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.