Estimation of optimum adhesive thickness & its effect on shear bond strength & debonding pattern using novel bracket positioner with pressure gauge for precise force application during bonding procedure

Abstract

Purpose There is a limited data available about effect of adhesive thickness on shear bond strength and debonding pattern. Thus, this study aimed to find the optimum adhesive resin thickness between orthodontic bracket base and enamel tooth surface which is required to achieve clinically acceptable shear bond strength and its effect on debonding pattern using novel bracket positioning gauge with force sensor.Materials/Methods A total of 150 premolars extracted for orthodontic treatment purpose were categorized into three groups of 50 samples, each on the basis of applied compressive bonding force of 60-62 g, 120–122 g and 180–182 g using the novel bracket positioning gauge with force sensor. The thickness of adhesive resin was measured using Image J software. Thereafter, the universal testing machine was used to measure shear bond strength. The debonding pattern of each sample was assessed using adhesive remnant index.Results Adhesive resin thickness decreases with increase in compressive bonding force application. The shear bond strength showed the tendency to increase with decrease in adhesive thickness upto a certain extent and then it started decreasing.Conclusions Optimum bonding force of 120–122 g having a mean adhesive resin thickness of 0.44 mm may be contemplated as optimum adhesive thickness needed to attain adequate bond strength with the utmost expression of pre-adjusted edgewise appliance system. The clinical benefit seen by achieving optimum adhesive thickness will help to reduce the possibility of bracket-bond failure at enamel-adhesive interface, thereby preventing the enamel surface from damage.

Keywords

• Adhesive thickness
• shear bond strength
• Image J software
• force sensor
• adhesive remnant index