Microcomputed tomography assessment of microleakage and void formation under ceramic adhesive precoated orthodontic brackets.

Abstract

Introduction: This study aimed to evaluate microleakage, voids, and gaps in ceramic adhesive precoated (APC) brackets using microcomputed tomography and investigate their correlation with bond strength.

Methods: A total of 52 human premolars were included in this study. The teeth were randomly divided into 4 groups of 13 teeth each. The brackets used in this study were the Clarity Advanced APC Flash-free Ceramic Bracket (3M Unitek, Monrovia, Calif) and the Clarity Advanced Ceramic Bracket (3M Unitek, Monrovia, Calif). The materials used for each group were as follows: (1) 37% phosphoric acid, Transbond XT primer (3M Unitek, Monrovia, Calif), and APC Flash-free Ceramic Bracket; (2) Transbond Plus self-etching primer and APC Flash-free Ceramic Bracket; (3) 37% phosphoric acid, Transbond XT primer, Transbond XT light-cure adhesive, and Clarity Advanced Ceramic Bracket; and (4) Transbond Plus self-etching primer, Transbond XT light-cure adhesive, and Clarity Advanced Ceramic Bracket. The teeth were scanned using microcomputed tomography for microleakage, void, and gap analyses. The bond strength was measured and recorded in megapascals. One-way analysis of variance was used to compare parameters with a normal distribution. The Kruskal-Wallis test was used to compare parameters that did not comply with the normal distribution. The relationships among variables were evaluated using Spearman and Pearson correlation coefficients.

Results: There were no statistically significant differences among the groups in terms of gap volume, void volume, and total void and gap volume values (P >0.05). No significant differences were observed in relation to bond strength (P >0.05). The mean bond strength was 20.42, 19.87, 19.28, and 19.47 for groups 1-4, respectively. The Spearman's correlation analysis results demonstrated that the bond strength was significantly affected by the gap volume and total void and gap volumes. The bond strength increased with reduced total volume of voids and gaps.

Conclusions: There was no difference between the APC Flash-free Ceramic Bracket and the Clarity Advance Ceramic Bracket regarding bond strength, void volume, gap volume, and total void and gap volume. The gap volume and total void and gap volumes significantly affected the bond strength. The bond strength increased with decreased total void and gap volumes. The bond strengths of the APC Flash-free Ceramic Brackets were comparable to those of the ceramic brackets bonded using the conventional method.