Occlusal curvatures such as the
curve of Spee, curve of Wilson and Monsons's sphere exist in the human
adult mandibular arch. A previous study showed that human young adults
with flatter occlusal curvatures had higher ability of food comminution
and mixing. The aim of this study was to clarify functional significance
of occlusal curvatures in terms of masticatory movements. This study
investigated the association between occlusal curvature and mandibular
movements while chewing a variety of food items.
young adults with complete dentitions (mean age, 25.0 years)
participated in the study. Sphere radius of occlusal curvature was
determined by a three-dimensional analysis of the mandibular arch based
on the Broadrick flag method. Mandibular movements during unilateral
chewing of six test food items (chewing gum, cheese, kamaboko, boiled
beef, gummy jelly and raw carrot) until the subjects felt ready to
swallow were recorded using a six-degrees-of-freedom mandibular movement
recording system, and 11 parameters for masticatory movements of a
lower incisal point of the mandible were analysed.
regression analyses identified the sphere radius as a significant
predictor for closing velocity in all test food items, occluding/cycle
duration in 3 items, opening velocity, closing duration and chewing time
in 2 items, and opening duration in 1 item (P<0.01).
The results suggest that subjects with larger sphere radius (flatter
occlusal curvature) in the mandibular arch could prepare food bolus
effectively for swallowing.
Occlusal curvature seems to be associated with masticatory movements in young adults with permanent dentition.