The evaluation of the effect of the pterygo-maxillary junction structure on surgically assisted maxillary expansion by finite element analysis

Objective: There is no consensus regarding the approach to the pterygo-maxillary junction in surgically assisted maxillary expansion. While pterygo-maxillary osteotomy is not recommended by some researchers due to the presence of important neuro-vascular structures associated with the region, another group of researchers argue that this region will create a serious resistance point for maxillary expansion and should be separated. In this study, the morphological characteristic of the pterygomaxillary junction was determined radiologically and its effects on the maxillary expansion pattern were investigated by finite element analysis. Material-Method:The 3-dimensional morphology of the pterygo-maxillary was measured separately for each dimension by examining 240 maxillary tomographies belonging to 18-30 years old healthy individuals with full teeth available in the archive of our faculty.First quartile, median, third quartile values of the measurements were calculated.Seven maxilla models with different three dimensional pterygo-maxillary characteristics were modelled and the effect of the structural characteristic of the pterygo-maxillary on the maxillary expansion pattern and the stresses in the resistance regions was evaluated by simulating the surgically assisted maxillary expansion. Results: It has been observed that the factor that increases the stress in the pterygomaxillary region the most with the enlargement of the maxilla is the depth, followed by thickness and height. The increase in pterygomaxillary region height led to a decrease in stress. In addition, in models with larger pterygomaxillary junction, stresses in areas such as the zygomatic arch, frontozygomatic suture, and medial pterigoid plate increased. The dimensional increase of the pterygomaxillary junction ended with a gradual decrease in the posterior region in transversal expansion.. Conclusion: According to the results of this study, it can be said that the increase in the depth and thickness of the pterygo-maxillary junction are critical factors in determining the need for osteotomy in this region, especially in cases where the transversal stenosis also includes the posterior maxilla. Keywords: Finite elements analysis, pterygo-maxillary junction, SARPE