Abstract
Employing a microphone especially contructed for the purpose, we recorded occulusal sound from 158 subjects. Thirty recordings were made per subject with instructions to the subjects given by tooth tapping. As a matter of course, a general dental examination as well as investigation for occlusal abnormality was given to each subject. Clear occlusal sound was collected from 130 of the subjects. The waveform changes due to the presence of malocclusion were studied with attention given to the general shape of the wave, as well as the duration and the maximum amplitude of the sound.
The results were:
1) In deciduous dention, a sliding sound was predominant in both abnormal and normal occlusion groups. The incidence of the impact sound increased from III B to IV A after which the radio of the sounds reversed.
2) The incidence of impact sound was higher in normal occlusion for whole dentition groups.
3) Among subjects with normal occlusion, there was no significant difference between the left and right side nor dentition and maximum amplitude in accordance with maturation of dentition.
4) The variation in maximum amplitude was greater than that in duration between subjects and groups.
5) There was no significant difference in maximum amplitude between the normal and abnormal groups.
6) The duration of occlusal sound was significantly greater in the abnormal group.
