A critical evaluation of meta-analyses in orthodontics

Introduction: The aim of this systematic review was to investigate the topics in orthodontics that currently provide the best evidence, as documented by meta-analyses, by critically evaluating and discussing the methodologies used in these studies. Methods: Several electronic databases were searched, and hand searching was also done to identify the corresponding meta-analysis studies dealing with orthodontic-related subjects. In total, 98 studies were retrieved initially. After applying specific inclusion criteria, 16 orthodontic-related articles were identified as meta-analyses. Results: Many of these 16 articles followed appropriate meta-analytic approaches to quantitatively synthesize data and presented adequately supported evidence. However, the methodologies used in others had weaknesses, limitations, or deficiencies. Consequently, the topics in orthodontics that currently provide the best evidence, as documented by meta-analyses, include issues concerning maxillary protraction treatment, prevention of posterior crossbites, reliability of lateral cephalometric measurements, correlation between anterior tooth injuries and magnitude of overjet, correlation of external apical root resorption with treatment-related factors and type of tooth movement, and prevalence of tooth agenesis. Conclusions: Currently, for only a few orthodontic topics is there adequately supported evidence. More well-conducted, high-quality studies are needed to produce strong evidence in orthodontics.