Enamel demineralization and bracket bond strength when etching with acid and /or Er:YAG laser.

Background:  Enamel etching for brackets is usually done with phosphoric acid. Er:YAG lasers have been recently used for this purpose with conflicting results. The effects of lasers on tooth demineralization and the effects of different combinations of laser treatments and bonding agents were evaluated in this study. Methods:  The enamel contents of fluorine, calcium oxide and phosphorus pentoxide (P2O5) were analysed using acid etching, laser treatment or both. The tensile bond strength of metallic and ceramic brackets using Transbond® XT and Fuji Ortho® LC were also tested, using acid etching, laser treatment or a combination of both. Results:  All treatments reduced the contents of fluorine, P2O5 and calcium oxide, and acid reduced P2O5 levels more than laser. The bond strength with laser was weaker than with acid, and stronger when combining both. When using laser, the best adhesive was the Fuji Ortho® LC. The combination of laser and acid produced the best results when using Transbond® XT. Conclusions:  The demineralization promoted by laser was lower than the one produced with acid. Laser treatment produced lower tensile stress strength than acid, but still enough to produce clinically efficient retention. The combination of laser and acid produced the best retention results.