Effects of demineralizaton-inhibition procedures on the bond strength of brackets bonded to demineralized enamel surface

Objective: To study and compare the effects of different demineralizationinhibition methods on the shear bond strength (SBS) and fracture mode of an adhesive used to bond orthodontic brackets to demineralized enamel surfaces. Methods: Eighty freshly extracted, human maxillary premolars were divided into 4 equal groups and demineralized over the course of 21 days. Brackets were bonded to the demineralized enamel of teeth in Group 1. In Group 2, bonding was performed following resin infi ltration (ICON®, DMG, Hamburg, Germany). Before bonding, pre-treatment with acidulated phosphate fluoride (APF) or solutions containing casein phosphopeptide-amorphous calcium phosphate with 2% neutral sodium fluoride (CPP-ACP/wF) was performed in Groups 3 and 4, respectively. Th e SBS values of the brackets were measured and recorded following mechanical shearing of the bracket from the tooth surface. Th e adhesive remnant index (ARI) scores were determined aft er the brackets failed. Statistical comparisons were performed using one-way ANOVA, Tukey’s post-tests, and G-tests. Results: Significant differences were found in some of the intergroup comparisons of the SBS values (F = 39.287, p < 0.001). No signifi cant diff erences were found between the values for the APF-gel and control groups, whereas signifi cantly higher SBS values were recorded for the resin-infi ltrated and CPPACP/ wF-treated groups. Th e ARI scores were also signifi cantly diff erent among the 4 groups (p < 0.001). Conclusions: Tooth surfaces exposed to resin infi ltration and CPP-ACP/wF application showed higher debonding forces than the untreated, demineralized surfaces