High frequency ultrasonic agitation of self-etch adhesives

Objectives: The aim of this study is to investigate the effect of high frequency ultrasonic agitation on the microtensile bond strengths of different self-etch adhesives. Methods: Thirty-six human molars were wet-ground occlusally until dentin was exposed. Clearfil S³ Bond, G-Bond and Futurabond NR, one-step self-etch adhesives, were used in this study. In control groups, bonding procedures were performed according to the manufacturer's instructions. In the experimental groups, bonding materials were applied with a 1 MHz therapeutic ultrasonic device at the recommended time. Composite crown was built up incrementally to dentin up to 5 mm height. Each tooth was serially sectioned into rectangular beams. The specimens were subjected to microtensile testing. Failure modes were observed with a stereomicroscope and classified. Randomly selected specimens from each group were observed with SEM. Results: Two-factor ANOVA indicated that both factor; adhesive system and ultrasonic agitation effect on bond strength (p<0.05). The bond strengths of G-Bond adhesive to dentin was increased after ultrasonic agitation (p<0.05), whereas ultrasonic agitation of Futurabond and 3S Bond did not effect on bond strength values (p>0.05) (Table 1). All tested groups showed predominantly adhesive failure patterns. But G-Bond after ultrasonic agitation group revealed also some adhesive failures associated with partial cohesive failure in the dentin. Conclusion: High frequency ultrasonic agitations of self etch adhesives during their applications may enhance their bonding performance.

Table1. The mean values (and Standard Deviation) of all tested groups