Comparison of a recently developed nanofiller self-etching primer adhesive with other self-etching primers and conventional acid etching.

The purpose of this ex vivo study was to compare the bond strengths and modes of failure of brackets bonded with three self-etching products [Adper Prompt L-Pop (3M Espe), Futurabond NR (Voco) and Transbond Plus (3M Unitek)] and a conventional 38 per cent phosphoric acid-etching system Etch-Rite (Pulpdent Corp.) at two different time points. Ninety-six defect-free premolars were randomly allocated to eight groups (n = 12). The etching procedure was carried out according to the manufacturers' instructions. The shear bond strengths (SBSs) were measured after storage in distilled water for 12 and 24 hours. The brackets were debonded using a universal testing machine with a cross-head speed of 0.5 mm/minute. Multiple comparisons of the SBSs for the different etching types were performed using analysis of variance. The chi-square test was used to evaluate differences in adhesive remnant index (CARI) scores among the groups. The differences between SBSs analysed at 12 and 24 hours were not significantly different. Although a significant difference (P < 0.01) was observed with conventional and self-etching primer (SEP) adhesive systems, SEP revealed bond strengths higher than clinically accepted limits (6-8 MPa). SEP systems can achieve successful orthodontic bond strengths. The rate of development of the bond strength must be determined to ensure sufficient maturation of orthodontic adhesives before functional loading.