Optimization of a procedure for rebonding dislodged orthodontic brackets

The purpose of this study was to compare shear bond strength (SBS) of bonde d and rebonded orthodontic brackets following a variety of commonly used co nditioning treatments and using both light-cured and self-cured composite r esin systems. Brackets debonded during the initial determination of SBS wer e rebonded after the removal of residual resin from enamel surfaces using f ive different treatments: (1) Remove residual resin using a tungsten carbid e bur, re-etch enamel surface, then bond a new bracket; (2) Remove resin fr om the base mesh with micro-etching then rebond the same bracket, (3) Remov e residual resin from the enamel surface using resin-removing pliers, recon dition the enamel with an air-powder polisher, then bond a new bracket; (4) Remove residual resin using a rubber cup and pumice, then bond a new brack et; (5) Remove residual resin using pliers alone, then bond a new bracket. The results revealed that the light-cured system produced higher shear bond strength in the initial bond than the self-cured system (p<0.005). Recondi tioning the enamel surfaces using a tungsten carbide bur and acid-etching g ave the highest SBS (difference 5.8 MPa; p<0.01) and clinically favorable f racture characteristics. The data suggest that the optimal procedure for re bonding dislodged orthodontic brackets is to resurface the enamel using a t ungsten carbide bur, acid-etch the enamel, and use a new or re-use an old b racket after microetching.