Mandibular Biomechanics and Development of the Human Chin

OBJECTIVES: 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. METHODS: Using an anatomically correct 3-D model of a dentate mandible derived from a CT scan image, we analyse strain patterns during incisal and molar biting. We then construct a second mandible, without a chin, by defeaturing the first model. Strain patterns of the second model are then contrasted to the first. RESULTS: Our main finding is that chinned and non-chinned mandibles follow closely concordant patterns of strain distribution. We also show that there is a buccal-lingual crossover of strain distribution in the molar region during function. CONCLUSION: The results suggest that the development of the human chin is unrelated to the functional demands placed on the mandible during function.