Does Early Orthodontic Treatment in Mixed Dentition Improve Long-Term Outcomes? A Systematic Review and Meta-Analysis

Background and Objectives: Early orthodontic intervention during the mixed dentition phase is commonly used to intercept developing malocclusions and potentially reduce the need for more complex treatment later. However, there is limited and conflicting evidence regarding the long-term stability of such early interventions, particularly in comparison to delayed treatment or no treatment at all. This systematic review aims to address this gap by critically evaluating and synthesizing the available evidence on the long-term skeletal and dental outcomes, following early orthodontic treatment in children aged 6-12 years versus delayed or no intervention. Materials and Methods: A comprehensive literature search was conducted across electronic databases (PubMed, Scopus, Web of Science, and Google Scholar) for studies published between January 1995 and April 2025. Eligible studies included randomized controlled trials, controlled clinical trials, and cohort studies involving children who underwent early orthodontic treatment using fixed or removable appliances with a minimum of one-year post-treatment follow-up. Comparator groups included no treatment or delayed treatment. Primary outcomes were long-term changes in overjet, ANB angle, and Peer Assessment Rating (PAR) scores. Meta-analyses were performed using a random-effects model, and the certainty of evidence was assessed using the GRADE framework. Results: A total of 18 studies were included in the systematic review, of which nine provided sufficient data on overjet for meta-analysis, with overlapping datasets available for ANB angle (n = 6) and PAR scores (n = 4). Meta-analyses showed no statistically significant long-term differences between early treatment and control groups in overjet, ANB angle, or PAR scores. Heterogeneity across outcomes ranged from low to moderate. The overall certainty of the evidence was rated as moderate, mainly due to imprecision and variability in study methods. Conclusions: Early orthodontic treatment provides short-term improvements in occlusal and skeletal parameters. However, current evidence does not support consistent long-term benefits over delayed intervention. Clinical decision-making should be individualized and reserved for cases with specific indications, such as functional crossbites, increased risk of dental trauma, or psychosocial concerns.