A Cinephotographic Study of the Role of the Canine in Limiting Lateral Jaw Movement in Macaca fascicularis

Abstract

Three specimens of Macaca fascicularis were examined to test the hypothesis that the canines do not restrict lateral masticatory movements in these animals. The animals were filmed while chewing freely before, shortly after, and seven weeks after canine removal. Facial markers, viewed from the lateral plane, allowed for computer tracings of all mandibular movements. The maximal lateral movement of the mandible was assessed for each chewing cycle, and means were calculated for each test condition and animal. These means were compared intra-animal for statistically significant differences in lateral jaw movement before and after canine removal. No significant long-term increase in lateral movement was found in any animal after the removal of its canine teeth. We conclude that, in accordance with our hypothesis, the lateral movement during mastication did not increase significantly after removal of the canine teeth in three specimens of Macaca fascicularis. Therefore, the use of the macaque as a human model for masticatory studies requires further assessment. This study reveals that the canine teeth are not as important as previously assumed in affecting the form of the masticatory cycle in the macaque.