Evaluation of condylar distraction and joint space in temporomandibular disorders

Objective: To investigate condylar distraction in temporomandibular joints(TMJ) with unilateral disc displacement without reduction and in asymptomatic volunteers. Method: Each TMJs of 34 patients with unilateral disc displacement without reduction and 11 asymptomatic volunteers had been studied in terms of distraction movement. Besides, factors that considered to have an effect on distraction; such as age, sex, condyle position, disc position, joint space area or distance were also evaluated. Joint space, articular disc and condyle position measurements were performed on magnetic resonance images. Distraction movement was observed while subjects were unilaterally biting on acrylic, which is compatible with the occlusal morphology of first and second premolars, and first molar. Distraction movement is observed by detecting the condyle position with the aid of electronic condyle position programme on ultrasonic jaw motion analyser (Jaw Motion Analyser, Zebris, Germany). Findings: Ipsilateral biting caused distraction in TMJs with disc displacement without reduction. Compression occured in all other TMJs during ipsilateral bite. During contralateral bite, compression occured in all TMJs. The amount of compression movement is smallest in TMJs with disc displacement without reduction during contralateral bite. Amount of distraction movement wasn't affected by the factors such as age, sex, condyle and disc position, joint space area/distance. Conclusion: According to the findings of this study; TMJ disc must absolutely be displaced nonreducingly, for the condyles to be distracted for a therapeutic intention.