Macro H2A.1 immunohistochemical expression in an “in vivo” model of orthodontic dental movement

Aim : The present study aimed to verify the histone MacroH2A.1 immunohistochemical expression and localization after orthodontic force application on rat maxillary molars to deep insight the molecular mechanisms involved in tooth movement. Materials and Methods : Sixteen Sprague-Dawley rats were used as previously described. Tooth movement was induced, and rats were then killed. Molar-bearing segments of alveolar bone were cut from each side and further fixed in paraformaldehyde, decalcified, and then dehydrated. Specimens embedded in paraffin, including the crestal areas mesial and distal to the maxillary molars, were cut by microtome and processed for immunohistochemistry to detect macroH2A.1 according to literature protocols. Results : On the compression side, MacroH2A.1 was strongly immunostained in the spindle round cells of PDL, in cementoblast cells of root teeth and osteoclasts of alveolar bone. Sections also showed vacuolization of odontoblastic layer near to the pulp tissue. Alveolar bone evidenced the presence of marrow spaces. On the tension side, odontoblastic cells near to pulp tissue take spindle shape and showed a Journal of Oral Pathology and Medicine - Proof for Peer Review for Review Only scattered cell immunolabelling. Negative controls showed no immunolabelling. Conclusions : The results of the present study demonstrated overexpression of MacroH2A.1, on the compression side, after orthodontic force appliance suggesting a role of this histone in the remodeling of alveolar bone nonetheless further molecular analysis will be helpful to understand the specific involvement of MacroH2A.1 in orthodontic mechanical stress.