Experimental model of tooth movement by orthodontic force in mice and its application to tumor necrosis factor receptor-deficient mice

• DOI: 10.1007/s00774-005-0641-4
• Publication Date: 2005-12-21T03:42:57Z
• Authors: Masako Yoshimatsu; Yasuaki Shibata; Hideki Kitaura; Xin Chang; Takeshi Moriishi; Fumio Hashimoto; Noriaki Yoshida; Akira Yamaguchi
• Keywords: Mice, Knockout; Periodontium; Tooth Movement Techniques; Reverse Transcriptase Polymerase Chain Reaction; Tartrate-Resistant Acid Phosphatase; Tumor Necrosis Factor-alpha; Acid Phosphatase; Cathepsin K; Osteoclasts; Cathepsins; Biomechanical Phenomena; Isoenzymes; Mice; 03 medical and health sciences; 0302 clinical medicine; Receptors, Tumor Necrosis Factor, Type I; Models, Animal; Animals; Receptors, Tumor Necrosis Factor, Type II; Bone Remodeling; RNA, Messenger; Tooth

Orthodontic tooth movement is achieved by mechanical loading; however, the biological mechanism involved in this process is not clearly understood owing to the lack of a suitable experimental model. In the present study, we established an orthodontic tooth movement model in mice using a Ni-Ti closed coil spring that was inserted between the upper incisors and the upper first molar. Histological examination demonstrated that the orthodontic force moved the first upper molar mesially without necrosis of the periodontium during tooth movement. The number of TRAP-positive osteoclasts on the pressure side significantly increased in a time-dependent manner. Quantitative real time-based reverse transcription-polymerase chain reaction analysis demonstrated increased levels of mRNA for cathepsin K. Immunohistochemical staining revealed the expression of tumor necrosis factor-alpha (TNFalpha) in periodontium on the pressure side of the first molar during orthodontic tooth movement. When this tooth movement system was applied to TNF type 1 receptor-deficient mice and TNF type 2 receptor-deficient mice, tooth movement observed in TNF type 2 receptor-deficient mice was smaller than that in the wild-type mice and TNF type 1 receptor-deficient mice. The number of TRAP-positive osteoclasts on the pressure side was significantly small in TNF type 2 receptor-deficient mice compared with that in TNF type 1 receptor-deficient mice on day 6 after application of the appliance. The present study indicates that TNFalpha signaling plays some important roles in orthodontic tooth movement.