Magnetic Resonance Examination And Diagnosis In Anterior Disc Displacement Of Temporomandibular Joint

Anterior disc displacement of temporomandibular joint which occurs commonly clinically is one type of temporomandibular joint disorders (TMD). Previous diagnostic method is to observe disc displacement and morphologic change according to clinical symptom, tomography (X-ray) or shadowgraph technique indirectly. Because of special principle of magnetic resonance (MR), it can observe the articular disc and its relative structure directly, and no trauma or radioaction. Therefore it can be applicable to examine TMD.ObjectiveStudy anatomic structure morphous, position and signal change in temporomandibular joint area of anterior disc displacement patients, and explore the effect of MR to this disease.Methods1. Objects selection: 15 anterior disc displacement patients according to clinical symptom and X-ray 18 sides TMJ were selected as case group; other 15 volunteers with no clinical symptom 30 sides TMJ were selected as contrast group.2. MR examination: Using the Signo Excite 3.0 MR machine produced by GE company, both TMJ sides' special position of volunteers' and patients' were scanned and imaged in the open-mouth procedure with the established optimum scanning method. 3. Image analysis: The anatomic structure in the TMJ area were analyzed qualitatively and quantitatively in the scanning procedure, then the variation and relative numerical value were gained ,and finally the diagnostic criteria of anterior temporomandibular disc displacement were established by statistical analysis of all cases.(1) Measure disc prezone and postzone positions at closed mouth position in oblique anteroposterior axes images of patients and the normal respectively, and then do the statistical analysis.(2) Measure disc-condyle relationships at special position when opening mouth in oblique anteroposterior axes images of patients and the normal respectively, and then do the statistical analysis.(3) Measure every disc band thickness at closed and maximum open-mouth position in oblique anteroposterior axes image of patients and the normal respectively, and then do the statistical analysis.(4) Measure condyle motion ranges at maximum open-mouth position in oblique anteroposterior axes images of patients and the normal respectively, and then do the statistical analysis.(5) Observe effusion in articular cavity at closed mouth position in oblique anteroposterior axes image of patients and the normal respectively, and then do the statistical analysis.Results1. At closed mouth position the disc anterior displacement mainly occur postzone, and prezone displacement is not obvious.2. The disc-condyle relationship can be used to diagnose anterior disc displacement and its type. There is evident difference in disc-condyle relationship at closed and 5mm open-mouth position of anterior disc displacement with reduction (ADDR) patients and the normal. There is not evident difference in disc-condyle relationship at 25mm and maximum open-mouth position of ADDR patients and the normal. There is evident difference in disc-condyle relationship at closed and 5mm open-mouth position of anterior temporomandibular disc displacement without reduction (ADDWR) patients and the normal. There is evident difference in disc-condyle relationship at 25mm and maximum open-mouth position of ADDWR patients and the normal.3. The articular disc morphous changes in patients. At closed mouth position, disc postzone is thicker than prezone which is also thicker than intermedial zone in the normal and patients. At maximum open-mouth position disc postzone is thicker than prezone which is also thicker than intermedial zone in the normal and patients; Disc intermedial zone is thicker at maximum open-mouth position than at closed mouth position in the normal, and is thinner at maximum open-mouth position than at closed mouth position in patients; At closed mouth position, prezone and intermedial zone in patients are thicker than in the normal, and postzone has no evident difference. At maximum open-mouth position, prezone and postzone are thicker in patients than in the normal, and intermedial zone has no evident difference.4. There is no evident difference of Condyle motional range in patients and the normal which explains that merely depending on Condyle motion range has limit to diagnose anterior disc displacement.5. Effusion in patients' cavitas articularis is more than that in the normal.ConclusionsMagnetic resonance imaging can clearly reflect the TMJ and its relative anatomic structure, especially the disc position, morphous and signal change, and it has great assistant effection to clinically diagnose anterior disc displacement.