Immediate and long-term microshear bond strength of resin-based cements to core build-up materials

To evaluate the microshear bond strength (?-SBS) between resin-based cements and core build-up materials after water storage. Material and Methods: Cylinders (1x1 mm) of conventional dual-cure resin cement (RelyX ARC, 3M ESPE), universal du

Dentin microhardness during and after whitening treatments

Objective: This in vitro study aimed to evaluate the effect of bleaching agents on dentin microhardness during and after bleaching. Method and materials: Specimens were randomly assigned to seven groups (n = 15): Nite White Excel 2 Z [NW] 10% and 22%; Rembrandt [REM] 10% and 22%; Opalescence [OPA] 10% and 20%; and a placebo agent. The 42-day whitening treatment consisted of daily application of the agents to the dentin surfaces for 8 hours, followed by immersion in artificial saliva for 16 hours. After the bleaching treatment, specimens were kept immersed in artificial saliva for 14 days. Microhardness was measured at baseline, 8 hours, and 7, 14, 21, 28, 35, and 42 days of bleaching and during the posttreatment period (7 and 14 days). Results: The analysis of variance for split-plot showed a significant effect on the interaction between bleaching agent and time. Tukey's test and regression analyses revealed that during the bleaching period, the agents NW 10%, NW 22%, and OPA 20%, which did not differ from each other, did not alter dentin microhardness, showing constant microhardness values. There were no differences among REM 10%, REM 22%, and OPA 10%, which showed significant reductions in microhardness after day 14 compared to other agents. After bleaching procedures, there was an increase in dentin microhardness for all groups. Conclusion: Throughout the bleaching treatment, depending on the agent applied, dentin showed a transitory decrease in microhardness values. In the posttreatment period, artificial saliva presented a remineralizing effect on the bleached surfaces

Composite surfaces after finishing and polishing techniques

Purpose: To evaluate the effect of finishing and polishing techniques on surface roughness of resin-based composites (RBCs). Materials and Methods: Forty specimens of each material were cured under Mylar strips and immersed in artificial saliva for 1 wk. Samples were tested with a profilometer to obtain baseline average surface roughness (Ra). Specimens of both RBCs were then finished and polished according to four techniques: (1) Sof-Lex disks; (2) Sof-Lex disks followed by Prisma Gloss; (3) Enhance points; (4) Enhance points followed by Prisma Gloss application. New readings of the roughness pattern were carried out and the difference of post-polishing and baseline values were analyzed. Results: ANOVA test (alpha= 0.05) did not show differences between materials (P= 0.9393) nor interaction effects (P= 0.3094), but significant difference among the finishing/polishing techniques were detected (P= 0.0157). Tukey's test showed that the smoothest surface was obtained when the specimens were treated by Sof-Lex followed by Prosma Gloss polishing paste; and the worst results were obtained after using Enhance points alone

Abrasive wear on eroded root dentine after different periods of exposure to saliva in situ

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOThe effect of salivary exposure time on the abrasive wear of acid-eroded dentine was evaluated in situ. One-hundred and twenty bovine root dentine slabs were randomly assigned into six groups (A-F) and placed in intraoral palatal devices, which were worn by 10 volunteers for 4 d. On the first day, no erosive/abrasive procedures were carried out. On the following 3 d, erosive challenges were performed extraorally, two times per day, by immersing the device for 90 s in a soft drink. Subsequently, the group A specimens were immediately brushed (40 strokes), and the others were brushed after the following times: B, 20 min; C, 40 min; and D, 60 min. Group E specimens were only acid-eroded and those of group F were only brushed. Dentine wear was measured with a profilometer. ANOVA and Dunnett's test showed that groups A-D did not differ statistically from the control group E but differed from the control group F. The lowest mean value was found for group F. Regression analysis was unable to show salivary effect on dentine wear reduction. The data suggest that the exposure time of saliva of up to 60 min has no effect on reducing the eroded dentine wear by toothbrushing1115423427FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO2000/14278-