ObjectivesThis study evaluated the influence of the cavity configuration factor ("C-Factor") and light activation technique on polymerization contraction forces of a Bis-GMA-based composite resin (Charisma, Heraeus Kulzer). Material and MethodsThree different pairs of steel moving bases were connected to a universal testing machine (emic DL 500): groups A and B - 2x2 mm (CF=0.33), groups C and D - 3x2 mm (CF=0.66), groups e and F - 6x2 mm (CF=1.5). After adjustment of the height between the pair of bases so that the resin had a volume of 12 mm3 in all groups, the material was inserted and polymerized by two different methods: pulse delay (100 mW/cm2 for 5 s, 40 s interval, 600 mW/cm2 for 20 s) and continuous pulse (600 mW/cm2 for 20 s). Each configuration was light cured with both techniques. Tensions generated during polymerization were recorded by 120 s. The values were expressed in curves (Force(N) x Time(s)) and averages compared by statistical analysis (ANOVA and Tukey's test, p<0.05). Results: For the 2x2 and 3x2 bases, with a reduced C-Factor, significant differences were found between the light curing methods. For 6x2 base, with high C-Factor, the light curing method did not influence the contraction forces of the composite resin. ConclusionsPulse delay technique can determine less stress on tooth/restoration interface of adhesive restorations only when a reduced C-Factor is present.
Evaluation of the influence of chemical agents before applying Self-etching Adhesives on dentin Bond Strength With the Self-etching adhesives, acid-etching with phosphoric acid has to be dispensed in dentin. Than, other solutions have been proposed in order to promote the cavity cleaner and improvement in bonding effectiveness. The aim of this study was to investigate the microshear bond strength, with the influence of chemical solutions and time, in three adhesive systems used on bovine dentin. Two hundred and forty bovine incisors were included, and the surface was polished in series with silicon carbide paper, getting flattened dentin surface of 10 mm in diameter. The specimens were randomly divided into four groups, according to the applied solution: SF-saline solution with 0.9% NaCl (control group), HS-deproteinization with sodium hypochlorite at 5%, for 2 minutes and HSAA-sodium hypochlorite 5% for 2 minutes followed by the application of ascorbic acid (ascorbate) and 10% for 1 minute;CHXapplication of chlorhexidine solution (2% for 1 minute). Were applied to surfaces prepared three adhesive systems, per group-Optibond All-in-One (Kerr), Filtek-P90 System Adhesive (3M-ESPE) and Adper SE (3M-ESPE), all followed by the insertion of composite resin (Filtek Z250 and Filtek P90). Half of the specimens of each group / treatment were stored for 24 hours and half for six months. After these periods were tested using the microshear in a universal testing machine (Emic, the speed of 0.5 mm / min). Results were submitted to three way ANOVA and TUKEY test multiple comparison both considering α = 0.05. The adhesive Filtek P90 System Adhesive was the one who kept the bond strength after aging, however, the two surface treatments containing sodium hypochlorite influenced negatively. With chlorhexidine, there was no statistically significant difference compared to the control group. The adhesive OptiBond All-in-One (Kerr) was affected by the sodium hypochlorite, sodium hypochlorite more ascorbate, at 24 hours. As a result of iqual with aging in aqueous solution. Adper SE (3M-ESPE) was influenced by the treatments using sodium hypochlorite. The best result, comparing two treatments with hypochlorite, after aging, was obtained by treatment with sodium hypochlorite more ascorbate was statistically identical to the control group. It was concluded that the influence of surface treatments on bond strength of adhesives tested. The chlorhexidine resulted in better results in almost every test.
Dental diastemas are common findings at dental clinics. This clinical situation produces discomfort in many patients and its solution is difficult to many professionals. Silicone guides, made from waxed casts, have been used to assist the stratification of resin composites in cases of dental diastemas. This technique, however, does not necessarily need to be used as protocol in all situations. Objective: To demonstrate the stratification technique without silicone guides. Case report:The present study reports a case of stratification technique for anterior diastemas closure without silicone guide. Conclusion: The closure of diastemas can be quickly and easily performed using composite resins without the need of previously manufacturing silicone guides.
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