A radiographic and scanning electron microscopic study of approximal margins of Class II resin composite restorations placed in vivo

Introduction: Clinical studies on the quality of Class II amalgam and resin composite restorations frequently report defective cervical margins. Aim: The aim of this study was to evaluate the quality of the approximal margins of Class II resin composite restorations placed in vivo using various application techniques and adhesive systems. Materials and Methods: Class II restorations were placed in premolar teeth in vivo, using different adhesive systems and application techniques. After extraction of the teeth, the restorations were evaluated radiographically and by SEM. Results: One-hundred and forty-four resin composite Class II restorations were evaluated. According to the radiographs, 4% of the restorations were overfilled and 33% were underfilled. SEM pictures revealed that 43% of the restorations were overfilled and 25% underfilled. Thirty-two per cent of the restored teeth showed a flash of bonding agent on the approximal surface. Conclusions: Class II resin composite restorations placed in vivo may be found frequently to show imperfect cervical margins. Overextended margins observed by SEM are difficult to detect on radiographs. When seen on a radiograph, a thick layer of bonding agent may be interpreted as an underfilled restoration.