Comparison of shear bond strength and adhesive remnant index between precoated and conventionally bonded orthodontic brackets

BACKGROUND The purpose of this study was to compare the shear bond strength and adhesive remnant index (ARI) at the enamel-bonding interface of precoated and conventionally bonded brackets, utilizing standardized procedures. METHODS The test sample consisted of 90 recently extracted bovine permanent mandibular incisors. The teeth were bonded using the same protocol and were tested in three different situations. A material testing systems machine was utilized for debonding, and the remaining adhesive on the tooth was recorded. RESULTS Immediately after bonding, we found that the shear bond strength of the precoated brackets (6.27 MPa) was significantly higher than that of conventional brackets (5.37 MPa) (p<0.05). However, no significant differences in bond strength were found between the two bracket systems after 24 h of bonding or after thermocycling. The conventional brackets had higher ARI scores than the precoated bracket systems immediately after bonding and after 24 h. CONCLUSIONS Since there were no significant differences in the bonding strength after 24 h, the immediate bonding strength of the precoated brackets during the first day does not appear to be a major advantage over the conventional bracket systems. However, less adhesive on the tooth after debonding is an advantage of precoated brackets.