Influence of Bioactive Glass Incorporation in Resin Adhesives of Orthodontic Brackets on Adhesion Properties and Calcium Release

Abstract

This study evaluated a light-cure orthodontic adhesive with the incorporation of bioactive glass particles and its effects on shear bond strength (SBS), adhesive remnant index (ARI), degree of conversion (DC), calcium release, and particle size distribution. Bioactive glass was added to the Transbond XT Adhesive (3M ESPE), resulting in five groups: TXT (0% wt of bioactive glass-incorporated-negative control); TXT20 (20% wt of bioactive glass-incorporated); TXT30 (30% wt of bioactive glass-incorporated), TXT50 (50% wt of bioactive glass-incorporated), and FLB (positive control-FL BOND II adhesive system with S-PRG particles, SHOFU Inc.). Data were analyzed with one-way ANOVA followed by Tukey's test (α = 0.05). Quantitative SEM analysis confirmed submicron particle agglomerates (median equivalent circular diameter 0.020-0.108 µm). The TXT20 exhibited the highest values of degree of conversion (<i>p</i> &lt; 0.05) (73.02 ± 3.33A). For SBS (in MPa): Control Group TXT-19.50 ± 1.40A, Group TXT20 18.22 ± 1.04AB, Group FLB 17.62 ± 1.45B, Group TXT30 14.48 ± 1.46C and Group TXT50 14.13 ± 1.02C (<i>p</i> &lt; 0.05). For calcium release the group TXT50 2.23 ± 0.11D showed higher values (<i>p</i> &lt; 0.05). The incorporation of distinct bioactive glass particle concentrations influenced the shear bond strength, degree of conversion, and calcium release. While the 50 wt% bioactive glass group exhibited the highest calcium release, both 20 wt% of bioactive glass group and the positive control group exhibited the highest degree of conversion without compromising the bonding strength.