11 - Masticatory Biomechanics of Pediatric and Adult Crania: A Comparative Finite Element Analysis

Poster Board Number: 11
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Abstract Body : Finite element analysis (FEA) is a modeling technique that examines how complex structures respond to loads. It has been used in clinical and evolutionary contexts to characterize the biomechanics of human craniofacial structures, but previous work has focused on adults. As a result, little is known about whether and how ontogenetic changes affect masticatory biomechanics across developmental stages. Here we present the first pediatric cranial masticatory FEA model and compare it to a baseline of previously published, morphologically variable adults.

Using the New Mexico Decedent Image Database, a CT-scan of a 7-year-old female without cranial deformity was selected. Imaging data of the cranium was reconstructed as a surface mesh using the Biomesh FE modeling protocol. The model was edited using anatomical references and meshed as a volumetric model. Proximal and distal insertions for muscles of mastication were mapped and physiological muscle forces applied. Restraints were placed at both temporomandibular joints and on the left M1 deciduous molar to simulate a bite. Linear static analysis was performed in Strand7 (Strand7 Pty Ltd, Sydney). The resulting strain pattern and magnitudes were analyzed and compared to an adult model.

The pediatric cranium reveals similar strain patterns to the adult cranium with a few notable differences. Both models exhibit elevated strains extending superiorly from the bite point along the nasal margin to the postorbital bar, medial orbital wall, and zygomatic arch. Interestingly, strains at the zygomatic root of the pediatric model are elevated, with von Mises strain magnitudes more than 270% greater than the adult in this region. Examination of deformation and strain regimes reveals greater facial torsion in the adult, which may be explained by a premolar bite point that is more anterior relative to the zygoma. In contrast, the bite point of the pediatric molar is more closely positioned to the zygoma, resulting in greater facial shear. Literature on bone biology has highlighted the osteogenic response of bone to shear strains, therefore this critical difference in strain regimes warrants further investigation.

Future work will expand our sample to include additional pediatric crania across stages of facial development to determine whether observed patterns correspond to different facial growth stages. Further characterization of pediatric craniofacial biomechanics including the creation of additional pediatric FE models could serve as a basis for research and treatment of craniofacial abnormalities and injuries affecting occlusion and mastication.