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

Abstract

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 endo-dontically treated teeth and the reduction of postoperative pain. Material and methods. Forty patients with PLs in mandibular molars were referred for root canal re-treatment (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 treat-ment, 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 gutta-percha, 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.