Microleakage of a single-bottle adhesive system with 3 restorative materials: in vitro study and clinical considerations.

The purpose of this study is to evaluate whether differences in material composition between 3 restoratives (compomer, packable composite, and amalgam) affect microleakage in class II preparations. Class II cavity preparations were made in the mesial and distal surfaces of a noncarious human premolar with the gingival margins in dentin. Preparations were etched and rinsed, and a single-bottle adhesive agent (Prime & Bond NT) was applied. Preparations were restored with the following materials (n = 8 per group): Dyract AP, SureFil, and Dispersalloy. For Dyract AP total-bond restorations, a new nonrinse conditioner (NRC) was tested against a total-etch with 36% phosphoric acid. Specimens were coated with nail varnish, immersed in toluidine blue for 24 hours, and evaluated for dye penetration, after removal of the restorative material, using a 0-to-4 scale. Statistical analysis using analysis of variance revealed significantly higher leakage scores (P < .05) for the NRC-Dyract AP group when compared with all other groups. Dispersalloy had significantly lower scores compared with Dyract AP and SureFil, all with the total-etch bonding technique. No statistically significant difference was observed between the latter 2 groups. The inability of all 3 materials to create a perfect seal in vitro raises concerns about the ability of the adhesive system to provide completely sealed restorations in vivo. However, bonded amalgam restorations are more effective in reducing marginal microleakage, particularly at the dentinal margin.