The aim of this study was to investigate the effect of different Er:YAG laser pulse modes on the microleakage of composite resin restorations using self-etch adhesive systems. Standard class V adhesive cavities were prepared on the buccal and lingual surfaces of sound human premolar teeth. The cervical cavity margins were below the CEJ. The teeth were randomly divided into three groups: Group 1; acid etching, Group 2; Er:YAG laser etching with MSP mode, Group 3: Er:YAG laser etching with QSP mode. Cavities were restored with a hybrid composite (Clearfil Majesty Posterior A3.5 Kuraray).
After thermocycling for 1000 cycles between 5C and 55 C, the specimens were stained with 0.5% aqueous basic fuchsin dye and sectioned bucco- lingually. Dye penetration was then scored. The data were analyzed using the Kruskal-Wallis and Mann- Whitney U tests with Bonferroni correction. The Wilcoxon signed ranks test was used to compare occlusal and gingival scores. Even though no statistically significant differences were found between any of the groups (p>0.05), the cavities etched with Er:YAG laser QSP mode showed less microleakage, and there were no significant differences between the microleakage at the dentin margins and the enamel margins in all groups (P>0.05).