再定位垫戴入前后颞下颌关节盘和髁突的位置改变

Positional changes of temporomandibular joint disk and condyle with insertion of anterior repositioning splint

目的测量再定位垫(ARS)戴入前后关节盘和髁突的位置改变,探讨ARS的治疗机制。方法选择22例单侧或双侧可复性颞下颌关节盘前移位患者进行研究,其中关节盘前移位的关节31侧,设为前移位组;关节盘位置正常的关节13侧,设为正常组。分别在闭口位(ARS戴入前)、对刃位和下颌最少前伸位(ARS戴入后)行磁共振成像扫描,测量不同下颌位置时的2组关节的盘突角度、关节盘和髁突位置的变化。结果1)盘突角度:闭口位时前移位组为54.23°,正常组为9.80°;对刃位和下颌最少前伸位时,前移位组的盘突角度多可回复至正常范围。2)关节盘位置:从闭口位至对刃位或下颌最少前伸位,正常组关节盘位置无明显改变,前移位组关节盘明显向后移动。3)髁突位置:从闭口位至对刃位或下颌最少前伸位,髁突在关节窝中向前下方移动,正常组与前移位组比较的差异无统计学意义(P>0.05)。结论ARS使髁突向前下方移动,关节盘向后回复。ARS的作用可能是阻止已经向后上方移动而复位的关节盘在闭口过程中再次发生前移位,起到固定作用。

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° in the disk-displaced group, while it was 9.80° 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. Conclusion 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.