Introduction: One of the most important aspects of self-etching primer system in orthodontics is the duration of adhesive resin use after application of self-etching primer. Evaluating time delay effect on band strength is the objective of this study.
Materials and methods: In this interventional-axperimental study, premolar with sound buccal enamel were selected, and randomly divided in four groups, In the first group buccal surface were etched for 30 seconds, with 37% phosphoric acid. After washing and drying, primer XT was applied on teeth and brackets. Transbond XT was used in bonding. Light with 500 mw was glowed from mesial, occlusal and distal surface for fifteen seconds, 5 and 10 minutes respectively. After thermocycling of all samples, debonding strength was measured with the help of DARTEC machine. Analysis was done by ANOVA and Duncan.
Results: The highest shear bond strength (19.4 Mpa) was seen in group one and the lowest (9.87 Mpa) in group four. Between the remaining groups and group one, there was a significant difference in mean shear bond strength. Scan electron microscope showed a strong deep tag between tooth enamel surface and adhesive in group one.
Conclusion: Significant difference in shear bond strength of two groups, traditional etching and self-etching primer was observed. Mean of shear bond strength with self-etching primer method was acceptable and delay in applying resin composite had no significant effect on shear bond strength of brackets to enamel.