Acid etching and composite resin restorations. A culturing and histologic study bacterial penetration

Class‐V cavities were prepared on the buccal surfaces of homologous pairs of premolars in vivo. Composite resin restorations (Adaptic®) were performed using two different acid‐etch techniques. All cavities were unlined. Four cavities were unetched and served as controls. In one series the enamel margins were etched and a non‐composite intermediate resin was used before filling. In the second series the enamel surrounding the composite filling was etched after the insertion of the composite resin and coated with an UV‐light polymerized resin (Nuva‐Seal®). The results were evaluated using both histological and culturing techniques. Neither of the two etching techniques was effective in preventing marginal leakage and in growth of bacteria was found along the cavity walls. The cervical border of the Class‐V cavity is considered a weak link for marginal leakage. Culturing revealed a bacterial flora resembling that of dental plaque.