Indirect bonding--do custom bases need a plastic conditioner? A randomised clinical trial.

AIM To compare the clinical failure rates over six months of indirectly bonded brackets with and without methyl methacrylate monomer (MMM) conditioned custom bases. METHODS Thirty-six consecutive patients satisfying the selection criteria were randomly assigned to two groups in a split-mouth study design. In Group 1, the maxillary right and mandibular left quadrants were indirectly bonded after the custom bases had been conditioned with MMM. The brackets bonded to the teeth in the contralateral quadrants were not conditioned. In Group 2, the custom bases on the brackets indirectly bonded to the teeth in the maxillary left and mandibular right quadrants were conditioned and the brackets in the contralateral quadrants were not conditioned. Over the 6-month observation period all loose brackets were recorded, and the data were compared with a Wilcoxon signed ranks test. RESULTS Of the 828 brackets placed, six with the MMM conditioning came loose (1.4 per cent failed) compared with five in the Control group (1.2 per cent failed). The difference was not statistically significant (p = 0.74). CONCLUSION These results indicate that conditioning custom bases with methyl methacrylate monomer is an unnecessary step when indirectly bonding brackets.