The Enamel Surface and Bonding in Orthodontics

Current research on the enamel surface after different bonding and debonding procedures is discussed in this review. Preconditioning the enamel surface with a 37% orthophosphoric acid solution or gel for approximately 30 seconds dissolves the minerals and thus induces irreversible changes to the enamel. The cumulative enamel loss of pumicing, bonding, debonding, and clean ups is difficult to estimate precisely as minerals are not dissolved in a uniform way. Residual adhesive may persist in surface enamel after debonding. Resin tags can reach more than 20 μm into the enamel after bonding based on the acid-etching principle, and alteration of the prism structure even further. Little research is available on the long-term effect of residual adhesive material in surface enamel. Bonding systems using self-etching primers in combination with composite adhesives or resin-modified glass ionomer bonding systems provide bond strengths sufficient for clinical use in orthodontics. These bonding systems induce less adverse effects to the enamel surface, and hence the clean up process is easier for the orthodontist. The risk of leaving residual bonding material in surface enamel is thus less.