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Sample records for ii bonded amalgam

  1. Microleakage of Class II Combined Amalgam-Composite Restorations Using Different Composites and Bonding Agents

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    F. Sharafeddin

    2008-09-01

    Full Text Available Objective: The purpose of the present study was to assess the microleakage of composite restorations with and without a cervical amalgam base and to compare the results of dif-ferent composites and bonding agents.Materials and Methods: One hundred and twenty mesio-occlusal (MO and disto-occlusal (DO Class II cavities were prepared on sixty extracted permanent premolar teeth. The teeth were randomly divided into four groups of 30 and restored as follows:In group A, the mesio-occlusal cavity (MO, Scotchbond multi purpose plus + Z250 and in the disto-occlusal (DO cavity, Prompt-L-Pop + Z250 were applied. As for group B, in the MO and DO cavities, Clearfil SE Bond + Clearfil APX, and varnish + amalgam (In box + Clearfil SE Bond + Clearfil APX were used respectivelywhile in group C; the teeth were restored with amalgam and varnish mesio-occlusally and with amalgam only disto-occlusally. As for group D, varnish + amalgam (in box + Scotchbond multi purpose plus + Z250 were applied mesio-occlusally and Varnish + Amalgam (in box + Prompt–L–Pop + Z250 disto-occlusally.Marginal leakage was assessed by the degree of dye penetration into various sections of the restored teeth. Chi-square and Fisher's exact tests were used for data analysis.Results: Microleakage in gingival margin was more than that in occlusal margin (P<0.05 and microleakage of combined amalgam-composite restorations was significantly lower than that of conventional composite and amalgam restorations.Conclusion: Marginal microleakage decreased by using amalgam at the base of the box in Class II composite restorations.

  2. Fracture resistance of premolars with bonded class II amalgams.

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    Dias de Souza, Grace Mendonça; Pereira, Gisele Damiana Silveira; Dias, Carlos Tadeu Santos; Paulillo, Luis Alexandre Maffei Sartini

    2002-01-01

    This study evaluated the fracture resistance of maxillary premolars with MOD cavity preparation and simulated periodontal ligament. The teeth were restored with silver amalgam (G1), Scotchbond Multi-Purpose Plus and silver amalgam (G2) and Panavia F and silver amalgam (G3). After restorations were made, the specimens were stored at 37 degrees C for 24 hours at 100% humidity and submitted to the compression test in the Universal Testing Machine (Instron). The statistical analysis of the results (ANOVA and Tukey Test) revealed that the fracture resistance of group 2 (G2=105.720 kgF) was superior to those of groups 1 (G1=72.433 kgF) and 3 (G3=80.505 kgF) that did not differ between them.

  3. Bond strength of repaired amalgam restorations.

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    Rey, Rosalia; Mondragon, Eduardo; Shen, Chiayi

    2015-01-01

    This in vitro study investigated the interfacial flexural strength (FS) of amalgam repairs and the optimal combination of repair materials and mechanical retention required for a consistent and durable repair bond. Amalgam bricks were created, each with 1 end roughened to expose a fresh surface before repair. Four groups followed separate repair protocols: group 1, bonding agent with amalgam; group 2, bonding agent with composite resin; group 3, mechanical retention (slot) with amalgam; and group 4, slot with bonding agent and amalgam. Repaired specimens were stored in artificial saliva for 1, 10, 30, 120, or 360 days before being loaded to failure in a 3-point bending test. Statistical analysis showed significant changes in median FS over time in groups 2 and 4. The effect of the repair method on the FS values after each storage period was significant for most groups except the 30-day storage groups. Amalgam-amalgam repair with adequate condensation yielded the most consistent and durable bond. An amalgam bonding agent could be beneficial when firm condensation on the repair surface cannot be achieved or when tooth structure is involved. Composite resin can be a viable option for amalgam repair in an esthetically demanding region, but proper mechanical modification of the amalgam surface and selection of the proper bonding system are essential.

  4. The comparative evaluation of fracture resistance and microleakage in bonded amalgam, amalgam, and composite resins in primary molars.

    Science.gov (United States)

    Vanishree, H S; Shanthala, B M; Bobby, W

    2015-01-01

    The intense development of adhesive restorative materials and parents' preferences for esthetic restorations prompt clinicians to use alternative restorative materials for primary molars. Amalgam, however, is the choice of material when it comes to occlusal stress bearing areas, either in primary or permanent molars. To overcome the drawbacks of amalgam and restorative adhesive materials, the bonded amalgam technique is employed. To evaluate microleakage and fracture resistance of bonded amalgam in primary molars, and compare it with the microleakage and fracture resistance of high-copper amalgam and composite resin materials. An in vitro study and 60 caries-free primary molars were used. A total of 60 samples were randomly divided into two equal groups for the evaluation of microleakage and fracture resistance. Class V cavities for microleakage study prepared on 30 samples and Class II mesio-occluso-distal cavities for fracture resistance study on other 30 samples were prepared and randomly divided into three equal groups. Group I received amalgam, Group II received bonded amalgam, and Group III received composite resins. The microleakage was viewed under a stereomicroscope. The fracture resistance was evaluated using a universal testing machine. Bonded amalgam exhibited minimum microleakage, when compared to amalgam and composite resin and was found to be statistically insignificant (P = 0.203), while amalgam showed better fracture resistance compared to bonded amalgam and composite resin. It was found to be statistically insignificant (P = 0.144). Bonded amalgam appears to be comparable to amalgam when microleakage is considered and to composite resin when fracture resistance is considered; hence, bonded amalgam can also be an alternative material to amalgam in primary molars.

  5. Microleakage of different amalgams bonded with dual cure resin cements.

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    Lombard, R; du Preez, I C; Oberholzer, T G

    2007-03-01

    To reduce microleakage in high-copper amalgam restorations, bonding of amalgam was introduced. This study compared the microleakage of admixed and spherical amalgams when bonded with different bonding intermediates under thermo- and non-thermocycling conditions. Class II butt-joint cavities were prepared in 200 extracted human molar teeth, and randomly divided into 5 groups. Calibra, Duo Cement Plus, RelyX ARC and Amalgambond Plus were applied to 4 of these groups. The fifth group was left untreated. The groups were further divided and restored with either Dispersalloy or Oralloy Magicap S. Ten specimens of each group were thermocycled between 5 degrees C and 55 degrees C, placed in basic fuchsin for 8 hours, sectioned and evaluated for dye penetration under 40X magnification. The mean microleakage scores were analysed using the chi-squared test at a confidence level of 95%. Microleakage of the non-bonded amalgams was significantly higher (p amalgams (thermocycled and non-thermocycled). The microleakage of the different intermediates bonded to Dispersalloy (thermocycled and non-thermocycled) was not significantly different (p > 0.05). The microleakage of the different intermediates was not significant different except for Duo Cement compared to Calibra (p amalgams was not significantly increased by thermocycling (p > 0.05). The microleakage of the two amalgams when bonded with the same resin cements (thermocycled and non-thermocycled) was not significantly different except for Duo Cement (thermocycled) (p = 0.0051) and RelyX (non-thermocycled) (p = 0.0356). Bonding amalgam restorations to tooth structure in butt-joint cavities will reduce microleakage of both admixed and spherical amalgam restorations. Thermal stress does not affect the bond adversely.

  6. In vitro bond strengths of amalgam added to existing amalgams.

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    Roggenkamp, Clyde L; Berry, Frederick A; Lu, Huan

    2010-01-01

    This study determined if a standardized condensation force and dwell time per condensation pressure point could reliably bond new amalgam to older amalgam without applying extrinsic Hg. A stabilization jig was created to hold 15 friction-fit 1-inch diameter (25 mm) cylindrical resin specimen blocks face up with cavities drilled to contain the condensed primary amalgam (Valiant PhD-XT). Freshly mixed secondary amalgam (Valiant PhD-XT) was condensed against the primary amalgam surfaces through the 3.5-mm-diameter central holes of specially fabricated split-ring molds. The 15 disks fit snugly within the holes of the stabilization jig tray. Condensation was with a consistent, calibrated force of 22.5 MPa (4 lbs/0.79 mm2) applied with a spring-loaded amalgam carrier custom adapted with a 1-mm-diameter stainless steel condenser tip. Secondary amalgam additions were built up in three 1-mm thick increments with a pattern of eight 22.5 MPa two-second condenser strokes per incremental layer. Shear-bond testing with a 1-mm/minute crosshead speed occurred 24-hours post-condensation. One-way analysis of variance statistical analysis was conducted to analyze the results. The mean shear-bond forces (MPa, N = 15) found were: Control 28.1 +/- 5, 15 minutes 31 +/-5, one hour 10.7 +/-4 (N = 30), one day 25.5 +/- 4, one week 25.2 +/- 4, two months 25.1 +/- 5 and seven years 24.7 +/- 4. Under the condensation pressures used in the current study, the addition of new amalgam to smooth previously set amalgam surfaces, not including the one-hour group, up to seven years old, resulted in shear-bond forces not statistically different (p = 0.05) from the intact control. Virtually all (94%) of the bonds tested, except for the one-hour sample, resulted in cohesive rather than adhesive failures except those of the one-hour sample. Forty percent bond strengths of the controls were achieved when only 5.6 MPa (1 lb/0.79 mm2) and 14 MPa (2.5 lb/0.79 mm2) condensation pressures were used.

  7. The comparative evaluation of fracture resistance and microleakage in bonded amalgam, amalgam, and composite resins in primary molars

    Directory of Open Access Journals (Sweden)

    H S Vanishree

    2015-01-01

    Conclusions: Bonded amalgam appears to be comparable to amalgam when microleakage is considered and to composite resin when fracture resistance is considered; hence, bonded amalgam can also be an alternative material to amalgam in primary molars.

  8. No available evidence to assess the effectiveness of bonded amalgams.

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    Murad, Mohammed

    2009-01-01

    Sources of data were the Cochrane Oral Health Group's Trials Register, Cochrane CENTRAL (Cochrane Library), Medline and Embase. Reference lists of relevant articles were also searched and the investigators of the included studies were contacted for details of additional published and unpublished trials. Randomised controlled trials (RCT) were chosen that compared adhesively bonded versus traditional nonbonded amalgam restorations in conventional preparations utilising deliberate retention, in adults with permanent molar and premolar teeth suitable for Class I and II amalgam restorations only. Two review authors independently screened papers, extracted trial details and assessed the risk of bias in the included study. One trial was included, comprising 31 patients who received 113 restorations. At 2 years, only three out of 53 restorations in the nonbonded group were lost, which was attributed to a lack of retention, and 55 out of 60 bonded restorations survived, with five unaccounted for at followup. Postinsertion sensitivity was not significantly different (P >0.05) at baseline or 2-year followup. No fractures of tooth tissue were reported and there was no significant difference between the groups or matched pairs of restorations in their marginal adaptation (P >0.05). There is no evidence to either claim or refute a difference in survival between bonded and nonbonded amalgam restorations. This review only found one methodologically sound but somewhat under-reported trial. This trial did not find any significant difference in the in-service performance of moderately sized adhesively bonded amalgam restorations, in terms of their survival rate and marginal integrity, in comparison with nonbonded amalgam restorations over a 2-year period. In view of the lack of evidence on the additional benefit of adhesively bonding amalgam compared with with nonbonded amalgam, it is important that clinicians are mindful of the additional costs that may be incurred.

  9. Shear bond strength of the amalgam-resin composite interface.

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    Machado, Camilo; Sanchez, Eliana; Alapati, Satish; Seghi, Robert; Johnston, William

    2007-01-01

    This study compared the initial and one year shear bond strengths (SBS) of resin composite bonded to amalgam using Amalgambond-Plus. Resin composite cylinders (Point 4, Kerr Corporation) were bonded to either etched-enamel (A), 50% etched enamel-50% polished amalgam (B), airborne-particle abraded amalgam (C), carbide bur prepared amalgam (D) and airborne-particle abraded 50% amalgam-50% etched-enamel (E). Shear bond strengths were determined using a standardized testing device (Ultradent Products) in a universal testing machine (Instron model 4204). The failed interfaces were evaluated with SEM to obtain visual evidence of the failure mode. ANOVA indicated significant differences among the groups (p composite masking has the strongest, most durable SBS on airborne-particle abraded amalgam and airborne-particle abraded enamel-amalgam surfaces and could be used as a method to improve the esthetics of amalgam restorations.

  10. 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

  11. Microleakage of bonded amalgam restorations using different adhesive agents with dye under vacuum: an in vitro study.

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    Parolia, Abhishek; Kundabala, M; Gupta, Vaibhav; Verma, Mudita; Batra, Chandni; Shenoy, Ramya; Srikant, N

    2011-01-01

    In an effort to minimize tooth preparation, yet provide additional retention to compromised tooth structure, bonded amalgam restorations were introduced. Various resin-based adhesives have been tried earlier under bonded amalgam restorations. Still there are controversies regarding the outcome of bonded amalgam restorations regarding their adaptability to the tooth structure and microleakage. Therefore, this study was undertaken to compare the microleakage of bonded amalgam restorations using different adhesive materials. Standard Class I cavities were prepared on occlusal surfaces of 60 human molars. Teeth (n=60) were divided into three groups according to the material employed, as follows: group I: amalgam with glass ionomer cement (GIC) (type I); group II: amalgam with resin cement (Panavia F 2.0) and group III: amalgam with Copalex varnish as a control. Following restoration, the teeth were submitted to thermal cycling. The teeth were subsequently immersed in 2% rhodamine B dye under vacuum for 48 hours and sectioned to allow the assessment of microleakage under stereomicroscope. The values were tabulated and the results were statistically analyzed using analysis of variance (ANOVA), Tukey's post hoc test and Kruskal-Wallis test. Amalgam with type I GIC showed the least leakage with no statistically significant difference (P value 0.226) when compared to amalgam with Panavia F 2.0 and amalgam with varnish (P value 0.107). It can be concluded that bonded amalgam with type I GIC is a good alternative to amalgam with resin cement (Panavia F 2.0) and amalgam with varnish for large restorations, with the added advantages of GICs. Bonded amalgam restorations prevent over-preparation and reduce the tooth flexure. GIC type I under amalgam provides chemical bonding in between amalgam and tooth structure and thus reduces the microleakage.

  12. Repair of amalgam restorations with composite resin and bonded amalgam: A microleakage study

    Directory of Open Access Journals (Sweden)

    Daniela Araújo Veloso Popoff

    2011-01-01

    Conclusions: The use of adhesive systems significantly affected the ability to seal the repair/ tooth interface. However, at the level of the repair/restoration interface, the bonded amalgam technique may increase microleakage.

  13. Amalgam stained dentin: a proper substrate for bonding resin composite?

    NARCIS (Netherlands)

    Scholtanus, J.D.

    2016-01-01

    Nowadays the use of dental amalgam is mostly abandoned and substituted by tooth colored resin composites that can be bonded to teeth tissues by adhesive techniques. The aim of this thesis was to find out whether dark stained dentin, as often observed after removal of amalgam restorations and

  14. Longevity of conventional and bonded (sealed) amalgam restorations in a private general dental practice.

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    Bonsor, S J; Chadwick, R G

    2009-01-24

    To compare and contrast the longevity of conventionally placed dental amalgam restorations with those placed using bonding techniques. Retrospective survival analysis (Kaplan Meier) of dental amalgam restorations placed by a single operator in a private general dental practice. The records relating to dental amalgam restorations placed between 1 August 1996 and 31 July 2006 were sourced. The details of these were placed into a database that permitted flexible interrogation. Survival data on conventionally placed amalgams (C) and those bonded with either Panavia Ex (PE) or Rely X ARC (RX) were exported into a statistical package to permit survival analysis by the method of Kaplan and Meier.Results The number of restorations available for analysis were C = 3,854, PE = 51 and RX = 1,797. Percentage survival at one year was C = 96.29, PE = 95.65, and RX = 97.58. Percentage survival at five years was C = 86.21, PE = 76.35 and RX = 82.59. A Log Rank test demonstrated no statistically significant difference (p >0.05) in survival between the restoration types. Amalgam restorations bonded with PE or RX exhibited an acceleration of failure rate around 1,000 days post-placement. Further survival analyses of the method of restoration versus type of restored teeth (molar/premolar) and cavity preparation (Class I/II) showed no significant difference in the survival curves in respect of type of restored tooth. In the comparison of Class I and II cavities, the survival curves for the restorations differed significantly (p p = 0.2634). This was also the case for the Class II restorations (p = 0.2260). Within the limitations of the study, bonding amalgams, compared to placing them conventionally, afforded no significant benefit upon restoration longevity. This, coupled with the emerging trend of an accelerating decline in longevity of bonded amalgams from 1,000 days onwards and with the greater cost, challenges the justification for routine bonding of amalgams.

  15. A comparative study of bonded and non-bonded amalgam restorations in general dental practice.

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    Worskett, P

    2013-04-01

    This study compared the performance of non-bonded and bonded amalgam restorations in a general dental practice. A retrospective cohort study was carried out in a general dental practice of amalgam restorations, placed by a single operator. Non-bonded amalgam restorations were analysed over a ten-year period and bonded amalgam restorations over a five-year period. Survival analysis using the Kaplan-Maier method was carried out and an analysis of postoperative sensitivity and reasons for failure. Each group consisted of 231 restorations in 135 patients. Survival rates of non-bonded amalgam restorations were 72.2% over five years and 51.0% over ten years. The survival rate for bonded amalgam restorations was 85.0% over five years. The difference was significant (p amalgam restorations demonstrated greater longevity over non-bonded amalgam restorations and offer significant benefit to patients. Clinicians may feel confident to offer bonded amalgam restorations for their patients as a better alternative than non-bonded amalgam restorations.

  16. Repair of amalgam restorations with composite resin and bonded amalgam: a microleakage study.

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    Popoff, Daniela Araújo Veloso; Gonçalves, Fabiana Santos; Magalhães, Cláudia Silami; Moreira, Allyson Nogueira; Ferreira, Raquel Conceição; Mjör, Ivar A

    2011-01-01

    Total replacement is the most common technique for defective amalgam restorations, and it represents a major part of restorative dental treatment. Repair is an alternative option for amalgam restorations with localized defects. This study compared microleakage of amalgam restorations repaired by bonded amalgam or composite resin. Thirty extracted human pre-molars were prepared and restored with class I amalgam. A simulated defect was prepared that included the cavosurface margin on restorations, and the pre-molars were assigned to two treatment groups (n=15): In group 1, premolars were treated by composite resin (34% Tooth Conditioner Gel + Adper Single Bond 2 + Z100) and in group 2, premolars were repaired by bonded amalgam (34% Tooth Conditioner Gel + Prime and Bond 2.1 + Permite C). The teeth were immersed in a 50% silver nitrate solution, thermocycled, sectioned longitudinally and then observed by three examiners using a stereomicroscope. Microleakage was evaluated using a 0-4 scale for dye penetration, and data was analyzed by Kruskal Wallis and Dunn tests. Neither of the two methods eliminated microleakage completely. Composite resin was significantly the most effective for repair/tooth interface sealing (score 0 = 80.0%; P=0.0317). For the repair/restoration interface, composite resin was also statistically more effective as a sealant (score 0=66%; P=0.0005) when compared to the bonded amalgam technique (score 0=13%; P=0.0005). The use of adhesive systems significantly affected the ability to seal the repair/ tooth interface. However, at the level of the repair/restoration interface, the bonded amalgam technique may increase microleakage.

  17. Adhesively bonded versus non-bonded amalgam restorations for dental caries.

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    Agnihotry, Anirudha; Fedorowicz, Zbys; Nasser, Mona

    2016-03-08

    Dental caries (tooth decay) is one of the commonest diseases which afflicts mankind, and has been estimated to affect up to 80% of people in high-income countries. Caries adversely affects and progressively destroys the tissues of the tooth, including the dental pulp (nerve), leaving teeth unsightly, weakened and with impaired function. The treatment of lesions of dental caries, which are progressing through dentine and have caused the formation of a cavity, involves the provision of dental restorations (fillings). This review updates the previous version published in 2009. To assess the effects of adhesive bonding on the in-service performance and longevity of dental amalgam restorations. We searched the Cochrane Oral Health Group Trials Register (to 21 January 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2015, Issue 12), MEDLINE via Ovid (1946 to 21 January 2016) and EMBASE via Ovid (1980 to 21 January 2016). We also searched the US National Institutes of Health Trials Registry (http://clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (www.who.int/ictrp/search/en) (both to 21 January 2016) for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. Randomised controlled trials comparing adhesively bonded versus traditional non-bonded amalgam restorations in conventional preparations utilising deliberate retention, in adults with permanent molar and premolar teeth suitable for Class I and II amalgam restorations only. Two review authors independently screened papers, extracted trial details and assessed the risk of bias in the included study. One trial with 31 patients who received 113 restorations was included. At two years, 50 out of 53 restorations in the non-bonded group survived, and 55 of 60 bonded restorations survived with five unaccounted for at follow-up. Post-insertion sensitivity was not significantly different

  18. Electrochemical study of insulating properties of dental amalgam bonding polymers

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    Toumelin-Chemla, Florence; Degrange, Michel [Faculte de Chirurgie Dentaire de Paris V, Montrouge (France)

    1998-06-01

    The standard techniques used for amalgam restorations often result in a lack of adhesion to mineralized dental tissues. The bonding of amalgam with polymer has been suggested to improve its adaptation to dental tissues. Moreover the polymer involved in the bonding should inhibit the corrosion and the diffusion of metallic ions. The aim of this study was to evaluate in vitro the capacity of bonded amalgam to prevent ionic diffusion and migration. In this respect, an original method employing electrochemical techniques was used to determine the leakage current of bonded amalgam restorations. The electrochemical behaviour of conventional and bonded amalgam restorations was compared using a potentiostat driven by a computerized system (Voltamaster, Radiometer Analytical) with software for specific applications such as chronoamperometry or cyclic voltammetry. Samples of recently extracted teeth of young patients were first examined, and then the results were checked by other experimental assays using protected and unprotected copper sticks. The measurements obtained with chronoamperometry (E=+300 mV/SCE) in Ringer's solution at 37 deg. C showed that after polarization for 30 h the oxidation current decreased threefold for bonded samples (10 {mu}A cm{sup -2}) as compared with the unprotected samples (35 {mu}A cm{sup -2}). These results, as well as those obtained with the copper wires, demonstrated that even with two layers of adhesive the bonded joint is permeable to ions probably as a result of the hydrophylic properties of HEMA, a component of the adhesive. However, using five layers of adhesive reduced the ionic current by a factor as large as 10{sup 6}. (author)

  19. Critical appraisal: dental amalgam update--part II: biological effects.

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    Wahl, Michael J; Swift, Edward J

    2013-12-01

    Dental amalgam restorations have been controversial for over 150 years. In Part I of this Critical Appraisal, the clinical efficacy of dental amalgam was updated. Here in Part II, the biological effects of dental amalgam are addressed. © 2013 The Authors.Journal of Esthetic and Restorative Dentistry © 2013 Wiley Periodicals, Inc.

  20. Microleakage of bonded amalgam restorations using different adhesive agents with dye under vacuum: An in vitro study

    Directory of Open Access Journals (Sweden)

    Abhishek Parolia

    2011-01-01

    Clinical Significance: Bonded amalgam restorations prevent over-preparation and reduce the tooth flexure. GIC type I under amalgam provides chemical bonding in between amalgam and tooth structure and thus reduces the microleakage.

  1. Improved orthodontic bonding to silver amalgam. Part 2. Lathe-cut, admixed, and spherical amalgams with different intermediate resins.

    Science.gov (United States)

    Büyükyilmaz, T; Zachrisson, B U

    1998-08-01

    Flat rectangular tabs (n = 270) prepared from spherical (Tytin), admixed (Dispersalloy) or lathe-cut amalgam (ANA 2000) were subjected to aluminum oxide sandblasting with either 50-mu or 90-mu abrasive powder. Mandibular incisor edgewise brackets were bonded to these tabs. An intermediate resin was used, either All-Bond 2 Primers A + B or a 4-META product--Amalgambond Plus (AP) or Reliance Metal Primer (RMP)--followed by Concise. All specimens were stored in water at 37 degrees C for 24 hours and thermocycled 1000 times from 5 degrees C to 55 degrees C and back before tensile bond strength testing. The bond strength of Concise to etched enamel of extracted, caries-free premolars was used as a control. Bond failure sites were classified using a modified adhesive remnant index (ARI) system. Results were expressed as mean bond strength with SD, and as a function relating the probability of bond failure to stress by means of Weibull analysis. Mean tensile bond strength in the experimental groups ranged from 2.9 to 11.0 MPa--significantly weaker than the control sample (16.0 MPa). Bond failure invariably occurred at the amalgam/adhesive interface. The strongest bonds were created to the spherical and lathe-cut amalgams (range 6.8 to 11.0 MPa). Bonds to the spherical amalgam were probably more reliable. The intermediate application of the 4-META resins AP and RMP generally created significantly stronger bonds to all three basic types of amalgam products than the bonds obtained with the All-Bond 2 primers. The effect of abrasive-particle size on bond strength to different amalgam surfaces was not usually significant (p > 0.05). The implications of these findings are discussed in relationship to clinical experience bonding orthodontic attachments to large amalgam restorations in posterior teeth.

  2. The comparative evaluation of fracture resistance and microleakage in bonded amalgam, amalgam, and composite resins in primary molars

    OpenAIRE

    H S Vanishree; B M Shanthala; W Bobby

    2015-01-01

    Background : The intense development of adhesive restorative materials and parents′ preferences for esthetic restorations prompt clinicians to use alternative restorative materials for primary molars. Amalgam, however, is the choice of material when it comes to occlusal stress bearing areas, either in primary or permanent molars. To overcome the drawbacks of amalgam and restorative adhesive materials, the bonded amalgam technique is employed. Aims: To evaluate microleakage and fracture re...

  3. Bonded amalgams and their use in clinical practice.

    Science.gov (United States)

    Bonsor, Stephen J

    2011-05-01

    There has been a move in recent years for operative dentists to use the benefits of adhesive technology when placing dental amalgam restorations. This paper describes the potential advantages of the bonded amalgam technique. These benefits include decreased microleakage between the cavity wall and the restorative material. This, in turn, may decrease post-operative sensitivity, pulpal inflammation and the incidence of recurrent caries. Extra retention for the restoration may also be provided and the need for cavities to rely on traditional retention and resistance form may be decreased or even eliminated, thus conserving precious tooth tissue. If the restoration is bonded then flexure during function in teeth may be decreased and, in the case of teeth exhibiting a cracked cusp, this may alleviate or eliminate symptoms. Bonding may also provide support to weakened tooth tissue which otherwise would have to be removed, so rendering cavities more conservative, and may increase the fracture resistance of the tooth. Clinical examples are included to illustrate some of these benefits. The use of adhesives to bond amalgam to tooth tissue offers potential advantages, although some of the current evidence is equivocal about their routine use.

  4. Summary of: a comparative study of bonded and non-bonded amalgam restorations in general dental practice.

    Science.gov (United States)

    Chadwick, R G

    2013-04-01

    This study compared the performance of non-bonded and bonded amalgam restorations in a general dental practice. A retrospective cohort study was carried out in a general dental practice of amalgam restorations, placed by a single operator. Non-bonded amalgam restorations were analysed over a ten-year period and bonded amalgam restorations over a five-year period. Survival analysis using the Kaplan-Maier method was carried out and an analysis of postoperative sensitivity and reasons for failure. Each group consisted of 231 restorations in 135 patients. Survival rates of non-bonded amalgam restorations were 72.2% over five years and 51.0% over ten years. The survival rate for bonded amalgam restorations was 85.0% over five years. The difference was significant (p amalgam restorations demonstrated greater longevity over non-bonded amalgam restorations and offer significant benefit to patients. Clinicians may feel confident to offer bonded amalgam restorations for their patients as a better alternative than non-bonded amalgam restorations.

  5. Shear bond strength, failure modes, and confocal microscopy of bonded amalgam restorations.

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    Cianconi, Luigi; Conte, Gabriele; Mancini, Manuele

    2011-01-01

    This study evaluated the shear bond strength, failure modes, and confocal microscopy of two different amalgam alloy restorations lined with five adhesive systems. Two regular-set high-copper dental amalgam alloys, Amalcap Plus and Valiant Ph.D, and five commercially available adhesive systems were selected. One hundred and twenty freshly-extracted human third molars were used for the study. The results were statistically evaluated using two-factor analysis of variance (ANOVA). The shear bond strength (SBS) of amalgam to dentin was significantly affected by both the adhesive (pamalgam alloy (p<0.0002). Regarding mode of failure (MF), among samples restored with Valiant Ph.D, 31 of 50 exhibited adhesive failure, and 19 displayed mixed failure. Laser optical microscopy (OM) of the bonded interface revealed the presence of a good hybrid layer was evident in all experimental groups. Higher bond strengths were measured for four of the five adhesives when used in combination with the spherical alloy.

  6. Bond strength of resin composite to differently conditioned amalgam.

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    Ozcan, M; Vallittu, P K; Huysmans, M-C; Kalk, W; Vahlberg, T

    2006-01-01

    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=84) were condensed into acrylic and randomly assigned to one of the following treatments (N=6): (1) Alloy primer + opaquer, (2) Air-particle abrasion (50 micro m Al(2)O(3)) + alloy primer + opaquer, (3) Silica coating (30 micro m SiO(x)) + silanization + opaquer, (4) Opaquer + pre-impregnated continuous bidirectional E-glass fibre sheets, (5) Silica coating + silanization + fibre sheets, (6) Silica coating + silanization + opaquer + fibre sheet application. Non-conditioned amalgam surfaces were considered as control group (7). The mean surface roughness depth (R(Z)) was measured from the control group and air-abraded amalgam surfaces. The resin composite was bonded to the conditioned amalgam specimens using polyethylene molds. All specimens were tested under dry and thermocycled (6.000, 5-55 degrees C, 30 s) conditions. The shear bond strength of resin composite to amalgam substrates was measured in a universal testing machine (1 mm/min). Surface roughness values for the non-conditioned control group (R(Z) approximately 0.14 micro m) and for air-particle abraded surfaces with either Al(2)O(3) or SiO(x) (R(Z) approximately 0.19 micro m and R(Z) approximately 0.16 micro m, respectively) did not show significant differences (p=0.23) (One-way ANOVA). In dry conditions, silica coating and silanization followed by fibre sheet application exhibited significantly higher results (14.8+/-5.6 MPa) than those of the groups conditioned with alloy primer (2.2+/-0.7 MPa) (p<0.001), air-particle abrasion+alloy primer (4.4+/-2.0 MPa, p<0.001), silica coating+silanization alone (6.2+/-0.8 MPa, p=0.009) or non-conditioned group (1.4+/-0.6, p<0.001). Silica coating and silanization followed

  7. Bonded amalgams and their use in clinical practice.

    Science.gov (United States)

    Bonsor, S J

    2011-06-01

    There has been a move in recent years for operative dentists to use the benefits of adhesive technology when placing dental amalgam restorations. This paper describes the potential advantages of the bonded amalgam technique. These benefits include decreased microleakage between the cavity wall and the restorative material. This, in turn, may decrease post-operative sensitivity, pulpal inflammation and the incidence of recurrent caries. Extra retention for the restoration may also be provided and the need for cavities to rely on traditional retention and resistance form may be decreased or even eliminated, thus conserving precious tooth tissue. If the restoration is bonded then flexure during function in teeth may be decreased and, in the case of teeth exhibiting a cracked cusp, this may alleviate or eliminate symptoms. Bonding may also provide support to weakened tooth tissue which otherwise would have to be removed, so rendering cavities more conservative, and may increase the fracture resistance of the tooth. Clinical examples are included to illustrate some of these benefits.

  8. A 3-year randomized clinical trial evaluating two different bonded posterior restorations: Amalgam versus resin composite.

    Science.gov (United States)

    Kemaloglu, Hande; Pamir, Tijen; Tezel, Huseyin

    2016-01-01

    To compare the performance and postoperative sensitivity of a posterior resin composite with that of bonded amalgam in 40 (n = 20) large sized cavities and to evaluate whether resin composite could be an alternative for bonded amalgam. This was a randomized clinical trial. Twenty patients in need of at least two posterior restorations were recruited. Authors randomly assigned one half of the restorations to receive bonded amalgam and the other half to composite restorations. Forty bonded amalgams (n = 20) and composites (n = 20) were evaluated for their performance on modified-US Public Health Service criteria and postoperative sensitivity using visual analogue scale (VAS) for 36-months. Success rate of this study was 100%. First clinical alterations were rated as Bravo after 1 year in marginal discoloration, marginal adaptation, anatomical form, and surface roughness for both amalgam and composite. At the 3(rd) year, overall "Bravo" rated restorations were 12 for bonded amalgam and 13 for resin composites. There were no significant differences among the VAS scores of composites and bonded amalgams for all periods (P > 0.05) except for the comparisons at the 3(rd) year evaluation (P composite and bonded amalgam were clinically acceptable. Postoperative sensitivity results tend to decrease more in composite restorations rather than amalgams. Therefore, it was concluded that posterior resin composite can be used even in large sized cavities.

  9. A 3-year randomized clinical trial evaluating two different bonded posterior restorations: Amalgam versus resin composite

    Science.gov (United States)

    Kemaloglu, Hande; Pamir, Tijen; Tezel, Huseyin

    2016-01-01

    Objective: To compare the performance and postoperative sensitivity of a posterior resin composite with that of bonded amalgam in 40 (n = 20) large sized cavities and to evaluate whether resin composite could be an alternative for bonded amalgam. Materials and Methods: This was a randomized clinical trial. Twenty patients in need of at least two posterior restorations were recruited. Authors randomly assigned one half of the restorations to receive bonded amalgam and the other half to composite restorations. Forty bonded amalgams (n = 20) and composites (n = 20) were evaluated for their performance on modified-US Public Health Service criteria and postoperative sensitivity using visual analogue scale (VAS) for 36-months. Results: Success rate of this study was 100%. First clinical alterations were rated as Bravo after 1 year in marginal discoloration, marginal adaptation, anatomical form, and surface roughness for both amalgam and composite. At the 3rd year, overall “Bravo” rated restorations were 12 for bonded amalgam and 13 for resin composites. There were no significant differences among the VAS scores of composites and bonded amalgams for all periods (P > 0.05) except for the comparisons at the 3rd year evaluation (P amalgam were clinically acceptable. Postoperative sensitivity results tend to decrease more in composite restorations rather than amalgams. Therefore, it was concluded that posterior resin composite can be used even in large sized cavities. PMID:27011734

  10. Early failure of Class II resin composite versus Class II amalgam restorations placed by dental students.

    Science.gov (United States)

    Overton, J D; Sullivan, Diane J

    2012-03-01

    Using the information from remake request slips in a dental school's predoctoral clinic, we examined the short-term survival of Class II resin composite restorations versus Class II dental amalgam restorations. In the student clinic, resin composite is used in approximately 58 percent of Class II restorations placed, and dental amalgam is used in the remaining 42 percent. In the period examined, Class II resin composite restorations were ten times more likely to be replaced at no cost to the patient than Class II dental amalgam restorations. A total of eighty-four resin composite restorations and six amalgam restorations were replaced due to an identified failure.

  11. Microleakage of a 4-methacryloxyethyl trimellitate anhydride bonding agent with amalgams.

    Science.gov (United States)

    Chang, J C; Chan, J T; Chheda, H N; Iglesias, A

    1996-05-01

    Microleakage contributes to deterioration of materials, recurrent decay, growth of microorganisms at the interface, and postoperative tooth sensitivity. This study examined the microleakage between amalgams and tooth surfaces with a cavity liner, a 4-methacryloxyethyl trimellitate anhydride bonding agent (Amalgambond) and six different types of amalgams. Class 1 cavity preparations in extracted human molars were filled with different combinations of liners and amalgams and were stored at 37 degrees C in physiologic saline solution. After 1 week half of each amalgam restoration was removed. Within the same group the same cavity treatment was performed and the same type of amalgam was packed as before. Microleakage was determined after 2000 thermal cycles. Statistical analysis indicated that Amalgambond significantly reduced microleakage of different amalgams compared with the Copalite-lined and unlined controls. No microleakage was detected at the interface between the existing and replacement amalgams.

  12. Radial multipliers on amalgamated free products of II-factors

    DEFF Research Database (Denmark)

    Möller, Sören

    2014-01-01

    Let ℳi be a family of II1-factors, containing a common II1-subfactor 풩, such that [ℳi : 풩] ∈ ℕ0 for all i. Furthermore, let ϕ: ℕ0 → ℂ. We show that if a Hankel matrix related to ϕ is trace-class, then there exists a unique completely bounded map Mϕ on the amalgamated free product of the ℳi with a...... with amalgamation over 풩, which acts as a radial multiplier. Hereby, we extend a result of Haagerup and the author for radial multipliers on reduced free products of unital C*- and von Neumann algebras....

  13. [Is amalgam stained dentin a proper substrate for bonding resin composite?].

    Science.gov (United States)

    Scholtanus, J D

    2016-06-01

    After the removal of amalgam restorations, black staining of dentin is often observed, which is attributed to the penetration of corrosion products from amalgam. A study was carried out to determine whether this amalgam stained dentin is a proper substrate for bonding resin composites. A literature study and an in vitro study showed that Sn and Zn in particular are found in amalgam stained dentin, and this was the case only in demineralised dentin. In vitro, demineralised dentin acted as porte d'entrÈe for amalgam corrosion products. Bond strength tests with 5 adhesive strategies showed no differences between bond strengths to amalgam stained and to sound dentin, but did show different failure types. A clinical study showed good survival of extensive cusp replacing resin composite restorations. No failures were attributed to inadequate adhesion. It is concluded that staining of dentin by amalgam corrosion products has no negative effect upon bond strength of resin composite. It is suggested that Sn and Zn may have a beneficial effect upon dentin, thus compensating the effects of previous carious attacks, preparation trauma and physico-chemical challenges during clinical lifetime.

  14. The effect of surface conditioning on the bond strength of resin composite to amalgam.

    Science.gov (United States)

    Blum, Igor R; Hafiana, Khaula; Curtis, Andrew; Barbour, Michele E; Attin, Thomas; Lynch, Christopher D; Jagger, Daryll C

    2012-01-01

    This study evaluated the effect of different surface conditioning methods on the tensile bond strength (TBS) and integrity of the amalgam-resin composite interface, using commercially available restoration repair systems. One hundred and sixty Gamma 2 amalgam specimens were stored in artificial saliva for 2 weeks and then randomly assigned to one of the following conditioning groups (n=20/group): Group 1: air abrasion, alloy primer and 'Panavia 21', Group 2: air abrasion and 'Amalgambond Plus', Group 3: air abrasion and 'All-Bond 3', Group 4: diamond bur, alloy primer and 'Panavia 21', Group 5: diamond bur and 'Amalgambond Plus', Group 6: diamond bur and 'All-Bond 3', Group 7: silica coating technique, and Group 8: non-conditioned amalgam surfaces (control group). Subsequently, resin composite material was added to the substrate surfaces and the amalgam-resin composite specimens were subjected to TBS testing. Representative samples from the test groups were subjected to scanning electron microscopy and surface profilometry. The data was analysed statistically with one-way ANOVA and post hoc Tukey's tests (α=0.05). The mean TBS of amalgam-resin composite ranged between 1.34 and 5.13MPa and varied with the degree of amalgam surface roughness and the type of conditioning technique employed. Significantly highest TBS values (5.13±0.96MPa) were obtained in Group 1 (p=0.013). Under the tested conditions, significantly greater tensile bond strength of resin composite to amalgam was achieved when the substrate surface was conditioned by air abrasion followed by the application of the Panavia 21 adhesive system. Effecting a repair of an amalgam restoration with resin composite via the use of air abrasion and application of Panavia 21 would seem to enhance the integrity of the amalgam-resin composite interface. Clinical trials involving the implementation of this technique are indicated to determine the usefulness of this technique. Copyright © 2011 Elsevier Ltd. All

  15. In vitro evaluation of the marginal microleakage of class II amalgam restoration associated with dentin adhesive

    Directory of Open Access Journals (Sweden)

    OLIVEIRA Fabiana Sodré de

    1999-01-01

    Full Text Available The marginal microleakage of class II amalgam restorations (Dispersalloy associated with copal varnish (Copalite and with two dentin bonding agents (Scotchbond Multi-uso Plus and Multi Bond Alpha was evaluated in vitro and compared by two methods: scores and linear measurements. Forty-five sound premolars were used, on which two separated class II cavities were prepared on the M and D surfaces. After the restoration, the specimens were thermocycled and stored in a solution of 0.5% basic fuchsin during 24 hours. The analysis allowed to conclude that none of the three restorative systems were able to eliminate the marginal microleakage. Nevertheless, the leakage was significantly smaller on the restorations associated with dentin bonding agents when compared to copal varnish. The linear measurement method was more sensitive than the score criteria.

  16. The influence of long term water immersion on shear bond strength of amalgam repaired by resin composite and mediated by adhesives or resin modified glass ionomers.

    Science.gov (United States)

    Pilo, R; Nissan, J; Shafir, H; Shapira, G; Alter, E; Brosh, T

    2012-07-01

    To assess the shear bond strength between amalgam and resin composite mediated by either multipurpose adhesive systems or RMGI when subjected to long term immersion in saline. Part I: Cylindrical specimens (6 mm × 6 mm) composed of equal parts of sandblasted set amalgam (Oralloy) and composite (Z-100), with a thin layer of either Scotchbond Multipurpose, All Bond 2, Amalgam Bond Plus, High Q Bond Plus or Vitrebond in between were fabricated (n = 100 × 5). Each group was divided into 3 subgroups, immersed in saline at 37 °C for either 48 h, 3 or 6 months, followed by thermocycling (5000; 5/55 °C) and shear bond strength testing (SBS). Part II: Identical specimens were fabricated with intermediary of either Ketac Cem, Fuji Lining LC, Rely X Luting, Fuji Plus or Meron Plus (n = 100 × 5). Immersion periods, followed by thermocycling and SBS testing as in Part I. Two representative specimens from each subgroup were sectioned and inspected under SEM. The two classes of intermediary agents yielded SBS which differed mainly in the 6 months incubation period. While multipurpose adhesives provided SBS values of ~9-10 MPa RMGI provided higher SBS of ~16 MPa. All Bond 2 and Amalgam Bond Plus exhibited deterioration of SBS during the 6 month period as well as Rely X Luting. Gap sizes between 0.5 and 3 μm exist between all intermediaries and the amalgam; on the other hand all intermediaries exhibit gap-free interfaces between the adhesives/RMGI and the composite. Vitrebond in particular and RMGIs in general can serve as an excellent coupler of resin composite to amalgam, providing a durable bond. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Bond strength comparison of amalgam repair protocols using resin composite in situations with and without dentin exposure.

    Science.gov (United States)

    Ozcan, Mutlu; Schoonbeek, Geert; Gökçe, Bülent; Cömlekoglu, Erhan; Dündar, Mine

    2010-01-01

    The replacement of defective amalgam restorations leads to loss of tooth material and weakens the tooth, creating an increased risk of cusp fracture. The repair of such defects is a minimal intervention technique. The current study compared the repair bond strengths of a resin composite to amalgam and an amalgam-dentin complex after various surface conditioning methods. The specimens (N = 50) consisted of sound human canines with cylindrical preparations (diameter: 2.3 mm, depth: 3 mm) with amalgam-dentin complex (N = 30, n = 10/per group) and two groups with amalgam only (N = 20, n = 10/per group). The teeth were embedded in auto-polymerized polymethylmethacrylate (PMMA). The preparations were filled with non-Gamma 2 amalgam. The enamel was removed to expose dentin. The specimens with the amalgam-dentin complex were randomly assigned to one of the following conditioning methods: Group 1: Silicacoating amalgam, etching dentin, silane application on amalgam, primer/bonding on dentin, opaquer on amalgam, resin composite on both; Group 2: Etching dentin, silicacoating amalgam, silane application on amalgam, primer/bonding on dentin, opaquer on amalgam, resin composite on both and Group 3: Etching dentin, primer/bonding on dentin, opaquer, resin composite. The specimens with only amalgam were assigned to one of the following conditioning methods: Group 4: Silicacoating, silane application, opaquer, resin composite and Group 5: Opaquer, resin composite. For the two control groups, where no dentin was involved (Groups 4 and 5), bonding was achieved only on amalgam and Group 5 had no conditioning. The specimens were kept in water at 37 degrees C for five weeks before bond strength (MPa +/- SD) testing (Universal Testing Machine). After debonding, the failure types were analyzed. The results were significantly affected by the surface conditioning method (ANOVA). Only dentin conditioning (Group 3) showed the highest bond strength (39.9 +/- 14). The unconditioned control

  18. Shear bond strength of amalgam to dentin using different dentin adhesive systems

    Directory of Open Access Journals (Sweden)

    Farimah Sardari

    2012-01-01

    Full Text Available Background and Aims: The aim of this in vitro study was to assess the shear bond strength of amalgam to dentin using four dentin adhesive systems.Materials and Methods: One hundred human molars were selected. After enamel removal, a dentin cylinder with 3 mm thickness was prepared. Eighty specimens were resorted with amalgam and four dentin adhesive systems as follows (n=20: group 1, Scotch Bond Multi-Purpose; group 2, One Coat Bond; group 3, PQ1; and group 4, Panavia-F. In group 5, 20 specimens were resorted with amalgam and varnish as control group. The specimens were incubated at 37°C for 24 h. The shear bond strengths were then measured by using push out method. The data were analyzed by one-way ANOVA and post hoc Duncan's tests.Results: Mean values for bond strengths of test groups were as follows: group 1=21.03±8.9, group 2=23.47±9, group 3=13.16±8.8, group 4=20.07±8.9 and group 5=14.15±8.7 MPa±SD. One-way ANOVA showed the statistically significant difference between the bond strengths of five groups (P=0.001. Post hoc Duncan's test showed significant difference between groups 1and 3 (P=0.008, groups 1 and 5 (P=0.019, groups 2 and 5 (P=0.0008, groups 4 and 5 (P=0.042, and groups 3 and 4 (P=0.018.Conclusion: Results of this study showed that the bond strength of amalgam to dentin using One Coat Bond as dentin adhesive system was higher than that observed in other dentin adhesive systems.

  19. The bonded amalgam restoration--a review of the literature and report of its use in the treatment of four cases of cracked-tooth syndrome.

    Science.gov (United States)

    Bearn, D R; Saunders, E M; Saunders, W P

    1994-05-01

    Recent interest in amalgam as a restorative material has been directed toward the development of the bonded amalgam restoration. The literature regarding the theoretical and clinical aspects of this technique is reviewed. Four cases of successful treatment of cracked-tooth syndrome with the bonded amalgam restoration are presented.

  20. Short-term clinical evaluation of post-operative sensitivity with bonded amalgams.

    Science.gov (United States)

    Kennington, L B; Davis, R D; Murchison, D F; Langenderfer, W R

    1998-08-01

    To compare the in vivo short-term post-operative sensitivity of teeth restored with amalgam using a bonded resin liner vs. teeth restored using a copal varnish liner. 20 patients received Class I or Class II contralaterally paired restorations which were placed at the same appointment. All restorations were placed by the same operator using an identical technique except that, in each randomized pair, one was lined with an adhesive resin (Scotchbond Multi-Purpose Plus) while the other was lined with copal varnish. (Plastodent) Patients were provided visual analog scale response forms, instructed in their use, and requested to complete and return a form reporting their degree of sensitivity at baseline and on days 1, 3, 7, 14, and 30 post-operatively. Data from the response forms were analyzed for differences using a paired t-test. A response rate of 90% (18/20) was achieved for the complete 30-day assessment. Increases in thermal sensitivity beyond baseline were seen in 13 of the 18 subjects involving 12 restorations lined with copal varnish and 10 lined with adhesive resin. Typically, sensitivity peaked on day 1 or day 3 and diminished to pre-operative levels by day 30. Only three subjects reported greater sensitivity at day 30 than at baseline. No significant difference in post-operative sensitivity was found between the two cavity lining materials at any post-operative interval.

  1. Resistance of composite and amalgam core foundations retained with and without pins and bonding agents.

    Science.gov (United States)

    Imbery, Terence A; Swigert, Ryan; Richman, Brian; Sawicki, Vincent; Pace, Lauren; Moon, Peter C

    2010-01-01

    To compare the resistance of different amalgam and composite core foundations retained by pins, bonding agents, or both, 100 molars were mounted in acrylic resin and their occlusal surfaces were reduced to expose dentin. Pins were inserted at the four line angles of the teeth and matrices were placed. Bonding agents were applied according to the manufacturers' instructions. Amalgam was handcondensed and composite was incrementally added and photocured. Restorations were adjusted to produce specimens (n = 10) 5 mm in height with a 1 mm bevel at the axial-occlusal surface. After immersion in deionized water for 24 hours, specimens were loaded at a 45 degree angle on their beveled surfaces in a Universal Testing Machine at a crosshead speed of 0.02 in./minute. ANOVA and Tukey's tests indicated that FluoroCore 2 (with or without pins) was statistically stronger than all other combinations (p < 0.05).

  2. In vitro evaluation of marginal microleakage of class II bonded amalgam restorations using a dentin adhesive and a glass ionomer cement Avaliação in vitro da microinfiltração marginal em restaurações de amálgama tipo classe II usando adesivo dentinário e cimento de ionômero de vidro

    Directory of Open Access Journals (Sweden)

    Edmêr Silvestre PEREIRA JÚNIOR

    1999-04-01

    Full Text Available The purpose of this study was to evaluate in vitro the effectiveness of the dentin bonding system All Bond 2 associated with Resinomer (Bisco, and of Vitrebond (3M glass ionomer cement fresh-mixed, both used in the bonded amalgam technique, to prevent short-term microleakage in class II cavities restored with Dispersalloy (Dentsply, an admixed alloy. The control group utilized the Copalite (Cooley & Cooley varnish. Forty five sound human extracted premolars were used. Class II cavity preparations were made on the mesial and distal surfaces of non-carious teeth, with the gingival margins wall established 1mm under the cementum enamel junction. The specimens were divided randomly into three groups with thirty cavities in each group. The teeth were stored in distilled water for 24 hours and were thermocyled through 500 cycles in distilled water between 5°C and 55°C with a dwell time of 15 seconds. The apices and roots of the teeth were sealed. They were placed in a 37°C bath of 0.5% basic fuchsin dye for 24 hours. The teeth were washed in tap water for 24 hours and cut. The microleakage scores per restoration were averaged and three values of various test groups were subjected to the Kruskal-Wallis and Dunn test at a significance level of p O objetivo deste estudo foi avaliar in vitro a efetividade na prevenção da microinfiltração do sistema adesivo All Bond 2 associado ao Resinomer (Bisco, e do cimento de ionômero de vidro Vitrebond (3M, sem polimerização, em amálgama adesivo classe II, restauradas com Dispersalloy (Dentsply. No grupo controle utilizou-se o verniz cavitário Copalite (Cooley & Cooley. Para tanto, 45 pré-molares humanos íntegros e extraídos, com finalidade ortodôntica, receberam cavidades classe II, sendo uma na face mesial e outra na face distal de cada dente, com a parede cervical localizada a 1mm além da junção cemento-esmalte, sendo 30 cavidades em cada grupo. Após as restaurações os dentes foram estocados

  3. Clinical evaluation of bonded amalgam restorations in endodontically treated premolar teeth: a one-year evaluation.

    Science.gov (United States)

    Ahrari, Farzaneh; Nojoomian, Mahsima; Moosavi, Horieh

    2010-10-14

    The aim of this clinical study was to compare the fracture resistance, marginal adaptation, and rate of recurrent caries of bonded and nonbonded amalgam restorations in endodontically treated premolar teeth. A total of 36 patients with endodontically treated maxillary first or second premolars were selected and divided into three groups. The treatments in all groups consisted of lingual cusp coverage and cementation of a prefabricated intracanal post (No. 2 long, Dentatus USA, New York, NY, USA). One type of cavity liner was used for each group as follows: copal varnish (Group A), Amalgambond Plus (Group B), and Scotchbond Multi-Purpose (Group C). The teeth were then restored with Cinalux high-copper spherical amalgam (Cinalux, Sh. Dr Faghihi Dental Co., Tehran, Iran). After one year, fracture resistance, marginal adaptation, and secondary caries were evaluated. Fischer's exact test was used for statistical analysis using a 0.05 percent significance level. There was no significant difference among groups with respect to fracture resistance (p=0.49). However, significant differences in marginal adaptation existed among the three groups (p=0.02) and no recurrent caries were found in any of the restored teeth. Bonding amalgam restorations using Amalgambond Plus and Scotchbond Multi-Purpose Plus did not improve the fracture resistance or affect the resistance to secondary caries in endodontically treated premolar teeth. However, the teeth in both these bonded groups showed significant improvement in marginal adaptation compared with restorations placed with copal varnish (p=0.02). Amalgambond Plus or Scotchbond Multi-Purpose adhesive resins significantly improved marginal adaptation of amalgam compared with copal varnish, but did not enhance fracture resistance or affect the prevention of secondary caries.

  4. Effects of different surface conditioning methods on the bond strength of composite resin to amalgam.

    Science.gov (United States)

    Ozcan, M; Koolman, C; Aladag, A; Dündar, M

    2011-01-01

    Repairing amalgam restorations with composite resins using surface conditioning methods is a conservative treatment approach. This study investigated the effects of different conditioning methods that could be used for repair of amalgam fractures. Amalgam (N=96) was condensed into cavities within autopolymerizing polymethylmethacrylate (PMMA), and the exposed surface of each specimen (diameter, 6 mm; thickness, 2 mm) was ground finished. The specimens were randomly divided into nine experimental groups (n=12 per group), depending on the conditioning method used. The control group had natural central incisors with amalgam (n=12). The combination of the following conditioning methods was tested: silicacoating (Sc), sandblasting (Sb), metal primers, coupling agents, fiber (Fb) application, and opaquers (O). Five types of silanes, metal primers, or adhesives (Visiobond [V], Porcelain Photobond [PP], Alloy Primer [AP], Unibond sealer [Us], ESPE-Sil [ES]), and four opaquers, namely, Clearfil St Opaquer (CstO), Sinfony (S), Miris (M), and an experimental Opaquer (EO-Cavex), were used. The groups were as follows: group 1, Sc+ES+S+V; group 2, Sc+ES+CstO+V; group 3, Sc+ES+M+V; group 4, Sc+ES+EO+V; group 5, Sb+AP+S; group 6, Sb+AP+PP+CstO; group 7, Sc+ES+S+Fb+V+Fb; group 8-control, SC+ES+V; and group 9, Etch+Sc+ES+S+Us. One repair composite was used for all groups (Clearfil Photo Bond Posterior, Kuraray, Tokyo, Japan). Shear bond strengths (SBSs) (MPa ± SD) were evaluated after 5 weeks of water storage (analysis of variance [ANOVA], Tukey honestly significant differences [HSD], α=0.05). Group 1 exhibited significantly higher values (35.5 ± 4.1) than were seen in group 4 (19.4 ± 8.9), group 6 (19.1 ± 7.8), and group 8 (20.1 ± 4.1) (pcomposite adhesion to amalgam. Experimental opaquer exhibited lower values. Leaving a small border of enamel around the restoration decreased the bond strength.

  5. Analysis of the diametral compressive bond strength between composite resin and amalgam in different stages of oxidation.

    Science.gov (United States)

    Benitez Catirse, A B E; Oliveira Pagnano, V; Da Silva Mello, A S; Do Nascimento, C; Mardegan Issa, J P

    2007-04-01

    Amalcomp is a technique that combines composite resin to amalgam in restorative procedures to improve esthetics and minimize the negative effects of polymerization on dental tissues. The objective of this in vitro study was to measure the diametral compressive bond strength between Fill Magic composite (Vigodent) versus Permite (DFL) or Velvalloy (SS White) amalgams in different oxidation stages. Twenty-four cylinders of each amalgam brand were fabricated using a Teflon matrix and divided into 3 groups according to the immersion period in artificial saliva for oxidation: A (1 day), B (7 days) and C (30 days). After immersion, the amalgam cylinders were bonded to the composite specimens using the Scotch Bond Multi Use Plus (3M) bonding system. Diametral compression assays were then carried out in an EMIC-MEM 2000 universal testing machine set to 0.5 mm/min. Statistical analysis was performed using ANOVA and Tukey's test. The mean recorded strength (MPa) for each oxidation group was: A=9.71, B=8.21 and C=6.98 (A>B = C; Pcomposite than Velvalloy (9.36; Pamalgam showed the greatest diametral compressive strength values.

  6. Clinical Success Rate of Compomer and Amalgam Class II Restorations in First Primary Molars: A Two-year Study

    OpenAIRE

    Faezeh Ghaderi; Ali Mardani

    2015-01-01

    Background and aims. The majority of failures in Class II amalgam restorations occur in the first primary molar teeth; in addition, use of compomer instead of amalgam for primary molar teeth restorations is a matter of concern. The aim ofthe present study was to compare the success rate of Class II compomer and amalgam restorations in the first primary molars. Materials and methods. A total of 17 amalgams and 17 compomer restorations were placed in 17 children based on a split-mouth design...

  7. Effect of amalgam corrosion products in non-discolored dentin on the bond strength of replaced composite resin.

    Science.gov (United States)

    Ghavamnasiri, Marjaneh; Eslami, Samaneh; Ameri, Hamide; Chasteen, Joseph E; Majidinia, Sara; Moghadam, Fatemeh Velayaty

    2015-01-01

    To evaluate the effect of amalgam corrosion products in non-discolored dentin on the bond strength of replaced composite resin. One hundred and sixty-one Class I cavities were prepared on extracted premolars and divided into seven groups. Group 1: Light-cured composite; Groups 2, 3, and 4: Amalgam stored in 37°C normal saline for respectively 1, 3, and 6 months and then replaced with composite leaving the cavity walls intact. Groups 5, 6, and 7: Identical to Groups 2, 3, and 4, except the cavity walls were extended 0.5 mm after amalgam removal. Eighteen specimens from each group were selected for shear bond strength testing, while on remaining five samples, elemental microanalysis was conducted. Data were analyzed using Mann-Whitney and Freidman (α = 0.05). There was a significant difference between Groups 1 and 4 and also between Group 1 and Groups 5, 6, and 7. However, Groups 1, 2, and 3 showed no significant difference regarding bond strength. Bond strengths of Group 4 was significantly less than Groups 2 and 3. However, Groups 5, 6, and 7 showed similar bond strength. There was no difference among all groups in terms of metal elements at any storage times.

  8. Clinical Success Rate of Compomer and Amalgam Class II Restorations in First Primary Molars: A Two-year Study

    Directory of Open Access Journals (Sweden)

    Faezeh Ghaderi

    2015-06-01

    Full Text Available Background and aims. The majority of failures in Class II amalgam restorations occur in the first primary molar teeth; in addition, use of compomer instead of amalgam for primary molar teeth restorations is a matter of concern. The aim ofthe present study was to compare the success rate of Class II compomer and amalgam restorations in the first primary molars. Materials and methods. A total of 17 amalgams and 17 compomer restorations were placed in 17 children based on a split-mouth design. Restorations were assessed at 12- and 24-month intervals for marginal integrity, the anatomic form and recurrent caries. Data were analyzed with SPSS 11. Chi-squared test was applied for the analysis. Statistical significance was set at P<0.05. Results. A total 34 restorations of 28 restorations (14 pairs of the total restorations still survived after 24 months. Compomer restorations showed significantly better results in marginal integrity. Recurrent caries was significantly lower in compomer restorations compared to amalgam restorations. Cumulative success rate at 24-month interval was significantly higher in compomer restorations compared to amalgam restorations. There was no statistically significant difference in anatomic form between the two materials. Conclusion. Compomer appears to be a suitable alternative to amalgam for Class II restorations in the first primary mo-lars.

  9. Clinical Success Rate of Compomer and Amalgam Class II Restorations in First Primary Molars: A Two-year Study.

    Science.gov (United States)

    Ghaderi, Faezeh; Mardani, Ali

    2015-01-01

    Background and aims. The majority of failures in Class II amalgam restorations occur in the first primary molar teeth; in addition, use of compomer instead of amalgam for primary molar teeth restorations is a matter of concern. The aim ofthe present study was to compare the success rate of Class II compomer and amalgam restorations in the first primary molars. Materials and methods. A total of 17 amalgams and 17 compomer restorations were placed in 17 children based on a split-mouth design. Restorations were assessed at 12- and 24-month intervals for marginal integrity, the anatomic form and recurrent caries. Data were analyzed with SPSS 11. Chi-squared test was applied for the analysis. Statistical significance was set at Pamalgam restorations. Cumulative success rate at 24-month interval was significantlyhigher in compomer restorations compared to amalgam restorations. There was no statistically significant difference inanatomic form between the two materials. Conclusion. Compomer appears to be a suitable alternative to amalgam for Class II restorations in the first primary mo-lars.

  10. Factors influencing dentists' choice of amalgam and tooth-colored restorative materials for Class II preparations in younger patients.

    Science.gov (United States)

    Vidnes-Kopperud, Simen; Tveit, Anne Bjørg; Gaarden, Torunn; Sandvik, Leiv; Espelid, Ivar

    2009-01-01

    To identify factors associated with dentists' decisions on choice of restorative material in children and adolescents. In the period 2001-2004, 27 dentists in the Public Dental Health Service in Norway placed 4030 Class II restorations in 1912 patients. The reason for placement, previous caries experience (DMFT), oral hygiene, and characteristics of the cavity were recorded. The most frequently used material was resin composite (81.5%), followed by compomer (12.7%), amalgam (4.6%), and glass ionomer cement (1.2%). Tooth-colored restorations were more frequently placed than amalgam in younger patients (p=0.017). Female patients received fewer amalgam restorations than male patients (p=0.006). Amalgam was more often used in patients with high DMFT (pp=0.021). Amalgam was more frequently placed in molars than in premolars (pamalgam in more challenging restorations with respect to caries activity, lesion depth, and tooth type. The findings indicate that in a period when the use of amalgam was phasing out, resin composite was the predominant material of choice for Class II restorations in children and adolescents.

  11. An evaluation on microleakage and gap width of different dentin bonding agents in high copper amalgam restorations

    Directory of Open Access Journals (Sweden)

    Ghavam-Nasiri M. Associate Professor

    2003-07-01

    Full Text Available Statement of Problem: A lot of efforts have been made to create a complete adaptation between tooth"nand amalgam restorations."nPurpose: The aim of this study was to evaluate microleakage and interfacial micromorphology of"namalgam restorations lined with dentin adhesives, namely One Coat Bond, Syntac, Excite and Copalite,"nas liners."nMaterials and Methods: 144 intact human canine teeth were selected. Then class V cavities, with"nenamel and dentinal margins, were prepared on each of them. Cavities were lined with different dentin"nbonding systems (Syntac, One Coat Bond and Excite according to the manufacturer's instructions and"nrestored with Oralloy and Cinalloy, non gamma 2 spherical amalgams and Aristaloy a non gamma 2"nAdmixed alloy. Copalite was used in the group, served as controls. After thirty days storage in synthetic"nsaliva at 37°c, the specimens were thermocycled in saliva (4000 cycles. The degree of microleakage was"nassessed by means of basic fushin dye penetration and recorded. The gap width was evaluated with"nScanning Electron Microscope. Pearson and %2 tests were used to analyze the results."nResults: None of the systems, tested in this study, eliminated microleakage completely, Pearson's"ncorrelation coefficient showed a positive correlation between gap and microleakage (P<0/05.Statistical"nsignificant differences were revealed among the liners regarding gap and microleakage (P<0.05."nOne Coat Bond and Syntac appeared to leak less than other groups. The gap width by One Coat Bond"nand Syntac were respectively 0.35 and 0.3 urn in dentine, 0.2 and 0.1 in enamel. Excite and copalite gap"nwidth in dentine and enamel were 1,3-1.36 urn and 0.3-0.6, respectively. The type of amalgam did not"nhave any effect in the degree of microleakage and gap width (P>0/05."nConclusion: One Coat Bond and Syntac, comparing to Excite and Copalite, showed less microleakage"nand gap width.

  12. Detection of proximal secondary caries at cervical class II-amalgam restoration margins in vitro.

    Science.gov (United States)

    Neuhaus, K W; Rodrigues, J A; Seemann, R; Lussi, A

    2012-06-01

    To compare the performance of LFpen (DIAGNOdent pen) with two different wedge-shaped tips to conventional bitewing radiography (BW) for detecting proximal secondary caries at the cervical margin of amalgam restorations in vitro. Seventy-five molars with class II amalgam restorations were selected. Depending on the marginal filling extension, data was subdivided into a crown group (C), when the filling ended in enamel, and into a root group (R), when the filling ended beyond the cementum-enamel junction. Bayesian analysis including calculation of the area under the receiver operating curve (AUC) was performed. Furthermore, Spearman correlations between caries and cofactors, such as presence of plaque or stain, occlusal ditching, marginal gap size, filling overhangs, and shortfalls, were calculated. Additionally, for group R the correlation coefficient between LFpen measurements and lesion depth was calculated. Histology served as gold standard. In group C both at the D1 and D3 levels, LFpen with two different tips showed a better performance than bitewing radiography (AUC at D1: 0.83/0.79 (LFpen) and 0.63 (BW); at D3: 0.66/0.66 (LFpen) and 0.53 (BW)). In group R, the respective AUC values were 0.53/0.56 (LF) and 0.59 (BW). A significant medium correlation was observed for occlusal ditching and proximal caries. Stain accumulation at the restoration margins especially in combination with filling overhangs interfered with LFpen readings, resulting in false positive measurements. Compared to BW, LFpen enhances the detection of secondary caries lesions at the cervical margin of amalgam restorations that do not extend below the cementum-enamel junction. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Potential of Brass to Remove Inorganic Hg(II) from Aqueous Solution through Amalgamation.

    Science.gov (United States)

    Wenke, Axel; Bollen, Anne; Richard, Jan-Helge; Biester, Harald

    2016-06-01

    Brass shavings (CuZn45) were tested for their efficiency to remove Hg(II) from contaminated groundwater through amalgamation. The study was focused on long-term retention efficiency, the understanding of the amalgamation process and kinetics, and influences of filter surface alteration. Column tests were performed with brass filters (thickness 3 to 9 cm) flushed with 1000 μg/L Hg solution for 8 hours under different flow rates (300 to 600 mL/h). Brass filters consistently removed >98% of Hg from solution independent of filter thickness and flow rate. In a long-term experiment (filter thickness 2 cm), Hg retention decreased from 96 to 92% within 2000 hours. Batch and column experiments for studying kinetics of Hg removal indicate ~100% Hg removal from solution within only 2 hours. Solid-phase mercury thermo-desorption analysis revealed that Hg(0) diffusion into the brass surface controls kinetics of mercury retention. Brass surface alteration could be observed, but did not influence Hg retention.

  14. Does Magnetic Resonance Imaging Affect the Microleakage of Amalgam Restorations?

    International Nuclear Information System (INIS)

    Akgun, Ozlem Marti; Polat, Gunseli Guven; Turan Illca, Ahmet; Yildirim, Ceren; Demir, Pervin; Basak, Feridun

    2014-01-01

    The effect of MRI on microleakage of amalgam restorations is an important health issue that should be considered. If MRI application causes increase of microleakage, amalgam fillings should be reassessed after MRI and replaced if necessary. The aim of this study is to compare the effect of magnetic resonance imaging (MRI) on microleakage of class II bonded amalgam versus classical amalgam restorations. Class II cavities (3 mm width × 1.5 mm depth) with gingival margins ending 1 mm below the cementoenamel junction (CEJ) were prepared in 40 permanent molar teeth. The teeth were randomly divided into four groups. Cavities in the first and second groups were restored with dentin adhesive and amalgam (bonded amalgam), and those in the third and fourth groups with amalgam only. MRI was performed with the teeth specimens from the first and third groups. All specimens were then thermocycled at 5° to 55° C with a 30-second dwell time for 1000 cycles. The samples were then immersed in 0.5% methylene blue dye for 24 hours and sectioned longitudinally. Dye penetration at the occlusal and gingival margins was quantified by 15× stereomicroscopy. IBM SPSS Statistics ver. 21.0 (IBM Corp., Released 2012., IBM SPSS Statistics for Windows, Armonk, NY: IBM Corp.) and MS-Excel 2007 programs were used for statistical analyses and calculations. “nparLD” module was used for F2-LD-F1 design analysis at R program. P<0.05 was considered statistically significant. In teeth with amalgam filling, there were no significant differences of occlusal and gingival surface microleakage after MRI exposure. Occlusal and gingival surface microleakages were also similar with and without MRI in teeth with bonded amalgam filling. The results of this study suggest that MRI does not increase microleakage of amalgam restorations

  15. Dental Amalgam

    Science.gov (United States)

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

  16. Reasons for failure and replacement of class I and class II amalgam ...

    African Journals Online (AJOL)

    Aim: The aim of this study is to evaluate the reasons for failure of amalgam restorations in a teaching hospital. Method: A structured questionnaire was used to obtain information from patients presenting with failed amalgam restorations in the conservative clinic of a teaching hospital. The questionnaire was administered by ...

  17. Does magnetic resonance imaging affect the microleakage of amalgam restorations?

    Science.gov (United States)

    Akgun, Ozlem Marti; Polat, Gunseli Guven; Turan Illca, Ahmet; Yildirim, Ceren; Demir, Pervin; Basak, Feridun

    2014-08-01

    The effect of MRI on microleakage of amalgam restorations is an important health issue that should be considered. If MRI application causes increase of microleakage, amalgam fillings should be reassessed after MRI and replaced if necessary. The aim of this study is to compare the effect of magnetic resonance imaging (MRI) on microleakage of class II bonded amalgam versus classical amalgam restorations. Class II cavities (3 mm width × 1.5 mm depth) with gingival margins ending 1 mm below the cementoenamel junction (CEJ) were prepared in 40 permanent molar teeth. The teeth were randomly divided into four groups. Cavities in the first and second groups were restored with dentin adhesive and amalgam (bonded amalgam), and those in the third and fourth groups with amalgam only. MRI was performed with the teeth specimens from the first and third groups. All specimens were then thermocycled at 5° to 55° C with a 30-second dwell time for 1000 cycles. The samples were then immersed in 0.5% methylene blue dye for 24 hours and sectioned longitudinally. Dye penetration at the occlusal and gingival margins was quantified by 15× stereomicroscopy. IBM SPSS Statistics ver. 21.0 (IBM Corp., Released 2012., IBM SPSS Statistics for Windows, Armonk, NY: IBM Corp.) and MS-Excel 2007 programs were used for statistical analyses and calculations. "nparLD" module was used for F2_LD_F1 design analysis at R program. Pamalgam filling, there were no significant differences of occlusal and gingival surface microleakage after MRI exposure. Occlusal and gingival surface microleakages were also similar with and without MRI in teeth with bonded amalgam filling. The results of this study suggest that MRI does not increase microleakage of amalgam restorations.

  18. Management of Class I and Class II Amalgam Restorations with Localized Defects: Five-Year Results

    Directory of Open Access Journals (Sweden)

    Javier Martin

    2013-01-01

    Full Text Available Replacement of dental restorations has been the traditional treatment for defective restorations. This five-year prospective clinical trial evaluated amalgam restorations with localized defects that were treated by means of repair or refurbishing. Fifty-two patients (50% female and 50% male, mean age 28.3±18.1 years, range 18–80 with 160 class I and class II defective restorations were included. The study focused on the application of two minimally invasive treatments for localized restoration defects and compared these with no treatment and total replacement as negative and positive controls, respectively. Restorations were assessed by two calibrated examiners according to modified U.S. Public Health Service criteria, including marginal adaptation, anatomic form, secondary caries, and roughness. At five years, recall was examined in 45 patients with 108 restorations (67.5%. The results suggest that repair treatment is as effective as total replacement of restorations with localized defects, reducing biological costs to the patient and providing new tools to the clinician. Refinishing restoration is a useful treatment for localized anatomic form defects.

  19. Anaerobic microflora under Class I and Class II composite and amalgam restorations.

    Science.gov (United States)

    Splieth, Christian; Bernhardt, Olaf; Heinrich, Annegret; Bernhardt, Hannelore; Meyer, Georg

    2003-01-01

    The microflora around and beneath restorations is an important factor of restoration failure. The aim of this pilot study was to determine and compare the microbial spectrum under composite and amalgam restorations with special attention to the anaerobic flora. Ten composite and five amalgam restorations scheduled for replacement were clinically evaluated for marginal gaps, fractures, and secondary caries. After their removal and caries diagnosis, a dentin sample just below the restoration was taken under sterile conditions, stored in a prereduced transport medium for anaerobic bacteria, and immediately transferred to a laboratory for microbial diagnosis. The clinical parameters showing mostly moderate marginal imperfections and the ratios of aerobic to anaerobic flora were comparable for composite and amalgam restorations (11.4%:88.6% and 15.4%:84.5%, respectively). The microbial variety under composite restorations was much greater compared to amalgam, and it was similar to that of infected root canals including anaerobic gram-negative rods, such as Fusobacterium species or Porphyromonas species. Beneath amalgam, the microbial flora was similar to the one found in carious dentin and plaque, with anaerobic and facultatively anaerobic gram-positive rods dominating. Quantitatively, there were up to eight times more microorganisms under composite restorations. The number of bacterial strains correlated with the caries activity and the filling material, the number of anaerobic rods correlated highly with caries activity and localization. In a linear regression, caries activity and the filling material had statistically significant influence on the bacterial load. Although caries activity and location had the greatest influence on the microbial flora under the restorations, the kind of restoration material seemed to have an additional effect on the composition of the microflora. This pilot study indicates that inadequate composite restorations may promote the growth of

  20. Repair strength of dental amalgams.

    Science.gov (United States)

    Shen, Chiayi; Speigel, Jason; Mjör, Ivar A

    2006-01-01

    This study tested the hypothesis that newly triturated amalgam condensed vertically on old amalgam was essential for establishing a bond between the new and old amalgams. Twelve rectangular bars were prepared with Dispersalloy and Tytin to establish their baseline flexure strength values. An additional 12 specimens were made and separated into 24 equal halves. All fracture surfaces were abraded with a flat end fissure bur. Twelve surfaces were paired with the original amalgam, and the remaining 12 surfaces were repaired with a different amalgam. At first, freshly triturated amalgam was condensed vertically on the floor of the specimen mold (Group A). The majority of specimens repaired with Group A failed to establish bond at the repair interface. All repair surfaces were abraded again and prepared by a second method. A metal spacer was used to create a four-wall cavity to facilitate vertical condensation directly on the repair surface (Group B). The specimens were stored in ambient air for seven days prior to flexure testing. The strength of specimens repaired with Group B ranged from 26% to 54% of the baseline specimens. ANOVA showed that amalgams repaired with a different amalgam yielded higher strength values than those repaired with the original amalgam, and the baseline specimens exhibited significantly higher strength values than all the repaired specimens.

  1. Increased mercury emissions from modern dental amalgams

    OpenAIRE

    Bengtsson, Ulf G.; Hylander, Lars D.

    2017-01-01

    All types of dental amalgams contain mercury, which partly is emitted as mercury vapor. All types of dental amalgams corrode after being placed in the oral cavity. Modern high copper amalgams exhibit two new traits of increased instability. Firstly, when subjected to wear/polishing, droplets rich in mercury are formed on the surface, showing that mercury is not being strongly bonded to the base or alloy metals. Secondly, high copper amalgams emit substantially larger amounts of mercury vapor ...

  2. Fracture Resistance of Pulpotomized Primary Molar Restored with Extensive Class II Amalgam Restorations

    Directory of Open Access Journals (Sweden)

    F. Mazhari

    2008-06-01

    Full Text Available Objective: The aim of the present study was to evaluate fracture resistance of pulpoto-mized primary molar teeth restored with extensive multisurface amalgam restorations.Materials and Methods: Eighty extracted carious human primary molar teeth were se-lected forpresent study. Teeth were divided in to eight groups of ten. Mesio- or disto-occlusal and Mesio-occluso-distal cavities with different cavity wall thickness (1.5 or 2.5mm were prepared in both first and second primary molar teeth. After restoring teeth with amalgam, all specimens were stored in distilled water at 37°C for 7 days. Then samples were thermocycled for 1000 cycles from 5°C to 55°C. The specimens then were subjected to a compressive load in a universal testing machine at a crosshead speed of 0.5 mm min-1. ANOVA and t-test were used for statistical analysis.Results: Mean fracture resistance of first and second molar teeth were 975.5 N (SD=368.8 and 1049.2 N (SD=540.1 respectively. In the first molar group, fracture resis-tance of two-surface cavities was significantly more than three-surface cavities (P<0.001, however this difference was not statistically significant in the second molar group. In both first and second molar group, fracture resistance incavities with 2.5 mm wall thickness, was significantly more than the group with 1.5 mm wall thickness.Conclusion: The mean fracture resistance in pulpotomized primary molar restored with amalgam restorations was higher than reported maximum bite force in primary teeth even in extensive multi-surface restorations. Therefore, the teeth with large proximal carious lesions in schoolchildren could be restored with amalgam.

  3. An In Vitro Evaluation of the Use of Resin Liners to Reduce Microleakage and Improve Bond Strength of Amalgam Restorations

    Science.gov (United States)

    1991-01-01

    study microleakage, dyes are the most frequently employed.7 Eosin, methylene blue, methyl violet, hematoxylin and mercuric chloride, Prontosil soluble...of amalgam, gutta percha, and zinc oxide- eugenol , found that the dyes possessed many of the advantages noted by other researchers. The ability of

  4. Comparison of microleakage in high copper spherical amalgam restorations using three different dentin bondin systems

    Directory of Open Access Journals (Sweden)

    Yasini E.

    2008-11-01

    Full Text Available "nBackground and Aim: Amalgam is one of the mostly used restorative materials, but has some disadvantages. Microleakage is one of the short comings of amalgam which may lead to sensitivity and recurrent caries. The aim of this study was to evaluate the effect of three dentin bonding systems on reduction of microleakage in amalgam restorations. "nMaterials and Methods: Class II amalgam restorations were made in 40 noncarious molar and premolar teeth. Then the specimens were divided into four equal groups. Scotch Bond Multi Purpose, Single bond, "niBond, were used as liner in groups one to three respectively and in group four no liner was used. The teeth were restored with high copper spherical amalgam. After thermocycling for 500 cycles at 50C and 550C, the specimens were immersed in basic fuchsin for 24 hours, bisectioned mesiodistally and evaluated under stereomicroscope at X25 for dye penetration. The data were analyzed by Kruskal-wallis and Scheffe. P<0.05 was considered as the level of significance. "nResults: The groups showed significant difference (p=0.003. The group four had significantly less microleakage than the first and second groups (p<0.05. The second and third groups showed significantly different microleakage (p=0.038. "nConclusion: Based on the results of this investigation applying dentin bonding agents has no effect on reducing microleakage in amalgam restorations, however more studies are recommended.

  5. Marginal behaviour of self-etch adhesive/composite and combined amalgam-composite restorations.

    Science.gov (United States)

    Kournetas, Nikos; Kakaboura, Afrodite; Giftopoulos, Dimitrios; Chakmachi, Magdad; Rahiotis, Christos; Geis-Gerstorfer, J

    2010-06-01

    The aim of this study was to compare the marginal and internal adaptation in self-etching adhesive (SEA)/composite restorations with combined amalgam-resin-based composite restorations in the proximal box with and without bonding agent beneath amalgam both before and after load-cycling. Class II restorations, were manufactured as following a) Bonding agent (Clearfil Liner Bond 2V, Kuraray) beneath amalgam (Tytin, SDS Kerr) and resin-based composite (Clearfil APX, Kuraray) with SEA, b) Amalgam without bonding agent and resin-based composite with SEA and c) Resin-based composite with SEA. Each group divided into two equal subgroups (n=8). Marginal and internal adaptation of first subgroup evaluated after 7-day water storage and of the second after load-cycling in chewing simulator for 1.2 x 10(6) cycles. Marginal and internal adaptation at cervical and amalgam-composite sites evaluated by videomicroscope and ranked as "excellent"/"non-excellent". Slices of restorations examined under optical microscope to determine the quality of bonding layer. Defects in cervical adaptation observed in the three restorative techniques examined prior loading. Amalgam-composite combination in proximal surface provided comparable marginal and internal adaptation results at cervical wall, to self-etching-composite combination. Portion (25-37.5%) of amalgam-resin-based composite interfaces in proximal box presented no perfect sealing. The application of bonding agent beneath amalgam resulted in relatively inferior cervical adaptation. Loading resulted in fewer excellent restorations in all three restorative techniques but not in a statistically significant level.

  6. Comprehension of amalgamation for future digital society

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byeong Uk

    2010-08-15

    This book deals with understanding of amalgamation for future digital society, which describes outline of amalgamation, ubiquitous environment, cognitive science I such as psychology and neurology, cognitive science II like philosophy, linguistics and anthropology, an automatic machine, evolution theory and amalgamation, brain science and consciousness, mind and software and creativity and art. Each chapter has introduction, composition, related science, function and models.

  7. Comprehension of amalgamation for future digital society

    International Nuclear Information System (INIS)

    Lee, Byeong Uk

    2010-08-01

    This book deals with understanding of amalgamation for future digital society, which describes outline of amalgamation, ubiquitous environment, cognitive science I such as psychology and neurology, cognitive science II like philosophy, linguistics and anthropology, an automatic machine, evolution theory and amalgamation, brain science and consciousness, mind and software and creativity and art. Each chapter has introduction, composition, related science, function and models.

  8. The microfloral analysis of secondary caries biofilm around Class I and Class II composite and amalgam fillings.

    Science.gov (United States)

    Mo, Si-su; Bao, Wei; Lai, Guang-yun; Wang, Jun; Li, Ming-yu

    2010-08-17

    Secondary caries is responsible for 60 percent of all replacement restorations in the typical dental practice. The diversity of the bacterial sources and the different types of filling materials could play a role in secondary caries. The aim of this study was to determine and compare the microbial spectrum of secondary caries biofilms around amalgam and composite resin restorations. Clinical samples were collected from freshly extracted teeth diagnosed with clinical secondary caries. Samples were categorized into four groups according to the types of restoration materials and the classification of the cavity. Biofilms were harvested from the tooth-restoration interface using a dental explorer and after dilution were incubated on special agars. The bacteria were identified using the biochemical appraisal system. Statistical calculations were carried out using SPSS11.5 software to analyze the prevalence of the bacteria involved in secondary caries. Samples from a total of four groups were collected: two groups were collected from amalgam restorations, each had 21 samples from both Class I and Class II caries; and the other two groups were from composite resin restorations, each had 13 samples from both class I and class II caries. Our results showed: (1) Anaerobic species were dominant in both restoration materials. (2) In terms of the types of individual bacteria, no significant differences were found among the four groups according to the geometric mean of the detected bacteria (P > 0.05). However, there were significant differences among the detected bacteria within each group (P composition of each bacterium had no statistical difference among the four groups (P > 0.05), but showed significant differences among the detected bacteria in each group (P 0.05), however, the detection rate of each bacterium within each group was statistically different among the detected bacteria (P composition of the microflora.

  9. Amalgam tattoo.

    Science.gov (United States)

    Tran, Hien T; Anandasabapathy, Niroshana; Soldano, Anthony C

    2008-05-15

    A 53-year-old woman with a history of melanoma status-post excision two years prior presented with a 4-month history of 4, dark-brown macules on the inferior surface of her tongue. A biopsy specimen showed a squamous mucosa with chronic submucosal inflammation and brown pigment. The clinical and histopathologic findings were consistent with a diagnosis of amalgam tattoo. Amalgam tattoos are common, oral pigmented lesions that clinically present as isolated, blue, grey, or black macules on the gingivae, the buccal and alveolar mucosae, the palate, and/or the tongue. They are due to deposition of a mixture of silver, tin, mercury, copper, and zinc, which are components of an amalgam filling, into the oral soft tissues. Amalgam tattoos can either be treated surgically or with a Q-switched ruby laser. In the case of our patient with the history of melanoma, her oral lesions proved not to be the more dire diagnosis of malignant melanoma.

  10. Amalgamation based optical and colorimetric sensing of mercury(II) ions with silver graphene oxide nanocomposite materials

    International Nuclear Information System (INIS)

    Kamali, Khosro Zangeneh; Pandikumar, Alagarsamy; Jayabal, Subramaniam; Huang, Nay Ming; Ramaraj, Ramasamy; Lim, Hong Ngee; Ong, Boon Hoong; Bien, Chia Sheng Daniel; Kee, Yeh Yee

    2016-01-01

    The article describes a facile method for the preparation of a conjugate composed of silver nanoparticles and graphene oxide (Ag GO) via chemical reduction of silver precursors in the presence of graphene oxide (GO) while sonicating the solution. The Ag GO was characterized by X-ray photoelectron spectroscopy, X-ray powder diffraction, and energy-dispersive X-ray spectroscopy. The nanocomposite undergoes a color change from yellow to colorless in presence of Hg(II), and this effect is based on the disappearance of the localized surface plasmon resonance absorption of the AgNPs due to the formation of silver-mercury amalgam. The presence of GO, on the other hand, prevents the agglomeration of the AgNPs and enhances the stability of the nanocomposite material in solution. Hence, the probe represents a viable optical probe for the determination of mercury(II) ions in that it can be used to visually detect Hg(II) concentrations as low as 100 μM. The instrumental LOD is 338 nM. (author)

  11. About Dental Amalgam Fillings

    Science.gov (United States)

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

  12. Phase down of amalgam

    Science.gov (United States)

    AL-Rabab’ah, Mohammad A.; Bustani, Mohammad A.; Khraisat, Ameen S.; Sawair, Faleh A.

    2016-01-01

    Objectives To assess the knowledge of Jordanian dentists toward phase down of dental amalgam as recommended by the Minamata Convention, and their training and competency in placing posterior composites. Methods This study was conducted through structured questionnaire interviews with randomly selected cohort of dentists in Jordan between March 2015 and June 2015. Out of 230 dentists who were invited, 196 (85.2%) agreed to participate. Dentists were asked if they know about the Minamata Convention. They were also asked about their training in placement of posterior composite. Results Out of the 196 interviewed, only 13.8% know about Minamata Convention and 17% had an undergraduate training in favor of placing composites in posterior teeth. Approximately 50% of those dentists were not trained in using rubber dam when placing posterior composites, while only 38.3% had training in sectional matrix placement. Undergraduate training did not influence (p=0.00) the dentists’ decision to remove old amalgam based on patient’s demands. Only 28.1% were of the opinion of discontinuing the use of amalgam due to its alleged health and environmental hazards. There was no general agreement on the type of composite, liner, and bonding strategy when placing posterior composites. Conclusion Dentists are not well informed on the Minamata Convention and the phase down of amalgam. Training in posterior composite placement should be given more room in undergraduate curriculum and continuous dental education. PMID:27874155

  13. The Microfloral Analysis of Secondary Caries Biofilm around Class I and Class II Composite and Amalgam Fillings

    Directory of Open Access Journals (Sweden)

    Mo Si-su

    2010-08-01

    Full Text Available Abstract Background Secondary caries is responsible for 60 percent of all replacement restorations in the typical dental practice. The diversity of the bacterial sources and the different types of filling materials could play a role in secondary caries. The aim of this study was to determine and compare the microbial spectrum of secondary caries biofilms around amalgam and composite resin restorations. Methods Clinical samples were collected from freshly extracted teeth diagnosed with clinical secondary caries. Samples were categorized into four groups according to the types of restoration materials and the classification of the cavity. Biofilms were harvested from the tooth-restoration interface using a dental explorer and after dilution were incubated on special agars. The bacteria were identified using the biochemical appraisal system. Statistical calculations were carried out using SPSS11.5 software to analyze the prevalence of the bacteria involved in secondary caries. Results Samples from a total of four groups were collected: two groups were collected from amalgam restorations, each had 21 samples from both Class I and Class II caries; and the other two groups were from composite resin restorations, each had 13 samples from both class I and class II caries. Our results showed: (1 Anaerobic species were dominant in both restoration materials. (2 In terms of the types of individual bacteria, no significant differences were found among the four groups according to the geometric mean of the detected bacteria (P > 0.05. However, there were significant differences among the detected bacteria within each group (P 0.05, but showed significant differences among the detected bacteria in each group (P 0.05, however, the detection rate of each bacterium within each group was statistically different among the detected bacteria (P Conclusions The proportion of obligatory anaerobic species was much greater than the facultative anaerobic species in the

  14. Dentalni amalgam

    OpenAIRE

    Galić, Nada; Šutalo, Jozo; Prpić-Mehičić, Goranka; Anić, Ivica

    1994-01-01

    Dentalni amalgam je bio materijal izbora za ispune na stražnjim zubima tijekom proteklih 150 godina. U radu je prikazan p o vijesni razvoj amalgama, njegov obvezni sastav, te podjela dentalnih amalgama prema količinskom udjelu bakra i prema obliku čestica. Navedena su svojstva amalgama s posebnim osvrtom na njegovu toksičnost. Poznato je da se posljednjih godina pojačao napad na amalgam i u znanstvenoj i u popularnoj literaturi, a u svezi s njegovim navodnim patološkim djelovanjem ...

  15. Cycloaddition Reaction of Hydrogen-Bonded Zn(II)

    Indian Academy of Sciences (India)

    J. Chem. Sci. Vol. 129, No. 2, February 2017, pp. 239–247. c Indian Academy of Sciences. DOI 10.1007/s12039-016-1218-6. REGULAR ARTICLE. Solid-state Photochemical [2+2] Cycloaddition Reaction of. Hydrogen-Bonded Zn(II) Metal Complex Containing Several Parallel. C=C Bonds. ABDUL MALIK P PEEDIKAKKAL.

  16. Are there acceptable alternatives to amalgam?

    Science.gov (United States)

    Mackert, J Rodway; Wahl, Michael J

    2004-07-01

    Amalgam has been the material of choice for restoring posterior teeth for more than 100 years. The past 25 years have witnessed significant advances in restorative materials themselves and in the bonding systems for retaining a restoration in the prepared tooth. As a result, there has been a shift toward resin composite materials during this same period because of concerns about the esthetics and biocompatibility of dental amalgam. In addition, other materials such as glass ionomer cements, ceramic inlays and onlays, and gold alloys have been used as alternatives to amalgam. This article will review recent studies on the longevity and biocompatibility of these alternatives to dental amalgam.

  17. Novel Amalgams for In-Space Parts Fabrication

    Science.gov (United States)

    Cochran, Calvin; VanHoose, James R.; Grugel, Richard N.

    2012-01-01

    Sound amalgams can be fabricated by substituting Ga-In liquid for mercury; Cu-coated steel fibers bond well with the amalgam components. Inclusion of steel fibers significantly improved mechanical properties. An application scenario utilizing amalgams for in-space parts fabrication and repair was suggested. Procedure and materials need to be optimized

  18. Kondensasi Pada Dental Amalgam

    OpenAIRE

    Batubara, Runi Syahriani

    2011-01-01

    Amalgam merupakan campuran dari dua atau beberapa logam (alloy) yang salah satunya adalah merkuri. Kata amalgam juga didefenisikan untuk menggambarkan kombinasi atau campuran dari beberapa bahan seperti merkuri, perak, timah, tembaga, dan lainnya. Dental amalgam sendiri adalah kombinasi alloy dengan merkuri melalui suatu proses yang disebut amalgamasi. Pemanipulasian amalgam meliputi triturasi, kondensasi, carving, dan polishing. Kondensasi merupakan penekanan amalgam setelah triturasi p...

  19. Irregular amalgams

    Directory of Open Access Journals (Sweden)

    James Stewart

    1986-01-01

    Full Text Available The amalgam of Lp and ℓq consists of those functions for which the sequence of Lp-norms over the intervals [n,n+1 is in ℓq. These spaces (Lp,ℓq have been studied in several recent papers. Here we replace the intervals [n,n+1 by a cover α={In;n∈Z} of the real line consisting of disjoint half-open intervals In each of the form [a,b, and investigate which properties of (Lp,ℓq carry over to these irregular amalgams (Lp,ℓqα. In particular, we study how (Lp,ℓqα varies as p, q, and α vary and determine conditions under which translation is continuous.

  20. Amalgam Electrode-Based Electrochemical Detector for On-Site Direct Determination of Cadmium(II and Lead(II from Soils

    Directory of Open Access Journals (Sweden)

    Lukas Nejdl

    2017-08-01

    Full Text Available Toxic metal contamination of the environment is a global issue. In this paper, we present a low-cost and rapid production of amalgam electrodes used for determination of Cd(II and Pb(II in environmental samples (soils and wastewaters by on-site analysis using difference pulse voltammetry. Changes in the electrochemical signals were recorded with a miniaturized potentiostat (width: 80 mm, depth: 54 mm, height: 23 mm and a portable computer. The limit of detection (LOD was calculated for the geometric surface of the working electrode 15 mm2 that can be varied as required for analysis. The LODs were 80 ng·mL−1 for Cd(II and 50 ng·mL−1 for Pb(II, relative standard deviation, RSD ≤ 8% (n = 3. The area of interest (Dolni Rozinka, Czech Republic was selected because there is a deposit of uranium ore and extreme anthropogenic activity. Environmental samples were taken directly on-site and immediately analysed. Duration of a single analysis was approximately two minutes. The average concentrations of Cd(II and Pb(II in this area were below the global average. The obtained values were verified (correlated by standard electrochemical methods based on hanging drop electrodes and were in good agreement. The advantages of this method are its cost and time effectivity (approximately two minutes per one sample with direct analysis of turbid samples (soil leach in a 2 M HNO3 environment. This type of sample cannot be analyzed using the classical analytical methods without pretreatment.

  1. Increased mercury emissions from modern dental amalgams.

    Science.gov (United States)

    Bengtsson, Ulf G; Hylander, Lars D

    2017-04-01

    All types of dental amalgams contain mercury, which partly is emitted as mercury vapor. All types of dental amalgams corrode after being placed in the oral cavity. Modern high copper amalgams exhibit two new traits of increased instability. Firstly, when subjected to wear/polishing, droplets rich in mercury are formed on the surface, showing that mercury is not being strongly bonded to the base or alloy metals. Secondly, high copper amalgams emit substantially larger amounts of mercury vapor than the low copper amalgams used before the 1970s. High copper amalgams has been developed with focus on mechanical strength and corrosion resistance, but has been sub-optimized in other aspects, resulting in increased instability and higher emission of mercury vapor. This has not been presented to policy makers and scientists. Both low and high copper amalgams undergo a transformation process for several years after placement, resulting in a substantial reduction in mercury content, but there exist no limit for maximum allowed emission of mercury from dental amalgams. These modern high copper amalgams are nowadays totally dominating the European, US and other markets, resulting in significant emissions of mercury, not considered when judging their suitability for dental restoration.

  2. Amalgams for fluorescent lamps. Pt. II. The systems Bi-Pb-Hg and Bi-Pb-Au-Hg

    Energy Technology Data Exchange (ETDEWEB)

    Lankhorst, M.H.R.; Keur, W.; Hal, H.A.M. van [Philips Research Labs., Eindhoven (Netherlands)

    2000-09-14

    In nowadays compact fluorescent lamps, having coolest spot temperatures in the range 60-130 C, amalgams based on the eutectic Bi-In and Bi-Pb-Sn alloys are used to control the mercury vapour pressure inside the lamp. The consequence of the trend towards smaller and more attractive compact fluorescent lamps is that the amalgam temperature increases. In this paper the materials and thermodynamic properties of the amalgams Bi-Pb-Hg and Bi-Pb-Au-Hg are described. The mercury vapour pressure measurements show that these amalgams can be used for controlling the optimal mercury vapour pressure inside fluorescent lamps at temperatures in the range 60-150 C. In the ternary Bi-Pb-Au system the new ternary compound BiPb{sub 3}Au has been found for which the crystal structure and melting point have been determined. The results of XRD, EPMA, DTA and mercury vapour pressure measurements are combined to formulate a thermodynamic model for the mercury activity in both liquid and solid Bi-Pb-Hg and Bi-Pb-Au-Hg. (orig.)

  3. Class I and Class II silver amalgam and resin composite posterior restorations: teaching approaches in Canadian faculties of dentistry.

    Science.gov (United States)

    McComb, Dorothy

    2005-06-01

    A 10-question survey was mailed to the 10 Canadian faculties of dentistry to determine current approaches to teaching undergraduates about silver amalgam and resin composite for posterior restorations in adults and children. Responses were received from all 10 pedodontic programs and from 8 of the 10 operative and restorative programs. The use of silver amalgam and posterior composite for restorations of primary and permanent teeth is covered in the curricula of all dental schools, but the relative emphasis on the 2 materials varies. In the operative and restorative programs, curriculum time devoted to silver amalgam is either greater than or equal to that devoted to posterior composite. Five of the 8 schools reported greater educational emphasis on silver amalgam for the permanent dentition; however, course directors noted that the preference among patients seen in clinics is tending toward composite restorations. Curricula appear designed to educate students about the optimal use of both materials. Requirements for performance of restorations during training generally do not specify the type of material; these requirements range from 60 restorations to 250 surfaces. Five of the 8 schools conduct clinical competency tests with both materials. The responses from the pedodontic programs were more diverse. The proportion of curriculum time devoted to each type of material in these programs ranged from less than 25% to more than 75%. Five schools reported more emphasis on silver amalgam, 3 schools reported equal emphasis, and 2 schools reported more emphasis on posterior composite. No clinical requirements were specified in any of the undergraduate pedodontic programs. Within some of the faculties, there were differences between the operative and restorative program and the pedodontic program with respect to emphasis on different materials for the posterior dentition.

  4. [Illnesses caused by amalgam?].

    Science.gov (United States)

    Staehle, H J

    1998-02-15

    As side effects of dental amalgam have been mentioned allergy, oral lichen, electro-galvanism, amalgam tattoos of gingiva or oral mucosa, and undesirable esthetics. Patients with amalgam restorations show increased mercury levels in different body fluids compared to amalgam-free controls. An intoxication due to dental amalgam fillings, however, is not to be expected-despite equivocal statements in the literature. In contrast, recent studies revealed that dental amalgam contributes to mercury exposure less than assumed few years ago. Therefore, amalgam will stay an option as a restorative material in future. The removal of intact amalgam fillings in the intention of "detoxification" is not science-based. Successful caries prevention (e.g. due to the widespread use of fluoride) and the further development of esthetic restorative materials based on composite resins will limit the utilisation of amalgam. Thus, alternative materials have not been shown to have a lower rate of side effects (e.g. allergy) compared to amalgam.

  5. Has resin-based composite replaced amalgam?

    Science.gov (United States)

    Christensen, Gordon J; Child, Paul L

    2010-02-01

    The major health organizations in the world continue to accept amalgam use, but the "amalgam war" of the 1800s is still going on. The end is not in sight. There is little disagreement that amalgam serves well and, although controversial, it appears to have minimal to no health hazards. There is a wide variation in the relative amount of amalgam placed in developed countries, and many dentists in North America do not use it. However, amalgam is still being used at least some of the time by the majority of practitioners in North America, and most of those practitioners also place resin-based composite in Class II locations. The evolution from amalgam to tooth-colored restorations has been a slow and tumultuous journey. The acceptability of resin-based composite in Class II locations continues to be a question for some dentists, while others have concluded that amalgam is "dead." It would be highly desirable if some of dentists using the alleged poisonous properties of amalgam as a "practice building" ploy would find more legitimate methods to increase their practice activity.

  6. Electrospun nanofibers decorated with bio-sonochemically synthesized gold nanoparticles as an ultrasensitive probe in amalgam-based mercury (II) detection system.

    Science.gov (United States)

    Parsaee, Zohreh

    2018-06-01

    In this study, bio-ultrasound-assisted synthesized gold nanoparticles using Gracilaria canaliculata algae have been immobilized on a polymeric support and used as a glassy probe chemosensor for detection and rapid removal of Hg 2+ ions. The function of the suggested chemosensor has been explained based on gold-amalgam formation and its catalytic role on the reaction of sodium borohydride and rhodamine B (RhB) with fluorescent and colorimetric sensing function. The catalyzed reduction of RhB by the gold amalgam led to a distinguished color change from red and yellow florescence to colorless by converting the amount of Hg 2+ deposited on Au-NPs. The detection limit of the colorimetric and fluorescence assays for Hg 2+ was 2.21 nM and 1.10 nM respectively. By exposing the mentioned colorless solution to air for at least 2 h, unexpectedly it was observed that the color and fluorescence of RhB were restored. Have the benefit of the above phenomenon a recyclable and portable glass-based sensor has been provided by immobilizing the Au-NPs and RB on the glass slide using electrospinning. Moreover, the introduced combinatorial membrane has facilitated the detection and removal of Hg 2+ ions in various Hg (II)-contaminated real water samples with efficiency of up to 99%. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. DNA-based electrochemical determination of mercury(II) by exploiting the catalytic formation of gold amalgam and of silver nanoparticles

    International Nuclear Information System (INIS)

    Tang, Juan; Huang, Yapei; Zhang, Cengceng; Liu, Huiqiong; Tang, Dianping

    2016-01-01

    The authors describe an electrochemical assay for mercury ion (Hg 2+ ) by using a glassy carbon electrode (GCE) to which a 25-base thymine oligomer was covalently immobilized. On addition of Hg(II) ion, it is captured via T-Hg(II)-T coordination. The T-Hg(II)-T complex catalyzes the reduction of auric acid by hydroxylamine and this leads to the formation of gold amalgam (AuHg). The electrode is then placed in an ammoniacal solution of silver nitrate. On applying a deposition potential of −0.12 V for 60 s, silver nanoparticles are deposited on the surface that serve as signal reporters to indicate the concentration of Hg(II) in the sample solution. The electrode, if operated at 50 mV (vs. Ag/AgCl) enables Hg(II) to be detected in the 0.005 to 80 nM concentration range, with a detection limit as low as 2 pM. The method was successfully applied to the determination of Hg(II) in spiked river water. (author)

  8. Fracture strength of Class 2 amalgams with various cavity-lining materials.

    Science.gov (United States)

    Palmer, A E; Davis, R D; Murchison, D F; Cohen, R B

    1999-01-01

    This in vitro study compared the fracture resistance of class 2 amalgam restorations placed over seven materials: three resin-modified glass-ionomer cements (Fuji II LC, Vitrebond, and Vitremer), one polyacid-modified composite resin (VariGlass VLC), two conventional glass-ionomer cements (Ketac-Bond and GlasIonomer Cement), and one calcium-hydroxide material (Dycal). Eighty maxillary molars with flattened occlusal surfaces were divided into 14 experimental groups and two control (no liner) groups. One standardized class 2 amalgam cavity preparation was completed per tooth. Lining materials standardized at a thickness of 0.5 mm were placed in the approximal box portion of 10 test specimens per experimental group. Spherical amalgam was hand condensed into each cavity preparation. At 1 hour and again at 7 days, five samples from each group were fractured in compression using an Instron Universal Testing Machine. The force was directed at 10 degrees to the long axis of the tooth, 2.0 mm inside the approximal portion of the restoration. Results were analyzed using a two-way ANOVA for time and material. No statistically significant differences were found among the materials and controls at either time interval tested (P > 0.05). A statistically significant difference was found (P amalgam restorations was not affected by the presence of a material 0.5 mm thick placed in the approximal box when 3 mm of bulk of amalgam remained over it.

  9. Biocompatibility of dental amalgams.

    Science.gov (United States)

    Uçar, Yurdanur; Brantley, William A

    2011-01-01

    Objective. The purpose of this review paper is to review the literature regarding the toxicology of mercury from dental amalgam and evaluate current statements on dental amalgam. Materials and Methods. Two key-words "dental amalgam" and "toxicity" were used to search publications on dental amalgam biocompatibility published in peer-reviewed journals written in English. Manual search was also conducted. The most recent declarations and statements were evaluated using information available on the internet. Case reports were excluded from the study. Results. The literature show that mercury released from dental amalgam restorations does not contribute to systemic disease or systemic toxicological effects. No significant effects on the immune system have been demonstrated with the amounts of mercury released from dental amalgam restorations. Only very rarely have there been reported allergic reactions to mercury from amalgam restorations. No evidence supports a relationship between mercury released from dental amalgam and neurological diseases. Almost all of the declarations accessed by the internet stated by official organizations concluded that current data are not sufficient to relate various complaints and mercury release from dental amalgam. Conclusions. Available scientific data do not justify the discontinuation of amalgam use from dental practice or replacement with alternative restorative dental materials.

  10. A technical report on repair of amalgam-dentin complex.

    Science.gov (United States)

    Ozcan, M; Salihoğlu-Yener, E

    2011-01-01

    This clinical report describes a repair protocol for cusp fracture of a failed amalgam-dentin complex. A maxillary right first premolar with an amalgam restoration presented a buccal cusp fracture. Chairside repair has been undertaken by conditioning the existing amalgam restoration with silica coating (30 μm CoJet®-Sand), phosphoric acid etching the beveled enamel surface, priming dentin, and application of a bonding agent on both enamel and dentin. Thereafter, the amalgam was silanized (ESPE®-Sil), and opaque resin was applied and polymerized to mask the amalgam. The fractured buccal cusp was modeled using resin composite (Clearfil Photo Posterior) and photo-polymerized. Finally, the amalgam was refinished and refurbished and the composite was finished and polished.

  11. Biocompatibility of Dental Amalgams

    Directory of Open Access Journals (Sweden)

    Yurdanur Uçar

    2011-01-01

    Full Text Available Objective. The purpose of this review paper is to review the literature regarding the toxicology of mercury from dental amalgam and evaluate current statements on dental amalgam. Materials and Methods. Two key-words “dental amalgam” and “toxicity” were used to search publications on dental amalgam biocompatibility published in peer-reviewed journals written in English. Manual search was also conducted. The most recent declarations and statements were evaluated using information available on the internet. Case reports were excluded from the study. Results. The literature show that mercury released from dental amalgam restorations does not contribute to systemic disease or systemic toxicological effects. No significant effects on the immune system have been demonstrated with the amounts of mercury released from dental amalgam restorations. Only very rarely have there been reported allergic reactions to mercury from amalgam restorations. No evidence supports a relationship between mercury released from dental amalgam and neurological diseases. Almost all of the declarations accessed by the internet stated by official organizations concluded that current data are not sufficient to relate various complaints and mercury release from dental amalgam. Conclusions. Available scientific data do not justify the discontinuation of amalgam use from dental practice or replacement with alternative restorative dental materials.

  12. Repair of amalgam restorations with conventional and bonded amalgam: an in vitro study = Reparo de restaurações de amálgama com amálgama adesivo e convencional: estudo in vitro

    OpenAIRE

    Popoff, Daniela Araújo Veloso

    2010-01-01

    Objetivo: Avaliar a microinfiltração em restaurações de amálgama com reparo em amálgama ou amálgama adesivo. Métodos: Trinta pré-molares humanos extraídos foram restaurados com amálgama. Simu- lou-se um defeito nas restaurações reparado com: G1 - amálgama (n=15) (Permite C-SDI); G2 - amálgama adesivo (n=15) (Caulk 34% Condicionador dentário Gel Dentsply + Prime & Bond 2. 1 Dentsply + Permite C-SDI). Os dentes foram imersos em solução de nitrato de prata a 50%, termociclados e então, seciona...

  13. Composite veneering of complex amalgam restorations.

    Science.gov (United States)

    Demarco, Flávio Fernando; Zanchi, César Henrique; Bueno, Márcia; Piva, Evandro

    2007-01-01

    In large posterior cavities, indirect restorations could provide improved performance when compared to direct restorations, but with higher cost and removal of sound tooth structure. Improved mechanical properties have resulted in good clinical performance for amalgam in large cavities but without an esthetic appearance. Resin composites have become popular for posterior restorations, mainly because of good esthetic results. A restorative technique is presented that combines the esthetic properties of directly bonded resin composite and the wide range of indications for amalgam in stress-bearing areas.

  14. Comparison of the composition of Cinalux amalgam with ADA standard

    Directory of Open Access Journals (Sweden)

    Moosavi Nasab M

    2002-07-01

    Full Text Available Dental amalgam is one of the oldest restorative materials, used in dentistry, which has undergone a lot of quality changes since its advent. Copper is one of the major elements in dental amalgam. Dental amalgam is classified as low and high cooper group based on the percentage of this element. Cinaluy is an Iranian product, a product of Shahid Faghihi's factory and its particles are spherical with high copper and it does not contain any zinc and gama II phase. The goal of this study was to identify the type and percentage of its ingredients and to analyze this dental amalgam by muclear reactor. The products of the factory, at two different times, were compared with each other and also with the percentages presented by the factory, regarding their ingredients. They were also compared with two standardized amalgams called: Sybralloy and Tytin. Three typical Cinalux amalgam capsules, produced on different dates, were selected. The contents of capsules were enveloped in plastic bags and then sealed and placed in a miniature reactor to undergo nuclear radiation for 10 days. After this period, the elements in amalgam became activated and converted into radioisotopes of the same elements, and began to radiate. Then gama spectrometer system accumulated these radiations and transferred them to Span software. This software, aided by reference standards, shows the intensity and the wave length of the received radiation, and consequently identifies the type and percentage of the elements in amalgam. The results demonstrated that the Cinalux amalgam samples, regarding the type and percentage of their elements, were identical and also met the factory standards. The differences were not significant. There was also no significant difference between Cinalux amalgam and the standardized amalgam Sybralloy, regarding the percentage of their elements, but comparing this amalgam with the standardized amalgam Tytin, a significant difference was not observed.

  15. Repair of amalgam restorations with conventional and bonded amalgam: an in vitro study = Reparo de restaurações de amálgama com amálgama adesivo e convencional: estudo in vitro

    Directory of Open Access Journals (Sweden)

    Popoff, Daniela Araújo Veloso

    2010-01-01

    Full Text Available Objetivo: Avaliar a microinfiltração em restaurações de amálgama com reparo em amálgama ou amálgama adesivo. Métodos: Trinta pré-molares humanos extraídos foram restaurados com amálgama. Simu- lou-se um defeito nas restaurações reparado com: G1 - amálgama (n=15 (Permite C-SDI; G2 - amálgama adesivo (n=15 (Caulk 34% Condicionador dentário Gel – Dentsply + Prime & Bond 2. 1 – Dentsply + Permite C-SDI. Os dentes foram imersos em solução de nitrato de prata a 50%, termociclados e então, secionados longitudinalmente através da restauração e examinados por três examinadores usando um estereomicroscópio. A microinfiltração foi avaliada pela penetração de corante com uma escala de 0 a 4. Diferenças entre os grupos foram verificadas pelos testes Kruskal Wallis e Dunn. Resultados: Na interface reparo/dente, a técnica de reparo com amálgama adesivo foi signi- ficativamente mais efetiva, apresentando menor microinfiltração (escore 0=53. 3%, P= 0,0012. Já na interface reparo/restauração, houve menor microinfiltração nas restaurações reparadas com amálgama convencional (escore 0=86. 7%, P<0,001. Conclusão: Nenhum dos materiais eliminou a microinfiltração completamente. O uso de sistemas adesivos tem efeito significativo no selamento da interface reparo/dente, entretanto para interface reparo/restauração, ele pode aumentar a microinfiltração

  16. 75 FR 33169 - Dental Devices: Classification of Dental Amalgam, Reclassification of Dental Mercury, Designation...

    Science.gov (United States)

    2010-06-11

    ... Dental Amalgam, Reclassification of Dental Mercury, Designation of Special Controls for Dental Amalgam, Mercury, and Amalgam Alloy; Technical Amendment AGENCY: Food and Drug Administration, HHS. ACTION: Final... device, reclassified dental mercury from class I to class II, and designated special controls for dental...

  17. Dental devices: classification of dental amalgam, reclassification of dental mercury, designation of special controls for dental amalgam, mercury, and amalgam alloy; technical amendment. Final rule; technical amendment.

    Science.gov (United States)

    2010-06-11

    The Food and Drug Administration (FDA) published a final rule in the Federal Register of August 4, 2009 (74 FR 38686) which classified dental amalgam as a class II device, reclassified dental mercury from class I to class II, and designated special controls for dental amalgam, mercury, and amalgam alloy. The effective date of the rule was November 2, 2009. The final rule was published with an inadvertent error in the codified section. This document corrects that error. This action is being taken to ensure the accuracy of the agency's regulations.

  18. In vitro testing of dental materials by means of macrophage cultures: II. Effects of particulate dental amalgams and their constituent phases on cultured macrophages.

    Science.gov (United States)

    Syrjänen, S; Hensten-Pettersen, A; Nilner, K

    1986-10-01

    It is known that macrophages play an important role in the removal of foreign particulate matter from tissue. When powdered dental amalgam is introduced into the soft tissues an amalgam tattoo is formed due to the intracellular degradation of amalgam by macrophages and their polykaryons. It was therefore feasible to study the effects of particulate amalgams as well as their individual phases on macrophages in vitro. The parameters compared were rate of the phagocytosis, changes of cellular morphology, and release of lactate dehydrogenase (LDH) to demonstrate plasma membrane permeability. It was shown that all the alloys except the Sn8Hg particles (gamma 2-phase) and gamma 2-containing Revalloy were effectively phagocytized by macrophages, and the alterations in cellular morphology were slight during the first day. Prominent cellular damage was seen in cultures treated with particulate Ag2Hg3 (gamma 1-phase) and Revalloy for 1 week. A slight increase in LDH activity in the medium was seen one hour after the alloy treatment. The LDH activities due to the amalgam treatment increased in the order Dispersalloy less than Revalloy less than Sybraloy. Intraperitoneal phagocytosis did not cause any morphological changes in macrophages, but the per cent of phagocytosis was diminished.

  19. Dental amalgam: An update

    Science.gov (United States)

    Bharti, Ramesh; Wadhwani, Kulvinder Kaur; Tikku, Aseem Prakash; Chandra, Anil

    2010-01-01

    Dental amalgam has served as an excellent and versatile restorative material for many years, despite periods of controversy. The authors review its history, summarize the evidence with regard to its performance and offer predictions for the future of this material. The PubMed database was used initially; the reference list for dental amalgam featured 8641 articles and 13 publications dealing with recent advances in dental amalgam. A forward search was undertaken on selected articles and using some author names. For the present, amalgam should remain the material of choice for economic direct restoration of posterior teeth. When esthetic concerns are paramount, tooth-colored materials, placed meticulously, can provide an acceptable alternative. All alternative restorative materials and procedures, however, have certain limitations. PMID:21217947

  20. Estudo comparativo da resistência à fratura de pré-molares superiores íntegros e restaurados com amálgama aderido Comparative study of the fracture resistance of sound upper premolars and upper premolars restored with bonded amalgam

    Directory of Open Access Journals (Sweden)

    André Marcelo Peruchi Minto

    2002-06-01

    Full Text Available No presente estudo avaliou-se, in vitro, a resistência à fratura de pré-molares superiores preparados com cavidades de classe II compostas (conservadoras e extensas restauradas com amálgama aderido a dois tipos diferentes de sistemas adesivos. Setenta dentes foram divididos em 4 grupos: grupo 1 ou controle com 10 dentes íntegros; grupo 2 com 20 dentes, sendo 10 cavidades conservadoras e 10 extensas restauradas com amálgama sem qualquer tipo de forramento. O grupo 3 e o grupo 4 foram compostos da mesma forma que o grupo 2, sendo que o primeiro recebeu cimento de ionômero de vidro (Vitrebond - 3M e o segundo, adesivo dental (Scotchbond Multi-Purpose Plus - 3M, antes de serem restaurados. Os dentes haviam sido incluídos anteriormente em cilindros de PVC e fixados com resina acrílica. Após serem restaurados e termociclados, foram submetidos à fratura por força de compressão em uma máquina universal de testes EMIC-MEM 2000. Após análise de variância e aplicação do teste complementar de Tukey, concluiu-se que os sistemas adesivos utilizados condicionaram o aumento da resistência à fratura da estrutura dental nas cavidades convencionais, sendo os dentes com cavidades conservadoras mais resistentes em qualquer condição experimental.The purpose of this in vitro study was to determine the fracture resistance of upper premolars which had received class II preparations (conservative and extensive and were restored with bonded amalgam, with two different adhesive systems. Seventy teeth were divided in four groups: group 1 (control, with ten sound teeth; group 2, with twenty prepared teeth (10 teeth received conservative cavities and 10, extensive cavities restored with amalgam without any kind of liner; groups 3 and 4, similar to group 2, though with linings of glass ionomer cement (Vitrebond - 3M (group 3 and dental adhesive (Scotchbond Multi-Purpose Plus - 3M (group 4. The teeth were previously fixed in PVC cylinders with acrylic

  1. 12-year survival of composite vs. amalgam restorations.

    Science.gov (United States)

    Opdam, N J M; Bronkhorst, E M; Loomans, B A C; Huysmans, M C D N J M

    2010-10-01

    Information about the long-term clinical survival of large amalgam and composite restorations is still lacking. This retrospective study compares the longevity of three- and four-/five-surface amalgam and composite restorations relative to patients' caries risk. Patient records from a general practice were used for data collection. We evaluated 1949 large class II restorations (1202 amalgam/747 composite). Dates of placement, replacement, and failure were recorded, and caries risk of patients was assessed. Survival was calculated from Kaplan-Meier statistics. After 12 years, 293 amalgam and 114 composite restorations had failed. Large composite restorations showed a higher survival in the combined population and in the low-risk group. For three-surface restorations in high-risk patients, amalgam showed better survival.

  2. Bond forms of methane in porous system of coal II

    Czech Academy of Sciences Publication Activity Database

    Weishauptová, Zuzana; Medek, Jiří; Kovář, Lukáš

    2004-01-01

    Roč. 83, č. 13 (2004), s. 1759-1764 ISSN 0016-2361 R&D Projects: GA AV ČR IAA2046101; GA AV ČR KSK2067107 Institutional research plan: CEZ:AV0Z3046908 Keywords : coal-bed methane * absorption * fifth bond form Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.368, year: 2004

  3. Overhanging amalgam restorations by undergraduate students.

    Science.gov (United States)

    Quadir, Fauzia; Ali Abidi, S Yawar; Ahmed, Shahbaz

    2014-07-01

    To determine the frequency of overhanging margins in amalgam restorations done by undergraduate students at Fatima Jinnah Dental College Hospital, Karachi. Observational study. Department of Operative Dentistry, Fatima Jinnah Dental Hospital, Karachi, from January to June 2009. Patients aged 20 - 45 years attending the Department of Operative Dentistry requiring class-II restorations were included in the study. Whereas, third molars, overlapped proximal surfaces, teeth adjacent to edentulous spaces and pregnant females were excluded. One hundred and fifty patients were selected randomly aged between 20 - 45 years requiring class-II restorations. Posterior Bitewing radiographs were taken and 1600 surfaces were examined. Restorations were done by undergraduate students at Fatima Jinnah Dental College Hospital, Karachi. Chi-square test was utilized to analyze the relationship between location and surface of overhang. Overhanging amalgam restorations were common in the restorations done by undergraduate students (58%). The occurrence of overhangs was more frequent on the distal surfaces (56%) Although the association of amalgam overhangs with the surfaces of the teeth was significant (p p amalgam restorations done by undergraduate students.

  4. Dentin Pre-Treatment to Suppress Microleakage of Amalgam Restorations

    Directory of Open Access Journals (Sweden)

    Yosi Kusuma Eriwati Arianto

    2015-10-01

    Full Text Available Diminished microleakage of amalgam-to-dentin preparations would benefit large populations in public health facilities. Prior studies demonstrated less microleakage for bonded amalgams than similarly bonded advanced composites among 30 different composite/bonding agent/storage conditions, Haller et al. showed that a combination of formaldehyde pre-treatment and glutaraldehyde-containing Syntac adhesive minimized microleakage. In the current study, CLass V restorations (groups of 10 formaldehyde-treated non carious human molars were filled with Valiant (Ivoclar NA amalgam after application of one of three liners: Copalite varnish; Amalagambond Plus with microfiber; and Syntac/Variolink. The control group used no liner material. After 24 hours at 37°C/100% RH, samples were thermocycled (1000 eyeles in water at 5°C and 60°C (15 second dwell time in each. Samples were immersed in 5% methylene blue solution (4 hrs and observed under a stereomicroscope; interfaces also were examined by SEM. Krsukal Wallis ANOVA by ranks (P<0.01 and Mann Whitney U Tests (P<0.05 of the data indicate improvements (equivalent among the 3 different liners tested here over unlined amalgam preparations. Liner/aldehyde-crosslinked dentin interphases, without technique-sensitive composites, may minimize microleakage by improving amalgam contact (physical bonding.

  5. Pengaruh Penambahan Paladium Terhadap Perilaku Thermal Amalgam Tembaga Tinggi Tipe Lathe Cut

    Directory of Open Access Journals (Sweden)

    Ellyza Herda

    2015-09-01

    Full Text Available Effects of additing 1 percent (w/o palladium (Pd on the thermal behavior of a lathe cut type high copper amalgam (13 w/o copper were studied. The identical alloys, with and without 1% Pd were fabricated. X-ray diffraction studies of the amalgams revealed the elimination of the γ2-phase by Pd addition DSC thermogram of non-Pd containing amalgam indicated the existence of two γ1-phaseone with the transition temperature (endothermic peak at 88◦C and the other at 109◦C. The thermogram data of the Pd containing amalgam showed an endothermic peak at 110.7◦C. The transition temperature of the n phase of the palladium containing amalgam is 4.9◦C lower than the transition temperature of the n phase of the non Pd containing amalgam. This result indicates that the n phase of the Pd containing amalgam includes more of Tin (Sn than the non-Pd containing amalgam. The thermogravimetri diagram showed that the phase decomposition occurred at about 390◦C for the non-Pd containing amalgam and at about 410◦C for the Pd containing amalgam. It is concluded that the addition of 1% Pd into a lathe cut type of high copper amalgam (13% could eliminate the formation of γ2 phase as well as an unstable γ1 phase, promoting strong mercury bonding to Silver.

  6. Reduction-oxidation Enabled Glass-ceramics to Stainless Steel Bonding Part II interfacial bonding analysis

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Steve Xunhu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Among glass-ceramic compositions modified with a variety of oxidants (AgO, FeO, NiO, PbO, SnO, CuO, CoO, MoO3 and WO3) only CuO and CoO doped glass-ceramics showed existence of bonding oxides through reduction-oxidation (redox) at the GC-SS interface. The CuO-modified glass-ceramics demonstrate the formation of a continuous layer of strong bonding Cr2O3 at the interface in low partial oxygen (PO2) atmosphere. However, in a local reducing atmosphere, the CuO is preferentially reduced at the surface of glass-ceramic rather than the GC-SS interface for redox. The CoO-modified glass-ceramics demonstrate improved GC-SS bonding. But the low mobility of Co++ ions in the GC limited the amount of CoO that can diffuse to and participate in redox at the interface.

  7. [Crack path in dental amalgams].

    Science.gov (United States)

    Oualint, S; Lagouvardos, P; Vougiouklakis, G

    1990-12-01

    The need of amalgam to resist fracture becomes a more evident necessity when restoration margins are taken into consideration. Marginal microcracks permit bacteria to pass beneath the restoration resulting in cement base dessalution, secondary caries and pulp inflammation. Fracture toughness of amalgam is usually studied indirectly from the maximum force required to fracture the amalgam, during compressive, tensile or bend stresses, through its ability to deform plastically or its surface hardness. Important information on fracture toughness of amalgams can be also taken from metallographic studies of their microstructures, during or after the formation of a crack. This study was planned to evaluate the microcracks produced on the surface of different amalgams, with a Vickers pyramid head of a hardness tester and their relation to the different phases of the amalgam structure. Seven amalgams were studied: Amalcap-F, Tytin, Cupralloy, Ana-2000 and three experimental combinations of them, in order to have in the same amalgam different alloy particles, for evaluation purposes. The result showed that the structure elements, that mainly assist crack formation and propagation, are voids and gamma 2-phase, while elements that resist fracture are alloy particles (gamma-phase) in conventional amalgams, eutectic spheres in admixed high copper amalgams and eta'-phase crystals in single melt high copper amalgams.

  8. Cycloaddition Reaction of Hydrogen-Bonded Zn(II)

    Indian Academy of Sciences (India)

    2.2 Synthesis of Complexes. 2.2a [{Zn(H2O)3(bpe)2}2(bpe)](NO3)4·3bpe·14H2O. (1): Single crystals of 1 were synthesized based on the reported procedure with a slight modification.12. Zn(NO3)26H2O (14mg, .... ity of coumarin in solid state as shown in Figure 2. Here, θ1 represents rotational angle of one double bond.

  9. In vivo and in vitro evaluations of microleakage around Class I amalgam and composite restorations.

    Science.gov (United States)

    Alptekin, Tuncay; Ozer, Fusan; Unlu, Nimet; Cobanoglu, Nevin; Blatz, Markus B

    2010-01-01

    This study evaluated and compared microleakage values of in vivo and in vitro placed Class I amalgam restorations with or without three different lining materials and posterior composite restorations with two dentin bonding agents. For the in vivo group, 72 standardized Class I cavities were prepared on the occlusal surfaces of molars scheduled for extraction. The test groups (n = 12) were: amalgam without lining (A), amalgam with cavity varnish (A+C), amalgam with Clearfil SE Bond (A+CSE), amalgam with Clearfil 2V (A+C2V), composite with Clearfil SE Bond (C+CSE) and composite with Protect Bond (C+PB). The restored teeth were extracted after seven days. The same grouping, materials and techniques were used in 72 extracted molars for the in-vitro part of the study. The specimens were immersed in basic fuchsin for 24 hours and sectioned. Microleakage was examined and scored at 20x magnification. Statistical analyses were performed with the Kruskal-Wallis and Mann-Whitney U-tests with the 5% level of significance. Overall, the in vivo and in vitro test groups were not different from each other. No significant differences in microleakage values were observed between the unlined and lined amalgam groups (p > 0.05). However, since lined amalgam restorations did not reveal any marginal leakage, the application of an adhesive bonding material under the amalgam restorations can be considered. In general, cavity varnish was not as effective as adhesive bonding agents in preventing microleakage in amalgam restorations. Composite restorations demonstrated higher leakage values than amalgam restorations (p 0.05) in the in vivo group. There was no significant difference between the two composite groups for in vitro and in vivo conditions (p > 0.05).

  10. Ten-year clinical assessment of three posterior resin composites and two amalgams.

    Science.gov (United States)

    Mair, L H

    1998-08-01

    The long-term clinical performance of three posterior resin composites and two amalgams was assessed. Thirty Class II restorations each of P-30, Occlusin, Clearfil Posterior (composites), New True Dentalloy, and Solila Nova (amalgams) were placed. Reviews took place at 6 months and at 1, 2, 3, 4, 5, and 10 years. At each visit the gingival condition, the contact point status, and the presence of ledges, gaps, or recurrent caries were assessed. The color match, cavosurface marginal stain, general surface stain, tarnish, and corrosion were also scored where applicable. Epoxy resin replicas were used to measure the maximum depth of wear. After 10 years, there had been corrosion of both the high- and low-copper amalgams and a slight deterioration in color match of a number of composite restorations. Eighteen (of 20) Occlusin restorations had obvious cavosurface marginal stain, attributed to staining of the unfilled bonding resin layer. Statistical analysis indicated that New True Dentalloy, Solila Nova, and Clearfil-P exhibited significantly less wear than Occlusin and P-30. None of the restorations examined at the 10-year recall required replacement. The five materials, placed in a dental school environment, provided adequate clinical service for 10 years.

  11. Dynamics of Long-Distance Hydrogen-Bond Networks in Photosystem II.

    Science.gov (United States)

    Guerra, Federico; Siemers, Malte; Mielack, Christopher; Bondar, Ana-Nicoleta

    2018-03-28

    Photosystem II uses the energy of absorbed light to split water molecules, generating molecular oxygen, electrons and protons. The four protons generated during each reaction cycle are released to the lumen via mechanisms that are poorly understood. Given the complexity of photosystem II, which consists of multiple protein subunits and cofactor molecules and hosts numerous waters, a fundamental issue is finding transient networks of hydrogen bonds that bridge potential proton donor and acceptor groups. Here, we address this issue by performing all-atom molecular dynamics simulations of wild type and mutant photosystem II monomers, which we analyze using a new protocol designed to facilitate efficient analysis of hydrogen-bond networks. Our computations reveal that local protein/water hydrogen-bond networks can assemble transiently in photosystem II, such that the reaction center connects to the lumen. The dynamics of the hydrogen-bond networks couple to the protonation state of specific carboxylate groups, and are altered in a mutant with defective proton transfer. Simulations on photosystem II without its extrinsic PsbO subunit provide a molecular interpretation of the elusive functional role of this subunit.

  12. Electrochemical properties of corroded amalgams.

    Science.gov (United States)

    Moberg, L E

    1987-10-01

    Three types of amalgam, one conventional, ANA 68, and two with high copper content, Dispersalloy (dispersed type) and ANA 2000 (single composition type), were investigated. The amalgams were immersed for periods of 7 wk at a time, up to 35 wk, in 23 ml (37 degrees C) of 0.9% NaCl aqueous solutions and in 0.9% NaCl solution buffered with NaH2PO4 (8.8 mM) and Na2HPO4 (1.2 mM). The amalgam specimens were embedded in epoxy resin. The surface area of amalgam exposed to the solutions was 0.2 cm2 for each specimen. Every 7 wk the corrosion potential was measured, the amalgam specimens lightly brushed with a soft toothbrush, and the solutions renewed. After 14-21 wk and 35 wk the currents during anodic polarization sweeps over the amalgams were recorded. The corrosion potential for the high-Cu amalgams was somewhat more positive (noble) in the phosphate buffered solution than in the non-buffered solution during the 35 wk of corrosion. The phosphate buffer reduced the reactivity of the amalgams during anodic polarization. Corrosion made the amalgams more passive during the anodic polarization. However, all the elements leached from the amalgams into the solutions throughout the entire experiment.

  13. Fracture resistance of endodontically treated teeth restored with combined composite-amalgam restorations.

    Science.gov (United States)

    Geiger, Selly; Paikin, Lev; Gorfil, Colin; Gordon, Moshe

    2008-02-01

    To evaluate the resistance to fracture of endodontically treated teeth restored with combined composite-amalgam restorations in comparison to all-amalgam restorations. Forty-eight human premolar teeth were equally divided into 4 groups. Mesio-occlusodistal (MOD) cavities were prepared in 3 groups, and in the fourth group, a modified MOD preparation was designed with an additional buccolingual groove. All teeth were endodontically treated and restored using 1 of several restorative modalities: all amalgam (AM), all amalgam plus dentin adhesive (ADA), amalgam plus dentin adhesive plus composite resin (ADAC), and amalgam plus dentin adhesive plus composite resin with a modified preparation design (ADACM). Specimens were tested in a universal testing machine (Instron). The load (in kilonewtons) at fracture was recorded and statistically analyzed using a Bonferroni one-way statistical analysis (significance: Pcomposite-amalgam restoration were significantly more resistant to fracture ( Pamalgam alone. The modification with an additional horizontal buccolingual cavity preparation groove did not significantly increase resistance to fracture, nor did the addition of a bonding material to the amalgam restorations. Mean resistance to fracture (in kilonewtons) of each group was as follows: group AM, 0.31; group ADA, 0.34; group ADAC, 0.45; and group ADACM, 0.47. Restoration of endodontically treated teeth with combined composite-amalgam materials increased tooth resistance to fracture up to 51% when compared to teeth restored with amalgam alone.

  14. Corrosion behaviour of high copper dental amalgams.

    Science.gov (United States)

    Yap, A U J; Ng, B L; Blackwood, D J

    2004-06-01

    This study evaluated the corrosion behaviour of two high copper dental amalgam alloys [Dispersalloy (Dentsply-Caulk) and Tytin (Kerr)] in different electrolytes. Amalgam specimens were prepared, coupled to a copper wire, cemented into glass tubes and polished to a 600-grit finish. A corrosion cell was prepared using a carbon counter-electrode, a standard calomel electrode as the reference and amalgam as the working electrode. The alloys were tested in the following mediums at 37 degrees C: (i) artificial saliva based on Fusayama's solution (FS), (ii) artificial saliva with citric acid adjusted to pH 4.0 (FC) and (iii) 1% sodium chloride solution (SC). Corrosion potentials (E(corr)) and corrosion rates (I(corr)) were determined using potentiostatic and impedance spectroscopy methods. Data was subjected to anova/Scheffe's post hoc test at 0.05 significance level. For both alloys, the corrosion potential in FS was significantly greater than in SC. Corrosion potential of Tytin in FS and SC was also significantly greater than in FC. The corrosion rate of Dispersalloy in FC was significantly greater than in FS and SC. For Tytin, corrosion rate in SC was significantly greater than in FS and FC. Although no significant difference in corrosion potential/rate was observed between the alloys when tested in FS, significant differences were observed when electrochemical testing was carried out in FC and SC. The corrosion behaviour of high copper amalgam alloys are both material and environment dependent. Certain food substances may increase the corrosion of high copper amalgams.

  15. Effect of small cage guests on hydrogen bonding of tetrahydrofuran in binary structure II clathrate hydrates.

    Science.gov (United States)

    Alavi, Saman; Ripmeester, John A

    2012-08-07

    Molecular dynamics simulations of the pure structure II tetrahydrofuran clathrate hydrate and binary structure II tetrahydrofuran clathrate hydrate with CO(2), CH(4), H(2)S, and Xe small cage guests are performed to study the effect of the shape, size, and intermolecular forces of the small cages guests on the structure and dynamics of the hydrate. The simulations show that the number and nature of the guest in the small cage affects the probability of hydrogen bonding of the tetrahydrofuran guest with the large cage water molecules. The effect on hydrogen bonding of tetrahydrofuran occurs despite the fact that the guests in the small cage do not themselves form hydrogen bonds with water. These results indicate that nearest neighbour guest-guest interactions (mediated through the water lattice framework) can affect the clathrate structure and stability. The implications of these subtle small guest effects on clathrate hydrate stability are discussed.

  16. Self-assembly of a Co (II) dimer through H-bonding of water ...

    Indian Academy of Sciences (India)

    The solid-state structure reveals that the compound is a dimeric Co(II) complex assembled to a 3D architecture via an intricate intra- and inter-molecular hydrogen-bonding interactions involving water molecules and carboxylate oxygens of the ligand ptcH2-. Crystal data: monoclinic, space group 21/, = 11.441(5) Å, ...

  17. Health Implications of Dental Amalgam

    OpenAIRE

    Naimi-Akbar, Aron

    2013-01-01

    Dental amalgam is one of the most widely used, but also the most controversial of dental restorative materials. Since its introduction during the first half of the 19 th century, concerns have been raised about health hazards related to the toxicity of a major component of amalgam, mercury. This has been a particularly contentious issue in Swed en, where amalgam use was discontinued in 2009, on environmental grounds. Two aspects of particular concern are the release...

  18. Effect of a resin-based desensitizing agent and a self-etching dentin adhesive on marginal leakage of amalgam restorations.

    Science.gov (United States)

    Ghavamnasiri, Marjaneh; Alavi, Mohammad; Alavi, Samin

    2007-11-01

    The purpose of this study was to compare the marginal leakage of Class II amalgam restorations whose preparations were lined with a resin-based desensitizing agent, a self-etching adhesive system, and copal varnish. Fifty-six freshly extracted human premolar teeth were divided into four groups. A Class II preparation was prepared with only a proximal box on the mesial and distal surfaces of each tooth. The cavities in one group were lined with a desensitizing agent (VivaSens) and a second group with an adhesive (Clearfil S3 Bond). A third group was lined with copal varnish (Copalite) and a fourth group was used as the control without any cavity liner. Spherical high copper amalgam was hand-condensed into each preparation, specimens were thermocycled, stained, and sectioned. Microleakage was graded using a stereomicroscope. Microleakage scores were calculated and analyzed using the Kruskal Wallis and the Mann-Whitney tests (alpha=0.05). Less microleakage was indicated with the VivaSens liner when compared with the other groups (P0.05). VivaSens reduced the microleakage of Class II high copper amalgam restorations significantly more than the Clearfil S3 Bond and copal varnish.

  19. $1$-cohomology of simplicial amalgams of groups

    OpenAIRE

    Blok, Rieuwert J.; Hoffman, Corneliu G.

    2015-01-01

    We develop a cohomological method to classify amalgams of groups. We generalize this to simplicial amalgams in any concrete category. We compute the non-commutative 1-cohomology for several examples of amalgams defined over small simplices.

  20. 21 CFR 872.3100 - Dental amalgamator.

    Science.gov (United States)

    2010-04-01

    ... amalgamator is a device, usually AC-powered, intended to mix, by shaking, amalgam capsules containing mercury and dental alloy particles, such as silver, tin, zinc, and copper. The mixed dental amalgam material...

  1. Clinical evaluation of four dental amalgams over a two year period.

    Science.gov (United States)

    van der Merwe, W J

    1992-12-01

    The aim of this study was to determine the clinical durability of two locally manufactured amalgams. In each of eighty-two patients one class II cavity was restored with Dispersalloy (Johnson and Johnson) which served as the control and all the other class II cavities were randomly restored with one of the following amalgams: Amalgaphase, Amalga 43 (Amalgam Alloys-South Africa) or Permite C (Southern Dental Industries). Matrix bands were placed. Kalzinol bases and Polyvar varnish were applied in all cavities. All amalgams were mixed according to the manufacturers' instructions. The cavities were overpacked with amalgam, and the amalgam condensed by hand, carved and then burnished with a ball burnisher. Twenty-four hours later all restorations were polished with a Shofu polishing system and colour photographs were taken. The restorations were evaluated using the Ryge and Snyder (1973) evaluation system, as well as comparison of the colour photos. The Fisher's Exact Test was used for the statistical analysis. During the second year there were no significant (p amalgam restorations except as regards the gloss category. The two South African manufactured amalgams compared well with the two imported amalgams. During the second year the marginal integrity and surface texture of Amalgaphase compared well with that of Permite C. Dispersalloy and Permite C showed more deterioration in anatomic form than the two South African amalgams. Amalgaphase was the only amalgam to show no bulk fracture within a period of two years. Amalgaphase performed better in the gloss category than the other three amalgams during the second year evaluation. According to the weighted product calculation Amalgaphase was the best amalgam followed by Dispersalloy, Amalga 43 and Permite C.

  2. States on Orthomodular Amalgamations Over Trees

    Science.gov (United States)

    Al-Agha, Khaled J.; Greechie, Richard J.

    2006-02-01

    An amalgamation of bounded involution posets over a strictly directed graph is introduced and states on this amalgamation are studied. We introduce conditions under which the amalgamation induces a structure that is of the same type as that of the amalgamated structures. We also study circumstances under which common properties of the state spaces (such as unital, full, and strongly order determining) of the amalgamated structures are inherited by the amalgamation.

  3. Congruence amalgamation of lattices

    CERN Document Server

    Grätzer, G; Wehrung, F; Gr\\"{a}tzer, George; Lakser, Harry; Wehrung, Friedrich

    2000-01-01

    J. Tuma proved an interesting "congruence amalgamation" result. We are generalizing and providing an alternate proof for it. We then provide applications of this result: --A.P. Huhn proved that every distributive algebraic lattice $D$ with at most $\\aleph\\_1$ compact elements can be represented as the congruence lattice of a lattice $L$. We show that $L$ can be constructed as a locally finite relatively complemented lattice with zero. --We find a large class of lattices, the $\\omega$-congruence-finite lattices, that contains all locally finite countable lattices, in which every lattice has a relatively complemented congruence-preserving extension.

  4. [The future of dental amalgam

    NARCIS (Netherlands)

    Opdam, N.J.M.

    2005-01-01

    This paper is a comment on 'The enigma of dental amalgam' by Carl Leinfelder published in 2004 in the Journal of Esthetic and Restorative Dentistry. In that paper a warning is stated against a too abrupt change from amalgam towards resin composite, because this will bring a lot of clinical problems

  5. Amalgams and χ-Boundedness

    DEFF Research Database (Denmark)

    Penev, Irena

    2017-01-01

    , clique-cutsets, and amalgams together preserve χ-boundedness. More precisely, we show that if G and G∗ are hereditary classes of graphs such that G is χ-bounded, and such that every graph in G∗ either belongs to G or admits a proper homogeneous set, a clique-cutset, or an amalgam, then the class G∗ is χ...

  6. Axial Mn-CCN Bonds of Cyano Manganese(II) Porphyrin Complexes: Flexible and Weak?

    Science.gov (United States)

    He, Mingrui; Li, Xiangjun; Liu, Yanhong; Li, Jianfeng

    2016-06-20

    Three five-coordinate high-spin (cyano)manganese(II) complexes, utilized tetraphenylporphyrin (TPP), tetratolylporphyrin (TTP), and tetramesitylporphyrin (TMP) as ligands, are prepared and studied by single-crystal X-ray, FT-IR, UV-vis, and EPR spectroscopies. The crystal structure studies revealed noteworthy structural features including unexpectedly wide tilting angles of the axial Mn-CCN bonds, which is contrasted to the isoelectronic Fe(III)-CCN bonds. Solid-state EPR measurements (90 K) and simulations are applied to obtain the ZFS parameters (D, E, and E/D (λ)), which are compared to Mn(II) porphyrin analogues of hemes to understand the ligand field of the cyanide. The solution EPR studies gave new insights into the chemical equilibrium of four- and five-coordinate species, which has been monitored by UV-vis spectroscopy.

  7. [Enamel-dentinal adhesives in amalgam restorations. Review of the literature].

    Science.gov (United States)

    Cadenaro, M; Gregorig, G

    2000-06-01

    Amalgam is still the material most often used to restore posterior teeth, since it is easy to use, it has a low cost and a long clinical life. However, its use requires the solutions of several problems: lack of adhesion to tooth structure, marginal leakage, postoperative sensitivity and susceptibility to corrosion. In order to combine the advantages of dentinal adhesives with the excellent mechanical properties and good long clinical behaviour of amalgam, their use under amalgam restorations has been proposed. Adhesives improve marginal sealing and guarantee an additional retention to restorations, due to the formation of a layer linked with micromechanical bonds both to the tooth and the amalgam; they create a barrier that occludes dentinal tubules access, protecting the pulp. In this article the results of several in vitro studies performed to assess amalgam restorations properties are summarized. Present knowledge, based on an accurate literature review, allows to consider bonded amalgam restorations as a real progress in conservative dentistry: if long-term longitudinal studies, that are presently carried out, confirm the good short-term results, bonded restorations will represent the solution of choice for amalgam application.

  8. Microtensile Bond Strength of Adhesive Systems in Different Dentin Regions on a Class II Cavity Configuration.

    Science.gov (United States)

    Sinhoreti, Mário Alexandre Coelho; Soares, Eveline Freitas; Abuna, Gabriel Flores; Correr, Lourenço; Roulet, Jean-François; Geraldeli, Saulo

    2017-01-01

    The aim of this study was to evaluate microtensile bond strength (µTBS) of self-etch and etch-and-rinse adhesives systems compared in different dentin regions (central-CD or proximal-PD) in a class II cavity configuration. A class II (mesial-oclusal-distal) cavity configuration was simulated on 20 extracted human third-molars (4 mm wide/3 mm deep). Etch-and-rinse adhesive (Scotchbond Multi Purpose, n=5, SBMP and Optibond FL, n=5, OPFL) and self-etch adhesives (Clearfil SE Bond, n=5, CSE and Optibond XTR, n=5, OPXTR) were applied. Class II restorations were performed by incremental technique and photo-activated (Bluephase/G2). Samples were sectioned to beam shape (1 mm² cross-section), placed on Geraldeli's device for µTBS test (0.5 mm/min cross-head speed). Fracture patterns were analyzed on stereomicroscope and classified as cohesive-resin, adhesive, mixed/resin or mixed/dentin. Samples (n=4) were prepared for scanning electron microscope observation. Data were submitted to one-way ANOVA with Split-Plot arrangement and Tukey's test (α=0.05). There were no statistically significant differences among SBMP, OPFL, CSE and OPXTR on CD (p>0.05). However, on PD for SBMP and OPFL, µTBS values were significantly lower compared to CSE and OPXTR (padhesive). In class II type cavity configuration, PD location negatively influenced bond strength of etch-and-rinse adhesive systems. Opposite to self-etching adhesives, which presented higher bond strength values compared to etch-and-rinse adhesives in PD.

  9. Selective Palladium(II)-Catalyzed Carbonylation of Methylene β-C-H Bonds in Aliphatic Amines.

    Science.gov (United States)

    Cabrera-Pardo, Jaime R; Trowbridge, Aaron; Nappi, Manuel; Ozaki, Kyohei; Gaunt, Matthew J

    2017-09-18

    Palladium(II)-catalyzed C-H carbonylation reactions of methylene C-H bonds in secondary aliphatic amines lead to the formation of trans-disubstituted β-lactams in excellent yields and selectivities. The generality of the C-H carbonylation process is aided by the action of xantphos-based ligands and is important in securing good yields for the β-lactam products. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Novel Amalgams for In-Space Fabrication of Replacement Parts

    Science.gov (United States)

    Cochran, Calvin T.; Van Hoose, James R.; Grugel, R. N.

    2012-01-01

    Being able to fabricate replacement parts during extended space flight missions precludes the weight, storage volume, and speculation necessary to accommodate spares. Amalgams, widely used in dentistry, are potential candidates for fabricating parts in microgravity environments as they are moldable, do not require energy for melting, and do not pose fluid handling problems. Unfortunately, amalgams have poor tensile strength and the room temperature liquid component is mercury. To possibly resolve these issues a gallium-indium alloy was substituted for mercury and small steel fibers were mixed in with the commercial alloy powder. Subsequent microscopic examination of the novel amalgam revealed complete bonding of the components, and mechanical testing of comparable samples showed those containing steel fibers to have a significant improvement in strength. Experimental procedures, microstructures, and test results are presented and discussed in view of further improving properties.

  11. Study of gluing and wire bonding for the Belle II Silicon Vertex Detector

    International Nuclear Information System (INIS)

    Kang, K.H.; Hara, K.; Higuchi, T.; Hyun, H.J.; Jeon, H.B.; Joo, C.W.; Kah, D.H.; Kim, H.J.; Mibe, T.; Onuki, Y.; Park, H.; Rao, K.K.; Sato, N.; Shimizu, N.; Tanida, K.; Tsuboyama, T.; Uozumi, S.

    2014-01-01

    This paper describes an investigation into gluing and wire bonding for assembling the Silicon Vertex Detector (SVD) for the Belle II experiment at KEK in Japan. Optimizing the gluing of the silicon microstrip sensors, the support frame, and the readout flex cables is important for achieving the required mechanical precision. The wire bonding between the sensors and the readout electronic chips also needs special care to maximize the physics capability of the SVD. The silicon sensors and signal fan out flex circuits (pitch adapters) are glued and connected using wire bonding. We determine that gluing quality is important for achieving good bonding efficiency. The standard deviation in the glue thickness for the best result is measured to be 3.11 μm. Optimal machine parameters for wire bonding are determined to be 70 mW power, 20 gf force, and 20 ms for the pitch adapter and 60 mW power, 20 gf force, and 20 ms for the silicon strip sensors; these parameters provide a pull force of (10.92±0.72) gf. With these settings, 75% of the pitch adapters and 25% of the strip sensors experience the neck-broken type of break

  12. The microstructure of corroded amalgams.

    Science.gov (United States)

    Moberg, L E; Odén, A

    1985-07-01

    One conventional amalgam and two amalgams with a high copper content were stored in 0.9% NaCl solution buffered with phosphate to pH 6. In one experimental series the amalgams were placed in contact with a gold alloy. Every 7 weeks the solutions were changed and analyzed with regard to elements released from the amalgams. The microstructure of the specimens was studied in a scanning electron microscope before immersion and after 7 and 35 weeks in the solution. All the amalgams corroded along the grain boundaries in the gamma 1 phase. Corrosion was greatest in the gamma 2 phase of ANA 68, in the eta phase of ANA 2000 and in the reaction zone (eta + gamma 1) surrounding the Ag-Cu-eutectic particles of Dispersalloy. The microstructure of the corroded amalgams showed similarities to amalgams corroded in vivo. The change in microstructure observed in cross-sections of the corroded specimens was related to the amounts of corrosion products released into the saline solution.

  13. Cyclic voltammetry of dental amalgams.

    Science.gov (United States)

    Horasawa, N; Nakajima, H; Ferracane, J L; Takahashi, S; Okabe, T

    1996-05-01

    This study used cyclic voltammetry to examine the effect of the composition of dental amalgams on their electrochemical behavior, including reactions occurring outside of oral conditions. Amalgams (residual mercury 47.5%) were prepared using two low-copper (3 wt% Cu) powders and five high-copper powders (40-80 wt% Ag, 12-30 wt% Cu) with and without zinc (1.5 wt%). Cyclic voltammograms were obtained at 37 degrees C in 1.0% NaCl scanning at 2 mV/s in the potential range from -1.5 V to +0.8 V vs. Ag/AgCl. During the anodic scans, AgCl and Hg2Cl2 films were formed on all amalgams except the one with only 40 wt% Ag. In all high-copper amalgams, a prominent Cu (oxidation) peak was found at -0.1 V, indicating the release of copper during corrosion. Zinc affected the oxidation process for both low- and high-copper amalgams. When zinc was absent, a peak for Sn2+ oxidation appeared at -0.4 V. When zinc was present, a Sn4+ oxidation peak was revealed at -0.6 V. In some amalgams, there was evidence of the selective corrosion (pitting corrosion) of tin and copper. In the lowest silver-content amalgam, no protective films were formed, which is indicative of its poor corrosion resistance. As expected, in all the low-copper amalgams, an extreme increase in current density was recorded immediately at 0 V, due to the release of tin from gamma 2. Cyclic voltammetry is useful for the rapid examination (less than an hour) of the electrochemical behavior of amalgams, specifically to obtain information on the formation of compounds and the sequences of electrochemical reactions.

  14. Effect of Cooling Rate on the Longitudinal Modulus of Cu3Sn Phase of Ag-Sn-Cu Amalgam Alloy (Part II

    Directory of Open Access Journals (Sweden)

    R. H. Rusli

    2015-10-01

    Full Text Available Effects of cooling rate (at the time of solidification on the elastic constants of Cu3Sn phase of Ag-Sn-Cu dental amalgam alloy were studied. In this study, three types of alloys were made, with the composition Cu-38-37 wt% Sn by means of casting, where each alloy was subjected to different cooling rate, such as cooling on the air (AC, air blown (AB, and quenched in the water (WQ. X-ray diffraction, metallography, and Scanning Electron Microscopy with Energy Dispersive Spectroscopy studies of three alloys indicated the existence of Cu3Sn phase. Determination of the modulus of elasticity of Cu3Sn (ε phase was carried out by the measurement of longitudinal and transversal waves velocity using ultrasonic technique. The result shows that Cu3Sn (ε phase on AC gives higher modulus of elasticity values than those of Cu3Sn (ε on AB and WQ. The high modulus of elasticity value will produce a strong Ag-Sn-Cu dental amalagam alloy.

  15. A study of sister chromatid exchange in patients with dental amalgam restorations.

    Science.gov (United States)

    Priya, E Lakshmi; Ranganathan, K; Rao, Uma Devi K; Joshua, Elizabeth; Mathew, Deepu George; Wilson, Kavitha

    2014-01-01

    Dental amalgam is still widely used as a restorative material in developing countries due to its low cost and ease of manipulation. The health risks associated with the components of this restorative material has always been a matter of concern. Our study was designed to address this question regarding dental amalgam. To study sister chromatid exchange (SCE) as an indicator of systemic genotoxicity, due to the exposure from the components of amalgam restorations during its placement and chronic use. Systemic genotoxicity in subjects exposed to amalgam during its placement (Group II; n=5) and subjects with chronic exposure to amalgam (Group III; n=5) were compared with controls (Group I; n=5) by SCE assay in cultured peripheral blood lymphocytes. Subjects exposed to amalgam during its placement and subjects having chronic exposure to amalgam showed an increase in the frequency of SCE, but the change was not statistically significant (P=0.84, P=0.123 respectively). Systemic genotoxicity was not observed due to the components of amalgam restorations released during its placement and chronic use. The findings of this study can be considered as preliminary information on the systemic toxicity due to the components of amalgam restorations.

  16. A bonding study toward the quality assurance of Belle-II silicon vertex detector modules

    Energy Technology Data Exchange (ETDEWEB)

    Kang, K.H.; Jeon, H.B. [RSRI, Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Park, H., E-mail: sunshine@knu.ac.kr [RSRI, Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Uozumi, S. [RSRI, Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Adamczyk, K. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Aihara, H. [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Angelini, C. [Dipartimento di Fisica, Universitá di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Aziz, T.; Babu, V. [Tata Institute of Fundamental Research, Mumbai 400005 (India); Bacher, S. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Bahinipati, S. [Indian Institute of Technology Bhubaneswar, Satya Nagar (India); Barberio, E.; Baroncelli, T. [School of Physics, University of Melbourne, Melbourne, Victoria 3010 (Australia); Basith, A.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Batignani, G. [Dipartimento di Fisica, Universitá di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bauer, A. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Behera, P.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Bergauer, T. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Bettarini, S. [Dipartimento di Fisica, Universitá di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bhuyan, B. [Indian Institute of Technology Guwahati, Assam 781039 (India); and others

    2016-09-21

    A silicon vertex detector (SVD) for the Belle-II experiment comprises four layers of double-sided silicon strip detectors (DSSDs), assembled in a ladder-like structure. Each ladder module of the outermost SVD layer has four rectangular and one trapezoidal DSSDs supported by two carbon-fiber ribs. In order to achieve a good signal-to-noise ratio and minimize material budget, a novel chip-on-sensor “Origami” method has been employed for the three rectangular sensors that are sandwiched between the backward rectangular and forward (slanted) trapezoidal sensors. This paper describes the bonding procedures developed for making electrical connections between sensors and signal fan-out flex circuits (i.e., pitch adapters), and between pitch adapters and readout chips as well as the results in terms of the achieved bonding quality and pull force. - Highlights: • Gluing and wire binding for Belle-II SVD are studied. • Gluing robot and Origami module are used. • QA are satisfied in terms of the achieved bonding throughput and the pull force. • Result will be applied for L6 ladder assembly.

  17. A bonding study toward the quality assurance of Belle-II silicon vertex detector modules

    International Nuclear Information System (INIS)

    Kang, K.H.; Jeon, H.B.; Park, H.; Uozumi, S.; Adamczyk, K.; Aihara, H.; Angelini, C.; Aziz, T.; Babu, V.; Bacher, S.; Bahinipati, S.; Barberio, E.; Baroncelli, T.; Basith, A.K.; Batignani, G.; Bauer, A.; Behera, P.K.; Bergauer, T.; Bettarini, S.; Bhuyan, B.

    2016-01-01

    A silicon vertex detector (SVD) for the Belle-II experiment comprises four layers of double-sided silicon strip detectors (DSSDs), assembled in a ladder-like structure. Each ladder module of the outermost SVD layer has four rectangular and one trapezoidal DSSDs supported by two carbon-fiber ribs. In order to achieve a good signal-to-noise ratio and minimize material budget, a novel chip-on-sensor “Origami” method has been employed for the three rectangular sensors that are sandwiched between the backward rectangular and forward (slanted) trapezoidal sensors. This paper describes the bonding procedures developed for making electrical connections between sensors and signal fan-out flex circuits (i.e., pitch adapters), and between pitch adapters and readout chips as well as the results in terms of the achieved bonding quality and pull force. - Highlights: • Gluing and wire binding for Belle-II SVD are studied. • Gluing robot and Origami module are used. • QA are satisfied in terms of the achieved bonding throughput and the pull force. • Result will be applied for L6 ladder assembly.

  18. Structural and spectroscopic characterization of iron(II), cobalt(II), and nickel(II) ortho-dihalophenolate complexes: insights into metal-halogen secondary bonding.

    Science.gov (United States)

    Machonkin, Timothy E; Boshart, Monica D; Schofield, Jeremy A; Rodriguez, Meghan M; Grubel, Katarzyna; Rokhsana, Dalia; Brennessel, William W; Holland, Patrick L

    2014-09-15

    Metal complexes incorporating the tris(3,5-diphenylpyrazolyl)borate ligand (Tp(Ph2)) and ortho-dihalophenolates were synthesized and characterized in order to explore metal-halogen secondary bonding in biorelevant model complexes. The complexes Tp(Ph2)ML were synthesized and structurally characterized, where M was Fe(II), Co(II), or Ni(II) and L was either 2,6-dichloro- or 2,6-dibromophenolate. All six complexes exhibited metal-halogen secondary bonds in the solid state, with distances ranging from 2.56 Å for the Tp(Ph2)Ni(2,6-dichlorophenolate) complex to 2.88 Å for the Tp(Ph2)Fe(2,6-dibromophenolate) complex. Variable temperature NMR spectra of the Tp(Ph2)Co(2,6-dichlorophenolate) and Tp(Ph2)Ni(2,6-dichlorophenolate) complexes showed that rotation of the phenolate, which requires loss of the secondary bond, has an activation barrier of ~30 and ~37 kJ/mol, respectively. Density functional theory calculations support the presence of a barrier for disruption of the metal-halogen interaction during rotation of the phenolate. On the other hand, calculations using the spectroscopically calibrated angular overlap method suggest essentially no contribution of the halogen to the ligand-field splitting. Overall, these results provide the first quantitative measure of the strength of a metal-halogen secondary bond and demonstrate that it is a weak noncovalent interaction comparable in strength to a hydrogen bond. These results provide insight into the origin of the specificity of the enzyme 2,6-dichlorohydroquinone 1,2-dioxygenase (PcpA), which is specific for ortho-dihalohydroquinone substrates and phenol inhibitors.

  19. Heterometallic Pd(II)-Ni(II) complexes with meso-substituted dibenzotetraaza[14]annulene: double C-H bond activation and formation of a rectangular tetradibenzotetraaza[14]annulene.

    Science.gov (United States)

    Khaledi, Hamid; Olmstead, Marilyn M; Fukuda, Takamitsu; Ali, Hapipah Mohd

    2014-11-03

    Three isomeric 2[Pd(II)-Ni(II)] metal complexes, derived from indoleninyl meso-substituted dibenzotetraaza[14]annulene, were synthesized. The resulting dimers feature Ni···Ni or, alternatively, Ni···π interactions in staggered or slipped cofacial structures. A remarkable insertion of palladium into two different C-H bonds yielded a 4[Pd(II)-Ni(II)] rectangular complex with dimensions of 8.73 × 10.38 Å.

  20. Creep as a mechanism for sealing amalgams.

    Science.gov (United States)

    Osborne, John W

    2006-01-01

    Dental amalgam seals itself over time. The reduction of microleakage in amalgam restorations has been explained by corrosion products filling in the interface gap between amalgam and tooth structure in order to seal the restoration interface. This concept has been widely accepted; yet, curiously, there is little research supporting this theory. The creep mechanism may be a plausible alternative to explaining why microleakage is reduced over time in amalgam restorations. Amalgam restorations are confined to the fixed space of the cavity preparation; expansion of the amalgam through internal phase changes in this confined area must be relieved. The resultant creep-expansion of the amalgam restoration fills in the tooth/amalgam interface gap. Once the interfacial gap is filled and amalgam has made intimate contact with the cavity wall, the dental amalgam slides along the tooth preparation plane as predicted by classic metallurgical studies. The results of the creep of amalgam have been observed clinically as the extrusion of amalgam from the cavity preparation. This explanation for amalgam sealing the tooth/amalgam gap fits many clinical observations and certain research data.

  1. Retention of cast crowns cemented to amalgam and composite resin cores.

    Science.gov (United States)

    Hormati, A A; Denehy, G E

    1981-05-01

    An in vitro study was conducted to determine the tensile bond strength of complete cast gold restorations cemented with zinc phosphate cement on composite resin and amalgam crown cores. The samples were thermocycled and tested at 1-week, 1-month, and 3-month intervals. Results of the study showed that: (1) the amalgam core provides more retention for the cast gold crown than does the composite resin core and (2) the composite resin core provides increasing retention over a longer time period.

  2. Selective Palladium(II)-Catalyzed Carbonylation of Methylene β-C-H Bonds in Aliphatic Amines.

    OpenAIRE

    Cabrera-Pardo, Jaime R; Trowbridge, Aaron; Nappi, Manuel; Ozaki, Kyohei; Gaunt, Matthew James

    2017-01-01

    Pd(II)-catalyzed C–H carbonylation of methylene C–H bonds in secondary aliphatic amines leads to the formation trans-disubstituted β-lactams in excellent yields and selectivities. The generality of the C–H carbonylation process is aided by the action of xantphos-based ligands and is important in securing good yields of the β-lactam products. EPSRC (EP/100548X/1), ERC (ERC-STG-259711), Royal Society (Wolfson Award), Marie Curie Foundation and Herchel Smith Foundation.

  3. Application of Ni(II-assisted peptide bond hydrolysis to non-enzymatic affinity tag removal.

    Directory of Open Access Journals (Sweden)

    Edyta Kopera

    Full Text Available In this study, we demonstrate a non-enzymatic method for hydrolytic peptide bond cleavage, applied to the removal of an affinity tag from a recombinant fusion protein, SPI2-SRHWAP-His(6. This method is based on a highly specific Ni(II reaction with (S/TXHZ peptide sequences. It can be applied for the protein attached to an affinity column or to the unbound protein in solution. We studied the effect of pH, temperature and Ni(II concentration on the efficacy of cleavage and developed an analytical protocol, which provides active protein with a 90% yield and ∼100% purity. The method works well in the presence of non-ionic detergents, DTT and GuHCl, therefore providing a viable alternative for currently used techniques.

  4. The Post-Amalgam Era: Norwegian Dentists’ Experiences with Composite Resins and Repair of Defective Amalgam Restorations

    Science.gov (United States)

    Kopperud, Simen E.; Staxrud, Frode; Espelid, Ivar; Tveit, Anne Bjørg

    2016-01-01

    Amalgam was banned as a dental restorative material in Norway in 2008 due to environmental considerations. An electronic questionnaire was sent to all dentists in the member register of the Norwegian Dental Association (NTF) one year later, to evaluate dentists’ satisfaction with alternative restorative materials and to explore dentists’ treatment choices of fractured amalgam restorations. Replies were obtained from 61.3%. Composite was the preferred restorative material among 99.1% of the dentists. Secondary caries was the most commonly reported cause of failure (72.7%), followed by restoration fractures (25.1%). Longevity of Class II restorations was estimated to be ≥10 years by 45.8% of the dentists, but 71.2% expected even better longevity if the restoration was made with amalgam. Repair using composite was suggested by 24.9% of the dentists in an amalgam restoration with a fractured cusp. Repair was more often proposed among young dentists (p composite as a restorative material. Most dentists chose minimally- or medium invasive approaches when restoring fractured amalgam restorations. PMID:27110804

  5. The Post-Amalgam Era: Norwegian Dentists’ Experiences with Composite Resins and Repair of Defective Amalgam Restorations

    Directory of Open Access Journals (Sweden)

    Simen E. Kopperud

    2016-04-01

    Full Text Available Amalgam was banned as a dental restorative material in Norway in 2008 due to environmental considerations. An electronic questionnaire was sent to all dentists in the member register of the Norwegian Dental Association (NTF one year later, to evaluate dentists’ satisfaction with alternative restorative materials and to explore dentists’ treatment choices of fractured amalgam restorations. Replies were obtained from 61.3%. Composite was the preferred restorative material among 99.1% of the dentists. Secondary caries was the most commonly reported cause of failure (72.7%, followed by restoration fractures (25.1%. Longevity of Class II restorations was estimated to be ≥10 years by 45.8% of the dentists, but 71.2% expected even better longevity if the restoration was made with amalgam. Repair using composite was suggested by 24.9% of the dentists in an amalgam restoration with a fractured cusp. Repair was more often proposed among young dentists (p < 0.01, employees in the Public Dental Service (PDS (p < 0.01 and dentists working in counties with low dentist density (p = 0.03. There was a tendency towards choosing minimally invasive treatment among dentists who also avoided operative treatment of early approximal lesions (p < 0.01. Norwegian dentists showed positive attitudes towards composite as a restorative material. Most dentists chose minimally- or medium invasive approaches when restoring fractured amalgam restorations.

  6. The Post-Amalgam Era: Norwegian Dentists' Experiences with Composite Resins and Repair of Defective Amalgam Restorations.

    Science.gov (United States)

    Kopperud, Simen E; Staxrud, Frode; Espelid, Ivar; Tveit, Anne Bjørg

    2016-04-22

    Amalgam was banned as a dental restorative material in Norway in 2008 due to environmental considerations. An electronic questionnaire was sent to all dentists in the member register of the Norwegian Dental Association (NTF) one year later, to evaluate dentists' satisfaction with alternative restorative materials and to explore dentists' treatment choices of fractured amalgam restorations. Replies were obtained from 61.3%. Composite was the preferred restorative material among 99.1% of the dentists. Secondary caries was the most commonly reported cause of failure (72.7%), followed by restoration fractures (25.1%). Longevity of Class II restorations was estimated to be ≥10 years by 45.8% of the dentists, but 71.2% expected even better longevity if the restoration was made with amalgam. Repair using composite was suggested by 24.9% of the dentists in an amalgam restoration with a fractured cusp. Repair was more often proposed among young dentists (p composite as a restorative material. Most dentists chose minimally- or medium invasive approaches when restoring fractured amalgam restorations.

  7. Effect of resin coating on dentin bonding of resin cement in Class II cavities.

    Science.gov (United States)

    Sultana, Shamim; Nikaido, Toru; Matin, Khairul; Ogata, Miwako; Foxton, Richard M; Tagami, Junji

    2007-07-01

    This study was designed to evaluate the efficacy of resin coating on the regional microtensile bond strength (MTBS) of a resin cement to the dentin walls of Class II cavities. Twenty mesio-occlusal cavities were prepared in human molars. In 10 cavities, a resin coating consisting of a self-etching primer bonding system, Clearfil SE Bond, and a low-viscosity microfilled resin, Protect Liner F, was applied. The other 10 teeth served as a non-coating group. After impression taking and temporization, they were kept in water for one day. Composite inlays were then cemented with a dual-cure resin cement, Panavia F 2.0, and stored in water for one day. Thereafter, MTBSs were measured. Two-way ANOVA (p=0.05) revealed that the MTBS of resin cement to dentin was influenced by resin coating, but not by regional difference. In conclusion, application of a resin coating to the dentin surface significantly improved the MTBS in indirect restorations.

  8. Madumycin II inhibits peptide bond formation by forcing the peptidyl transferase center into an inactive state

    Energy Technology Data Exchange (ETDEWEB)

    Osterman, Ilya A.; Khabibullina, Nelli F.; Komarova, Ekaterina S.; Kasatsky, Pavel; Kartsev, Victor G.; Bogdanov, Alexey A.; Dontsova, Olga A.; Konevega, Andrey L.; Sergiev, Petr V.; Polikanov, Yury S. (InterBioScreen); (UIC); (MSU-Russia); (Kurchatov)

    2017-05-13

    The emergence of multi-drug resistant bacteria is limiting the effectiveness of commonly used antibiotics, which spurs a renewed interest in revisiting older and poorly studied drugs. Streptogramins A is a class of protein synthesis inhibitors that target the peptidyl transferase center (PTC) on the large subunit of the ribosome. In this work, we have revealed the mode of action of the PTC inhibitor madumycin II, an alanine-containing streptogramin A antibiotic, in the context of a functional 70S ribosome containing tRNA substrates. Madumycin II inhibits the ribosome prior to the first cycle of peptide bond formation. It allows binding of the tRNAs to the ribosomal A and P sites, but prevents correct positioning of their CCA-ends into the PTC thus making peptide bond formation impossible. We also revealed a previously unseen drug-induced rearrangement of nucleotides U2506 and U2585 of the 23S rRNA resulting in the formation of the U2506•G2583 wobble pair that was attributed to a catalytically inactive state of the PTC. The structural and biochemical data reported here expand our knowledge on the fundamental mechanisms by which peptidyl transferase inhibitors modulate the catalytic activity of the ribosome.

  9. 21 CFR 872.3070 - Dental amalgam, mercury, and amalgam alloy.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental amalgam, mercury, and amalgam alloy. 872... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3070 Dental amalgam, mercury... elemental mercury, supplied as a liquid in bulk, sachet, or predosed capsule form, and amalgam alloy...

  10. Longevity of dental amalgam in comparison to composite materials

    Directory of Open Access Journals (Sweden)

    Windisch, Friederike

    2008-11-01

    Full Text Available Health political background: Caries is one of the most prevalent diseases worldwide. For (direct restaurations of carious lesions, tooth-coloured composite materials are increasingly used. The compulsory health insurance pays for composite fillings in front teeth; in posterior teeth, patients have to bear the extra cost. Scientific background: Amalgam is an alloy of mercury and other metals and has been used in dentistry for more than one hundred and fifty years. Composites consist of a resin matrix and chemically bonded fillers. They have been used for about fifty years in front teeth. Amalgam has a long longevity; the further development of composites has also shown improvements regarding their longevity. Research questions: This HTA-report aims to evaluate the longevity (failure rate, median survival time (MST, median age of direct amalgam fillings in comparison to direct composite fillings in permanent teeth from a medical and economical perspective and discusses the ethical, legal and social aspects of using these filling materials. Methods: The systematic literature search yielded a total of 1,149 abstracts. After a two-step selection process based on defined criteria 25 publications remained to be assessed. Results: The medical studies report a longer longevity for amalgam fillings than for composite fillings. However, the results of these studies show a large heterogeneity. No publication on the costs or the cost-effectiveness of amalgam and composite fillings exists for Germany. The economic analyses (NL, SWE, GB report higher costs for composite fillings when longevity is assumed equal (for an observation period of five years or longer for amalgam compared to composite fillings. These higher costs are due to the higher complexity of placing composite fillings. Discussion: Due to different study designs and insufficient documentation of study details, a comparison of different studies on longevity of direct amalgam and composite

  11. Longevity of dental amalgam in comparison to composite materials.

    Science.gov (United States)

    Antony, Katja; Genser, Dieter; Hiebinger, Cora; Windisch, Friederike

    2008-11-13

    Caries is one of the most prevalent diseases worldwide. For (direct) restaurations of carious lesions, tooth-coloured composite materials are increasingly used. The compulsory health insurance pays for composite fillings in front teeth; in posterior teeth, patients have to bear the extra cost. Amalgam is an alloy of mercury and other metals and has been used in dentistry for more than one hundred and fifty years. Composites consist of a resin matrix and chemically bonded fillers. They have been used for about fifty years in front teeth. Amalgam has a long longevity; the further development of composites has also shown improvements regarding their longevity. This HTA-report aims to evaluate the longevity (failure rate, median survival time (MST), median age) of direct amalgam fillings in comparison to direct composite fillings in permanent teeth from a medical and economical perspective and discusses the ethical, legal and social aspects of using these filling materials. The systematic literature search yielded a total of 1,149 abstracts. After a two-step selection process based on defined criteria 25 publications remained to be assessed. The medical studies report a longer longevity for amalgam fillings than for composite fillings. However, the results of these studies show a large heterogeneity. No publication on the costs or the cost-effectiveness of amalgam and composite fillings exists for Germany. The economic analyses (NL, SWE, GB) report higher costs for composite fillings when longevity is assumed equal (for an observation period of five years) or longer for amalgam compared to composite fillings. These higher costs are due to the higher complexity of placing composite fillings. Due to different study designs and insufficient documentation of study details, a comparison of different studies on longevity of direct amalgam and composite fillings in posterior teeth is difficult. Apart from the difficulties in conducting a randomized, controlled long-term study

  12. Benefits and disadvantages of tooth-coloured alternatives to amalgam.

    Science.gov (United States)

    Roulet, J F

    1997-11-01

    To give the practising dentist scientifically based data to assist him/her in the responsible decision-making process necessary to weigh the options available to the patient if she/he prefers not to have an amalgam placed. Based on the literature and on the research work, which was done in the author's department, the indications and limitations of the known alternatives of amalgam were formulated. DESCRIPTION OF ALTERNATIVES TO AMALGAM: With the exception of cast gold restorations, all alternatives require the strict use of adhesive techniques. When compared with similar amalgam restorations, placing composite restorations (if they are indicated) takes approximately 2.5 times longer because complex incremental techniques are needed. Despite all the efforts, direct composite restorations placed in large cavities still show unacceptable amounts of marginal openings. Tooth-coloured inlays are a better alternative for large restorations. These restorations must be inserted with adhesive techniques. With composite inlays it is difficult to achieve a composite-composite bond. Ceramic inlays may be micromechanically bonded to the luting composite. They all show clinically a good marginal behaviour and the use of ultrasonic energy may further simplify the application technique of aesthetic inlays. Papers describing the different techniques were used as a base for the corresponding chapter. To assess and compare the longevity of the different restoration types, literature data were used. We limited ourselves to papers reporting at least 5-year clinical data. Longitudinal, clinically controlled studies were preferred. However, to be more complete, retrospective, cross sectional studies were also included. LONGEVITY OF POSTERIOR RESTORATIONS: Amalgam shows excellent longevity data with studies up to 20 years. The average annual failure rate is 0.3-6.9%. Posterior composites are in the same range (0.5-6.6%), however, the study times are much shorter (max. 10 years). For tooth

  13. Penetration of amalgam constituents into dentine.

    Science.gov (United States)

    Scholtanus, Johannes D; Ozcan, Mutlu; Huysmans, Marie-Charlotte D N J M

    2009-05-01

    Amalgam restorations are replaced by adhesively placed composite resin restorations at an increasing rate. After the removal of amalgam dentine often shows marked dark discoloration that is attributed to the penetration of corrosion products from overlying amalgams. It is questioned whether penetration of metals into dentine affects the dentine as a substrate for adhesive procedures. This study has been performed to clarify the origin of dark discoloration of dentine by metals from amalgam with special regards to corrosion products. A review of the literature has been performed using Medline database. As keywords dentine and amalgam, subsequently combined with penetration, interface, crevice, interaction, corrosion, were used. This was followed up by extensive hand search using reference lists of relevant articles. Data in the literature have been gathered from extracted amalgam filled teeth and from artificially aged amalgam filled teeth. Corrosion studies have been performed in vivo aged teeth as well as in vitro. Sn is the main element, followed by Zn and Cu, that is consistently found in dentine underneath amalgam, as well as in amalgam corrosion products and in marginal seal deposits. Penetration of elements from amalgam has only been observed in discolored and in demineralised dentine. Darkly discolored dentine as found underneath amalgam restorations contains amalgam corrosion products and is demineralised. Therefore it must be considered a different substrate for clinical procedures than sound dentine.

  14. Periodontal treatment of an amalgam tattoo.

    Science.gov (United States)

    Kissel, Scott O; Hanratty, James J

    2002-10-01

    The amalgam tattoo can often result in an unsightly cosmetic appearance, especially in the maxillary anterior region. The predominant treatment for an amalgam tattoo is the free gingival graft, which also results in a poor cosmetic appearance. The authors would like to review the pathogenesis of the amalgam tattoo and present a new technique that leads to a pleasing cosmetic result.

  15. Penetration of amalgam constituents into dentine.

    NARCIS (Netherlands)

    Scholtanus, J.D.; Ozcan, M.; Huysmans, M.C.D.N.J.M.

    2009-01-01

    OBJECTIVES: Amalgam restorations are replaced by adhesively placed composite resin restorations at an increasing rate. After the removal of amalgam dentine often shows marked dark discoloration that is attributed to the penetration of corrosion products from overlying amalgams. It is questioned

  16. Risks of amalgam toxity in dental treatment

    African Journals Online (AJOL)

    Risks of amalgam toxity in dental treatment. Majambo M.~. " Dental amalgam has been, one of the mo'st serviceable restorative material used in dentistry for over I OOyrs. Its numerous clinical adv~ntage's eg.:High mechanical str~ngth, good working properties etc; may account for its popularity. Amalgam is indicated for ...

  17. Amalgams still viable, safe treatment, controversies notwithstanding.

    Science.gov (United States)

    Dixon, S E

    1998-01-01

    This article addresses the dental amalgam debate from two aspects. The first is a review of the current status regarding the appropriate treatment planning of direct restorations. The second is a discussion of the safety of amalgam and the mercury toxicity concerns. Dental research continues to support the use of amalgam while the search continues for the "ideal" restorative material.

  18. Amalgam contact hypersensitivity lesion: an unusual presentation ...

    African Journals Online (AJOL)

    Amalgam or its components may cause Type IV hypersensitivity reactions on the oral mucosa. These amalgam contact hypersensitivity lesions (ACHL) present as white striae and plaques, erythematous, erosive, atrophic, or ulcerative lesions. Postinflammatory pigmentation in such lesions and pigmentation due to amalgam ...

  19. Penetration of amalgam constituents into dentine

    NARCIS (Netherlands)

    Scholtanus, Johannes D.; Ozcan, Mutlu; Huysmans, Marie-Charlotte D. N. J. M.

    Objectives: Amalgam restorations are replaced by adhesively placed composite resin restorations at an increasing rate. After the removal of amalgam dentine often shows marked dark discoloration that is attributed to the penetration of corrosion products from overlying amalgams. it is questioned

  20. Amalgam Contact Hypersensitivity Lesion: An Unusual Presentation ...

    African Journals Online (AJOL)

    They also state that the lesion considerably regressed after replacement of the amalgam restoration with posterior composites. Interestingly, these authors clearly confirmed that hypersensitivity to amalgam might be attributed to mercury in amalgam, but they did not rule out the significant role of exposure to common sources.

  1. The use of amalgam in pediatric dentistry: new insights and reappraising the tradition.

    Science.gov (United States)

    Fuks, Anna B

    2015-01-01

    The debate on amalgam led to its being phased out in some countries. Results of clinical trials report failure rates of amalgams ranging from 12 percent to over 70 percent. Treatment of caries should meet the needs of each particular patient, based on his/her caries risk. In general, for small occlusal lesions, a conservative preventive resin restoration would be more appropriate than the classic Class I amalgam preparation. For proximal lesions, amalgam would be indicated for two-surface Class II preparations that do not extend beyond the line angles of primary teeth. This recommendation might not be appropriate for high-risk patients or restoring primary first molars in children four years old and younger where stainless steel crowns have demonstrated better longevity. Currently, amalgam demonstrates the best clinical success for Class II restorations that extend beyond the proximal line angles of permanent molars. The need to reduce the use of amalgam as a mercury-containing material is inevitable when aiming to reduce environmental contamination. It is important always to praise prevention and constantly search for biologically safe materials regarding health, clinical work, and environment. The purpose of this report was to summarize several factors that affect the effectiveness, advantages, and disadvantages of using dental amalgam in primary teeth.

  2. Composite Replacement of Amalgam Restoration Versus Freshly Cut Dentin: An In Vitro Microleakage Comparison.

    Science.gov (United States)

    Redwan, H; Bardwell, D N; Ali, A; Finkelman, M; Khayat, S; Weber, H-P

    2016-01-01

    The aim of this study was to evaluate the microleakage of the composite restorations when bonded to tooth structure previously restored with amalgam material compared with that of freshly cut dentin. Thirty intact, extracted intact human molars were mounted in autopolymerizing acrylic resin. Class II box preparations were prepared on the occluso-proximal surfaces of each tooth (4-mm bucco-lingual width and 2-mm mesio-distal depth) with the gingival cavosurface margin 1 mm above the CEJ. Each cavity was then restored using high copper amalgam restoration (Disperalloy, Dentsply) and then thermocycled for 10,000 thermal cycles. Twenty-five of the amalgam restorations were then carefully removed and replaced with Filtek Supreme Ultra Universal (3M ESPE); the remaining five were used for scanning electron microscopy and energy dispersive x-ray spectroscopy analysis. A preparation of the same dimensions was performed on the opposite surface of the tooth and restored with composite resin and thermocycled for 5000 thermal cycles. Twenty samples were randomly selected for dye penetration testing using silver nitrate staining to detect the microleakage. The specimens were analyzed with a stereomicroscope at a magnification of 20×. All of the measurements were done in micrometers; two readings were taken for each cavity at the occlusal and proximal margins. Two measurements were taken using a 0-3 scale and the percentage measurements. Corrosion products were not detected in either group (fresh cut dentin and teeth previously restored with amalgam). No statistically significant difference was found between the microleakage of the two groups using a 0-3 scale at the occlusal margins (McNemar test, p=0.727) or proximal margins (Wilcoxon signed-rank test, p=0.174). No significance difference was found between the two groups using the percentage measurements and a Wilcoxon signed-rank test at either the occlusal (p=0.675) or proximal (p=0.513) margins. However, marginal

  3. Conditioning of spent mercury by amalgamation

    International Nuclear Information System (INIS)

    Yim, S. P.; Shon, J. S.; An, B. G.; Lee, H. J.; Lee, J. W.; Ji, C. G.; Kim, S. H.; Yoon, J. H.; Yang, M. S.

    2002-01-01

    Solidification by amalgamation was performed to immobilize and stabilize the liquid spent mercury. First, the appropriate metal and alloy which can convert liquid mercury into a solid form of amalgam were selected through initial tests. The amalgam form, formulated in optimum composition, was characterized and subjected to performance tests including compressive strength, water immersion, leachability and initial vaporization rate to evaluate mechanical integrity, durability and leaching properties. Finally, bench scale amalgamation trial was conducted with about 1 kg of spent mercury to verify the feasibility of amalgamation method

  4. Hybridization vs. Bond Stretching Isomerism in Ru(II Cyclometalated Complexes of 2-Phenylpyridine

    Directory of Open Access Journals (Sweden)

    Roberto Salcedo

    2011-12-01

    Full Text Available The phenomenon of formation of two isomers, yellow and orange, of the cyclometalated Ru(II complex, [Ru(o-C6H4-py(MeCN4]+, was investigated by EELS spectroscopy and theoretical calculations. Both forms show very similar structures and spectroscopic properties, but slight differences in X-ray data and absorption between them were noted. No double minimum on the potential energy surface was found and thus these two forms cannot be considered as bond stretching isomers. However, the DFT study revealed the change in the hybridization of the carbon in trans-position of one of acetonitrile ligands. This effect can be responsible for the difference in colour. The results of the theoretical modelling coincide well with the experimental EELS data.

  5. Halogen bond tunability II: the varying roles of electrostatic and dispersion contributions to attraction in halogen bonds

    Czech Academy of Sciences Publication Activity Database

    Riley, Kevin Eugene; Murray, J. S.; Fanfrlík, Jindřich; Řezáč, Jan; Solá, R. J.; Concha, M. C.; Ramos, F. M.; Politzer, P.

    2013-01-01

    Roč. 19, č. 11 (2013), s. 4651-4659 ISSN 1610-2940 R&D Projects: GA ČR GBP208/12/G016 Grant - others:Operational Program Research and Development for Innovations(XE) CZ.1.05/2.1.00/03.0058 Institutional support: RVO:61388963 Keywords : dispersion * electrostatics * halogen bonding * noncovalent interactions Subject RIV: CE - Biochemistry Impact factor: 1.867, year: 2013

  6. Conserved water-mediated hydrogen bond network between TM-I, -II, -VI, and -VII in 7TM receptor activation

    DEFF Research Database (Denmark)

    Nygaard, Rie; Hansen, Louise Valentin; Mokrosinski, Jacek

    2010-01-01

    Five highly conserved polar residues connected by a number of structural water molecules together with two rotamer micro-switches, TrpVI:13 and TyrVII:20, constitute an extended hydrogen bond network between the intracellular segments of TM-I, -II, -VI, and -VII of 7TM receptors. Molecular dynamics...... simulations showed that, although the fewer water molecules in rhodopsin were relatively movable, the hydrogen bond network of the beta2-adrenergic receptor was fully loaded with water molecules that were surprisingly immobilized between the two rotamer switches, both apparently being in their closed...... (AsnI:18, AspII:10, and AsnVII:13), whereas others (AsnVII:12 and AsnVII:16) located one helical turn apart and sharing a water molecule were shown to be essential for agonist-induced signaling. It is concluded that the conserved water hydrogen bond network of 7TM receptors constitutes an extended...

  7. Dental amalgam exposure and urinary mercury levels in children: the New England Children's Amalgam Trial.

    Science.gov (United States)

    Maserejian, Nancy Nairi; Trachtenberg, Felicia L; Assmann, Susan F; Barregard, Lars

    2008-02-01

    Urinary mercury (U-Hg) excretion is a commonly used biomarker for mercury exposure from dental amalgam restorations. Our goal was to determine the most efficient measure of dental amalgam exposure for use in analyses concerning U-Hg in children. We analyzed time-sensitive longitudinal amalgam exposure data in children randomized to amalgam restorations (n = 267) during the 5-year New England Children's Amalgam Trial. We calculated 8 measures of amalgam, evaluating current versus cumulative exposure, teeth versus surfaces, and total versus posterior occlusal amalgams. Urine samples collected during follow-up years 3-5 were analyzed for mercury excretion. Multivariate models for current and cumulative U-Hg excretion estimated associations between exposures and U-Hg. At the end of follow-up, the average (+/- SD) cumulative exposure was 10.3 +/- 6.1 surfaces and 5.7 +/- 2.9 teeth ever filled with amalgam, corresponding to 30 +/- 21 surface-years. Amalgam measures and U-Hg were moderately correlated. Of amalgam exposure measures, the current total of amalgam surfaces was the most robust predictor of current U-Hg, whereas posterior occlusal surface-years was best for cumulative U-Hg. In multivariate models, each additional amalgam surface present was associated with a 9% increase in current U-Hg, and each additional posterior occlusal surface-year was associated with a 3% increase in cumulative U-Hg excretion (p amalgam exposure is insufficient. Studies of cumulative effects of mercury from amalgam exposure in children are likely to have improved validity and precision if time-sensitive amalgam exposure measures are used. In contrast, simple counts of current amalgam fillings are adequate to capture amalgam-related current U-Hg.

  8. Antimicrobial activity of amalgams, alloys and their elements and phases.

    Science.gov (United States)

    Morrier, J J; Suchett-Kaye, G; Nguyen, D; Rocca, J P; Blanc-Benon, J; Barsotti, O

    1998-03-01

    This in vitro study aimed to evaluate the antibacterial effect of amalgams, alloys, elements and phases against two cariogenic bacteria, Actinomyces viscosus and Streptococcus mutans. Test materials comprised: (i) commercial amalgams comprising Amalcap (Vivadent), Cavex Avalloy LC and DP (Cavex), Cupromuc (Merz), Fluoralloy and Synalloy (Dentoria); (ii) Ag-Cu alloy; (iii) gamma, gamma 1, gamma 2 and Cu6Sn5 phases; (iv) pure metal samples and chloride solutions of copper, mercury, tin and zinc; and (v) aqueous sodium fluoride. Bacterial suspensions of each of the two bacteria were grown in the presence of the test materials for 24 h. Antimicrobial effectiveness was assessed by measuring reduction in optical density at 640 nm using a visible spectrophotometer. Cupromuc/Fluoralloy, non gamma 2 amalgams and Amalcap displayed high, moderate and no antibacterial activity, respectively. Antibacterial effectiveness was not related to copper content. Whereas mercury, copper, Ag-Cu alloy, fluoride and zinc showed antibacterial activity (Hg > Cu > F > Zn), tin, gamma phases and Cu6Sn5 showed no such activity. Although the fluoride and copper solutions were most effective at 50 micrograms ml-1 concentration, their antibacterial action was still significant, albeit reduced, at 10 micrograms ml-1 concentration. This was not the case for mercury chloride which was just as effective at both concentrations. Our results show that although mercury and copper contribute significantly to the antibacterial properties of amalgams, a high copper content does not necessarily relate to high antibacterial effectiveness. These elements could be useful in conferring antibacterial properties to amalgam although their effects on host cells must be investigated.

  9. Amalgam-chromatographic separation of magnesium isotopes

    International Nuclear Information System (INIS)

    Klinskij, G.D.; Levkin, A.V.; Ivanov, S.A.

    1990-01-01

    Separation of magnesium isotopes within Mg(Hg)-MgI 2 system (in dimethylformamide) is conducted under amalgam-chromatographic conditions. Separation maximal degree, that is (1.09), for 24 Mg and 26 Mg and separation coefficient (α = 1.0089±0.006) are determined. Light isotopes are found to concentrate in the amalgam. Technique of thermal conversion of flows within amalgam-dimethylformamide system is suggested on the basis of reversible reaction of Ca-Mg element exchange

  10. Amalgam tattoo: a cause of sinusitis?

    OpenAIRE

    Parizi, José Luiz Santos; Nai, Gisele Alborghetti

    2010-01-01

    Little attention has been paid to the toxicity of silver amalgam fillings, which have been used over the centuries in Dentistry. Amalgam particles may accidentally and/or traumatically be embedded into the submucosal tissue during placement of a restoration and perpetuate in such area. This article presents a case of amalgam tattoo and investigates whether it is related to the patient's repeated episodes of sinusitis. The patient was a 46-year-old woman with a 2 mm diameter radiopaque lesion ...

  11. Penetration of amalgam constituents into dentine

    OpenAIRE

    Scholtanus, J D; Özcan, M; Huysmans, M C D N J M

    2009-01-01

    OBJECTIVES: Amalgam restorations are replaced by adhesively placed composite resin restorations at an increasing rate. After the removal of amalgam dentine often shows marked dark discoloration that is attributed to the penetration of corrosion products from overlying amalgams. It is questioned whether penetration of metals into dentine affects the dentine as a substrate for adhesive procedures. This study has been performed to clarify the origin of dark discoloration of dentine by metals fro...

  12. Side effects of mercury in dental amalgam

    Directory of Open Access Journals (Sweden)

    Titiek Berniyanti

    2008-03-01

    Full Text Available Dental amalgam is an alloy composed of mixture of approximately equal parts of elemental liquid mercury and an alloy powder. The popularity of amalgam arises from excellent long term performance, ease of use and low cost. Despite the popularity of dental amalgam as restorative material, there have been concerns regarding the potential adverse health and environmental effects arising from exposure to mercury in amalgam. They have long been believed to be of little significance as contributors to the overall body burden of mercury, because the elemental form of mercury is rapidly consumed in the setting reaction of the restoration. In 1997, 80% of dentist in Indonesia still using amalgam as an alternative material, and 60% of them treat the rest of unused amalgam carelessly. In recent years, the possible environmental and health impact caused by certain routines in dental practice has attracted attention among regulators. As part of point source reduction strategies, the discharge of mercury/amalgam-contaminated wastes has been regulated in a number of countries, even though it has been documented that by adopting appropriate mercury hygiene measures, the impact of amalgam use in dentistry is minimal. The purpose of this paper is to examine on studies that relate mercury levels in human to the presence of dental amalgams. It is concluded that even though mercury used in filling is hazardous, if normal occupational recommendations for proper mercury hygiene routines and source of reduction strategies are followed, no occupational health risk can be assumed.

  13. A retrospective clinical study on longevity of posterior composite and amalgam restorations.

    Science.gov (United States)

    Opdam, Niek J M; Bronkhorst, Ewald M; Roeters, Joost M; Loomans, Bas A C

    2007-01-01

    The purpose of this study was to evaluate retrospectively the longevity of class I and II amalgam and composite resin restorations placed in a general practice. Patient records of a general practice were used for collecting the data for this study. From the files longevity and reasons for failure of 2867 class I and II amalgam and composite resin restorations placed in 621 patients by two operators between 1990 and 1997 were recorded in 2002. 912 amalgam restorations (502 by operator 1 and 410 by operator 2) and 1955 posterior composite resin restorations (1470 by operator 1 and 485 by operator 2) were placed. One hundred and eighty-two amalgam and 259 posterior composite resin restorations failed during the observation period. The main reasons for failure of the restorations were caries (34%), endodontic treatment (12%) and fracture of the tooth (13%). Life tables calculated from the data reveal a survival for composite resin of 91.7% at 5 years and 82.2% at 10 years. For amalgam the survival is 89.6% at 5 years and 79.2% at 10 years. Cox-regression analysis resulted in a significant effect of the amount of restored surfaces on the survival of the restorations. No significant effect of operator, material as well as combination of material and operator was found. In the investigated general practice, two dentists obtained comparable longevity for amalgam and composite resin restorations.

  14. Evaluation and comparison of the microleakage of cinaaly amalgam

    OpenAIRE

    K. Khosravi; P. Bahrami Esfarjani

    1994-01-01

    The microleakage of Cinaally amalgam, manufactured by Dr Faghihi Co. which is a high copper alloy and fine-cut amalgam was evaluated by radioisotope agents. The microleakage of cinaally amalgam was compared with Sybraloy amalgam, manufactured by Sybron/Kerr Co. which is a high copper alloy and spherical shape amalgam and is known as a standard amalgam alloy. The results showed that there is no statistically significant difference between microleakage of them after 24 hours, one month and two ...

  15. The environmental effects of dental amalgam.

    Science.gov (United States)

    Chin, G; Chong, J; Kluczewska, A; Lau, A; Gorjy, S; Tennant, M

    2000-12-01

    Dental amalgam is one of the most commonly used materials in restorative dentistry. However, one of its major components, mercury, is of particular concern due to its potential adverse effects on humans and the environment. In this review, the environmental impact of dental amalgam will be discussed, with particular reference to the effects attributed to its mercury component. Mercury commonly occurs in nature as sulfides and in a number of minerals. Globally, between 20,000-30,000 tons of mercury are discharged into the environment each year as a result of human activities. According to a recent German report, approximately 46 per cent of the freshly triturated amalgam is inserted as new amalgam restorations and the rest is waste. Depending on the presence of an amalgam separating unit, some of the generated amalgam-contaminated sludge is discharged into the sewage system. Lost or extracted teeth with amalgam fillings and amalgam-contaminated waste, such as trituration capsules and cotton rolls are discharged with the solid waste and, in most instances, are incinerated. Use of disinfectants containing oxidizing substances in dental aspirator kits may contribute to remobilization of mercury and its subsequent release into the environment. Nevertheless, dental mercury contamination is only a small proportion of terrestrial mercury (3-4 per cent), which is quite insignificant compared with industrial pollution and combustion of fossil fuels by vehicles. The environmental impact of dental mercury is mainly due to the poor management of dental amalgam waste. Proper collection of mercury-contaminated solid waste prevents the release of mercury vapour during combustion. In addition, the use of amalgam separating devices reduces the amount of amalgam-contaminated water released from dental clinics.

  16. Bonding glass to metal with plastic for stability over temperature: II

    Science.gov (United States)

    Willis, Chris L.; Petrie, Stephen P.

    2002-09-01

    To enable the invention of new optical instruments subjected to a broad range of operating conditions, there is a need to develop improved technology to hold small mirrors and other optical elements with high dimensional stability and low cost. A previous paper described a screening experiment on small face bonded mirrors subjected to an environment of -41 to +70 degree(s)C with the intent of finding factors that influence the bond joint's contribution to angular stability. This paper describes part of the continuing experiment, specifically addressing BK-7 mirrors bonded to Aluminum mounts with a flexible adhesive. The resulting tilt errors in the mirror assemblies were measured, and showed a definite pattern with respect to bond thickness. Flexible bonds between these two CTE mismatched materials did not fail, and exhibited high stability over temperature at 0.002-inch bond thickness.

  17. Dental Amalgam Exposure and Urinary Mercury Levels in Children: The New England Children’s Amalgam Trial

    OpenAIRE

    Maserejian, Nancy Nairi; Trachtenberg, Felicia L.; Assmann, Susan F.; Barregard, Lars

    2007-01-01

    Background Urinary mercury (U-Hg) excretion is a commonly used biomarker for mercury exposure from dental amalgam restorations. Objectives Our goal was to determine the most efficient measure of dental amalgam exposure for use in analyses concerning U-Hg in children. Methods We analyzed time-sensitive longitudinal amalgam exposure data in children randomized to amalgam restorations (n = 267) during the 5-year New England Children’s Amalgam Trial. We calculated 8 measures of amalgam, evaluatin...

  18. Advanced Thermal Protection Systems (ATPS), Aerospace Grade Carbon Bonded Carbon Fiber Material, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Carbon bonded carbon fiber (CBCF) insulating material is the basis for several highly successful NASA developed thermal protection systems (TPS). Included among...

  19. Dental amalgam and psychosocial status: the New England Children's Amalgam Trial.

    Science.gov (United States)

    Bellinger, D C; Trachtenberg, F; Zhang, A; Tavares, M; Daniel, D; McKinlay, S

    2008-05-01

    High-dose exposures to elemental mercury vapor cause emotional dysfunction, but it is uncertain whether the levels of exposure that result from having dental amalgam restorations do so. As part of the New England Children's Amalgam Trial, a randomized trial involving 6- to 10-year-old children, we evaluated the hypothesis that restoration of caries using dental amalgam resulted in worse psychosocial outcomes than restoration using mercury-free composite resin. The primary outcome was the parent-completed Child Behavior Checklist. The secondary outcome was children's self-reports using the Behavior Assessment System for Children. Children's psychosocial status was evaluated in relation to three indices of mercury exposure: treatment assignment, surface-years of amalgam, and urinary mercury excretion. All significant associations favored the amalgam group. No evidence was found that exposure to mercury from dental amalgams was associated with adverse psychosocial outcomes over the five-year period following initial placement of amalgams.

  20. Dental Amalgam-Civa Toksisitesi

    OpenAIRE

    Tatlı, Esra Ceren; Yavuz Avşar, Ayşe Filiz

    2016-01-01

    Dental amalgam diş hekimliğinde sıklıkla kullanılan bir restorasyon materyalidir. Son yıllarda içeriğindeki civa sebebiyle sıklıkla çeşitli nörolojik hastalıklar ile ilişkilendirilmektedir. Bu tartışmanın amacı konuyla ilgisi olabileceği düşünülen hastalıkların değerlendirilmesidir.

  1. High Copper Amalgam Alloys in Dentistry

    Directory of Open Access Journals (Sweden)

    Gaurav Solanki

    2012-07-01

    Full Text Available Amalgam Restoration is an example of the material giving its name to the process. Amalgam fillings are made up of mercury, powdered silver and tin. They are mixed and packed into cavities in teeth where it hardens slowly and replaces the missing tooth substance. The high copper have become material of choice as compared to low copper alloys nowadays because of their improved mechanical properties, corrosion resistance, better marginal integrity and improved performance in clinical trial. The high copper amalgam was used as a restorative material. The application of high copper amalgam was found to be much more useful than low copper amalgam. High copper had much more strength, corrosion resistance, durability and resistance to tarnish as compared to low copper amalgams. No marked expansion or condensation was noted in the amalgam restoration after its setting after 24 hrs. By using the high copper alloy, the chances of creep were also minimized in the restored tooth. No discomfort or any kind of odd sensation in the tooth was noted after few days of amalgam restoration in the tooth.

  2. Dynamic mechanical properties of dental amalgams.

    Science.gov (United States)

    Chern Lin, J H; Greener, E H; Hanawa, T; Okabe, T

    1990-01-01

    The dynamic mechanical properties of two high-copper amalgams (Tytin and Dispersalloy) and two traditional amalgams (Aristalloy and Aristalloy with Zn) were measured over a temperature range of 0-70 degrees C and at frequencies of 0.1, 1, and 10 Hz by means of a DuPont DMA. Values of storage modulus (E') for the amalgams were equivalent to the Young's modulus (E) measured from static mechanical test methods, with Dispersalloy demonstrating the highest moduli. Values of E' decreased with increased temperature. E' of traditional amalgams decreased more rapidly than did those of the Cu-rich amalgams. Values of loss modulus (E") for Tytin were smaller than those of Dispersalloy and the two types of Aristalloy. High values of E" for the traditional amalgams correspond to a greater viscous behavior. Marked differences between the magnitude of tan delta and its temperature coefficients for traditional and high-copper amalgams were observed, which is indicative of differences in visco-elastic behavior between these two amalgam systems.

  3. Elimination of mercury from amalgam in rats

    Energy Technology Data Exchange (ETDEWEB)

    Galic, N. [Dept. of Dental Pathology, School of Dentistry, Zagreb (Croatia); Prpic-Mehicic, G.; Prester, Lj.; Blanusa, M. [Inst. for Medical Research and Occupational Health, Zagreb (Croatia); Krnic, Z.; Erceg, D. [Pliva Pharmaceutical Co., Biomedicine Research Inst. ' ' Pliva' ' , Zagreb (Croatia)

    2001-07-01

    The aim of this study was to measure the urinary mercury excretion in rats exposed to amalgam over a two months period. Animals were either exposed to mercury from 4 dental amalgams or fed the diet containing powdered amalgams. The results showed significantly higher mercury amount in urine of both exposed groups than in control. Even two months after the amalgam had been placed in rats teeth, the amount of mercury in the urine remained 4-5 times higher than in control, and 4 times higher than in rats exposed to diet containing powdered amalgam. The elevated urinary Hg amount was accompanied by an increased level of total protein in urine. In the same exposure period the excretion of total protein in urine of rats with amalgam fillings was 2 times higher than in control and 1.5 times higher than in rats exposed to amalgam through diet. Concentrations of mercury in the sera of all groups were below the detection limit of the method. The results show that amount of mercury and protein in the urine of rats were related to the mercury release from dental amalgam. (orig.)

  4. Comparative study of the shear bond strength of various veneering materials on grade II commercially pure titanium.

    Science.gov (United States)

    Lee, Eun-Young; Jun, Sul-Gi; Wright, Robert F; Park, Eun-Jin

    2015-02-01

    To compare the shear bond strength of various veneering materials to grade II commercially pure titanium (CP-Ti). Thirty specimens of CP-Ti disc with 9 mm diameter and 10 mm height were divided into three experimental groups. Each group was bonded to heat-polymerized acrylic resin (Lucitone 199), porcelain (Triceram), and indirect composite (Sinfony) with 7 mm diameter and 2 mm height. For the control group (n=10), Lucitone 199 were applied on type IV gold alloy castings. All samples were thermocycled for 5000 cycles in 5-55℃ water. The maximum shear bond strength (MPa) was measured with a Universal Testing Machine. After the shear bond strength test, the failure mode was assessed with an optic microscope and a scanning electron microscope. Statistical analysis was carried out with a Kruskal-Wallis Test and Mann-Whitney Test. The mean shear bond strength and standard deviations for experimental groups were as follows: Ti-Lucitone 199 (12.11 ± 4.44 MPa); Ti-Triceram (11.09 ± 1.66 MPa); Ti-Sinfony (4.32 ± 0.64 MPa). All of these experimental groups showed lower shear bond strength than the control group (16.14 ± 1.89 MPa). However, there was no statistically significant difference between the Ti-Lucitone 199 group and the control group, and the Ti-Lucitone 199 group and the Ti-Triceram group. Most of the failure patterns in all experimental groups were adhesive failures. The shear bond strength of veneering materials such as heat-polymerized acrylic resin, porcelain, and indirect composite to CP-Ti was compatible to that of heatpolymerized acrylic resin to cast gold alloy.

  5. An in vitro quantitative antibacterial analysis of amalgam and composite resins.

    Science.gov (United States)

    Beyth, Nurit; Domb, Abraham J; Weiss, Ervin I

    2007-03-01

    Antibacterial properties of restorative dental materials such as amalgam and composite resins may improve the restorative treatment outcome. This study evaluates the antibacterial properties of three composite resins: Z250, Tetric Ceram, P60 and a dental amalgam in vitro. Streptococcus mutans and Actinomyces viscosus served as test microorganisms. Three quantitative microtiter spectrophotometric assays were used to evaluate the effect of the restorative materials on: (i) early-stage biofilm using a direct contact test (DCT); (ii) planktonic bacterial growth; (iii) bacterial growth in the materials' elute. For comparison purposes, agar diffusion test (ADT) was also performed. The effect of the composite resins on bacterial growth was minimal and limited to a few days only. One-week-aged composites promoted growth of S. mutans and A. viscosus. The antibacterial properties in direct contact were more potent than in planktonic bacterial growth. Amalgam showed complete inhibition of both bacteria in all phases, and the effect lasted for at least 1 week. The materials' elute had no effect on both bacterial growth with the exception of complete inhibition of S. mutans in amalgam. The later results correlated with the ADT. The present findings demonstrate potent and lasting antibacterial properties of amalgam, which are lacking in composite resins. This may explain the clinical observation of biofilm accumulated more on composites compared to amalgams. It follows that the assessment of antibacterial properties of poorly-soluble materials has to employ more than one assay.

  6. 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

  7. Effect of adhesive cements on reduction of microleakage at the amalgam/composite-resin interface

    Directory of Open Access Journals (Sweden)

    Khoroushi M

    2007-05-01

    Full Text Available Background and Aim: Patients always complain about metallic color of amalgam restorations. Covering amalgam by composite can solve this problem. Since polymerization shrinkage is a serious shortcoming in composites, application of the combined amalgam and composite restoration is one of the methods to reduce leakage in the cervical margins of posterior restorations. The aim of this invitro study was to evaluate the microleakage of amalgam/composite interface when Rely-X ARC adhesive resin cement was used in the joint. Materials and Methods: Twenty-four sound extracted premolars were chosen. Mesial and distal class II conventional cavities were prepared and the samples were divided into 4 groups of 12. In all groups, the bases of the cavities were restored with amalgam and then the remaining part was filled by composite resin. Specimens in groups 1 and 2 were restored with composite-resin, immediately after condensing amalgam without or with application of Rely-X ARC (3M, ESPE respectively. In groups 3 and 4, composite resin were applied 24 hours after condensation of amalgam, without or with application of Rely-X ARC respectively. After polishing and thermocycling, all specimens were prepared for dye penetration and the degree of leakage was scored and analyzed using Kruskall Wallis test with p<0.05 as the level of significance. Results: The frequency of dye penetration in different groups was obtained. The most and the least scores were observed in groups 3 and 4 respectively. No statistically significant difference was observed in different methods. Conclusion: None of the methods in this study could seal the amalgam/composite-resin interface.

  8. Hydrogen peroxide coordination to cobalt(II) facilitated by second-sphere hydrogen bonding

    Czech Academy of Sciences Publication Activity Database

    Wallen, C.M.; Palatinus, Lukáš; Bacsa, J.; Scarborough, C.C.

    2016-01-01

    Roč. 55, č. 39 (2016), s. 11902-11906 ISSN 0044-8249 Institutional support: RVO:68378271 Keywords : cobalt * hydrogen bonds * peroxides * peroxido ligands * second-sphere interactions Subject RIV: CC - Organic Chemistry

  9. Halogen bond preferences of thiocyanate ligand coordinated to Ru(II) via sulphur atom

    Science.gov (United States)

    Ding, Xin; Tuikka, Matti; Hirva, Pipsa; Haukka, Matti

    2017-09-01

    Halogen bonding between [Ru(bpy)(CO)2(S-SCN)2] (bpy = 2,2'-bipyridine), I2 was studied by co-crystallising the metal compound and diiodine from dichloromethane. The only observed crystalline product was found to be [Ru(bpy)(CO)2(S-SCN)2]ṡI2 with only one NCSṡṡṡI2 halogen bond between I2 and the metal coordinated S atom of one of the thiocyanate ligand. The dangling nitrogen atoms were not involved in halogen bonding. However, computational analysis suggests that there are no major energetic differences between the NCSṡṡṡI2 and SCNṡṡṡI2 bonding modes. The reason for the observed NCSṡṡṡI2 mode lies most probably in the more favourable packing effects rather than energetic preferences between NCSṡṡṡI2 and SCNṡṡṡI2 contacts.

  10. [Dental amalgams and mercury polemic in Abidjan].

    Science.gov (United States)

    Avoaka-Boni, M-C; Adou-Assoumou, N M; Sinan, A A; Abouattier-Mansilla, E C

    2007-12-01

    Dental amalgam is metallic biomaterials which has raised a number of controversies in the past few years, because of mercury potential toxicity. Considering the significance of theses controversies, this study was carried out with a view to evaluating the behaviour of Abidjan-based practitioners with respect to dental amalgam. The contemplated objective is to determine the frequency in the use of dental amalgam, to identify the problems encountered using dental amalgam and to propose solutions for fighting mercury contamination. The results show that dental amalgam is used in 81.8% for posterior teeth restoration. The side effects mentioned are metallic taste, gingival tattoo, galvanic corrosion and tooth pain. This is why 21.8 % of practitioners believe that the controversy over dental amalgam has merits while 45.5% hold the contrary opinion because of lack of scientific arguments. However, considering the absence of means to treat amalgam waste, dentist practitioners and authorities have to get involved to fight against mercury contamination.

  11. Corrosion potential recovery of dental amalgam restorations following prophylaxis.

    Science.gov (United States)

    Sutow, Elliott J; Maillet, J Peggy; Maillet, Wayne A; Hall, Gordon C; Millar, Michele

    2007-07-01

    Dental amalgam restorations are subjected to abrasion during selective prophylaxis that can damage or remove the protective oxide and result in increased rates of corrosion and chemical dissolution of mercury. It was the objective of this research to study the corrosion potential change of dental amalgam restorations to obtain an indication of the time required for in vivo repassivation following prophylaxis. The corrosion potentials of 27 Class I and Class II amalgam restorations were measured pre- and post-prophylaxis using a high impedance voltmeter and a Ag/AgCl micro-reference electrode. Prophylaxis was performed for approximately 2s on each amalgam surface using a slow-speed handpiece with a rubber-cup and commercial abrasive paste. Subjects thoroughly rinsed before the post-prophylaxis corrosion potentials were measured. The data were analyzed using a confidence interval, a t-test and correlation analysis. The pre- and post-prophylaxis mean corrosion potentials were, respectively, -132 (27)mV and -126 (27)mV. The mean of the differences between the pre- and post-prophylaxis corrosion potentials was 6.1 (28)mV, with an associated 95% confidence interval of (-4.8, 17)mV. A t-test showed the mean absolute difference in corrosion potential was less than 50 mV (pamalgam restorations occurred by at most 10-44 min, indicating that the period of elevated corrosion rate and elevated chemical dissolution rate of mercury, due to oxide damage or removal, may be short-lived.

  12. Extensive amalgam tattoo on the alveolar-gingival mucosa.

    Science.gov (United States)

    Galletta, Vivian C; Artico, Gabriela; Dal Vechio, Aluana M C; Lemos, Celso A; Migliari, Dante A

    2011-01-01

    Amalgam tattoos are common exogenous pigmented lesions of the oral mucosa occurring mainly by inadvertent placement of amalgam particles into soft tissues. The diagnosis of amalgam tattoo is simple, usually based on clinical findings associated with presence or history of amalgam fillings removal. Intraoral X-rays may be helpful in detecting amalgam-related radiopacity. In cases where amalgam tattoo cannot be differentiated from other causes of oral pigmentation, a biopsy should be performed. This article deals with an extensive amalgam tattoo lesion which required a biopsy for a definitive diagnosis.

  13. Effect of Self-etch Adhesives on Self-sealing Ability of High-Copper Amalgams.

    Science.gov (United States)

    Moazzami, Saied Mostafa; Moosavi, Horieh; Moddaber, Maryam; Parvizi, Reza; Moayed, Mohamad Hadi; Mokhber, Nima; Meharry, Michael; B Kazemi, Reza

    2016-12-01

    Similar to conventional amalgam, high-copper amalgam alloy may also undergo corrosion, but it takes longer time for the resulting products to reduce microleakage by sealing the micro-gap at the tooth/amalgam interface. The aim of this study was to evaluate the effect of self-etch adhesives with different pH levels on the interfacial corrosion behavior of high-copper amalgam restoration and its induction potential for self-sealing ability of the micro-gap in the early hours after setting by means of Electro-Chemical Tests (ECTs). Thirty cylindrical cavities of 4.5mm x 4.7mm were prepared on intact bicuspids. The samples were divided into five main groups of application of Adhesive Resin (AR)/ liner/ None (No), on the cavity floor. The first main group was left without an AR/ liner (No). In the other main groups, the types of AR/ liner used were I-Bond (IB), Clearfil S 3 (S 3 ), Single Bond (SB) and Varnish (V). Each main group (n=6) was divided into two subgroups (n=3) according to the types of the amalgams used, either admixed ANA 2000 (ANA) or spherical Tytin (Tyt). The ECTs, Open Circuit Potential (OCP), and the Linear Polarization Resistance (LPR) for each sample were performed and measured 48 hours after the completion of the samples. The Tyt-No and Tyt-IB samples showed the highest and lowest OCP values respectively. In LPR tests, the Rp values of ANA-V and Tyt-V were the highest (lowest corrosion rate) and contrarily, the ANA-IB and Tyt-IB samples, with the lowest pH levels, represented the lowest Rp values (highest corrosion rates). Some self-etch adhesives may increase interfacial corrosion potential and self-sealing ability of high-copper amalgams.

  14. Retrograde root filling with amalgam and Cavit.

    Science.gov (United States)

    Finne, K; Nord, P G; Persson, G; Lennartsson, B

    1977-04-01

    In a 3-year review of 218 teeth with retrograde root filling with amalgam orCavit, the results obtained with the former proved significantly better than those obtained with the latter. The difference seemed to be due to a better obliteration of the canal by amalgam. The obliterating effect of amalgam probably eliminates the need for revision of incomplete othograde root filling, for example, in cases with a post in the root canal. Irrespective of type of filling materials, the results were less good in cases with marginal bone loss.

  15. Dental Amalgam and Psychosocial Status: The New England Children’s Amalgam Trial

    OpenAIRE

    Bellinger, D.C.; Trachtenberg, F.; Zhang, A.; Tavares, M.; Daniel, D.; McKinlay, S.

    2008-01-01

    High-dose exposures to elemental mercury vapor cause emotional dysfunction, but it is uncertain whether the levels of exposure that result from having dental amalgam restorations do so. As part of the New England Children’s Amalgam Trial, a randomized trial involving 6- to 10-year-old children, we evaluated the hypothesis that restoration of caries using dental amalgam resulted in worse psychosocial outcomes than restoration using mercury-free composite resin. The primary outcome was the pare...

  16. Long-lived, high-strength states of ICAM-1 bonds to beta2 integrin, II

    DEFF Research Database (Denmark)

    Kinoshita, Koji; Leung, Andrew; Simon, Scott

    2010-01-01

    Using single-molecule force spectroscopy to probe ICAM-1 interactions with recombinant alphaLbeta2 immobilized on microspheres and beta2 integrin on neutrophils, we quantified an impressive hierarchy of long-lived, high-strength states of the integrin bond, which start from basal levels with acti......Using single-molecule force spectroscopy to probe ICAM-1 interactions with recombinant alphaLbeta2 immobilized on microspheres and beta2 integrin on neutrophils, we quantified an impressive hierarchy of long-lived, high-strength states of the integrin bond, which start from basal levels......-out and outside-in signaling in neutrophils on the lifetimes and mechanical strengths of ICAM-1 bonds to beta2 integrin on the cell surface. Even though ICAM-1 bonds to recombinant alphaLbeta2 on microspheres in Mg2+ or Mn2+ can live for long periods of time under slow pulling, here we show that stimulation...... of neutrophils in Mg2+ plus the chemokine IL-8 (i.e., inside-out signaling) induces several-hundred-fold longer lifetimes for ICAM-1 attachments to LFA-1, creating strong bonds at very slow pulling speeds where none are perceived in Mg2+ or Mn2+ alone. Similar changes are observed with outside-in signaling, i...

  17. Oral leukoplakia associated with amalgam restorations.

    Science.gov (United States)

    Gönen, Zeynep B; Yılmaz Asan, Canay; Etöz, Osman; Alkan, Alper

    2016-01-01

    The World Health Organization has defined oral leukoplakia (OL) as "a white patch or plaque of the oral mucosa that cannot be characterized clinically or pathologically as any other disease". A 21-year-old male with OL presented with a bilateral burning sensation in the buccal mucosa. The patient had amalgam restorations, and an epicutaneous patch test indicated a positive response to amalgam. The amalgam restorations were therefore removed and the cavities were refilled with a composite resin restorative material. During 5 years of follow-up, there was no recurrence of the oral lesions. This case illustrates that amalgam fillings may cause OL lesions. (J Oral Sci 58, 445-448, 2016).

  18. Clinical Evaluation of Reasons for Replacement of Amalgam Restorations in Patients Referring to a Dental School in Iran

    Directory of Open Access Journals (Sweden)

    Firoz Pouralibaba

    2010-06-01

    Full Text Available Background and aims. The present study evaluated the most common reasons for replacing amalgam restorations in a university clinic. Materials and methods. A total of 217 restorations which needed to be replaced were clinically and radiographically evaluated in a period of 4 months. The frequencies of reasons for replacing amalgam restorations were calculated: The assessed items included recurrent caries, tooth structure fracture (functional or non-functional cusps, amalgam bulk fracture, amalgam marginal fracture, proximal overhangs, and esthetics. Data were analyzed using Fischer’s exact test. Results. Both in vital teeth and teeth which had undergone root canal therapy, the most common reason for amalgam replacement was cusp fracture, with the fracture of non-functional cusps being statistically significant. Recurrent caries was the second most common reason for amalgam replacement. In Class I restorations, the most common reasons were recurrent caries and esthetics, with no statistical significance. The most frequent problem in Class II restorations was fracture of nonfunctional cusps, with a statistical significance in three-surface restorations. Conclusion. According to the results, failing to reduce undermined cusps and neglectful caries removal are the reasons for majority of amalgam restoration replacements. These issues should be emphasized in the curriculum for dental students and continuing education courses.

  19. Intramolecular Fe(II)-Catalyzed N–O or N–N Bond Formation from Aryl Azides

    Science.gov (United States)

    Stokes, Benjamin J.; Vogel, Carl V.; Urnezis, Linda K.; Pan, Minjie; Driver, Tom G.

    2010-01-01

    Iron(II) bromide catalyzes the transformation of aryl- and vinyl azides with ketone- or methyl oxime substituents into 2,1-benzisoxazoles, indazoles or pyrazoles through the formation of an N–O or N–N bond. This transformation tolerates a variety of different functional groups to facilitate access to a range of benzisoxazoles or indazoles. The unreactivity of the Z-methyloxime indicates that N-heterocycle formation occurs through a nucleophilic attack of the ketone or oxime onto an activated planar iron azide complex. PMID:20507088

  20. Passivation of dental amalgams and mercury release.

    Science.gov (United States)

    Joska, Ludĕk; Marek, Miroslav

    2004-01-01

    In this study the rate of dissolution of mercury from two dental amalgams with different compositions and structures was determined in vitro under different oxidation and abrasion conditions, and the results were correlated with the electrochemical characteristics. A spherical high copper and a lathe-cut very high-copper amalgam were tested in aerated and deaerated artificial saliva. The electrochemical characteristics were determined by potential-time, anodic polarization, polarization resistance and cathodic stripping measurements. Mercury release tests were performed after either stabilization in the solution, or abrasion using SiC papers or rotary toothbrush, with or without toothpaste. Dissolved mercury was determined by atomic absorption spectrophotometry. Both amalgams exhibited passivation, the amalgam with the higher copper content passivating spontaneously even when the oxygen content in the solution was minimized. At a higher oxygen content in the solution the rate of mercury release from the amalgams was lower than when the oxygen content was minimized, and decreased further after a pre-exposure. Brushing generally increased the release. The results show the importance of the oxidation conditions and passivation characteristics of dental amalgams for mercury release, especially in the transient state after abrasion by chewing or tooth brushing.

  1. Corrosion of amalgams under sliding wear.

    Science.gov (United States)

    Lian, K; Meletis, E I

    1996-05-01

    During mastication, dental amalgams are simultaneously subjected to corrosion by the oral environment and to a sliding-wear process by biting forces. In the present study, the effect of sliding wear on the corrosion behavior of two high-copper dental amalgams was investigated. An experimental apparatus was utilized that allows electrochemical testing under sliding-wear conditions. Corrosion potential measurements and anodic polarization scans were conducted in 0.1 M NaCl solution under sliding wear to characterize the behavior of two commercial, high-copper, single composition dental amalgams. In addition, long duration tests were conducted to assess possible corrosion and wear synergistic effects. The results showed that sliding wear caused a sharp reduction in the corrosion potential, a significant increase in the corrosion rate and a decrease in the repassivation rate of both amalgams. These effects are due to the mechanical removal by the wear process of the surface protective film formed on dental amalgams. The simultaneous action of sliding wear and corrosion can also induce embrittlement that leads to cracking. The present evidence suggests that this cracking may be one of the major contributors to marginal failures of dental amalgam restorations.

  2. Bonding and Emotional Reeducation of Couples in the PAIRS Training: Part II.

    Science.gov (United States)

    Durana, Carlos

    1996-01-01

    Uses quantitative and qualitative research methods to evaluate the impact of the bonding and catharsis segment of a measure of intimate relationship skills. Results suggest that the segment can lead to significant improvements in marital adjustment, cohesion, self-esteem, and anxiety levels. Explores differences in changes for males and females.…

  3. Relationship between percentage of regulatory T-cells and dental amalgam fillings.

    Directory of Open Access Journals (Sweden)

    Fahad Khaliq

    2016-06-01

    Full Text Available Introduction: Regulatory T-cells are the main component of peripheral tolerance and their level is decreased in autoimmunity. In dental amalgam, a mixture of metals is used as a restorative material. During daily a ctivities, these metals are ingested and affect renal, neurosensory and immune systems. Studies have demonstrated an increased risk of autoimmune diseases in patients with dental amalgam fillings. It was hypothesized that the percentage of regulatory T-cells decreases in individuals with amalgam fillings. Therefore this study was designed to determine and compare the percentage of regulatory T-cells in individuals with and without amalgam fillings. Material and Methods: This was a cross-sectional study. Subjects were divided into two groups with each group consisting of 40 individuals. Group I (study group comprised individuals with amalgam fillings, and Group II (control group, individuals without amalgam fillings in their teeth. Blood samples of all the participants were collected and tagged with CD4‑FITC, CD25‑PE and CD127‑PerCP-Cy monoclonal antibodies for the detection of regulatory T-cells, FACSCalibur was used for this purpose. Results: The percentage of regulatory T-cells in the control group was high (77.77±5.54% compared to the study group (76.09±7.68%, however, on comparison, the difference was not statistically significant (p=0.25. Conclusion: Dental amalgam fillings did not show a declining effect on the percentage of regulatory T-cells.

  4. The effect of surface treatment and position of the dental restoration on amalgam corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Mortazavi, V. [Isfahan Univ. of Medical Sciences, Faculty of Dentistry, Isfahan (Iran, Islamic Republic of); Fathi, M.H. [Isfahan Univ. of Technology, Materials Engineering Dept., Isfahan (Iran, Islamic Republic of)

    2003-07-01

    The aim of this research was to evaluate the effect of surface treatment, clinical operations and the condition and position of the dental restoration on amalgam corrosion behavior. Commercial amalgam alloy namely Oralloy was selected. Twenty-one amalgam samples were prepared. After triturating and condensation, the samples were divided into three groups and each group was finished by using one of three surface clinical procedures; carving, carving-burnishing, carving-burnishing-polishing. A special cylindrical mold was used in order to simulation of the interproximal areas and proximal surfaces of the dental restorations. Stainless steel matrix band was laid on the internal mold surfaces and amalgam paste was compacted in the mold. Electrochemical potentiodynamic tests were performed at a temperature of 37{+-}1 {sup o}C in physiological solution in order to determine and compare the corrosion behavior of dental amalgam samples, as an indication of biocompatibility. The results showed statistically significant differences between the mean corrosion current density values of three different groups of dental amalgam (P<0.05). The polished group possesses the lowest and the carved group shows the highest corrosion current density. The carved group shows more corrosion resistance in compare with the sample near the matrix band as an index of the proximal surfaces of restorations. It was concluded that even a simple clinical operation could effect on dental amalgam corrosion resistance. The proximal surfaces of the class II restorations are not only susceptible to concentration cell corrosion but also possess less corrosion resistance because dentist could perform no clinical surface treatment. (author)

  5. A retrospective clinical study on longevity of posterior composite and amalgam restorations.

    NARCIS (Netherlands)

    Opdam, N.J.M.; Bronkhorst, E.M.; Roeters, F.J.M.; Loomans, B.A.C.

    2007-01-01

    OBJECTIVES: The purpose of this study was to evaluate retrospectively the longevity of class I and II amalgam and composite resin restorations placed in a general practice. METHODS: Patient records of a general practice were used for collecting the data for this study. From the files longevity and

  6. Insertion of molecular oxygen into a palladium(II) methyl bond: a radical chain mechanism involving palladium(III) intermediates.

    Science.gov (United States)

    Boisvert, Luc; Denney, Melanie C; Hanson, Susan Kloek; Goldberg, Karen I

    2009-11-04

    The reaction of (bipy)PdMe(2) (1) (bipy = 2,2'-bipyridine) with molecular oxygen results in the formation of the palladium(II) methylperoxide complex (bipy)PdMe(OOMe) (2). The identity of the product 2 has been confirmed by independent synthesis. Results of kinetic studies of this unprecedented oxygen insertion reaction into a palladium alkyl bond support the involvement of a radical chain mechanism. Reproducible rates, attained in the presence of the radical initiator 2,2'-azobis(2-methylpropionitrile) (AIBN), reveal that the reaction is overall first-order (one-half-order in both [1] and [AIBN], and zero-order in [O(2)]). The unusual rate law (half-order in [1]) implies that the reaction proceeds by a mechanism that differs significantly from those for organic autoxidations and for the recently reported examples of insertion of O(2) into Pd(II) hydride bonds. The mechanism for the autoxidation of 1 is more closely related to that found for the autoxidation of main group and early transition metal alkyl complexes. Notably, the chain propagation is proposed to proceed via a stepwise associative homolytic substitution at the Pd center of 1 with formation of a pentacoordinate Pd(III) intermediate.

  7. Defective amalgams - repair or replace?

    Science.gov (United States)

    Levenson, David; Keenan, Analia V

    2010-01-01

    Cochrane Oral Health Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, ISI Web of Science, ISI Web of Science Conference Proceedings, BIOSIS, OpenSIGLE. Reference lists of all eligible trials and review articles, and their reference lists were searched. Trials were selected if they met the following criteria: randomised or quasi-randomised controlled trial, involving replacement and repair of amalgam restorations. Titles and abstracts were assessed independently by two authors. Full papers were obtained for relevant articles. Data synthesis was to follow Cochrane Collaboration statistical guidelines. 145 potentially eligible studies were identified. Only three studies were analysed further but none of these met the inclusion criteria and all were excluded from this review. There are no published randomised controlled clinical trials (RCTs) relevant to this review question. There is a need for methodologically sound RCTs reported according to the Consolidated Standards of Reporting Trials (CONSORT) statement (www.consort-statement.org/). Further research needs to explore qualitatively the views of patients on repairing versus replacement and investigate themes around pain, distress and anxiety, time and costs.

  8. Intra-/Intermolecular Bifurcated Chalcogen Bonding in Crystal Structure of Thiazole/Thiadiazole Derived Binuclear (DiaminocarbenePdII Complexes

    Directory of Open Access Journals (Sweden)

    Alexander S. Mikherdov

    2018-02-01

    Full Text Available The coupling of cis-[PdCl2(CNXyl2] (Xyl = 2,6-Me2C6H3 with 4-phenylthiazol-2-amine in molar ratio 2:3 at RT in CH2Cl2 leads to binuclear (diaminocarbenePdII complex 3c. The complex was characterized by HRESI+-MS, 1H NMR spectroscopy, and its structure was elucidated by single-crystal XRD. Inspection of the XRD data for 3c and for three relevant earlier obtained thiazole/thiadiazole derived binuclear diaminocarbene complexes (3a EYOVIZ; 3b: EYOWAS; 3d: EYOVOF suggests that the structures of all these species exhibit intra-/intermolecular bifurcated chalcogen bonding (BCB. The obtained data indicate the presence of intramolecular S•••Cl chalcogen bonds in all of the structures, whereas varying of substituent in the 4th and 5th positions of the thiazaheterocyclic fragment leads to changes of the intermolecular chalcogen bonding type, viz. S•••π in 3a,b, S•••S in 3c, and S•••O in 3d. At the same time, the change of heterocyclic system (from 1,3-thiazole to 1,3,4-thiadiazole does not affect the pattern of non-covalent interactions. Presence of such intermolecular chalcogen bonding leads to the formation of one-dimensional (1D polymeric chains (for 3a,b, dimeric associates (for 3c, or the fixation of an acetone molecule in the hollow between two diaminocarbene complexes (for 3d in the solid state. The Hirshfeld surface analysis for the studied X-ray structures estimated the contributions of intermolecular chalcogen bonds in crystal packing of 3a–d: S•••π (3a: 2.4%; 3b: 2.4%, S•••S (3c: less 1%, S•••O (3d: less 1%. The additionally performed DFT calculations, followed by the topological analysis of the electron density distribution within the framework of Bader’s theory (AIM method, confirm the presence of intra-/intermolecular BCB S•••Cl/S•••S in dimer of 3c taken as a model system (solid state geometry. The AIM analysis demonstrates the presence of appropriate bond critical points for these

  9. Evaluation and comparison of the microleakage of cinaaly amalgam

    Directory of Open Access Journals (Sweden)

    K. Khosravi

    1994-07-01

    Full Text Available The microleakage of Cinaally amalgam, manufactured by Dr Faghihi Co. which is a high copper alloy and fine-cut amalgam was evaluated by radioisotope agents. The microleakage of cinaally amalgam was compared with Sybraloy amalgam, manufactured by Sybron/Kerr Co. which is a high copper alloy and spherical shape amalgam and is known as a standard amalgam alloy. The results showed that there is no statistically significant difference between microleakage of them after 24 hours, one month and two months.

  10. A quantitative analysis of the ν ??? (IR) bands of H-bonds. II. Adipic acid crystals

    Science.gov (United States)

    Marechal, Y.

    1983-08-01

    The theory described in the preceding article is applied to the ν ??? bands (X-H¯???Y) of adipic (H and D) acid monocrystals. The lineshape g(ω) that ν ??? is supposed to exhibit in the absence of Fermi resonances is computed at temperatures ranging from 10 to 300 K. This lineshape has at least two components in the case of H-adipic acid which we preferentially attribute to the ν ???-ν ??? interaction (= 100 cm -1) between the two H-bonds of the cyclic dimers (RCOOH) 2. We cannot however exclude that these two components are due to a tunnelling of the protons through the H-bonds of these dinners. The precise determination of the second centered moments (or width) of g(ω) at various temperatures gives results which are consistent with the value of the first moment and can be simply accounted for with the assumption that the modulation of ν ??? by low-frequency modes is quadratic. The question as to whether this low-frequency mode is a stretching mode or a bending mode in an isolated H-bond remains unanswered.

  11. Perception of patients with amalgam fillings about toxicity of mercury in dental amalgam.

    Science.gov (United States)

    Bamise, C T; Oginni, Adeleke O; Adedigba, Michael A; Olagundoye, O O

    2012-05-01

    The objective of this study is to evaluate the awareness of patients with dental fillings about the toxicity of mercury in dental amalgam. Adult patients having at least one amalgam filling in their mouth were recruited in the Oral Diagnosis Department of OAUTHC, Ile-Ife Dental Hospital. Participants were recruited consecutively as they report in the clinic. Data were collected using a structured questionnaire developed based on standard questions from relevant publications. They were asked to indicate the type of filling material in their mouth, ingredients of the material, previous knowledge of mercury in dental amalgam and ailments due to mercury. They were to indicate their level of agreement with filling their cavities with dental amalgam despite prior information about its mercury content. There were about 446 respondents analyzed; male, 194 (43.5%); female 252 (56.5%). Six (1.4%) and 21 (4.7%) respondents were primary and secondary schools students respectively; 15(3.4%) had no formal education while about 410 (91.9%) were either undergraduate or graduate. All of them had at least one amalgam filling. 249 (55%) participants know the type of filling on their teeth; 156 (34.5%) had the knowledge of the presence of mercury in dental amalgam while 26.1% believed mercury can cause problems in human beings. About 90 (19.9%) participants claimed to have heard about adverse reactions to dental amalgams and 34 (7.5%) of them have heard about people recovering from an illness after removal of their filling. The level of agreement with filling their cavities with amalgam despite prior knowledge of its mercury content was 74% while 60% was observed for allowing just any material to be placed on their teeth. Awareness of toxicity of mercury in dental amalgam was slightly low among the respondents studied. This may be suggested to be a reflection of nonexistent of global amalgam controversy in Nigeria.

  12. Evidence summary: which dental liners under amalgam restorations are more effective in reducing postoperative sensitivity?

    Science.gov (United States)

    Nasser, Mona

    2011-06-10

    Since August 2009, members of the Primary Care Dentistry Research Forum (www.dentistryresearch.org) have taken part in an online vote to identify questions in day-to-day practice that they felt most needed to be answered with conclusive research. The question that receives the most votes each month forms the subject of a critical appraisal of the relevant literature. Each month a new round of voting takes place to decide which further questions will be reviewed. Dental practitioners and dental care professionals are encouraged to take part in the voting and submit their own questions to be included in the vote by joining the website. The paper below details a summary of the findings of the ninth critical appraisal. In order to address the question raised by dentistry research forum, first a search was conducted for systematic reviews on the topic. There was one systematic review retrieved comparing bonded amalgam restorations versus non-bonded amalgam restorations. However, there was no other systematic review identified assessing the effectiveness of dental liners under amalgam restorations in general. Therefore, a search was conducted for any randomised controlled trial (RCT) comparing use of a lining under amalgam restorations versus no lining or RCTs comparing differing lining materials under amalgam against each other. There were eight relevant RCTs identified. Due to the low quality, small sample sizes or lack of adequate reporting of the outcome data, the evidence is inadequate to claim or refute a difference in postoperative sensitivity between different dental liners. Further well-conducted RCTs are needed to answer this question. These RCTs would be preferably included and synthesised in a systematic review.

  13. Amalgam dental fillings and hearing loss.

    Science.gov (United States)

    Rothwell, Janet A; Boyd, Paul J

    2008-12-01

    In this study we investigated the effects of amalgam dental fillings on auditory thresholds. Participants (n=39) were non-smoking women age 40 to 45. Regression and correlation analyses were performed between auditory thresholds, measured from 0.25 to 16 kHz, and the number/surface area of dental fillings, using the ASHA criteria for ototoxic change as a reference for comparison. No significant correlation (p>0.05) was found between composite (non-amalgam) filling or drilling data and auditory thresholds. However, there was a significant positive linear correlation between amalgam filling data and auditory thresholds at 8, 11.2, 12.5, 14, and 16 kHz. The strongest association (r=0.587, n=39, pamalgam filling was associated with a 2.4 dB decline in hearing threshold (95% confidence interval [CI], 1.3-3.5 dB). The results suggest an association between more amalgam fillings and poorer thresholds at higher frequencies, which could contribute to presbyacusis in developed countries. This provides further argument for the use of amalgams to be phased out where suitable alternatives exist.

  14. The safety of dental amalgam in children.

    Science.gov (United States)

    Martin, Michael D; Woods, James S

    2006-11-01

    The safety of mercury-containing dental amalgam has been hotly debated for well over a century. Dental exposures from mercury have been suggested as the cause of numerous diseases including multiple sclerosis, autism and many others. Known health effects of mercury exposure include CNS and renal damage. However, these effects have only been shown at occupational or higher levels of exposure, and have not been conclusively shown to be present at levels of mercury exposure consistent with that from dental amalgam fillings. The use of mercury amalgam fillings remains a state-of-the-art treatment for dental caries throughout the world. Although there have been a small number of peer-reviewed reports examining the health effects of dental mercury in children, only very recently have the only randomised, controlled clinical trials (two) of the safety of mercury amalgam been published. The purpose of this review is to discuss the scientific evidence on the safety of the use of mercury-containing dental amalgam as a treatment for dental caries.

  15. Evidence for nonhydrogen bonded compound II in cyclic reaction of hemoglobin I from Lucina pectinata with hydrogen peroxide.

    Science.gov (United States)

    De Jesús-Bonilla, Walleska; Ramírez-Meléndez, Eunice; Cerda, José; López-Garriga, Juan

    2002-01-01

    Studies that elucidate the behavior of the hemoglobins (Hbs) and myoglobins upon reaction with hydrogen peroxide are essential to the development of oxygen carrier substitutes. Stopped-flow kinetics and resonance Raman data show that the reaction between hydrogen peroxide and oxygenated and deoxygenated ferric Hb I (oxy- and deoxy-HbI) from Lucina pectinata produce compound I and compound II ferryl species. The rate constants ratio (k23/k41) between the formation of compound II from compound I (k23) and the oxidation of the ferrous HbI (k41, i.e., 25 M(-1) s(-1)) of 12 x 10(-4) M suggests that HbI has a peroxidative capacity for removing H2O2 from solution. Resonance Raman presents the formation of both, met-aquo-HbI and compound II ferryl species in the cyclic reaction of HbI with H2O2. The ferric HbI species is maintained by the presence of H2O2; it can produce HbI compound I, or it can be reduced to a deoxy-HbI derivative to form HbI compound II upon reaction with H2O2. The compound II ferryl vibration frequency appears at 805 and 769 cm(-1) for HbIFe(IV)=(16)O and HbIFe(IV)=(18)O species, respectively. This ferryl mode indicates the absence of hydrogen bonding between the carbonyl group of the distal Q64 and the HbIFe(IV)=O ferryl moiety. The observation suggests that both the trans-ligand effect and the polarizabilty of the HbI heme pocket are responsible for the observed ferryl oxo vibrational energy. The vibrational mode also suggests that the carbonyl group of the distal Q64 is oriented toward the iron of the heme group, increasing the distal pocket electron density. Copyright 2002 Wiley Periodicals, Inc.

  16. Advancing Discontinuous Fiber-Reinforced Composites above Critical Length for Replacing Current Dental Composites and Amalgam.

    Science.gov (United States)

    Petersen, Richard C

    2017-02-01

    bond breakage is expected from greater interlaminar shearing as the PFC accentuates straining deflections compared to amalgam at the higher modulus tooth enamel margins during loading. Preliminary testing for experimental FRCs with fibers above L c demonstrated three-body wear even less than enamel to reduce the possibility of marginal ditching as a factor in secondary caries seen with both PFCs and amalgam. Further, FRC molding compounds with chopped fibers above L c properly impregnated with photocure resin can pack with condensing forces higher than the amalgam to eliminate voids in the proximal box commonly seen with dental PFCs and reestablish interproximal contacts better than amalgam. Subsequent higher FRC packing forces can aid in squeezing monomer, resin, particulate and nanofibers deeper into adhesive mechanical bond retention sites and then leave a higher concentration of insoluble fibers and particulate as moisture barriers at the cavity margins. Also, FRC molding compounds can incorporate triclosan antimicrobial and maintain a strong packing condensing force that cannot be accomplished with PFCs which form a sticky gluey consistency with triclosan. In addition, large FRC packing forces allow higher concentrations of the hydrophobic ethoxylated bis phenol A dimethacrylate (BisEMA) low-viscosity oligomer resin that reduces water sorption and solubility to then still maintain excellent consistency. Therefore, photocure molding compounds with fibers above L c appear to have many exceptional properties and design capabilities as improved alternatives for replacing both PFCs and amalgam alloys in restorative dental care.

  17. Dental Amalgam and Psychosocial Status: The New England Children’s Amalgam Trial

    Science.gov (United States)

    Bellinger, D.C.; Trachtenberg, F.; Zhang, A.; Tavares, M.; Daniel, D.; McKinlay, S.

    2009-01-01

    High-dose exposures to elemental mercury vapor cause emotional dysfunction, but it is uncertain whether the levels of exposure that result from having dental amalgam restorations do so. As part of the New England Children’s Amalgam Trial, a randomized trial involving 6- to 10-year-old children, we evaluated the hypothesis that restoration of caries using dental amalgam resulted in worse psychosocial outcomes than restoration using mercury-free composite resin. The primary outcome was the parent-completed Child Behavior Checklist. The secondary outcome was children’s self-reports using the Behavior Assessment System for Children. Children’s psychosocial status was evaluated in relation to three indices of mercury exposure: treatment assignment, surface-years of amalgam, and urinary mercury excretion. All significant associations favored the amalgam group. No evidence was found that exposure to mercury from dental amalgams was associated with adverse psychosocial outcomes over the five-year period following initial placement of amalgams. PMID:18434579

  18. Evaluating the Reasons of Amalgam Restoration Replacement in Esthetic and Restorative Department of Babol Dental School in 2013-14

    Directory of Open Access Journals (Sweden)

    F Abolghasemzade

    2015-08-01

    Results: Within 263 patients, there were 81(30.8% men and 182(69.2% women. Most patients aged 30-40(42.2%, and were reported to suffer from class Ι dental occlusion(92.4%.The mean DMF was 9.7±2.4 . Lower molars were demonstrated as the most frequent teeth group for replacing amalgam restorations as well as causing secondary caries. Furthermore, secondary caries involved the major causes of amalgam restoration replacement. The most prevalent class for amalgam restoration replacement was class II restorations. It should be noted that secondary caries were most prevalent within class II MO / DO(25 cases(44.6%. Conclusion: The study findings revealed that the most common cause of the restoration replacement involved the secondary caries which was most observed in the Class II restorations.

  19. Oral amalgam pigmentations (tattoos): a retrospective study.

    Science.gov (United States)

    Owens, B M; Johnson, W W; Schuman, N J

    1992-12-01

    Oral amalgam tattoos are typically asymptomatic, benign, solitary or multiple clinical lesions produced by inadvertent placement of dental silver amalgam restorative material into the oral soft tissues. Diffuse lesions often display a grayish brown discoloration while other tattoos present a darker blue-black contrast. One hundred sixty-eight biopsy reports that confirmed the diagnosis of amalgam tattoo were analyzed to find age, sex, and race of the patients and size, location, and duration of occurrence of the lesions. Among the 168 cases, 235 individual tissue specimens were identified. A majority of the specimens were taken from the buccal mucosa, gingiva, and alveolar mucosa. The most common site for the lesion was the mandibular arch. The size of the individual specimens ranged from 0.10 cm to 1.50 cm. Almost two thirds of the specimens were 0.40 cm or less.

  20. Dental amalgam implantation and thyroid autoimmunity.

    Science.gov (United States)

    Kisakol, G

    2014-01-01

    Mercury was heavily studied as a factor in the autoimmune processes. We aimed to observe whether mercury of amalgam is associated with Hashimoto disease. 363 patients with Hashimoto's thyroiditis and 365 control subjects were included in to the study. Amalgam fillings were checked by the physician. 363 (49.9 %) patients and 365 (50.1 %) healthy controls were included into the study. Hashimoto's thyroiditis was diagnosed with thyroid hormones, antithyroid antibody levels, and ultrasonographic findings. Control subjects were selected from patients with no known autoimmune diseases. They were controlled with ultrasonography, as well as antibody titers. None of them had Hashimoto's thyroiditis. Sex distribution of the study population was following: 319 (87.9 %) female, 44 (12.1 %) male in the patient group and 277 (75.9 %) male and 88 (24.1 %) female in healthy control subjects, respectively. Mean free T4 values for Hashimoto's thyroiditis and healthy control group were 15.30±0.76, 17.30±0.96 pmol/L and mean TSH values for Hashimoto's thyroiditis and healthy control group were 9.29±20.79, 1.20±0.32 uIU/ml. Frequency of dental amalgam implantation in patients with Hashimoto's thyroiditis was not statistically significantly different from healthy controls (p=186) (t=-1.324) CONCLUSIONS: Some studies identified mercury of amalgam as responsible for autoimmune thyroiditis. We studied whether amalgam fillings are more frequent in Hashimoto's thyroiditis patients and whether it is a causative factor for Hashimoto's thyroiditis. Statistical analysis revealed that there is no relation of amalgam with Hashimoto's thyroiditis (Tab. 1, Ref. 34).

  1. Phase down of amalgam. Awareness of Minamata convention among Jordanian dentists.

    Science.gov (United States)

    Al-Rabab'ah, Mohammad A; Bustani, Mohammad A; Khraisat, Ameen S; Sawair, Faleh A

    2016-12-01

    To assess the knowledge of Jordanian dentists toward phase down of dental amalgam as recommended by the Minamata Convention, and their training and competency in placing posterior composites.  Methods: This study was conducted through structured questionnaire interviews with randomly selected cohort of dentists in Jordan between March 2015 and June 2015. Out of 230 dentists who were invited, 196 (85.2%) agreed to participate. Dentists were asked if they know about the Minamata Convention. They were also asked about their training in placement of posterior composite.  Results: Out of the 196 interviewed, only 13.8% know about Minamata Convention and 17% had an undergraduate training in favor of placing composites in posterior teeth. Approximately 50% of those dentists were not trained in using rubber dam when placing posterior composites, while only 38.3% had training in sectional matrix placement. Undergraduate training did not influence (p=0.00) the dentists' decision to remove old amalgam based on patient's demands. Only 28.1% were of the opinion of discontinuing the use of amalgam due to its alleged health and environmental hazards. There was no general agreement on the type of composite, liner, and bonding strategy when placing posterior composites. Conclusion: Dentists are not well informed on the Minamata Convention and the phase down of amalgam. Training in posterior composite placement should be given more room in undergraduate curriculum and continuous dental education.

  2. Renal Effects of Dental Amalgam in Children: The New England Children’s Amalgam Trial

    OpenAIRE

    Barregard, Lars; Trachtenberg, Felicia; McKinlay, Sonja

    2007-01-01

    Background Mercury is nephrotoxic and dental amalgam is a source of mercury exposure. Methods Children 6–10 years of age (n = 534) with two or more posterior teeth with caries but no prior amalgam restorations, were randomized to one of two treatments—amalgam or resin composite (white fillings)—used for caries treatment during 5 years of follow-up. The primary outcome was change in IQ, but important secondary outcomes were effects on markers of glomerular and tubular kidney function: urinary ...

  3. Cytotoxicity of corroded and non-corroded dental silver amalgams.

    Science.gov (United States)

    Milleding, P; Wennberg, A; Hasselgren, G

    1985-02-01

    The cytotoxicity of one conventional and four non-gamma 2-amalgams was studied in a cell culture system, using the Millipore filter method. Before testing set amalgam specimens were kept in distilled water or in artificial saliva at pH 4, 5, or 7 for up to 28 wk to produce a corrosion layer on the test surface. Non-corroded set amalgam specimens was also tested. None of the noncorroded, set amalgams showed any sign of surface accumulation of cytotoxic products whereas the corroded amalgams showed varying degrees of cytotoxicity. Generally, the non-gamma 2-amalgams gave a more pronounced cytotoxic effect than the conventional amalgam. When the corrosion procedure was carried out at pH 7, the various non-gamma 2-amalgams showed different degrees of cytotoxicity. It appears that the difference in cytotoxic effect between the non-gamma 2-amalgams and the conventional amalgam as well as the differences among the various non-gamma 2-amalgams could be related to variation in the retention of corrosion products deposited on the amalgam surface.

  4. 21 CFR 872.3110 - Dental amalgam capsule.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental amalgam capsule. 872.3110 Section 872.3110...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3110 Dental amalgam capsule. (a) Identification. A dental amalgam capsule is a container device in which silver alloy is intended to be mixed with mercury...

  5. Adsorption of cobalt (II) octaethylporphyrin and 2H-octaethylporphyrin on Ag(111): new insight into the surface coordinative bond

    International Nuclear Information System (INIS)

    Bai Yun; Buchner, Florian; Kellner, Ina; Schmid, Martin; Vollnhals, Florian; Steinrueck, Hans-Peter; Marbach, Hubertus; Michael Gottfried, J

    2009-01-01

    The adsorption of cobalt (II) octaethylporphyrin (CoOEP) and 2H-octaethylporphyrin (2HOEP) on Ag(111) was investigated with scanning tunneling microscopy (STM) and photoelectron spectroscopy (XPS/UPS), in order to achieve a detailed mechanistic understanding of the surface chemical bond of coordinated metal ions. Previous studies of related systems, especially cobalt (II) tetraphenylporphyrin (CoTPP) on Ag(111), have revealed adsorption-induced changes of the oxidation state of the Co ion and the appearance of a new valence state. These effects were attributed to a covalent interaction of the Co ion with the silver substrate. However, recent studies show that the porphyrin ligand of adsorbed CoTPP undergoes a pronounced saddle-shape distortion, which could alter the electronic structure and thus provide an alternative explanation for the new valence state previously attributed to the formation of a surface coordinative bond. With the octaethylporphyrins investigated here, which were found to adsorb in a flat, undistorted conformation on Ag(111), the effects of geometric distortion can be separated from those of the electronic interaction with the substrate. The CoOEP monolayer gives rise to an adsorption-induced shift of the Co 2p signal (-1.9 eV relative to the multilayer), a new valence state at 0.6 eV below the Fermi energy, and a work-function shift of -0.84 eV (2HOEP: -0.44 eV) relative to the clean surface. Comparison with data for the distorted CoTPP confirms the existence of a covalent ion-surface interaction that is insensitive to the conformation of the ligand.

  6. Pd(II)-Catalyzed Olefination of sp3 C–H Bonds

    Science.gov (United States)

    Wasa, Masayuki; Engle, Keary M.; Yu, Jin-Quan

    2010-01-01

    The first Pd(II)-catalyzed sp3 C–H olefination reaction has been developed using N-arylamide directing groups. Following olefination, the resulting intermediates were found to undergo rapid 1,4-addition to give the corresponding γ lactams. Notably, this method was effective with substrates containing α-hydrogen atoms and could be applied to effect methylene C–H olefination of cyclopropane substrates. PMID:20187642

  7. Magnetic circular dichroism and density functional theory studies of electronic structure and bonding in cobalt(ii)-N-heterocyclic carbene complexes.

    Science.gov (United States)

    Iannuzzi, Theresa E; Gao, Yafei; Baker, Tessa M; Deng, Liang; Neidig, Michael L

    2017-10-10

    The combination of simple cobalt salts and N-heterocyclic carbene (NHC) ligands has been highly effective in C-H functionalization, hydroarylation and cross-coupling catalysis, though displaying a strong dependence on the identity of the NHC ligand. In addition, reactions effective with NHC ligands are often ineffective with phosphine ligands, further motivating the evaluation of the fundamental electronic structure and bonding differences in well-defined distorted tetrahedral Co(ii) complexes. Magnetic circular dichroism (MCD) studies indicate that Co(ii)-bisphosphines have larger ligand fields than Co(ii)-NHC complexes. Theoretical density functional theory (DFT) calculations were performed on an expanded set of L 2 CoCl 2 complexes (L 2 = NHC, bisphosphine and diamine) to study the electronic structure and relative ligation properties of NHCs compared to bisphosphine and diamine ligands. Mayer bond order and charge decomposition analyses indicate that NHC ligands are slightly stronger donor ligands than bisphosphines but also result in a weakening of Co-Cl bonds in a trans-like influence. From MCD and DFT studies, changing the NHC N-substituent has a larger effect on the ligand field of Co(ii)-NHC complexes than saturating the backbone. Overall, these studies provide detailed insight into the electronic structure and bonding effects in Co(ii) complexes with ligand types commonly explored in catalysis.

  8. Effect of composite/amalgam thickness on fracture resistance of maxillary premolar teeth, restored with combined amalgam-composite restorations.

    Science.gov (United States)

    Firouzmandi, Maryam; Doozandeh, Maryam; Jowkar, Zahra; Abbasi, Sanaz

    2016-07-01

    Combined amalgam-composite restorations have been used through many years to benefit from the advantages of both dental amalgam and composite resin. Two variations have been mentioned for this technique, this study investigated the fracture resistance of maxillary premolar teeth with extended mesio-occluso-distal (MOD) cavities, restored with the two variations of combined amalgam-composite restorations. Sixty intact extracted premolar teeth were randomly divided into 6 groups (G1-G6) of 10 teeth. G1; consisted of intact teeth and G2; consisted of teeth with MOD preparations were assigned as the positive and negative control groups respectively. Other experimental groups after MOD preparations were as follows: G3, amalgam restoration; G4, composite restoration; G5 combined amalgam-composite restoration with amalgam placement only on 1mm of the gingival floor of the proximal boxes; G6, combined amalgam-composite restoration with amalgam placement to the height of contact area of the proximal surface of the tooth. Fracture strength of the specimens was measured and the data were analyzed using one-way analysis of variance (ANOVA). The level of significance was Pamalgam-composite restoration was similar to that achieved with composite restoration alone and more than that of amalgam restoration alone. It can be concluded that the thickness of amalgam in combined amalgam-composite restorations did not affect fracture resistance of the teeth. Amalgam, composite, fracture resistance, restoration.

  9. Carbon-carbon bond formation in cationic aryl-olefin-platinum (II) complexes

    Energy Technology Data Exchange (ETDEWEB)

    De Felice, V. [Universita del Molise, Campobasso (Italy); Renzi, A.D.; Tesauro, D.; Vitagliano, A. [Universita di Napoli (Italy)

    1992-11-01

    Cationic five-coordinate [Pt(3-R{sup 1}-4-R{sup 2}-C{sub 6}H{sub 3})(MeCN) (6-Me-py-2-CH=NPh)(C{sub 2}H{sub 4})]{sup +} complexes (R{sup 1}, R{sup 2} = H, Me, OMe) undergo an unexpected rearrangement at 0{degrees}C in chloroform solution, affording, after treatment with aqueous LiCl, the neutral four-coordinate species [Pt(2-Et-4-R{sup 1}-5-R{sup 2}-C{sub 6}H{sub 2})Cl(6-Me-py-1-CH=NPh)]. Pt-C{sub aryl} bond breaking and making is involved in the whole process, resulting in a 1,2-shift of the platinum atom to an adjacent position of the benzene ring. The same compound is obtained, together with products deriving from a typical insertion, when an equimolar amount of ethylene is added to a chloroform solution of [Pt(3-R{sub 1}-4-R{sup 2}-C{sub 6}H{sub 3})(MeCN)(6-Me-py-2-CH=NPh)]{sup +} at 0{degrees}C. When higher ethylene/Pt ratios are used, only five-coordinate [Pt(3-R{sup 1}-4-R{sup 2}-C{sub 6}H{sub 3}CH{sub 2}CH{sub 2})Cl(6-Me-py-2-CH{double_bond}NPh)(C{sub 2}H{sub 4})] complex is isolated. As the experimental data rule out the possibility of a (2-arylethyl)platinum to (2-ethylaryl)platinum rearrangement, different reaction paths are suggested for the two processes. When the two reactions are combined in a {open_quotes}one-pot{close_quotes} sequence, a regiocontrolled double alkylation of the aryl system can be obtained. The behavior substrates containing bidenate nitrogen ligands having different five-coordination stabilizing effects is examined, and data concerning the reactions of propene and styrene are reported. 13 refs., 3 tabs.

  10. Dentin bonding system. Part I: Literature review.

    Science.gov (United States)

    Miyazaki, M; Oshida, Y; Xirouchaki, L

    1996-01-01

    Currently, clinicians face choices of restoration including amalgams (mercury-based, gallium-based alloys, or mercury-free silver-based substitutes), composite resins, ceramics, and gold alloy. In order to choose an appropriate restorative material, many parameters are involved; they include preparation time requirements, finishing and polishing, marginal integrity, anatomy and contours, chipping and fracture, sensitivity, microleakage, wear resistance, and corrosion resistance. It is generally believed that amalgams are still evaluated as the best of all restorative materials as far as the aforementioned parameters are concerned. It is claimed that the amalgams exhibit in the range of 10 to 25 service years, while the composite resin exhibits ranging between 7 and 11 service years. When a composite resin requires a mass large enough for indirect fabrication, a bonding system is demanded with which this restoration should form an instantaneous, impervious, and stable bond to the tooth structure. Roughly a quarter century has passed since the research and development of a promising dentin bonding system was initiated. We are now in the fifth generation of the dentin bonding system, during the research and development of which various types of bonding agents as well as bonding models have been introduced. In this article, the history of development of the bonding agents and the understanding of the bonding mechanism will be reviewed.

  11. Amalgam tattoo (amalgam pigmentation) of the oral mucosa: clinical manifestations, diagnosis and treatment.

    Science.gov (United States)

    Buchner, A

    2004-07-01

    Amalgam tattoo is an iatrogenic lesion caused by traumatic implantation of dental amalgam into soft tissue. Amalgam tattoo is the most common localized pigmented lesion in the mouth. In a study of a mass screening oral examination in the United States, it was found in about 0.4-0.9% of the adult population and in Sweden in about 8%. Clinically, amalgam tattoo presents as a dark gray or blue, flat macule located adjacent to a restored tooth. Most are located on the gingiva and alveolar mucosa followed by the buccal mucosa and the floor of the mouth. Microscopic examination reveals that amalgam is present in the tissues in two forms: as irregular dark, solid fragments of metal or as numerous, discrete fine, brown or black granules dispersed along collagen bundles and around small blood vessels and nerves. In most lesions, it is presented in both forms. The biologic response to the amalgam is related to particle size, quantity and elemental composition of the amalgam. Large fragments often become surrounded by dense fibrous connective tissue. Smaller particles are associated with mild to moderate chronic inflammatory response with individual macrophages engulfing small amalgam particles. Occasionally, the reaction takes the form of foreign body granuloma in which macrophages and multinucleated giant cells are present. Some of the multinucleated giant cells also contain amalgam particles. Diagnosis of amalgam tattoo is usually obvious from the location and clinical appearance. A radiograph is recommended to confirm the presence of metallic particles, but absence of radiographic evidence does not rule out the possibility, since particles are often too fine or widely dispersed to be visible on radiographs. When there is no radiographic evidence or an adjacent restored tooth, biopsy is recommended to rule out an early melanoma. Once the diagnosis of amalgam tattoo has been established, no additional treatment is necessary except for cosmetic reasons. If the pigmentation

  12. Dental amalgam: is this the end?

    Science.gov (United States)

    Taut, Cristina

    Dental amalgam is a reliable and effective restorative material with a well-established role in modern dentistry. Throughout the years its mercury content and the risks posed to human health were main topics of interest for many scientists. This paper offers a review of the scientific literature on the health and environmental impact of mercury in dentistry published over the last decade. A variety of peer-reviewed, epidemiological and large-scale clinical studies on dental amalgam, as well as published reports of professional and governmental bodies, were organised thematically and analysed. The most relevant findings of the aforementioned literature are reported. No reliance has been placed on unpublished work or publicly available opinions that are not scientifically based. In order to offer an appropriate view on the topic the toxicology, health impacts and possible environmental threats are briefly presented in relation to the relevant literature published in the last ten years. It is almost unanimously accepted that dental amalgam is a safe material, with little or insignificant adverse effect on general health. However, current and mostly unfounded environmental concerns may result in the implementation of new across the board legislation that could lead to a global dental amalgam "phase out".

  13. Amalgam tattoo: a cause of sinusitis?

    Directory of Open Access Journals (Sweden)

    José Luiz Santos Parizi

    2010-02-01

    Full Text Available Little attention has been paid to the toxicity of silver amalgam fillings, which have been used over the centuries in Dentistry. Amalgam particles may accidentally and/or traumatically be embedded into the submucosal tissue during placement of a restoration and perpetuate in such area. This article presents a case of amalgam tattoo and investigates whether it is related to the patient's repeated episodes of sinusitis. The patient was a 46-year-old woman with a 2 mm diameter radiopaque lesion in the right oral mucosa detected on a panoramic radiograph and presented as a black macula clinically. A complete surgical resection was carried out. The histopathological examination revealed deposits of dark-brownish pigments lining the submucosal tissue with adjacent lymphocytic inflammatory infiltrate and multinucleated giant cells phagocyting pigments. There was a negative staining for both iron and melanin. One year after lesion removal, the patient reported that the sinusitis crises had ceased after repeated episodes for years. It may be speculated that the inflammatory process related to amalgam tattoo seems to lead to a local immune response that causes sinusitis because it enhances the human leukocyte antigen DR (HLA-DR tissue expression.

  14. Amalgam tattoo: a cause of sinusitis?

    Science.gov (United States)

    Parizi, José Luiz Santos; Nai, Gisele Alborghetti

    2010-01-01

    Little attention has been paid to the toxicity of silver amalgam fillings, which have been used over the centuries in Dentistry. Amalgam particles may accidentally and/or traumatically be embedded into the submucosal tissue during placement of a restoration and perpetuate in such area. This article presents a case of amalgam tattoo and investigates whether it is related to the patient's repeated episodes of sinusitis. The patient was a 46-year-old woman with a 2 mm diameter radiopaque lesion in the right oral mucosa detected on a panoramic radiograph and presented as a black macula clinically. A complete surgical resection was carried out. The histopathological examination revealed deposits of dark-brownish pigments lining the submucosal tissue with adjacent lymphocytic inflammatory infiltrate and multinucleated giant cells phagocyting pigments. There was a negative staining for both iron and melanin. One year after lesion removal, the patient reported that the sinusitis crises had ceased after repeated episodes for years. It may be speculated that the inflammatory process related to amalgam tattoo seems to lead to a local immune response that causes sinusitis because it enhances the human leukocyte antigen DR (HLA-DR) tissue expression.

  15. Reference Electrodes Based on Solid Amalgams

    Czech Academy of Sciences Publication Activity Database

    Josypčuk, Bohdan; Novotný, Ladislav

    2004-01-01

    Roč. 16, č. 3 (2004), s. 238-241 ISSN 1040-0397 Grant - others:GIT(AR) 101/02/U111/CZ Institutional research plan: CEZ:AV0Z4040901 Keywords : solid amalgam * reference electrode * voltammetry Subject RIV: CG - Electrochemistry Impact factor: 2.038, year: 2004

  16. Boundedness of positive operators on weighted amalgams

    Directory of Open Access Journals (Sweden)

    Aguilar Cañestro María Isabel

    2011-01-01

    Full Text Available Abstract In this article, we characterize the pairs (u, v of positive measurable functions such that T maps the weighted amalgam in (Lp (u, ℓ q for all , where T belongs to a class of positive operators which includes Hardy operators, maximal operators, and fractional integrals. 2000 Mathematics Subject Classification 26D10, 26D15 (42B35

  17. Dental amalgam restorations and children's neuropsychological function: the New England Children's Amalgam Trial.

    Science.gov (United States)

    Bellinger, David C; Daniel, David; Trachtenberg, Felicia; Tavares, Mary; McKinlay, Sonja

    2007-03-01

    A concern persists that children's exposure to mercury vapor from dental amalgams produces neurotoxicity. Our goal was to compare the neuropsychological function of children, without prior exposure to dental amalgam, whose caries were repaired using either dental amalgam or mercury-free composite materials. We conducted a randomized controlled trial involving 534 6- to 10-year-old urban and rural children who were assessed yearly for 5 years using a battery of tests of intelligence, achievement, language, memory, learning, visual-spatial skills, verbal fluency, fine motor function, problem solving, attention, and executive function. Although the mean urinary mercury concentration was greater among children in the amalgam group than the composite group (0.9 vs. 0.6 microg/g creatinine), few significant differences were found between the test scores of children in the two groups. The differences found were inconsistent in direction. Analyses using two cumulative exposure indices--surface years of amalgam and urinary mercury concentration--produced similar results. Exposure to elemental mercury in amalgam at the levels experienced by the children who participated in the trial did not result in significant effects on neuropsychological function within the 5-year follow-up period.

  18. A Review on Dental Amalgam Corrosion and Its Consequences

    Directory of Open Access Journals (Sweden)

    M Fathi

    2004-02-01

    Full Text Available Dental amalgam is still the most useful restorative material for posterior teeth and has been successfully used for over a century. Dental amalgam has been widely used as a direct filling material due to its favorable mechanical properties as well as low cost and easy placement. However, the mercury it contains raises concerns about its biological toxicity and environmental hazard. Although in use for more than 150 years, dental amalgam has always been suspected more or less vigorously due to its alleged health hazard. Amalgam restorations often tarnish and corrode in oral environment. Corrosion of dental amalgam can cause galvanic action. Ion release as a result of corrosion is most important. Humans are exposed to mercury and other main dental metals via vapor or corrosion products in swallowed saliva and also direct absorption into blood from oral mucosa. During recent decades the use of dental amalgam has been discussed with respect to potential toxic effects of mercury components. In this article, the mechanisms of dental amalgam corrosion are described and results of researches are reviewed. It finally covers the corrosion of amalgams since this is the means by which metals, including mercury, can be released within oral cavity. Keywords: Dental amalgam, Amalgam corrosion, Biocompatibility, Mercury release, Amalgam restoration

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

    Science.gov (United States)

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

    2001-06-01

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

  20. Mercury evaporation from amalgams with varied mercury contents.

    Science.gov (United States)

    Ohmoto, K; Nakajima, H; Ferracane, J L; Shintani, H; Okabe, T

    2000-09-01

    This study examined the relationship between mercury content and mercury evaporation from amalgams during setting. Two different types of commercial high-copper amalgams (single composition and admixed types) were used. Cylindrical specimens of each amalgam were prepared with five different mercury contents according to ADA Specification No.1. Specimens were also prepared by hand condensation. Mercury evaporation from amalgam specimens maintained at 37 degrees C was measured using a gold film mercury analyzer from 10 min after the end of trituration until the mercury concentration in air reached an undetectable level. The mercury content more clearly influenced the mercury evaporation from the admixed type amalgam specimens when the mercury content decreased below the manufacturers' recommended trituration conditions. Triturating with less mercury than the manufacturers' recommended amount cannot lower the evaporation of mercury from freshly made amalgam. Proper condensing procedures can minimize the mercury evaporation from the amalgam surface.

  1. The synthesis and properties of some organometallic compounds containing group IV (Ge, Sn)-group II (Zn, Cd) metal---metal bonds

    NARCIS (Netherlands)

    Des Tombe, F.J.A.; Kerk, G.J.M. van der; Creemers, H.M.J.C.; Carey, N.A.D.; Noltes, J.G.

    1972-01-01

    The reactions of triphenylgermane and triphenyltin hydride with coordinatively saturated organozinc or organocadmium compounds give organometallic complexes containing Group IV (Ge, Sn)-Group II(Zn, Cd) metal---metal bonds. The 2,2′-bipyridine complexes show solvent-dependent charge-transfer

  2. Short-term evaluation of resin sealing and rebonding on amalgam microleakage: an SEM observation.

    Science.gov (United States)

    Moosavi, Horieh; Sadeghi, Samaneh

    2008-03-01

    The aim of this study was to evaluate the effect of two different sealing agents on the microleakage of Class V amalgam restorations with and without resin rebonding. Sixty extracted premolars were divided into six groups with ten teeth in each group. Class V cavity preparations were prepared on the facial surfaces of each tooth with the coronal margins placed in enamel and apical margins in cementum (dentin). The preparations in three groups were treated with Copalite, Scotchbond Multi-Purpose (SBMP), and no sealing agent, respectively. The other three groups received the same sealing agents in conjunction with a rebonding process. This arrangement of specimens provided for a comparison of the groups with and without a rebonding procedure. Amalgam was used as the restorative material. Specimens were thermocycled, stained, and sectioned. Microleakage was graded (0-3) using a stereomicroscope at 40x magnification. A scanning electron microscope (SEM) was used along with a high resolution elemental analysis. Data were analyzed with Kruskal-Wallis, Mann-Withney, and Wilcoxon pair wise statistical tests (alpha=.05). The bonded amalgam groups demonstrated significantly less microleakage, whereas the unsealed groups showed the highest microleakage (P=0.001). A significant difference between the mean rank of the microleakage of enamel and dentin margins was observed (P=0.037). Insignificant, lower microleakage was observed in groups receiving a rebonding procedure (P=0.085). Copalite and a multi-step adhesive system had a significant effect on microleakage of Class V amalgam restorations. The influence of the multi-step adhesive system was significantly greater than Copalite. The rebonding of the amalgam restorations did not have a significant effect on microleakage.

  3. The effect of rebonding and liner type on microleakage of Class V amalgam restorations

    Directory of Open Access Journals (Sweden)

    Moosavi H.

    2008-10-01

    Full Text Available Background and Aim: Application of varnish and dentin bonding agents can effectively reduce microleakage under amalgam restorations. Also rebonding may show some effects on microleakage and its complications. The aim of this study was to evaluate the effect of liner/ adhesives on microleakage of Class V amalgam restoration with or without rebonding. Materials and Methods: In this in vitro study Class V cavities were prepared on sixty sound human maxillary premolars with the gingival floor 1mm below the CEJ. Cases were divided into six groups of ten teeth each. Specimens in group 1 and 2 were lined with Copalite and Scotchbond Multi-Purpose (SBMP respectively. In the third group (control no liner was applied. The teeth were then restored with spherical amalgam. Specimens in group 4 to 6 received the same treatments but after filling, the interfaces of restorations and teeth were etched with 37% phosphoric acid gel, rinsed and dried. Adhesive resin of SBMP was applied over amalgam and tooth margins and polymerized (rebonding. Specimens were thermocycled, exposed to dye and sectioned. Microleakage was graded (0-3 using a stereomicroscope at X40 magnification. Data were analyzed with Kruskal-Wallis, Mann-Whitney and Wilcoxon pair wise statistical tests. P<0.05 was considered as the limit of significance. Results: The groups lined with SBMP showed the lowest and the groups without liner the highest microleakage (p= 0.001. Significant difference was observed in microleakage mean rank of enamel and dentin margins (p=0.048. Rebonding with resin did not improve the seal (p> 0.05. Conclusion: Based on the results of this study, total etch adhesive system had significant effect on microleakage of Class V amalgam restorations especially in cervical margin. Rebonding did not show a significant effect on microleakage.

  4. The future of dental amalgam: a review of the literature. Part 1: Dental amalgam structure and corrosion.

    Science.gov (United States)

    Eley, B M

    1997-04-12

    This is the first article in a series of seven on the future of dental amalgam. Dental amalgam is still the most useful restorative material for posterior teeth and has been used successfully for over 100 years. The history of dental amalgam since its introduction in 1819 and the controversies about its use between 1834 and today are described. The composition of the various dental amalgams in clinical use today are then reported. It finally covers the corrosion of amalgams since this is the means by which metals, including mercury, can be released.

  5. Prenatal exposure to dental amalgam in the Seychelles Child Development Nutrition Study: associations with neurodevelopmental outcomes at 9 and 30 months.

    Science.gov (United States)

    Watson, Gene E; Evans, Katie; Thurston, Sally W; van Wijngaarden, Edwin; Wallace, Julie M W; McSorley, Emeir M; Bonham, Maxine P; Mulhern, Maria S; McAfee, Alison J; Davidson, Philip W; Shamlaye, Conrad F; Strain, J J; Love, Tanzy; Zareba, Grazyna; Myers, Gary J

    2012-12-01

    Dental amalgam is approximately 50% metallic mercury and releases mercury vapor into the oral cavity, where it is inhaled and absorbed. Maternal amalgams expose the developing fetus to mercury vapor. Mercury vapor can be toxic, but uncertainty remains whether prenatal amalgam exposure is associated with neurodevelopmental consequences in offspring. To determine if prenatal mercury vapor exposure from maternal dental amalgam is associated with adverse effects to cognition and development in children. We prospectively determined dental amalgam status in a cohort of 300 pregnant women recruited in 2001 in the Republic of Seychelles to study the risks and benefits of fish consumption. The primary exposure measure was maternal amalgam surfaces present during gestation. Maternal occlusal points were a secondary measure. Outcomes were the child's mental (MDI) and psychomotor (PDI) developmental indices of the Bayley Scales of Infant Development-II (BSID-II) administered at 9 and 30 months. Complete exposure, outcome, and covariate data were available on a subset of 242 mother-child pairs. The number of amalgam surfaces was not significantly (p>0.05) associated with either PDI or MDI scores. Similarly, secondary analysis with occlusal points showed no effect on the PDI or MDI scores for boys and girls combined. However, secondary analysis of the 9-month MDI was suggestive of an adverse association present only in girls. We found no evidence of an association between our primary exposure metric, amalgam surfaces, and neurodevelopmental endpoints. Secondary analyses using occlusal points supported these findings, but suggested the possibility of an adverse association with the MDI for girls at 9 months. Given the continued widespread use of dental amalgam, we believe additional prospective studies to clarify this issue are a priority. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Prenatal Exposure to Dental Amalgam in the Seychelles Child Development Nutrition Study: Associations with Neurodevelopmental Outcomes at 9 and 30 Months

    Science.gov (United States)

    Watson, Gene E.; Evans, Katie; Thurston, Sally W.; van Wijngaarden, Edwin; Wallace, Julie M. W.; McSorley, Emeir M.; Bonham, Maxine P.; Mulhern, Maria S.; McAfee, Alison J.; Davidson, Philip W.; Shamlaye, Conrad F.; Strain, J.J.; Love, Tanzy; Zareba, Grazyna; Myers, Gary J.

    2012-01-01

    Background Dental amalgam is approximately 50% metallic mercury and releases mercury vapor into the oral cavity, where it is inhaled and absorbed. Maternal amalgams expose the developing fetus to mercury vapor. Mercury vapor can be toxic, but uncertainty remains whether prenatal amalgam exposure is associated with neurodevelopmental consequences in offspring. Objective To determine if prenatal mercury vapor exposure from maternal dental amalgam is associated with adverse effects to cognition and development in children. Methods We prospectively determined dental amalgam status in a cohort of 300 pregnant women recruited in 2001 in the Republic of Seychelles to study the risks and benefits of fish consumption. The primary exposure measure was maternal amalgam surfaces present during gestation. Maternal occlusal points were a secondary measure. Outcomes were the child’s mental (MDI) and psychomotor (PDI) developmental indices of the Bayley Scales of Infant Development-II (BSID-II) administered at 9 and 30 months. Complete exposure, outcome, and covariate data were available on a subset of 242 mother-child pairs. Results The number of amalgam surfaces was not significantly (p>0.05) associated with either PDI or MDI scores. Similarly, secondary analysis with occlusal points showed no effect on the PDI or MDI scores for boys and girls combined. However, secondary analysis of the 9 month MDI was suggestive of an adverse association present only in girls. Conclusion We found no evidence of an association between our primary exposure metric, amalgam surfaces, and neurodevelopmental endpoints. Secondary analyses using occlusal points supported these findings, but suggested the possibility of an adverse association with the MDI for girls at 9 months. Given the continued widespread use of dental amalgam, we believe additional prospective studies to clarify this issue are a priority. PMID:23064204

  7. The mercury-richest europium amalgam Eu{sub 10}Hg{sub 55}

    Energy Technology Data Exchange (ETDEWEB)

    Tambornino, Frank; Hoch, Constantin [Department of Chemistry, Ludwig-Maximilians-Universitaet Muenchen (Germany)

    2015-03-15

    The mercury-richest europium amalgam Eu{sub 10}Hg{sub 55} was synthesized by isothermal electrocrystallization from a solution of EuI{sub 3}.8DMF in DMF on a reactive mercury cathode. The crystal structure shows remarkable complexity and polar metal-metal bonding. Closely related to the structures of mercury-rich amalgams A{sub 11-x}Hg{sub 55+x} (A = Na, Ca, Sr), it shows underoccupied Hg positions along [00z]. Eu{sub 10}Hg{sub 55} can be described as hettotype structure of the Gd{sub 14}Ag{sub 51} structure type. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Effect of amalgam cuspal coverage on the fracture resistance of endodontically treated teeth

    Directory of Open Access Journals (Sweden)

    Mahshid Mohammdi Basir

    2013-05-01

    Full Text Available   Background and Aims: Endodontically treated teeth are prone to fracture because they loose a big amount of their structure. The treatment plan of those teeth is completed when they are rehabilitated with a strong and functional restoration. The purpose of this study was to evaluate the fracture resistance of endodontically treated teeth restored with amalgam cuspal coverage in comparison with other restorative techniques.   Materials and Methods: 40 human healthy maxillary premolars were divided into 4 groups: group1 (S: sound teeth, group 2(Co: endodontically treated teeth with MOD cavity restored with bonding and composite, group 3(Am-B: endodontically treated teeth with MOD cavity restored with bonding and amalgam and group 4 (Am-CC: endodontically treated teeth with MOD cavity restored with amalgam cuspal coverage. Then the restorations were stored in water and room temperature for 100 days at then thermocycled for 500 cycles between water baths at (5.5 ± 1 and (55 ± 1 0 C. The fracture resistance was evaluated by universal testing machine (Instron, 1195 UK with the compressive force of about 2000 N in 0.5 mm/min. The fracture modes were evaluated in four groups by a stereomicroscope. Statistical analysis (Scheffe test was done for all groups (P0.05. The lowest fracture resistance was found in group 2 (Co (384 ± 137.4 N that had no significant difference with group 3 (Am-B (P>0.05. The fracture resistance in group 4 was significantly higher than group 2 (Co and 3 (Am-B. The fracture mode in group 1 was cohesive within tooth and in group 2 (Co and 3 (Am-B was mixed cohesive and adhesive, and in group 4 was cohesive within in restorative material.   Conclusion: The highest fracture resistance was found in teeth that received amalgam cuspal coverage.

  9. Dentists' perspective about dental amalgam: current use and future direction.

    Science.gov (United States)

    Bakhurji, Eman; Scott, Thayer; Mangione, Thomas; Sohn, Woosung

    2017-06-01

    In 2013, the United Nations Environment Programme (UNEP) reached a binding agreement - a.k.a. the Minamata treaty - to decrease dental amalgam use. This study aims to investigate US dentists' current practice and opinions about amalgam use, and to determine factors affecting their amalgam use and opinions. A total of 45,557 general dentists and 5,101 pediatric dentists were invited to participate in a pre-tested electronic survey. The survey consisted of 12 close-ended questions using a 5-point Likert Scale. The Qualtrics™ software was used to distribute the survey, followed by three reminders. Response rate was 5.2 percent for general dentists, and 17.6 percent for pediatric dentists. Sixty-two percent of general dentists and 56 percent of pediatric dentists reported using amalgam. Most dentists disagreed with banning amalgam, while agreeing with installing amalgam separators. Environmentally conscious dentists were more likely to agree with banning amalgam and installing amalgam separators. Responding dentists favor the continued use of dental amalgam. Their perspectives vary by several factors including dentists' environmental consciousness. Policies toward minimizing amalgam's environmental impact need to be implemented. © 2017 American Association of Public Health Dentistry.

  10. Electrochemical behavior of some commercial dental amalgams in artificial saliva.

    Science.gov (United States)

    Cahoon, J R; Regalbuto, C

    1975-01-01

    Cathodic, linear anodic, and anodic polarization studies conducted on three commercial dental amalgams, Caulk Fine Cut Alloy, Spheralloy, and Dispersalloy, showed that all amalgams were in a passive state at the corrosion potential in synthetic saliva solution. The corrosion currents at the corrosion potential were therefore small for all the amalgams, in the range 0.08 to 0.30 muA/cm2. However, the Caulk Fine Cut Alloy and Spheralloy amalgams exhibited a breakdown of passivity and high anodic currents at potentials only approximately equal to 100 mV more noble than the corrosion potential whereas Dispersalloy amalgams maintained passivity at potentials up to 700 mV more noble than the corrosion potential. The breakdown of passivity in Caulk Alloy and Spheralloy amalgams is attributed to the presence of the gamma2 phase (Sn7-8Hg) whereas the passive behavior of Dispersalloy amalgam is attributed to the absence of the phase. It is concluded that none of the amalgams will exhibit severe general corrosion in use, but that both Caulk Alloy and Spheralloy amalgams will exhibit pitting corrosion whereas this type of corrosion should be minimal in Dispersalloy amalgams.

  11. Micro-PIXE study of metal loss from dental amalgam

    Science.gov (United States)

    Meesat, Ridthee; Sudprasert, Wanwisa; Guibert, Edouard; Wang, Liping; Chappuis, Thibault; Whitlow, Harry J.

    2017-08-01

    Mercury amalgams have been a topic of controversy ever since their introduction over 150 years ago as a dental material. An interesting question is if metals are released from the amalgam into the enamel and dentine tissue. To elucidate this PIXE mapping was used to investigate metal redistribution in an extracted molar tooth with a ∼30 year old high-Cu content amalgam filling. The tooth was sectioned and polished, and elemental mapping carried out on the amalgam/enamel, bulk amalgam and the wear surface of the amalgam. As expected, the amalgam was multiphase amalgam comprising of Cu-rich and Ag-rich grains with non-uniform distribution of Hg. The amalgam/dentine interface was clearly defined with amalgam elements on one side and C and P from hydroxyapatite on the other side with evidence of only slight interface corrosion. The peaks for Cu Hg and Zn were isolated from interfering signals with concentrations in the enamel tissue, observed to be at, or below the method detection limit. The proximity in energy of the Sn L α and Ca K α , peaks and the background on the Hg M α gave signal overlap which increased the MDL for these elements. Remarkably, a course grain texture in the amalgam was observed just below the biting surface of the amalgam which might be associated with tribochemical processes from mastication. This coupled with the clear absence of the amalgam metals from tooth tissue, even in close proximity to the interface, suggests that for this sample, release of Hg occurred via erosion or dissolution in saliva.

  12. Metal release from high-copper amalgams containing palladium.

    Science.gov (United States)

    Lin, T H; Chan, C C; Chung, K H

    1994-03-01

    High-copper amalgam containing palladium has been successfully developed. However, the effect of palladium on the release of corrosion products remains unknown. We studied the effect of palladium addition on the electrochemical properties of amalgams by measuring the amount of the elements released from the experimental Pd-containing amalgams into Ringer's solution. A series of specimens of high-copper amalgams containing different concentrations of palladium, from 0.42 w% to 3.33 w% in the final amalgam, fabricated from a blend of traditional amalgam alloy and copper-silver-palladium ternary alloy, were subjected to free corrosion in Ringer's solution at 37 degrees C for 3 months. Aliquots of 10 microL of electrolyte were removed serially with time, and the concentrations of Ag, Sn, Cu, Pd and Zn were evaluated by graphite furnace atomic absorption technique. In addition, dissolved Hg was evaluated by cold vapor atomic absorption technique in the same aliquotes. Various kinds of commercial amalgam including traditional (Spheraloy), high-copper blends (Dispersalloy and Valiant-Ph.D.) and high-copper spherical (Valiant) were employed as controls. Ag and Sn cations released from the amalgams containing palladium were similar in concentration to those released from the commercial amalgams. The concentrations of released Cu and Hg cations decreased as a function of increased Pd concentration in the experimental amalgams. Averaging an order of magnitude of released Cu and Hg cations less than commercial controls for amalgam containing 1.7 w% Pd. Detection of Pd was essentially below the resolution of the technique and Zn was only detected in case of Dispersalloy. Pd addition to high-copper amalgam alloy reduces the release of mercury and copper from the Pd-containing amalgam.

  13. Mercury release from dental amalgam restorations after magnetic resonance imaging and following mobile phone use

    International Nuclear Information System (INIS)

    Mortazavi, S.M.J.; Daiee, E.; Yazdi, A.; Khiabani, K.; Kavousi, A.; Vazirinejad, R.; Behnejad, B.; Ghasemi, M.; Mood, M. Balali

    2008-01-01

    Background: Mercury or Hydrargyrum (Hg) is the most non-radioactive toxic element. Dental amalgam is made up of 50% mercury. Exposure to electromagnetic fields of magnetic resonance imaging (MRI) and microwave radiation emitted from mobile phone use may increase the emission of mercury from dental amalgam fillings. It was thus aimed to study the effects of exposure to MRI and mobile phone use on the mercury release from dental amalgam restorations. Materials and Methods: Following approval of the University Medical Ethics Committee and the informed consents of the subjects, two different studies were undertaken. A-MRI: - Thirty patients (27 F, 3 M) aged 18 to 48 years who had been referred to MRI department of Ali-ebn Abitaleb Teaching Hospital and had at least four amalgam restorated teeth, were investigated. Five ml stimulated saliva was collected just before and after MRI. The magnetic flux density was 0.23 T, and the duration of exposure of patients to magnetic field was 30 minutes. B-Mobile phone Use: Fourteen female healthy University students aged 19-23 years, who had not used mobile phones before the study and did not have any previous amalgam restorations but had decays in at least four teeth were investigated. Their urine samples were collected before amalgam restoration, and at days 1, 2, 3 and 4 after restoration. Dental amalgam restoration was performed for all 14 students (2 molars on one side, one class I and one class II restorations with identical volume and surface area of the amalgam fillings). The students randomly divided into two equal groups. The test group students were exposed to microwave radiation emitted from a Nokia 3310 mobile phone (SAR=0.96 W kg -1 ) that was operated in talk mode for 15 min every day at days 1-4 after restoration. The other seven female age matched students who served as controls sham exposed to microwave radiation. For each subject, a questionnaire regarding their possible sources of exposure to electromagnetic

  14. Real-time measurement of dentinal fluid flow during amalgam and composite restoration.

    Science.gov (United States)

    Kim, Sun-Young; Ferracane, Jack; Kim, Hae-Young; Lee, In-Bog

    2010-04-01

    This study examined changes in the dentinal fluid flow (DFF) during restorative procedures and compared permeability after restoration among restorative materials and adhesives. A class 1 cavity was prepared and restored with either amalgam (Bestaloy), or composite (Z-250) with one of two etch-and-rinse adhesives (Scotchbond MultiPurpose: MP and Single Bond 2: SB) or one of two self-etch adhesives (Clearfil SE Bond: CE and Easy Bond: EB) on an extracted human third molar which was connected to a sub-nanoliter fluid flow measuring device (NFMD) under 20 cm water pressure. DFF was measured from the intact tooth state through the restoration procedures to 30 min after restoration, and re-measured at 3 and 7 days post-restoration. Inward flow during cavity preparation was followed by outward flow after preparation. In amalgam restoration, the outward flow changed into an inward flow during amalgam filling, which was followed by a slight outward flow after finishing. In composite restoration, MP and SB showed an inward flow and outward flow for the rinsing and drying steps, respectively. Application of a hydrophobic bonding resin in the MP and CE systems caused a decrease in the flow rate. Air-drying of solvent for the CE and EB systems caused a sudden outward flow, whereas light-curing of the adhesive and composite caused an abrupt inward flow. Each restorative step clearly changed the direction and the rate of the DFF during restoration, which could be well identified with NFMD. Copyright 2010 Elsevier Ltd. All rights reserved.

  15. Recovery of silver residues from dental amalgam.

    Science.gov (United States)

    Pereira, Heloísa Aparecida Barbosa da Silva; Iano, Flávia Godoy; da Silva, Thelma Lopes; de Oliveira, Rodrigo Cardoso; de Menezes, Manoel Lima; Buzalaf, Marília Afonso Rabelo

    2010-01-01

    Dental amalgam residues are probably the most important chemical residues generated from clinical dental practice because of the presence of heavy metals among its constituents, mainly mercury and silver. The purpose of this study was to develop an alternative method for the recovery of silver residues from dental amalgam. The residue generated after vacuum distillation of dental amalgam for the separation of mercury was initially diluted with 32.5% HNO3, followed by precipitation with 20% NaCl. Sequentially, under constant heating and agitation with NaOH and sucrose, the sample was reduced to metallic silver. However, the processing time was too long, which turned this procedure not viable. In another sequence of experiments, the dilution was accomplished with concentrated HNO3 at 90 degrees C, followed by precipitation with 20% NaCl. After washing, the pellet was diluted with concentrated NH4OH, water and more NaCl in order to facilitate the reaction with the reducer. Ascorbic acid was efficiently used as reducer, allowing a fast reduction, thus making the procedure viable. The proposed methodology is of easy application and does not require sophisticated equipment or expensive reagents.

  16. Recovery of silver residues from dental amalgam

    Directory of Open Access Journals (Sweden)

    Heloísa Aparecida Barbosa da Silva Pereira

    2010-04-01

    Full Text Available Dental amalgam residues are probably the most important chemical residues generated from clinical dental practice because of the presence of heavy metals among its constituents, mainly mercury and silver. OBJECTIVE: The purpose of this study was to develop an alternative method for the recovery of silver residues from dental amalgam. MATERIAL AND METHODS: The residue generated after vacuum distillation of dental amalgam for the separation of mercury was initially diluted with 32.5% HNO3, followed by precipitation with 20% NaCl. Sequentially, under constant heating and agitation with NaOH and sucrose, the sample was reduced to metallic silver. However, the processing time was too long, which turned this procedure not viable. In another sequence of experiments, the dilution was accomplished with concentrated HNO3 at 90ºC, followed by precipitation with 20% NaCl. After washing, the pellet was diluted with concentrated NH4OH, water and more NaCl in order to facilitate the reaction with the reducer. RESULTS: Ascorbic acid was efficiently used as reducer, allowing a fast reduction, thus making the procedure viable. CONCLUSIONS: The proposed methodology is of easy application and does not require sophisticated equipment or expensive reagents.

  17. Radiopacities in dentine under amalgam restorations.

    Science.gov (United States)

    Rudolphy, M P; van Amerongen, J P; ten Cate, J M

    1994-01-01

    Radiopacities, caused by tin or zinc deposits in partly demineralized dental tissue, are frequently seen under amalgam restorations. The aim of this study was to determine to what extent these radiopaque areas could be identified by Caries Detector (1% acid red in propylene glycol) which is claimed to stain the irreversibly demineralized dentine. Twenty-eight extracted teeth showing radiopacities under amalgam fillings were selected. The restorations were removed, and Caries Detector was applied. Caries was excavated until the dentine did no longer stain with the Caries Detector. Standardized radiographs were taken at different stages. In all teeth the radiopaque areas stained with the Caries Detector. Visual inspection of the radiographs, taken after excavation, revealed that the radiopacities had disappeared completely in 6 teeth; in 5 teeth a very small part of the radiopaque area remained; in 17 teeth the cavity floor appeared as a thin white line on X-ray. Overall, line scan analysis confirmed the data obtained by visual observation. The residual radiopacities and radiopaque lines were a very small fraction of the initial radiopacities. Therefore, it is concluded that the radiopaque zone under amalgam fillings represents almost entirely an area of irreversibly demineralized dentine as indicated by the Caries Detector.

  18. [Creep of amalgam fillings under clasp rests].

    Science.gov (United States)

    Borchers, L; Jung, T; West, M

    1989-10-01

    A clinically realistic experiment was set up to obtain information on the amount of vertical settling of clasp rests in amalgam restorations under functional loading. Mesioocclusal cavities were prepared in 16 lower molar specimens cast in brass. The cavities were filled with amalgam and provided with a mesial rest seat. A constant load of 100 N was applied via a simplified (experimental) saddle to a cobalt-chromium E-clasp cast to the saddle. The duration of the load corresponded to 160 days of clinical function. The chronological course of vertical displacement was analyzed mathematically. According to this result the process can be divided into three components: settling immediately upon load initiation (mean value 96 microns, transition creep (mean value 25 microns) and creep ata constant rate (mean value 15 microns). The mean overall vertical displacement of the rests was 136 microns, the maximum value 287 microns. These findings suggest that vertical settling of a clasp rest into its seat in an amalgam restoration may eventually result in significant changes in occlusion and may almost completely exhaust gingival resilience.

  19. Evaluation of hydrogen bond networks in cellulose Iβ and II crystals using density functional theory and Car-Parrinello molecular dynamics.

    Science.gov (United States)

    Hayakawa, Daichi; Nishiyama, Yoshiharu; Mazeau, Karim; Ueda, Kazuyoshi

    2017-09-08

    Crystal models of cellulose Iβ and II, which contain various hydrogen bonding (HB) networks, were analyzed using density functional theory and Car-Parrinello molecular dynamics (CPMD) simulations. From the CPMD trajectories, the power spectra of the velocity correlation functions of hydroxyl groups involved in hydrogen bonds were calculated. For the Iβ allomorph, HB network A, which is dominant according to the neutron diffraction data, was stable, and the power spectrum represented the essential features of the experimental IR spectra. In contrast, network B, which is a minor structure, was unstable because its hydroxymethyl groups reoriented during the CPMD simulation, yielding a different crystal structure to that determined by experiments. For the II allomorph, a HB network A is proposed based on diffraction data, whereas molecular modeling identifies an alternative network B. Our simulations showed that the interaction energies of the cellulose II (B) model are slightly more favorable than model II(A). However, the evaluation of the free energy should be waited for the accurate determination from the energy point of view. For the IR calculation, cellulose II (B) model reproduces the spectra better than model II (A). Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. The neglected Pt-N(sulfonamido) bond in Pt chemistry. New fluorophore-containing Pt(II) complexes useful for assessing Pt(II) interactions with biomolecules.

    Science.gov (United States)

    Christoforou, Anna Maria; Marzilli, Patricia A; Marzilli, Luigi G

    2006-08-21

    Treatment of cis-Pt(Me2SO)2Cl2 with DNSH-tren afforded [Pt(DNSH-tren)Cl]Cl and with DNSH-dienH, under increasingly more basic conditions, led to Pt(DNSH-dienH)Cl(2), Pt(DNSH-dien)Cl, and Pt(DNS-dien). (DNSH = 5-(dimethylamino)naphthalene-1-sulfonyl, linked via a sulfonamide group to tris(2-aminoethyl)amine (DNSH-tren) and diethylenetriamine (DNSH-dienH); the H's in DNSH-dienH designate protons sometimes lost upon Pt binding, i.e., sulfonamide NH for the dienH moiety and H8 for the DNSH moiety). Respectively, the three neutral DNSH-dienH-derived complexes are difunctional, monofunctional, and nonfunctional and exhibit decreasing fluorescence in this order as the dansyl group distance to Pt decreases. 2D NMR data establish that Pt(DNS-dien) has a Pt-C8 bond and a Pt-N(sulfonamido) bond. Pt(DNSH-dien)Cl and [Pt(DNSH-tren)Cl]Cl bind to N7 of 6-oxopurines (e.g., 5'-GMP, 3'-IMP, and 9-ethylguanine) and sulfur of methionine (met). Competition and challenge reactions for Pt(II) with met and 5'-GMP typically reveal that met binding is favored kinetically but that 5'-GMP binding is favored thermodynamically. This common type of behavior was found for [Pt(DNSH-tren)Cl]Cl. In contrast, Pt(DNSH-dien)Cl had reduced kinetic selectivity for met. This unusual behavior undoubtedly arises as a consequence of the bound Pt-N(sulfonamido) group, which donates strongly to Pt (as indicated by relatively upfield dien NH signals) and which places the bulky DNSH moiety close to the monofunctional reaction site. The decrease in the relatively upfield shifts of the DNSH group signals indicates that this group stacks with the purine. This stacking could explain the unprecedented, relatively low reactivity of a Pt complex bearing a dien-type ligand toward met vs 5'-GMP.

  1. [Dental amalgams and urine elimination of mercury in workers exposed to low concentrations of inorganic mercury].

    Science.gov (United States)

    Soleo, L; Pesola, G; Vimercati, L; Elia, G; Michelazzi, M; Gagliardi, T; Drago, I; Lasorsa, G

    1998-01-01

    The aim of the research was to assess the contribution of dental amalgams and other non-occupational factors of exposure to inorganic mercury (diet, etc.) to the quantity of mercury excreted with urine in workers exposed to low level concentrations of inorganic mercury. Two groups of workers (Groups I and II) were studied who were exposed to low and different environmental concentrations of inorganic mercury. These two groups were compared with a group of subjects not occupationally exposed to mercury in the same geographical area (Group III). All subjects were administered a questionnaire concerning personal data, lifestyle, recent removal and/or insertion of dental amalgam fillings, presence of nasal obstruction or bruxism and consumption of fish. The number of amalgam-filled teeth was established for each subject. Mean environmental exposure to inorganic mercury was 0.0087 mg/m3 for Group I and 0.0030 mg/m3 for Group II. Urinary excretion in the 3 groups was 4.2 +/- 2.8 micrograms/l for Group I, 3.0 +/- 2.1 micrograms/l for Group II and 1.6 +/- 1.2 micrograms/l for Group III. The results showed that of the factors of exposure to inorganic mercury, only occupational exposure (T = 9.18; p = 0.000) and the number of amalgam-filled teeth (T = 2.03; p = 0.043) were able to influence significantly urinary excretion of mercury; the sources of non-occupational exposure did not appear to play any role. The contribution of each amalgam filling to urinary mercury excretion was calculated to be 0.08 microgram/l. Occupational exposure therefore, even at low level doses, is still the main cause of urinary mercury excretion in workers exposed to inorganic mercury; of the non-occupational exposure factors, a significant role is played by amalgam dental fillings, whose contribution needs to be taken into consideration in order to make a correct interpretation of the results of biological monitoring of exposed workers.

  2. An amalgam tattoo causing local and systemic disease?

    Science.gov (United States)

    Weaver, T; Auclair, P L; Taybos, G M

    1987-01-01

    Amalgam tattoos are common oral lesions. The case presented here involved a 33-year-old woman who had had an amalgam tattoo for 2 years and complained of localized soreness and occasional swelling as well as systemic symptoms of weight loss, fatigue, sinusitis, and headaches. After excisional biopsy of the lesion, the patient's complaints ceased dramatically. It is suggested that alterations in healing due to the presence of amalgam particles led to systemic as well as local disease.

  3. Analytical Applications of Solid and Paste Amalgam Electrodes

    Czech Academy of Sciences Publication Activity Database

    Josypčuk, Bohdan; Barek, J.

    2009-01-01

    Roč. 39, č. 3 (2009), s. 189-203 ISSN 1040-8347 R&D Projects: GA ČR GA203/07/1195; GA AV ČR IAA400400806; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40400503 Keywords : solid amalgam electrodes * voltammetry * paste amalgam electrodes * reference amalgam electrodes Subject RIV: CG - Electrochemistry Impact factor: 2.621, year: 2009

  4. Optimizing the procedure for mercury recovery from dental amalgam

    OpenAIRE

    Iano, Flávia Godoy; Santos Sobrinho, Ovídio dos; Silva, Thelma Lopes da; Pereira, Marlus Alves; Figueiredo, Paulo Jorge Moraes; Alberguini, Leny Borghesan Albertini; Granjeiro, José Mauro

    2008-01-01

    Mercury, as any other heavy metal, may cause environmental damages due to its accumulation and biotransformation. Dental offices, whether private or institutional, use dental amalgam as a restorative material on a daily basis. Dental amalgam is composed of mercury (50%), silver (30%) and other metals. Approximately 30% of the amalgam prepared in dental offices (0.6 g per capsule) are wasted and inadequately discarded without any treatment. Methods for mercury recovery have been proposed previ...

  5. Mercury release from dental amalgams into continuously replenished liquids.

    Science.gov (United States)

    Okabe, T; Elvebak, B; Carrasco, L; Ferracane, J L; Keanini, R G; Nakajima, H

    2003-01-01

    Studies have been performed using high- and low-copper amalgams to measure the amounts of mercury dissolution from dental amalgam in liquids such as artificial saliva; however, in most cases, mercury dissolution has been measured under static conditions and as such, may be self-limiting. This study measured the mercury release from low- and high-copper amalgams into flowing aqueous solutions to determine whether the total amounts of dissolution vary under these conditions when tested at neutral and acidic pH. High- and low-copper amalgam specimens were prepared and kept for 3 days. They were then longitudinally suspended in dissolution cells with an outlet at the bottom. Deionized water or acidic solution (pH1) was pumped through the cell. Test solutions were collected at several time periods up to 6 days or 1 month and then analyzed with a cold vapor atomic absorption spectrophotometer. After dissolution testing, the specimens were examined using SEM/XEDA for any selective degradation of the phases in the amalgam. Except for the high-copper amalgam in the pH1 solution, the dissolution rates were found to decrease exponentially with time. The rate for the high-copper amalgam in pH1 solution slowly increased for 1 month. The total amounts (microgram/cm(2)) of mercury released over 6 days or 1 month from both types of amalgam in deionized water were not significantly different (p>/=0.05). The high-copper amalgam released significantly more mercury than the low-copper amalgam in the pH1 solution at both time periods. For both amalgams, the dissolution in pH1 was significantly higher than in deionized water. Mercury dissolution from amalgam under dynamic conditions is enhanced in an acidic media, and most prominently for a high-copper formulation.

  6. Renal effects of dental amalgam in children: the New England children's amalgam trial.

    Science.gov (United States)

    Barregard, Lars; Trachtenberg, Felicia; McKinlay, Sonja

    2008-03-01

    Mercury is nephrotoxic and dental amalgam is a source of mercury exposure. Children 6-10 years of age (n = 534) with two or more posterior teeth with caries but no prior amalgam restorations, were randomized to one of two treatments--amalgam or resin composite (white fillings)--used for caries treatment during 5 years of follow-up. The primary outcome was change in IQ, but important secondary outcomes were effects on markers of glomerular and tubular kidney function: urinary excretion of albumin, alpha-1-microglobulin (A1M), gamma-glutamyl transpeptidase (gamma-GT), and N-acetyl-beta-d-glucosaminidase (NAG). These markers were measured on several occasions during the trial, together with urinary mercury and covariates. We evaluated the results using repeated-measures analyses. There were no significant differences between treatment groups in average levels of renal biomarkers, nor significant effects of number of dental amalgams on these markers. There was, however, a significantly increased prevalence of microalbuminuria (MA) among children in the amalgam group in years 3-5 (adjusted odds ratio 1.8; 95% confidence interval, 1.1-2.9). Most of these cases are likely to be temporary MA, but 10 children in the amalgam group had MA in both years 3 and 5, versus 2 children in the composite group (p = 0.04). There were no differences in the occurrence of high levels of renal tubular markers (A1M, gamma-GT, or NAG). The increase in MA may be a random finding, but should be tested further. The results did not support recent findings in an observational study of an effect of low-level mercury on tubular biomarkers in children.

  7. Removal of dental amalgam decreases anti-TPO and anti-Tg autoantibodies in patients with autoimmune thyroiditis.

    Science.gov (United States)

    Sterzl, Ivan; Prochazkova, Jarmila; Hrda, Pavlina; Matucha, Petr; Bartova, Jirina; Stejskal, Vera

    2006-12-01

    The impact of dental amalgam removal on the levels of anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-Tg) antibodies was studied in patients with autoimmune thyroiditis (AT) with and without mercury allergy. Thirty-nine patients with AT were tested by an optimized lymphocyte proliferation test MELISA for allergy (hypersensitivity) to inorganic mercury. Patients were divided into two groups: Group I (n = 12) with no hypersensitivity to mercury and Group II (n = 27) with hypersensitivity to mercury. Amalgam fillings were removed from the oral cavities of 15 patients with hypersensitivity to mercury (Group IIA) and left in place in the remaining 12 patients (Group IIB). The laboratory markers of AT, anti-TPO and anti-Tg autoantibodies, were determined in all groups at the beginning of the study and six months later. Compared to levels at the beginning of the study, only patients with mercury hypersensitivity who underwent amalgam replacement (Group IIA) showed a significant decrease in the levels of both anti-Tg (p=0.001) and anti-TPO (p=0.0007) autoantibodies. The levels of autoantibodies in patients with or without mercury hypersensitivity (Group I and Group IIB) who did not replace amalgam did not change. Removal of mercury-containing dental amalgam in patients with mercury hypersensitivity may contribute to successful treatment of autoimmune thyroiditis.

  8. Structural effects of the lone pair on lead(II), and parallels with the coordination geometry of mercury(II). Does the lone pair on lead(II) form H-bonds? Structures of the lead(II) and mercury(II) complexes of the pendant-donor macrocycle DOTAM (1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane).

    Science.gov (United States)

    Hancock, Robert D; Reibenspies, Joseph H; Maumela, Hulisani

    2004-05-03

    The synthesis and structures of [Pb(DOTAM)](ClO4)2.4.5H2O (1) and [Hg(DOTAM)](ClO4)2.0.5CH3OH.1.5H2O (2) are reported, where DOTAM is 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane. Compound 1 is triclinic, space group P, a = 12.767(3) A, b = 13.528(2) A, c = 18.385(3) A, alpha = 101.45(2) degrees, beta = 93.32(2) degrees, gamma = 90.53(2) degrees, Z = 4, R = 0.0500. Compound 2 is monoclinic, space group Cc, a = 12.767(3) A, b = 13.528(2) A, c = 18.385(3) A, beta = 101.91(2) degrees, Z = 4, R = 0.0381. The Pb(II) ion in 1 has an average Pb-N = 2.63 A to four N-donors from the macrocyclic ring, and four O-donors (average Pb-O = 2.77 A) from the amide pendant donors of the macrocycle, with a water molecule placed with Pb-O = 3.52 A above the proposed site of the lone pair (Lp) on Pb. The Hg(II) in 2 appears to be only six-coordinate, with four Hg-N bond lengths averaging 2.44 A, and two Hg-O from pendant amide donors at 2.41 A. The other two amide donors appear to be noncoordinating, with Hg-O distances of 2.74 and 2.82 A. A water situated 3.52 A above the proposed site of the lone pair on Pb(II) in 1 is oriented in such a way that it might be thought to be forming a Pb-Lp.H-O-H hydrogen bond. It is concluded that that this is not an H-bond, but that the presence of the lone pair allows a closer approach of the hydrogens to Pb than would be true otherwise. The structural analogy in the VSEPR sense between Pb(II), which has the 5d(10)6s(2) outer electron structure, and the Hg(II) ion, which has the 5d10 structure, is examined. The tendency of Hg(II) toward linear coordination, with two short Hg-L bonds (L = ligand) at 180 degrees to each other, and other donor groups at roughly 90 degrees to this and at much longer bond distances, is paralleled by Pb(II). One of the short Hg-L bonds is replaced in the Pb(II) structures by the lone pair (Lp), which is opposite the short Pb-L bond, or in some cases 2-4 shorter Pb-L bonds.

  9. Ions released from dental amalgams in contact with titanium.

    Science.gov (United States)

    Lim, Shi-Duk; Takada, Yukyo; Kim, Kyo-Han; Okuno, Osamu

    2003-03-01

    The ions released from conventional and high-copper amalgams in contact with titanium were quantitatively analyzed in a 0.9% NaCl solution at 37 degrees C when the surface area ratio of titanium/amalgam was set up as 1/10, 1/1, or 10/1. The corrosion potentials of the amalgams and titanium were measured under the same conditions. Surface analyses on the amalgams were also employed using SEM with WDS. Though the potential of the conventional amalgam was always lower than that of titanium, that of the high-copper amalgam was reversed during the early stage of immersion and remained lower. When the surface area ratio of titanium grew at 10/1, tin and copper ions released from the conventional and high-copper amalgam, respectively, increased significantly compared with those of each amalgam that was not in contact with titanium. The galvanic corrosion in such a large surface area of titanium possibly led to the heavy corrosion of the amalgams.

  10. Marginal microhardness of corroded amalgams: a comparative in vitro study.

    Science.gov (United States)

    Patsurakos, A; Moberg, L E

    1990-08-01

    One conventional and two high-Cu amalgams were tested for marginal microhardness after 2 months' corrosion in an 85 mM NaCl solution. Amalgams immersed in 200 mM phosphate buffer solution were used as controls. The microhardness tests were conducted on cross-sections of the amalgams 50 microns from the surface edges. The microstructure of the amalgams was studied in SEM and the amounts of Sn, Cu, Zn, Ag, and Hg dissolved in the solutions were analyzed with an atomic absorption spectrophotometer. For the amalgams immersed in the NaCl solution the depth of corrosion after 2 months was between 50 and 400 microns. The specimens immersed in the phosphate solution showed no signs of subsurface corrosion. The marginal microhardness of all the amalgams was reduced after corrosion in the NaCl solution. The greatest microhardness in both the uncorroded and corroded states was shown in the two high-Cu amalgams. The reduction in marginal microhardness after corrosion can probably be attributed mainly to degradation of the gamma-2 phase for the conventional amalgam and to degradation of the eta' phase for the two high-Cu amalgams.

  11. Evaluating and comparison between wear behavior of dental Amalgam

    Directory of Open Access Journals (Sweden)

    Fathi MH

    1999-06-01

    Full Text Available Wear characteristics of dental amalgams were investigated by in vivo and in vitro tests. Wear"nof dental amalgam was studied and evaluated using a three - body abrasion test and Pin-On-Disk"nmethod. Porcelain was used for preparing disk and materials such as toothpaste, artificial saliva and"nnaturally saliva were used as the third material that was contributed in tribologic system"nThe results showed that effects of various toothpastes on the wear of dental amalgam are considerably"ndifferent and size, shape and chemical composition of amalgam are important too.

  12. A comparative survey on the increased fracture resistance of amalgam restored teeth using three types of Glass Ionomer as adhesive liners

    Directory of Open Access Journals (Sweden)

    Shafiee F.

    2004-08-01

    Full Text Available Statement of Problem: Because dental amalgam does not adhere to tooth structure, using adhesive cements in amalgam-bonded restorations have been increased. Purpose: The goal of this in-vitro study was to compare the effects of three types of glass ionomer as adhesive liners as well as varnish liner in increasing fracture resistance of teeth restored with amalgam. Materials and Methods: Seventy extracted human maxillary premolars were selected and MOD cavities were prepared on them excluding ten intact teeth as positive control group and ten cavity prepared teeth without restoration as negative control group. All the prepared teeth were then restored with spherical amalgam (gs.80 with one of the following liners silver alloy glass ionomer liner, conventional glass ionomer liner, varnish liner, resin-modified glass ionomer and resin-modified glass ionomer with delayed light curing. The teeth were stored in 37C distilled water for 7 days and were then loaded under compressive strength using an Instron testing machine. The force required to fracture teeth were recorded and the data were analyzed statistically using ANOVA and Tukey HSD tests. Results: Statistically significant differences were observed in fracture resistance between restored and non-restored samples. Comparisons between groups attributed significant effects to resin-modified glass ionomer in increasing fracture resistance of amalgam restored teeth (P<0.05. In most specimens, one cusp was separated from tooth structure whereas amalgam remained bonded to the intact cusp. Conclusion: According to these findings, resin-modified glass ionomer put a statistically significant effect in fracture resistance of amalgam-restored teeth.

  13. Dental Amalgam Restorations and Children’s Neuropsychological Function: The New England Children’s Amalgam Trial

    OpenAIRE

    Bellinger, David C.; Daniel, David; Trachtenberg, Felicia; Tavares, Mary; McKinlay, Sonja

    2006-01-01

    Background: A concern persists that children’s exposure to mercury vapor from dental amalgams produces neurotoxicity. Objective: Our goal was to compare the neuropsychological function of children, without prior exposure to dental amalgam, whose caries were repaired using either dental amalgam or mercury-free composite materials. Methods: We conducted a randomized controlled trial involving 534 6- to 10-year-old urban and rural children who were assessed yearly for 5 years using a battery of ...

  14. Effect of composite/amalgam thickness on fracture resistance of maxillary premolar teeth, restored with combined amalgam-composite restorations

    OpenAIRE

    Firouzmandi, Maryam; Doozandeh, Maryam; Jowkar, Zahra; Abbasi, Sanaz

    2016-01-01

    Background Combined amalgam-composite restorations have been used through many years to benefit from the advantages of both dental amalgam and composite resin. Two variations have been mentioned for this technique, this study investigated the fracture resistance of maxillary premolar teeth with extended mesio-occluso-distal (MOD) cavities, restored with the two variations of combined amalgam-composite restorations. Material and Methods Sixty intact extracted premolar teeth were randomly divid...

  15. Rh2(II)-catalyzed intramolecular aliphatic C-H bond amination reactions using aryl azides as the N-atom source.

    Science.gov (United States)

    Nguyen, Quyen; Sun, Ke; Driver, Tom G

    2012-05-02

    Rhodium(II) dicarboxylate complexes were discovered to catalyze the intramolecular amination of unactivated primary, secondary, or tertiary aliphatic C-H bonds using aryl azides as the N-atom precursor. While a strong electron-withdrawing group on the nitrogen atom is typically required to achieve this reaction, we found that both electron-rich and electron-poor aryl azides are efficient sources for the metal nitrene reactive intermediate. © 2012 American Chemical Society

  16. Rh2(II)-Catalyzed Intramolecular Aliphatic C–H Bond Amination Reactions Using Aryl Azides as the N-Atom Source

    Science.gov (United States)

    Nguyen, Quyen; Sun, Ke; Driver, Tom G.

    2012-01-01

    Rhodium(II) dicarboxylate complexes were discovered to catalyze the intramolecular amination of unactivated primary-, secondary-, or tertiary aliphatic C–H bonds using aryl azides as the N-atom precursor. While a strong electron-withdrawing group on the nitrogen atom is typically required to achieve this reaction, we found that both electron-rich- and electron-poor aryl azides are efficient sources for the metal nitrene reactive intermediate. PMID:22519742

  17. Patients' experiences of changes in health after removal of dental amalgam - quantitative and qualitative approaches

    OpenAIRE

    Sjursen, Therese Thornton

    2016-01-01

    Patients with medically unexplained health complaints attributed to dental amalgam often wish to have their amalgam fillings replaced with other materials. The main purpose of this thesis was to explore how patients with health complaints attributed to dental amalgam experienced changes in health after removal of all amalgam fillings. Forty patients with health complaints attributed to dental amalgam were included and assigned to a treatment group (n=20; amalgam removal) and a reference gr...

  18. Health Complaints Attributed to Dental Amalgam: A Retrospective Survey Exploring Perceived Health Changes Related to Amalgam Removal.

    Science.gov (United States)

    Kristoffersen, Agnete Egilsdatter; Alræk, Terje; Stub, Trine; Hamre, Harald Johan; Björkman, Lars; Musial, Frauke

    2016-01-01

    Many patients have complex health complaints they attribute to dental amalgam. There is some evidence of symptom relief after removal of amalgam. The aims of this study were to assess the total symptom load in patients with all their amalgam fillings removed, and to investigate the self-reported improvement of health with regard to precautions taken under amalgam removal and time since removal. The survey was distributed to all members (n=999) of the Norwegian Dental patients association in 2011. The study participants returned the questionnaires anonymously by means of a pre-stamped envelope. The questionnaire asked for sociodemographic data, subjectively perceived health status, complaints persisting after amalgam removal and self-reported changes in symptoms after amalgam removal. A total of 324 participants were included in the study. The majority of the participants reported improved health after amalgam removal, even though the mean degree of severity of complaints was still high. Exhaustion and musculoskeletal complaints were most severe, and reflects the fact that 38% of the participants reported poor to very poor current health. With regard to amalgam removal, associations between improved health, number of precautions applied, and time since removal were found. Most of the participants in this study reported improvement of health after amalgam removal even though they still suffered a high complaint load. Since absolute symptom load is a robust predictor for general health outcome and socioeconomic burden for society, a possible intervention, which enables patients to further improve their health status is desirable.

  19. [Amalgam tattoo--an important differential diagnosis from malignant melanoma of the mouth mucosa].

    Science.gov (United States)

    Tolsdorff, P; Schützenberger, K H

    1991-09-01

    Amalgam tattoos develop as an amalgam deposit often as a result of continuous contact between an amalgam filling and the gingiva or amalgam fragments embedded in the oral tissue during dental filling or surgical operations. Sometimes fragments of amalgam restorations are broken off during extraction and embed in the adjacent soft tissue. In our case a small piece of amalgam had broken off during an extraction after retrograde filling up this tooth some years before following a resection of the dental root. Embedded in the depth of the bony resection cavity the piece of amalgam had produced the amalgam tattoo 13 years later.

  20. Fac and mer isomers of Ru(II) tris(pyrazolyl-pyridine) complexes as models for the vertices of coordination cages: structural characterisation and hydrogen-bonding characteristics.

    Science.gov (United States)

    Metherell, Alexander J; Cullen, William; Stephenson, Andrew; Hunter, Christopher A; Ward, Michael D

    2014-01-07

    We have prepared a series of mononuclear fac and mer isomers of Ru(II) complexes containing chelating pyrazolyl-pyridine ligands, to examine their differing ability to act as hydrogen-bond donors in MeCN. This was prompted by our earlier observation that octanuclear cube-like coordination cages that contain these types of metal vertex can bind guests such as isoquinoline-N-oxide (K = 2100 M(-1) in MeCN), with a significant contribution to binding being a hydrogen-bonding interaction between the electron-rich atom of the guest and a hydrogen-bond donor site on the internal surface of the cage formed by a convergent set of CH2 protons close to a 2+ metal centre. Starting with [Ru(L(H))3](2+) [L(H) = 3-(2-pyridyl)-1H-pyrazole] the geometric isomers were separated by virtue of the fact that the fac isomer forms a Cu(I) adduct which the mer isomer does not. Alkylation of the pyrazolyl NH group with methyl iodide or benzyl bromide afforded [Ru(L(Me))3](2+) and [Ru(L(bz))3](2+) respectively, each as their fac and mer isomers; all were structurally characterised. In the fac isomers the convergent group of pendant -CH2R or -CH3 protons defines a hydrogen-bond donor pocket; in the mer isomer these protons do not converge and any hydrogen-bonding involving these protons is expected to be weaker. For both [Ru(L(Me))3](2+) and [Ru(L(bz))3](2+), NMR titrations with isoquinoline-N-oxide in MeCN revealed weak 1 : 1 binding (K ≈ 1 M(-1)) between the guest and the fac isomer of the complex that was absent with the mer isomer, confirming a difference in the hydrogen-bond donor capabilities of these complexes associated with their differing geometries. The weak binding compared to the cage however occurs because of competition from the anions, which are free to form ion-pairs with the mononuclear complex cations in a way that does not happen in the cage complexes. We conclude that (i) the presence of fac tris-chelate sites in the cage to act as hydrogen-bond donors, and (ii

  1. Development of strength in dental silver amalgam.

    Science.gov (United States)

    Darvell, B W

    2012-10-01

    To characterize the development of strength during the setting process of dental silver amalgam in the context of 'early strength' measurements for standards compliance testing in relation to patient instructions, and demonstrate the applicability of the Hertzian 'ball on disc' method. Sixteen dental silver amalgam products were tested using the 'ball on disc' protocol at 1, 2, 3, 4 and 24h after setting at 37°C in air. The mixed materials were packed into a tapered steel disc mold (10mm diameter, 3mm thick) resting on a glass surface, slightly overfilled and carved level with a sharp edge, then ejected at ∼10min and placed immediately into an incubator at 37°C. Testing was in Hertzian mode, using a 20mm steel ball, with the specimen resting on a disc of glass-filled polyamide (E=10GPa) at a cross-head speed of 0.2mm/min on a universal testing machine (E3000, Instron). The load at first crack was recorded, as was the number of radial cracks produced. Radial cracking into 2-5 pieces, in a clinically-relevant (non-explosive) mode was observed in all cases. Considerable variation in setting rate between products, as indicated by the development of load at failure with time, was found. The distribution of normalized failure load values overall was lognormal (Weibull was excluded). The RMS coefficient of variation overall was 12.4%. The ball-on-disc test provides a facile, relevant measure of the strength of dental silver amalgam, and is viable as a standards compliance test. Early strength testing at a minimum of 2h is suggested. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  2. A Safe Protocol for Amalgam Removal

    Science.gov (United States)

    Colson, Dana G.

    2012-01-01

    Today's environment has different impacts on our body than previous generations. Heavy metals are a growing concern in medicine. Doctors and individuals request the removal of their amalgam (silver mercury) restorations due to the high mercury content. A safe protocol to replace the silver mercury filling will ensure that there is minimal if any absorption of materials while being removed. Strong alternative white composite and lab-processed materials are available today to create a healthy and functioning mouth. Preparation of the patient prior to the procedure and after treatment is vital to establish the excretion of the mercury from the body. PMID:22315627

  3. Determination of light elements in amalgam restorations

    International Nuclear Information System (INIS)

    Hanson, A.L.; Jones, K.W.; Kraner, H.W.; Osborne, J.W.; Nelson, G.V.

    1982-01-01

    Rutherford backscattering has been used to measure the major elemental compositions in the near-surface regions of freshly prepared and used samples of dental amalgam. A depletion from bulk stoichiometry of the major elements, which indicates an accumulation of lighter elements on the surface of the materials, has been observed. Increases in the F, Na, Cl, P, O, C, and N concentrations between freshly prepared samples and used samples were measured by observation of gamma rays produced by proton and deuteron induced reactions

  4. A Safe Protocol for Amalgam Removal

    Directory of Open Access Journals (Sweden)

    Dana G. Colson

    2012-01-01

    Full Text Available Today's environment has different impacts on our body than previous generations. Heavy metals are a growing concern in medicine. Doctors and individuals request the removal of their amalgam (silver mercury restorations due to the high mercury content. A safe protocol to replace the silver mercury filling will ensure that there is minimal if any absorption of materials while being removed. Strong alternative white composite and lab-processed materials are available today to create a healthy and functioning mouth. Preparation of the patient prior to the procedure and after treatment is vital to establish the excretion of the mercury from the body.

  5. 12-year survival of composite vs. amalgam restorations.

    NARCIS (Netherlands)

    Opdam, N.J.M.; Bronkhorst, E.M.; Loomans, B.A.C.; Huysmans, M.C.D.N.J.M.

    2010-01-01

    Information about the long-term clinical survival of large amalgam and composite restorations is still lacking. This retrospective study compares the longevity of three- and four-/five-surface amalgam and composite restorations relative to patients' caries risk. Patient records from a general

  6. Recovery of mercury from dental amalgam scrap-Indian perspective

    Directory of Open Access Journals (Sweden)

    Kadandale Sadasiva

    2017-01-01

    Full Text Available Aim: The aim is to recycle mercury from dental amalgam scrap using the vacuum distillation method. Materials and Methods: A total of 150 g of dental amalgam scrap was taken in a round bottom flask and was subjected to vacuum distillation at 398°C. The vapor of mercury was collected in another round bottom flask. Observation: The procedure is carried out for mercury recovery using vacuum distillation apparatus, and mercury vapor are collected in a round bottom flask, and the silver is recovered using sucrose as reducing agent. Using 150 g of dental amalgam scrap 50%–80% of silver are recovered, and silver has a purity of 70%–80%. However, the total time required in the reduction process ranged between 303 and 600 min. Conclusion: Mercury could be recycled from dental amalgam scrap through vacuum distillation method at 398°C and its implication of dental amalgam scrap in an Indian perspective.

  7. Effects of bleaching on mercury ion release from dental amalgam.

    Science.gov (United States)

    Al-Salehi, S K

    2009-03-01

    The chemical reactions that take place at the amalgam surface when exposed to bleaching agents are not well-understood. It is known, however, that mercury ions are released from dental amalgam when bleached. We hypothesized that increasing concentrations of hydrogen peroxide are more effective than water at increasing mercury ion release from dental amalgam. We prepared dental amalgam discs (n = 65) by packing amalgam into cylindrical plastic molds and divided them into 13 equal groups of 5 discs each. The discs in each group were individually immersed in either 0%, 3.6%, 6%, or 30% (w/v) hydrogen peroxide at exposure periods of 1, 8, 48, and 168 hrs. Samples were taken for mercury ion release determination by inductively coupled plasma mass spectrometry. There were significant increases in mercury release between control and all other hydrogen peroxide concentrations at all exposure times (p < 0.05).

  8. Recovery of Mercury from Dental Amalgam Scrap-Indian Perspective.

    Science.gov (United States)

    Sadasiva, Kadandale; Rayar, Sreeram; Manu, Unnikrishnan; Senthilkumar, Kumarappan; Daya, Srinivasan; Anushaa, Nagarajan

    2017-11-01

    The aim is to recycle mercury from dental amalgam scrap using the vacuum distillation method. A total of 150 g of dental amalgam scrap was taken in a round bottom flask and was subjected to vacuum distillation at 398°C. The vapor of mercury was collected in another round bottom flask. The procedure is carried out for mercury recovery using vacuum distillation apparatus, and mercury vapor are collected in a round bottom flask, and the silver is recovered using sucrose as reducing agent. Using 150 g of dental amalgam scrap 50%-80% of silver are recovered, and silver has a purity of 70%-80%. However, the total time required in the reduction process ranged between 303 and 600 min. Mercury could be recycled from dental amalgam scrap through vacuum distillation method at 398°C and its implication of dental amalgam scrap in an Indian perspective.

  9. Effect of Pd and In on mercury evaporation from amalgams.

    Science.gov (United States)

    Okabe, T; Ohmoto, K; Nakajima, H; Woldu, M; Ferracane, J L

    1997-12-01

    The amount of Hg vapor released from "synthesized" gamma 1 with 1% (wt) Pd was reported to be less than 30% of that from gamma 1 with no Pd. This study tested the hypothesis that Hg evaporation from Pd-containing amalgams decreases with Pd concentration and that In also reduces Hg vapor. Specimens (4 mm dia, 8 mm long) were prepared by triturating Ag-Sn(25%)-Cu(12%) alloy powder containing 0.5-9.0% Pd with pure Hg and by triturating 3% Pd alloy powder with Hg containing 1-5% In (all residual Hg approximately equal to 62%). The total amount (ng/mm2) of Hg vapor released at 37 degrees C from freshly prepared amalgams was measured. Pd (3-9%) in the powder significantly (p amalgams during setting. Use of In-containing Hg also reduced Hg vapor release (5% In, p amalgam appear to work together to reduce Hg vaporization from these amalgams.

  10. Bifunctional RuII -Complex-Catalysed Tandem C-C Bond Formation: Efficient and Atom Economical Strategy for the Utilisation of Alcohols as Alkylating Agents.

    Science.gov (United States)

    Roy, Bivas Chandra; Chakrabarti, Kaushik; Shee, Sujan; Paul, Subhadeep; Kundu, Sabuj

    2016-12-12

    Catalytic activities of a series of functional bipyridine-based Ru II complexes in β-alkylation of secondary alcohols using primary alcohols were investigated. Bifunctional Ru II complex (3 a) bearing 6,6'-dihydroxy-2,2'-bipyridine (6DHBP) ligand exhibited the highest catalytic activity for this reaction. Using significantly lower catalyst loading (0.1 mol %) dehydrogenative carbon-carbon bond formation between numerous aromatic, aliphatic and heteroatom substituted alcohols were achieved with high selectivity. Notably, for the synthesis of β-alkylated secondary alcohols this protocol is a rare one-pot strategy using a metal-ligand cooperative Ru II system. Remarkably, complex 3 a demonstrated the highest reactivity compared to all the reported transition metal complexes in this reaction. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Domination Number of Vertex Amalgamation of Graphs

    Science.gov (United States)

    Wahyuni, Y.; Utoyo, M. I.; Slamin

    2017-06-01

    For a graph G = (V, E), a subset S of V is called a dominating set if every vertex x in V is either in S or adjacent to a vertex in S. The domination number γ ( G ) is the minimum cardinality of the dominating set of G. The dominating set of G with a minimum cardinality denoted by γ ( G )-set. Let G 1, G 2, …, Gt be subgraphs of the graph G. If the union of all these subgraphs is G and their intersection is {v}, then we say that G is the vertex-amalgamation of G 1, G 2, …, Gt at vertex v. Based on the membership of the common vertex v in the γ ( Gi )-set, there exist three conditions to be considered. First, if v elements of every γ ( Gi )-set, second if there is no γ ( Gi )-set containing v, and third if either v is element of γ ( Gi )-set for 1 ≤ i ≤ p or there is no γ ( Gi )-set containing v for p amalgamation of G 1, G 2, …, Gt at vertex v can be determined.

  12. Neutron structure of human carbonic anhydrase II in complex with methazolamide: mapping the solvent and hydrogen-bonding patterns of an effective clinical drug

    Directory of Open Access Journals (Sweden)

    Mayank Aggarwal

    2016-09-01

    Full Text Available Carbonic anhydrases (CAs; EC 4.2.1.1 catalyze the interconversion of CO2 and HCO3−, and their inhibitors have long been used as diuretics and as a therapeutic treatment for many disorders such as glaucoma and epilepsy. Acetazolamide (AZM and methazolamide (MZM, a methyl derivative of AZM are two of the classical CA inhibitory drugs that have been used clinically for decades. The jointly refined X-ray/neutron structure of MZM in complex with human CA isoform II (hCA II has been determined to a resolution of 2.2 Å with an Rcryst of ∼16.0%. Presented in this article, along with only the second neutron structure of a clinical drug-bound hCA, is an in-depth structural comparison and analyses of differences in hydrogen-bonding network, water-molecule orientation and solvent displacement that take place upon the binding of AZM and MZM in the active site of hCA II. Even though MZM is slightly more hydrophobic and displaces more waters than AZM, the overall binding affinity (Ki for both of the drugs against hCA II is similar (∼10 nM. The plausible reasons behind this finding have also been discussed using molecular dynamics and X-ray crystal structures of hCA II–MZM determined at cryotemperature and room temperature. This study not only allows a direct comparison of the hydrogen bonding, protonation states and solvent orientation/displacement of AZM and MZM, but also shows the significant effect that the methyl derivative has on the solvent organization in the hCA II active site.

  13. The dental amalgam toxicity fear: a myth or actuality.

    Science.gov (United States)

    Rathore, Monika; Singh, Archana; Pant, Vandana A

    2012-05-01

    Amalgam has been used in dentistry since about 150 years and is still being used due to its low cost, ease of application, strength, durability, and bacteriostatic effect. When aesthetics is not a concern it can be used in individuals of all ages, in stress bearing areas, foundation for cast-metal and ceramic restorations and poor oral hygiene conditions. Besides all, it has other advantages like if placed under ideal conditions, it is more durable and long lasting and least technique sensitive of all restorative materials, but, concern has been raised that amalgam causes mercury toxicity. Mercury is found in the earth's crust and is ubiquitous in the environment, so even without amalgam restorations everyone is exposed to small but measurable amount of mercury in blood and urine. Dental amalgam restorations may raise these levels slightly, but this has no practical or clinical significance. The main exposure to mercury from dental amalgam occurs during placement or removal of restoration in the tooth. Once the reaction is complete less amount of mercury is released, and that is far below the current health standard. Though amalgam is capable of producing delayed hypersensitivity reactions in some individuals, if the recommended mercury hygiene procedures are followed the risks of adverse health effects could be minimized. For this review the electronic databases and PubMed were used as data sources and have been evaluated to produce the facts regarding amalgam's safety and toxicity.

  14. Amalgam tattoo as a means for person identification.

    Science.gov (United States)

    Slabbert, H; Ackermann, G L; Altini, M

    1991-06-01

    Person identification from the teeth depends on establishing a number of points of correspondence between ante- and postmortem dental data, but a single characteristic, if unique enough, may be sufficient. The use of amalgam tattoos in establishing identity has not been reported in the literature. Two cases in which amalgam tattoos were used in conjunction with other dental data to establish identity are reported. Ante- and postmortem radiographs showed the presence of amalgam within the adjacent alveolar bone and periapical tissues, respectively. Attempts were made to duplicate the angulation of the original antemortem radiographs so that a direct comparison could be made of the amalgam fragments. The antemortem radiographs date from 1984 and 1985 in the two respective cases. In both instances the pattern of amalgam remained fairly similar, differences being ascribed to angulation which could not be reproduced exactly. From these results it seems that amalgam tattoo may be a reliable method of identification, even though a number of years may have elapsed since the ante- and postmortem radiographs were taken. The pattern of amalgam dispersal may be sufficiently unique so that identity can be established using this single characteristic.

  15. Prenatal exposure to dental amalgam and pregnancy outcome.

    Science.gov (United States)

    Lygre, Gunvor Bentung; Haug, Kjell; Skjaerven, Rolv; Björkman, Lars

    2016-10-01

    Questions have been raised about potential risks of prenatal exposure to mercury from amalgam fillings during pregnancy. The aim of this study was to assess possible associations between exposure to amalgam fillings in pregnant women participating in a large cohort study and adverse pregnancy outcome. In the Norwegian Mother and Child Cohort Study (MoBa), a valid information about the number of teeth with amalgam fillings and dental treatment, including new amalgam fillings placed or removed during pregnancy, was available from 69 474 pregnancies. The information was obtained from two questionnaires sent to the women at 17 and 30 weeks of pregnancy, and the data were linked to the Medical Birth Registry of Norway. Logistic regression was used to estimate the odds ratio (OR) and 95% confidence intervals (95% CI) as a measure of association between pregnancy outcome and prenatal exposure to amalgam fillings. Logistic regression models, including mothers' age, education, BMI, parity, smoking during pregnancy, and alcohol consumption during pregnancy revealed no significant associations between the number of teeth with amalgam fillings and early preterm delivery, late preterm delivery, low birthweight, malformation or stillbirth. We found no evidence for serious perinatal consequences of maternal exposure to amalgam fillings during pregnancy. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  16. Mercury derived from dental amalgams and neuropsychologic function.

    Science.gov (United States)

    Factor-Litvak, Pam; Hasselgren, Gunnar; Jacobs, Diane; Begg, Melissa; Kline, Jennie; Geier, Jamie; Mervish, Nancy; Schoenholtz, Sonia; Graziano, Joseph

    2003-05-01

    There is widespread concern regarding the safety of silver-mercury amalgam dental restorations, yet little evidence to support their harm or safety. We examined whether mercury dental amalgams are adversely associated with cognitive functioning in a cross-sectional sample of healthy working adults. We studied 550 adults, 30-49 years of age, who were not occupationally exposed to mercury. Participants were representative of employees at a major urban medical center. Each participant underwent a neuropsychologic test battery, a structured questionnaire, a modified dental examination, and collection of blood and urine samples. Mercury exposure was assessed using a) urinary mercury concentration (UHg); b) the total number of amalgam surfaces; and c) the number of occlusal amalgam surfaces. Linear regression analysis was used to estimate associations between each marker of mercury exposure and each neuropsychologic test, adjusting for potential confounding variables. Exposure levels were relatively low. The mean UHg was 1.7 micro g/g creatinine (range, 0.09-17.8); the mean total number of amalgam surfaces was 10.6 (range, 0-46) and the mean number of occlusal amalgam surfaces was 6.1 (range, 0-19). No measure of exposure was significantly associated with the scores on any neuropsychologic test in analyses that adjusted for the sampling design and other covariates. In a sample of healthy working adults, mercury exposure derived from dental amalgam restorations was not associated with any detectable deficits in cognitive or fine motor functioning.

  17. Effect of bleaching on mercury release from amalgam fillings and antioxidant enzyme activities: a pilot study.

    Science.gov (United States)

    Cakir, Filiz Yalcin; Ergin, Esra; Gurgan, Sevil; Sabuncuoglu, Suna; Arpa, Cigdem Sahin; Tokgoz, İlknur; Ozgunes, Hilal; Kiremitci, Arlin

    2015-01-01

    The aim of this pilot clinical study was to determine the mercury release from amalgam fillings and antioxidant enzyme activities (Superoxide Dismutase [SOD] and Catalase[CAT] ) in body fluids after exposure to two different vital tooth bleaching systems. Twenty eight subjects with an average age of 25.6 years (18-41) having at least two but not more than four Class II amalgam fillings on each quadrant arch in the mouth participated in the study. Baseline concentrations of mercury levels in whole blood, urine, and saliva were measured by a Vapor Generation Accessory connected to an Atomic Absorption Spectrometer. Erythrocyte enzymes, SOD, and CAT activities in blood were determined kinetically. Subjects were randomly assigned to two groups of 14 volunteers. Group 1 was treated with an at-home bleaching system (Opalescence PF 35% Carbamide Peroxide, Ultradent), and Group 2 was treated with a chemically activated office bleaching system (Opalescence Xtra Boost 38% Hydrogen Peroxide, Ultradent) according to the manufacturer's recommendations. Twenty-four hours after bleaching treatments, concentrations of mercury and enzymes were remeasured. There were no significant differences on mercury levels in blood, urine, and saliva before and after bleaching treatments (p > 0.05). No differences were also found in the level of antioxidant enzyme activities (SOD and CAT) before and after treatments (p > 0.05). Mercury release did not affect the enzyme activities (p > 0.05). Bleaching treatments either office or home did not affect the amount of mercury released from amalgam fillings in blood, urine, and saliva and the antioxidant-enzyme activities in blood. Bleaching treatments with the systems tested in this pilot study have no deleterious effect on the mercury release from amalgam fillings and antioxidant enzymes in body fluids. © 2014 Wiley Periodicals, Inc.

  18. Exposure to dental amalgam restorations in pregnant women.

    Science.gov (United States)

    Lygre, Gunvor Bentung; Björkman, Lars; Haug, Kjell; Skjaerven, Rolv; Helland, Vigdis

    2010-10-01

    The Norwegian Mother and Child Cohort Study (MoBa) started in 1999 to identify environmental factors that could be involved in mechanisms leading to disease. Questions have been raised about potential risks to the fetus from prenatal exposure to mercury from amalgam fillings in pregnant women. The aim of the present study was to identify factors potentially associated with amalgam fillings in pregnant women participating in the Norwegian Mother and Child Cohort Study (MoBa). An additional aim was to obtain information about dental treatment in the cohort. Total of 67,355 pregnancies from the MoBa study were included in the present study. Information regarding age, education, smoking habits, alcohol consumption, weight, and height for the women was obtained from a questionnaire that was filled in at the 17th week of pregnancy. In another questionnaire, which was sent to all participants in the 30th week of pregnancy, the women reported types of dental treatment during pregnancy, total number of teeth, and number of teeth with amalgam fillings. The self-assessed number of teeth and number of teeth with amalgam fillings were validated in an external sample of 97 women of childbearing age. Odds ratio for having more than 12 teeth with amalgam fillings increased considerably with age. Other significant risk factors for having high exposure to amalgam were low education, high body mass index (BMI), and smoking during pregnancy. Women with the lowest levels of education had a twofold increased odds ratio of having more than 12 teeth filled with amalgam compared with women who had more than 4 years of university studies. According to the results from the validation of self-assessed number of teeth with amalgam fillings, the information obtained was reliable. Age, education, smoking habits, and BMI were associated with amalgam exposure. © 2010 John Wiley & Sons A/S.

  19. [Corrosion of titanium in presence of dental amalgams and fluorides].

    Science.gov (United States)

    Di Carlo, F; Cassinelli, C; Morra, M; Ronconi, L F; Andreasi Bassi, M; De Muro, G; Quaranta, A

    2003-03-01

    The aim of this study was to evaluate the behaviour of titanium (Ti) in precipitant condition, and more precisely the resistance against corrosion of Ti in presence of fluorides and the electrochemical interaction between Ti- amalgam couples in fluorinated solution. The experimental test was made with the use of an electrochemical cell. The following materials were tested: commercially pure Ti and 2 types of amalgams, the Persistalloy (Prs) and the IQC. Palladium (IQC.P). The free corrosion potential of Ti and the amalgams, the polarization curves of both amalgams and the corrosion current of the Ti-amalgam couples in the measurements were performed in 3 different electrolytic solutions: Ringer solution, fluorinated neutral Ringer solution and acid fluorinated solution. The three corrosive media are described. The results showed that Ti could be damaged by the presence of fluorides with an acid pH: Ti potential becomes more negative in acid fluorinated solution. The corrosion currents between Ti and amalgam couples were considered: the amalgams underwent anodic oxidation in neutral Ringer, but a reversal phenomenon occurred in the fluorinated acid solution: Ti was damaged and the amalgams both Prs and IQC.P became the cathodic partner of the couple. In neutral fluorinated solution the IQC.P amalgam induced a significantly higher corrosion of Ti, when compared to the Prs one. Results clearly show the dependence of the Ti corrosion behaviour on the pH and composition of the solution and that the outcome of the damage is affected by the composition of other metals.

  20. Amalgam pigmentation (amalgam tattoo) of the oral mucosa. A clinicopathologic study of 268 cases.

    Science.gov (United States)

    Buchner, A; Hansen, L S

    1980-02-01

    A series of 268 cases of amalgam tattoo is analyzed both clinically and histologically. The most common location was the gingiva and alveolar mucosa, followed by the buccal mucosa. Histologically, the amalgam was present in the tissues as discrete, fine, dark granules and as irregular solid fragments. The dark granules were arranged mainly along collagen bundles and around blood vessels. They were also associated with the walls of blood vessels, nerve sheaths, elastic fibers, basement membranes of mucosal epithelium, striated muscle fibers, and acini of minor salivary glands. Dark granules were also present intracellularly within macrophages, multinucleated giant cells, endothelial cells, and fibroblasts. Although in 45% of the cases there was no tissue reaction to the amalgam, in 17% there was a macrophagic reaction and in 38% there was a chronic inflammatory response, usually in the form of a foreign body granuloma, with multinucleated giant cells of the foreign body and Langhans types. Asteroid bodies were also found in some of the foreign body giant cells.

  1. Cu(II) salen complex with propylene linkage: An efficient catalyst in the formation of Csbnd X bonds (X = N, O, S) and biological investigations

    Science.gov (United States)

    Azam, Mohammad; Dwivedi, Sourabh; Al-Resayes, Saud I.; Adil, S. F.; Islam, Mohammad Shahidul; Trzesowska-Kruszynska, Agata; Kruszynski, Rafal; Lee, Dong-Ung

    2017-02-01

    The catalytic property of a mononuclear Cu(II) salen complex in Chan-Lam coupling reaction with phenyl boronic acid at room temperature is reported. The studied complex is found to be potential catalyst in the preparation of carbon-heteroatom bonds with excellent yields. The studied Cu(II) salen complex is monoclinic with cell parameters, a = 9.6807(5) (α 90°), (b = 17.2504(8) (β 112.429 (2), c = 11.1403 (6) (γ = 90°), and has distorted square planar environment around Cu(II) ion. Furthermore, there is no π⋯π interactions in the reported complex due to large distance between the centroid of aromatic rings. In addition, DNA binding study of Cu(II) salen complex by fluorescence and absorption spectroscopy is also reported. Moreover, the reported Cu(II) salen complex exhibits significant anticancer activity against MCF-7 cancer cell lines, and displays potential antimicrobial biofilm activity against P. aeruginosa, suggesting antimicrobial biofilm an important tool for suppression of resistant infections caused by P. aeruginosa.

  2. Microstructural studies of dental amalgams using analytical transmission electron microscopy

    Science.gov (United States)

    Hooghan, Tejpal Kaur

    Dental amalgams have been used for centuries as major restorative materials for decaying teeth. Amalgams are prepared by mixing alloy particles which contain Ag, Sn, and Cu as the major constituent elements with liquid Hg. The study of microstructure is essential in understanding the setting reactions and improving the properties of amalgams. Until the work reported in this dissertation, optical microscopy (OM), scanning electron microscopy (SEM), and x-ray diffractometry (XRD) were used commonly to analyze amalgam microstructures. No previous systematic transmission electron microscopy (TEM) study has been performed due to sample preparation difficulties and composite structure of dental amalgams. The goal of this research was to carry out detailed microstructural and compositional studies of dental amalgams. This was accomplished using the enhanced spatial resolution of the TEM and its associated microanalytical techniques, namely, scanning transmission electron microscopy (STEM), x-ray energy dispersive spectroscopy (XEDS) and micro-microdiffraction (mumuD). A new method was developed for thinning amalgam samples to electron transparency using the "wedge technique." Velvalloy, a low-Cu amalgam, and Tytin, a high-Cu amalgam, were the two amalgams characterized. Velvalloy is composed of a Agsb2Hgsb3\\ (gammasb1)/HgSnsb{7-9}\\ (gammasb2) matrix surrounding unreacted Agsb3Sn (gamma) particles. In addition, hitherto uncharacterized reaction layers between Agsb3Sn(gamma)/Agsb2Hgsb3\\ (gammasb2)\\ and\\ Agsb2Hgsb3\\ (gammasb1)/HgSnsb{7-9}\\ (gammasb2) were observed and analyzed. An Ag-Hg-Sn (betasb1) phase was clearly identified for the first time. In Tytin, the matrix consists of Agsb2Hgsb3\\ (gammasb1) grains. Fine precipitates of Cusb6Snsb5\\ (etasp') are embedded inside the gammasb1 and at the grain boundaries. These precipitates are responsible for the improved creep resistance of Tytin compared to Velvalloy. The additional Cu has completely eliminated the gammasb

  3. [Amalgam, composite and compomer: microbiological study].

    Science.gov (United States)

    Zogheib, C M; Hardan, L; Khoury, C Kassis; Naaman, N Bou Abboud

    2012-03-01

    Restorative materials have different consequences on the periodontium. The surface of these materials may influence gingival health and cause in some instances gingival inflammation. The purpose of this study was to investigate and compare, in a healthy periodontium, intracrevicular plaque bacteria (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis and Treponema denticola), at day 0 and at 6 months, around subgingivally located amalgam, composite and compomer fillings. All the tests were negative (less than 0.1% of the sum of 103 cells), since none of the investigated pathogens were detected. It has been concluded that the material used does not have direct effect on the bacteria species developed around the restorations at this short time period.

  4. Evaluation of the dental structure loss produced during maintenance and replacement of occlusal amalgam restorations

    OpenAIRE

    Sardenberg,Fernanda; Bonifácio,Clarissa Calil; Braga,Mariana Minatel; Imparato,José Carlos Pettorossi; Mendes,Fausto Medeiros

    2008-01-01

    The aim of this in vitro study was to evaluate four different approaches to the decision of changing or not defective amalgam restorations in first primary molar teeth concerning the loss of dental structure. Ditched amalgam restorations (n = 11) were submitted to four different treatments, as follows: Control group - polishing and finishing of the restorations were carried out; Amalgam group - the ditched amalgam restorations were replaced by new amalgam restorations; Composite resin group -...

  5. The Chemical Forms of Mercury in Aged and Fresh Dental Amalgam Surfaces

    OpenAIRE

    George, Graham N.; Singh, Satya P.; Hoover, Jay; Pickering, Ingrid J.

    2009-01-01

    Mercury-containing dental amalgam is known to be a source of human exposure to mercury. We have explored the use of electron-yield Hg LIII X-ray absorption spectroscopy to characterize the chemical nature of dental amalgam surfaces. We find that the method is practical, and that it shows extensive mercury depletion in the surface of the aged amalgam with significant differences between old and fresh amalgam surfaces. Whereas the fresh amalgam gives spectra that are typical of metallic mercury...

  6. Schiff base ligand derived from (±trans-1,2-cyclohexanediamine and its Cu(II, Co(II, Zn(II and Mn(II complexes: Synthesis, characterization, styrene oxidation and hydrolysis study of the imine bond in Cu(II Schiff base complex

    Directory of Open Access Journals (Sweden)

    Sarkheil Marzieh

    2016-01-01

    Full Text Available A Schiff base ligand (H2L derived from 2´-hydroxypropiophenone and (±trans-1,2-cyclohexanediamine was synthesized. The reactions of MCl2.xH2O (M =Cu(II, Co(II, Zn(II and Mn(IIwith the di-Schiff base ligand (H2L were studied. This ligand when stirred with 1 equivalent of CuCl2.2H2O in the solution of ethanol and chloroform undergoes partial hydrolysis of the imino bond and the resultant tridentate ligand (HL′immediately forms complex[CuL´Cl]∙3/2CHCl3(1with N2O coordination sphere. Under the same condition, the reaction of H2L with MCl2.xH2O (M = Co(II (3, Zn(II (4 and Mn(II (5 gave complexes[ML]•1/2CHCl3∙3/2H2O (3-5with N2O2 coordination sphere and no hydrolytic cleavage was occurred. Also, the reaction of H2L with CuCl2.2H2O in THF gave the complex CuL (2with N2O2 coordination sphere. The ligand and complexes were characterized by FTIR, UV-Vis, 1H NMRand elemental analysis. The homogeneous catalytic activity of the complexes1, 3 and 5wasevaluated for the oxidation of styrene using tert-butyl hydroperoxide (TBHP as oxidant. Finally, the copper(II complex(1encapsulated in the nanopores of zeolite-Y by flexible ligand method (CuL´-Yand its encapsulation was ensured by different studies. The catalytic performance of heterogeneous catalyst in the styrene oxidation with TBHP was investigated. The catalytic tests showed that the homogenous and heterogeneous catalysts were active in the oxidation of styrene.

  7. Three-year clinical evaluation of cuspal coverage with combined composite-amalgam in endodontically-treated maxillary premolars.

    Science.gov (United States)

    Shafiei, Fereshteh; Memarpour, Mahtab; Doozandeh, Maryam

    2010-01-01

    This clinical study evaluated the clinical performance of cuspal coverage with combined composite-amalgam restorations in endodontically-treated maxillary premolars over a three-year period. Thirty-six maxillary premolars, each with a Class II cavity in 36 patients ranging in age between 28 and 52 years, were selected after endodontic treatment. After reduction of the buccal and palatal cusps, internal coverage and veneering of the reduced buccal cusp was performed with composite. The remaining cavity and reduced palatal cusp were restored with high-copper amalgam. The restorations were evaluated at baseline and in one-, two- and three-year recalls with USPHS criteria. Changes in characteristics of the restorations were analyzed with the Cochran Q-test at a significance level of p composite-amalgam interface after one year (p > 0.05). Four restorations exhibited slight discoloration of the composite veneering after three years (p composite-amalgam cusp coverage of endodontically-treated maxillary premolars showed acceptable clinical performance after three years.

  8. The future of dental amalgam: a review of the literature. Part 6: Possible harmful effects of mercury from dental amalgam.

    Science.gov (United States)

    Eley, B M

    1997-06-28

    This is the sixth article in a series of seven on the future of dental amalgam. It considers the possible toxic and allergic effects which could occur as a result of exposure to mercury from dental amalgam. The main toxic effects covered are neurotoxicity, kidney dysfunction, reduced immunocompetence, effects on the oral and intestinal bacterial flora, fetal and birth effects and effects on general health. The relevant studies in all these areas are described and extensively discussed. In addition, the possible development of hypersensitivity to mercury from amalgam is described and the production of delayed hypersensitivity contact reactions on the skin and mucous membrane, including lichenoid lesions, are considered.

  9. Mercury (Hg) burden in children: The impact of dental amalgam

    Energy Technology Data Exchange (ETDEWEB)

    Al-Saleh, Iman, E-mail: iman@kfshrc.edu.sa [Biological and Medical Research Department, King Faisal Specialist Hospital and Research Centre, PO Box: 3354, Riyadh 11211 (Saudi Arabia); Al-Sedairi, Al anoud [Department of Zoology, College of Science, King Saud University, PO Box: 24452, Riyadh 11495 (Saudi Arabia)

    2011-07-15

    The risks and benefits of using mercury (Hg) in dental amalgam have long been debated. This study was designed to estimate Hg body burden and its association with dental amalgam fillings in 182 children (ages: 5-15 years) living in Taif City. Hg was measured in urine (UHg), hair (HHg) and toenails (NHg) by the Atomic Absorption Spectrophotometer with Vapor Generator Accessory system. Urinary Hg levels were calculated as both micrograms per gram creatinine ({mu}g/g creatinine) and micrograms per liter ({mu}g/L). We found that children with amalgam fillings (N = 106) had significantly higher UHg-C levels than children without (N = 76), with means of 3.763 {mu}g/g creatinine versus 3.457 {mu}g/g creatinine, respectively (P = 0.019). The results were similar for UHg (P = 0.01). A similar pattern was also seen for HHg, with means of 0.614 {mu}g/g (N = 97) for children with amalgam versus 0.242 {mu}g/g (N = 74) for those without amalgam fillings (P = 0). Although the mean NHg was higher in children without amalgam (0.222 {mu}g/g, N = 61) versus those with (0.163 {mu}g/g, N = 101), the relationship was not significant (P = 0.069). After adjusting for many confounders, the multiple logistic regression model revealed that the levels of UHg-C and HHg were 2.047 and 5.396 times higher, respectively, in children with dental amalgam compared to those without (P < 0.01). In contrast, a significant inverse relationship was seen between NHg levels and dental amalgam fillings (P = 0.003). Despite the controversy surrounding the health impact of dental amalgam, this study showed some evidence that amalgam-associated Hg exposure might be related with symptoms of oral health, such as aphthous ulcer, white patches, and a burning-mouth sensation. Further studies are needed to reproduce these findings. The present study showed that significant numbers of children with or without amalgam had Hg levels exceeding the acceptable reference limits. The detrimental neurobehavioral and

  10. The Thickness of Amalgamations and Cartesian Product of Graphs

    Directory of Open Access Journals (Sweden)

    Yang Yan

    2017-08-01

    Full Text Available The thickness of a graph is the minimum number of planar spanning subgraphs into which the graph can be decomposed. It is a measurement of the closeness to the planarity of a graph, and it also has important applications to VLSI design, but it has been known for only few graphs. We obtain the thickness of vertex-amalgamation and bar-amalgamation of graphs, the lower and upper bounds for the thickness of edge-amalgamation and 2-vertex-amalgamation of graphs, respectively. We also study the thickness of Cartesian product of graphs, and by using operations on graphs, we derive the thickness of the Cartesian product Kn □ Pm for most values of m and n.

  11. Crystallic silver amalgam – a novel electrode material

    Czech Academy of Sciences Publication Activity Database

    Daňhel, A.; Mansfeldová, Věra; Janda, Pavel; Vyskočil, V.; Barek, J.

    2011-01-01

    Roč. 136, č. 118 (2011), s. 36563662 ISSN 0003-2654 Institutional research plan: CEZ:AV0Z40400503 Keywords : crystallic silver amalgam * electrode materials * electrochemistry Subject RIV: CG - Electrochemistry Impact factor: 4.230, year: 2011

  12. Improving the strength of amalgams by including steel fibers

    Energy Technology Data Exchange (ETDEWEB)

    Cochran, Calvin T. [Hendrix College, Conway, AR 72032 (United States); Van Hoose, James R. [Siemens, Orlando, FL 32826 (United States); McGill, Preston B. [Marshall Space Flight Center, EM20, Huntsville, AL 35812 (United States); Grugel, Richard N., E-mail: richard.n.grugel@nasa.gov [Marshall Space Flight Center, EM30, Huntsville, AL 35812 (United States)

    2012-05-30

    Highlights: Black-Right-Pointing-Pointer A room temperature liquid Ga-In alloy was successfully substituted for mercury. Black-Right-Pointing-Pointer Physically sound amalgams with included steel fibers can be made. Black-Right-Pointing-Pointer A small volume fraction inclusion of fibers increased strength by {approx}20%. - Abstract: Mercury amalgams, due to their material properties, are widely and successfully used in dental practice. They are, however, also well recognized as having poor tensile strength. With the possibility of expanding amalgam applications it is demonstrated that tensile strength can be increased some 20% by including a small amount of steel fibers. Furthermore, it is shown that mercury can be replaced with a room temperature liquid gallium-indium alloy. Processing, microstructures, and mechanical test results of these novel amalgams are presented and discussed in view of means to further improve their properties.

  13. Mercury (Hg) burden in children: the impact of dental amalgam.

    Science.gov (United States)

    Al-Saleh, Iman; Al-Sedairi, Al Anoud

    2011-07-15

    The risks and benefits of using mercury (Hg) in dental amalgam have long been debated. This study was designed to estimate Hg body burden and its association with dental amalgam fillings in 182 children (ages: 5-15 years) living in Taif City. Hg was measured in urine (UHg), hair (HHg) and toenails (NHg) by the Atomic Absorption Spectrophotometer with Vapor Generator Accessory system. Urinary Hg levels were calculated as both micrograms per gram creatinine (μg/g creatinine) and micrograms per liter (μg/L). We found that children with amalgam fillings (N=106) had significantly higher UHg-C levels than children without (N=76), with means of 3.763 μg/g creatinine versus 3.457 μg/g creatinine, respectively (P=0.019). The results were similar for UHg (P=0.01). A similar pattern was also seen for HHg, with means of 0.614 μg/g (N=97) for children with amalgam versus 0.242 μg/g (N=74) for those without amalgam fillings (P=0). Although the mean NHg was higher in children without amalgam (0.222 μg/g, N=61) versus those with (0.163 μg/g, N=101), the relationship was not significant (P=0.069). After adjusting for many confounders, the multiple logistic regression model revealed that the levels of UHg-C and HHg were 2.047 and 5.396 times higher, respectively, in children with dental amalgam compared to those without (Phealth impact of dental amalgam, this study showed some evidence that amalgam-associated Hg exposure might be related with symptoms of oral health, such as aphthous ulcer, white patches, and a burning-mouth sensation. Further studies are needed to reproduce these findings. The present study showed that significant numbers of children with or without amalgam had Hg levels exceeding the acceptable reference limits. The detrimental neurobehavioral and/or nephrotoxic effects of such an increased Hg on children should be a cause of concern, and further investigation is warranted. Our results are alarming and indicate an urgent need for biomonitoring and

  14. Amalgam Tattoo Mimicking Mucosal Melanoma: A Diagnostic Dilemma Revisited

    OpenAIRE

    Lundin, K.; Schmidt, G.; Bonde, C.

    2013-01-01

    Mucosal melanoma of the oral cavity is a rare but highly aggressive neoplasm. However, the clinicians need to be aware of the other and more frequent etiologies of intraoral pigmentation, such as amalgam tattoos. As amalgam has been extensively used for dental restorations and can cause pigmentations in the oral mucosa, this is a differential diagnosis not to be forgotten. We describe the characteristics of these two phenomena and present a case vignette illustrating the differential diagnost...

  15. Dental amalgam and urinary mercury concentrations: a descriptive study

    OpenAIRE

    Nicolae, Alexandra; Ames, Harry; Qui?onez, Carlos

    2013-01-01

    Background Dental amalgam is a source of elemental and inorganic mercury. The safety of dental amalgam in individuals remains a controversial issue. Urinary mercury concentrations are used to assess chronic exposure to elemental mercury. At present, there are no indications of mercury-associated adverse effects at levels below 5??g Hg/g creatinine (Cr) or 7??g Hg/L (urine). The purpose of the present study is to determine the overall urinary mercury level in the Canadian general population in...

  16. Working electrodes from amalgam paste for electrochemical measurements

    Czech Academy of Sciences Publication Activity Database

    Josypčuk, Bohdan; Šestáková, Ivana

    2008-01-01

    Roč. 20, č. 4 (2008), s. 426-433 ISSN 1040-0397 R&D Projects: GA ČR GA203/07/1195; GA ČR GA521/06/0496 Institutional research plan: CEZ:AV0Z40400503 Keywords : voltammetry * paste amalgam * silver amalgam * paste electrode Subject RIV: CG - Electrochemistry Impact factor: 2.901, year: 2008

  17. D1-Asn-298 in photosystem II is involved in a hydrogen-bond network near the redox-active tyrosine YZfor proton exit during water oxidation.

    Science.gov (United States)

    Nagao, Ryo; Ueoka-Nakanishi, Hanayo; Noguchi, Takumi

    2017-12-08

    In photosynthetic water oxidation, two water molecules are converted into one oxygen molecule and four protons at the Mn 4 CaO 5 cluster in photosystem II (PSII) via the S-state cycle. Efficient proton exit from the catalytic site to the lumen is essential for this process. However, the exit pathways of individual protons through the PSII proteins remain to be identified. In this study, we examined the involvement of a hydrogen-bond network near the redox-active tyrosine Y Z in proton transfer during the S-state cycle. We focused on spectroscopic analyses of a site-directed variant of D1-Asn-298, a residue involved in a hydrogen-bond network near Y Z We found that the D1-N298A mutant of Synechocystis sp. PCC 6803 exhibits an O 2 evolution activity of ∼10% of the wild-type. D1-N298A and the wild-type D1 had very similar features of thermoluminescence glow curves and of an FTIR difference spectrum upon Y Z oxidation, suggesting that the hydrogen-bonded structure of Y Z and electron transfer from the Mn 4 CaO 5 cluster to Y Z were little affected by substitution. In the D1-N298A mutant, however, the flash-number dependence of delayed luminescence showed a monotonic increase without oscillation, and FTIR difference spectra of the S-state cycle indicated partial and significant inhibition of the S 2 → S 3 and S 3 → S 0 transitions, respectively. These results suggest that the D1-N298A substitution inhibits the proton transfer processes in the S 2 → S 3 and S 3 → S 0 transitions. This in turn indicates that the hydrogen-bond network near Y Z can be functional as a proton transfer pathway during photosynthetic water oxidation. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. Dental amalgam exposure can elevate urinary mercury concentrations in children.

    Science.gov (United States)

    Baek, Hye-Jin; Kim, Eun-Kyong; Lee, Sang Gyu; Jeong, Seong-Hwa; Sakong, Jun; Merchant, Anwar T; Im, Sang-Uk; Song, Keun-Bae; Choi, Youn-Hee

    2016-06-01

    Owing to its cost-effectiveness and operative convenience, dental amalgam remains in use as a restorative material for tooth caries in children in many countries. The aim of this study was to evaluate the relationship between dental amalgam exposure and urinary mercury (U-Hg) concentrations in children. In this longitudinal study, 463, 367 and 348 children, 8-11 years of age, were evaluated at baseline, and at the first and second follow-up visits, respectively. The interval between each survey was 6 months. For the oral examination and urine sample, the amalgam-filled tooth surface (TS), and U-Hg and creatinine concentrations of participants were determined, and the cumulative amalgam-filled TS and cumulative creatinine-adjusted U-Hg were calculated. To assess potential covariates, socio-demographic factors, oral health behaviour and dietary factors were surveyed by questionnaire. Data were analysed by the t-test, correlation analysis and mixed-model analysis. The statistical analyses were performed using SPSS 18.0. Children with more than one amalgam-filled TS exhibited significantly higher creatinine-adjusted U-Hg concentrations than those without, in all three survey periods (P dental amalgam exposure can affect the systemic mercury concentration in children. © 2016 FDI World Dental Federation.

  19. The Post-Amalgam Era: Norwegian Dentists? Experiences with Composite Resins and Repair of Defective Amalgam Restorations

    OpenAIRE

    Kopperud, Simen E.; Staxrud, Frode; Espelid, Ivar; Tveit, Anne Bj?rg

    2016-01-01

    Amalgam was banned as a dental restorative material in Norway in 2008 due to environmental considerations. An electronic questionnaire was sent to all dentists in the member register of the Norwegian Dental Association (NTF) one year later, to evaluate dentists’ satisfaction with alternative restorative materials and to explore dentists’ treatment choices of fractured amalgam restorations. Replies were obtained from 61.3%. Composite was the preferred restorative material among 99.1% of the de...

  20. [Solubility of metal components into tissue culture medium from dental amalgams (author's transl)].

    Science.gov (United States)

    Kawahara, H; Yamada, T; Nakamura, M; Tomoda, T; Kobayashi, H; Saijo, A; Kawata, Y; Hikari, S

    1981-10-01

    Solubility of metal components into tissue culture medium, YLH, from various dental amalgams including high copper, conventional and copper amalgam was measured with atomic absorption spectrometry. The results obtained were as follows.: 1. Mercury solubility was found much in all the dental amalgams after one day extraction. This was followed by gradual increase in solubility in the high copper amalgams until after seven days. On the otherhand, initial high solubility was maintained in conventional and copper amalgams through the whole experimental period. 2. Higher solubility of silver and copper was recorded in the high copper amalgams. 3. Zinc was only found in Dispersalloy and copper amalgam. 4. Tin was unable to be measured in all the amalgams examined. It was considered that the present results could shed a light on the mechanism for cytotoxicity yielding of the dental amalgams.

  1. Dental Amalgam Restorations and Children’s Neuropsychological Function: The New England Children’s Amalgam Trial

    Science.gov (United States)

    Bellinger, David C.; Daniel, David; Trachtenberg, Felicia; Tavares, Mary; McKinlay, Sonja

    2007-01-01

    Background A concern persists that children’s exposure to mercury vapor from dental amalgams produces neurotoxicity. Objective Our goal was to compare the neuropsychological function of children, without prior exposure to dental amalgam, whose caries were repaired using either dental amalgam or mercury-free composite materials. Methods We conducted a randomized controlled trial involving 534 6- to 10-year-old urban and rural children who were assessed yearly for 5 years using a battery of tests of intelligence, achievement, language, memory, learning, visual–spatial skills, verbal fluency, fine motor function, problem solving, attention, and executive function. Results Although the mean urinary mercury concentration was greater among children in the amalgam group than the composite group (0.9 vs. 0.6 μg/g creatinine), few significant differences were found between the test scores of children in the two groups. The differences found were inconsistent in direction. Analyses using two cumulative exposure indices—surface years of amalgam and urinary mercury concentration—produced similar results. Conclusions Exposure to elemental mercury in amalgam at the levels experienced by the children who participated in the trial did not result in significant effects on neuropsychological function within the 5-year follow-up period. PMID:17431496

  2. A dose-effect analysis of children's exposure to dental amalgam and neuropsychological function: the New England Children's Amalgam Trial.

    Science.gov (United States)

    Bellinger, David C; Trachtenberg, Felicia; Daniel, David; Zhang, Annie; Tavares, Mary A; McKinlay, Sonja

    2007-09-01

    The New England Children's Amalgam Trial (NECAT) was a five-year randomized trial of 534 6- to 10-year-old children that compared the neuropsychological outcomes of those whose caries were restored using dental amalgam with the outcomes of those those whose caries were restored using mercury-free resin-based composite. The primary intention-to-treat analyses did not reveal significant differences between the treatment groups on the primary or secondary outcomes of the administered psychological tests: Full-Scale IQ score on the Wechsler Intelligence Scale for Children-Third Edition, General Memory Index of the Wide Range Assessment of Memory and Learning, and Visual-Motor Composite of the Wide Range Assessment of Visual Motor Abilities. To determine whether treatment group assignment, a dichotomous measure of exposure, was sufficiently sensitive to detect associations between mercury exposure and these outcomes, the authors conducted analyses to evaluate the associations between the primary and secondary outcomes and two continuously distributed indexes of potential exposure, surface-years of amalgam and urinary mercury excretion. Neither index of mercury exposure was significantly associated with any of the three outcomes. The authors found no evidence that exposure to mercury from dental amalgam was associated with any adverse neuropsychological effects over the five-year period after placement of amalgam restorations. Analyses of the outcomes of the NECAT study indicate that use of dental amalgam was not associated with an increase in children's risk of experiencing neuropsychological dysfunction.

  3. Synthesis of diorganoplatinum(IV) complexes by the Ssbnd S bond cleavage with platinum(II) complexes

    Science.gov (United States)

    Niroomand Hosseini, Fatemeh; Rashidi, Mehdi; Nabavizadeh, S. Masoud

    2016-12-01

    Reaction of [PtR2(NN)] (R = Me, p-MeC6H4 or p-MeOC6H4; NN = 2,2‧-bipyridine, 4,4‧-dimethyl-2,2‧-bipyridine, 1,10-phenanthroline or 2,9-dimethyl-1,10-phenanthroline) with MeSSMe gives the platinum(IV) complexes cis,trans-[PtR2(SMe)2(NN)]. They are characterized by NMR spectroscopy and elemental analysis. The geometries and the nature of the frontier molecular orbitals of Pt(IV) complexes containing Ptsbnd S bonds are studied by means of the density functional theory.

  4. Graphical linking of MO multicenter bond index and VB structures. II-5-c rings and 6-c heterocyclic rings

    International Nuclear Information System (INIS)

    Bollini, Carlos Guido; Giambiagi, Mario; Giambiagi, Myriam Segre de; Figueiredo, Aloysio Paiva de

    2001-02-01

    Through the graphical method proposed it is possible to set a link between an MO multicenter bond index and VB structures. The value of the index depends on the order of the atoms involved if they are more than three. For 5-c rings three basic structures are required; the eventually different values are 12. Unlike the 6-c case it may happen that different pairs of basic structures are used to build the same polygon. For the 6-c rings including heteroatoms the original degeneracy of benzene splits leading eventually to 60 different I ring values. (author)

  5. Graphical linking of MO multicenter bond index and VB structures. II-5-c rings and 6-c heterocyclic rings

    CERN Document Server

    Bollini, C G; Giambiagi, M

    2001-01-01

    Through the graphical method proposed it is possible to set a link between an MO multicenter bond index and VB structures. The value of the index depends on the order of the atoms involved if they are more than three. For 5-c rings three basic structures are required; the eventually different values are 12. Unlike the 6-c case it may happen that different pairs of basic structures are used to build the same polygon. For the 6-c rings including heteroatoms the original degeneracy of benzene splits leading eventually to 60 different I sub r sub i sub n sub g values.

  6. A series of Cd(II) complexes with π-π stacking and hydrogen bonding interactions: Structural diversities by varying the ligands

    International Nuclear Information System (INIS)

    Wang Xiuli; Zhang Jinxia; Liu Guocheng; Lin Hongyan

    2011-01-01

    Seven new Cd(II) complexes consisting of different phenanthroline derivatives and organic acid ligands, formulated as [Cd(PIP) 2 (dnba) 2 ] (1), [Cd(PIP)(ox)].H 2 O (2), [Cd(PIP)(1,4-bdc)(H 2 O)].4H 2 O (3), [Cd(3-PIP) 2 (H 2 O) 2 ].4H 2 O (4), [Cd 2 (3-PIP) 4 (4,4'-bpdc)(H 2 O) 2 ].5H 2 O (5), [Cd(3-PIP)(nip)(H 2 O)].H 2 O (6), [Cd 2 (TIP) 4 (4,4'-bpdc)(H 2 O) 2 ].3H 2 O (7) (PIP=2-phenylimidazo[4,5-f]1,10-phenanthroline, 3-PIP=2-(3-pyridyl)imidazo[4,5-f]1,10-phenanthroline, TIP=2-(2-thienyl)imidazo[4,5-f]1,10-phenanthroline, Hdnba=3,5-dinitrobenzoic acid, H 2 ox=oxalic acid, 1,4-H 2 bdc=benzene-1,4-dicarboxylic acid, 4,4'-H 2 bpdc=biphenyl-4,4'-dicarboxylic acid, H 2 nip=5-nitroisophthalic acid) have been synthesized under hydrothermal conditions. Complexes 1 and 4 possess mononuclear structures; complexes 5 and 7 are isostructural and have dinuclear structures; complexes 2 and 3 feature 1D chain structures; complex 6 contains 1D double chain, which are further extended to a 3D supramolecular structure by π-π stacking and hydrogen bonding interactions. The N-donor ligands with extended π-system and organic acid ligands play a crucial role in the formation of the final supramolecular frameworks. Moreover, thermal properties and fluorescence of 1-7 are also investigated. -- Graphical abstract: Seven new supramolecular architectures have been successfully isolated under hydrothermal conditions by reactions of different phen derivatives and Cd(II) salts together with organic carboxylate anions auxiliary ligands. Display Omitted Research highlights: → Complexes 1-7 are 0D or 1D polymeric structure, the π-π stacking and H-bonding interactions extend the complexes into 3D supramolecular network. To our knowledge, systematic study on π-π stacking and H-bonding interactions in cadmium(II) complexes are still limited. → The structural differences among the title complexes indicate the importance of N-donor chelating ligands for the creation of molecular

  7. The chemical forms of mercury in aged and fresh dental amalgam surfaces.

    Science.gov (United States)

    George, Graham N; Singh, Satya P; Hoover, Jay; Pickering, Ingrid J

    2009-11-01

    Mercury-containing dental amalgam is known to be a source of human exposure to mercury. We have explored the use of electron yield Hg L(III) X-ray absorption spectroscopy to characterize the chemical nature of dental amalgam surfaces. We find that the method is practical and that it shows extensive mercury depletion in the surface of the aged amalgam with significant differences between old and fresh amalgam surfaces. Whereas the fresh amalgam gives spectra that are typical of metallic mercury, the aged amalgam is predominantly beta-mercuric sulfide. The toxicological implications of these results are discussed.

  8. Bacteriology of deep carious lesions underneath amalgam restorations with different pulp-capping materials - an in vivo analysis

    Directory of Open Access Journals (Sweden)

    Prasanna Neelakantan

    2012-04-01

    Full Text Available Microorganisms remaining in dentin following cavity preparation may induce pulp damage, requiring the use of pulp-capping agents with antimicrobial activity underneath permanent restorations. OBJECTIVE: The aims of this study were to analyze the bacteriological status of carious dentin and to assess the efficacy of different base underneath silver amalgam restorations. MATERIAL AND METHODS: This study was conducted on 50 patients aged 13 to 30 years. Sterile swabs were used to take samples after cavity preparation, which was assessed by microbiological culture to identify the microorganisms present. Following this, cavities were restored with silver amalgam, using one of the materials being investigated, as the base: calcium hydroxide (Group II, polyantibiotic paste (Group III, a novel light-cured fluoride-releasing hydroxyapatite-based liner (Group IV and mineral trioxide aggregate - MTA (Group V. In Group I, the cavities were restored with silver amalgam, without any base. After 3 months, the amalgam was removed and samples taken again and analyzed for the microbial flora. RESULTS: Lactobacilli were the most commonly isolated microorganisms in the samples of carious dentin. Groups IV and V showed negative culture in the 3-month samples. There was no statistically significant difference between Groups I, II and III. There was no significant difference between Groups IV and V (p>0.05. Both Groups IV and V showed significantly better results when compared to Groups I, II and III (p<0.05. CONCLUSIONS: The hydroxyapatite-based liner and MTA performed significantly better in terms of antibacterial activity than the other materials.

  9. A comparison between new dentinal adhesives (fifth generation and traditional varnish in microleakage reduction of amalgam restorations in primary teeth

    Directory of Open Access Journals (Sweden)

    Mortazavi M. Associate Professor

    2003-06-01

    Full Text Available Statement of Problem: Microleakage presents the major cause for restorations failure in the oral cavity resulting in postoperative sensitivity, pulp irritation and secondary caries formation."nAim: The aim of this study was to compare two dentinal adhesive systems of fifth generation and copalite varnish in reducing microleakage of amalgam restorations in primary teeth."nMaterials and Methods: In this in-vitro study, 100 class V amalgam restorations were prepared on the buccal or lingual surfaces of primary molar and canine teeth. Samples were randomly divided into four groups (25 samples each. No liner was used for the first group and the second group restorations were lined with copalite varnish. Two dentin adhesives, called Syntac C and Single Bond, were used for the third and fourth groups, respectively. At the next stage, the samples were immersed in 5% fuschin solution for 24 hours, then sectioned buccolingually, and examined under a stereomicroscope for microleakage evaluation."nResults: There was a significant difference between four groups statistically (PO.000I, Comparing"nfour groups, the first and fourth ones, demonstrated the most and the least microleakage, respectively."nConclusion: The present study showed that new dentinal adhesive systems caused microleakage"nreduction in amalgam restorations of primary teeth.

  10. [The effects of high copper amalgams upon L strain fibroblasts in vitro (author's transl)].

    Science.gov (United States)

    Isomura, S

    1980-04-01

    To investigate the cytotoxicity of three high copper amalgams (HA 1, HA 2 and HA 3) which are currently available in Japan, and compare with that of the conventional amalgams, i. e., fine cut, spherical and copper amalgams, a cell culture system with L strain fibroblasts was used. Results were assessed by cell multiplication rate calculated from cell nuclei counting and cell morphology. The results obtained were as follows: 1. Amalgam alloys of two of the high copper amalgams tested (HA 3 and HA 1) as well as two of the conventional amalgams, i. e., fine cut and spherical amalgams did not give adverse effects to the cells. However, the alloys of the other high copper amalgam, HA 2, and copper amalgam yielded intense cytotoxicity. 2. As to the triturated amalgams, two of the high copper amalgams (HA 3 and HA 1) showed a very similar effects to the cell to the fine cut and spherical amalgams. At three hours after trituration, depression of cell growth diminished in two of the high copper amalgams(HA 3 and HA 1). However, the other high copper amalgam, HA 2, yielded intense and persistent cytotoxicity even at 24 hours after after trituration. 3. Cell morphology of the experimental groups confirmed the above result of the rate of cell multiplication. 4. A similar biological effect to the results in several previous reports with three conventional amalgams in vitro was confirmed. It was discussed that difference of biological effects in vitro among the three high copper amalgams might be attributed to the alloy composition. It is considered that the present results will be able to lend suggestions to the use of the high copper amalgams.

  11. Comparison of 2 comprehensive Class II treatment protocols including the bonded Herbst and headgear appliances: a double-blind study of consecutively treated patients at puberty.

    Science.gov (United States)

    Baccetti, Tiziano; Franchi, Lorenzo; Stahl, Franka

    2009-06-01

    The aim of this clinical trial was to compare the effects of 2 protocols for single-phase comprehensive treatment of Class II Division 1 malocclusion (bonded Herbst followed by fixed appliances [BH + FA] vs headgear followed by fixed appliances and Class II elastics [HG + FA]) at the pubertal growth spurt. Fifty-six Class II patients were enrolled in the trial and allocated by personal choice to 2 practices, where they underwent 1 of 2 treatment protocols (28 patients were treated consecutively with BH + FA, and 28 patients were treated consecutively with HG + FA). All patients started treatment at puberty (cervical stage [CS] 3 or CS 4) and completed treatment after puberty (CS 5 or CS 6). Lateral cephalograms were taken before therapy and 6 months after the end of comprehensive therapy, with an average interval of 28 months. Longitudinal observations of a matched group of 28 subjects with untreated Class II malocclusions were compared with the 2 treated groups. Analysis of variance (ANOVA) with post-hoc tests was used for statistical comparisons. Discriminant analysis was applied to identify preferential candidates for the BH + FA protocol on the basis of profile changes (advancement of the soft tissues of the chin). The success rate (full occlusal correction of the malocclusion after treatment) was 92.8% in both treatment groups. The BH + FA group showed a significant increase in mandibular protrusion. The increase in effective mandibular length (Co-Gn) was significantly greater in both treatment groups when compared with natural growth changes in the Class II controls. Significantly greater improvement in sagittal maxillomandibular relationships was found in the BH + FA group. Retrusion of maxillary incisors and mesial movement of mandibular molars were significant in the HG + FA group. The BH + FA group showed significantly greater forward movements of soft-tissue B-point and pogonion compared with both the HG + FA and the control groups. Two pretreatment

  12. Evaluation of genotoxic effect of amalgam restorations in oral cavity

    Directory of Open Access Journals (Sweden)

    Chennoju Sai Kiran

    2015-01-01

    Full Text Available Background: Mercury a popular heavy metal used in dentistry in the form of amalgam is a known clastogen. The assessment of micronuclei in cells is a promising tool for studying the genotoxic effect of mercury on them. Hence, a study was conducted to evaluate the frequency of micronuclei in exfoliated buccal cells of subjects with amalgam restorations. Materials and Methods: A total of 60 subjects (age and gender-matched sample of 30 study group and 30 control group were included in this study. Smears were obtained with moistened wooden spatula from buccal mucosa in close contact with amalgam restoration and fixed with 100% ethyl alcohol. After staining with Papanicolaou stain, all the slides were examined under ×40 and 1,000 cells were counted for the presence of micronuclei. The data were entered into a spread sheet and subjected to statistical analysis. Results: A statistically significant increase in the number of micronuclei containing cells was observed in the study group when compared to control group (P < 0.05. A positive correlation was observed between the duration of restoration and frequency of micronuclei (P < 0.05. Conclusion: The results showed a definite genotoxic effect of amalgam restorations on the oral cavity which can be attributed to the clastogenic action of mercury in amalgam restorations.

  13. Monte carlo dose calculation in dental amalgam phantom

    Directory of Open Access Journals (Sweden)

    Mohd Zahri Abdul Aziz

    2015-01-01

    Full Text Available It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC. On the other hand, computed tomography (CT images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatment volume, the CT images input showed prominent streak artefact, thus, contributed sources of error. Hence, metal amalgam phantom often creates streak artifacts, which cause an error in the dose calculation. Thus, a streak artifact reduction technique was applied to correct the images, and as a result, better images were observed in terms of structure delineation and density assigning. Furthermore, the amalgam density data were corrected to provide amalgam voxel with accurate density value. As for the errors of dose uncertainties due to metal amalgam, they were reduced from 46% to as low as 2% at d80 (depth of the 80% dose beyond Zmax using the presented strategies. Considering the number of vital and radiosensitive organs in the head and the neck regions, this correction strategy is suggested in reducing calculation uncertainties through MC calculation.

  14. Mercury exposure levels in children with dental amalgam fillings.

    Science.gov (United States)

    Miriam Varkey, Indu; Shetty, Rajmohan; Hegde, Amitha

    2014-01-01

    Mercury combined with other metals to form solid amalgams has long been used in reconstructive dentistry but its use has been controversial since at least the middle of the 19th century. The exposure and body burden of mercury reviews have consistently stated that there is a deficiency of adequate epidemiological studies addressing this issue. Fish and dental amalgam are two major sources of human exposure to organic (MeHg) and inorganic Hg respectively. A total of 150 subjects aged between 9 and 14 years were divided into two groups of 75 subjects each depending on their diet, i.e. seafood or nonseafood consuming. Each category was subdivided into three groups based on number of restorations. Scalp hair and urine samples were collected at baseline and 3 months later to assess the organic and inorganic levels of mercury respectively by atomic absorption spectrophotometer (AAS). The mean values of urinary mercury (inorganic mercury) in the group of children with restorations were 1.5915 μg/l as compared to 0.0130 μg/l in the groups with no amalgam restorations (p p amalgam restorations as a sole exposure source needs to be put to a rest, as environmental factors collectively overpower the exposure levels from restorations alone. How to cite this article: Varkey IM, Shetty R, Hegde A. Mercury Exposure Levels in Children with Dental Amalgam Fillings. Int J Clin Pediatr Dent 2014;7(3):180-185.

  15. A Comparison between Amalgam and MTA in Repairing Furcal Perforation

    Directory of Open Access Journals (Sweden)

    H. Ghanbari

    2008-09-01

    Full Text Available Objective: The purpose of this study was to investigate the histological response to delib-erate perforation repaired using amalgam or MTA either immediately or with delay on cats’ molars.Materials and Methods: Twenty-eight molar teeth from four cats were used in this ex-perimental randomized study. After preparing the access cavity, the floor of pulp cham-bers were deliberately perforated with a round bur No. 5. The teeth were randomly divided into four groups of seven. In groups one and two,the perforation was immediately sealed with amalgam and MTA, respectively. In groups three and four, the perforations were leftexposed to saliva for six weeks and then sealed with amalgam or MTA. The animals were sacrificed four months later and the specimens processed. The samples were blindly exam-ined for inflammatory reaction and healing process under light microscope. The data were analyzed with Mann-Whitney U and Fisher exact tests.Results: The type of the materials used has no significant effect on the severity of in-flammation; while, immediate or delayed repair of furcal perforation has, and immediate application of, MTA produced less inflammation than that of amalgam (P<0.05. No dif-ferences were found in vasodilatation, abscess formation or healing process between the immediate and the delayed repair groups (P=0.13.Conclusion: MTA is a more suitable material than amalgam for perforation repair, par-ticularly when used immediately after perforation.

  16. Monte Carlo dose calculation in dental amalgam phantom.

    Science.gov (United States)

    Aziz, Mohd Zahri Abdul; Yusoff, A L; Osman, N D; Abdullah, R; Rabaie, N A; Salikin, M S

    2015-01-01

    It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC). On the other hand, computed tomography (CT) images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatment volume, the CT images input showed prominent streak artefact, thus, contributed sources of error. Hence, metal amalgam phantom often creates streak artifacts, which cause an error in the dose calculation. Thus, a streak artifact reduction technique was applied to correct the images, and as a result, better images were observed in terms of structure delineation and density assigning. Furthermore, the amalgam density data were corrected to provide amalgam voxel with accurate density value. As for the errors of dose uncertainties due to metal amalgam, they were reduced from 46% to as low as 2% at d80 (depth of the 80% dose beyond Zmax) using the presented strategies. Considering the number of vital and radiosensitive organs in the head and the neck regions, this correction strategy is suggested in reducing calculation uncertainties through MC calculation.

  17. Mechanical Properties Comparing Composite Fiber Length to Amalgam.

    Science.gov (United States)

    Petersen, Richard C; Liu, Perng-Ru

    Photocure fiber-reinforced composites (FRCs) with varying chopped quartz-fiber lengths were incorporated into a dental photocure zirconia-silicate particulate-filled composite (PFC) for mechanical test comparisons with a popular commercial spherical-particle amalgam. FRC lengths included 0.5-mm, 1.0 mm, 2.0 mm, and 3.0 mm all at a constant 28.2 volume percent. Four-point fully articulated fixtures were used according to American Standards Test Methods with sample dimensions of 2×2×50 mm 3 across a 40 mm span to provide sufficient Euler flexural bending and prevent top-load compressive shear error. Mechanical properties for flexural strength, modulus, yield strength, resilience, work of fracture, critical strain energy release, critical stress intensity factor, and strain were obtained for comparison. Fiber length subsequently correlated with increasing all mechanical properties, p amalgam than all composites, all FRCs and even the PFC had higher values than amalgam for all other mechanical properties. Because amalgams provide increased longevity during clinical use compared to the standard PFCs, modulus would appear to be a mechanical property that might sufficiently reduce margin interlaminar shear stress and strain-related microcracking that could reduce failure rates. Also, since FRCs were tested with all mechanical properties that statistically significantly increased over the PFC, new avenues for future development could be provided toward surpassing amalgam in clinical longevity.

  18. Association between oral lichenoid reactions and amalgam restorations.

    Science.gov (United States)

    Pezelj-Ribarić, S; Prpić, J; Miletić, I; Brumini, G; Soskić, M Simunović; Anić, I

    2008-11-01

    The aim of this study was to perform a clinical assessment of the association between oral lichenoid reactions (OLR) and amalgam restorations and to determine the salivary concentrations of interleukin-6 (IL-6) and IL-8 before and after replacement of the amalgam restorations. The study included 20 patients with OLR and 20 healthy volunteers, who were examined between 2001 and 2005 at the Oral Medicine Unit of the Medical Faculty University of Rijeka. All patients were skin patch tested by an experienced physician. Saliva samples were collected, prepared and analysed for IL-6 and IL-8 concentrations using enzyme-linked immunosorbent assay. Sixteen out of 20 patch-tested patients showed a sensitization to inorganic mercury or amalgam. Total replacement of all amalgam fillings was carried out on 20 patients with fillings based on composite resin, gold, porcelain or a combination of these. Sixteen out of 20 patients showed complete healing of OLR; three patients had marked improvement, whereas one patient showed no improvement. Levels of IL-6 detected before replacement were significantly higher than IL-6 levels following the replacement (P = 0.003). The IL-8 levels measured before replacement procedure were significantly higher than the IL-8 levels after replacement of the fillings (P amalgam fillings with fillings based on other restorative materials, levels of both IL-6 and IL-8 shifted towards normal, as measured in healthy subjects.

  19. Optimizing the procedure for mercury recovery from dental amalgam.

    Science.gov (United States)

    Iano, Flávia Godoy; Santos Sobrinho, Ovídio dos; Silva, Thelma Lopes da; Pereira, Marlus Alves; Figueiredo, Paulo Jorge Moraes; Alberguini, Leny Borghesan Albertini; Granjeiro, José Mauro

    2008-01-01

    Mercury, as any other heavy metal, may cause environmental damages due to its accumulation and biotransformation. Dental offices, whether private or institutional, use dental amalgam as a restorative material on a daily basis. Dental amalgam is composed of mercury (50%), silver (30%) and other metals. Approximately 30% of the amalgam prepared in dental offices (0.6 g per capsule) are wasted and inadequately discarded without any treatment. Methods for mercury recovery have been proposed previously, using high temperatures through exposure to direct flame (650 degrees C), long processing time, and hazardous reagents as potassium cyanide. The purpose of this study was to develop a method to replace the direct flame by an electrical mantle in the process of mercury recovery. Results showed an average mercury recovery of 90% from 2 kg of amalgam after 30 minutes of processing time, thus optimizing the procedure. The proposed modifications allowed a significant reduction in processing time and a mercury recovery with high purity. The modified process also provided minimization of operator exposure to physical, chemical and ergonomic hazards, representing a technological advance compared to the risks inherent to the original method. It also provided environmental health and economy of energy resources by replacing a finite energy source (fossil and organic) by a more environmentally appropriate electric source, resulting in significant improvement of the procedure for mercury recovery from dental amalgam.

  20. Optimizing the procedure for mercury recovery from dental amalgam

    Directory of Open Access Journals (Sweden)

    Flávia Godoy Iano

    2008-06-01

    Full Text Available Mercury, as any other heavy metal, may cause environmental damages due to its accumulation and biotransformation. Dental offices, whether private or institutional, use dental amalgam as a restorative material on a daily basis. Dental amalgam is composed of mercury (50%, silver (30% and other metals. Approximately 30% of the amalgam prepared in dental offices (0.6 g per capsule are wasted and inadequately discarded without any treatment. Methods for mercury recovery have been proposed previously, using high temperatures through exposure to direct flame (650°C, long processing time, and hazardous reagents as potassium cyanide. The purpose of this study was to develop a method to replace the direct flame by an electrical mantle in the process of mercury recovery. Results showed an average mercury recovery of 90% from 2 kg of amalgam after 30 minutes of processing time, thus optimizing the procedure. The proposed modifications allowed a significant reduction in processing time and a mercury recovery with high purity. The modified process also provided minimization of operator exposure to physical, chemical and ergonomic hazards, representing a technological advance compared to the risks inherent to the original method. It also provided environmental health and economy of energy resources by replacing a finite energy source (fossil and organic by a more environmentally appropriate electric source, resulting in significant improvement of the procedure for mercury recovery from dental amalgam.

  1. Impact of nocturnal bruxism on mercury uptake from dental amalgams.

    Science.gov (United States)

    Isacsson, G; Barregård, L; Seldén, A; Bodin, L

    1997-06-01

    The mercury (Hg) release from dental amalgam fillings increases by mechanical stimulation. The aim of this study was to investigate the possible impact of nocturnal bruxism on Hg exposure from dental amalgams and to evaluate the effect of an occlusal appliance. 88 female patients from an orofacial pain clinic with a complete maxillary and mandibular dentition, a normal frontal vertical overbite with cuspid guidance, and at least 4 occlusal amalgam fillings in contact with antagonists in intercuspidal position, were examined with the Bruxcore bruxism monitoring device to measure the level of on-going nocturnal bruxism. Based on the degree of abrasion recorded, the subjects were divided into a group defined as bruxists, (n = 29), another group defined as non-bruxists, (n = 32), serving as controls, the intermediate group being discarded. The Hg exposure was assessed from the Hg concentration in plasma and urine, corrected for the creatinine content. In a regression model with bruxism as the only explanatory variable, no significant effect of bruxism was found, but when the number of amalgam fillings, chewing gum use, and other background variables were taken into account, there was a limited impact of bruxism on Hg in plasma. The nocturnal use of an occlusal appliance did not, however, significantly change the Hg levels. This study indicates that mechanical wear on amalgams from nocturnal bruxism may increase the Hg uptake, but the magnitude of this effect seems to be less than from the use of chewing gum.

  2. Expansion of contaminated amalgams assessed by photoelastic resin.

    Science.gov (United States)

    Osborne, J W

    1999-10-01

    Eight amalgam alloys, 6 high-copper and 2 low-copper, were assessed for expansion via photoelastic resin. The photoelastic resin sheet was sectioned into 20 x 25-mm blocks, and two 4 x 8-mm holes were drilled into the resin. The amalgam alloys were hand condensed into the prepared holes. Test conditions for each alloy were (1) uncontaminated, (2) contaminated with 5 microL of Ringer's solution, and (3) contaminated with 5 microL of cell culture medium. Contaminated high-copper amalgam alloys may exhibit expansion to varying degrees but do not show the classic delayed expansion. One spherical, nonzinc high-copper alloy showed no expansion, whether it was uncontaminated or contaminated, and 3 high-copper alloys with different amounts of zinc (0% to 1%) showed slight expansion when contaminated. One low-copper alloy displayed delayed expansion; within 17 days after initial expansion in the photoelastic resin, it had exceeded the greatest stress observed in any contaminated, high-copper zinc-containing alloy at 3 months. Contamination of dental amalgam is to be avoided, but a zinc-containing high-copper amalgam will not exhibit classic delayed expansion even if contaminated.

  3. Mercury Exposure Levels in Children with Dental Amalgam Fillings

    Science.gov (United States)

    Miriam Varkey, Indu; Shetty, Rajmohan; Hegde, Amitha

    2014-01-01

    ABSTRACT% Objectives: Mercury combined with other metals to form solid amalgams has long been used in reconstructive dentistry but its use has been controversial since at least the middle of the 19th century. The exposure and body burden of mercury reviews have consistently stated that there is a deficiency of adequate epidemiological studies addressing this issue. Fish and dental amalgam are two major sources of human exposure to organic (MeHg) and inorganic Hg respectively. Materials and methods: A total of 150 subjects aged between 9 and 14 years were divided into two groups of 75 subjects each depending on their diet, i.e. seafood or nonseafood consuming. Each category was subdivided into three groups based on number of restorations. Scalp hair and urine samples were collected at baseline and 3 months later to assess the organic and inorganic levels of mercury respectively by atomic absorption spectrophotometer (AAS). Results: The mean values of urinary mercury (inorganic mercury) in the group of children with restorations were 1.5915 μg/l as compared to 0.0130 μg/l in the groups with no amalgam restorations (p amalgam restorations as a sole exposure source needs to be put to a rest, as environmental factors collectively overpower the exposure levels from restorations alone. How to cite this article: Varkey IM, Shetty R, Hegde A. Mercury Exposure Levels in Children with Dental Amalgam Fillings. Int J Clin Pediatr Dent 2014;7(3):180-185. PMID:25709298

  4. Unsymmetrical Chelation of N-Thioether-Functionalized Bis(diphenylphosphino)amine-Type Ligands and Substituent Effects on the Nuclearity of Iron(II) Complexes: Structures, Magnetism, and Bonding.

    Science.gov (United States)

    Fliedel, Christophe; Rosa, Vitor; Falceto, Andrés; Rosa, Patrick; Alvarez, Santiago; Braunstein, Pierre

    2015-07-06

    Starting from the short-bite ligands N-thioether-functionalized bis(diphenylphosphino)amine-type (Ph2P)2N(CH2)3SMe (1) and (Ph2P)2N(p-C6H4)SMe (2), the Fe(II) complexes [FeCl2(1)]n (3), [FeCl2(2)]2 (4), [Fe(OAc)(1)2]PF6 (5), and [Fe(OAc)(2)2]PF6 (6) were synthesized and characterized by Fourier transform IR, mass spectrometry, elemental analysis, and also by X-ray diffraction for 3, 4, and 6. Complex 3 is a coordination polymer in which 1 acts as a P,P-pseudochelate and a (P,P),S-bridge, whereas 4 has a chlorido-bridged dinuclear structure in which 2 acts only as a P,P-pseudochelate. Since these complexes were obtained under strictly similar synthetic and crystallization conditions, these unexpected differences were ascribed to the different spacer between the nitrogen atom and the −SMe group. In both compounds, one Fe–P bond was found to be unusually long, and a theoretical analysis was performed to unravel the electronic or steric reasons for this difference. Density functional theory calculations were performed for a set of complexes of general formula [FeCl2(SR2){R21PN(R2)P′R23}] (R = H, Me; R1, R2, and R3 = H, Me, Ph), to understand the reasons for the significant deviation of the iron coordination sphere away from tetrahedral as well as from trigonal bipyramidal and the varying degree of unsymmetry of the two Fe–P bonds involving pseudochelating PN(R)P ligands. Electronic factors nicely explain the observed structures, and steric reasons were further ruled out by the structural analysis in the solid-state of the bis-chelated complex 6, which displays usual and equivalent Fe–P bond lengths. Magnetic susceptibility studies were performed to examine how the structural differences between 3 and 4 would affect the interactions between the iron centers, and it was concluded that 3 behaves as an isolated high-spin Fe(II) mononuclear complex, while significant intra- and intermolecular ferromagnetic interactions were evidenced for 4 at low temperatures

  5. Preparation and corrosion behavior evaluation of amalgam/titania nano composite

    Directory of Open Access Journals (Sweden)

    Neda Bahremandi Tolou

    2011-01-01

    Conclusion: By adding nano particles of titania and preparing amalgam/titania nano composite as a dental amalgam, corrosion behavior and mercury release during the 2 st h after preparation could be improved.

  6. A prospective study of prenatal mercury exposure from maternal dental amalgams and autism severity.

    Science.gov (United States)

    Geier, David A; Kern, Janet K; Geier, Mark R

    2009-01-01

    Dental amalgams containing 50% mercury (Hg) have been used in dentistry for the last 150 years, and Hg exposure during key developmental periods was associated with autism spectrum disorders (ASDs). This study examined increased Hg exposure from maternal dental amalgams during pregnancy among 100 qualifying participants born between 1990-1999 and diagnosed with DSM-IV autism (severe) or ASD (mild). Logistic regression analysis (age, gender, race, and region of residency adjusted) by quintile of maternal dental amalgams during pregnancy revealed the ratio of autism:ASD (severe:mild) were about 1 (no effect) for amalgams and increased for > or =6 amalgams. Subjects with > or =6 amalgams were 3.2-fold significantly more likely to be diagnosed with autism (severe) in comparison to ASD (mild) than subjects with amalgams. Dental amalgam policies should consider Hg exposure in women before and during the child-bearing age and the possibility of subsequent fetal exposure and adverse outcomes.

  7. Residual mercury content and leaching of mercury and silver from used amalgam capsules.

    Science.gov (United States)

    Stone, M E; Pederson, E D; Cohen, M E; Ragain, J C; Karaway, R S; Auxer, R A; Saluta, A R

    2002-06-01

    The objective of this investigation was to carry out residual mercury (Hg) determinations and toxicity characteristic leaching procedure (TCLP) analysis of used amalgam capsules. For residual Hg analysis, 25 capsules (20 capsules for one brand) from each of 10 different brands of amalgam were analyzed. Total residual Hg levels per capsule were determined using United States Environmental Protection Agency (USEPA) Method 7471. For TCLP analysis, 25 amalgam capsules for each of 10 brands were extracted using a modification of USEPA Method 1311. Hg analysis of the TCLP extracts was done with USEPA Method 7470A. Analysis of silver (Ag) concentrations in the TCLP extract was done with USEPA Method 6010B. Analysis of the residual Hg data resulted in the segregation of brands into three groups: Dispersalloy capsules, Group A, retained the most Hg (1.225 mg/capsule). These capsules were the only ones to include a pestle. Group B capsules, Valliant PhD, Optaloy II, Megalloy and Valliant Snap Set, retained the next highest amount of Hg (0.534-0.770 mg/capsule), and were characterized by a groove in the inside of the capsule. Group C, Tytin regular set double-spill, Tytin FC, Contour, Sybraloy regular set, and Tytin regular set single-spill retained the least amount of Hg (0.125-0.266 mg/capsule). TCLP analysis of the triturated capsules showed Sybraloy and Contour leached Hg at greater than the 0.2 mg/l Resource Conservation and Recovery Act (RCRA) limit. This study demonstrated that residual mercury may be related to capsule design features and that TCLP extracts from these capsules could, in some brands, exceed RCRA Hg limits, making their disposal problematic. At current RCRA limits, the leaching of Ag is not a problem.

  8. In vivo intraoral reflectance confocal microscopy of an amalgam tattoo.

    Science.gov (United States)

    Yélamos, Oriol; Cordova, Miguel; Peterson, Gary; Pulitzer, Melissa P; Singh, Bhuvanesh; Rajadhyaksha, Milind; DeFazio, Jennifer L

    2017-10-01

    The majority of oral pigmentations are benign lesions such as nevi, melanotic macules, melanoacanthomas or amalgam tattoos. Conversely, mucosal melanomas are rare but often lethal; therefore, excluding oral melanomas in this setting is crucial. Reflectance confocal microscopy is a non-invasive, in vivo imaging system with cellular resolution that has been used to distinguish benign from malignant pigmented lesions in the skin, and more recently in the mucosa. However, lesions located posteriorly in the oral cavity are difficult to assess visually and difficult to biopsy due to their location. Herein we present a patient with previous multiple melanomas presenting with an oral amalgam tattoo in the buccal mucosa, which was imaged using an intraoral telescopic probe attached to a commercially available handheld RCM. In this case report we describe this novel probe, the first RCM description of an amalgam tattoo and we discuss its differences with the findings described in oral melanomas.

  9. [Normal and induced Hg release from different amalgams].

    Science.gov (United States)

    Zimmermann, M; Mairgünther, R; Scheuber, T; Hamm, G

    1993-01-01

    In an experimental investigation of 20 subjects who had no amalgam fillings, the mercury load from artificially applied, standardised amalgam surfaces was tested for one product containing gamma-2 and one free of gamma-2 respectively. The product which contained gamma-2 caused a statistically significant increase in Hg concentrations in the 24-hour urine sample. After challenge with Dimaval, an intensifying effect on the elimination rate could be detected, although all values clearly remained below a toxicologically relevant concentration. In order to avoid unnecessary exposure to heavy metals, the use of gamma-2-free amalgams and, in the long term, the development of optimised filling materials and intensification of prophylactic measures for prevention of dental caries are to be welcomed.

  10. Kinetic study of lithium-cadmium ternary amalgam decomposition

    International Nuclear Information System (INIS)

    Cordova, M.H.; Andrade, C.E.

    1992-01-01

    The effect of metals, which form stable lithium phase in binary alloys, on the formation of intermetallic species in ternary amalgams and their effect on thermal decomposition in contact with water is analyzed. Cd is selected as ternary metal, based on general experimental selection criteria. Cd (Hg) binary amalgams are prepared by direct contact Cd-Hg, whereas Li is formed by electrolysis of Li OH aq using a liquid Cd (Hg) cathodic well. The decomposition kinetic of Li C(Hg) in contact with 0.6 M Li OH is studied in function of ageing and temperature, and these results are compared with the binary amalgam Li (Hg) decomposition. The decomposition rate is constant during one hour for binary and ternary systems. Ageing does not affect the binary systems but increases the decomposition activation energy of ternary systems. A reaction mechanism that considers an intermetallic specie participating in the activated complex is proposed and a kinetic law is suggested. (author)

  11. Patients? experiences of changes in health complaints before, during, and after removal of dental amalgam

    OpenAIRE

    Sjursen, Therese T.; Binder, Per-Einar; Lygre, Gunvor B.; Helland, Vigdis; Dalen, Knut; Bj?rkman, Lars

    2015-01-01

    In this article, we explore how patients with health complaints attributed to dental amalgam experienced and gave meaning to changes in health complaints before, during, and after removal of all amalgam fillings. We conducted semistructured qualitative interviews with 12 participants from the treatment group in a Norwegian amalgam removal trial. Interviews took place within a couple months of the final follow-up 5 years after amalgam removal. Using the NVivo9 software, we conducted an explora...

  12. Management of large radicular cyst associated with amalgam particles in cystic lining

    OpenAIRE

    Borkar, Swati A.; Dhupar, Vikas; Gadkar, Abhilasha M.; Nivedita, C.K.V.S.

    2016-01-01

    The failure of amalgam retrofilling and presence of an associated cystic lesion makes surgical endodontic intervention inevitable. Amalgam retrofilling can also give rise to mucoperiosteal tattoo formation and allow incorporation of amalgam particles in the cystic lining. Such a finding has not yet been reported in the endodontic literature. This case report describes the successful endodontic management of a large radicular cyst associated with failed amalgam retrofilling, mucoperiosteal tat...

  13. Surface group amalgams that (don't) act on 3-manifolds

    OpenAIRE

    Hruska, G. Christopher; Stark, Emily; Tran, Hung Cong

    2017-01-01

    We determine which amalgamated products of surface groups identified over multiples of simple closed curves are not fundamental groups of 3-manifolds. We prove each surface amalgam considered is virtually the fundamental group of a 3-manifold. We prove that each such surface group amalgam is abstractly commensurable to a right-angled Coxeter group from a related family. In an appendix, we determine the quasi-isometry classes among these surface amalgams and their related right-angled Coxeter ...

  14. A dose-dependent relationship between mercury exposure from dental amalgams and urinary mercury levels: a further assessment of the Casa Pia Children's Dental Amalgam Trial.

    Science.gov (United States)

    Geier, D A; Carmody, T; Kern, J K; King, P G; Geier, Mark R

    2012-01-01

    Dental amalgams are a commonly used dental restorative material, and amalgams are about 50% mercury (Hg). In our study, urinary Hg levels was examined in children of age 8-18 years, with and without dental amalgam fillings, from a completed clinical trial (parent study) that was designed to evaluate the potential health consequences of prolonged exposure to Hg from dental amalgam fillings. Our study was designed to determine whether there was a significant dose-dependent correlation between increasing Hg exposure from dental amalgams and urinary Hg levels. Hg exposure depends on the size and number of teeth with dental amalgams. Overall, consistent with the results observed in the parent study, there was a statistically significant dose-dependent correlation between cumulative exposure to Hg from dental amalgams and urinary Hg levels, after covariate adjustment. Further, it was observed that urinary Hg levels increased by 18% to 52% among 8 to 18 year old individuals, respectively, with an average exposure to amalgams, in comparison to study subjects with no exposure to amalgams. The results of our study suggest that dental amalgams contribute to ongoing Hg exposure in a dose-dependent fashion.

  15. The amalgam-free dental school.

    NARCIS (Netherlands)

    Roeters, F.J.M.; Opdam, N.J.M.; Loomans, B.A.C.

    2004-01-01

    OBJECTIVES: To review the change in teaching of Restorative Dentistry at Nijmegen dental school over the period 1986 to the present. KEY POINTS: In 1986, class I and II resin composite restorations were included in the pre-clinical program. However, these courses still started with class I and II

  16. Aggravated neuromuscular symptoms of mercury exposure from dental amalgam fillings.

    Science.gov (United States)

    Akbal, Ayla; Yılmaz, Hınç; Tutkun, Engin; Köş, Durdu Mehmet

    2014-01-01

    Dental amalgam fillings are widely used all over the world. However, their mercury content can lead to various side effects and clinical problems. Acute or chronic mercury exposure can cause several side effects on the central nerve system, renal and hepatic functions, immune system, fetal development and it can play a role on exacerbation of neuromuscular diseases. In this case, we will present a patient with vacuolar myopathy whose symptoms were started and aggravated with her dental amalgam fillings. Copyright © 2013 Elsevier GmbH. All rights reserved.

  17. Amalgam tattoo mimicking mucosal melanoma: a diagnostic dilemma revisited.

    Science.gov (United States)

    Lundin, K; Schmidt, G; Bonde, C

    2013-01-01

    Mucosal melanoma of the oral cavity is a rare but highly aggressive neoplasm. However, the clinicians need to be aware of the other and more frequent etiologies of intraoral pigmentation, such as amalgam tattoos. As amalgam has been extensively used for dental restorations and can cause pigmentations in the oral mucosa, this is a differential diagnosis not to be forgotten. We describe the characteristics of these two phenomena and present a case vignette illustrating the differential diagnostic issues. Other causes of intraoral pigmentation are summarized.

  18. Amalgam Tattoo Mimicking Mucosal Melanoma: A Diagnostic Dilemma Revisited

    Directory of Open Access Journals (Sweden)

    K. Lundin

    2013-01-01

    Full Text Available Mucosal melanoma of the oral cavity is a rare but highly aggressive neoplasm. However, the clinicians need to be aware of the other and more frequent etiologies of intraoral pigmentation, such as amalgam tattoos. As amalgam has been extensively used for dental restorations and can cause pigmentations in the oral mucosa, this is a differential diagnosis not to be forgotten. We describe the characteristics of these two phenomena and present a case vignette illustrating the differential diagnostic issues. Other causes of intraoral pigmentation are summarized.

  19. Urinary porphyrin excretion in children with mercury amalgam treatment: findings from the Casa Pia Children's Dental Amalgam Trial.

    Science.gov (United States)

    Woods, James S; Martin, Michael D; Leroux, Brian G; DeRouen, Timothy A; Bernardo, Mario F; Luis, Henrique S; Leitão, Jorge G; Simmonds, P Lynne; Echeverria, Diana; Rue, Tessa C

    2009-01-01

    Increases in the urinary concentrations of pentacarboxyl- and coproporphyrins and the appearance of the atypical precoproporphyrin have been defined in relation to mercury (Hg) body burden in animal studies, and this change in the porphyrin excretion pattern has been described as a biomarker of occupational Hg exposure and toxicity in adult human subjects. In the present studies, urinary porphyrins were determined in relation to Hg exposure in children and adolescents, 8-18 yr of age, over the 7-yr course of a clinical trial designed to evaluate the neurobehavioral and renal effects of dental amalgam in children. Subjects were randomized to either dental amalgam or composite resin treatments. Urinary porphyrins and creatinine concentrations were measured at baseline and annually in all subjects. Results were evaluated using linear regression analysis. No significant differences between treatment groups (amalgam versus composite) were found when comparing all subjects for any of the porphyrins of interest. However, incipent amalgam treatment-specific increases were observed in the mean concentrations of penta-, precopro- and coproporphyrins especially when the analyses were restricted to younger subjects (8 to 9 yr old at baseline), and these increases were most apparent during yr 2 through 3 of follow-up, the period of highest mercury exposure from amalgam treatment. Based on the mean number of amalgam fillings received by children in this group (17.8), the renal Hg concentration associated with incipient increases in urinary porphyrins was estimated to be approximately 2.7 microg/g renal cortex. This value corresponds to an observed mean urinary Hg concentration of 3.2 microg/g creatinine, which is approximately fivefold less than that at which renal damage from Hg exposure is estimated to occur in children. These findings are consistent with growing evidence supporting the sensitivity of urinary porphyrins as a biological indicator of subclinical Hg exposure in

  20. Non-bonding interactions and non-covalent delocalization effects play a critical role in the relative stability of group 12 complexes arising from interaction of diethanoldithiocarbamate with the cations of transition metals Zn(II), Cd(II), and Hg(II): a theoretical study.

    Science.gov (United States)

    Bahrami, Homayoon; Farhadi, Saeed; Siadatnasab, Firouzeh

    2016-07-01

    The chelating properties of diethanoldithiocarbamate (DEDC) and π-electron flow from the nitrogen atom to the sulfur atom via a plane-delocalized π-orbital system (quasi ring) was studied using a density functional theory method. The molecular structure of DEDC and its complexes with Zn(II), Cd(II), and Hg(II) were also considered. First, the geometries of this ligand and DEDC-Zn(II), DEDC-Cd(II), and DEDC-Hg(II) were optimized, and the formation energies of these complexes were then calculated based on the electronic energy, or sum of electronic energies, with the zero point energy of each species. Formation energies indicated the DEDC-Zn(II) complex as the most stable complex, and DEDC-Cd(II) as the least stable. Structural data showed that the N1-C2 π-bond was localized in the complexes rather than the ligand, and a delocalized π-bond over S7-C2-S8 was also present. The stability of DEDC-Zn(II), DEDC-Cd(II), and DEDC-Hg(II) complexes increased in the presence of the non-specific effects of the solvent (PCM model), and their relative stability did not change. There was π-electron flow or resonance along N1-C2-S7 and along S7-C2-S8 in the ligand. The π-electron flow or resonance along N1-C2-S7 was abolished when the metal interacted with sulfur atoms. Energy belonging to van der Waals interactions and non-covalent delocalization effects between the metal and sulfur atoms of the ligand was calculated for each complex. The results of nucleus-independent chemical shift (NICS) indicated a decreasing trend as Zn(II) Hg(II) for the aromaticity of the quasi-rings. Finally, by ignoring van der Waals interactions and non-covalent delocalization effects between the metal and sulfur atoms of the ligand, the relative stability of the complexes was changed as follows:[Formula: see text] Graphical Abstract Huge electronic cloud localized on Hg(II) in the Hg(II)-DEDC complex.

  1. In vitro cytotoxicity of amalgams made with binary Hg-In liquid alloys.

    Science.gov (United States)

    Nakajima, H; Wataha, J C; Rockwell, L C; Okabe, T

    1997-05-01

    Mercury vapor release from amalgams during setting significantly decreases when the amalgams are prepared with binary Hg-In liquid alloys. The objective of this study was to compare the cytotoxicity of amalgams made with experimental Hg-In alloys with that of amalgam without In and a commercial In-containing amalgam. Amalgam specimens were prepared by triturating a high-Cu alloy powder (Tytin, Kerr) with pure Hg or Hg-In liquid alloy containing 5, 20 or 50% In and also by triturating an In-containing high-copper alloy powder (Indiloy, Shofu) with pure Hg. After the specimens were aged for 2 wk, a cylindrical specimen of each amalgam was immersed consecutively in cell culture medium for 0-8, 8-48 and 48-72 h. The cytotoxicity of the extracts was determined by placing them in contact with Balb/c 3T3 mouse fibroblasts for 24 h, after which the succinic dehydrogenase (SDH) activity was measured and expressed as a percentage of the Teflon negative controls. The results were statistically compared using ANOVA and Tukey's test (alpha = 0.05). The concentration of elements released into the extracts was determined by atomic absorption spectrophotometry and evaluated by Kruskal-Wallis and nonparametric multiple comparisons. For the 0-8 h and 8-48 h intervals, the 20% In amalgam was significantly (p amalgams, and not different from the Teflon control. Results for the other amalgams were only slightly depressed compared to the Teflon control. For the 48-72 h interval, all amalgams were essentially no different from the control. Copper was the element dominantly released into the medium from all the amalgams tested. For amalgam tested after aging, alloying indium to mercury did not deleteriously affect the cytotoxicity of the resultant amalgam compared to the amalgam without indium.

  2. Biomechanical Stress Analysis of Mandibular First Permanent Molar; Restored with Amalgam and Composite Resin: A Computerized Finite Element Study.

    Science.gov (United States)

    Musani, Iqbal; Prabhakar, A R

    2010-01-01

    Normal mastication with its varying magnitude and direction generates considerable reactionary stresses in teeth and their supporting tissues. The structure of the human tooth and its supporting tissues is a complex assemblage of materials of varied mechanical properties. The finite element method (FEM), a modern technique of numerical stress analysis, has the great advantage of being applicable to solids of irregular geometry and heterogeneous material properties and therefore ideally suited to the examination of structural behavior of teeth. The mandibular first permanent molar is one of the earliest permanent teeth to erupt in the oral cavity and hence most prone to caries. The purpose of the present study was to construct a two-dimensional FE model of the mandibular first permanent molar and its supporting structures, using a FE software called NISA II-Display III, EMRC, USA to study the following: • To compare stress distributions patterns when a modeled Class I Cavity was restored with dental amalgam and composite resin. • To compare the stress distributions pattern when the load was applied to different to locations, i.e.: At the mesial cusp tip, and at the center of the occlusal surface. Both amalgam and composite resin showed similar stress distribution pattern, however, the magnitudes of stresses generated in the tooth restored with composite resin were higher. Thus, amalgam is a better restorative material in distributing stresses.

  3. Are institutional combinations, mergers or amalgamation the answer ...

    African Journals Online (AJOL)

    Many higher and further education institutions in South Africa are struggling to survive in a context of financial stringency, declining student enrolments and increasing competition. For some of these institutions merging or amalgamation with other institutions in the near future is becoming a strong likelihood. The perceptions ...

  4. Mercury Amalgam Diffusion in Human Teeth Probed Using Femtosecond LIBS.

    Science.gov (United States)

    Bello, Liciane Toledo; da Ana, Patricia Aparecida; Santos, Dário; Krug, Francisco José; Zezell, Denise Maria; Vieira, Nilson Dias; Samad, Ricardo Elgul

    2017-04-01

    In this work the diffusion of mercury and other elements from amalgam tooth restorations through the surrounding dental tissue (dentin) was evaluated using femtosecond laser-induced breakdown spectroscopy (fs-LIBS). To achieve this, seven deciduous and eight permanent extracted human molar teeth with occlusal amalgam restorations were half-sectioned and analyzed using pulses from a femtosecond laser. The measurements were performed from the amalgam restoration along the amalgam/dentin interface to the apical direction. It was possible to observe the presence of metallic elements (silver, mercury, copper and tin) emission lines, as well as dental constituent ones, providing fingerprints of each material and comparable data for checking the consistence of the results. It was also shown that the elements penetration depth values in each tooth are usually similar and consistent, for both deciduous and permanent teeth, indicating that all the metals diffuse into the dentin by the same mechanism. We propose that this diffusion mechanism is mainly through liquid dragging inside the dentin tubules. The mercury diffused further in permanent teeth than in deciduous teeth, probably due to the longer diffusion times due to the age of the restorations. It was possible to conclude that the proposed femtosecond-LIBS system can detect the presence of metals in the dental tissue, among the tooth constituent elements, and map the distribution of endogenous and exogenous chemical elements, with a spatial resolution that can be brought under 100 µm.

  5. Particle size analysis of amalgam powder and handpiece generated specimens.

    Science.gov (United States)

    Drummond, J L; Hathorn, R M; Cailas, M D; Karuhn, R

    2001-07-01

    The increasing interest in the elimination of amalgam particles from the dental waste (DW) stream, requires efficient devices to remove these particles. The major objective of this project was to perform a comparative evaluation of five basic methods of particle size analysis in terms of the instrument's ability to quantify the size distribution of the various components within the DW stream. The analytical techniques chosen were image analysis via scanning electron microscopy, standard wire mesh sieves, X-ray sedigraphy, laser diffraction, and electrozone analysis. The DW particle stream components were represented by amalgam powders and handpiece/diamond bur generated specimens of enamel; dentin, whole tooth, and condensed amalgam. Each analytical method quantified the examined DW particle stream components. However, X-ray sedigraphy, electrozone, and laser diffraction particle analyses provided similar results for determining particle distributions of DW samples. These three methods were able to more clearly quantify the properties of the examined powder and condensed amalgam samples. Furthermore, these methods indicated that a significant fraction of the DW stream contains particles less than 20 microm. The findings of this study indicated that the electrozone method is likely to be the most effective technique for quantifying the particle size distribution in the DW particle stream. This method required a relative small volume of sample, was not affected by density, shape factors or optical properties, and measured a sufficient number of particles to provide a reliable representation of the particle size distribution curve.

  6. BACTERIAL ADHESION TO DENTAL AMALGAM AND 3 RESIN COMPOSITES

    NARCIS (Netherlands)

    SULJAK, JP; REID, G; WOOD, SM; MCCONNELL, RJ; VANDERMEI, HC; BUSSCHER, HJ

    Objectives: The ability of three oral bacteria to adhere to hydrophobic amalgam (water contact angle 60 degrees) and hydrophobic resin composites (Prisma-AP.H 56 degrees, Herculite XRV 82 degrees and Z100 89 degrees) was compared using an in vitro assay. Methods and results: Following preincubation

  7. Drop amalgam voltammetric study of lead complexation by natural ...

    African Journals Online (AJOL)

    Drop amalgam voltammetric study of lead complexation by natural inorganic ligands in a salt lake. ... Bulletin of the Chemical Society of Ethiopia ... The results obtained indicate that in Lake Katwe water (25 oC, carbonate alkalinity = 0.11 M, pH 11) approximately 0.00% of total inorganic lead exists as the free ion, and at ...

  8. Staining of dentin from amalgam corrosion is induced by demineralization

    NARCIS (Netherlands)

    Scholtanus, Johannes D.; van der Hoorn, Wietske; Huysmans, Marie-Charlotte D. N. J. M.; Roeters, Joost F. M.; Kleverlaan, Cornelis J.; Feilzer, Albert J.; Ozcan, Mutlu

    Purpose: To evaluate the effect of artificial demineralization upon color change of dentin in contact with dental amalgam. Methods: Sound human molars (n= 34) were embedded in resin and coronal enamel was removed. Dentin was exposed to artificial caries gel (pH 5.5) at 37 degrees C for 12 weeks (n=

  9. Staining of dentin from amalgam corrosion is induced by demineralization

    NARCIS (Netherlands)

    Scholtanus, J.D.; van der Hoorn, W.; Özcan, M.; Huysmans, M.C.D.N.J.M.; Roeters, J.F.M.; Kleverlaan, C.J.; Feilzer, A.J.

    2013-01-01

    PURPOSE: To evaluate the effect of artificial demineralization upon color change of dentin in contact with dental amalgam. METHODS: Sound human molars (n = 34) were embedded in resin and coronal enamel was removed. Dentin was exposed to artificial caries gel (pH 5.5) at 37 degrees C for 12 weeks (n

  10. Electrodes of Nontoxic Solid Amalgams for Electrochemical Measurements

    Czech Academy of Sciences Publication Activity Database

    Josypčuk, Bohdan; Novotný, Ladislav

    2002-01-01

    Roč. 14, č. 24 (2002), s. 1733-1738 ISSN 1040-0397 R&D Projects: GA ČR GV204/97/K084 Institutional research plan: CEZ:AV0Z4040901 Keywords : solid amalgam electrodes * voltammetry * electrochemical measurements Subject RIV: CG - Electrochemistry Impact factor: 1.783, year: 2002

  11. Amalgam vs Composite Restoration, Survival, and Secondary Caries.

    Science.gov (United States)

    Alhareky, Muhanad; Tavares, Mary

    2016-06-01

    Amalgam and resin composite longevity of posterior restorations: a systematic review and meta-analysis. Moraschini V, Fai CK, Alto RM, dos Santos GO. J Dent 2015;43(9):1043-50. Information not available Systematic review with meta-analysis of data. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. A systematic technique for carving amalgam and composite restorations.

    Science.gov (United States)

    Kilistoff, A

    2011-01-01

    Both amalgam and composite restorations can quickly and accurately be carved using a systematic technique. By following the outlined steps, anatomically accurate restorations can be easily achieved. Inlay wax is used as a training medium to negate the setting constraints and as a high fidelity simulation.

  13. The Fiscal Imperative in the Amalgamation of 1914 | Lawal ...

    African Journals Online (AJOL)

    Many historians that have written about Nigeria have shown a great deal of interest in the factors, which accounted for the amalgamation of 1914 by which Nigeria was established as a single political entity. The various works, which have been published, have treated exhaustively the administrative and political factors.1 ...

  14. Intermunicipal cooperation, municipal amalgamation and the price of credit

    NARCIS (Netherlands)

    Allers, Maarten A.; van Ommeren, Bernard

    2016-01-01

    In many countries, local government size is increasingly thought to be insufficient to operate efficiently. Two possible solutions to this problem are amalgamation and intermunicipal cooperation. This paper applies a novel methodology to shed light on the efficiency implications of this choice.

  15. Drop amalgam voltammetric study of lead complexation by natural ...

    African Journals Online (AJOL)

    A study of inorganic complexation of lead using drop amalgam voltammetry is described. The study has been carried out in simulated salt lake water and at ionic strength of 7.35 M, the predetermined ionic strength of Lake Katwe. The complexation of lead with the simple ligands (Cl-, CO32-) created anodic waves and the ...

  16. Determination of 5-nitroindazole using silver solid amalgam electrode

    Czech Academy of Sciences Publication Activity Database

    Nováková, Kateřina; Hrdlička, V.; Navrátil, Tomáš; Vyskočil, V.; Barek, J.

    2015-01-01

    Roč. 146, č. 5 (2015), s. 761-769 ISSN 0026-9247 R&D Projects: GA ČR(CZ) GAP208/12/1645 Institutional support: RVO:61388955 Keywords : 5-nitroindazole * hanging mercury drop electrode * silver sold amalgam electrode Subject RIV: CG - Electrochemistry Impact factor: 1.131, year: 2015

  17. Coordinating a Large, Amalgamated REU Program with Multiple Funding Sources

    Science.gov (United States)

    Fiorini, Eugene; Myers, Kellen; Naqvi, Yusra

    2017-01-01

    In this paper, we discuss the challenges of organizing a large REU program amalgamated from multiple funding sources, including diverse participants, mentors, and research projects. We detail the program's structure, activities, and recruitment, and we hope to demonstrate that the organization of this REU is not only beneficial to its…

  18. Issues of importance in phasing out dental amalgam | Kabulwa ...

    African Journals Online (AJOL)

    Dental amalgam contains about 50% of mercury in elemental form. It has been used for over 150 years for dental restoration due to its mechanical properties and the long term familiarity of dentists with its use. Despite these facts, there have been increasing awareness and recognition of implications caused by mercury ...

  19. Long-term survival of extensive amalgams and posterior crowns.

    Science.gov (United States)

    Smales, R J; Hawthorne, W S

    1997-01-01

    There is very little information available from private dental practices on the comparative survivals of extensive posterior amalgam restorations and posterior crowns placed in the same patient population. Therefore, the present retrospective study examined the performance of such restorations at three long-established Adelaide city practices. Life-table survival estimates were generated for 160 extensive amalgams, 96 cast gold crowns and 174 ceramometal crowns. The restorations were placed by 20 dentists at various times in 100 patients who attended the practices on a regular basis for around 25 years on average. There were no significant differences found in the survival times for both types of crowns, with around 70% still being present at 20 years. However, the median survival time for the extensive amalgams was much lower, at 14.6 years. Despite these differences in survival times, the extensive amalgam restorations survived for longer than is usually expected. In this present study, the survival findings have implications for the most cost-effective dental treatments of large lesions in posterior teeth.

  20. Solidification/Stabilization of Elemental Mercury Waste by Amalgamation

    Energy Technology Data Exchange (ETDEWEB)

    Yim, S. P.; Ahn, B. G.; Lee, H. J.; Shon, J. S.; Chung, H.; Kim, K. J.; Lee, C. K.

    2003-02-24

    Experiments on solidification of elemental mercury waste were conducted by amalgamation with several metal powders such as copper, zinc, tin, brass and bronze. Unlike the previous studies which showed a dispersible nature after solidification, the waste forms were found to possess quite large compressive strengths in both copper and bronze amalgam forms. The durability was also confirmed by showing very minor changes of strength after 90 days of water immersion. Leachability from the amalgam forms is also shown to be low: measured mercury concentration in the leachate by the Toxicity Characteristic Leaching Procedure (TCLP) was well below the Environmental Protection Agency (EPA) limit. Long term leaching behavior by Accelerated Leach Test (ALT) has shown that the leaching process was dominated by diffusion and the effective diffusion coefficient was quite low (around 10-19 cm2/sec). The mercury vapor concentration from the amalgam forms were reduced to a 20% level of that for elemental mercury and to one-hundredth after 3 months.

  1. Detecting DNA damage with a silver solid amalgam electrode

    Czech Academy of Sciences Publication Activity Database

    Kuchaříková, Kateřina; Novotný, Ladislav; Josypčuk, Bohdan; Fojta, Miroslav

    2004-01-01

    Roč. 16, č. 5 (2004), s. 410-414 ISSN 1040-0397 R&D Projects: GA AV ČR IAA4004108; GA AV ČR IBS5004355 Institutional research plan: CEZ:AV0Z5004920 Keywords : DNA damage * silver solid amalgam electrode * HMDE Subject RIV: BO - Biophysics Impact factor: 2.038, year: 2004

  2. Determination of Iodates using Silver Solid Amalgam Electrodes

    Czech Academy of Sciences Publication Activity Database

    Josypčuk, Bohdan; Novotný, Ladislav

    2002-01-01

    Roč. 14, 15/16 (2002), s. 1138-1142 ISSN 1040-0397 R&D Projects: GA ČR GV204/97/K084 Institutional research plan: CEZ:AV0Z4040901 Keywords : silver solid amalgam electrodes * voltammetry * table salt Subject RIV: CG - Electrochemistry Impact factor: 1.783, year: 2002

  3. Voltammetric determination of leucovorin using silver solid amalgam electrode

    Czech Academy of Sciences Publication Activity Database

    Šelešovská, R.; Bandžuchová, L.; Navrátil, Tomáš; Chýlková, J.

    2012-01-01

    Roč. 60, JAN 2012 (2012), s. 375-383 ISSN 0013-4686 R&D Projects: GA AV ČR IAA400400806; GA ČR GAP206/11/1638 Institutional research plan: CEZ:AV0Z40400503 Keywords : leucovorin * voltammetry * amalgam electrode Subject RIV: CG - Electrochemistry Impact factor: 3.777, year: 2012

  4. Oxidative Reactivity and Cytotoxic Properties of a Platinum(II) Complex Prepared by Outer-Sphere Amide Bond Coupling

    Science.gov (United States)

    Wilson, Justin J.; Lippard, Stephen J.

    2012-01-01

    Benzyl amine was coupled to the dangling carboxylic acid groups of the platinum(II) complex [Pt(edda)Cl2], where edda = ethylenediamine-N,N’-diacetic acid, to give the diamidetethered complex [Pt(L)Cl2] (1), where L = ethylenediamine-N,N’-bis(N-benzylacetamide). Complex 1 was oxidized with both PhICl2 and Br2. Oxidation with PhICl2 cleanly afforded the tetrachloride complex, [Pt(L)Cl4] (2), whereas oxidation with Br2 gave rise to several mixed halide complexes of the general formula, [Pt(L)ClxBr4-x], where x = 1, 2, or 3. Complexes 1 and 2 were fully characterized by 1H, 13C, and 195Pt NMR spectroscopy, as well as by ESI-MS. These compounds exist as a mixture of diastereomers that arise from the chirality of the two coordinated nitrogen atoms. Crystal structures of 1, 2, and [Pt(L)ClxBry] (3) are reported. Although refined as the tetrabromide complex [Pt(L)Br4], the crystal structure of 3 is a mixture of species with site-occupancy disorder of chloride and bromide ligands. DFT calculations indicate that the two sets of diastereomers of 1 and 2 are effectively thermoneutral, a conclusion that is also supported by the observation of both members of each pair by NMR spectroscopy. The cytotoxicity of 1 and 2 was measured by the MTT assay in HeLa cells and compared to that of cisplatin. Both exhibit IC50 values close to 50 μM and are therefore substantially less toxic than cisplatin, for which the IC50 is 1 μM. PMID:24489429

  5. Maternal-fetal distribution of mercury (203Hg) released from dental amalgam fillings

    International Nuclear Information System (INIS)

    Vimy, M.J.; Takahashi, Y.; Lorscheider, F.L.

    1990-01-01

    In humans, the continuous release of Hg vapor from dental amalgam tooth restorations is markedly increased for prolonged periods after chewing. The present study establishes a time-course distribution for amalgam Hg in body tissues of adult and fetal sheep. Under general anesthesia, five pregnant ewes had twelve occlusal amalgam fillings containing radioactive 203Hg placed in teeth at 112 days gestation. Blood, amniotic fluid, feces, and urine specimens were collected at 1- to 3-day intervals for 16 days. From days 16-140 after amalgam placement (16-41 days for fetal lambs), tissue specimens were analyzed for radioactivity, and total Hg concentrations were calculated. Results demonstrate that Hg from dental amalgam will appear in maternal and fetal blood and amniotic fluid within 2 days after placement of amalgam tooth restorations. Excretion of some of this Hg will also commence within 2 days. All tissues examined displayed Hg accumulation. Highest concentrations of Hg from amalgam in the adult occurred in kidney and liver, whereas in the fetus the highest amalgam Hg concentrations appeared in liver and pituitary gland. The placenta progressively concentrated Hg as gestation advanced to term, and milk concentration of amalgam Hg postpartum provides a potential source of Hg exposure to the newborn. It is concluded that accumulation of amalgam Hg progresses in maternal and fetal tissues to a steady state with advancing gestation and is maintained. Dental amalgam usage as a tooth restorative material in pregnant women and children should be reconsidered

  6. Mechanical Properties Comparing Composite Fiber Length to Amalgam

    Directory of Open Access Journals (Sweden)

    Richard C. Petersen

    2016-01-01

    Full Text Available Photocure fiber-reinforced composites (FRCs with varying chopped quartz-fiber lengths were incorporated into a dental photocure zirconia-silicate particulate-filled composite (PFC for mechanical test comparisons with a popular commercial spherical-particle amalgam. FRC lengths included 0.5-mm, 1.0 mm, 2.0 mm, and 3.0 mm all at a constant 28.2 volume percent. Four-point fully articulated fixtures were used according to American Standards Test Methods with sample dimensions of 2×2×50 mm3 across a 40 mm span to provide sufficient Euler flexural bending and prevent top-load compressive shear error. Mechanical properties for flexural strength, modulus, yield strength, resilience, work of fracture, critical strain energy release, critical stress intensity factor, and strain were obtained for comparison. Fiber length subsequently correlated with increasing all mechanical properties, p<1.1×10-5. Although the modulus was significantly statistically higher for amalgam than all composites, all FRCs and even the PFC had higher values than amalgam for all other mechanical properties. Because amalgams provide increased longevity during clinical use compared to the standard PFCs, modulus would appear to be a mechanical property that might sufficiently reduce margin interlaminar shear stress and strain-related microcracking that could reduce failure rates. Also, since FRCs were tested with all mechanical properties that statistically significantly increased over the PFC, new avenues for future development could be provided toward surpassing amalgam in clinical longevity.

  7. Postirradiation results and evaluation of helium-bonded uranium--plutonium carbide fuel elements irradiated in EBR-II. Interim report

    International Nuclear Information System (INIS)

    Latimer, T.W.; Barner, J.O.; Kerrisk, J.F.; Green, J.L.

    1976-02-01

    An evaluation was made of the performance of 74 helium-bonded uranium-plutonium carbide fuel elements that were irradiated in EBR-II at 38-96 kW/m to 2-12 at. percent burnup. Only 38 of these elements have completed postirradiation examination. The higher failure rate found in fuel elements which contained high-density (greater than 95 percent theoretical density) fuel than those which contained low-density (77-91 percent theoretical density) fuel was attributed to the limited ability of the high-density fuel to swell into the void space provided in the fuel element. Increasing cladding thickness and original fuel-cladding gap size were both found to influence the failure rates for elements containing low-density fuel. Lower cladding strain and higher fission-gas release were found in high-burnup fuel elements having smear densities of less than 81 percent. Fission-gas release was usually less than 5 percent for high-density fuel, but increased with burnup to a maximum of 37 percent in low-density fuel. Maximum carburization in elements attaining 5-10 at. percent burnup and clad in Types 304 or 316 stainless steel and Incoloy 800 ranged from 36-80 μm and 38-52 μm, respectively. Strontium and barium were the fission products most frequently found in contact with the cladding but no penetration of the cladding by uranium, plutonium, or fission products was observed

  8. Luminescent pincer platinum(II) complexes with emission quantum yields up to almost unity: photophysics, photoreductive C-C bond formation, and materials applications.

    Science.gov (United States)

    Chow, Pui-Keong; Cheng, Gang; Tong, Glenna So Ming; To, Wai-Pong; Kwong, Wai-Lun; Low, Kam-Hung; Kwok, Chi-Chung; Ma, Chensheng; Che, Chi-Ming

    2015-02-09

    Luminescent pincer-type Pt(II)  complexes supported by C-deprotonated π-extended tridentate RC^N^NR' ligands and pentafluorophenylacetylide ligands show emission quantum yields up to almost unity. Femtosecond time-resolved fluorescence measurements and time-dependent DFT calculations together reveal the dependence of excited-state structural distortions of [Pt(RC^N^NR')(CC-C6 F5 )] on the positional isomers of the tridentate ligand. Pt complexes [Pt(R-C^N^NR')(CC-Ar)] are efficient photocatalysts for visible-light-induced reductive CC bond formation. The [Pt(R-C^N^NR')(CC-C6 F5 )] complexes perform strongly as phosphorescent dopants for green- and red-emitting organic light-emitting diodes (OLEDs) with external quantum efficiency values over 22.1 %. These complexes are also applied in two-photon cellular imaging when incorporated into mesoporous silica nanoparticles (MSNs). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Flow electrochemical biosensors based on enzymatic porous reactor and tubular detector of silver solid amalgam

    Energy Technology Data Exchange (ETDEWEB)

    Josypčuk, Bohdan, E-mail: josypcuk@jh-inst.cas.cz [J. Heyrovský Institute of Physical Chemistry of AS CR, v.v.i., Department of Biophysical Chemistry, Dolejskova 3, Prague (Czech Republic); Barek, Jiří [Charles University in Prague, Faculty of Science, University Center of Excellence UNCE “Supramolecular Chemistry”, Department of Analytical Chemistry, UNESCO Laboratory of Environmental Electrochemistry, Albertov 6, CZ-128 43 Prague 2 (Czech Republic); Josypčuk, Oksana [J. Heyrovský Institute of Physical Chemistry of AS CR, v.v.i., Department of Biophysical Chemistry, Dolejskova 3, Prague (Czech Republic); Charles University in Prague, Faculty of Science, University Center of Excellence UNCE “Supramolecular Chemistry”, Department of Analytical Chemistry, UNESCO Laboratory of Environmental Electrochemistry, Albertov 6, CZ-128 43 Prague 2 (Czech Republic)

    2013-05-17

    Graphical abstract: -- Highlights: •Flow amperometric enzymatic biosensor was constructed. •The biosensor is based on a reactor of a novel material – porous silver solid amalgam. •Tubular amalgam detector was used for determination of decrease of O{sub 2} concentration. •Covalent bonds amalgam−thiol−enzyme contributed to the sensor long-term stability. •LOD of glucose was 0.01 mmol L{sup −1} with RSD = 1.3% (n = 11). -- Abstract: A flow amperometric enzymatic biosensor for the determination of glucose was constructed. The biosensor consists of a flow reactor based on porous silver solid amalgam (AgSA) and a flow tubular detector based on compact AgSA. The preparation of the sensor and the determination of glucose occurred in three steps. First, a self-assembled monolayer of 11-mercaptoundecanoic acid (MUA) was formed at the porous surface of the reactor. Second, enzyme glucose oxidase (GOx) was covalently immobilized at MUA-layer using N-ethyl-N′-(3-dimethylaminopropyl) carboimide and N-hydroxysuccinimide chemistry. Finally, a decrease of oxygen concentration (directly proportional to the concentration of glucose) during enzymatic reaction was amperometrically measured on the tubular detector under flow injection conditions. The following parameters of glucose determination were optimized with respect to amperometric response: composition of the mobile phase, its concentration, the potential of detection and the flow rate. The calibration curve of glucose was linear in the concentration range of 0.02–0.80 mmol L{sup −1} with detection limit of 0.01 mmol L{sup −1}. The content of glucose in the sample of honey was determined as 35.5 ± 1.0 mass % (number of the repeated measurements n = 7; standard deviation SD = 1.2%; relative standard deviation RSD = 3.2%) which corresponds well with the declared values. The tested biosensor proved good long-term stability (77% of the current response of glucose was retained after 35 days)

  10. Randomized clinical comparison of endodontically treated teeth restored with amalgam or with fiber posts and resin composite: five-year results.

    Science.gov (United States)

    Mannocci, Francesco; Qualtrough, Alison J E; Worthington, Helen V; Watson, Timothy F; Pitt Ford, Thomas R

    2005-01-01

    Prospective clinical studies comparing the results of different types of restorations of endodontically treated teeth are lacking. This study compared the clinical success rate of endodontically treated premolars restored with fiber posts and direct composite to the restorations of premolars using amalgam. Premolars with Class II carious lesions were selected and randomly assigned to one of two experimental groups: (1) restoration with amalgam or (2) restoration with fiber posts and composite. One hundred and nine teeth were included in Group 1 and 110 in Group 2. Patients were recalled after 1, 3 and 5 years. No statistically significant difference was found between the proportion of failed teeth in the two experimental groups. Significant differences were observed between the proportion of root fractures (p=0.029) and caries (p=0.047), with more root fractures and less caries observed in the teeth restored with amalgam at the five-year recall. Within the limits of this study, it can be concluded that restorations with fiber posts and composite were found to be more effective than amalgam in preventing root fractures but less effective in preventing secondary caries.

  11. Mercury vapour exposure during dental student training in amalgam removal.

    Science.gov (United States)

    Warwick, Robin; O'Connor, Andrea; Lamey, Brianne

    2013-10-03

    Amalgam that is used for dental fillings contains approximately 50% elemental mercury. During dental student training, amalgam is often removed by drilling without the use of water spray and suction, which are protective measures in preventing mercury aerosol. In this study we measured mercury vapor levels in ambient air during amalgam removal as is typically performed in dental training. Mercury vapor levels in ambient air were measured in a dental school laboratory during removal of amalgam fillings from artificial teeth set into a dental jaw simulator. Mercury vapor was measured under three conditions (25 measurements each): with the simultaneous use of water spray and suction, with the use of suction only, and with the use of neither suction nor water spray. These three conditions are all used during dental student training. Results were compared to Alberta occupational exposure limits for mercury vapor in order to assess potential occupational risk to students. Analysis of variance testing was used to compare data obtained under the three conditions. When water spray and suction were used, mercury vapor levels ranged from 4.0 to 19.0 μg/m3 (arithmetic mean = 8.0 μg/m3); when suction only was used, mercury vapor levels ranged from 14.0 to 999.0 (999.0 μg/m3 represents the high limit detection of the Jerome analyzer) (arithmetic mean = 141.0 μg/m3); when neither suction nor water was used, the vapor levels ranged from 34.0 to 796.0 μg/m3 (arithmetic mean = 214.0 μg/m3). The Alberta Occupational Health and Safety threshold limit value for mercury vapor over an eight-hour time-weighted period is 25.0 μg/m3. The absolute ceiling for mercury vapor, not to be exceeded at any time, is 125.0 μg/m3. When both water spray and suction were used, mercury vapor levels were consistently below this threshold. When suction without water spray was used, mercury vapor levels exceeded the safety threshold 8% of the time. When neither water spray nor

  12. Long term changes in health complaints after removal of amalgam restorations.

    Science.gov (United States)

    Björkman, Lars; Sjursen, Therese T; Dalen, Knut; Lygre, Gunvor B; Berge, Trine Lise L; Svahn, Johanna; Lundekvam, Birgitte F

    2017-04-01

    Concerns over adverse effects of mercury released from dental amalgam sometimes lead patients to request removal of their amalgam restorations. Several studies report improvement of subjective health after removal of amalgam restorations, but the mechanisms are unclear. The aim of this paper is to present data on long term changes in intensity of health complaints after amalgam removal in a group of patients with health complaints self-attributed to dental amalgam. Data from the five years follow-up in a clinical trial are presented and related to potential determinants of change. Patients previously referred to a specialty unit for health complaints attributed to amalgam restorations were included in the study. The 20 participants who were allocated to the treatment group had all amalgam restorations removed and replaced with other dental restorative materials. Intensity of health complaints was calculated from questionnaire data and personality variables were measured by MMPI-2. At the follow-up five years after the amalgam removal was completed, intensity of general health complaints was significantly reduced (p=.001), but the symptom load was still high. The reduction was significantly correlated with concentration of mercury in urine at pre-treatment. There were no significant correlations with personality variables. Removal of amalgam restorations was followed by a long term reduction of general health complaints, which was associated with mercury concentration in urine before amalgam removal. Additional studies are needed to confirm the potential mechanisms for the observed reduction.

  13. Repairing ditched amalgam restorations is less time and tooth structure-consuming than replacement.

    Science.gov (United States)

    Lenzi, T L; Marquezan, M; Bonini, G C; Camargo, L B; Raggio, D P

    2013-10-01

    To evaluate the dental structure loss associated with procedures of replacement or maintenance for ditched amalgam restorations in primary molars and the time required to perform each treatment. Ditched amalgam restorations (n = 40) were submitted to four different strategies: polishing group-polishing and finishing of restorations; amalgam group-replacement of ditched amalgam restorations with new amalgam restorations; resin group-replacement of amalgam restorations with resin composite restorations; flowable resin group-filling the ditch with a flowable resin composite. The teeth were analysed with a stereomicroscope and the areas pre- and post-treatment were determined by image analysis software to evaluate structural loss. The time required to perform each treatment was recorded in seconds. Student's t test was used to compare areas pre- and post-treatments. ANOVA and Student-Newman-Keuls tests (p amalgam groups. Replacing the restorations with amalgam took more time, while polishing and applying flowable resin composite consumed less than half of the time compared with amalgam and resin groups. Maintenance of ditched amalgam restorations by polishing and sealing preserves dental structure and involves less time compared with that for replacement of restorations.

  14. Investigation of adding fluoroapatite nanoparticles on compressive strength and corrosion behaviour of dental amalgams

    Directory of Open Access Journals (Sweden)

    Fahimeh Mirlohi

    2012-12-01

    Full Text Available In recent years, there have been many efforts to improve biological and biocompatibility features of amalgam. The aim of this research was investigating the effect of adding fluoroapatite (FA nanoparticles on compressive strength and corrosion behaviour of dental amalgam. An amalgam alloy powder was mixed with 1, 3 and 5 wt.% of FA nanoparticles to form composite powders. Compressive strength of the corresponding dental amalgam samples was measured on the first and seventh day after preparation and the corrosion behaviour was investigated by potentiodynamic polarization electrochemical test in 0.9 wt.% salt solution (physiologic serum. The results showed that the amalgam containing 1 wt.% FA nanoparticles has higher compressive strength then the pure amalgam and with increasing the FA content in amalgam to 3 and 5 wt.%, the compressive strength decreases. The results also indicated that the corrosion behaviour of the amalgam sample with 1 wt.% FA is similar to the corrosion behaviour of the original amalgam, while with increasing the weight percentage of fluorapatite, the corrosion resistance decreases. The results of this research showed that adding FA nanoparticles in amounts of up to 1 wt.% to amalgam alloy improve compressive strength, has no destructive effect on corrosion behaviour of the material and can increase its biocompatibility and biological activity.

  15. Clinicopathological and immunohistochemical study of oral amalgam pigmentation.

    Science.gov (United States)

    Vera-Sirera, Beatriz; Risueño-Mata, Presentación; Ricart-Vayá, José M; Baquero Ruíz de la Hermosa, Carmen; Vera-Sempere, Francisco

    2012-01-01

    Amalgam tattoo, the most common exogenous oral pigmentation, can sometimes be confused with melanotic lesions, being then biopsied. We present the clinicopathological characteristics of 6 biopsied cases (5 females and 1 male) of oral amalgam pigmentation. The most common location was the gingival mucosa, followed by the buccal and palatal mucosa. Morphology and distribution (stromal, perivascular, perineural, endomysial) of pigmentation was variable; there was only 1 case with fibrous capsular reaction and likewise only a single case of granulomatous foreign body reaction. Morphological variability is conditioned by the timing and amount of the pigment deposit, which is often associated with infiltration by mast cells (CD117+), as well as overexpression of metallothionein and HLA-DR at different tissue levels. Copyright © 2011 Elsevier España, S.L. All rights reserved.

  16. Clinical management of galvanic current between gold and amalgam.

    Science.gov (United States)

    Williamson, R

    1996-01-01

    Placing a strip of rubber dam or similar insulator between the contacting dissimilar restorations is a diagnostic technique for relieving and evaluating painful galvanic currents. Treatment modalities vary according to severity of pain. In cases of little or no pain, nothing is done, and corrosion products are allowed to form an insulating cover over the offending restoration. For patients with severe pain that does not improve, treatment may consist of placing a composite restoration in the amalgam restoration to break the interproximal dissimilar-metal contact. For painful currents caused by occluding restorations, a coating of unfilled light-cured resin over the offending amalgam breaks the metal contact and allows corrosion product buildup. Galvanic currents can occur and cause pain, but this is generally shortlived and should not influence the dentist's choice of an appropriate restorative material.

  17. Amalgamation of performance indicators to support NRC senior management reviews

    International Nuclear Information System (INIS)

    Wreathall, J.; Schurman, D.; Modarres, M.; Mosleh, A.; Anderson, N.; Reason, J.

    1991-01-01

    The purpose of this project is to develop a methodology for amalgamating performance indicators to provide an overall perspective on plant safety, as one input to Nuclear Regulatory Commission's (NRC) senior management reviews of plant safety. These reviews are used to adjust the level of oversight by NRC. Work completed to date includes the development of frameworks for relating indicator measures to safety, a classification scheme for performance indicators, and a mapping process to portray indicators in the frameworks

  18. Monte carlo dose calculation in dental amalgam phantom

    OpenAIRE

    Mohd Zahri Abdul Aziz; A L Yusoff; N D Osman; R Abdullah; N A Rabaie; M S Salikin

    2015-01-01

    It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC). On the other hand, computed tomography (CT) images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatm...

  19. In vivo intraoral reflectance confocal microscopy of an amalgam tattoo

    OpenAIRE

    Yélamos, Oriol; Cordova, Miguel; Peterson, Gary; Pulitzer, Melissa P.; Singh, Bhuvanesh; Rajadhyaksha, Milind; DeFazio, Jennifer L.

    2017-01-01

    The majority of oral pigmentations are benign lesions such as nevi, melanotic macules, melanoacanthomas or amalgam tattoos. Conversely, mucosal melanomas are rare but often lethal; therefore, excluding oral melanomas in this setting is crucial. Reflectance confocal microscopy is a non-invasive, in vivo imaging system with cellular resolution that has been used to distinguish benign from malignant pigmented lesions in the skin, and more recently in the mucosa. However, lesions located posterio...

  20. Dental composites and amalgam and physical development in children.

    Science.gov (United States)

    Maserejian, N N; Hauser, R; Tavares, M; Trachtenberg, F L; Shrader, P; McKinlay, S

    2012-11-01

    Resin-based composite dental restoration materials may release bisphenol-A, an endocrine-disrupting chemical. Using secondary analysis of a randomized clinical safety trial of amalgam vs. composites, we tested the hypothesis that dental restoration materials affect children's growth. Children (N = 218 boys, N = 256 girls) aged 6 to 10 yrs at baseline with ≥ 2 decayed posterior teeth were randomized to amalgam or composites (bisphenol-A-diglycidyl-dimethacrylate composite for permanent teeth, urethane-dimethacrylate compomer for primary teeth) for treatment of posterior caries throughout follow-up. Primary outcomes for this analysis were 5-year changes in BMI-for-age z-scores, body fat percentage (BF%), and height velocity; exploratory analyses (n = 113) examined age at menarche. Results showed no significant differences between treatment assignment and changes in physical development in boys [(composites vs. amalgam) BF%, 4.9 vs. 5.7, p = 0.49; (BMI-z-score) 0.13 vs. 0.25, p = 0.36] or girls (8.8 vs. 7.7, p = 0.95; 0.36 vs. 0.21, p = 0.49). Children with more treatment on primary teeth had greater increases in BF% regardless of material type. Girls assigned to composites had lower risk of menarche during follow-up (hazard ratio = 0.57, 95% CI 0.35-0.95). Overall, there were no significant differences in physical development over 5 years in children treated with composites or amalgam. Additional studies examining these restoration materials in relation to age at menarche are warranted (clinicaltrials.gov number NCT00065988).

  1. A model for amalgamation in group decision making

    Science.gov (United States)

    Cutello, Vincenzo; Montero, Javier

    1992-01-01

    In this paper we present a generalization of the model proposed by Montero, by allowing non-complete fuzzy binary relations for individuals. A degree of unsatisfaction can be defined in this case, suggesting that any democratic aggregation rule should take into account not only ethical conditions or some degree of rationality in the amalgamating procedure, but also a minimum support for the set of alternatives subject to the group analysis.

  2. Voltammetric Determination of Nitrophenols at a Silver Solid Amalgam Electrode

    Czech Academy of Sciences Publication Activity Database

    Fischer, J.; Vaňourková, L.; Daňhel, A.; Vyskočil, V.; Čížek, K.; Barek, J.; Pecková, K.; Josypčuk, Bohdan; Navrátil, Tomáš

    2007-01-01

    Roč. 2, - (2007), s. 226-134 ISSN 1452-3981 R&D Projects: GA MŠk(CZ) LC06063; GA ČR GA203/07/1195; GA MPO 1H-PK/42 Institutional research plan: CEZ:AV0Z40400503 Keywords : solid amalgam electrodes * voltammetry * nitrophenols * growth stimulators * solid phase extraction (SPE) Subject RIV: CF - Physical ; Theoretical Chemistry

  3. Voltammetric Determination of Nitronaphthalenes at a Silver Solid Amalgam Electrode

    Czech Academy of Sciences Publication Activity Database

    Pecková, K.; Barek, J.; Navrátil, Tomáš; Josypčuk, Bohdan; Zima, J.

    2009-01-01

    Roč. 42, č. 15 (2009), s. 2339-2363 ISSN 0003-2719 R&D Projects: GA ČR GA203/07/1195; GA AV ČR IAA400400806; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40400503 Keywords : cyclic voltammetry * differential pulse voltammetry * elimination voltammetry with linear scan * silver amalgam electrode Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.317, year: 2009

  4. Silver Solid Amalgam Electrodes as Sensors for Chemical Carcinogens

    Czech Academy of Sciences Publication Activity Database

    Barek, J.; Fischer, J.; Navrátil, Tomáš; Pecková, K.; Josypčuk, Bohdan

    2006-01-01

    Roč. 6, č. 4 (2006), s. 445-452 ISSN 1424-8220 R&D Projects: GA MPO 1H-PK/42; GA ČR GA203/03/0182 Institutional research plan: CEZ:AV0Z40400503 Keywords : solid amalgam electrodes * voltammetry * carcirogens * 3-nitrofluoranthene * Ostazine Orange Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.373, year: 2006

  5. Voltammetric Determination of Azidothymidine Using Silver Solid Amalgam Electrodes

    Czech Academy of Sciences Publication Activity Database

    Pecková, K.; Navrátil, Tomáš; Josypčuk, Bohdan; Moreira, J. C.; Leandro, K. Ch.; Barek, J.

    2009-01-01

    Roč. 21, č. 15 (2009), s. 1750-1757 ISSN 1040-0397 R&D Projects: GA ČR GA203/07/1195; GA AV ČR IAA400400806; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40400503 Keywords : azidothymidine * Zidovudine * Silver solid amalgam electrode * Differential pulse voltammetry Subject RIV: CG - Electrochemistry Impact factor: 2.630, year: 2009

  6. Radiopaque zones in the dentin beneath amalgam restorations

    International Nuclear Information System (INIS)

    You, Young Jun; Ahn, Hyung Kyu

    1978-01-01

    The purpose of the present investigation is determine how frequently radiopaque zones are seen on standard intraoral film and to research some other things about radiopaque bones. This study obtained the following results: 1. According to the standard intraoral films of the charts that were kept at the Dept. of Oral Diagnosis in Seoul National University Hospital, radiopaque zones were found in the rate of 4.1% among 1150 cases of amalgam-restored teeth that were treated at least two years ago. 2. Out of teeth that possessed radiopaque zones, 38.3% had radiolucent area between amalgam restoration and radiopaque zone. 3. Out of teeth that possessed radiopaque zones, 36.2% had cement base between amalgam restoration and radiopaque zone. 4. Out of teeth that possessed radiopaque zones, no tooth had periapical radiolucency. 5. Radiopaque zones were found more frequently in the mandibular teeth than the maxillary teeth. 6. According to the result of direct x-ray taking of 50 teeth that were treated at least 2 years ago, 6% had radiopaque zone.

  7. Amalgam or composite fillings--which material lasts longer?

    Science.gov (United States)

    Hurst, Dominic

    2014-06-01

    Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase and LILACS. Hand searched relevant journals and attempted contact with authors of unpublished studies and manufacturers. Randomised controlled trials comparing dental resin composites with dental amalgams in permanent posterior teeth with a minimum follow up of three years were eligible. Data were extracted independently by a minimum of two review authors using specially designed data extraction forms. Risk of bias was assessed using the Cochrane risk of bias tool. Relative risks and 95% CIs were extracted for dichotomous data and mean difference (MD) or standardised mean difference (SMD) for continuous data. Relative risk was combined in a meta-analysis. Seven studies were included. Two were parallel and five split-mouth design. Data from 871 participants were available from the two parallel studies but several of the split-mouth studies did not report the number of participants. All studies were considered at high risk of bias. Only data from the two parallel studies were included in the primary meta-analysis. Failure rates in these studies were recorded for between five and seven years. The risk ratio of failure for composite versus amalgam was 1.89 with 95% CI of 1.52-2.35. The increased failure was primarily due to caries rather than fracture. There is low-quality evidence to suggest that resin composites lead to higher failure rates and risk of secondary caries than amalgam restorations.

  8. Oral mucosal lesions related to silver amalgam restorations.

    Science.gov (United States)

    Bolewska, J; Hansen, H J; Holmstrup, P; Pindborg, J J; Stangerup, M

    1990-07-01

    A total of 49 consecutive patients with lesions of the oral mucosa that were in contact with corroding dental amalgam restorations were subdivided into two groups. In group 1 the lesions were restricted to the contact area opposing the dental restoration, whereas the extent of the lesions in group 2 exceeded that of the contact area. Epicutaneous test for mercury allergy showed that a significantly greater proportion of the patients in group 1 had positive reactions to mercury than in group 2 (p = 0.019). The amalgam restorations were replaced by composite resin or porcelain fused to gold crowns, or contact between amalgam fillings and oral mucosa was prevented by an acrylic splint. After this treatment regression of lesions was far more pronounced in group 1 than in group 2 (p less than 0.001). On the basis of these findings, contact allergy to mercury is suggested as a possible etiologic factor of the mucosal changes in group 1, and the designation contact lesion is proposed for such lesions. The lesions of patients in group 2 seem unrelated to a contact allergy to mercury, and other causes such as lichen planus should be considered.

  9. Evaiuation of Cracks Propagation in Retroflllings with Cinalloy Amalgam

    Directory of Open Access Journals (Sweden)

    Zarrabian M

    2000-06-01

    Full Text Available One of the major goals of preradicular surgery is to create a good apical seal. This can be done by sectioning approximately one third of the apex, preparation of a class I cavity, and filling with a biocompatible material. The purpose of this in vitro study was to compare crack propagation in retro filling with two commercially available amalgams. Thirty-four extracted single rooted teeth were divided into two groups. After instrumentation and filling with Gutta percha by lateral condensation method, three millimeter of apex was resected and retro preparations were done by a low speed hand piece and '/> round bur. Then cavities were filled with cinalloy and luxalloy amalgam in-group "one" and "two" respectively. The surface of resected root ends was examined in two stages, after doing retro preparation and retro filling and the presence of any cracks or structural changes was inspected by stereomicroscope 50x. Regard to number and type of cracks, the result of this study showed that there was no significant difference between cinalloy or luxalloy retro fillings. By considering the conditions of this study, cinalloy amalgam can be used as a retro filling material.

  10. The Impact of Amalgamations on Services in Icelandic Municipalities

    Directory of Open Access Journals (Sweden)

    Grétar Thór Eythórsson

    2018-03-01

    Full Text Available This article deals with answering the question whether municipal amalgamations can meet the wishes at the root of the most common motives behind them: to gain cost-efficiency and more quality in the municipal services. The analysis is partly based on a survey among Icelandic local leaders in 2015 and partly on survey among citizens in 8 recently amalgamated municipalities collected with a snowball method through Facebook in the spring and summer 2013. The main results are that the impact of amalgamations on municipal services seems to depend on whether we look at the central or peripheral parts of the municipality. Both leaders and citizens seem to perceive developments of services differently depending on the position in the municipality. In the peripheries, they have significantly more negative view than in the service centres. This has to do with both their evaluation of specific services and their general evaluation of service development. However, in the general evaluation the difference is significantly larger.

  11. Structure and strength of low-mercury dental amalgams prepared with liquid Hg-47.4% In alloy.

    Science.gov (United States)

    Friedman, A; Kaufman, A

    1998-06-01

    Two low-mercury amalgams: (1) low-copper lathe-cut and (2) high-copper (Tytin) were prepared by amalgamation with liquid Hg-47.4% In alloy. The strength-structure relationship of these amalgams was investigated and compared with standard amalgams (i.e. amalgams prepared with the same powders and pure mercury). The matrix phase of the low-mercury amalgam was found to be depleted of mercury and may be thought of as In4Ag9 compound with some mercury dissolved, indicating that less mercury (compared with standard amalgam) combines with silver, thus producing a strong amalgam matrix. On the other hand, an increase was observed in the consumption of the initial gamma (Ag3Sn)-phase, leading to an increase of the tin released. As a result, the potential of [HgSn]-phase formation in low-mercury amalgams increases. The observed increase in the quantity of gamma2(Sn7-8Hg)-phase in low-copper amalgam, or its appearance in high-copper amalgam (where it is normally absent), contributes to a deterioration in the strength of the investigated amalgam. The conclusion drawn was that low-mercury amalgam may be prepared with liquid Hg-47.4%In alloy but, in order to eliminate gamma2-phase formation, novel and possibly tin-free amalgamable alloys should be developed. Copyright 1998 Chapman & Hall

  12. Estimated quantity of mercury in amalgam waste water residue released by dentists into the sewerage system in Ontario, Canada.

    Science.gov (United States)

    Adegbembo, Albert O; Watson, Philip A

    2004-12-01

    To estimate the quantity of dental amalgam that Ontario dentists release into waste water. Information from a self-administered postal survey of Ontario dentists was combined with the results of other experiments on the weight of amalgam restorations and the quantity of amalgam waste that bypasses solids separators in dental offices. Algorithms were developed to compute the quantity of amalgam waste leaving dental offices when dentists used or did not use ISO 11143 amalgam particle separators. A total of 878 (44.0%) of 1,994 sampled dentists responded to the survey. It was estimated that Ontario dentists removed 1,880.32 kg of amalgam (940.16 kg of mercury) during 2002, of which 1,128.19 kg of amalgam (564.10 kg of mercury) would have been released into waste water in Ontario if no dentists had been using a separator. Approximately 22% of the dentists reported using amalgam particle separators. On the basis of current use of amalgam separators, it was estimated that 861.78 kg of amalgam (430.89 kg of mercury or 170.72 mg per dentist daily) was released in 2002. The use of amalgam separators by all dentists could reduce the quantity of amalgam (and mercury) entering waste water to an estimated 12.41 kg (6.21 kg of mercury, or 2.46 mg per dentist per day). Amalgam particles separators can dramatically reduce amalgam and mercury loading in waste water released from dental offices.

  13. Patients’ experiences of changes in health complaints before, during, and after removal of dental amalgam

    Directory of Open Access Journals (Sweden)

    Therese T. Sjursen

    2015-06-01

    Full Text Available In this article, we explore how patients with health complaints attributed to dental amalgam experienced and gave meaning to changes in health complaints before, during, and after removal of all amalgam fillings. We conducted semistructured qualitative interviews with 12 participants from the treatment group in a Norwegian amalgam removal trial. Interviews took place within a couple months of the final follow-up 5 years after amalgam removal. Using the NVivo9 software, we conducted an explorative and reflective thematic analysis and identified the following themes: Something is not working: betrayed by the body, You are out there on your own, Not being sure of the importance of amalgam removal, The relief experienced after amalgam removal, and To accept, to give up, or to continue the search. We discuss the findings in the context of patients’ assigning meaning to illness experiences.

  14. Patients’ experiences of changes in health complaints before, during, and after removal of dental amalgam

    Science.gov (United States)

    Sjursen, Therese T.; Binder, Per-Einar; Lygre, Gunvor B.; Helland, Vigdis; Dalen, Knut; Björkman, Lars

    2015-01-01

    In this article, we explore how patients with health complaints attributed to dental amalgam experienced and gave meaning to changes in health complaints before, during, and after removal of all amalgam fillings. We conducted semistructured qualitative interviews with 12 participants from the treatment group in a Norwegian amalgam removal trial. Interviews took place within a couple months of the final follow-up 5 years after amalgam removal. Using the NVivo9 software, we conducted an explorative and reflective thematic analysis and identified the following themes: Something is not working: betrayed by the body, You are out there on your own, Not being sure of the importance of amalgam removal, The relief experienced after amalgam removal, and To accept, to give up, or to continue the search. We discuss the findings in the context of patients’ assigning meaning to illness experiences. PMID:26112454

  15. Patients' experiences of changes in health complaints before, during, and after removal of dental amalgam.

    Science.gov (United States)

    Sjursen, Therese T; Binder, Per-Einar; Lygre, Gunvor B; Helland, Vigdis; Dalen, Knut; Björkman, Lars

    2015-01-01

    In this article, we explore how patients with health complaints attributed to dental amalgam experienced and gave meaning to changes in health complaints before, during, and after removal of all amalgam fillings. We conducted semistructured qualitative interviews with 12 participants from the treatment group in a Norwegian amalgam removal trial. Interviews took place within a couple months of the final follow-up 5 years after amalgam removal. Using the NVivo9 software, we conducted an explorative and reflective thematic analysis and identified the following themes: Something is not working: betrayed by the body, You are out there on your own, Not being sure of the importance of amalgam removal, The relief experienced after amalgam removal, and To accept, to give up, or to continue the search. We discuss the findings in the context of patients' assigning meaning to illness experiences.

  16. Oral lichenoid contact lesions to mercury and dental amalgam--a review.

    Science.gov (United States)

    McParland, Helen; Warnakulasuriya, Saman

    2012-01-01

    Human oral mucosa is subjected to many noxious stimuli. One of these substances, in those who have restorations, is dental amalgam which contains mercury. This paper focuses on the local toxic effects of amalgam and mercury from dental restorations. Components of amalgam may, in rare instances, cause local side effects or allergic reactions referred to as oral lichenoid lesions (OLLs). OLLs to amalgams are recognised as hypersensitivity reactions to low-level mercury exposure. The use of patch testing to identify those susceptible from OLL is explored, and recommendations for removing amalgam fillings, when indicated are outlined. We conclude that evidence does not show that exposure to mercury from amalgam restorations poses a serious health risk in humans, except for an exceedingly small number of hypersensitivity reactions that are discussed.

  17. 1D and 2D assembly structures by imidazole···chloride hydrogen bonds of iron(II) complexes [Fe(II)(HL(n-Pr))3]Cl·Y (HL(n-Pr) = 2-methylimidazol-4-yl-methylideneamino-n-propyl; Y = AsF6, BF4) and their spin states.

    Science.gov (United States)

    Fujinami, Takeshi; Nishi, Koshiro; Matsumoto, Naohide; Iijima, Seiichiro; Halcrow, Malcolm A; Sunatsuki, Yukinari; Kojima, Masaaki

    2011-12-07

    Two Fe(II) complexes fac-[Fe(II)(HL(n-Pr))(3)]Cl·Y (Y = AsF(6) (1) and BF(4) (2)) were synthesized, where HL(n-Pr) is 2-methylimidazole-4-yl-methylideneamino-n-propyl. Each complex-cation has the same octahedral N(6) geometry coordinated by three bidentate ligands and assumes facial-isomerism, fac-[Fe(II)(HL(n-Pr))(3)](2+) with Δ- and Λ-enantiomorphs. Three imidazole groups per Δ- or Λ-fac-[Fe(II)(HL(n-Pr))(3)](2+) are hydrogen-bonded to three Cl(-) ions or, from the viewpoint of the Cl(-) ion, one Cl(-) ion is hydrogen-bonded to three neighbouring fac-[Fe(II)(HL(n-Pr))(3)](2+) cations. The 3 : 3 NH···Cl(-) hydrogen bonds between Δ- or Λ-fac-[Fe(II)(HL(n-Pr))(3)](2+) and Cl(-) generate two kinds of assembly structures. The directions of the 3 : 3 NH···Cl(-) hydrogen bonds and hence the resulting assembly structures are determined by the size of the anion Y, though Y is not involved into the network structure and just accommodated in the cavity. Compound 1 has a 1D ladder structure giving a larger cavity, in which the Δ- and Λ-fac-[Fe(II)(HL(n-Pr))(3)](2+) enantiomorphs are bridged by two NH···Cl(-) hydrogen bonds. Compound 2 has a 2D network structure with a net unit of a cyclic trimer of {fac-[Fe(II)(HL(n-Pr))(3)](2+)···Cl(-)}(3) giving a smaller cavity, in which Δ- or Λ-fac-[Fe(II)(HL(n-Pr))(3)](2+) species with the same chirality are linked by NH···Cl(-) hydrogen bonds to give a homochiral 2D network structure. Magnetic susceptibility and Mössbauer spectral measurements demonstrated that compound 1 showed an abrupt one-step spin crossover with 4.0 K thermal hysteresis of T(c↓) = 125.5 K and T(c↑) = 129.5 K and compound 2 showed no spin transition and stayed in the high-spin state over the 5-300 K temperature range.

  18. 'n Ondersoek na die amalgamering van skole in die RSA / André Johann Nel

    OpenAIRE

    Nel, André Johann

    1999-01-01

    Rationalisation, because of a lack of governmental funds, has become part of the education system of the RSA. In schools it implies that teaching posts are being reduced and that more emphasis is placed on the optimum use of physical facilities. For many smaller and rural schools, amalgamation became a possible solution to the problem. The amalgamation of schools however, implies a drastic change in the status quo. The main aim of the study is to investigate amalgamation as ...

  19. Attitudes of dentists and interns in Riyadh to the use of dental amalgam

    OpenAIRE

    Alkhudhairy, Fahad

    2016-01-01

    Background Studies investigating the attitudes of Saudi dentists to the use of amalgam for restorations are relatively rare. Considering the goals set forth by the Minamata Convention on Mercury, it appears prudent to investigate the attitudes of experienced dentists and fresh dental graduates to the use of amalgam. The aim of this study was to assess the attitudes of Saudi dentists and interns working in Riyadh, Saudi Arabia to the use of amalgam. Using a convenience sampling methodology, a ...

  20. ASSESSMENT OF MERCURY RELEASE FROM DENTAL AMALGAM: AN IN VITRO STUDY

    OpenAIRE

    Shetty Aditya; Hegde Mithra N.; Mathew Tony; Bhat Ganesh

    2013-01-01

    Exposure to mercury from dental amalgam restoration, with possible negative health effects, has generally been considered to occur via either erosion or evaporation directly from the surface of fillings, followed by ingestion. This study aims to assess the mercury release from dental amalgam and provide a basis for comparison between mercury release in oral cavities with single and multiple amalgam restorations at different time intervals. This study was conducted in A.B. Shetty Memorial Inst...

  1. Comparison of the abrasive wear resistance between amalgams, hybrid composite material and different dental cements.

    Science.gov (United States)

    Gil, F J; Espias, A; Sánchez, L A; Planell, J A

    1999-12-01

    This paper reports on the abrasion wear of various restorative dental materials (three amalgams and two dental cements and a hybrid composite material) commonly used in dentistry. The mechanical properties, surface roughness and the volume loss by abrasion were determined for the different materials studied. The results showed a better profile for the amalgams versus the composite materials due to the failure of the polymeric matrix of the latter materials. However, the amalgams exhibited corrosion observed by means of Scanning Electron Microscopy.

  2. Comparative Evaluation of the Initial Corrosion of Four Brands of High Copper Dental Amalgams

    Directory of Open Access Journals (Sweden)

    V. Mortazavi

    2004-09-01

    Full Text Available Statement of Problem: Many attempts have been made in order to evaluate the amalgam corrosion behavior as an indicator of biocompatibility. Purpose: The aim of this study was to evaluate and compare the initial corrosion of four different brands of dental amalgams. Materials and Methods: Four different types of commercial high copper dental amalgam were studied. A special mold was used and twenty-one samples of each type of commercial dental amalgams were prepared. X-ray diffraction technique was used to investigate the microstructure of freshly prepared specimens. Electrochemical potentiodynamic tests were performed in physiological solutions in order to determine and compare the corrosion behavior of freshly prepared sample of four brands of dental amalgams. The physiological solutions were the Ringer’s solution and physiological normal saline. Five replicate tests on each group of specimens were performed. Tafel extrapolation and linear polarization methods determined corrosion potentials and corrosion current densities. The mean value and standard deviations of the results were calculated. The mean values were statistically compared by ANOVA and Duncan methods at 95% level of confidence. Results: Gamma-2 phase was present in freshly prepared sample of each type of commercial amalgam. The results showed statistically significant differences between the mean corrosion current density values of freshly prepared sample of four brands of amalgams (P<0.05. The freshly prepared specimen of Sybraloy dental amalgam possesses the higher initial corrosion resistance than the other three, and Cinaalloy dental amalgam possesses the lowest corrosion resistance. This trend is independent to the type of physiological environment. Conclusion: Initial corrosion resistance of each type of commercial dental amalgam is much less than its corrosion resistance that could be obtained after one week. From the viewpoint of the corrosion behavior as an indication of

  3. Parental Bonding

    Directory of Open Access Journals (Sweden)

    T. Paul de Cock

    2014-08-01

    Full Text Available Estimating the early parent–child bonding relationship can be valuable in research and practice. Retrospective dimensional measures of parental bonding provide a means for assessing the experience of the early parent–child relationship. However, combinations of dimensional scores may provide information that is not readily captured with a dimensional approach. This study was designed to assess the presence of homogeneous groups in the population with similar profiles on parental bonding dimensions. Using a short version of the Parental Bonding Instrument (PBI, three parental bonding dimensions (care, authoritarianism, and overprotection were used to assess the presence of unobserved groups in the population using latent profile analysis. The class solutions were regressed on 23 covariates (demographics, parental psychopathology, loss events, and childhood contextual factors to assess the validity of the class solution. The results indicated four distinct profiles of parental bonding for fathers as well as mothers. Parental bonding profiles were significantly associated with a broad range of covariates. This person-centered approach to parental bonding has broad utility in future research which takes into account the effect of parent–child bonding, especially with regard to “affectionless control” style parenting.

  4. Evaluation of the dental structure loss produced during maintenance and replacement of occlusal amalgam restorations.

    Science.gov (United States)

    Sardenberg, Fernanda; Bonifácio, Clarissa Calil; Braga, Mariana Minatel; Imparato, José Carlos Pettorossi; Mendes, Fausto Medeiros

    2008-01-01

    The aim of this in vitro study was to evaluate four different approaches to the decision of changing or not defective amalgam restorations in first primary molar teeth concerning the loss of dental structure. Ditched amalgam restorations (n = 11) were submitted to four different treatments, as follows: Control group - polishing and finishing of the restorations were carried out; Amalgam group - the ditched amalgam restorations were replaced by new amalgam restorations; Composite resin group - the initial amalgam restorations were replaced by composite resin restorations; Flowable resin group - the ditching around the amalgam restorations was filled with flowable resin. Images of the sectioned teeth were made and the area of the cavities before and after the procedures was determined by image analysis software to assess structural loss. The data were submitted to ANOVA complemented by the Student Newman Keuls test (p amalgam group showed more substantial dental loss. The other three groups presented no statistically significant difference in dental structure loss after the re-treatments. Thus, replacing ditched amalgam restorations by other similar restorations resulted in a significant dental structure loss while maintaining them or replacing them by resin restorations did not result in significant loss.

  5. Evaluation of the dental structure loss produced during maintenance and replacement of occlusal amalgam restorations

    Directory of Open Access Journals (Sweden)

    Fernanda Sardenberg

    2008-09-01

    Full Text Available The aim of this in vitro study was to evaluate four different approaches to the decision of changing or not defective amalgam restorations in first primary molar teeth concerning the loss of dental structure. Ditched amalgam restorations (n = 11 were submitted to four different treatments, as follows: Control group - polishing and finishing of the restorations were carried out; Amalgam group - the ditched amalgam restorations were replaced by new amalgam restorations; Composite resin group - the initial amalgam restorations were replaced by composite resin restorations; Flowable resin group - the ditching around the amalgam restorations was filled with flowable resin. Images of the sectioned teeth were made and the area of the cavities before and after the procedures was determined by image analysis software to assess structural loss. The data were submitted to ANOVA complemented by the Student Newman Keuls test (p < 0.05. The cavities in all the groups presented significantly greater areas after the procedures. However, the amalgam group showed more substantial dental loss. The other three groups presented no statistically significant difference in dental structure loss after the re-treatments. Thus, replacing ditched amalgam restorations by other similar restorations resulted in a significant dental structure loss while maintaining them or replacing them by resin restorations did not result in significant loss.

  6. Mechanism of improved corrosion resistance of Zn-containing dental amalgams.

    Science.gov (United States)

    Sarkar, N K; Park, J R

    1988-10-01

    The aim of this study was to determine the mechanism of improved corrosion resistance of Zn-containing dental amalgams. Two Zn-containing conventional amalgams, their Zn-free counterparts, and three experimental amalgams (SnHg, ZnHg, and SnZnHg) were evaluated by the potentiodynamic polarization technique in 1% NaCl solution. The main difference between the two types of amalgams was found in their respective breakdown potentials at which passivity was destroyed. The breakdown potential of Zn-containing amalgams was about 200 mV more positive than that of the Zn-free amalgams. The improved stability of the Zn-containing amalgams has been attributed to the formation of a previously reported Zn stannate passive film which, according to the polarization data, is more resistant to the aggressive chloride ion than tin hydroxide that forms on Zn-free amalgams. The formation of Zn stannate was not found to affect the oxygen reduction reaction, the major cathodic reaction involved in the corrosion of dental amalgams.

  7. Prenatal Exposure to Dental Amalgam: Evidence from the Seychelles Child Development Main Cohort

    Science.gov (United States)

    Watson, Gene E.; Lynch, Miranda; Myers, Gary J.; Shamlaye, Conrad F.; Thurston, Sally W.; Zareba, Grazyna; Clarkson, Thomas W.; Davidson, Philip W.

    2011-01-01

    Background Dental amalgams contain approximately 50% metallic mercury and emit small quantities of mercury vapor. Controversy surrounds whether fetal exposure to mercury vapor from maternal dental amalgams has neurodevelopmental consequences. Methods Maternal amalgam status during gestation (prenatal mercury vapor exposure) was determined retrospectively on 587 mother-child pairs enrolled in a prospective longitudinal cohort study of effects of prenatal and recent postnatal methylmercury exposure on neurodevelopment. Covariate-adjusted associations were examined between 6 age-appropriate neurodevelopmental tests administered at 66 months of age and prenatal maternal amalgam status. Models were fit without and with adjustment for prenatal and recent postnatal methylmercury exposure metrics. Results Mean maternal amalgams present during gestation were 5.1 surfaces (range 1-22) in the 42% of mothers with amalgams. No significant adverse associations were found between the number of prenatal amalgam surfaces and any of the 6 outcomes, with or without adjustment for prenatal and postnatal methylmercury exposure. Analyses using our secondary metric, prenatal amalgam occlusal point scores, showed an adverse association in males only on the Letter Word Recognition subtest of the Woodcock-Johnson Tests of Achievement, and several apparently beneficial associations for females only. Conclusions This study provides no support for the hypothesis that prenatal mercury vapor exposure from maternal dental amalgams results in neurobehavioral consequences in the child. These findings need confirmation from a prospective study of co-exposure to methyl mercury and mercury vapor. PMID:22041415

  8. Amalgamation of South Africa’s rural municipalities: is it a good idea?

    Directory of Open Access Journals (Sweden)

    Mkhululi Ncube

    2017-04-01

    Full Text Available The majority of South African municipalities facing the challenges of unemployment, poverty and weak infrastructure are in rural areas. To fulfil their mandate, they depend significantly on financial transfers.  This is something that the government is focused on minimising as evidenced by the recent Department of Cooperative Governance and Traditional Affairs proposal of amalgamating many municipalities to make them self-reliant and functional.  This paper asks the question: ‘will amalgamations of rural municipalities correct for financial viability and functionality’? Using case studies of amalgamated municipalities, the paper observes that amalgamations will not make all rural municipalities self-sufficient and functional.

  9. A significant dose-dependent relationship between mercury exposure from dental amalgams and kidney integrity biomarkers: a further assessment of the Casa Pia children's dental amalgam trial.

    Science.gov (United States)

    Geier, D A; Carmody, T; Kern, J K; King, P G; Geier, M R

    2013-04-01

    Dental amalgams are a commonly used dental restorative material. Amalgams are about 50% mercury (Hg), and Hg is known to significantly accumulate in the kidney. It was hypothesized that because Hg accumulates in the proximal tubules (PTs), glutathione-S-transferases (GST)-α (suggestive of kidney damage at the level of PT) would be expected to be more related to Hg exposure than GST-π (suggestive of kidney damage at the level of the distal tubules). Urinary biomarkers of kidney integrity were examined in children of 8-18 years old, with and without dental amalgam fillings, from a completed clinical trial (parent study). Our study determined whether there was a significant dose-dependent correlation between increasing Hg exposure from dental amalgams and GST-α and GST-π as biomarkers of kidney integrity. Overall, the present study, using a different and more sensitive statistical model than the parent study, revealed a statistically significant dose-dependent correlation between cumulative exposure to Hg from dental amalgams and urinary levels of GST-α, after covariate adjustment; where as, a nonsignificant relationship was observed with urinary levels of GST-π. Furthermore, it was observed that urinary GST-α levels increased by about 10% over the 8-year course of the study among individuals with an average exposure to amalgams among the study subjects from the amalgam group, in comparison with study subjects with no exposure to dental amalgams. The results of our study suggest that dental amalgams contribute to ongoing kidney damage at the level of the PTs in a dose-dependent fashion.

  10. Eight-year randomized clinical evaluation of Class II nanohybrid resin composite restorations bonded with a one-step self-etch or a two-step etch-and-rinse adhesive

    DEFF Research Database (Denmark)

    van Dijken, Jan WV; Pallesen, Ulla

    2015-01-01

    Objectives: The aimof this study is to observe the durability of Class II nanohybrid resin composite restorations, placed with two different adhesive systems, in an 8-year follow-up. Methods: Seventy-eight participants received at random at least two Class II restorations of the ormocer......-based nanohybrid resin composite (Ceram X) bonded with either a one-step self-etch adhesive (Xeno III) or a control two-step etch-and-rinse adhesive (Excite). The 165 restorations were evaluated using slightly modified United States Public Health Services (USPHS) criteria at baseline and then yearly during 8 years...... and no significant difference in overall clinical performance between the two adhesives. Fracture was the main reason for failure. Clinical relevance: The one-step self-etch adhesive showed a good long-term clinical effectiveness in combination with the nanohybrid resin composite in Class II restorations....

  11. Knowledge and practices regarding mercury hygiene and amalgam waste disposal: A survey among general dental practitioners

    Directory of Open Access Journals (Sweden)

    Sarita Bhardwaj

    2017-01-01

    Full Text Available Introduction: Amalgam, the most commonly used restorative material, is composed of nearly 50% mercury and 69% silver. It cannot be disposed along with biomedical waste (BMW because mercury-contaminated waste cannot be incinerated or autoclaved. Objectives: To assess the knowledge and observance of proper mercury hygiene and amalgam waste management among general dental practitioners (GDPs. Materials and Methods: A confidential questionnaire containing 14 questions regarding handling and disposal of amalgam was randomly distributed to 175 GDPs in Chandigarh, Panchkula, and Mohali. A response rate of 78% was obtained, and results were statistically analyzed. Results: Out of total dentists surveyed, 71% were found to be using amalgam as restorative material, 63% were doing <5 amalgam restorations per week. Only 6.5% of dentists placed rubber dam during removal and replacement of amalgam restorations. Fifty-five percent of dentists used high-volume evacuation. Filter was used only by 6% dentists. For 98%, dentists' evacuation drained into regular drain. Eighty-six percent of dentists never used amalgamator. Only 31% of dentists stored leftover amalgam scrap in radiographic fixer. Fifty-one percent of dentists disposed the bottle of leftover amalgam scrap along with BMW. One hundred percent of dentists disposed amalgam-contaminated gloves and cotton along with BMW. Only 17% of GDPs periodically monitored mercury vapors in their dental operatories. Conclusion: There exists a significant lack of knowledge regarding mercury hygiene and amalgam waste disposal among GDPs. Guidelines on mercury management need to be strongly implemented to prevent contamination of environment by mercury.

  12. Bond strengths of a porcelain material to different abutment substrates.

    Science.gov (United States)

    Ferrari, M; Mannocci, F; Vichi, A; Goracci, G

    2000-01-01

    The study evaluated the bond strength values of a single-unit all-porcelain material luted with an adhesive-resin cement to different abutment substrates: amalgam, compomer, traditional glass ionomer cement, microhybrid resin composite, two resin composites for abutment build-up, gold, sandblasted gold, dentin and enamel. Syntac enamel-dentin bonding system, in combination with IPS-Empress porcelain material, was used. After thermal cycling, the samples were inserted into a Bencor jig device and sheared in a Controls testing machine. The statistical analysis of the differences between the bond strength values obtained was performed by ANOVA and the Student-Newman-Keuls multiple-comparison test. The type of failure at the interface was evaluated using scanning electron microscopy. The type of failure, such as adhesive, cohesive and adhesive-cohesive, was correlated with bond strength values. Enamel, dentin and the two resin composites for crown build-up showed the highest bond strength values, while amalgam and gold samples showed the lowest.

  13. Gastrointestinal and in vitro release of copper, cadmium, indium, mercury and zinc from conventional and copper-rich amalgams

    International Nuclear Information System (INIS)

    Brune, D.; Gjerdet, N.; Paulsen, G.

    1983-01-01

    Particles of a conventional lathe-cut, a spherical non-gamma 2 and a copper amalgam have been gastrointestinally administered to rats for the purpose of evaluation of the dissolution resistance. The animals were sacrificed after 20 hrs. The contents of copper, cadmium, indium, mercury and zinc in kidney, liver, lung or blood were measured using nuclear tracer techniques. From a copper amalgam an extreme release of copper was demonstrated. This study simulates the clinical conditions of elemental release from swallowed amalgam particles after amalgam insertion or after removal of old amalgam fillings. Specimens of the same types of amalgams were also exposed to artificial saliva for a period of 10 days. The amounts of copper and mercury released were measured with flame and flameless atomic absorption spectrophotometry respectively. The levels of copper and mercury released from the copper amalgam were approximately 50 times those of the two other amalgam types studied. (author)

  14. Comparative evaluation of combined amalgam and composite resin restorations in extensively carious vital posterior teeth: An in vivo study.

    Science.gov (United States)

    Kaur, Gagandeep; Singh, Manpreet; Bal, Cs; Singh, Up

    2011-01-01

    The clinical performance of the combined composite - amalgam restorations in posterior teeth was evaluated. One hundred carious posterior teeth were randomly divided into four groups of 25 teeth each. In Group A, the teeth were restored with composite Z250 and amalgam FusionAlloy. In Group B, composite Surefil and amalgam were used. In Groups C and D, the teeth were restored with composite Surefil and amalgam FusionAlloy, respectively. The restorations were evaluated at 3, 6, 12, and 15 months, using the Ryge criteria. Combined restorations and amalgam restorations showed better contact and contour than the composite restorations. No statistically significant difference was observed among the groups. Three amalgam restorations exhibited loss of retention. The combined composite-amalgam restorations performed better for contact and contour and retention than composite and amalgam restorations, respectively.

  15. Clinical longevity of extensive direct composite restorations in amalgam replacement : Up to 3.5 years follow-up

    NARCIS (Netherlands)

    Scholtanus, Johannes D.; Ozcan, Mutlu

    2014-01-01

    Objectives: This prospective clinical trial evaluated the longevity of direct resin composite (DRC) restorations made on stained dentin that is exposed upon removal of existing amalgam restorations in extensive cavities with severely reduced macro-mechanical retention for amalgam replacement.

  16. Dental amalgam and urinary mercury concentrations: a descriptive study.

    Science.gov (United States)

    Nicolae, Alexandra; Ames, Harry; Quiñonez, Carlos

    2013-09-09

    Dental amalgam is a source of elemental and inorganic mercury. The safety of dental amalgam in individuals remains a controversial issue. Urinary mercury concentrations are used to assess chronic exposure to elemental mercury. At present, there are no indications of mercury-associated adverse effects at levels below 5 μg Hg/g creatinine (Cr) or 7 μg Hg/L (urine). The purpose of the present study is to determine the overall urinary mercury level in the Canadian general population in relation to the number of dental amalgam surfaces. Data come from the 2007/09 Canadian Health Measures Survey, which measured urinary mercury concentrations in a nationally representative sample of 5,418 Canadians aged 6-79 years. Urinary mercury concentrations were stratified by sex, age, and number of dental amalgam surfaces. The overall mean urinary mercury concentration varied between 0.12 μg Hg/L and 0.31 μg Hg/L or 0.13 μg Hg/g Cr and 0.40 μg Hg/g Cr. In general, females showed slightly higher mean urinary mercury levels than men. The overall 95th percentile was 2.95 μg Hg/L, the 99th percentile was 7.34E μg Hg/L, and the 99.9th percentile was 17.45 μg Hg/L. Expressed as μg Hg/g Cr, the overall 95th percentile was 2.57 μg Hg/g Cr, the 99th percentile was 5.65 μg Hg/g Cr, and the 99.9th percentiles was 12.14 μg Hg/g Cr. Overall, 98.2% of participants had urinary mercury levels below 7 μg Hg/L and 97.7% had urinary mercury levels below 5 μg Hg/g Cr. All data are estimates for the Canadian population. The estimates followed by the letter "E" should be interpreted with caution due to high sampling variability (coefficient of variation 16.6%-33.3%). The mean urinary mercury concentrations in the general Canadian population are significantly lower than the values considered to pose any risks for health.

  17. Comparative evaluation of combined amalgam and composite resin restorations in extensively carious vital posterior teeth: An in vivo study

    OpenAIRE

    Kaur, Gagandeep; Singh, Manpreet; Bal, CS; Singh, UP

    2011-01-01

    Aim : The clinical performance of the combined composite - amalgam restorations in posterior teeth was evaluated. Materials and Methods : One hundred carious posterior teeth were randomly divided into four groups of 25 teeth each. In Group A, the teeth were restored with composite Z250 and amalgam FusionAlloy. In Group B, composite Surefil and amalgam were used. In Groups C and D, the teeth were restored with composite Surefil and amalgam FusionAlloy, respectively. The restorations were ...

  18. Benchmarking Parameter-free AMaLGaM on Functions With and Without Noise

    NARCIS (Netherlands)

    P.A.N. Bosman (Peter); J. Grahl; D. Thierens (Dirk)

    2013-01-01

    htmlabstractWe describe a parameter-free estimation-of-distribution algorithm (EDA) called the adapted maximum-likelihood Gaussian model iterated density-estimation evolutionary algorithm (AMaLGaM-IDEA, or AMaLGaM for short) for numerical optimization. AMaLGaM is benchmarked within the 2009 black

  19. On Reduced Amalgamated Free Products of C*-algebras and the MF-Property

    DEFF Research Database (Denmark)

    Seebach, Jonas A.

    We establish an isomorphism of the group von Neumann algebra of an amalgamated free product of countable Abelian discrete groups. This result is then used to give some new examples of reduced group $ C^* $-algebras which are MF. Finally, we give a characterization of the amalgamated free products...

  20. A study of sister chromatid exchange in patients with dental amalgam restorations

    Directory of Open Access Journals (Sweden)

    E Lakshmi Priya

    2014-01-01

    Conclusion: Systemic genotoxicity was not observed due to the components of amalgam restorations released during its placement and chronic use. The findings of this study can be considered as preliminary information on the systemic toxicity due to the components of amalgam restorations.

  1. Treatment of an amalgam tattoo with the Q-switched ruby laser.

    Science.gov (United States)

    Ashinoff, R; Tanenbaum, D

    1994-10-01

    The amalgam tattoo is an asymptomatic, ill-defined pigmented macule or patch on the gingiva, buccal mucosa, or mucobuccal fold. It can be cosmetically disfiguring if present on the anterior gingiva. The only reported treatments have involved extensive surgery and grafting. We report use of the Q-switched ruby laser to remove a gingival amalgam tattoo.

  2. 78 FR 38872 - Approval and Promulgation of Air Quality Implementation Plans; Idaho Amalgamated Sugar Company...

    Science.gov (United States)

    2013-06-28

    ... Sugar Company Nampa BART Alternative AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed... determination and an alternate control measure for The Amalgamated Sugar Company, LLC. (TASCO) plant located in... their Nampa facility. See Amalgamated Sugar v. EPA, No. 11-72445 (9th Cir.) The case is pending before...

  3. Discrete Silver(I)-Palladium(II)-Oxo Nanoclusters, {Ag4Pd13} and {Ag5Pd15}, and the Role of Metal-Metal Bonding Induced by Cation Confinement.

    Science.gov (United States)

    Yang, Peng; Xiang, Yixian; Lin, Zhengguo; Lang, Zhongling; Jiménez-Lozano, Pablo; Carbó, Jorge J; Poblet, Josep M; Fan, Linyuan; Hu, Changwen; Kortz, Ulrich

    2016-12-19

    We introduce the class of discrete silver(I)-palladium(II)-oxo nanoclusters with the preparation of {Ag 4 Pd 13 } and {Ag 5 Pd 15 }. Both polyanions represent the first examples of noble metal-capped polyoxo-noble-metalates in a fully inorganic assembly, featuring an unprecedented host-guest mode containing hetero- and homometallic Ag-Pd and Ag-Ag bonding interactions. Comprehensive theoretical calculations suggest that the Ag-Pd metallic bonds originate partially from surface confinement of Ag I guest ions onto the anionic polyoxopalladate host that is induced by strong electrostatic forces. This work opens the field of fully inorganic silver-palladium-oxo nanoclusters, which can be considered as discrete mixed noble metal precursors for the formation of monodisperse core-shell nanoparticles, with high relevance for catalysis. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. [Black or white--is amalgam 'out'? Part 1. Amalgam or composite: which of these 2 materials is the most deleterious?].

    Science.gov (United States)

    De Moor, Roeland; Delmé, Katleen

    2008-01-01

    Dental amalgam containing mercury has been condemned because of its toxicity and hence to be damaging of harmful to the general health. It must be clear that many sensational, confusing and misleading reports have been published. Today there is evidence that dental amalgam in the oral cavity does not harm anyone's health. For those who are condemning amalgam there an abundant number of alarming reports taking into consideration the biologic effects of resin composites: methacrylate allergy for dentists and dental technicians, the three-finger-syndrome due to contact with liquid resin, allergic reactions at the level of the airways and breathing problems caused by dust particles (esp. composite particles after polishing procedures) have been described. It can be concluded that dental amalgam is not more toxic than resin composite in light of both patients' and dental care providers' health. Recent investigations demonstrated higher than expected health risks with resin composites.

  5. Attitudes of dentists and interns in Riyadh to the use of dental amalgam.

    Science.gov (United States)

    Alkhudhairy, Fahad

    2016-11-17

    Studies investigating the attitudes of Saudi dentists to the use of amalgam for restorations are relatively rare. Considering the goals set forth by the Minamata Convention on Mercury, it appears prudent to investigate the attitudes of experienced dentists and fresh dental graduates to the use of amalgam. The aim of this study was to assess the attitudes of Saudi dentists and interns working in Riyadh, Saudi Arabia to the use of amalgam. Using a convenience sampling methodology, a total of 400 Saudi dentists and interns were contacted to request their participation in this cross-sectional questionnaire-based study. The questionnaire consisted of socio-demographic and practice characteristics such as gender, type of practice, as well as their service sector and questions related to the use of dental amalgam. The data obtained was analyzed using Chi square tests to compare differences in distribution between groups. P values of less than 0.05 were considered statistically significant. The overall response rate was 84% (336 of 400 potential participants). The majority of the participants (80.7%) did not use dental amalgam for restorations in their clinical practice frequently. A significantly higher number of participants working in private sector did not use amalgam frequently (P = 0.004), agreed on replacing good amalgam restoration with composite resin (P amalgam as a final restoration (P = 0.017) compared to participants working in public sector. A significantly higher number of interns did not use amalgam in their clinical practice frequently (P amalgam restoration with composite resin (P = 0.002) and on stopping the use of amalgam as a final restoration (P amalgam seems to be less frequently used among the surveyed Saudi dentists and interns working in Riyadh. Fresh dental graduates used amalgam less frequently compared to experienced dentists. Furthermore, private dental practitioners showed a propensity to replace existing well-placed amalgam

  6. The longevity of amalgam versus compomer/composite restorations in posterior primary and permanent teeth: findings From the New England Children's Amalgam Trial.

    Science.gov (United States)

    Soncini, Jennifer Ann; Maserejian, Nancy Nairi; Trachtenberg, Felicia; Tavares, Mary; Hayes, Catherine

    2007-06-01

    Limited information is available from randomized clinical trials comparing the longevity of amalgam and resin-based compomer/composite restorations. The authors compared replacement rates of these types of restorations in posterior teeth during the five-year follow-up of the New England Children's Amalgam Trial. The authors randomized children aged 6 to 10 years who had two or more posterior occlusal carious lesions into groups that received amalgam (n=267) or compomer (primary teeth)/composite (permanent teeth) (n=267) restorations and followed them up semiannually. They compared the longevity of restorations placed on all posterior surfaces using random effects survival analysis. The average+/-standard deviation follow-up was 2.8+/-1.4 years for primary tooth restorations and 3.4+/-1.9 years for permanent tooth restorations. In primary teeth, the replacement rate was 5.8 percent of compomers versus 4.0 percent of amalgams (P=.10), with 3.0 percent versus 0.5 percent (P=.002), respectively, due to recurrent caries. In permanent teeth, the replacement rate was 14.9 percent of composites versus 10.8 percent of amalgams (P=.45), and the repair rate was 2.8 percent of composites versus 0.4 percent of amalgams (P=.02). Although the overall difference in longevity was not statistically significant, compomer was replaced significantly more frequently owing to recurrent caries, and composite restorations required seven times as many repairs as did amalgam restorations. Compomer/composite restorations on posterior tooth surfaces in children may require replacement or repair at higher rates than amalgam restorations, even within five years of placement.

  7. Multiple sclerosis and dental amalgam: case-control study in Ferrara, Italy.

    Science.gov (United States)

    Casetta, I; Invernizzi, M; Granieri, E

    2001-05-01

    Dental amalgam fillings containing mercury have been suggested as a possible risk factor for multiple sclerosis (MS). In the context of a wider program of investigation into environmental risk factors and MS, we conducted a case-control comparison to investigate the alleged association between MS, dental caries, and amalgam fillings. We included 132 MS patients with onset during the last 16 years and 423 controls, matched to cases for sex, age and residence. Data were collected by a personal interview conducted by trained doctors. Cases and controls gave informed consent. Although we report a trend toward a higher number of dental fillings in cases than controls, odds ratios for subjects with exposures of different duration and with different numbers of amalgam fillings were not statistically significant. This case-control study failed to demonstrate an association between either the number of dental amalgam fillings or the duration of exposure to mercury amalgam and MS. Copyright 2001 S. Karger AG, Basel

  8. Amalgam and composite posterior restorations: curriculum versus practice in operative dentistry at a US dental school.

    Science.gov (United States)

    Ottenga, Marc E; Mjör, Ivar

    2007-01-01

    This study recorded the number of preclinical lecture and simulation laboratory sessions spent teaching the preparation and placement of amalgam and resin composite posterior restorations. These data were compared to the use of both materials in the operative clinic as placed by third- and fourth-year students. The number of posterior restorations inserted by the students, expressed as a function of the number of restoration surfaces, was also evaluated. The results show that the teaching of posterior restorations pre-clinically has consistently favored amalgam 2.5 to 1 during the last three years. However, clinically, resin composite is being used for posterior restorations 2.3 times more often than amalgam. The only instance that favored amalgam over composite during the last year was in the placement of four surface posterior restorations. This shift in emphasis from amalgam to composite needs to be addressed within dental educational institutions so that newly graduated dentists are prepared to place composite restorations properly.

  9. Stuck in Our Teeth? Crystal Structure of a New Copper Amalgam, Cu3Hg

    Directory of Open Access Journals (Sweden)

    Jonathan Sappl

    2017-11-01

    Full Text Available We have synthesized a new Cu amalgam, the Cu-rich phase Cu 3 Hg. It crystallizes with the Ni 3 Sn structure type with a hexagonal unit cell (space group P6 3 /mmc , a = 5.408(4 Å, c = 4.390(3 Å and shows some mixed occupancy of Cu on the Hg site, resulting in a refined composition of Cu 3.11 Hg 0.89 . This is the first example of an amalgam with the Ni 3 Sn structure type where Hg is located mainly on the Sn site. Cu 3 Hg might be one of the phases constituting dental amalgams and therefore has major relevance, as well as the only Cu amalgam phase described so far, Cu 7 Hg 6 with the γ -brass structure. It occurs as a biphase in our samples. Thermal decomposition of Cu amalgam samples in a dynamic vacuum yields nanostructured copper networks, possibly suitable for catalytic applications.

  10. Amalgams for fluorescent lamps. Pt. I. Thermodynamic design rules and limitations

    Energy Technology Data Exchange (ETDEWEB)

    Lankhorst, M.H.R. [Philips Research Labs., Eindhoven (Netherlands); Niemann, U. [Philips Forschungslaboratorien, Weishausstr. 2, 52066, Aachen (Germany)

    2000-08-10

    In compact fluorescent lamps, amalgams can be used to control the mercury vapour pressure inside the lamp. Since the optimal mercury vapour pressure and the coolest spot temperature of these lamps differ for each particular lamp configuration, it is desired to be able to design amalgams in such a way that a mercury vapour pressure versus temperature curve suitable for an optimal light-output is obtained for each particular lamp geometry. Using regular solution thermodynamics, relations have been derived between the mercury vapour pressure of the amalgam and the melting point, melting enthalpy and mercury interaction enthalpy of the underlying alloy. From these relations amalgam design rules and amalgam design limitations have been formulated. (orig.)

  11. The future of dental amalgam: a review of the literature. Part 7: Possible alternative materials to amalgam for the restoration of posterior teeth.

    Science.gov (United States)

    Eley, B M

    1997-07-12

    This is the last in a series of articles on the future of dental amalgam. It considers possible alternative materials to amalgam for the restoration of posterior teeth. The materials discussed are gold inlays, gold foil, gallium alloys, and tooth coloured non-metal alternatives including glass-ionomer cements, composite resins, glass-ionomer-resin hybrids, compomers and ceramics. The clinical indications for these restorations are first described along with their potential clinical problems and their mean survival rates in comparison with dental amalgam. Secondly, the safety of composite resins is considered and potential toxic and hypersensitive effects of these materials are discussed. Finally, it is concluded that the present evidence does not appear to demonstrate that dental amalgam is hazardous to the health of the general population. It does, however, recommend that in continuing to use amalgam dentists must use strict mercury hygiene procedures to avoid risk to their staff and contamination of the environment. It seems that mercury contamination of the environment is likely to be the main reason for any future government action against the continued clinical use of dental amalgam.

  12. Preparation and corrosion behavior evaluation of amalgam/titania nano composite.

    Science.gov (United States)

    Tolou, Neda Bahremandi; Fathi, Mohammadhossein; Monshi, Ahmad; Mortazavi, Vajihesadat; Shirani, Farzaneh

    2011-12-01

    Many attempts have been performed and continued for improvement of dental amalgam properties during last decades. The aim of present research was fabrication and characterization of amalgam/titania nano composite and evaluation of its corrosion behavior. In this experimental research, nano particles of titania were added to initial amalgam alloy powder and then, dental amalgam was prepared. In order to investigate the effect of nano particle amounts on properties of dental amalgam, proper amount of 0, 0.5, 1, 2 and 3 wt% of titania nano particles were added to amalgam alloy powder and the prepared composite powder was triturated by a given percent of mercury. X-ray Diffraction, Scanning Electron Microscopy and Energy-Dispersive Spectroscopy techniques were use to characterize the prepared nano composites. Potentiodynamic polarization corrosion tests were performed in the Normal Saline (0.9 wt% NaCl) and Ringer's solutions as electrolytes at 37°C. Immersion corrosion tests were also performed immediately 2 h after preparation of cylindrical samples (4 mm in diameter and 8 mm height) via immersion into a 100 ml volumetric flask consisting of artificial saliva. The results indicated that the current corrosion density of amalgam/titania nano composite changes a bit with adding 1% of nano particles of titania. Also, during the 1(st) h after preparation, initial released mercury from prepared nano composite dental amalgam decreased. By adding nano particles of titania and preparing amalgam/titania nano composite as a dental amalgam, corrosion behavior and mercury release during the 2(st) h after preparation could be improved.

  13. A variety of amalgamated allusion in Saeb’s sonnet

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    Siavash Haghjoo

    2014-12-01

    Full Text Available Abstract Poetic figures of speech are among the factors which their prominence in a poet’s poetry makes up his/her specific style. One of the figures of speech and poetic techniques is allusive figures of speech or amalgamated allusions. As the name entails, these are types of figures in which allusion is located at the center and amalgamates with other figures. Such amalgamation brings about a novel complicated figure of speech.  One special type of allusive figures of speech is an allusion which is occasionally amalgamated with metaphor and ambiguity, and at times in addition to metaphor and ambiguity with simile. The origin of this figure, which is recently referred to as “metaphoric ambiguous allusion, is traced back to Hakim baz in Persian literature. Although, poetry of Hafez is replete with metaphoric ambiguous allusion, it is considerably ubiquitous in Indian style in a way that its ignorance especially in Saeb’s poetry implies the denial of one of its foremost stylistic qualities. The mixed nature of this figure and the presence of several robust figures besides each other which are the basis of poetic fantasy and a fantastic presentation is created by combination of these figures. These figures invite readers into a mode of reflection and thinking and opens corridors of fantasy towards him replete with unsurpassable satisfaction. Such amalgamated figure is formed when a poet grants an allusion to a phenomenon which in reality the phenomenon owns such quality but in a different conceptualization. Supposedly, the given figure was Saeb’s major artifact which helped him to fulfill his distinct poetic quality i.e. unsurpassed power of creating vivacious contents. The present article intended to conduct a supplementary reanalysis of “metaphoric ambiguous allusion and its different varieties and examined it in Saeb’s Poetry. Metaphoric ambiguous allusion refers to a metaphor which alludes to something. The characteristics of the

  14. Calorimetric investigations of hydrogen bonding in binary mixtures containing pyridine and its methyl-substituted derivatives. II. The dilute solutions of methanol and 2-methyl-2-propanol

    International Nuclear Information System (INIS)

    Marczak, Wojciech; Heintz, Andreas; Bucek, Monika

    2004-01-01

    Enthalpies of solution of methanol and 2-methyl-2-propanol (tert-butanol) in pyridine and its methyl derivatives were investigated in the range of mole fractions of alcohol x≤0.02 at temperature 298.15 K by a titration calorimeter. Dissolution of methanol is an exothermic process, with heat effects very close to those for water reported in part I of this study. The negative enthalpy of solution increases in the following order: pyridine < 3-methylpyridine < 4-methylpyridine < 2-methylpyridine < 2,6-dimethylpyridine < 2,4,6-trimethylpyridine. Positive enthalpies of solution of 2-methyl-2-propanol increase as follows: 2-methylpyridine < 2,4,6-trimethylpyridine < 4-methylpyridine < 2,6-dimethylpyridine < 3-methylpyridine < pyridine. The propensity of pyridine derivatives to hydrogen bonding is enhanced by the ortho effect. Methyl groups are probably too small to prevent the nitrogen atom in the pyridine ring from hydrogen bonding. However, spacious hydrocarbon group in 2-methyl-2-propanol molecule makes the bonding difficult for 2,6-dimethylpyridine and 2,4,6-trimethylpyridine, thus the number of O-H···N bonds is smaller than that in the solutions of methanol or water. The two latter seem to be very close to each other

  15. How overdrying wood reduces its bonding to phenol-formaldehyde adhesives : a critical review of the literature. Part II, Chemical reactions

    Science.gov (United States)

    Alfred W. Christiansen

    1991-01-01

    Literature dealing with the effect of excessive drying (overdrying) on wood surface inactivation to bonding is reviewed in two parts and critically evaluated, primarily for phenolic adhesives. Part 1 of the review, published earlier, covers physical mechanisms that could contribute to surface inactivation. The principal physical mechanism is the migration to the...

  16. Neurobehavioral effects of dental amalgam in children: a randomized clinical trial.

    Science.gov (United States)

    DeRouen, Timothy A; Martin, Michael D; Leroux, Brian G; Townes, Brenda D; Woods, James S; Leitão, Jorge; Castro-Caldas, Alexandre; Luis, Henrique; Bernardo, Mario; Rosenbaum, Gail; Martins, Isabel P

    2006-04-19

    Dental (silver) amalgam is a widely used restorative material containing 50% elemental mercury that emits small amounts of mercury vapor. No randomized clinical trials have determined whether there are significant health risks associated with this low-level mercury exposure. To assess the safety of dental amalgam restorations in children. A randomized clinical trial in which children requiring dental restorative treatment were randomized to either amalgam for posterior restorations or resin composite instead of amalgam. Enrollment commenced February 1997, with annual follow-up for 7 years concluding in July 2005. A total of 507 children in Lisbon, Portugal, aged 8 to 10 years with at least 1 carious lesion on a permanent tooth, no previous exposure to amalgam, urinary mercury level or =67, and with no interfering health conditions. Routine, standard-of-care dental treatment, with one group receiving amalgam restorations for posterior lesions (n = 253) and the other group receiving resin composite restorations instead of amalgam (n = 254). Neurobehavioral assessments of memory, attention/concentration, and motor/visuomotor domains, as well as nerve conduction velocities. During the 7-year trial period, children had a mean of 18.7 tooth surfaces (median, 16) restored in the amalgam group and 21.3 (median, 18) restored in the composite group. Baseline mean creatinine-adjusted urinary mercury levels were 1.8 microg/g in the amalgam group and 1.9 microg/g in the composite group, but during follow-up were 1.0 to 1.5 microg/g higher in the amalgam group than in the composite group (Pamalgam and composite groups over all 7 years of follow-up, with no statistically significant differences observed at any time point (P values from .29 to .91). Starting at 5 years after initial treatment, the need for additional restorative treatment was approximately 50% higher in the composite group. In this study, children who received dental restorative treatment with amalgam did not, on

  17. Evaluation of Relation between Mercury Concentration in Saliva with Number and Surfaces of Amalgam Fillings

    Directory of Open Access Journals (Sweden)

    F. Agha Hosseini

    2004-09-01

    Full Text Available Statement of Problem: Amalgam is the most widely used dental restorative material.However, because of continuous low-level release of Mercury from amalgam fillings, its safety has been questionable.Purpose: The aim of this study was the evaluation of concentration of Mercury in saliva before and after amalgam fillings and its relation with numbers and surfaces of amalgam fillings.Materials and Methods: In an analytic interventional study we surveyed concentration Mercury in saliva before and after amalgam fillings. Twenty-five Patients (9 male, 16 female who referred to oral medicine department of Tehran university of medical scienceand Haj- Abdol- Vahab medical center who had no amalgam fillings were selected and the samples of saliva (5cc was collected before fillings. After that all of posterior decayed teeth were filled in an appointment with amalgam and, 24 hours later, the second samplesof saliva (5cc was collected. The amount of saliva Mercury before and after filling was measured and its difference was analyzed by paired t- test.Results: In this study the mean of Mercury in saliva was 0.00896 μg/ml before and 0.16404 μg/ml after amalgam fillings. The mean of number of fillings was 1.96 and mean of size of surfaces was 76.43 mm2 and mean of consumption amalgam was 4.1 units.Conclusion: There was no significant correlation between age (P=0.677, sex, number of fillings (P=0.055, number of surface of filling (P=0.059 and size of surfaces of fillings (P=0.072, with Mercury levels in saliva after amalgam fillings. There was a significant relation between Mercury level of saliva after fillings and amalgam amount (P= 0.036.Therefore amalgam may be designate a significant source for Mercury release in saliva.Since this is a preliminary study, it needs supplementary evaluations in saliva, blood and urine in different periods after amalgam fillings.

  18. N-H bond activation by palladium(ii) and copper(i) complexes featuring a reactive bidentate PN-ligand

    NARCIS (Netherlands)

    de Boer, S.Y.; Gloaguen, Y.; Reek, J.N.H.; Lutz, M.; van der Vlugt, J.I.

    2012-01-01

    The first examples of reactivity at the backbone of a bidentate PN-ligand L1H relevant to N-H activation are described, leading to novel PdII and CuI amido complexes. Activation of the PN-ligand backbone led to selective dearomatization of the pyridyl ring structure. In the case of PdII, the

  19. Constructions of a set of novel hydrogen-bonded supramolecules from reactions of cobalt(II) salt with bis(3,5-dimethylpyrazolyl)methane and different carboxylic acids

    Science.gov (United States)

    Li, Qiao-Yun; Tang, Xiao-Yan; Zhang, Wen-Hua; Wang, Jing; Ren, Zhi-Gang; Li, Hong-Xi; Zhang, Yong; Lang, Jian-Ping

    2008-05-01

    Reactions of CoX 2·6H 2O (X = Cl -, ClO 4-) with bis(3,5-dimethylpyrazolyl)methane (dmpzm) and formic acid, acetic acid, benzoic acid, salicylic acid, maleic acid, or fumaric acid under the presence of KOH solution produced a new family of Co(II)/dmpzm complexes, [Co(dmpzm) 2L]X· nH 2O ( 1: L = O 2CH, X = Cl, n = 2; 2: L = OAc, X = Cl, n = 3; 3: L = benzoate, X = ClO 4, n = 1/3; 4: L = salicylate, X = ClO 4, n = 1/3) and [Co 2(dmpzm) 4L](ClO 4) 2· nSolv ( 5: L = maleate, n = 3, Solv = H 2O; 6: L = fumarate, n = 2, Solv = MeOH). These compounds were structurally characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Compounds 1- 4 are mononuclear while 5- 6 are binuclear. Each cobalt atom of 1- 6 is hexacoordinate, with a distorted octahedral CoN 4O 2 coordination geometry incorporating two N, N'-bidentate dmpzm ligands and one O, O'-bidentate carboxylate ligand. There are rich intra- and intermolecular hydrogen bonds in the crystals of 1- 6, thereby forming either 2D hydrogen-bonded networks ( 1 and 2) or 3D hydrogen-bonded networks ( 3- 6). In addition, the thermal behaviors of 1- 6 were also investigated.

  20. Comparative electrochemical investigation of the effect of aging on corrosion of dental amalgam.

    Science.gov (United States)

    Amin, Wala M

    2007-01-01

    To investigate corrosion in dental amalgam and evaluate the effects of composition and long-term aging on the alloy's corrosion behavior. A sample of high-copper and low-copper formulations was employed. Corrosion tests were performed using a 3-electrode polarization cell. Anodic polarization curves were drawn, and the potential and the current density corresponding to the first anodic peak were registered. Scanning electron microscopy was performed, and the different metallurgical phases of the alloy's microstructure were examined and analyzed chemically using an energy-dispersive x-ray technique. The amalgams' corrosion behavior was evaluated at 1 week and after aging in a simulated oral environment for 6 months, 1 year, and 2 years. Data were analyzed using analysis of variance (ANOVA)Scheffe post hoc test at a .05 significance level. The potential values recorded by the high-copper amalgam were higher (P amalgam than in the high-copper alloy. For both formulations the potentials increased significantly (P amalgam. High-copper amalgam exhibited better resistance to corrosion than the low-copper alloy. Aging in a simulated oral environment improved corrosion behavior for both high- and low-copper amalgams.

  1. Restorative service patterns in Australia: amalgam, composite resin and glass ionomer restorations.

    Science.gov (United States)

    Brennan, D S; Spencer, A J

    2003-12-01

    To examine the provision of amalgam, composite resin and glass ionomer restorations, and to assess whether these main restorative services varied by patient, visit and oral health characteristics. A cross-sectional survey incorporating a log of service items provided on a typical day. Australian private general practice. Data on services and patients were collected by a mailed survey from a random sample of dentists from each State/Territory in Australia in 1998-99 with a response rate of 71%. Rates per visit of amalgam, composite resin and glass ionomer restorations among dentate adults who had received a restoration. Analysis showed older patients had lower amalgam rates but higher glass ionomer rates, composite resin rates were lower at emergency visits, capital city patients had higher amalgam rates but lower composite resin rates, patients with decayed teeth had higher amalgam and composite resin rates, and use of restorative materials varied by clinical problem. Despite widespread use of alternative materials, amalgam rates remained high in circumstances such as replacement restorations and restorations involving more than one surface. Other restorative materials also had specific applications. Both amalgam and composite resins were provided at higher rates to patients with active caries but composite resins were also used at higher rates for aesthetic problems. Glass ionomer restorations were used at higher rates for initial and one-surface restorations, and for conditions such as root caries and dentinal sensitivity.

  2. Secondary Caries Development in in situ Gaps next to Composite and Amalgam.

    Science.gov (United States)

    Kuper, Nicolien K; Montagner, Anelise F; van de Sande, Françoise H; Bronkhorst, Ewald M; Opdam, Niek J M; Huysmans, Marie-Charlotte D J N M

    2015-01-01

    This in situ study investigated the secondary caries development in dentin in gaps next to composite and amalgam. For 21 days, 14 volunteers wore a modified occlusal splint containing human dentin samples with an average gap of 215 µm (SD=55 µm) restored with three different materials: Filtek Supreme composite, Clearfil AP-X composite and Tytin amalgam. Eight times a day, the splint with samples was dipped in a 20% sucrose solution for 10 min. Before and after caries development, specimens were imaged with transversal wavelength independent microradiography, and lesion depth (LD) and mineral loss (ML) were calculated. The LD and ML of the three restoration materials were compared within patients using paired t tests (α=5%). In total 38 composite samples (Filtek n=19 and AP-X n=19) and 19 amalgam samples could be used for data analysis. AP-X composite presented the highest mean values of LD and ML of the three restorative materials. Amalgam showed statistically significantly less ML (Δ=452 µm×vol%) than the combined composite materials (p=0.036). When comparing amalgam to the separate composite materials, only AP-X composite showed higher ML (Δ=515 µm×vol%) than amalgam (p=0.034). Analysis of LD showed the same trends, but these were not statistically significant. In conclusion, amalgam showed reduced secondary caries progression in dentin in gaps compared to composite materials tested in this in situ model. © 2015 S. Karger AG, Basel.

  3. Mercury release of amalgams with various silver contents after exposure to bleaching agent.

    Science.gov (United States)

    Bahari, Mahmoud; Alizadeh Oskoee, Parnian; Savadi Oskoee, Siavash; Pouralibaba, Firoz; Morsali Ahari, Ali

    2016-01-01

    Background. Since it is possible for carbamide peroxide (CP) bleaching agent to contact old amalgam restorations, the present in vitro study evaluated the amount of dissolved mercury released from amalgam restorations with various percent-ages of silver content subsequent to the use of 15% CP. Methods. Thirty ANA 2000 amalgam disks with 43.1% silver content and thirty ANA 70 amalgam disks with 69.3% silver content were prepared. In each group, 15 samples were randomly placed in glass tubes containing 15% CP (as experimental groups) and the remaining 15 samples were placed in buffered phosphate solution (as control groups) with the same 3-mL volume for 48 hours. Subsequently, the amount of mercury dissolved in each test tube was measured using Mercury Analyzing System (Cold Vapor Atomic Absorption, MASLO, Shimadzu, Japan). Data was analyzed with two-way ANOVA and a post hoc Tukey test. (α = 0.05). Results. The amount of mercury released after exposure to CP was significantly higher than that released after exposure to buffered phosphate (P amalgam with a silver content of 43% was significantly higher than that released from dental amalgam with a silver content of 69% (P amalgam.

  4. Vaporization of Hg from Hg-in amalgams during setting and after abrasion.

    Science.gov (United States)

    Ferracane, J; Adey, J; Wiltbank, K; Nakajima, H; Okabe, T

    1999-05-01

    The aim of this study was to determine if Hg vaporization during setting and after abrasion of amalgams could be reduced by adding indium to Hg prior to trituration. Hg-In alloys (0,5,10,15 wt% In) were triturated with commercial amalgam alloys (Tytin, Kerr; Artalloy, Degussa; Sybraloy, Kerr) and condensed into cylinders (4 x 8 mm). In one experiment, Hg release during setting was measured in air (37 degrees C) with a Jerome 431 Hg analyzer (n = 4). In a second experiment, amalgams aged two months were uniformly abraded on wet #600 SiC, blotted dry, and Hg release was measured in air (22 degrees C) for 30 min with a Jerome 411 Hg analyzer (n = 6). Total Hg was determined by integration (ng/mm2). Results were compared by ANOVA and Tukey's test (alpha = 0.05). Indium reduced Hg release from amalgams during setting. Amalgams ceased Hg release within 5 h. Indium did not reduce Hg release from abraded, set amalgams except Artalloy w/15% In. Coupled with our previous studies, this work shows that 5-15 wt% indium can be added to effectively reduce Hg release during setting, but not after abrasion of set amalgams.

  5. Mercury release of amalgams with various silver contents after exposure to bleaching agent

    Directory of Open Access Journals (Sweden)

    Mahmoud

    2016-06-01

    Full Text Available Background. Since it is possible for carbamide peroxide (CP bleaching agent to contact old amalgam restorations, the present in vitro study evaluated the amount of dissolved mercury released from amalgam restorations with various percent-ages of silver content subsequent to the use of 15% CP. Methods. Thirty ANA 2000 amalgam disks with 43.1% silver content and thirty ANA 70 amalgam disks with 69.3% silver content were prepared. In each group, 15 samples were randomly placed in glass tubes containing 15% CP (as experimental groups and the remaining 15 samples were placed in buffered phosphate solution (as control groups with the same 3-mL volume for 48 hours. Subsequently, the amount of mercury dissolved in each test tube was measured using Mercury Ana-lyzing System (Cold Vapor Atomic Absorption, MASLO, Shimadzu, Japan. Data was analyzed with two-way ANOVA and a post hoc Tukey test. (α = 0.05 Results. The amount of mercury released after exposure to CP was significantly higher than that released after exposure to buffered phosphate (P < 0.001. In addition, the amount of mercury released from dental amalgam with a silver content of 43% was significantly higher than that released from dental amalgam with a silver content of 69% (P < 0.001. Conclusion. The amount of mercury release is inversely proportional to the silver content of dental amalgam.

  6. Surface analysis of dental amalgams by X-ray photoelectron spectroscopy and X-ray diffraction.

    Science.gov (United States)

    Uo, Motohiro; Berglund, Anders; Cardenas, Juan; Pohl, Lars; Watari, Fumio; Bergman, Maud; Sjöberg, Staffan

    2003-11-01

    It is important to characterize the surface of dental amalgam in order to understand the process of mercury release from amalgam restorations in the oral cavity. The mercury evaporation occurs not only from the newly made restoration but also from the set material. The surfaces of four different types of amalgams, which had been well set, were analyzed with X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) and the relationship between surface compositions and mercury release was studied. Fresh amalgam surfaces as well as aged surfaces, which were stored for 30 days in air, were investigated using XPS and the chemical states of amalgam components and oxygen were studied. The aged surfaces were also characterized with XRD and grazing angle XRD. With increased oxidation, the surface contents of tin and oxygen were increased in all amalgams. In contrast, the surface contents of copper and mercury were decreased. An increase of zinc or indium content were observed in zinc or indium containing amalgams, respectively. A surface layer enriched with indium and oxygen was clearly detected by XPS but not with grazing angle XRD. The thickness of the enriched surface layer is estimated to be in the order of few nanometer, which is approximately equal to the analysis depth of XPS. In addition, the presence of metallic elements, like tin and zinc, that readily form a stable oxide layer at the surface suppress the release of mercury.

  7. Effect of diode laser irradiation on compressive strength of dental amalgam

    Science.gov (United States)

    Tabari, Mitra; Fekrazad, Reza; Alaghemand, Homayoun; Hamzeh, Mahtab

    2017-01-01

    Introduction One of the biggest disadvantages of dental amalgam is that gaining its ultimate strength is a slow process. The use of a rapid-setting amalgam with high early compressive strength could be a better option in preventing early fractures in pediatric dentistry. The aim of this study was to determine the effect of diode laser irradiation on compressive strength of dental amalgam. Methods A case-control study was performed on 180 amalgam samples made at the Tehran Dental Material Research Center in 2014. Fifteen and thirty minute compressive strength of regular setting and fast setting amalgams were measured as control. In case groups, the samples were irradiated by 810nm diode laser with power of 1 and 2 watt and in pulsed and continuous mode, and compressive strength was measured after 15 and 30 minutes. Statistical analysis was performed with SPSS 18 using one and two way ANOVA and Scheffe multiple comparisons test and plaser irradiation led to a significant increase in compressive strength compared to regular setting control groups. Fifteen minutes-compressive strength of regular-setting amalgam irradiated by 2 watt laser was significantly more than fast-setting control group (plaser can significantly increase the compressive strength of dental amalgam especially in the first 15 minutes. PMID:28607639

  8. The mercury concentration in breast milk resulting from amalgam fillings and dietary habits.

    Science.gov (United States)

    Drexler, H; Schaller, K H

    1998-05-01

    Health risks from amalgam fillings are a subject of controversy. In Germany it is not advised to use amalgam fillings during breast feeding. Objectives of this study were to examine the concentration of mercury in human breast milk and the confounders which may modify the mercury levels. Women who gave birth between August 1995 and May 1996 in a district hospital were asked to participate in the study. The examination included a standardized anamnesis and an inspection of the teeth by an dentist. Blood and urine samples of 147 women and breast milk samples of 118 women were collected in the first week after birth. After 2 months of breast feeding a second breast milk sample was collected from 85 of women. Mercury was measured by cold-vapor atomic absorption spectrometry. The concentration of mercury in the breast milk collected immediately after birth showed a significant association with the number of amalgam fillings as well as with the frequency of meals. Urine mercury concentrations correlated with the number of amalgam fillings and amalgam surfaces. In the breast milk after 2 months of lactation, the concentrations were lower (mean: consumption but no longer with the number of the amalgam fillings. Accordingly, the additional exposure to mercury of breast-fed babies from maternal amalgam fillings is of minor importance compared to maternal fish consumption. Copyright 1998 Academic Press.

  9. Effect of corrosion on the strength of dental silver amalgam.

    Science.gov (United States)

    Darvell, B W

    2012-09-01

    To characterize the effect of crevice corrosion on the strength of dental silver amalgam as determined by the Hertzian 'ball on disc' method, with a view to providing a test method for use in standards compliance testing. Sixteen dental silver amalgam products were tested using the 'ball on disc' protocol at 30 d after setting at 37°C in air or immersed in artificial saliva at pH 6.2. The mixed materials were packed into a tapered steel disc mold (10 mm diameter, 3 mm thick) resting on a glass surface, slightly overfilled and carved level with a sharp edge, then ejected at ∼10 min and placed immediately into an incubator at 37°C. For corrosion specimens, the disc was laid on a flat polystyrene surface, immersed in artificial saliva, to create a spontaneous crevice corrosion cell. Testing was in Hertzian mode, using a 20 mm steel ball, with the specimen resting on a disc of glass-filled polyamide (E=10 GPa) at a cross-head speed of 0.2 mm/min on a universal testing machine (E3000, Instron). The load at first crack was recorded, as was the number of radial cracks produced. Radial cracking into 2-4 pieces, in a clinically relevant (non-explosive) mode was observed in all cases. On average, corrosion caused a decrease in load at failure of ∼10%, although the interaction with alloy (analysis of variance) was significant (P∼0.03) indicating variation between products. Comparison of the 30 d dry (uncorroded) results with those at 24h obtained earlier showed that there was highly significant increase on average (P∼5×10(-12)), but again a significant variation between products (P∼5×10(-6)), the maximum effect being +22%. The ball-on-disc test provides a facile means of ascertaining the sensitivity of dental silver amalgam to corrosion under clinically relevant conditions, and is viable as a standards compliance test. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Effect of topical fluoride application before and after amalgam restoration placement on recurrent caries inhibition.

    Science.gov (United States)

    Donly, K J; Stufflebeam, M; García-Godoy, F

    1998-08-01

    To evaluate the in vitro caries inhibition effects of 1.23% APF foam topical fluoride treatment of cavity preparations, prior to restoration placement and after restoration placement. Sixty standardized Class V preparations were placed in molars. Randomly, 40 teeth received an amalgam restoration: Twenty other teeth had 1cc 1.23% APF foam applied to preparation surfaces for 1 minute, then an amalgam restoration was placed. The APF was not rinsed away prior to restoration, it was displaced by the pressure of the amalgam being condensed into the preparation. Twenty of the initial 40 amalgam restorations had 1 cc 1.23% APF foam applied to the external tooth/restoration margins for 4 minutes, the remaining 20 amalgam restorations acted as the controls. Acid-resistant varnish was placed, leaving 1 mm of tooth adjacent to restoration margins exposed. All specimens were subjected to an artificial caries challenge (pH 4.4) for 5 days. Sections of 100 microns were cut longitudinally through the restored margins, photographed under polarized light microscopy, then demineralized areas adjacent to restoration margins were quantitated. Results demonstrated the mean (+/- S.D.) area (microns 2) of demineralization 100 microns from the restoration margins to be: amalgam 10,221 +/- 524, amalgam with 1-minute APF over preparation 529 +/- 557, amalgam with 4-minute APF over external surface 736 +/- 359. ANOVA and Duncan's (P < 0.05) indicated both 1.23% APF foam topical fluoride treatment regimens exhibited significantly less demineralization at restoration margins than the non-treated amalgam control. There was no significant difference between the two fluoride placement regimens examined in this study.

  11. Prenatal exposure to dental amalgam: evidence from the Seychelles Child Development Study main cohort.

    Science.gov (United States)

    Watson, Gene E; Lynch, Miranda; Myers, Gary J; Shamlaye, Conrad F; Thurston, Sally W; Zareba, Grazyna; Clarkson, Thomas W; Davidson, Philip W

    2011-11-01

    Dental amalgams contain approximately 50 percent metallic mercury and emit mercury vapor during the life of the restoration. Controversy surrounds whether fetal exposure to mercury vapor resulting from maternal dental amalgam restorations has neurodevelopmental consequences. The authors determined maternal amalgam restoration status during gestation (prenatal exposure to mercury vapor [Hg(0)]) retrospectively in 587 mother-child pairs enrolled in the Seychelles Child Development Study, a prospective longitudinal cohort study of the effects of prenatal and recent postnatal methylmercury (MeHg) exposure on neurodevelopment. They examined covariate-adjusted associations between prenatal maternal amalgam restoration status and the results of six age-appropriate neurodevelopmental tests administered at age 66 months. The authors fit the models without and with adjustment for prenatal and recent postnatal MeHg exposure metrics. The mean number of maternal amalgam restorations present during gestation was 5.1 surfaces (range, 1-22) in the 42.4 percent of mothers who had amalgam restorations. The authors found no significant adverse associations between the number of amalgam surfaces present during gestation and any of the six outcomes, with or without adjustment for prenatal and postnatal MeHg exposure. Results of analyses with the secondary metric, prenatal amalgam occlusal point scores, showed an adverse association in boys only on a letter- and word-identification subtest of a frequently used test of scholastic achievement, whereas girls scored better on several other tests with increasing exposure. This study's results provide no support for the hypothesis that prenatal Hg(0) exposure arising from maternal dental amalgam restorations results in neurobehavioral consequences in the child. These findings require confirmation from a prospective study of coexposure to MeHg and Hg(0).

  12. The Copper concentration variation to physical properties of high copper amalgam alloy

    Directory of Open Access Journals (Sweden)

    Aminatun Aminatun

    2006-09-01

    Full Text Available The function of copper (Cu inside amalgam is to increase hardness and impact force and to decrease thermal expansion coefficient. In general, amalgam which is used in dentistry and available in the market is contain Cu 22%, while the maximum Cu concentration is 30%. It is necessary to determine the concentration Cu does generate the best physical properties to be used as dental restorative agent. Amalgam is made by mixing blended-metal Ag-Sn-Cu (with Cu concentration of 13%, 21%, 22%, and 29% and Hg, stirred manually in a bowl for 15 minutes,leave it in temperature 27°C for 24 hours to become hardened. The result of X-Ray Diffractometer (XRD, analyzed by Rietveld method and Rietica program, shows amalgam with Cu 29% concentration for Cu3Sn compound density is 31.790 sma/Å3, for Ag2Hg3 compound is 41.733 sma/ Å3, a Cu3Sn relative weight percentage of 43.23%, Ag2Hg3 of 54.54%, Cu 7Hg6 of 2.23% and hardness of Cu 29% is 90.700 ± 0.005 kgf/mm2. These numbers are the highest values on Cu 29% concentrations compared to other copper concentration variants. Whereas amalgam thermal expansion coefficient on Cu 29% is (2.17 ± 0.9110-3 mm/°C is the lowest value compared to other Cu concentration. The conclution is that adding Cu concentration into amalgam will increase density value, Cu3Sn relative weight percentage, hardness level and will decrease amalgam thermal expansion coefficient. Amalgam 29% Cu concentration has better physical properties compared to amalgam Cu 22% concentration.

  13. Prevalence of cusp fractures in teeth restored with amalgam and with resin-based composite.

    Science.gov (United States)

    Wahl, Michael J; Schmitt, Margaret M; Overton, Donald A; Gordon, M Kathleen

    2004-08-01

    Complete cusp fracture in restored teeth is a common problem observed in general dental practice. Many dentists believe that teeth restored with amalgam are more likely to be associated with cusp fractures than are those restored with resin-based composite. METHODS. The authors noted the condition of 10,869 posterior teeth with amalgam or resin-based composite restorations with at least one cusp present, unrestored or missing in 1,902 consecutively seen adult patients in a private general dental practice. For each patient, the authors recorded age, type of restorations, number of surfaces of each restoration, and presence or absence of a complete cusp fracture and of caries. There was a lower percentage of cusp fractures in younger subjects than in older subjects and in teeth with a single restored surface than in those with more than one restored surface. There was no significant difference in the prevalence of cusp fracture rates in amalgam-restored teeth versus composite-restored teeth in subjects aged 18 through 54 years. In subjects aged 55 through 96 years, there was a marginally significantly greater cusp fracture rate in composite-restored teeth than in those restored with amalgam. Overall, there was no significant difference in the prevalence of cusp fracture in teeth restored with amalgam (1.88 percent) versus composite-restored teeth (2.29 percent). The prevalence of cusp fractures in amalgam-restored teeth and resin-based composite-restored teeth is not significantly different. Teeth with more than one surface restored with either resin-based composite or amalgam and teeth in older subjects were more likely to suffer a cusp fracture. Teeth restored with amalgam and with resin-based composite exhibited equally low cusp fracture prevalence. When choosing between amalgam and resin-based composite in consideration of the likelihood of a future cusp fracture, either restorative material is acceptable.

  14. Toxicological aspects on the release and systemic uptake of mercury from dental amalgam.

    Science.gov (United States)

    Ekstrand, J; Björkman, L; Edlund, C; Sandborgh-Englund, G

    1998-04-01

    This paper summarizes some recent reports on mercury release from amalgam fillings and resulting concentrations in biological fluids, development of antibiotic resistance, and kidney function. In a series of studies of subjects with amalgam fillings, mercury (Hg) levels were followed in saliva, feces, blood, plasma, and urine before and until 60 d after removal of all of the fillings. The Hg concentrations in saliva remained elevated for at least 1 wk, suggesting that dissolved Hg vapor is not the major source of mercury in mixed saliva. An absorption phase of Hg was seen in plasma during 24 h after amalgam removal. After 60 d the plasma Hg concentration was reduced to 40%, of the baseline level. The decrease per amalgam surface was 0.11 nmol/l (range 0.02 0.40). The Hg level in feces increased two orders of magnitude two days after amalgam removal. At day 60, the median Hg concentration was still slightly higher than the median value of the amalgam free control group. The resistance patterns of the oral and intestinal microflora in these subjects were also studied. In the intestinal microflora, the relative amount of intestinal microorganisms resistant to 50 microM HgCl2 peaked 7 d after removal of the amalgam fillings, with a median value per sample of 6.1%, compared to 1.3% in samples collected prior to the Hg exposure. However, no statistical differences in the resistance pattern of the oral microflora were detected between the control and the experimental groups. A number of sensitive kidney function parameters were measured 1 wk before and 1, 2, and 60 d after amalgam removal. No effects on the various kidney parameters studied were recorded. According to the conclusions of independent evaluations from different state health agencies, the release of mercury from dental amalgam does not present any non-acceptable risk to the general population.

  15. Immune Function Effects of Dental Amalgam in Children: A Randomized Clinical Trial

    Science.gov (United States)

    Shenker, Bruce J.; Maserejian, Nancy N.; Zhang, Annie; McKinlay, Sonja

    2010-01-01

    Background Dental amalgam is a widely used restorative material containing 50% elemental mercury that emits mercury vapor. No randomized clinical trials have determined whether there are adverse immunologic effects associated with this low-level mercury exposure in children. The objective of this study was to evaluate a sub-population of the New England Children’s Amalgam Trial (NECAT) for in vitro manifestations of immunotoxic effects of dental amalgam. Methods A randomized clinical trial in which children requiring dental restorative treatment were randomized to either amalgam for posterior restorations or resin composite. A total of 66 children, aged 6–10 years, were assessed for total white cell numbers, T-cell, B-cell, neutrophil and monocyte responsiveness over a five-year period. Owing to the small number of participants, the study is exploratory in nature with limited statistical power. Results The mean number of tooth surfaces restored during the five-year period was 7.8 for the amalgam group and 10.1 for composite group. In the amalgam group there was a slight, but not statistically significant, decline in responsiveness of T-cells and monocytes at 5–7 days post treatment; no differences were consistently observed at 6, 12 or 60 months. Conclusions This study confirms that treatment of children with dental amalgams leads to increased, albeit low level, exposure to mercury. In this exploratory analysis of immune function, amalgam exposure did not cause overt immune deficits, although small transient effects were observed 5–7 days post restoration. Clinical implications These findings suggest that immunotoxic effects of amalgam restorations in children need not be a concern when choosing this restorative dental material. PMID:18978388

  16. Synthesis, crystal structure and DFT studies of a Zinc(II) complex of 1,3-diaminopropane (Dap), [Zn(Dap)(NCS)2][Zn(Dap)(NCS)2]n. The additional stabilizing role of S⋯π chalcogen bond

    Science.gov (United States)

    Alotaibi, Mshari A.; Alharthi, Abdulrahman I.; Zierkiewicz, Wiktor; Akhtar, Muhammad; Tahir, Muhammad Nawaz; Mazhar, Muhammad; Isab, Anvarhusein A.; Ahmad, Saeed

    2017-04-01

    A zinc(II) complex of 1,3-diaminopropane (Dap), [Zn(Dap)(NCS)2][Zn(Dap)(NCS)2]n (1) has been prepared and characterized by elemental analysis, IR, 1H &13C NMR spectroscopy, and its crystal structure was determined by X-ray crystallography. The crystal structure of 1 consists of two types of molecules, a discrete monomer and a polymeric one. In the monomeric unit, the zinc atom is bound to one terminal Dap molecule and to two N-bound thiocyanate ions, while in the polymeric unit, Dap acts as a bridging ligand forming a linear chain. The Zn(II) ions in both assume a slightly distorted tetrahedral geometry. The structures of two systems: the [Zn(Dap)(NCS)2][Zn(Dap)(NCS)2]3 complex as a model of 1 and [Zn(Dap)(NCS)2]4 as a simple polymeric structure were optimized with the B3LYP-D3 method. The DFT results support that the experimentally determined structure (1) is more stable in comparison to a simple polymeric structure, [Zn(Dap)(NCS)2]n (2). The interaction energies (ΔE) for NCS anions obtained by B3LYP-D3 method are about -145 kcal mol-1, while the calculated ΔE values for neutral organic ligands are about twice smaller. The X-ray structure of 1 shows that the complex is stabilized mainly by hydrogen bonds. We also found that weak chalcogen bonds play an additional role in stabilization of compound 1. Some of the intermolecular S⋯N distances are smaller than the sum of the van der Waals radii of the corresponding atoms. To the best of our knowledge, this is the first study that shows the structure where the trivalent sulfur is involved in formation of a S⋯π chalcogen bond. The NBO and NCI analyses confirm the existence of this kind of interactions.

  17. Cu(II)-catalyzed allylic silylation of Morita-Baylis-Hillman alcohols via dual activation of Si-B bond and hydroxyl group.

    Science.gov (United States)

    Xuan, Qing-Qing; Zhong, Neng-Jun; Ren, Chuan-Li; Liu, Li; Wang, Dong; Chen, Yong-Jun; Li, Chao-Jun

    2013-11-01

    The reaction of Morita-Baylis-Hillman (MBH) alcohols with Me2PhSiBpin under the catalysis of Cu(OTf)2/pyridine in methanol has been developed. The direct silylation of allylic alcohols via dual activation of the Si-B bond and the hydroxyl group of the MBH alcohol provides an efficient and convenient method for the synthesis of functionalized allylsilanes.

  18. Investigation of the mechanism of mercury removal from a silver dental amalgam alloy

    Directory of Open Access Journals (Sweden)

    M. DJURDJEVIC

    2004-12-01

    Full Text Available An investigation of silver dental amalgam decomposition and the mercury removal mechanism was performed. The decomposition process was analysed during thermal treatment in the temperature interval from 400 °C to 850 °C and for times from 0.5 to 7.5 h. The chemical compositions of the silver dental amalgam alloy and the treated alloy were tested and microstructure analysis using optical and scanning electron microscopy was carried out. The phases were identified using energy disperse electron probe microanalysis. A mechanism for the mercury removal process from silver dental amalgam alloy is suggested.

  19. A novel method for the preparation of uranium metal, oxide and carbide via electrolytic amalgamation

    International Nuclear Information System (INIS)

    Wang, L.C.; Lee, H.C.; Lee, T.S.; Lai, W.C.; Chang, C.T.

    1978-01-01

    A solid uranium amalgam was prepared electrolytically using a two-compartment cell separated with an ion exchange membrane for the purpose of regulating pH value within a narrowly restricted region of 2 to 3. The mercury cathode was kept at -1.8V vs SCE during electrolysis. The thereby obtained amalgam containing as high as 1.9gm U/ml Hg is easily converted into uranium metal by heating in vacuo above 1300 0 C. Uranium dioxide and uranium monocarbide could be easily obtained at relatively low temperature by reacting the amalgam with water vapor and methane. (author)

  20. Pengaruh Penambahan Paladium Terhadap Perilaku Thermal Amalgam Tembaga Tinggi Tipe Lathe Cut

    OpenAIRE

    Ellyza Herda

    2015-01-01

    Effects of additing 1 percent (w/o) palladium (Pd) on the thermal behavior of a lathe cut type high copper amalgam (13 w/o copper) were studied. The identical alloys, with and without 1% Pd were fabricated. X-ray diffraction studies of the amalgams revealed the elimination of the γ2-phase by Pd addition DSC thermogram of non-Pd containing amalgam indicated the existence of two γ1-phaseone with the transition temperature (endothermic peak) at 88◦C and the other at 109◦C. The thermogram data of...

  1. Functionally generated amalgam stops for single complete denture: A case report

    Directory of Open Access Journals (Sweden)

    Pravinkumar G Patil

    2009-01-01

    Full Text Available Single complete denture opposing natural dentition is a common occurrence in clinical practice. This article reports a case of a single complete denture with a technique of occlusal refinement by func-tionally generated amalgam stops condensed in prepared resin teeth after initial balancing of the den-ture with semi-adjustable articulator. This technique provides intimacy of contact in all excursions by carving the amalgam in plastic stage. Amalgam stops improve the efficiency of the resin teeth. Den-tures fabricated using this technique require fewer and simpler post-insertion adjustments.

  2. Stainless steel crowns versus amalgams in the primary dentition and decision-making in clinical practice.

    Science.gov (United States)

    Mata, Annette F; Bebermeyer, Richard D

    2006-01-01

    This article reviews scientific dental literature related to amalgam restorations versus stainless steel crowns (SSCs) in the primary dentition. An extensive literature search of clinical studies was conducted to address the use of amalgams and SSCs in the primary dentition. The scientific literature provides evidence that SSCs demonstrate greater longevity and reduced need for retreatment, compared to multi-surface amalgam restorations. There is high-level evidence for the use of SSCs because of their cost-effectiveness, ease of placement, and longevity.

  3. Long-term survival of repaired amalgams, recemented crowns and gold castings.

    Science.gov (United States)

    Smales, Roger J; Hawthorne, Warwick S

    2004-01-01

    This retrospective longitudinal study compared the long-term survival rate of repaired versus replaced amalgam restorations and recemented crowns and gold castings versus non-recemented similar restorations. Private general dental practitioners treated adult subjects at three city practices. No significant survival differences were found between the repaired and replaced amalgams at five years, although the repaired amalgams showed higher failure rates by 10 years (p=0.37). However, there were significantly higher failures by five years for recemented crowns (pamalgams had survival rates of approximately 37 +/- 15 (SEr) percent, recemented crowns 28 +/- 15 (SEr) percent and recemented gold castings 42 +/- 17 (SEr) percent.

  4. Process Optimization for Valuable Metal Recovery from Dental Amalgam Residues

    Directory of Open Access Journals (Sweden)

    C.M. Parra–Mesa

    2009-07-01

    Full Text Available In this paper, the methodology used for optimizing leaching in a semi pilot plant is presented. This leaching process was applied to recover value metals from dental amalgam residues. 23 factorial design was used to characterize the process during the first stage and in the second one, a central compound rotational design was used for modeling copper percentage dissolved, a function of the nitric acid concentration, leaching time and temperature. This model explained the 81% of the response variability, which is considered satisfactory given the complexity of the process kinetics and, furthermore, it allowed the definition of the operation conditions for better copper recovery, which this was of 99.15%, at a temperature of 55°C, a concentration of 30% by weight and a time of 26 hours.

  5. Positive patch test for mercury possibly from exposure to amalgam.

    Science.gov (United States)

    Mori, Tomio; Sato, Kazuhiro; Kusaka, Yukinori; Ido, Toshiko; Kumagiri, Masanobu; Ogasawara, Toshiyuki; Sano, Kazuo

    2007-07-01

    Mercury allergy is a serious health problem. We investigated the relationship between positive patch test for mercury and sources of mercury exposure, indicated by concentrations in biological samples from healthy medical students. Patch tests for mercury (Hg-PT) were performed on 580 students. For a group of 55 students with a positive Hg-PT result (Hg-PT(+)) and a reference group of 79 students with a negative Hg-PT result (Hg-PT)(-)), mercury concentrations in urine (Hg-u) and hair (Hg-h) were measured. In our search for environmental indicators of mercury exposure, the level of fish intake and mercurochrome usage were determined using a self-administered questionnaire. The oral cavity was investigated and the numbers of decayed teeth filled with amalgam (NA) were counted by dentists. For the male Hg-PT(+) group, Hg-u and Hg-h were higher than those of a male reference Hg-PT(-) group; Hg-u values obtained in the early morning and after supper were significantly different. Multiple regression analysis with Hg-u as the objective variable among all students showed that increases in the level of fish intake, mercurochrome usage, and the NA independently increased Hg-u measured in the early morning for both gender groups. NA significantly affected Hg-u. We showed that a higher NA was related to a higher Hg-u measured in the early morning. Therefore, exposure to amalgam may increase Hg-u. It was suggested that Hg-PT(+) might be related to a high Hg-u, and possibly to a high NA.

  6. Diffusion bonding

    International Nuclear Information System (INIS)

    Anderson, R.C.

    1976-01-01

    A method is described for joining beryllium to beryllium by diffusion bonding. At least one surface portion of at least two beryllium pieces is coated with nickel. A coated surface portion is positioned in a contiguous relationship with another surface portion and subjected to an environment having an atmosphere at a pressure lower than ambient pressure. A force is applied on the beryllium pieces for causing the contiguous surface portions to abut against each other. The contiguous surface portions are heated to a maximum temperature less than the melting temperature of the beryllium, and the applied force is decreased while increasing the temperature after attaining a temperature substantially above room temperature. A portion of the applied force is maintained at a temperature corresponding to about maximum temperature for a duration sufficient to effect the diffusion bond between the contiguous surface portions

  7. Effect of surface treatment on marginal integrity of amalgam restorations (in vitro study).

    Science.gov (United States)

    Kamel, F M

    1995-07-01

    A total of 80 freshly extracted human molars, free from caries, cracks & decalcifications, were used in this study. Conservative class I cavities were prepared in the occlusal surface. Two types of amalgam alloys were used, high copper (Dispersalloy) & conventional (Velvalloy). The prepared cavities were classified into 5 groups, 16 each carve (C), carve & polish (CP), precarve burnish (BC), past-carve (CB) & pre post carve burnish (BCB). The specimens were thermally stressed using the stress fatigue device. The marginal integrity of the amalgam enamel interface were evaluated using SEM, for the four marginal quantities: 1--excellent margin, 2--open margins, 3--enamel fracture, and 4--amalgam fracture. The results of this study revealed that higher copper amalgam demonstrated superior marginal integrity than the conventional one. The pre-post carve burnish group showed the highest percentage of excellent margin than the other groups.

  8. Cracked mercury dental amalgam as a possible cause of fever of unknown origin: a case report

    Directory of Open Access Journals (Sweden)

    Bamonti Fabrizia

    2008-03-01

    Full Text Available Abstract Introduction Sudden fever of unknown origin is quite a common emergency and may lead to hospitalization. A rise in body temperature can be caused by infectious diseases and by other types of medical condition. This case report is of a woman who had fever at night for several days and other clinical signs which were likely related to cracked dental mercury amalgam. Case presentation A healthy women developed fever many days after had cracked a mercury dental amalgam filling. Blood tests evidenced increased erythrocyte sedimentation rate, anemia and elevated white cell count; symptoms were headache and palpitations. Blood tests and symptoms normalized within three weeks of removal of the dental amalgam. Conclusion This case highlights the possible link between mercury vapor exposure from cracked dental amalgam and early activation of the immune system leading to fever of unknown origin.

  9. New science challenges old notion that mercury dental amalgam is safe.

    Science.gov (United States)

    Homme, Kristin G; Kern, Janet K; Haley, Boyd E; Geier, David A; King, Paul G; Sykes, Lisa K; Geier, Mark R

    2014-02-01

    Mercury dental amalgam has a long history of ostensibly safe use despite its continuous release of mercury vapor. Two key studies known as the Children's Amalgam Trials are widely cited as evidence of safety. However, four recent reanalyses of one of these trials now suggest harm, particularly to boys with common genetic variants. These and other studies suggest that susceptibility to mercury toxicity differs among individuals based on multiple genes, not all of which have been identified. These studies further suggest that the levels of exposure to mercury vapor from dental amalgams may be unsafe for certain subpopulations. Moreover, a simple comparison of typical exposures versus regulatory safety standards suggests that many people receive unsafe exposures. Chronic mercury toxicity is especially insidious because symptoms are variable and nonspecific, diagnostic tests are often misunderstood, and treatments are speculative at best. Throughout the world, efforts are underway to phase down or eliminate the use of mercury dental amalgam.

  10. [Management of wastes from dental amalgam by dentists in Burkina Faso and Morocco].

    Science.gov (United States)

    Chala, S; Sawadogo, A; Sakout, M; Abdallaoui, F

    2012-12-01

    Dental amalgam is a metallic restorative material that is used for direct filling of carious lesions since many years. The use of this material generates solid and particulate wastes that present potential challenges to the environment. This study was carried out to assess amalgam use and waste management protocols practiced by Moroccan and Burkinabe dentists. A cross-sectional study was made of 79 in Rabat, Sale and Temara in Morocco and 56 in Ouagadougou, Bobo-Dioulasso in Burkina-Faso. The results showed that 69.5% of dental amalgam waste in Morocco vs 49.9% in Burkina-Faso was disposed with household waste which is a problem for both the environment and a risk to human being. Proper methods of dental amalgam waste disposal should be carried out to prevent indirect mercury poisoning for human.

  11. Esthetic use of a free gingival autograft to cover an amalgam tattoo: report of case.

    Science.gov (United States)

    Dello Russo, N M

    1981-03-01

    Amalgam tattooing of the labial gingiva in the maxillary anterior region can be extremely disfiguring to a patient with a high lip line. A case is described in which a palatal gingival autograft was performed.

  12. Treatment of amalgam tattoo with a subepithelial connective tissue graft and acellular dermal matrix.

    Science.gov (United States)

    Thumbigere-Math, Vivek; Johnson, Deborah K

    2014-04-01

    A 54-year-old female was referred for management of a large amalgam tattoo involving the alveolar mucosa between teeth #6 and #9. The lesion had been present for over 20 years following endodontic treatment of teeth #7 and #8. A two-stage surgical approach was used to remove the pigmentation, beginning with removal of amalgam fragments from the underlying bone and placement of a subepithelial connective tissue graft and acellular dermal matrix to increase soft tissue thickness subadjacent to the amalgam. Following 7 weeks of healing, gingivoplasty was performed to remove the overlying pigmented tissue. At the 21-month follow-up appointment, the patient exhibited naturally appearing soft tissue with no evidence of amalgam tattoo.

  13. Removal of an amalgam tattoo using a subepithelial connective tissue graft and laser deepithelialization.

    Science.gov (United States)

    Campbell, Casey M; Deas, David E

    2009-05-01

    A 56-year-old female presented for periodontal treatment with a large amalgam tattoo located in alveolar mucosa on the facial aspect of her maxillary central incisors. The lesion had been present for 42 years since having endodontic surgery at teeth #8 and #9 after a traumatic childhood incident. A two-stage surgical approach was used to eliminate the lesion, beginning with a subepithelial connective tissue graft to increase tissue thickness subjacent to the amalgam tattoo. After 6 weeks of healing, the overlying pigmented tissue was removed using laser surgery to expose the underlying grafted connective tissue. After 2 months of healing following laser surgery, the amalgam pigmentation was completely removed, with good color match and an increased width of keratinized tissue at the surgical site. A relatively large amalgam tattoo in the esthetic zone can be adequately removed by a two-stage procedure using grafted palatal connective tissue and laser deepithelialization.

  14. Treatment of an amalgam tattoo with a Q-switched alexandrite (755 nm) laser.

    Science.gov (United States)

    Shah, Geeta; Alster, Tina S

    2002-12-01

    Amalgam tattoos result from deposition of metallic particles (eg, silver, mercury, copper, zinc, and tin) into the oral mucosa. Their clinical and histologic appearance is similar to that of decorative tattoos. To describe the successful use of a Q-switched alexandrite laser for removal of an amalgam tattoo. An amalgam tattoo on the buccal mucosa and gingiva was treated with a QS 755 nm alexandrite laser. Three treatments were delivered at 8-week time intervals (average fluence = 6.8 J/cm2). Significant lightening of the tattoo was achieved after each of the three treatments without adverse sequelae. Q-switched alexandrite laser irradiation can safely and effectively eradicate amalgam tattoos.

  15. Direct composite resin fillings versus amalgam fillings for permanent or adult posterior teeth.

    Science.gov (United States)

    Rasines Alcaraz, M Graciela; Veitz-Keenan, Analia; Sahrmann, Philipp; Schmidlin, Patrick Roger; Davis, Dell; Iheozor-Ejiofor, Zipporah

    2014-03-31

    Amalgam has been the traditional material for filling cavities in posterior teeth for the last 150 years and, due to its effectiveness and cost, amalgam is still the restorative material of choice in certain parts of the world. In recent times, however, there have been concerns over the use of amalgam restorations (fillings), relating to the mercury release in the body and the environmental impact following its disposal. Resin composites have become an esthetic alternative to amalgam restorations and there has been a remarkable improvement of its mechanical properties to restore posterior teeth.There is need to review new evidence comparing the effectiveness of both restorations. To examine the effects of direct composite resin fillings versus amalgam fillings for permanent posterior teeth, primarily on restoration failure. We searched the Cochrane Oral Health Group's Trials Register (to 22 October 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 9), MEDLINE via OVID (1946 to 22 October 2013), EMBASE via OVID (1980 to 22 October 2013), and LILACs via BIREME Virtual Health Library (1980 to 22 October 2013). We applied no restrictions on language or date of publication when searching the electronic databases. We contacted manufacturers of dental materials to obtain any unpublished studies. Randomized controlled trials comparing dental resin composites with dental amalgams in permanent posterior teeth. We excluded studies having a follow-up period of less than three years. We used standard methodological procedures expected by The Cochrane Collaboration. Of the 2205 retrieved references, we included seven trials (10 articles) in the systematic review. Two trials were parallel group studies involving 1645 composite restorations and 1365 amalgam restorations (921 children) in the analysis. The other five trials were split-mouth studies involving 1620 composite restorations and 570 amalgam restorations in an unclear

  16. Daya Antibakteri Bahan Tumpat Amalgam dan Resin Komposit Berfluor Terhadap Bakteri Streptococcus Mutans Serotipe KPSK2

    Directory of Open Access Journals (Sweden)

    Dewa Ayu Nyoman Putri Artiningsih

    2015-09-01

    Full Text Available This research was carried out to study the difference in the antibacterial capacity of two kinds of filling materials, namely amalgam and composite resin, on S. mutans KPSK2 bacteria with different times of treatment. In total, 48 amalgam and composite resin samples each were prepared and then divided into four groups of treatment. Of each group, 6 samples were used to count the number of bacterial colonies and 6 samples to count the right obstacle zone. The results show that the best antibacterial capacity of composite resin occurred within one week, while for amalgam the best performance appears within one day. The antibacterial capacity of fluorine containing composites is stronger than that of amalgam for a time of 1 to 2 weeks.

  17. Managing the phase-down of amalgam: Part I. Educational and training issues.

    Science.gov (United States)

    Lynch, C D; Wilson, N H F

    2013-08-01

    Following the recently agreed Minamata Convention, a phase-down in the use of dental amalgam will become a priority for the profession. With a lead-in period of a number of years, important changes in the mind-set of the profession are required to ensure that patient safety is not compromised. Posterior composites have been a viable, and in many cases preferable, alternative to amalgam for many years. However, notwithstanding considerable developments in dental school teaching on the application and placement of posterior composites, growing evidence to support the use of composites in the restoration of posterior teeth and advances in composite systems, many practitioners remain reluctant to place composite rather than amalgam. This paper considers the present and future use of posterior composites and highlights ways in which dental school teaching and continuing professional development (CPD) may contribute to the successful phase-down, and now inevitable discontinuation, in the use of dental amalgam.

  18. [The effect of pH on anti-corrosion nature of amalgams].

    Science.gov (United States)

    Chen, W; Wang, G; Li, W

    1997-09-01

    Corrosion behavior of alloys are affected not only by themselves but also by environment, such as a change of pH. In this study, the corrosion behavior of four dental amalgams (L, C, DA, GK) in Fusayama saliva with different pH 6.65 and 4.00 are evaluated by electrochemical techniques. It seems that changes in pH may exert different effects on the four amalgams. In the acid environment DA exhibits best anti-corrosion nature and followed by GK, C, and L, which conforms to clinical observations. This may be resulted either from amalgams themselves or from conditions of corrosion products of amalgams' surface. Thus, consideration must be given to the changing oral environment when screening anti-corrosion alloys.

  19. High Tensile Strength Amalgams for In-Space Fabrication and Repair

    Science.gov (United States)

    Grugel, Richard N.

    2006-01-01

    Amalgams are well known for their use in dental practice as a tooth filling material. They have a number of useful attributes that include room temperature fabrication, corrosion resistance, dimensional stability, and very good compressive strength. These properties well serve dental needs but, unfortunately, amalgams have extremely poor tensile strength, a feature that severely limits other potential applications. Improved material properties (strength and temperature) of amalgams may have application to the freeform fabrication of repairs or parts that might be necessary during an extended space mission. Advantages would include, but are not limited to: the ability to produce complex parts, a minimum number of processing steps, minimum crew interaction, high yield - minimum wasted material, reduced gravity compatibility, minimum final finishing, safety, and minimum power consumption. The work presented here shows how the properties of amalgams can be improved by changing particle geometries in conjunction with novel engineering metals.

  20. Evaluation of corrosion degradation of amalgams by immersion and fracture test.

    Science.gov (United States)

    Horasawa, Noriko; Takahashi, Shigeo; Marek, Miroslav

    2003-12-01

    In this study an immersion and fracture test was used to evaluate the susceptibility of dental amalgams to degradation of their mechanical strength by corrosion. Specimens of each of the six types of high-copper amalgams and one type of low-copper amalgam were prepared and tested. Cylindrical specimens were grooved using a diamond cutoff blade and immersed in 1% NaCl to which H2O2 was added to increase the oxidation power. After two weeks of exposure the specimens and controls were fractured and the loss of strength was calculated. Two amalgams showed a significant loss of strength. The test procedure is relatively simple and does not require sophisticated electrochemical or analytical instrumentation. A higher resolution power might be achieved by increasing the severity of corrosion or the number of replicate tests.