Possible role of immunocompetent cells and the expression of Hsp25 in the process of pulpal regeneration

本研究旨在通过热休克蛋白（Hsp） 25和ⅱ类主要组织相容性复合体（MHC）抗原的免疫细胞化学检测，阐明热休克蛋白（Hsp） 25在大鼠磨牙损伤后牙髓再生过程中的时间变化与表达的关系。分化成牙髓细胞具有强烈的热休克蛋白25免疫反应性。在牙损伤早期，造腔和再植牙均可引起成牙细胞层变性，导致牙髓内热休克蛋白25免疫反应丧失。在预备空腔后12-24小时和牙齿再植后3天，沿牙髓-牙本质边界出现大量II类mhc阳性细胞，并将细胞突起延伸至牙本质小管。在牙髓-牙本质边缘排列着新分化的具有Hsp - 25免疫反应性的成牙细胞样细胞，II类mhc阳性细胞在牙髓损伤后3-5天向成牙细胞亚层退退。因此，在两种不同的实验损伤后，牙髓再生过程中发生了共同的细胞事件。这些发现表明，hsp25免疫反应性表达变化的时间过程反映了成牙髓细胞的变性/再生过程，而II类mhc阳性细胞在牙髓-牙本质边界的时间出现表明它们参与了成牙髓细胞的分化以及牙髓再生过程中的初始防御反应。另一方面，在激光消融的情况下，术后3-5天在牙髓内发现明显的脓肿形成，由多形核白细胞组成。在预备腔下的牙本质小管中可见大量口腔细菌的渗透。这些结果表明，激光消融造腔术通过牙本质小管引起持续的细菌感染，引起明显的炎症反应。少

The purpose of the present study was to clarify the relationship between the chronological changes of immunocompetent cells and the expression of heat shock protein(Hsp) 25 in the process of pulpal regeneration after tooth injury in rat molars by immunocytochemistry for Hsp 25 and class II major histocompatibility complex(MHC) antigen. An intense Hsp 25-immunoreactivity was found in the differentiated odontoblasts. Both cavity preparation and tooth replantation caused the degeneration of the odontoblast layer to result in the loss of Hsp 25-immunoreactions in the suffered dental pulp at the early stages after tooth injury. Numerous class II MHC-positive cells appeared along the pulp-dentin border and extend their cell processes into the dentinal tubules at 12-24 hours after cavity preparation and 3 days after tooth replantation. Newly differentiated odontoblast-like cells with Hsp 25-immunoreactivity were arranged at the pulp-dentin border, and the class II MHC-positive cells retreated … More towards the subodontoblastic layer by postoperative 3-5 days after tooth injury. Thus, the common cellular events occur during pulpal regeneration following two different experimental injuries. These findings indicate that the time course of changes in the expression of Hsp 25-immunoreactivity reflects the degeneration/regeneration process of odontoblasts and that the temporal appearance of the class II MHC-positive cells at the pulp-dentin border suggests their participation in odontoblast differentiation as well as in initial defense reactions during the pulpal regeneration process. In the case of laser ablation, on the other hand, distinct abscess formation consisting of polymorphonuclear leukocytes was found in the dental pulp by 3-5 days postoperation. The penetration of masses of oral bacteria was recognizable in the dentinal tubules beneath the prepared cavity. These findings indicate that cavity preparation by laser ablation induces remarkable inflammation by continuous bacterial infections via dentinal tubules. Less