Debonding stresses of metal orthodontic brackets retained to tooth enamel with co-cured self-etch primer.

Objective: To evaluate the efficiency of the self-etch primer co-curing protocol in retaining orthodontic brackets to tooth enamel.

Materials and methods: A self-etch orthodontic resin primer was pre-cured or co-cured together with the resin adhesive (Groups 1 and 2) to retain either non-coated or pre-coated orthodontic brackets (Subgroups 1 and 2) on the buccal surfaces of extracted premolars. The debonding shear stress values were evaluated immediately after bonding (Category 1) and after exposure to cyclic intraoral hydraulic, thermal, and mechanical stress simulations (Category 2). The adhesive remnant index (ARI) was also assessed for each test category.

Results: The co-cured primer provided higher immediate debonding stress values for both non- and pre-coated brackets (Tukey's, P < 0.05) than the pre-cured primer. However, after artificial aging and stress simulation, there was no difference in bonding values for the four test categories (Tukey's, P > 0.05). The delayed debonding stress values were lower than the immediately assessed values (Tukey's, P < 0.05) for both brackets. No difference (Mann-Whitney's, P > 0.05) was noticed in the ARIs of all test categories.

Conclusion: Although intraoral stress simulation reduced the brackets' debonding values, co-curing the self-etch orthodontic primer may offer clinically efficient bonding of both non- and pre-coated metal brackets with minimal harm to tooth enamel on debonding.