Effect of er,cr:ysgg and er:yag lasers tooth preparation on gap formation of bonded enamel/dentin

Aim: To evaluate the effect of Er,Cr:YSGG and Er:YAG laser irradiations on gap formation at bonding interfaces.
Materials and Methods: Total of 45 standardized class V cavities were prepared on sound premolars with Er,Cr:YSGG laser, Er:YAG laser, or round carbide bur. A two-step self-etch adhesive, with selective enamel acid etching, and a nano-filled resin composite were applied. After 24 hours of water storage at 37°C, samples were subjected to thermocycling artificial aging. gap assessment was performed with a scanning electron microscope (JEOL JSM-6610LV, Japan). Data were analyzed in SPSS software (IBM Inc., Chicago, USA), with a significance threshold of p<0.05. Kruskal Wallis non-parametric statistical test was used to compare the mean ranks of the gap formation percentages.
Results: At enamel, both Er:YAG and Er,Cr:YSGG laser irradiation resulted in higher gap formation than the conventional cavity preparation method. Er,Cr:YSGGlaser resulted in the highest gap formation percentage at the dentin-resin interface followed by the conventional method, and Er:YAG laser resulted in the least gap formation.
Conclusion: According to the selected laser parameters, cavity preparation using Er,Cr:YSGG and Er:YAG lasers affects the gap formation at enamel and dentin surfaces. This might be due the morphological and chemical alterations of the irradiated tissues.