Evaluation of the microleakage of different class V cavities prepared by using Er:YAG laser, ultrasonic device, and conventional rotary instruments with two dentin bonding systems (an in vitro study).

This study aimed to evaluate the extent of microleakage in class V cavities prepared with bur, Er:YAG laser, and ultrasonic, hybridized with two different bonding agents ("Single bonding" solvent-free bonding agent and "Swiss TEC SL bond" alcohol-based solvent). Thirty freshly extracted human premolars were divided into three groups (n = 10), on each tooth, two cavities were prepared on the buccal and the lingual surfaces, and each group was subdivided into two subgroups (n = 5). Group 1: 20 cavities were prepared by using Er:YAG laser (500 mJ, 10 Hz, 63.69 J/cm(2)) (subgroup1a: Single bonding was used with 10 cavities; subgroup 1b: Swiss TEC SL bond was used with 10 cavities). Group 2: 20 cavities were prepared by using ultrasonic (subgroup 2a: Single bonding was used with 10 cavities; subgroup 2b: Swiss TEC SL bond was used with 10 cavities). Group 3: 20 cavities were prepared by using burs (subgroup 3a: Single bonding was used with 10 cavities; subgroup 3b: Swiss TEC SL bond was used with 10 cavities). Cavities were restored with a micro-hybrid composite resin. After thermocycling, the specimens were immersed in 2 % methylene blue solution for 4 h and then sectioned in the bucco-lingual direction. Dye penetration was scored based upon the extent of the dye using a stereomicroscope. The two-way ANOVA test and paired t-test revealed no statistically significant differences among the methods of preparation (conventional, laser, and ultrasonic). However, statistical differences were found between the adhesives tested: the "Single bonding", which represented the solvent-free bonding agent, had lower microleakage values than "Swiss TEC SL bond", which represented the alcohol-based bonding agent. Based on the results of this study, it can be concluded that the Erbium:Yttrium-Aluminum Garnet (Er:YAG) laser and ultrasonic are as effective as the conventional method for preparing cavities and the extent of microleakage depends on the type of the bonding agents.