Mandibular dimensional change.

Abstract A study was conducted in which the dimensional changes in the mandibles of 25 subjects during opening were measured at various degrees of jaw opening. It was found that the mandible contracted an average of 0.78 ± 0.05 mm. during maximum opening. The data were plotted as the per cent of contraction of the mandible versus the per cent of jaw opening. There was no change in the width of the mandible up to 28 per cent opening: Thereafter, the change in width is directly related to the per cent of opening. The change in mandibular width is due to stresses exerted by the muscles of mastication responsible for depression of the mandible.