Mandible strength and geometry in relation to bite force: a study in three caviomorph rodents

Abstract

The monophyletic group Caviomorpha constitutes the most diverse rodent clade in terms of locomotion, ecology and diet. Caviomorph species show considerable variation in cranio‐mandibular morphology that has been linked to the differences in toughness of dietary items and other behaviors, such as chisel‐tooth digging. This work assesses the structural strength of the mandible of three caviomorph species that show remarkable differences in ecology, behavior and bite force: Chinchilla lanigera (a surface‐dwelling species), Octodon degus (a semi‐fossorial species) and Ctenomys talarum (a subterranean species). Finite element (FE) models of the mandibles are used to predict the stresses they withstand during incisor biting; the results are related to in vivo bite forces and interspecific variations in the mandibular geometries. The study concludes that the mandible of C. talarum is better able to withstand strong incisor bites. Its powerful adducting musculature is consistent with the notorious lateral expansion of the angular process and the masseteric crest, and the enhanced cortical bone thickness. Although it has a relatively low bite force, the mandible of O. degus also shows a good performance for mid‐to‐strong incisor biting, in contrast to that of C. lanigera, which exhibits, from a mechanical point of view, the worst performance. The mandibles of C. talarum and O. degus appear to be better suited to withstand stronger reaction forces from incisor biting, which is consistent with their closer phylogenetic affinity and shared digging behaviors. The contrast between the low in vivo bite force of C. lanigera and the relatively high estimations that result from the models suggests that its adductor musculature could play significant roles in functions other than incisor biting.

Evaluation of geometric parameters of the stomatognathic system using radiological imaging

“…It also allows, with the use of FEM, the construction of the strength to be considered under personalized conditions, taking into account the physiological capacity of the tissues under load. The spatial objective dimensions of the masticatory organ form the basis for the correlation of shape with the possibilities of generating forces that may occur in occlusion [40][41][42].…”

Comparison of the biomechanical differences in the occlusal movement of wild-type and BMP9 knockout mice with apical periodontitis

“…The models were imported into the 3D FEA software ANSYS and the meshes were divided automatically. Young’s modulus and Poisson’s ratio values were adopted from the relevant literature ( Table 1 ) ( Mankani et al, 2006 ; Buezas et al, 2019 ).…”

Computational analysis of the mechanical behavior of mandibular bone structures during the molar power stroke phase in Wistar rats

“…Although the methods are different, this simulation allows to apply the mandibular pattern in the power stroke phases since the closed mouth position(Weijs and Dantuma, 1975) features the deformation instead movements. The molar chewing process under static conditions has been simulated previously by FEM, which resulted in stress and, consequently, bone deformations in the mandible(Tsouknidas et al, 2017;Buezas et al, 2019), allowing the study of the mechanical behavior of the mandible successfully.Differently from the study byWeijs and Dantuma (1975), which obtained muscle force data from electromyography, this study used a method similar to previous FEM studies for the reproduction of muscle action, using morphological data of the mandibular elevator musclesfrom microCT associated to iodine-based contrast (Cox et al, 2012; Buezas et al, 2019), and the calculation of the estimated muscle force from the CSA. This method was previously used to simulate muscle action in infant mandibles (Humphries et al, 2021), which was used as a reference for this study.…”