A comparison of different osteotomy techniques with and without pterygomaxillary disjunction in surgically assisted maxillary expansion utilizing modified hybrid rapid maxillary expansion device with posterior implants: A finite element study

INTRODUCTION: The study aims to evaluate the effect of osteotomies with and without Pterygomaxillary disjunction (PMD) during Surgical Assisted Rapid Maxillary Expansion on the displacement pattern and stress distribution of Dental and Skeletal structures of the Nasomaxillary (NM) complex by a modified rapid maxillary expansion (RME) Hybrid appliance. MATERIALS AND METHODS: A CT scan of a 20-year-old adult with maxillary constriction and the posterior bite was utilized for the restructuring of the finite element model. Five different meshed models were created individually with varying procedures of the osteotomy. A posteriorly anchored Hybrid-Hyrax appliance was utilized for RME. Groups included Group 0 - Control group without osteotomy; Group I - Only Midpalatal osteotomy; Group II - Only Subtotal Le fort I; Group III - Both Midpalatal and Subtotal Le fort I without PMD; Group IV - Midpalatal + subtotal Le fort I with bilateral PMD. The displacement pattern and stress distribution in all three dimensions were recorded and analyzed using analysis of variance and post-hoc Tukey test. RESULTS: Group IV with PMD exhibited the highest stress dissipation and displacement of the skeletal and dental structures followed by Group III osteotomies. The highest stress concentration was at midpalatal suture (292 MPa) for Group III osteotomies. There is no statistical difference between Group III and Group IV osteotomies for many of the parameters measured (P > 0.05). CONCLUSIONS: Posteriorly anchored Hybrid appliance without PMD is as effective as that with of PMD.