In vitro bond strength of orthodontic brackets and resin composite cement degree of conversion as a function of pre-cure temperature

The goal of this study was to evaluate the shear bond strength of orthodontic brackets and corresponding resin composite cement degree of conversion as function of pre-cure temperature. Orthodontic brackets were bonded to paired maxillary premolars or mandibular third molars in an environmental chamber with either room temperature (control) or warmed (68°C) resin cement. Bonding was followed immediately by shear testing of the bracket/cement/tooth interface. Residual resin cement on the bracket base was evaluated using micro-Raman spectroscopy to measure the degree of conversion of the cement from ratios of spectral peak heights at 1610cm-1 and 1640cm-1. Results showed no difference in shear bond strength or degree of conversion between room temperature and pre-warmed groups. Also, there was no difference in bond strength between premolar and third molar groups. The evidence suggests that pre-warming resin composite cement is not beneficial for increasing shear bond strength.