Abstract
This investigation was carried out for the purpose of explaining the functional development of muscles related to mastication which is one of the functions of the stomatognatic system, and how to apply this information to clinical pedo- dontics.
The subjects consisted of 50 children with a normal occlusion. They were divided into groups from IIA to IIIC according to Hellman's dental stages.
The muscles examined bilaterally were the anterior temporal muscle, the posterior temporal muscle and the superficial portion of the masseter muscle u- tilizing four established movements. The actions of the above muscles were recorded using electromyography (EMG).
An intergrator was used to handle the EMG data and the TA%, TP% and M%, which are the percentages of the total action potential of TA, TP and M, were caliculated to determine the quantity of the action between each average. As a result of the study, the authors arrived at the following conclusions.
1. In established actions such as gum free chewing, and maximum bite, no difference was found between men and women, or between the right and left side regarding TA, TP and M.
2. A difference was found as to how masticatory muscles are used for mastication in the deciduous dentition and in the permanent dentition. In short, the temporal muscle works mainly in the deciduous dentition; the other hand however the masseter muscle works mainly in the permanent dentition.
3. We suggest that growth and development were largely due to these changes.
