The change of periodontium after extraction of periodontally involved tooth in rats

Abstract

Recent interest has focused on intentional replantation as an alternative choice to restore an original tooth instead of replacing it with prosthesis or an implant. Some studies dealing with immediate replantation has shown successful results with intentional replantation for periodontally involved teeth. For long-term success of replantation, a healthy periodontal status of recipient site is required so that delayed replantation is more suitable for periodontally involved teeth.To reveal the ideal timing for delayed replantation of periodontally involved teeth, healing process of extraction sockets after extraction of periodontitis-induced teeth in rats were evaluated. Twenty eight rats were randomly divided into two groups; control group (n=8) and test group (n=20). In the test group, periodontitis was induced by a ligature around the cervix of mandibular first molar of all rats. Two weeks later, the mandibular first molars were extracted in all animals of control and test groups. The animals were sacrificed on days 0, 3, 7 and 10 after extraction (n=2 in control group and n=5 in test group on each day) and mandibles were retrieved for histological and immunohistochemical analysis. The change in amount of inflammatory cells and cytokines such as interleukin (IL)-6 and tumor necrosis factor (TNF)-α were quantified.In histological analysis of test group, inflammatory cell infiltrate was found abundantly in the remaining periodontium at the first 3 days after tooth extraction and decreased gradually at later time points. In immunohistochemical analysis of test group, both IL-6 and TNF-α were numerous in the furcation area at each post-extraction day. IL-6 was stained more heavily at between 3 and 7 days after extraction; at days 10 after extraction, little staining was observed. TNF-α staining was more intense at 3 days after extraction and gradually became weaken at later time points. Within the limits of this study, it takes at least 10 days to resolve periodontal inflammation in rat extraction socket. Further studies are required to reveal the effect of delayed replantation in human model and compare between immediate and delayed replantation of periodontally involved teeth.