Immediate 3D Skull Changes Following 3D-Guided Midpalatal Piezocorticotomy-Assisted MARPE: Case Report

<b>Background/Objectives</b>: Mini-Screw-Assisted Rapid Skeletal Expansion (MARPE) appliances have been widely used for maxillary skeletal expansion in non-growing subjects and adolescents with a fused midpalatal suture. The current case report describes the immediate 3D cephalometric changes in the skeletal and soft tissue parameters, along with upper airway volume, shape, and dimensions, in a patient with Skeletal Class I anterior underbite. <b>Methods:</b> The pre- and post-expansion full-face Cone-Beam Computed Tomograms (CBCTs) of a 19-year-old patient who underwent 3D-guided midpalatal piezocorticotomy-assisted MARPE were compared and analyzed using 3D cephalometric software. Both CBCT volumes were re-oriented relative to the Frankfurt horizontal plane (FHP) to accommodate postural changes. <b>Results:</b> The total upper airway volume and minimum upper airway cross-section increased after expansion. The nasal base plane (ANS-PNS) rotated in all three spatial planes, including the sagittal plane (anterior downward and posterior upward rotation, with the center of rotation around the maxillary center of rotation) and the vertical plane (upward rotation on the left side). The maxillary canine and molar cant planes rotated around the center of rotation in the midface, with left upward and right downward rotation. The orientation of the ANS-PNS plane changed due to the leftward rotation of the ANS, with the center of rotation approaching the PNS. Cervical curvature improved from kyphotic to lordotic immediately following expansion. <b>Conclusions:</b> Three-dimensionally guided midpalatal piezocorticotomy-assisted MARPE has been shown to produce midfacial changes in all three spatial planes when evaluated via 3D cephalometric analysis. Comprehensive observational studies are necessary to analyze these changes and their effects for different skeletal classifications.