Abstract:

Objective ·To systematically investigate the effects of different parameter combinations of erbium-doped yttrium aluminum garnet (Er:YAG) laser on the cutting depth and thermal damage extent in fresh ex vivo porcine tongue tissue, and to explore its potential application value in precise cutting of tongue tissue. Methods ·Fresh ex vivo porcine tongue specimens were selected as experimental models. The tissues were irradiated under various parameter settings, including different power, frequencies, scanning speeds, and water-to-air ratios. Following irradiation, the samples were fixed, embedded, and sectioned. Hematoxylin and eosin (H-E) staining was performed, and the cutting areas were observed under a microscopy to measure the cutting depth and the extent of thermal damage. The cutting depth was defined as the maximum depth of tissue ablation, while the extent of thermal damage was assessed based on the average width of the thermally affected zone. Results ·The experiments were conducted in long pluse mode. Under the conditions of a frequency of 20 Hz, a scanning speed of 0.250 mm/s, and a water-to-air ratio of 4:4, as the power increased from 1.6 W to 3.2 W, the ablation depth increased from (2.336±0.049) mm to (4.271±0.147) mm, while the width of the thermal damage zone increased from (12.849±0.834) μm to (19.649±1.055) μm, indicating that although higher power enhances ablation, it simultaneously increases thermal effects. At a power of 2.4 W, a scanning speed of 0.250 mm/s, and a water-to-air ratio of 4:4, when the frequency increased from 10 Hz to 20 Hz, the ablation depth increased from (1.272±0.120) mm to (3.042±0.021) mm, while the width of thermal damage zone decreased from (17.647±0.726) μm to (12.944±0.815) μm, suggesting that under the same power, a higher frequency (with lower pulse energy) can improve cutting efficiency while reducing instantaneous thermal damage. At a power of 2.4 W, a frequency of 20 Hz, and a water-to-air ratio of 4:4, when the scanning speed increased from 0.125 mm/s to 0.500 mm/s, the ablation depth decreased from (3.824±0.060) mm to (2.230±0.206) mm, and the width of thermal damage zone decreased from (17.711±1.177) μm to (10.203±0.475) μm, indicating that increasing the scanning speed reduces energy deposition and thermal diffusion. At a power of 2.4 W, a frequency of 20 Hz, and a scanning speed of 0.250 mm/s, the thermal damage widths at water-to-air ratios of 2:2, 4:4, and 6:6 were (16.276±0.316) μm, (12.944±0.815) μm, and (10.764±0.270) μm, respectively, indicating that the water-to-air ratio has a significant cooling effect on thermal damage. Under all tested parameter combinations, the average width of the thermal damage zone remained below 25 μm, suggesting that the thermal effects induced by the Er:YAG laser during soft tissue cutting are relatively controllable. Conclusion ·By appropriately selecting the combination of Er:YAG laser parameters, effective cutting can be ensured while keeping low thermal damage, thereby achieving a balance between tissue protection and precise surgical operation.

Key words: erbium-doped yttrium aluminum garnet (Er:YAG) laser, tongue, cutting