Understanding the ablation rate of Holmium:YAG and thulium fiber lasers. Perspectives from an in vitro study

This study sought to analyze the ablation rates of Holmium:YAG (Ho:YAG) and thulium fiber laser (TFL) under different settings combinations. Lasering was carried out by a computed spiral pattern through a stepper motor bearing a laser fiber. BegoStones were placed inside a water container and lasered therein and the ablation rate was calculated. Different combinations were tested for ~12 Watts (W) for Ho:YAG and TFL lasers. Further 25 W combination for TFL were conducted testing higher frequencies. One-hundred-one experiments were conducted. Under ~12 W, the highest ablation rate for Ho:YAG was obtained with 40 Hz/0.3 J, and Virtual Basket™ (VB) emission mode [114.35 (88.30 - 126.40) mg/min] whereas for TFL, using 40 Hz/0.3 J, and long pulse [143.40 (137.40 - 146) mg/min]. A matched-comparison for 12 Hz/1 J settings showed that TFL outperformed Ho:YAG using medium pulse [63.30 (55.30 - 81.30) vs 132.00 (115.70 - 228.60) mg/min, p=0.016] and long pulse [62.90 (51.60 - 78.90) vs 134.70 (110.60 - 149.30) mg/min, p=0.016]. In the 40 Hz/0.3 J settings, TFL outperformed Ho:YAG (p=0.034). Nonetheless, Ho:YAG with VB's ablation rate increased [114.35 (88.30 - 126.40)], being comparable to that of TFL with medium pulse [127.5 (88.90 - 141.70)] (p=0.400). In TFL 25 W experiments, the ablation rate of 500 Hz / 0.05 J, was higher than those of 1000 Hz / 0.025 J (p=0.049). TFL ablation rate is higher than that of Ho:YAG. Moreover, the Virtual Basket™ emission mode, increased Ho:YAG ablation rates, resulting reaching similar to that of TFL in certain modalities.