Transient apical peak pressure measurement of Er:YAG laser–activated irrigation in different in vitro tooth models using a high-frequency sensor system

The transient apical pressure side effect is an important safety consideration for Er:YAG laser-activated irrigation (LAI). Therefore, this study aimed to measure the transient apical peak pressure (TAPP) of LAI under different laser settings in various tooth models using a high-frequency sensor system. Tooth models with different pulp chamber structures, apical diameters, and curvatures were prepared using transparent resin and filled with deionised water. The Er:YAG laser fibre was placed 3 mm from the root canal orifice. Irrigation was performed at 10–40 mJ and 20–50 Hz using the super short pulse mode. The TAPP was measured using a 50,000-sample/second pressure sensor connected to the models’ apices. The TAPP of LAI was significantly higher than that of other chemical preparation methods. Among all investigated factors, pulp chamber anatomy and apical diameters had the greatest effects and were highly related to the apical peak pressure. Root canal curvature showed no direct correlation with TAPP. The larger the final prepared working width, the greater the TAPP. Furthermore, both pulse energy and frequency had positive correlations with TAPP. In conclusion, tooth anatomy factors and laser parameter settings influenced TAPP during Er:YAG LAI. Therefore, proper settings of laser parameters are important to improve the safety of Er:YAG LAI.