Effect of accelerated restorative techniques on the microleakage of Class II composites.

PURPOSE: To assess the marginal seal of Class II resin-based composite restorations cured by a high intensity halogen light or a plasma arc light. MATERIALS AND METHODS: Class II cavities were prepared in extracted molar teeth with cervical margins located apical to the cemento-enamel junction. Cavities were restored with a posterior resin-based composite (Tetric Ceram) using either a two-increment or a bulk placement and cure restorative technique after application of bonding agent (Excite). Test parameters included light unit type/curing mode, application of flowable composite and restorative technique. After thermocycling, the teeth were immersed in basic fuchsin dye. Sectioned restorations were examined under a stereomicroscope (x 25) and extent of microleakage (mm) was recorded using an image analysis system. Data was analyzed by non-parametric statistical tests. RESULTS: No leakage was observed at the occlusal enamel margin of a nyrestoration. Median gingival leakage values for the different test groups ranged from 0.02-2.51 mm. Light unit type had a highly significant effect on leakage (P=0.0002). The highest leakage scores were recorded with the plasma arc light used in standard curing mode and the lowest with the halogen light in turbo-boost mode.

Effects of grit blasting and silanization on bond strengths of a resin luting cement to Belleglass HP indirect composite.

PURPOSE: To investigate the extent of bonding possible of a resin luting cement with three opacities of Belleglass HP, representing different filler type and loading levels in a highly cross-linked resin matrix. MATERIALS AND METHODS: Belleglass HP (3 opacities: opaque dentin, translucent dentin, cuspal enamel) was prepared as solid notched discs (Group A) or luted halves to create notched discs (Groups B-F). Luted samples were split through the notch on the Instron for conditions: as-is after molding (B), grit blasted with 50 microm Al2O3 (C), grit blasted and silanated (D) grit blasted, silanated, and stored 1 week (E), and grit blasted and treated with Artglass liquid (F). All the samples were stored in distilled water at 37 degrees C for 24 hours before testing. The fractured surfaces were examined by light and scanning electron microscopy (SEM) to assess the effect of the surface treatments. RESULTS: The mean fracture resistance (+/- S.D) of the tested groups ranged from 7.6 (+/- 1.9 N mm(-1)) for Group A to 13.9 (+/- 5.4 N mm(-1)) for Group D. Two-way analysis of variance showed no significant interaction (P>0.05) between product opacities & surface treatments. The bonded inlay test halves in Groups B and C failed adhesively between the inlay test halves and the luting cement whereas the other three test groups (D,E,F) failed cohesively in the luting cement. One-way analysis of variance with post-hoc paired group Tukey testing revealed that Group D (13.9 +/- 5.4 N mm(-1)) performed significantly better (P<0.05) than Groups A (7.6 +/- 1.9 N mm(-1), B (9.2 +/- 3.7 N mm(-1)) or C (7.8 +/- 1.6 N mm(-1)). No statistical difference was found between Groups D to F (P>0.05).