Abstract
The characteristics of temporomandibular joint (TMJ) sounds such as clicking and crepitation have been assessed by many studies, however reports concerning sounds of asymptomatic joint are still scarce. Also, recording TMJ sounds with contact microphones is a difficult matter because several factors cause variation of the recordings.
The purpose of this study was to clarify the characteristics of TMJ sounds in normal subjects and to determine the location of an optimum recording site. TMJ sounds and mandibular movements in nine fully dentate, healthy subjects who had no history of TMJ pathology were respectively recorded with contact microphone and a jaw tracking device.
Three velocity parameters of jaw opening were studied in four recording sites. The results were as follows:
1. Sound of TMJ movement in normal subjects was distributed below 30 Hz with peak frequency of 2-4 Hz.
2. TMJ sounds picked up by the contact microphone were considered to be those associated with condylar movement within the joint.
3. Frequency of TMJ sound changed in relation to the recording site; and the magnitude of sound was also affected by the velocity of mandibular opening.
4. TMJ sounds generated by TMJ movement were best recorded when the contact microphone was located 20 mm anterior to the average condylar point.
