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

在兔颅下颌关节内诱导关节盘前移位。在椎间盘后组织的前外侧边缘放置缝合线，并在椎间盘向前移位7mm后将其固定在眶下部分。术后第2、3、5、8、24周分别进行评估。第2、3周关节盘移位导致髁突关节软骨肥大，第5周发生关节盘穿孔。随后，观察到退行性关节炎变化。然后，我们设计了实验性椎间盘移位手术后第2和第3周的第二次椎间盘复位手术时间。因此，在第2周接受二次椎间盘复位的动物显示软骨层从肥大和关节炎变化中恢复。然而，第3周的二次手术显示没有恢复，但在软骨中观察到进行性关节炎变化。其变化类似于动物髁突，无需二次手术。这些结果表明，在盘前移位的情况下，盘复位术的应用有一定的局限性。本项目包括另一项与下颌骨髁突骨折相关的动物实验。对青少年和成年兔髁状突进行人工旋转脱位，观察骨折块的愈合过程。无论髁突脱位角度如何，青春期动物的骨折均显示完全愈合。另一方面，在成年动物中观察到髁状突旋转脱位的骨折碎片愈合延迟和不完全。这些结果表明，开放复位，提倡在人类成年患者髁状突骨折。这一现象已被不断调查的酶活性在骨折部位的评估。

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.