The effects of application time of a self-etching primer and debonding methods on bracket bond strength

Abstract

Objective: To test the manufacturer's recommendation for the application rubbing time of a self-etching primer (Transbond Plus, 3M Unitek) and to compare the resulting bond strength of a resin composite (Transbond XT, 3M Unitek) in the traditional laboratory tension on all four wings with a simulation of the clinical single-wing lift-off debonding instrument (LODI; 3M Unitek).

Materials and methods: Flattened stainless-steel maxillary incisor orthodontic brackets (Victory Series, 3M Unitek) were bonded to 108 flattened bovine incisors. The enamel was rubbed with the self-etching primer for 0, 5 (the manufacturer's recommendation), and 10 seconds during a 10-second application. Traditional four-wing and LODI simulated debonding forces and the adhesive remnant index (ARI) were recorded.

Results: One-way analysis of variance testing among rubbing times and debonding methods indicated a significant difference in strength with 0 and 5 seconds of rubbing and between traditional and LODI simulated tension. The bond strengths were higher in the ARI = 1 subset compared to the ARI = 3-5 subsets.

Conclusions: The manufacturer's recommendation for primer rubbing time produced the highest bond strength. Less force is required for debonding when tension is applied to one wing (LODI simulation) vs on all four wings.