Sexual dimorphisms in three-dimensional masticatory muscle attachment morphometry regulates temporomandibular joint mechanics

Xin She; Shuchun Sun; Brooke J Damon; Cherice N Hill; Matthew C Coombs; Feng Wei; Michael K Lecholop; Martin B Steed; Thierry H Bacro; Elizabeth H Slate; Naiquan Zheng; Janice S Lee; Hai Yao

doi:10.1016/j.jbiomech.2021.110623

Sexual dimorphisms in three-dimensional masticatory muscle attachment morphometry regulates temporomandibular joint mechanics

J Biomech. 2021 Sep 20:126:110623. doi: 10.1016/j.jbiomech.2021.110623. Epub 2021 Jul 10.

Authors

Affiliations

¹ Department of Bioengineering, Clemson University, Clemson, SC, USA.
² Department of Bioengineering, Clemson University, Clemson, SC, USA; Department of Oral Health Sciences, Medical University of South Carolina (MUSC), Charleston, SC, USA.
³ Department of Oral and Maxillofacial Surgery, MUSC, Charleston, SC, USA.
⁴ Center for Anatomical Studies and Education, MUSC, Charleston, SC, USA.
⁵ Department of Statistics, Florida State University, Tallahassee, FL, USA.
⁶ Department of Mechanical Engineering and Center for Biomedical Engineering and Science, University of North Carolina at Charlotte, Charlotte, NC, USA.
⁷ NIH NIDCR, Bethesda, MD, USA.
⁸ Department of Bioengineering, Clemson University, Clemson, SC, USA; Department of Oral Health Sciences, Medical University of South Carolina (MUSC), Charleston, SC, USA. Electronic address: haiyao@clemson.edu.

Abstract

Temporomandibular joint (TMJ) disorders disproportionally affect females, with female to male prevalence varying from 3:1 to 8:1. Sexual dimorphisms in masticatory muscle attachment morphometry and association with craniofacial size, critical for understanding sex-differences in TMJ function, have not been reported. The objective of this study was to determine sex-specific differences in three-dimensional (3D) TMJ muscle attachment morphometry and craniofacial sizes and their impact on TMJ mechanics. Human cadaveric TMJ muscle attachment morphometry and craniofacial anthropometry (10Males; 11Females) were determined by previously developed 3D digitization and imaging-based methods. Sex-differences in muscle attachment morphometry and craniofacial anthropometry, and their correlation were determined, respectively using multivariate general linear and linear regression statistical models. Subject-specific musculoskeletal models of the mandible were developed to determine effects of sexual dimorphisms in mandibular size and TMJ muscle attachment morphometry on joint loading during static biting. There were significant sex-differences in craniofacial size (p = 0.024) and TMJ muscle attachment morphometry (p < 0.001). TMJ muscle attachment morphometry was significantly correlated with craniofacial size. TMJ contact forces estimated from biomechanical models were significantly, 23% on average (p < 0.001), greater for females compared to those for males when generating the same bite forces. There were significant linear correlations between TMJ contact force and both 3D mandibular length (R² = 0.48, p < 0.001) and muscle force moment arm ratio (R² = 0.68, p < 0.001). Sexual dimorphisms in masticatory muscle morphology and craniofacial sizes play critical roles in subject-specific TMJ biomechanics. Sex-specific differences in the TMJ mechanical environment should be further investigated concerning mechanical fatigue of TMJ discs associated with TMJ disorders.

Keywords: Craniofacial morphology; Muscle attachment; Musculoskeletal modelling; Sexual dimorphism; Temporomandibular joint.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Bite Force
Female
Humans
Male
Mandible
Masticatory Muscles
Sex Characteristics*
Temporomandibular Joint*

Abstract

Publication types

MeSH terms

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