Osteoclastogenesis in Local Alveolar Bone in Early Decortication-Facilitated Orthodontic Tooth Movement.
OBJECTIVE
In the current study, we aimed to investigate the effects of alveolar decortication on local bone remodeling, and to explore the possible mechanism by which decortication facilitates tooth movement.


METHODS
Forty rabbits were included in the experiment. The left mandible was subjected to decortication-facilitated orthodontics, and the right mandible underwent traditional orthodontics as a control. The animals were sacrificed on the days 1, 3, 5, 7 and 14, after undergoing orthodontic procedures. Tooth movement was measured by Micro-CT, and the local periodontal tissues were investigated using H&E, Masson's trichrome and tartrate-resistant acid phosphatase (TRAP) staining. The mRNA levels of genes related to bone remodeling in the alveolar bone were analyzed using real-time PCR.


RESULTS
On days 3, 5, 7 and 14, tooth movement was statistically accelerated by decortication (P<0.05) and was accompanied by increased hyperemia. Despite the lack of new bone formation in both groups, more osteoclasts were noted in the decorticated group, with two peak counts (P<0.05). The first peak count was consistent with the maximum values of ctsk and TRAP expression, and the second peak counts accompanied the maximum nfatc1 and jdp2 expression. The increased fra2 expression and the ratio of rankl/opg also accompanied the second peak counts.


CONCLUSIONS
Following alveolar decortication, osteoclastogenesis was initially induced to a greater degree than the new bone formation which was thought to have caused a regional acceleratory phenomenon (RAP). The amount of steoclastogenesis in the decorticated alveolar bone was found to have two peaks, perhaps due to attenuated local resistance. The first peak count in osteoclasts may have been due to previously existing osteoclast precursors, whereas the second may represent the differentiation of peripheral blood mononuclear cells which came from circulation as the result of hyperemia.
Department of Orthodontics, Peking University School and Hospital of Stomatology, 22 South Zhongguancun Avenue, Haidian District, Beijing 100081, China.|Department of Stomatology of the First Hospital of Jiaxing, 1882 Zhonghuan South Road, Nanhu District, Jiaxing 314001, China.
Ya-Wen
YW
Chen
Department of Pathology, School & Hospital of Stomatology, Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai 200072, China.
Hai-Cheng
HC
Wang
Department of Orthodontics, College of Stomatology, Dalian Medical University, 9 Lushun South Road West, Lushun Port District, Dalian 116044, China.
Long-Hua
LH
Gao
Department of Orthodontics, Shandong University School of Stomatology, 44 Wenhua West Road, Lixia District, Jinan 250012, China.
Chang
C
Liu
Department of Stomatology, Binzhou Medical University, 346 Guanhai Road, Laishan District, Yantai 264003, China.
Yu-Xi
YX
Jiang
Department of Orthodontics, College of Stomatology, Dalian Medical University, 9 Lushun South Road West, Lushun Port District, Dalian 116044, China.
Hong
H
Qu
Central Laboratory, Peking University School and Hospital of Stomatology, 22 South Zhongguancun Avenue, Haidian District, Beijing 100081, China.
Cui-Ying
CY
Li
Department of Orthodontics, Peking University School and Hospital of Stomatology, 22 South Zhongguancun Avenue, Haidian District, Beijing 100081, China.
Jiu-Hui
JH
Jiang
D000539:Alveolar Process / Q000166:cytology / Q000378:metabolism / Q000601:surgery*; D000818:Animals; D016723:Bone Remodeling; D005260:Female; D005786:Gene Expression Regulation; D010010:Osteoclasts / Q000166:cytology*; D010012:Osteogenesis; D010519:Periodontium / Q000648:ultrastructure; D012333:RNA, Messenger / Q000235:genetics; D011817:Rabbits; D014087:Tooth Movement Techniques / Q000379:methods*; D055114:X-Ray Microtomography
D012333:RNA, Messenger