)

    da Silva, Luciana Mendonça; Andrade, Andréa Mello de; Machuca, Melissa Fernanda Garcia; da Silva, Paulo Maurício Batista; da Silva, Ricardo Virgolino C; Veronezi, Maria Cecília

    2008-01-01

    This in vitro study evaluated the tensile bond strength of glass fiber posts (Reforpost - Angelus-Brazil) cemented to root dentin with a resin cement (RelyX ARC - 3M/ESPE) associated with two different adhesive systems (Adper Single Bond - 3M/ESPE and Adper Scotchbond Multi Purpose (MP) Plus - 3M/ESPE), using the pull-out test. Twenty single-rooted human teeth with standardized root canals were randomly assigned to 2 groups (n=10): G1- etching with 37% phosphoric acid gel (3M/ESPE) + Adper Single Bond + #1 post (Reforpost - Angelus) + four #1 accessory posts (Reforpin - Angelus) + resin cement; G2- etching with 37% phosphoric acid gel + Adper Scotchbond MP Plus + #1 post + four #1 accessory posts + resin cement. The specimens were stored in distilled water at 37 degrees C for 7 days and submitted to the pull-out test in a universal testing machine (EMIC) at a crosshead speed of 0.5 mm/min. The mean values of bond strength (kgf) and standard deviation were: G1- 29.163 +/- 7.123; G2- 37.752 +/-13.054. Statistical analysis (Student's t-test; a=0.05 showed no statistically significant difference (p<0.05) between the groups. Adhesive bonding failures between resin cement and root canal dentin surface were observed in both groups, with non-polymerized resin cement in the apical portion of the post space when Single Bond was used (G1). The type of adhesive system employed on the fiber post cementation did not influence the pull-out bond strength.

  2. Microstructure, Tensile Strength and Probabilistic Fatigue Life Evaluation of Gray Cast Iron

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Yong Hyeon; Han, Seung-Wook; Choi, Nak-Sam [Hanyang Univ., Seoul (Korea, Republic of)

    2017-08-15

    High-grade gray cast iron (HCI350) was prepared by adding Cr, Mo and Cu to the gray cast iron (GC300). Their microstructure, mechanical properties and fatigue strength were studied. Cast iron was made from round bar and plate-type castings, and was cut and polished to measure the percentage of each microstructure. The size of flake graphite decreased due to additives, while the structure of high density pearlite increased in volume percentage improving the tensile strength and fatigue strength. Based on the fatigue life data obtained from the fatigue test results, the probability - stress - life (P-S-N) curve was calculated using the 2-parameter Weibull distribution to which the maximum likelihood method was applied. The P-S-N curve showed that the fatigue strength of HCI350 was significantly improved and the dispersion of life data was lower than that of GC300. However, the fatigue life according to fatigue stress alleviation increased further. Data for reliability life design was presented by quantitatively showing the allowable stress value for the required life cycle number using the calculated P-S-N curve.

  3. Effect of cement shade and light-curing unit on bond strength of a ceramic cemented to dentin.

    Science.gov (United States)

    de Castro, Humberto Lago; Passos, Sheila Pestana; Zogheib, Lucas Villaça; Bona, Alvaro Della

    2012-04-01

    To evaluate the effect of cement shade, light-curing unit, and water storage on tensile bond strength (σ) of a feldspathic ceramic resin bonded to dentin. The dentin surface of 40 molars was exposed and etched with 37% phosphoric acid, then an adhesive system was applied. Forty blocks of feldspathic ceramic (Vita VM7) were produced. The ceramic surface was etched with 10% hydrofluoric acid for 60 s, followed by the application of a silane agent and a dual-curing resin cement (Variolink II). Ceramic blocks were cemented to the treated dentin using either A3 or transparent (Tr) shade cement that was activated using either halogen or LED light for 40 s. All blocks were stored in 37°C distilled water for 24 h before cutting to obtain non-trimmed bar-shaped specimens (adhesive area = 1 mm2 ± 0.1) for the microtensile bond strength test. The specimens were randomly grouped according to the storage time: no storage or stored for 150 days in 37°C distilled water. Eight experimental groups were obtained (n = 30). The specimens were submitted to the tensile bond strength test using a universal testing machine at a crosshead speed of 1 mm/min. The data were statistically analyzed using ANOVA and Tukey's posthoc tests (a = 0.05). The mean bond strength values were significantly lower for the corresponding water stored groups, except for the specimens using A3 resin cement activated by halogen light. There was no significance difference in mean bond strength values among all groups after water storage. Water storage had a detrimental effect under most experimental conditions. For both cement shades investigated (Tr and A3) under the same storage condition, the light-curing units (QTH and LED) did not affect the mean microtensile bond strengths of resin-cemented ceramic to dentin.

  4. Bonding polycarbonate brackets to ceramic: : Effects of substrate treatment on bond strength

    NARCIS (Netherlands)

    Özcan, Mutlu; Vallittu, Pekka K.; Peltomäki, Timo; Huysmans, Marie-Charlotte; Kalk, Warner

    2004-01-01

    This study evaluated the effects of 5 different surface conditioning methods on the bond strength of polycarbonate brackets bonded to ceramic surfaces with resin based cement. Six disc-shaped ceramic specimens (feldspathic porcelain) with glazed surfaces were used for each group. The specimens were

  5. Effect of bond thickness on fracture and fatigue strength of adhesively bonded composite joints

    Science.gov (United States)

    Mall, S.; Ramamurthy, G.

    1989-01-01

    An experimental investigation of composite to composite bonded joints was undertaken to study the effect of bond thickness on debond growth rate under cyclic loading and critical strain energy release rate under static loading. Double cantilever beam specimens of graphite/epoxy adherends bonded with EC 3445 were tested under mode I loading. A different behavior of fracture and fatigue strength was observed with variation of bondline thickness.

  6. Evaluation of push-out bond strength of surface treatments of two esthetic posts

    Directory of Open Access Journals (Sweden)

    Cherif Adel Mohsen

    2012-01-01

    Conclusions: Glass fiber posts recorded higher bond strength than glass ceramic post to both root canal and resin core. Surface treatments increase bond strength for glass fiber and zirconia ceramic posts to both root canal and resin core. SB+SIC+SC gave higher bond strength than E+SC. Bond strength at the cervical section is higher than at the apical section.

  7. Microshear bond strength between restorative composites and resin cements

    OpenAIRE

    Rubens Nazareno GARCIA; Góes,Mário Fernando de; Giannini,Marcelo

    2008-01-01

    Introduction and objective: The techniques of adhesive cementationhave been widely used in dental restoration. The purpose of this studywas to evaluate the microshear bond strength between restorativecomposites and resin cements. Material and methods: Twenty composites blocks were prepared in order to obtain a flat surface, using 600-grid sandpaper. The samples were randomly divided in four groups(n=15) according to the experimental groups: [1] Z250 block + Single Bond + cylinder of RelyX ARC...

  8. Influence of dentin pretreatment on bond strength of universal adhesives

    OpenAIRE

    Poggio, Claudio; Beltrami, Riccardo; Colombo, Marco; Chiesa, Marco; Scribante, Andrea

    2017-01-01

    Abstract Objective: The purpose of the present study was to compare bond strength of different universal adhesives under three different testing conditions: when no pretreatment was applied, after 37% phosphoric acid etching and after glycine application. Materials and methods: One hundred and fifty bovine permanent mandibular incisors were used as a substitute for human teeth. Five different universal adhesives were tested: Futurabond M+, Scotchbond Universal, Clearfil Universal Bond, G-Prem...

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

    Science.gov (United States)

    Liaqat, Saad; Aljabo, Anas; Khan, Muhammad Adnan; Ben Nuba, Hesham; Bozec, Laurent; Ashley, Paul; Young, Anne

    2015-01-01

    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.

  10. 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.

  11. Shear Bond Strengths of Different Adhesive Systems to Biodentine

    Science.gov (United States)

    Odabaş, Mesut Enes; Bani, Mehmet; Tirali, Resmiye Ebru

    2013-01-01

    The aim of this study was to measure the shear bond strength of different adhesive systems to Biodentine with different time intervals. Eighty specimens of Biodentine were prepared and divided into 8 groups. After 12 minutes, 40 samples were randomly selected and divided into 4 groups of 10 each: group 1: (etch-and-rinse adhesive system) Prime & Bond NT; group 2: (2-step self-etch adhesive system) Clearfil SE Bond; group 3: (1-step self-etch adhesive systems) Clearfil S3 Bond; group 4: control (no adhesive). After the application of adhesive systems, composite resin was applied over Biodentine. This procedure was repeated 24 hours after mixing additional 40 samples, respectively. Shear bond strengths were measured using a universal testing machine, and the data were subjected to 1-way analysis of variance and Scheffé post hoc test. No significant differences were found between all of the adhesive groups at the same time intervals (12 minutes and 24 hours) (P > .05). Among the two time intervals, the lowest value was obtained for group 1 (etch-and-rinse adhesive) at a 12-minute period, and the highest was obtained for group 2 (two-step self-etch adhesive) at a 24-hour period. The placement of composite resin used with self-etch adhesive systems over Biodentine showed better shear bond strength. PMID:24222742

  12. Shear Bond Strengths of Different Adhesive Systems to Biodentine

    Directory of Open Access Journals (Sweden)

    Mesut Enes Odabaş

    2013-01-01

    Full Text Available The aim of this study was to measure the shear bond strength of different adhesive systems to Biodentine with different time intervals. Eighty specimens of Biodentine were prepared and divided into 8 groups. After 12 minutes, 40 samples were randomly selected and divided into 4 groups of 10 each: group 1: (etch-and-rinse adhesive system Prime & Bond NT; group 2: (2-step self-etch adhesive system Clearfil SE Bond; group 3: (1-step self-etch adhesive systems Clearfil S3 Bond; group 4: control (no adhesive. After the application of adhesive systems, composite resin was applied over Biodentine. This procedure was repeated 24 hours after mixing additional 40 samples, respectively. Shear bond strengths were measured using a universal testing machine, and the data were subjected to 1-way analysis of variance and Scheffé post hoc test. No significant differences were found between all of the adhesive groups at the same time intervals (12 minutes and 24 hours (. Among the two time intervals, the lowest value was obtained for group 1 (etch-and-rinse adhesive at a 12-minute period, and the highest was obtained for group 2 (two-step self-etch adhesive at a 24-hour period. The placement of composite resin used with self-etch adhesive systems over Biodentine showed better shear bond strength.

  13. Shear bond strengths of different adhesive systems to biodentine.

    Science.gov (United States)

    Odabaş, Mesut Enes; Bani, Mehmet; Tirali, Resmiye Ebru

    2013-01-01

    The aim of this study was to measure the shear bond strength of different adhesive systems to Biodentine with different time intervals. Eighty specimens of Biodentine were prepared and divided into 8 groups. After 12 minutes, 40 samples were randomly selected and divided into 4 groups of 10 each: group 1: (etch-and-rinse adhesive system) Prime & Bond NT; group 2: (2-step self-etch adhesive system) Clearfil SE Bond; group 3: (1-step self-etch adhesive systems) Clearfil S(3) Bond; group 4: control (no adhesive). After the application of adhesive systems, composite resin was applied over Biodentine. This procedure was repeated 24 hours after mixing additional 40 samples, respectively. Shear bond strengths were measured using a universal testing machine, and the data were subjected to 1-way analysis of variance and Scheffé post hoc test. No significant differences were found between all of the adhesive groups at the same time intervals (12 minutes and 24 hours) (P > .05). Among the two time intervals, the lowest value was obtained for group 1 (etch-and-rinse adhesive) at a 12-minute period, and the highest was obtained for group 2 (two-step self-etch adhesive) at a 24-hour period. The placement of composite resin used with self-etch adhesive systems over Biodentine showed better shear bond strength.

  14. Shear bond strength of hydrophilic adhesive systems to enamel.

    Science.gov (United States)

    Hara, A T; Amaral, C M; Pimenta, L A; Sinhoreti, M A

    1999-08-01

    To compare the enamel shear bond strength of four hydrophilic adhesive systems: one multiple-bottle (Scotchbond Multi-Purpose Plus), two one-bottle (Stae, Single Bond) and one self-etching (Etch & Prime). 120 bovine incisor teeth were obtained, embedded in polyester resin, polished to 600 grit to form standardized enamel surfaces, and randomly assigned to four groups (n = 30). Each adhesive system was used on enamel according to the manufacturer's instructions, and resin-based composite (Z100) cylinders with 3 mm diameter and 5 mm height were bonded. Specimens were stored in humid environment for 1 week, and bond strength was determined using a universal testing machine, at a crosshead speed of 0.5 mm/minute. The mean shear bond strength values (MPa +/- SD) were: Single Bond: 24.28 +/- 5.27 (a); Scotchbond Multi-Purpose Plus: 21.18 +/- 4.35 (ab); Stae: 19.56 +/- 4.71 (b); Etch & Prime 3.0: 15.13 +/- 4.92 (c). ANOVA revealed significant difference in means (P bottle systems.

  15. Dentine bond strength and antimicrobial activity evaluation of adhesive systems.

    Science.gov (United States)

    André, Carolina Bosso; Gomes, Brenda Paula Figueiredo Almeida; Duque, Thais Mageste; Stipp, Rafael Nobrega; Chan, Daniel Chi Ngai; Ambrosano, Glaucia Maria Bovi; Giannini, Marcelo

    2015-04-01

    This study evaluated the dentine bond strength (BS) and the antibacterial activity (AA) of six adhesives against strict anaerobic and facultative bacteria. Three adhesives containing antibacterial components (Gluma 2Bond (glutaraldehyde)/G2B, Clearfil SE Protect (MDPB)/CSP and Peak Universal Bond (PUB)/chlorhexidine) and the same adhesive versions without antibacterial agents (Gluma Comfort Bond/GCB, Clearfil SE Bond/CSB and Peak LC Bond/PLB) were tested. The AA of adhesives and control groups was evaluated by direct contact method against four strict anaerobic and four facultative bacteria. After incubation, according to the appropriate periods of time for each microorganism, the time to kill microorganisms was measured. For BS, the adhesives were applied according to manufacturers' recommendations and teeth restored with composite. Teeth (n=10) were sectioned to obtain bonded beams specimens, which were tested after artificial saliva storage for one week and one year. BS data were analyzed using two-way ANOVA and Tukey test. Saliva storage for one year reduces the BS only for GCB. In general G2B and GCB required at least 24h for killing microorganisms. PUB and PLB killed only strict anaerobic microorganisms after 24h. For CSP the average time to eliminate the Streptococcus mutans and strict anaerobic oral pathogens was 30 min. CSB showed no AA against facultative bacteria, but had AA against some strict anaerobic microorganisms. Storage time had no effect on the BS for most of the adhesives. The time required to kill bacteria depended on the type of adhesive and never was less than 10 min. Most of the adhesives showed stable bond strength after one year and the Clearfil SE Protect may be a good alternative in restorative procedures performed on dentine, considering its adequate bond strength and better antibacterial activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. An in vitro shear bond strength study of enamel/dentin bonding systems on enamel.

    Science.gov (United States)

    Reifeis, P E; Cochran, M A; Moore, B K

    1995-01-01

    The purpose of this study was to compare the enamel shear bond strengths achieved with four acid conditioners employed by current enamel/dentin bonding systems (maleic acid, citric acid, nitric acid, oxalic acid) with a 37% phosphoric acid etching technique. The study also compared enamel shear bond strengths between the manufacturers' enamel/dentin conditioner used with an unfilled enamel bonding resin. The facial surfaces of 135 bovine incisors were ground flat and divided into nine test groups of n=15. Conditioning and bonding procedures were carried out following manufacturers' instructions. The phosphoric acid groups were etched for 15 seconds, rinsed for 30 seconds, and dried for 20 seconds with compressed air. All bonding was accomplished at a constant temperature of 21 degrees C and a relative humidity of 60%. A single composite restorative resin (Z-100) was used with all specimens to eliminate variables between composite materials. All specimens were thermocycled 2500 times (5 to 45 degrees C) and had a total storage time of 21 days prior to shear testing on an Instron at a crosshead speed of 1.0 mm/minute. Shear strengths were calculated by dividing load at failure by specimen area. A light microscope was used to determine failure mode. The data were subjected to Bartlett's test for homogeneity of variance and were found not to be homogeneous. The Welch Test was applied and indicated that the treatments used had influence on bond strength at Pbond strength values between traditional phosphoric acid/enamel bonding resin and Mirage Bond Dentin and Enamel Adhesive, Clearfil Liner Bond System, and Scotchbond Multi-Purpose Dental Adhesive System.

  17. Microtensile bond strength to Er:YAG laser pretreated dentin

    OpenAIRE

    da Graça Lopes, Roberta Marques; Special Laboratory of Lasers in Dentistry (LELO) – Department of Restorative Dentistry – School of Dentistry – University of São Paulo (USP) – São Paulo – SP – Brazil.; Steiner-Oliveira, Carolina; Special Laboratory of Lasers in Dentistry (LELO) – Department of Restorative Dentistry – School of Dentistry – University of São Paulo (USP) – São Paulo – SP – Brazil.; Aranha, Ana Cecília Côrrea; Special Laboratory of Lasers in Dentistry (LELO) – Department of Restorative Dentistry – School of Dentistry – University of São Paulo (USP) – São Paulo – SP – Brazil.; Castellan, Carina Strano; Department of Dental Materials – School of Dentistry – University of São Paulo (USP) – São Paulo – SP – Brazil.; Bello-Silva, Marina Stella; Special Laboratory of Lasers in Dentistry (LELO) – Department of Restorative Dentistry – School of Dentistry – University of São Paulo (USP) – São Paulo – SP – Brazil. Center for Reseacrh and Innovation in Laser – Universidade Nove de Julho – São Paulo – SP – Brazil.; Dias Vieira Júnior, Nilson; Center of Lasers and Applications – Energy and Nuclear Research Institute (IPEN) – São Paulo – SP – Brazil.; de Paula Eduardo, Carlos; Special Laboratory of Lasers in Dentistry (LELO) – Department of Restorative Dentistry – School of Dentistry – University of São Paulo (USP) – São Paulo – SP – Brazil.

    2014-01-01

    Objective: Although the effects of Er:YAG  (erbium:yttrium aluminium garnet) laser on cavity  preparation as well as on dentin bonding to composite  have been described in the literature, the longevity of  this bond is still unknown. So, this study evaluated the  short-term microtensile bond strength to dentin samples  after different protocols of surface treatment. Materials  and Methods: 60 bovine incisors were cleaned, worn  to expose a dentin area and subdivided into groups  according to ...

  18. Hygrothermal effects on the tensile strength of carbon/epoxy laminates with molded edges

    Directory of Open Access Journals (Sweden)

    Cândido Geraldo Maurício

    2000-01-01

    Full Text Available The interlaminar stresses are confined to a region near the free edge. Therefore, the laminate stacking sequence and the free edge finishing are some of the factors that affect the strength of the laminate and limit its life. The use of molded edges eliminates the need for trimming and machining the laminates edges thus improving productivity. However, this fabrication technique may have a detrimental effect on the laminate strength for certain stacking sequences. This effect in the presence of moisture has not been characterized. This work presents the results of a comparative study of the resistance to delamination of laminates with machined edges and molded edges. Additionally, two environmental conditions were considered: dry laminates and laminates saturated with moisture. The tensile strength of the laminates were measured and micrographs were used to analyze the microstructure of the laminates near the free edges. It is concluded that the mechanical properties of advanced composites depend on the environmental conditions and the fabrication techniques used to produce the laminates. Therefore, it is necessary to account for these factors when experimentally determining the design allowables.

  19. Size and strain rate effects in tensile strength of penta-twinned Ag nanowires

    Science.gov (United States)

    Zhang, Xuan; Li, Xiaoyan; Gao, Huajian

    2017-08-01

    Penta-twinned Ag nanowires (pt-AgNWs) have recently attracted much attention due to their interesting mechanical and physical properties. Here we perform large-scale atomistic simulations to investigate the influence of sample size and strain rate on the tensile strength of pt-AgNWs. The simulation results show an apparent size effect in that the nanowire strength (defined as the critical stress for dislocation nucleation) increases with decreasing wire diameter. To account for such size effect, a theoretical model involving the interaction between an emerging dislocation and the twin boundary has been developed for the surface nucleation of dislocations. It is shown that the model predictions are in quantitative agreement with the results from atomistic simulations and previous experimental studies in the literatures. The simulations also reveal that nanowire strength is strain-rate dependent, which predicts an activation volume for dislocation nucleation in the range of 1-10b3, where b is the magnitude of the Burgers vector for a full dislocation.

  20. A COMPARISON OF THE TENSILE STRENGTH OF PLASTIC PARTS PRODUCED BY A FUSED DEPOSITION MODELING DEVICE

    Directory of Open Access Journals (Sweden)

    Juraj Beniak

    2015-12-01

    Full Text Available Rapid Prototyping systems are nowadays increasingly used in many areas of industry, not only for producing design models but also for producing parts for final use. We need to know the properties of these parts. When we talk about the Fused Deposition Modeling (FDM technique and FDM devices, there are many possible settings for devices and models which could influence the properties of a final part. In addition, devices based on the same principle may use different operational software for calculating the tool path, and this may have a major impact. The aim of this paper is to show the tensile strength value for parts produced from different materials on the Fused Deposition Modeling device when the horizontal orientation of the specimens is changed.

  1. [Comparative animal experiments of different tissue adhesives. I. Tensile strength studies. II. Histologic and morphometric studies].

    Science.gov (United States)

    Stephan, E; Buntrock, P; Köhler, S

    1989-01-01

    This paper for the first time presents the results of extensive histological and histomorphometric studies investigating the tensile strength of tissue adhesives in model experiments on animals. The material used in comparative studies were TISSEEL, a human adhesive based on fibrinogen, HISTOACRYL-blue, a cyanoacrylate, and KL-3, a type of urethane adhesive. All the materials used in these studies were shown to be principally suitable as tissue adhesives. TISSEEL, the biological adhesive, was obviously superior to all the other adhesives whereas the two synthetic adhesives HISTOACRYL-blue and KL-3 were found to be roughly equal in their properties. The animal model described in the present paper is recommended for use as a standard technique for testing the suitability of new tissue adhesives.

  2. The assessment of bond strength between heat damaged concrete and high strength fibre reinforced concrete

    Science.gov (United States)

    Zahid, M. Z. A. Mohd; Muhamad, K.

    2017-09-01

    The aim of this study is to assess the bond strength between heat damaged concrete and high strength fibre reinforced concrete (HPFRC). Firstly, this paper presents the various steps taken to prepare the HPFRC with self-compacting property. The minimum targeted slump flow is 600 mm and minimum targeted compressive strength is 80 MPa. The key mix variables considered are such as type of superplasticizer, water cement ratio and silica fume content. Then, the bond strength between the heat damaged concrete with HPFRC was examined. The experimental parameters are heating temperature, surface treatment technique and curing method and the results show that, all experimental parameters are significantly affected the bond strength between heat damaged concrete and HPFRC.

  3. Micro-Raman Vibrational Identification of 10-MDP Bond to Zirconia and Shear Bond Strength Analysis

    Directory of Open Access Journals (Sweden)

    Diego Martins De-Paula

    2017-01-01

    Full Text Available So far, there is no report regarding the micro-Raman vibrational fingerprint of the bonds between 10-methacryloyloxy-decyl dihydrogen phosphate (10-MDP and zirconia ceramics. Thus, the aim of this study was to identify the Raman vibrational peaks related to the bonds of 10-MDP with zirconia, as well as the influence on microshear bond strength. Micro-Raman spectroscopy was employed to assess the vibrational peak of 10-MDP binding to zirconia. Microshear bond strength of the dual-cure resin cement to zirconia with the presence of 10-MDP in composition of experimental ceramic primer and self-adhesive resin cement was also surveyed. Statistical analysis was performed by one-way ANOVA and Tukey’s test (p<0.05. Peaks at 1545 cm−1 and 1562 cm−1 were found to refer to zirconia binding with 10-MDP. The presence of 10-MDP in both experimental ceramic primer and self-adhesive resin cement improved microshear bond strength to zirconia ceramic. It can be concluded that the nondestructive method of micro-Raman spectroscopy was able to characterize chemical bonds of 10-MDP with zirconia, which improves the bond strengths of resin cement.

  4. Effect of robotic manipulation on unidirectional barbed suture integrity: evaluation of tensile strength and sliding force.

    Science.gov (United States)

    Kaushik, Dharam; Clay, Kevin; Hossain, S G M; Park, Eugene; Nelson, Carl A; LaGrange, Chad A

    2012-06-01

    One of the more challenging portions of robot-assisted radical prostatectomy (RARP) is the urethrovesical anastomosis. Because of this, a unidirectional absorbable barbed suture (V-Loc(™)) has been used to complete the anastomosis with better efficiency and less tension. The effect of robotic needle driver manipulation on barbed suture is unknown. Therefore, the aim of this study is to determine whether robotic manipulation decreases the tensile strength and peak sliding force of V-Loc barbed suture. Fifty-six V-Loc sutures were compared with 56 Maxon sutures. All sutures were 3-0 caliber. Half of the sutures in each group were manipulated with a da Vinci(®) robot large needle driver five times over a 5 cm length of suture. The other half was not manipulated. Breaking force was determined by placing sutures in a Bose ElectroForce load testing device. For sliding force testing, 28 V-Loc sutures were manipulated in the same fashion and compared with 28 nonmanipulated V-Loc sutures. Peak force needed to make the suture slip backward in porcine small intestine was determined to be the sliding force. Scanning electron microscopy of the barbs before and after robotic manipulation was also performed. The mean difference in breaking forces for manipulated vs nonmanipulated Maxon sutures was 4.52 N (P=0.004). The mean difference in breaking forces for manipulated vs nonmanipulated V-Loc sutures was 1.30 N (P=0.046). The manipulated V-Loc group demonstrated a lower peak sliding force compared with the nonmanipulated group (0.76 vs 0.88 N, P=0.199). Electron microscopy revealed minor structural damage to the barbs and suture. Tensile strength and peak sliding force of V-Loc suture is decreased by robotic manipulation. This is likely because of structural damage to the suture and barbs. This structural damage, however, is likely not clinically significant.

  5. Tensile Fracture Strength of Brisbane Tuff by Static and Cyclic Loading Tests

    Science.gov (United States)

    Erarslan, N.; Alehossein, H.; Williams, D. J.

    2014-07-01

    This research presents the results of laboratory experiments during the investigation of tensile strength-strain characteristics of Brisbane tuff disc specimens under static and diametral cyclic loading. Three different cyclic loading methods were used; namely, sinusoidal cyclic loading, type I and II increasing cyclic loading with various amplitude values. The first method applied the stress amplitude-cycle number (s-n) curve approach to the measurement of the indirect tensile strength (ITS) and fracture toughness ( K IC) values of rocks for the first time in the literature. The type I and II methods investigated the effect of increasing cyclic loading on the ITS and K IC of rocks. For Brisbane tuff, the reduction in ITS was found to be 30 % under sinusoidal loading, whereas type I and II increasing cyclic loading caused a maximum reduction in ITS of 36 %. The maximum reduction of the static K IC of 46 % was obtained for the highest amplitude type I cyclic loading tested. For sinusoidal cyclic loading, a maximum reduction of the static K IC of 30 % was obtained. A continuous irreversible accumulation of damage was observed in dynamic cyclic tests conducted at different amplitudes and mean stress levels. Scanning electron microscope images showed that fatigue damage in Brisbane tuff is strongly influenced by the failure of the matrix because of both inter-granular fracturing and trans-granular fracturing. The main characteristic was grain breakage under cyclic loading, which probably starts at points of contact between grains and is accompanied by the production of very small fragments, probably due to frictional sliding within the weak matrix.

  6. Comparison of shear bond strength of stainless steel brackets bonded with three light- cured adhesives

    Directory of Open Access Journals (Sweden)

    Zahra Minaei Basharik

    2015-09-01

    Full Text Available Introduction: The bonding process of the brackets to enamel has been a critical issue in orthodontic research. The purpose of this study was to evaluate the shear bond strength of 3 light-cured adhesives (transbond XT, Z250, light bond. Materials &Methods: In this study sixty extracted human premolars were collected and randomly divided into 3 test groups. All teeth were etched by 37% phosphoric acid. In first group brackets were bonded by Transbond XT adhesive, in group two brackets were bonded by Light bond adhesive and in third group were bonded by filtek Z250 composite. All of them were cured with Ortholux xt for 40 seconds.24 hours after thermocycling, Shear Bond Strength (SBS values of these brackets were recorded using a Universal Testing Machine. Adhesive Remnant Index (ARI scores were determined after the failure of the brackets, using Stereo Microscope the data were analyzed using ANOVA and Chi-square tests. Results: Mean shear bond strength of Transbond XT, light bond and Z250 were 28.9±2.25 MPa, 25.06±1.98 MPa and 26.8±2.57 MPa, respectively. No significant difference was observed in the SBS among the groups and a clinically acceptable SBS was found for the three adhesives. ARI scores were not significantly different between the various groups (P>0.05. Conclusion: This study showed that the Z250 can be used as light bond and transbond xt to bond orthodontic brackets and ARI and SBS scores were not significantly different.

  7. Improvement of the bond strength of 4-META/MMA-TBB resin to collagen-depleted dentin.

    Science.gov (United States)

    Soeno, Kohyoh; Suzuki, Shiro; Taira, Yohsuke; Atsuta, Mitsuru

    2005-04-01

    It has been reported that the tensile bond strength between the 4-META/MMA-TBB resin and dentin pretreated with 10% citric/3% ferric chloride solution decreased after immersion in water for 2 years. The current study investigated the effect of an experimental dentin conditioner on the bonding of 4-META/MMA-TBB resin to dentin after thermocycling. The experimental conditioner was an aqueous solution of 10% ascorbic acid and 5% ferric chloride (Exp). Human teeth were prepared to expose flat dentin surfaces. These were treated sequentially with 40% phosphoric acid, 10% sodium hypochlorite, and the experimental conditioner. A commercially available dentin conditioner, an aqueous solution of 10% citric/3% ferric chloride (10-3) was used for a control group. Stainless steel rods were bonded to the pretreated dentin surfaces with the use of the 4-META/MMA-TBB resin. Tensile bond strengths were determined after 0, 5,000, 10,000, 20,000 themocycles. All data were analyzed by ANOVA, and differences among groups were analyzed by Duncan's new multiple range test (n = 10, p adhesive resin and a hybrid layer. The experimental dentin pretreatment improved the bond strength of a 4-META/MMA-TBB resin to human dentin compared to 10-3 treatment after thermocycling. (c) 2004 Wiley Periodicals, Inc.

  8. Effect of Icon and Bond Type on Shear Bond Strength: An In vitro Study

    Directory of Open Access Journals (Sweden)

    Ahmed M Yousif AL-Mayali

    2017-11-01

    Full Text Available Aim: To investigate the differences in SBS of orthodontic brackets after applying a caries resin infiltrant and its relationship to the bond type used. Materials and methods: A total of 48 extracted upper premolar were divided to four groups, and the force required for debonding of brackets was recorded. Residual adhesive material was examined by light microscopy. Statistical analysis was performed included t-test and Chi-square test. Result: The highest bond strength (22.543 MPa was get by use the caries infiltrant with self-etching bond. More residual adhesive was observed on infiltrated enamel surfaces. Conclusion: Acceptable bond strengths were obtained with Icon application as measured in vitro, producing the highest strength of all tested sample when compared with the other adhesive system without Icon.

  9. Tensile strength and impact resistance properties of materials used in prosthetic check sockets, copolymer sockets, and definitive laminated sockets.

    Science.gov (United States)

    Gerschutz, Maria J; Haynes, Michael L; Nixon, Derek M; Colvin, James M

    2011-01-01

    Prosthetic sockets serve as the interface between people with amputations and their prostheses. Although most materials used to make prosthetic sockets have been used for many years, knowledge of these materials' properties is limited, especially after they are subjected to fabrication processes. This study evaluated tensile and impact properties of the current state-of-the-art materials used to fabricate prosthetic check sockets, copolymer sockets, and definitive laminated sockets. Thermolyn Rigid and Orfitrans Stiff check socket materials produced significantly lower tensile strength and impact resistance than polyethylene terephthalate glycol (PETG). Copolymer socket materials exhibited greater resistance to impact forces than the check socket materials but lower tensile strengths than PETG. The heated molding processes, for the check socket and copolymer materials, reduced both tensile strength and elongation at break. Definitive laminated sockets were sorted according to fabrication techniques. Nyglass material had significantly higher elongation, indicating a more ductile material than carbon-based laminations. Carbon sockets with pigmented resin had higher tensile strength and modulus at break than nonpigmented carbon sockets. Elongation at yield and elongation at break were similar for both types of carbon-based laminations. The material properties determined in this study provide a foundation for understanding and improving the quality of prosthetic sockets using current fabrication materials and a basis for evaluating future technologies.

  10. Comparison of the bond strength of stainless steel orthodontic brackets bonded to crown porcelains.

    Science.gov (United States)

    Chay, Siew Han; Wattanapayungkul, Pranee; Yap, Adrian U Jin; Loh, Poey Ling; Chung, Sew Meng

    2005-05-01

    The bond strengths and mode of failure of stainless steel orthodontic brackets bonded to the newer all-ceramic crown systems has not been fully investigated. To compare the shear-peel bond strengths and modes of failure of stainless steel Begg orthodontic brackets bonded to all-ceramic crown systems (Finesse, Empress II) and a conventional feldsphatic crown porcelain (Vita Omega 900). Fifteen flat-surface discs of three crown porcelains (Finesse, Vita Omega 900, Empress II) were made and mounted in acrylic moulds. The discs were pumiced, etched with phosphoric acid, primed with silane, and a flat stainless steel Begg bracket bonded to each disc with a chemical cure composite resin (Unite Bond). The discs were stored for one week in water and debonded with a sheer-peel load in an Instron uniaxial testing system with a crosshead speed of 0.5 mm/min. The composite remnants on the ceramic surfaces were classified using the Adhesive Remnant Index (ARI). The bond strength of Finesse (15.03 +/- 1.90 MPa) was significantly greater (p stainless steel orthodontic brackets bonded to Finesse and Empress II porcelains are clinically acceptable.

  11. Adhesion between glass fiber posts and resin cement: evaluation of bond strength after various pre-treatments.

    Science.gov (United States)

    Sipahi, Cumhur; Piskin, Bulent; Akin, Gulsah E; Bektas, Ozden Ozel; Akin, Hakan

    2014-10-01

    To evaluate surface roughness and bond strength of glass fiber posts to a resin cement after various surface treatments. Sixty individually formed glass fiber posts with a diameter of 1.5 mm and a length of 20 mm were used for this study. They were randomly assigned to six groups of pre-treatment (n = 10/group): Group C, untreated (control); Group SB, sandblasted; Group SC, silica coated; Group HF, hydrofluoric acid-etched; Group N, Nd:YAG laser irradiated; Group E, Er:YAG laser irradiated. Surface roughness of the posts was measured before and after pre-treatment. The posts were then bonded to resin cement and tensile bond strengths were determined in a universal testing machine. For statistical analysis, two-way ANOVA and post-hoc comparison tests (α = 0.05) were performed. The highest bond strength value was observed in group HF, followed by group SC. There was a statistically significant difference in bond strength between group C and groups HF, SC and E (p Posts of group SB and group N showed the highest surface roughness. The findings of the present study reveal that hydrofluoric acid-etching, silica coating and Er:YAG laser irradiation provided a significant increase in bond strength between glass fiber posts and resin cement.

  12. Sorption, Solubility, Bond Strength and Hardness of Denture Soft Lining Incorporated with Silver Nanoparticles

    Science.gov (United States)

    Chladek, Grzegorz; Kasperski, Jacek; Barszczewska-Rybarek, Izabela; Żmudzki, Jarosław

    2013-01-01

    The colonization of denture soft lining material by oral fungi can result in infections and stomatitis of oral tissues. In this study, 0 ppm to 200 ppm of silver nanoparticles was incorporated as an antimicrobial agent into composites to reduce the microbial colonization of lining materials. The effect of silver nanoparticle incorporation into a soft lining material on the sorption, solubility, hardness (on the Shore A scale) and tensile bond strength of the composites was investigated. The data were statistically analyzed using two-way ANOVA and Newman-Keuls post hoc tests or the chi-square Pearson test at the p hardness, an increase in sorption and solubility, a decrease in bond strength and a change in the failure type of the samples. The best combination of bond strength, sorption, solubility and hardness with antifungal efficacy was achieved for silver nanoparticle concentrations ranging from 20 ppm to 40 ppm. These composites did not show properties worse than those of the material without silver nanoparticles and exhibited enhanced in vitro antifungal efficiency. PMID:23271371

  13. 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. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. Influence of ceramic particulate type on microstructure and tensile strength of aluminum matrix composites produced using friction stir processing

    Directory of Open Access Journals (Sweden)

    I. Dinaharan

    2016-06-01

    Full Text Available Friction stir processing (FSP was applied to produce aluminum matrix composites (AMCs. Aluminum alloy AA6082 was used as the matrix material. Various ceramic particles, such as SiC, Al2O3, TiC, B4C and WC, were used as reinforcement particle. AA6082 AMCs were produced using a set of optimized process parameters. The microstructure was studied using optical microscopy, filed emission scanning electron microscopy and electron back scattered diagram. The results indicated that the type of ceramic particle did not considerably vary the microstructure and ultimate tensile strength (UTS. Each type of ceramic particle provided a homogeneous dispersion in the stir zone irrespective of the location and good interfacial bonding. Nevertheless, AA6082/TiC AMC exhibited superior hardness and wear resistance compared to other AMCs produced in this work under the same set of experimental conditions. The strengthening mechanisms and the variation in the properties are correlated to the observed microstructure. The details of fracture mode are further presented.

  15. Microshear bond strength of Nano-Bond adhesive containing nanosized aluminum trioxide particles.

    Science.gov (United States)

    Althomali, Yousef Mohammed; Ebrahim, Mohamed Ismail

    2017-01-01

    The present study was conducted to evaluate the effect of nanosized aluminum trioxide (Al 2 O 3 ) particles when added to the Nano-Bond adhesive system and its effect on the microshear bond strength of nanocomposite resin to dentin. A newly developed adhesive (Nano-Bond) and one type of light-cured resin restorative material (nanocomposite resin) were used in this study. The occlusal surfaces of extracted human molar teeth were ground perpendicular to the long axis of each tooth to expose a flat dentin surface. The adhesives were applied to the dentin surfaces according to manufacturers' instructions. The nanocomposite resin was then placed and light cured for 40 s. After immersion in water at 37°C for 24 h, the specimens were subjected to thermocycling before testing, and a microshear bond test was carried out. The recorded bond strengths (MPa) were collected, tabulated, and statistically analyzed. A one-way analysis of variance and Tukey's tests were used to test for significance between the means of the groups; statistical significance was assumed when the P ≤ 0.05. The mean microshear bond strength of the Nano-Bond adhesive system containing nanosized Al 2 O 3 at a concentration of 2% was 23.15 MPa (Group B), which was significantly greater than that of the Nano-Bond adhesive system without additives (15.03 MPa, Group A). These results indicate that nanosized Al 2 O 3 added to the Nano-Bond adhesive system at a concentration of 2% increases the microshear bond strength.

  16. Expansion of Kolarik model for tensile strength of polymer particulate nanocomposites as a function of matrix, nanoparticles and interphase properties.

    Science.gov (United States)

    Zare, Yasser; Rhee, Kyong Yop

    2017-11-15

    Kolarik proposed a model for tensile strength of polymer particulate composites based on the cubic orthogonal skeleton or three perpendicular plates (3PP) system. In this paper, Kolarik model is expanded for tensile strength of polymer nanocomposites containing spherical nanoparticles assuming the interphase properties. This model expresses the strength as a function of interphase properties. This development is performed using some models such as Pukanszky and Nicolais-Narkis. The expanded model is applied to calculate the thickness and strength of interphase by the experimental results. Furthermore, the strength of polymer nanocomposites is evaluated at different levels of material and interphase properties. The experimental data show good agreement with the predictions of the developed model. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. The effect of intravitreal bevacizumab and ranibizumab on cutaneous tensile strength during wound healing

    Directory of Open Access Journals (Sweden)

    Christoforidis JB

    2013-01-01

    : saline controls, 18.31 ± 0.43; bevacizumab, 11.02 ± 0.45 (P < 0.0001; and ranibizumab, 13.55 ± 0.43 (P < 0.0001. The interobserver correlation coefficient was 0.928.Conclusion: At day 7, both anti–vascular endothelial growth factor (anti-VEGF agents had significantly suppressed MNV scores and exerted a significant reduction of cutaneous wound tensile strength compared with saline controls. At day 14, neither agent produced a significant effect on tensile wound strength. Since angiogenesis is an integral component of the proliferative phase of wound healing, we encourage clinicians to be aware of their patients' recent surgical history during intravitreal anti-VEGF therapy and to consider refraining from their use during the perioperative period.Keywords: wound healing, tensile strength, bevacizumab, ranibizumab

  18. Bond strength between acrylic resin and maxillofacial silicone

    Science.gov (United States)

    HADDAD, Marcela Filié; GOIATO, Marcelo Coelho; dos SANTOS, Daniela Micheline; CREPALDI, Nádia de Marchi; PESQUEIRA, Aldiéris Alves; BANNWART, Lisiane Cristina

    2012-01-01

    The development of implant dentistry improved the possibilities of rehabilitation with maxillofacial prosthesis. However, clinically it is difficult to bond the silicone to the attachment system. Objectives This study aimed to evaluate the effect of an adhesive system on the bond strength between acrylic resin and facial silicone. Material and Methods A total of 120 samples were fabricated with auto-polymerized acrylic resin and MDX 4-4210 facial silicone. Both materials were bonded through mechanical retentions and/or application of primers (DC 1205 primer and Sofreliner primer S) and adhesive (Silastic Medical Adhesive Type A) or not (control group). Samples were divided into 12 groups according to the method used to attach the silicone to the acrylic resin. All samples were subjected to a T-peel test in a universal testing machine. Failures were classified as adhesive, cohesive or mixed. The data were evaluated by the analysis of variance (ANOVA) and the Tukey's HSD test (α=.05). Results The highest bond strength values (5.95 N/mm; 3.07 N/mm; 4.75 N/mm) were recorded for the samples that received a Sofreliner primer application. These values were significantly higher when the samples had no scratches and did not receive the application of Silastic Medical Adhesive Type A. Conclusions The most common type of failure was adhesive. The use of Sofreliner primer increased the bond strength between the auto-polymerized acrylic resin and the Silastic MDX 4-4210 facial silicone. PMID:23329247

  19. Relationship between thin-film bond strength as measured by a scratch test, and indentation hardness for bonding agents.

    Science.gov (United States)

    Kusakabe, Shusuke; Rawls, H Ralph; Hotta, Masato

    2016-03-01

    To evaluate thin-film bond strength between a bonding agent and human dentin, using a scratch test, and the characteristics and accuracy of measurement. One-step bonding agents (BeautiBond; Bond Force; Adper Easy Bond; Clearfil tri-S Bond) and two-step bonding agents (Cleafil SE Bond; FL-Bond II) were investigated in this study. Flat dentin surfaces were prepared for extracted human molars. The dentin surfaces were ground and bonding agents were applied and light cured. The thin-film bond strength test of the specimens was evaluated by the critical load at which the coated bonding agent failed and dentin appeared. The scratch mark sections were then observed under a scanning electron microscope. Indentation hardness was evaluated by the variation in depth under an applied load of 10gf. Data were compared by one-way ANOVA with the Scheffé's post hoc multiple comparison test (phardness were analyzed using analysis of correlation and covariance. The thin-film bond strength of two-step bonding agents were found to be significantly higher than that of one-step bonding agents with small standard deviations. Scratch marks consistently showed adhesive failure in the vicinity of the bonding agent/dentin interface. The indentation hardness showed a trend that two-step bonding agents have greater hardness than one-step bonding agents. A moderately significant correlation (r(2)=0.31) was found between thin-film bond strength and indentation hardness. Thin-film bond strength test is a valid and reliable means of evaluating bond strength in the vicinity of the adhesive interface and is more accurate than other methods currently in use. Further, the thin-film bond strength is influenced by the hardness of the cued bonding agent. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  20. Shear bond strength of orthodontic buccal tubes to porcelain

    Science.gov (United States)

    Purmal, Kathiravan; Alam, Mohammad K.; Sukumaran, Prema

    2013-01-01

    Background: Bonding of molar tubes is becoming more popular in orthodontics. Occasionally, these bonding are done on posterior porcelain crowns or bridges. The purpose of this study was to evaluate the shear bond strength of buccal tubes on feldspathic porcelain crowns with two different methods. Materials and Methods: Forty porcelain right molar crowns were fabricated for this study. The crowns were randomly divided into two groups. In group 1, the crowns were etched with 9.6% hydrofluoric acid, silane coupling agent applied, coated with bonding primer and bonded with Transbond XT (3M Unitek, Monrovia, Calif). In group 2, the crowns were etched with phosphoric acid 37%, silane coupling agent applied, coated with bonding primer and bonded with Transbond XT. All the crowns were stored for 24 hours at 37°C and thermo-cycled before the shear bond test. The analysis of variance (ANOVA) was used to determine whether significant difference were present between the groups. Results: The results of the analysis of variance (F = 0.23) indicated the shear bond strength of group 1 (3.57 ± 0.87 MPa) was not significantly different (P > 0.05) from group 2 (3.46 ± 0.65 Mpa). Fisher's exact test for the adhesive remnant index (ARI) revealed significant difference between both groups (P porcelain/resin interface. Conclusion: Etching with phosphoric acid with the use of silane coupling agent would be safer and should make it easier for clinicians to clean the adhesive on the porcelain surface after debonding. PMID:23878568

  1. Microtensile bond strength between adhesive cements and root canal dentin

    OpenAIRE

    Bouillaguet, Serge; Troesch, Sabra; Wataha, John C.; Krejci, Ivo; Meyer, Jean Marc; Pashley, David H

    2003-01-01

    The hypotheses tested were that the bond strength of adhesive cements to root canal dentin (1) would be reduced as a function of configuration factor, polymerization process and type of luting material and (2) would be lowered near the apex of the tooth.

  2. ADHESIVE SYSTEM AFFECTS REPAIR BOND STRENGTH OF RESIN COMPOSITE

    Directory of Open Access Journals (Sweden)

    Özgür IRMAK

    2017-10-01

    Full Text Available Purpose: This study evaluated the effects of different adhesive systems on repair bond strength of aged resin composites. Materials and Methods: Ninety composite discs were built and half of them were subjected to thermal aging. Aged and non-aged specimens were repaired with resin composite using three different adhesive systems; a two-step self-etch adhesive, a two-step total-etch adhesive and a one-step self-etch adhesive; then they were subjected to shear forces. Data were analyzed statistically. Results: Adhesive type and aging significantly affected the repair bond strengths (p<0.0001. No statistical difference was found in aged composite groups repaired with two-step self- etch or two-step total-etch adhesive. One-step self-etch adhesive showed lower bond strength values in aged composite repair (p<0.0001. Conclusion: In the repair of aged resin composite, two-step self-etch and two-step total-etch adhesives exhibited higher shear bond strength values than that of one-step self-etch adhesive.

  3. Evaluation of Calcium Silicate Cement Bond Strength after Using ...

    African Journals Online (AJOL)

    2018-01-24

    Jan 24, 2018 ... Two‑way ANOVA analysis of variance and post hoc Tukey tests were used for analyses (P= 0.05). Results: The highest push‑out bond strength was observed in the Biodentine ..... Effect of blood contamination on the retention characteristics of two endodontic biomaterials in simulated furcation perforations.

  4. Effect of thickness of bonded composite resin on compressive strength

    NARCIS (Netherlands)

    Hamburger, J.T.; Opdam, N.J.; Bronkhorst, E.M.; Roeters, J.; Huysmans, M.C.

    2014-01-01

    OBJECTIVE: The aim of this study was to investigate the compressive strength of composites with different physical properties bonded as a restoration to dentin in layers of varying thicknesses. METHODS: Four types of direct composite materials: a midway-filled (Tetric EvoCeram); a compact-filled

  5. Bond strength of resin composite to differently conditioned amalgam

    NARCIS (Netherlands)

    Ozcan, M; Vallittu, PK; Huysmans, MC; Kalk, W; Vahlberg, T

    Bulk fracture of teeth, where a part of the amalgam restoration and/or the cusp is fractured, is a common clinical problem. The aim of this study was to evaluate the effect of different surface conditioning methods on the shear bond strength of a hybrid resin composite to fresh amalgam. Amalgams (N

  6. Fluoride release/recharging ability and bond strength of glass ...

    African Journals Online (AJOL)

    release as well as greater fluoride recharge capacity. Key words: Bond strength, caries-affected dentin, fluoride release, glass ionomer cements. Date of Acceptance: 17-Aug-2015. Introduction. The current concept of restorative dentistry is characterized by the preservation of tooth structure during cavity preparation and less ...

  7. Comparison of bonding strengths of the sapwoods and heartwoods ...

    African Journals Online (AJOL)

    oak (Quercus petrea L.) and Scotch pine (Pinus sylvestris L.) with polyurethane, epoxy, and resorcinol formaldehyde adhesives are the focus of the study since these wood species and adhesives are used extensively in Turkey. The results of the study indicated that oak has the best bonding strength performance for all ...

  8. Evaluation of Calcium Silicate Cement Bond Strength after Using ...

    African Journals Online (AJOL)

    2018-01-24

    Jan 24, 2018 ... Objectives: To determine the effect of different gutta‑percha solvents. (chloroform, Endosolv E, orange oil, and eucalyptol) on the push‑out bond strength of calcium silicate cements (CSCs; white mineral trioxide aggregate. [WMTA]; capsule‑form mineral trioxide aggregate [CMTA], and Biodentine). Materials ...

  9. Compressive and bonding strength of fly ash based geopolymer mortar

    Science.gov (United States)

    Zailani, Warid Wazien Ahmad; Abdullah, Mohd Mustafa Al Bakri; Zainol, Mohd Remy Rozainy Mohd Arif; Razak, Rafiza Abd.; Tahir, Muhammad Faheem Mohd

    2017-09-01

    Geopolymer which is produced by synthesizing aluminosilicate source materials with an alkaline activator solution promotes sustainable and excellent properties of binder. The purpose of this paper is to determine the optimum binder to sand ratio of geopolymer mortars based on mechanical properties. In order to optimize the formulation of geopolymer mortar, various binder to sand ratios (0.25, 0.33, 0.5, 1.0, 2.0, 3.0, and 4.0) are prepared. The investigation on the effect of sand inclusion to the compressive and bonding strength of geopolymer mortar is approached. The experimental results show that the bonding strength performance of geopolymer is also depends on the various binder to sand ratio, where the optimum ratio 0.5 gives a highest strength of 12.73 MPa followed by 12.35 MPa, which corresponds the ratio 1.0 for geopolymer, while the compared value of OPC bonding strength is given by 9.3 MPa. The morphological structure at the interface zone is determined by Scanning Electron Microscope (SEM) and the homogenous bonding between geopolymer and substrate can be observed. Fly ash based geopolymers reveal a new category of mortar which has high potential to be used in the field of concrete repair and rehabilitation.

  10. Shear bond strength of ceramic and metallic orthodontic brackets bonded with self-etching primer and conventional bonding adhesives.

    Science.gov (United States)

    Arash, Valiollah; Naghipour, Fatemeh; Ravadgar, Mehdi; Karkhah, Ahmad; Barati, Mohammad Saleh

    2017-01-01

    Adult patients typically require high-quality orthodontic treatment for ceramic brackets, but some clinicians remain concerned about the bond strength of these brackets. Therefore, the aim of this study was to determine the shear bond strength and de-bonding characteristics of metallic and ceramic brackets bonded with two types of bonding agents. In an experimental study done in 2013 in Babol, Iran, 120 extracted human maxillary premolar teeth were randomly divided into four groups as follows: HM group: metallic bracket/conventional bonding agent; SM group: metallic bracket/Transbond self-etching primer; HC group: ceramic bracket/conventional bonding agent; SC group: ceramic bracket/Transbond self-etching primer. Twenty-four hours after thermocycling (1000 cycle, 5 °C-55 °C), the shear bond strength values were measured. The amount of resin remaining on the tooth surface (adhesive remnant index: ARI) was determined under a stereomicroscope. Enamel detachment index was evaluated under a scanning electron microscope. To perform statistical analysis, ANOVA, Kruskal-Wallis, and Tukey post-hoc tests were applied. The level of significance was set at p conventional technique. Many samples showed the bracket-adhesive interface failure or failure inside the adhesive.

  11. Tensile testing

    CERN Document Server

    2004-01-01

    A complete guide to the uniaxial tensile test, the cornerstone test for determining the mechanical properties of materials: Learn ways to predict material behavior through tensile testing. Learn how to test metals, alloys, composites, ceramics, and plastics to determine strength, ductility and elastic/plastic deformation. A must for laboratory managers, technicians, materials and design engineers, and students involved with uniaxial tensile testing. Tensile Testing , Second Edition begins with an introduction and overview of the test, with clear explanations of how materials properties are determined from test results. Subsequent sections illustrate how knowledge gained through tensile tests, such as tension properties to predict the behavior (including strength, ductility, elastic or plastic deformation, tensile and yield strengths) have resulted in improvements in materals applications. The Second Edition is completely revised and updated. It includes expanded coverage throughout the volume on a variety of ...

  12. Carbon Nanotube Bonding Strength Enhancement Using Metal "Wicking" Process

    Science.gov (United States)

    Lamb, James L.; Dickie, Matthew R.; Kowalczyk, Robert S.; Liao, Anna; Bronikowski, Michael J.

    2012-01-01

    Carbon nanotubes grown from a surface typically have poor bonding strength at the interface. A process has been developed for adding a metal coat to the surface of carbon nano tubes (CNTs) through a wicking process, which could lead to an enhanced bonding strength at the interface. This process involves merging CNTs with indium as a bump-bonding enhancement. Classical capillary theory would not normally allow materials that do not wet carbon or graphite to be drawn into the spacings by capillary action because the contact angle is greater than 90 degrees. However, capillary action can be induced through JPL's ability to fabricate oriented CNT bundles to desired spacings, and through the use of deposition techniques and temperature to control the size and mobility of the liquid metal streams and associated reservoirs. A reflow and plasma cleaning process has also been developed and demonstrated to remove indium oxide, and to obtain smooth coatings on the CNT bundles.

  13. Hybrid framework with cobalt-chromium alloy and gold cylinder for implant superstructure: Bond strength and corrosion resistance.

    Science.gov (United States)

    Yoshinari, Masao; Uzawa, Shinobu; Komiyama, Yataro

    2016-10-01

    The aim of this in vitro study was to evaluate tensile bond strengths and corrosion resistance of CoCr alloys joined with gold cylinder by a soldering system in comparison with the conventional cast-joining system. CoCr alloys joined with gold cylinder by a soldering system using a high-fusing gold solder (CoCr/Solder/Gold cylinder), gold alloy joined with gold cylinder by a cast joining system (Gold alloy/Gold cylinder) and CoCr castings were fabricated. The tensile bond strength and corrosion resistance in 0.9% NaCl solution (pH 7.4 and pH 2.3) were evaluated. Scanning electron microscopy (SEM) of the fractured surface and electron probe microanalysis (EPMA) of the joined interfaces were also performed. The tensile bond strengths of the CoCr/Solder/Gold cylinder specimens showed similar values as the Gold alloy/Gold cylinder specimens. SEM observation and EPMA analyses suggested firm bonding between the CoCr alloy and gold cylinder. The released elements from the CoCr/Solder/Gold cylinder specimens were similar to ones from CoCr castings. Results showed that superstructures made of CoCr alloys joined with the gold cylinder using a high-fusing gold solder had sufficient bond strength and high corrosion resistance. These hybrid frameworks with cobalt-chromium alloy and gold cylinder are promising prosthesis for implant superstructures with the low cost and favorable mechanical properties instead of conventional high-gold alloys. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  14. The effect of grinding and/or airborne-particle abrasion on the bond strength between zirconia and veneering porcelain: a systematic review

    Science.gov (United States)

    Lundberg, Karin; Wu, Lindsey; Papia, Evaggelia

    2017-01-01

    Abstract Objective: The aim of the study was to make an inventory of current literature on the bond strength between zirconia and veneering porcelain after surface treatment of zirconia by grinding with diamond bur and/or with airborne-particle abrasion. Material and methods: The literature search for the present review was made following recommended guidelines using acknowledged methodology on how to do a systematic review. The electronic databases PubMed, Cochrane Library, and Science Direct were used in the present study. Results: Twelve studies were selected. Test methods used in the original studies included shear bond strength (SBS) test, tensile bond strength test, and micro-tensile bond strength test. The majority of studies used SBS. Results showed a large variation within each surface treatment of zirconia, using different grain size, blasting time, and pressure. Conclusions: Airborne-particle abrasion might improve the bond strength and can therefore be considered a feasible surface treatment for zirconia that is to be bonded. Grinding has been recommended as a surface treatment for zirconia to improve the bond strength; however, this recommendation cannot be verified. A standardized test method and surface treatment are required to be able to compare the results from different studies and draw further conclusions. PMID:28642927

  15. Optimization of tensile strength of friction welded AISI 1040 and AISI 304L steels according to statistics analysis (ANOVA)

    Energy Technology Data Exchange (ETDEWEB)

    Kirik, Ihsan [Batman Univ. (Turkey); Ozdemir, Niyazi; Firat, Emrah Hanifi; Caligulu, Ugur [Firat Univ., Elazig (Turkey)

    2013-06-01

    Materials difficult to weld by fusion welding processes can be successfully welded by friction welding. The strength of the friction welded joints is extremely affected by process parameters (rotation speed, friction time, friction pressure, forging time, and forging pressure). In this study, statistical values of tensile strength were investigated in terms of rotation speed, friction time, and friction pressure on the strength behaviours of friction welded AISI 1040 and AISI 304L alloys. Then, the tensile test results were analyzed by analysis of variance (ANOVA) with a confidence level of 95 % to find out whether a statistically significant difference occurs. As a result of this study, the maximum tensile strength is very close, which that of AISI 1040 parent metal of 637 MPa to could be obtained for the joints fabricated under the welding conditions of rotation speed of 1700 rpm, friction pressure of 50 MPa, forging pressure of 100 MPa, friction time of 4 s, and forging time of 2 s. Rotation speed, friction time, and friction pressure on the friction welding of AISI 1040 and AISI 304L alloys were statistically significant regarding tensile strength test values. (orig.)

  16. Statistical Analysis of the Tensile Strength of Coal Fly Ash Concrete with Fibers Using Central Composite Design

    Directory of Open Access Journals (Sweden)

    Marinela Barbuta

    2015-01-01

    Full Text Available The influence of coal fly ash and glass fiber waste on the tensile strength of cement concrete was studied using central composite design. Coal fly ash was used to replace 10% of the cement in the concrete mix. Glass fiber was added to improve the tensile properties of the concrete in different dosages and lengths. In total, 14 mixes were investigated, one only with 10% coal fly ash replacement of cement and the other thirteen were determined by the experimental design. Using analysis of variance, the order of importance of the variables was established for each property (flexural strength and split tensile strength. From the nonlinear response surfaces, it was found that higher values of flexural strength were obtained for fibers longer than 12 mm and at a dosage of 1-2%. For split tensile strength, higher values were obtained for fibers with a length of 19–28 mm and at a dosage of 1–1.5%.

  17. Effects of laser energy density on forming accuracy and tensile strength of selective laser sintering resin coated sands

    Directory of Open Access Journals (Sweden)

    Xu Zhifeng

    2014-05-01

    Full Text Available Baozhu sand particles with size between 75 μm and 150 μm were coated by resin with the ratio of 1.5 wt.% of sands. Laser sintering experiments were carried out to investigate the effects of laser energy density (E = P/v, with different laser power (P and scanning velocity (v, on the dimensional accuracy and tensile strength of sintered parts. The experimental results indicate that with the constant scanning velocity, the tensile strength of sintered samples increases with an increase in laser energy density; while the dimensional accuracy apparently decreases when the laser energy density is larger than 0.032 J·mm-2. When the laser energy density is 0.024 J·mm-2, the tensile strength shows no obvious change; but when the laser energy density is larger than 0.024 J·mm-2, the sample strength is featured by the initial increase and subsequent decrease with simultaneous increase of both laser power and scanning velocity. In this study, the optimal energy density range for laser sintering is 0.024-0.032 J·mm-2. Moreover, samples with the best tensile strength and dimensional accuracy can be obtained when P = 30-40 W and v = 1.5-2.0 m·s-1. Using the optimized laser energy density, laser power and scanning speed, a complex coated sand mould with clear contour and excellent forming accuracy has been successfully fabricated.

  18. Influence of Accumulative Roll Bonding on the Texture and Tensile Properties of an AZ31 Magnesium Alloy Sheets

    Directory of Open Access Journals (Sweden)

    Zuzanka Trojanová

    2018-01-01

    Full Text Available Deformation behaviour of rolled AZ31 sheets that were subjected to the accumulative roll bonding was investigated. Substantially refined microstructure of samples was achieved after the first and second pass through the rolling mill. Sheets texture was investigated using an X-ray diffractometer. Samples for tensile tests were cut either parallel or perpendicular to the rolling direction. Tensile tests were performed at temperatures ranging from room temperature up to 300 °C. Tensile plastic anisotropy, different from the anisotropy observed in AZ31 sheets by other authors, was observed. This anisotropy decreases with an increasing number of rolling passes and increasing deformation temperature. Grain refinement and texture are the crucial factors influencing the deformation behaviour.

  19. Determining the Compressive, Flexural and Splitting Tensile Strength of Silica Fume Reinforced Lightweight Foamed Concrete

    Directory of Open Access Journals (Sweden)

    Mydin M.A.O.

    2014-01-01

    Full Text Available This study investigated the performance of the properties of foamed concrete in replacing volumes of cement of 10%, 15% and 20% by weight. A control unit of foamed concrete mixture made with ordinary Portland cement (OPC and 10%, 15% and 20% silica fume was prepared. Three mechanical property parameters were studied such as compressive strength, flexural strength and splitting tensile of foamed concrete with different percentages of silica fume. Silica fume is commonly used to increase the mechanical properties of concrete materials and it is also chosen due to certain economic reasons. The foamed concrete used in this study was cured at a relative humidity of 70% and a temperature of ±28°C. The improvement of mechanical properties was due to a significant densification in the microstructure of the cement paste matrix in the presence of silica fume hybrid supplementary binder as observed from micrographs obtained in the study. The overall results showed that there is a potential to utilize silica fume in foamed concrete, as there was a noticeable enhancement of thermal and mechanical properties with the addition of silica fume.

  20. Theoretical determination of the strength of soft noncovalent molecular bonds.

    Science.gov (United States)

    Chen, Hsuan-Yi; Chu, Yi-Ping

    2005-01-01

    The strength of a simple soft bond under a constant loading rate is studied theoretically. There is a scaling regime where rebinding is negligible and the rupture force scales as const+ [ln (kv) ](2/3) , where kv is the loading rate. The scaling regime is smaller for weaker bonds and broader for stronger bonds. For a loading rate beyond the upper limit of the scaling regime, the bond rupture is deterministic and the thermal effects are negligible. For a loading rate below the lower limit of the scaling regime, the contribution from rebinding becomes important and there is no simple scaling relation between the rupture force and the loading rate. Our theory takes the effect of rebinding in the calculation, therefore we find good agreement between theory and simulation even below the scaling regime.

  1. Cytotoxicity and shear bond strength of four orthodontic adhesive systems.

    Science.gov (United States)

    Jonke, Erwin; Franz, Alexander; Freudenthaler, Josef; König, Franz; Bantleon, Hans-Peter; Schedle, Andreas

    2008-10-01

    The objective of this study was to compare the cytotoxicity of four orthodontic bonding systems, Light Bond, Enlight, Concise, and Transbond, and to evaluate their shear bond strength (SBS). These orthodontic bonding materials were applied to metal brackets (Mini Diamond). Glass specimens were used as controls in all experiments. Only Concise was a chemically cured system, the other systems were light cured. The specimens were added to L-929 fibroblast cultures immediately after fabrication or after pre-incubation for 7 days. The incubation time was 72 hours and the cells were counted by flow cytometry. One hundred and fifty-seven freshly extracted human third molars were used for testing the SBS in a universal testing machine. Statistical significance was determined using analysis of variance followed by post hoc comparisons for multiple-level alpha control. Pairwise comparisons showed a significant difference only between Light Bond and Concise (P = 0.0126). The highest SBS was obtained with Light Bond (23.23 +/- 1.53 MPa) followed by Transbond (20.39 +/- 1.18 MPa) and Enlight, (20.32 +/- 1.06 MPa). Concise (17.87 +/- 1.04 MPa) showed the lowest SBS. The cytotoxicity of all light-cured systems for fresh specimens was comparable, whereas the chemically cured system, Concise, was significantly more cytotoxic. After 7 days of pre-incubation, all systems were significantly less cyotoxic than fresh specimens (P cytotoxic. All bonding systems showed a clinically satisfactory bond strength higher than 10 MPa, with the chemically cured system showing the lowest SBS.

  2. Acrylic mechanical bond tests

    Energy Technology Data Exchange (ETDEWEB)

    Wouters, J.M.; Doe, P.J.

    1991-02-01

    The tensile strength of bonded acrylic is tested as a function of bond joint thickness. 0.125 in. thick bond joints were found to posses the maximum strength while the acceptable range of joints varied from 0.063 in. to almost 0.25 in. Such joints are used in the Sudbury Neutrino Observatory.

  3. Recent results for bonding S-65C grade Be to copper alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dombrowski, D.W. [Brush Wellman Inc., Cleveland, OH (United States)

    1995-09-01

    Novel processes for bonding beryllium to copper alloys without the use of a silver bonding aid have been developed at Brush Wellman. Tensile strength results will be presented at room temperature and elevated temperatures. A comparison will be made between bond strengths derived from rectangular tensile specimens and reduced section tensile specimens. Failure modes of the specimens at various temperatures will be shown.

  4. Relationships among the structural topology, bond strength, and mechanical properties of single-walled aluminosilicate nanotubes

    Science.gov (United States)

    Liou, Kai-Hsin; Tsou, Nien-Ti; Kang, Dun-Yen

    2015-10-01

    Carbon nanotubes (CNTs) are regarded as small but strong due to their nanoscale microstructure and high mechanical strength (Young's modulus exceeds 1000 GPa). A longstanding question has been whether there exist other nanotube materials with mechanical properties as good as those of CNTs. In this study, we investigated the mechanical properties of single-walled aluminosilicate nanotubes (AlSiNTs) using a multiscale computational method and then conducted a comparison with single-walled carbon nanotubes (SWCNTs). By comparing the potential energy estimated from molecular and macroscopic material mechanics, we were able to model the chemical bonds as beam elements for the nanoscale continuum modeling. This method allowed for simulated mechanical tests (tensile, bending, and torsion) with minimum computational resources for deducing their Young's modulus and shear modulus. The proposed approach also enabled the creation of hypothetical nanotubes to elucidate the relative contributions of bond strength and nanotube structural topology to overall nanotube mechanical strength. Our results indicated that it is the structural topology rather than bond strength that dominates the mechanical properties of the nanotubes. Finally, we investigated the relationship between the structural topology and the mechanical properties by analyzing the von Mises stress distribution in the nanotubes. The proposed methodology proved effective in rationalizing differences in the mechanical properties of AlSiNTs and SWCNTs. Furthermore, this approach could be applied to the exploration of new high-strength nanotube materials.Carbon nanotubes (CNTs) are regarded as small but strong due to their nanoscale microstructure and high mechanical strength (Young's modulus exceeds 1000 GPa). A longstanding question has been whether there exist other nanotube materials with mechanical properties as good as those of CNTs. In this study, we investigated the mechanical properties of single

  5. In Vitro Evaluation of Various Surface Treatments of Fiber Posts on the Bond Strength to Composite Core

    Directory of Open Access Journals (Sweden)

    Sareh Nadalizadeh

    Full Text Available Introduction: The reliable bond at the root-post-core interface is critical for the clinical success of post-retained restorations. To decrease the risk of fracture, it is important to optimize the adhesion. Therefore, various post surface treatments have been proposed. The purpose of this study was to investigate the influence of various surface treatments of fiber posts on the bond strength to composite core. Materials & Methods: In this study, 40 fiber reinforced posts were used. After preparing and sectioning them, resulting specimens were divided into four groups (N=28. The posts received different surface treatments such as no surface treatment (control group, preparing with hydrogen peroxide 10%, preparing with silane, preparing with HF and silane. Then, posts were tested in micro tensile testing machine. The results were analyzed by One-Way ANOVA and Dunnett T3 test. Results: The greatest bond strength observed was in treatment with hydrogen peroxide 10% (19.84±8.95 MPa, and the lowest strength was related to the control group (12.44±3.40 MPa. The comparison of the groups with Dunnett T3 test showed that the differences between the groups was statistically significant (α=0.05.Conclusion: Based on the results of this study, preparing with H2O2 -10 % and silane increases the bond strength of FRC posts to the composite core more than the other methods. Generally, the bond strength of posts to the composite core increases by surface treatment.

  6. Reduction versus cross-linking: how to improve the tensile strength of graphene oxide/polyvinyl alcohol composite film

    Science.gov (United States)

    Tao, Cheng-an; Zhang, Hao; Huang, Jian; Zou, Xiaorong; Zhu, Hui; Wang, Jianfang

    2017-08-01

    Both reduction and cross-linking can improve the mechanical performance of graphene/polymer composites. However, few reports exist on the comparison and combination of both methods. Taking graphene oxide/polyvinyl alcohol composite film as its model, this study focuses on the effect of reduction and cross-linking (as well as their order) on the composite film’s tensile strength. GO/PVA composite films were prepared by a simple solution mixing method, then reduced with hydroiodic acid and cross-linked with glutaraldehyde. Both reduction and cross-linking can improve the tensile strength, but the effect of cross-linking is superior. The improvement of tensile strength is cumulative when reduction and cross-linking are used simultaneously or even successively. Moreover, the order in which these two methods are applied also plays a role; reduction first with cross-linking second shows superior results than the reverse. The tensile strength of the obtained composite film peaked at 112.8 MPa, which is over 7 times that of neat PVA.

  7. Optimal suture materials for contaminated gastrointestinal surgery: does infection influence the decrease of the tensile strength of sutures?

    Science.gov (United States)

    Tanaka, Yoichi; Sadahiro, Sotaro; Ishikawa, Kenji; Suzuki, Toshiyuki; Kamijo, Akemi; Tazume, Seiki; Yasuda, Masanori

    2012-12-01

    Suture materials are selected based on the following factors: absorbable/non-absorbable, monofilament/multifilament, duration with sufficiently high tensile strength, and the tissue to be sutured. Absorbable sutures are hydrolyzed in tissues. However, little is known about the influence of infection on the hydrolysis and decrease in the tensile strength. Four kinds of sutures, i.e., non-absorbable multifilament silk, non-absorbable monofilament polypropylene (Prolene(®)), absorbable multifilament polyglactin 910 (Vicryl(®)), and absorbable monofilament polydioxanone (PDS(®)) were implanted in the back of rats. A suspension of Escherichia coli + Bacteroides fragilis or saline was injected subcutaneously into the contaminated and clean condition groups, respectively. The sutures were removed 1, 2, 4 or 8 weeks after the implantation. There was significantly more severe inflammation macroscopically for the silk sutures under the contaminated conditions (p = 0.03), however, no significant differences were observed among the other three sutures. All 4 kinds of sutures showed a reduction of the tensile strength over time. There were no significant differences in the magnitude of reduction between both the clean and contaminated conditions for any of the sutures. The reduction of the tensile strength with time did not differ significantly between sutures exposed to contaminated and clean conditions, even for the absorbable sutures.

  8. Evaluation of Surface Roughness and Tensile Strength of Base Metal Alloys Used for Crown and Bridge on Recasting (Recycling).

    Science.gov (United States)

    Agrawal, Amit; Hashmi, Syed W; Rao, Yogesh; Garg, Akanksha

    2015-07-01

    Dental casting alloys play a prominent role in the restoration of the partial dentition. Casting alloys have to survive long term in the mouth and also have the combination of structure, molecules, wear resistance and biologic compatibility. According to ADA system casting alloys were divided into three groups (wt%); high noble, Noble and predominantly base metal alloys. To evaluate the mechanical properties such as tensile strength and surface roughness of the new and recast base metal (nickel-chromium) alloys. Recasting of the base metal alloys derived from sprue and button, to make it reusable has been done. A total of 200 test specimens were fabricated using specially fabricated jig of metal and divided into two groups- 100 specimens of new alloy and 100 specimens of recast alloys, which were tested for tensile strength on universal testing machine and surface roughness on surface roughness tester. Tensile strength of new alloy showed no statistically significant difference (p-value>0.05) from recast alloy whereas new alloy had statistically significant surface roughness (Maximum and Average surface roughness) difference (p-valuealloy. Within the limitations of the study it is concluded that the tensile strength will not be affected by recasting of nickel-chromium alloy whereas surface roughness increases markedly.

  9. Effects of reclaimed asphalt pavement on indirect tensile strength test of foamed asphalt mix tested in dry condition

    Science.gov (United States)

    Yati Katman, Herda; Rasdan Ibrahim, Mohd; Yazip Matori, Mohd; Norhisham, Shuhairy; Ismail, Norlela

    2013-06-01

    Indirect tensile strength (ITS) test was conducted to analyse strength of the foamed asphalt mixes incorporating reclaimed asphalt pavement. Samples were tested for ITS after cured in the oven at 40°C for 72 hours. This testing condition known as dry condition or unconditioned. Laboratory results show that reclaimed asphalt pavement (RAP) contents insignificantly affect the ITS results. ITS results significantly affected by foamed bitumen contents.

  10. Evaluation of the mechanical properties and porcelain bond strength of cobalt-chromium dental alloy fabricated by selective laser melting.

    Science.gov (United States)

    Wu, Lin; Zhu, Haiting; Gai, Xiuying; Wang, Yanyan

    2014-01-01

    Limited information is available regarding the microstructure and mechanical properties of dental alloy fabricated by selective laser melting (SLM). The purpose of this study was to evaluate the mechanical properties of a cobalt-chromium (Co-Cr) dental alloy fabricated by SLM and to determine the correlation between its microstructure and mechanical properties and its porcelain bond strength. Five metal specimens and 10 metal ceramic specimens were fabricated to evaluate the mechanical properties of SLM Co-Cr dental alloy (SLM alloy) with a tensile test and its porcelain bond strength with a 3-point bending test. The relevant properties of the SLM alloy were compared with those of the currently used Co-Cr dental alloy fabricated with conventional cast technology (cast alloy). The Student t test was used to compare the results of the SLM alloy and the cast alloy (α=.05). The microstructure of the SLM alloy was analyzed with a metallographic microscope; the metal ceramic interface of the SLM porcelain bonded alloy was studied with scanning electron microscopy, energy dispersive x-ray spectroscopy, and an electron probe microanalyzer. Both the mean (standard deviation) yield strength (884.37 ± 8.96 MPa) and tensile strength (1307.50 ±10.65 MPa) of the SLM alloy were notably higher than yield strength (568.10 ± 30.94 MPa) and tensile strength (758.73 ± 25.85 MPa) of the currently used cast alloy, and the differences were significant (Pporcelain bond strength of the SLM alloy was 55.78 ± 3.02 MPa, which was similar to that of the cast alloy, 54.17 ± 4.96 MPa (P>.05). Microstructure analysis suggested that the SLM alloy had a dense and obviously orientated microstructure, which led to excellent mechanical properties. Analysis from scanning electron microscopy, energy dispersive x-ray spectroscopy, and the electron probe microanalyzer indicated that the SLM alloy had an intermediate layer with elemental interpenetration between the alloy and the porcelain, which

  11. Methods used in dentine bonding tests: an analysis of 102 investigations on bond strength.

    Science.gov (United States)

    Burke, F J Trevor; Hussain, Aftab; Nolan, Lawrence; Fleming, Garry J P

    2008-12-01

    Bond strength testing of resin-based materials to dentine may provide evidence as to the potential effectiveness of a dentine-bonding agent in producing adhesion and minimising microleakage. The purpose of this analysis was to analyse the methods used in 102 recently-published investigations on bond strength tests of resin composite to dentine. One hundred and two papers, published during the years 1998 to 2002 on the subject of bond strength measurement of resin composite to dentine were identified from a literature search. These papers were assessed for their inclusion of the following variables: type of test, thermal cycling regime, tooth notation, storage medium, preparation of dentine surface, rate of load application, type of dentine, film thickness, dimensions of surface area contact and time of testing. Shear testing was the most common type of test, used in 46% (n=47) of the papers analysed, human dentine was used in 77% (n=79) of the investigations, and 24 h post-placement was the predominant time of specimen testing (67%, n=68). Surface area of contact, or specimen diameter, was stated in 65% (n=66) of the papers analysed. A number of variables were not stated in a majority of papers. There was little standardization of test methods and a number of potentially significant variables may not be reported or recorded in bond strength determinations which limit the overall standardization between different test centres.

  12. Solubility parameters, fractional polarities, and bond strengths of some intermediary resins used in dentin bonding.

    Science.gov (United States)

    Asmussen, E; Uno, S

    1993-03-01

    An effective bonding of resin composites to dentin is generally preceded by a conditioning of the surface of the dentin. Previous studies have indicated that the intermediary or adhesive resin should have specific wetting characteristics matching those of the conditioned dentin, in order that optimum bonding can be ensured. The wetting characteristics may be expressed in terms of solubility parameter (delta) and polarity (p) of the resin. The aims of the present study were to determine these variables for a number of compounds used in adhesive resins and to investigate the effects of delta and p on the shear bond strength to dentin. Solubility parameters were obtained according to the method of Small. Fractional polarities were calculated on the basis of measurements of refractive index and dielectric constant of the resins. In the measurements of bond strength, Scotchprep, EDTA + Gluma, or Al2Ox3/glycine were used as dentin conditioners in combination with intermediary resins having various delta and p. For each conditioner, the shear bond strength (BS) could be "explained" by an exponential expression of the form BS = e(a + bx), where x = (delta + cp + d)2, and where a-d are constants depending on the conditioned dentin. It may be concluded that solubility parameter and polarity of the intermediary resins are important variables in the process of bonding to dentin.

  13. Comparison of shear bond strength of amalgam bonded to primary and permanent dentin

    Directory of Open Access Journals (Sweden)

    Mahdi S

    2008-06-01

    Full Text Available Amalgam′s non-adhesive characteristics necessitate cavity preparations incorporating retentive features, which often require the removal of non-carious tooth structure. Use of adhesives beneath amalgam restorations, would be helpful to overcome this disadvantage. This study was undertaken to compare the mean shear bond strength of amalgam bonded to primary and permanent dentin, to evaluate the efficacy of amalgam adhesives in pediatric dentistry.27 primary and 28 permanent posterior teeth with intact buccal or lingual surfaces were grounded to expose dentin and wet-polished with 400-grit silicone carbide paper. Scotchbond Multi Purpose Plus adhesive system was applied to the dentin surfaces and light cured. Amalgam was condensed onto the treated dentin through a plastic mold.shear bond strength testing was done using an Instron Universal testing machine, at a crosshead speed of 0.5 mm/min.The data were analyzed by independent samples t-test The difference among the two groups was not statistically significant (p>0.05 Bonded amalgam showed the same level of bond strength to primary and permanent dentin; so, application of amalgam bonding agents in pediatric dentistry can be recommended.

  14. Bond strength and stress measurements in thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Gell, M.; Jordan, E. [Univ. of Connecticut, Storrs, CT (United States)

    1995-10-01

    Thermal barrier coatings have been used extensively in aircraft gas turbines for more than 15 years to insulate combustors and turbine vanes from the hot gas stream. Plasma sprayed thermal barrier coatings (TBCs) provide metal temperature reductions as much as 300{degrees}F, with improvements in durability of two times or more being achieved. The introduction of TBCs deposited by electron beam physical vapor deposition (EB-PVD) processes in the last five years has provided a major improvement in durability and also enabled TBCs to be applied to turbine blades for improved engine performance. To meet the aggressive Advanced Turbine Systems goals for efficiency, durability and the environment, it will be necessary to employ thermal barrier coatings on turbine airfoils and other hot section components. For The successful application of TBCs to ATS engines with 2600{degrees}F turbine inlet temperatures and required component lives 10 times greater than those for aircraft gas turbine engines, it is necessary to develop quantitative assessment techniques for TBC coating integrity with time and cycles in ATS engines. Thermal barrier coatings in production today consist of a metallic bond coat, such as an MCrAlY overlay coating or a platinum aluminide (Pt-Al) diffusion coating. During heat treatment, both these coatings form a thin, tightly adherent alumina (Al{sub 2}O{sub 3}) film. Failure of TBC coatings in engine service occurs by spallation of the ceramic coating at or near the bond coat to alumina or the alumina to zirconia bonds. Thus, it is the initial strength of these bonds and the stresses at the bond plane, and their changes with engine exposure, that determines coating durability. The purpose of this program is to provide, for the first time, a quantitative assessment of TBC bond strength and bond plane stresses as a function of engine time and cycles.

  15. Evaluation of surface roughness and bond strength of quartz fiber posts after various pre-treatments.

    Science.gov (United States)

    Akin, Gulsah E; Akin, Hakan; Sipahi, Cumhur; Piskin, Bulent; Kirmali, Omer

    2014-11-01

    Debonding at the post-adhesive interface is a major problem for quartz fiber posts. The objective of this study was to evaluate surface roughness and bond strength of quartz fiber posts after various surface treatments. Sixty-six quartz fiber posts were randomly divided into six experimental groups (n = 11) including group C, untreated (control); group SB, sandblasted; group SC, silica coated; group HF, hydrofluoric acid-etched; group N, Nd:YAG laser irradiated; group E, Er:YAG laser irradiated. Surface roughness of the posts was measured before and after pre-treatment. They were then bonded to resin cement and tensile bond strength was determined in a universal testing machine. Furthermore, two-way ANOVA and post hoc comparison tests (α = 0.05) were performed on all data. The highest mean force value was observed in group SB and followed by group E. Tukey's HSD test showed that there was no statistical difference between group SB and group E (p = 0.673). The highest mean roughness value was observed in group SB and a significant difference was found between group SB and all other groups (p quartz fiber posts and resin cement. Sandblasting or Er:YAG laser-irradiation of the surface of the quartz fiber post before cementation is recommended for increasing retention.

  16. Effect of mode of polymerization of bonding agent on shear bond strength of autocured resin composite luting cements.

    Science.gov (United States)

    Dong, Cecilia C S; McComb, Dorothy; Anderson, James D; Tam, Laura E

    2003-04-01

    There have been anecdotal reports of low bond strength with autocured resin composite materials, particularly when light-cured bonding agents that combine primer and adhesive in a 1-bottle preparation are used. The objective of this study was to determine if the mode of polymerization of the bonding agent influences the strength of the attachment of autocured resin composite luting cements to dentin. The shear bond strength of 2 resin luting cements, Calibra and RelyX ARC, polymerized by autocuring, in combination with 4 different bonding agents, Scotchbond Multipurpose Plus, Prime & Bond NT, IntegraBond and Single Bond, polymerized to bovine dentin by light-curing, autocuring or dual-curing, was determined. The pH of each bonding agent and its components was measured. Two-way analysis of variance was used to test the effect of cement and adhesive on shear bond strength. For each bonding agent, the adhesive variable combined the factors product brand and mode of polymerization. With significant interaction among the above variables, the least square means of the 16 combinations of resin cement and adhesive were compared. There was no consistent relationship between shear bond strength and mode of polymerization of the bonding agent. Significant differences in bond strength were specific to the proprietary brand of bonding agent. The pH of the bonding agent depends on the manufacturer's formulation, and low pH may contribute to low bond strength. The low in vitro bond strength occurring with some combinations of bonding agent and resin cement could be clinically significant.

  17. Bond strength of composite resin to enamel: assessment of two ethanol wet-bonding techniques.

    Directory of Open Access Journals (Sweden)

    Maryam Khoroushi

    2014-04-01

    Full Text Available Ethanol wet-bonding (EWB technique has been stated to decrease degradation of resin-dentin bond. This study evaluated the effect of two EWB techniques on composite resin-to-enamel bond strength.Silicon carbide papers were used to produce flat enamel surfaces on the buccal faces of forty-five molars. OptiBond FL (OFL adhesive was applied on enamel surfaces in three groups of 15 namely: Enamel surface and OFL (control;Protocol 1 of the EWB technique: absolute ethanol was applied to water-saturated acid-etched enamel surfaces for 1 minute before the application of ethanol-solvated hydrophobic adhesive resin of OFL 3 times;Protocol 2: progressive ethanol replacement; water was gradually removed from the enamel matrix using ascending ethanol concentrations before OFL application. Composite build-ups were made and the specimens were stored for 24 hours at 37°C and 100% relative humidity. Shear bond strength test was performed using a universal testing machine at 1 mm/min crosshead speed. Fracture patterns were evaluated microscopically. Data were analyzed with one-way ANOVA and Fisher's exact test (α=0.05.There were no significant differences in bond strength between the groups (P=0.73. However, regarding failure patterns, the highest cohesive enamel fractures were recorded in groups 2 and 3.In this study, although both methods of EWB did not influence immediate bond strength of composite resin to enamel, the majority of failure patterns occurred cohesively in enamel.

  18. Effect of simplified ethanol-wet bonding on microtensile bond strengths of dentin adhesive agents with different solvents

    Directory of Open Access Journals (Sweden)

    Muhammet Kerim Ayar

    2015-09-01

    Conclusion: Simplified ethanol-wet bonding exhibited similar 24-hour bond strength mean values for both ethanol/water-based and acetone-based etch-and-rinse adhesives. Therefore, solvent content may not interfere with bond strength to ethanol-saturated dentin.

  19. The effect of repeated bonding on the shear bond strength of different resin cements to enamel and dentin.

    Science.gov (United States)

    Bulut, Ali Can; Atsü, Saadet Sağlam

    2017-02-01

    Cementation failures of restorations are frequently observed in clinical practice. The purpose of this study is to compare the effect of initial and repeated bonding on the bond strengths of different resin cements to enamel and dentin. Ninety human maxillary central incisors were bisected longitudinally. The 180 tooth halves were divided into 2 groups (n = 90) for enamel and dentin bonding. The enamel and dentin groups were further divided into 3 groups (n = 30) for different resin cement types. Composite resin (Filtek Ultimate) cylinders (3 × 3 mm) were prepared and luted to enamel and dentin using Variolink II (Group V), RelyX ARC (Group R), or Panavia F 2.0 (Group P) resin cement. After 24 hours, initial shear bond strengths of the resin cements to enamel and dentin were measured. Using new cylinders, the specimens were de-bonded and re-bonded twice to measure the first and the second bond strengths to enamel and dentin. Failure modes and bonding interfaces were examined. Data were statistically analyzed. Initial and repeated bond strengths to enamel were similar for all the groups. The first (15.3 ± 2.2 MPa) and second (10.4 ± 2.2 MPa) bond strengths to dentin were significantly higher in Group V (Pdentin groups were significantly lower than initial and first bond strengths to dentin (Pdentin. Bond strength to dentin decreases after the first re-bonding for all resin cements.

  20. Comparison of Shear Bond Strength between Composite Resin and Porcelain Using Different Bonding Systems

    Directory of Open Access Journals (Sweden)

    E.Yassini

    2005-03-01

    Full Text Available Statement of Problem: Ceramics as in ceramo-metallic and all ceramic tooth restorations have grown popular owing to their high tissue compatibility and esthetic advantages. Such restorations have the capability to deliver valuable services over a long period of time; however, failures under intraoral conditions are not unanticipated.Purpose: The purpose of this in-vitro study was to investigate the shear bond strength of composite resin to porcelain using different bonding system materials.Materials and Methods: In this experimental study forty porcelain blocks were prepared and randomly divided into four equal groups. The porcelain surfaces were then etched with HF for 2 minutes, washed with water for 2 minutes and treated with a silane layer. The silane treated porcelain surfaces were left for one minute and then the specimens were bonded to composite resin as follow:Group 1 (control group, hybrid composite Z100 was applied and light cured from four directions for 20 seconds. Group 2, flowable composite was applied and light cured for 20 seconds. Group 3, unfilled resin was used and photo cured for 20 seconds. Group 4,(Dentin bonding agent adhesive resin was used followed by 20 seconds photo curing.Hybrid composite resin Z100 was subsequently applied on all porcelain surfaces of groups 2, 3 and 4, and light cured for 20 seconds from four directions. Specimens were then subjected to thermocycling 1000 times. Shear bond strength was determined by a Universal testing machine. The data obtained was subjected to a one-way ANOVA test.Results: The results indicate that there is a statistically significant difference between adhesive group and the other three groups of hybrid, flowable and unfilled resin (P<0.05.Conclusion: The results from this study showed that the shear bond strength of composite resin to porcelain was significantly higher for porcelain bonded surfaces using a dentin bonding agent than that of other materials tested.

  1. Effects of substrate preheating during direct energy deposition on microstructure, hardness, tensile strength, and notch toughness

    Science.gov (United States)

    Baek, Gyeong Yun; Lee, Ki Yong; Park, Sang Hu; Shim, Do Sik

    2017-11-01

    This study examined the effects of substrate preheating for the hardfacing of cold-press dies using the high-speed tool steel AISI M4. The preheating of the substrate is a widely used technique for reducing the degree of thermal deformation and preventing crack formation. We investigated the changes in the metallurgical and mechanical properties of the high-speed tool steel M4 deposited on an AISI D2 substrate with changes in the substrate preheating temperature. Five preheating temperatures (100-500 °C; interval of 100 °C) were selected, and the changes in the temperature of the substrate during deposition were observed. As the preheating temperature of the substrate was increased, the temperature gradient between the melting layer and the substrate decreased; this prevented the formation of internal cracks, owing to thermal stress relief. Field-emission scanning electron microscopy showed that a dendritic structure was formed at the interface between the deposited layer and the substrate while a cellular microstructure was formed in the deposited layer. As the preheating temperature was increased, the sizes of the cells and precipitated carbides also increased. Furthermore, the hardness increased slightly while the strength and toughness decreased. Moreover, the tensile and impact properties deteriorated rapidly at excessively high preheating temperatures (greater than 500 °C). The results of this study can be used as preheating criteria for achieving the desired mechanical properties during the hardfacing of dies and molds.

  2. Root diversity in alpine plants: root length, tensile strength and plant age

    Science.gov (United States)

    Pohl, M.; Stroude, R.; Körner, C.; Buttler, A.; Rixen, C.

    2009-04-01

    A high diversity of plant species and functional groups is hypothesised to increase the diversity of root types and their subsequent effects for soil stability. However, even basic data on root characteristics of alpine plants are very scarce. Therefore, we determined important root characteristics of 13 plant species from different functional groups, i.e. grasses, herbs and shrubs. We excavated the whole root systems of 62 plants from a machine-graded ski slope at 2625 m a.s.l. and analysed the rooting depth, the horizontal root extension, root length and diameter. Single roots of plant species were tested for tensile strength. The age of herbs and shrubs was determined by growth-ring analysis. Root characteristics varied considerably between both plant species and functional groups. The rooting depth of different species ranged from 7.2 ± 0.97 cm to 20.5 ± 2.33 cm, but was significantly larger in the herb Geum reptans (70.8 ± 10.75 cm). The woody species Salix breviserrata reached the highest horizontal root extensions (96.8 ± 25.5 cm). Most plants had their longest roots in fine diameter classes (0.5

  3. Effects of substrate preheating during direct energy deposition on microstructure, hardness, tensile strength, and notch toughness

    Science.gov (United States)

    Baek, Gyeong Yun; Lee, Ki Yong; Park, Sang Hu; Shim, Do Sik

    2017-10-01

    This study examined the effects of substrate preheating for the hardfacing of cold-press dies using the high-speed tool steel AISI M4. The preheating of the substrate is a widely used technique for reducing the degree of thermal deformation and preventing crack formation. We investigated the changes in the metallurgical and mechanical properties of the high-speed tool steel M4 deposited on an AISI D2 substrate with changes in the substrate preheating temperature. Five preheating temperatures (100-500 °C; interval of 100 °C) were selected, and the changes in the temperature of the substrate during deposition were observed. As the preheating temperature of the substrate was increased, the temperature gradient between the melting layer and the substrate decreased; this prevented the formation of internal cracks, owing to thermal stress relief. Field-emission scanning electron microscopy showed that a dendritic structure was formed at the interface between the deposited layer and the substrate while a cellular microstructure was formed in the deposited layer. As the preheating temperature was increased, the sizes of the cells and precipitated carbides also increased. Furthermore, the hardness increased slightly while the strength and toughness decreased. Moreover, the tensile and impact properties deteriorated rapidly at excessively high preheating temperatures (greater than 500 °C). The results of this study can be used as preheating criteria for achieving the desired mechanical properties during the hardfacing of dies and molds.

  4. Note on the Use of Diametrical Compression to Determine Tablet Tensile Strength.

    Science.gov (United States)

    Hilden, Jon; Polizzi, Mark; Zettler, Aaron

    2017-01-01

    The diametrical compression (DC) test, as defined in United States Pharmacopeia and in American Society for Testing and Materials testing standard D 3967, has been used extensively to derive the tensile strength (TS) of pharmaceutical tablets from the measured breaking force. DC-derived TSs provide a good approach to measuring the consistency of tablet mechanical properties from one batch to the next. For these quality control type applications, method precision is required, but accuracy is not. In addition, DC has been used to calibrate parameters of the Druker Prager Cap model, a yield criterion expressing the failure of a powder compact under arbitrary 3D loading conditions. For this application, the DC method must not only provide suitable precision but also provide accuracy. In this work, we explore the accuracy of the DC method by comparing TS results to those of the 3-point bend test method (also defined in United States Pharmacopeia ). We conclude that the true TS of a powder compact is approximately double the DC-derived value. Although historical literature assumes that tablets fracture under tension along the centerline of the tablet, analysis of the stress state suggests that tablets are likely to fracture under shear. The impact of this ∼50% error should be considered when accuracy of the TS result is required. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  5. Are Bonding Agents being Effective on the Shear Bond Strength of Orthodontic Brackets Bonded to the Composite?

    Directory of Open Access Journals (Sweden)

    Fahimeh Farzanegan

    2014-06-01

    Full Text Available Introduction: One of the clinical problems in orthodontics is the bonding of brackets tocomposite restorations. The aim of this study was to evaluate the shear bondstrength of brackets bonded to composite restorations using Excite. Methods:Forty brackets were bonded to composite surfaces, which were embedded inacrylic resin. One of the following four protocols was employed for surfacepreparation of the composite: group 1 37% phosphoric acid for 60 seconds, group2 roughening with a diamond bur plus 37% phosphoric acid for 60 seconds, group3 37% phosphoric acid for 60 seconds and the applying Excite®, group4 roughening with diamond bur plus 37% phosphoric acid for 60 seconds andapplying Excite®. Maxillary central brackets were bonded onto thecomposite prepared samples with Transbond XT. Shear Bond Strength (SBS wasmeasured by a universal testing machine. The ANOVA and Tukey test was utilizedfor data analysis. Results: There was a significant difference betweenthe four groups (P

  6. Microleakage and Shear Bond Strength of a New Giomer Sealant

    Science.gov (United States)

    2015-05-08

    step conditioning agent in sealant placement: 6-month results International Journal of Paediatric Dentistry 16 424-430. 23. Feigal RJ & Quelhas I...Capt Samuel N. Durham 2. Academic Title: Resident, Advanced Education in General Dentistry Residency (AEGD-2) 3. School/Department/Center: Air Force...34Microleakage and Shear Bond Strength of a New Giomer Sealant" 7. Intended publication/meeting: Operative Dentistry 8. "Required by" date: 30 June 2015

  7. Maximizing fusible interlinings bonding strength by optimizing the fusing conditions

    OpenAIRE

    Golomeova, Saska; Demboski, Goran; Kortosheva, Sonja

    2011-01-01

    In this paper, Taguchi robust design methods were applied for optimization a fusing process conditions to maximize the bonding strength between a fabric and a fusible interlining before and after laundering process. Four parameters, including type of fusible interlining, fusing temperature, pressure, and time were selected to optimize the quality of fused textile system. Nine experiments were performed with respect to the L9 orthogonal design for the Taguchi method. The results show a conside...

  8. Strain Rate Effect on Tensile Behavior for a High Specific Strength Steel: From Quasi-Static to Intermediate Strain Rates

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2017-12-01

    Full Text Available The strain rate effect on the tensile behaviors of a high specific strength steel (HSSS with dual-phase microstructure has been investigated. The yield strength, the ultimate strength and the tensile toughness were all observed to increase with increasing strain rates at the range of 0.0006 to 56/s, rendering this HSSS as an excellent candidate for an energy absorber in the automobile industry, since vehicle crushing often happens at intermediate strain rates. Back stress hardening has been found to play an important role for this HSSS due to load transfer and strain partitioning between two phases, and a higher strain rate could cause even higher strain partitioning in the softer austenite grains, delaying the deformation instability. Deformation twins are observed in the austenite grains at all strain rates to facilitate the uniform tensile deformation. The B2 phase (FeAl intermetallic compound is less deformable at higher strain rates, resulting in easier brittle fracture in B2 particles, smaller dimple size and a higher density of phase interfaces in final fracture surfaces. Thus, more energy need be consumed during the final fracture for the experiments conducted at higher strain rates, resulting in better tensile toughness.

  9. Effect of Ringer's Solution on Tensile Strength of Non-Absorbable, Medium- and Long-Term Absorbable Sutures

    Directory of Open Access Journals (Sweden)

    Robert Karpiński

    2017-12-01

    Full Text Available The paper presents an experimental and correlational study of mechanical properties of selected surgical sutures. The research methods employed in the study consisted in conducting tensile strength tests on suture material and subjecting the obtained data to statistical analysis. The changes in tensile strength of absorbable sutures measured in tests were subsequently collated with results for suture material samples that were not exposed to Ringer’s solution. The results were, furthermore, compared with manufacturer’s specifications concerning suture absorption time in the body. The detailed analysis of differences between results presented in the study allowed us to formulate conclusions regarding the impact of exposure to Ringer’s solution on the strength of surgical sutures.

  10. Improving the tensile strength of carbon nanotube yarn via one-step double [2+1] cycloadditions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, HeeJin [Kyungpook National University, Daegu (Korea, Republic of); Lee, Jaegeun; Park, Byungrak; Sa, Jeong Hoon; Jung, Alum; Kim, Teawon; Park, Junbeom; Hwang, Woonbong; Lee, Kun Hong [Pohang University of Science and Technology, Pohang (Korea, Republic of)

    2016-01-15

    The tensile strength of a CNT yarn was improved through simple one-step double [2+1] cycloaddition reactions that crosslinked the constituent CNTs using a polyethylene glycol (PEG)-diazide crosslinker. The FT-IR spectrum confirmed that the azide groups in the PEG-diazide were converted into aziridine rings, indicating that the cycloaddition reaction was successful. The generation of crosslinked CNTs was also supported by the observation of N1s peak in the XPS spectrum and the increased thermal stability of the material, as observed by TGA. The tensile strength of the CNT yarn was increased from 0.2GPa to 1.4GPa after the crosslinking reaction when twisted at 4000 twists/ meter. The appropriate selection of the crosslinker may further optimize the CNT yarn crosslinking reaction. The simplicity of this one-step crosslinking reaction provides an economical approach to the mass production of high-strength CNT yarns.

  11. Bond strength between zirconium ceramic and dual resinous cement

    Directory of Open Access Journals (Sweden)

    João Galan Junior

    2010-04-01

    Full Text Available Objective: To assess the influence of different surface treatments on the bond strength between the resinous cement Panavia F (Kuraray Co. Ltd., Osaka, Japan and the structure of In-Ceram YZ (Vita Zahnfabrik, Bad Säckingen, Germany. Methods: Fifteen ceramic blocks were assessed: Group 1, finishing with abrasive paper; Group 2, finishing, airborne Al2O3 particle abrasion and silanization; Group 3, finishing, airborne particle abrasion, silicatization and silanization. After treatment, the blocks received cementation of resin composite cylinders with Panavia F (Kuraray Co. Ltd., Osaka, Japan and were submitted to the shear bond strength test in a universal testing machine. Results: The results were statistically analyzed (ANOVA and multiple comparison Student-Newman-Keuls test: Group 1 (9.66 ± 1.67 MPa < Group 2 (16.61 ± 3.38 MPa = Group 3 (19.23 ± 5.69 MPa, with p = 0.007. Conclusion: The structures of the In-Ceram YZ system (Vita Zahnfabrik, Bad Säckingen, Germany associated with Panavia F (Kuraray Co. Ltd., Osaka, Japan require previous etching to achieve greater bond strength between the ceramic and cement, and this treatment may be performed with airborne particle abrasion I or traditional silicatization, both followed by silanization.

  12. Structural disorder effects on the tensile strength distribution of heterogeneous brittle materials with emphasis on fiber networks

    Science.gov (United States)

    Hristopulos, Dionissios T.; Uesaka, Tetsu

    2004-08-01

    Understanding the interplay of structural disorder and strength properties at various length scales can lead to improvements in the strength reliability of heterogeneous brittle materials. Various studies in ordered fiber- matrix composites have shown the existence of critical clusters of breaks and macroscopic weak-link scaling behavior. The fiber network in paper is structurally disordered. We verify experimentally that the tensile strength of newsprint samples follows weak-link scaling and obtain an estimate for the link and critical-cluster sizes. However, a slight nonlinear behavior is observed in the Weibull plots of the experimental strength distributions. We propose that this is due to mesoscopic structural disorder (e.g., at length scales between millimeters and centimeters), which we incorporate in the strength distribution of the links by averaging over the elastic stress variations. The prevailing industry perception is that mesoscopic disorder controls the strength reliability. In contrast, we find that it does not significantly affect the crucial lower tail of the strength distribution. Based on our analysis, we suggest a more reliable measurement approach for the tensile strength of newsprint paper. We also obtain explicit expressions for the effects of disorder on stress variations and the macroscopic Young’s modulus, including dependence on the shear modulus and anisotropic effects.

  13. Vertical density profile and internal bond strength of wet-formed particleboard bonded with cellulose nanofibrils

    Science.gov (United States)

    John F. Hunt; Weiqi Leng; Mehdi Tajvidi

    2017-01-01

    In this study, the effects of cellulose nanofibrils (CNFs) ratio, press program, particle size, and density on the vertical density profile (VDP) and internal bond (IB) strength of the wet-formed particleboard were investigated. Results revealed that the VDP was significantly influenced by the press program. Pressing using a constant pressure (CP) press program...

  14. Comparison of shear bond strength of orthodontic brackets bonded with halogen and plasma arc light curing

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein IndianJPsychiatry

    2012-01-01

    Conclusion: Using the plasma arc system is superior to other methods due to reduced curing time. Also, since in using the halogen light system, an increase in curing periods from different angles resulted in a significant increase in shear bond strength; it is advisable to apply the halogen light from different angles.

  15. Methods used in dentin bonding tests: an analysis of 50 investigations on bond strength.

    Science.gov (United States)

    al-Salehi, S K; Burke, F J

    1997-11-01

    Researchers have carried out a variety of investigations to determine the properties of available dentin bonding systems. The test methods and variables used in 50 published investigations of bond strength were analyzed. Among the studies analyzed, shear tests predominated, being used in 80% of the studies; dentin from human molar teeth was used most often (in 88% of investigations); and the most prevalent time of testing was 24 hours postcuring. However, a number of potential variables were not recorded in a high proportion of articles, among these the film thickness, the type of dentin tested, and the surface condition (moist or dry). The mode of failure was recorded in only 42% of the investigations assessed. It was found that there is little standardization of test methods in studies of dentin bond strength and that a number of variables are often either not recorded or reported.

  16. Effect of clearfil protect bond and transbond plus self-etch primer on shear bond strength of orthodontic brackets

    Directory of Open Access Journals (Sweden)

    S Hamid Raji

    2011-01-01

    Conclusion: The shear bond strength of clearfil protect bond and transbond plus self-etch primer was enough for bonding the orthodontic brackets. The mode of failure of bonded brackets with these two self-etch primers is safe for enamel.

  17. CORRELATION BETWEEN HARDNESS AND TENSILE PROPERTIES IN ULTRA-HIGH STRENGTH DUAL PHASE STEELS – SHORT COMMUNICATION

    Directory of Open Access Journals (Sweden)

    Martin Gaško

    2012-02-01

    Full Text Available The possibility to predict yield strength, strength limit, fatigue live estimation as well as other mechanical properties depending on values of materials hardness is commonly known and it is often used in practice. The main aim of this contribution is to review the possibilities of application of correlation relationships between hardness and ultimate tensile strength of steel sheets in various structural states. The experiments were performed on advanced steels with structure which is composed from ferrite and martensite (dual phase steels.

  18. CORRELATION BETWEEN HARDNESS AND TENSILE PROPERTIES IN ULTRA-HIGH STRENGTH DUAL PHASE STEELS ��� SHORT COMMUNICATION

    Directory of Open Access Journals (Sweden)

    Gejza Rosenberg

    2011-11-01

    Full Text Available The possibility to predict yield strength, strength limit, fatigue live estimation as well as other mechanical properties depending on values of materials hardness is commonly known and it is often used in practice. The main aim of this contribution is to review the possibilities of application of correlation relationships between hardness and ultimate tensile strength of steel sheets in various structural states. The experiments were performed on advanced steels with structure which is composed from ferrite and martensite (dual phase steels.

  19. Comparison of the shear bond strength of orthodontic brackets bonded using silorane base and metacrylate base composite

    Directory of Open Access Journals (Sweden)

    Abdolrahim Davari

    2015-07-01

    Full Text Available Background and Aims: Orthodontic bracket failure during treatment is a common problem. With the introduction of low shrinkage composites the question is that whether: this sufficient has coefficient bond strength for bonding bracket during orthodontic treatment. The aim of this study was to compare the shear bond strength (SBS of silorane-based and metacrylate-based composites to metal brackets.   Materials and Methods: 30 human premolar teeth were collected and divided into 2 groups. In group 1, 15 orthodontic brackets were bonded using silorane-based composite, in group 2, 15 orthodontic brackets were bonded using metacrylate-based composite. The shear bond strength of each specimen was determined in an Instron machine. Amount of residual adhesive remaining on each tooth was evaluated using a stereomicroscope. Data were analyzed using T-test to compare the shear bond strength between groups and LSD method to compare the Adhesive Remnant Index (ARI scores.   Results: There was significant difference in the SBS between the test groups (P<0.001. The mean bond strength of bonding brackets to silorane-based composite was (42.42 ± 7.03 MPa, and the mean bond strength of bonding brackets metacrylate-based composite was (21.08±2.97 MPa. No significant difference in the ART was found between groups (P=0.66.   Conclusion: Silorane-based composite provided higher bond strength to orthodontic metal brackets.

  20. Social-bond strength influences vocally mediated recruitment to mobbing.

    Science.gov (United States)

    Kern, Julie M; Radford, Andrew N

    2016-11-01

    Strong social bonds form between individuals in many group-living species, and these relationships can have important fitness benefits. When responding to vocalizations produced by groupmates, receivers are expected to adjust their behaviour depending on the nature of the bond they share with the signaller. Here we investigate whether the strength of the signaller-receiver social bond affects response to calls that attract others to help mob a predator. Using field-based playback experiments on a habituated population of wild dwarf mongooses (Helogale parvula), we first demonstrate that a particular vocalization given on detecting predatory snakes does act as a recruitment call; receivers were more likely to look, approach and engage in mobbing behaviour than in response to control close calls. We then show that individuals respond more strongly to these recruitment calls if they are from groupmates with whom they are more strongly bonded (those with whom they preferentially groom and forage). Our study, therefore, provides novel evidence about the anti-predator benefits of close bonds within social groups. © 2016 The Author(s).

  1. Light-curing efficiency of dental adhesives by gallium nitride violet-laser diode determined in terms of ultimate micro-tensile strength.

    Science.gov (United States)

    Kameyama, Atsushi; Kato, Junji; De Munck, Jan; Hatayama, Hitoshi; Haruyama, Akiko; Yoshinari, Masao; Takase, Yasuaki; Van Meerbeek, Bart; Tsunoda, Masatake

    2011-01-01

    The purpose of this study was to evaluate whether violet-laser diode (VLD) can be used as light-curing source. The ultimate (micro-)tensile strength (μTS) of three adhesives was determined when cured by VLD in comparison with curing by two different types of commercial LED light-curing units. One VLD (VLM 500) and two LED units (Curenos and G-Light Prima) were used to cure the adhesive resin of the two-step self-etch adhesives Clearfil SE Bond, Tokuso Mac Bond II, and FL-Bond II. A 0.6-mm thick acrylic mould was filled with adhesive resin and cured for 60 s. After 24-h water storage, specimens were trimmed into an hourglass shape with a width of 1.2 mm at the narrowest part, after which the μTS was determined (n=10). In addition, the light transmittance of each adhesive was characterized using a UV-vis-NIR spectrometer. No significant difference in curing efficiency between VLD and LED were observed for both Tokuso Mac Bond II and FL-Bond II (p>0.05). For Clearfil SE Bond, the μTS of VLD-cured specimens was higher than that of the specimens cured by the LED Curenos unit (p<0.05). Spectrometry revealed that this marked difference must be attributed to a different light transmittance of Clearfil SE Bond for visible blue light versus for the lower area of UV and visible violet light. In conclusion, A GaN-based violet laser diode can be used as light-curing source to initiate polymerization of dental resins.

  2. Comparison of the microtensile bond strength of different composite core materials and bonding systems to a fiber post (DT Light

    Directory of Open Access Journals (Sweden)

    Lelya Sadighpour

    2013-10-01

    Full Text Available   Background and Aims: Retention and stability of the post and core system is the key factor for success of final restoration . The aim of this study was to evaluate the microtensile bond strength of the different composite core materials and bonding systems to a fiber post.   Materials and Methods: To evaluate the bond strength of the composite resins to a fiber post ( DT light post 60 posts were divided into six groups : group A: Heliomolar Flow + Seal Bond, group B: Heliomolar Flow + SE Bond , group C: Valux Plus + Seal Bond , group D: Valux Plus + SE Bond , group E: Corecem + Seal Bond, group F: Corecem + SE Bond. All samples were thermocycled for 5000 cycles (5-55 0C and cut into four bars for the microtensile bond strength test. Failure modes were identified using a stereomicroscope. Data were analysed using One-way ANOVA and Tukey HSD post hoc test (P<0.05.   Results: The interaction between composite resin materials and bonding systems were positive. The conventional hybrid composite (Valux Plus had significantly higher bond strength compared with the core specific flowable composite (Corecem when Seal Bond was applied as bonding agent (P<0.05. However, when SE Bond was utilized hybrid composite demonstrated significantly lower bond strength than that of other two groups (P<0.05.   Conclusion: The performance of a particular composite is affected by the bonding system that is applied. A single composite resin may have different bond strength when combined with different bonding system.

  3. Effect of surface modifications on the bond strength of zirconia ceramic with resin cement resin.

    Science.gov (United States)

    Hallmann, Lubica; Ulmer, Peter; Lehmann, Frank; Wille, Sebastian; Polonskyi, Oleksander; Johannes, Martina; Köbel, Stefan; Trottenberg, Thomas; Bornholdt, Sven; Haase, Fabian; Kersten, Holger; Kern, Matthias

    2016-05-01

    Purpose of this in vitro study was to evaluate the effect of surface modifications on the tensile bond strength between zirconia ceramic and resin. Zirconia ceramic surfaces were treated with 150-μm abrasive alumina particles, 150-μm abrasive zirconia particles, argon-ion bombardment, gas plasma, and piranha solution (H2SO4:H2O2=3:1). In addition, slip casting surfaces were examined. Untreated surfaces were used as the control group. Tensile bond strengths (TBS) were measured after water storage for 3 days or 150 days with additional 37,500 thermal cycling for artificial aging. Statistical analyses were performed with 1-way and 3-way ANOVA, followed by comparison of means with the Tukey HSD test. After storage in distilled water for three days at 37 °C, the highest mean tensile bond strengths (TBS) were observed for zirconia ceramic surfaces abraded with 150-μm abrasive alumina particles (TBS(AAP)=37.3 MPa, TBS(CAAP)=40.4 MPa), and 150-μm abrasive zirconia particles (TBS(AZP)=34.8 MPa, TBS(CAZP)=35.8 MPa). Also a high TBS was observed for specimens treated with argon-ion bombardment (TBS(BAI)=37.8 MPa). After 150 days of storage, specimens abraded with 150-μm abrasive alumina particles and 150-μm abrasive zirconia particles revealed high TBS (TBS(AAP)=37.6 MPa, TBS(CAAP)=33.0 MPa, TBS(AZP)=22.1 MPa and TBS(CAZP)=22.8 MPa). A high TBS was observed also for specimens prepared with slip casting (TBS(SC)=30.0 MPa). A decrease of TBS was observed for control specimens (TBS(UNT)=12.5 MPa, TBS(CUNT)=9.0 MPa), specimens treated with argon-ion bombardment (TBS(BAI)=10.3 MPa) and gas plasma (TBS(GP)=11.0 MPa). A decrease of TBS was observed also for specimens treated with piranha solution (TBS(PS)=3.9 MPa, TBS(CPS)=4.1 MPa). A significant difference in TBS after three days storage was observed for specimens treated with different methods (p0.05), CAAP(p>0.05) and SC(p>0.05). However, the failure patterns of debonded specimens prepared with 150-μm abrasive zirconia

  4. Effect of activation modes on the compressive strength, diametral tensile strength and microhardness of dual-cured self-adhesive resin cements.

    Science.gov (United States)

    Kim, Ah-Rang; Jeon, Yong-Chan; Jeong, Chang-Mo; Yun, Mi-Jung; Choi, Jae Won; Kwon, Yong Hoon; Huh, Jung-Bo

    2016-01-01

    The purpose of this study was to compare the compressive strength, diametral tensile strength and microhardnss of several selfadhesive resin cements (Rely-X U200, Clearfill SA Luting, G-CEM LinkAce, Maxcem Elite, PermaCem 2.0, and Zirconite) using different activation modes (self-cured, light-cured) and testing time (immediately, 24 h, thermocycling). Specimens were prepared for the compressive strength (Ø 4×6 mm) and diametral tensile strength and microhardness (Ø 6×3 mm) according to ISO standards. The strength after 24 h was higher than immediately after. In addition, G-CEM showed the highest values. In terms of the activation modes, Rely-X U200, PermaCem 2.0 had higher values in the light-curing than the self-curing. In conclusion, all cements demonstrated clinically available strength values and revealed differences in strength according to their composition, testing time and activation mode. Furthermore, correlation was found between the microhardness (degree of conversion) and mechanical strengths of the cements tested.

  5. Effect of Normalizing Temperature on Fracture Characteristic of Tensile and Impact Tested Creep Strength-Enhanced Ferritic P92 Steel

    Science.gov (United States)

    Saini, N.; Pandey, C.; Mahapatra, M. M.

    2017-11-01

    The high-temperature Cr-Mo creep strength-enhanced ferritic (CSEF) steels are mainly used in nuclear and thermal power plants. In the present investigation, a systematic study on fracture surface morphologies of tensile and impact tested specimens and mechanical properties of cast and forged (C&F) P92 steel was performed for various heat treatment conditions. The heat treatment was carried out in normalizing temperature range of 950-1150 °C and then tempered to a fixed tempering temperature of 760 °C. The effect of varying normalizing temperatures before and after tempering on microstructure evolution, tensile properties, Vicker's hardness and Charpy toughness was studied. The normalizing temperature before and after tempering was having a noticeable effect on mechanical properties of as-received P92 steel. The fracture surface of impact and tensile tested samples was also studied for various normalizing temperatures with or without tempering. Fracture surface morphology was affected by the presence of secondary phase carbide particles. The fraction area of cleavage facets on the tensile fracture surface was found to be increased with an increase in the normalizing temperature. The fractured tensile specimens were characterized by transgranular ductile dimples, tear ridges and transgranular cleavage facets for various heat treatments. The fracture mode of impact tested samples was more complex. It showed both quasi-cleavage facets and ductile dimple tearing for various normalizing temperatures.

  6. Effect of Normalizing Temperature on Fracture Characteristic of Tensile and Impact Tested Creep Strength-Enhanced Ferritic P92 Steel

    Science.gov (United States)

    Saini, N.; Pandey, C.; Mahapatra, M. M.

    2017-10-01

    The high-temperature Cr-Mo creep strength-enhanced ferritic (CSEF) steels are mainly used in nuclear and thermal power plants. In the present investigation, a systematic study on fracture surface morphologies of tensile and impact tested specimens and mechanical properties of cast and forged (C&F) P92 steel was performed for various heat treatment conditions. The heat treatment was carried out in normalizing temperature range of 950-1150 °C and then tempered to a fixed tempering temperature of 760 °C. The effect of varying normalizing temperatures before and after tempering on microstructure evolution, tensile properties, Vicker's hardness and Charpy toughness was studied. The normalizing temperature before and after tempering was having a noticeable effect on mechanical properties of as-received P92 steel. The fracture surface of impact and tensile tested samples was also studied for various normalizing temperatures with or without tempering. Fracture surface morphology was affected by the presence of secondary phase carbide particles. The fraction area of cleavage facets on the tensile fracture surface was found to be increased with an increase in the normalizing temperature. The fractured tensile specimens were characterized by transgranular ductile dimples, tear ridges and transgranular cleavage facets for various heat treatments. The fracture mode of impact tested samples was more complex. It showed both quasi-cleavage facets and ductile dimple tearing for various normalizing temperatures.

  7. In vitro evaluation of the Long-term bond strength of two resin cements to enamel and dentin

    Directory of Open Access Journals (Sweden)

    Zahra Jaberi Ansari

    2014-04-01

    Full Text Available   Background and Aims : In this in vitro study, the long-term bond strength of a self-adhesive resin cement and conventional resin cements to human enamel and dentin was compared .   Materials and Methods: 80 sections of intact human third molars were randomly assigned into eight groups according to the cement type [Rely X Unicem (RXU, Rely X ARC (RXA], bond substrate (enamel, dentin and the duration of water storage (24 h or 1 year. Rods of cements (0.75×1 mm were prepared on the top surface of specimens using Tygon tubes. The micro-shear bond strengths of specimens were measured by a micro-tensile tester. Data were analyzed using Wilcoxon signed ranks and Mann Whitney tests ( α =0.05.   Results: The bond strengths of RXA and RXU cements to enamel after 24h were 18.56±4.08 MPa and 14.99±4.17 MPa, and after 1 year were 19.41±6.24 MPa and 15.51±6.17 MPa, respectively. The bond strengths of RXA and RXU cements to dentin were 13.36±4.02 MPa and 14.16±4.69 MPa after 24h , and 14.63±5.96 MPa and 14.08±6.72 MPa after 1 year, respectively. Tooth substrate had significant effect only on the shear bond strength of RXA cement after 24h (P=0.01, while no other significant differences were found in this study (P>0.05.   Conclusion: According to the results of this study, one-step self-adhesive and multi-step conventional resin cements were similarly effective in bonding to enamel and dentin after 1 year water storage.

  8. Microtensile Bond Strength of Translucent Glass Fiber Posts to Intra-radicular Dentin

    Directory of Open Access Journals (Sweden)

    N. Mohammadi

    2009-03-01

    Full Text Available Objective: The aim of the present study was to compare microtensile bond strengths (μTBS of glass fiber posts to different parts of intra-radicular dentin using conventional method and one-shot technique under different light intensities.Materials and Methods: Twenty-eight single-rooted teeth were prepared to receive fiber posts: Group 1: Conventional method at light intensity of 600 mW/cm2; Groups 2, 3 and 4:One-shot technique at light intensities of 600, 800 and 1000 mW/cm2 respectively. Dumbbell-shaped slices were obtained from the samples and submitted to micro-tensile testing.The data were analyzed using two-way ANOVA and paired-samples t-test.Results: There were no significant differences in μTBS values of the cervical and middle thirds between the groups (P>0.05. μTBS values in the cervical thirds in groups 2 and 3 were significantly higher than those in the middle thirds (P>0.05. However, there were nosuch differences in groups 1 and 4 (P>0.05.Conclusion: It is proper to simultaneously cure the resin cement and the adhesive agent (one-shot technique; however, in that case, high light intensities (1000 mW/cm2 are recommended to achieve identical bond strength values in the cervical and middle thirds.

  9. Effect of bonding variables on the shear bond strength and interfacial morphology of a one-bottle adhesive.

    Science.gov (United States)

    Medina, V; Shinkai, K; Shirono, M; Tanaka, N; Katoh, Y

    2001-01-01

    This study's objectives were: 1) to determine the combination of bonding procedures (with or without acid etching, moist or dry substrate, one or two applications of primer/adhesive) that would produce the highest shear bond strength of Prime & Bond and Dyract AP and 2) to characterize the resin-dentin/enamel interface produced by these bonding procedures. Ninety-six bovine incisors were randomly assigned to eight groups for shear bond testing to enamel (n = 6) and dentin (n = 6). Prime & Bond and Dyract AP were applied and cured following manufacturers' instructions. Shear bond testing was conducted in a Universal Testing Machine. Thirty-two bovine incisors were sectioned to produce blocks with enamel and dentin, then bonded in pairs for evaluation of interfacial morphology. They were polished and argon ion-etched using a high-speed argon ion-etching machine and examined by SEM. The groups where enamel was etched, kept moist or dry and received a single application of Prime & Bond produced the highest shear bond strength. Dentin bond strengths were high in the groups where dentin was etched and kept moist. The number of Prime & Bond applications had no effect on dentin bond strength. Acid etching results in better adaptation of Prime & Bond to enamel and dentin regardless of whether moisture is present.

  10. Shear bond strength of composite resin to high performance polymer PEKK according to surface treatments and bonding materials.

    Science.gov (United States)

    Lee, Ki-Sun; Shin, Myoung-Sik; Lee, Jeong-Yol; Ryu, Jae-Jun; Shin, Sang-Wan

    2017-10-01

    The object of the present study was to evaluate the shear bonding strength of composite to PEKK by applying several methods of surface treatment associated with various bonding materials. One hundred and fifty PEKK specimens were assigned randomly to fifteen groups (n = 10) with the combination of three different surface treatments (95% sulfuric acid etching, airborne abrasion with 50 µm alumina, and airborne abrasion with 110 µm silica-coating alumina) and five different bonding materials (Luxatemp Glaze & Bond, Visio.link, All-Bond Universal, Single Bond Universal, and Monobond Plus with Heliobond). After surface treatment, surface roughness and contact angles were examined. Topography modifications after surface treatment were assessed with scanning electron microscopy. Resin composite was mounted on each specimen and then subjected to shear bond strength (SBS) test. SBS data were analyzed statistically using two-way ANOVA, and post-hoc Tukey's test (P<.05). Regardless of bonding materials, mechanical surface treatment groups yielded significantly higher shear bonding strength values than chemical surface treatment groups. Unlike other adhesives, MDP and silane containing self-etching universal adhesive (Single Bond Universal) showed an effective shear bonding strength regardless of surface treatment method. Mechanical surface treatment behaves better in terms of PEKK bonding. In addition, self-etching universal adhesive (Single Bond Universal) can be an alternative bonding material to PEKK irrespective of surface treatment method.

  11. Weibull Analysis of the Behavior on Tensile Strength of Hemp Fibers for Different Intervals of Fiber Diameters

    Science.gov (United States)

    Rohen, Lázaro A.; Margem, Frederico M.; Neves, Anna C. C.; Gomes, Maycon A.; Monteiro, Sérgio N.; Vieira, Carlos Maurício F.; de Castro, Rafael G.; Borges, Gustavo X.

    Economic and environmental benefits are motivating studies on natural fibers, especially lignocellulosic extracted from plants, have been studied to substitute synthetic fibers, such as glass fiber as reinforcement in polymer matrices. By contrast to synthetic fibers, natural fibers have the disadvantage of being heterogeneous in their dimensions specially the diameter. About the hemp fiber, little is known of their dimensional characteristics. The aim of the present work was to statistically characterize the distribution of the diameter of hemp fibers. Based on this characterization, diameter intervals were set and the dependence of the tensile strength of theses fibers with a corresponding diameter was analyzed by the Weibull method. The diameter was measured with precision using a profile projector. Tensile tests were conducted on each fiber obtain mechanical strength. The results interpreted by Weibull statistical showed a correlation between the resistances of the fiber to its diameter.

  12. Comparative evaluation of the effects of a new biological adhesive (Colagel on the tensile strength and healing of intestinal anastomoses

    Directory of Open Access Journals (Sweden)

    José Luiz Laus

    1992-06-01

    Full Text Available The effects of a new biological adhesive based on a mixture of gelatin-resorcin and formaldehyde (Colagel for use as an adjuvant in the reinforcement, impermeabilization and healing of intestinal anastomoses were evaluated and compared to those obtained with omentun fixation, the standard procedure used for this purpose. Two ileal anastomoses were performed in each of 12 experimental dogs using an extramucosal technique and single plane sutures. One of the anastomoses in each animal was covered with adhesive and the other with omentun, in random order. The anastomosed intestinal segments were tested for tensile strength and analysed histopathologically 1, 3, 7, 14, 21 and 28 days after surgery. The tensile strength of the anastomoses treated by the two different procedures was statistically identical. Histopathology revealed normal healing evolution for both procedures on days 1, 3 and 7, and greater exudation in the adhesive group on days 14, 21 and 28 after surgery.

  13. An Experimental Study on Assessment of Pavement Interlayer Bond Strength

    Directory of Open Access Journals (Sweden)

    Mahabir Panda

    2013-06-01

    Full Text Available It is a common practice to apply a tack coat usually in the form of bituminous emulsion over an existing bituminous surface before laying another bituminous layer. The boundary between these two consecutive bituminous layers is the layer interface and the pavement stress distribution is highly influenced by the adhesion conditions at this interface. Poor adhesion causes adverse effects on the structural strength of the pavement system. A number of premature failures such as slippage failure and delamination failures result thus defeating the construction objectives. In the absence of a standard method and apparatus to address this field problem, an attempt has been made in this study to develop a simple testing arrangement to be used in a laboratory to determine the interlayer bond strength. Normal Marshall procedure has been used to prepare the specimens consisting of two different types of bituminous materials in lower and upper part of the same specimen. It is observed within the scope of study that Cationic rapid setting (CRS-1 emulsion applied at 0.25 Kg/m2 offers the best results of interlayer bond strength.

  14. Influence of reprocessing on fibre length distribution, tensile strength and impact strength of injection moulded cellulose fibre-reinforced polylactide (PLA composites

    Directory of Open Access Journals (Sweden)

    N. Graupner

    2016-08-01

    Full Text Available The present study focuses on the reprocessing behaviour of recycled injection moulded polylactide (PLA composites. The composites are reinforced with regenerated cellulose fibres (lyocell of variable fineness and a fibre mass content of 30%. They were reprocessed up to three times. The influence of reprocessing on the fibre length distribution and the resulting composite mechanical properties (tensile and impact strength was analysed. While the first reprocessing cycle does not affect the mechanical characteristics of the neat PLA matrix, the strength of the composites decreases significantly due to a decreasing fibre aspect ratio. It was shown that fibres having a larger cross-sectional area display a lower aspect ratio than finer fibres, after reprocessing. This phenomenon leads to a larger decrease in tensile strength of composites reinforced with coarser fibres when compared to composites reinforced with finer fibres. A comparison of virgin composites and threefold reprocessed composites with a similar fibre length distribution resulted in a significantly higher tensile strength compared to the virgin sample. This result leads to the conclusion that not only the fibre length is drastically reduced by reprocessing but also that the fibres and the matrix were damaged.

  15. Failure strength prediction for adhesively bonded single lap joints

    Science.gov (United States)

    Rahman, Niat Mahmud

    For adhesively bonded joint, failure strength depends on many factors such as material properties (both adhesive and adherend), specimen geometries, test environments, surface preparation procedures, etc. Failure occurs inside constitutive materials or along joint interfaces. Based on location, adhesively bonded failure mode can be classified as adhesive failure mode, cohesive failure mode and adherend failure mode. Failure mode directly affects the failure strength of joint. For last eight decades, resear