Muscle and Joint Mechanics During Maximum-Force Biting Following Total Temporomandibular Joint Replacement Surgery

Abstract

Abstract Total temporomandibular joint replacement (TMJR) surgery is the established treatment for severe temporomandibular joint disorders. While TMJR surgery is known to increase mouth opening capacity, reduce pain and improve quality of life, little is known about post-surgical jaw function during biting and chewing. The aim of this study was to use subject-specific 3D bite force measurements to evaluate the magnitude and direction of joint loading in unilateral total TMJR patients and healthy control subjects. An optoelectronic tracking system was used to measure jaw kinematics during maximum-force biting on a rubber sample in 5 unilateral total TMJR patients and 8 controls. Finite element model simulations driven by the measured kinematics were then employed to calculate the resultant bite force generated when compressing the rubber sample between the maxillary and mandibular teeth. Subject-specific musculoskeletal models were subsequently used to calculate muscle and TMJ loading. Unilateral total TMJR patients generated a bite force of 249.6 ± 24.4 N and 164.2 ± 62.3 N when biting on the contralateral and ipsilateral molars, respectively. In contrast, controls generated a bite force of 317.1 ± 206.6 N. Unilateral total TMJR patients biting on the contralateral molars had a significantly higher lateral TMJ force direction (median difference: 63.6°, p = 0.028), and a significantly lower ratio of working TMJ force to bite force compared to controls (median difference: 0.17, p = 0.049). The findings of this study provide insight into the loading of dental structures, which may influence the design and evaluation of dental implants, and guide TMJ prosthesis design.