OBJECTIVETo compare the clinical appearances of TMD patients between acute and chronic anterior disc displacement without reduction.

METHODSSuccessive one hundred TMD patients with fully recorded documents diagnosed as anterior disc displacement without reduction (ADDw/oR) were included, 45 acute and 55 chronic ADDw/oR patients. Clinical appearances including signs and symptoms, maximal mouth opening, Fricton's craniomandibular index, condylar bone changes on radiograms, findings on arthrograms and MRI were compared.

RESULTSThe main reason for asking treatment was joint pain in chronic, instead of limited mouth opening in acute patients. Clinical symptoms such as pain and limited mandibular movement showed improvement in chronic patients. Fricton's joint dysfunction index was higher in acute than in chronic patients, but muscle palpation index was higher in chronic than in acute patients, but Fricton's craniomandibular index was not significantly different between chronic and acute patients. The destructive bone changes of condyle on radiograms, the damage of stretched disc attachment on arthrograms and the morphological deformed disc on MRI were more frequently found in chronic than in acute patients.

CONCLUSIONSIn acute patients there is a great likelihood that tissues are healthy and not morphologically changed, we suggest that early and efficacious intervention should be made to reposition the anterior displaced disc that may block the progress of pathological impairment to both the disc and the condyle of TMJ.