Effects of endodontic retreatment by conventional therapy compared to combined therapy with an Er:YAG laser and photobiomodulation: A randomized clinical trial.

Background: The success of endodontic retreatment relies on the effective elimination of pathogenic microflora from the root canal.

Objectives: The study aimed to investigate the effects of an erbium-doped yttrium-aluminum-garnet (Er:YAG) laser and a 635-nm laser on the healing of asymptomatic chronic periapical lesions (PLs) in endodontically treated teeth and the reduction of postoperative pain.

Material and methods: Forty patients with PLs in mandibular molars were referred for root canal retreatment (RCR). Conventional chemo-mechanical endodontic treatment was conducted in the control group (G1; n = 20). In the test group (G2; n = 20), in addition to conventional chemo-mechanical treatment, Er:YAG laser-activated irrigation (LAI) with 2% NaOCl and 17% EDTA was performed. The laser parameters were as follows: 50 mJ; 25 Hz; 1 W; 300 μs; a tip diameter of 300 μm; fluence of 71.4 J/cm2; and power density of 1,428.6 W/cm2. Subsequently, the canals were filled with thermo-condensed guttapercha, using the AH Plus sealer. In group G2, additional photobiomodulation (PBM) with a wavelength of 635 nm (400 mW, 5 s per point, a dose per point: 2 J, a dose per square centimeter: 4 J, an applicator diameter of 8 mm) was applied, with 2 application points at the apex level, administered over 4 sessions - on the treatment day, and after 24 h, 48 h and 96 h. Endodontic lesion remission was assessed by measuring the PL size with the use of cone-beam computed tomography (CBCT) at 6 and 12 months postoperatively. Postoperative pain was evaluated using the visual analog scale (VAS) after 1, 2 and 4 days.

Results: The study results demonstrated a statistically significant decrease in the mean PL size at 6 months postoperatively in the test group (mean PL size: 1.55 ±0.51 mm) as compared to the control group (mean PL size: 1.95 ±0.71 mm) (p < 0.05). In the test group, postoperative pain on VAS was significantly lower after the procedure (p < 0.05).

Conclusions: The application of Er:YAG and 635-nm diode lasers improved PL healing and decreased postoperative pain.