Facioskeletal remodelling resulting from rapid palatal expansion in the monkey (Macaca cynomolgus)

Previous studies have established that rapid palatal expansion does open the midpalatal suture. The purpose of this study was to demonstrate the gross architectural changes in the facio-skeletal structures of four cynomolgus monkeys produced by the palate-splitting appliance. Bone changes were demonstrated by the utilization of tetracycline vital staining and ultraviolet light-excited fluorescence of new bone formed during an episode of skeletal remodelling.Findings indicated extensive remodelling had occurred in the nasal cavity, lateral alveolar processes, inferior surface of the palate, and the floor and lateral and medial walls of the orbits. Lateral orbital changes terminated at the zygomatico-frontal suture anteriorly, and fronto-sphenoidal suture posteriorly. Medially, changes were limited to the structures below the fronto-ethmoidal and fronto-nasal sutures. Thus, the roof of the orbits formed by the frontal bone was unaffected by the procedure of maxillary expansion, indicating that all changes in the facial skeleton were restricted to the appendymal structures of the neurocranium. The cranial base remained unchanged.