The purpose of this study was to evaluate the performance of modified 4-META/ MMA-TBB resin cements (Superbond C&B) in terms of debonding orthodontic brackets easily and safely from enamel without the loss of proper bracket bond strength. Poly(DL-lactide-co-glycolide) (PLGA), calcium fluoride (CaF₂), or α-tricalcium phosphate (α-TCP) was added to the polymer powder of 4-META/ MMA-TBB resin, and the shear bond strength of orthodontic brackets to human enamel using modified resins was measured before and after 10,000-cycle thermal cycling test between 5°C and 55°C.
The modified resins tended to provide lower bond strength compared with the original 4-META/ MMA-TBB resin. However, α-TCP- or CaF₂-modified resin showed no significant differences in bond strength before and after thermal cycling. Moreover, there was a tendency of more residual resin remaining on the tooth surface after debonding, thereby suggesting a lower risk of enamel fracture.
In conclusion, α-TCP- or CaF₂-modified 4-META/ MMA-TBB resin seemed to allow easy and safe debonding of orthodontic brackets without loss of proper bracket bond strength