Deformation of the Human Mandible During Simulated Tooth Clenching

Abstract

Localized corpus and dental arch distortions measured directly on human and animal mandibles suggest complex deformation patterns at other mandibular sites during functional loading. To describe these, we simulated selected static bites on a three-dimensional finite element computer model of the human jaw. Five clenching tasks were modeled: intercuspal position, left group function, left group function plus balancing contact, incisal clenching, and right molar clenching. Under conditions of static equilibrium and within the limitations of the current modeling approach, the human jaw deforms elastically during symmetrical and asymmetrical clenching tasks. This deformation is complex, and includes the rotational distortion of the corpora around their axes. In addition, the jaw also deforms parasagittally and transversely. The degree of distortion depended on each clenching task, with actual deformations being relatively small and ranging from 0.46 mm to 1.06 mm for the tasks modeled when all sites were taken into account. The predicted overall narrowing of the dental arch is consistent with clinical reports in the literature during similar, although not identical, static jaw function. The predicted regional deformations of the upper condylar surfaces imply differential loading at their upper surfaces. Although still constrained to forceful static biting conditions, the simulated mandibular and dental arch distortions should be taken into consideration in the design and testing of prosthetic devices in the lower jaw.

Modeling the Human Mandible Under Masticatory Loads: Which Input Variables are Important?

“…Because it is not usually possible to model trabecular architecture in current FEA studies of whole mandibles, cancellous bone tissue is often modeled as a homogeneous bulk material (e.g., Tanne et al, 1993;Korioth and Hannam, 1994;Ichim et al, 2006;Gr€ oning et al, 2011b), but it is difficult to decide on the homogeneous property values of this material, because the density and morphology of the cancellous bone tissue varies within the mandible (Fanuscu and Chang, 2004). In a recent study (Gr€ oning et al, in press), we considered the effects of using different Young's modulus values for cortical bone tissue and teeth in an FE model of a human mandible, but how different values for cancellous bone tissue affect the FEA results remains to be tested.…”

“…Therefore, many FEA studies of human mandibles include it as a layer of soft material between the tooth roots and the alveolar bone (e.g., Korioth and Hannam, 1994;Tanaka et al, 1994;Reina et al, 2006;Gr€ oning et al, 2011b). However, CT scans used for FE models of whole mandibles usually do not have a sufficiently high resolution for an automatic separation between the PDL, the tooth roots and the alveolar bone, so that time-consuming manual segmentation is necessary.…”

“…The bite point is either constrained in all three axes (e.g., Gr€ oning et al, 2011a,b) or only in the axis perpendicular to the occlusal plane (e.g., Korioth and Hannam, 1994;Ichim et al, 2006;Reina et al, 2006). The condyles are either constrained directly in different directions (e.g., Haskell et al, 1986;Reina et al, 2006) or indirectly by creating simplified models of the temporomandibular joints (TMJ), each consisting of a block of temporal bone and a compliant material representing the TMJ cartilage, and constraining the block of temporal bone (e.g., Tanne et al, 1993;Korioth and Hannam, 1994;Tanaka et al, 1994;Gr€ oning et al, 2011a,b).…”

“…The condyles are either constrained directly in different directions (e.g., Haskell et al, 1986;Reina et al, 2006) or indirectly by creating simplified models of the temporomandibular joints (TMJ), each consisting of a block of temporal bone and a compliant material representing the TMJ cartilage, and constraining the block of temporal bone (e.g., Tanne et al, 1993;Korioth and Hannam, 1994;Tanaka et al, 1994;Gr€ oning et al, 2011a,b). This indirect way of constraining the condyles is meant to mimic the buffering effect of the TMJ cartilage and to avoid over-constraining the model, but as with the PDL the creation of a simplified TMJ requires time-consuming manual image processing.…”

A finite element study on the effects of midsymphyseal distraction osteogenesis on the mandible and articular disc

“…The final mesh consisted of 237,453 elements with 46,084 nodes. The mechanical properties of the materials 18,19 are described in Table 1, and considered to be homogenous, isotropic, and linear elastic.…”