Outcomes Of 3D-Guided Midpalatal Piezocorticotomy Combined With MARPE Expansion In Adults

Background: While mini-screw-assisted rapid palatal expansion (MARPE) is effective for correcting maxillary transverse deficiency in adults, perimaxillary suture disarticulation—particularly at the pterygomaxillary junction—can be inconsistent. This study evaluates skeletal and dentoalveolar outcomes of a novel 3D-guided midpalatal piezocorticotomy-assisted MARPE protocol, focusing on expansion symmetry and pre-existing asymmetries. Methods: Three adult patients were retrospectively analyzed after treatment with 3D-guided midpalatal piezocorticotomy-assisted MARPE expansion and one with non-guided midpapalatal piezocorticotomy and MARPE expansion. Surgical guides were digitally designed using CBCT data to align with the nasal septum orientation in multiple planes. Perimaxillary suture disarticulation was measured pre- and post-expansion, and dentoalveolar changes were evaluated. Post-expansion asymmetries were addressed using directly printed aligners. Results: Complete midpalatal suture separation (mean 8.48 mm), involving both anterior and posterior nasal spine regions, was achieved in one patient. Bilateral pterygomaxillary disarticulation averaged 1.06–1.23 mm, resulting in forward–outward rotation of the nasomaxillary complex. Additional separation occurred at the frontonasal (2.03 mm) and vomeromaxillary (1–2 mm) sutures, with no significant changes in orbital or peri-orbital sutures. One patient presented with pre-existing dentoalveolar asymmetry, which intensified the perceived post-expansion imbalance but was successfully corrected with directly printed aligners. In the second case, 5.6 mm of suture separation resulted in a limited lateral nasal width increase (<1.5 mm), while maxillary base expansion exceeded 6 mm. A significant canine plane cant (1.2 mm) and divergent axial inclinations of the maxillary central incisors relative to the palatal plane were also observed. In the second case, a non-impactful palatal bone fracture with asymmetric displacement of the left palatine fragment was documented. After 16 months of aligner therapy, all cases exhibited favorable remodeling of the palatal structures, midpalatal suture, and alveolar processes, accompanied by improved dental alignment, occlusal plane symmetry, and mandibular dentoalveolar adaptation. The dento-alveolar expansion achieved in the third case over the course of 16 months of treatment was approximated at 4 mm. The fourth case showed consistent improvement with direct printed aligners after MARPE midpalatal diasrticulation of 11 mm after experiencing minor bone fracture. Conclusions: Human skulls exhibit considerable variability between the left and right sides, which can influence spatial balance. Pre-existing cranial asymmetries appear to be the primary contributors to asymmetry following MARPE treatment. Careful evaluation of dentoalveolar discrepancies and axial tooth inclinations is essential for preventing and managing potential asymmetric dental arch outcomes during the post-expansion phase. Although peri-maxillary bone fractures are relatively uncommon, their occurrence is influenced by multiple factors. Adjunctive techniques, such as 3D-guided midpalatal piezocorticotomy, show promise in significantly lowering the risk of intra-expansion peri-maxillary fractures.