Removal of Pulp Tissue Remnants from the Isthmus Area of Lower Molars using Photon-Induced Photoacoustic Streaming and Sonic–Activated Irrigation

Statement of Clinical Relevance • SWEEPS technique was the most effective irrigation technique in the removal of pulp tissue remnants from isthmus area in the apical part of mesial canals in lower molars • Conventional syringe and needle irrigation and sonic-activated irrigation using Pro EndoActivator showed similar efficacy in the removal of pulp tissue remnants from isthmus area in lower molars To assess the efficacy of the Er:YAG laser modality Shock Wave Enhanced Emission Photo-acoustic Streaming (SWEEPS), sonic-activated irrigation (SAI), and passive conventional irrigation (CI) in removing pulp tissue remnants (PTR) from the root canal isthmus area in mandibular molars. Forty-six extracted human mandibular molars presenting a continuous isthmus between mesial canals were selected for this study. The specimens were randomly assigned to three experimental groups (n=12/each) based on the final irrigation (FI) techniques: Group 1, SWEEPS; Group 2, SAI (SmartLite Pro EndoActivator, Denstply Sirona); and Group 3, CI. A control group received no treatment. In the experimental groups, the mesial root canals were initially prepared with a Path File instrument (13/.02) followed by ProTaper Ultimate up to the instrument F2 (25/.08), with 3% sodium hypochlorite (NaOCl) as the irrigant. The FI protocol consisted of the sequential application of 3% NaOCl, 15% ethylenediaminotetraacetic acid and 3% NaOCl. After demineralization, histological sections of the isthmus region in the apical third were evaluated, and PTR was measured. Statistical analysis was performed using the Kruskal–Wallis test and post hoc Dunn tests (α = 0.05). The SWEEPS group demonstrated the lowest PTR values (median PTR: 1.58%), with four samples exhibiting no PTR (p < 0.05). This was followed by the SAI and CI groups, which showed median PTR values of 5% and 7.39%, respectively; however, the difference between these two groups was not statistically significant (p = 0.495). SWEEPS was the most effective technique for removing RPT from the apical isthmus area, while SAI and CI showed similar efficacy.