Bonding Performance of Self-etching Adhesives Bur-cut Dentin with Active Application Mode

Abstract

Purpose: This study evaluated whether active application of self-etching adhesives would influence their microtensile bond strength (μTBS) to dentin cut with burs of different grit sizes. Materials and Methods: Eighty-four human premolars were divided into 12 groups according to 1) two dentin sur face preparations with either superfineor regular-grit diamond burs; 2) three adhesives – Clearfil SE Bond 2 (SE2), Scotchbond Universal (SBU, 3M Oral Care) and G-Premio Bond (GPB, GC); and 3) two application modes of each adhesive (active or passive). Six bonded teeth per group were sectioned into sticks for μTBS testing. Statistical analyses were performed using 3-way ANOVA followed by Duncan’s test (p 0.05). Additional teeth were prepared to observe the interaction between the dentin smear layer obtained from each bur with adhesives under different application modes using transmission electron microscopy (TEM). Results Active application significantly increased the dentin bond strength of SE2, irrespective of the kind of bur used (p 0.05). The highest bond strength of SBU was observed when bonded to superfine-grit diamond bur-cut dentin with the active application. There was, however, no influence of the tested factors on GPB group (p 0.05). TEM observation showed that active application promoted dentin smear layer dissolution in all adhesive groups. Conclusions Bond strengths of self-etching adhesives to dentin are influenced by bur-cut smear layers and mainly by application mode of adhesive materials. Active application improves μTBS of self-etching adhesives by enhanc ing smear layer modification and resin penetration into bur-cut dentin.