Pain profile during orthodontic levelling and alignment with fixed appliances reported in randomized trials: a systematic review with meta-analyses

Objective To assess the pain profile of patients in the levelling/alignment phase of orthodontic treatment, as reported from randomized clinical trials. Materials and methods Five databases were searched in September 2022 for randomized clinical trials assessing pain during levelling/alignment with a visual analogue scale (VAS). After duplicate study selection, data extraction, and risk-of-bias assessment, random effects meta-analyses of mean differences (MDs) and their 95% confidence intervals (CIs) were performed, followed by subgroup/meta-regression, and certainty analyses. Results A total of 37 randomized trials including 2277 patients (40.3% male; mean age 17.5 years) were identified. Data indicated quick pain initiation after insertion of orthodontic appliances ( n = 6; average = 12.4 mm VAS), a quick increase to a peak at day 1 ( n = 29; average = 42.4 mm), and gradually daily decrease the first week until its end ( n = 23; average = 9.0 mm). Every second patient reported analgesic use at least once this week ( n = 8; 54.5%), with peak analgesic use at 6 h post-insertion ( n = 2; 62.3%). Patients reported reduced pain in the evening compared to morning ( n = 3; MD = − 3.0 mm; 95%CI = − 5.3, − 0.6; P = 0.01) and increased pain during chewing ( n = 2; MD = 19.2 mm; 95% CI = 7.9, 30.4; P