A Bio-Realistic Finite Element Model to Evaluate the Effect of Masticatory Loadings on Mouse Mandible-Related Tissues

Abstract

Mice are arguably the dominant model organisms for studies investigating the effect of genetic traits on the pathways to mammalian skull and teeth development, thus being integral in exploring craniofacial and dental evolution. The aim of this study is to analyse the functional significance of masticatory loads on the mouse mandible and identify critical stress accumulations that could trigger phenotypic and/or growth alterations in mandible-related structures. To achieve this, a 3D model of mouse skulls was reconstructed based on Micro Computed Tomography measurements. Upon segmenting the main hard tissue components of the mandible such as incisors, molars and alveolar bone, boundary conditions were assigned on the basis of the masticatory muscle architecture. The model was subjected to four loading scenarios simulating different feeding ecologies according to the hard or soft type of food and chewing or gnawing biting movement. Chewing and gnawing resulted in varying loading patterns, with biting type exerting a dominant effect on the stress variations experienced by the mandible and loading intensity correlating linearly to the stress increase. The simulation provided refined insight on the mechanobiology of the mouse mandible, indicating that food consistency could influence micro evolutionary divergence patterns in mandible shape of rodents.

Paradoxical sleep deprivation induces differential biological response in rat masticatory muscles: Inflammation, autophagy and myogenesis

“…When the animals were submitted to SD96 + R, MyoD expression decreased in both muscles evaluated. 36 In this study, SD was able to recruit satellite cells as far as to induce myoblast proliferation for both skeletal muscles evaluated. Despite masseter and temporal increased myogenin expression in the SD96 group, masseter showed no difference in the SD96 + R group, whereas a significant increase in myogenin expression was detected to temporal in the SR96 + R group.…”

Masseter muscle atrophy impairs bone quality of the mandibular condyle but not the alveolar process early after induction

“…The maturation of bone in the alveolar process is reached before the ramus, including the mandibular condyle . The mandibular condyle in rodents is influenced by higher mechanical stress than the alveolar process during mastication . To stabilize the mandible during the occlusal phase of the chewing cycle in mice, the bilateral synchronously action of both masseter muscle and temporalis is required .…”

“…The mandibular condyle and the alveolar process are influenced differently by masticatory loading due to particular structural and anatomical features. During mastication, occlusal stress acting on the alveolar process is dampened by the periodontal ligament . This may explain why fewer extreme changes are expected in the alveolar bone than in mandibular condyle during altered loading conditions.…”

“…39 The mandibular condyle in rodents is influenced by higher mechanical stress than the alveolar process during mastication. 40 To stabilize the mandible during the occlusal phase of the chewing cycle in mice, the bilateral synchronously action of both masseter muscle and temporalis is required. 4 This is also supported by the fact that the mandibular condyle is closely related with different masticatory muscles, such as the lateral pterygoid in its anterior and medial border.…”

The jaw is a second-class lever inPedetes capensis(Rodentia: Pedetidae)

“…To address the hypotheses and to study the function of the springhare skull during biting, finite element analysis (FEA) will be employed. FEA is an engineering technique for predicting stress, strain and deformation in an object during loading (Rayfield, 2007), and is now frequently applied to reconstructions of skulls and other skeletal elements in order to analyse vertebrate biomechanics (e.g., Richmond et al, 2005; Kupczik et al, 2007; Dumont et al, 2011; Ross et al, 2011; Cox et al, 2012; Cox, Kirkham & Herrel, 2013; O’Hare et al, 2013; Porro et al, 2013; Figueirido et al, 2014; Cuff, Bright & Rayfield, 2015; Sharp, 2015; McIntosh & Cox, 2016; McCabe et al, 2017; Tsouknidas et al, 2017). As well as simulating stress and strain distributions, FEA is also able to predict reaction forces, and so will be used here to estimate bite force, jaw joint reaction force and mechanical advantage.…”