In the outpatient clinic, we have many patients who suffer from temporomandibular joint disorders. These vary from MPD syndrome to osteoarthrosis, and many cases have tender spots or areas on the temporomandibular joint region and/or masticatory
muscles. Further, they frequently have masticatory muscle pain when opening the jaw.
This paper presents the results of our research on the idfferential diagnosis for tendernesses and pain on opening the jaw in the temporomandibular joint region and the masticatory muscles by joint cavity pumping with local anesthestic.
The areas of tenderness and jaw-opening pain in 65 patients suffering from temporomanaibular joint disorder were examined and recorded before and after anesthetizing the upper joint cavity with 2% lidocaine. Maximum interrincisal distance was
similarly
recorded.
@ES The results were as follows:
@EN in the area surrounding the upper joint cavity including the lateral pterygoid muscle, the tenderness and jaw-opening pain vanished almost entirely after anesthesia. This was considered a direct infiltrative effect of the local anesthesia.
After the anesthesia, 86% of the tendernesses on the sternocleidomastoid muscles, and 66% of those on the posterior belly of the diagstric muslces vanished, while the disappearance rates on the masseter, temporal, and medial pterygoid muscles
were
50~60%.
Apart from the temporomandibular region, pain on opening the jaw was found on the masseter, temporal, posterior belly of the ditgastric muscles, and medial prterygoid muscles before anesthesia. The disappearance rates after anesthesia were
90~100%
except for the pain of the posterior belly of the digastric muscles, for which the rate was 66%.
These results suggest that more than 88% of the tendernesses on the sternocleidomastoid muscle, more than 60% of the tendernesses and jaw-opening pains on the digastric muscle, and more than half of the tendernesses and almost all of the
jaw-opening
pains in the jaw-closing muscle are referred pains from the temporomandibular joint.
The tendernesses that had no change after anesthesia were considered to be derived from spasms of the muscles proper.
Generally, maximum interincisal distance increased after anesthesia. The average distance was 34mm before anesthesia, but increased to 41mm after anesthesia. In a few cases, however little or no change was found in those distances. In these
cases,
pathological changes were found in the joint cavities arthrographically or arthroscopically.
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