Intranuclear delivery of nuclear factor‐kappa b p65 in a rat model of tooth replantation

After avulsion and replantation, teeth are at risk of bone and root resorption. The present study aimed to demonstrate that the intra‐nuclear transducible form of transcription modulation domain of p65 (nt‐p65‐TMD) can suppress osteoclast differentiation in vitro, and reduce bone re-sorption in a rat model of tooth replantation. Cell viability and nitric oxide release were evaluated in RAW264.7 cells using CCK‐8 assay and Griess reaction kit. Osteoclast differentiation was evaluated using quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) and tartrate‐re-sistant acid phosphatase (TRAP) staining. Thirty‐two maxillary rat molars were extracted and stored in saline (n = 10) or 10 μM nt‐p65‐TMD solution (n = 22) before replantation. After 4 weeks, specimens were scored according to the inflammatory pattern using micro‐computed tomography (CT) imaging and histological analyses. nt‐p65‐TMD treatment resulted in significant reduction of nitric oxide release and osteoclast differentiation as studied using PCR and TRAP staining. Further, micro‐CT analysis revealed a significant decrease in bone resorption in the nt‐p65‐TMD treatment group (p < 0.05). Histological analysis of nt‐p65‐TMD treatment group showed that not only bone and root resorption, but also inflammation of the periodontal ligament and epithelial insertion was significantly reduced. These findings suggest that nt‐p65‐TMD has the unique capabilities of regulating bone remodeling after tooth replantation.