Evaluation of three methods of surface treatment for bonding orthodontic metal brackets to resin composite in vitro

Document Type : Original Article

Authors

Orthodontic Department, Alexandria University

Abstract

Objective: The aim of this study is to compare shear bond strength of orthodontic stainless steel brackets to resin composite surfaces In vitro using three different methods of surface treatment. Materials and methods: 60 composite resin discs, 6 mm in diameter and 2 mm in height, were prepared and aged by immersion in water for 4 weeks. After ageing, the specimens were randomly assigned to one of the following groups: (1) Control with no surface treatment, (2) 99 per cent Acetone, (3) methyl methacrylate monomer, (4) Diamond bur. The metal brackets were bonded to composite surfaces by means of an orthodontic adhesive. All specimens were stored in water for 1 week. Shear Bond Strength values were tested using a universal testing machine at a crosshead speed of 1 mm/minute, the brackets bases and corresponding RC discs were examined under stereomicroscope at 10X magnification for adhesive remnant evaluation. Shear bond strength values were analyzed using 1-way analysis of variance (ANOVA)), Adhesive remnant index scores were analysed using Chi-square test using Monte Carlo correction. Significance of the obtained results was judged at the 5% level (P ≤ 0.05). Results: The results of 1-way ANOVA for SBS means showed no statistical significant difference among the 4 groups (P = 0.564). The result of Chi-square test for ARI scores between the four groups showed a statistically significant difference (MCp = 0.039). Chi square comparisons of ARI scores showed statistically significant difference only between group 1 (control) with groups 3 (P1= 0.003) and group 4 (P1= 0.046)