Measurement of Pressures Generated in Root Canal During Er:YAG Laser-Activated Irrigation

To measure distribution of pressures along the depth of the root canal during erbium-doped yttrium aluminum garnet (Er:YAG) laser-activated irrigation (LAI) with different modalities and fiber tip (FT) geometries. A new LAI modality based on the delivery of synchronized pairs of Er:YAG laser pulses to generate enhanced irrigant streaming and shock wave emission was recently introduced. However, the influence of FT geometry on efficacy and comparison with single pulse modality is not yet presented. Pressures within a simulated root canal were simultaneously measured at 5 depths during LAI. Seven FT geometries (conical and cylindrical) and two modalities [Super Short Pulse (SSP) and dual pulse AutoSWEEPS] were compared. Under the same conditions, average pressures using SSP at 20 mJ of laser energy ranged from 111 Pa for a conical 600 μm FT to 225 Pa for a flat 400 μm FT. The measured pressures for the SSP and the AutoSWEEPS at 20 mJ laser energy were 223 and 308 Pa at the most coronal level and 119 and 126 Pa at the apical constriction, respectively. Measured pressures and irrigant penetration depths at different root canal levels were found to be linearly correlated (R² = 0.82; p < 0.01). The generated pressures get progressively reduced from the coronal toward the apical third of the root canal. A strong dependence on the FT design and laser modality was observed. Within the limitations of the study, the AutoSWEEPS modality is more effective than standard SSP in generating pressures within the root canal, without increasing the risk of extrusion.