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Sample records for bonded amalgam restorations

  1. Amalgam Restorations: To Bond or Not.

    PubMed

    Larson, Thomas D

    2015-01-01

    This article will review the use of various liners used to eliminate microleakage in amalgam restorations. It will review the literature about whether amalgam restorations are improved by using a bonding process and if so specifically how it improves the patient outcome.

  2. Cusp reinforcement by bonding of amalgam restorations.

    PubMed

    Pilo, R; Brosh, T; Chweidan, H

    1998-01-01

    The purpose of the present study was to assess the effectivenes of several adhesives in bonding amalgam in order to recover tooth stiffness. A non-destructive experimental methodology was adopted, using strain gauges bonded to the midbuccal surfaces of 40 teeth, with sequential evaluation of loaded intact, prepared and restored stages of the same tooth. Continuous strain measurement as a function of the applied load was acquired by A/D equipment and a data acquisition programme. The strain-force behaviour of the sound teeth under non-axial force up to 97.5 N served as the baseline. The five experimental groups (8 x 5) consisted of control (no adhesive) and four different adhesives. One-way analysis of variance with repeated measures was calculated for the deformation ratio, relative stiffness and recovery values. Reductions in tooth structure by cutting a mesio-occlusal-distal preparation, width one-third intercuspal distance, resulted in 39-52% loss of buccal cusp stiffness. Non-bonded amalgam produced negligible increase (5%) in the stiffness recovery values of the buccal cusps. The adhesives splinted the cusps together, thereby decreasing cuspal flexure and increasing relative stiffness values. Recovery values obtained ranged from 39% to 61%. Assuming that cusp fracture occurs as a result of brittle tooth structure fatigue, amalgam adhesives may contribute to the strengthening of weakened cusps.

  3. Bond strength of repaired amalgam restorations.

    PubMed

    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. Effect of restoration size on fracture resistance of bonded amalgam restorations.

    PubMed

    Lindemuth, J S; Hagge, M S; Broome, J S

    2000-01-01

    The purpose of this study was to determine the effect of restoration size on the fracture strength of amalgam restorations bonded with Amalgambond Plus (with HPA). Research has shown that this adhesive is dispersed throughout the unset amalgam during condensation and that a decrease in diametral tensile strength, proportional to the amount of adhesive incorporated into the unset amalgam, has resulted. Smaller cavity preparations have a higher ratio of surface area to volume than do larger preparations, and it was anticipated that a proportionately greater amount of adhesive would be incorporated into smaller amalgam restorations. Sixty extracted human molars were divided into four groups of 15 teeth and mounted in tray acrylic-filled PVC cylinders. Shallow approximo-occlusal channels were prepared in two groups. One group was restored with Amalgambond Plus and Tytin amalgam, the other with just Tytin amalgam. Larger proximo-occlusal preparations were made in the remaining two groups, then restored in the same fashion. Samples were stored in 37 degrees C for at least 24 hours, then thermocycled from 5-55 degrees C 1000 times with a one-minute dwell time. Specimens were mounted in a Universal Testing Machine, and a chisel was applied to the restorations in compression mode at a crosshead speed of 5.0 mm/minute until bulk fracture of the amalgam occurred. The results indicated no difference in bulk fracture strengths between large amalgam restorations restored with and without Amalgambond Plus. However, small amalgam restorations restored with Amalgambond Plus exhibited significantly greater (p < 0.025) bulk fracture strengths than small amalgam restorations restored without use of the adhesive.

  5. Fracture resistance of teeth restored with the bonded amalgam technique.

    PubMed

    Dias de Souza, G M; Pereira, G D; Dias, C T; Paulillo, L A

    2001-01-01

    This study evaluated the fracture resistance of maxillary premolars with MOD Class II cavity preparations restored with silver amalgam (G1), Scotchbond Multi Purpose Plus and silver amalgam (G2) and Panavia F and silver amalgam (G3). After the restorations were made, the specimens were stored at 37 degrees C for 24 hours at 100% humidity and submitted to the compression test. Statistical analysis of the data (ANOVA and Tukey Test) revealed no significant differences among the three groups that were studied.

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

    PubMed Central

    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 < 0.05). Conclusions: Within the limitation of this study, both resin 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. PMID:27011734

  7. Bonded amalgam restorations: using a glass-ionomer as an adhesive liner.

    PubMed

    Chen, R S; Liu, C C; Cheng, M R; Lin, C P

    2000-01-01

    Due to the lack of adhesiveness of amalgam to tooth structure, several adhesive cements have been utilized in bonded amalgam restorations. This study evaluated whether Fuji-II glass-ionomer cement is an appropriate adhesive liner in bonded amalgam restorations. Two adhesive composite luting cements (Amalgambond Plus and Panavia-21) and Copalite cavity liner were compared. The study was conducted in two phases. In the first part, we quantitatively assessed the tensile bond strengths as well as the failure modes of amalgam bonded to human dentin, using different adhesive liners. In each group, the flat dentin surface was treated with the assigned adhesive cement with a Teflon mold, followed by condensation of amalgam (Valiant PhD) onto it. Each group's mean tensile bond strengths were recorded and the statistical analysis by one way ANOVA showed no significant differences among groups (p > 0.05). Similar to the fracture patterns of the Amalgambond Plus and Panavia-21 groups, the failure mode of Fuji-II group was predominantly adhesive fracture. In the second part, the fracture strengths of amalgam restored teeth were measured using different adhesive liners. Standard MOD cavities were prepared in each tooth except for the intact tooth group. After treatment with the assigned adhesives or varnish, the cavities were restored with amalgam. Fracture strengths were then measured and the fractured interfaces examined using a scanning electron microscope. The fracture strengths of the intact tooth, Amalgambond Plus, Panavia-21 and Fuji-II groups were significantly higher than those of the Copalite and prepared cavity without restoration groups (p < 0.01). Accordingly, Fuji-II glass-ionomer cement, when used as an adhesive liner of amalgam restoration, may effectively reinforce the remaining tooth structure and, therefore, enhance the fracture resistance of the amalgam-restored teeth.

  8. Microleakage in conventional and bonded amalgam restorations: influence of cavity volume.

    PubMed

    da Silva, Adriana Fernandes; Piva, Evandro; Demarco, Flávio Fernando; Correr Sobrinho, Lourenço; Osinga, Prudêncio Willy Rodo

    2006-01-01

    This study verified the relationship between the volume and microleakage of conventional and bonded amalgam restorations. Also, the microleakage influence of intermediate materials, substrates and the direction of sectioning was investigated. Fifty-six bovine incisors were selected. Standard Class V cavities were prepared in buccal and lingual surfaces. For each tooth, two cavity sizes were prepared, corresponding to two cavity volumes: one larger (A) and the other smaller (B). The cervical wall was located in cementum/dentin and the incisal wall in enamel. The teeth were distributed in four groups (n=28) according to the intermediate material employed (glass-ionomer cement, resin cement, adhesive system and copal varnish-control). The materials were applied following manufacturers' directions. After restoration, the teeth were submitted to thermal cycling. They were then immersed in a dye solution and sectioned in two directions inciso-cervical (IC) and mesio-distal (MD) sections to evaluate the microleakage. Data were subjected to non-parametric statistical analysis (Wilcoxon's paired test and Kruskal-Wallis test). No significant difference was found between the two cavity sizes. Leakage in enamel was statistically lower than in the cementum/dentin interface (p < 0.05). In some situations, glass-ionomer or resin cement lined amalgam restorations presented less dye leakage than copal varnish lined restorations (p < 0.05). No significant difference was observed in microleakage between IC or MD sectioning. Within the limitations of this study, it was concluded that cavity size and direction of section were not significant factors for microleakage, while substrate and intermediate materials had a significant effect on the sealing ability in amalgam restorations.

  9. Evaluation of dental adhesive systems with amalgam and resin composite restorations: comparison of microleakage and bond strength results.

    PubMed

    Neme, A L; Evans, D B; Maxson, B B

    2000-01-01

    A variety of laboratory tests have been developed to assist in predicting the clinical performance of dental restorative materials. Additionally, more than one methodology is in use for many types of tests performed in vitro. This project assessed and compared results derived from two specific laboratory testing methods, one for bond strength and one for microleakage. Seven multi-purpose dental adhesives were tested with the two methodologies in both amalgam and resin composite restorations. Bond strength was determined with a punch-out method in sections of human molar dentin. Microleakage was analyzed with a digital imaging system (Image-Pro Plus, Version 1.3) to determine the extent of dye penetration in Class V preparations centered at the CEJ on both the buccal and lingual surfaces of human molar teeth. There were 32 treatment groups (n = 10); seven experimental (dental adhesives) and one control (copal varnish, 37% phosphoric acid) followed by restoration with either amalgam or resin composite. Specimens were thermocycled 500 times in 5 degrees and 55 degrees C water with a one-minute dwell time. Bond strength and microleakage values were determined for each group. ANOVA and Student-Newman-Keuls tests demonstrated an interaction between restorative material and adhesive system with a significant difference among adhesives (p < 0.05). Using a multi-purpose adhesive system resulted in both a statistically significant increase in bond strength and a statistically significant decrease in extent of microleakage (p < 0.05). The effect of the adhesive upon both microleakage and bond strength was greater in the resin composite restorations than in the amalgam restorations. Bond strength testing was more discriminating than microleakage evaluation in identifying differences among materials.

  10. Composite veneering of complex amalgam restorations.

    PubMed

    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.

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

    DTIC Science & Technology

    1991-01-01

    their assistance with the illustrations and photographs used in this thesis. To my Air Force colleagues, Dr. Charles B. Hermesch and Dr. David F...Brannstrom M. Dentin and pulp in restorative dentistry. Castelnuovo: Wolfe Medical Publication, 1982:70. 16. Wing G, Lyell JS. The marginal seal of amalgam...like lesions in vitro: the effect of fluoride cavity liner and cavity varnish. Br Dent J 1973;134:530-6. 76. Barber D, Lyell J, Massler M. Effectiveness

  12. Evaluation of various concentrations of alkaline surface treatment on interfacial bond strengths of amalgam bonded to amalgam.

    PubMed

    Mirza, Asaad Javaid; Ahmad, Asif; Mohammad, Taqi; Khan, Zahid Akhter

    2013-09-01

    This study was done to assess the influence of alkaline surface modification on interfacial bond strength of existing fractured (old) amalgam restoration bonded to fresh amalgam. Old and Fresh amalgam interfaced samples were prepared by applying a 4-methacryloyloxyethy trimellitate anhydride (4-META) containing adhesive. The adhesive used was Amalgabond (Parkell, Farmingdale, NY 11735, USA). Four concentrations of calcium hydroxide Ca(OH)2 solutions were used as a surface modifiers for old amalgam to increase the pH of the amalgam surfaces. The concentrations used were 2.5, 5, 10 and 15%. Direct measurement of the interfacial bond strength was carried out using an electromechanical universal tensile testing machine at crosshead speed of 10mm per minute. Results show that all the calcium hydroxide modified samples produced the increased tensile bond strength (TBS) as compared to their control group. The highest values of bond strength were achieved using 15% Ca(OH)2 solution as surface modifier. Pretreatment of fractured amalgam with calcium hydroxide improves the bond strength of 4-META adhesives. Its use in repair of amalgam may therefore be considered.

  13. Proximal Contact Repair of Complex Amalgam Restorations.

    PubMed

    Zguri, M N; Casey, J A; Jessup, J P; Vandewalle, K S

    2017-01-12

    The carving of a complex amalgam restoration may occasionally result in light proximal contact with the adjacent tooth. The purpose of this study was to investigate the strength of complex amalgam restorations repaired with a proximal slot amalgam preparation. Extracted human third molars of similar coronal size were sectioned 1 mm apical to the height of the contour using a saw and were randomly distributed into 9 groups of 10 teeth each. One pin was placed at each line angle of the flattened dentinal tooth surface. A metal matrix band was placed and an admixed alloy was condensed and carved to create a full crown contour but with a flat occlusal surface. A proximal slot was prepared with or without a retention groove and repaired using a single-composition spherical amalgam 15 minutes, 24 hours, one week, or six months after the initial crown condensation. The specimens were stored for 24 hours in 37°C water before fracture at the marginal ridge using a round-ended blade in a universal testing machine. The control group was not repaired. The mean maximum force in newtons and standard deviation were determined per group. Data were analyzed with a 2-way analysis of variance as well as Tukey and Dunnett tests (α=0.05). Significant differences were found between groups based on type of slot preparation (p=0.017) but not on time (p=0.327), with no significant interaction (p=0.152). No significant difference in the strength of the marginal ridge was found between any repair group and the unrepaired control group (p>0.076). The proximal repair strength of a complex amalgam restoration was not significantly different from an unrepaired amalgam crown. Placing a retention groove in the proximal slot preparation resulted in significantly greater fracture strength than a slot with no retention grooves. Time of repair had no significant effect on the strength of the repair.

  14. Improving orthodontic bonding to silver amalgam.

    PubMed

    Zachrisson, B U; Büyükyilmaz, T; Zachrisson, Y O

    1995-01-01

    Flat rectangular tabs (n = 84) prepared from lathe-cut amalgam (ANA 2000) were subjected to aluminum oxide sandblasting or roughening with a diamond bur. Mandibular incisor edgewise brackets were bonded to these tabs using: Concise (Bis-GMA resin); one of three metal-bonding adhesives, viz., Superbond C&B (4-META resin), Panavia Ex (10-MDP Bis-GMA resin) or Geristore (composite base); and Concise after application of the intermediate resins All-Bond 2 Primers A+B, or the Scotch-Bond Multi-Purpose (SBMP) system. All specimens were stored in water at 37 degrees C for 24 hours before tensile bond strength testing. Alignment and uniform loading during testing were secured by engaging a hook in a circular ring soldered onto the bracket slot before bonding. Similar control brackets (n = 12) were bonded with Concise to extracted caries-free mandibular incisors. Bond failure sites were classified by a modified ARI system. Mean tensile bond strengths in the experimental group ranged from 3.4 to 6.4 MPa--significantly weaker than the control sample (13.2 MPa). Bond failure generally occurred at the amalgam/adhesive interface. Superbond C&B created the strongest bonds to amalgam; according to ANOVA and Duncan's Multiple-Range test, they were significantly stronger than the bonds with Panavia Ex and Concise, with Geristore in between. However, the bond strength of Concise to sandblasted amalgam was comparable to the Superbond C&B bonds when coupled with an intermediate application of All-Bond 2 Primers A+B. The SBMP, on the other hand, was less effective.(ABSTRACT TRUNCATED AT 250 WORDS)

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

    PubMed

    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), except for A+C (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).

  16. Comparison of shear bond strength of amalgam bonded to primary and permanent dentin.

    PubMed

    Mahdi, S; Bahman, S; Arghavan, A B; Fatemeh, M

    2008-06-01

    Amalgam's non-adhesive characteristics necessitate cavity preparations incorporating retentive features, which often require the removal of non-carious tooth structure. Use of adhesives beneath amalgam restorations, would be helpful to overcome this disadvantage. This study was undertaken to compare the mean shear bond strength of amalgam bonded to primary and permanent dentin, to evaluate the efficacy of amalgam adhesives in pediatric dentistry.27 primary and 28 permanent posterior teeth with intact buccal or lingual surfaces were grounded to expose dentin and wet-polished with 400-grit silicone carbide paper. Scotchbond Multi Purpose Plus adhesive system was applied to the dentin surfaces and light cured. Amalgam was condensed onto the treated dentin through a plastic mold.shear bond strength testing was done using an Instron Universal testing machine, at a crosshead speed of 0.5 mm/min.The data were analyzed by independent samples t-test The difference among the two groups was not statistically significant (p>0.05) Bonded amalgam showed the same level of bond strength to primary and permanent dentin; so, application of amalgam bonding agents in pediatric dentistry can be recommended.

  17. Shear bond strength of brackets bonded to amalgam with different intermediate resins and adhesives.

    PubMed

    Germec, Derya; Cakan, Umut; Ozdemir, Fulya Isik; Arun, Tulin; Cakan, Murat

    2009-04-01

    The aims of this study were to compare, in vitro, the shear bond strength (SBS) of stainless steel orthodontic brackets bonded to silver amalgam with the use of three different intermediate resins and two different adhesives, and to evaluate bond failure mode. Forty-five amalgam specimens were divided into three equal groups. In groups 1 and 2, the brackets were bonded with Unite (3M Unitek) using Reliance Metal Primer (RMP; Reliance Orthodontic Products) and Power Bond OLC (PB OLC; Ortho Organizers Inc.) as intermediate resins, respectively. In group 3, Resinomer and One-Step Plus (OS+; Bisco Inc.) were used. Thirty bovine teeth served as the controls to test bracket bonding to acid-etched enamel with Unite and Resinomer-OS+. After thermocycling from 10 to 50 degrees C 1000 times, all samples were tested for SBS. Bond failure sites were classified using a modified adhesive remnant index (ARI) system. Data were analyzed with one-way analysis of variance, post hoc Tukey multiple comparison and chi-square tests. The results showed that the mean SBS to amalgam surfaces were significantly lower than those to etched bovine enamel (P<0.001). There were no statistically significant differences in mean SBS between the amalgam bonding groups (P>0.05). For the ARI, significant differences were found between the amalgam- and enamel-bonding groups (P<0.001). The mean SBS of stainless steel orthodontic brackets bonded to amalgam surfaces with RMP, PB OLC, OS+ intermediate resins and Unite and Resinomer adhesives was significantly lower than to etched bovine enamel. Bond failure occurred at the amalgam-adhesive interface regardless of the adhesive system and without damage to the amalgam restoration.

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

    PubMed

    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.

  19. 12-year survival of composite vs. amalgam restorations.

    PubMed

    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.

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

    PubMed Central

    Firouzmandi, Maryam; Doozandeh, Maryam; 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 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 P<0.05. Fracture mode of the specimens was also recorded. Results G1 had the highest value of fracture resistance (1736.90 N). G2 and G3 had the lowest fracture resistance (775.70 N and 874.70 N, respectively). The difference between G 4, 5 and 6 was not statistically significant. However, G4, G5 and G6 showed significantly higher resistance to fracture compared to G2 and G3. Fracture modes were favorable in all of the study groups except in G6. Conclusions Fracture resistance of the premolars restored with the two variations of combined amalgam-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

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

    PubMed

    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.

  2. Secondary caries formation in vitro around glass ionomer-lined amalgam and composite restorations.

    PubMed

    Dionysopoulos, P; Kotsanos, N; Papadogianis, Y

    1996-08-01

    The aim of this in vitro secondary caries study was to examine the glass-ionomer liner's effect on wall-lesion inhibition when a conventional and a light-cured glass ionomer liner was placed under amalgam and composite resin restorations. Class V preparations in extracted upper premolars were used and ten restorations were used for each of the following groups: (i) two layers of copal varnish and amalgam; (ii) conventional glass-ionomer and amalgam; (iii) light-cured glass-ionomer and amalgam; (iv) bonding agent and light-cured composite resin; (v) conventional glass-ionomer, bonding agent and light-cured composite resin; (vi) light-cured glass-ionomer, extended 0.3 mm short of the enamel margin bonding agent and light-cured composite resin; and (vii) light-cured glass-ionomer, extended 1 mm short of the enamel margin, bonding agent and light-cured composite resin. The teeth were thermocycled and artificial caries were created using an acid-gel. The results of this study showed that artificial recurrent caries can be reduced significantly (P < 0.05) with a glass-ionomer liner under amalgam restorations. The results also showed that when the light-cured glass-ionomer liner was placed 0.3 mm from the cavosurface margin under composite resin restoration, the artificial recurrent caries reduced significantly (P < 0.05).

  3. Determination of light elements in amalgam restorations. [Dental amalgam

    SciTech Connect

    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. Bond strength of resin composite to differently conditioned amalgam.

    PubMed

    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

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

    PubMed

    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

  6. A systematic technique for carving amalgam and composite restorations.

    PubMed

    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.

  7. Bonding of adhesive resin luting agents to metal and amalgam.

    PubMed

    Osman, Saad A; McCabe, John F; Walls, Angus W G

    2008-12-01

    The shear bond strength of three adhesives, Panavia 21, Superbond, All Bond C&B Cement, and a dual cure resin (Variolink), to Ni-Cr-Be (Rexillium III), Midigold (Type III gold) and Amalgam (Sybraloy) were determined. Fifteen samples were prepared using 800 grit abrasive papers for Ni-Cr and Midi-Gold, and 100 grit papers for amalgam. Ni-Cr-Be and Midi-Gold samples were sandblasted for 30 s and steam cleaned for 10 s. The adhesives were bonded to the samples using gelatine capsules and were matured for 24 h in water at 37 degrees C. The samples were debonded in shear using an Instron at a cross-head speed of 1 mm/min. The data was analysed using ANOVA and a Tukey test. The bond strength of Superbond to both metal alloys was significantly higher (P<0.05) than any of the materials tested, with the exception Panavia 21 to gold. The bond strength of All Bond C&B cement had shown to be not significant difference from those of Panavia 21 and Variolink, when bonded to Rexillium and Midi-Gold, respectively. The bond strength of All Bond C&B Cement to amalgam was significantly greater (P<0.05) than those of the other materials tested. The shear bond strength to gold showed lower bonding for all adhesives when compared with Rexillium (P<.001). The ranking of bond strength to both alloys was as follows: Superbond>Panavia 21>All Bond C&B>Variolink. The nature of substrate to be used for bonding and the adhesive material itself are important factors in bonding which can be achieved between cast metals and prepared teeth with amalgam filling. Superbond should be successful as an adhesive for the attachment of all substrates tested, with the possible exception of amalgam, for which All Bond C&B Cement gives the best result.

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

    PubMed

    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.

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

    PubMed

    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.

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

    PubMed

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

    PubMed

    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 < 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.

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

    PubMed Central

    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 < 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. PMID:27110804

  13. Adhesives, silver amalgam.

    PubMed

    1995-09-01

    The most recent advancement in silver amalgam is use of resin formulations to bond metal to tooth both chemically &/or physically, Since, historically, amalgam has been used successfully without adhesion to tooth, obvious clinical question is: Why is bonding now desirable? Two major clinical reasons to bond are: (1) Adhesive can increase fracture resistance of amalgam restored teeth & decrease cusp fractures; & (2) Seal provided by adhesive can greatly decrease, & often eliminate post-operative sensitivity. Following report summarizes CRA laboratory study of shear bond strength & sealing capability of 23 commercial adhesives used to bond 2 types of silver amalgam to tooth structure.

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

    PubMed

    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).

  15. Amalgam and composite posterior restorations: curriculum versus practice in operative dentistry at a US dental school.

    PubMed

    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.

  16. Amalgam

    SciTech Connect

    Fox, Kevin

    2012-09-05

    Amalgam is a system that allows you to generate collections of files that work with conventional tools but take up minimal extra space on storage. If you already are archiving files in a file system and don't want to make multiple copies of whole files in order to ship the data somewhere then this system is for you. Amalgam consists of tools that allow you to create and get information about '.amalgam' files which contain just the metadata associated with a set of files. It also contains a fuse file system that, using amalgam files, will dynamically create traditional tar files. With this setup, you can see multiple orders of magnitude reduction in storage requirements for temporary data collections.

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

    PubMed

    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) (p<0.05). Group 9 exhibited significantly lower values (8.3 ± 3.4) than were noted in groups 1 to 3 (35.5 ± 4.1; 27 ± 12.5; 24.4 ± 5.1, respectively) (p<0.05). Group 7 (16.4 ± 5.9) showed significantly lower values than were observed in

  18. Decisions of practitioners regarding placement of amalgam and composite restorations in general practice settings.

    PubMed

    Pink, F E; Minden, N J; Simmonds, S

    1994-01-01

    This study was undertaken to analyze the current reasons practitioners in general practice settings choose to place amalgam and composite restorations. Data were gathered on individual restorations in the clinical setting to provide information on reasons practitioners state that restorations are placed, the type of material most often placed in different restoration classifications, and the age of restorations at the time of replacement. The results of this study indicate that approximately one-half of all restorations, both amalgam and composite, were placed to treat primary caries. One-half of the remaining restorations placed, i.e., not including those with primary caries, were placed to treat recurrent caries. With respect to restorative materials, amalgam was most often placed in class 1 and class 2 situations (88.9% of the amalgam restorations reported), while composite was most often placed in class 3, 4, or 5 situations (77.4% of the composite restorations reported). From the total data set returned for replaced restorations, only 20% of the data forms reported on verified longevity of the restoration being replaced. Analysis of these data gave a calculated median longevity for amalgam and composite restorations of 10 years and 5 years respectively.

  19. The effectiveness of four-cavity treatment systems in sealing amalgam restorations.

    PubMed

    Morrow, Leean A; Wilson, Nairn H F

    2002-01-01

    Amalgam does not bond to tooth tissue; therefore, restorations using such material are prone to leakage despite the deposition of corrosion products. This study evaluated the effectiveness of four cavity treatment systems placed in vivo in sealing restorations of amalgam. Four cavity treatment systems were investigated in this study: Cervitec, Gluma One Bond, Panavia 21 and Copaliner Dentin Varnish and Sealant. No cavity treatment was placed in an additional group to serve as a control. The teeth were extracted within 15 minutes of restoration placement. The specimens were thermocycled (5-55 +/- 2 degrees C, 500 cycles), immersed in a dye solution, sectioned and scored for leakage. Scanning electron microscopy also examined features of the tooth/restoration interfaces. There were statistically significant differences among the groups regarding leakage scores (p = 0.00). None of the materials tested consistently prevented leakage; however, use of Copaliner Dentin Varnish and Sealant resulted in less overall, occlusal and cervical microleakage than any other systems tested. Significantly more leakage was observed in relation to the cervical portions of the cavities (p = 0.00). No significant differences were identified between the leakage scores obtained for the buccal and palatal (lingual) cavities and the different tooth types (p = 0.52 and 0.83, respectively). A level of significance of 0.05 was selected in all cases. The benefits of the materials tested in this study need to be evaluated using robust, long-term clinical studies. Further work should continue to develop laboratory tests that predict the behavior and performance of cavity sealants in clinical service.

  20. Minor changes in serum levels of cytokines after removal of amalgam restorations.

    PubMed

    Björkman, Lars; Brokstad, Karl A; Moen, Ketil; Jonsson, Roland

    2012-06-01

    Dental amalgam restorations release mercury and silver which is absorbed and distributed in the body. Animal studies have shown that both elements may interfere with the host by activation of the immune system in genetically susceptible strains at exposure levels relevant to those from dental amalgam restorations. The aim of this study was to test the hypothesis of no change over time in concentrations of a number of immune mediators in serum after removal of all dental amalgam restorations in patients with health complaints attributed to their amalgam restorations and compare with a healthy reference group. Twenty patients previously examined at a specialty unit for health complaints attributed to dental materials were included in a clinical trial and had all amalgam restorations replaced with other dental restorative materials. Serum samples were collected before amalgam removal and 3 and 12 months after the removal was finished. Twenty blood donors matched for age and gender were used as comparison group. A fluorescent bead-based (Luminex) immunoassay kit was used to measure cytokines, chemokines and growth factors in serum. At baseline, the patient group had slightly higher values for GM-CSF, IL-6, IL-2R, IFN-alpha, IL-7, and IL-12p40/p70 compared with the reference group. After amalgam removal a decrease towards the median value of the reference group was found for GM-CSF, IL-8, and IL-7. In conclusion, removal of all dental amalgam restorations and replacement with other dental restorative materials was associated with decreased concentrations of Th1-type proinflammatory markers in serum.

  1. Lichenoid reaction associated with silver amalgam restoration in a Bombay blood group patient: A case report.

    PubMed

    Pawar, Rohini Rangarao; Mattigatti, Sudha S; Mahaparale, Rushikesh R; Kamble, Amit P

    2016-01-01

    The pathogenic relationship between the oral lichenoid reaction (OLR) and dental restorative materials has been confirmed many times. An OLR affecting oral mucosa in direct contact with an amalgam restoration represents a delayed, type IV, cell mediated immune response to mercury or one of the other constituents of the dental amalgam. Bombay blood group patients are more prone to this. A case of bilateral OLR is presented, which is present in relation to amalgam restoration. The lesion healed up after the replacement of restorations with an intermediate restorative material. The clinician should be aware of all the possible pathological etiologies of white lesions. If there is any doubt about the nature or management of a usual oral lesion, a referral to an appropriate specialist is mandatory.

  2. Replacing Amalgam Restorations: A Standardized Protocol Based on Analyzing Tissue Physicochemical Modifications.

    PubMed

    Decup, Franck; Epaillard, Alexandre; Chemla, Florence

    2015-12-01

    Almost 60% of operative dentistry is devoted to replacing restorations. When practitioners have to replace an amalgam restoration, they tend to opt for an adhesive restoration, as it is conservative of tooth tissues and mimics the natural appearance of teeth. Based on a literature review, the aim of this article is to determine the best tissue approach when replacing an old amalgam by a new adhesive restoration. After analyzing and understanding tissue alterations due to the amalgam corrosion process, the authors propose an analytical approach to managing the situation. Both tissue orientated and specific mechanical approaches are developed and should be implemented to carry out the optimal clinical procedure and achieve the most conservative and durable treatment.

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

    PubMed

    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 P<0.05. Results. A total 34 restorations of 28 restorations (14 pairs) of the total restorations still survived after 24 months. Compomerrestorations showed significantly better results in marginal integrity. Recurrent caries was significantly lower incompomer restorations compared to amalgam 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.

  4. In vitro comparison of the shear bond strength of amalgam to tooth structure using two bonding agents--lutting glass ionomer and 4-META.

    PubMed

    Sheela, K; Sudeep, P T; Hegde, V; Francis, R F; Bhat, K S; Sundeep, P T

    1998-01-01

    Bonding dental amalgam to tooth structure using 4-META has become an accepted clinical procedure. Glass ionomer cements possess the ability to bind to tooth structure as well as to the components of dental amalgam. The present in vitro study evaluates the shear bond strength of amalgam to tooth structure using luting glass ionomer as a bond mediating agent, and compares with that obtained using 4-META. Results indicate that it is possible to bond amalgam to tooth structure using a thin layer of glass ionomer cement. The shear bond strength of glass ionomer cement mediated bond is significant and may be adequate for clinical application.

  5. Comparison of wear and clinical performance between amalgam, composite and open sandwich restorations: 2-year results.

    PubMed

    Sachdeo, A; Gray, Gordon B; Sulieman, M A; Jagger, Daryll C

    2004-03-01

    There has been some disquiet over the use of mercury containing restorative materials. The most commonly used alternative is composite resin but this has the potential disadvantage associated with wear and marginal leakage, which in turn, has proven to result in secondary caries and sensitivity. To overcome the shortcomings of a directly placed composite restoration, the glass-ionomer/composite open sandwich technique was introduced followed by the subsequent introduction of compomer systems. The aims of this study were to evaluate the wear and clinical performance of a control group of amalgam restorations compared with that of a group of posterior composite resin restorations fillings and a group of compomer/composite open sandwich restorations placed by a single general dental practitioner. The duration of the study was 2 years. One hundred and thirty three (71.4%) patients were successfully recalled and the wear and clinical performance of each restoration after 6, 12 and 24 months was measured, indirectly. There was no statistically significant difference recorded between the groups at 6 months or 1 year (p > 0.05). However, at the end of the 2-year study, there was a significantly lower rate of wear recorded for the control amalgam restorations compared with other two groups (p = 0.033). There was no statistically significant difference in wear recorded between the two groups of tooth-coloured restorations (p > 0.05). With regards to clinical performance of the restorations, occlusal and proximal contacts in each group of restoration remained satisfactory throughout the study.

  6. Restoration of posterior teeth in clinical practice: evidence base for choosing amalgam versus composite.

    PubMed

    Kovarik, Robert E

    2009-01-01

    This article reviews the current use of amalgam versus resin composite in posterior restorations and the evidence-base for choosing between these two treatment options. While much research has been published on the issue of the clinical use of amalgam versus resin composite, there are several issues that limit the true evidence-base on the subject. Furthermore, while the majority of published studies on posterior composites would seem to indicate equivalent clinical performance of resin composite to amalgam restorations, the studies that should be weighted much more heavily (randomized controlled trials) do not support the slant of the rest of the literature. As part of an evidence-based approach to private practice, clinicians need to be aware of the levels of evidence in the literature and need to properly inform patients of the true clinical outcomes that are associated with the use of amalgam versus resin composite for posterior restorations, so that patients are themselves making informed decisions about their dental care.

  7. An in vitro Evaluation of Microleakage of Posterior Teeth Restored with Amalgam, Composite and Zirconomer – A Stereomicroscopic Study

    PubMed Central

    Punia, Sandhya Kapoor; Bhat, Surekha; Singh, Gautam; Goyal, Pravesh; Oza, Swapnil; Raiyani, Chirag M.

    2015-01-01

    Background Numerous restorative materials are being used in dentistry to achieve adequate strength and restore aesthetics. However, a perfect ideal restorative material has still eluded dentist. Dental amalgam is versatile material with self-sealing property, but is unaesthetic. Other restorative materials like, composites require conservative preparation, but exhibits polymerisation shrinkage resulting in microleakage. To overcome these drawbacks a high strength restorative material reinforced with ceramic and zirconia fillers known as zirconomer has been introduced. The aim of this study was to evaluate the micro-leakage of these three different restorative materials. Materials and Methods Thirty non-carious human permanent first and second molars were utilized in this study. Class I cavities were prepared on the occlusal surface; cavities were then restored with amalgam, composite and zirconomer as per manufacture’s instruction. All samples were stored for 24 hours in distilled water followed by thermocycling. The entire tooth surface was painted with two coats of varnish to within 1mm of the restoration margins. The teeth were immersed in dye. Teeth were sectioned and observed under stereomicroscope. Results In this study the zirconomer exhibited the highest micro leakage as compared to composite and amalgam but composite having higher micro leakage as compared to amalgam and lower micro leakage as compared to zirconomer. Conclusion Even though composite and amalgam are being marketed aggressively and new material like zirconomer are on origin, amalgam still proves to be one of the best materials. PMID:26393208

  8. Legislation and informed consent brochures for dental patients receiving amalgam restorations.

    PubMed

    Edlich, Richard F; Cochran, Amy A; Cross, Catherine L; Wack, Courtney A; Long, William B; Newkirk, Anthony T

    2008-01-01

    In 2008, Norway banned the use of mercury for amalgam restorations. Four states in the United States have developed Informed Consent Brochures for amalgam restorations that must be given to their dental patients. The authors describe a patient who had a large cavity in his left lower molar tooth no.18 that had to be removed by an oral surgeon. When the patient went to the oral surgeon, the surgeon told the patient that he would replace the carious tooth with a gold implant. He was not given an Informed Consent Brochure regarding dental restorative materials. The oral surgeon extracted the carious tooth, replacing the tooth with a supposed gold crown implant. On his yearly dental examination, his dentist took an x-ray of his dental implant and explained that the x-ray could not distinguish whether the implant contained either gold or mercury. Consequently, the dentist referred him to a dental clinic in which the dental implant could be removed without mercury contamination of the patient's neurologic system during the extraction of the implant from the root canal. During the removal of the dental restoration, the dentist found build up expanding into the root canal that had a black color. The crown and underlying tooth were sent to ALT BioScience for analysis. Elemental analysis of the crown and underlying tooth confirmed the presence of mercury in the restoration. The patient should have been given an Informed Consent Brochure by the dentist that described the dental restoration that was used in the dental implant.

  9. Curriculum time compared to clinical procedures in amalgam and composite posterior restorations in U.S. dental schools: a preliminary study.

    PubMed

    Rey, Rosalia; Nimmo, Susan; Childs, Gail S; Behar-Horenstein, Linda S

    2015-03-01

    Dental clinicians have an expanding range of biomaterial choices for restoring tooth structure. Scientific developments in cariology, advances in dental biomaterials, and patients' esthetic concerns have led to a reduction in amalgam restorations and an increase in composite restorations. The aim of this study was to compare teaching time with students' clinical procedures in amalgam and composite posterior restorations in dental schools across the United States. Academic deans in 60 schools were invited to complete a survey that asked for the amount of instructional time for amalgam and composite posterior restorations and the number of clinical restorations performed by their Classes of 2009, 2010, and 2011. Of these 60, 12 returned surveys with complete data, for a 20% response rate. Responses from these schools showed little change in lecture and preclinical laboratory instruction from 2009 to 2011. There was a slight increase in two-surface restorations for both amalgam and composites; however, the total number of reported composite and amalgam restorations remained the same. Of 204,864 restorations reported, 53% were composite, and 47% were amalgam. There were twice as many multisurface large or complex amalgam restorations as composites. One-surface composite restorations exceeded amalgams. Among the participating schools, there was little to no change between curriculum time and clinical procedures. Findings from this preliminary study reflect a modest increase in two-surface resin-based restorations placed by dental students from 2009 to 2011 and little change in curricular time devoted to teaching amalgam restorations. The total number of posterior composite restorations placed by students in these schools was slightly higher than amalgams.

  10. Trends in material choice for posterior restorations in an Israeli dental school: composite resin versus amalgam.

    PubMed

    Ben-Gal, Gilad; Weiss, Ervin I

    2011-12-01

    According to a recent American Dental Association survey, posterior composite resin restorations now outnumber amalgam restorations in the United States. Dental schools around the world vary considerably in the extent to which they teach the use of composite resins. We aimed to determine if there has been an increase in the placement of posterior composite restorations in an Israeli dental school and if faculty experience affects the type of posterior restoration placed. In this retrospective study, we recorded and analyzed all the restorations performed by undergraduate students in the last five academic years at the Hebrew University Hadassah School of Dental Medicine in Jerusalem. All clinical records of student treatments between 2004 and 2009 were screened, and direct restorations were registered. Out of 6,094 posterior restorations performed during the study period, 42.3 percent were made of composite resin, increasing from 36.8 percent in 2004-05 to 48.5 percent in 2008-09, an increase of 11.7 percent. When clinical instructors were asked to state their preference if they themselves were to undergo posterior restoration, similar results were obtained. Instructors with less than ten years' experience preferred posterior composite resin restorations in 54.8 percent of the hypothetical situations, compared with 37.2 percent preferred by instructors with ten years of experience or more. It appears that the use of composite resin was influenced mainly by the prevailing trend and was not based on scientific evidence. Dental faculties should define criteria, based on up-to-date clinical studies, for using new materials, taking into consideration differences among instructors regarding treatment concept.

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

    PubMed

    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.

  12. Effects of mercury release from amalgam dental restorations during cremation on soil mercury levels of three New Zealand crematoria

    SciTech Connect

    Nieschmidt, A.K.; Kim, N.D.

    1997-05-01

    A vast amount of research has been undertaken in the last 15-20 years on the corrosion reactions occurring in dental amalgam, release of mercury from amalgam restorations, and the toxic effects of this released mercury on the human body. However, one environmental aspect of amalgam dental restorations that has not received a great deal of attention is the release of mercury during cremation. Mercury is liberated during cremation both because dental amalgams are unstable at cremation temperatures (650-700{degrees}C) and because the free mercury metal is highly volatile. In New Zealand, 58% of deaths are followed by cremation and this figure is likely to rise in the future. This increasing use of cremation as the method of corpse disposal, coupled with the fact that each amalgam restoration is approximately 50% mercury, implies that a significant amount of mercury may be emitted into the environment every year. This study examines mercury released from crematoria in New Zealand. 20 refs., 2 figs., 5 tabs.

  13. Seal, replacement or monitoring amalgam restorations with occlusal marginal defects? Results of a 10-year clinical trial.

    PubMed

    Moncada, G; Fernández, E; Mena, K; Martin, J; Vildósola, P; De Oliveira Junior, O B; Estay, J; Mjör, I A; Gordan, V V

    2015-11-01

    The aim of this prospective and blind clinical trial was to assess the effectiveness of sealing localized marginal defects of amalgam restoration that were initially scheduled to be replaced. A cohort of twenty six patients with 60 amalgam restorations (n=44Class I and n=16Class II), that presented marginal defects deviating from ideal (Bravo) according to USPHS criteria, were assigned to either sealing or replacement groups: A: sealing n=20, Replacement n=20, and no treatment (n=20). Two blind examiners evaluated the restorations at baseline (K=0.74) and after ten years (K=0.84) according with USPHS criteria, in four parameters: marginal adaptation (MA), secondary caries (SC), marginal staining (MS) and teeth sensitivity (TS). Multiple comparison of restorations degradation/upgrade was analyzed by Friedman test and the comparisons within groups were performed by Wilcoxon test. After 10 years, 44 restorations were assessed (73.3%), Group A: n=14 and Group B: n=16; and Group C: n=14 sealing and replacement amalgam restorations presented similar level of quality in MA (p=0.76), SC (p=0.25) and TS (p=0.52), while in MS (p=0.007) presented better performance in replacement group after 10-years. Most of the occlusal amalgam restorations with marginal gaps showed similar long term outcomes than the restorations were sealed, replaced, or not treated over a 10-year period. Most of the restorations of the three groups were clinically acceptable, under the studied parameters. All restorations had the tendency to present downgrade/deterioration over time.

  14. Streptococcus mutans-induced secondary caries adjacent to glass ionomer cement, composite resin and amalgam restorations in vitro.

    PubMed

    Gama-Teixeira, Adriana; Simionato, Maria Regina Lorenzeti; Elian, Silvia Nagib; Sobral, Maria Angela Pita; Luz, Maria Aparecida Alves de Cerqueira

    2007-01-01

    The aim of this study was to define, in vitro, the potential to inhibit secondary caries of restorative materials currently used in dental practice. Standard cavities were prepared on the buccal and lingual surfaces of fifty extracted human third molars. The teeth were randomly divided into five groups, each one restored with one of the following materials: glass ionomer cement (GIC); amalgam; light-cured composite resin; ion-releasing composite; and light-cured, fluoride-containing composite resin. The teeth were thermocycled, sterilized with gamma irradiation, exposed to a cariogenic challenge using a bacterial system using Streptococcus mutans, and then prepared for microscopic observation. The following parameters were measured in each lesion formed: extension, depth, and caries inhibition area. The outer lesions developed showed an intact surface layer and had a rectangular shape. Wall lesions were not observed inside the cavities. After Analysis of Variance and Component of Variance Models Analysis, it was observed that the GIC group had the smallest lesions and the greatest number of caries inhibition areas. The lesions developed around Amalgam and Ariston pHc restorations had an intermediate size and the largest lesions were observed around Z-100 and Heliomolar restorations. It may be concluded that the restorative materials GIC, amalgam and ion-releasing composites may reduce secondary caries formation.

  15. Validity and reliability of methods for the detection of secondary caries around amalgam restorations in primary teeth.

    PubMed

    Braga, Mariana Minatel; Chiarotti, Ana Paula Sturion; Imparato, José Carlos Pettorossi; Mendes, Fausto Medeiros

    2010-01-01

    Secondary caries has been reported as the main reason for restoration replacement. The aim of this in vitro study was to evaluate the performance of different methods--visual inspection, laser fluorescence (DIAGNOdent), radiography and tactile examination--for secondary caries detection in primary molars restored with amalgam. Fifty-four primary molars were photographed and 73 suspect sites adjacent to amalgam restorations were selected. Two examiners evaluated independently these sites using all methods. Agreement between examiners was assessed by the Kappa test. To validate the methods, a caries-detector dye was used after restoration removal. The best cut-off points for the sample were found by a Receiver Operator Characteristic (ROC) analysis, and the area under the ROC curve (Az), and the sensitivity, specificity and accuracy of the methods were calculated for enamel (D2) and dentine (D3) thresholds. These parameters were found for each method and then compared by the McNemar test. The tactile examination and visual inspection presented the highest inter-examiner agreement for the D2 and D3 thresholds, respectively. The visual inspection also showed better performance than the other methods for both thresholds (Az = 0.861 and Az = 0.841, respectively). In conclusion, the visual inspection presented the best performance for detecting enamel and dentin secondary caries in primary teeth restored with amalgam.

  16. [Black or white--Which choice for the molars? Part 2. Which does one choose for the restoration of posterior teeth: amalgam or composite?].

    PubMed

    De Moor, Roeland; Delmé, Katleen

    2008-01-01

    The two direct dental restorative materials most commonly used today are silver-mercury amalgam and resin-based composite. The survival of dental amalgam restorations is twice as high than for composite fillings: polymerisation shrinkage, deficient marginal adaptation, higher wear rates, defective contact points leading to food impaction, insufficiently converted composite at the bottom of the cavity are problems that cannot be underestimated when using resin-composite. This does not imply that there is no weakness for amalgam: the need for retentive cavities at the cost of healthy tooth substance, weakening of the tooth's strength by cutting through the tooth crown's ridges, the risk of fracture of remaining tooth substance (mostly buccal and lingual surfaces) as the result of the cavity design, and the lack of adhesion between amalgam and tooth substance. Retaining a tooth's strength by the replacement of amalgam by resin-composites is not always the correct solution. In this respect, it can be questioned whether it is not appropriate to repair failing (extensive) amalgam restorations as to replace them with resin-composites. Research in this respect has demonstrated that dentists still are not convinced of this treatment option. Restoring a tooth in its original build-up or structure and function within the oral cavity is the basis of the biomimetic principle: the use of composite appears to be more obvious than restoring with amalgam. In the present survey pro's and con's of amalgams and resin-composites for the restoration of posterior teeth are weighted. The conclusion demonstrates that there is still a place for dental amalgam in modern restorative dentistry when plastic filling materials are used for the direct tooth repair or restoration.

  17. On modeling and nanoanalysis of caries-affected dentin surfaces restored with Zn-containing amalgam and in vitro oral function.

    PubMed

    Toledano, Manuel; Aguilera, Fátima S; Osorio, Estrella; López-López, Modesto T; Cabello, Inmaculada; Toledano-Osorio, Manuel; Osorio, Raquel

    2015-12-19

    The aim of this research was to assess the influence of mechanical loading on the ability of Zn-free versus Zn-containing amalgams to promote remineralization at the dentin interface. Sound and caries-affected dentin surfaces (CAD) were restored using Zn-free or Zn-containing dental amalgams. Midcoronal dentin surfaces were studied by (1) atomic force microscopy analysis (including plot and phase imaging, nanoindentation test [modulus of Young (Ei), nanoroughness measurements, and fibril diameter assessment], (2) Raman spectroscopy/cluster analysis, (3) x-ray diffraction, (4) field emission electron microscope and energy-dispersive analysis, for morphological, mechanical, and physicochemical characterization. Analyses were performed before amalgam placement and after amalgam removal, at 24 h and 3 weeks of load cycling. Zn-free and Zn-containing amalgams restorations promoted an increase in the modulus of Young of CAD surfaces, after 3 weeks of load cycling; at this time, Zn-containing amalgams attained higher Ei than Zn-free restorations. Zn-containing amalgams induced tubular occlusion after load cycling, in both sound and CAD. Zn free-amalgams promoted remineralization of both intertubular and peritubular dentin in CAD substrata. These minerals were identified as calcium-phosphate deposits and crystals as hydroxyl-apatite with augmented crystallographic maturity but with some components of lattice distortion. Crosslinking of collagen diminished and secondary structure of collagen increased in CAD substrate restored with Zn-containing amalgam after 3 weeks of load cycling, indicating an advanced preservation, molecular organization, and orientation of collagen fibrils after load cycling. Plot and phase images permitted to observe the topographical changes which were promoted by the mineral deposits; in general, the indexes related to higher remineralization gave rise to a decrease of nanoroughness and an augmentation of the bandwidth of the collagen fibrils. Zn

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

    PubMed

    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.

  19. Biocompatibility of a flowable composite bonded with a self-etching adhesive compared with a glass lonomer cement and a high copper amalgam.

    PubMed

    Shimada, Yasushi; Seki, Yuichi; Sasafuchi, Yasutaka; Arakawa, Makoto; Burrow, Michael F; Otsuki, Masayuki; Tagami, Junji

    2004-01-01

    This study evaluated the pulpal response and in-vivo microleakage of a flowable composite bonded with a self-etching adhesive and compared the results with a glass ionomer cement and amalgam. Cervical cavities were prepared in monkey teeth. The teeth were randomly divided into three groups. A self-etching primer system (Imperva FluoroBond, Shofu) was applied to the teeth in one of the experimental groups, and the cavities were filled with a flowable composite (SI-BF-2001-LF, Shofu). In the other groups, a glass ionomer cement (Fuji II, GC) or amalgam (Dispersalloy, Johnson & Johnson) filled the cavity. The teeth were then extracted after 3, 30 and 90 days, fixed in 10% buffered formalin solution and prepared according to routine histological techniques. Five micrometer sections were stained with hematoxylin and eosin or Brown and Brenn gram stain for bacterial observation. No serious inflammatory reaction of the pulp, such as necrosis or abscess formation, was observed in any of the experimental groups. Slight inflammatory cell infiltration was the main initial reaction, while deposition of reparative dentin was the major long-term reaction in all groups. No bacterial penetration along the cavity walls was detected in the flowable composite or glass ionomer cement except for one case at 30 days in the glass ionomer cement. The flowable composite bonded with self-etching adhesive showed an acceptable biological com- patibility to monkey pulp. The in vivo sealing ability of the flowable composite in combination with the self-etching adhesive was considered comparable to glass ionomer cement. Amalgam restorations without adhesive liners showed slight bacterial penetration along the cavity wall.

  20. An elementary study of deformation of molar teeth during amalgam restorative procedures.

    PubMed

    Bell, J G

    1977-06-01

    A technique using an optical comparator was employed to examine the dimensional changes resulting from cavity preparation, application of the matrix and packing with amalgam in three extracted molar teeth. The changes have been reported and the nature of the change discussed. A modification in the use of the matrix and amalgam packing technique is suggested.

  1. Reactions of connective tissue to amalgam, intermediate restorative material, mineral trioxide aggregate, and mineral trioxide aggregate mixed with chlorhexidine.

    PubMed

    Sumer, Mahmut; Muglali, Mehtap; Bodrumlu, Emre; Guvenc, Tolga

    2006-11-01

    The aim of this study was to histopathologically examine the biocompatibility of the high-copper amalgam, intermediate restorative material (IRM), mineral trioxide aggregate (MTA), and MTA mixed with chlorhexidine (CHX). This study was conducted to observe the rat subcutaneous connective tissue reaction to the implanted tubes filled with amalgam, IRM, MTA, and MTA mixed with CHX. The animals were sacrificed 15, 30, and 60 days after the implantation procedure. The implant sites were excised and prepared for histological evaluation. Sections of 5 to 6 microm thickness were cut by a microtome and stained with hemotoxylin eosin and examined under a light microscope. The inflammatory reactions were categorized as weak (none or few inflammatory cells < or =25 cells), moderate (>25 cells), and severe (a lot of inflammatory cells not to be counted, giant cells, and granulation tissue). Thickness of fibrous capsules measured five different areas by the digital imaging and the mean values were scored. Amalgam, IRM, and MTA mixed with CHX caused a weak inflammatory response on days 15, 30, and 60. MTA provoked an initial severe inflammatory response that subsided at the 30 and 60 day study period. A clear fibrous capsule was observed beginning from the 15 days in all of the groups. Within the limits of this study, amalgam, IRM, MTA, and MTA mixed with CHX materials were surrounded by fibrous connective tissue indicated that they were well tolerated by the tissues, therefore, MTA/CHX seemed to be biocompatible.

  2. Staining of residual caries under freshly-packed amalgam restorations exposed to tea/chlorhexidine in vitro.

    PubMed

    Kidd, E A; Joyston-Bechal, S; Smith, M M

    1990-08-01

    Discoloration around restorations may lead practitioners to suspect recurrent caries. Dentists, using conventional optical and tactile criteria, often fail to render the enamel-dentine junction completely caries-free during cavity preparation. The aim of the present laboratory study was to test the hypothesis that such residual caries could take up stain from tea and hence affect clinical judgement on the presence of recurrent disease. Cavities were prepared in freshly extracted carious teeth and restored with amalgam. Specimens were then temperature cycled in tea and chlorhexidine or in tea alone to encourage leakage. Subsequent removal of restorations showed staining of parts of the enamel-dentine junctions and histological examination showed these stained areas to correspond to areas of demineralization. Similarly prepared caries-free teeth showed no such staining. Thus residual caries in teeth with leaking restorations can, in the laboratory, take up stain. If this were to happen in vivo, stained residual caries could subsequently be misdiagnosed as recurrent caries.

  3. Removal of amalgam, glass-ionomer cement and compomer restorations: changes in cavity dimensions and duration of the procedure.

    PubMed

    Szep, Susanne; Baum, C; Alamouti, C; Schmidt, D; Gerhardt, T; Heidemann, D

    2002-01-01

    This study investigated changes in the dimensions of Class II cavities following the removal of amalgam, glass ionomer and compomer restorations. In 30 extracted caries-free human molars, preparation for 60 mesio-occlusal and occluso-distal cavities (two cavities per tooth) occurred. With a CEREC 3 laser triangulation sensor and software-based construction analysis, the dimensions of the cavities at seven defined sites were measured. The cavities were randomized into four groups. Group 1 was restored with Ketac-Fil glass-ionomer cement, Group 2 with amalgam and Group 3 with Compoglass F compomer. In Group 4, Compoglass F was used in combination with photochromic Tetric Flow Chroma as a cavity liner. The completed restorations were then removed using 2x magnification and the cavities were once again controlled using the laser system. The duration of the removal procedure was also recorded. Changes in cavity dimensions (depth, height and width) following removal of the restorations were significantly smaller in Groups 1 and 2. Groups 3 and 4 were characterized by a significant overextension of the cavities compared to Groups 1 and 2 in all three dimensions. Group 4, with Tetric Flow Chroma as a cavity liner, showed better results than Group 3, but this improvement was not statistically significant. The duration of the removal procedure was significantly shorter in Group 2 than in the other groups.

  4. Bonded restorations for the prevention and treatment of the cracked-tooth syndrome.

    PubMed

    Geurtsen, W; García-Godoy, F

    1999-12-01

    Several reports revealed that the cracked-tooth syndrome is a common problem in dental practice, which often results in extraction of the affected incompletely fractured teeth. Predominantly restored teeth suffer from these incomplete fractures. Therefore, it is of outstanding importance to stabilize teeth weakened due to cavity preparation. Besides full cuspal coverage by partial or full crowns, bonded restorations have been proposed for internal splinting of restored teeth. Although contradictory data have been published, there is evidence that bonded amalgam or resin-based composite restorations (RBC) do not increase fracture resistance of teeth with wide occlusal-proximal cavities to values similar to sound, unrestored controls. Indirectly fabricated RBC inlays and various ceramic inlays, however, increased fracture strength to levels as high as those of sound caries-free teeth. Therefore, it is recommended that weakened teeth with wide cavities be strengthened by full cuspal coverage with cast or ceramic restorations, by bonded ceramic inlays, or by indirectly-fabricated bonded RBC composite inlays.

  5. Randomized clinical comparison of endodontically treated teeth restored with amalgam or with fiber posts and resin composite: five-year results.

    PubMed

    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.

  6. Absence of carious lesions at margins of glass-ionomer cement and amalgam restorations: An update of systematic review evidence

    PubMed Central

    2011-01-01

    Background This article aims to update the existing systematic review evidence elicited by Mickenautsch et al. up to 18 January 2008 (published in the European Journal of Paediatric Dentistry in 2009) and addressing the review question of whether, in the same dentition and same cavity class, glass-ionomer cement (GIC) restored cavities show less recurrent carious lesions on cavity margins than cavities restored with amalgam. Methods The systematic literature search was extended beyond the original search date and a further hand-search and reference check was done. The quality of accepted trials was assessed, using updated quality criteria, and the risk of bias was investigated in more depth than previously reported. In addition, the focus of quantitative synthesis was shifted to single datasets extracted from the accepted trials. Results The database search (up to 10 August 2010) identified 1 new trial, in addition to the 9 included in the original systematic review, and 11 further trials were included after a hand-search and reference check. Of these 21 trials, 11 were excluded and 10 were accepted for data extraction and quality assessment. Thirteen dichotomous datasets of primary outcomes and 4 datasets with secondary outcomes were extracted. Meta-analysis and cumulative meta-analysis were used in combining clinically homogenous datasets. The overall results of the computed datasets suggest that GIC has a higher caries-preventive effect than amalgam for restorations in permanent teeth. No difference was found for restorations in the primary dentition. Conclusion This outcome is in agreement with the conclusions of the original systematic review. Although the findings of the trials identified in this update may be considered to be less affected by attrition- and publication bias, their risk of selection- and detection/performance bias is high. Thus, verification of the currently available results requires further high-quality randomised control trials. PMID

  7. Dental Amalgam

    MedlinePlus

    ... Products 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 ...

  8. Interface corrosion in amalgam-to-amalgam and amalgam-to-nonprecious metal crown couplings.

    PubMed

    Schimelmitz, H; Bapna, M S; Punwani, I; Ashrafi, S H; Anderson, A W

    1986-02-01

    This study examined the contact surface area in the coupling of a class II amalgam restoration with another class II amalgam restoration or with a stainless steel or nickel-chrome crown in 1% NaCl solution. The characterization of interfaces was carried out by using SEM and EDX microanalysis. The results indicate that the coupling of an amalgam-stainless steel crown and an amalgam-inconel crown in NaCl solution forms a deposit on the crown surfaces. This deposit contains all the constituents of corrodible phases of amalgam, including Zn. If amalgam restorations in adjoining teeth are contemplated, non-Zn-containing amalgam alloys of the same composition should be considered.

  9. Increased mercury release from dental amalgam restorations after exposure to electromagnetic fields as a potential hazard for hypersensitive people and pregnant women.

    PubMed

    Mortazavi, Ghazal; Mortazavi, S M J

    2015-01-01

    Over the past decades, the use of common sources of electromagnetic fields such as Wi-Fi routers and mobile phones has been increased enormously all over the world. There is ongoing concern that exposure to electromagnetic fields can lead to adverse health effects. It has recently been shown that even low doses of mercury are capable of causing toxicity. Therefore, efforts are initiated to phase down or eliminate the use of mercury amalgam in dental restorations. Increased release of mercury from dental amalgam restorations after exposure to electromagnetic fields such as those generated by MRI and mobile phones has been reported by our team and other researchers. We have recently shown that some of the papers which reported no increased release of mercury after MRI, may have some methodological errors. Although it was previously believed that the amount of mercury released from dental amalgam cannot be hazardous, new findings indicate that mercury, even at low doses, may cause toxicity. Based on recent epidemiological findings, it can be claimed that the safety of mercury released from dental amalgam fillings is questionable. Therefore, as some individuals tend to be hypersensitive to the toxic effects of mercury, regulatory authorities should re-assess the safety of exposure to electromagnetic fields in individuals with amalgam restorations. On the other hand, we have reported that increased mercury release after exposure to electromagnetic fields may be risky for the pregnant women. It is worth mentioning that as a strong positive correlation between maternal and cord blood mercury levels has been found in some studies, our findings regarding the effect of exposure to electromagnetic fields on the release of mercury from dental amalgam fillings lead us to this conclusion that pregnant women with dental amalgam fillings should limit their exposure to electromagnetic fields to prevent toxic effects of mercury in their fetuses. Based on these findings, as infants

  10. Dental amalgam: An update

    PubMed Central

    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

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

    PubMed

    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.

  12. A 24-month Evaluation of Amalgam and Resin-Based Composite Restorations: Findings from The National Dental Practice-Based Research Network

    PubMed Central

    McCracken, Michael S.; Gordan, Valeria V.; Litaker, Mark S.; Funkhouser, Ellen; Fellows, Jeffrey L.; Shamp, Douglass G.; Qvist, Vibeke; Meral, Jeffrey S.; Gilbert, Gregg H.

    2013-01-01

    Background Knowing which factors influence restoration longevity can help clinicians make sound treatment decisions. The authors analyzed data from the National Dental Practice-Based Research Network to identify predictors of early failures of amalgam and resin-based composite (RBC) restorations. Methods This prospective cohort study gathered information from clinicians and offices participating in the network. Clinicians completed a baseline data collection form at the time of restoration placement, and annually thereafter. Data collected included patient factors, practice factors, and dentist factors, and were analyzed using mixed-model logistic regression. Results A total of 226 practitioners followed 6,218 direct restorations in 3,855 patients; 386 restorations failed (6.6 percent) during the mean follow-up period of 23.7 (SD 8.8) months. The number of tooth surfaces restored at baseline predicted subsequent restoration failure; large restorations were over 4 times more likely to fail. Material was not significantly associated with longevity; neither was tooth type. Patient age was highly associated with failure (p<0.0001). The failure rate for children was 5 percent, compared to 12 percent in persons 65 years old or older. Dentist gender and practice workload were significantly associated with restoration longevity. Conclusions In this prospective cohort study, these factors significantly predicted an increased failure rate for amalgam and RBC restorations: older patient age and a higher number of surfaces restored at baseline, with other key baseline variables taken into account. Material choice was not significantly predictive in these early results. Clinical Implications Understanding risk factors for early restoration failure may lead to more-effective patient care. PMID:23729455

  13. Shear bond strength of partial coverage restorations to dentin

    PubMed Central

    Agustín-Panadero, Rubén; Alonso-Pérez-Barquero, Jorge; Fons-Font, Antonio; Solá-Ruíz, María-Fernanda

    2015-01-01

    Background When partial coverage restorations (veneers, inlays, onlays…) must be cemented to dentin, bond strength may not reach the same predictable values as to enamel. The purpose of this study was: 1. To compare, with a shear bond test, the bond strength to dentin of a total-etch and a self-etching bonding agent. 2. To determine whether creating microretention improves the bond strength to dentin. Material and Methods Two bonding agents were assayed, Optibond FL® (Kerr), two-bottle adhesive requiring acid etching, and Clearfil SE Bond® (Kuraray), two-bottle self-etching adhesive. The vestibular, lingual, distal and mesial surfaces of ten molars (n=10) were ground to remove all enamel and 40 ceramic samples were cemented with Variolink II® (Ivoclar Vivadent). Half the molar surfaces were treated to create round microretention (pits) to determine whether these could influence bond strength to dentin. The 40 molar surfaces were divided into four groups (n=10): Optibond FL (O); Clearfil SE (C); Optibond FL + microretention (OM); Clearfil SE + micro retention (CM). A shear bond test was performed and the bond failures provoked examined under an optical microscope. Results O=35.27±8.02 MPa; C=36.23±11.23 MPa; OM=28.61±6.27 MPa; CM=27.01±7.57 MPa. No statistically significant differences were found between the adhesives. Optibond FL showed less statistical dispersion than Clearfil SE. The presence of microretentions reduced bond strength values regardless of the adhesive used. Conclusions 1. Clearfil SE self-etching adhesive and Optibond FL acid-etch showed adequate bond strengths and can be recommended for bonding ceramic restorations to dentin. 2. The creation of round microretention pits compromises these adhesives’ bond strength to dentin. Key words:Adhesion to dentin, bonding agent, Optibond FL, Clearfil SE, microretention, shear bond test. PMID:26330937

  14. Durability of bonds and clinical success of adhesive restorations

    PubMed Central

    Carvalho, Ricardo M.; Manso, Adriana P.; Geraldeli, Saulo; Tay, Franklin R.; Pashley, David H.

    2013-01-01

    Resin-dentin bond strength durability testing has been extensively used to evaluate the effectiveness of adhesive systems and the applicability of new strategies to improve that property. Clinical effectiveness is determined by the survival rates of restorations placed in non-carious cervical lesions (NCCL). While there is evidence that the bond strength data generated in laboratory studies somehow correlates with the clinical outcome of NCCL restorations, it is questionable whether the knowledge of bonding mechanisms obtained from laboratory testing can be used to justify clinical performance of resin-dentin bonds. There are significant morphological and structural differences between the bonding substrate used in in vitro testing versus the substrate encountered in NCCL. These differences qualify NCCL as a hostile substrate for bonding, yielding bond strengths that are usually lower than those obtained in normal dentin. However, clinical survival time of NCCL restorations often surpass the durability of normal dentin tested in the laboratory. Likewise, clinical reports on the long-term survival rates of posterior composite restorations defy the relatively rapid rate of degradation of adhesive interfaces reported in laboratory studies. This article critically analyzes how the effectiveness of adhesive systems is currently measured, to identify gaps in knowledge where new research could be encouraged. The morphological and chemical analysis of bonded interfaces of resin composite restorations in teeth that had been in clinical service for many years, but were extracted for periodontal reasons, could be a useful tool to observe the ultrastructural characteristics of restorations that are regarded as clinically acceptable. This could help determine how much degradation is acceptable for clinical success. PMID:22192252

  15. Bonding of restorative materials to dentin with various luting agents.

    PubMed

    Peutzfeldt, A; Sahafi, A; Flury, S

    2011-01-01

    The aim was to compare eight types of luting agents when used to bond six indirect, laboratory restorative materials to dentin. Cylinders of the six restorative materials (Esteticor Avenir [gold alloy], Tritan [titanium], NobelRondo [feldspathic porcelain], Finesse All-Ceramic [leucite-glass ceramic], Lava [zirconia], and Sinfony [resin composite]) were ground and air-abraded. Cylinders of feldspathic porcelain and glass ceramic were additionally etched with hydrofluoric acid and were silane-treated. The cylinders were luted to ground human dentin with eight luting agents (DeTrey Zinc [zinc phosphate cement], Fuji I [conventional glass ionomer cement], Fuji Plus [resin-modified glass ionomer cement], Variolink II [conventional etch-and-rinse resin cement], Panavia F2.0 and Multilink [self-etch resin cements], and RelyX Unicem Aplicap and Maxcem [self-adhesive resin cements]). After water storage at 37°C for one week, the shear bond strength of the specimens (n=8/group) was measured, and the fracture mode was stereomicroscopically examined. Bond strength data were analyzed with two-factorial analysis of variance (ANOVA) followed by Newman-Keuls' Multiple Range Test (α=0.05). Both the restorative material and the luting agent had a significant effect on bond strength, and significant interaction was noted between the two variables. Zinc phosphate cement and glass ionomer cements produced the lowest bond strengths, whereas the highest bond strengths were found with the two self-etch and one of the self-adhesive resin cements. Generally, the fracture mode varied markedly with the restorative material. The luting agents had a bigger influence on bond strength between restorative materials and dentin than was seen with the restorative material.

  16. Quantitative microleakage of some dentinal bonding restorative systems.

    PubMed

    Hasegawa, T; Retief, D H

    1993-03-01

    The quantitative microleakage of class V cementum (dentin) cavities restored with six dentinal bonding restorative systems was determined in vitro. Ninety extracted human permanent first and second mandibular and maxillary premolars were used in this study. Class V preparations were made in cementum (dentin) at the root facial surfaces. The preparations were restored with 1) a dentin bonding system containing 2% HEMA and BisGMA and a light-cured microfilled composite; 2) the same materials only substituting META/MMA base and TBB catalyst monomers for the BisGMA sealer; 3) a dentin bonding system containing 35% HEMA with META/MMA base and TBB catalyst, and a light-cured hybrid composite; 5) the same dentin bonding system only substituting the 35% glycerylmethacrylate for the 35% HEMA and using the microfilled composite; and 6) the previously described system with a substitution of 0.5 mol EDTA for the 10% citric acid -3% FeCl3. Fifteen teeth were restored with each procedure. The restorations were finished with 12-bladed carbide burs 15 min after placement, the teeth were stored in saline at 37 degrees C for 24 h, finished with Sof-Lex discs and then thermocycled in 2% methylene blue solution 500 times between 50 degrees C and 8 degrees C with a dwell time of 15 s. Quantitative microleakage was determined by a spectrophotometric dye-recovery method and expressed in microgram/dye/restoration. The data were analyzed by ANOVA, Student-Newman-Keuls and Kruskal-Wallis tests. The quantitative microleakage of the teeth restored with the adhesive systems containing 35% glyceryl methacrylate was significantly reduced. The bonding mechanism of glyceryl methacrylate is not known.

  17. Effect of dentin surface roughness on the shear bond strength of resin bonded restorations

    PubMed Central

    Koodaryan, Roodabeh; Poursoltan, Sajjad

    2016-01-01

    PURPOSE This study aimed to investigate whether dentin surface preparation with diamond rotary instruments of different grit sizes affects the shear bond strength of resin-bonded restorations. MATERIALS AND METHODS The buccal enamel of 60 maxillary central incisors was removed with a low speed diamond saw and wet ground with silicon carbide papers. The polished surfaces of the teeth were prepared with four groups of rotary diamond burs with super-coarse (SC), coarse (C), medium (M), and fine (F) grit sizes. Following surface preparation, 60 restorations were casted with nickel-chromium alloy and bonded with Panavia cement. To assess the shear bond strength, the samples were mounted on a universal testing machine and an axial load was applied along the cement-restoration interface at the crosshead speed of 0.5 mm/min. The acquired data was analyzed with one way ANOVA and Tukey post hoc test (α=.05). RESULTS The mean ± SD shear bond strengths (in MPa) of the study groups were 17.75 ± 1.41 for SC, 13.82 ± 1.13 for C, 10.40 ± 1.45 for M, and 7.13 ± 1.18 for F. Statistical analysis revealed the significant difference among the study groups such that the value for group SC was significantly higher than that for group F (P<.001). CONCLUSION Dentin surface roughness created by diamond burs of different grit sizes considerably influences the shear bond strength of resin bonded restorations. PMID:27350858

  18. Porcelain laminate veneer restorations bonded with a three-liquid silane bonding agent and a dual-activated luting composite.

    PubMed

    Matsumura, Hideo; Aida, Yukiko; Ishikawa, Yumi; Tanoue, Naomi

    2006-12-01

    This clinical report describes the fabrication and bonding of porcelain laminate veneer restorations in a patient with anterior open spaces. Laminate veneer restorations made of feldspathic porcelain were etched with 5% hydrofluoric acid, rinsed under tap water, ultrasonically cleaned with methanol, and primed with a chemically activated three-liquid silane bonding agent (Clearfil Porcelain Bond). The enamel surfaces were etched with 40% phosphoric acid, rinsed with water, and primed with a two-liquid bonding agent (Clearfil New Bond) that contained a hydrophobic phosphate (10-methacryloyloxydecyl dihydrogen phosphate; MDP). The restorations were bonded with a dual-activated luting composite (Clapearl DC). The veneers have been functioning satisfactorily for an observation period of one year. Combined use of the Clearfil bonding agents and Clapearl DC luting composite is an alternative to conventional materials for seating porcelain laminate veneer restorations, although the system is inapplicable to dentin bonding.

  19. Shear Bond Strength of Three Orthodontic Bonding Systems on Enamel and Restorative Materials

    PubMed Central

    Ebeling, Jennifer; Schauseil, Michael; Stein, Steffen; Roggendorf, Matthias; Korbmacher-Steiner, Heike

    2016-01-01

    Objective. The aim of this in vitro study was to determine the shear bond strength (SBS) and adhesive remnant index (ARI) score of two self-etching no-mix adhesives (iBond™ and Scotchbond™) on different prosthetic surfaces and enamel, in comparison with the commonly used total etch system Transbond XT™. Materials and Methods. A total of 270 surfaces (1 enamel and 8 restorative surfaces, n = 30) were randomly divided into three adhesive groups. In group 1 (control) brackets were bonded with Transbond XT primer. In the experimental groups iBond adhesive (group 2) and Scotchbond Universal adhesive (group 3) were used. The SBS was measured using a Zwicki 1120™ testing machine. The ARI and SBS were compared statistically using the Kruskal–Wallis test (P ≤ 0.05). Results. Significant differences in SBS and ARI were found between the control group and experimental groups. Conclusions. Transbond XT showed the highest SBS on human enamel. Scotchbond Universal on average provides the best bonding on all other types of surface (metal, composite, and porcelain), with no need for additional primers. It might therefore be helpful for simplifying bonding in orthodontic procedures on restorative materials in patients. If metal brackets have to be bonded to a metal surface, the use of a dual-curing resin is recommended. PMID:27738633

  20. An in vitro comparison of diagnostic accuracy of cone beam computed tomography and phosphor storage plate to detect simulated occlusal secondary caries under amalgam restoration

    PubMed Central

    Shahidi, Shoaleh; Zadeh, Nahal Kazerooni; Sharafeddin, Farahnaz; Shahab, Shahriar; Bahrampour, Ehsan; Hamedani, Shahram

    2015-01-01

    Background: This study was aimed to compare the diagnostic accuracy and feasibility of cone beam computed tomography (CBCT) with phosphor storage plate (PSP) in detection of simulated occlusal secondary caries. Materials and Methods: In this in vitro descriptive-comparative study, a total of 80 slots of class I cavities were prepared on 80 extracted human premolars. Then, 40 teeth were randomly selected out of this sample and artificial carious lesions were created on these teeth by a round diamond bur no. 1/2. All 80 teeth were restored with amalgam fillings and radiographs were taken, both with PSP system and CBCT. All images were evaluated by three calibrated observers. The area under the receiver operating characteristic curve was used to compare the diagnostic accuracy of two systems. SPSS (SPSS Inc., Chicago, IL, USA) was adopted for statistical analysis. The difference between Az value of bitewing and CBCT methods were compared by pairwise comparison method. The inter- and intra-operator agreement was assessed by kappa analysis (P < 0.05). Results: The mean Az value for bitewings and CBCT was 0.903 and 0.994, respectively. Significant differences were found between PSP and CBCT (P = 0.010). The kappa value for inter-observer agreement was 0.68 and 0.76 for PSP and CBCT, respectively. The kappa value for intra-observer agreement was 0.698 (observer 1, P = 0.000), 0.766 (observer 2, P = 0.000) and 0.716 (observer 3, P = 0.000) in PSP method, and 0.816 (observer 1, P = 0.000), 0.653 (observer 2, P = 0.000) and 0.744 (observer 3, P = 0.000) in CBCT method. Conclusion: This in vitro study, with a limited number of samples, showed that the New Tom VGI Flex CBCT system was more accurate than the PSP in detecting the simulated small secondary occlusal caries under amalgam restoration. PMID:25878682

  1. Direct Contra Naïve-Indirect Comparison of Clinical Failure Rates between High-Viscosity GIC and Conventional Amalgam Restorations: An Empirical Study

    PubMed Central

    Mickenautsch, Steffen; Yengopal, Veerasamy

    2013-01-01

    Background Naïve-indirect comparisons are comparisons between competing clinical interventions’ evidence from separate (uncontrolled) trials. Direct comparisons are comparisons within randomised control trials (RCTs). The objective of this empirical study is to test the null-hypothesis that trends and performance differences inferred from naïve-indirect comparisons and from direct comparisons/RCTs regarding the failure rates of amalgam and direct high-viscosity glass-ionomer cement (HVGIC) restorations in permanent posterior teeth have similar direction and magnitude. Methods A total of 896 citations were identified through systematic literature search. From these, ten and two uncontrolled clinical longitudinal studies for HVGIC and amalgam, respectively, were included for naïve-indirect comparison and could be matched with three out twenty RCTs. Summary effects sizes were computed as Odds ratios (OR; 95% Confidence intervals) and compared with those from RCTs. Trend directions were inferred from 95% Confidence interval overlaps and direction of point estimates; magnitudes of performance differences were inferred from the median point estimates (OR) with 25% and 75% percentile range, for both types of comparison. Mann-Whitney U test was applied to test for statistically significant differences between point estimates of both comparison types. Results Trends and performance differences inferred from naïve-indirect comparison based on evidence from uncontrolled clinical longitudinal studies and from direct comparisons based on RCT evidence are not the same. The distributions of the point estimates differed significantly for both comparison types (Mann–Whitney U  =  25, nindirect  =  26; ndirect  =  8; p  =  0.0013, two-tailed). Conclusion The null-hypothesis was rejected. Trends and performance differences inferred from either comparison between HVGIC and amalgam restorations failure rates in permanent posterior teeth are not the same. It is

  2. Bacterial leakage of mineral trioxide aggregate as compared with zinc-free amalgam, intermediate restorative material, and Super-EBA as a root-end filling material.

    PubMed

    Fischer, E J; Arens, D E; Miller, C H

    1998-03-01

    Several dye leakage studies have demonstrated the fact that mineral trioxide aggregate (MTA) leaks significantly less than other root-end filling materials. The purpose of this study was to determine the time needed for Serratia marcescens to penetrate a 3 mm thickness of zinc-free amalgam, Intermediate Restorative Material (IRM), Super-EBA, and MTA when these materials were used as root-end filling materials. Fifty-six, single-rooted extracted human teeth were cleaned and shaped with a series of .04 Taper rotary instruments (Pro-series 29 files). Once the canals were prepared in a crown down approach, the ends were resected and 48 root-end cavities were ultrasonically prepared to a 3 mm depth. The teeth were then steam sterilized. Using an aseptic technique, under a laminar air flow hood, the root-end cavities were filled with amalgam, IRM, Super-EBA, and MTA. Four root-end cavities were filled with thermoplasticized gutta-percha without a root canal sealer and served as positive controls. Another four root-end cavities were filled with sticky wax covered with two layers of nail polish and served as negative controls. The teeth were attached to presterilized (ethylene oxide gas) plastic caps, and the root ends were placed into 12-ml vials of phenol red broth. Using a micropipette, a tenth of a milliliter of S. marcescens was placed into the root canal of each tooth. To test the sterility of the apparatus set-up, the root canals of two teeth with test root-end filling materials and one tooth from the positive and negative control groups were filled with sterile saline. The number of days required for S. marcescens to penetrate the four root-end filling materials and grow in the phenol red broth was recorded and analyzed. Most of the samples filled with zinc-free amalgam leaked bacteria in 10 to 63 days. IRM began leaking 28 to 91 days. Super-EBA began leaking 42 to 101 days. MTA did not begin leaking until day 49. At the end of the study, four of the MTA samples

  3. Phase down of amalgam

    PubMed Central

    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

  4. Shear strength of resin developed by four bonding agents used with cast metal restorations.

    PubMed

    Reilly, B; Davis, E L; Joynt, R B; Quevedo, J

    1992-07-01

    The evolution of the acid etch technique has made possible a more conservative approach to the fabrication of cast metal restorations. The resin bonding technique, however, places a greater burden for success on the selection of a bonding agent. This study examined the shear bond strength durability of cast metal restorations bonded to tooth structure with one of four metal adhesive bonding agents. Results indicated stronger bonds for restorations cemented with Panavia EX bonding agent than with any of the other bonding agents tested, both with and without exposure to thermal stress. Although it was one of the easier materials with which to work, Panavia EX bonding agent requires the additional step of applying an agent to prevent oxygen contact in the setting process.

  5. Dental amalgam and mercury

    SciTech Connect

    Mackert, J.R. Jr. )

    1991-08-01

    This paper looks at the issues of the current amalgam controversy: the daily dose of mercury from amalgam, hypersensitivity to mercury, claims of adverse effects from amalgam mercury and alleged overnight 'cures.' In addition, the toxicity and allergenicity of the proposed alternative materials are examined with the same kind of scrutiny applied by the anti-amalgam group to dental amalgam. 100 references.

  6. Novel Amalgams for In-Space Parts Fabrication

    NASA Technical Reports Server (NTRS)

    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

  7. The influence of a packable resin composite, conventional resin composite and amalgam on molar cuspal stiffness.

    PubMed

    Molinaro, J D; Diefenderfer, K E; Strother, J M

    2002-01-01

    Packable resin composites may offer improved properties and clinical performance over conventional resin composites or dental amalgam. This in vitro study examined the cuspal stiffness of molars restored with a packable resin composite, a conventional posterior microfilled resin composite and amalgam. Forty-eight intact caries-free human third molars were distributed into four treatment groups (n=12) so that the mean cross-sectional areas of all groups were equal. Standardized MOD cavity preparations were made and specimens restored using one of four restorative materials: (1) a spherical particle amalgam (Tytin); (2) Tytin amalgam with a dentin adhesive liner (OptiBond Solo); (3) a conventional microfilled posterior resin composite (Heliomolar); (4) a packable posterior resin composite (Prodigy Posterior). Cuspal stiffness was measured using a Bionix 200 biomaterials testing machine (MTS). Specimens were loaded vertically to 300 N at a crosshead speed of 1.0 mm/minute. Stiffness was measured at 10 intervals: (1) prior to cavity preparation (intact); (2) following cavity preparation, but before restoration; (3) seven days after restoration; then (4) 1, 2, 3, 4, 5, 6 and 12 months after restoration. All specimens were stored at 37 degrees C in deionized water throughout the study and thermocycled (5 degrees/55 degrees C; 2000 cycles) monthly for 12 months. Repeated Measures ANOVA revealed significant differences among treatment groups over time (p<0.0001). Cavity preparation reduced cuspal stiffness by more than 60%. At 12 months, the cuspal stiffness of restored teeth was, on average, 58% that of intact specimens. Neither the packable nor the conventional resin composite increased cuspal stiffness over that of amalgam.

  8. Do Laboratory Results Concerning High-Viscosity Glass-Ionomers versus Amalgam for Tooth Restorations Indicate Similar Effect Direction and Magnitude than that of Controlled Clinical Trials? - A Meta-Epidemiological Study

    PubMed Central

    Mickenautsch, Steffen; Yengopal, Veerasamy

    2015-01-01

    Background A large percentage of evidence concerning dental interventions is based on laboratory research. The apparent wealth of laboratory evidence is sometimes used as basis for clinical inference and recommendations for daily dental practice. In this study two null-hypotheses are tested: whether trial results from laboratory and controlled clinical trials concerning the comparison of high-viscosity glass-ionomer cements (HVGIC) to amalgam for restorations placed in permanent posterior teeth have: (i) similar effect direction and (ii) similar effect magnitude. Methods 7 electronic databases were searched, as well as reference lists. Odds ratios (OR) and Standardised Mean Differences (SMD) with 95% Confidence intervals were computed for extracted dichotomous and continuous data, respectively. Pooled effect estimates for laboratory and clinical data were computed to test for effect direction. Odds ratios were converted into SMDs. SMDs from laboratory and clinical data were statistically compared to test for differences in effect magnitude. The analysed results were further investigated within the context of potential influencing or confounding factors using a Directed acyclic graph. Results Of the accepted eight laboratory and nine clinical trials, 13 and 21 datasets could be extracted, respectively. The pooled results of the laboratory datasets were highly statistically significant in favor of amalgam. No statistically significant differences, between HVGICs and amalgam, were identified for clinical data. For effect magnitude, statistically significant differences between clinical and laboratory trial results were found. Both null-hypotheses were rejected. Conclusion Laboratory results concerning high-viscosity glass-ionomers versus amalgam for tooth restorations do not indicate similar effect direction and magnitude than that of controlled clinical trials. PMID:26168274

  9. [Dentin bonding of cements. The bonding of cements with dentin in combination with various indirect restorative materials].

    PubMed

    Peutzfeldt, Anne; Sahafi, Alireza; Flury, Simon

    2011-01-01

    The number of both luting agents and restorative materials available on the market has rapidly increased. This study compared various types of luting agents when used to bond different indirect, laboratory restorative materials to dentin. Cylinders were produced of six restorative materials (gold alloy, titanium, feldspathic porcelain, leucite-glass ceramic, zirconia, and an indirect resin composite). Following relevant pretreatment, the end surface of the cylinders were luted to ground, human dentin with eight different luting agents (DeTrey Zinc [zinc phosphate cement], Fuji I [conventional glass ionomer cement], Fuji Plus [resin-modified glass ionomer cement], Variolink II [conventional etch-and-rinse resin cement], Panavia F2.0 and Multilink [self-etch resin cements], RelyX Unicem Aplicap and Maxcem [self-adhesive resin cements]). After water storage at 37 °C for one week, the shear bond strength of the specimens was measured and the fracture mode was examined stereo-microscopically. Restorative material and luting agent both had a significant effect on bond strength and there was a significant interaction between the two variables. The zinc phosphate cement and the glass ionomer cements resulted in the lowest bond strengths, whereas the highest bond strengths were found with the two self-etch and one of the self-adhesive resin cements.

  10. The effects of glass ionomer and flowable composite liners on the fracture resistance of open-sandwich class II restorations.

    PubMed

    Güray Efes, Begüm; Yaman, Batu Can; Gümüştaş, Burak; Tıryakı, Murat

    2013-01-01

    This in vitro study aimed to investigate the effects of glass-ionomer and flowable composite liners on the fracture resistance of Class II amalgam and composite restorations. Group 1 cavities were restored with amalgam and Group 4 cavities with nanofill composite after the application of a dentin-bonding agent. For the remaining groups, light-cured-glass-ionomer liner was used in a gingival floor proximal box (Groups 2, 5) or flowable composite was used as a liner (Groups 3, 6), the remainder of the cavity was restored with amalgam (Groups 2, 3) or composite (Groups 5, 6). The restorations were loaded in compression to failure. The data was analyzed using Tukey's multiple comparison test. The fracture resistance was significantly higher (p<0.05) in Group 3 than in all other groups, except Group 2 (p>0.05). Flowable composite, glass-ionomer liners increased the fracture resistance of open-sandwich Class II amalgam restorations.

  11. Comparative in vitro study of the shear bond strength of brackets bonded with restorative and orthodontic resins.

    PubMed

    Isber, Hassan; Ambrosio, Aldrieli Regina; Carvalho, Paulo Eduardo Guedes; Valle-Corotti, Karyna Martins do; Siqueira, Danilo Furquim

    2011-01-01

    The aim of this study was to evaluate the shear bond strength of brackets bonded with different restorative systems and compare it with that afforded by an established orthodontic bonding system. Seventy human bicuspids were used, divided into five different groups with 14 teeth each. Whereas a specific orthodontic bonding resin (Transbond™ XT) was used in the control group, the restorative systems Charisma, Tetric Ceram, TPH Spectrum and Z100 were used in the other four groups. Seven days after bonding the brackets to the samples, shear forces were applied under pressure in a universal testing machine. The data collected was evaluated using the ANOVA test and, when a difference was identified, the Tukey test was applied. A 5% level of significance was adopted. The mean results of the shear bond strength tests were as follows: Group 1 (Charisma), 14.98 MPa; Group 2 (Tetric Ceram), 15.16 MPa; Group 3 (TPH), 17.70 MPa; Group 4 (Z100), 13.91 MPa; and Group 5 or control group (Transbond™ XT), 17.15 MPa. No statistically significant difference was found among the groups. It was concluded that all tested resins have sufficient bond strength to be recommended for bonding orthodontic brackets.

  12. Effect of surface roughness on amalgam repair using adhesive systems.

    PubMed

    Giannini, Marcelo; Paulillo, Luis Alexandre Maffei Sartini; Ambrosano, Gláucia Maria Bovi

    2002-01-01

    The objective of this in vitro study was to evaluate the effect of three surface treatments and two adhesive systems on the shear bond strength of old and freshly placed amalgam. The results suggested that the intact amalgam showed a significantly higher strength than repaired groups and the strongest repaired specimens were made when the amalgam surfaces were roughened with a diamond bur or microetcher. The adhesive systems showed no significant differences on bond strength with the same superficial texture.

  13. Has resin-based composite replaced amalgam?

    PubMed

    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.

  14. [The impact of ultrasonic dental hygiene procedures on the bonding strength of restorations].

    PubMed

    Kuznetsov, D L; Mel'nik, A A; Laze, R; Petrikas, O A; Petrikas, I V

    2013-01-01

    Ultrasonic calculus scaling has become a common oral hygiene procedure in patients with composite restorations, dental veneers, orthodontic brackets. The aim of the study was to evaluate in vitro the influence of the EMS-ultrasonic system scaling on the flowable composite bond strength to the tooth enamel, dentine, and e-max ceramic. The samples were divided into three groups: 1 group (composite bonded to enamel), 2 group (composite bonded to dentine), 3 group (composite bonded to e-max ceramic). The bonded samples were loaded to failure in the universal testing machine. The shear bond strength was calculated in newtons (N). T (Student's)-test was used to evaluate the data. Significantly lower bond strengths were observed with the ultrasonic treated samples in each groups. The EMS-ultrasonic system scaling significantly decreases the flowable composite bond strength to the tooth enamel, dentine, and e-max ceramic.

  15. Shear bond strengths of self-adhesive luting resins fixing dentine to different restorative materials.

    PubMed

    Zhang, Congxiao; Degrange, Michel

    2010-01-01

    The purpose of this study was to assess the bond strengths of three self-adhesive resin cements (Rely X Unicem, Maxcem and Multilink Sprint) fixing dentine to four different restorative substrates (Ni-Cr alloy, E-Max glass-ceramic, Y-TZP Zirconia and Adoro micro-filled composite) and to compare their performances with those of two conventional dual-cured luting cements (Variolink II + Total-etch Excite DSC and Multilink Automix + Self-etching Primer A + B). Cylindric specimens (5 x 5 mm) were prepared with the four restorative materials for bonding to human dentine. Three surface treatments were performed depending on the restorative material: (i) Al2O3 50 microm sandblasting (Ni-Cr, Adoro), (ii) #800 SiC polishing (Zirconia, E-Max), (iii) hydrofluoric acid (HF)-etching (E-Max). Twenty-five groups (n = 10) were designed according to luting cements, restorative materials and surface pre-treatments. In some experimental groups, Variolink II and Multilink Automix were coupled with, respectively, a silane primer (Monobond S) and an alloy/zirconia primer (Multilink A/Z primer). Specimens were stored in distilled water at 37 degrees C for 24 h and then loaded in shear until failure. Variolink II and Multilink Automix showed the highest bond strengths, regardless of the restorative substrate, when used with dentine bonding systems and primers, while the weakest bonds were with Maxcem. The bond strength recorded with the two other self-adhesive cements depended on the nature of the restorative substrate. Increasing retention at the interfaces (i.e., HF ceramic etching) and using specific primers significantly improves the bond strength of luted restorative materials to dentine.

  16. Effect of provisional restorations on the final bond strengths of porcelain laminate veneers.

    PubMed

    Aykent, F; Usumez, A; Ozturk, A N; Yucel, M T

    2005-01-01

    The purpose of this in vitro study was to evaluate the effect of the different provisional restorations cementation techniques on the final bond strengths of porcelain laminate veneers (PLVs). Thirty-six extracted human central incisors were sectioned 2 mm below the cemento-enamel junction, and crown parts were embedded into self-cure acrylic resin. Standardized PLV preparations were carried out on labial surfaces of the teeth. Then the teeth were randomly divided into three groups of 12 each. In group 1, provisional restorations were cemented with eugenol-free cement. In group 2, prepared teeth surfaces were first coated with a desensitizing agent then provisional restorations were cemented with resin cement. In group 3, provisional restorations were not fabricated to serve as control. After specimens were stored in distilled water for 2 weeks, provisional restorations were removed and final IPS Empress 2 ceramic veneers were bonded with a dual-curing resin. Two microtensile samples from each tooth measuring 1.2 x 1.2 x 5 mm were prepared. These sections were subjected to microtensile testing and failure values were recorded. The data were analysed by one-way anova and Tukey HSD tests. The PLVs, placed on the tooth surface that had received a dentine desensitizer and provisional restorations luted with resin cement (group 2), showed the lowest bond strength in all test groups. But no statistically significant differences were found between the bond strength of PLVs in control group (no provisional restorations) and group 1 (provisional restorations cemented with eugenol-free cement before final cementations). Scanning electron microscopic (SEM) examination of this study also showed that the bonding to enamel surface was better in control group and group 1 than group 2.

  17. About Dental Amalgam Fillings

    MedlinePlus

    ... documents in the Related Resources section. Why is mercury used in dental amalgam? Approximately half of a ... about bioaccumulation, please see Related Resources. Is the mercury in dental amalgam the same as the mercury ...

  18. Treatment of extended anterior crown fractures using Type IIIA bonded porcelain restorations.

    PubMed

    Magne, Pascal; Magne, Michel

    2005-05-01

    Novel-design bonded porcelain restorations, the so-called Type IIIA BPRs, represent a reliable and effective procedure when restoring large parts of the coronal volume and length in the anterior dentition. While traditional treatment approaches involve the removal of large amounts of sound tooth substance (with adverse effects on the pulp, gingivae and crown biomechanics, as well as serious financial consequences), the use of adhesive technology instead can provide maximum preservation of tissues and limited costs. Considerable advantages, such as the economical and noninvasive treatment of crown-fractured teeth, are inherent to Type IIIA bonded porcelain restorations, reducing the need for preprosthetic interventions (e.g., root canal therapy and crown-lengthening) and the use of intraradicular posts. This article, illustrated with cases with up to eight and 10 years' follow-up, sets the scientific foundations of this concept, as well as important considerations about function, strength, tooth preparation, laboratory technique, and bonding optimization.

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

    PubMed Central

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

    2016-01-01

    Statement of the Problem: Similar to conventional amalgam, high-copper amalgam alloy may also undergo corrosion, but it takes longer time for the resulting products to reduce microleakage by sealing the micro-gap at the tooth/amalgam interface. Purpose: The aim of this study was to evaluate the effect of self-etch adhesives with different pH levels on the interfacial corrosion behavior of high-copper amalgam restoration and its induction potential for self-sealing ability of the micro-gap in the early hours after setting by means of Electro-Chemical Tests (ECTs). Materials and Method: Thirty cylindrical cavities of 4.5mm x 4.7mm were prepared on intact bicuspids. The samples were divided into five main groups of application of Adhesive Resin (AR)/ liner/ None (No), on the cavity floor. The first main group was left without an AR/ liner (No). In the other main groups, the types of AR/ liner used were I-Bond (IB), Clearfil S3 (S3), Single Bond (SB) and Varnish (V). Each main group (n=6) was divided into two subgroups (n=3) according to the types of the amalgams used, either admixed ANA 2000 (ANA) or spherical Tytin (Tyt). The ECTs, Open Circuit Potential (OCP), and the Linear Polarization Resistance (LPR) for each sample were performed and measured 48 hours after the completion of the samples. Results: The Tyt-No and Tyt-IB samples showed the highest and lowest OCP values respectively. In LPR tests, the Rp values of ANA-V and Tyt-V were the highest (lowest corrosion rate) and contrarily, the ANA-IB and Tyt-IB samples, with the lowest pH levels, represented the lowest Rp values (highest corrosion rates). Conclusion: Some self-etch adhesives may increase interfacial corrosion potential and self-sealing ability of high-copper amalgams. PMID:27942548

  20. Human brain mercury levels related to exposure to amalgam fillings.

    PubMed

    Ertaş, E; Aksoy, A; Turla, A; Karaarslan, E S; Karaarslan, B; Aydın, A; Eken, A

    2014-08-01

    The safety of dental amalgam as the primary material in dental restoration treatments has been debated since its introduction. It is widely accepted that amalgam restorations continuously release elemental mercury (Hg) vapor, which is inhaled and absorbed by the body and distributed to tissues, including the brain. The aim of the present study was to investigate whether the presence of amalgam fillings is correlated with brain Hg level. The Hg levels in the parietal lobes of the brains of 32 cadavers were analyzed with an atomic absorption spectrometer with the mercury hydride system. A total of 32 brain samples were tested; of these, 10 were from cadavers with amalgam fillings, while 22 of them were amalgam free. Hg was detected in 60.0% (6 of 10) of the samples in the amalgam group and in 36.3% (8 of 22) in the amalgam-free group. The average Hg level of the amalgam group was 0.97 ± 0.83 µg/g (minimum: 0.3 µg/g and maximum: 2.34 µg/g), and in the amalgam-free group, it was 1.06 ± 0.57 µg/g (minimum: 0.17 µg/g and maximum: 1.76 µg/g). The results of the present study showed no correlation between the presence of amalgam fillings and brain Hg level.

  1. Eroded dentin does not jeopardize the bond strength of adhesive restorative materials.

    PubMed

    Cruz, Janaina Barros; Lenzi, Tathiane Larissa; Tedesco, Tamara Kerber; Guglielmi, Camila de Almeida Brandão; Raggio, Daniela Prócida

    2012-01-01

    This in vitro study evaluated the bond strength of adhesive restorative materials to sound and eroded dentin. Thirty-six bovine incisors were embedded in acrylic resin and ground to obtain flat buccal dentin surfaces. Specimens were randomly allocated in 2 groups: sound dentin (immersion in artificial saliva) and eroded dentin (pH cycling model - 3× / cola drink for 7 days). Specimens were then reassigned according to restorative material: glass ionomer cement (KetacTM Molar Easy Mix), resin-modified glass ionomer cement (VitremerTM) or adhesive system with resin composite (Adper Single Bond 2 + Filtek Z250). Polyethylene tubes with an internal diameter of 0.76 mm were placed over the dentin and filled with the material. The microshear bond test was performed after 24 h of water storage at 37ºC. The failure mode was evaluated using a stereomicroscope (400×). Bond strength data were analyzed with two-way ANOVA and Tukey's post hoc tests (α = 0.05). Eroded dentin showed bond strength values similar to those for sound dentin for all materials. The adhesive system showed the highest bond strength values, regardless of the substrate (p < 0.0001). For all groups, the adhesive/mixed failure prevailed. In conclusion, adhesive materials may be used in eroded dentin without jeopardizing the bonding quality. It is preferable to use an etch-and-rinse adhesive system because it shows the highest bond strength values compared with the glass ionomer cements tested.

  2. Impact of intracoronal dentin treatment prior to bleaching on bond strength of restorative materials.

    PubMed

    Zanconato-Carvalho, Erica Moreno; Bruniera, João Felipe; Faria, Natália Spadini de; Colucci, Vivian; Messias, Danielle Cristine

    2014-01-01

    Surface treatment of dentin before the bleaching procedure may affect its permeability and influence the bond strength of restorative materials. This study evaluated the influence of surface treatment before the bleaching on shear bond strength (SBT) of restorative materials to intracoronal dentin. Dentin slabs were subjected to surface treatment: no bleaching (control - CON), no surface treatment + bleaching (HP), 37% phosphoric acid + bleaching (PA) and Er:YAG laser + bleaching (L). After the bleaching procedure, specimens (n=10) were restored with: microhybrid composite resin (MH), flowable composite resin (F), and resin-modified glass-ionomer cement (RMGIC). The shear test was carried out. ANOVA and Tukey's test (α=0.05) showed significant difference for surface treatment and restorative materials (p<0.05). CON presented higher STB and was statistically different from HP (p<0.05). PA and L showed intermediate values and were statistically similar to CON and HP (p>0.05). STB for MH and F were higher than RMGIC (p<0.05), and did not differ from each other (p>0.05). The surface treatments with phosphoric acid and Er:YAG laser before the bleaching procedure provided shear bond strength at the same level of unbleached dentin and the composite resins presented superior bond strength to the intracoronal dentin.

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

    PubMed

    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.

  4. The Dental Amalgam Toxicity Fear: A Myth or Actuality

    PubMed Central

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

    2012-01-01

    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. PMID:22778502

  5. Bonding of flowable resin composite restorations to class 1 occlusal cavities with and without cyclic load stress.

    PubMed

    Kawai, Takatoshi; Maseki, Toshio; Nara, Yoichiro

    2016-01-01

    To examine the bonding of flowable resin composite restorations (F-restoration) to class 1 occlusal cavities with and without cyclic load stress, compared with that of a universal resin composite restoration (U-restoration). Two flowable composites and one universal composite (control) were applied with an adhesive system to 42 standardized class 1 occlusal cavities. The restored specimens were subjected to cyclic load stress and no stress modes. The microtensile bond strength (μ-TBS) of the dentin floor was measured. The U-restoration did not show pretesting failure. The F-restorations exhibited pretesting failure, regardless of the stress mode. The μ-TBS was not significantly different among the three restorations, regardless of the stress mode. The cyclic load stress did not influence the μ-TBS of the F-restorations; however, it significantly reduced μ-TBS in the U-restoration. The bonding reliability of the F-restorations was inferior to that of the U-restoration, for both stress modes.

  6. A comparison of fracture resistance of endodontically treated teeth restored with bonded partial restorations and full-coverage porcelain-fused-to-metal crowns.

    PubMed

    Gupta, Abhishek; Musani, Smita; Dugal, Ramandeep; Jain, Nikhil; Railkar, Bhargavi; Mootha, Ajay

    2014-01-01

    The aim of this study was to evaluate the use of bonded partial restorations compared with full-coverage porcelain-fused-to-metal (PFM) crowns as a viable treatment option for endodontically treated posterior teeth. Forty-five recently extracted maxillary first premolars were collected, endodontically treated, and mounted in acrylic blocks. The specimens were randomly divided into three groups and prepared to receive their respective restorations. The teeth in group 1 received full-coverage porcelain-fused-to-metal crowns. The teeth in group 2 received bonded partial restorations made from pressed ceramics (lithium disilicate) involving a functional cusp (palatal). Finally, group 3 received bonded partial restorations made from pressed ceramics involving the buccal cusp and keeping a functional cusp (palatal) intact. All group 1 restorations were cemented using glass ionomer cement. Restorations in groups 2 and 3 were bonded using a dual-cured resin cement. All specimens were subjected to an aging process and tested for shear bond strength using a universal loading machine. The mean force applied in Newtons to cause failure for group I was 674.90 ± 94.16 N, for group 2, 463.46 ± 61.11 N, and for group 3, 849.33 ± 68.92 N. P values obtained using one-way analysis of variance showed a highly significant difference between groups 2 and 3 (P = .001), groups 1 and 2 (P = .001), and groups 1 and 3 (P = .001). The fracture modes observed in all groups involved restorations and tooth fracture. This in vitro study suggests that endodontically treated posterior teeth with intact functional cusps can be restored with bonded partial porcelain restorations. However, if the loss of tooth structure involves the functional cusp, full-coverage PFM crowns are the treatment of choice.

  7. Orofacial granulomatosis related to amalgam fillings.

    PubMed

    Ellison, R; Green, C; Gibson, J; Ghaffar, S

    2013-11-01

    This paper reports on a case of Orofacial Granulomatosis (OFG) in which the presence of amalgam fillings appears to have played a part in the aetiology. Once these restorations were removed and replaced with an alternative composite restorative material, all symptoms and signs of OFG resolved completely. This case highlights the necessity to include dental metals in the patch test battery when performing delayed patch testing on patients with OFG.

  8. DESENSITIZING BIOACTIVE AGENTS IMPROVES BOND STRENGTH OF INDIRECT RESIN-CEMENTED RESTORATIONS: PRELIMINARY RESULTS

    PubMed Central

    Pires-De-Souza, Fernanda de Carvalho Panzeri; de Marco, Fabíola Fiorezi; Casemiro, Luciana Assirati; Panzeri, Heitor

    2007-01-01

    Objective: The aim of this study was to assess the bond strength of indirect composite restorations cemented with a resin-based cement associated with etch-and-rinse and self-etching primer adhesive systems to dentin treated or not with a bioactive material. Materials and Method: Twenty bovine incisor crowns had the buccal enamel removed and the dentin ground flat. The teeth were assigned to 4 groups (n=5): Group I: acid etching + Prime & Bond NT (Dentsply); Group II: application of a bioactive glass (Biosilicato®)+ acid etching + Prime & Bond NT; Group III: One-up Bond F (J Morita); Group IV: Biosilicato® + One-up Bond F. Indirect composite resin (Artglass, Kulzer) cylinders (6x10mm) were fabricated and cemented to the teeth with a dualcure resin-based cement (Enforce, Dentsply). After cementation, the specimens were stored in artificial saliva at 37oC for 30 days and thereafter tested in tensile strength in a universal testing machine (EMIC) with 50 kgf load cell at a crosshead speed of 1 mm/min. Failure modes were assessed under scanning electron microscopy. Data were analyzed statistically by ANOVA and Tukey's test (95% level of confidence). Results: Groups I, II and III had statistically similar results (p>0.05). Group IV had statistically significant higher bond strength means (p<0.05) than the other groups. The analysis of the debonded surfaces showed a predominance of adhesive failure mode for Group III and mixed failure mode for the other groups. Conclusion: The use of desensitizing agent did not affect negatively the bonding of the indirect composite restorations to dentin, independently of the tested adhesive systems. PMID:19089114

  9. Use of resin-bonded partial coverage ceramic restorations to treat incomplete fractures in posterior teeth: a clinical report.

    PubMed

    Liebenberg, W H

    1996-11-01

    The objective of restorative treatment of teeth with incomplete fractures is to minimize flexure of the compromised cusps to prevent propagation of the crack. These goals can be addressed with resin-bonded posterior ceramic restorations, but long-term integrity rests on the efficiency of the restoration's bond to the dental hard tissues. Success is dependent on diligent operative performance throughout the entire procedure. Some tips for achieving successful preparation, provisionalization, and partial-coverage restoration of the incompletely fractured posterior tooth are discussed.

  10. Electrical activity in dental amalgam of submerged divers during welding.

    PubMed

    Ortendahl, T W; Holland, R I

    1987-10-01

    Divers performing underwater manual metal arc welding/cutting (UMMA) have complained about a metallic taste phenomenon. In several dives with voluntary leakage in their diving suits, potential alterations in dental amalgam were registered when they performed UMMA. Polarization resistance values were obtained for the test amalgam cylinders used and the diver's dental restorations. These values, along with the recorded potential values of the amalgam test cylinders and of the diver's dental restorations, enabled us to calculate the depolarizing current, using the law of Ohm. The current depolarizing the amalgam test cylinder did not differ significantly from the mean intermetallic currents between the dental restorations. The clinical effect of intraoral currents when performing UMMA welding should be regarded as small, whereas considerably higher currents should not be ruled out in an intense cutting situation.

  11. Crevice corrosion products of dental amalgam

    SciTech Connect

    Sutow, E.J.; Jones, D.W.; Hall, G.C.; Owen, C.G. )

    1991-07-01

    The objective of this study was to determine the in vitro corrosion products that resulted from crevice corrosion of low- and high-copper dental amalgams. Specimens were potentiostatically polarized in a chloride-containing electrolyte while set against a PTFE surface to form a crevice. After 16 h, corrosion products were examined by light microscopy, SEM, EDS, and XRD. Analysis showed the presence of three previously reported products (Sn4(OH)6Cl2, SnO, and Cu2O) and a new product, CuCl, which formed on high-copper, {gamma} 2-free amalgams. Thermodynamic considerations show that CuCl is stable for the reported in vivo potentials of amalgam restorations and the high acidity and high chloride ion concentration associated with crevice corrosion.

  12. Maternal-fetal distribution of mercury ( sup 203 Hg) released from dental amalgam fillings

    SciTech Connect

    Vimy, M.J.; Takahashi, Y.; Lorscheider, F.L. )

    1990-04-01

    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.

  13. Shear bond strengths of resin-modified glass-ionomer restorative materials.

    PubMed

    Swift, E J; Pawlus, M A; Vargas, M A

    1995-01-01

    The purpose of this study was to evaluate the shear bond strength of resin-modified glass-ionomer restorative materials to dentin. The materials tested were Fuji II LC, Geristore, Photac-Fil, VariGlass VLC, and Vitremer. Ketac-Fil, a conventional glass ionomer, was used as the control. The occlusal surfaces of 60 extracted molars were ground flat in dentin using 600-grit silicon carbide abrasive paper. Dentin surfaces were treated according to manufacturers' instructions, and restorative materials were applied using gelatin capsule matrices. Shear bond strengths were determined after the specimens were thermocycled 500 times. Mean bond strengths of the resin-modified glass ionomers ranged from 1.4 MPa (Photac-Fil) to 12.3 MPa (Fuji II LC). Except for Photac-Fil, all values were significantly higher than the control. Pairwise comparisons between the means for Fuji II LC and Vitremer, Vitremer and Geristore, and Geristore and VariGlass were not significantly different.

  14. Shear bond strength of bulk-fill and nano-restorative materials to dentin

    PubMed Central

    Colak, Hakan; Ercan, Ertugrul; Hamidi, Mehmet Mustafa

    2016-01-01

    Objectives: Bulk-fill composite materials are being developed for preparation depths of up to 4 mm in an effort to simplify and improve the placement of direct composite posterior restorations. The aim of our study was to compare shear-bond strength of bulk-fill and conventional posterior composite resins. Materials and Methods: In this study, 60 caries free extracted human molars were used and sectioned parallel to occlusal surface to expose midcoronal dentin. The specimens were randomly divided into four groups. Total-etch dentine bonding system (Adper Scotchbond 1XT, 3M ESPE) was applied to dentin surface in all the groups to reduce variability in results. Then, dentine surfaces covered by following materials. Group I: SonicFill Bulk-Fill, Group II: Tetric EvoCeram (TBF), Group III: Herculite XRV Ultra, and Group IV: TBF Bulk-Fill, 2 mm × 3 mm cylindrical restorations were prepared by using application apparatus. Shear bond testing was measured by using a universal testing machine. Kruskal–Wallis and Mann–Whitney U-tests were performed to evaluate the data. Results: The highest value was observed in Group III (14.42 ± 4.34) and the lowest value was observed in Group IV (11.16 ± 2.76) and there is a statistically significant difference between these groups (P = 0.046). However, there is no statistically significant difference between the values of other groups. In this study, Group III was showed higher strength values. Conclusion: There is a need for future studies about long-term bond strength and clinical success of these adhesive and bulk-fill systems. PMID:27011738

  15. Push-Out Bond Strength of Restorations with Bulk-Fill, Flow, and Conventional Resin Composites

    PubMed Central

    Caixeta, Rodrigo Vieira; Guiraldo, Ricardo Danil; Kaneshima, Edmilson Nobumitu; Barbosa, Aline Silvestre; Picolotto, Cassiana Pedrotti; Lima, Ana Eliza de Souza; Gonini Júnior, Alcides; Berger, Sandrine Bittencourt

    2015-01-01

    The aim of this study was to evaluate the bond strengths of composite restorations made with different filler amounts and resin composites that were photoactivated using a light-emitting diode (LED). Thirty bovine incisors were selected, and a conical cavity was prepared in the facial surface of each tooth. All preparations were etched with Scotchbond Etching Gel, the Adper Scotchbond Multipurpose Plus adhesive system was applied followed by photoactivation, and the cavities were filled with a single increment of Filtek Z350 XT, Filtek Z350 XT Flow, or bulk-fill X-tra fil resin composite (n = 10) followed by photoactivation. A push-out test to determine bond strength was conducted using a universal testing machine. Data (MPa) were submitted to Student's t-test at a 5% significance level. After the test, the fractured specimens were examined using an optical microscope under magnification (10x). Although all three composites demonstrated a high prevalence of adhesive failures, the bond strength values of the different resin composites photoactivated by LED showed that the X-tra fil resin composite had a lower bond strength than the Filtek Z350 XT and Filtek Z350 XT Flow resin composites. PMID:26457322

  16. Bond and fracture strength of metal-ceramic restorations formed by selective laser sintering

    PubMed Central

    Bae, Eun-Jeong; Kim, Woong-Chul; Kim, Hae-Young

    2014-01-01

    PURPOSE The purpose of this study was to compare the fracture strength of the metal and the bond strength in metal-ceramic restorations produced by selective laser sintering (SLS) and by conventional casting (CAST). MATERIALS AND METHODS Non-precious alloy (StarLoy C, DeguDent, Hanau, Germany) was used in CAST group and metal powder (SP2, EOS GmbH, Munich, Germany) in SLS group. Metal specimens in the form of sheets (25.0 × 3.0 × 0.5 mm) were produced in accordance with ISO 9693:1999 standards (n=30). To measure the bond strength, ceramic was fired on a metal specimen and then three-point bending test was performed. In addition, the metal fracture strength was measured by continuing the application of the load. The values were statistically analyzed by performing independent t-tests (α=.05). RESULTS The mean bond strength of the SLS group (50.60 MPa) was higher than that of the CAST group (46.29 MPa), but there was no statistically significant difference. The metal fracture strength of the SLS group (1087.2 MPa) was lower than that of the CAST group (2399.1 MPa), and this difference was statistically significant. CONCLUSION In conclusion the balling phenomenon and the gap formation of the SLS process may increase the metal-ceramic bond strength. PMID:25177469

  17. 43 CFR 3215.12 - What will BLM do if I do not restore the face amount or file a new bond?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... face amount or file a new bond? 3215.12 Section 3215.12 Public Lands: Interior Regulations Relating to... restore the face amount or file a new bond? If we collect against your bond and you do not restore it to the original face amount, we may shut in any well(s) or utilization facilities covered by that...

  18. 43 CFR 3215.12 - What will BLM do if I do not restore the face amount or file a new bond?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... face amount or file a new bond? 3215.12 Section 3215.12 Public Lands: Interior Regulations Relating to... restore the face amount or file a new bond? If we collect against your bond and you do not restore it to the original face amount, we may shut in any well(s) or utilization facilities covered by that...

  19. 43 CFR 3215.12 - What will BLM do if I do not restore the face amount or file a new bond?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... face amount or file a new bond? 3215.12 Section 3215.12 Public Lands: Interior Regulations Relating to... restore the face amount or file a new bond? If we collect against your bond and you do not restore it to the original face amount, we may shut in any well(s) or utilization facilities covered by that...

  20. 43 CFR 3215.12 - What will BLM do if I do not restore the face amount or file a new bond?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... face amount or file a new bond? 3215.12 Section 3215.12 Public Lands: Interior Regulations Relating to... restore the face amount or file a new bond? If we collect against your bond and you do not restore it to the original face amount, we may shut in any well(s) or utilization facilities covered by that...

  1. Bonding performance and interfacial characteristics of short fiber-reinforced resin composite in comparison with other composite restoratives.

    PubMed

    Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

    2016-06-01

    The purpose of this study was to investigate the shear bond strength (SBS) and surface free-energy (SFE) of short fiber-reinforced resin composite (SFRC), using different adhesive systems, in comparison with other composite restoratives. The resin composites used were everX Posterior (EP), Clearfil AP-X (CA), and Filtek Supreme Ultra Universal Restorative (FS). The adhesive systems used were Scotchbond Multi-Purpose (SM), Clearfil SE Bond (CS), and G-Premio Bond (GB). Resin composite was bonded to dentin, and SBS was determined after 24 h of storage in distilled water and after 10,000 thermal cycles (TCs). The SFEs of the resin composites and the adhesives were determined by measuring the contact angles of three test liquids. The SFE values and SFE characteristics were not influenced by the type of resin composite, but were influenced by the type of adhesive system. The results of this study suggest that the bonding performance and interfacial characteristics of SFRC are the same as for other composite restoratives, but that these parameters are affected by the type of adhesive system. The bonding performance of SFRC was enhanced by thermal cycling in a manner similar to that for other composite restoratives.

  2. An effect of immediate dentin sealing on the shear bond strength of resin cement to porcelain restoration

    PubMed Central

    Cho, In-Ho

    2010-01-01

    PURPOSE The aim of this study was to determine differences in shear bond strength to human dentin using immediate dentin sealing (IDS) technique compared to delayed dentin sealing (DDS). MATERIALS AND METHODS Forty extracted human molars were divided into 4 groups with 10 teeth each. The control group was light-cured after application of dentin bonding agent (Excite® DSC) and cemented with Variolink® II resin cement. IDS/SE (immediate dentin sealing, Clearfil™ SE Bond) and IDS/SB (immediate dentin sealing, AdapterTM Single Bond 2) were light-cured after application of dentin bonding agent (Clearfil™ SE Bond and Adapter™ Sing Bond 2, respectively), whereas DDS specimens were not treated with any dentin bonding agent. Specimens were cemented with Variolink® II resin cement. Dentin bonding agent (Excite® DSC) was left unpolymerized until the application of porcelain restoration. Shear strength was measured using a universal testing machine at a speed of 5 mm/min and evaluated of fracture using an optical microscope. RESULTS The mean shear bond strengths of control group and IDS/SE group were not statistically different from another at 14.86 and 11.18 MPa. Bond strength of IDS/SE group had a significantly higher mean than DDS group (3.14 MPa) (P < .05). There were no significance in the mean shear bond strength between IDS/SB (4.11 MPa) and DDS group. Evaluation of failure patterns indicates that most failures in the control group and IDS/SE groups were mixed, whereas failures in the DDS were interfacial. CONCLUSION When preparing teeth for indirect ceramic restoration, IDS with Clearfil™ SE Bond results in improved shear bond strength compared with DDS. PMID:21165186

  3. Dental amalgam: is this the end?

    PubMed

    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".

  4. Restorative resins: hardness and strength vs. quantity of remaining double bonds.

    PubMed

    Asmussen, E

    1982-12-01

    It has been hypothesized that the Wallace indentation hardness of smooth surface resins is a factor of prime importance for the abrasion by food of Class 1 restorations. In the present work factors affecting the hardness of polymers were investigated. In addition the tensile strength of composite resins was measured and related to the catalytic system of the polymer. It was found that for a given composition of the monomer the Wallace hardness number increased with increasing content of inhibitor, decreased with increasing content of peroxide, and was unaffected by changes in the content of amine. The hardness was well correlated with the quantity of double bonds remaining in the polymer. BISGMA-based polymers showed no variation in hardness when the originating monomer varied with respect to content of a bi- or a trifunctional diluting monomer. Light-polymerized polymers were relatively hard as compared to chemically cured materials of adequate setting time. The tensile strength of composite resins was predominantly determined by the monomer content of peroxide and increased herewith. The tensile strength was well correlated with the quantity of remaining double bonds in the constituting polymer.

  5. Dentin bonding performance and interface observation of an MMA-based restorative material.

    PubMed

    Shinagawa, Junichi; Inoue, Go; Nikaido, Toru; Ikeda, Masaomi; Sadr, Alireza; Tagami, Junji

    2016-07-30

    The purpose of this study was to evaluate bonding performance and dentin interface acid resistance using a 4-META/MMA-TBB based restorative material (BF) compared to a conventional 4-META/MMA-TBB resin cement (SB), and the effect of sodium fluoride (NaF) addition to the materials. Dentin surfaces were treated with 10% citric acid-3% ferric chloride (10-3) or 4-META containing self-etching primer (TP), followed by application of BF or SB polymer powders with or without NaF, to evaluate microtensile bond strength (µTBS) in six experimental groups; 10-3/SB, 10-3/BF, TP/SB, TP/BF, TP/SB/NaF and TP/BF/NaF. SEM observation of the resin-dentin interface was performed after acid-base challenge to evaluate interfacial dentin resistance to acid attack. TP/BF showed highest µTBS, while NaF polymers decreased µTBS. TP/BF showed funnel-shaped erosion at the interface, however, NaF polymers improved acid resistance of interface. In conclusion, BF demonstrated high µTBSs and low acid-resistance at the interface. NaF addition enhanced acid resistance but decreased µTBS.

  6. The effect of prophylaxis method on microtensile bond strength of indirect restorations to dentin.

    PubMed

    Soares, C J; Pereira, J C; Souza, S J B; Menezes, M S; Armstrong, S R

    2012-01-01

    The aim of this study was to evaluate the effect of different materials used for dentin prophylaxis on the microtensile bond strengths (μTBS) of adhesively cemented indirect composite restorations. Sixty bovine incisors had the buccal surface ground with wet #600-grit silicon carbide abrasive paper to obtain a flat exposed superficial dentin and were submitted to different prophylaxis protocols, as follows: 3% hydrogen peroxide (HydP); 0.12% chlorhexidine (Chlo); sodium bicarbonate jet (SodB); 50-μm aluminum oxide air abrasion (AirA); pumice paste (PumP), and control group-water spray (Cont). After prophylaxis protocols a resin composite block (3.0 mm × 5.0 mm × 5.0 mm) was adhesively cemented using dual resin cement (Rely X ARC). After 24 hours of water storage, specimens were serially sectioned perpendicular to the bonded interface into 1-mm-thick slices. Each specimen was trimmed with a diamond bur to an hourglass shape with a cross-sectional area of approximately 1.0 mm(2) at the bonded area. Specimens were tested (μTBS) at 0.5 mm/min using a universal testing machine. Scanning electron microscopy was used to examine the effects of prophylaxis techniques on dentin. Bond strength data (MPa) were analyzed by one-way analysis of variance and failure mode by Fisher test (α=0.05). μTBS data, means (SD), were (different superscripted letters indicate statistically significant differences): AirA, 25.2 (7.2)(a); PumP, 24.1 (7.8)(a); Chlo, 21.5 (5.6)(a); Cont, 20.6 (8.1)(a); HydP(,) 15.5 (7.6)(b); and SodB(,) 11.5 (4.4)(c). The use of aluminum oxide air abrasion, pumice paste, and chlorhexidine before acid etching did not significantly affect μTBS to dentin; however, the use of hydrogen peroxide and sodium bicarbonate jet significantly reduced μTBS.

  7. Posterior composite restoration update: focus on factors influencing form and function

    PubMed Central

    Bohaty, Brenda S; Ye, Qiang; Misra, Anil; Sene, Fabio; Spencer, Paulette

    2013-01-01

    Restoring posterior teeth with resin-based composite materials continues to gain popularity among clinicians, and the demand for such aesthetic restorations is increasing. Indeed, the most common aesthetic alternative to dental amalgam is resin composite. Moderate to large posterior composite restorations, however, have higher failure rates, more recurrent caries, and increased frequency of replacement. Investigators across the globe are researching new materials and techniques that will improve the clinical performance, handling characteristics, and mechanical and physical properties of composite resin restorative materials. Despite such attention, large to moderate posterior composite restorations continue to have a clinical lifetime that is approximately one-half that of the dental amalgam. While there are numerous recommendations regarding preparation design, restoration placement, and polymerization technique, current research indicates that restoration longevity depends on several variables that may be difficult for the dentist to control. These variables include the patient’s caries risk, tooth position, patient habits, number of restored surfaces, the quality of the tooth–restoration bond, and the ability of the restorative material to produce a sealed tooth–restoration interface. Although clinicians tend to focus on tooth form when evaluating the success and failure of posterior composite restorations, the emphasis must remain on advancing our understanding of the clinical variables that impact the formation of a durable seal at the restoration–tooth interface. This paper presents an update of existing technology and underscores the mechanisms that negatively impact the durability of posterior composite restorations in permanent teeth. PMID:23750102

  8. Influence of dentin conditioning on bond strength of light-cured ionomer restorative materials and polyacid-modified composite resins.

    PubMed

    Buchalla, W; Attin, T; Hellwig, E

    1996-01-01

    The purpose of the study was to evaluate the dentin bond strength of restorative materials containing both glass ionomer and composite resin components. Three resin-modified glass ionomer restorative materials (Fuji II LC, Photac-Fil, Vitremer), three polyacid-modified composite resins (Dyract, Ionosit Fil, VariGlass VLC), a hybrid composite (blend-a-lux) and a chemical-cured glass ionomer cement (ChemFil Superior) were investigated for dentin tensile bond strength with and without conditioning of the tooth surfaces. For each material, tensile bond strength was determined using five conditioned and five unconditioned bovine tooth specimens. Conditioning of the specimens was performed according to the manufacturers' instructions. The tensile bond strength was tested with a universal testing machine. Statistical analysis was performed with analysis of variance, the Scheffe's-test and the Student's t-test. All materials showed higher adhesion to conditioned dentin than to unconditioned specimens. Except for Photac-Fil, the bond strength to conditioned dentin of all resin-modified glass ionomer restorative materials and polyacid-modified composite resins was higher as compared to the chemical-cured glass ionomer and the hybrid composite. However, these differences were not statistically significant. All polyacid-modified composite resins resulted in higher bond strengths to conditioned dentin as compared to the resin-modified glass ionomer restorative materials. These differences were statistically significant only for VariGlass VLC as compared to Photac-Fil. In order to improve adhesion of the tested materials to dentin it is highly recommended to follow the manufacturers' instructions concerning dentin conditioning.

  9. Mercury exposure and risks from dental amalgam in the US population, post-2000.

    PubMed

    Richardson, G M; Wilson, R; Allard, D; Purtill, C; Douma, S; Gravière, J

    2011-09-15

    Dental amalgam is 50% metallic mercury (Hg) by weight and Hg vapour continuously evolves from in-place dental amalgam, causing increased Hg content with increasing amalgam load in urine, faeces, exhaled breath, saliva, blood, and various organs and tissues including the kidney, pituitary gland, liver, and brain. The Hg content also increases with maternal amalgam load in amniotic fluid, placenta, cord blood, meconium, various foetal tissues including liver, kidney and brain, in colostrum and breast milk. Based on 2001 to 2004 population statistics, 181.1 million Americans carry a grand total of 1.46 billion restored teeth. Children as young as 26 months were recorded as having restored teeth. Past dental practice and recently available data indicate that the majority of these restorations are composed of dental amalgam. Employing recent US population-based statistics on body weight and the frequency of dentally restored tooth surfaces, and recent research on the incremental increase in urinary Hg concentration per amalgam-filled tooth surface, estimates of Hg exposure from amalgam fillings were determined for 5 age groups of the US population. Three specific exposure scenarios were considered, each scenario incrementally reducing the number of tooth surfaces assumed to be restored with amalgam. Based on the least conservative of the scenarios evaluated, it was estimated that some 67.2 million Americans would exceed the Hg dose associated with the reference exposure level (REL) of 0.3 μg/m(3) established by the US Environmental Protection Agency; and 122.3 million Americans would exceed the dose associated with the REL of 0.03 μg/m(3) established by the California Environmental Protection Agency. Exposure estimates are consistent with previous estimates presented by Health Canada in 1995, and amount to 0.2 to 0.4 μg/day per amalgam-filled tooth surface, or 0.5 to 1 μg/day/amalgam-filled tooth, depending on age and other factors.

  10. Mercury Amalgam Diffusion in Human Teeth Probed Using Femtosecond LIBS.

    PubMed

    Bello, Liciane Toledo; da Ana, Patricia Aparecida; Santos, Dário; Krug, Francisco José; Zezell, Denise Maria; Vieira, Nilson Dias; Samad, Ricardo Elgul

    2017-01-01

    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.

  11. VIEW, LOOKING SOUTHWEST OF GOLD AMALGAMATION ROOM, SHOWING AMALGAMATION BARREL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW, LOOKING SOUTHWEST OF GOLD AMALGAMATION ROOM, SHOWING AMALGAMATION BARREL AT CENTER FOREGROUND, BULLION FURNACE IN LARGE HOOD BEHIND IT, AND GOLD RETORT IN BACKGROUND HOOD. NOTE OVERHEAD MONORAIL FOR MATERIALS HANDLING. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  12. In vitro shear bond strength of the Amalgambond Plus system.

    PubMed

    van der Vyver, P J; de Wet, F A; Dearlove, W R

    1995-06-01

    The bonding of composite resins to dentine by means of dentine bonding agents is common practice. Although amalgam has been used for many years, no attempt had been made to bond it chemically to tooth structure. Amalgambond Plus (ABP) was developed to bond amalgam (as well as composite) to various substrates. The purpose of this study was to evaluate the ABP system for its ability to bond amalgam, as well as composite, to dentine, and also to assess the strength of the product when bonding composite to set amalgam. The following values (MPa) were obtained for the different ABP variations: Amalgam to Dentine (with HPA): 5.20; Amalgam to Dentine (without HPA): 3.26; Composite to Dentine (without HPA): 17.57; Composite to Amalgam (without HPA): 12.00. It can be concluded that Amalgambond Plus gives varying bond strengths to different substrates, with the highest value obtained when used to bond Composite to Dentine.

  13. Mercury Exposure Levels in Children with Dental Amalgam Fillings

    PubMed Central

    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 < 0.001) (Wilcoxon sign rank test and paired t-test). The hair mercury levels (organic mercury) varied signi-ficantly between the fsh-eating group and nonfsh-eating group, the average values being 1.03 μg/l and 0.84 μg/l respectively (p < 0.001) (Mann-Whitney U-test and paired t-test). Conclusion and significance: The notion about the mercury being released from the 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

  14. Adhesive/Dentin Interface: The Weak Link in the Composite Restoration

    PubMed Central

    Spencer, Paulette; Ye, Qiang; Park, Jonggu; Topp, Elizabeth M.; Misra, Anil; Marangos, Orestes; Wang, Yong; Bohaty, Brenda S.; Singh, Viraj; Sene, Fabio; Eslick, John; Camarda, Kyle; Katz, J. Lawrence

    2010-01-01

    Results from clinical studies suggest that more than half of the 166 million dental restorations that were placed in the United States in 2005 were replacements for failed restorations. This emphasis on replacement therapy is expected to grow as dentists use composite as opposed to dental amalgam to restore moderate to large posterior lesions. Composite restorations have higher failure rates, more recurrent caries, and increased frequency of replacement as compared to amalgam. Penetration of bacterial enzymes, oral fluids, and bacteria into the crevices between the tooth and composite undermines the restoration and leads to recurrent decay and premature failure. Under in vivo conditions the bond formed at the adhesive/dentin interface can be the first defense against these noxious, damaging substances. The intent of this article is to review structural aspects of the clinical substrate that impact bond formation at the adhesive/dentin interface; to examine physico-chemical factors that affect the integrity and durability of the adhesive/dentin interfacial bond; and to explore how these factors act synergistically with mechanical forces to undermine the composite restoration. The article will examine the various avenues that have been pursued to address these problems and it will explore how alterations in material chemistry could address the detrimental impact of physico-chemical stresses on the bond formed at the adhesive/dentin interface. PMID:20195761

  15. Is it the end of the road for dental amalgam? A critical review

    PubMed Central

    Shenoy, Arvind

    2008-01-01

    The longevity of dental restorations is dependent on many factors, including those related to materials, the dentist, and the patient. Dental amalgams have successfully served the profession for over a century. The main reasons for restoration failure are secondary caries, fracture of the bulk of the restoration or of the tooth, and marginal deficiencies and wear. The importance of direct-placement, aesthetic, tooth-colored restorative materials is still increasing. Amalgam restorations are being replaced because of alleged adverse health effects and inferior aesthetic appearance. All alternative restorative materials and procedures, however, have certain limitations. This article will attempt to critically analyse both amalgams and resin based composites, through an evaluation of scientific literature. PMID:20142895

  16. Effect of postoperative peroxide bleaching on the marginal seal of composite restorations bonded with self-etch adhesives.

    PubMed

    Roubickova, A; Dudek, M; Comba, L; Housova, D; Bradna, P

    2013-01-01

    The aim of this study was to determine the effect of peroxide bleaching on the marginal seal of composite restorations bonded with several adhesive systems. Combined cylindrical Class V cavities located half in enamel and half in dentin were prepared on the buccal and lingual surfaces of human molars. The cavities were bonded with the self-etch adhesives Clearfil SE-Bond (CLF), Adper Prompt (ADP), and iBond (IBO) and an etch-and-rinse adhesive Gluma Comfort Bond (GLU) and restored with a microhybrid composite Charisma. Experimental groups were treated 25 times for eight hours per day with a peroxide bleaching gel Opalescence PF 20, while the control groups were stored in distilled water for two months and then subjected to a microleakage test using a dye penetration method. Scanning electron microscopy was used to investigate the etching and penetration abilities of the adhesives and morphology of debonded restoration-enamel interfaces after the microleakage tests. Statistical analyses were performed using nonparametric Kruskal-Wallis, Mann-Whitney, and Wilcoxon tests at p=0.05. The microleakage of all GLU groups was low and not significantly affected by peroxide bleaching. Low microleakage was recorded for CLF control groups, but after bleaching, a small but significant increase in microleakage at the enamel margin indicated its sensitivity to peroxide bleaching. For ADP and IBO control groups, the microleakage at the enamel margins was significantly higher than for GLU and CLF and exceeded that at the dentin margins. Bleaching did not induce any significant changes in the microleakage. Electron microscopy analysis indicated that in our experimental setup, decreased adhesion and mechanical resistance of the ADP- and IBO-enamel interfaces could be more important than the chemical degradation effects induced by the peroxide bleaching gel.

  17. [Abrasion measurements in vivo in occlusal composite and amalgam fillings].

    PubMed

    Meier, C; Lutz, F

    1978-09-01

    A new method for quantitative measurement of occlusal wear on restorations is described. In a clinical evaluation with four different composites and an amalgam the method proved to be simple in execution and very exact. Statistical analysis after 7 months has shown significant differences in wear resistance of the different materials. The nature of the resulting wear was electron optically examined. Typical structural surface characteristics were observed for each of the different materials. More recently developed composities utilizing extremly small filler particles (Aerosil) seem to be comparable to amalgam in wear resistance.

  18. Evaluation of bond strength of silorane and methacrylate based restorative systems to dentin using different cavity models

    PubMed Central

    ISAAC, Stephano Zerlottini; BERGAMIN, Ana Claudia Pietrobom; TURSSI, Cecília Pedroso; do AMARAL, Flávia Lucisano Botelho; BASTING, Roberta Tarkany; FRANÇA, Fabiana Mantovani Gomes

    2013-01-01

    Objective The aim of this in vitro study was to evaluate the microtensile bond strength (µTBS) to dentin of two different restorative systems: silorane-based (P90), and methacrylate-based (P60), using two cavity models. Material and Methods Occlusal enamel of 40 human third molars was removed to expose flat dentin surface. Class I cavities with 4 mm mesial-distal width, 3 mm buccal-lingual width and 3 mm depth (C-factor=4.5) were prepared in 20 teeth, which were divided into two groups (n=10) restored with P60 and P90, bulk-filled after dentin treatment according to manufacturer's instructions. Flat buccal dentin surfaces were prepared in the 20 remaining teeth (C-factor=0.2) and restored with resin blocks measuring 4x3x3 mm using the two restorative systems (n=10). The teeth were sectioned into samples with area between 0.85 and 1.25 mm2 that were submitted to µTBS testing, using a universal testing machine (EMIC) at speed of 0.5 mm/min. Fractured specimens were analyzed under stereomicroscope and categorized according to fracture pattern. Data were analyzed using ANOVA and Tukey Kramer tests. Results For flat surfaces, P60 obtained higher bond strength values compared with P90. However, for Class I cavities, P60 showed significant reduction in bond strength (p<0.05). No statistical difference between restorative systems was shown for Class I cavity model (p>0.05), or between Class I Cavity and Flat Surface group, considering P90 restorative system (p>0.05). Regarding fracture pattern, there was no statistical difference among groups (p=0.0713) and 56.3% of the fractures were adhesive. Conclusion It was concluded that methacrylate-based composite µTBS was influenced by cavity models, and the use of silorane-based composite led to similar bond strength values compared to the methacrylate-based composite in cavities with high C-factor. PMID:24212992

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

    PubMed

    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.

  20. The Influence of Different Restorative Materials on Secondary Caries Development in situ

    PubMed Central

    van de Sande, Françoise H.; Opdam, Niek J.M.; Truin, Gert Jan; Bronkhorst, Ewald M.; de Soet, Johannes J.; Cenci, Maximiliano S.; Huysmans, Marie-Charlotte

    2014-01-01

    Objectives: The effect of direct restorative materials on caries lesion formation was investigated with an 8-week in situ study with split-mouth design, testing the hypothesis that no difference in mineral loss next to a restoration would be found between different composite-based-materials and amalgam. Methods: Six groups (n=18) of restored dentin samples were prepared using amalgam, a microhybrid, a nanohybrid and a silorane composite. The composites were adhesively bonded with systems with or without an antibacterial monomer (Clearfil-SE-Protect, Clearfil-SE-bond, respectively), except for the silorane group (Silorane- System-Adhesive). Non-restored dentin samples were used as control (primary caries). Samples were inserted into slots, in lower prosthesis especially made for the experiment. Subjects were instructed to dip the lower prosthesis in a sucrose solution 4 times per day. At baseline and 8 weeks, samples were radiographed extra-orally and the integrated mineral loss was calculated. Data were statistically analyzed using multiple linear regression with a multilevel model (p=0.05). Results: Nine subjects were selected, and only outer lesions were observed. The hypothesis was partially rejected, as the microhybrid composite bonded with the antibacterial system and the nanohybrid composite presented statistically significant lower mineral loss compared to amalgam. Also, no significant differences were seen for these groups compared to control. Conclusion: Within the limits of this study, the restorative material may influence outer lesion progression. Amalgam was not found to be related to lower secondary caries progression in dentin compared to composite-based materials after 8 weeks in situ. PMID:25010541

  1. Secondary Caries Development in in situ Gaps next to Composite and Amalgam.

    PubMed

    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.

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

    PubMed

    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.

  3. Influence of periodontal ligament simulation on bond strength and fracture resistance of roots restored with fiber posts

    PubMed Central

    MARCHIONATTI, Ana Maria Estivalete; WANDSCHER, Vinícius Felipe; BROCH, Juliana; BERGOLI, César Dalmolin; MAIER, Juliana; VALANDRO, Luiz Felipe; KAIZER, Osvaldo Bazzan

    2014-01-01

    Objective Considering that periodontal ligament simulation may influence the stress distribution over teeth restored with intraradicular retainers, this study aimed to assess the combined effect of mechanical cycling and periodontal ligament simulation on both the bond strength between fiber posts and root dentin and the fracture resistance of teeth restored using glass fiber posts. Material and Methods Ninety roots were randomly distributed into 3 groups (n=10) (C-MC: control; P-MC: polyether; AS-MC: addition silicone) to test bond strength and 6 groups (n=10) (C: control; P: polyether; AS: addition silicone, without mechanical cycling, and C-MC, P-MC and AS-MC with mechanical cycling) to test fracture strength, according to the material used to simulate the periodontal ligament. For the bond strength test, fiber posts were cemented, cores were built, mechanical cycling was applied (2×106 cycles, 88 N, 2.2 Hz, and 45º incline), and the teeth cut into 3 slices (2 mm), which were then subjected to the push-out test at 1 mm/min. For the fracture strength test, fiber posts were cemented, cores were built, and half of the groups received mechanical cycling, followed by the compressive strength (45° to the long axis and 1 mm/min) performed on all groups. Results Periodontal ligament simulation did not affect the bond strength (p=0.244) between post and dentin. Simulation of periodontal ligament (p=0.153) and application of mechanical cycling (p=0.97) did not affect fracture resistance. Conclusions The materials used to simulate the periodontal ligament did not affect fracture or bond strength, therefore periodontal ligament simulation using the tested materials could be considered optional in the conditions of the study. PMID:25466478

  4. Bonding All-Ceramic Restorations with Two Resins Cement Techniques: A Clinical Report of Three-Year Follow-Up

    PubMed Central

    Anchieta, Rodolfo Bruniera; Rocha, Eduardo Passos; de Almeida, Erika Oliveira; Junior, Amilcar Chagas Freitas; Martini, Ana Paula

    2011-01-01

    Ceramics have been widely used for esthetic and functional improvements. The resin cement is the material of choice for bonding ceramics to dental substrate and it can also dictate the final esthetic appearance and strength of the restoration. The correct use of the wide spectrum of resin luting agents available depends on the dental tooth substrate. This article presents three-year clinical results of a 41 years old female patient B.H.C complaining about her unattractive smile. Two all-ceramic crowns and two laminates veneers were placed in the maxillary incisors and cemented with a self-adhesive resin luting cement and conventional resin luting cement, respectively. After a three-year follow-up, the restorations and cement/teeth interface were clinically perfect with no chipping, fractures or discoloration. Proper use of different resin luting cements shows clinical appropriate behavior after a three-year follow-up. Self-adhesive resin luting cement may be used for cementing all-ceramic crowns with high predictability of success, mainly if there is a large dentin surface available for bonding and no enamel at the finish line. Otherwise, conventional resin luting agent should be used for achieving an adequate bonding strength to enamel. PMID:21912505

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

    NASA Technical Reports Server (NTRS)

    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.

  6. In vitro evaluation of the effect of deproteinization on the marginal leakage of resin restorations using three bonding agents

    PubMed Central

    Ravishanker, Padmanabhan; Chaitanya, Krishna

    2012-01-01

    Background: The perfect sealing of the tooth/restoration interface is important to prevent bacteria penetration that may lead to secondary caries and also, when dentin is involved, prevent excessive fluid movement in the dentinal tubules that may cause hypersensitivity. The aim of this study was to evaluate the effect of deproteinization and application of reducing agent on the marginal integrity of composite restorations using three different bonding agents (Prime & Bond NT, AdheSE and G-Bond). Materials and Methods: Class V cavities were prepared on the buccal surface of 90 recently extracted human premolars and were divided into three groups (I, II, and III) based on the adhesives. Each group was subdivided into three subgroups of 10 each according to the surface treatment: application according to clinical protocol; etching with 37% phosphoric acid for 15 seconds/5% NaOCl; 10% sodium ascorbate after etching/NaOCl. The cavities were restored with Filtek Z 350 nanocomposite. The specimens were sectioned and evaluated under stereomicroscope. The morphology of the resin-dentin interface was visualized using SEM. Statistical analysis was done using Kruskal-Wallis one-way ANOVA followed by a Mann-Whitney U- test (P<0.05). Results: Group I showed significantly least microleakage among the groups. No significant difference in microleakage was found between groups I and II. Within the subgroups for each group, no significant difference in microleakage scores was observed. SEM micrographs presented gap free areas in group I and varying degrees of gaps in the other two groups. Conclusion: Etch and rinse adhesives were tenable for deproteinization than self etch adhesives. PMID:23162588

  7. Extreme masking: achieving predictable outcomes in challenging situations with lithium disilicate bonded restorations.

    PubMed

    Hatai, Yugo

    2014-01-01

    In contemporary dentistry, we have a vast range of materials to choose from, and metal free restorations have become the premier materials for achieving the ultimate in both esthetics and durability. Metal-free restorations are utilized with more conservative preparations to preserve the vital natural dentition, and have proven to be superior alternatives to traditional porcelain-fused-to-metal (PFM) restorations in many cases. There are always "pros and cons" when selecting materials, and to make the best choice it is essential for dental professionals to plan precisely and understand their options in any clinical situation. Selecting suitable materials and techniques involves consideration of the following factors: - Esthetic zone. - Required strength based on the patient's occlusion/dental habits. - Preparation reduction. - Position of the margin. - Type of restoration/preparation. - The treating clinician's philosophy. - Stump shade. Final shade. One of the most significant challenges in the metal-free dentistry is the reproduction of natural dentition without the influence of a "negative stump" - a very dark or metal core showing through the final restorations. There are many factors to be considered when working on such a case, and controlling the opacity of the coping and crown is the key to success. This article presents a unique "outside of the box" technique that provides consistent, predictable and durable restorations, which provide the best possible esthetic outcome.

  8. Microleakage in Resin Composite Restoration following Antimicrobial Pre-treatments with 2% Chlorhexidine and Clearfil Protect Bond

    PubMed Central

    Hameed, Hisham; Babu, Biju P; Sagir, V M Mohammed; Chiriyath, Kennet J; Mathias, Jones; Shaji, A P

    2015-01-01

    Aim: To evaluate microleakage in resin composite restorations after antimicrobial pre – treatments Materials and Methods: Forty freshly extracted non carious human premolars were procured. In all forty premolar specimens, class V preparation of standard dimension were prepared and were randomly divided into three experimental and one control group. In all control and experimental groups the class V preparations were restored with FILTEK Z350 composite restorative material. The experimental groups included different self etching primers and 2% Chlorhexidine gluconate. The control group included Xeno III and no antimicrobial pre-treatment was done for the control group. Thereafter these specimens were thermocycled, dried and sealed with nail varnish, leaving 1mm around the restoration and immersed in 0.5% basic fuchsin for 24 hours and then the specimens were subjected for microleakage evaluation. The results were statistically analyzed by Kruskal Wallis Test and Mann Whitney ‘U’ test. Results: Results indicate that group II (2% chlorhexidine gluconate group) had the minimum mean value (15.05) and group III(Clearfil protect Bond group) and IV(control group) had the maximum mean microleakage at the enamel margin (23.00). At the gingival margin the lowest mean microleakage values were obtained with group I (Clearfil SE bond group) and group II (2% chlorhexidine gluconate) (20.25) and highest with group III and group IV (20.85). The difference was not statistically significant both at the enamel margin and the dentin margin (p>0.05). Interpretation & Conclusions: Within the limitations of this in-vitro study, we conclude that: None of the materials tested in this study completely eliminated microleakage at the enamel and at the gingival margin.All of the tested materials provided better sealing at the enamel margin than at the gingival margin. PMID:26229374

  9. The 24-year clinical performance of porcelain laminate veneer restorations bonded with a two-liquid silane primer and a tri-n-butylborane-initiated adhesive resin.

    PubMed

    Nakamura, Mitsuo; Matsumura, Hideo

    2014-09-01

    This report describes the bonding technique and clinical course of porcelain laminate veneer restorations applied to discolored maxillary incisors and canines. The patient was an 18-year-old woman, and tooth reduction was limited to the enamel. Laminate veneer restorations were made with a feldspathic porcelain material (Cosmotech Porcelain). After try-in, enamel surfaces were etched with 65% phosphoric acid gel, and a tri-n-butylborane-initiated resin (Super-Bond C&B) was applied as a bonding agent. The inner surface of the restorations was etched with 5% hydrofluoric acid gel (HF Gel) and treated with a two-liquid silane primer (Porcelain Liner M), after which the Super-Bond resin was applied. Each restoration was seated with a dual-activated composite luting agent (Cosmotech Composite). After 24 years and 8 months, the restorations are functioning satisfactorily. The luting system and bonding technique described in this report are an option for seating laminate veneer restorations made of silica-based tooth-colored ceramics.

  10. Use of self-curing composite resins to facilitate amalgam repair.

    PubMed

    Lacy, A M; Rupprecht, R; Watanabe, L

    1992-01-01

    Resin cements, which have been shown to adhere to various metal alloys, were investigated as possible repair adhesives for dental amalgam. Test bars of repaired amalgam, formed by condensing new alloy against previously set alloy with or without the use of "adhesive" resins, were subjected to three-point bending measurements of transverse fracture strength. The results indicated that application of adhesive resin did not improve the breaking strength of the repaired specimens from that of specimens prepared without the use of such resins. The breaking strength of all repaired specimens was approximately 15% of the transverse fracture strength of the original intact amalgam bars. Scanning electron microscopy revealed that there was an intermixing of fresh amalgam and unset interfacial resin, which led to mechanical bonding of these materials, but there was no evidence of adhesion of the resin to the previously set amalgam.

  11. Influence of different light sources on microtensile bond strength and gap formation of resin cement under porcelain inlay restorations.

    PubMed

    Ozturk, A N; Usumez, A

    2004-09-01

    Clinical success with ceramic inlays/onlays has been assisted by the ability to develop a reliable bond of composite resin to dental tissues. The purpose of this study was to test the efficiency of two different light sources on microtensile bond strength and the gap formation of resin cement under class II porcelain inlay restorations. Standardized mesio-occlusal cavities were prepared in 30 freshly extracted, intact human premolar teeth. Then impressions were made and ceramic inlays were fabricated. In the cementation process, the resin cement/inlay combinations were exposed to two different photopolymerization units. The polymerizations through 15 specimens were performed with a conventional halogen light source for 60 s, and the other specimens were cured by a plasma arc light for 9 s. After the cementation process, two 1.2 x 1.2 mm wide 'I' shape sections per tooth were produced with a sectioning machine and sections were subjected to microtensile testing after 24 h or 1 week. Gap formation of specimens cured by different photopolymerization units were evaluated with scanning electron microscopy (SEM). Statistically significant differences were found between the microtensile bond strength of inlays exposed to conventional light and plasma arc curing unit (P < 0.001). Plasma arc curing units make it possible to polymerize composite in much shorter times than conventional curing unit. However, the samples polymerized with conventional halogen light produced better microtensile bond strength than the plasma arc unit.

  12. Amalgam contact hypersensitivity lesion: an unusual presentation-report of a rare case.

    PubMed

    Ramnarayan, Bk; Maligi, Pm; Smitha, T; Patil, Us

    2014-09-01

    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 incorporation in the soft tissue have been reported in the literature. However, ACHL presenting primarily as a black pigmented lesion is extremely rare if not reported. The clinician should be aware of one such presentation of ACHL; we report a unique case of ACHL in a 30-year-old female with such a pigmented lesion in close contact with amalgam restorations. The lesion regressed considerably in a year after replacement of the restoration with posterior composites.

  13. Amalgam Contact Hypersensitivity Lesion: An Unusual Presentation-Report Of A Rare Case

    PubMed Central

    Ramnarayan, BK; Maligi, PM; Smitha, T; Patil, US

    2014-01-01

    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 incorporation in the soft tissue have been reported in the literature. However, ACHL presenting primarily as a black pigmented lesion is extremely rare if not reported. The clinician should be aware of one such presentation of ACHL; we report a unique case of ACHL in a 30-year-old female with such a pigmented lesion in close contact with amalgam restorations. The lesion regressed considerably in a year after replacement of the restoration with posterior composites. PMID:25364611

  14. Mercury release of amalgams with various silver contents after exposure to bleaching agent

    PubMed Central

    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 < 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. PMID:27429729

  15. Development and Validation of a Prototype Vacuum Sensing Unit for the DD2011 Chairside Amalgam Separators

    DTIC Science & Technology

    2015-10-30

    during placement and removal of amalgam restorations can contribute to mercury pollution in waterways. Chairside amalgam separators in dental...1L/min. A liter of water evacuated within 1 min, 1.5 min, and greater than 2 min were categorized as normal, warning, and critical states... water through the system. The time that flushing began and ended was recorded. The high vacuum evacuation device valve remained open until all

  16. [Application of gypsum-bonded investment containing niobium carbide on casting of alloy for metal-ceramic restoration].

    PubMed

    Tsuruta, S; Ban, S; Hasegawa, J; Hayashi, S; Iiyama, K; Yamamura, Y

    1990-07-01

    Experimental gypsum-bonded investments containing 0.5-5.0 wt% NbC were prepared by mechanical mixing of each powder. Setting and thermal expansion measurement, compressive strength and casting accuracy for Ni-Cr alloy for metal-ceramic restoration were investigated. Analysis of NbC during heating was carried out by X-ray diffraction, TG-DTA and SEM. NbC was oxidized to Nb2O5 with a volume change between 300-600 degrees C, as in the following equation: 2NbC + 4 1/2O2----Nb2O5 + 2CO2 The theoretical volume of 1/2Nb2O5 calculated from the lattice constants according to JCPDS file was approximately 4 times larger than that of NbC. The experimental investments of 70 wt% cristobalite and 30 wt% gypsum containing 2.0, 3.0 and 5.0 wt% NbC showed large thermal expansion of 7.0, 10.0 and 13.0% respectively. The investment containing 2.0 wt% NbC showed nearly the same casting accuracy for Ni-Cr alloys for metal-ceramic restoration as the commercial phosphate-bonded investment.

  17. Cementation of prosthetic restorations: from conventional cementation to dental bonding concept.

    PubMed

    Haddad, Marcela Filié; Rocha, Eduardo Passos; Assunção, Wirley Gonçalves

    2011-05-01

    The cementation procedure of metal-free fixed partial dentures exhibits special characteristics about the porcelains and cementation agents, which turns the correct association between these materials necessary. Our purpose in this literature review was to point the main groups of cements associated to metal-free restoration and discuss about the advantages, disadvantages, and recommendations of each one. Our search was confined to the electronic databases PubMed and SciELO and to books about this matter. There are essentially 3 types of hard cement: conventional, resin, or a hybrid of the two. The metal-free restorations can be fixed with conventional or resin cements. The right choice of luting material is of vital importance to the longevity of dental restorative materials. Conventional cements are advantageous when good compressive straight, good film thickness, and water dissolution resistance are necessary. However, they need an ideal preparation, and they are not acid dissolution resistant. Conventional cements are indicated to porcelains that cannot be acid etched. Resin cements represent the choice to metal-free restoration cementation because they present better physical properties and aesthetic than conventional agents.

  18. EFFECT OF DEPROTEINIZATION AND TUBULAR OCCLUSION ON MICROTENSILE BOND STRENGTH AND MARGINAL MICROLEAKAGE OF RESIN COMPOSITE RESTORATIONS

    PubMed Central

    Baseggio, Wagner; Consolmagno, Elaine Cristina; de Carvalho, Flávia Lunardelli Negreiros; Ueda, Julio Katuhide; Schmitt, Vera Lucia; Formighieri, Luis Alberto; Naufel, Fabiana Scarparo

    2009-01-01

    Dentin adhesion procedure presents limitations, especially regarding to lifetime stability of formed hybrid layer. Alternative procedures have been studied in order to improve adhesion to dentin. Objective: The aim of this study was to evaluate in vitro the influence of deproteinization or dentin tubular occlusion, as well as the combination of both techniques, on microtensile bond strength μTBS) and marginal microleakage of composite resin restorations. Material and Methods: Extracted erupted human third molars were randomly divided into 4 groups. Dentin surfaces were treated with one of the following procedures: (A) 35% phosphoric acid gel (PA) + adhesive system (AS); (B) PA + 10% NaOCl + AS; (C) PA + oxalate + AS and (D) PA + oxalate + 10% NaOCl + AS. Bond strength data were analyzed statistically by two-way ANOVA and Tukey's test. The microleakage scores were analyzed using Kruskal-Wallis and Mann-Whitney non-parametric tests. Significance level was set at 0.05 for all analyses. Results: μTBS data presented statistically lower values for groups D and B, ranking data as A>C>B>D. The use of oxalic acid resulted in microleakage reduction along the tooth/restoration interface, being significant when used alone. On the other hand, the use of 10% NaOCl alone or in combination with oxalic acid, resulted in increased microleakage. Conclusions: Dentin deproteinization with 10% NaOCl or in combination with oxalate significantly compromised both the adhesive bond strength and the microleakage at interface. Tubular occlusion prior to adhesive system application seems to be a useful technique to reduce marginal microleakage. PMID:19936527

  19. 21 CFR 872.3070 - Dental amalgam, mercury, and amalgam alloy.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 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...

  20. 21 CFR 872.3070 - Dental amalgam, mercury, and amalgam alloy.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 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...

  1. 21 CFR 872.3070 - Dental amalgam, mercury, and amalgam alloy.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 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...

  2. 21 CFR 872.3070 - Dental amalgam, mercury, and amalgam alloy.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 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...

  3. 21 CFR 872.3070 - Dental amalgam, mercury, and amalgam alloy.

    Code of Federal Regulations, 2010 CFR

    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...

  4. Dental composites and amalgam and physical development in children.

    PubMed

    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).

  5. High-field MRI and mercury release from dental amalgam fillings.

    PubMed

    Mortazavi, S M J; Neghab, M; Anoosheh, S M H; Bahaeddini, N; Mortazavi, G; Neghab, P; Rajaeifard, A

    2014-04-01

    Mercury is among the most toxic nonradioactive elements which may cause toxicity even at low doses. Some studies showed release of mercury from dental amalgam fillings in individuals who used mobile phone. This study was conducted to assess the effect of high-field MRI on mercury release from dental amalgam filling. We studied two groups of students with identical tooth decays requiring a similar pattern of restorative dentistry. They were exposed to a magnetic flux density of 1.5 T produced by a MRI machine. 16 otherwise healthy students with identical dental decay participated in this study. They underwent similar restorative dentistry procedures and randomly divided into two groups of MRI-exposed and control arms. Urinary concentrations of mercury in the control subjects were measured before (hour 0) and 48 and 72 hrs after amalgam restoration, using cold vapor atomic absorption spectrometry. Urinary concentrations of mercury in exposed individuals were determined before (hour 0), and 24, 48, 72 and 96 hrs after amalgam restoration. Unlike control subjects, they underwent conventional brain MRI (15 min, 99 slices), 24 hrs after amalgam restoration. The mean±SD urinary mercury levels in MRI-exposed individuals increased linearly from a baseline value of 20.70±17.96 to 24.83±22.91 μg/L 72 hrs after MRI. In the control group, the concentration decreased linearly from 20.70±19.77 to 16.14±20.05 μg/L. The difference between urinary mercury in the exposed and control group, 72 hrs after MRI (96 h after restoration),was significant (p=0.046). These findings provide further support for the noxious effect of MRI (exposure to strong magnetic field)and release of mercury from dental amalgam fillings.

  6. An esthetic solution for single-implant restorations - type III porcelain veneer bonded to a screw-retained custom abutment: a clinical report.

    PubMed

    Magne, Pascal; Magne, Michel; Jovanovic, Sascha A

    2008-01-01

    A new esthetic solution to restore dental implants in combination with limited interdental, facial or labial, or interocclusal space is presented. This article describes the translational application of novel-design porcelain veneers and adhesive restorative principles in the implant realm. A patient is presented who was treated with a single implant-supported restoration replacing a missing mandibular lateral incisor and partially collapsed interdental space. A screw-retained custom metal ceramic abutment was combined with a bonded porcelain restoration. This unique design was motivated by the limited restorative space and subgingival implant shoulder. It was also developed as a solution to the interference of the screw-access channel with the incisal edge, therefore providing the surgeon with more options during implant axis selection. The porcelain-to-porcelain adhesive approach was used instead of traditional principles of retention and resistance form of the abutment.

  7. A galvanic study of different amalgams.

    PubMed

    Wang Chen, C P; Greener, E H

    1977-01-01

    Due to the difference in open circuit potential (OCP) versus SCE for Aristaloy amalgam (-969 mV) and Dispersalloy amalgam (-549 mV) in Ringer's solution at 25 degrees C, a galvanic cell was created with Dispersalloy amalgam as cathode and Aristaloy amalgam as anode. The galvanic corrosion current was studied as a function of time for the above cell as well as for a cell of type III dental gold (OCP is +0-5 mV) versus Aristaloy amalgam. The initial corrosion current of the latter cell (105 micronA) is about twice that for the cell of Aristaloy amalgam versus Dispersalloy amalgam (54 micronA), however, their passivating behaviour is quite similar. Also, an interrupted galvanic corrosion test simulating the oral 'make and break' situation was performed. A much higher corrosion current than the steady state was found when the two electrodes resumed contact.

  8. Managing the phase-down of amalgam: Part I. Educational and training issues.

    PubMed

    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.

  9. Effect of LED curing on the microleakage, shear bond strength and surface hardness of a resin-based composite restoration.

    PubMed

    Oberholzer, Theunis G; Du Preez, Ignatius C; Kidd, M

    2005-06-01

    To determine the effect of Light emitting diode (LED) curing on dental resins, microleakage, shear bond strength and surface hardness of a dental composite cured with different LEDs were determined and compared with conventional halogen curing. For microleakage, Class V cavities were restored with Esthet-X, divided into groups, and exposed to one of the curing protocols (Elipar Freelight in soft start and standard modes; Ultra-Lume 2; Spectrum 800). Standard dye penetration tests were performed and the data summarised in a 2-way contingency table of observed frequencies. The Chi-square test was used (p<0.05) to test for significant differences between the lights. For surface hardness, samples of Esthet-X were exposed to the light-curing units (LCUs). Vickers hardness was determined on the upper and the bottom surfaces. Data was subjected to statistical analysis using ANOVA (p<0.05). Shear bond strength was determined using a push out method. Comparisons (ANOVA, p<0.05) were made between the different curing protocols. No significant difference in microleakage could be demonstrated between the different LCUs at the enamel side (p=0.60). At the dentin side only the Elipar Freelight (soft start), could significantly reduce microleakage (p<0.01). The hardness score for the halogen light was significantly lower than for the LED lights (p<0.01). The Spectrum 800 and the Elipar Freelight (soft start) have significantly higher shear bond strengths than the others (p<0.01). It was concluded that the LED source is more efficient for a comparable overall power output.

  10. Amalgam ablation with the Er:YAG laser

    NASA Astrophysics Data System (ADS)

    Wigdor, Harvey A.; Visuri, Steven R.; Walsh, Joseph T., Jr.

    1995-04-01

    Any laser that will be used by dentist to replace the dental drill (handpiece) must remove dental hard tissues safely. These lasers must also have the ability to ablate the restorative dental materials which are present in the teeth being treated. Prior to any laser being used to treat humans a thorough knowledge of the effects of the laser treatment on dental materials must be understood. Cores of dental amalgam were created and sliced into thin wafers for this experiment. Ablation efficiency and thermal changes were evaluated with and without water. It appears as if the Er:YAG laser can effectively ablate amalgam dental material with and without water. The water prevents the temperature from increasing much above baseline and does not reduce efficiency of ablation.

  11. Neurodevelopmental outcomes at 5 years in children exposed prenatally to maternal dental amalgam: the Seychelles Child Development Nutrition Study.

    PubMed

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

    2013-01-01

    Limited human data are available to assess the association between prenatal mercury vapor (Hg⁰)) exposure from maternal dental amalgam restorations and neurodevelopment of children. We evaluated the association between maternal dental amalgam status during gestation and children's neurodevelopmental outcomes at 5 years in the Seychelles Child Development Nutrition Study (SCDNS). Maternal amalgam status was determined prospectively in a longitudinal cohort study examining the associations of prenatal exposure to nutrients and methylmercury (MeHg) with neurodevelopment. A total of 236 mother-child pairs initially enrolled in the SCDNS in 2001 were eligible to participate. Maternal amalgam status was measured as number of amalgam surfaces (the primary metric) and number of occlusal points. The neurodevelopmental assessment battery was comprised of age-appropriate tests of cognitive, language, and perceptual functions, and scholastic achievement. Linear regression analysis controlled for MeHg exposure, maternal fatty acid status, and other covariates relevant to child development. Maternal amalgam status evaluation yielded an average of 7.0 surfaces (range 0-28) and 11.0 occlusal points (range 0-40) during pregnancy. Neither the number of maternal amalgam surfaces nor occlusal points were associated with any outcome. Our findings do not provide evidence to support a relationship between prenatal exposure to Hg⁰ from maternal dental amalgam and neurodevelopmental outcomes in children at 5 years of age.

  12. Corrosion Penetration in Crevices of Dental Amalgam.

    DTIC Science & Technology

    1978-09-07

    AD-AC59 301 LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CALIF PA-ETC F/6 A/S .9 CORROSION PENETRATION IN CREVICES OF DENTAL AMALGAM. (U) SEP 78 T...OF RE;-ORT & PERIOD COVERED ./CORROSION PENETRATION IN CREVICES OF _. Itm . / DENTAL AMALGAM, - . .... ,,, T 7 AUTHOR(s) / L S i DG3t1 , T. Katan and...identify by block number) amalgam corrosion, crevice corrosion, dental amalgam. 20.- ABSTRACT (Continue on reverse side If necessary and Identify by

  13. [Amalgam fillings and T-lymphocyte changes].

    PubMed

    Giuliani, M; Rumi, C; Marciani, F; Boari, A; Rumi, G; Di Felice, R

    1990-07-01

    Dental amalgam and nickel alloys have been considered quite safe. Previous authors reported the effect of dental amalgam and nickel alloys on human T-lymphocytes modifications after amalgam dental fillings, into dose-dependence of any modifications and into possible temporary. Eight patients were subjected to dental care with amalgam dental fillings. Drawings of blood were executed at start, fifteen days after late fillings and two months later. The results about modifications of T-lymphocytes were not univocal. We believe, at now, that temporary modifications of the immunity seem to be related to a cytotoxic mechanism.

  14. Comparative Evaluation of Shear Bond Strength of Luting Cements to Different Core Buildup Materials in Lactic Acid Buffer Solution

    PubMed Central

    Patil, Siddharam M.; Desai, Raviraj G.; Arabbi, Kashinath C.; Prakash, Ved

    2015-01-01

    Aim and Objectives The core buildup material is used to restore badly broken down tooth to provide better retention for fixed restorations. The shear bond strength of a luting agent to core buildup is one of the crucial factors in the success of the cast restoration. The aim of this invitro study was to evaluate and compare the shear bond strength of luting cements with different core buildup materials in lactic acid buffer solution. Materials and Methods Two luting cements {Traditional Glass Ionomer luting cement (GIC) and Resin Modified Glass Ionomer luting cement (RMGIC)} and five core buildup materials {Silver Amalgam, Glass ionomer (GI), Glass Ionomer Silver Reinforced (GI Silver reinforced), Composite Resin and Resin Modified Glass Ionomer(RMGIC)} were selected for this study. Total 100 specimens were prepared with 20 specimens for each core buildup material using a stainless steel split metal die. Out of these 20 specimens, 10 specimens were bonded with each luting cement. All the bonded specimens were stored at 370c in a 0.01M lactic acid buffer solution at a pH of 4 for 7days. Shear bond strength was determined using a Universal Testing Machine at a cross head speed of 0.5mm/min. The peak load at fracture was recorded and shear bond strength was calculated. The data was statistically analysed using Two-way ANOVA followed by HOLM-SIDAK method for pair wise comparison at significance level of p<0.05. Results Two-Way ANOVA showed significant differences in bond strength of the luting cements (p<0.05) and core materials (p<0.05) and the interactions (p<0.05). Pairwise comparison of luting cements by HOLM-SIDAK test, showed that the RMGIC luting cement had higher shear bond strength values than Traditional GIC luting cement for all the core buildup materials. RMGIC core material showed higher bond strength values followed by Composite resin, GI silver reinforced, GI and silver amalgam core materials for both the luting agents. Conclusion Shear bond strength of

  15. Fatigue resistance of bovine teeth restored with resin-bonded fiber posts: effect of post surface conditioning.

    PubMed

    Zamboni, Sandra C; Baldissara, Paolo; Pelogia, Fernanda; Bottino, Marco Antonio; Scotti, Roberto; Valandro, Luiz Felipe

    2008-01-01

    This study evaluated the effect of post surface conditioning on the fatigue resistance of bovine teeth restored with resin-bonded fiber-reinforced composite (FRC). Root canals of 20 single-rooted bovine teeth (16 mm long) were prepared to 12 mm using a preparation drill of a double-tapered fiber post system. Using acrylic resin, each specimen was embedded (up to 3.0 mm from the cervical part of the specimen) in a PVC cylinder and allocated into one of two groups (n = 10) based on the post surface conditioning method: acid etching plus silanization or tribochemical silica coating (30 pm SiO(x) + silanization). The root canal dentin was etched (H2PO3 for 30 seconds), rinsed, and dried. A multi-step adhesive system was applied to the root dentin and the fiber posts were cemented with resin cement. The specimens were submitted to one million fatigue cycles. After fatigue testing, a score was given based on the number of fatigue cycles until fracture. All of the specimens were resistant to fatigue. No fracture of the root or the post and no loss of retention of the post were observed. The methodology and the results of this study indicate that tribochemical silica coating and acid etching performed equally well when dynamic mechanical loading was used.

  16. Overexpression of the rhodanese PspE, a single cysteine-containing protein, restores disulfide bond formation to an Escherichia coli strain lacking DsbA

    PubMed Central

    Chng, Shu-Sin; Dutton, Rachel J.; Denoncin, Katleen; Vertommen, Didier; Collet, Jean-Francois; Kadokura, Hiroshi; Beckwith, Jonathan

    2012-01-01

    Summary Escherichia coli uses the DsbA/DsbB system for introducing disulfide bonds into proteins in the cell envelope. Deleting either dsbA or dsbB or both reduces disulfide bond formation but does not entirely eliminate it. Whether such background disulfide bond forming activity is enzyme-catalyzed is not known. To identify possible cellular factors that might contribute to the background activity, we studied the effects of overexpressing endogenous proteins on disulfide bond formation in the periplasm. We find that overexpressing PspE, a periplasmic rhodanese, partially restores substantial disulfide bond formation to a dsbA strain. This activity depends on DsbC, the bacterial disulfide bond isomerase, but not on DsbB. We show that overexpressed PspE is oxidized to the sulfenic acid form and reacts with substrate proteins to form mixed disulfide adducts. DsbC either prevents the formation of these mixed disulfides or resolves these adducts subsequently. In the process, DsbC itself gets oxidized and proceeds to catalyze disulfide bond formation. Although this PspE/DsbC system is not responsible for the background disulfide bond forming activity, we suggest that it might be utilized in other organisms lacking the DsbA/DsbB system. PMID:22809289

  17. Characterisation of baroque tin amalgam mirrors of the historical Green Vault in Dresden

    NASA Astrophysics Data System (ADS)

    Zywitzki, O.; Nedon, W.; Kopte, T.; Modes, T.

    2008-07-01

    The historical Green Vault, one of Europe’s most sumptuous treasure chambers, has reopened in September 2006 in the Dresden Royal Palace. For the baroque presentation of the artworks the special properties of tin amalgam mirrors are of great importance. A comprehensive analytic characterisation was necessary for restoration and reconstruction. The different original casting glasses were analysed in respect of chemical composition, roughness, waviness and optical properties like chromaticity coordinates and transmittance. The microstructure of the tin amalgam layers were investigated on metallographic cross-sections and by X-ray diffraction. The investigations reveal that the tin amalgam layers are composed of γ-HgSn6-10 phase with a grain size between 5 and 50 μm surrounded by a thin mercury phase with about 2 wt. % tin. However the most important property of the baroque tin amalgam mirrors is a relative low reflectivity of about 59% which is drastically lower than for silver mirrors with a reflectivity of about 96%. According to the characterisation results a suitable glass for reconstruction was selected. The mirror layers were produced by historical tin amalgam technology for the rooms not destroyed by bombarding of Dresden in February 1945. For the completely destroyed Jewel Room pure tin layers were deposited by magnetron sputtering. The results show that this new technology enables an adequate substitute for the original tin amalgam layers.

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

    PubMed

    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 < 0.05. Most of the restorations received an overall score of alpha, except two restorations, which showed a slight discrepancy at the composite-amalgam interface after one year (p > 0.05). Four restorations exhibited slight discoloration of the composite veneering after three years (p < 0.05). No restoration exhibited fracture after three years. It was concluded that combined composite-amalgam cusp coverage of endodontically-treated maxillary premolars showed acceptable clinical performance after three years.

  19. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... is intended for filling dental caries. (b) Classification. Class I (general controls). The device is... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A...

  20. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... is intended for filling dental caries. (b) Classification. Class I (general controls). The device is... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A...

  1. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... is intended for filling dental caries. (b) Classification. Class I (general controls). The device is... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A...

  2. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... is intended for filling dental caries. (b) Classification. Class I (general controls). The device is... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A...

  3. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... is intended for filling dental caries. (b) Classification. Class I (general controls). The device is... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A...

  4. A Comparison between Shear Bond Strength of VMK Master Porcelain with Three Base-metal Alloys (Ni-cr-T3, VeraBond, Super Cast) and One Noble Alloy (X-33) in Metal-ceramic Restorations

    PubMed Central

    Ahmadzadeh, A; Neshati, A; Mousavi, N; Epakchi, S; Dabaghi Tabriz, F; Sarbazi, AH

    2013-01-01

    Statement of Problem: The increase in the use of metal-ceramic restorations and a high prevalence of porcelain chipping entails introducing an alloy which is more compatible with porcelain and causes a stronger bond between the two. This study is to compare shear bond strength of three base-metal alloys and one noble alloy with the commonly used VMK Master Porcelain. Materials and Method: Three different groups of base-metal alloys (Ni-cr-T3, Super Cast, and VeraBond) and one group of noble alloy (X-33) were selected. Each group consisted of 15 alloy samples. All groups went through the casting process and change from wax pattern into metal disks. The VMK Master Porcelain was then fired on each group. All the specimens were put in the UTM; a shear force was loaded until a fracture occurred and the fracture force was consequently recorded. The data were analyzed by SPSS Version 16 and One-Way ANOVA was run to compare the shear strength between the groups. Furthermore, the groups were compared two-by-two by adopting Tukey test. Results: The findings of this study revealed shear bond strength of Ni-Cr-T3 alloy was higher than the three other alloys (94 MPa or 330 N). Super Cast alloy had the second greatest shear bond strength (80. 87Mpa or 283.87 N). Both VeraBond (69.66 MPa or 245 N) and x-33 alloys (66.53 MPa or 234 N) took the third place. Conclusion: Ni-Cr-T3 with VMK Master Porcelain has the greatest shear bond strength. Therefore, employment of this low-cost alloy is recommended in metal-ceramic restorations. PMID:24724144

  5. Making High-Tensile-Strength Amalgam Components

    NASA Technical Reports Server (NTRS)

    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

  6. Restoring Bonds of Respect

    ERIC Educational Resources Information Center

    Brokenleg, Martin

    2014-01-01

    In writing about the Circle of Courage, Martin Brokenleg and his co-authors brought together different professions, racial backgrounds, and upbringing (Brendtro, Brokenleg, & Van Bockern, 2002). While the Circle of Courage philosophy transcends culture, they initially used Native American images and stories to express these ideas. Because…

  7. A comparative study of shear bond strength between metal and ceramic brackets and artificially aged composite restorations using different surface treatments.

    PubMed

    Eslamian, Ladan; Borzabadi-Farahani, Ali; Mousavi, Nasim; Ghasemi, Amir

    2012-10-01

    This in vitro study evaluated the shear bond strength (SBS) between ceramic brackets (CBs) and resin composite restorations (RCRs) prepared using different surface treatments. The findings were also compared with a similar study that used stainless steel brackets (SSBs). Forty-five premolars were restored with a nano-hybrid composite resin (Tetric EvoCeram) and randomly assigned to three surface treatment groups: group 1, 5 per cent hydrofluoric acid (HF); group 2, air abrasion (50 μm alumina particles); and group 3, diamond bur. Specimens were bonded with CBs (Fascination) and exposed to thermo-cycling (500 cycles). The shear force at a crosshead speed of 1 mm/minute was transmitted to brackets. The adhesive remnant index (ARIs) scores were recorded after bracket failure. The analysis of SBS variance (P < 0.01) and chi-square test of ARIs scores (P < 0.01) revealed significant differences among three groups tested. The SBS in group 3 (mean: 26.34 ± 4.76 MPa) and group 2 (mean: 26.68 ± 5.93 MPa) was significantly higher than group 1 (mean: 16.25 ± 5.42 MPa). The SBS was significantly higher in CBs (mean: 23.09 ± 7.19 MPa) compared to SSBs (mean: 15.56 ± 5.13 MPa). High ARIs (100 per cent) occurred in SSBs treated with a diamond bur, whereas CBs primarily failed at the resin-adhesive interface (P < 0.01). In two-thirds of the specimens (SSBs or CBs), no adhesive was left on the restoration after HF conditioning. The ARIs profile of CBs and SSBs that received surface treatments with air abrasion were similar (P > 0.05) and bond failure occurred mainly in adhesive-bracket base and resin-adhesive interfaces. The diamond bur surface treatment is recommended as a safe and cost-effective method of bonding CBs to RCRs.

  8. Radiochemical separation of gold by amalgam exchange

    USGS Publications Warehouse

    Ruch, R.R.

    1970-01-01

    A rapid and simple method for the radiochemical separation of gold after neutron activation. The technique is based on treatment with a dilute indium-gold amalgam, both chemical reduction and isotopic exchange being involved. The counting efficiency for 198Au in small volumes of the amalgam is good. Few interferences occur and the method is applicable to clays, rocks, salts and metals. The possibility of determining silver, platinum and palladium by a similar method is mentioned. ?? 1970.

  9. Radiochemical separation of gallium by amalgam exchange

    USGS Publications Warehouse

    Ruch, R.R.

    1969-01-01

    An amalgam-exchange separation of radioactive gallium from a number of interfering radioisotopes has been developed. A dilute (ca. 0.3%) gallium amalgam is agitated with a slightly acidic solution of 72Ga3+ containing concentrations of sodium thiocyanate and either perchlorate or chloride. The amalgam is then removed and the radioactive gallium stripped by agitation with dilute nitric acid. The combined exchange yield of the perchlorate-thiocyanate system is 90??4% and that of the chloride-thiocyanate system is 75??4%. Decontamination yields of most of the 11 interfering isotopes studied were less than 0.02%. The technique is applicable for use with activation analysis for the determination of trace amounts of gallium. ?? 1969.

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

    PubMed

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

    2012-11-01

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

  11. 21 CFR 872.3110 - Dental amalgam capsule.

    Code of Federal Regulations, 2010 CFR

    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...

  12. Electrical potentials of restorations in subjects without oral complaints.

    PubMed

    Muller, A W; Van Loon, L A; Davidson, C L

    1990-09-01

    The electrical potentials of 183 amalgam and 11 precious metal restorations, and one set of brackets, were measured. None of the 28 subjects had galvanism, leukoplakia, oral lichen planus, or toxic or allergic reactions to restorations. The potentials of the amalgam restorations increased with age, from about -350 mV NHE at 30 days, to about +100 mV NHE after more than 1000 days. In most subjects potential differences of more than 50 mV were present between restorations; this phenomenon is therefore assumed to be common in healthy populations.

  13. Marginal microleakage of cervical composite resin restorations bonded using etch-and-rinse and self-etch adhesives: two dimensional vs. three dimensional methods

    PubMed Central

    Khoroushi, Maryam

    2016-01-01

    Objectives This study was evaluated the marginal microleakage of two different adhesive systems before and after aging with two different dye penetration techniques. Materials and Methods Class V cavities were prepared on the buccal and lingual surfaces of 48 human molars. Clearfil SE Bond and Single Bond (self-etching and etch-and-rinse systems, respectively) were applied, each to half of the prepared cavities, which were restored with composite resin. Half of the specimens in each group underwent 10,000 cycles of thermocycling. Microleakage was evaluated using two dimensional (2D) and three dimensional (3D) dye penetration techniques separately for each half of each specimen. Data were analyzed with SPSS 11.5 (SPSS Inc.), using the Kruskal-Wallis and Mann-Whitney U tests (α = 0.05). Results The difference between the 2D and 3D microleakage evaluation techniques was significant at the occlusal margins of Single bond groups (p = 0.002). The differences between 2D and 3D microleakage evaluation techniques were significant at both the occlusal and cervical margins of Clearfil SE Bond groups (p = 0.017 and p = 0.002, respectively). The difference between the 2D and 3D techniques was significant at the occlusal margins of non-aged groups (p = 0.003). The difference between these two techniques was significant at the occlusal margins of the aged groups (p = 0.001). The Mann-Whitney test showed significant differences between the two techniques only at the occlusal margins in all specimens. Conclusions Under the limitations of the present study, it can be concluded that the 3D technique has the capacity to detect occlusal microleakage more precisely than the 2D technique. PMID:27200275

  14. Analysis of Resin-Dentin Interface Morphology and Bond Strength Evaluation of Core Materials for One Stage Post-Endodontic Restorations

    PubMed Central

    Bitter, Kerstin; Gläser, Christin; Neumann, Konrad; Blunck, Uwe; Frankenberger, Roland

    2014-01-01

    Purpose Restoration of endodontically treated teeth using fiber posts in a one-stage procedure gains more popularity and aims to create a secondary monoblock. Data of detailed analyses of so called “post-and-core-systems” with respect to morphological characteristics of the resin-dentin interface in combination with bond strength measurements of fiber posts luted with these materials are scarce. The present study aimed to analyze four different post-and-core-systems with two different adhesive approaches (self-etch and etch-and-rinse). Materials and Methods Human anterior teeth (n = 80) were endodontically treated and post space preparations and post placement were performed using the following systems: Rebilda Post/Rebilda DC/Futurabond DC (Voco) (RB), Luxapost/Luxacore Z/Luxabond Prebond and Luxabond A+B (DMG) (LC), X Post/Core X Flow/XP Bond and Self Cure Activator (Dentsply DeTrey) (CX), FRC Postec/MultiCore Flow/AdheSE DC (Ivoclar Vivadent) (MC). Adhesive systems and core materials of 10 specimens per group were labeled using fluorescent dyes and resin-dentin interfaces were analyzed using Confocal Laser Scanning Microscopy (CLSM). Bond strengths were evaluated using a push-out test. Data were analyzed using repeated measurement ANOVA and following post-hoc test. Results CLSM analyses revealed significant differences between groups with respect to the factors hybrid layer thickness (p<0.0005) and number of resin tags (p = 0.02; ANOVA). Bond strength was significantly affected by core material (p = 0.001), location inside the root canal (p<0.0005) and incorporation of fluorescent dyes (p = 0.036; ANOVA). CX [7.7 (4.4) MPa] demonstrated significantly lower bond strength compared to LC [14.2 (8.7) MPa] and RB [13.3 (3.7) MPa] (p<0.05; Tukey HSD) but did not differ significantly from MC [11.5 (3.5) MPa]. Conclusion It can be concluded that bond strengths inside the root canal were not affected by the adhesive approach of the post

  15. Amalgam Surface Treatment by Different Output Powers of Er:YAG Laser:SEM Evaluation

    PubMed Central

    Hosseini, Mohammad Hashem; Hassanpour, Mehdi; Etemadi, Ardavan; Ranjbar Omrani, Ladan; Darvishpour, Hojat; Chiniforush, Nasim

    2015-01-01

    Introduction: The purpose of this study was to evaluate amalgam surfaces treated by different output powers of erbium-doped yttrium aluminum garnet (Er:YAG) laser by scanning electron microscope (SEM). Methods: Twenty-one amalgam blocks (8 mm × 8 mm, 3 mm thickness) were prepared by condensing silver amalgam (into putty impression material. After keeping them for 24 hours in distilled water, they were divided into 7 groups as follow: G1: Er:YAG laser (1 W, 50 mJ), G2: Er:YAG laser (2 W, 100 mJ), G3: Er:YAG laser (3 W, 150 mJ), G4: Sandblast, G5: Sandblast + Er:YAG laser (1 W, 50 mJ), G6: Sandblast +Er:YAG laser (2 W, 100 mJ) and G7: Sandblast +Er:YAG laser (3 W, 150 mJ). Then after preparation of all samples, they were examined by SEM. Results: The SEM results of amalgam surfaces treated by different output powers of Er:YAG laser showed some pitting areas with non-homogenous irregularities Conclusion: It seems that the application of sandblasting accompanied by Er:YAG laser irradiation can provide proper surface for bonding of orthodontic brackets. PMID:26705463

  16. Antibacterial properties of amalgam and composite resin materials used as cores under crowns.

    PubMed

    Al Ghadban, A; Al Shaarani, F

    2012-06-01

    The Aim of this Study was to compare the bacterial growth in the bulk of both amalgam and fluoridated composite resin materials used as cores under crowns at core's surface (in the superficial area of the bulk) and depth levels. With 24 lower premolars, 12 of them were restored with metal posts and amalgam cores (group 1). The rest were restored with glass Fiber-reinforced Composite (FRC) posts and fluoridated composite resin cores (group 2). All specimens were covered with aluminium crowns cemented with resin cement, and then they were soaked in natural saliva for three months. Excoriations abraded from the superficial and the depth areas of the core materials were cultured under aerobic conditions on blood agar plates. After incubation for 2 days, colonies formed on the plates were identified, and the CFU mg(-1) counts were recorded accordingly. Statistical analysis was performed using an independent sample T test. The mean values of CFU mg(-1) counts in group 2 excoriations (surface 39.75, and depth 9.75) were higher than the group 1 excoriations (surface 1.67, and depth 0.42). This study supports the use of amalgam for building up cores due to its antibacterial properties. Composite resin, however, enhanced sizable bacterial growth despite the presence of fluoride.

  17. Effect of dental amalgam on gene expression profiles in rat cerebrum, cerebellum, liver and kidney.

    PubMed

    Takahashi, Yoshifumi; Tsuruta, Shozo; Honda, Akiko; Fujiwara, Yasuyuki; Satoh, Masahiko; Yasutake, Akira

    2012-01-01

    Dental amalgam is a source of exposure to elemental mercury vapor in the general population. The aim of this study was to elucidate the effect of elemental mercury vapor exposure from dental amalgam restorations on gene expression profiles. Out of 26,962 rat genes, mercury vapor was found to increase the expression of 1 gene (Atp1b3) and decrease the expression of 1 gene (Tap1) in the cerebrum, increase the expression of 1 gene (Dnaja2) in the cerebellum, increase the expression of 2 genes (Actb and Timm23) and decrease the expression of 1 gene (Spink3) in the liver, increase the expression of 2 genes (RT1-Bb and Mgat5) and decrease the expression of 6 genes (Tnfaip8, Rara, Slc2a4, Wdr12, Pias4 and Timm13) in the kidney.

  18. Direct metallic amalgam alternative: a research update.

    PubMed

    Eichmiller, F C; Marjenhoff, W A; Dariel, M P; Lashmore, D S

    1996-01-01

    Discussions between two group leaders at the National Institute of Standards and Technology (NIST) led to the suggestion that a mercury-free, silver-based material could be used for dental direct-filling applications. This concept brought about a new approach that, nonetheless, is still based on powder technology such as amalgams. The resulting material also retains the tin and silver components of conventional amalgams. The condensation of a loose powder mixture into a cohesive solid relies, however, on cold-welding across atomically clean silver-silver interfaces after a mild acid treatment of the surfaces. The National Institute of Dental Research (NIDR) and American Dental Association Health Foundation (ADAHF) became involved in the research in 1992, and ADAHF scientists continue to collaborate with NIST metallurgists and electrochemists toward the further development of this promising new technology.

  19. Fracture resistance of cuspal coverage of endodontically treated maxillary premolars with combined composite-amalgam compared to other techniques.

    PubMed

    Shafiei, F; Memarpour, M; Karimi, F

    2011-01-01

    This in vitro study investigated the fracture resistance of teeth restored with combined composite-amalgam for cuspal coverage compared to direct coverage with composite (with or without an amalgam base) and composite onlay. Seventy-two intact maxillary premolars were randomly divided into six groups (n=12). The two control groups were G1, intact teeth (negative control), and G2, mesio-occlusodistal preparation only (positive control). Each of the four experimental groups used a different type of restoration for the prepared teeth: G3, direct composite cusp coverage; G4, composite onlay; G5, direct composite coverage with an amalgam base; and G6, combined composite-amalgam cuspal coverage. After thermocycling, fracture strength was tested. The data were analyzed with analysis of variance and the least significant differences post hoc tests (α=0.05). Mean fracture resistance in the six groups (in N) were G1, 1101 ±1 86; G2, 228 ± 38; G2, 699 ± 161; G4, 953 ± 185; G5, 859 ± 146; and G6, 772 ± 154. There were significant differences between G1 and all the other groups except for G4 and between G2 and all the other groups. Fracture strength in G3 also differed significantly compared to G4 and G5. The difference between G4 and G6 was statistically significant (p<0.05), but the difference between G3 and G6 was not (p>0.05).

  20. Conventional glass ionomers as posterior restorations. A status report for the American Journal of Dentistry.

    PubMed

    Naasan, M A; Watson, T F

    1998-02-01

    The search for a material to replace amalgam continues as a major quest in materials science. Resin composites may offer one solution but an alternative class of material, the glass ionomer cements (GICs) may have some potential for fulfilling this role. GICs were first introduced to the dental profession in 1976, and have now become an accepted part of the dental armamentarium, especially for use in low load bearing situations. They possess a low coefficient of thermal expansion similar to that of tooth structure, physicochemical bonding to both enamel and dentin, and the release of fluoride ions into the adjacent tooth tissue. These properties help to reduce marginal leakage and may contribute to a reduced incidence of recurrent decay in the restored tooth. Fluoride released into the ambient fluids has a caries-preventive effect in neighboring teeth by enhancing remineralization and inhibiting demineralization of the dental hard tissues. The main criticisms of the GICs are their brittleness, poor surface polish, porosity and surface wear. To overcome some of these deficiencies, considerable attention has been directed at improving their physical properties, especially with the addition of metal powders, the metal-modified GICs. Different metal powders have been tried, including alloys of silver and tin, pure silver, gold, titanium, palladium and stainless steel. There is conflicting data as to whether or not these materials are sufficiently strong for use in high stress restorations, especially their potential use as replacement materials for amalgam fillings.

  1. The tarnished history of a posterior restoration.

    PubMed

    Rose, M D; Costello, J P

    1998-11-14

    Galvanic corrosion is an electrochemical reaction between dissimilar metals that has the potential to cause unpleasant and even painful biological effects intra-orally. A case is presented where a full gold crown underwent galvanic change after being placed in contact with an amalgam restoration.

  2. METHOD AND APPARATUS FOR DETERMINING AMALGAM DECOMPOSITION RATE

    DOEpatents

    Johnson, R.W.; Wright, C.C.

    1962-04-24

    A method and apparatus for measuring the rate at which an amalgam decomposes in contact with aqueous solutions are described. The amalgam and an aqueous hydroxide solution are disposed in an electrolytic cell. The amalgam is used as the cathode of the cell, and an electrode and anode are disposed in the aqueous solution. A variable source of plating potential is connected across the cell. The difference in voltage between the amalgam cathode and a calibrated source of reference potential is used to control the variable source to null the difference in voltage and at the same time to maintain the concentration of the amalgam at some predetermined constant value. The value of the current required to maintain this concentration constant is indicative of the decomposition rate of the amalgam. (AEC)

  3. Restoration Materials and Secondary Caries Using an In Vitro Biofilm Model

    PubMed Central

    van de Sande, F.H.; Opdam, N.J.M.; Bronkhorst, E.M.; de Soet, J.J.; Cenci, M.S.; Huysmans, M.C.D.J.N.M.

    2015-01-01

    This in vitro study investigated whether restoration materials and adhesives influence secondary caries formation in gaps using a short-term in vitro biofilm model. Sixty enamel–dentin blocks were restored with 6 different restoration materials with or without adhesives (n = 10 per group) with a gap: 1) Clearfil AP-X composite, 2) Clearfil AP-X composite + SE Bond, 3) Clearfil AP-X composite + ProtectBond, 4) Filtek Silorane composite, 5) Filtek Silorane composite + Silorane System adhesive, or 6) Tytin amalgam. Specimens were subjected to an intermittent 1% sucrose biofilm model for 20 days to create artificial caries lesions. Lesion progression in the enamel–dentin next to the different materials was measured in lesion depth (LD) and mineral loss (ML) using transversal wavelength independent microradiography (T-WIM). A regression analysis was used to compare the LD and ML of the different restoration materials at 4 measurement locations: 1 location at the surface of the enamel, 1 location at the wall of the enamel, and 2 locations at the wall of the dentin. A statistically significant effect of AP-X composite with Protect Bond was found for LD and ML at the WallDentin1 location, leading to less advanced wall lesions. An additional finding was that gap size was also statistically significant at the 2 wall locations in dentin, leading to increasing lesion progression with wider gaps. In conclusion, adhesives can influence wall lesion development in gaps. Protect Bond showed significantly less caries progression compared to bare restoration materials or other adhesives in this short-term in vitro biofilm model. PMID:25297114

  4. 48. INTERIOR VIEW FROM THE WEST END OF THE AMALGAMATION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    48. INTERIOR VIEW FROM THE WEST END OF THE AMALGAMATION TABLES LOOKING NORTH TOWARDS THE STAMP BATTERIES WITH AMALGAM TRAPS SHOWN IN THE BOTTOM FOREGROUND. NOTE THE EXTANT EQUIPMENT IN THE FOREGROUND THAT THE PARK USES TO INTERPRET THE MILL. FROM LEFT TO RIGHT, A SCREEN FROM THE MORTAR BOX, A STAMP STOP. A (HUMAN'S) SHOE, A DIE FROM THE BOTTOM OF A MORTAR BOX, AN AMALGAM SCRAPPER AND AN AMALGAM BUCKET. - Standard Gold Mill, East of Bodie Creek, Northeast of Bodie, Bodie, Mono County, CA

  5. Assessing microleakage of different class V restorations after Er:YAG laser and bur preparation.

    PubMed

    Corona, S A M; Borsatto, M C; Pecora, J D; De SA Rocha, R A S; Ramos, T S; Palma-Dibb, R G

    2003-10-01

    This study assessed in vitro marginal leakage of class V cavities prepared by turbine and Er:YAG laser and restored with different materials. Sixty cavities with enamel and dentine margins were prepared and assigned to six groups: I, II, III by turbine and IV, V, VI by Er:YAG laser. The following restorative systems were used: groups I and IV: Bond 1 + Alert; II and V: Fuji II LC; III and VI: SBMP + Dispersalloy. After finishing, specimens were thermocycled for 8 h and 45 min (500 cycles), isolated, immersed in a 0.2% Rhodamine B solution, sectioned oro-facially and analysed for leakage. The dye penetration means (%) were: occlusal I: 10.09 (+/- 21.28), II: 3.25 (+/- 10.27), III: 0, IV: 41.77 (+/- 42.48), V: 23.37 (+/- 33.79), VI: 12.66 (+/- 24.06); cervical I: 16.49 (+/- 26.67), II: 4.34 (+/- 13.71), III: 0, IV: 37.71 (+/- 30.47), V: 39.56 (+/- 43.35) and VI: 72.53 (+/- 37.79). The use of Er:YAG laser for cavity preparation yielded higher degree of marginal leakage, as compared with the use of conventional air-turbine. The enamel interface provided better marginal sealing, comparing with dentine/cementum margin. As to the cavity preparation device (i.e. laser or bur), the analysis of the results showed that bonded amalgam and Fuji II LC provided less infiltration, than Alert. On the other hand, for lased cavities, Alert provided the best results, similar to those of Fuji II LC and superior to those reached by bonded amalgam.

  6. Allergy to dental materials with special reference to the use of amalgam and polymethylmethacrylate.

    PubMed

    Kaaber, S

    1990-12-01

    The increase in new clinical materials with questionable biological properties and the corresponding increase in awareness in patients to health hazards from dental materials are two important problems of modern clinical dentistry. Based upon evidence from clinical research the hypersensitivity problems related to the use of silver amalgam and acrylic denture base materials are reviewed to define possible risk groups among dental patients. In silver amalgam therapy the main risk group is patients with contact lesions in the oral mucosa adjacent to the restorations, as this group exhibits a high frequency of skin sensitivity to mercury and other base materials in dental amalgam. Among denture wearers a corresponding risk group has been observed among patients with previous allergic diseases and burning mouth syndrome. In these cases a high incidence of skin sensitivity reactions to denture allergens has been observed, usually to methylmethacrylate monomer and formaldehyde. Some possible pathogenic mechanisms leading to a contact allergy of the oral mucosa in these patient groups are discussed.

  7. Association between History of Dental Amalgam Fillings and Risk of Parkinson’s Disease: A Population-Based Retrospective Cohort Study in Taiwan

    PubMed Central

    Hsu, Yung-Chuang; Chang, Cheng-Wei; Lee, Hsin-Lin; Chuang, Chuan-Chung; Chiu, Hsien-Chung; Li, Wan-Yun; Horng, Jorng-Tzong; Fu, Earl

    2016-01-01

    The impact of dental amalgam on the development of Parkinson’s disease (PD) is still uncertain, although a positive association between dental amalgam and PD has been found in a few case-control studies. The patients with amalgam fillings restored between 2000 and 2008 were identified by using the National Health Insurance Research Database (NHIRD) in Taiwan. The same number of patients who had no new amalgam filling restored was matched by sex, age, and treatment date. Both cohorts were followed up from the treatment date until the date of diagnosis of PD, death, or the end of the year 2008. The individuals who received amalgam fillings had a significantly higher risk of PD afterward (adjusted hazard ratio [HR]=1.583, 95% confidence interval [CI]=1.122–2.234, p=0.0089) than those who did not. In the individuals who received amalgam fillings, being diagnosed with diabetes or hyperlipidemia demonstrated a significantly lower HR of PD occurrence than in the patients without diabetes or hyperlipidemia (HR=0.449, 95% CI=0.254–0.794, p=0.0059; HR=0.445, 95% CI=0.260–0.763, p=0.0032) after adjusting for comorbidities and Charlson-Deyo Comorbidity Index (CCI) scores. Meanwhile, hypertension increased the hazard risk of PD (HR=1.645, 95% CI=1.098–2.464, p=0.0159). The patients exposed to dental amalgam fillings were 1.583 times more likely to have PD afterward compared to their non-exposed counterparts after adjusting for comorbidities and CCI scores. PMID:27906991

  8. Association between History of Dental Amalgam Fillings and Risk of Parkinson's Disease: A Population-Based Retrospective Cohort Study in Taiwan.

    PubMed

    Hsu, Yung-Chuang; Chang, Cheng-Wei; Lee, Hsin-Lin; Chuang, Chuan-Chung; Chiu, Hsien-Chung; Li, Wan-Yun; Horng, Jorng-Tzong; Fu, Earl

    2016-01-01

    The impact of dental amalgam on the development of Parkinson's disease (PD) is still uncertain, although a positive association between dental amalgam and PD has been found in a few case-control studies. The patients with amalgam fillings restored between 2000 and 2008 were identified by using the National Health Insurance Research Database (NHIRD) in Taiwan. The same number of patients who had no new amalgam filling restored was matched by sex, age, and treatment date. Both cohorts were followed up from the treatment date until the date of diagnosis of PD, death, or the end of the year 2008. The individuals who received amalgam fillings had a significantly higher risk of PD afterward (adjusted hazard ratio [HR]=1.583, 95% confidence interval [CI]=1.122-2.234, p=0.0089) than those who did not. In the individuals who received amalgam fillings, being diagnosed with diabetes or hyperlipidemia demonstrated a significantly lower HR of PD occurrence than in the patients without diabetes or hyperlipidemia (HR=0.449, 95% CI=0.254-0.794, p=0.0059; HR=0.445, 95% CI=0.260-0.763, p=0.0032) after adjusting for comorbidities and Charlson-Deyo Comorbidity Index (CCI) scores. Meanwhile, hypertension increased the hazard risk of PD (HR=1.645, 95% CI=1.098-2.464, p=0.0159). The patients exposed to dental amalgam fillings were 1.583 times more likely to have PD afterward compared to their non-exposed counterparts after adjusting for comorbidities and CCI scores.

  9. 21 CFR 872.3110 - Dental amalgam capsule.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Dental amalgam capsule. 872.3110 Section 872.3110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3110 Dental amalgam capsule. (a) Identification....

  10. 21 CFR 872.3110 - Dental amalgam capsule.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Dental amalgam capsule. 872.3110 Section 872.3110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3110 Dental amalgam capsule. (a) Identification....

  11. 21 CFR 872.3110 - Dental amalgam capsule.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Dental amalgam capsule. 872.3110 Section 872.3110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3110 Dental amalgam capsule. (a) Identification....

  12. 21 CFR 872.3110 - Dental amalgam capsule.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Dental amalgam capsule. 872.3110 Section 872.3110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3110 Dental amalgam capsule. (a) Identification....

  13. Terrane amalgamation in the Philippine Sea margin

    NASA Astrophysics Data System (ADS)

    Hall, Robert; Nichols, Gary J.

    1990-09-01

    The Philippine Sea plate includes plateaus of thickened crust interpreted as imbricated ophiolite and arc-related terranes of late Mesozoic-early Tertiary age separated by thinner oceanic crust. The arrival of plateaus at the subducting southwest margin of the Philippine Sea plate has caused the Philippine Trench to propagate southward in increments and caused transfer of terranes to the Philippine margin. New data from the Halmahera region indicate that the position, nature and evolution of plate boundaries have been strongly influenced by the heterogeneous character of the Philippine Sea plate. At present the Philippine Trench terminates at an oceanic plateau which is structurally continuous with an old forearc and ophiolite terrane on Halmahera. The position of this terrane has caused Philippine Sea plate-Eurasia convergence to be transferred from subduction at the Philippine Trench to the Molucca Sea Collision Zone through a broad NE-SW dextral transpressional zone across Halmahera. This plate boundary configuration is unstable and requires the future development of a new subduction zone to the east of Halmahera which will result in amalgamation of the Halmahera ophiolite terrane to the Philippine margin. In the Halmahera region amalgamation of terranes to the evolving Philippine microcontinent is currently in process.

  14. Minimally invasive prosthetic restoration of posterior tooth loss with resin-bonded, wing-retained, and inlay-retained fixed dental prostheses fabricated from monolithic zirconia: A clinical report of two patients.

    PubMed

    Bömicke, Wolfgang; Karl, Jochen; Rammelsberg, Peter

    2017-04-01

    The esthetics and biocompatibility of ceramic resin-bonded fixed dental prostheses (RBFDPs) are regarded as better than those of their metal ceramic counterparts. However, a high incidence of complications in the posterior arches of ceramic RBFDPs initiated a process of continuous and evolving design development. This clinical report describes 2 successful restorations of a missing posterior tooth with monolithic zirconia RBFDPs with 2 different retainer designs: retentively prepared adhesive wings and inlays.

  15. Mercury in saliva and feces after removal of amalgam fillings.

    PubMed

    Björkman, L; Sandborgh-Englund, G; Ekstrand, J

    1997-05-01

    The toxicological consequences of exposure to mercury (Hg) from dental amalgam fillings is a matter of debate in several countries. The purpose of this study was to obtain data on Hg concentrations in saliva and feces before and after removal of dental amalgam fillings. In addition Hg concentrations in urine, blood, and plasma were determined. Ten subjects had all amalgam fillings removed at one dental session. Before removal, the median Hg concentration in feces was more than 10 times higher than in samples from an amalgam free reference group consisting of 10 individuals (2.7 vs 0.23 mumol Hg/kg dry weight, p < 0.001). A considerable increase of the Hg concentration in feces 2 days after amalgam removal (median 280 mumol Hg/kg dry weight) was followed by a significant decrease. Sixty days after removal the median Hg concentration was still slightly higher than in samples from the reference group. In plasma, the median Hg concentration was 4 nmol/liter at baseline. Two days after removal the median Hg concentration in plasma was increased to 5 nmol/liter and declined subsequently to 1.3 nmol/liter by Day 60. In saliva, there was an exponential decline in the Hg concentration during the first 2 weeks after amalgam removal (t 1/2 = 1.8 days). It was concluded that amalgam fillings are a significant source of Hg in saliva and feces. Hg levels in all media decrease considerably after amalgam removal. The uptake of amalgam mercury in the GI tract in conjunction with removal of amalgam fillings seems to be low.

  16. The challenge for innovation in direct restorative materials.

    PubMed

    Bayne, S; Petersen, P E; Piper, D; Schmalz, G; Meyer, D

    2013-11-01

    During the past 50 years, a series of key UN conferences have established a framework to minimize human health risks from environmental exposures to key chemicals. In January 2013, more than 140 countries agreed to the text of new treaty to minimize Hg effects on the environment (the Minamata Convention). Dental caries is omnipresent around the globe, affecting 60% to 90% of school children and most adults, and producing discomfort that affects quality of life. Dental amalgam is frequently used to treat carious lesions and its use releases mercury into the environment. The best way to avoid the use of dental amalgam is to emphasize caries prevention. Alternatives to amalgam are suitable in some applications, but no replacement for amalgam has been found for large posterior restorations. For any restorative material, safety and environmental impacts are part of clinical risk assessment. Safety is freedom from unacceptable risks. Risk is a combination of probability of exposure and severity of harm. Best management practices are crucial to manage dental amalgam, but these impose additional that are disproportionately more for developing countries. The Minamata Convention seeks a phase-out of all mercury-based products except dental amalgam, where a phase-down is the present goal. For dentistry, the most important focus is the promotion of caries prevention and research on new materials.

  17. Comparative evaluation of strength of various core restorative materials for endodontically treated anterior teeth.

    PubMed

    Dabas, V K

    2000-01-01

    In the present study, four restorative materials were used for the restoration of endodontically treated anterior teeth and their strength were compared with that of natural teeth. 100 freshly extracted Maxillary Central Incisors were used. The teeth were restored with Pin-retained amalgam-core buildups, Dowel-post with Glass ionomer-Amalgam alloy combination Cast Core build up. The natural tooth showed the maximum strength. Though some of the restorative materials showed promising results, none of them is able to show strength anywhere near to that of natural tooth.

  18. 75 FR 33169 - Dental Devices: Classification of Dental Amalgam, Reclassification of Dental Mercury, Designation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-11

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

  19. Stress Relaxation of High-Copper Amalgam Alloys,

    DTIC Science & Technology

    1978-03-10

    Unlimited ~~~ 17. DISTRIBUTION STA ~~EMENT (of th. ab.traci .nt. r.d In Block 20. i di f ferent from Report) 1$. SUPPLEMENTARY NOTES IS. KEY WORDS...Contlnu• on r.v.,a. aid. SI n.c...ay aid Id.ntlfy by block niaib. r) Amalgam alloys; high—copper amalgam alloys; viscoelastic properties and stress...relaxation. 20. ABSTRACT (Ge.~~~j . ai r, ,.,.. .i~~ II ne.ma y d Sd.nsSfr by block n~~~)5 tress relaxation of sevenhigh— copper dental amalgam alloys was

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

    PubMed Central

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

    2016-01-01

    Background: Many patients have complex health complaints they attribute to dental amalgam. There is some evidence of symptom relief after removal of amalgam. Objective: 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. Methods: 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. Results: 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. Conclusion: 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. PMID:28217190

  1. Durable bonds at the adhesive/dentin interface: an impossible mission or simply a moving target?

    PubMed Central

    SPENCER, Paulette; Jonggu PARK, Qiang YE; MISRA, Anil; BOHATY, Brenda S.; SINGH, Viraj; PARTHASARATHY, Ranga; SENE, Fábio; de Paiva GONÇALVES, Sérgio Eduardo; LAURENCE, Jennifer

    2013-01-01

    Composite restorations have higher failure rates, more recurrent caries and increased frequency of replacement as compared to dental amalgam. Penetration of bacterial enzymes, oral fluids, and bacteria into the crevices between the tooth and composite undermines the restoration and leads to recurrent decay and failure. The gingival margin of composite restora tions is particularly vulnerable to decay and at this margin, the adhesive and its seal to dentin provides the primary barrier between the prepared tooth and the environment. The intent of this article is to examine physico-chemical factors that affect the integrity and durability of the adhesive/dentin interfacial bond; and to explore how these factors act synergistically with mechanical forces to undermine the composite restoration. The article will examine the various avenues that have been pursued to address these problems and it will explore how alterations in material chemistry could address the detrimental impact of physico-chemical stresses on the bond formed at the adhesive/dentin interface. PMID:24855586

  2. British Society of Prosthodontics Debate on the Implications of the Minamata Convention on Mercury to Dental Amalgam--Should our Patients be Worried?.

    PubMed

    Austin, Rupert; Eliyas, Shiyana; Burke, F J Trevor; Taylor, Phil; Toner, James; Briggs, Peter

    2016-01-01

    In 2013, the Minamata Convention on Mercury called for a global phase-down of amalgam use, with a view to reduce environmental mercury pollution. This will significantly impact UK dentistry, given the still extensive use of amalgam in U.K. general dental practice. However, until now there has been little national discussion or debate. In Spring 2015, The British Society of Prosthodontics dedicated a significant part of its Annual Conference to debating the implications of this issue. Clinical case examples were discussed with audience interaction and voting facilitated using innovative Audience Response System Technology. A remarkable range of concerns and opinions were given. The debate elicited specific concerns amongst clinicians regarding the suitability of mercury-free alternatives to amalgam; particularly where cavities are large and extend beneath the gingival anatomy. There are also anecdotal reports of Dental Foundation (DF) dentists not being adequately taught the use of dental amalgam in undergraduate dental schools. CPD/CLINICAL RELEVANCE: Many clinicians, especially those treating patients for whom moisture control is challenging, feel that amalgam should remain available for clinicians to choose in certain clinical circumstances for the restoration of posterior teeth, even in the event of a complete phase-down.

  3. Viscoelastic Behavior of High-Copper Dental Amalgam Alloys,

    DTIC Science & Technology

    1980-07-24

    Apprv.-. . - 17. DISTRIWUTION STATEMENT (of the abstract entered in Block 20, If dliffern Item Roiport) • . y-",.-,D T IC 13. SUPPLEMENTARY NOTES...MAUG 1 3 1980 A * 19. KEY WORDS (Continue on recerse aide if necea2wry and Identify by block number) ? i Amalgam alloys; high-copper amalgam alloys...viscoelastic properties andstress relaxation. C 2 LJJ 20. ABSTRACT (Con"nue on reverse side , f #ncoary and Identify by block numbe) Stress relaxation of

  4. Mercury recovery in situ of four different dental amalgam separators.

    PubMed

    Hylander, Lars D; Lindvall, Anders; Uhrberg, Roland; Gahnberg, Lars; Lindh, Ulf

    2006-07-31

    Amalgam separators are used to physically remove dental amalgam from waste water in dental clinics. They are thereby supposed to reduce mercury (Hg) emissions to the municipal waste water system to acceptable levels. We here present results from a comparative study in situ of three amalgam separators available on the market, all with a claimed efficiency of 99% according to Danish and ISO protocols, and using sedimentation as the principle of separation. We also present corresponding data for an investigational prototype of an improved separator. The obtained efficiency of the three commercial separators is far below what is stated by the manufacturer and by authorities assumed to be the efficiency in clinical conditions. They reduced Hg emissions by 79 - 91%, leaving an average Hg content in outgoing waste water of 1.5 mg L(-1). However, the prototype separator participating in this study retained 99.9% of the waste water Hg emissions, leaving an average Hg content in outgoing waste water of 0.004 mg L(-1). Physical restrictions prohibit sedimentary type separators to recover the Hg fractions causing the largest damages in wastewater treatment plants. This fraction is not considered in the ISO protocol for testing amalgam separators, which therefore needs to be revised. Abolishing the use of dental amalgam and cleaning the tubing systems is the most efficient long-term solution to reduce Hg emissions from dental clinics. Until then, Hg emissions originating from placing, polishing or removing existing amalgam fillings, should be counteracted by the use of low-emission amalgam separators, already on the market or presently being developed for use alone or together with sedimentary type amalgam separators.

  5. Microleakage between endodontic temporary restorative materials placed at different times.

    PubMed

    Pai, S F; Yang, S F; Sue, W L; Chueh, L H; Rivera, E M

    1999-06-01

    Occlusal endodontic access preparations are occasionally made in teeth without removing the original restoration. However, microleakage between restorative materials that are placed at different times has not been extensively studied. Therefore, our objective was to compare microleakage at three areas: between an access opening restorative material and the cavity wall; between an additional material placed later to patch a secondary opening in the first restorative material and the original restorative material itself; and between the secondarily placed material and the cavity wall. Standard endodontic access preparations were made in 120 noncarious, nonrestored crowns of extracted human molars. These teeth were divided into six experimental groups. Another four molars were controls. The endodontic access cavities were restored with either IRM or amalgam as the primary restorative material. After 14 days, half of the primary restorations was removed, and this defect was filled with a secondary restorative material: IRM, Caviton, or a double seal of Caviton and IRM. Microleakage was measured linearly as the extent of basic fuchsin dye penetration under a stereomicroscope after thermal cycling (5 degrees and 55 degrees C for 100 cycles) and tooth sectioning. Wilcoxon signed-rank test was used for statistical analysis. Results indicated significantly less microleakage between primary and secondary restorative materials placed at different times than microleakage between primary temporary restorative materials and the access cavity wall, regardless of the type of primary restorative material used (IRM or amalgam).

  6. Determination of ablation threshold for composite resins and amalgam irradiated with femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Freitas, A. Z.; Freschi, L. R.; Samad, R. E.; Zezell, D. M.; Gouw-Soares, S. C.; Vieira, N. D., Jr.

    2010-03-01

    The use of laser for caries removal and cavity preparation is already a reality in the dental clinic. The objective of the present study was to consider the viability of ultrashort laser pulses for restorative material selective removal, by determining the ablation threshold fluence for composite resins and amalgam irradiated with femtosecond laser pulses. Lasers pulses centered at 830 nm with 50 fs of duration and 1 kHz of repetition rate, with energies in the range of 300 to 770 μJ were used to irradiate the samples. The samples were irradiated using two different geometrical methods for ablation threshold fluence determinations and the volume ablation was measured by optical coherence tomography. The shape of the ablated surfaces were analyzed by optical microscopy and scanning electron microscopy. The determined ablation threshold fluence is 0.35 J/cm2 for the composite resins Z-100 and Z-350, and 0.25 J/cm2 for the amalgam. These values are half of the value for enamel in this temporal regime. Thermal damages were not observed in the samples. Using the OCT technique (optical coherence tomography) was possible to determine the ablated volume and the total mass removed.

  7. Mechanical Properties Comparing Composite Fiber Length to Amalgam

    PubMed Central

    Petersen, Richard C.; Liu, Perng-Ru

    2016-01-01

    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. PMID:27642629

  8. Monte Carlo dose calculation in dental amalgam phantom.

    PubMed

    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.

  9. Amalgam buildups: shear strength and dentin sealing properties.

    PubMed

    Pashley, E L; Comer, R W; Parry, E E; Pashley, D H

    1991-01-01

    The retentive strength and sealing properties of amalgam buildups were compared in vitro in three groups of specimens. All teeth were prepared with flat, nonretentive surfaces. In the first group, the amalgam buildups were retained by four self-threading Minim pins. In the second group, retention was provided by a circumferential slot prepared in the dentin just inside the DEJ. The third group utilized an adhesive resin for retention. Dentin permeability was measured as a hydraulic conductance before and after placement of the amalgam buildups and before and after thermocycling. All methods of retention sealed dentin very well even in the absence of cavity varnish. The 90 degree retentive strength was: pins, 10.3 +/- 0.9 MPa; slots, 4.1 +/- 0.5 MPa; resin, 3.1 +/- 0.8 MPa (mean +/- SEM).

  10. Backscattering from dental restorations and splint materials during therapeutic radiation

    SciTech Connect

    Farman, A.G.; Sharma, S.; George, D.I.; Wilson, D.; Dodd, D.; Figa, R.; Haskell, B.

    1985-08-01

    Models were constructed to simulate as closely as possible the human oral cavity. Radiation absorbed doses were determined for controls and various test situations involving the presence of dental restorative and splint materials during cobalt-60 irradiation of the models. Adjacent gold full crowns and adjacent solid dental silver amalgam cores both increased the dose to the interproximal gingivae by 20%. Use of orthodontic full bands for splinting the jaws increased the dose to the buccal tissues by an average of 10%. Augmentation of dose through backscatter radiation was determined to be only slight for intracoronal amalgam fillings and stainless steel or plastic bracket splints.

  11. Integrated starting and running amalgam assembly for an electrodeless fluorescent lamp

    DOEpatents

    Borowiec, Joseph Christopher; Cocoma, John Paul; Roberts, Victor David

    1998-01-01

    An integrated starting and running amalgam assembly for an electrodeless SEF fluorescent lamp includes a wire mesh amalgam support constructed to jointly optimize positions of a starting amalgam and a running amalgam in the lamp, thereby optimizing mercury vapor pressure in the lamp during both starting and steady-state operation in order to rapidly achieve and maintain high light output. The wire mesh amalgam support is constructed to support the starting amalgam toward one end thereof and the running amalgam toward the other end thereof, and the wire mesh is rolled for friction-fitting within the exhaust tube of the lamp. The positions of the starting and running amalgams on the wire mesh are jointly optimized such that high light output is achieved quickly and maintained, while avoiding any significant reduction in light output between starting and running operation.

  12. A Comparison of US and Japanese Dental Restorative Care Present on Service Members Recovered from the WWII Era.

    PubMed

    Shiroma, Calvin Y

    2017-02-20

    The documentation of dental materials used in the USA during the WWII era is readily available, while references for the Japanese are minimal. It was therefore important to build a photographic database of Japanese restorative care which could be utilized as a comparison tool for the deployed odontologist. The dental restorative care of approximately 400 US and 100 Japanese sets of remains was evaluated. Both countries share many similar restorative techniques to include collared crowns, full-coverage restorations, cantilever bridge/pontics to close spaces; restorative materials such as amalgam, gold, and zinc phosphate (temporary) restorations; and removable prostheses. The dental restorative materials most commonly used by US dentists include the amalgam and silicate cement, while the full-coverage crown was the type of restoration most frequently seen on the Japanese remains. Silicates, porcelain and replaceable crowns, and partial-coverage prepared crowns were not observed on the recovered Japanese remains.

  13. [Antibacterial properties of two conventional and two high copper dental amalgams].

    PubMed

    Günyakti, N; Misirligil, A; Gökay, O

    1989-05-01

    Two conventional and two high copper dental amalgams (Non gamma 2) has been investigated for their antibacterial properties. The high copper dental amalgam, Ana 2000 possessed a very small range of antibacterial propertie against Lac. acidophilus and Staph. epidermidis, while other amalgams found to have no antibacterial activity against the ten tested microorganism strains.

  14. Test of Picture-Text Amalgams in Procedural Texts.

    ERIC Educational Resources Information Center

    Stone, David Edey

    Designed to assess how people read and comprehend information presented in picture-text amalgams in procedural texts, this instrument presents various combinations of text information and illustrative information on slides. Subjects are assigned to one of four conditions and directed to follow the instructions presented on the slides. Videotapes…

  15. Solidification/Stabilization of Elemental Mercury Waste by Amalgamation

    SciTech Connect

    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.

  16. An estimate for the rank of the intersection of subgroups in free amalgamated products of two groups with normal finite amalgamated subgroup

    SciTech Connect

    Zakharov, Alexander O

    2013-02-28

    We generalize the estimate for the rank of intersection of subgroups in free products of groups, proved earlier by Ivanov and Dicks (which is analogous to the Hanna Neumann inequality in free groups) to the case of free amalgamated products of groups with normal finite amalgamated subgroup. We also prove that the estimate obtained is sharp and cannot be further improved when the amalgamated product contains an involution. Bibliography: 11 titles.

  17. A study of high copper amalgams. IV. Formation of eta Cu-Sn (Cu6Sn5) crystals in a high copper dispersant amalgam matrix.

    PubMed

    Okabe, T; Mitchell, R J; Fairhurst, C W

    1979-03-01

    In an HCD amalgam, eta Cu-Sn crystals were found dispersed within gamma1 matrix areas. Previously, eta Cu-Sn phase was thought to form only as part of a reaction zone surrounding Ag-Cu dispersant particles. The eta Cu-Sn crystals found in matrix areas of this HCD amalgam are smaller and more widely scattered than eta Cu-Sn crystals dispersed in the gamma1 matrix of HCSC amalgams.

  18. Surface roughness analysis of four restorative materials exposed to 10% and 15% carbamide peroxide.

    PubMed

    Zavanelli, Adriana Cristina; Mazaro, Vitor Quinelli; Silva, Cristina Ramos; Zavanelli, Ricardo Alexandre; Mancuso, Daniela Nardi

    2011-01-01

    The aim of this study was to evaluate the effects of carbamide peroxide (CP) on surfaces of different restorative materials. Porcelain, composite resin, glass ionomer, and amalgam were analyzed in this study. Surface roughness (Ra) was measured before and after treatment with 10% and 15% CP. Fifteen percent CP increased Ra values in both the glass ionomer and amalgam subgroups, while 10% CP increased Ra values in the glass ionomer subgroup only. Changes in restorative material surfaces can be more severe when bleaching is completed without a clinician's supervision. Hence, thorough patient examinations must be done before, during, and after bleaching treatment.

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

    PubMed

    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 tattoo and amalgam particles dispersed in the epithelial cystic lining. All four mandibular incisors associated with the lesion presented with Weine Type II canal anatomy. The follow-up revealed clinical and radiographic signs of healing.

  20. Influence of dentin substrates to simplify wet-bonding: a leakage-free and reliable tensile strength interface for long-lasting restorations.

    PubMed

    Piemjai, Morakot; Waleepitackdej, Onusa; Nakabayashi, Nobuo

    2011-11-01

    The wet-bonding procedure can be simplified by eliminating the primer. An aqueous mixture of 1% citric acid and 1% ferric chloride (1-1) was hypothesized as providing an easier dehydratable thinner substrate to which 4-META/MMA-TBB resin can adhere reliably. The 1-1 was applied for 10 s and rinsed off with water for 10 s. Demineralized dentin under four conditions was prepared before bonding to PMMA rod using 4-META/MMA-TBB resin: air-dried 10 s (D-NP); air-dried 10 s, primed 60 s with 5% 4-META in acetone (D-P); blotted dry 10 s (W-NP); blotted dry 10 s, primed 60 s (W-P). The tensile strengths (MPa) using mini-dumbbell specimens were 4.0 ± 2.4 for D-NP, 10.6 ± 5.4 for D-P, 38.3 ± 4.4 for W-NP, and 42.9 ± 3.3 for W-P. There was no significant difference between W-NP and W-P with cohesive failure in the dentin and the cured resin. In the wet groups, the hybridized dentin was stable against both HCl and NaOCl challenges. TEM examination and a leakage tests confirmed a perfect seal with a leakage-free interface of W-NP. These results suggest that this primer-less wet-bonding is promising method to protect the underlying intact dentin and pulp, thus providing long-lasting dental treatment.

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

    PubMed

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

    2012-01-01

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

  2. Exploiting the higher specificity of silver amalgamation: selective detection of mercury(II) by forming Ag/Hg amalgam.

    PubMed

    Deng, Li; Ouyang, Xiangyuan; Jin, Jianyu; Ma, Cheng; Jiang, Ying; Zheng, Jing; Li, Jishan; Li, Yinhui; Tan, Weihong; Yang, Ronghua

    2013-09-17

    Heavy metal ion pollution poses severe risks in human health and the environment. Driven by the need to detect trace amounts of mercury, this article demonstrates, for the first time, that silver/mercury amalgamation, combining with DNA-protected silver nanoparticles (AgNPs), can be used for rapid, easy and reliable screening of Hg(2+) ions with high sensitivity and selectivity over competing analytes. In our proposed approach, Hg(2+) detection is achieved by reducing the mercury species to elemental mercury, silver atoms were chosen as the mercury atoms' acceptors by forming Ag/Hg amalgam. To signal fluorescently this silver amalgamation event, a FAM-labeled ssDNA was employed as the signal reporter. AgNPs were grown on the DNA strand that resulted in greatly quenching the FAM fluorescence. Formation of Ag/Hg amalgam suppresses AgNPs growth on the DNA, leading to fluorescence signal increase relative to the fluorescence without Hg(2+) ions, as well as marked by fluorescence quenching. This FAM fluorescence enhancement can be used for detection of Hg(2+) at the a few nanomolar level. Moreover, due to excellent specificity of silver amalgamation with mercury, the sensing system is highly selective for Hg(2+) and does not respond to other metal ions with up to millimolar concentration levels. This sensor is successfully applied to determination of Hg(2+) in tap water, spring water and river water samples. The results shown herein have important implications in the development of new fluorescent sensors for the fast, easy, and selective detection and quantification of Hg(2+) in environmental and biological samples.

  3. A novel clinical approach for long-term retention and durability of resin restorations bonded to multiple developmental defects of enamel

    PubMed Central

    Harika, Rapala; Dutta, Brahmananda; Arun, Parsa; Teja, Raveen P.

    2016-01-01

    Dental enamel is a unique, highly mineralized tissue of ectodermal origin. It is characterized by lack of metabolic activity once formed, implying that disturbances during development can manifest as permanent defects in the erupted tooth. Although the etiology of enamel defects may be attributed to local, systemic, genetic, or environmental factors, most are likely to be multifactorial in nature. The time frame of exposure and the mechanism underpinning the causative factors determine the presentation of these defects. These developmental defects of enamel (DDE) may range from slight abnormalities of the tooth's color to a complete absence of the enamel, some of which may be sensed by an individual as being disfiguring and call for treatment to improve the appearance of the dentition. Molar incisor hypomineralization (MIH) is a relatively common condition that varies in clinical severity, remains localized to permanent incisors and first permanent molars, and whose prevalence varies between 2.8 and 25% depending upon the study. Adhesion and retention of resin restorations is challenging in long-term rehabilitation in these cases. This paper presents a novel approach in the functional and esthetic rehabilitation of a 13-year-old female child diagnosed with multiple DDEs. PMID:28032054

  4. A novel clinical approach for long-term retention and durability of resin restorations bonded to multiple developmental defects of enamel.

    PubMed

    Harika, Rapala; Dutta, Brahmananda; Arun, Parsa; Teja, Raveen P

    2016-01-01

    Dental enamel is a unique, highly mineralized tissue of ectodermal origin. It is characterized by lack of metabolic activity once formed, implying that disturbances during development can manifest as permanent defects in the erupted tooth. Although the etiology of enamel defects may be attributed to local, systemic, genetic, or environmental factors, most are likely to be multifactorial in nature. The time frame of exposure and the mechanism underpinning the causative factors determine the presentation of these defects. These developmental defects of enamel (DDE) may range from slight abnormalities of the tooth's color to a complete absence of the enamel, some of which may be sensed by an individual as being disfiguring and call for treatment to improve the appearance of the dentition. Molar incisor hypomineralization (MIH) is a relatively common condition that varies in clinical severity, remains localized to permanent incisors and first permanent molars, and whose prevalence varies between 2.8 and 25% depending upon the study. Adhesion and retention of resin restorations is challenging in long-term rehabilitation in these cases. This paper presents a novel approach in the functional and esthetic rehabilitation of a 13-year-old female child diagnosed with multiple DDEs.

  5. Measurements of Mercury Released from Amalgams and Sulfide Compounds

    SciTech Connect

    Mattus, C.H.

    1999-04-01

    This report covers work performed during FY 1998 in support of treatment demonstrations conducted for the Mercury Working Group. In order to comply with the requirements of the Resource Conservation and Recovery Act, as implemented by the US Environmental Protection Agency (EPA), the US Department of Energy (DOE) must apply amalgamation, the treatment standard for radioactively contaminated mercury, before disposing of these wastes. The Mercury Working Group under the Mixed Waste Focus Area sponsored a demonstration in which two commercial vendors demonstrated their technologies for the treatment of radioactive mercury from various DOE sites. The project, described in this report, addresses the need for data on the vapor pressure and degradation occurring in amalgamated mercury mixed low-level wastes generated during these demonstrations under a variety of conditions.

  6. A model for amalgamation in group decision making

    NASA Technical Reports Server (NTRS)

    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.

  7. Effect of rubber dam on mercury exposure during amalgam removal.

    PubMed

    Kremers, L; Halbach, S; Willruth, H; Mehl, A; Welzl, G; Wack, F X; Hickel, R; Greim, H

    1999-06-01

    It was the aim of this investigation to treat 20 volunteers with maximally 5 amalgam fillings by the same comprehensive protocol in which all removals with (n = 8) and without (n = 12) rubber dam had been performed within a few months. Nine amalgam-related parameters indicated a close matching of both groups before removal. In the group without rubber dam, mercury (Hg) levels in plasma increased significantly above preremoval values at days 1 and 3 after removal; they decreased significantly below preremoval values at day 30 in the rubber-dam group and at day 100 in both groups. Excretion rates did not increase significantly in either group, but decreased significantly at day 100 in the protected group. Peak plasma-Hg was 0.6 ng/mL on average at day one and decreased with halftimes of 3 and 43 d in subjects protected by rubber dam. The results indicated that concentrations of total mercury in plasma responded rapidly to changes in the amalgam status and reflected the actual absorption most reliably. Notably, plasma-Hg levels were sensitive enough to detect a transient attenuation of the additional exposure by using rubber dam during the removal of only a few fillings. However, being small in magnitude and lasting 100 d at best, the rubber-dam effect had minor toxicological relevance.

  8. A Novel Characterization of Amalgamated Networks in Natural Systems

    PubMed Central

    Barranca, Victor J.; Zhou, Douglas; Cai, David

    2015-01-01

    Densely-connected networks are prominent among natural systems, exhibiting structural characteristics often optimized for biological function. To reveal such features in highly-connected networks, we introduce a new network characterization determined by a decomposition of network-connectivity into low-rank and sparse components. Based on these components, we discover a new class of networks we define as amalgamated networks, which exhibit large functional groups and dense connectivity. Analyzing recent experimental findings on cerebral cortex, food-web, and gene regulatory networks, we establish the unique importance of amalgamated networks in fostering biologically advantageous properties, including rapid communication among nodes, structural stability under attacks, and separation of network activity into distinct functional modules. We further observe that our network characterization is scalable with network size and connectivity, thereby identifying robust features significant to diverse physical systems, which are typically undetectable by conventional characterizations of connectivity. We expect that studying the amalgamation properties of biological networks may offer new insights into understanding their structure-function relationships. PMID:26035066

  9. Costing dental restorations in public sector dental clinics.

    PubMed

    Khairiyah, Abdul Muttalib; Razak, Ishak Abdul; Raja-Latifah, Raja Jalludin; Tan, Bee Siew; Norain, Abu Talib; Noor-Aliyah, Ismail; Natifah, Che Salleh; Rauzi, Ismail

    2009-04-01

    The objective of this study is to share cost analysis methodology and to obtain cost estimates for posterior restorations in public sector dental clinics. Two urban and 2 rural dental clinics in Selangor state were selected. Only cases of 1 posterior restoration per visit by dental officers were included over 6 months. One capsulated amalgam type, 1 capsulated tooth-colored, and 1 non-capsulated tooth-colored material were selected. A clinical pathway form was formulated to collect data per patient. Annual capital and recurrent expenditures were collected per clinic. The mean cost of an amalgam restoration was RM 30.96 (sdRM 7.86); and tooth-colored restorations ranged from RM 33.00 (sdRM 8.43) to RM 41.10 (sdRM 10.61). Wherein 1 USD = RM 2.8. Restoration costs were 35% to 55% higher in clinics in rural areas than in urban areas. The findings demonstrate economy of scale for clinic operation and restoration costs with higher patient load. Costs per restoration were higher in rural than in urban dental clinics. More studies are recommended to address the dearth of dental costs data in Malaysia.

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

    PubMed

    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.

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

    PubMed Central

    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

  12. Effect of dental restorative materials on total antioxidant capacity and calcium concentration of unstimulated saliva

    PubMed Central

    Moghadam, Mona-Momeni; Garcia-Godoy, Franklin; Asatourian, Armen; Aminsobhani, Mohsen; Scarbecz, Mark; Sheibani, Nader

    2017-01-01

    Background To evaluate the effect of dental amalgam and composite restorations on total antioxidant capacity (TAC) and calcium (Ca) ion concentration of unstimulated saliva. Material and Methods Forty-eight children aged 6-10 years selected and divided into three groups of sixteen (8 males, 8 females). In group A and B, samples consisted of two class II dental composite or amalgam restorations, while in group C samples were caries-free (control group). Unstimulated saliva from all samples was collected and TAC was measured by spectrophotometry using an adaptation of 2, 2’-azino-di-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) assay. The Ca ion level was estimated by an auto- analyzer. Data were analyzed with one- and two-way ANOVA test, at a p<.05 level of significance. Results Composite samples showed significantly higher TAC and lower Ca ion levels compared to amalgam and caries-free samples (p<.05). The TAC values showed only significant difference between groups (p<.05), while the Ca ion results showed significant differences within and between groups (p<.05). Conclusions Dental composite restorations increased TAC and decreased Ca ion levels more than amalgam restorations in saliva. Gender is an effective factor in changes induced in oral cavity as females showed more emphatic reaction to dental filling materials than males. Statement of Clinical Relevance Patients who have dental restorations, especially dental composites, should pay more attention to their dental hygiene, because dental restorations can increase oxidative stress and decrease Ca ion level in saliva, which might jeopardize remineralization process of tooth structures after demineralization. Key words:Amalgam, caries, composite, saliva, total antioxidant capacity. PMID:28149467

  13. River restoration

    NASA Astrophysics Data System (ADS)

    Wohl, Ellen; Angermeier, Paul L.; Bledsoe, Brian; Kondolf, G. Mathias; Macdonnell, Larry; Merritt, David M.; Palmer, Margaret A.; Poff, N. Leroy; Tarboton, David

    2005-10-01

    River restoration is at the forefront of applied hydrologic science. However, many river restoration projects are conducted with minimal scientific context. We propose two themes around which a research agenda to advance the scientific basis for river restoration can be built. First, because natural variability is an inherent feature of all river systems, we hypothesize that restoration of process is more likely to succeed than restoration aimed at a fixed end point. Second, because physical, chemical, and biological processes are interconnected in complex ways across watersheds and across timescales, we hypothesize that restoration projects are more likely to be successful in achieving goals if undertaken in the context of entire watersheds. To achieve restoration objectives, the science of river restoration must include (1) an explicit recognition of the known complexities and uncertainties, (2) continued development of a theoretical framework that enables us to identify generalities among river systems and to ask relevant questions, (3) enhancing the science and use of restoration monitoring by measuring the most effective set of variables at the correct scales of measurement, (4) linking science and implementation, and (5) developing methods of restoration that are effective within existing constraints. Key limitations to river restoration include a lack of scientific knowledge of watershed-scale process dynamics, institutional structures that are poorly suited to large-scale adaptive management, and a lack of political support to reestablish delivery of the ecosystem amenities lost through river degradation. This paper outlines an approach for addressing these shortcomings.

  14. [The application of universal adhesives in dental bonding].

    PubMed

    Guo, Jingmei; Lei, Wenlong; Yang, Hongye; Huang, Cui

    2016-03-01

    The bonding restoration has become an important clinical technique for the development of dental bonding technology. Because of its easy operation and the maximum preservation of tooth tissues, bonding repair is widely used in dental restoration. The recent multi-mode universal adhesives have brought new progress in dental bonding restoration. In this article the universal adhesives were reviewed according to its definition, development, improvement, application features and possible problems.

  15. Prenatal Exposure to Dental Amalgam: Evidence from the Seychelles Child Development Main Cohort

    PubMed Central

    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

  16. Effects of magnetic fields from underwater electrical cutting on in vitro corrosion of dental amalgam

    SciTech Connect

    Ortendahl, T.W.; Hoegstedt, P.O.; Odelius, H.; Noren, J.G.

    1988-11-01

    Metallic taste has been reported from divers working with underwater electric welding and cutting. An in vitro model was designed to simulate the intraoral situation of the divers with respect to the magnetic field. Potentiostatic analyses were performed on amalgam samples exposed to AC and DC magnetic fields. Morphologic changes were analyzed using differential interference light microscopy and scanning electron microscopy. Chemical changes on the surface of the amalgam samples were analyzed with secondary ion mass spectrometry. Results demonstrated that dental amalgams exposed to a specific AC magnetic field underwent morphologic and chemical changes in the superficial amalgam layers.

  17. Effects of magnetic fields from underwater electrical cutting on in vitro corrosion of dental amalgam.

    PubMed

    Ortendahl, T W; Högstedt, P; Odelius, H; Norén, J G

    1988-11-01

    Metallic taste has been reported from divers working with underwater electric welding and cutting. An in vitro model was designed to simulate the intraoral situation of the divers with respect to the magnetic field. Potentiostatic analyses were performed on amalgam samples exposed to AC and DC magnetic fields. Morphologic changes were analyzed using differential interference light microscopy and scanning electron microscopy. Chemical changes on the surface of the amalgam samples were analyzed with secondary ion mass spectrometry. Results demonstrated that dental amalgams exposed to a specific AC magnetic field underwent morphologic and chemical changes in the superficial amalgam layers.

  18. Restoring primary anterior teeth.

    PubMed

    Waggoner, William F

    2002-01-01

    A variety of esthetic restorative materials are available for restoring primary incisors. Knowledge of the specific strengths, weakness, and properties of each material will enhance the clinician's ability to make the best choice of selection for each individual situation. Intracoronal restorations of primary teeth may utilize resin composites, glass ionomer cements, resin-modified ionomers, or polyacid-modified resins. Each has distinct advantages and disadvantages and the clinical conditions of placement may be a strong determining factor as to which material is utilized. Full coronal restoration of primary incisors may be indicated for a number of reasons. Crowns available for restoration of primary incisors include those that are directly bonded onto the tooth, which generally are a resin material, and those crowns that are luted onto the tooth and are some type of stainless steel crown. However, due to lack of supporting clinical data, none of the crowns can be said to be superior to the others under all circumstances. Though caries in the mandibular region is rare, restorative solutions for mandibular incisors are needed. Neither stainless steel crowns nor celluloid crown forms are made specifically for mandibular incisors. Many options exist to repair carious primary incisors, but there is insufficient controlled, clinical data to suggest that one type of restoration is superior to another. This does not discount the fact that dentists have been using many of these crowns for years with much success. Operator preferences, esthetic demands by parents, the child's behavior, and moisture and hemorrhage control are all variables which affect the decision and ultimate outcome of whatever restorative treatment is chosen.

  19. The decision to repair or replace a defective restoration is affected by who placed the original restoration: findings from the National Dental PBRN

    PubMed Central

    Gordan, Valeria V; Riley, Joseph; Geraldeli, Saulo; Williams, O. Dale; Spoto, Joseph C; Gilbert, Gregg H

    2014-01-01

    Objectives To evaluate how restoration characteristics are associated with the decision to repair or replace an existing restoration. The following hypotheses were studied: Dentists who placed the original restoration are more likely to repair instead of replace restorations (H1) that are in molar teeth; (H2) that are in the upper arch; (H3) that have amalgam restorative material; (H4) if a fracture is not the primary reason for the defect; and (H5) when the restoration comprises more than one surface. Methods This cross-sectional study used a consecutive patient/restoration recruitment design. 194 dentists members of a dental practice-based research network recorded data on restorations in permanent teeth that needed repair or replacement. Results For 6,623 of the 8,770 defective restorations in 6,643 patients, the treatment was provided by the dentist who had not placed the original restoration (75%). The 2-way interaction revealed that dentists who had placed the original restoration often chose to repair when the defective restoration was in a molar, relative to premolar or anterior teeth (OR = 2.2, p < .001); and chose to replace when the restoration had amalgam (OR = 0.5, p < .001), and when it was a fracture compared to another reason (OR = 0.8, p = 001). Conclusion Most dentists are not conservative when they revisit a restoration that they originally placed regardless of type of failure, number of surfaces or material used. However, dentists who had placed the original restoration were significantly more likely to repair it when the defective restoration was in a molar tooth. PMID:25223822

  20. Handling characteristics of a palladium-free gallium-based alloy compared with a high copper dental amalgam in a simulated clinical trial.

    PubMed

    Shaini, F J; Shortall, A C; Ellakwa, A E; Marquis, P M

    2001-11-01

    The aim of the current study was to compare the handling characteristics of a palladium-free gallium-based alloys (Galloy) with those of a high-copper amalgam (Permite C). The study had a particular interest in the evaluation of the direct placement delivery system used with both alloys. Ten dentists participated in the current study. Each placed two amalgam and two gallium-based alloy restorations in conventional class II cavities prepared in acrylic typodont teeth. None of the participating dentists had used the direct placement delivery system or had any previous experience with gallium-based alloy and no practice was allowed beforehand. The restorations were evaluated according to the following criteria: ease of loading the cavity (delivery system), ease of condensation, capacity to produce and sustain contact area, ease of carving, resistance to damage during removal of the matrix band, overall quality of the restoration and the available working time. Each criterion was given a score on a scale of 1-5 (1: very poor, 2: poor, 3: fair, 4: good, 5: very good). The results showed no statistically significant difference in the evaluated criteria between the two alloys (P > 0.05) except for criterion number 2 (ease of condensation, P=0.0005).

  1. Bent Bonds and Multiple Bonds.

    ERIC Educational Resources Information Center

    Robinson, Edward A.; Gillespie, Ronald J.

    1980-01-01

    Considers carbon-carbon multiple bonds in terms of Pauling's bent bond model, which allows direct calculation of double and triple bonds from the length of a CC single bond. Lengths of these multiple bonds are estimated from direct measurements on "bent-bond" models constructed of plastic tubing and standard kits. (CS)

  2. In situ surface biodegradation of restorative materials.

    PubMed

    Padovani, Gc; Fúcio, Sbp; Ambrosano, Gmb; Sinhoreti, Mac; Puppin-Rontani, Rm

    2014-01-01

    SUMMARY This study aimed to evaluate the surface characteristics of restorative materials (roughness, hardness, chemical changes by energy-dispersive spectroscopy [EDX], and scanning electron microscopy [SEM]) submitted to in situ biodegradation. Fifteen discs of each material (IPS e.max [EM], Filtek Supreme [FS], Vitremer [VI], Ketac Molar Easymix [KM], and Amalgam GS-80 [AM]) were fabricated in a metallic mold (4.0 mm × 1.5 mm). Roughness, hardness, SEM, and EDX were then evaluated. Fifteen healthy volunteers used a palatal device containing one disc of each restorative material for seven days. After the biodegradation, the roughness, hardness, SEM, and EDX were once again evaluated. Data obtained from the roughness and hardness evaluations were submitted to Kolmogorov-Smirnov and Tukey-Kramer tests (p<0.05). All esthetic restorative materials showed a significant increase in the roughness after biodegradation. Before biodegradation, significant differences in the hardness among the materials were seen: EM>AM>FS>KM>VI. After biodegradation, the hardness was significantly altered among the materials studied: EM>AM>FS=KM>VI, along with a significant increase in the hardness for AM, KM, and VI. SEM images indicated degradation on the surface of all materials, showing porosities, cracks, and roughness. Furthermore, after biodegradation, FS showed the presence of Cl, K, and Ca on the surface, while F was not present on the VI and KM surfaces. EM and AM did not have alterations in their chemical composition after biodegradation. It was concluded that the dental biofilm accumulation in situ on different restorative materials is a material-dependent parameter. Overall, all materials changed after biodegradation: esthetic restorative materials showed increased roughness, confirmed by SEM, and the ionomer materials and silver amalgam showed a significantly higher hardness. Finally, the initial chemical composition of the composite resin and ionomer materials evaluated was

  3. Rondeau Seminars amalgamated mid-sagittal (lateral) cephalometric analysis.

    PubMed

    Palencar, Adrian J

    2014-01-01

    The author presents a comprehensive International Association for Orthodontics--Rondeau Seminars Amalgamated Mid-sagittal (Lateral) Cephalometric Analysis. Norms on the Cephalometric Data Sheet are age and gender specific for the Caucasian population and the postings are color coded for visual attraction. If the patient is ofa different ethnic group, the Norms should be adjusted accordingly. This Cephalometric Analysis is comprised often Sections, in alphabetical order and twenty nine Factors. The author expanded Rondeau Seminars Cephalometric Analysis by only six Factors, thus fulfilling the requirement for the case presentation for the Fellow of the IAO and the Diplomate ofthe IBO.

  4. Sensibility of Teeth Having Based versus Non-Based Amalgam Restorations: A Clinical Study.

    DTIC Science & Technology

    1983-04-01

    623-37, Oct. 1971. 101. Guevara, M., and McClugage, S. The effects of intrusive forces upon the microvasculature of the dental pulp . Angle Orthodont ...widespread. Certainly, pulp protection was not unknown. Harrower (3), in 1886, stated that a protective layer of varnish was used under gold fillings as...8217 " :- .. ".....-.... .... . .-. .- ........-.... ~-.. .........-... . . . . . 4 textbook "A System of Dental Surgery", wrote that pulp capping could be done by means of covering the deep

  5. Magnetic field effects on dental amalgam in divers welding and cutting electrically underwater

    SciTech Connect

    Ortendahl, T.W.; Hoegstedt, P.

    1988-11-01

    Divers have for some years been complaining about a metallic taste in the mouth while electrically welding and cutting underwater. This paper reports on results from an assessment of this problem. It was hypothesized that the magnetic fields arising from the welding or cutting current could correlate with the reported symptoms. The intraoral magnetic flux density was calculated to 1.15 mT, at 650 ADC, in a normal cutting situation. This was verified in vivo. This magnetic field was shown to contain an AC component that is a candidate for inducing secondary currents in the oral tissues and restorative materials. Five submerged divers exposed to a magnetic field of 0.35 mT did not report any metallic taste. Magnetophosphenes were reported by 1 diver. (Magnetophosphenes are luminous impressions due to excitement of the retina by a magnetic field in addition to or in place of impingement of light rays.) Only a slight shielding effect to magnetic fields was observed due to a copper-brass helmet. An in vitro model for exposure of dental amalgams to magnetic fields was designed. Recommendations for decreasing the magnetic field surrounding the diver in practical work is given.

  6. Magnetic field effects on dental amalgam in divers welding and cutting electrically underwater.

    PubMed

    Ortendahl, T W; Högstedt, P

    1988-11-01

    Divers have for some years been complaining about a metallic taste in the mouth while electrically welding and cutting underwater. This paper reports on results from an assessment of this problem. It was hypothesized that the magnetic fields arising from the welding or cutting current could correlate with the reported symptoms. The intraoral magnetic flux density was calculated to 1.15 mT, at 650 ADC, in a normal cutting situation. This was verified in vivo. This magnetic field was shown to contain an AC component that is a candidate for inducing secondary currents in the oral tissues and restorative materials. Five submerged divers exposed to a magnetic field of 0.35 mT did not report any metallic taste. Magnetophosphenes were reported by 1 diver. (Magnetophosphenes are luminous impressions due to excitement of the retina by a magnetic field in addition to or in place of impingement of light rays.) Only a slight shielding effect to magnetic fields was observed due to a copper-brass helmet. An in vitro model for exposure of dental amalgams to magnetic fields was designed. Recommendations for decreasing the magnetic field surrounding the diver in practical work is given.

  7. [Black or white--is amalgam 'out'? Part 1. Amalgam or composite: which of these 2 materials is the most deleterious?].

    PubMed

    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.

  8. EDS and μ-XRF mapping of amalgam degradation products in ancient mirrors.

    PubMed

    Arizio, E; Orsega, E F; Falcone, R; Vallotto, M

    2014-12-01

    An amalgam mirror is a mirror type, used from the fifteenth century until the end of the nineteenth century, where the reflective layer is constituted by a tin amalgam layer adhered to a glass sheet. In this work, two amalgam mirrors samples were studied by scanning electron microscopy with an energy dispersive spectrometer and by micro-X-ray fluorescence elemental mapping to go deeply into the understanding of the degradation mechanism of the amalgam layer of ancient mirrors. The investigation has been focused for the first time on the reflective surface of the amalgam layer adherent to the glass sheet to better understand the processes of amalgam corrosion. The two amalgam degradation compounds, romarchite and cassiterite, has been spatially differentiated by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) maps. SEM images and micro-X-ray fluorescence and EDS maps showed that the amalgam degradation products grow up to form hemispherical stratified calottes. This structure is probably due to a mechanism involves cyclic phases and oxygen radial diffusion from a superficial oxidation nucleus.

  9. Tin amalgam mirrors: investigation by XRF, SEM-EDS, XRD and EPMA-WDS mapping

    NASA Astrophysics Data System (ADS)

    Arizio, E.; Orsega, E. F.; Sommariva, G.; Falcone, R.

    2013-06-01

    Ancient mirrors were constituted by a tin-mercury amalgam layer superimposed to a glass sheet. This was the only one method used until the nineteenth century, when the wet silvering process was invented. The tin amalgam is a binary alloy of tin and mercury constituted by two different phases: a mercury-rich liquid phase and a tin-rich solid phase. The amalgam alteration produces mercury loss and a general growth of the solid crystalline phase. In addition, tin dioxide and monoxide are formed with a consequent decrease of the amalgam adhesion to the glass. These degradation phenomena led to reduction or disappearance of the mirror reflective power. The aim of this study was the characterization of the amalgam layers of eight mirror samples dating during the seventeenth and nineteenth centuries. The samples were analyzed by X-ray diffraction and by a Scanning Electron Microscope with an Energy Dispersive Spectrometer (SEM-EDS), and for the first time on this type of alloy by X-ray Fluorescence and EPMA-WDS (Electron Probe Micro Analysis with Wavelength Dispersive Spectrometry) elemental mapping. The contents of tin, mercury, and some trace elements in the amalgam layers have been determined. The investigation of the superficial patterns of the amalgam by SEM, EPMA-WDS mapping, and SEM-EDS allowed a first understanding of some morphologies and processes of the degradation of the amalgam layer.

  10. Factors affecting the placement or replacement of direct restorations in a dental school

    PubMed Central

    Silvani, Samara; Trivelato, Roberta Ferreira; Nogueira, Ruchele Dias; Gonçalves, Luciano de Souza; Geraldo-Martins, Vinícius Rangel

    2014-01-01

    Context: The knowledge of the reasons for the placement of direct restorations makes possible to trace an epidemiological profile of a specific population and to direct the teaching of dentistry to techniques that are commonly used today and will be continued performed in the future. Purpose: The aim of this study was to verify the reasons for placement and replacement of direct restorations in patients treated in the Dental Clinic of the Uberaba University – Brazil. Materials and Methods: This study evaluated 306 restorative procedures carried out on 60 patients. During the treatment planning, a form that contained information about the patient's gender, tooth number, the classification of restorations, the reasons for placement and replacement of amalgam and tooth-colored restorations, the material that had to be removed and the new material used to fill the cavities was filled for each patient. Statistical analysis was carried out using Chi-square test (α = 0.05). Results: The data showed that most of the patients were female (66.7%). Of all the restorations placed, 60.45% were 1st-time placements, while 39.55% were replacements. For 1st-time restorations, the main reason for placement was primary caries (76.76%), followed by non-carious cervical lesions (15.14%). The amalgam restorations were replaced more frequently (67.77%). The primary reason for replacements was the presence of secondary caries (for both previous amalgam (42.68%) and composite (66.67%) restorations (P < 0.05). The resin composite was the most indicated material for the new restorations (98.04%) (P < 0.05). Conclusions: The main reason for placement of direct restorations was primary caries, while secondary caries was the main reason for replacements. In almost all cases, the material used to fill the cavities was the resin composite. PMID:24808696

  11. Speciation of mercury excreted in feces from individuals with amalgam fillings.

    PubMed

    Engqvist, A; Colmsjö, A; Skare, I

    1998-01-01

    Investigators established methods for the analysis of total mercury (Hg-total), oxidized mercury and mercury bound to sulfhydryl groups (Hg-S), mercury vapor (Hg0), and mercury from amalgam particles (APs) in fecal samples. Two individuals consumed mercury as a mercury-cysteine complex mercury vapor, and mercury from amalgam particles, and the cumulative excretion of mercury in feces was followed. Investigators found that 80% of the mercury from amalgam particles and mercury bound to sulfhydryl groups was excreted, but only 40% of the mercury vapor was excreted. Speciation of mercury excreted in feces from 6 individuals with a moderate loading of amalgam fillings showed that most of the mercury originating from the fillings consisted of oxidized mercury, which was probably bound to sulfhydryl-containing compounds. The proportion of amalgam particles in fecal samples from these individuals was low, and it did not exceed 26% of the total amount of mercury excreted.

  12. Galvanic corrosion and cytotoxic effects of amalgam and gallium alloys coupled to titanium.

    PubMed

    Bumgardner, J D; Johansson, B I

    1996-06-01

    The aim of this study was to examine and compare the galvanic corrosion of a conventional, a dispersed high-copper, and a palladium-enriched spherical high-copper amalgam and a gallium alloy coupled to titanium in saline and cell culture solutions, and to evaluate the effects of the couples on cultured cells. The potentials and charge transfers between amalgams and titanium were measured by electrochemical corrosion methods. Cytotoxicity of the couples, as indicated by the uptake of neutral red vital stain, was determined in 24-h direct contact human gingival fibroblast cell cultures. Results of this study indicated that before connecting the high-copper amalgams to titanium, the amalgams exhibited more positive potentials which resulted in initial negative charge transfers, i.e. corrosion of titanium. However, this initial corrosion appeared to cause titanium to passivate, and a shift in galvanic currents to positive charge transfers, i.e. corrosion of the amalgam samples. Lower galvanic currents were measured for the amalgam-titanium couples as compared to the gallium alloy-titanium couple. Coupling the conventional or the palladium-enriched high-copper amalgams to titanium did not significantly affect the uptake of neutral red as compared to cells not exposed to any test alloy. However, significant cytotoxic effects were observed when the dispersed-type high-copper amalgam and the gallium alloy were coupled to titanium. Even though the corrosion currents measured for these couples were less than gold alloys coupled to amalgam, these results suggest there is the potential for released galvanic corrosion products to become cytotoxic. These data warrant further investigations into the effects of coupling amalgam and gallium alloys to titanium in the oral environment.

  13. Three-body wear of a hand-consolidated silver alternative to amalgam.

    PubMed

    Xu, H H; Eichmiller, F C; Giuseppetti, A A; Ives, L K; Parry, E E; Schumacher, G E

    1999-09-01

    Recent studies have investigated a mercury-free silver alternative to amalgam, but the silver powders required a relatively high compaction pressure to consolidate. The aim of the present study was to consolidate a precipitated silver powder into a cohesive solid using an air-driven pneumatic condenser fitted with an amalgam plugger at a clinically realistic load, and to study the mechanisms and rates of three-body wear of the consolidated silver in comparison with that of an amalgam. The silver powder was annealed, rinsed with a dilute acid, and consolidated either in a prepared tooth cavity or in a specimen mold at a load of 15 N. A four-station wear machine was used where each specimen was immersed in a slurry containing polymethyl methacrylate beads, then a steel pin was loaded and rotated against the specimen at a maximum load of 76 N. The flexural strength in MPa (mean +/- SD; n = 10) was 86 +/- 20 for amalgam, 181 +/- 45 for silver with a polished surface, and 202 +/- 21 for silver with a burnished surface. After 4 x 10(5) wear cycles, the wear scar depth in microm was 134 +/- 54 for amalgam, 143 +/- 8 for polished silver, and 131 +/- 9 for burnished silver, which were not significantly different (Tukey's multiple comparison test; family confidence coefficient = 0.95). SEM examination revealed cracks and fracture pits in the worn surface of amalgam, in contrast to a smooth surface in silver. Wear and material removal in amalgam occurred by microfracture and dislodgement of cracked segments, while wear in the silver occurred by ductile deformation and flow of materials. To conclude, the consolidated silver possesses a three-body wear resistance similar to that of amalgam, and a higher resistance to wear-induced damage and cracking than amalgam. The mechanism of wear in amalgam is microfracture and material dislodgement, while that in consolidated silver is ductile deformation and flow of material.

  14. [Restoration of canine guidance using bonded prostheses].

    PubMed

    Maroto García, J; Maroto García, F

    1989-11-01

    The aim of this paper is to offer an easy, accurate and aesthetical solution to the problem of the loss, by wastage, of anterior guides in those patients who show facets in initial stages of bruxism (central of peripheral). Using the acid-etch non-precious metals(Cr-Ni-Be) technique we make a metalic plaque covering the posterior face of the upper canines, on which we place a porcelain incisal rim. All of this is fixed with a composed material.

  15. Smooth surface glass ionomer restoration for primary teeth.

    PubMed

    Killian, C M; Croll, T P

    1991-01-01

    Glass ionomer restorative cement offers the clinician an alternative to bonded composite resin for restoration of certain lesions in primary teeth. This article details a step-by-step procedure for restoration of a smooth surface carious lesion in a primary incisor using an encapsulated glass ionomer restorative material and reviews advantages and limitations of the cement. A light-hardened glass ionomer liner/base that has proven useful as an enamel and dentin restorative is also described.

  16. The effect of occlusal forces on restorations.

    PubMed

    Larson, Thomas D

    2014-09-01

    This review will focus on the effect occlusal forces, both normal masticatory force and paranormal bruxing and clenching force, have on various restorative materials and their interaction with the teeth through a variety of bonding mechanisms. Salient physical properties of each of the materials will be reviewed, as well as the effect occlusal force has on restoration durability.

  17. Biomarkers of kidney integrity in children and adolescents with dental amalgam mercury exposure: Findings from the Casa Pia children's amalgam trial

    SciTech Connect

    Woods, James S. Martin, Michael D.; Leroux, Brian G.; DeRouen, Timothy A.; Bernardo, Mario F.; Luis, Henrique S.; Leitao, Jorge G.; Kushleika, John V.; Rue, Tessa C.; Korpak, Anna M.

    2008-11-15

    Mercury is toxic to the kidney, and dental amalgam is a source of mercury exposure. Few studies have evaluated the effects of dental amalgam on kidney function in a longitudinal context in children. Here, we evaluated urinary concentrations of glutathione S-transferases (GSTs) {alpha} and {pi} as biomarkers of renal proximal and distal tubular integrity, respectively, and albumin as a biomarker of glomerular integrity in children and adolescents 8-18 years of age over a 7-year course of dental amalgam treatment. Five hundred seven children, 8-12 years of age at baseline, participated in a clinical trial to evaluate the neurobehavioral and renal effects of dental amalgam in children. Subjects were randomized to either dental amalgam or resin composite treatments. Urinary GSTs {alpha} and {pi}, albumin, and creatinine concentrations were measured at baseline and annually in all subjects. Results were evaluated using linear regression analysis. GST-{alpha} concentrations were similar between treatment groups and in each sex and race (white vs. non-white) group in each follow-up year. GST-{pi} levels tended upward over the course of follow-up by four- to six-fold. This increase was seen in all groups irrespective of the treatment, race, or gender. Females had GST-{pi} levels approximately twice those of males at all ages. Albumin concentrations were constant throughout the follow-up period and did not differ by treatment, although females had 39% higher albumin levels than males. Additionally, we found no significant effects of amalgam treatment on the proportion of children with microalbuminuria (>30 mg/g creatinine). These findings are relevant within the context of children's health risk assessment as relates to the safety of mercury exposure from dental amalgam on kidney function. These data also provide normative values for sensitive indices of renal functional integrity that may serve in the evaluation of children and adolescents with renal disorders.

  18. Gap measurement and bond strength of five selected adhesive systems bonded to tooth structure.

    PubMed

    Arbabzadeh, F; Gage, J P; Young, W G; Shahabi, S; Swenson, S M

    1998-06-01

    The ability of a restorative material to bond and seal the interface with tooth structure is perhaps the most significant factor in determining resistance to marginal caries. Thus, the quality and durability of marginal seal and bond strength are major considerations in the selection of restorative materials. The purpose of this study was to compare the bond strength and marginal discrepancies of five adhesive systems: All-Bond 2, Clearfil Liner Bond, KB 200, ProBond and AELITE Bond. Twenty-five buccal and 25 lingual cavities were prepared in 25 caries-free extracted molar teeth, giving 10 cavities for each of the 5 adhesive systems. All teeth were restored with the resin composite Pertac Hybrid, or PRISMA Total Performance Hybrid with their appropriate adhesive systems. After restoration, the teeth were thermocycled, were stained with a 1.5% aqueous solution of a procion dye (reactive orange 14) and sectioned coronally with a saw microtome. Three sections of 200 microns thickness were prepared from each restoration which were then examined microscopically to measure marginal gap widths using a confocal tandem microscope. Shear bond strength measurements were carried out on the dentine bond using a universal testing machine. The All-Bond 2 adhesive system was found to have higher shear bond strength and to have the least gap width at the cementodentinal margin.

  19. Clinical survey on type of restoration in deciduous teeth.

    PubMed

    Fukuyama, Tatsuro; Oda, Shinya; Yamashita, Haruto; Sekiguchi, Hiroshi; Yakushiji, Masashi

    2008-02-01

    This study was conducted in 533 children with 1,634 treated teeth who visited the Pediatric Dentistry Department at the Chiba Hospital of Tokyo Dental College between January and December, 2003. Restorations on deciduous tooth were categorized by age of patient and tooth type. The following observations were made: Children aged 4 (17.9%) visited the clinic most frequently and this group had the highest number of deciduous restorations (21.3%). Among the 1,634 deciduous teeth restored, metal inlays were provided in 29.4% of total teeth restored, composite resin restorations in 27.2%, stainless-steel crowns in 25.7%, composite resin full crowns in 7.7%, glass-ionomer cement restorations in 6.6%, and amalgam restorations in 3.4%. By age, composite resin was most frequently used in children aged 1 to 3. In children aged 5 to 9, metal inlay was most frequently used. Those aged 4 received mostly stainless-steel crowns. Composite resin restorations were used mostly in anterior deciduous teeth, and metal inlays mostly in deciduous molars. Previous research indicated an increasing trend towards composite resin restorations and composite resin full crowns. The present study also confirmed such a trend. While the use of metal inlays and stainless-steel crowns tended to increase until 1987, the present study indicated a trend to decrease.

  20. Comparison of microleakage from stainless steel crowns margins used with different restorative materials: An in vitro study

    PubMed Central

    Memarpour, Mahtab; Derafshi, Reza; Razavi, Mahshid

    2016-01-01

    Background: Obtaining optimal marginal adaption with prefabricated stainless steel crowns (SSCs) is difficult, especially after removing dental caries or defects in cervical areas. This situation requires the use of an SSC after tooth reconstruction. This study evaluated microleakage and material loss with five restorative materials at SSC margins. Materials and Methods: One hundred and twenty primary molar teeth were randomly divided into six groups (n = 20). Class V cavities were prepared on the buccal surfaces of the teeth in groups 1-5. Cavities were restored with amalgam, resin-based composite, glass ionomer (GI), zinc phosphate, or reinforced zinc oxide eugenol (Zonalin). Group 6 without cavity preparation was used as a control. Restorations with SSCs were prepared according to standard methods. Then, SSCs were fitted so that the crown margins overlaid the restorative materials and cemented with GI. After thermocycling, the specimens were placed in 0.5% fuchsin and sectioned. The proportions of mircoleakage and material loss were evaluated with a digital microscope. Statistical analysis was performed with Kruskal–Wallis and Mann–Whitney tests. Results: The groups differed significantly (P < 0.001). Amalgam and GI showed the least microleakage. Amalgam restorations had significantly less microleakage than the other materials (P < 0.05). Microleakage was greatest with resin-based composite, followed by Zonalin. Material loss was greater in samples restored with Zonalin and zinc phosphate. Conclusion: When SSC margins overlaid the restoration materials, cavity restoration with amalgam or GI before SSC placement led to less microleakage and material loss. Regarding microleakage and material loss, resin-based composite, zinc phosphate, and Zonalin were not suitable options. PMID:26962309

  1. Discrimination of tooth layers and dental restorative materials using cutting sounds.

    PubMed

    Zakeri, Vahid; Arzanpour, Siamak; Chehroudi, Babak

    2015-03-01

    Dental restoration begins with removing carries and affected tissues with air-turbine rotary cutting handpieces, and later restoring the lost tissues with appropriate restorative materials to retain the functionality. Most restoration materials eventually fail as they age and need to be replaced. One of the difficulties in replacing failing restorations is discerning the boundary of restorative materials, which causes inadvertent removal of healthy tooth layers. Developing an objective and sensor-based method is a promising approach to monitor dental restorative operations and to prevent excessive tooth losses. This paper has analyzed cutting sounds of an air-turbine handpiece to discriminate between tooth layers and two commonly used restorative materials, amalgam and composite. Support vector machines were employed for classification, and the averaged short-time Fourier transform coefficients were selected as the features. The classifier performance was evaluated from different aspects such as the number of features, feature scaling methods, classification schemes, and utilized kernels. The total classification accuracies were 89% and 92% for cases included composite and amalgam materials, respectively. The obtained results indicated the feasibility and effectiveness of the proposed method.

  2. Dependence of kinetic variables in the short-term release of Hg2+, Cu2+ and Zn2+ ions into synthetic saliva from an high-copper dental amalgam.

    PubMed

    Campus, Guglielmo; Garcia-Godoy, Franklin; Gaspa, Leonardo; Panzanelli, Angelo; Piu, Paola C; Micera, Giovanni; Lugliè, Pierfranca; Sanna, Gavino

    2007-08-01

    The short term (up to 14 days after restoration) release of selected ions (i.e., Hg(2+), Cu(2+) and Zn(2+)) from Dispersalloy into artificial saliva has been evaluated in regards to the nature of the saliva (Fusayama and McCarty and Shklar's solutions), the amount of amalgam, the time of contact and the periodical renewal (every 48 h interval) of artificial saliva. The evaluation of the ionic fraction of such metals has been accomplished by using anodic stripping methods (i.e., Differential Pulse Anodic Stripping Voltammetry, DPASV) with a 7 microm graphite disk microelectrode as a working electrode. Data obtained in this work are almost unprecedented in the literature due the fact that such analytical method exclude metals in non-ionic forms (e.g., metals or organometallic compounds). The high concentrations measured in every experimental condition confirm the concern for the short-term release of metals from amalgam into saliva.

  3. High Tensile Strength Amalgams for In-Space Repair and Fabrication

    NASA Technical Reports Server (NTRS)

    Grugel, R. N.

    2005-01-01

    Amalgams are defined as an alloy of mercury with one or more other metals. These, along with those based on gallium (also liquid at near room temperature), are widely used in dental practice as a tooth filling material. Amalgams have a number of useful attributes that indude room temperature compounding. corrosion resistance, dimensional stability, and good compressive strength. These properties well serve dental needs but, unfortunately, amalgams have extremely poor tensile strength, a feature that severely limits their applications. The work presented here demonstrates how, by modifying particle geometry, the tensile strength of amalgams can be increased and thus extending the range of potential applications. This is relevant to, for example, the freeform fabrication of replacement parts that might be necessary during an extended space mission. Advantages, i.e. Figures-of-Merit. include the ability to produce complex parts, minimum crew interaction, high yield - minimum wasted material, reduced gravity compatibility, minimum final finishing, safety, and minimum power consumption.

  4. New science challenges old notion that mercury dental amalgam is safe.

    PubMed

    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.

  5. High Tensile Strength Amalgams for In-Space Fabrication and Repair

    NASA Technical Reports Server (NTRS)

    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.

  6. DETERMINATION OF TOTAL MERCURY IN FISH TISSUES USING PYROLYSIS ATOMIC ABSORPTION SPECTROMETRY WITH GOLD AMALGAMATION

    EPA Science Inventory

    A simple and rapid procedure for measuring total mercury in fish tissues is evaluated and
    compared with conventional techniques. Using an automated instrument incorporating combustion, preconcentration by amalgamation with gold, and atomic absorption spectrometry (AAS), mill...

  7. Field evaluation of mercury vapor analytical methods: comparison of the "double amalgam method" and ISO 17733.

    PubMed

    Takaya, Mitsutoshi; Joeng, Jee Yeon; Ishihara, Nobuo; Serita, Fumio; Kohyama, Norihiko

    2006-04-01

    In this study, a gold amalgam method called the "Double amalgam method" was compared with the ISO 17733 method for mercury vapor analysis method. In terms of sensitivity and ease of operation, the amalgamation method is superior to the oxidation method. Two parallel samplings were carried out in this research at a button battery factory, where the mercury vapor level in the air was about 0.001 mg/m3 and at a fluorescent lamp factory, where the mercury vapor level was about 0.015 mg/m3. In the both cases, the measured values of the two showed good agreement with each other. As these two workplaces represent typical mercury levels in industries today, the double amalgam method is applicable to working environment measurement.

  8. Evaluation of corrosion degradation of amalgams by immersion and fracture test.

    PubMed

    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.

  9. Macroinvertebrate community assembly in pools created during peatland restoration.

    PubMed

    Brown, Lee E; Ramchunder, Sorain J; Beadle, Jeannie M; Holden, Joseph

    2016-11-01

    Many degraded ecosystems are subject to restoration attempts, providing new opportunities to unravel the processes of ecological community assembly. Restoration of previously drained northern peatlands, primarily to promote peat and carbon accumulation, has created hundreds of thousands of new open water pools. We assessed the potential benefits of this wetland restoration for aquatic biodiversity, and how communities reassemble, by comparing pool ecosystems in regions of the UK Pennines on intact (never drained) versus restored (blocked drainage-ditches) peatland. We also evaluated the conceptual idea that comparing reference ecosystems in terms of their compositional similarity to null assemblages (and thus the relative importance of stochastic versus deterministic assembly) can guide evaluations of restoration success better than analyses of community composition or diversity. Community composition data highlighted some differences in the macroinvertebrate composition of restored pools compared to undisturbed peatland pools, which could be used to suggest that alternative end-points to restoration were influenced by stochastic processes. However, widely used diversity metrics indicated no differences between undisturbed and restored pools. Novel evaluations of restoration using null models confirmed the similarity of deterministic assembly processes from the national species pool across all pools. Stochastic elements were important drivers of between-pool differences at the regional-scale but the scale of these effects was also similar across most of the pools studied. The amalgamation of assembly theory into ecosystem restoration monitoring allows us to conclude with more certainty that restoration has been successful from an ecological perspective in these systems. Evaluation of these UK findings compared to those from peatlands across Europe and North America further suggests that restoring peatland pools delivers significant benefits for aquatic fauna by

  10. Natural restoration

    SciTech Connect

    Kamlet, K.S.

    1993-02-01

    After a company pays millions of dollars to clean up contaminated site, its liability may not be over. It may have to spend tens of millions more to restore damaged natural resources under an oft-overlooked Superfund program. Examples of liability are cited in this report from the Exxon Valdez oil spill and a pcb leak which contaminated a harbor.

  11. Sticker Bonding.

    ERIC Educational Resources Information Center

    Frazier, Laura Corbin

    2000-01-01

    Introduces a science activity on the bonding of chemical compounds. Assigns students the role of either a cation or anion and asks them to write the ions they may bond with. Assesses students' understanding of charge, bonding, and other concepts. (YDS)

  12. Adjunctive role of dental restorations in personal identification of burnt victims

    PubMed Central

    Vandrangi, Sameer Kumar; Radhika, MB; Paremala, K; Reshma, V; Sudhakara, M; Hosthor, Sreelatha S

    2016-01-01

    Background: Fire remains one of the major causes of morbidity and mortality throughout the world and identification of a body from the fatal fire remains a daunting task. Several forensic cases involve interpretation of burnt human bodies from airline and automobile accidents, bombings and unlawful cremation. Fire is also involved in homicides, suicides, accidental death, arson and in attempts to destroy forensic evidence in criminal cases. Soft tissue destruction from fire can be so extensive that conventional methods of identification may be impossible. However, teeth survive even high temperatures due to their resistant composition and so, obviously, the restorative material housed in the teeth are even more secure and can yield valuable information in personal identification. Aim: To assess the usefulness of most common restorations in personal identification in burnt cases. Materials and Methods: The study was conducted on 40 extracted teeth which were divided into four groups (Group 1 - Unrestored teeth, Group 2 - Amalgam restored, Group 3 - Glass ionomer restored and Group 4 - Composite resin restored teeth. The effect of incineration at 200°C, 400°C, 600°C, 800°C, 1000°C for 15 min at each target temperature followed by subsequent cooling was studied. Results: Amalgam restoration was resistant and intact even at 1000°C, whereas GIC and composite restoration are identifiable till 600°C, the residual cavity preparation leaves a clue for narrowing down the spectrum of identification. PMID:27194881

  13. Salivary levels of mutans streptococci associated with restorations: a case-control study.

    PubMed

    Petti, S; Campus, G; Lumbau, A; Tarsitani, G

    2001-07-01

    Our aim was to estimate whether restorative therapy with amalgam and composite resin could decrease salivary mutans streptococcal level, thus also decreasing the risk for other caries development. We selected a case group of 93 children with detectable salivary mutans levels (i.e., at least 1x10(4) cfu/ml), and a control group (n=93 subjects) with undetectable levels. Children had the same age (12 years), no extracted teeth, crowns, temporary fillings, and restorations other than amalgam and composite resin, and the two groups had similar gender distribution. We clinically examined children and recorded active caries, restorations and oral hygiene level by means of gingival bleeding on probing; we also investigated sucrose intake at breakfast. The case group had statistically significant higher prevalence of restorations (36.6% vs. 18.3%), active caries (44.1% vs. 12.9%), and bad oral hygiene (84.9% vs. 68.8%) than the control group. However, the logistic regression analysis showed that presence of active caries was the only significant variable associated with mutans streptococci (OR=4.0; p=0.0002), while the effects of sucrose intake and of restorations were marginally significant. This apparent contrast between statistical analyses was due to the concomitant presence, in children with detectable mutans streptococci level, of restorations and decayed teeth at the same time, and, on the basis of the multivariate analysis, presence of mutans streptococci in these children was explained by the presence of active caries, more than restorations.

  14. Various Effects of Sandblasting of Dental Restorative Materials

    PubMed Central

    Nishigawa, Goro; Maruo, Yukinori; Irie, Masao; Maeda, Naoto; Yoshihara, Kumiko; Nagaoka, Noriyuki; Matsumoto, Takuya; Minagi, Shogo

    2016-01-01

    Background Sandblasting particles which remain on the surfaces of dental restorations are removed prior to cementation. It is probable that adhesive strength between luting material and sandblasting particle remnants might exceed that with restorative material. If that being the case, blasting particles adhere to sandblasted material surface could be instrumental to increasing adhesive strength like underlying bonding mechanism between luting material and silanized particles of tribochemical silica coating-treated surface. We hypothesize that ultrasonic cleaning of bonding surfaces, which were pretreated with sandblasting, may affect adhesive strength of a resin luting material to dental restorative materials. Methods We therefore observed adhesive strength of resin luting material to aluminum oxide was greater than those to zirconia ceramic and cobalt-chromium alloy beforehand. To measure the shear bond strengths of resin luting material to zirconia ceramic and cobalt-chromium alloy, forty specimens of each restorative material were prepared. Bonding surfaces were polished with silicon abrasive paper and then treated with sandblasting. For each restorative material, 40 sandblasted specimens were equally divided into two groups: ultrasonic cleaning (USC) group and non-ultrasonic cleaning (NUSC) group. After resin luting material was polymerized on bonding surface, shear test was performed to evaluate effect of ultrasonic cleaning of bonding surfaces pretreated with sandblasting on bond strength. Results For both zirconia ceramic and cobalt-chromium alloy, NUSC group showed significantly higher shear bond strength than USC group. Conclusions Ultrasonic cleaning of dental restorations after sandblasting should be avoided to retain improved bonding between these materials. PMID:26764913

  15. Restoration Process

    NASA Technical Reports Server (NTRS)

    1979-01-01

    In the accompanying photos, a laboratory technician is restoring the once-obliterated serial number of a revolver. The four-photo sequence shows the gradual progression from total invisibility to clear readability. The technician is using a new process developed in an applications engineering project conducted by NASA's Lewis Research Center in conjunction with Chicago State University. Serial numbers and other markings are frequently eliminated from metal objects to prevent tracing ownership of guns, motor vehicles, bicycles, cameras, appliances and jewelry. To restore obliterated numbers, crime laboratory investigators most often employ a chemical etching technique. It is effective, but it may cause metal corrosion and it requires extensive preparatory grinding and polishing. The NASA-Chicago State process is advantageous because it can be applied without variation to any kind of metal, it needs no preparatory work and number recovery can be accomplished without corrosive chemicals; the liquid used is water.

  16. Gradual surface degradation of restorative materials by acidic agents.

    PubMed

    Hengtrakool, Chanothai; Kukiattrakoon, Boonlert; Kedjarune-Leggat, Ureporn

    2011-01-01

    The aim of this study was to investigate the effect of acidic agents on surface roughness and characteristics of four restorative materials. Fifty-two discs were created from each restorative material: metal-reinforced glass ionomer cement (Ketac-S), resin-modified glass ionomer cement (Fuji II LC), resin composite (Filtek Z250), and amalgam (Valiant-PhD); each disc was 12 mm in diameter and 2.5 mm thick. The specimens were divided into four subgroups (n=13) and immersed for 168 hours in four storage media: deionized water (control); citrate buffer solution; green mango juice; and pineapple juice. Surface roughness measurements were performed with a profilometer, both before and after storage media immersion. Surface characteristics were examined using scanning electron microscopy (SEM). Statistical significance among each group was analyzed using two-way repeated ANOVA and Tukey's tests. Ketac-S demonstrated the highest roughness changes after immersion in acidic agents (p<0.05), followed by Fuji II LC. Valiant-PhD and Filtek Z250 illustrated some minor changes over 168 hours. The mango juice produced the greatest degradation effect of all materials tested (p<0.05). SEM photographs demonstrated gradual surface changes of all materials tested after immersions. Of the materials evaluated, amalgam and resin composite may be the most suitable for restorations for patients with tooth surface loss.

  17. Morphology and electrochemical behavior of Ag-Cu nanoparticle-doped amalgams.

    PubMed

    Chung, Kwok-Hung; Hsiao, Li-Yin; Lin, Yu-Sheng; Duh, Jenq-Gong

    2008-05-01

    The aim of this study was to introduce Ag-Cu phase nanopowder as an additive to improve the corrosion behavior of dental amalgams. A novel Ag-Cu nanopowder was synthesized by the precipitation method. An amalgam alloy powder (World-Cap) was added and mixed with 5 wt.% and 10 wt.% of Ag-Cu nanopowders, respectively, to form experimental amalgam alloy powders. The original alloy powder was used as a control. Alloy powders were examined using X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy and electron probe microanalysis. Amalgam disk specimens of metallurgically prepared were tested in 0.9% NaCl solution using electrochemical methods. The changes in the corrosion potential and anodic polarization characteristics were determined. Corrosion potential data were analyzed statistically (n=3, analysis of variance, Tukey's test, p<0.05). The diameters of lamellar structure Ag-Cu nanoparticles were measured to be approximately 30 nm. The composition of the Ag-Cu nanoparticles determined by TEM-energy-dispersive spectroscopy was 56.28 at.% Ag-43.72 at.% Cu. A light-shaded phase was found mixing with dark Cu-Sn reaction particles in the reaction zones of Ag-Cu nanoparticle-doped amalgams. The Ag-Cu nanoparticle-doped amalgams exhibited zero current potentials more positive than the control (p<0.05) and no current peak was observed at -325mV that related to Ag-Hg phase and Cu6Sn5 phase in anodic polarization curves. The results indicated that the corrosion resistance of high-copper single-composition amalgam could be improved by Ag-Cu nanoparticle-doping.

  18. Is dental amalgam safe for humans? The opinion of the scientific committee of the European Commission

    PubMed Central

    2011-01-01

    It was claimed by the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR)) in a report to the EU-Commission that "....no risks of adverse systemic effects exist and the current use of dental amalgam does not pose a risk of systemic disease..." [1, available from: http://ec.europa.eu/health/ph_risk/committees/04_scenihr/docs/scenihr_o_016.pdf]. SCENIHR disregarded the toxicology of mercury and did not include most important scientific studies in their review. But the real scientific data show that: (a) Dental amalgam is by far the main source of human total mercury body burden. This is proven by autopsy studies which found 2-12 times more mercury in body tissues of individuals with dental amalgam. Autopsy studies are the most valuable and most important studies for examining the amalgam-caused mercury body burden. (b) These autopsy studies have shown consistently that many individuals with amalgam have toxic levels of mercury in their brains or kidneys. (c) There is no correlation between mercury levels in blood or urine, and the levels in body tissues or the severity of clinical symptoms. SCENIHR only relied on levels in urine or blood. (d) The half-life of mercury in the brain can last from several years to decades, thus mercury accumulates over time of amalgam exposure in body tissues to toxic levels. However, SCENIHR state that the half-life of mercury in the body is only "20-90 days". (e) Mercury vapor is about ten times more toxic than lead on human neurons and with synergistic toxicity to other metals. (f) Most studies cited by SCENIHR which conclude that amalgam fillings are safe have severe methodical flaws. PMID:21232090

  19. Study of the short-term release of the ionic fraction of heavy metals from dental amalgam into synthetic saliva, using anodic stripping voltammetry with microelectrodes.

    PubMed

    Sanna, Gavino; Pilo, Maria I; Piu, Paola C; Spano, Nadia; Tapparo, Andrea; Campus, Guglielmo G; Seeber, Renato

    2002-11-12

    The present paper describes a fast and reproducible procedure, employing differential pulse stripping analysis technique with graphite microelectrodes, for the quantitative evaluation of the ionic fraction of heavy metals (namely Hg, Cu, and Zn) released from dental amalgams into synthetic saliva during 6-90 h contact between amalgam and saliva, after completion of the dental restoration (short-term release). The Zn(2+) concentration was evaluated by linear calibration, whereas Cu(2+) and Hg(2+) contents were estimated by the standard additions method. While the concentration of Zn(2+) ion does not increase significantly anymore after a 6-h contact (values from 288+/-12 to 346+/-12 mugdm(-3) at time of contact from 6 to 90 h, respectively), in the same time interval the concentration of both Cu(2+) and Hg(2+) ions progressively increases (from 38+/-6 to 197+/-4 mugdm(-3) and from 15+/-3 to 101+/-2 mugdm(-3), respectively). The results of the release tests reveal that Hg concentration is at the highest level of risk (HBM III), as identified by the three human biomonitoring categories suggested by the Institut für Wasser-, Boden- und Lufthygiene des Umweltbundesamtes (Germany) for the estimation of potential harmful effects on health due to exposure to heavy metals.

  20. Joint amalgamation of most parsimonious reconciled gene trees

    PubMed Central

    Scornavacca, Celine; Jacox, Edwin; Szöllősi, Gergely J.

    2015-01-01

    Motivation: Traditionally, gene phylogenies have been reconstructed solely on the basis of molecular sequences; this, however, often does not provide enough information to distinguish between statistically equivalent relationships. To address this problem, several recent methods have incorporated information on the species phylogeny in gene tree reconstruction, leading to dramatic improvements in accuracy. Although probabilistic methods are able to estimate all model parameters but are computationally expensive, parsimony methods—generally computationally more efficient—require a prior estimate of parameters and of the statistical support. Results: Here, we present the Tree Estimation using Reconciliation (TERA) algorithm, a parsimony based, species tree aware method for gene tree reconstruction based on a scoring scheme combining duplication, transfer and loss costs with an estimate of the sequence likelihood. TERA explores all reconciled gene trees that can be amalgamated from a sample of gene trees. Using a large scale simulated dataset, we demonstrate that TERA achieves the same accuracy as the corresponding probabilistic method while being faster, and outperforms other parsimony-based methods in both accuracy and speed. Running TERA on a set of 1099 homologous gene families from complete cyanobacterial genomes, we find that incorporating knowledge of the species tree results in a two thirds reduction in the number of apparent transfer events. Availability and implementation: The algorithm is implemented in our program TERA, which is freely available from http://mbb.univ-montp2.fr/MBB/download_sources/16__TERA. Contact: celine.scornavacca@univ-montp2.fr, ssolo@angel.elte.hu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:25380957

  1. Bonded composite resin crowns for primary incisors: technique update.

    PubMed

    Croll, T P

    1990-02-01

    A technique for restoration of carious primary maxillary incisors with a hybrid visible light-curing composite resin and a dentinal bonding agent is described. Careful use of this technique and the new materials can provide a restoration that is esthetic and resistant to fracture and displacement. The technique requires careful preparation of the operative field and precise handling of the restorative materials. The method is illustrated by the placement of bonded composite resin crowns in a 3-year-old boy.

  2. A comparison of tissue reactions to Ketac-Fil and amalgam.

    PubMed

    DeGrood, M E; Oguntebi, B R; Cunningham, C J; Pink, R

    1995-02-01

    The objective of this study was to compare the bone tissue reactions of Ketac-Fil to the most commonly used retrograde filling material, amalgam, in a rat model. Forty-eight Harlan rats were divided into three groups: amalgam, Ketac-Fil, and controls. Following anesthesia, the right lower incisor was extracted from each animal. A 3-mm long x 1-mm diameter polyethylene tube filled with amalgam or Ketac-Fil was implanted in the extraction site. The animals were killed at 14, 42, and 90 days; and the mandibles were dissected en block and processed histologically. The inflammatory reaction was assessed by the number of plasma cells, lymphocytes, polymorphonuclear neutrophils, giant cells, and osteoclasts within 100 microns of the implant. Bone formation was determined as either present or absent in the same area. There was no statistically significant bone apposition within 100 microns of the Ketac material, and there was a statistically significant increase in inflammation in the amalgam group. This study indicates that both Ketac-Fil and amalgam are relatively biocompatible, and provides support for clinical usage tests of Ketac-Fil as a retrograde filling material.

  3. Endodontic complications in teeth with vital pulps restored with composite resins: a systematic review.

    PubMed

    Dawson, V S; Amjad, S; Fransson, H

    2015-07-01

    Composite resin is used extensively for restoration of teeth with vital pulps. Although cell culture studies have disclosed harmful effects on pulpal cells, any untoward clinical effects, manifest as adverse pulpal responses, have yet to be determined. This study comprises a systematic review, designed to address the question of whether the risk of endodontic complications is greater with composite resin restorations than with other restorative materials, such as amalgam. The study methodology involved (i) formulation of the research question, (ii) construction and conduct of an extensive literature search with (iii) interpretation and assessment of the retrieved literature. A search of the medical database PubMed was complemented with a search of the Controlled Trials Register (CENTRAL). The initial search yielded 1043 publications, the abstracts of which were read independently by the authors. After additional searches, 10 studies were included in the review. In all the included studies, the level of evidence was assessed as low. No conclusions could therefore be drawn. The included studies reported few, if any, endodontic complications. Little or no differences emerged between teeth restored with composite resins and those restored with amalgam. To determine whether composite resin restorations of teeth with vital pulps are associated with an increased risk for development of endodontic complications such as apical periodontitis, further evidence is needed, from well-constructed studies with a large number of participants.

  4. Taguchi optimization: Case study of gold recovery from amalgamation tailing by using froth flotation method

    NASA Astrophysics Data System (ADS)

    Sudibyo, Aji, B. B.; Sumardi, S.; Mufakir, F. R.; Junaidi, A.; Nurjaman, F.; Karna, Aziza, Aulia

    2017-01-01

    Gold amalgamation process was widely used to treat gold ore. This process produces the tailing or amalgamation solid waste, which still contains gold at 8-9 ppm. Froth flotation is one of the promising methods to beneficiate gold from this tailing. However, this process requires optimal conditions which depends on the type of raw material. In this study, Taguchi method was used to optimize the optimum conditions of the froth flotation process. The Taguchi optimization shows that the gold recovery was strongly influenced by the particle size which is the best particle size at 150 mesh followed by the Potassium amyl xanthate concentration, pH and pine oil concentration at 1133.98, 4535.92 and 68.04 gr/ton amalgamation tailing, respectively.

  5. [Phase transition analysis of ancient bronze mirror surface tin amalgam in heating].

    PubMed

    Zhang, Shao-yun; Qin, Ying

    2010-10-01

    Taking advantage of theta-theta scanning (vertical goniometer) sealed and ceramic X-ray tube full-automatic diffractometer, which can be heated and detected at the same time when the temperature is between normal temperature and 1200 degrees C, and X-ray fluorescence, and combining surface feature with character, high tin bronze mirror which had been daubed "tin amalgam" was detected and analyzed. It can prove that phase with Hg will disappear gradually when the sample is heated to the temperature higher than the boiling point of Hg; It indicates that bronze surface cannot be as a proof of "tin amalgam" used whether it contains Hg, moreover, it is not necessary that bronze mirror is covered with "tin amalgam" in terms of application.

  6. Benchmarking parameter-free AMaLGaM on functions with and without noise.

    PubMed

    Bosman, Peter A N; Grahl, Jörn; Thierens, Dirk

    2013-01-01

    We describe a parameter-free estimation-of-distribution algorithm (EDA) called the adapted maximum-likelihood Gaussian model iterated density-estimation evolutionary algorithm (AMaLGaM-ID[Formula: see text]A, or AMaLGaM for short) for numerical optimization. AMaLGaM is benchmarked within the 2009 black box optimization benchmarking (BBOB) framework and compared to a variant with incremental model building (iAMaLGaM). We study the implications of factorizing the covariance matrix in the Gaussian distribution, to use only a few or no covariances. Further, AMaLGaM and iAMaLGaM are also evaluated on the noisy BBOB problems and we assess how well multiple evaluations per solution can average out noise. Experimental evidence suggests that parameter-free AMaLGaM can solve a wide range of problems efficiently with perceived polynomial scalability, including multimodal problems, obtaining the best or near-best results among all algorithms tested in 2009 on functions such as the step-ellipsoid and Katsuuras, but failing to locate the optimum within the time limit on skew Rastrigin-Bueche separable and Lunacek bi-Rastrigin in higher dimensions. AMaLGaM is found to be more robust to noise than iAMaLGaM due to the larger required population size. Using few or no covariances hinders the EDA from dealing with rotations of the search space. Finally, the use of noise averaging is found to be less efficient than the direct application of the EDA unless the noise is uniformly distributed. AMaLGaM was among the best performing algorithms submitted to the BBOB workshop in 2009.

  7. Current status of zirconia restoration.

    PubMed

    Miyazaki, Takashi; Nakamura, Takashi; Matsumura, Hideo; Ban, Seiji; Kobayashi, Taira

    2013-10-01

    During the past decade, zirconia-based ceramics have been successfully introduced into the clinic to fabricate fixed dental prostheses (FDPs), along with a dental computer-aided/computer-aided manufacturing (CAD/CAM) system. In this article (1) development of dental ceramics, (2) the current status of dental CAD/CAM systems, (3) CAD/CAM and zirconia restoration, (4) bond between zirconia and veneering ceramics, (5) bond of zirconia with resin-based luting agents, (6) surface finish of zirconia restoration and antagonist enamel wear, and (7) clinical evaluation of zirconia restoration are reviewed. Yttria partially stabilized tetragonal zirconia polycrystalline (Y-TZP) showed better mechanical properties and superior resistance to fracture than other conventional dental ceramics. Furthermore, ceria-stabilized tetragonal zirconia polycrystalline and alumina nanocomposites (Ce-TZP/A) had the highest fracture toughness and had resistance to low-temperature aging degradation. Both zirconia-based ceramics have been clinically available as an alternative to the metal framework for fixed dental prostheses (FDPs). Marginal adaptation of zirconia-based FDPs is acceptable for clinical application. The most frequent clinical complication with zirconia-based FDPs was chipping of the veneering porcelain that was affected by many factors. The mechanism for the bonding between zirconia and veneering ceramics remains unknown. There was no clear evidence of chemical bonding and the bond strength between zirconia and porcelain was lower than that between metal and porcelain. There were two alternatives proposed that might avoid chipping of veneering porcelains. One was hybrid-structured FDPs comprising CAD/CAM-fabricated porcelain parts adhering to a CAD/CAM fabricated zirconia framework. Another option was full-contour zirconia FDPs using high translucent zirconia. Combined application of silica coating and/or silane coupler, and 10-methacryloyloxydecyl dihydrogen phosphate is

  8. Influence of thermal treatments on Ag Sn Cu powders in order to reduce mercury contents in dental amalgam.

    PubMed

    Bracho-Troconis, C; Colon, P; Bartout, J D; Bienvenu, Y

    2000-01-01

    The mercury content of dental amalgams is a controversial subject with regard to the biological properties of these materials. The object of this study is to optimize the thermal treatments performed on an experimental powder in order to obtain a low mercury ratio (41% by weight) while preserving the desirable clinical qualities of the material. Using atomized powder, two types of thermal treatments are performed: A1, to obtain a partially annealed structure and A2, to obtain a complete homogenization. The kinetics of the amalgamation reaction is mainly evaluated by X-ray diffraction to identify the newly formed phases as a function of setting time. Mechanical properties are evaluated according to the ISO norms at 37 degrees C. Metallographical examination of the amalgams shows a Ag-Hg phase which acts as a matrix incorporating the Cu-Sn and Ag-Sn compounds. The setting kinetics of the A1 amalgams is linear and slightly more rapid than that of the A2 amalgam. The mechanical properties of the amalgams are significantly improved regarding the higher mercury content commercial amalgams. A specific thermal treatment permits us to slow down the diffusion of mercury between the different intermetallic compounds into the powder. The final amalgam composition, thus, most approaches the stoechiometric ratio calculated from a quaternary diagram.

  9. Artifacts resembling budding bacteria produced in placer-gold amalgams by nitric acid leaching

    USGS Publications Warehouse

    Watterson, J.R.

    1994-01-01

    Microscopic filiform morphologies in gold which are indistinguishable from forms originally interpreted as bacterial in origin were produced in the laboratory by treating amalgams made from natural and artificial gold with hot nitric acid. Textures ranging from cobblestone to deeply crenulated to nodular filiform were produced in the laboratory from all tested natural and artificial gold amalgams; analogous textures widespread in Alaskan placer gold may have a similar inorganic origin. These results indicate that morphology alone cannot be considered adequate evidence of microbial involvement in gold formation. -Author

  10. Artifacts resembling budding bacteria produced in placer-gold amalgams by nitric acid leaching

    USGS Publications Warehouse

    Watterson, J.R.

    1994-01-01

    Microscopic filiform morphologies in gold which are indistinguishable from forms originally interpreted as bacterial in origin were produced in the laboratory by treating amalgams made from natural and artificial gold with hot nitric acid. Textures ranging from cobblestone to deeply crenulated to nodular filiform were produced in the laboratory from all tested natural and artificial gold amalgams; analogous textures widespread in Alaskan placer gold may have a similar inorganic origin. These results indicate that morphology alone cannot be considered adequate evidence of microbial involvement in gold formation.

  11. [Currently Recommended Restorative Materials in Modern Conservative Dentistry].

    PubMed

    Kobierska-Brzoza, Joanna Monika; Dobrzyński, Maciej; Fita, Katarzyna Agnieszka; Bader-Orłowska, Dorota; Szymonowicz, Maria

    2015-01-01

    Conservative treatment which restores the function, aesthetics and protects remaining tooth structure, and what is the most important, the viability of the tooth pulp, is still needed. Dental fillings replace specialized tissues of the tooth that have been lost due to caries or injury. Any decision concerning the use of a particular restorative material should be individualized and based on the competence regarding the composition, properties and characteristics of the specific restorative material. This requires continuous updating of knowledge about available dental materials as well as education of patients who, according to actual models of dental care, should be active partners in the therapeutic process. The selection of restorative materials is often related to financial abilities of the patients, and more generally to the economic model of organized health care in a particular country. Nowadays, amalgam is increasingly dislodged by adhesive materials which permit to save more tooth structure and allow to preserve natural teeth for a longer time. In the nearest future we can expect further development of minimally invasive techniques and improvements of restorative materials, especially their mechanical properties like strength and wear resistance as well as biocompatibility. The article presents restorative materials used in modern dentistry.

  12. Evaluation of Shear Bond Strength of Newer Bonding Systems on Superficial and Deep Dentin

    PubMed Central

    Kumari, R Veena; Siddaraju, Kishore; Nagaraj, Hema; Poluri, Ramya Krishna

    2015-01-01

    Background: The purpose of this study was to compare the shear bond strength of nanocomposite resin to superficial dentin and deep dentin using two different dentin bonding systems. Materials and Methods: All teeth were sectioned at various levels (superficial dentin: Dentin within 0.5-1 mm of dentinoenamel junction; deep dentin: Dentin within 0.5 mm of the highest pulp horn) using a Carborundum Disc and embedded in acrylic block of specific size. Selected specimens (60 premolar teeth) were grouped randomly into three groups, the groups were differentiated into superficial dentin, deep dentin, and control group which were further divided into sub Group A and Subgroup B containing 10 teeth each, depending on the bonding agents used. In Subgroup A, Tetric N Bond, and in Subgroup B Single Bond Universal were used. In the control group no bonding agent was used. The specimens were thermocycled for 500 cycles between 5°C and 55°C water bath for 40 s. Finally, the specimens were subjected to shear bond strength study under INSTRON machine (Universal Testing Machine). The maximum shear bond strengths were noted at the time of fracture (de-bonding) of the restorative material. Results were analyzed using ANOVA test, Bonferroni test, and paired t-test. Results: Bond strength values of fifth generation bonding system (Tetric N Bond) showed higher mean shear bond strength compared to seventh generation bonding system (Single Bond Universal). There was a significant fall in bond strength values as one reaches deeper levels of dentin from superficial to deep dentin. Conclusion: There was a significant difference between the bond strength of fifth generation bonding system (Tetric N Bond) and seventh generation bonding system (Single Bond Universal). Decrease in the bond strength values is seen for the deeper level of dentin as compared to superficial dentin. PMID:26435613

  13. Cytotoxicity of dental composite (co)monomers and the amalgam component Hg(2+) in human gingival fibroblasts.

    PubMed

    Reichl, Franz-Xaver; Simon, Sabine; Esters, Magalie; Seiss, Mario; Kehe, Kai; Kleinsasser, Norbert; Hickel, Reinhard

    2006-08-01

    Unpolymerized resin (co)monomers or mercury (Hg) can be released from restorative dental materials (e.g. composites and amalgam). They can diffuse into the tooth pulp or the gingiva. They can also reach the gingiva and organs by the circulating blood after the uptake from swallowed saliva. The cytotoxicity of dental composite components hydroxyethylmethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), urethanedimethacrylate (UDMA), and bisglycidylmethacrylate (Bis-GMA) as well as the amalgam component Hg(2+) (as HgCl(2)) and methyl mercury chloride (MeHgCl) was investigated on human gingival fibroblasts (HGFs) at two time intervals. To test the cytotoxicity of substances, the bromodeoxyuridine (BrdU) assay and the lactate dehydrogenase (LDH) assay were used. The test substances were added in various concentrations and cells were incubated for 24 or 48 h. The EC(50) values were obtained as half-maximum-effect concentrations from fitted curves. Following EC(50) values were found [BrdU: mean (mmol/l); SEM in parentheses; n=12]: (24 h/48 h) HEMA 8.860 (0.440)/6.600(0.630), TEGDMA 1.810(0.130)/1.220(0.130), UDMA 0.120(0.010)/0.140(0.010), BisGMA 0.060(0.004)/0.040(0.002), HgCl(2) 0.015(0.001)/0.050(0.006), and MeHgCl 0.004(0.001)/0.005(0.001). Following EC(50) values were found [LDH: mean (mmol/l); SEM in parentheses; n=12]: (24 h/48 h) HEMA 9.490(0.300)/7.890(1.230), TEGDMA 2.300(0.470)/1.950(0.310), UDMA 0.200(0.007)/0.100(0.007), BisGMA 0.070(0.005)/0.100(0.002), and MeHgCl 0.014(0.006)/0.010(0.003). In both assays, the following range of increased toxicity was found for composite components (24 and 48 h): HEMA < TEGDMA < UDMA < BisGMA. In both assays, MeHgCl was the most toxic substance. In the BrdU assay, Hg(2+) was about fourfold less toxic than MeHgCl but Hg(2+) was about fourfold more toxic than BisGMA. In the BrdU test, a significantly (P<0.05) decreased toxicity was observed for Hg(2+) at 48 h, compared to the 24 h Hg(2+)-exposure. A time depending

  14. Evaluation of efficacy of restorative dental treatment provided under general anesthesia at hospitalized pediatric dental patients of Isfahan

    PubMed Central

    Eshghi, Alireza; Samani, Mahdi Jafarzadeh; Najafi, Naghme Feyzi; Hajiahmadi, Maryam

    2012-01-01

    Background: General anesthesia (GA) allows dental treatment to be rendered under optimal conditions, theoretically ensuring ideal outcomes. The aim of this study was to determine the efficacy of restorative dental procedures performed under GA. Materials and Methods: In this cross-sectional retrospective study, 305 pediatric patients who had been treated under GA 6 to 24 months before our survey at Isfahan's hospitalized dentistry center were examined. The examination was performed on dental chair with oral mirror and dental probe. The results were recorded in a special form for each patient for statistical analysis and evaluation of restorations to be successful or failed. Statistical analysis was performed by chi-square and fisher exact tests for comparison between success rates of restorations and Kendall's tau-b test for evaluating the effect of time on success rates of them (P < 0.05). Results: Stainless steel crown restorations had significantly better results vs class I and class II amalgam and class I and class II tooth color restorations. All types of posterior tooth color restorations had statistically same results with amalgam restorations. Anterior composite resin build-up represented significantly low success rates. The failure rates of stainless steel crown and anterior composite resin build-up restorations did not correlate with the time of follow-up (P = 0.344 and P = 0.091, respectively). Conclusion: Stainless steel crown restorations had significantly better results vs other posterior restorations. The failure rates of stainless steel crown and anterior composite resin build-up restorations did not correlate with the time of follow-up in comparison of other restorations. PMID:23162592

  15. Current Teaching of Proximal Retention Grooves for Class II Amalgam Preparations.

    ERIC Educational Resources Information Center

    Moore, David L.

    1992-01-01

    A survey gathered information on methods of class II amalgam preparation taught in 59 dental schools. Focus was on the teaching and testing of proximal retention groove use, stated rationale for placing retention grooves, and the relationship of the instruction to board criteria for cavity preparation. (MSE)

  16. Colorimetric Signal Amplification Assay for Mercury Ions Based on the Catalysis of Gold Amalgam.

    PubMed

    Chen, Zhengbo; Zhang, Chenmeng; Gao, Qinggang; Wang, Guo; Tan, Lulu; Liao, Qing

    2015-11-03

    Mercury is a major threat to the environment and to human health. It is highly desirable to develop a user-friendly kit for on-site mercury detection. Such a method must be able to detect mercury below the threshold levels (10 nM) for drinking water defined by the U.S. Environmental Protection Agency. Herein, we for the first time reported catalytically active gold amalgam-based reaction between 4-nitrophenol and NaBH4 with colorimetric sensing function. We take advantage of the correlation between the catalytic properties and the surface area of gold amalgam, which is proportional to the amount of the gold nanoparticle (AuNP)-bound Hg(2+). As the concentration of Hg(2+) increases until the saturation of Hg onto the AuNPs, the catalytic performance of the gold amalgam is much stronger due to the formation of gold amalgam and the increase of the nanoparticle surface area, leading to the decrease of the reduction time of 4-nitrophenol for the color change. This sensing system exhibits excellent selectivity and ultrahigh sensitivity up to the 1.45 nM detection limit. The practical use of this system for Hg(2+) determination in tap water samples is also demonstrated successfully.

  17. Real-Time Plasmonic Monitoring of Single Gold Amalgam Nanoalloy Electrochemical Formation and Stripping.

    PubMed

    Wang, Jun-Gang; Fossey, John S; Li, Meng; Xie, Tao; Long, Yi-Tao

    2016-03-01

    Direct electrodeposition of mercury onto gold nanorods on an ITO substrate, without reducing agents, is reported. The growth of single gold amalgam nanoalloy particles and subsequent stripping was monitored in real-time monitoring by plasmonic effects and single-nanoparticle dark-field spectroelectrochemistry techniques. Time-dependent scattering spectral information conferred insight into the growth and stripping mechanism of a single nanoalloy particle. Four critical stages were observed: First, rapid deposition of Hg atoms onto Au nanorods; second, slow diffusion of Hg atoms into Au nanorods; third, prompt stripping of Hg atoms from Au nanorods; fourth, moderate diffusion from the inner core of Au nanorods. Under high Hg(2+) concentrations, homogeneous spherical gold amalgam nanoalloys were obtained. These results demonstrate that the morphology and composition of individual gold amalgam nanoalloys can be precisely regulated electrochemically. Moreover, gold amalgam nanoalloys with intriguing optical properties, such as modulated plasmonic lifetimes and quality factor Q, could be obtained. This may offer opportunities to extend applications in photovoltaic energy conversion and chemical sensing.

  18. Saturated vapor pressure above the amalgam of alkali metals in discharge lamps

    NASA Astrophysics Data System (ADS)

    Gavrish, S. V.

    2011-12-01

    A theoretical and numerical analysis of the evaporation process of two-component compounds in vapors of alkali metals in discharge lamps is presented. Based on the developed mathematical model of calculation of saturated vapor pressure of the metal above the amalgam, dependences of mass fractions of the components in the discharge volume on design parameters and thermophysical characteristics of the lamp are obtained.

  19. Teaching as an Amalgam of Discourses and the Consequent Need for Appropriate Modes of Reflection.

    ERIC Educational Resources Information Center

    Coldron, John; Smith, Robin

    This paper explores the concept of reflection and reflective practice in teacher education. Teaching is a complex achievement that brings together a number of conceptual, practical, and physical resources in an individual's professional practice. Achievement in teaching is an amalgam of at least four different discourses--science, craft, art, and…

  20. Electrolytic method for the production of lithium using a lithium-amalgam electrode

    DOEpatents

    Cooper, John F.; Krikorian, Oscar H.; Homsy, Robert V.

    1979-01-01

    A method for recovering lithium from its molten amalgam by electrolysis of the amalgam in an electrolytic cell containing as a molten electrolyte a fused-salt consisting essentially of a mixture of two or more alkali metal halides, preferably alkali metal halides selected from lithium iodide, lithium chloride, potassium iodide and potassium chloride. A particularly suitable molten electrolyte is a fused-salt consisting essentially of a mixture of at least three components obtained by modifying an eutectic mixture of LiI-KI by the addition of a minor amount of one or more alkali metal halides. The lithium-amalgam fused-salt cell may be used in an electrolytic system for recovering lithium from an aqueous solution of a lithium compound, wherein electrolysis of the aqueous solution in an aqueous cell in the presence of a mercury cathode produces a lithium amalgam. The present method is particularly useful for the regeneration of lithium from the aqueous reaction products of a lithium-water-air battery.

  1. Corrosion of the eta'(Cu-Sn) phase in dental amalgam.

    PubMed

    Marek, M; Okabe, T; Butts, M B; Fairhurst, C W

    1983-11-01

    Previous studies have shown preferential corrosion of the eta'(Cu-Sn) phase in high-copper dental amalgam both in vitro and in vivo, while samples of pure eta' have shown high corrosion resistance. To clarify this contradiction, samples of pure eta' crystals mixed with other phases were prepared and tested. Evaluation of the corrosion resistance was based on the results of coulometry at constant potential and potentiodynamic polarization. The corrosion susceptibility of eta' in the matrix of gamma 1(Ag-Hg) was considerably higher than the susceptibility of isolated eta'. The susceptibility of pure eta' also could be increased by plating it will small amounts of Hg. It was concluded that in dental amalgam, the presence of mercury in the phases surrounding eta' reduces its resistance to corrosion. Although eta' is more resistant to corrosion than gamma 2(Sn-Hg) which appears in low-copper amalgams, it is the least corrosion resistant major phase in high-copper amalgams and can suffer deterioration.

  2. When Old and New Regionalism Collide: Deinstitutionalization of Regions and Resistance Identity in Municipality Amalgamations

    ERIC Educational Resources Information Center

    Zimmerbauer, Kaj; Paasi, Anssi

    2013-01-01

    Regions as well as their identities and borders are social and discursive constructs that are produced and removed in contested, historically contingent and context-bound processes of institutionalization and deinstitutionalization. This article studies the deinstitutionalization of regions in the context of municipality amalgamations and the…

  3. 75 FR 10331 - In the Matter of: Amalgamated Explorations, Inc., Areawide Cellular, Inc., Genomed, Inc., Global...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-05

    ... [Federal Register Volume 75, Number 43 (Friday, March 5, 2010)] [Notices] [Pages 10331-10332] [FR Doc No: 2010-4801] SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] In the Matter of: Amalgamated Explorations, Inc., Areawide Cellular, Inc., Genomed, Inc., Global Maintech Corp., Military Resale Group, Inc., Verado Holdings, Inc., and...

  4. [Cavity preparation and restorative therapy in articles, published by the Fogorvosi Szemle in the last hundred years].

    PubMed

    Nemes, Júlia; Duhaj, Szilvia; Nyárasdy, Ida

    2009-04-01

    The aim of this review is to overview the development achieved in restorative therapy based on the publications in Fogorvosi Szemle during the past hundred years. The top quality of the restorative therapy was, and still has been the inlay, but nowadays the esthetic inlay -- fixed with adhesive material -- has priority over the gold inlay. The quality of amalgam fillings has been recently improved by using high-copper containing amalgam alloys. The development on the field of adhesive material and methods made it possible to give up the routine use of any conventional base material. The place of gingival wall of the cavity moved from subgingival position into supragingival position. The macro retention has been replaced by micro retention, and nowadays the cavity preparation prefers minimal-invasive techniques.

  5. Microleakage and Micrographic Evaluation of Composite Restorations with Various Bases over ZOE Layer in Pulpotomized Primary Molars

    PubMed Central

    Bargrizan, M.; Mirkarimi, M.; Rezamand, M.; Eskandarion, S.

    2011-01-01

    Objective Zinc oxide eugenol (ZOE) under composite restorations should be covered with a suitable material in order to prevent the harmful effect of ZOE on the composite. The aim of this in vitro study was to evaluate microleakage of composite restorations in pulpotomized primary molars with different bases for covering the ZOE layer and to assess the distance between different layers. Materials and Methods Proximo-occlusal cavities were prepared in 78 extracted second primary molars. Carious lesions were removed and pulpotomy was carried out. Zinc oxide eugenol paste was placed in 2-mm thickness. The teeth were randomly divided in 6 groups and restored as follows: 1. Light-cured composite; 2. Resin-modified glass-ionomer and composite resin; 3. Glass-ionomer and composite resin; 4. Light-cured calcium hydroxide and composite resin; 5. Calcium hydroxide and composite resin; 6. Amalgam and composite resin. The restored specimens were thermocycled for 500 cycles (5°C/55°C) and microleakage was assessed by dye penetration technique. Three specimens from each group were processed for scanning electron microscope evaluation to determine the distance between the layers. The results were analyzed by Kruskal-Wallis and Dunn tests. Results Microleakage assessment revealed significant differences between the groups (P=0.04), with the amalgam group exhibiting the lowest microleakage values. In SEM micrographs no significant differences were observed in the distance between ZOE base layers (P=0.94) and base-composite layers (P=0.47); however, the amalgam group had the lowest distances. Conclusion The use of amalgam over zinc oxide eugenol layer in pulpotomized primary molars decreases microleakage. PMID:22509457

  6. Effects of elevated temperatures on various restorative materials: an in vitro study.

    PubMed

    Bose, Raison S; Mohan, B; Lakshminarayanan, L

    2005-01-01

    In cases of mass disasters associated with fire, identification of the burnt victims can be a real challenge to the forensic team. Teeth and their restorations play a significant role to aid in the identification process, as various restorative materials have varying resistance to high temperatures. A study was undertaken to evaluate the changes taking place on teeth restored with amalgam, composites, glass ionomers, heat cure acrylic, and ceramics. The specimens were placed in a furnace and heated to predetermined temperatures of 200, 400, 600, 800, and 1000 degrees C and the changes were examined using a digital camera and stereomicroscope. Our observations show that while some restorations were able to withstand elevated temperatures, others were reduced to an unrecognizable mass at relatively low temperatures.

  7. Restoring primary anterior teeth: updated for 2014.

    PubMed

    Waggoner, William F

    2015-01-01

    The purpose of this paper was to review the current literature associated with the techniques and materials for the restoration of primary anterior teeth and make clinical recommendations based upon the available literature. A variety of esthetic restorative materials are available to utilize for restoring primary incisors. Awareness of the specific strengths, weakness, and properties of each material can enhance the clinician's ability to make the best choice of selection for each individual situation. Intracoronal restorations of primary teeth may utilize resin composites, glass ionomer cements, resin-modified ionomers, or polyacid-modified resins. Full coronal restoration of primary incisors may be indicated for a number of reasons. Crowns available for restoration of primary incisors include those that are directly bonded onto the tooth, which generally are a resin material, and crowns that are luted onto the tooth and are either some type of stainless steel or zirconia crown. There is insufficient controlled, clinical data to suggest that one type of restoration is superior to another. Operator preferences, esthetic demands by parents, the child's behavior, the amount of tooth structure remaining, and moisture and hemorrhage control are all variables that affect the decision and ultimate outcome of whatever restorative solution is chosen.

  8. Effects of high temperature on different restorations in forensic identification: Dental samples and mandible

    PubMed Central

    Patidar, Kalpana A; Parwani, Rajkumar; Wanjari, Sangeeta

    2010-01-01

    Introduction: The forensic odontologist strives to utilize the charred human dentition throughout each stage of dental evaluation, and restorations are as unique as fingerprints and their radiographic morphology as well as the types of filling materials are often the main feature for identification. The knowledge of detecting residual restorative material and composition of unrecovered adjacent restoration is a valuable tool-mark in the presumptive identification of the dentition of a burned victim. Gold, silver amalgam, silicate restoration, and so on, have a different resistance to prolonged high temperature, therefore, the identification of burned bodies can be correlated with adequate qualities and quantities of the traces. Most of the dental examination relies heavily on the presence of the restoration as well as the relationship of one dental structure to another. This greatly narrows the research for the final identification that is based on postmortem data. Aim: The purpose of this study is to examine the resistance of teeth and different restorative materials, and the mandible, to variable temperature and duration, for the purpose of identification. Materials and Methods: The study was conducted on 72 extracted teeth which were divided into six goups of 12 teeth each based on the type of restorative material. (Group 1 - unrestored teeth, group 2 - teeth restored with Zn3(PO4)2, group 3 - with silver amalgam, group 4 with glass ionomer cement, group 5 - Ni-Cr-metal crown, group 6 - metal ceramic crown) and two specimens of the mandible. The effect of incineration at 400°C (5 mins, 15 mins, 30 mins) and 1100°C (15 mins) was studied. Results: Damage to the teeth subjected to variable temperatures and time can be categorized as intact (no damage), scorched (superficially parched and discolored), charred (reduced to carbon by incomplete combustion) and incinerated (burned to ashes). PMID:21189989

  9. Yankee bonds

    SciTech Connect

    Delaney, P. )

    1993-10-01

    Yankee and Euromarket bonds may soon find their way into the financing of power projects in Latin America. For developers seeking long-term commitments under build, own, operate, and transfer (BOOT) power projects in Latin America, the benefits are substantial.

  10. Comparison of chlorine and chloramine in the release of mercury from dental amalgam.

    PubMed

    Stone, Mark E; Scott, John W; Schultz, Stephen T; Berry, Denise L; Wilcoxon, Monte; Piwoni, Marv; Panno, Brent; Bordson, Gary

    2009-01-01

    The purpose of this project was to compare the ability of chlorine (HOCl/OCl(-)) and monochloramine (NH(2)Cl) to mobilize mercury from dental amalgam. Two types of amalgam were used in this investigation: laboratory-prepared amalgam and samples obtained from dental-unit wastewater. For disinfectant exposure simulations, 0.5 g of either the laboratory-generated or clinically obtained amalgam waste was added to 250 mL amber bottles. The amalgam samples were agitated by end-over-end rotation at 30 rpm in the presence of 1 mg/L chlorine, 10 mg/L chlorine, 1 mg/L monochloramine, 10 mg/L monochloramine, or deionized water for intervals of 0 h, 2 h, 4 h, 8 h, and 24 h for the clinically obtained amalgam waste samples and 4 h and 24 h for the laboratory-prepared samples. Chlorine and monochloramine concentrations were measured with a spectrophotometer. Samples were filtered through a 0.45 microm membrane filter and analyzed for mercury with USEPA standard method 245.7. When the two sample types were combined, the mean mercury level in the 1 mg/L chlorine group was 0.020 mg/L (n=25, SD=0.008). The 10 mg/L chlorine group had a mean mercury concentration of 0.59 mg/L (n=25, SD=1.06). The 1 mg/L chloramine group had a mean mercury level of 0.023 mg/L (n=25, SD=0.010). The 10 mg/L chloramine group had a mean mercury level of 0.024 mg/L (n=25, SD=0.011). Independent samples t-tests showed that there was a significant difference between the natural log mercury measurements of 10 mg/L chlorine compared to those of 1 mg/L and 10 mg/L chloramine. Changing from chlorine to chloramine disinfection at water treatment plants would not be expected to produce substantial increases in dissolved mercury levels in dental-unit wastewater.

  11. San Francisquito Creek Stabilization at Bonde Weir Project

    EPA Pesticide Factsheets

    Information about the SFBWQP San Francisquito Creek Stabilization at Bonde Weir Project, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic resources.

  12. The effect of oxidizing water on metallic restorations in the mouth: in vitro reduction behavior of oxidizing water.

    PubMed

    Nishida, T

    1997-03-01

    Mouth-rinsing with oxydized water which contains electrolytically generated chlorine is known to hinder dental plaque formation and growth, but it also accelerates the deterioration of metallic restorations in the mouth. The present work consists of an in vitro study to elucidate the electrochemical reactions involved in the reduction of oxydized water on dental alloys through a systematic investigation of the potentiostatic polarization behavior of dental alloy electrodes. The five dental alloys selected for investigation were gold alloy, gold alloy containing platinum, silver-palladium-gold alloy, conventional amalgam and high copper amalgam. The corrosion potentials of all dental alloy electrodes were shown to be more noble in oxydized water than in 0.1N sodium chloride solution. The potential differences between the corrosion potentials were relatively small in the case of amalgam electrodes. The polarization curves for all of the dental alloy electrodes in oxydized water revealed reduction currents of chlorine, hypochlorous acid, dissolved oxygen and oxonium ion. The reduction of chlorine and hypochlorous acid started at a more noble potential than that of dissolved oxygen. The dental alloys studied, except the amalgams, did not dissolve excessively at the corrosion potentials in oxydized water.

  13. Diffusion bonding

    DOEpatents

    Anderson, Robert C.

    1976-06-22

    1. A method for joining beryllium to beryllium by diffusion bonding, comprising the steps of coating at least one surface portion of at least two beryllium pieces with nickel, positioning a coated surface portion in a contiguous relationship with an other surface portion, subjecting the contiguously disposed surface portions to an environment having an atmosphere at a pressure lower than ambient pressure, applying a force upon the beryllium pieces for causing the contiguous surface portions to abut against each other, heating the contiguous surface portions to a maximum temperature less than the melting temperature of the beryllium, substantially uniformly decreasing the applied force while increasing the temperature after attaining a temperature substantially above room temperature, and maintaining a portion of the applied force at a temperature corresponding to about maximum temperature for a duration sufficient to effect the diffusion bond between the contiguous surface portions.

  14. Clinical effectiveness of contemporary dentin bonding agents

    PubMed Central

    Krithikadatta, Jogikalmat

    2010-01-01

    Aim: The purpose of this paper is to review the literature on the clinical effectiveness of contemporary resin-based dentin bonding agents primarily focussing on the longevity of restoration. Materials and Methods: The literature published from June 2004 up to September 2010 was reviewed for clinical trials that tested the effectiveness of dentin bonding agents in the longevity of noncarious class V restoration. Results of each study reported using the USPHS criteria for clinical assessment of restoration were included and tabulated. The American Dental Association guidelines for dentin and enamel adhesives were used as a reference to compare the performance of individual bonding agents. Kruskal–Wallis followed by Mann–Whitney U was done to compare the mean Alfa score percentage for the three categories of bonding systems [etch-and-rinse (ER), self-etch primer (SEP), and self-etch-adhesive (SEA)]. Results: A comparison of the mean Alfa score percentages revealed no difference between the ER, SEP, and SEA categories of bonding systems except for marginal adaptation where ER was found to be superior to SEA. Conclusion: The clinical effectiveness of resin-based bonding agents is comparable among the three categories. PMID:21217944

  15. Effect of mercury (Hg) dental amalgam fillings on renal and oxidative stress biomarkers in children.

    PubMed

    Al-Saleh, Iman; Al-Sedairi, Al anoud; Elkhatib, Rola

    2012-08-01

    We examined the effect of mercury (Hg) associated with dental amalgam fillings on biomarkers of renal and oxidative stress in children between the ages of 5-15.5 years. Urine samples were analyzed for N-acetyl-β-D-glucosaminidase (NAG), α(1)-microglobulin (α(1)-MG), β(2)-microglobulin (β(2)-MG), retinol binding protein (RBP), albumin (ALB), 8-hydroxy-2-deoxyguanosine (8-OHdG) and malondialdehyde (MDA). The level of urinary Hg (UHg-C) was calculated as μg/g creatinine. Multiple regression analyses revealed that the excretion of urinary NAG was significantly associated with the presence of dental amalgam fillings (β=0.149, P=0.03) and the levels of UHg-C (β=0.531, P=0), with an interaction between the two (P=0). The increase in urinary NAG in relation to UHg-C levels had a dose-effect pattern. The lowest observed effect was seen at UHg-C levels above 1.452 μg/g creatinine, which is lower than previously reported. In contrast, α(1)-MG was negatively associated with the presence of dental amalgam fillings (β=-0.270, P=0), but positively with UHg-C levels (β=0.393, P=0). There were 7 children without, and one child with, dental amalgam fillings with urinary α(1)-MG levels above the reference limit of >7 mg/g creatinine. Even though α(1)-MG seems to be a reliable biomarker for early changes in renal functions, it might exert its effect only at a higher level of exposure. An inverse relationship was also observed between urinary 8-OHdG levels and the presence of dental amalgam fillings. This might suggest that the dental amalgam does not increase DNA damage but reduces the capacity to repair DNA, leading to lower urinary excretion of 8-OHdG. On the other hand, we found that Hg affected the excretion of urinary 8-OHdG in a dose-related pattern that was mostly associated with long-term exposure to low Hg levels. Urinary NAG levels were positively associated with urinary MDA levels (β=0.516, P=0) but not with 8-OHdG (β=0.134, P=0.078) after adjustment for

  16. Enhancement in resistivity resolution based on the data sets amalgamation technique at Bukit Bunuh, Perak, Malaysia

    NASA Astrophysics Data System (ADS)

    Anderson Bery, Andy; Saad, Rosli; Hidayah, I. N. E.; Azwin, I. N.; Saidin, Mokhtar

    2015-01-01

    In this paper, we have carried out a study with the main objective to enhance the resolution of the electrical resistivity inversion model by introducing the data sets amalgamation technique to be used in the data processing stage. Based on the model resistivity with topography results, the data sets amalgamation technique for pole-dipole and wenner- schlumberger arrays are successful in identifying the boundary or interface of the overburden and weathered granite. Although the electrical resistivity method is well known, the proper selection of an array and appropriate inversion parameters setting such as damping factors are important in order to achieve the study objective and to image the target at the Earth's subsurface characterizations.

  17. Steady-state transfer and depletion kinetics of mercury from amalgam fillings.

    PubMed

    Halbach, S; Welzl, G; Kremers, L; Willruth, H; Mehl, A; Wack, F X; Hickel, R; Greim, H

    2000-10-02

    In 29 volunteers with a low amalgam load, the number of amalgam-covered tooth surfaces and the occlusal area of the fillings were determined. Before and at select times after removal of all amalgams, concentrations of total mercury were measured by cold-vapor atomic absorption in plasma and erythrocytes as well as in urine together with the excretion rate. Absorbed daily doses were estimated from intraoral Hg emission by two separate methods. The transfer of Hg from the fillings via the oral cavity and blood to urinary excretion was evaluated according to the most representative combination of parameters. This consisted of occlusal area (1), absorbed dose (2), Hg concentration in plasma (3) and urinary excretion (4). Pairwise correlation coefficients were 0.49 for parameters 1 vs. 2, and 0.75 each for parameters 2 vs. 3 and 3 vs. 4. Within 9 days after removal of the fillings, a transient increase in Hg levels was observed in plasma only; in the group without a rubber dam, concentrations increased significantly above pre-removal values at days 1 and 3, whereas they decreased significantly below pre-removal values at day 30 in the rubber-dam group and at day 100 in both groups. Excretion rates decreased significantly at day 100 in the protected group. Peak plasma-Hg was 0.6 ng/ml on average at day 1 and decreased with halftimes of 3 and 43 days in subjects protected by a rubber dam. The results indicated that concentrations of total mercury in plasma responded rapidly to changes in the amalgam status and reflected the actual absorption most reliably. Notably, plasma-Hg levels were sensitive enough to detect a transient attenuation of the additional exposure after using a rubber dam during the removal of only a few fillings. However, being small in magnitude and lasting 100 days at best, the rubber-dam effect had minor toxicological relevance.

  18. The Decim system for the production of dental restorations.

    PubMed

    Sjölin, R; Sundh, A; Bergman, M

    1999-07-01

    The general background to the development of CAD/CAM is presented in short. Specific problems when using this technique for the manufacturing of dental restorations are emphasized, and then the reverse engineering and CAD/CAM process that have been implemented in the Decim (Dentronic AB, Skellefteå, Sweden) system are presented. The system is organized in the following way: 1. The measurement process is encapsulated in a product called Decim Reader. 2. The design functionality is provided by software running on a conventional personal computer. This unit is called Decim Designer. 3. The CAM calculation is done by a dedicated personal computer, the Decim Calculator, that does not require any user interaction. 4. The actual manufacturing of the restorations is performed in the Decim Producer that works with a grinding technique. These components communicate via a local computer network or, when a distributed solution is desired, via internet. The Decim System is presently used for the production of dental ceramic restorations, and it is the only system which can be used for manufacturing inlays of yttria-stabilized zirconia. This ceramic material is CE-approved under the brand name Denzir (Dentronic AB, Skellefteå, Sweden). Due to its favorable mechanical properties, it may be an alternative to dental amalgam, and is therefore of topical interest in dentistry. The use of computer-based techniques for manufacturing dental restorations is briefly outlined and commented on.

  19. Versatile combustion-amalgamation technique for the photometric determination of mercury in fish and environmental samples

    USGS Publications Warehouse

    Willford, Wayne A.; Hesselberg, Robert J.; Bergman, Harold L.

    1973-01-01

    Total mercury in a variety of substances is determined rapidly and precisely by direct sample combustion, collection of released mercury by amalgamation, and photometric measurement of mercury volatilized from the heated amalgam. Up to 0.2 g fish tissue is heated in a stream of O2 (1.2 L/min) for 3.5 min in 1 tube of a 2-tube induction furnace. The released mercury vapor and combustion products are carried by the stream of O2 through a series of traps (6% NaOH scrubber, water condenser, and Mg(CIO4)2 drying tube) and the mercury is collected in a 10 mm diameter column of 24 gauge gold wire (8 g) cut into 3 mm lengths. The resulting amalgam is heated in the second tube of the induction furnace and the volatilized mercury is measured with a mercury vapor meter equipped with a recorder-integrator. Total analysis time is approximately 8 min/sample. The detection limit is less than 0.002 μg and the system is easily converted for use with other biological materials, water, and sediments.

  20. In vitro corrosion behaviour and microhardness of high-copper amalgams with platinum and indium.

    PubMed

    Ilikli, B G; Aydin, A; Işimer, A; Alpaslan, G

    1999-02-01

    Samples prepared from Luxalloy, GS-80, Permite-C and Logic and polished after 24 h by traditional methods were stored in polypropylene tubes containing phosphate-buffered saline solutions (pH 3.5 and 6.5) and distilled water. The amounts of mercury, silver, tin, copper, zinc, platinum and indium in the test solutions were determined at the first, second, eighth, 52nd and 78th week by atomic absorption spectrometry. At the end of the eighth week the amalgam samples were removed from solutions and evaluated by Rockwell Super Scial Microhardness tester. Statistically significant low amounts of metal ions were measured for Permite-C containing indium and Logic containing platinum. The microhardness test results showed that there were statistically significant increases in the microhardness of Permite-C and Logic. As a result it was shown that the amalgam samples were affected from corrosion conditions to different degrees. Sample of the Logic group that was stored in distilled water, showed smoother surface properties than other amalgam samples containing high copper. However, it was observed that samples of Permite-C group had the smoothest surface properties.

  1. Effects of elevated temperatures on different restorative materials: An aid to forensic identification processes

    PubMed Central

    Pol, Chetan A.; Ghige, Suvarna K.; Gosavi, Suchitra R.; Hazarey, Vinay K.

    2015-01-01

    Background: Heat-induced alterations to dental and restorative materials can be of great interest to forensic dentistry. Knowing the specific optical behavior of dental materials can be of high importance as recognition of changes induced by high temperatures can lead to the determination of material which was used in a dental restoration, facilitating identification of burned human remains. Aim: To observe the effects of predetermined temperatures (200°C–400°C–600°C–800°C–1000°C) on unrestored teeth and different restorative materials macroscopically and then examine them under a stereomicroscope for the purpose of identification. Materials and Methods: The study was conducted on 375 extracted teeth which were divided into five groups of 75 teeth each as follows: group 1- unrestored teeth, group 2- teeth restored with all-ceramic crowns, Group 3- with class I silver amalgam filling, group 4- with class I composite restoration, and group 5- with class I glass ionomer cement restoration. Results: Unrestored and restored teeth display a series of specific macroscopic & stereomicroscopic structural changes for each range of temperature. Conclusion: Dental tissues and restorative materials undergo a series of changes which correlate well with the various temperatures to which they were exposed. These changes are a consequence of the nature of the materials and their physicochemical characteristics. PMID:26005305

  2. Pi Bond Orders and Bond Lengths

    ERIC Educational Resources Information Center

    Herndon, William C.; Parkanyi, Cyril

    1976-01-01

    Discusses three methods of correlating bond orders and bond lengths in unsaturated hydrocarbons: the Pauling theory, the Huckel molecular orbital technique, and self-consistent-field techniques. (MLH)

  3. Embryotoxicity assays for leached components from dental restorative materials

    PubMed Central

    2011-01-01

    Background Currently, there are no suitable assays available to evaluate the embryotoxicity of leached components from restorative dental materials. Methods The effect of the medium conditioned by composites and amalgam on mouse blastocysts in vitro was tested. The materials were also subcutaneously implanted, and the effect of the medium supplemented with serum from the host blood was evaluated in the embryotoxicity assay. The embryo implantation rate in the material-transplanted mothers was also evaluated. Results The results show that while the culture in media conditioned by amalgams did not affect blastocyst development, the medium conditioned by composites caused blastocyst degeneration and apoptosis. The development of blastocysts in a medium containing serum obtained from animals after transplantation was, however, without effect. Finally, inconsistent reduction in the implantation rate in transplanted mothers was observed. Conclusions In this study, we provide examples of in vitro and in vivo tests that may be used to evaluate embryotoxicity for dental materials. Our results show that leached components from our composite-material induced embryotoxicity in vitro, however, no toxicity was observed when subcutaneously implanted in vivo. This highlights the necessity of integrated in vitro and in vivo tests for valuable predictive estimation of embryotoxicity for complex materials. PMID:21978455

  4. Breuner Marsh Restoration Project

    EPA Pesticide Factsheets

    Information about the San Francisco Bay Water Quality Project (SFBWQP) Breuner Marsh Restoration Project, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic resources.

  5. Quartermaster Reach Restoration Project

    EPA Pesticide Factsheets

    Information about the SFBWQP Quartermaster Reach Restoration Project, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic resources.

  6. Bonded Lubricants

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Another spinoff to the food processing industry involves a dry lubricant developed by General Magnaplate Corp. of Linden, N.J. Used in such spacecraft as Apollo, Skylab and Viking, the lubricant is a coating bonded to metal surfaces providing permanent lubrication and corrosion resistance. The coating lengthens equipment life and permits machinery to be operated at greater speed, thus increasing productivity and reducing costs. Bonded lubricants are used in scores of commercia1 applications. They have proved particularly valuable to food processing firms because, while increasing production efficiency, they also help meet the stringent USDA sanitation codes for food-handling equipment. For example, a cookie manufacturer plagued production interruptions because sticky batter was clogging the cookie molds had the brass molds coated to solve the problem. Similarly, a pasta producer faced USDA action on a sanitation violation because dough was clinging to an automatic ravioli-forming machine; use of the anti-stick coating on the steel forming plates solved the dual problem of sanitation deficiency and production line downtime.

  7. Restorative dentistry for children.

    PubMed

    Donly, Kevin J

    2013-01-01

    This article discusses contemporary pediatric restorative dentistry. Indications and contraindications for the choice of different restorative materials in different clinical situations, including the risk assessment of the patient, are presented. The specific use of glass ionomer cement or resin-modified glass ionomer cement, resin-based composite, and stainless steel crowns is discussed so that preparation design and restoration placement is understood.

  8. Linking restoration ecology with coastal dune restoration

    NASA Astrophysics Data System (ADS)

    Lithgow, D.; Martínez, M. L.; Gallego-Fernández, J. B.; Hesp, P. A.; Flores, P.; Gachuz, S.; Rodríguez-Revelo, N.; Jiménez-Orocio, O.; Mendoza-González, G.; Álvarez-Molina, L. L.

    2013-10-01

    Restoration and preservation of coastal dunes is urgently needed because of the increasingly rapid loss and degradation of these ecosystems because of many human activities. These activities alter natural processes and coastal dynamics, eliminate topographic variability, fragment, degrade or eliminate habitats, reduce diversity and threaten endemic species. The actions of coastal dune restoration that are already taking place span contrasting activities that range from revegetating and stabilizing the mobile substrate, to removing plant cover and increasing substrate mobility. Our goal was to review how the relative progress of the actions of coastal dune restoration has been assessed, according to the ecosystem attributes outlined by the Society of Ecological Restoration: namely, integrity, health and sustainability and that are derived from the ecological theory of succession. We reviewed the peer reviewed literature published since 1988 that is listed in the ISI Web of Science journals as well as additional references, such as key books. We exclusively focused on large coastal dune systems (such as transgressive and parabolic dunefields) located on natural or seminatural coasts. We found 150 articles that included "coastal dune", "restoration" and "revegetation" in areas such as title, keywords and abstract. From these, 67 dealt specifically with coastal dune restoration. Most of the studies were performed in the USA, The Netherlands and South Africa, during the last two decades. Restoration success has been assessed directly and indirectly by measuring one or a few ecosystem variables. Some ecosystem attributes have been monitored more frequently (ecosystem integrity) than others (ecosystem health and sustainability). Finally, it is important to consider that ecological succession is a desirable approach in restoration actions. Natural dynamics and disturbances should be considered as part of the restored system, to improve ecosystem integrity, health and

  9. Amalgam tattoo: report of an unusual clinical presentation and the use of energy dispersive X-ray analysis as an aid to diagnosis

    SciTech Connect

    McGinnis, J.P. Jr.; Greer, J.L.; Daniels, D.S.

    1985-01-01

    An unusual appearing gingival amalgam pigmentation (amalgam tattoo) that completely surrounded the maxillary right first premolar in a 13-year-old boy is presented. Because of the wide distribution and apparent clinical progression of the discoloration, an excisional biopsy was performed. The histopathologic diagnosis of amalgam pigmentation was confirmed in paraffin sections by energy dispersive X-ray microanalysis. Silver, tin, and mercury were detected in the specimen.

  10. Effectiveness of simplified dentin bonding systems.

    PubMed

    Imai, T; Itoh, K; Tani, C; Manabe, A; Yamashita, T; Hisamitsu, H; Wakumoto, S

    1998-03-01

    The effectiveness of newly developed commercial dentin bonding systems (SB, MB II and KB) was evaluated by measuring the contraction gap width of a resin composite restored into a cylindrical dentin cavity prepared in an extracted human molar and by measuring the tensile bond strength to the flat dentin surface. In addition, calcium loss during dentin conditioning was analyzed using electron microanalyses. An experimental dentin bonding system composed of EDTA conditioning, GM solution priming and a bonding agent containing 10-MDP was employed as a control in which it was presumed that contraction gap formation was prevented completely. However, gap formation was observed using the three commercial simplified dentin bonding systems. SEM observation showed that the gap was formed between the resin composite and the top surface of the dentin cavity wall indicating that the fracture occurred at the adhesive interface, but never inside the dentin nor inside the resin composite.

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

    PubMed Central

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

    2015-01-01

    Background: Newer dentin bonding agents were developed to improve the quality of composite restoration and to reduce time consumption in its application. The aim of the present study was to evaluate tensile bond strength of 6th, 7th and 8th generation bonding agents by in vitro method. Materials and Methods: Selected 60 permanent teeth were assigned into 20 in each group (Group I: 6th generation bonding agent-Adper SE plus 3M ESPE, Group II: 7th generation bonding agent-G-Bond GC Corp Japan and Group III: 8th generation dentin adhesives-FuturaBond, DC, Voco, Germany). With high-speed diamond disc, coronal dentin was exposed, and selected dentin bonding agents were applied, followed by composite restoration. All samples were saved in saline for 24 h and tensile bond strength testing was done using a universal testing machine. The obtained data were tabulated and statistically analyzed using ANOVA test. Results: The tensile bond strength readings for 6th generation bonding agent was 32.2465, for 7th generation was 31.6734, and for 8th-generation dentine bonding agent was 34.74431. The highest tensile bond strength was seen in 8th generation bonding agent compared to 6th and 7th generation bonding agents. Conclusion: From the present study it can be conclude that 8th generation dentine adhesive (Futura DC, Voco, Germany) resulted in highest tensile bond strength compared to 6th (Adper SE plus, 3M ESPE) and 7th generation (G-Bond) dentin bonding agents. PMID:26028901

  12. Power system restoration planning

    SciTech Connect

    Adibi, M.M. ); Fink, L.H.

    1994-02-01

    System restoration, as an extraordinary mode of system operation, requires careful planning and operator training. The generic tasks of restoration include determination of system and equipment status, preparation of plants and network for systematic restoration, reenergization of the network, and system rebuilding. The procedures for developing an effective restoration plan include formation of a qualified planning team, review of relevant system characteristics, formulation of assumptions regarding blackout scenarios, agreement on restoration goals, development of strategy and tactics, validation of the plan, training, and documentation.

  13. Restoring the incisal edge.

    PubMed

    Terry, Douglas A

    2005-01-01

    Restorative dentistry evolves with each development of new material and innovative technique. Selection of improved restorative materials that simulate the physical properties and other characteristics of natural teeth, in combination with restorative techniques such as the proximal adaptation and incremental layering, provide the framework that ensures the optimal development of an esthetic restoration. These advanced placement techniques offer benefits such as enhanced chromatic integration, polychromatism, ideal anatomical form and function, optimal proximal contact, improved marginal integrity and longer lasting directly placed composite restorations. The purpose of this article is to give the reader a better understanding of the complex restorative challenge in achieving true harmonization of the primary parameters in esthetics (that is, color, shape and texture) represented by the replacement of a single anterior tooth. The case presented demonstrates the restoration of a Class IV fracture integrating basic adhesive principles with these placement techniques and a recently developed nanoparticle hybrid composite resin system (Premise, Kerr/Sybron, Orange, CA). The clinical presentation describes preoperative considerations, tooth preparation, development of the body layer, internal characterization with tints, development of the artificial enamel layer, shaping and contouring, and polishing of a Class IV composite restoration. The clinical significance is that anterior tooth fractures can be predictably restored using contemporary small particle hybrid composite resin systems with the aforementioned restorative techniques. These placement techniques when used with proper attention to preparation design, adhesive protocol and finishing and polishing procedures, allow the clinician to successfully restore form, function and esthetics to the single anterior tooth replacement.

  14. Application of Laser Irradiation for Restorative Treatments

    PubMed Central

    Davoudi, Amin; Sanei, Maryam; Badrian, Hamid

    2016-01-01

    Nowadays, lasers are widely used in many fields of medicine. Also, they can be applied at many branches of dental practice such as diagnosis, preventive procedures, restorative treatments, and endodontic therapies. Procedures like caries removal, re-mineralization, and vital pulp therapy are the most noticeable effects of laser irradiation which has gained much attention among clinicians. With controlled and appropriate wavelength, they can help stimulating dentinogenesis, controlling pulpal hemorrhage, sterilization, healing of collagenic proteins, formation of a fibrous matrix, and inducing hard tissue barrier. Nevertheless, there are many controversies in literatures regarding their effects on the quality of bonded restorations. It hampered a wide application of lasers in some aspects of restorative dentistry and requirements to identify the best way to use this technology. The aim of this mini review is to explain special characteristics of laser therapy and to introduce the possible applications of laser devices for dental purposes. PMID:27990188

  15. Distribution of toxic elements in teeth treated with amalgam using μ-energy dispersive X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Guerra, M.; Ferreira, C.; Carvalho, M. L.; Santos, J. P.; Pessanha, S.

    2016-08-01

    Over the years, the presence of mercury in amalgam fillings has raised some safety concerns. Amalgam is one of the most commonly used tooth fillings and contains approximately 50% of elemental mercury and 50% of other metals, mostly silver, tin and copper. Amalgam can release small amounts of mercury vapor over time, and patients can absorb these vapors by inhaling or ingesting them. In this study, 10 human teeth treated with dental amalgam were analyzed using energy dispersive X-ray fluorescence (EDXRF) to study the diffusion of its constituents, Ag, Cu, Sn and Hg. The used EDXRF setup, makes use of a polycapillary lens to focus radiation up to 25 μm allowing the mapping of the elemental distribution in the samples. Quantification was performed using the inbuilt software based on the Fundamental Parameters method for bulk samples, considering a hydroxyapatite matrix. The teeth were longitudinally cut and each slice was scanned from the surface enamel to the inner region (dentin and pulp cavity). Mercury concentration profiles show strong levels of this element close to the amalgam region, decreasing significantly in the dentin, and increasing again up to 40,000 μg·g- 1 in the cavity were the pulp used to exist when the tooth was vital.

  16. Analysis of tensile bond strengths using Weibull statistics.

    PubMed

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

    2004-09-01

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

  17. Determination of lead and cadmium in seawater using a vibrating silver amalgam microwire electrode.

    PubMed

    Bi, Zhaoshun; Salaün, Pascal; van den Berg, Constant M G

    2013-03-26

    Silver amalgamated electrodes are a good substrate to determine lead (Pb) and cadmium (Cd) in seawater because they have properties similar to mercury but without the free mercury (Hg). Here a silver amalgamated microwire (SAM) electrode is optimised for the determination of Pb and Cd in coastal waters and uncontaminated ocean waters. The SAM was vibrated during the deposition step to increase the sensitivity, and electroanalytical parameters were optimised. The Hg coating required plating from a relatively concentrated (millimolar) solution, much greater (500×) than used for instance to coat glassy carbon electrodes. However, the coating on the ex situ amalgamated electrode was found to be stable and could be used for up to a week to determine trace levels of Pb in seawater of natural pH. The limit of detection square-wave ASV (50 Hz) using the pre-plated SAM electrode was 8 pM Pb using a 1-min plating time at pH 4.5. The limit of detection in pH 2 seawater was 4 pM using a 5-min plating time, and it was 12 pM using a 10-min plating time at natural pH in the presence of air, using a square-wave frequency of 700 Hz. The vibrating SAM electrode was tested on the determination of Pb in reference seawater samples from the open Atlantic (at the 20 pM level), Pacific, and used for a study of Pb in samples collected over 24 h in Liverpool Bay (Irish Sea).

  18. Mercury in dental amalgam: Are our health care workers at risk?

    PubMed

    Sahani, M; Sulaiman, N S; Tan, B S; Yahya, N A; Anual, Z F; Mahiyuddin, W R Wan; Khan, M F; Muttalib, K A

    2016-11-01

    Dental amalgam in fillings exposes workers to mercury. The exposure to mercury was investigated among 1871 dental health care workers. The aim of the study was to evaluate the risk of mercury exposure among dental compared to nondental health care workers and to determine other risk factors for mercury exposure. Respondents answered questionnaires to obtain demographic, personal, professional, and workplace information and were examined for their own amalgam fillings. Chronic mercury exposure was assessed through urinary mercury levels. In total, 1409 dental and 462 nondental health care workers participated in the study. Median urine mercury levels for dental and nondental health care workers were 2.75 μg/L (interquartile range [IQR] = 3.0175) and 2.66 μg/L (IQR = 3.04) respectively. For mercury exposure, there were no significant risk factor found among the workers involved within the dental care. The Mann-Whitney test showed that urine mercury levels were significantly different between respondents who eat seafood more than 5 times per week compared to those who eat it less frequently or not at all (p = 0.003). The urinary mercury levels indicated significant difference between dental workers in their practice using squeeze cloths (Mann-Whitney test, p = 0.03). Multiple logistic regression showed that only the usage of cosmetic products that might contain mercury was found to be significantly associated with the urinary mercury levels (odds ratio [OR] = 15.237; CI: 3.612-64.276). Therefore, mean urinary mercury levels of health care workers were low. Exposure to dental amalgam is not associated with high mercury exposure. However, usage of cosmetic products containing mercury and high seafood consumption may lead to the increase of exposure to mercury.

  19. Use of copper shavings to remove mercury from contaminated groundwater or wastewater by amalgamation.

    PubMed

    Huttenloch, Petra; Roehl, Karl Ernst; Czurda, Kurt

    2003-09-15

    The efficacy of copper shavings (Cu(0)) for the removal of Hg2+ from aqueous solution by amalgamation is demonstrated. Two kinds of copper shavings were investigated: (a) chemically processed shavings (Fluka) and (b) recycled shavings from scrap metal. Batch sorption experiments yielded very high retardation coefficients of 28 850-82 830 for the concentration range studied (1-10 000 microg/L Hg2+ dissolved in distilled water or in a 0.01 M CaCl2 matrix solution). Sorption data were well-described bythe Freundlich isotherm equation. Kinetic batch sorption experiments showed that 96-98% of Hg2+ was removed within 2 h. Column experiments were performed with a mercury solution containing 1000 microg/L Hg in a 0.01 M CaCl2 matrix with a flow rate of 0.5 m/d. No mercury breakthrough (c/c(0) = 0.5) could be detected after more than 2300 percolated pore volumes, and the high retardation coefficients determined in the batch studies could be confirmed. Copper was released from the shavings due to the amalgamation process and to copper corrosion by oxygen, resulting in concentrations of mobilized copper of 0.2-0.6 mg/L. Due to their high efficiency in removing Hg2+ from aqueous solution, the use of copper shavings for the removal of mercury from contaminated water is suggested, employing a sequential system of mercury amalgamation followed by the removal of mobilized copper by an ion exchanger such as zeolites. Possible applications could be in environmental technologies such as wastewater treatment or permeable reactive barriers for in situ groundwater remediation.

  20. Assessment of exposures and potential risks to the US adult population from wear (attrition and abrasion) of gold and ceramic dental restorations.

    PubMed

    Richardson, G Mark; Clemow, Scott R; Peters, Rachel E; James, Kyle J; Siciliano, Steven D

    2016-01-01

    Little has been published on the chemical exposures and risks of dental restorative materials other than from dental amalgam and composite resins. Here we provide the first exposure and risk assessment for gold (Au) alloy and ceramic restorative materials. Based on the 2001-2004 US National Health and Nutrition Examination Survey (NHANES), we assessed the exposure of US adults to the components of Au alloy and ceramic dental restorations owing to dental material wear. Silver (Ag) is the most problematic component of Au alloy restorations, owing to a combination of toxicity and proportional composition. It was estimated that adults could possess an average of four tooth surfaces restored with Au alloy before exceeding, on average, the reference exposure level (REL) for Ag. Lithium (Li) is the most problematic component of dental ceramics. It was estimated that adults could possess an average of 15 tooth surfaces restored with ceramics before exceeding the REL for Li. Relative risks of chemical exposures from dental materials decrease in the following order: Amalgam>Au alloys>ceramics>composite resins.

  1. Determination of mercury in blood, urine and saliva for the biological monitoring of an exposure from amalgam fillings in a group with self-reported adverse health effects.

    PubMed

    Zimmer, Holger; Ludwig, Heidi; Bader, Michael; Bailer, Josef; Eickholz, Peter; Staehle, Hans Jörg; Triebig, Gerhard

    2002-04-01

    It has been argued that the release of mercury from amalgam fillings is of toxicological relevance. The aim of the study was to determine the internal mercury exposure of two groups differing in their attitude towards possible health hazards by mercury from amalgam fillings. It was to be examined if the two groups differ with regard to the mercury concentration in different biological matrices and to compare the results with current reference values. Blood, urine and saliva samples were analyzed from 40 female subjects who claimed to suffer from serious health damage due to amalgam fillings ("amalgam sensitive subjects"). 43 female control subjects did not claim any association ("amalgam non-sensitive controls"). Mercury was determined by means of cold vapour atomic absorption spectrometry. Number and surfaces of amalgam fillings were determined by dentists for each subject. Median (range) mercury levels in blood were 2.35 (0.25-13.40) micrograms/l for "amalgam sensitive subjects" and 2.40 (0.25-10.50) micrograms/l for "amalgam non-sensitive controls". In urine, the median mercury concentrations were 1.55 (0.06-14.70) micrograms/l and 1.88 (0.20-8.43) micrograms/g creatinine respectively. No significant differences could be found between the two groups. Mercury levels in blood and urine of the examined subjects were within the range of background levels in the general population including persons with amalgam fillings. Stimulated saliva contained 76.4 (6.7-406.0) micrograms mercury/l in "amalgam sensitive subjects" and 57.0 (2.8-559.0) micrograms mercury/l in controls (not significant). Mercury levels in saliva did not correlate with the concentrations in blood and urine, but merely with the number of amalgam fillings or of the filling surfaces. Mercury in saliva is therefore not recommended for a biological monitoring.

  2. [The corrosion behavior of antimony in a Ag-Sn-Cu-Sb amalgam].

    PubMed

    Weiland, M; Borrmann, S; Nossek, H

    1989-01-01

    Specimen of amalgam containing antimony were stored in solutions with different pH and different content of rhodanide until 21 days. The most antimony were solved within 24 hours. After 7 days an increase of the antimony concentration were not observed in physiological pH. An inhibition of corrosion by rhodanide existed only after incubation from 21 days. The quantity of antimony (10-21 micrograms) were analysed by mean of atomic absorption spectroscopy. It represent not a risk for the health. The natural presence of this element in environment and in human body is discussed to the analysed quantity of solved antimony.

  3. Structural chemistry and number theory amalgamized: crystal structure of Na11Hg52.

    PubMed

    Hornfeck, Wolfgang; Hoch, Constantin

    2015-12-01

    The recently elucidated crystal structure of the technologically important amalgam Na11Hg52 is described by means of a method employing some fundamental concept of number theory, namely modular arithmetical (congruence) relations observed between a slightly idealized set of atomic coordinates. In combination with well known ideas from group theory, regarding lattice-sublattice transformations, these allow for a deeper mutual understanding of both and provide the structural chemist with a slightly different kind of spectacles, thus enabling a distinct viw on complex crystal structures in general.

  4. Watershed Restoration Project

    SciTech Connect

    Julie Thompson; Betsy Macfarlan

    2007-09-27

    In 2003, the U.S. Department of Energy issued the Eastern Nevada Landscape Coalition (ENLC) funding to implement ecological restoration in Gleason Creek and Smith Valley Watersheds. This project was made possible by congressionally directed funding that was provided through the US Department of Energy, Energy Efficiency and Renewable Energy, Office of the Biomass Program. The Ely District Bureau of Land Management (Ely BLM) manages these watersheds and considers them priority areas within the Ely BLM district. These three entities collaborated to address the issues and concerns of Gleason Creek and Smith Valley and prepared a restoration plan to improve the watersheds’ ecological health and resiliency. The restoration process began with watershed-scale vegetation assessments and state and transition models to focus on restoration sites. Design and implementation of restoration treatments ensued and were completed in January 2007. This report describes the restoration process ENLC undertook from planning to implementation of two watersheds in semi-arid Eastern Nevada.

  5. Retention of composite resin restorations in class IV preparations.

    PubMed

    Eid, Hani

    2002-01-01

    Clinicians often utilized composite resin restorations in combination with different types of preparation to restore class IV fractures on anterior incisors. A new preparation technique called (stair-step chamfer technique) is investigated in this study to detect bond strength to tooth structure. Eighty-eight bovine teeth were divided into 4 groups. Group I had twenty-three samples with a 45 degree bevel that extended 2 millimeters beyond the fracture line. Group II had twenty-three samples with a circumferential chamfer, which extended 2 mm beyond the fracture line and half the enamel thickness in depth. Group III had twenty-three samples with a facial stair-step chamfer, which followed the anatomical contour and extended 2 mm beyond the fracture line with a lingual plain chamfer. Group IV had eighteen samples as controls, which were untreated teeth. The first three groups were prepared and restored with hybrid composite resin in conjunction with a single step bonding agent and as surface penetrating sealer, then tested for shear-bond strength on the Instron machine. The results were that there was no significant difference found between the treated teeth when tested for shear-bond strength. However, according to the site of the fracture, the stair-step chamfer technique gave significantly better results. It can be concluded that, the stir-step chamfer technique provides the clinician better environment to place a composite resin restoration resulting in good shear-bond strength and better esthetics.

  6. Chemical Bonds II

    ERIC Educational Resources Information Center

    Sanderson, R. T.

    1972-01-01

    The continuation of a paper discussing chemical bonding from a bond energy viewpoint, with a number of examples of single and multiple bonds. (Part I appeared in volume 1 number 3, pages 16-23, February 1972.) (AL)

  7. What Determines Bond Costs. Municipal Bonds Series.

    ERIC Educational Resources Information Center

    Young, Douglas; And Others

    Public officials in small towns who participate infrequently in the bond market need information about bond financing. This publication, one in a series of booklets published by the Western Rural Development Center using research gathered between 1967-77, discusses factors influencing the marketability and cost of bond financing for towns and…

  8. Plasmonic detection of mercury via amalgam formation on surface-immobilized single Au nanorods

    PubMed Central

    Schopf, Carola; Martín, Alfonso; Iacopino, Daniela

    2017-01-01

    Abstract Au nanorods were used as plasmonic transducers for investigation of mercury detection through a mechanism of amalgam formation at the nanorod surfaces. Marked scattering color transitions and associated blue shifts of the surface plasmon resonance peak wavelengths (λ max) were measured in individual nanorods by darkfield microscopy upon chemical reduction of Hg(II). Such changes were related to compositional changes occurring as a result of Hg–Au amalgam formation as well as morphological changes in the nanorods’ aspect ratios. The plot of λ max shifts vs. Hg(II) concentration showed a linear response in the 10–100 nM concentration range. The sensitivity of the system was ascribed to the narrow width of single nanorod scattering spectra, which allowed accurate determination of peak shifts. The system displayed good selectivity as the optical response obtained for mercury was one order of magnitude higher than the response obtained with competitor ions. Analysis of mercury content in river and tap water were also performed and highlighted both the potential and limitation of the developed method for real sensing applications. PMID:28179959

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

    PubMed

    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.

  10. Super (a, d) - Fn - antimagic total labeling for a connected and disconnected amalgamation of fan graphs

    NASA Astrophysics Data System (ADS)

    Dafik, Agustin, Ika Hesti; Khuri Faridatun, N.

    2016-02-01

    All graph in this paper are finite, simple and undirected. Let G = (V (G), E(G)) be a graph of order p and size q. Graph G admits a H-covering, if every edge in E(G) belongs to at least one subgraph of G isomorphic to a given graph H. A graph G is said to be an (a, d)-H-antimagic total labeling if there exist a bijective function f : V (G) ∪ E(G) → {1, 2,…, |V(G)| + |E(G)|} such that for all subgraphs H' isomorphic to H, the total H-weights w(H) = ∑v∈V (H') f (v) + ∑e∈E(H') f (e) form an arithmetic sequence {a, a + d, a + 2d, …, a + (t - 1)d}, where a and d are positive integers and t is the number of all subgraphs H' isomorphic to H. Such a labeling is called a super if the smallest labels appear in the vertices. This paper studies the super (a, d)-Fn-antimagic total labeling for a connected and disconnected amalgamation of fan graphs. We can prove that, for some feasible d, a connected and disconnected amalgamation of fan graphs admit a super (a, d) - Fn-antimagic total labeling.

  11. An update on resin-bonded bridges.

    PubMed

    Barber, M W; Preston, A J

    2008-03-01

    Since the introduction of the 'Rochette' bridge in the 1970s the resin-bonded bridge has undergone a number of developments to become a commonly used technique for replacement of a missing tooth, especially in a minimally restored dentition. One of the major advantages of the resin-bonded bridge is that it requires less tooth preparation than conventional bridgework, with some authorities advising no preparation at all. Some reports have suggested poor long-term success rates, however, if used in appropriate clinical situations, this treatment modality can be extremely successful. The aim of this paper is to review the literature relating to resin-bonded bridges and suggest recommendations for clinicalpractice concerning the provision of resin-bonded bridges.

  12. Impact of rehabilitation with metal-ceramic restorations on oral health-related quality of life.

    PubMed

    da Silva, Gisele Rodrigues; Roscoe, Marina Guimarães; Ribeiro, Cristianne Pacheco; da Mota, Adérito Soares; Martins, Luís Roberto Marcondes; Soares, Carlos José

    2012-01-01

    Dental ceramics present excellent ability to reproduce the natural teeth regarding esthetic and biomechanics. Recently, due to the advancement of ceramic technology, metal-free restorations were developed. However, the traditional metal-ceramic restorations still present the requirements of high strength, long survival in the oral environment and favorable aesthetics. In this context, it is essential to know the specificity of each ceramic system available in order to apply it properly to various clinical situations. This report describes an integrated rehabilitation using metal-ceramic restorations of a patient at 50 years of age, who presented edentulous spaces, and previous unsatisfactory composite and amalgam restorations, and indirect metallic restorations, leading to compromised quality of life in both functional and psychosocial aspects. The impact on quality of life was measured using a generic instrument, OHIP-14, validated for the World Health Organization, which covers both the biological and the psychosocial dimensions. This instrument was applied to the patient before and after treatment. The patient had an overall OHIP-14 score of 28 before the treatment and after treatment the score decreased to 0, showing that dental and oral health conditions are factors that do impact on the quality of life. Rehabilitation has provided functional and aesthetic restorations, harmony of the stomatognathic system and improvement of life quality.

  13. Bulk-fill resin-based composite restorative materials: a review.

    PubMed

    Chesterman, J; Jowett, A; Gallacher, A; Nixon, P

    2017-03-10

    Resin-based composite (RBC) materials are increasingly being used for the restoration of posterior teeth. The increasing demand for aesthetic, tooth-coloured restorations coupled with the patient's concerns regarding the use of mercury containing restorations, has driven a surge in the use of RBC materials. With the Minamata Convention in 2013 calling for the phase-out of dental amalgam and dental schools increasingly teaching techniques for RBC restorations in posterior teeth, it is likely that the dental profession's reliance upon RBC for the restoration of posterior teeth will only increase. In order to simplify and speed-up the placement of large posterior RBCs, manufacturers have produced a range of materials which can be placed in single or deeper increments, known as bulk-fill RBCs. Over a relatively short period of time many bulk-fill RBCs have been marketed quoting increment depths between 4-10 mm. The placement of these larger increments of RBC may reduce the time needed when placing posterior restorations and thereby reduce technique sensitivity. This article aims to review the properties and handling characteristics of the bulk-fill RBC materials currently available, while advising the optimal techniques of placement.

  14. Effect of the lasers used in periodontal therapy on the surfaces of restorative materials.

    PubMed

    Hatipoğlu, Mükerrem; Barutcigil, Çağatay; Harorlı, Osman Tolga; Ulug, Bülent

    2016-05-01

    The present study aimed to reveal potential damage of the lasers, which are used as an alternative to manual instruments in periodontal therapy, might cause to the surface of restorative materials. Four different restorative materials were used: a glass-ionomer cement (GIC), a flowable composite (FC), a universal composite (UC) and an amalgam. Ten cylindrical samples (8 mm × 2 mm) were prepared for each restorative material. Two laser systems were used in subgingival curettage mode; an 940 nm diode laser (Epic Biolase, Irvine, CA) and an Er,Cr:YSGG laser (Waterlase iPlus, Biolase, Irvine, CA). After laser irradiation, roughness of the sample surfaces was measured using a profilometer. Additionally, atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses were performed to evaluate the morphology and surface deformations of the restorative materials and surfaces. The laser irradiation did not affect the surface roughness of any restorative materials relative to that of the control group (p > 0.05) except for the Er,Cr:YSGG treatment on GIC (p < 0.05). SEM and AFM images verified the results of the surface roughness tests. Within the limitations of the present study, it was demonstrated that Er,Cr:YSGG and diode lasers, aside from the Er;Cr:YSGG treatment on GIC, caused no harmful surface effects on adjacent restorative materials. SCANNING 38:227-233, 2016. © 2015 Wiley Periodicals, Inc.

  15. Bonding Durability of Four Adhesive Systems

    PubMed Central

    Seyed Tabai, Elaheh; Mohammadi Basir, Mahshid

    2015-01-01

    Objectives: This study aimed to compare the durability of four adhesive systems by assessing their microtensile bond strength (MTBS) and microleakage during six months of water storage. Materials and Methods: A total of 128 human third molars were used. The adhesives tested were Scotch Bond Multipurpose (SBMP), Single Bond (SB), Clearfil-SE bond (CSEB), and All-Bond SE (ABSE). After sample preparation for MTBS testing, the microspecimens were subjected to microtensile tester after one day and six months of water storage. For microleakage evaluation, facial and lingual class V cavities were prepared and restored with composite. After thermocycling, microleakage was evaluated. Bond strength values were subjected to one-way ANOVA and Tamhane’s test, and the microleakage data were analyzed by the Kruskal-Wallis, Dunn, Mann Whitney and Wilcoxon tests (P<0.05). Results: Single Bond yielded the highest and ABSE yielded the lowest bond strength at one day and six months. Short-term bond strength of SBMP and CSEB was similar. After six months, a significant decrease in bond strength was observed in ABSE and SBMP groups. At one day, ABSE showed the highest microleakage at the occlusal margin; however, at the gingival margin, there was no significant difference among groups. Long-term microleakage of all groups at the occlusal margins was similar, whilst gingival margins of SBMP and SB showed significantly higher microleakage. Conclusion: The highest MTBS and favorable sealability were obtained by Clearfil SE bond. Water storage had no effect on microleakage of self-etch adhesives at the gingival margin or MTBS of CSEB and SB. PMID:27123015

  16. Gill's 'History' restored

    NASA Astrophysics Data System (ADS)

    Hurn, Mark

    2009-06-01

    Note about the restoration of the copy of Sir David Gill's 'A History and Description of the Royal Observatory, Cape of Good Hope' in the Library of the Institute of Astronomy, Cambridge. The book was restored with funds provided by the SHA in thanks for facilities for meetings provided to the Institute.

  17. Guiding Restoration Principles

    DTIC Science & Technology

    2004-12-01

    restoration of important ecosystem functions requires reintegrating landscapes or restorating the func- tional aspects of landscapes ( Risser 1992...51-64. Risser , P. G. 1992. Landscape ecology approach to ecosystem rehabilitation. Pages 37-46 in M. L. Wali (ed.), Ecosystem Rehabilitation

  18. Utah Paiute Tribal Restoration.

    ERIC Educational Resources Information Center

    Turner, Allen C.

    The Paiute Indian Tribe of Utah Restoration Act (1980) restored federal recognition of the tribe after a quarter century of ambiguous political status, and resulted in significant improvements of educational status of tribal members and intensification of the political presence of Southern Paiutes. Following the Paiute Indian Termination Act…

  19. Power system restoration issues

    SciTech Connect

    Adibi, M.M. ); Kafka, R.J. )

    1991-04-01

    This article describes some of the problems encountered in the three phases of power system restoration (PSR). The three phases of PSR are: Planning for restart and reintegration of the bulk power supply; Actions during system degradation for saving and retaining critical sources of power; Restoration when the power system has stabilized at some degraded level.

  20. Retributive and restorative justice.

    PubMed

    Wenzel, Michael; Okimoto, Tyler G; Feather, Norman T; Platow, Michael J

    2008-10-01

    The emergence of restorative justice as an alternative model to Western, court-based criminal justice may have important implications for the psychology of justice. It is proposed that two different notions of justice affect responses to rule-breaking: restorative and retributive justice. Retributive justice essentially refers to the repair of justice through unilateral imposition of punishment, whereas restorative justice means the repair of justice through reaffirming a shared value-consensus in a bilateral process. Among the symbolic implications of transgressions, concerns about status and power are primarily related to retributive justice and concerns about shared values are primarily related to restorative justice. At the core of these processes, however, lies the parties' construal of their identity relation, specifically whether or not respondents perceive to share an identity with the offender. The specific case of intergroup transgressions is discussed, as are implications for future research on restoring a sense of justice after rule-breaking.

  1. Chlorhexidine preserves dentin bond in vitro.

    PubMed

    Carrilho, M R O; Carvalho, R M; de Goes, M F; di Hipólito, V; Geraldeli, S; Tay, F R; Pashley, D H; Tjäderhane, L

    2007-01-01

    Loss of hybrid layer integrity compromises resin-dentin bond stability. Matrix metalloproteinases (MMPs) may be partially responsible for hybrid layer degradation. Since chlorhexidine inhibits MMPs, we hypothesized that chlorhexidine would decelerate the loss of resin-dentin bonds. Class I preparations in extracted third molars were sectioned into two halves. One half was customarily restored (etch-and-rinse adhesive/resin composite), and the other was treated with 2% chlorhexidine after being acid-etched before restoration. Specimens were stored in artificial saliva with/without protease inhibitors. Microtensile bond strengths and failure mode distribution under SEM were analyzed immediately after specimens' preparation and 6 months later. With chlorhexidine, significantly better preservation of bond strength was observed after 6 months; protease inhibitors in the storage medium had no effect. Failure analysis showed significantly less failure in the hybrid layer with chlorhexidine, compared with controls after 6 months. In conclusion, this in vitro study suggests that chlorhexidine might be useful for the preservation of dentin bond strength.

  2. Bond strength of composite resin to pulp capping biomaterials after application of three different bonding systems.

    PubMed

    Jaberi-Ansari, Zahra; Mahdilou, Maryam; Ahmadyar, Maryam; Asgary, Saeed

    2013-01-01

    Background and aims. Bonding of composite resin filling materials to pulp protecting agents produces an adhesive joint which is important for the quality of filling as well as success of restoration. We aimed to assess the bond strength of composite resin to three pulp capping biomaterials: Pro Root mineral trioxide aggregate (PMTA), Root MTA (RMTA) and calcium enriched mixture (CEM) cement, using three bonding systems [a total-etch (Single Bond) and two self-etch systems (Protect bond and SE Bond)]. Materials and methods. Ninety acrylic molds, each containing a 6×2-mm hole, were divided into 3 groups and filled with PMTA, RMTA and CEM cements. The samples in each experimental group were then randomly divided into 3 sub-groups; Single Bond, Protect Bond and SE Bond bonding systems were applied to the tested materials. Cylindrical forms of composite resin (Z100, 2×2 mm) were placed onto the samples and cured. Shear bond strength values were measured for 9 subgroups using a universal testing machine. Data were analyzed using two-way ANOVA. Results. The average shear bond strengths of Z100 composite resin after application of Single Bond, Protect Bond and SE Bond systems were as follows; PMTA: 5.1±2.42, 4.56±1.96 and 4.52±1.7; RMTA: 4.71±1.77, 4.31±0.56 and 4.79±1.88; and CEM cement: 4.75±1.1, 4.54±1.59 and 4.64±1.78 MPa, respectively. The type of pulp capping material, bonding system and their interacting effects did not have a significant effect on the bond strengths of composite resin to pulp capping biomaterials. Conclusion. Within the limitations of this in vitrostudy, bond strength of composite resin to two types of MTA as well as CEM cement were similar following application of the total-etch or self-etch bonding systems.

  3. Bond Strength of Composite Resin to Pulp Capping Biomaterials after Application of Three Different Bonding Systems

    PubMed Central

    Jaberi-Ansari, Zahra; Mahdilou, Maryam; Ahmadyar, Maryam; Asgary, Saeed

    2013-01-01

    Background and aims. Bonding of composite resin filling materials to pulp protecting agents produces an adhesive joint which is important for the quality of filling as well as success of restoration. We aimed to assess the bond strength of composite resin to three pulp capping biomaterials: Pro Root mineral trioxide aggregate (PMTA), Root MTA (RMTA) and calcium enriched mixture (CEM) cement, using three bonding systems [a total-etch (Single Bond) and two self-etch systems (Protect bond and SE Bond)]. Materials and methods. Ninety acrylic molds, each containing a 6×2-mm hole, were divided into 3 groups and filled with PMTA, RMTA and CEM cements. The samples in each experimental group were then randomly divided into 3 sub-groups; Single Bond, Protect Bond and SE Bond bonding systems were applied to the tested materials. Cylindrical forms of composite resin (Z100, 2×2 mm) were placed onto the samples and cured. Shear bond strength values were measured for 9 subgroups using a universal testing machine. Data were analyzed using two-way ANOVA. Results. The average shear bond strengths of Z100 composite resin after application of Single Bond, Protect Bond and SE Bond systems were as follows; PMTA: 5.1±2.42, 4.56±1.96 and 4.52±1.7; RMTA: 4.71±1.77, 4.31±0.56 and 4.79±1.88; and CEM cement: 4.75±1.1, 4.54±1.59 and 4.64±1.78 MPa, respectively. The type of pulp capping material, bonding system and their interacting effects did not have a significant effect on the bond strengths of composite resin to pulp capping biomaterials. Conclusion. Within the limitations of this in vitrostudy, bond strength of composite resin to two types of MTA as well as CEM cement were similar following application of the total-etch or self-etch bonding systems. PMID:24082986

  4. Biological mercury measurements before and after administration of a chelator (DMPS) and subjective symptoms allegedly due to amalgam.

    PubMed

    Schuurs, A; Exterkate, R; ten Cate, J M; ten Cate, B

    2000-12-01

    The aim of the study was to explore multivariately the relationship between subjective symptoms allegedly due to amalgam and mercury measurements before and after administration of a chelator. Of 120 participants, the mercury concentrations in urine (U-Hg) and plasma (P-Hg) before and after a chelating agent or placebo were determined as were the numbers of fillings and symptoms allegedly due to subjective symptoms. The dental status was charted. Blood was analysed on 13 parameters. The analysis revealed neither the parameters in blood nor the subjective symptoms to be associated with a dimension dominated by 'mercury indicators'. The final analysis was therefore performed with 'number of subjective symptoms' and enabled to distinguish two subsamples. One subsample was characterised by > 2 subjective "symptoms", highest scores for U-Hg, P-Hg and filled surfaces, and chewing gum for > 1 h a day. The other subsample comprised the subjects with few filled surfaces and low U-Hg and P-Hg, but was not characterised by "no subjective symptoms". The chelator was considered neither to invalidate nor to improve these findings and was concluded not to be helpful in diagnosing "symptoms". The chelator caused side effects in 42% of the subjects and the placebo in 27%. A relationship between amalgam fillings and subjective symptoms could not be shown. Therefore, the mere fact of knowing to have amalgam fillings was assumed to be the reason why subjective symptoms were attributed to amalgam and side effects were ascribed to the treatment.

  5. Mercury contamination - Amalgamate (contract with NFS and ADA). Stabilize Elemental Mercury Wastes. Mixed Waste Focus Area. OST Reference Number 1675

    SciTech Connect

    None, None

    1999-09-01

    Through efforts led by the Mixed Waste Focus Area (MWFA) and its Mercury Working Group (HgWG), the inventory of bulk elemental mercury contaminated with radionuclides stored at various U. S. Department of Energy (DOE) sites is thought to be approximately 16 m3 (Conley et al. 1998). At least 19 different DOE sites have this type of mixed low-level waste in their storage facilities. The U. S. Environmental Protection Agency (EPA) specifies amalgamation as the treatment method for radioactively contaminated elemental mercury. Although the chemistry of amalgamation is well known, the practical engineering of a sizable amalgamation process has not been tested (Tyson 1993). To eliminate the existing DOE inventory in a reasonable timeframe, scaleable equipment is needed that can: produce waste forms that meet the EPA definition of amalgamation, produce waste forms that pass the EPA Toxicity Characteristic Leaching Procedure (TCLP) limit of 0.20 mg/L, limit mercury vapor concentrations during processing to below the Occupational Safety and Health Administration’s (OSHA) 8-hour worker exposure limit (50 mg/m3) for mercury, and perform the above economically.

  6. The Minamata Convention on Mercury: attempting to address the global controversy of dental amalgam use and mercury waste disposal.

    PubMed

    Mackey, Tim K; Contreras, John T; Liang, Bryan A

    2014-02-15

    In October 2013, a new international binding treaty instrument called the Minamata Convention on Mercury opened for signature in Minamata City, Japan, the site of arguably the worst public health and environmental disaster involving mercury contamination. The treaty aims to curb the significant health and environmental impacts of mercury pollution and includes provisions addressing the mining, export and import, storage, and waste management of products containing mercury. Importantly, a provision heavily negotiated in the treaty addresses the use of dental fillings using mercury amalgam, an issue that has been subject to decades of global controversy. Though use of dental amalgam is widespread and has benefits, concerns have been raised regarding the potential for human health risk and environmental damage from emissions and improper waste management. While the Minamata Convention attempts to address these issues by calling for a voluntary phase-down of dental amalgam use and commitment to other measures, it falls short by failing to require binding and measurable targets to achieve these goals. In response, the international community should begin exploring ways to strengthen the implementation of the dental amalgam treaty provisions by establishing binding phase-down targets and milestones as well as exploring financing mechanisms to support treaty measures. Through strengthening of the Convention, stakeholders can ensure equitable access to global oral health treatment while also promoting responsible environmental stewardship.

  7. Assessing ex vivo dental biofilms and in vivo composite restorations using cross-polarization optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Jones, R.; Aparicio, C.; Chityala, R.; Chen, R.; Fok, A.; Rudney, J.

    2012-01-01

    A cross-polarization 1310-nm optical coherence tomography system (CP-OCT), using a beam splitter based design, was used to assess ex vivo growth of complex multi-species dental biofilms. These biofilm microcosms were derived from plaque samples along the interface of composite or amalgam restoration in children with a history of early childhood caries. This paper presents a method of measuring the mean biofilm height of mature biofilms using CP-OCT. For our in vivo application, the novel swept source based CP-OCT intraoral probe (Santec Co. Komaki, Japan) dimensions and system image acquisition speed (20 image frames/second) allowed imaging pediatric subjects as young as 4 years old. The subsurface enamel under the interface of composite resin restorations of pediatric subjects were imaged using CP-OCT. Cavitated secondary caries is clearly evident from sound resin composite restorations.

  8. Brood amalgamation in the Bristle-thighed Curlew Numenius tahitiensis: process and function

    USGS Publications Warehouse

    Lanctot, Richard B.; Gill, R.E.; Tibbitts, T.L.; Handel, C.M.

    1995-01-01

    Alloparental care in birds generally involves nonbreeding adults that help at nests or breeding adults that help raise young in communal nests. A less often reported form involves the amalgamation of broods, where one or more adults care for young that are not their own. We observed this phenomenon among Bristle-thighed Curlew Numenius tahitiensis broods in western Alaska during 1990–1992. Amalgamation of broods generally involved the formation of temporary and extended associations. Temporary associations were formed by the incidental convergence of broods soon after they left their nests. During this period, parents defended distinct brood-rearing areas, were antagonistic to conspecifics and remained together for less than 3 days. Extended associations formed when chicks were 1–2 weeks old. Here, parents and their broods occupied distinct, but adjacent, brood-rearing areas and moved around as a unit. Whether a brood participated in either temporary or extended associations or remained solitary appeared to depend on brood density in the immediate area and on hatching date. When chicks were 3–4 weeks old, aggregations of up to ten broods formed wherein young mixed and parents defended a common brood-rearing area. All broods (n = 48) that survived to fledging joined such aggregations. Alloparental care involved only antipredator defence and was not associated with activities such as feeding and brooding. Most female parents abandoned their broods shortly after the young could fly and when aggregations were forming. The female parent of a pair always deserted its young before or on the same day as the male parent and, in every aggregation, one or two males continued to tend young for about 5 days longer than other male parents. In most cases, adults deserted the young 2–6 days before the young departed the area when about 38 days old. Bristle-thighed Curlews also formed temporary associations with American and Pacific Golden Plover Pluvialis dominica and

  9. Using Multiple Bonding Strategies.

    PubMed

    Larson, Thomas D

    2015-01-01

    There are many ways to bond to tooth structure, some micro-mechanical some chemical, some a combination. Different dentin bonding materials have different bonding strengths to differently prepared surfaces, and because of differences in their nature, different areas of tooth structure present peculiar bonding challenges. This paper will review a variety of material types, elucidating their particular bonding strengths and commenting on improved bonding strategies to increase durability, strength, and favorable pulpal response. In this discussion, resin dentin bonding systems, glass ionomers, Gluma, resin cements, and newer combined products will br reviewed.

  10. Bearing restoration by grinding

    NASA Technical Reports Server (NTRS)

    Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.

    1976-01-01

    A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No bearing failures occurred related to the restoration by grinding process. The risk and cost of a bearing restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.

  11. Effect of Restorative System and Thermal Cycling on the Tooth-Restoration Interface - OCT Evaluation.

    PubMed

    Sampaio, C S; Rodrigues, R V; Souza-Junior, E J; Freitas, A Z; Ambrosano, G M B; Pascon, F M; Puppin-Rontani, R M

    2016-01-01

    The present study evaluated the tooth/noncarious cervical lesion restoration interface when using different adhesive systems and resin composites, submitted to thermal cycling (TC), using optical coherence tomography (OCT). Noncarious cervical lesion (NCCL) preparations (0.7 mm depth × 2 mm diameter) were performed on 60 human third molars and randomly divided into six groups, according to the adhesive system and resin composite used: group 1 = Adper Single Bond 2 (SB2) + Aelite LS Posterior (AP); group 2 = SB2 + Venus Diamond (VD); group = SB2 + Filtek Z250XT (Z250); group 4 = Clearfil SE Bond (CSE) + AP; group 5 = CSE + VD; group 6 = CSE + Z250. Selective enamel etching was performed for 30 seconds on groups 4, 5, and 6, while groups 1, 2, and 3 were etched for 30 seconds in enamel and 15 seconds in dentin. All groups were evaluated using OCT before and after TC (n=10). Images were analyzed using Image J software; enamel and dentin margins were separately evaluated. Data from OCT were submitted to PROC MIXED for repeated measurements and Tukey Kramer test (α = 0.05). No marginal gaps were observed in etched enamel, either before or after TC, for all adhesive and resin composite systems. A significant interaction was found between adhesive system and TC for the dentin groups; after TC, restorations with CSE showed smaller gaps at the dentin/restoration interface compared with SB2 for all resin composites. Increased gap percentages were noticed after TC compared with the gaps before TC for all groups. In conclusion, TC affected marginal integrity only in dentin margins, whereas etched enamel margins remained stable even after TC. Dentin margins restored with CSE adhesive system showed better marginal adaptation than those restored with SB2. Resin composites did not influence marginal integrity of NCCL restorations.

  12. Principles of Wetland Restoration

    EPA Pesticide Factsheets

    the return of a degraded ecosystem to a close approximation of its remaining natural potential - is experiencing a groundswell of support across the United States. The number of stream, river, lake, wetland and estuary restoration projects grows yearly

  13. Ecosystem restoration: Chapter 4

    USGS Publications Warehouse

    Cullinane Thomas, Catherine M.; Skrabis, K. E.; Gascoigne, William

    2012-01-01

    The Department of the Interior extensively supports―through its mission, policy, programs, and funding― the study, planning, implementation, and monitoring of ecosystem restoration. This commitment is reflected in the Department's FY2011-2016 Strategic Plan.

  14. The Menominee Restoration Act

    ERIC Educational Resources Information Center

    Deer, Ada E.

    1973-01-01

    The article discusses the background and current status of the Menominee Restoration Bill, which will reverse the termination of Federal responsibility effected on the Wisconsin Menominee Tribe in 1961. (KM)

  15. ESTUARINE HABITAT RESTORATION

    SciTech Connect

    Thom, Ronald M.; Borde, Amy B.

    2015-09-01

    Restoring estuarine habitats generally means repairing damages caused by humans and natural forces. Because of the extensive human occupation, development, and use of coastal areas for centuries, the extensive estuarine habitats have been either destroyed or significantly impaired.

  16. Restoration of Ailing Wetlands

    PubMed Central

    Schmitz, Oswald J.

    2012-01-01

    It is widely held that humankind's destructive tendencies when exploiting natural resources leads to irreparable harm to the environment. Yet, this thinking runs counter to evidence that many ecological systems damaged by severe natural environmental disturbances (e.g., hurricanes) can restore themselves via processes of natural recovery. The emerging field of restoration ecology is capitalizing on the natural restorative tendencies of ecological systems to build a science of repairing the harm inflicted by humans on natural environment. Evidence for this, for example, comes from a new meta-analysis of 124 studies that synthesizes recovery of impacted wetlands worldwide. While it may take up to two human generations to see full recovery, there is promise, given human will, to restore many damaged wetlands worldwide. PMID:22291573

  17. AunHgm Clusters: Mercury Aurides, Gold Amalgams, or van der Waals Aggregates?

    NASA Astrophysics Data System (ADS)

    Zaleski-Ejgierd, Patryk; Pyykkö, Pekka

    2009-02-01

    The class of bimetallic clusters, AunMm (M = Zn, Cd, Hg), is calculated at the ab initio level using the DFT, RI-MP2, and CCSD(T) methods. For the triatomic Au2M (M = Zn, Cd), the auride-type linear Au-M-Au structures are preferred; for Au2Hg, the linear Au-Au-Hg "amalgam" is preferred. The mixed cation [HgAuHg]+, an analog of the known solid-state species Hg32+, is predicted. For larger AunHgm clusters, the results are similar to the isoelectronic AunM- anions. Several local minima and transition states are identified. All are found to be planar.

  18. A Mediterranean-style model for early Neoproterozoic amalgamation of South China

    NASA Astrophysics Data System (ADS)

    Zhang, Kai-Jun

    2017-04-01

    A Mediterranean-style model is proposed for early Neoproterozoic amalgamation of South China, based on recognition of the Guangxi promontory on the southeastern margin of the Yangtze craton through a synthesis of geologic, geophysical and chronological data. The model suggests that, while the Guangxi promontory collided with the overriding Cathaysia terrane along the Yunkai orogeny during the earliest Neoproterozoic, the convergence between the Yangtze craton and the Cathaysia terrane paused or slowed down, which triggered the upper Rhine Graben-style Kangdian impact rift along the western Yangtze margin and resulted in roll-back of the oceanic slab trapped in the embayments and sequential formation of backarc rifts in the Cathaysia margin during the early Neoproterozoic. This model predicts a complex diachronous Yangtze-Cathaysia collision history, first at the Guangxi promontory at ∼1000 Ma and finally at the Guizhou reentrant at ∼830 Ma.

  19. Design, synthesis, characterization and anti-inflammatory evaluation of novel pyrazole amalgamated flavones.

    PubMed

    Chavan, Hemant V; Bandgar, Babasaheb P; Adsul, Laxman K; Dhakane, Valmik D; Bhale, Pravin S; Thakare, Vishnu N; Masand, Vijay

    2013-03-01

    A series of novel pyrazole amalgamated flavones has been designed and synthesized from 1-methyl-5-(2,4,6-trimethoxy-phenyl)-1H-pyrazole 6. The structures of regioisomers 6 and 7 were resolved by 2D (1)H-(1)H COSY, (1)H-(13)C HSQC and (1)H-(13)C HMBC experiments. The newly synthesized compounds were tested for their in vitro COX inhibition and in vivo carrageenan induced hind paw edema in rats and acetic acid induced vascular permeability in mice. Although the compounds have inhibitory profile against both COX-1 and COX-2, some of the compounds are found to be selective against COX-2, supported by inhibition of paw edema and vascular permeability. Docking studies were also carried out to determine the structural features which sway the anti-inflammatory activity of the tested compounds. The keto and phenolic -OH are major factors that are prominently involved in interaction with COX-2 active site.

  20. How to bond to root canal dentin

    NASA Astrophysics Data System (ADS)

    Nica, Luminita; Todea, Carmen; Furtos, Gabriel; Baldea, Bogdan

    2014-01-01

    Bonding to root canal dentin may be difficult due to various factors: the structural characteristic of the root canal dentin, which is different from that of the coronal dentin; the presence of the organic tissue of the dental pulp inside the root canal, which has to be removed during the cleaning-shaping of the root canal system; the smear-layer resulted after mechanical instrumentation, which may interfere with the adhesion of the filling materials; the type of the irrigants used in the cleaning protocol; the type of the sealer and core material used in the obturation of the endodontic space; the type of the materials used for the restoration of the endodontically treated teeth. The influence of the cleaning protocol, of the root canal filling material, of the type of the adhesive system used in the restoration of the treated teeth and of the region of the root canal, on the adhesion of several filling and restorative materials to root canal dentin was evaluated in the push-out bond strength test on 1-mm thick slices of endodontically treated human teeth. The results showed that all these factors have a statistically significant influence on the push-out bond strength. Formation of resin tags between radicular dentin and the investigated materials was observed in some of the samples at SEM analysis.

  1. Preformed resin-veneered stainless steel crowns for restoration of primary incisors.

    PubMed

    Croll, T P; Helpin, M L

    1996-05-01

    Stainless steel crown forms with bonded resin veneers for primary incisors are commercially available to dentists. This type of preveneered crown was developed to serve as a convenient, durable, reliable, and esthetic solution to the difficult challenge of restoring severely carious primary incisors. This article describes preveneered crowns, reviews their advantages and disadvantages, and details a technique for placement of such restorations.

  2. Dental clinics: a point pollution source, not only of mercury but also of other amalgam constituents.

    PubMed

    Shraim, Amjad; Alsuhaimi, Awadh; Al-Thakafy, Jalal Thamer

    2011-08-01

    Current literature suggests that amalgam waste from dental clinics is a point-source of mercury pollution in the environment. However, apart from mercury, other amalgam constituents (e.g. Ag, Sn, Cu, and Zn) in dental clinics' wastewater have not been reported in the literature before. The objective of this study was to evaluate the concentrations of mercury and other metals in the wastewater of some dental clinics and the influent of a wastewater treatment plant in Al-Madinah Al-Munawarah (KSA). Samples were collected over a 2-month period from three dental clinics and analyzed for metals using ICP-MS. The mean concentrations of Hg, Ag, Sn, Cu, and Zn in the samples were 5.3±11.1, 0.49±0.96, 3.0±10.7, 10.0±14.5, and 76.7±106 mg L(-1), respectively. Additionally, high concentrations of other metals such as Mg (14.4±15.2 mg L(-1)), Mn (3.0±4.6 mg L(-1)), Fe (3.0±4.5 mg L(-1)), Sr (1.6±2.4 mg L(-1)), and Ba (6.9±10.3 mg L(-1)) were also found. These values are much higher than the local permissible limits. Most of the metals of interest were also detected in the influent of the wastewater treatment plant. This renders dental clinics wastewater a hazardous waste which should be properly treated before it is discharged into the environment.

  3. Bond Strength of 5th, 6th and 7th Generation Bonding Agents to Intracanal Dentin of Primary Teeth

    PubMed Central

    Afshar, Hossein; Baradaran Nakhjavani, Yahya; Rahro Taban, Sedighe; Baniameri, Zahra; Nahvi, Azam

    2015-01-01

    Objectives: This in-vitro study sought to assess the push-out bond strength of a total etch and 2 self-etch bonding systems to intracanal dentin of primary anterior teeth (PAT). Materials and Methods: Thirty-six primary anterior teeth were randomly divided into 3 groups of 5th generation (Single Bond 2), 6th generation (Clearfil SE) and 7th generation (Single Bond Universal) bonding agents. The canal orifice was restored with composite resin and the push-out test was carried out to assess the bond strength. After applying the push-out load, specimens were evaluated under a light microscope at 40X magnification. One-way ANOVA and log-rank test on Kaplan-Meier curves were applied for the comparison of bond strength among the 3 groups. Results: The mean± standard deviation (SD) bond strength was 13.6±5.33 MPa for Single Bond 2, 13.85±5.86 MPa for Clearfil SE and 12.28±5.24 MPa for Single Bond Universal. The differences in bond strength among the 3 groups were not statistically significant (P>0.05). Conclusion: All three bonding agents are recommended for use with composite posts in PAT. However, due to high technical sensitivity of the Total Etch system, single or two-step self etch systems may be preferred for uncooperative children. PMID:26056518

  4. Preventing postoperative tooth sensitivity in class I, II and V restorations.

    PubMed

    Christensen, Gordon J

    2002-02-01

    Postoperative tooth sensitivity in Class I, II and V resin-based composite restorations continues to be an unpredictable problem in dentistry. In spite of meticulous use of dentin bonding agents, dentists and patients are faced with the sensitivity problem and the frustrating need to remove restorations and occasionally accomplish endodontic therapy on teeth that were not sensitive before the restorations were placed. Practitioners have developed numerous preventive methods to overcome the sensitivity challenge, which I have described in this article.

  5. A study of composite restorations as a tool in forensic identification

    PubMed Central

    Hemasathya, Bahavathi Ananthan; Balagopal, Sundaresan

    2013-01-01

    Introduction: Comparing ante-mortem and post-mortem dental data is a principal method of identification in forensic odontology. Radiographic images of amalgam have been used in dental forensics for identification due to their unique appearance. Aim: The aim of this study was to investigate whether radio-opaque composite restorations have a potential for identification in forensic odontology. Materials and Methods: Thirty typodont mandibular first molar teeth were prepared with Class-II (proximo-occlusal) cavities and restored with a radio-opaque composite (Tetric N-Ceram). Two sets of standardized radiographs were taken from the 30 teeth, keeping the radiological parameters constant. One set of these 30 radiographs was named as SET 1. Ten randomly chosen radiographs from the other set and two other radiographs of Class-II composite restorations in typodont teeth constituted SET 2. Thirty dentally trained examiners were asked to match the 12 radiographic images of SET 2 with those of SET 1. Results: The results show that 15 examiners were able to correctly match all the 12 images. Statistical analysis was done using kappa statistical test. Conclusion: This study shows that, if the post-mortem radiographs are accurate duplicates of ante-mortem radiographs of composite restorations, then the shape of the composite restoration is unique and can be used for identification. PMID:23960413

  6. A randomized clinical trial evaluating the success rate of ethanol wet bonding technique and two adhesives

    PubMed Central

    Mortazavi, Vajihesadat; Samimi, Pouran; Rafizadeh, Mojgan; Kazemi, Shantia

    2012-01-01

    Background: Composite resin restorations may have a short lifespan due to the degradation of resin–dentin interface. Ethanol wet bonding technique may extend the longevity of resin–dentin bond. The purpose of this one year randomized clinical trial was to compare clinical performance of two adhesives with ethanol wet bonding technique. Materials and Methods: This randomized clinical trial was performed on 36 non-carious cervical lesions in 12 patients restored with composite resin using one of the following approaches: 1. OptiBond FL (Kerr, USA); 2. Clearfil SE Bond (Kuraray, Japan) with enamel etching and 3. Ethanol wet bonding technique with the part of adhesive of OptiBond FL. The clinical success rate was assessed after 24 h, 6, 9 and 12 months according to the United States Public Health Service (USPHS) criteria: Marginal discoloration, marginal defect, retention rate, caries occurrence, and postoperative sensitivity. The tooth vitality was also assessed. Results: The retention rate was 100% at baseline and at 6 months follow up for all types of bonding protocols and was 91.67% at 9 and 12 months follow up for ethanol wet bonding group. None of the restorations in three groups showed marginal defects, marginal discoloration or caries occurrence and were vital after 12 months. There was no statistically significant difference between three groups after 12 months follow up (p value = 0.358). Conclusions: Composite restorations placed using ethanol wet bonding technique presented equal performance to the other groups. PMID:23559924

  7. A quantitative method of measuring the microleakage of thermocycled or non-thermocycled posterior tooth restorations.

    PubMed

    Aguiar, Flávio Henrique Baggio; Dos Santos, Alex José Souza; França, Fabiana Mantovani Gomes; Paulillo, Luis Alexandre Maffei Sartini; Lovadino, José Roberto

    2003-01-01

    This study quantified microleakage in restorations made with three packable resin composites-Solitaire, SureFil and P60; one hybrid resin composite-Z250 and an amalgam-Dispersalloy, with or without the thermocycling process. Sixty sound, freshly extracted human molars were sectioned mesiodistally, creating buccal and lingual blocks. One hundred blocks with the flattest surface were selected. Cylindrical cavities with a diameter of 1.85 +/- 0.05 mm and a depth of 1.5 mm were prepared with a special diamond bur. The blocks were randomly assigned to 10 test groups (n = 10): five restorative materials and two thermal stress groups (thermocycled groups at 3,000 cycles at 5 degrees C and 55 degrees C with a dwell time of one minute at each temperature, or non-thermocycled). After the thermocycling test, the samples were immersed in 2% methylene blue for 12 hours. The samples were ground and the powder prepared for analysis in an absorbance spectrophotometer. All the results were statistically analyzed by the Kruskal-Wallis test and the Mann Whitney test. For the non-thermocycled groups, the means (microg/ml) of microleakage were: Amalgam-4.279 (a); Solitaire-4.148 (ab); Z250-3.418 (abc); P60-3.184 (bc); SureFil-2.890 (c). For the thermocycled groups, the means were: Amalgam-7.572 (a); Solitaire-5.471 (a); Z250-4.330 (ab); P60-3.418 (bc) and SureFil-2.779 (c). Thermocycling analysis showed no significant differences between the thermocycled and non-thermocycled groups for each material tested. It was concluded that no test material prevented microleakage. Only SureFil and P60 showed leakage means significantly lower than amalgam, with SureFil showing lower leakage than Solitaire. P60 only showed lower leakage than Solitaire in the thermocycled groups and Z250 showed results similar to the others materials.

  8. Hydroxide-catalyzed bonding

    NASA Technical Reports Server (NTRS)

    Gwo, Dz-Hung (Inventor)

    2003-01-01

    A method of bonding substrates by hydroxide-catalyzed hydration/dehydration involves applying a bonding material to at least one surface to be bonded, and placing the at least one surface sufficiently close to another surface such that a bonding interface is formed between them. A bonding material of the invention comprises a source of hydroxide ions, and may optionally include a silicate component, a particulate filling material, and a property-modifying component. Bonding methods of the invention reliably and reproducibly provide bonds which are strong and precise, and which may be tailored according to a wide range of possible applications. Possible applications for bonding materials of the invention include: forming composite materials, coating substrates, forming laminate structures, assembly of precision optical components, and preparing objects of defined geometry and composition. Bonding materials and methods of preparing the same are also disclosed.

  9. An in vitro comparative SEM study of marginal adaptation of IRM, light- and chemically-cured glass ionomer, and amalgam in furcation perforations.

    PubMed

    Rajablou, N; Azimi, S

    2001-12-01

    The furcation regions of 30 human mandibular molars were perforated and sealed using four different materials: IRM, light- and chemically-cured glass ionomer cement (GIC), and amalgam. The materials were compared for marginal gaps in coronal, mid, and apical regions after routine SEM processing. While light-cured GIC showed the smallest gaps in the three regions, in mid and coronal regions chemically-cured GIC, and in apical regions amalgam, showed the largest gaps. IRM cases showed the highest rate of fillings with a good "fit", whereas the majority of amalgam cases and none of the chemically-cured GIC cases were overfilled.

  10. Failure Rate of Direct High-Viscosity Glass-Ionomer Versus Hybrid Resin Composite Restorations in Posterior Permanent Teeth - a Systematic Review

    PubMed Central

    Mickenautsch, Steffen; Yengopal, Veerasamy

    2015-01-01

    Purpose Traditionally, resin composite restorations are claimed by reviews of the dental literature as being superior to glass-ionomer fillings in terms of restoration failures in posterior permanent teeth. The aim of this systematic review is to answer the clinical question, whether conventional high-viscosity glass-ionomer restorations, in patients with single and/or multi-surface cavities in posterior permanent teeth, have indeed a higher failure rate than direct hybrid resin composite restorations. Methods Eight databases were searched until December 02, 2013. Trials were assessed for bias risks, in-between datasets heterogeneity and statistical sample size power. Effects sizes were computed and statistically compared. A total of 55 citations were identified through systematic literature search. From these, 46 were excluded. No trials related to high-viscosity glass-ionomers versus resin composite restorations for direct head-to-head comparison were found. Three trials related to high-viscosity glass-ionomers versus amalgam and three trials related to resin composite versus amalgam restorations could be included for adjusted indirect comparison, only. Results The available evidence suggests no difference in the failure rates between both types of restoration beyond the play of chance, is limited by lack of head-to-head comparisons and an insufficient number of trials, as well as by high bias and in-between-dataset heterogeneity risk. The current clinical evidence needs to be regarded as too poor in order to justify superiority claims regarding the failure rates of both restoration types. Sufficiently large-sized, parallel-group, randomised control trials with high internal validity are needed, in order to justify any clinically meaningful judgment to this topic. PMID:26962372

  11. Resin cementation of zirconia ceramics with different bonding agents.

    PubMed

    Tanış, Merve Çakırbay; Akay, Canan; Karakış, Duygu

    2015-03-04

    The aim of this study was to evaluate the effects of sandblasting and different chemical bonding agents on shear bond strength of zirconia and conventional resin cement. In this study, 35 zirconia specimens were treated as follows: Group I: control; Group II: sandblasting; Group III: sandblasting + Monobond S; Group IV: sandblasting + Monobond Plus; Group V: sandblasting + Z-Prime Plus. The specimens in each group were bonded with conventional composite resin cement Variolink II. After cementation, specimens were stored in distilled water (at 37 °C) for 24 h and shear test was performed. The highest shear bond strength values were observed in Groups IV and V. The lowest shear bond strength values were observed in Group I. Using 10-methacryloyloxy-decyl dihydrogenphosphate monomer-containing priming agents, e.g. Monobond Plus and Z-PRIME Plus, combined with sandblasting can be an effective method for resin bonding of zirconia restorations.

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

    PubMed Central

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

    2014-01-01

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

  13. Resin cementation of zirconia ceramics with different bonding agents

    PubMed Central

    Tanış, Merve Çakırbay; Akay, Canan; Karakış, Duygu

    2015-01-01

    The aim of this study was to evaluate the effects of sandblasting and different chemical bonding agents on shear bond strength of zirconia and conventional resin cement. In this study, 35 zirconia specimens were treated as follows: Group I: control; Group II: sandblasting; Group III: sandblasting + Monobond S; Group IV: sandblasting + Monobond Plus; Group V: sandblasting + Z-Prime Plus. The specimens in each group were bonded with conventional composite resin cement Variolink II. After cementation, specimens were stored in distilled water (at 37 °C) for 24 h and shear test was performed. The highest shear bond strength values were observed in Groups IV and V. The lowest shear bond strength values were observed in Group I. Using 10-methacryloyloxy-decyl dihydrogenphosphate monomer-containing priming agents, e.g. Monobond Plus and Z-PRIME Plus, combined with sandblasting can be an effective method for resin bonding of zirconia restorations. PMID:26019653

  14. 48 CFR 228.102-70 - Defense Environmental Restoration Program construction contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 3 2011-10-01 2011-10-01 false Defense Environmental... System DEFENSE ACQUISITION REGULATIONS SYSTEM, DEPARTMENT OF DEFENSE GENERAL CONTRACTING REQUIREMENTS BONDS AND INSURANCE Bonds 228.102-70 Defense Environmental Restoration Program construction...

  15. 48 CFR 228.102-70 - Defense Environmental Restoration Program construction contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 3 2012-10-01 2012-10-01 false Defense Environmental... System DEFENSE ACQUISITION REGULATIONS SYSTEM, DEPARTMENT OF DEFENSE GENERAL CONTRACTING REQUIREMENTS BONDS AND INSURANCE Bonds 228.102-70 Defense Environmental Restoration Program construction...

  16. 48 CFR 228.102-70 - Defense Environmental Restoration Program construction contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Defense Environmental... System DEFENSE ACQUISITION REGULATIONS SYSTEM, DEPARTMENT OF DEFENSE GENERAL CONTRACTING REQUIREMENTS BONDS AND INSURANCE Bonds 228.102-70 Defense Environmental Restoration Program construction...

  17. 48 CFR 228.102-70 - Defense Environmental Restoration Program construction contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 3 2013-10-01 2013-10-01 false Defense Environmental... System DEFENSE ACQUISITION REGULATIONS SYSTEM, DEPARTMENT OF DEFENSE GENERAL CONTRACTING REQUIREMENTS BONDS AND INSURANCE Bonds 228.102-70 Defense Environmental Restoration Program construction...

  18. 48 CFR 228.102-70 - Defense Environmental Restoration Program construction contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 3 2014-10-01 2014-10-01 false Defense Environmental... System DEFENSE ACQUISITION REGULATIONS SYSTEM, DEPARTMENT OF DEFENSE GENERAL CONTRACTING REQUIREMENTS BONDS AND INSURANCE Bonds 228.102-70 Defense Environmental Restoration Program construction...

  19. The effect of repeated bonding on the shear bond strength of different resin cements to enamel and dentin

    PubMed Central

    Atsü, Saadet Sağlam

    2017-01-01

    PURPOSE Cementation failures of restorations are frequently observed in clinical practice. The purpose of this study is to compare the effect of initial and repeated bonding on the bond strengths of different resin cements to enamel and dentin. MATERIALS AND METHODS Ninety human maxillary central incisors were bisected longitudinally. The 180 tooth halves were divided into 2 groups (n = 90) for enamel and dentin bonding. The enamel and dentin groups were further divided into 3 groups (n = 30) for different resin cement types. Composite resin (Filtek Ultimate) cylinders (3 × 3 mm) were prepared and luted to enamel and dentin using Variolink II (Group V), RelyX ARC (Group R), or Panavia F 2.0 (Group P) resin cement. After 24 hours, initial shear bond strengths of the resin cements to enamel and dentin were measured. Using new cylinders, the specimens were de-bonded and re-bonded twice to measure the first and the second bond strengths to enamel and dentin. Failure modes and bonding interfaces were examined. Data were statistically analyzed. RESULTS Initial and repeated bond strengths to enamel were similar for all the groups. The first (15.3 ± 2.2 MPa) and second (10.4 ± 2.2 MPa) bond strengths to dentin were significantly higher in Group V (P<.0001). Second bond strengths of dentin groups were significantly lower than initial and first bond strengths to dentin (P<.0001). CONCLUSION All resin cements have similar initial and repeated bond strengths to enamel. Variolink II has the highest first and second bond strength to dentin. Bond strength to dentin decreases after the first re-bonding for all resin cements. PMID:28243393

  20. Effect of prebonding procedures on shear bond strength of resin composite to pressable ceramic.

    PubMed

    Estafan, D; Dussetschleger, F; Estafan, A; Jia, W

    2000-01-01

    Low bond strength between tooth structure and restorative ceramic material is a major cause of ceramic fractures or failures. Prebonding measures performed on pressable ceramic material were evaluated and the different shear bond strengths obtained by each method were tabulated. The three individual groups were subjected to 9% hydrofluoric (HF) acid gel for 0, 1, and 5 minutes. The different acid-etched time groups were chemically treated with silane coupler alone, silane coupling agent with bonding agent, and bonding agent alone. The silane coupling agent produced the highest bond strength between the composite structure and the pressable ceramic restorative material. High bond values were achieved by etching the porcelain for one minute. The use of the silane coupling agent with a one minute 9% HF acid etch yielded the greatest bond strength.

  1. Effects of green tea on the shear bond strength of orthodontic brackets after in-office vital bleaching.

    PubMed

    Berger, Sandrine Bittencourt; Guiraldo, Ricardo Danil; Lopes, Murilo Baena; Oltramari-Navarro, Paula Vanessa; Fernandes, Thais Maria; Schwertner, Renata de Castro Alves; Ursi, Wagner José Silva

    2016-01-01

    The application of bleaching agents before placement of resin-bonded fixed appliances significantly, but temporarily, reduces bond strength to tooth structure. Antioxidants have been studied as a means to remove residual oxygen that compromises bonding to bleached enamel. This in vitro study evaluated whether green tea (GT) could restore the shear bond strength between bonded orthodontic brackets and bleached enamel. Six experimental groups were compared: group 1, no bleaching plus bracket bonding (positive control); group 2, bleaching with 35% hydrogen peroxide (HP) plus bracket bonding (negative control); group 3, 35% HP plus 10% sodium ascorbate (SA) plus bracket bonding; group 4, 35% HP plus 10% GT plus bracket bonding; group 5, no bleaching plus 10% SA plus bracket bonding; group 6, no bleaching plus 10% GT plus bracket bonding. Results suggested that GT, like SA, may be beneficial for bracket bonding immediately after bleaching.

  2. Evaluation of the effect of tooth and dental restoration material on electron dose distribution and production of photon contamination in electron beam radiotherapy.

    PubMed

    Bahreyni Toossi, Mohammad Taghi; Ghorbani, Mahdi; Akbari, Fatemeh; Mehrpouyan, Mohammad; Sobhkhiz Sabet, Leila

    2016-03-01

    The aim of this study is to evaluate the effect of tooth and dental restoration materials on electron dose distribution and photon contamination production in electron beams of a medical linac. This evaluation was performed on 8, 12 and 14 MeV electron beams of a Siemens Primus linac. MCNPX Monte Carlo code was utilized and a 10 × 10 cm(2) applicator was simulated in the cases of tooth and combinations of tooth and Ceramco C3 ceramic veneer, tooth and Eclipse alloy and tooth and amalgam restoration materials in a soft tissue phantom. The relative electron and photon contamination doses were calculated for these materials. The presence of tooth and dental restoration material changed the electron dose distribution and photon contamination in phantom, depending on the type of the restoration material and electron beam's energy. The maximum relative electron dose was 1.07 in the presence of tooth including amalgam for 14 MeV electron beam. When 100.00 cGy was prescribed for the reference point, the maximum absolute electron dose was 105.10 cGy in the presence of amalgam for 12 MeV electron beam and the maximum absolute photon contamination dose was 376.67 μGy for tooth in 14 MeV electron beam. The change in electron dose distribution should be considered in treatment planning, when teeth are irradiated in electron beam radiotherapy. If treatment planning can be performed in such a way that the teeth are excluded from primary irradiation, the potential errors in dose delivery to the tumour and normal tissues can be avoided.

  3. AFOSR Wafer Bonding

    DTIC Science & Technology

    2009-07-31

    cleanliness (foreign particles) and surface morphology (roughness). Two silicon wafers, when properly cleaned, can easily bond at room temperature because of...4 Figure IV data for nSi-nGaN bond. Structure is similar to that shown in Figure Difficulties and Knowledge Added Surface Morphology and...Particles One of the most important features of materials in determining whether they will bond is the quality of the bonding surfaces , in both

  4. Diffusion bonding aeroengine components

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, G. A.; Broughton, T.

    1988-10-01

    The use of diffusion bonding processes at Rolls-Royce for the manufacture of titanium-alloy aircraft engine components and structures is described. A liquid-phase diffusion bonding process called activated diffusion bonding has been developed for the manufacture of the hollow titanium wide chord fan blade. In addition, solid-state diffusion bonding is being used in the manufacture of hollow vane/blade airfoil constructions mainly in conjunction with superplastic forming and hot forming techniques.

  5. Indirect aesthetic adhesive restoration with fibre-reinforced composite resin.

    PubMed

    Corona, S A M; Garcia, P P N S; Palma-Dibb, R G; Chimello, D T

    2004-10-01

    This paper describes the restoration of an endodontically treated upper first molar with a fibre-reinforced onlay indirect composite resin restoration. The clinical and radiographic examination confirmed that the tooth had suffered considerable loss of structure. Therefore, an indirect restoration was indicated. First, a core was built with resin-modified glass ionomer cement, followed by onlay preparation, mechanical/chemical gingival retraction and impression with addition-cured silicone. After the laboratory phase, the onlay was tried in, followed by adhesive bonding and occlusal adjustment. It can be concluded that fibre-reinforced aesthetic indirect composite resin restoration represented, in the present clinical case, an aesthetic and conservative treatment option. However, the use of fibres should be more extensively studied to verify the real improvement in physical and mechanical properties.

  6. Glass-ionomer Cements in Restorative Dentistry: A Critical Appraisal.

    PubMed

    Almuhaiza, Mohammed

    2016-04-01

    Glass-ionomer cements (GICs) are mainstream restorative materials that are bioactive and have a wide range of uses, such as lining, bonding, sealing, luting or restoring a tooth. Although the major characteristics of GICs for the wider applications in dentistry are adhesion to tooth structure, fluoride releasing capacity and tooth-colored restorations, the sensitivity to moisture, inherent opacity, long-term wear and strength are not as adequate as desired. They have undergone remarkable changes in their composition, such as the addition of metallic ions or resin components to their composition, which contributed to improve their physical properties and diversified their use as a restorative material of great clinical applicability. The light-cured polymer reinforced materials appear to have substantial benefits, while retaining the advantages of fluoride release and adhesion. Further research should be directed towards improving the properties, such as strength and esthetics without altering its inherent qualities, such as adhesion and fluoride releasing capabilities.

  7. Restoring the prairie

    SciTech Connect

    Mlot, C.

    1990-12-01

    The US DOE at the Fermi National Accelerator Laboratory in Batavia, Illinois, prairie restoration is taking place in order to conserve the rich topsoil. This is the largest of many prairie restoration experiments. Big bluestem grass (Andropogon gerardi), blue grama (Bouteloua gracilis), and buffalo grass (Buchloe dactyloides) are the main initial grasses grown. After their growth reaches enough biomass to sustain a fire, other prairie plants such as purple prairie clover and dropseed grass appear. The goal of this is to provide a generous refuge for disappearing native plants and animals, a site for scientific research, and a storehouse of genes adapted to a region that produces much of the worlds food. Plans for restoring the marsh and oak savanna, also native to the Fermilab site are also in the works.

  8. Acrylic mechanical bond tests

    SciTech Connect

    Wouters, J.M.; Doe, P.J.

    1991-02-01

    The tensile strength of bonded acrylic is tested as a function of bond joint thickness. 0.125 in. thick bond joints were found to posses the maximum strength while the acceptable range of joints varied from 0.063 in. to almost 0.25 in. Such joints are used in the Sudbury Neutrino Observatory.

  9. Rapid adhesive bonding concepts

    NASA Technical Reports Server (NTRS)

    Stein, B. A.; Tyeryar, J. R.; Hodges, W. T.

    1984-01-01

    Adhesive bonding in the aerospace industry typically utilizes autoclaves or presses which have considerable thermal mass. As a consequence, the rates of heatup and cooldown of the bonded parts are limited and the total time and cost of the bonding process is often relatively high. Many of the adhesives themselves do not inherently require long processing times. Bonding could be performed rapidly if the heat was concentrated in the bond lines or at least in the adherends. Rapid adhesive bonding concepts were developed to utilize induction heating techniques to provide heat directly to the bond line and/or adherends without heating the entire structure, supports, and fixtures of a bonding assembly. Bonding times for specimens are cut by a factor of 10 to 100 compared to standard press bonding. The development of rapid adhesive bonding for lap shear specimens (per ASTM D1003 and D3163), for aerospace panel bonding, and for field repair needs of metallic and advanced fiber reinforced polymeric matrix composite structures are reviewed.

  10. Bonding aluminum beam leads

    NASA Technical Reports Server (NTRS)

    Burkett, F. S.

    1978-01-01

    Report makes it relatively easy for hybrid-circuit manufacturers to convert integrated circuit chips with aluminum bead leads. Report covers: techniques for handling tiny chips; proper geometries for ultrasonic bonding tips; best combinations of pressure, pulse time, and ultrasonic energy for bonding; and best thickness for metal films to which beam leads are bonded.

  11. [Is it necessary to assess experimentally and clinically restorative materials already on the market?].

    PubMed

    Merte, Ilka; Schneider, Hartmut; Merte, Knut

    2004-01-01

    The precondition for introducing medical products, e.g. new filling materials, in the European Union is their safety, not their clinical reliability. The latter arises from longitudinal studies and is assessed on the basis of available standards or, if not existant, on formulated quality guidelines. In the case of the specific products Ariston Liner and Ariston pHc (Vivadent, Schaan, FL), designed as an amalgam substitute, the material combination did not correspond to the Swiss standard 2 of restorative dentistry. Although after a short-term application testing on caries free premolars the pulp and dentin were free from inflammation and bacteria, the material combination clinically failed within the 18 months control period with a cumulative failure rate of 16.1% due to marginal caries. After six months of function the subjectively assessed sensitivity tended to increase. Gap formations and porous zones were detected in the composite-tooth-interface in vitro as well as in vivo. Neither the lining, designed to ensure the passage of cations and anions out of the filling material, nor the concept of an adequate caries protective effect proved successful. Marginal caries and hypersensitivity of teeth were the main reasons for the replacement of this amalgam substitute. The specific material combination was withdrawn from the market. As long as laboratory methods cannot substitute clinical evaluations, the introduction of new materials or systems into the market should be supported by short-term clinical studies and the further quality assessment should result from intermediate to long-term longitudinal studies. In this respect guidelines are valuable, such as the Swiss guidelines concerning materials as amalgam substitute.

  12. Everglades Restoration Critiqued

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    The monitoring and assessment plan for the $7.8-billion effort to restore the hydrologic regime of the remaining wetlands of Florida's Everglades needs to be strengthened, according to a 2 April study by a committee of the National Academy of Sciences. The evolving monitoring and assessment plan of the Comprehensive Everglades Restoration Plan is grounded in current scientific theory and practice of adaptive management, according to the report. However, the least-developed aspects of the management are feedback mechanisms to connect monitoring to planning and management, the report notes.

  13. Overvoltage control during restoration

    SciTech Connect

    Adibi, M.M. ); Alexander, R.W. ); Avra-Movic, B. )

    1992-11-01

    This paper is one in a series presented on behalf of the System Operation Subcommittee with the intent of focusing industry attention on power system restoration issues. Restoration of a bulk power supply system presents the operator with unique challenges not normally encountered in daily operations. The initial, and even intermediate transmission system topologies are quite different from the well integrated systems during normal operation. There are several problems that pertain to these non-normal topologies that are of common concern to operators and need to be addressed. One of these, the problem of overvoltages, is the subject of this paper.

  14. Turbulence characterization on the ripple-dune amalgamation stage: importance for bed morphodynamic patterns

    NASA Astrophysics Data System (ADS)

    Frias, C.; Abad, J. D.

    2011-12-01

    extend the observations made by previous experimental results on the bedforms amalgamation process. To this end, three LES simulations are carried out to replicate an amalgamation process, a single dune case, a dune with a superimposed ripple on the dune stoss side case and a complete amalgamated ripple over dune case. Although the experimental base case involved two dimensional bedforms, a three dimensional simulation will be developed to analyze the effects of superimposition in transversal and streamwise directions. Some of the results to be analyzed are the average, instantaneous and the fluctuations of hydrodynamics parameters such as velocity, pressure and stresses. As observed previously, the superimposed case presents the highest turbulence intensities and thus a very important influence on sediment transport. Therefore, a characterization of the interaction of shear layers (from the ripple and the dune) is carried out to explain the implication of the localization of the ripple respect to the dune. These LES models are performed using a free surface condition at the top of the domain to allow the model develop undulations on the water surface caused by effect of the bedforms. Implications to bed morphology patterns are discussed.

  15. Assessment of the release of mercury from silver amalgam alloys exposed to different 10% carbamide peroxide bleaching agents.

    PubMed

    Salomone, Paloma; Bueno, Renata Pla Rizzolo; Trinidade, Rodrigo Farcili; Nascimento, Paulo Cicero; Pozzobon, Roselaine Tezezinha

    2013-01-01

    This in vitro study assessed the amount of mercury (Hg) released from a silver amalgam alloy following the application of different 10% carbamide peroxide bleaching agents. A total of 30 specimens (2 mm thick x 4 mm in diameter) were stored in deionized water at 37°C for 7 days. Next, the control group (n = 10) remained in the deionized water for 15 days, while the remaining samples were exposed to 1 of 2 bleaching agents (n = 10) for 8 hours daily (total exposure = 120 hours); for the remaining 16 hours, specimens in the test groups were stored in deionized water at 37°C under relative humidity. After this period, the quantity of Hg in the deionized water was assessed (using atomic absorption spectrophotometry) and compared to the amount of Hg at baseline. The results indicate that exposing amalgam alloys to bleaching agents released greater amounts of Hg compared to exposing samples to deionized [corrected] water.

  16. Bonding thermoplastic polymers

    DOEpatents

    Wallow, Thomas I.; Hunter, Marion C.; Krafcik, Karen Lee; Morales, Alfredo M.; Simmons, Blake A.; Domeier, Linda A.

    2008-06-24

    We demonstrate a new method for joining patterned thermoplastic parts into layered structures. The method takes advantage of case-II permeant diffusion to generate dimensionally controlled, activated bonding layers at the surfaces being joined. It is capable of producing bonds characterized by cohesive failure while preserving the fidelity of patterned features in the bonding surfaces. This approach is uniquely suited to production of microfluidic multilayer structures, as it allows the bond-forming interface between plastic parts to be precisely manipulated at micrometer length scales. The bond enhancing procedure is easily integrated in standard process flows and requires no specialized equipment.

  17. Cyclic Voltammetry Probe Approach Curves with Alkali Amalgams at Mercury Sphere-Cap Scanning Electrochemical Microscopy Probes.

    PubMed

    Barton, Zachary J; Rodríguez-López, Joaquín

    2017-03-07

    We report a method of precisely positioning a Hg-based ultramicroelectrode (UME) for scanning electrochemical microscopy (SECM) investigations of any substrate. Hg-based probes are capable of performing amalgamation reactions with metal cations, which avoid unwanted side reactions and positive feedback mechanisms that can prove problematic for traditional probe positioning methods. However, prolonged collection of ions eventually leads to saturation of the amalgam accompanied by irreversible loss of Hg. In order to obtain negative feedback positioning control without risking damage to the SECM probe, we implement cyclic voltammetry probe approach surfaces (CV-PASs), consisting of CVs performed between incremental motor movements. The amalgamation current, peak stripping current, and integrated stripping charge extracted from a shared CV-PAS give three distinct probe approach curves (CV-PACs), which can be used to determine the tip-substrate gap to within 1% of the probe radius. Using finite element simulations, we establish a new protocol for fitting any CV-PAC and demonstrate its validity with experimental results for sodium and potassium ions in propylene carbonate by obtaining over 3 orders of magnitude greater accuracy and more than 20-fold greater precision than existing methods. Considering the timescales of diffusion and amalgam saturation, we also present limiting conditions for obtaining and fitting CV-PAC data. The ion-specific signals isolated in CV-PACs allow precise and accurate positioning of Hg-based SECM probes over any sample and enable the deployment of CV-PAS SECM as an analytical tool for traditionally challenging conditions.

  18. Study of tin amalgam mirrors by 1 1 9 Sn Mössbauer spectroscopy and other analytical methods

    NASA Astrophysics Data System (ADS)

    Lerf, A.; Wagner, F. E.; Herrera, L. K.; Justo, A.; Mu noz-Páez, A.; Pérez-Rodríguez, J. L.

    2016-12-01

    From the beginning of the 16 th until the end of the 19 th century the most widely used mirrors consisted of a pane of glass backed with a reflecting layer of tin-mercury amalgam. They were made by sliding the glass pane over a tin foil covered with liquid mercury. After removal of the superfluous mercury, tin amalgam formed slowly at ambient temperature and yielded a reflecting layer adhering to the surface of the glass. Such mirrors often deteriorate in the course of time by oxidation of the tin in the amalgam to stannous or stannic oxide. 119Sn Mössbauer spectroscopy, scanning electron microscopy, micro-XRF and X-ray diffraction have been used to study this deterioration process. The studied specimens were a modern mirror made for the reconstruction of the Green Vault in Dresden in the early 2000s, two rather well preserved German mirrors from the 17 th and 19 th centuries and several strongly deteriorated specimens of Baroque mirrors from the south of Spain. The modern mirror consists mainly of a Sn0.9Hg0.1 amalgam with only 2 % of SnO2. The older German mirrors showed more pronounced oxidation, containing 12 and 15 % of SnO2, which did not noticeably impair their reflectivity. In the samples from the Spanish mirrors at best a few percent of metallic phase was left. The majority of the tin had oxidised to SnO2, but between 8 and 20 % of the tin was present as SnO. X-ray diffraction yielded similar results and micro-XRF mapping using synchrotron radiation for excitation gave information on the distribution of Sn and Hg in the reflecting layer of the mirrors.

  19. In-situ measurements of low-level mercury vapor exposure from dental amalgam with zeeman atomic absorption spectroscopy.

    PubMed

    Halbach, Stefan; Welzl, Gerhard

    2004-01-01

    Alongside food, emissions from amalgam fillings are an essential contribution to man's mercury burden. Previous methods for the determination of intraoral mercury vapor (Hg degrees ) release used principally some form of preconcentration of Hg on gold (film or wool), allowing relatively few measurements with unknown precision and sensitivity at selected times. Recently available computer-controlled Hg detectors operating on Zeeman atomic absorption spectroscopy (ZAAS) facilitate the direct real-time measurement of Hg degrees concentrations. It was the aim to adapt this method for a comparative investigation of emission processes from fillings in situ and from amalgam specimens in vitro. In addition to the ZAAS instrument, the apparatus consisted of a pump, magnetic valves, an electronic flow controller and a handle with a disposable mouth piece for aspiration of oral air. A programmable timer integrated the computer-controlled instrument operation and the data collection into a standard sampling protocol. A fast exponential decay of the emission was found after stimulation of amalgam specimens and of fillings in situ (halftimes 8.6 and 10.7 min). Precision was evaluated by a series of measurements on a single patient which indicated a consistently low coefficient of variation between 18% and 25%. After insertion of a few new fillings, sensitivity was high enough to detect a significant increase in emission against the background emission from the majority of old fillings. Zeeman-AAS in connection with a semi-automated sampling protocol and data storage provides precise in-situ measurements of Hg degrees emission from dental amalgam with real-time resolution. This facilitates the detailed exploration of the Hg degrees release kinetics and the applicability to large-scale studies.

  20. Influence of restorative techniques on marginal adaptation and dye penetration around Class V restorations.

    PubMed

    Pereira, Adriana de Fatima Vasconcelos; Poiate, Isis Andrea Venturini Pola; Poiate, Edgar; Rodrigues, Flavia Pires; Turbino, Mirian Lacalle; Miranda, Walter Gomes

    2012-01-01

    The aim of this study was to observe the influence of restorative techniques on marginal adaptation and dye penetration around Class V restorations simulating abfraction lesions. Sixty mandibular premolars were divided into six groups (n = 10) using different restorative materials. Cavity preparation presented the gingival wall localized in dentin and the incisal wall in enamel. Replicas of abfraction lesions were obtained and viewed under a stereomicroscope for adaptation assessment. All teeth were subjected to thermocycling and mechanical load cycling and immersed in 0.5% methylene blue dye (pH 7.2) for four hours. The results were tabulated and submitted to Kruskal-Wallis tests, which were significant for the dentin margin with lower microleakage values for primer/Vitremer, followed by Clearfil SE Bond/Durafill VS and Clearfil SE Bond/Z100 in qualitative and quantitative methods (P < 0.05). The enamel margin had no significant difference for microleakage values for all groups. There was no statistically significant difference among the substrates for marginal adaptation. The Spearman coefficient illustrated a direct relation between enamel and dentin for microleakage evaluation (P < 0.0001). The data demonstrated no difference for marginal fit by chi-square test. It can be concluded that all groups had microleakage in different degrees, with the lowest values for resin-modified glass ionomer.

  1. Fracture resistance of premolar teeth restored with different filling techniques.

    PubMed

    França, Fabiana Mantovani Gomes; Worschech, Claudia Cia; Paulillo, Luis Alexandre Maffei Sartini; Martins, Luis Roberto Marcondes; Lovadino, José Roberto

    2005-08-15

    The aim of this study is to verify the fracture resistance of premolars with large mesiocclusodistal (MOD) preparations with composite resin using different incremental techniques when subjected to an occlusal load. Forty maxillary premolar teeth were randomly divided into four groups (n=10). Class II MOD cavities were prepared in all specimens with parallel walls and no approximal boxes. The resulting isthmus width was 1/3 the distance between the cusp tips and (3/4) the height of the crown. Teeth in group I, the control group, were not restored. Specimens in group II were restored in three incremental vertical layers. Group III specimens were restored in three horizontal layers, and finally, specimens in group IV were restored in oblique layers. With exception of the placement technique, specimens in groups II, III and IV were restored using the Single Bond adhesive system and P60 composite resin following manufacturer's recommendations. A 4 mm diameter steel sphere contacted the buccal and lingual cusps of the tested teeth at a crosshead speed of 0.5 mm/min until fracture occurred. The values obtained in this study were subjected to Analysis of Variance (ANOVA) and a Tukey-Kramer test. Only group I (non-restored) obtained a minor means of fracture resistance. No significant differences among groups II, III, and IV were found. This study shows on large MOD cavities the incremental filling techniques do not influence the fracture resistance of premolar teeth restored with composite resin.

  2. Simple Bond Cleavage

    SciTech Connect

    Gary S. Groenewold

    2005-08-01

    Simple bond cleavage is a class of fragmentation reactions in which a single bond is broken, without formation of new bonds between previously unconnected atoms. Because no bond making is involved, simple bond cleavages are endothermic, and activation energies are generally higher than for rearrangement eliminations. The rate of simple bond cleavage reactions is a strong function of the internal energy of the molecular ion, which reflects a loose transition state that resembles reaction products, and has a high density of accessible states. For this reason, simple bond cleavages tend to dominate fragmentation reactions for highly energized molecular ions. Simple bond cleavages have negligible reverse activation energy, and hence they are used as valuable probes of ion thermochemistry, since the energy dependence of the reactions can be related to the bond energy. In organic mass spectrometry, simple bond cleavages of odd electron ions can be either homolytic or heterolytic, depending on whether the fragmentation is driven by the radical site or the charge site. Simple bond cleavages of even electron ions tend to be heterolytic, producing even electron product ions and neutrals.

  3. Hydrogen multicentre bonds.

    PubMed

    Janotti, Anderson; Van de Walle, Chris G

    2007-01-01

    The concept of a chemical bond stands out as a major development in the process of understanding how atoms are held together in molecules and solids. Lewis' classical picture of chemical bonds as shared-electron pairs evolved to the quantum-mechanical valence-bond and molecular-orbital theories, and the classification of molecules and solids in terms of their bonding type: covalent, ionic, van der Waals and metallic. Along with the more complex hydrogen bonds and three-centre bonds, they form a paradigm within which the structure of almost all molecules and solids can be understood. Here, we present evidence for hydrogen multicentre bonds-a generalization of three-centre bonds-in which a hydrogen atom equally bonds to four or more other atoms. When substituting for oxygen in metal oxides, hydrogen bonds equally to all the surrounding metal atoms, becoming fourfold coordinated in ZnO, and sixfold coordinated in MgO. These multicentre bonds are remarkably strong despite their large hydrogen-metal distances. The calculated local vibration mode frequency in MgO agrees with infrared spectroscopy measurements. Multicoordinated hydrogen also explains the dependence of electrical conductivity on oxygen partial pressure, resolving a long-standing controversy on the role of point defects in unintentional n-type conductivity of ZnO (refs 8-10).

  4. Model for Coastal Restoration

    SciTech Connect

    Thom, Ronald M.; Judd, Chaeli

    2007-07-27

    Successful restoration of wetland habitats depends on both our understanding of our system and our ability to characterize it. By developing a conceptual model, looking at different spatial scales and integrating diverse data streams: GIS datasets and NASA products, we were able to develop a dynamic model for site prioritization based on both qualitative and quantitative relationships found in the coastal environment.

  5. Nitriding of restored crankshafts

    NASA Astrophysics Data System (ADS)

    Ponukalin, V. V.; Aleksandrov, V. N.

    1984-02-01

    The following technology is recommended for restoration of steel crankshafts: facing with an Sv-08 electrode wire under an AN-348A flux with chromium and niobium introduced into the melt in accordance with the method used at automotive-repair plants and subsequent gas nitriding at (570±10)°C for 12 h.

  6. Restoring Fossil Creek

    ERIC Educational Resources Information Center

    Flaccus, Kathleen; Vlieg, Julie; Marks, Jane C.; LeRoy, Carri J.

    2004-01-01

    Fossil Creek had been dammed for the past 90 years, and plans were underway to restore the stream. The creek runs through Central Arizona and flows from the high plateaus to the desert, cutting through the same formations that form the Grand Canyon. This article discusses the Fossil Creek monitoring project. In this project, students and teachers…

  7. Ceramic restorations of anterior teeth without proximal reduction: a case report.

    PubMed

    Nakamura, Takashi; Nakamura, Toshio; Ohyama, Tatsuo; Wakabayashi, Kazumichi

    2003-01-01

    The primary advantage of using all-ceramic restorations is to reproduce a color and translucency close to those of the natural tooth. Additionally, it is anticipated that the use of an adhesion technique will allow a ceramic restoration without removing tooth structure in some patients. This case report describes the use of proximally bonded ceramic restorations for the closure of an anterior diastema without proximal tooth reduction. A silane coupling agent and a resin cement were used for bonding. The diastema was close with the ceramic restorations, which provided a natural appearance of the teeth. It was concluded that ceramic restorations without proximal tooth reduction was effective in improving esthetics, if the case was properly selected.

  8. Evaluation of the amalgamation reaction of experimental Ag-Sn-Cu alloys containing Pd using a mercury plating technique.

    PubMed

    Koike, Marie; Ferracane, Jack L; Fujii, Hiroyuki; Okabe, Toru

    2003-09-01

    A mercury plating technique was used to determine the phases forming on experimental Ag-Sn-Cu alloy powders (with and without Pd) exposed to electrolytically deposited mercury. Four series of alloy powders were made: a) 1.5% Pd with 10-14% Cu (CU series); b) 1.0% Pd with 10-14% Cu (1PD series); c) 1.5% Pd with different ratios of Ag3Sn (gamma) to Ag4Sn (beta) with 12% Cu (AGSN series); and d) 9-13% Cu with no Pd (NOPD series). Each powder was pressed on a freshly prepared amalgam specimen made from the same powder and metallographically polished until cross sections appeared; mercury was electroplated on the alloy particles. Alloy powders, amalgams and electroplated specimens were examined using XRD and SEM/EDS. XRD confirmed the presence of gamma2 in amalgams made from alloys with Cu < 13% or with Ag3Sn/Ag4Sn > 0.8. Specimens with moderately plated Hg showed gamma1 (Ag2Hg3) polyhedra and eta' Cu6Sn5, but not gamma2. This method effectively identifies alloys prone to forming gamma2.

  9. Emergency reattachment of fractured tooth. Using dentin bonding agent and flowable composite.

    PubMed

    Small, B W

    1996-10-01

    A case has been described that employed two restorative techniques used in novel ways. A dentin bonding system was used to reattach a fractured tooth fragment and a new flowable resin composite was placed to "fill in the cracks." This technique was recommended only as a temporary restoration and was used during an emergency visit. The restoration was accomplished in a timely fashion and can be recommended for use if excellent technique, including the use of the rubber dam, is followed.

  10. [Atraumatic restorative treatment: a dental alternative well-received by children].

    PubMed

    Aguirre Aguilar, Antonio Armando; Rios Caro, Teresa Etelvina; Huamán Saavedra, Jorge; França, Cristiane Miranda; Fernandes, Kristianne Porta Santos; Mesquita-Ferrari, Raquel Agnelli; Bussadori, Sandra Kalil

    2012-02-01

    The purpose of this study is to compare atraumatic restorative treatment (ART) with the conventional rotational restorative method (CM) to determine in both cases the total time required for the procedure, the cost, the presence of pain, and the behavior of pediatric patients in Peru. Of the 30 children selected for the study, half received ART and restoration with glass ionomer cement and the other half, CM and restoration with amalgam. The study parameters were the times required to remove the decayed tissue and to complete the entire procedure, the total cost of the procedure, the presence of pain, and the patient's behavior during treatment. Significant differences were found between the two techniques in all parameters, except for the patient's behavior. Although removing the decayed tissue was faster with the CM, the entire procedure was faster with ART, which, moreover, was significantly less expensive and less painful than the CM. The results indicated that ART is a very good alternative due to its low cost and acceptance by the children.

  11. Modelling the Longevity of Dental Restorations by means of a CBR System

    PubMed Central

    Aliaga, Ignacio J.; Vera, Vicente; García, Alvaro E.

    2015-01-01

    The lifespan of dental restorations is limited. Longevity depends on the material used and the different characteristics of the dental piece. However, it is not always the case that the best and longest lasting material is used since patients may prefer different treatments according to how noticeable the material is. Over the last 100 years, the most commonly used material has been silver amalgam, which, while very durable, is somewhat aesthetically displeasing. Our study is based on the collection of data from the charts, notes, and radiographic information of restorative treatments performed by Dr. Vera in 1993, the analysis of the information by computer artificial intelligence to determine the most appropriate restoration, and the monitoring of the evolution of the dental restoration. The data will be treated confidentially according to the Organic Law 15/1999 on 13 December on the Protection of Personal Data. This paper also presents a clustering technique capable of identifying the most significant cases with which to instantiate the case-base. In order to classify the cases, a mixture of experts is used which incorporates a Bayesian network and a multilayer perceptron; the combination of both classifiers is performed with a neural network. PMID:25866792

  12. Comparative study of mechanical properties of dental restorative materials and dental hard tissues in compressive loads

    PubMed Central

    Lee, Jong Yeop

    2014-01-01

    There are two objectives. One is to show the differences in the mechanical properties of various dental restorative materials compared to those of enamel and dentin. The other is to ascertain which dental restorative materials are more suitable for clinical treatments. Amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy were processed as dental restorative material specimens. The specimens (width, height, and length of 1.2, 1.2, and 3.0 mm, respectively) were compressed at a constant loading speed of 0.1 mm/min. The maximum stress (115.0 ± 40.6, 55.0 ± 24.8, 291.2 ± 45.3, 274.6 ± 52.2, 2206.0 ± 522.9, and 953.4 ± 132.1 MPa), maximum strain (7.8% ± 0.5%, 4.0% ± 0.1%, 12.7% ± 0.8%, 32.8% ± 0.5%, 63.5% ± 14.0%, and 45.3% ± 7.4%), and elastic modulus (1437.5 ± 507.2, 1548.4 ± 583.5, 2323.4 ± 322.4, 833.1 ± 92.4, 3895.2 ± 202.9, and 2222.7 ± 277.6 MPa) were evident for amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy, respectively. The reference hardness value of amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy was 90, 420, 130–135, 86.6–124.2, 1250, and 349, respectively. Since enamel grinds food, its abrasion resistance is important. Therefore, hardness value should be prioritized for enamel. Since dentin absorbs bite forces, mechanical properties should be prioritized for dentin. The results suggest that gold alloy simultaneously has a hardness value lower than enamel (74.8 ± 18.1), which is important in the wear of the opposing natural teeth, and higher maximum stress, maximum strain, and elastic modulus than dentin (193.7 ± 30.6 MPa, 11.9% ± 0.1%, 1653.7 ± 277.9 MPa, respectively), which are important considering the rigidity to absorb bite forces. PMID:25352921

  13. Placing Anterior Lithium-Disilicate Restorations Using a Dual-Cure Resin Cement.

    PubMed

    Poss, Stephen D

    2016-10-01

    Depending on the case, predictably seating today's esthetic indirect restorations can be challenging. Ultimately, the cementation and adhesive materials selected, combined with the techniques used for their placement, can greatly affect the quality and efficient delivery of laboratory-fabricated restorations. New adhesive bonding and cementation materials have the potential to simplify the delivery of indirect restorations and simultaneously reduce and/or eliminate many of the challenges clinicians face during the placement process. This article reviews the requisite characteristics of these materials and presents a case demonstrating their use when seating anterior lithium-disilicate restorations.

  14. Amalgamation of management information system into anaesthesiology practice: A boon for the modern anaesthesiologists.

    PubMed

    Bajwa, Sukhminder Jit Singh

    2014-03-01

    Over the years, traditional anaesthesia record keeping system has been the backbone of anaesthesiology ever since its introduction in the 1890s by Dr. Harvey Cushing and Dr. Ernest A. Codman. Besides providing the important information regarding patients' vital physiologic parameters, paper records had been a reliable source for various clinical research activities. The introduction of electronic monitoring gadgets and electronic record keeping systems has revolutionised the anaesthesiology practice to a large extent. Recently, the introduction of anaesthesia information management system (AIMS), which incorporates all the features of monitoring gadgets, such as electronic storage of large accurate data, quality assurance in anaesthesia, enhancing patient safety, ensuring legal protection, improved billing services and effecting an organisational change, is almost a revolution in modern-day anaesthesiology practice. The clinical research activities that are responsible for taking anaesthesiology discipline to higher peaks have also been boosted by the amalgamation of AIMS, enabling multicenter studies and sharing of clinical data. Barring few concerns in its installation, cost factors and functional aspects, the future of AIMS seems to be bright and will definitely prove to be a boon for modern-day anaesthesiology practice.

  15. Using cosmogenic nuclides from amalgamated talus cobbles to assess alpine erosion in the Teton Range

    NASA Astrophysics Data System (ADS)

    Tranel, L. M.

    2014-12-01

    Measuring spatial patterns and rates of erosion in alpine landscapes is challenging because locations are steep and remote, and hillslope processes including rockfalls, avalanches and landslides are stochastic. This study evaluates how variability between quantitative erosion rates and surface ages and qualitative weathering features on talus deposits may influence interpretations of the spatial distribution of hillslope erosion in the Teton Range. I use cosmogenic nuclide concentrations to estimate erosion rates and surface ages of bedrock and talus deposits. I then compare these cosmogenic nuclide results to talus volumetric estimates of erosion rates. I also compare the quantitative estimates of surface ages and erosion to qualitative weathering observations on talus cobbles. The resulting erosion rates from cosmogenic nuclides are slower than rates estimated from talus volumes, however, both methods produced the same pattern of erosion. The fastest and slowest cosmogenic nuclide and volumetric erosion rates were associated with the same fans. Exposure ages of talus surfaces decrease as elevation of the fans increase. Qualitative observations of weathering on cobble surfaces were not reliable to predict the relative rates of erosion on the talus fans. Using amalgamated samples from hillslope deposits adjacent to steep sided canyons for cosmogenic nuclide analysis has high uncertainty when finding accurate erosion rates or exposure ages due to complicated shielding on steeply sloping walls. The similar patterns of rapid or slow erosion rates, however, suggest that cosmogenic nuclides or volume estimates are both reasonable methods to understand relative timing of hillslope events, even if the absolute age or erosion rate cannot be determined.

  16. Determination of mercury in hair: Comparison between gold amalgamation-atomic absorption spectrometry and mass spectrometry.

    PubMed

    Domanico, Francesco; Forte, Giovanni; Majorani, Costanza; Senofonte, Oreste; Petrucci, Francesco; Pezzi, Vincenzo; Alimonti, Alessandro

    2016-09-29

    Mercury is a heavy metal that causes serious health problems in exposed subjects. The most toxic form, i.e., methylmercury (MeHg), is mostly excreted through human hair. Numerous analytical methods are available for total Hg analysis in human hair, including cold vapour atomic fluorescence spectrometry (CV-AFS), inductively coupled plasma mass spectrometry (ICP-MS) and thermal decomposition amalgamation atomic absorption spectrometry (TDA-AAS). The aim of the study was to compare the TDA-AAS with the ICP-MS in the Hg quantification in human hair. After the washing procedure to minimize the external contamination, from each hair sample two aliquots were taken; the first was used for direct analysis of Hg by TDA-AAS and the second was digested for Hg determination by the ICP-MS. Results indicated that the two data sets were fully comparable (median; TDA-AAS, 475ngg(-1); ICP-MS, 437ngg(-1)) and were not statistically different (Mann-Whitney test; p=0.44). The two techniques presented results with a good coefficient of correlation (r=0.94) despite different operative ranges and method limits. Both techniques satisfied internal performance requirements and the parameters for method validation resulting sensitive, precise and reliable. Finally, the use of the TDA-AAS can be considered instead of the ICP-MS in hair analysis in order to reduce sample manipulation with minor risk of contamination, less time consuming due to the absence of the digestion step and cheaper analyses.

  17. Speciation of methylmercury in market seafood by thermal degradation, amalgamation and atomic absorption spectroscopy.

    PubMed

    Ruiz-de-Cenzano, Manuela; Rochina-Marco, Arancha; Cervera, M Luisa; de la Guardia, Miguel

    2014-09-01

    Sample thermal decomposition followed by mercury amalgamation and atomic absorption has been employed for the determination of methylmercury (MeHg) in fish. The method involves HBr leaching of MeHg, extraction into toluene, and back-extraction into an aqueous l-cysteine solution. Preliminary studies were focused on the extraction efficiency, losses, contaminations, and species interconversion prevention. The limit of detection was 0.018µgg(-1) (dry weight). The intraday precision for three replicate analysis at a concentration of 4.2µgg(-1) (dry weight) was 3.5 percent, similar to the interday precision according to analysis of variance (ANOVA). The accuracy was guaranteed by the use of fortified samples involving 83-105 percent recoveries, and certified reference materials TORT-2 (lobster hepatopancreas) and DORM-3 (dogfish liver), providing 107 and 98 percent recovery of certified values. The greenness of the method was also evaluated with the analytical eco-scale being obtained a final score of 73 points which means an acceptable green analysis. The method was applied to fifty-seven market samples of different fish acquired from local markets in several sampling campaigns. The content of MeHg found varied between 0.0311 and 1.24µgg(-1) (wet weight), with values that involve 33-129 percent of the total mercury content. Some considerations about food safety were also done taking into account data about Spanish fish consume and Tolerable Weekly Intake (TWI) established for MeHg.

  18. Clinical anatomy of the subserous layer: An amalgamation of gross and clinical anatomy.

    PubMed

    Yabuki, Yoshihiko

    2016-05-01

    The 1998 edition of Terminologia Anatomica introduced some currently used clinical anatomical terms for the pelvic connective tissue or subserous layer. These innovations persuaded the present author to consider a format in which the clinical anatomical terms could be reconciled with those of gross anatomy and incorporated into a single anatomical glossary without contradiction or ambiguity. Specific studies on the subserous layer were undertaken on 79 Japanese women who had undergone surgery for uterine cervical cancer, and on 26 female cadavers that were dissected, 17 being formalin-fixed and 9 fresh. The results were as follows: (a) the subserous layer could be segmentalized by surgical dissection in the perpendicular, horizontal and sagittal planes; (b) the segmentalized subserous layer corresponded to 12 cubes, or ligaments, of minimal dimension that enabled the pelvic organs to be extirpated; (c) each ligament had a three-dimensional (3D) structure comprising craniocaudal, mediolateral, and dorsoventral directions vis-á-vis the pelvic axis; (d) these 3D-structured ligaments were encoded morphologically in order of decreasing length; and (e) using these codes, all the surgical procedures for 19th century to present-day radical hysterectomy could be expressed symbolically. The establishment of clinical anatomical terms, represented symbolically through coding as demonstrated in this article, could provide common ground for amalgamating clinical anatomy with gross anatomy. Consequently, terms in clinical anatomy and gross anatomy could be reconciled and compiled into a single anatomical glossary.

  19. Amalgamation of management information system into anaesthesiology practice: A boon for the modern anaesthesiologists

    PubMed Central

    Bajwa, Sukhminder Jit Singh

    2014-01-01

    Over the years, traditional anaesthesia record keeping system has been the backbone of anaesthesiology ever since its introduction in the 1890s by Dr. Harvey Cushing and Dr. Ernest A. Codman. Besides providing the important information regarding patients’ vital physiologic parameters, paper records had been a reliable source for various clinical research activities. The introduction of electronic monitoring gadgets and electronic record keeping systems has revolutionised the anaesthesiology practice to a large extent. Recently, the introduction of anaesthesia information management system (AIMS), which incorporates all the features of monitoring gadgets, such as electronic storage of large accurate data, quality assurance in anaesthesia, enhancing patient safety, ensuring legal protection, improved billing services and effecting an organisational change, is almost a revolution in modern-day anaesthesiology practice. The clinical research activities that are responsible for taking anaesthesiology discipline to higher peaks have also been boosted by the amalgamation of AIMS, enabling multicenter studies and sharing of clinical data. Barring few concerns in its installation, cost factors and functional aspects, the future of AIMS seems to be bright and will definitely prove to be a boon for modern-day anaesthesiology practice. PMID:24963173

  20. Wiener amalgams and pointwise summability of Fourier transforms and Fourier series

    NASA Astrophysics Data System (ADS)

    Feichtinger, Hans G.; Weisz, Ferenc

    2006-05-01

    This paper provides a fairly general approach to summability questions for multi-dimensional Fourier transforms. It is based on the use of Wiener amalgam spaces W(L_p,ℓ_q)({mathbb R}(d)) , Herz spaces and weighted versions of Feichtinger's algebra and covers a wide range of concrete special cases (20 of them are listed at the end of the paper). It is proved that under some conditions the maximal operator of the theta-means sigma_T(theta) f can be estimated pointwise by the Hardy-Littlewood maximal function. From this it follows that sigma_T(theta) f {->} f a.e. for all fin W(L_1,ℓ_infty)({mathbb R}(d)) , hence fin L_p({mathbb R}(d)) for any 1≤ p≤ infty. Moreover, sigma_T(theta) f(x) converges to f(x) at each Lebesgue point of fin L_1({mathbb R}(d)) (resp. fin W(L_1,ℓ_infty)({mathbb R}(d)) ) if and only if the Fourier transform of theta is in a suitable Herz space. In case theta is in a Besov space or in a weighted Feichtinger's algebra or in a Sobolev-type space then the a.e. convergence is obtained. Some sufficient conditions are given for theta to be in the weighted Feichtinger's algebra. The same results are presented for multi-dimensional Fourier series.

  1. Assessing competence in undergraduate nursing students: the Amalgamated Students Assessment in Practice model.

    PubMed

    Zasadny, Mark F; Bull, Rosalind M

    2015-03-01

    Assessment of competence is characterised by ambiguity and inconsistency despite its critical role in assessing readiness for entry to the nursing profession. In 2012 the Amalgamated Student Assessment in Practice (ASAP) model and tool were developed and trialled within an Australian University. Developed in response to the inadequacies of existing tools to assess competence, the ASAP model offers an integrated multilayered assessment that is designed to enable focussed diagnosis of practice deficits and implementation of targeted support. The ASAP model was evaluated by gathering clinical facilitator and student feedback over two 13-week semesters during practice and formal meetings, as well as review of student performance data. The ASAP model functioned effectively as an assessment tool, focussed diagnostic tool, removal from Professional Experience Placement (PEP) support tool and a framework for documenting evidence. Student failure rates decreased and the number of complaints and successful appeals was reduced. The ASAP model offers comprehensive focussed assessment of nursing students' performance in practice. It supports both formative and summative feedback and can be used to accurately identify specific areas of practice deficiency requiring redirection and support. It is transferable across settings and assessors.

  2. Sulfide bonded atomic radii

    NASA Astrophysics Data System (ADS)

    Gibbs, G. V.; Ross, N. L.; Cox, D. F.

    2017-03-01

    The bonded radius, r b(S), of the S atom, calculated for first- and second-row non-transition metal sulfide crystals and third-row transition metal sulfide molecules and crystals indicates that the radius of the sulfur atom is not fixed as traditionally assumed, but that it decreases systematically along the bond paths of the bonded atoms with decreasing bond length as observed in an earlier study of the bonded radius of the oxygen atom. When bonded to non-transition metal atoms, r b(S) decreases systematically with decreasing bond length from 1.68 Å when the S atom is bonded to the electropositive VINa atom to 1.25 Å when bonded to the more electronegative IVP atom. In the case of transition metal atoms, rb(S) likewise decreases with decreasing bond length from 1.82 Å when bonded to Cu and to 1.12 Å when bonded to Fe. As r b(S) is not fixed at a given value but varies substantially depending on the bond length and the field strength of the bonded atoms, it is apparent that sets of crystal and atomic sulfide atomic radii based on an assumed fixed radius for the sulfur atom are satisfactory in that they reproduce bond lengths, on the one hand, whereas on the other, they are unsatisfactory in that they fail to define the actual sizes of the bonded atoms determined in terms of the minima in the electron density between the atoms. As such, we urge that the crystal chemistry and the properties of sulfides be studied in terms of the bond lengths determined by adding the radii of either the atomic and crystal radii of the atoms but not in terms of existing sets of crystal and atomic radii. After all, the bond lengths were used to determine the radii that were experimentally determined, whereas the individual radii were determined on the basis of an assumed radius for the sulfur atom.

  3. Microanalysis of oligodeoxynucleotides by cathodic stripping voltammetry at amalgam-alloy surfaces in the presence of copper ions.

    PubMed

    Hason, Stanislav; Vetterl, Vladimír

    2006-05-15

    The application of gold amalgam-alloy electrode (AuAE) for a sensitive voltammetric detection of different oligodeoxynucleotides (ODNs) containing the purine units within the ODN-chains in the presence of copper is described. The detection of ODNs is based on the following procedure: (i) the first step includes an acidic hydrolysis of the ODN (ahODN) samples performing the release of the purine bases from ODN-chain; (ii) the second step includes an electrochemical accumulation of the complex of the purine base residues released from ODN-chain with copper ions Cu(I) (ahODN-Cu(I) complex) at the potential of reduction of copper ions Cu(II) on the amalgam-alloy electrode surfaces; (iii) finally followed the cathodic stripping of the electrochemically accumulated ahODN-Cu(I) complex from the electrode surface. The proposed electrochemical method was used for: (a) detection of different ODN lengths containing only adenine units (the number of adenine units within the ODN-chains was changed from 10 to 80), and (b) determination of the number of purine units within the 30-mer ODNs containing a random sequence segments involving both the purine and pyrimidine units. The intensity of the cathodic stripping current density peak (j(CSP)) of the electrochemically accumulated ahODN-Cu(I) complex increased linearly with the increasing number of purine units within the ODN-chains. We observed a good correlation between the percentage content of purine units to the whole length of different 30-mer ODNs and the percentage content of the intensity of the j(CSP) of the electrochemically accumulated 30-mer ahODN-Cu(I) complexes. The detection of acid hydrolysed 80-mer (A(80)) in the bulk solution and in a 20-mul volume is possible down to 200pM and 2nM at the AuAE, respectively. For the shortest 10-mer (A(10)) a detectable value of 5nM in the bulk solution on the AuAE was observed. The sensitive detection of different ODNs containing the purine units in their chains in the presence of

  4. Digital restoration of multichannel images

    NASA Technical Reports Server (NTRS)

    Galatsanos, Nikolas P.; Chin, Roland T.

    1989-01-01

    The Wiener solution of a multichannel restoration scheme is presented. Using matrix diagonalization and block-Toeplitz to block-circulant approximation, the inversion of the multichannel, linear space-invariant imaging system becomes feasible by utilizing a fast iterative matrix inversion procedure. The restoration uses both the within-channel (spatial) and between-channel (spectral) correlation; hence, the restored result is a better estimate than that produced by independent channel restoration. Simulations are also presented.

  5. Bonded semiconductor substrate

    DOEpatents

    Atwater, Jr.; Harry A. , Zahler; James M.

    2010-07-13

    Ge/Si and other nonsilicon film heterostructures are formed by hydrogen-induced exfoliation of the Ge film which is wafer bonded to a cheaper substrate, such as Si. A thin, single-crystal layer of Ge is transferred to Si substrate. The bond at the interface of the Ge/Si heterostructures is covalent to ensure good thermal contact, mechanical strength, and to enable the formation of an ohmic contact between the Si substrate and Ge layers. To accomplish this type of bond, hydrophobic wafer bonding is used, because as the invention demonstrates the hydrogen-surface-terminating species that facilitate van der Waals bonding evolves at temperatures above 600.degree. C. into covalent bonding in hydrophobically bound Ge/Si layer transferred systems.

  6. Adaptive wiener image restoration kernel

    SciTech Connect

    Yuan, Ding

    2007-06-05

    A method and device for restoration of electro-optical image data using an adaptive Wiener filter begins with constructing imaging system Optical Transfer Function, and the Fourier Transformations of the noise and the image. A spatial representation of the imaged object is restored by spatial convolution of the image using a Wiener restoration kernel.

  7. Prairie Restoration for Wisconsin Schools.

    ERIC Educational Resources Information Center

    Murray, Molly Fifield; Greenler, Robin McC.

    This packet is composed of several resources for teachers interested in prairie ecology and restoration. "A Guide to Restoration from Site Analysis to Management" focuses on the Prairie/Oak Savanna communities of Wisconsin and takes teachers through the planning and design process for a restoration project on school grounds including…

  8. 56-month clinical performance of Class I and II resin composite restorations

    PubMed Central

    PAZINATTO, Flavia Bittencourt; GIONORDOLI NETO, Ranulfo; WANG, Linda; MONDELLI, José; MONDELLI, Rafael Francisco Lia; NAVARRO, Maria Fidela de Lima

    2012-01-01

    Objective This study evaluated the 56-month clinical performance of Class I and II resin composite restorations. Filtek P60 was compared with Filtek Z250, which are both indicated for posterior restorations but differ in terms of handling characteristics. The null hypothesis tested was that there is no difference in the clinical performance of the two resin composites in posterior teeth. Material and Methods Thirty-three patients were treated by the same operator, who prepared 48 Class I and 42 Class II cavities, which were restored with Single Bond/Filtek Z250 or Single Bond/Filtek P60 restorative systems. Restorations were evaluated by two independent examiners at baseline and after 56 months, using the modified USPHS criteria. Data were analyzed statistically using Chi-square and Fisher's Exact tests (a=0.05). Results After 56 months, 25 patients (31 Class I and 36 Class II) were analyzed. A 3% failure rate occurred due to secondary caries and excessive loss of anatomic form for P60. For both restorative systems, there were no significant differences in secondary caries and postoperative sensitivity. However, significant changes were observed with respect to anatomic form, marginal discoloration, and marginal adaptation. Significant decreases in surface texture were observed exclusively for the Z250 restorations. Conclusions Both restorative systems can be used for posterior restorations and can be expected to perform well in the oral environment. PMID:22858698

  9. Microleakage of Er:YAG laser and dental bur prepared cavities in primary teeth restored with different adhesive restorative materials.

    PubMed

    Baghalian, Ali; Nakhjavani, Yahya B; Hooshmand, Tabassom; Motahhary, Pouria; Bahramian, Hoda

    2013-11-01

    The purpose of this study was to evaluate and compare the effect of erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiation and conventional dental bur cavity preparation on in vitro microleakage of class V cavities restored with different adhesive restorative materials and two types of self-etching adhesives in primary teeth. Standard class V cavities were prepared on 80 extracted primary, and the teeth were randomly divided into eight subgroups prepared either by dental bur or Er:YAG laser irradiation and then restored with self-cured glass ionomer (GI), resin-modified glass ionomer (RMGI), resin composite and Clearfil SE Bond (two-step self-etching adhesive), and resin composite and Clearfil S3 Bond (one-step self-etching adhesive). Restorations were finished and stored in distilled water at 37 °C for 24 h and then subjected to thermocycling. All the teeth were sealed with nail varnish, placed in a silver nitrate solution, and then vertically cut in a buccolingually direction. Subsequently, the specimens were evaluated for gingival and occlusal microleakage using a stereomicroscope. Data were analyzed using Kruskal-Wallis test followed by Mann-Whitney test. Wilcoxon test was used for comparing occlusal microleakage with gingival microleakage at p < 0.05. A higher degree of occlusal and gingival microleakage values for the teeth restored with GI or RMGI was obtained by both preparation methods compared with that of resin composites and the two self-etching primers. Er:YAG laser irradiation resulted in a significantly higher degree of microleakage only at the gingival margins for teeth restored with GI or RMGI, or composite and Clearfil S3 Bond compared with the bur preparation. The Er:YAG laser-prepared teeth restored with composite and Clearfil SE Bond demonstrated a better marginal seal on occlusal and gingival margins compared with that of bur-prepared cavities. The degree of microleakage in class V cavities was affected by the type of adhesive

  10. BONDING ALUMINUM METALS

    DOEpatents

    Noland, R.A.; Walker, D.E.

    1961-06-13

    A process is given for bonding aluminum to aluminum. Silicon powder is applied to at least one of the two surfaces of the two elements to be bonded, the two elements are assembled and rubbed against each other at room temperature whereby any oxide film is ruptured by the silicon crystals in the interface; thereafter heat and pressure are applied whereby an aluminum-silicon alloy is formed, squeezed out from the interface together with any oxide film, and the elements are bonded.

  11. Chemical bonding technology

    NASA Technical Reports Server (NTRS)

    Plueddemann, E.

    1986-01-01

    Primers employed in bonding together the various material interfaces in a photovoltaic module are being developed. The approach develops interfacial adhesion by generating actual chemical bonds between the various materials bonded together. The current status of the program is described along with the progress toward developing two general purpose primers for ethylene vinyl acetate (EVA), one for glass and metals, and another for plastic films.

  12. Relativistic Linear Restoring Force

    ERIC Educational Resources Information Center

    Clark, D.; Franklin, J.; Mann, N.

    2012-01-01

    We consider two different forms for a relativistic version of a linear restoring force. The pair comes from taking Hooke's law to be the force appearing on the right-hand side of the relativistic expressions: d"p"/d"t" or d"p"/d["tau"]. Either formulation recovers Hooke's law in the non-relativistic limit. In addition to these two forces, we…

  13. Evaluation of Fracture Resistance of Various Restorative Systems for Posterior Full Contour Restorations by Means of Scanning Technology

    NASA Astrophysics Data System (ADS)

    Dhima, Matilda

    Aims: The goals of this study were to: 1.) assess a range of the performance of four restorative systems for posterior single tooth crowns under single load to fracture submerged in an aqueous environment, 2.) identify restorative system(s) of interest to be examined under sliding contact step-stress fatigue as full contour anatomically appropriate single posterior tooth restoration(s) of various thicknesses submerged in water, 3.) assess a range of the performance of various thicknesses of restorative system(s) of interest. Material and Methods: A total of forty samples (n=10 each group) 2 mm uniform thickness were tested. Group 1. monolithic lithium disilicate IPS e.max Press; group 2. IPS e.max ZirPress, 0.8mm zirconia core with 1.2mm pressed veneering porcelain, group 3. IPS e.max ZirPress, 0.4mm zirconia core with 1.6mm pressed veneering porcelain, group 4. IPS InLine PoM. Samples were bonded to a block of polycast acrylic resin on a 30 degree sloped surface with resin cement. Samples were axially single loaded to failure while submerged under water. Findings from the testing were statistically analyzed and used to establish parameters for the material of interest to test submerged in aqueous environment under sliding contact step-stress fatigue as full contour single posterior restoration. This second phase assessed the performance of four groups (n=10 each group) of 0.5mm, 1.0mm, 1.5mm and 2.0mm of lithium disilicate restorations were tested. The tooth preparation for each sample was uniformly reduced, scanned digitally and milled for each group. The restorations were fabricated by scanning and milling technology. Results: There was a statistically significant difference (p< 0.001) in single failure load among the four restorative systems. Lithium disilicate showed a mean failure load similar to mean maximum posterior bite forces (743.1N +/- 114.3 N). This material was identified of interest to test submerged in aqueous environment under peak value force and

  14. Comparative Evaluation of Microshear Bond Strength of 5th, 6th and 7th Generation Bonding Agents to Coronal Dentin Versus Dentin at Floor of Pulp Chamber: An In vitro Study

    PubMed Central

    Deepa, Velagala Lakshmi; Damaraju, Bhargavi; Priyadharsini, Bollu Indira; Subbarao, Vummidisetti V; Raju, K Rama Krishna

    2014-01-01

    Background: Lack of seal and adhesion between the final restoration and tooth structure adversely affects the results of root canal treatment. Lots of adhesive bonding agents are marketed to overcome this deficiency and achieve successful restoration. So the study compares and evaluates the micro shear bond strength of coronal dentin and pulp chamber dentin using three different generation dentin bonding systems and to know clinical efficiency for clinical use. Materials and Methods: Different generation dentin bonding systems used were: (1) One bottle total etch system (XP Bond-5th generation), (2) Two-step self-etch system (Clearfil SE Bond-6th generation) and (3) All-in-one system (G Bond-7th generation). Thirty human mandibular molars were collected out of which sixty samples were prepared by sectioning each tooth into coronal dentin and pulpal floor dentin. They were divided into two major groups. Group I: 30 Coronal dentin samples. Group II:30 Pulpal floor dentin samples. Both the groups were further subdivided depending on the bonding agent used. Subgroup Ia:XP Bond, Subgroup Ib:Clearfil SE Bond, Subgroup Ic:G Bond, Subgroup IIa:XP Bond, Subgroup IIb:Clearfil SE Bond, Subgroup IIc:G Bond. Resin composite was bonded to these samples and tested for micro-shear bond strength. The mean bond strengths and standard deviations were calculated and analyzed using one-way ANOVA test and Student’s t-test (unpaired) and honestly significant difference post-hoc tests. Results: Coronal dentin showed higher values of micro shear bond strength than the pulpal floor dentin. All-in-one system (G Bond) showed least bond strength values to both the regions coronal dentin and pulpal floor dentin. Conclusion: Factors affecting the shear bond strength are dependent on material (adhesive system), substrate depth and adhesive/depth interaction. Hence composition and substrate treatment should be considered for good adhesive. Chemical composition of adhesive system determines

  15. Biofilm formation on dental restorative and implant materials.

    PubMed

    Busscher, H J; Rinastiti, M; Siswomihardjo, W; van der Mei, H C

    2010-07-01

    Biomaterials for the restoration of oral function are prone to biofilm formation, affecting oral health. Oral bacteria adhere to hydrophobic and hydrophilic surfaces, but due to fluctuating shear, little biofilm accumulates on hydrophobic surfaces in vivo. More biofilm accumulates on rough than on smooth surfaces. Oral biofilms mostly consist of multiple bacterial strains, but Candida species are found on acrylic dentures. Biofilms on gold and amalgam in vivo are thick and fully covering, but barely viable. Biofilms on ceramics are thin and highly viable. Biofilms on composites and glass-ionomer cements cause surface deterioration, which enhances biofilm formation again. Residual monomer release from composites influences biofilm growth in vitro, but effects in vivo are less pronounced, probably due to the large volume of saliva into which compounds are released and its continuous refreshment. Similarly, conflicting results have been reported on effects of fluoride release from glass-ionomer cements. Finally, biomaterial-associated infection of implants and devices elsewhere in the body is compared with oral biofilm formation. Biomaterial modifications to discourage biofilm formation on implants and devices are critically discussed for possible applications in dentistry. It is concluded that, for dental applications, antimicrobial coatings killing bacteria upon contact are more promising than antimicrobial-releasing coatings.

  16. Radiopacity of resin-modified glass-ionomer restorative cements.

    PubMed

    Sidhu, S K; Shah, P M; Chong, B S; Pitt Ford, T R

    1996-09-01

    This in vitro study compared the relative radiopacities of three commercially available resin-modified glass-ionomer cements (Vitremer, Fuji II LC, and Photac-Fil), an experimental resin-modified glass-ionomer (V-66), two conventional glass-ionomers (ChemFil and Fuji Cap II), and amalgam (as the control). Radiopacity was assessed densitometrically and expressed as equivalent thicknesses of aluminum. All the glass-ionomer cements were more radiopaque than enamel and dentin, with the exception of ChemFil and Photac-Fil. Apart from the control material, the experimental resin-modified glass-ionomer material, V-66, had the highest radiopacity of all the materials tested. Of the three resin-modified glass-ionomer materials tested, Fuji II LC was the most radiopaque and Photac-Fil the least. For the radiopacity of restorative glass-ionomer materials to exceed that of enamel, it should be greater than 1.5 mm of equivalent thickness of aluminum.

  17. Biological restoration in pediatric dentistry: a brief insight.

    PubMed

    Md, Indira; Singh Dhull, Kanika; Nandlal, B; Kumar Ps, Praveen; Singh Dhull, Rachita

    2014-01-01

    Dental caries is the most prevalent disease in humans, especially during early childhood. The restoration of such an extensive carious lesion should be done properly to reestablish their anatomy and hence their masticatory, phonetic, esthetic and space-maintainer functions in the dental arches. The consequences of premature loss of primary teeth are well known, namely the loss of vertical dimension of occlusion, tongue thrusting and mouth breathing habits, which can be the sources of future malocclusion. Satisfactory restoration of these teeth, improving esthetics, along with the management of space and function has always been a challenge for pediatric dentist. An ever increasing demand for esthetics has led to innovation and development of newer treatment modalities for these problems. In an attempt to widen the treatment options as biologically and conservatively as possible, tooth structure is used as a restorative material to rehabilitate severely destroyed tooth crowns. This technique consists of bonding sterile dental fragments, obtained either from the patient or from a tooth bank, to the teeth. Such a technique was termed as 'biological restoration'. This article aims at reviewing the evolution, techniques and outcome of such biological restorations. How to cite this article: MD Indira, Dhull KS, Nandlal B, Kumar PSP, Dhull RS. Biological Restoration in Pediatric Dentistry: A Brief Insight. Int J Clin Pediatr Dent 2014;7(3):197-201.

  18. Copper-nickel-rich, amalgamated ferromanganese crust-nodule deposits from Shatsky Rise, NW Pacific

    USGS Publications Warehouse

    Hein, J.R.; Conrad, T.A.; Frank, M.; Christl, M.; Sager, W.W.

    2012-01-01

    A unique set of ferromanganese crusts and nodules collected from Shatsky Rise (SR), NW Pacific, were analyzed for mineralogical and chemical compositions, and dated using Be isotopes and cobalt chronometry. The composition of these midlatitude, deep-water deposits is markedly different from northwest-equatorial Pacific (PCZ) crusts, where most studies have been conducted. Crusts and nodules on SR formed in close proximity and some nodule deposits were cemented and overgrown by crusts, forming amalgamated deposits. The deep-water SR crusts are high in Cu, Li, and Th and low in Co, Te, and Tl concentrations compared to PCZ crusts. Thorium concentrations (ppm) are especially striking with a high of 152 (mean 56), compared to PCZ crusts (mean 11). The deep-water SR crusts show a diagenetic chemical signal, but not a diagenetic mineralogy, which together constrain the redox conditions to early oxic diagenesis. Diagenetic input to crusts is rare, but unequivocal in these deep-water crusts. Copper, Ni, and Li are strongly enriched in SR deep-water deposits, but only in layers older than about 3.4 Ma. Diagenetic reactions in the sediment and dissolution of biogenic calcite in the water column are the likely sources of these metals. The highest concentrations of Li are in crust layers that formed near the calcite compensation depth. The onset of Ni, Cu, and Li enrichment in the middle Miocene and cessation at about 3.4 Ma were accompanied by changes in the deep-water environment, especially composition and flow rates of water masses, and location of the carbonate compensation depth.

  19. “Evaluation of shear bond strength of a composite resin to white mineral trioxide aggregate with three different bonding systems”-An in vitro analysis

    PubMed Central

    Patil, Anand C.

    2016-01-01

    Background Mineral trioxide aggregate (MTA) is a biomaterial that has been investigated for endodontic applications. With the increased use of MTA in pulp capping, pulpotomy, perforation repair, apexification and obturation, the material that would be placed over MTA as a final restoration is an important matter. As composite resins are one of the most widely used final restorative materials, this study was conducted to evaluate the shear bond strength of a composite resin to white mineral trioxide aggregate (WMTA) using three different bonding systems namely the two-step etch and rinse adhesive, the self-etching primer and the All-in-one system. Material and Methods Forty five specimens of white MTA (Angelus) were prepared and randomly divided into three groups of 15 specimens each depending on the bonding systems used respectively. In Group A, a Two-step etch and rinse adhesive or ‘total-etch adhesive’, Adper Single Bond 2 (3M/ESPE) and Filtek Z350 (3M ESPE, St Paul, MN) were placed over WMTA. In group B, a Two-step self-etching primer system, Clearfil SE Bond (Kuraray, Medical Inc) and Filtek Z350 were used. In Group C, an All-in-one system, G Bond (GC corporation, Tokyo, Japan) and Filtek Z350 were used. The shear bond strength was measured for all the specimens. The data obtained was subjected to One way Analysis of Variance (ANOVA) and Scheffe’s post hoc test. Results The results suggested that the Two-step etch and rinse adhesive when used to bond a composite resin to white MTA gave better bond strength values and the All-in-one exhibited the least bond strength values. Conclusions The placement of composite used with a Two-step etch and rinse adhesive over WMTA as a final restoration may be appropriate. Key words:Composite resins, dentin bonding agents, mineral trioxide aggregate, shear bond strength. PMID:27398177

  20. Restoration of endodontically treated anterior teeth: an evaluation of coronal microleakage of glass ionomer and composite resin materials.

    PubMed

    Diaz-Arnold, A M; Wilcox, L R

    1990-12-01

    A glass ionomer material was evaluated for coronal microleakage in permanent lingual access restorations of endodontically treated anterior teeth. The material was tested as a restoration, placed over a zinc oxide-eugenol base, and as a base with an acid-etched composite resin veneer and a dentinal bonding agent. Restored teeth were thermocycled, immersed in silver nitrate, developed, and sectioned to assess microleakage. Significant coronal leakage was observed with all materials used.

  1. Long-term durability of dentin bonds made with a self-etching primer, in vivo.

    PubMed

    Sano, H; Yoshikawa, T; Pereira, P N; Kanemura, N; Morigami, M; Tagami, J; Pashley, D H

    1999-04-01

    The long-term durability of bonds between adhesive resins and dentin is of significant importance for the longevity of bonded restorations. We carried out an in vivo one-year study to evaluate the durability of resin-dentin bonds in the oral cavity, as well as to test the hypothesis that the adhesive interface would show morphological changes in vivo over time. Very shallow saucer-shaped dentin cavities were prepared in 12 intact teeth of one Japanese monkey (Macaca fuscata) under general anesthesia. The cavities were restored with Clearfil Liner Bond II and Clearfil Photo Posterior resin composite. The teeth were extracted at three different times: immediately, and 180 and 360 days after placement of the restorations. One day after the monkey was killed, specimens of the three time periods were subjected to the micro-tensile bond test at a crosshead speed of 1 mm/min. The surfaces of the failed bonds were observed under a field emission scanning electron microscope (FE-SEM). Bond strength measurements in this study were successfully performed and were stable at approximately 19 MPa during the one-year testing. Scanning electron microscopic observations of the failed surfaces revealed, at the top of the hybrid layer and within the adhesive resin, porosity which increased over time. Long-term bonds can be assessed in vivo by the combined evaluation of the microtensile bond strength and SEM morphological examination of the adhesive interface.

  2. Mother-Child Bonding.

    ERIC Educational Resources Information Center

    Pearce, Joseph Chilton

    1994-01-01

    Examines the nature of mother-child bonding from the prenatal stage through early infancy, discussing how the mother's actions, even before birth, stimulate her child's senses. Explains the crucial role that physical contact, breastfeeding, and visual stimuli have on mother-child bonding in human and animal newborns. (MDM)

  3. Interfacial bonding stability

    NASA Technical Reports Server (NTRS)

    Boerio, J.

    1984-01-01

    Interfacial bonding stability by in situ ellipsometry was investigated. It is found that: (1) gamma MPS is an effective primer for bonding ethylene vinyl acetate (EVA) to aluminum; (2) ellipsometry is an effective in situ technique for monitoring the stability of polymer/metal interfaces; (3) the aluminized back surface of silicon wafers contain significant amounts of silicon and may have glass like properties.

  4. Chemical Bonds I

    ERIC Educational Resources Information Center

    Sanderson, R. T.

    1972-01-01

    Chemical bonding is discussed from a bond energy, rather than a wave mechanics, viewpoint. This approach is considered to be more suitable for the average student. (The second part of the article will appear in a later issue of the journal.) (AL)

  5. Covering bottom sediments as a lake restoration technique

    SciTech Connect

    Cooke, G.D.

    1980-10-01

    Application of flyash to lake bottoms as a lake restoration technique is discussed. Flyash application could control microorganisms and sediment nutrients associated with eutrophication; however, use of flyash would present more environmental costs than benefits. PVC-coated screens and spun-bonded polypropylene screens are acceptable, but costly, alternatives to flyash application. Use of sand, clay, or other sheeting to retard eutrophication should be investigated. 28 references, 3 tables.

  6. Tetrel Bonding Interactions.

    PubMed

    Bauzá, Antonio; Mooibroek, Tiddo J; Frontera, Antonio

    2016-02-01

    Tetrel (Tr) bonding is first placed into perspective as a σ-hole bonding interaction with atoms of the Tr family. An sp(3) R4Tr unit has four σ-holes with which a Lewis base can form a complex. We then highlight some inspiring crystal structures where Tr bonding is obvious, followed by an account of our own work. We have shown that Tr bonding is ubiquitous in the solid state and we have highlighted that Tr bonding with carbon is possible when C is placed in the appropriate chemical context. We hope that this account serves as an initial guide and source of inspiration for others wishing to exploit this vastly underexplored interaction.

  7. Wood Bond Testing

    NASA Technical Reports Server (NTRS)

    1989-01-01

    A joint development program between Hartford Steam Boiler Inspection Technologies and The Weyerhaeuser Company resulted in an internal bond analyzer (IBA), a device which combines ultrasonics with acoustic emission testing techniques. It is actually a spinoff from a spinoff, stemming from a NASA Lewis invented acousto-ultrasonic technique that became a system for testing bond strength of composite materials. Hartford's parent company, Acoustic Emission Technology Corporation (AET) refined and commercialized the technology. The IBA builds on the original system and incorporates on-line process control systems. The IBA determines bond strength by measuring changes in pulsar ultrasonic waves injected into a board. Analysis of the wave determines the average internal bond strength for the panel. Results are displayed immediately. Using the system, a mill operator can adjust resin/wood proportion, reduce setup time and waste, produce internal bonds of a consistent quality and automatically mark deficient products.

  8. Shape Bonding method

    NASA Technical Reports Server (NTRS)

    Pontius, James T. (Inventor)

    2010-01-01

    The present invention is directed to a method of bonding at least two surfaces together. The methods step of the present invention include applying a strip of adhesive to a first surface along a predefined outer boundary of a bond area and thereby defining a remaining open area there within. A second surface, or gusset plate, is affixed onto the adhesive before the adhesive cures. The strip of adhesive is allowed to cure and then a second amount of adhesive is applied to cover the remaining open area and substantially fill a void between said first and second surfaces about said bond area. A stencil may be used to precisely apply the strip of adhesive. When the strip cures, it acts as a dam to prevent overflow of the subsequent application of adhesive to undesired areas. The method results in a precise bond area free of undesired shapes and of a preferred profile which eliminate the drawbacks of the prior art bonds.

  9. Microleakage resistance of minimally invasive Class I flowable composite restorations.

    PubMed

    Bonilla, Esteban D; Stevenson, Richard G; Caputo, Angelo A; White, Shane N

    2012-01-01

    Minimally invasive flowable composite Class I restorations are widely used. However, flowable composites are characterized by low filler contents, modified resin formulations, low moduli of elasticity, low viscosity, generally poor mechanical properties, and decreased long-term stability. The purpose of this study was to compare the microleakage resistance of a wide variety of flowable composites used with their manufacturers' recommended bonding systems to that of a long-used and widely studied microhybrid composite when placed as minimally invasive occlusal restorations. Molar teeth were prepared in a standardized manner, restored, artificially aged, stained, sectioned, evaluated, and analyzed. Microleakage varied substantially, by a whole order of magnitude, among the material groups tested. The control group, a conventional microhybrid composite material, leaked significantly less than all the flowable composite groups. Microleakage varied very slightly among measurement site locations. Tiny microscopic bubbles were seen within many of the flowable composite specimens, as were a few voids.

  10. Tape Dump and Restore.

    DTIC Science & Technology

    1980-08-28

    VM/ CMS as provided at Virginia Tech and to make it possible to transfer files from this system to other computer systems , possibly machines using the...Technical Memorandum No. 80-5 DTI(-C August 28, 1980 DEC T.77w S DEC23 1980 F ABSTRACT A set of three programs to write CMS disk files on magnetic...tape in a variety of formats suitable for reading on a variety of computing systems and for restoring these tape files to disk within the restrictions

  11. Ultrasensitive and highly selective detection of bioaccumulation of methyl-mercury in fish samples via Ag⁰/Hg⁰ amalgamation.

    PubMed

    Deng, Li; Li, Yan; Yan, Xiuping; Xiao, Jun; Ma, Cheng; Zheng, Jing; Liu, Shaojun; Yang, Ronghua

    2015-02-17

    Methylmercury (CH3Hg(+)), the common organic source of mercury, is well-known as one of the most toxic compounds that is more toxic than inorganic or elemental mercury. In seabeds, the deposited Hg(2+) ions are converted into CH3Hg(+) by bacteria, where they are subsequently consumed and bioaccumulated in the tissue of fish, and finally, to enter the human diet, causing severe health problems. Therefore, sensitive and selective detection of bioaccumulation of CH3Hg(+) in fish samples is desirable. However, selective assay of CH3Hg(+) in the mercury-containing samples has been seriously hampered by the difficulty to distinguish CH3Hg(+) from ionic mercury. We report here that metal amalgamation, a natural phenomenon occurring between mercury atoms and certain metal atoms, combining with DNA-protected silver nanoparticles, can be used to detect CH3Hg(+) with high sensitivity and superior selectivity over Hg(2+) and other heavy metals. In our proposed approach, discrimination between CH3Hg(+) and Hg(2+) ions was realized by forming Ag/Hg amalgam with a CH3Hg(+)-specific scaffold. We have found that Ag/Hg amalgam can be formed on a CH3Hg(+)-specific DNA template between silver atoms and mercury atoms but cannot between silver atoms and CH3Hg(+). With a dye-labeled DNA strand, the sensor can detect CH3Hg(+) down to the picomolar level, which is >125-fold sensitive over Hg(2+). Moreover, the presence of 50-fold Hg(2+) and 10(6)-fold other metal ions do not interfere with the CH3Hg(+) detection. The results shown herein have important implications for the fast, easy, and selective detection and monitoring of CH3Hg(+) in environmental and biological samples.

  12. Effects of dentin depth and cavity configuration on bond strength.

    PubMed

    Yoshikawa, T; Sano, H; Burrow, M F; Tagami, J; Pashley, D H

    1999-04-01

    During polymerization of resin composites, shrinkage stresses compete with resin-dentin bonds in a manner that can cause failure of the bond, depending upon the configuration of the cavity, its depth, and the restorative technique. The hypothesis tested in this study was that the effect of cavity configuration (C) and remaining dentin thickness (RDT) influence resin bond strength to the dentin of Class I cavity floors. The occlusal enamel was ground to expose a flat superficial dentin surface as a control (superficial dentin, C-factor = 1) in human extracted third molars. Cavities 3 mm long x 4 mm wide were prepared to a depth 2 mm below the ground dentin surfaces (deep dentin within cavity floor, C-factor = 3). To assess the relationship between C-factor and RDT, we removed the walls of cavities, making a deep flat surface for bonding (deep dentin, C-factor = 1). The teeth were restored with either Clearfil Liner Bond II (LB II), One-Step (OS), or Super-Bond D Liner (DL), followed by Clearfil Photo Posterior resin composite. After 24 hrs' storage in water, the teeth were sectioned vertically into 3 or 4 slabs (0.7 mm thick) and trimmed for the micro-tensile bond test so that we could determine the strength of the resin bonds to the pulpal floor. All groups gave high bond strengths to superficial dentin, but OS and DL gave significantly lower bond strengths to flat deep dentin when the C-factor was 1. When the C-factor was increased to 3 by the creation of a three-dimensional cavity preparation, the bond strengths of all materials fell (range, 21 to 35%), but the difference was significant (p < 0.05) only with DL. SEM observations of failure patterns showed that specimens with high bond strengths tended to exhibit cohesive failures within the hybrid layer, while specimens exhibiting low bond strengths showed failures at the top of the hybrid layer. Some adhesives do not bond well to deep dentin, making them more susceptible to polymerization shrinkage stress that

  13. Effect of adhesive layers on microshear bond strength of nanocomposite resin to dentin

    PubMed Central

    Ebrahim, Mohamed I.

    2017-01-01

    Background Bond strength of adhesive layer can absorb unwanted stresses of polymerization shrinkage in composite resin restorations; increased microshear bond strength can prevent failure of restoration materials, the purpose of this study was to evaluate the effect of adhesive layers on microshear bond strength of nanocomposite resin to dentin. Material and Methods Two different types of adhesive systems: universal adhesive (ExciTE) and newly developed adhesive (Nano-Bond), and one type of light-cured resin restorative material (Nanocomposite resin) were used in this study. The occlusal surfaces of extracted human molar teeth were ground perpendicular to the long axis of each tooth to expose a flat dentin surface. The adhesives were applied on dentin surfaces (single application or double application). Nanocomposite resin was then placed and light cured for 40 seconds. After 24 hours of immersion in water at 37°C, then subjected to thermocycling before testing, a microshear bond test was carried out. The data were analyzed by a two-way ANOVA. For comparison between groups, Tukey’s post-hoc test was used. Results The mean bond strengths of ExciTE and Nano-Bond adhesives with a single application were 8.8 and 16.6 MPa, respectively. The mean bond strengths of ExciTE and Nano-Bond adhesives with double application were 13.2 and 21.8MPa, respectively. There were no statistically significant differences in microshear bond strengths between the single application of Nano-Bond and the double application of ExciTE adhesives. Conclusions Microshear bond strength increased significantly as the applied adhesive layer was doubled. Key words:Adhesive, microshear, bond, strength, nanocomposite. PMID:28210433

  14. Cytogenetic genotoxic investigation in peripheral blood lymphocytes of subjects with dental composite restorative filling materials.

    PubMed

    Pettini, F; Savino, M; Corsalini, M; Cantore, S; Ballini, A

    2015-01-01

    Dental composite resins are biomaterials commonly used to aesthetically restore the structure and function of teeth impaired by caries, erosion, or fracture. Residual monomers released from resin restorations as a result of incomplete polymerization processes interact with living oral tissues. The objective of this study was to evaluate the genotoxicity of a common dental composite material (Enamel Plus-HFO), in subjects with average 13 filled teeth with the same material, compared to a control group (subjects having neither amalgam nor composite resin fillings). Genotoxicity assessment of composite materials was carried out in vitro in human peripheral blood leukocytes using sister-chromatid exchange (SCE) and chromosomal aberrations (CA) cytogenetic tests. The results of correlation and multiple regression analyses confirmed the absence of a relationship between SCE/cell, high frequency of SCE(HFC) or CA frequencies and exposure to dental composite materials. These results indicate that composite resins used for dental restorations differ extensively in vivo in their cytotoxic and genotoxic potential and in their ability to affect chromosomal integrity, cell-cycle progression, DNA replication and repair.

  15. A Comparative Electrochemical Behaviour Study and Analytical Detection of the p-Nitrophenol Using Silver Solid Amalgam, Mercury, and Silver Electrodes

    PubMed Central

    De Souza, Djenaine; Mascaro, Lucia H.; Fatibello-Filho, Orlando

    2011-01-01

    This work reports a comparative electrochemical behaviour study and p-nitrophenol analytical detection using silver solid amalgam, hanging dropping mercury, and silver electrodes. For this, square wave voltammetry was employed, where the analytical responses and the redox mechanisms could be compared for reduction processes of 4-nitrophenol by analysis of the voltammetric responses. The analytical performance of the electrode was evaluated and detection and quantification limits, recovery percentages, repeatability, and reproducibility for the silver solid amalgam and hanging dropping mercury electrodes presented similar values; the results presented for the silver electrode indicated worse analytical parameters than the other electrodes. The results indicate that the silver solid amalgam electrode can be considered a suitable tool and an interesting alternative for the analytical determination of 4-nitrophenol, as well as for the determination of other biological and environmentally interesting compounds that present analytical responses on mercury surfaces. PMID:21647286

  16. Rapid communication: acute exposure to mercury from dental amalgam does not affect the levels of C-reactive protein or interleukin-6 in peripheral blood.

    PubMed

    Sandborgh-Englund, Gunilla; af Geijersstam, Eric; Loftenius, Annika

    2003-03-28

    In a previous study, a significant increase in serum interleukin-6 (IL-6) was apparent after an acute low-level mercury (Hg) exposure, achieved by removal of amalgam fillings (Loftenius et al., 1998). In the present study, 11 healthy volunteers were exposed to an oral dose of 1 g of pulverized amalgam powder. Hg, IL-6, and C-reactive protein (CRP) levels in plasma were followed before and up to 72 h after exposure. The Hg levels were low and stable prior to exposure and increased rapidly after exposure. The median Hg increase was 12.9 nmol/L, which is considerably higher than in the previous study. No significant change over time was observed for IL-6 and CRP levels. Therefore, it cannot be ruled out that our previous finding of increasing IL-6 levels detected after acute low-level Hg exposure through removal of amalgam fillings was due to the dental treatment per se.

  17. The Halogen Bond.

    PubMed

    Cavallo, Gabriella; Metrangolo, Pierangelo; Milani, Roberto; Pilati, Tullio; Priimagi, Arri; Resnati, Giuseppe; Terraneo, Giancarlo

    2016-02-24

    The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is now, and, perhaps, where it is going. The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design.

  18. The Halogen Bond

    PubMed Central

    2016-01-01

    The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is now, and, perhaps, where it is going. The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design. PMID:26812185

  19. Limitations in bonding to dentin and experimental strategies to prevent bond degradation.

    PubMed

    Liu, Y; Tjäderhane, L; Breschi, L; Mazzoni, A; Li, N; Mao, J; Pashley, D H; Tay, F R

    2011-08-01

    The limited durability of resin-dentin bonds severely compromises the lifetime of tooth-colored restorations. Bond degradation occurs via hydrolysis of suboptimally polymerized hydrophilic resin components and degradation of water-rich, resin-sparse collagen matrices by matrix metalloproteinases (MMPs) and cysteine cathepsins. This review examined data generated over the past three years on five experimental strategies developed by different research groups for extending the longevity of resin-dentin bonds. They include: (1) increasing the degree of conversion and esterase resistance of hydrophilic adhesives; (2) the use of broad-spectrum inhibitors of collagenolytic enzymes, including novel inhibitor functional groups grafted to methacrylate resins monomers to produce anti-MMP adhesives; (3) the use of cross-linking agents for silencing the activities of MMP and cathepsins that irreversibly alter the 3-D structures of their catalytic/allosteric domains; (4) ethanol wet-bonding with hydrophobic resins to completely replace water from the extrafibrillar and intrafibrillar collagen compartments and immobilize the collagenolytic enzymes; and (5) biomimetic remineralization of the water-filled collagen matrix using analogs of matrix proteins to progressively replace water with intrafibrillar and extrafibrillar apatites to exclude exogenous collagenolytic enzymes and fossilize endogenous collagenolytic enzymes. A combination of several of these strategies should result in overcoming the critical barriers to progress currently encountered in dentin bonding.

  20. Limitations in Bonding to Dentin and Experimental Strategies to Prevent Bond Degradation

    PubMed Central

    Liu, Y.; Tjäderhane, L.; Breschi, L.; Mazzoni, A.; Li, N.; Mao, J.; Pashley, D.H.; Tay, F.R.

    2011-01-01

    The limited durability of resin-dentin bonds severely compromises the lifetime of tooth-colored restorations. Bond degradation occurs via hydrolysis of suboptimally polymerized hydrophilic resin components and degradation of water-rich, resin-sparse collagen matrices by matrix metalloproteinases (MMPs) and cysteine cathepsins. This review examined data generated over the past three years on five experimental strategies developed by different research groups for extending the longevity of resin-dentin bonds. They include: (1) increasing the degree of conversion and esterase resistance of hydrophilic adhesives; (2) the use of broad-spectrum inhibitors of collagenolytic enzymes, including novel inhibitor functional groups grafted to methacrylate resins monomers to produce anti-MMP adhesives; (3) the use of cross-linking agents for silencing the activities of MMP and cathepsins that irreversibly alter the 3-D structures of their catalytic/allosteric domains; (4) ethanol wet-bonding with hydrophobic resins to completely replace water from the extrafibrillar and intrafibrillar collagen compartments and immobilize the collagenolytic enzymes; and (5) biomimetic remineralization of the water-filled collagen matrix using analogs of matrix proteins to progressively replace water with intrafibrillar and extrafibrillar apatites to exclude exogenous collagenolytic enzymes and fossilize endogenous collagenolytic enzymes. A combination of several of these strategies should result in overcoming the critical barriers to progress currently encountered in dentin bonding. PMID:21220360