Objectives: To identify malocclusion characteristics generated after using oral appliances (OAs) for at least 5 years for the management of snoring and obstructive sleep apnea (OSA) in adults.
Materials and Methods: PubMed, MEDLINE (Ovid), Scopus, CINAHL, and Informit were searched without language restrictions through January 20, 2021. Unpublished literature was searched on ClinicalTrials.gov, the National Research Register, and the Pro-Quest Dissertation Abstracts and Thesis database. Authors were contacted when necessary, and reference lists of the included studies were screened. Risk of bias was assessed through the revised Cochrane Risk of Bias tool for randomized controlled trials (RoB2) and Non-Randomized Studies of Interventions for non- RCTs and uncontrolled before-after studies (ROBINS-I). A random-effects meta-analysis was conducted only on studies that used the same OAs to exclude biomechanical differences. Risk of bias across studies was assessed with the Grading of Recommendations, Assessment, Development and Evaluation tool.
Results: A total of 12 studies were included in the final qualitative synthesis. Eight included studies had high, one had moderate, and three had low risks of bias. Significant progressive decreases of overjet (OJ;-1.43 mm; 95% confidence interval [CI], -1.66 to-1.20) and overbite (OB;-1.94 mm; 95% CI, -2.14 to -1.74) associated with maxillary incisor retroclination and mandibular incisor proclination were reported long term. Although most studies showed no sagittal skeletal changes, some degree of vertical skeletal changes were noted.
Conclusions: Based on a very low evidence level, inevitable anterior teeth positional changes seem to be a common long-term adverse effect of OAs. The magnitude of those changes could be considered clinically irrelevant for most pretreatment occlusions, but in occlusions with limited OJ and OB, it may be worth clinical consideration.