Abstract
We investigated the influence of the hardness of the chewing gum bolus on the electromyograms (EMGs) of the masticatory muscles in both children and adults with normal occlusion.
The subjects were divided into three groups, IIA, IIIA and IVA, according to Hellman's dental age classification. The gum was classified into soft, medium and hard types, according to hardness of the gum. All of the subjects were instructed to chew the gum on the right molars. Bipolar surface EMGs were recorded bilaterally from the masseter muscle and the temporal muscles.
The harder gum induced higher integrated values of the jaw closing muscle EMGs in order of the dental age. However, the hard gum did not the increase cycle times of the EMGs in the groups except in group IIA.
This suggest that the proprioceptive feedback is involved in the chewing of hard foods rather than the generation of chewing rhythm in the process of human growth and development.
