Investigation of Microleakage by Conventional and Er: YAG Laser Cavity Preparation

Recurrent caries is one of the most common problems after tooth restorative procedures. Despite improvements to resin composite formulations over the years, polymerization shrinkage of the resin matrix is still considered highly relevant in unsuccessful resin composite direct restorations. Therefore, pretreatment of the tooth surface is essential to establish a strong bond between resin and both enamel and dentine. The standard approach for enamel pre - treatment is acid etching. Some researchers have explored the use of lasers to modify the surfaces of teeth intentionally, to improve bonding of restorations. The effect of laser irradiation on surface characteristics is not still completely revealed if it beneficially alters surface specifications or not, and needs more investigations to show if it results in increasing or decreasing the microleakage in comparison to conventional chemical acid etching procedures. The aim of our in vitro study was to investigate the marginal leakage of class V cavities prepared by conventional diamond bur and Er: YAG laser.45 single rooted intact extracted human teeth were used. They were randomly assigned into three groups, dependent on the preparation technique: Group I (n=15) - diamond bur + total - etch technique; Group II (n=15) - Er: YAG laser + total - etch technique; Group III (n=15) - Er: YAG laser + laser etching. Microleakage was assessed according to the depth of dye penetration along the restoration at x 15 magnification. None of the procedures investigated on our study completely eliminated the microleakage. The extent of dye penetration was lowest in the laser - treated and acid - etched group (Group II). The results of our study revealed that the laser irradiation can modify the morphology of the cavity walls and increase the bond strength with the composite filling.