A NARRATIVE REVIEW OF THE ORTHODONTICS–OBSTRUCTIVE SLEEP APNEA INTERPLAY AND ADULT PERIODONTAL–ORTHODONTIC BIOMECHANICS

Background: Two areas of contemporary orthodontic practice remain without firm, long-term scientific consensus: the extent to which expansion, orthognathic surgery, and non-extraction treatment philosophies genuinely alter upper airway volume and resolve obstructive sleep apnea (OSA) in pediatric and adult populations, and the optimal force vectors and biological tolerance limits governing orthodontic tooth movement in adults with a reduced but healthy periodontium or a history of periodontitis. Objective: This narrative review synthesizes current systematic reviews, meta-analyses, consensus statements, and mechanistic studies addressing these two domains, framed within a broader model of airway, myofunctional, and systemic integration in orthodontics. Methods: A structured narrative search of PubMed/MEDLINE, Embase, Cochrane Library, and specialty-society publications was conducted, prioritizing systematic reviews, meta-analyses, and consensus or white-paper documents published within the last decade. Results: Maxillary expansion and orofacial myofunctional therapy show short- to medium-term improvements in apnea-hypopnea index and airway dimensions, particularly in pediatric and mild-to-moderate adult OSA, while orthognathic maxillomandibular advancement remains the most reliably effective skeletal surgical intervention for moderate-to-severe adult OSA. Premolar extraction, by contrast, shows no consistent, clinically meaningful reduction in pharyngeal airway volume. In adults with reduced or previously compromised periodontium, light, intermittent, well-controlled orthodontic forces appear compatible with periodontal stability, though age-related alveolar bone maladaptation slows tooth movement and narrows the biological safety margin. Conclusion: Existing evidence supports a cautious, individualized, and interdisciplinary approach to airway-focused and periodontally compromised orthodontic care, but methodological heterogeneity and the scarcity of long-term randomized data continue to preclude definitive, universally applicable clinical guidelines.