Histologic and biochemical assessments on experimentally induced disk displacement of the craniomandibular joints.

诱导兔颅颌关节盘前移位。盘前移位7 mm后，在盘后组织前外侧缘放置缝线，固定于颧骨眶下部。分别于术后第2、3、5、8、24周评价其变化。术后第2、3周关节盘移位导致关节软骨肥大，第5周发生关节盘穿孔。随后观察到退行性关节炎的改变。在此基础上，设计了实验性移位术后第2周和第3周的二期复位术时间。结果，在第2周接受二次椎间盘重新定位的动物表现出从软骨层肥大和关节炎改变中恢复。然而，第3周的二次手术没有恢复，但软骨有进行性的关节炎改变。它们的变化类似于动物的髁突，没有二次手术。这些结果表明，对于关节盘前移位的情况，椎间盘复位手术的应用有一段时间的限制。该项目包括另一项与下颌骨髁状突骨折有关的动物实验。对青春期和成年兔的髁突进行人工旋转脱位，观察骨折块愈合过程。青春期动物的骨折完全愈合，不受脱位角度的影响。另一方面，在患有旋转脱位的成年动物中，骨折碎片的延迟和不完全愈合被注意到。这些结果表明，成人髁状突骨折宜采用切开复位术。随着骨折部位酶活性的评估，这一现象已经被不断地研究。

Anterior disk displacement was induced in the craniomandibular joint of the rabbits. A sutured thread was placed at the antero-lateral margin of retrodiscal tissue and fixed to infra-orbital portion of zygoma after 7mm anterior displacement of the disk. Postoperative changes were assessed at the 2nd, 3rd, 5th, 8th, and 24th week. Disk displacement induced hypertrophy of articular cartilage of the condyle at the 2nd and 3rd week, then developed disk perforation at the 5th week. Subsequently, degenerative arthritic changes were noted. Then, we devised the period of the secondary disk repositioning surgery at the 2nd and 3rd week after experimental disk displacement procedure. Consequently, animals that underwent secondary disk repositioning at the 2nd week showed recovery from hypertrophy and arthritic changes in the cartilage layer. However, secondary operation at the 3rd week showed no recovery, but progressive arthritic changes were noted in the cartilage. Their changes resembled animal condyles without secondary operation. These results indicated a limitation period of the application of disk repositioning procedure for the condition of anterior disk displacement.This project includes another animal experiment relating to mandibular condyle fracture. An artificial rotational dislocation was performed on condyle of adolescent and adult rabbits, then healing process of the fractured fragments were observed. Fractures in the adolescent animals showed complete healing, regardless dislocation angle of the condyle. On the other hand, delayed and incomplete healing of the fractured fragments were noted among adult animals with rotational dislocation of the condyle. These results suggested that open reduction was advocated for condylar fracture in human adults patients. This phenomenon has been continuously investigated with the assessments for enzymatic activities at the fracture site.