In Vitro Evaluation of Temperature Variation in Dental Tissues During Er:YAG Laser-Assisted Ceramic Veneer Removal

Temperature increases in dental tissues during ceramic veneer removal with erbium lasers may compromise pulp viability (>5.5°C) and periodontal ligament health (>11°C). This study aimed to evaluate temperature variations during Er:YAG laser-assisted removal of ceramic laminates.

Seventy single-rooted human teeth extracted from the FOUSP Biobank repository (CAEE 02854118.3.0000.0075) were endodontically treated and divided into seven groups (n = 10). Lithium disilicate ceramic laminates measuring 4.0 × 4.0 × 0.7 mm were then cemented using Variolink Esthetic LC resin cement (Ivoclar). Temperature was measured with three fast-response thermocouples (type K, 125 mm thickness) at three different sites: inside the tooth filled with thermal paste and fixed externally with composite resin on the root surfaces. The Er:YAG laser (2940 nm; LiteTouch, Israel) was applied at a 1 mm distance from the veneer, operating at 20 Hz for 10.4 s, with energy settings ranging from 150 to 400 mJ, corresponding to average powers of 3.0 W, 3.5 W, 5.0 W, 6.0 W, 6.5 W, 7.0 W, and 8.0 W. Data normality was assessed using the Kolmogorov-Smirnov test, and comparisons were performed using Kruskal-Wallis and Mann-Whitney U tests (α = 0.05).

All laser parameters successfully promoted veneer debonding. The highest temperature increase (ΔT) was observed in the 8.0 W group (21.8°C in the pulp, 42.5°C in the periodontal ligament, and 9.7°C on the lingual crown surface), followed by the 7.0 W group (4.6°C, 27.0°C, and 6.3°C, respectively) and the 6.0 W group (5.7°C, 12.3°C, and 4.1°C, respectively). Statistically significant differences were found among these groups (p < 0.05). For all measurement sites, average powers ≥ 6.0 W exceeded established thermal safety thresholds.

Er:YAG laser-assisted ceramic veneer removal can be performed within safe thermal limits when average laser power settings remain below 5.7 W. These findings contribute to establishing safer clinical parameters for aesthetic laser applications while preserving pulp and periodontal tissue integrity.