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Background: Orthodontic treatment is a long-term therapy with time-related adverse effects. Low-level laser therapy (LLLT) has been used in the clinic as an intervention to accelerate orthodontic tooth movement (OTM) and prevent adverse effects. Previous systematic reviews have evaluated the effectiveness of LLLT in the acceleration of OTM. However, it remains unclear which treatment parameters are appropriate for LLLT. This review will evaluate the efficacy of LLLT on the acceleration of fixed OTM and the prevention of adverse effects.Methods: Several electronic databases will be searched. Grey literature also will be retrieved. Parallel or clustered randomised controlled trials that evaluated the effectiveness of different LLLTs on the acceleration of fixed OTM will be included. Two researchers will independently screen all titles, abstracts, and full-text articles retrieval, as well as data extraction. The risk bias of each study will be appraised using the Cochrane Risk of Bias tool (RoB 2.0). The primary outcome will be the efficacy of LLLT on the acceleration of fixed OTM (e.g., canine movement distance, orthodontic treatment duration). Secondary outcomes will be the effectiveness of LLLT to reduce orthodontic adverse effects such as pain and root resorption. The mean difference (MD) and relative risk (RR) with corresponding 95% confidence intervals (CI) will be chosen as effective measures for continuous and binary outcomes, respectively. When feasible, both fixed and random-effects pairwise meta-analyses and frequentist network meta-analyses will be conducted.Discussion: This network meta-analysis will compare the efficacy of LLLT on the acceleration of fixed OTM as well as whether LLLT can prevent adverse effects of this orthodontic treatment. By integrating the current evidence from direct and indirect comparisons and ranking all included interventions, our findings have the potential to help clinicians achieve more effective treatment goals.Systematic review registration: PROSPERO CRD42020175850

Objective: In this retrospective study, three-dimensional photography (3dMD) was used to evaluate the facial soft tissue symmetry of unilateral cleft lip with alveolar cleft (UCLA) and unilateral complete cleft lip and palate (UCLP). The differences between the cleft side and non-cleft side were compared, and symmetrical mirror image analysis was performed.Methods: The study comprised 39 patients including 21 patients with UCLA and 18 patients with UCLP. All subjects were scanned by facial stereo photogrammetry to obtain facial soft tissue data and construct a three-dimensional digital model. The characteristic line distance in the three-dimensional direction of facial soft tissue was selected, and 3dMD Vultus software was used to measure the three-dimensional digital model of the maxillofacial soft tissue. The data were statistically analyzed with SPSS 23.0. The measurement indices of bilateral facial symmetry in each group were tested by paired t-test. One patient was selected from each of the two groups for symmetrical mirror image analysis to evaluate the distribution and severity of asymmetry.Results: There were significant differences in nostril, nasal alar and upper lip measurement indices between the two sides in both patient groups. These included the base of the nostril width (Sbal-Sni), nasal alar projection length (Ac-Prn), depth of midface (T-Sn) and all of the lip indices in both UCLA and UCLP groups. The nasal lateral length (En-Ac) was different in the UCLA group whereas the axial length of the nostril (Sbal-C) was different in the UCLP group. According to the mirror image analysis, the facial asymmetry of UCLA patients was identified principally in the ala, nostril and cheilion which was considered as mild asymmetry. Patients with UCLP showed severe asymmetry, including the entire midface. Conclusion: Patients in both study groups continued to show facial soft tissue deformity in three-dimensional evaluation in prepuberty. It was principally manifested, but not limited to, the nasolabial area. The range of asymmetry in patients with UCLP was wider and the degree of asymmetry was greater than in patients with UCLA. The facial malformation of patients in both groups would still require additional improvement with subsequent treatment.