摘要： Background. This ?rst-in-human study in Saudi orthodontic patients has evaluated the role of low-level laser therapy (LLLT) in pain perception (PP). The outcome of single application of LLLT with 4 di?erent treatment modalities (TM) on PP are evaluated following orthodontic bracket bonding on maxilla. Materials and Methods. A prospective clinical intervention with imple- mentation of parallel technique in each group, 32 orthodontic patients with ectopic canine requiring ?xed orthodontic appliance were enrolled and randomly allocated to the 4 groups: LLLT + self-ligating (SL) bracket, LLLT + conventional (Conv.) bracket, non-LLLT + SL bracket, and non-LLLT + Conv. bracket. Orthodontic bracket bonding from 1st molar to 1st molar and superelastic 0.012 inch NiTi were applied for the maxilla. For each patient, maxillary 1st molar to molar received a single application of LLLT using a 940 nm Ga-Al-As laser device on 5 di?erent points labially/buccally and palatally. Main outcome measure was the degree of PP score during the 1st week of orthodontic tooth movement (OTM) after 4 hours, 24 hours, 3 days, and 7 days of both LLLT and non-LLLT treatment applications. A questionnaire with an 11-point numeric rating scale (NRS) was used for PP. Results. Mean ± SD of PP in the LLLT + SL group was 3.33 ± 1.4, 3.58 ± 1.06, 2.31 ± 0.67, and 1.89 ± 0.54 in 4 hours, 24 hours, 3 days, and 7 days, respectively. Compared to all 4 TM groups, LLLT groups showed better PP. More statistically signi?cant di?erences were found in LLLT groups. No harms were encountered. Limitations. The intervention provider and the patient were not blinded to the intervention. Conclusion. The LLLT + SL group revealed signi?cantly promising bene?ts on PP during OTM.