Effects of different expansion appliances and surgical incisions on maxillary expansion: A finite element analysis

This study aims to assess the impact of different surgical techniques and three expansion appliances on maxillary expansion in adults using finite element analysis (FEA), with a focus on maxillary displacement and stress on surrounding structures.

Seven different FEA models were created to compare different surgical techniques and three different expansion appliances. Model I represented a bone-supported appliance without surgical assistance. Model II, Model III, and Model IV were surgically assisted rapid palatal expansion (SARPE) models without pterygomaxillary suture disjunction (PMD). Model V, Model VI, and Model VII were SARPE models with PMD.

The largest displacement at the anterior nasal spine (ANS) was recorded for Model II (2.95 mm). For the posterior nasal spine (PNS), the highest displacement was observed in Models V, VI, VII (2.50 mm), with the lowest in Model III (0.79 mm). Stress analysis revealed the highest stress in Model I, with models featuring PMD displaying nearly zero stress at all anatomical points, highlighting distinct expansion patterns and stress distributions between models with and without PMD.

SARPE models with PMD demonstrated a parallel expansion of the maxilla with minimal stress, while the miniscrew assisted rapid maxillary expansion (MARPE) model displayed transverse rotation. SARPE models without PMD exhibited a V-shaped expansion pattern. SARPE models with PMD represent an optimal approach for achieving uniform expansion and minimizing stress, with stress levels nearly negligible at all anatomical points in models with PMD.