Abstract
It is now widely known that the silent period (SP) would appear on the EMG of masticatory muscles in adults. However very few studies have been made with children especially during the state of deciduous dentition. The present study was so designed to investigate the phase of SP and latency (La) in children and to compare this with that of adults and to attempt the possibility of any clinical application of SP on the functional diagnosis of occlusion in children.
Fifteen children and eleven adults were subjected to the test and the electromyographic activities in the anterior temporal and masseter muscles during tooth tapping were recorded bilaterally and occlusalsounds recorded from the forehead of the subjects were monitored. The metal overlay was placed on the mandibular right deciduous second molar of five children out of 15 to cause an intentional occlusal interference and its effect on EMG changesparticularly on the duration of SP was critically evaluated.
The results obtained in the present study were as follows:
1. Occurence of SP during tooth tapping wassignificantly lower among the children (92.7%) than among the adults (100%).
2. There were no significant differences in La between children and adults. Making a comparison of muscles ipsilaterally, La oftemporal muscles was significantly longer than that of the masseteramong the children, but no differences were noticed among the adults.
3. The duration of SP was significantly longer inchildren than in adults. Making a comparison of muscles ipsilaterally, SP ofmasseter muscles was significantly longer than that of the temporalis in both groups.
4. There was little influence on the duration of Laafter intentional occlusal interference.
5. The duration of SP increased significantly from immediately after placement of overlay to its removal, but showed a declining tendency with respect to its initial value with elapsed time. In comparison of interfered and non-interfered sides, no differences in the duration of either La and SP were found.
These results suggest that it is possible to apply the duration of SP clinically to the functional diagnosis of occlusion in children.
