An approach to enhance the interface adhesion between an orthodontic plastic bracket and adhesive

For the purpose of improving the degree of success of plastic bracket bondi ng, based on the analysis of the chemical components of plastic brackets, a systematic method for the treatment of the adhesive surface of plastic bra ckets was introduced in this study. After sandblasting the adhesive surface s of two commercially available plastic brackets (Spirit and Clear Bracket) , a favourable surface treatment was obtained with the application of a sil ane coupling agent, gamma -methacryloxy propyl trimethoxy silane. The findi ngs showed that (i) the fillers added to the plastic brackets were glass fi llers with Si-OH groups distributed on their surfaces; (ii) sandblasting of the bracket surface resulted in exposure of the glass fillers; (iii) combi ned with sandblasting, silane coupling treatment significantly increased th e bond strength (P < 0.05), which was adequate to withstand the forces gene rated during orthodontic therapy; and (iv) treatment with sandblasting and silane coupling 24 hours before direct bonding did not cause a significant reduction in bond strength. It is concluded that sandblasting and silane co upling treatment offers the benefit of increasing the in vitro bond strengt h of plastic brackets for orthodontic application.