TITLE:
TNF-α and RANKL facilitates the development of orthodontically-induced inflammatory root resorption
AUTHORS:
Tadashi Kojima, Masaru Yamaguchi, Tomokazu Yoshino, Mami Shimizu, Kunihiko Yamada, Takemi Goseki, Kazutaka Kasai
KEYWORDS:
TNF-α; sRANKL; Orthodontic Root Resorption; Gingival Crevicular Fluid
JOURNAL NAME:
Open Journal of Stomatology,
Vol.3 No.9A,
December
11,
2013
ABSTRACT: Background: The objective of this study was to determine the
levels of tumor necrosis factor-alpha (TNF-α)
and receptor activator of NF-kB ligand (RANKL) in the gingival crevicular fluid
(GCF) in patients with severe root resorption after orthodontic treatment.
Materials and Methods: Ten patients who had been receiving orthodontic
treatment (5-control subjects and 5-severe root resorption subjects) participated
in this study. GCF was collected from all patients. Subjects with severe root
resorption (>1/3 of the original root length) were identified. Control group
subjects with no loss of the root structure undergoing orthodontic treatment
were also identified. The GCF was collected non-invasively from the mesial
and distal sides of each of the upper central and lateral incisors using filter
paper strips. The eluted GCF was used for a Western blot analysis with Antibodies against TNF-α and soluble RANKL (sRANKL). Ten male 6-week-old Wistar
rats were subjected to orthodontic force of 50 g to induce a mesially tipping
movement of the upper first molars for 7 days. The expression levels of TNF-α and RANKL proteins were determined in
periodontal ligament (PDL) by immunohistochemical analysis. Results: The Western
blot analysis showed that the TNF-α and sRANKL expressions were significantly higher in the severe root resorption
group than in the control group. In the experimental tooth movement in vivo, resorption lacunae with multinucleated cells were observed in
50 g group. The immunoreactivity for TNF-α and RANKL was detected in PDL tissue subjected to the orthodontic
force on day 7. Conclusion: These results suggest that TNF-α and RANKL play important roles in
inducing or facilitating the development of orthodontically-induced inflammatory
root resorption (OIIRR).