Microleakage in CO2 laser etching class V composite restoration

Abstract

The CO2 laser (10.6 μm) can be indicated for dental hard tissues applications if it shows ability to remove the smear layer and creates irregular surfaces able to promote micromechanical retention for adhesive restorative dental materials. The purpose of this study was to evaluate in vitro the effect of CO2 laser etching on cavosurface of cavity preparations to composite resin restorations performed conventionally. Forty Class V cavities were performed with high-speed drill in 20 extracted human molar and randomly divided into 4 different groups: Group 1- CO2 laser (3W, 2Hz, 50ms) and after 37% phosphoric acid etching on enamel and dentin surface; Group 2- 37% phosphoric acid etching and after CO2 laser; Group 3- CO2 laser; Group 4- 37% phosphoric acid etching. The cavity restored with adhesive system (OptiBond Solo-Kerr) and composite resin (Prodigy-Kerr) and thermally stressed (700 cycles, 5º -55º C). The samples were then impermeabilized, immersed in 50% silver nitrate solution for 8 hours and sectioned with Isomet saw. The teeth were exposed to Photoflood light (G.E.) for 5 minutes to reveal the dye. Leakage was observed under stereomicroscope and evaluated with scores. Results were analyzed with ANOVA (p>1%) and Tukey's test (p=5%) and showed that group 2, 3 and 4 had similar results and statistically lower than group 1. These results suggested that CO2 laser may be useful for dental etching, under irradiation parameters used in this study. Further studies are required to verify efficient and safety irradiation conditions and test other restorative materials.