REFLEX RESPONSES OF THE MASSETER MUSCLE IN PATIENTS WITH CHRONIC ARTHRITIS OR INTERNAL DERANGEMENT OF THE TEMPOROMANDIBULAR-JOINT - A COMPARISON WITH SYMPTOM-FREE SUBJECTS
T. Bjornland et al., REFLEX RESPONSES OF THE MASSETER MUSCLE IN PATIENTS WITH CHRONIC ARTHRITIS OR INTERNAL DERANGEMENT OF THE TEMPOROMANDIBULAR-JOINT - A COMPARISON WITH SYMPTOM-FREE SUBJECTS, Journal of oral rehabilitation, 23(12), 1996, pp. 805-810
Averaged reflex responses in the masseter muscle to transverse taps de
livered to the upper central incisor were studied in 13 patients with
chronic arthritic temporomandibular joint (TMJ) disease (arthritis gro
up) and 28 patients having internal TMJ derangement (derangement group
). The diagnostic assessment of TMJ disease was based on a combination
of imaging methods. Fourteen symptomfree subjects served as a control
for the electromyographic observations. The tapping force was increas
ed in steps from 0.25 to 6 N. The pattern of the reflex response consi
sted of various inhibitory and excitatory waves, which were found to c
hange with increasing tapping force. The first inhibitory wave (I-1) i
ncreased in duration with increasing tapping force in all subjects. At
certain tapping forces, I-1 was of significantly lower amplitude and
longer duration in the arthritis group than in the control group, but
latency and threshold did not differ. The excitatory wave seemed to ha
ve longer latency and higher amplitude in the arthritis group than in
the control subjects at some tapping forces. In summary we conclude th
at the pattern of the reflex response seemed to be similar in patients
with different TMJ disorders and in symptomfree subjects. Only the le
vel of inhibition, duration of I-1 and higher excitatory response, mig
ht separate the patients with arthritic TMJ disease and internal TMJ d
erangement from symptomfree subjects, but no specific differences betw
een the groups could be found.