Effect of adhesive systems and bevel on enamel margin integrity in primary and permanent teeth

Purpose: This study compared the effectiveness of self-etch and total-etch adhesive systems in bonding to the beveled and nonbeveled margins of primary and permanent teeth. Methods: This in vitro, factorial-designed study allowed evaluation of 3 factors: (1) tooth type; (2) presence of a bevel; and (3) adhesive type. Two preparations, each including a beveled and nonbeveled margin, were completed on buccal surfaces of 60 extracted molars (30 primary and 30 permanent). Preparations were randomly assigned to self-etch or a total-etch adhesive system and restored with resin composite. After thermocycling, teeth were stained with silver nitrate, sectioned, and measured for microleakage. Statistical analysis used a repeated measures analysis of variance. Results: Beveled margins had less microleakage than nonbeveled margins for primary and permanent teeth (P<.001). Total-etch had less microleakage than self-etch adhesives on primary (53% less, P<.001) and on permanent teeth (22% less, P=.01). Self-etch had considerably more microleakage when enamel margins were not beveled. Comparably less microleakage, however, was found for total-etch and self-etch in restorations with beveled margins. Conclusions: Total-etch adhesive and beveled margins resulted in the least microleakage. Margin beveling has a greater effect in minimizing microleakage than the type of adhesive used.