The relations between the stress in temporomandibular joints and the deviated distances for mandibular asymmetric patients

The study aimed to compare the difference of stress distributions in temporomandibular joints (TMJs) between the patients with mandibular asymmetry and asymptomatic subjects and find the relations between deviated distance and biomechanical stress using three-dimensional finite element method, to give guidance to dentists for correction of mandibular asymmetry. Ten facial symmetric subjects without symptoms of temporomandibular disorders (TMD) and 10 mandibular asymmetric patients were recruited and assigned as the Control and Case group respectively. The FE models of the mandible and maxilla were reconstructed from cone-beam computed tomography (CBCT) images. Muscle forces and boundary conditions were applied to the two groups corresponding to centric and anterior occlusions. The simulation manifested significant differences in stresses of the TMJs between the non-deviated and deviated sides in the Case group under the centric and anterior occlusions. The stresses in the Case group were significantly greater than those in the Control group, especially on the non-deviated side. Besides, there were weak and moderate correlations between the third principal stresses and deviated distances for the patients under centric and anterior occlusions. The excessive stresses in the TMJ of patients with mandibular asymmetry were associated with temporomandibular disorders.