Tissue-Specific Remodeling and Load Partitioning in Maxillary Expansion: An Evidence-Informed Three-Compartment Mechanobiological Framework

Maxillary expansion combines sutural skeletal displacement with variable alveolar, dental, and periodontal responses. Because these effects are often reported as a single transverse outcome, their biological contributions are difficult to separate. We reviewed clinical, histological, and experimental evidence on midpalatal and circummaxillary sutural remodeling, alveolar deformation, anchorage-related periodontal loading, and used this evidence to formulate a three-compartment model. The sutural skeletal domain is the intended orthopedic target; the alveolar and dentoalveolar domain describes adaptive load transfer; and the anchorage-related periodontal domain captures non-target tissue responses. These labels describe treatment roles and do not imply a fixed sequence or biological independence. Experimental studies report overlapping mechanosensing, cellular recruitment, osteoclast-related margin turnover, immune and vascular activity, and osteogenesis within expanded sutures. Direct longitudinal molecular data in humans remain scarce, and the order of these events is unresolved. Clinical imaging also shows that comparable transverse corrections can contain different proportions of sutural opening, alveolar bending, dental tipping, and buccal cortical change. The model distinguishes skeletal correction from accompanying dentoalveolar and periodontal effects and yields testable predictions for multimodal imaging, tissue-specific biological measurements, histology, and patient-specific computational modeling. We present it as a provisional analytic model, not as a validated biological classification or clinical prediction rule.