Orthodontic mechanotransduction and the role of the P2X7 receptor.

INTRODUCTION The P2X7 receptor plays a crucial role in bone biology and inflammation. Its main function is to promote necrotic tissue metabolism by ensuring a normal acute-phase inflammatory response. We used a mouse model to describe and compare orthodontic mechanotransduction in wild-type and P2X7 knock-out mice. METHODS By using finite element analysis, mouse orthodontic mechanics were scaled to produce typical human stress levels. External root resorption, bone modeling, and bone remodeling were analyzed with fluorescent bone labels, Masson trichrome stain, and microcomputed tomography. Relationships between the biologic responses and the calculated stresses were statistically tested and compared between mouse types. RESULTS There were direct relationships between certain stress magnitudes and root resorption and bone formation. Hyalinization and root and bone resorption were different in the 2 types of mice. CONCLUSIONS Orthodontic responses are related to the principal stress patterns in the periodontal ligament, and the P2X7 receptor plays a significant role in their mechanotransduction.