[Positional changes of temporomandibular joint disk and condyle with insertion of anterior repositioning splint].
OBJECTIVE
To measure the positional changes of temporomandibular joint (TMJ) disk and condyle with insertion of anterior repositioning splint (ARS) using magnetic resonance imaging (MRI) for further understanding of the splint therapy mechanisms.


METHODS
Twenty-two patients with temporomandibular joint clicks were included. 31 TMJs were diagnosed as anterior disk displacement with reduction (disk-displaced group), and the other 13 TMJs were normal (normal group). All joints were scanned oblique-sagittally by MRI before splint treatment in three positions including closed-mouth position of centric occlusion (the position before insertion of ARS), incisors' edge to edge position, and mandibular least forward protrusion position (the position after insertion of ARS).


RESULTS
1) Disk-condyle angle: In closed-mouth position, the average angle was 54.23 degrees in the disk-displaced group, while it was 9.80 degrees in the normal group; in incisors' edge to edge position and mandibular least forward protrusion position, the angle was reduced to normal in most of the disk-displaced cases. 2) Disk position: From closed-mouth position to incisors' edge to edge position or mandibular least forward protrusion position, the forward displaced disk moved backward significantly, while the disk with normal position did not change significantly in the three positions. 3) Condyle position: From closed-mouth position to incisors' edge to edge position or mandibular least forward protrusion position, the condyle moved forward and downward significantly both in the disk-displaced group and in the normal group.


CONCLUSIONS
With insertion of the splint, the condyle moved anteriorly and inferiorly and the disk moved posteriorly, most of the anterior displaced disks could be reduced to normal positions in the joint fossa. The result indicated that the splint protruded condyle forward and prevented the backward reduced disk from displacing forward again during mouth closing.
Chen
Hui-min
HM
Center for Temporomandibular Disorders and Orofacial Pain, School and Hospital of Stomatology, Peking University, Beijing 100081, China.
Fu
Kai-yuan
KY
Li
You-wei
YW
Zhang
Zhen-kang
ZK
D000328:Adult; D000368:Aged; D005145:Face; D005260:Female; D006801:Humans; D007180:Incisor; D004204:Joint Dislocations; D008279:Magnetic Resonance Imaging; D008297:Male; D008334:Mandible; D008335:Mandibular Condyle; D013165:Splints; D019224:Temporomandibular Joint Disc; D013705:Temporomandibular Joint Disorders