Relationship between buccal osteotomy angulation and asymmetric expansion in surgically assisted rapid palatal expansion: a finite element analysis.

Objectives: To investigate the effects of buccal osteotomy angulation on surgically assisted rapid palatal expansion (SARPE) patterns.

Materials and methods: A finite element analysis (FEA) model of the maxilla with Haas expander was constructed from a cone beam computed tomography (CBCT) image using Mimics, Geomagic, and solidWorks software. One-mm-thick buccal osteotomies were created with different combinations of 0°, 10°, 20°, and 30° from the horizontal plane to simulate differences in bilateral osteotomy angulation. Springs were placed at the buccal osteotomy gaps to mimic the strain of the bone callus. After applying 150 Newton of expansion force at the level of the expander jackscrew in each FEA scenario, the expansion pattern of the hemimaxillae was evaluated in Ansys software.

Results: Scenarios with 20° (0-20°; 10-30°) and 30° (0-30°) differences resulted in significant transverse asymmetric expansion. Among the groups with 10° difference, 0-10° resulted in relatively parallel expansion, while 10-20° and 20-30° experienced V-shaped expansion with more anterior widening.

Conclusions: A larger difference between the angulations of the left and right buccal osteotomies resulted in increased asymmetry in both the transverse and vertical dimensions after expansion.