[TMJ radiographic bone alterations in patients of TMJDs]

The characteristics of temporomandibular joint (TMJ) bone changes showed by X-ray films in patients diagnosed as Temporomandibular Joint Disorders (TMJDs) were investigated.

X-ray films of 792 TMJDs patients who were diagnosised as TMJDs in our hospital from 1988 to 1995 were studied. Among them, 330 cases were male and 462 cases were female. Their ages ranged from 11 to 66 years old, averaged 27.4 years old. Bilateral TMJ, 1584 sides in all, were checked by X-ray. Among them, 210 cases (420 sides) were examined with transcraniall projective technique, 223 cases (446 sides) with tomogram, and 359 cases (718 sides) with both tomogram and transcranial projective techniques, Clinician observed and discussed the films together with the radiographer, and then the final radio-diagnosis was got.

1. 288 (25.31%) out of 1138 condyles examined with transcranial projective technique (temporal articular surface can not be observed accurately in this kind of films) and 82 (7.04%) out of 1164 condyles, 74 (6.36%) out of 1164 temporal articular surfaces checked with tomogram showed osseous changes. With analyzing on 718 sides of 356 cases checked with both methods, it was found that transcranial projective technique was more sensitive to TMJ osseous changes (P < 0.01). 2. The types of osseous changes: within the osseous changes of condyles showed in transcranial projection, 126 sides (43.75%) were mainly hyperplasia, and 140 sides showed absorptive changes. Moreover, both kinds of alterations appeared in 22 sides (7.64%). Among the condyles with osseous changes showed in tomogram, 28 sides were mainly hyperplasia and 54 sides showed absorptive changes, while two kinds of changes were not found in the same tomogram. But for temporal articular surface, 34 sides showed hyperplasia and 6 sides absorptive changes as their chief alterations. And the other 34 sides showed the two kinds of changes. Hyperplasia appeared more frequently in temporal articular surface than in condyles showed in tomogram (P < 0.01). 3. It was found that the osseous alterations were liable to occur in anterior condyle slope (88.19% in the films checked with transcranial projective technique, 81.71% in the films checked with tomography), the top (72.97% in the films checked with tomography) and the posterior slopes (71.62% in the films checked with tomography) of the articular eminence.

Being considered the characteristics of the osseous changes, the abnormal mechanics around ICP and physiological or pathological remodeling principles of different parts of TMJ might be explained. Further researches on the selection of the two examinational methods of TMJ were suggested.