RESUMO
BACKGROUND: This study aimed to assess the effect of a 980-nm diode laser following chemomechanical root canal preparation on the severity of post-operative pain (PP) after root canal treatment (RCT). METHODS: This study included asymptomatic, single-rooted teeth with a periapical index (PAI) score of 3 or 4. All the patients received RCT, including dressing with calcium hydroxide (Ca(OH)2), during two visits. The patients were randomly divided into two groups (n:30): a control group, in which the final irrigation was performed using 5 ml of 2.5% sodium hypochlorite (NaOCI), followed by 5 ml of 17% and ethylenediaminetetraacetic acid (EDTA) and 5 ml of distilled water, and a laser group, in which the root canals were irradiated using a 980-nm diode laser after the final irrigation at both visits. The pain levels after both visits were evaluated using a visual analogue scale (VAS) after 8 h, 24 h, 48 h and 7 d. In addition, the time intervals to medication intake were recorded. The collected data were statistically analysed using the chi-square and Mann-Whitney U test (p < 0.05). RESULTS: The average pain level in the control group 24 h after the first visit was significantly higher than that in the laser group (p < 0.05). The average pain level 24 h and 48 h after the second visit was significantly higher in the control group (p < 0.05). The levels of PP 24 h after the first visit were higher than those after the second visit only in the control group (p < 0.05). After the first visit, analgesic use in the control group was significantly higher after 8 h (40%) and 24 h (23%) as compared with that in the laser group (p < 0.05). CONCLUSIONS: Root canal irradiation with a diode laser may reduce PP after RCT in single-rooted teeth with a PAI score of 3 or 4. TRIAL REGISTRATION: Effect of the Diode Laser on Post-operative Pain After Endodontic Treatment in Teeth with Apical Periodontitis: NCT04486196. Registered 24 July 2020-Retrospectively registered, http://clinicaltrials.gov/ct2/show/NCT04486196.