Multiplanar Skeletal and Dentoalveolar Changes Associated with Orthopedic and Surgically Assisted Maxillary Expansion: A Multicenter Retrospective Observational Study

Abstract Background: This retrospective multicenter study describes skeletal and dentoalveolar changes following orthopedic rapid palatal expansion (RPE) in growing patients and surgically assisted expansion in skeletally mature adults. Objective: To characterize within-cohort transverse, sagittal, and vertical changes without directly comparing treatment effectiveness between clinically distinct populations. Methods: Records from two Italian centers (January 2024–December 2025) included 54 growing patients treated with orthopedic RPE and 27 nongrowing adults treated with surgically assisted expansion. Lateral and posteroanterior cephalograms and dental casts were assessed at baseline (T0), after appliance removal (T1), and, when available, 1 year later (T2). Changes were summarized within each cohort using mean differences and 95% confidence intervals. T2 cephalometric data were available for 20 orthopedic and 18 surgically assisted patients; dental-cast follow-up was available for 18 per cohort. Results: T0–T1 transverse increases predominated. In the orthopedic cohort, piriform aperture width increased by 1.72 mm (95% CI 1.32–2.12), maxillary skeletal width (MXR–MXL) by 3.56 mm (2.84–4.28), and cephalometric maxillary intermolar width by 6.56 mm (5.79–7.33). The corresponding surgically assisted changes were 1.17 mm (0.87–1.47), 1.39 mm (0.76–2.02), and 5.43 mm (4.95–5.91), respectively. During T1–T2, upper-intermolar cephalometric changes were +0.42 mm (95% CI −0.13 to 0.97) in the orthopedic cohort and −0.38 mm (−0.80 to 0.04) in the surgical cohort; dental-cast changes were +0.44 mm (−0.12 to 1.00) and −0.41 mm (−0.80 to −0.02), respectively. Follow-up summaries were exploratory and limited by incomplete ascertainment. Conclusions: Both clinically distinct cohorts showed maxillary transverse widening between T0 and T1. Changes from T1 to T2 were generally small in the available intermolar summaries, but incomplete follow-up precludes conclusions about treatment stability or relapse. Differences in skeletal maturity, treatment indication, and measurement landmarks, together with the retrospective design, do not permit direct causal or comparative-effectiveness inferences.