A Dynamic Jaw Model With a Finite-Element Temporomandibular Joint.

Benedikt Sagl,Eva Piehslinger,Martina Schmid-Schwap,Michael Kundi,Ian Stavness

doi:10.3389/fphys.2019.01156

Benedikt Sagl, Eva Piehslinger + Show 3 more

Open Access

https://doi.org/10.3389/fphys.2019.01156

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Abstract

The masticatory region is an important human motion system that is essential for basic human tasks like mastication, speech or swallowing. An association between temporomandibular disorders (TMDs) and high temporomandibular joint (TMJ) stress has been suggested, but in vivo joint force measurements are not feasible to directly test this assumption. Consequently, biomechanical computer simulation remains as one of a few means to investigate this complex system. To thoroughly examine orofacial biomechanics, we developed a novel, dynamic computer model of the masticatory system. The model combines a muscle driven rigid body model of the jaw region with a detailed finite element model (FEM) disk and elastic foundation (EF) articular cartilage. The model is validated using high-resolution MRI data for protrusion and opening that were collected from the same volunteer. Joint stresses for a clenching task as well as protrusive and opening movements are computed. Simulations resulted in mandibular positions as well as disk positions and shapes that agree well with the MRI data. The model computes reasonable disk stress patterns for dynamic tasks. Moreover, to the best of our knowledge this model presents the first ever contact model using a combination of EF layers and a FEM body, which results in a clear decrease in computation time. In conclusion, the presented model is a valuable tool for the investigation of the human TMJ and can potentially help in the future to increase the understanding of the masticatory system and the relationship between TMD and joint stress and to highlight potential therapeutic approaches for the restoration of orofacial function.

Highlights

The masticatory system is an incredibly complex musculoskeletal system, comprised of two bony structures, the mandible and the skull, which are connected by two temporomandibular joints (TMJs)
Previous literature suggests that many cases of temporomandibular disorders (TMDs) are associated with increased load on the TMJ (Detamore and Athanasiou, 2003; Ingawale and Goswami, 2009), which highlights the importance of the detailed investigation of TMJ loads using realistic, dynamic loading scenarios
This paper presents a novel rigid body model of the complete masticatory region in combination with a detailed finite element model (FEM) TMJ disk and an elastic foundation (EF) representation of articular cartilage

Summary

Introduction

The masticatory system is an incredibly complex musculoskeletal system, comprised of two bony structures, the mandible and the skull, which are connected by two temporomandibular joints (TMJs). A dynamic, cartilaginous disk is located between the mandibular condyle and the articular fossa This TMJ disk plays a crucial role in force absorption and lubrication of the joint (Koolstra et al, 2007; Tanaka and Koolstra, 2008; Koolstra and Tanaka, 2009; Nickel et al, 2009; Stankovic et al, 2013) and increases the complexity of mandibular dynamics. The small size and complex organization of the TMJ make in vivo investigations of joint forces impossible due to patient safety restrictions.

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