Influence of reduced application time on bonding durability of universal adhesives to demineralized enamel

Abstract

Objectives This study aimed to assess the effect of application time on the microshear bond strength (mu SBS) of three universal adhesives in demineralized and sound enamel before and after aging.

Materials and methods Bovine teeth (192) were prepared where buccal surfaces were ground and divided into two groups (sound enamel and demineralized enamel). The specimens in each group were divided into 12 subgroups by combining 3 adhesive agents (All-Bond Universal, Scotchbond Universal, and Tokuyama Universal Bond) x 4 adhesion strategy. Each adhesive was applied with either prolonged (PA) or reduced (RA) application time in etch-and-rinse or self-etch mode. Bonded composites were subjected to mu SBS testing after 24-h or 2-year water storage. The results were evaluated using four-way ANOVA and Tukey's post-hoc test (alpha = 0.05).

Results The mu SBS of adhesives to sound enamel in both etching modes was mostly similar to demineralized enamel, regardless of application time and aging time. At 24-h, all adhesives with PA in self-etch mode showed higher mu SBS when compared with RA, except Tokuyama Universal Bond, but after 2-year aging, no significant difference was found in mu SBS between RA and PA. The mu SBS of adhesives with PA in etch-and-rinse mode depended on used adhesive and enamel condition compared to RA, regardless of mu SBS testing time.

Conclusions PA of adhesives did not reveal a significant difference in mu SBS to enamel, regardless of substrate type and etching mode.