Thermal, Morphological, and Optical Analysis in the Removal of Ceramic Veneers with Er:YAG Laser.

INTRODUCTION: Er:YAG lasers offer an innovative, minimally invasive alternative for removing ceramic laminates. However, safe parameters preventing thermal and morphological damage require precise establishment. BACKGROUND/OBJECTIVES: To evaluate the debonding efficacy and thermal safety of Er:YAG laser irradiation on lithium disilicate veneers, focusing on thermal behavior, shear bond strength, and morphological alterations. METHODS: The study utilized 120 enamel slabs for shear bond strength and scanning electron microscopy (SEM), and 24 whole extracted teeth for temperature analysis. Ceramic veneers were cemented with a resin cement. Irradiations used an Er:YAG laser (2940 nm) at mean powers from 2 to 6 W (100-300 mJ) and repetition rates of 18 and 20 Hz, with 50/50 water/air cooling. Cement and ceramic optical absorption was characterized using Fourier transform infrared spectroscopy. RESULTS: The resin cement exhibited high absorption at 2940 nm. Increasing mean laser power reduced shear bond strength, shifting fracture patterns toward adhesive failures and facilitating veneer removal. Intrapulpal and periapical temperature variations remained within biologically safe limits. SEM revealed cement remnants but preserved enamel morphology. CONCLUSIONS: The Er:YAG laser is a safe and effective method for debonding lithium disilicate veneers. Tested parameters successfully compromised the adhesive interface without inducing harmful thermal effects or irreversible morphological damage to the enamel, achieving the proposed objectives.