Evaluation of shear bond strength of brackets bonded with orthodontic fluoride-releasing composite resins

Marcia Cristina RASTELLI, Ulisses COELHO, Emígdio Enrique Orellana JIMENEZ

Objective: To evaluate the shear bond strength of stainless steel brackets bonded with fluoride releasing composite resins, comparing them with a conventional resin and to analyze the amount of resin left on the enamel surface. Methods: Sixty premolars were randomly divided into three groups: Group I – Concise (3M), Group II – Ultrabond (Aditek do Brasil) and Group III – Rely-a-Bond (Reliance). After bonding, the samples were thermocycled (500 cycles) at 5ºC and 55ºC temperatures. After 48 hours they were subjected to shear bond strength testing, in the occluso-gingival direction, using an MTS 810 Universal Testing Machine with load speed of 0.5 mm/min. Results: The results demonstrated a mean shear bond strength of 24.54 ± 6.98 MPa for Group I, 11.53 ± 6.20 MPa for Group II, and 16.46 ± 5.72 MPa for Group III. Analysis of Variance (ANOVA) determined a statistical difference in the mean shear bond strengths between groups (p < 0.001). The Tukey test evidenced that the averages of the three groups were significantly different (p < 0.05), with the highest values for Group I and the lowest for Group II. The Kruskal-Wallis test did not show significant differences in the amount of resin left on the enamel in any of the three groups (p = 0.361). Conclusion: All materials exhibited adequate adhesive bond strength for clinical use. Concise exhibited the highest degree of shear bond strength but no significant differences were found in Adhesive Remnant Index (ARI) between the groups.

Keywords: Shear bond strength. Brackets. Composite fluoride resin.

Saturday, November 23, 2024 02:09