Marginal adaptation of composite resin-restored dentinal cavities

Cervical cavities were prepared in the dentin of intact, extracted premolars and randomly restored with four combinations of three bonding agents and two composite resins. After storage in water, thermocycling, and exposure to a fluorescent dye, specimens exhibiting gross marginal leakage and sealing were selected. The tooth was decalcified and the surface of the composite resin restorations opposite the cavity wall and floor were examined for adaptation between restoration and cavity surface. Both leaking and sealed specimens displayed well-replicated bur indentations on the resin surface, indicating adaptation between cavity surface and restoration. Porosities and voids were present on all restorations, but no single feature was identified that was responsible for sealing or leakage. Although suitable contact was achieved in all cases between the restoration and dentinal cavity, this did not indicate that the restoration could sustain a seal under the experimental conditions of this study.