Elucidation of the mechanism of post-repantation replacement resorption as a basis for the development of periodontal ligament regeneration therapy

以骨与牙根融合（强直）为特征的外部替代吸收是牙齿再植后不可控制的并发症。本研究是对再植后置换吸收的致病机制进行初步探讨。对大鼠磨牙进行即刻再植和次氯酸钠浸泡后再植两种不同条件下的实验性再植，并于术后1 ~ 3周采用组织学和免疫组织化学方法检测牙髓和牙周炎（PDL）组织病理变化。结果表明，naclo浸泡组牙髓和牙髓中表达cd68的巨噬细胞浸润比立即移植组更为明显(1)PDL的强直性改变，(2)牙髓中骨样组织形成，(3)牙髓和PDL中表达cd68的巨噬细胞浸润。这些结果表明，残留在根表面的PDL细胞受到严重损伤，引发了上述病理变化的发生。

External replacement resorption, characterized by the fusion of the bone and tooth root (ankylosis), is known as an uncontrollable complication after tooth replantation. This study was conducted as an initial exploration of the pathogenic mechanisms of post-replantation replacement resorption. Experimental replantation of rat molars were carried out in two different conditions (immediate replantation and replantation after sodium hypochlorite immersion), and pathological changes of the pulpal and periodontalligament (PDL) tissues were examined at 1 to 3 weeks postooperatively by means of histology and immunohistochemistry. Results demonstrated that (i) ankylotic changes in the PDL, (ii) bone-like tissue formation in the pulp, and (iii) CD68-expressing macrophage infiltration in the pulp and PDL were more prominent in the NaClO-immersed group than in the immediately replanted group. These findings suggest that severe damage to the PDL cells remaining on the root surface triggers the development of the above-mentioned pathological changes.