Influence of bioactive materials used on the dentin surface whitened with carbamide peroxide 16%

This study investigated the influence of bioactive materials on the dentin surface whitened. MATERIAL AND METHODS: Three bovine teeth were shaped into three dentin wafers. Each wafer was then sectioned, into six dentin slices. One slice from each tooth was distributed into one of 6 groups: 1.CG = control group (distilled water); 2.WT = whitening treatment; 3.WT + MI Paste Plus, applied once a day; 4.WT + Relief ACP30, applied once a day for 30 mintes; 5.WT + Relief ACP60, applied once a day for 60 minutes; 6.WT + Biosilicate®, applied once a week. All groups were treated over 14 days. RESULTS: CG presented all dentinal tubules occluded by smear layer; WT group was observed all dentinal tubules opened. In the groups 3, 4 and 6, tubules were occluded. Group 5, dentinal tubules were completely occluded by mineral deposits. CONCLUSION: The use of bioactive materials immediately after whitening treatment can reduce or even avoid the demineralization effect of whitening and avoid exposing dentinal tubules

Influência do tempo de armazenamento na microinfiltração de restaurações de resina composta: avaliação qualitativa e quantitativa

Objetivou-se verificar a influência do tempo de armazenamento (24 horas ou 3 meses) no selamento marginal de restaurações de classe II e, além disso, verificar a correlação entre dois métodos de obtenção dos resultados nos testes de microinfiltração. Cavidades classe II foram confeccionadas em molares humanos íntegros, sendo as cavidades MO restauradas com ABF experimental (Kuraray Medical Inc.) + Z250 (3M ESPE) e as DO, com Single Bond (3M ESPE) + Z250. Após os diferentes tempos de armazenamento, empregou-se uma metodologia para provocar microinfiltração (ciclagem térmica e corante azul de metileno 0,5% por 4 horas) e os corpos-de-prova foram seccionados em 3 fatias. Três avaliadores calibrados atribuíram escores conforme o grau de infiltração, e também foram realizadas medidas morfométricas com ajuda do software ImageLab 2000. A análise de regressão de Pearson mostrou correlação altamente significante entre os valores obtidos pelos dois métodos de avaliação (r = 0,978, p < 0,001). Constatou-se que o adesivo ABF experimental apresentou menor infiltração marginal em relação ao adesivo Single Bond (p < 0,001), sendo que o tempo de armazenamento não influenciou no comportamento dos adesivos.The aim of this study was to evaluate the influence of storage periods of 24 hours and 3 months on the microleakage of class II cavities. Two methods of assessing microleakage were also compared. Class II cavities were prepared in sound human molars. MO cavities were restored using ABF experimental (Kuraray Medical Inc.) + Z250 composite resin (3M ESPE), and DO cavities were restored using Single Bond (3M ESPE) + Z250. After different storage periods, specimens were thermocycled, immersed in a dye (0.5% methylene blue solution for 4 h) and longitudinally sectioned. Dye penetration was scored according to a 0-4 scale. The extent of microleakage was measured using the ImageLab 2000 program. A statistically significant correlation was verified between both evaluation methods (r = 0.978, p < 0.001). ANOVA revealed a statistically significant difference between the tested adhesive systems regarding microleakage (p < 0.001), although it was not influenced by the different storage periods

Influence of load cycling on marginal microleakage with two self-etching and two one-bottle dentin adhesive systems in dentin

PURPOSE: To evaluate the influence of occlusal load cycling on cervical microleakage of proximal slot restorations located in dentin, using two self-etching and two one-bottle dentin adhesive systems. MATERIALS AND METHODS: 240 proximal slot cavities were prepared in 120 bovine teeth and divided into two groups, one with load cycling and one without. The groups were then subdivided into four subgroups according to the adhesive system used (Experimental EXL 547 Self-etching 3M, Clearfil SE Bond, Single Bond, and Optibond Solo Plus) and restored following the manufacturers' instructions. The teeth were then submitted to mechanical load cycling with a force of 80 N and a frequency of 5 Hz, simultaneously over both restorations of each tooth, for a total of 50,000 cycles per specimen. All specimens were subsequently immersed in a 2% methylene blue solution (pH 7.0), and sectioned to examine the extent of dye penetration under a stereomicroscope (40X). RESULTS: There was no statistically significant difference (p = 0.00002) between the loaded and unloaded teeth. However, a statistically significant difference was observed between the adhesive systems used. The experimental self-etching EXL 547 presented the lowest mean microleakage, but was only statistically significantly different from the Single Bond loaded and unloaded groups and the Clearfil SE Bond unloaded group. CONCLUSION: The application of 50,000 loading cycles did not affect the microleakage of the two self-etching and the two one-bottle adhesive systems evaluated. In vitro mechanical load cycling is an important factor to consider when evaluating the performance of adhesive systems under simulated masticatory conditions

Measuring Bond Strength Between Fiber Post and Root Dentin: A Comparison of Different Tests

Purpose The aim of this study was to evaluate the ability of bond strength tests to accurately measure the bond strength of fiber posts luted into root canals Materials and Methods The test methods studied were hourglass microtensile (HM), push-out (PS), modified push out (MP) and pull out (PL) The evaluated parameters were bond strength values, reliability (using Weibull analysis), failure mode (using confocal microscopy), and stress distribution (using finite element analysis) Forty human intact single rooted and endodontically treated teeth were divided into four groups Each group was assigned one of the test methods The samples in the HM and PS groups were 1 0 +/- 0 1 mm thick, the HM samples were hourglass shaped and the PS samples were disk shaped For the PL and MP groups, each 1 mm dentin slice was luted with a fiber post piece Three dimensional models of each group were made and stress was analyzed based on Von Mises criteria Results PL provided the highest values of bond strength followed by MP both of which also had greater amounts of adhesive failures PS showed the highest frequency of cohesive failures MP showed a more homogeneous stress distribution and a higher Weibull modulus Conclusion The specimen design directly influences the biomechanical behavior of bond strength test