Mandibular Biomechanics and Development of the Human Chin

  title={Mandibular Biomechanics and Development of the Human Chin},
  author={Ionut P Ichim and M.V. Swain and Julius A. Kieser},
  journal={Journal of Dental Research},
  pages={638 - 642}
The development of the chin, a feature unique to humans, suggests a close functional linkage between jaw biomechanics and symphyseal architecture. The present study tests the hypothesis that the presence of a chin changes strain patterns in the loaded mandible. Using an anatomically correct 3-D model of a dentate mandible derived from a CT scan image, we analyzed strain patterns during incisal and molar biting. We then constructed a second mandible, without a chin, by ‘defeaturing’ the first… 

Figures from this paper

Why do humans have chins? Testing the mechanical significance of modern human symphyseal morphology with finite element analysis.
The results of this study corroborate prior hypotheses about the mechanical effects of the human chin and vertical symphysis orientation and support the idea that the relative importance of wishboning and vertical bending in the coronal plane might have played a role in the evolution of modern human symphyseal morphology.
Chin development as a result of differential jaw growth.
  • S. Marshall, Laura E. Low, T. Southard
  • Medicine
    American journal of orthodontics and dentofacial orthopedics : official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics
  • 2011
Symphyseal surface strain during in vitro human mandibular wishboning.
Human symphyseal form, with its distinctive chin, is unlikely to be adapted for countering wishboning loads, which runs counter to the optimality criterion typically invoked in assessing trait performance for signs of adaptation.
When anthropological considerations influence our attitude about the chin and orthognathic surgery
Recent research based on the analysis of stress using the finite element method (FEM) seems to establish that the presence of the chin is a biomechanical consequence of skeletal and muscular equilibrium peculiar to the human face.
The ontogeny of the chin: an analysis of allometric and biomechanical scaling
It is indicated that ontogenetic increases in chin projection do not provide greater bending resistance to the mandibular symphysis, and a complex interaction between symphyseal ontogeny and bending resistance is suggested.
Numerical and Experimental Models of the Mandible
This study proved that FE models of the mandible can reproduce experimental strains within an overall agreement of 10% and can be used for the design of a novel TMJ implant considering other load configurations and bone mechanical properties.
Design and Finite Element Analysis of Mandibular Prosthesis
Many reconstructive surgeons are confronted with difficult issues when it comes to defect repair. It is not only necessary to repair the implant during the reconstruction, but it is also necessary to
Biomechanical Analysis of Patient-Specific Temporomandibular Joint Implant and Comparison with Natural Intact Jaw Bone Using Finite Element Method
It is observed that the natural TMJ has a higher deformation value as compared to the patient-specific TMJ implant due to the lower mechanical strength of bone relative to the Ti-6Al-4V and Co-Cr alloy, which can conclude that the designed customTMJ implant is safe for the patient from the point of design perspective.
Biomechanical Response in Mandibular Bone due to Mastication Loading on 3-Unit Fixed Partial Dentures
This study investigates the potential biological remodelling response during mastication on the mandibular pre- and post-insertion of a fixed partial denture (FPD) and suggests similar outcomes to those reported clinically.


Mandibular stiffness in humans: numerical predictions.
Biomechanics of torsion in the human mandible.
Comparative investigations of mandibular function among primates have relied upon elementary structural models to estimate states of masticatory stress and strain, but these models are probably not consistently reliable for predicting the distribution of strains in the corpus.
Comparative Functional Morphology of Maximum Mandibular Opening (Gape) in Primates
There is wide variation among primates in the size and shape of teeth, the size and position of masticatory muscles, and the morphology of the craniofacial skeleton. The functional significance of
Experimental and finite element study of a human mandible.
It is concluded that the applied procedure of generating the FE model is a valid and accurate, non-invasive method to predict different parameters of the complex biomechanical behaviour of human mandibles.
Bone strain following application of a rigid bone plate: an in vitro study in human mandibles.
Cross-sectional geometry and morphology of the mandibular symphysis in Middle and Late Pleistocene Homo.
The decoupling of bending resistance and mentum osseum form in the Late Pleistocene suggests that the evolutionary emergence of the modern human "chin" was at least partly independent of the biomechanical demands placed on the symphysis.
Symphyseal fusion and jaw-adductor muscle force: an EMG study.
Both the analysis of the W/B EMG ratios and the muscle firing pattern data support the hypothesis that symphyseal fusion and transversely-directed muscle force in anthropoids are functionally linked, which supports the hypotheses that the evolution of symphySEal fusion in anthropoid is an adaptation to strengthen the symphysis so as to counter increased wishboning stress during forceful unilateral mastication.
Functional morphology of the human chin
When the morphology of the chin is considered in light of experimental data on mastication, its evolution can be interpreted as a consequence of recent changes in mandibular proportions that have altered the relative importance of different masticatory stresses.
Bite force production capability and efficiency in Neandertals and modern humans.
It is concluded that masticatory biomechanical adaptation does not underlie variation in the facial skeleton of later Pleistocene Homo in general, and that continued exploration of alternative explanations for Neandertal facial architecture seems warranted.