Investigation of the Mechanisms Involved in Periodontal Ligament Revascularization and Reinnervation Following Immediate Tooth Replantation in Rats.

Abstract

Background/aim: Tooth avulsion is characterized by the complete displacement of a tooth from its socket, and the recommended treatment is immediate replantation of the tooth. Despite this, the mechanisms involved in repairing the periodontal ligament following dental trauma remain unclear. Therefore, the objective of this research was to investigate the repair process of periodontal tissues after tooth avulsion and immediate replantation in Wistar rats.

Materials and methods: Twenty-four rats underwent extraction of the upper right incisors, followed by immediate replantation. The left teeth were left intact as controls. The animals were euthanized after 15 and 60 days, and histopathological evaluation, immunohistochemical staining (neurotrophin-4-NT-4, and platelet endothelial cell adhesion molecule-1-PECAM-1), and TUNEL-based apoptosis quantification were performed. Image deconvolution was used to analyze slides, applying hematoxylin and DAB filters. The "integrated density" and "area" tools measured staining intensity, with data presented as arbitrary units per μm². Data were analyzed using two-way ANOVA followed by Sidak's post-test at a significance level of 5%.

Results: Histopathological examination revealed an inflammatory response surrounding the replanted tooth, with mineralized tissue resorption occurring over time. After 15 days post-replantation, there was a significant increase in neurotrophin-4 (p = 0.0439) and platelet endothelial cell adhesion molecule-1 expression (p = 0.0389) compared with the control group (sound teeth). At 60 days, expression levels of these markers decreased and showed no significant difference compared to the control group (p > 0.05). Furthermore, replanted teeth showed a significantly higher amount of apoptotic cells compared with the control group, regardless of the period of investigation (p < 0.001).

Conclusions: This study indicate that proteins associated with angiogenesis and neurogenesis are present in the early stages of repair. Additionally, cell death was observed at both 15 and 60 days post-replantation.