In vitro Evaluation of the Effect of Reinforcement with Fiberglass in Class I Restorations with Composite Resin

Marginal microleakage is one of the major disadvantages of resin composite restorations. The purpose of this study was to evaluate in vitro the effect of reinforcement with fiberglass in Class I restorations with composite resin on the marginal microleakage.The sample was composed by 30 human third molars, which were divided into 3 groups: G1 (no fiberglass – control group), G2 (1 layer of fiberglass) and G3 (2 layers of fiberglass). The restorations were subjected to a total of 300 thermal cycles and were immersed in solution of methylene blue 2%. The analysis of microleakage was performed in a stereomicroscope and measured Data were analyzed statistically by the Chi-square and ANOVA tests at 5% significance level. G3 presented the lower infiltration index, but it was not statistically significant (p>0.05), indicating that use of fiberglass did not appears effective against microleakage. Although the use of layers of fiberglass slightly reduces polymerization shrinkage, the incremental technique seems to be more viable clinically.

Influence of water storage time on the bond strength of etch-and-rinse and self-etching adhesive systems

The purpose of this study was to evaluate comparatively the shear bond strength (SBS) of etch-and-rinse (Adper Scotch Bond Multi Purpose - ASBMP and Adper Single Bond 2 - ASB2) and self-etching (AdheSe -AD and Adper Prompt - AP) adhesive systems after short- and long-term water storage. Eighty bovine teeth were randomly assigned to 4 groups (n=20, 10 teeth for 24 h and 10 for 6 months). After surface treatment, composite resin cylinders were made with Tetric Ceram using a bisected metallic matrix. The specimens were stored in distilled water at 37°C for either 24 h or 6 months. After these periods, shear strength was assessed in a universal testing machine (0.5 mm/min). Data were submitted to ANOVA and F test at 5% significance level. Mean SBSs (MPa) for ASBMP (10.03 ± 3.78) and ASB2 (6.10 ± 2.67) showed no statistically significant differences (p>0.05) between times. The self-etching systems did not differ significantly from each other within the 24-h period, but significant difference was found for AD (1.37 ± 0.64) after 6 months of water storage. In conclusion, the tested etch-and-rinse systems had a better performance in terms of bond durability over time than the self-etching systems.