Methods: Ten DBA/1 mice were divided into two groups. Rheumatoid Arthritis (RA) group which were injected with type II collagen were compared to age-matched Control group(CTL). After sacrificing the mice, the left mandible from each group were used for micro-CT and histologic analysis. Concerning on the micro-CT analysis, alveolar bone loss was calculated as a distance and root surface area from cementoenamel junction to alveolar bone crest with 2-dimensional images. Alveolar bone density in the cancellous bone marrow was measured using 3-dimensional images.
The mandibles were fixed in 4% paraformaldehyde and then decalcified with 10% EDTA for paraffin embedding. Paraffin sections were deparaffinized, hydrated, and stained with H&E. Histologic findings were examined under the light microscope. The right mandibles were used for analysing osteoblastic osseoinduciton. Osteoblast was isolated by sequentional digestion method using collagenase and dispase. The osteoblsts were cultured and induced for osteogenic differentiation. Osteogenic differentiation was evaluated using alizarin red staining. Area of newly formed nodule was measured.
Results: Alveolar bone resorption in RA group was statistically significant than control group( p<0.05). Alveolar bone density was reduced in RA compared to control( p<0.05).. Histologically, osteoclastic activity on alveolar bone crest was significant in RA group( p<0.05). Furthermore, related with osteoblastic activity, osteogenic differentiation was reduced in RA group( p<0.05).
Conclusion: These results imply that RA could cause alveolar bone resorption and decrease bone density. It can be predicted that RA condition not only induce osteoclastic activity but also reduce osteoblastic activity.