Effect of Different Desensitizing Agents on the Shear Bond Strength of Orthodontic Metal Brackets Following Bleaching Procedure: An in Vitro Analytical Study.

Abstract

Introduction:

The increasing demand for dental aesthetics has led to a widespread use of tooth bleaching procedures, particularly with agents such as carbamide peroxide. However, bleaching has been reported to adversely affect the bonding of orthodontic brackets by altering enamel structure and leaving residual oxygen that interferes with resin polymerization.To overcome these effects, desensitizing agents like casein phosphopeptide–amorphous calcium phosphate (CPP-ACP) and casein phosphopeptide–amorphous calcium fluoride phosphate (CPP-ACFP) are commonly used due to their remineralizing potential.

Objectives:

1. To evaluate and compare the shear bond strength of orthodontic metal brackets following Bleaching with 35% carbamide peroxide on using CPP- ACP and CPP-ACFP desensitizing paste with Universal testing machine.


2. To evaluate and compare the adhesive remnant index score after debonding of Orthodontic Metal Brackets using stereo-microscope following bleaching with 35% carbamide peroxide on using CPP-ACP and CPP-ACFP desensitizing paste.

 Methods: A total of thirty (30) extracted premolars were subjected to bleaching using 35% carbamide peroxide and subsequently allocated into three groups: a control group (Group 1), a non-fluoride desensitizing agent group using CPP-ACP (Group 2), and a fluoride-containing desensitizing agent group using CPP-ACFP (Group 3). Following the respective treatments, orthodontic brackets were bonded with Transbond adhesive, and shear bond strength (SBS) was measured using a universal testing machine. After debonding, the adhesive remnant index (ARI) was evaluated under a stereomicroscope. The SBS values were statistically analyzed using one-way analysis of variance (ANOVA) followed by Tukey’s post hoc test, while ARI scores were assessed using the Kruskal–Wallis test and the Mann–Whitney U test, with the level of significance set at 5%.

Results: A statistically significant increase in shear bond strength was observed in Group 3 when compared with Groups 1 and 2 (p < 0.001). ARI score 2 was most frequently recorded in Group C (70%), whereas ARI score 3 predominated in Group C (30%).

Conclusions: Irrespective of the bleaching agent’s concentration or whether the procedure is performed in-office or at home, applying a floride based desensitizing agent enhances the shear bond strength.