Effect of Low-level Laser Therapy With Different Locations of Irradiation on Postoperative Endodontic Pain in Patients With Symptomatic Irreversible Pulpitis: A Double-Blind Randomized Controlled Trial

Abstract Introduction: This double-blind, placebo-controlled, clinical trial aimed to investigate the analgesic efficacy of low-level laser therapy (LLLT) with two different locations, and their comparison, in postoperative endodontic pain (PEP) levels in molars diagnosed with symptomatic irreversible pulpitis.Methods: Seventy-five patients with a molar tooth, diagnosed with symptomatic irreversible pulpitis, were divided into three groups of placebo, buccal only irradiation (BI), and buccal and lingual irradiation (BLI), with ۲۵ cases being in each group. The participants received similar singlevisit nonsurgical endodontic treatments. Then, a sham laser was used in the control group instead of LLLT. Individuals in BI and BLI groups received ۸۰-second irradiation on the buccal surface and ۸۰-second irradiation on each of the buccal and lingual surfaces respectively. A laser with an ۸۰۸ nm wavelength, power of ۱۰۰ mW, a fiber diameter of ۶۰۰ μm, and a dose of ۷۰ J/cm۲ was used. PEP was assessed using a ۰-۱۰۰ mm VAS ۴, ۸, ۲۴, and ۴۸ hours after the treatment.Results: BLI showed a significantly higher reduction of PEP compared to placebo in all time intervals of this study. BLI was significantly more effective than BI ۸ hours after the treatment. However, intragroup differences between BLI and BI groups at other time intervals and between BI and placebo groups in all time intervals were not significant. The number of taken analgesics in the BLI group was significantly lower than the placebo group and was on a statistical borderline compared to the BI group.Conclusion: LLLT with BLI was an effective measure as a supplement to oral analgesics in the reduction of PEP compared to the placebo. Keywords: Endodontic treatment Laser Low-level laser therapy Postoperative pain Root canal therapy.