Impact of orthodontic treatment on nasolabial fold: a systematic review and meta-analysis

Purpose Recently, there is a paradigm shift towards prioritizing soft tissue aesthetics over dental occlusion in orthodontic treatments. This modern approach in orthodontics emphasizes not only dental alignment but also the potential impact of treatments on facial soft tissues, including the nasolabial fold (NLF). The aim of this meta-analysis was to investigate any alterations occurring in the NLF due to orthodontic treatments.Methods and Materials In this meta-analysis, a search of the literature was conducted in Medline, Scopus, ISI Web of Science, and Cochrane Central Register of Controlled Trials. Data extraction involved patient characteristics, study design, treatment modality, and NLF measurements. Risk of bias was assessed using ROBINS checklist. The extracted data underwent meta-analysis using random-effects model.Results Out of a total of 800 articles retrieved, 7 met the eligibility criteria and were enrolled. Meta-analysis of three studies showed a statistically significant difference in NLF changes between extraction and non-extraction treatments (MD = 0.27 [95%CI = 0.01, 0.54], p = 0.01). Four other studies were systematically reviewed. Risk of bias analysis identified studies with a moderate to critical risk of bias. The reviewed studies all showed that orthodontic treatment has a significant effect on NLF position and shape.Conclusion Orthodontic extraction treatment plan can change the position of NLF posteriorly by 0.27 mm, which although found to be statistically significant, probably has little clinical impact. Some different factors including anchorage, incisor retraction, patient age, and skin elasticity contribute to NLF changes.