Marginal adaptation of Class 5 composite restorations: retention grooves versus enamel and dentin bonding

Microleakage was assessed in class 5 composite resin restorations placed in extracted noncarious human premolar teeth. The occlusal enamel cavo-surface margins of the class 5 cavity preparations had been beveled and etched with phosphoric acid gel for 30 seconds. The teeth were divided into four equal groups. The first group was only restored with the composite filling material, while in the second group, a mechanically cut undercut grooves were done before restoration. In the third group, a dentin bonding agent was used before restoration, while in the fourth group, the dentin bonding agent was used in conjunction with undercut grooves. The restored teeth were placed in methylene blue dye, invested and sectioned. The extent of dye penetration along the tooth-restoration interface was compared. The group restored in cavities with undercut grooves alone showed the greatest leakage. Leakage was statistically significantly greater than in the groups restored in conjunction with dentin bonding. The tooth restoration interface at the gingival margin showed severe leakage than did at the occlusal margin.