Abstract
BACKGROUND: Orofacial myofunctional disorders (OMDs) are conditions or behaviors that negatively affect oral postures and functions. These behaviors can interfere with normal orofacial growth and development and related functions. OBJECTIVES: Map the available evidence regarding the effectiveness of Orofacial Myofunctional Therapy (OMT) in treating or managing OMDs associated with specific malocclusion traits or orthognathic surgery outcomes. SEARCH METHODS: An experienced librarian developed a comprehensive search strategy for six databases and gray literature. The reference lists of included studies were reviewed. SELECTION CRITERIA: Randomized controlled trials and non-randomized studies of intervention were included in which individuals with OMDs were treated with OMT, regardless of the healthcare setting or the professional delivering the treatment. DATA COLLECTION AND ANALYSIS: Two independent reviewers screened the retrieved records in two phases based on predefined eligibility criteria and extracted data. The evidence level was assessed using the Oxford Levels of Evidence. RESULTS: Twenty-four studies were included (18 primary studies and 6 reviews). Seven studies focused on OMDs associated with malocclusion sagittal characteristics (Class I, II, or III), ten examined open-bite-related OMDs, and seven explored OMDs following orthognathic surgery. Only four studies (22%) were randomized controlled trials (RCTs); most studies lacked proper randomization procedures, did not report allocation concealment, and three of the four RCTs were open-label. Among the six comparisons identified, five were deemed plausible (four with a level of evidence 3 and one with a level of evidence 2). No comparisons were rated at level 1 evidence. As a result, the effectiveness of OMT alone or in combination with orthodontic treatment for the conditions of interest could not be conclusively confirmed. Further well-designed RCTs are needed to confirm or refute this finding and to strengthen the overall evidence base. CONCLUSION: Although no high-level evidence currently supports the effectiveness of OMT for managing OMDs associated with malocclusion traits, its potential effectiveness remains plausible. Level 2 evidence suggests that OMT may effectively manage OMDs following orthognathic surgery. REGISTRATION: Open Science Framework (DOI 10.17605/OSF.IO/M6HNS).