Qualitative analysis of dentin surface modifications induced by Er, Cr: YSGG and Er: YAG laser for resin composite bonding

Abstract

Abstract Purpose The aim of this study was to investigate the different dentin surfaces produced following their modification using Er, Cr: YSGG and Er: YAG lasers under different operating parameters. Methods Thirty-three sound, caries-free human third molars were collected and sectioned to expose flat dentin surfaces. Each specimen was polished and a 2 × 2 mm area was delineated for laser irradiation. The samples were divided into eleven groups according to laser type, irradiation time, tip diameter, and mode of application. Er: YAG laser irradiation was performed in non-contact mode for 30 s, 1 min, and 2 min, while Er, Cr: YSGG laser irradiation was applied in contact mode using different tips and exposure times. Control groups included untreated dentin and dentin etched with 37% phosphoric acid. All specimens were prepared for scanning electron microscopy (SEM) and qualitatively analyzed for surface morphology and elemental composition (Ca and P). Results Dentin surfaces irradiated with the Er, Cr: YSGG laser exhibited rough, smear layer–free surfaces with enlarged dentinal tubules, particularly after 30 s and 1 min of irradiation. Prolonged irradiation (2 min) with either laser resulted in excessively rough, irregular surfaces with cracks, craters and smear layer formation. Er: YAG-treated dentin showed pronounced surface irregularities and smear layer presence, with limited tubule opening even at shorter irradiation times. Elemental analysis revealed significant differences in calcium and phosphorus content among groups ( p < 0.05). Conclusions Both Er, Cr: YSGG and Er: YAG lasers are capable of modifying qualitatively the morphological appearance of the dentin surface in a different but comparable manner with phosphoric acid etching when appropriate parameters are selected.