The removal of filling material is important for successful root canal retreatment. The aim of the study was to compare the efficiency of two activated irrigation techniques, the shock wave-enhanced emission photoacoustic streaming (SWEEPS) mode of the Er:YAG laser and ultrasonically activated irrigation (UAI) and a conventional syringe-needle technique (SNI), in the removal of bioceramic sealer/gutta-percha during conventional retreatment in oval root canals. The study sample consisted of distal root canals of 42 extracted human mandibular molars, which were prepared using a ProTaper Next system up to size 40/0.06 and filled with bioceramic sealer using a single-cone obturation technique. The teeth were then re-treated with a Reciproc Blue RB40 file and 3% sodium hypochlorite solution. The prepared teeth were randomly divided into three groups (n = 14 per group) and subjected to one of the three irrigation methods. Micro-CT scans were performed at different stages to assess the amount of filling material after each retreatment phase. The results of the study showed that all the tested irrigation techniques reduced a statistically significant amount of the remnant filling material at retreatment (p < 0.05), and there were no statistically significant differences in efficacy between the three methods. All tested techniques had similar efficacy in the removal of the remaining filling remnants.

Background/Objectives: The clinical outcome of root canal treatments using calcium silicate-based sealer (CSBS) remains unclear. This study aimed to evaluate the 1-year effect of CSBS in combination with a single-cone obturation technique on periapical lesion (PL) healing evaluated on cone beam computed tomography scans (CBCT) after single-visit root canal retreatment. Methods: This randomized clinical study involved 50 patients with chronic apical periodontitis and previous root canal treatment (ClinicalTrials.gov ID: NCT04072926). The inclusion criteria were previous endodontic treatment, asymptomatic inadequate endodontic treatment, PLs measuring > 5 mm, and percussion and palpation sensitivity. The exclusion criteria were immunocompromised status, pregnancy, periodontally compromised teeth, vertical root fracture, and antibiotic usage in the last month. Single-visit root canal retreatment was performed by the same endodontist. The patients were randomly divided into two groups based on the root canal sealer used: CSBS (BioRoot RCS) and epoxy resin-based sealer (ERBS) (AH Plus). Periapical healing, as the primary outcome measure, was determined according to the reduction in PL volume on CBCT from the preoperative period to the 1-year postoperative period. Results: Pre- and postoperative PL volumes (p > 0.05) were not significantly different between the CSBS and ERBS groups. The success rate (loose criteria) was 82.9% in the ERBS group and 94.7% in CSBS group. Conclusions: Root canal retreatment outcomes of CSBS, including periapical healing, are comparable to those of ERBS at 1 year after the retreatment.

In this in vitro study, we aimed to evaluate and compare the antibacterial efficacy of a novel erbium-doped yttrium aluminum garnet laser modality, shock wave enhanced emission of photoacoustic streaming (SWEEPS), ultrasonically activated irrigation (UAI), and single needle irrigation (SNI) against old bacterial biofilm. A two-week-old Enterococcus faecalis biofilm was cultivated on transversal dentinal discs made from the middle third of the roots of single-rooted, single-canal premolars. Biofilm growth was confirmed using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The dentine samples were randomly distributed into three experimental groups and one control group based on the irrigation protocol used: Group 1, SWEEPS; Group 2, UAI; and Group 3, SNI. The root canals were irrigated with a 3% sodium hypochlorite solution. Antibacterial efficacy was evaluated quantitatively through bacterial culture and qualitatively through CLSM and SEM. Both SWEEPS and UAI demonstrated a statistically significant reduction in Enterococcus faecalis colony-forming units (CFUs) (p < 0.001), while SNI did not show a statistically significant reduction (p = 0.553). No significant difference was observed between the efficacy of SWEEPS and UAI (p > 0.05). The SWEEPS and UAI techniques were equally effective in eliminating mature E. faecalis biofilm.

The aim of this study was to evaluate the effect of two laser-assisted disinfection techniques on the porosity and bond strength (BS) of a new premixed calcium silicate sealer. Forty extracted human single-rooted premolars with one root canal were prepared up to 50/05. Samples were randomly assigned to the groups (n = 10 each): 1. shock wave-enhanced emission of photoacoustic streaming (SWEEPS) (20 mJ, 15 Hz, 0.60 W, pulse duration 25 µs), 2. diode laser (975 nm, 1.5 W), 3. conventional needle and syringe irrigation (CI), and 4. control (C), with no final irrigation protocol. Root canals were filled with a premixed calcium silicate sealer using the single-cone obturation technique. Micro-CT scans were performed after two weeks to determine the presence of voids in the filling. Dentinal discs from the middle third were prepared for push-out testing. Kruskal–Wallis and post hoc Dunn tests were used, with significance set at 5%. Micro-CT analysis detected porosity in all samples, with no significant differences among the groups (p > 0.05). SWEEPS showed the highest BS values (median 3.233 MPa) and outperformed CI and C (median 1.923 and 1.989 MPa) (p < 0.05) overall. SWEEPS enhanced the BS compared with CI. Voids were present in all experimental groups.