Abstract: Objective: To evaluate the effect of agonist and inhibitor of Adrb2 on the alveolar bone micro-structure reconstruction and osteoclast proliferation during the movement of orthodontic teeth in rats. Methods: 64 female SD rats were randomly divided into four groups: isoproterenol group, propranolol group, negative control group, and saline group. The rat orthodontic teeth movement models were established. The rats were injected corresponding reagents according to weight and were sacrificed on day 0, 7, 14, and 21. The movement distance of first molar of rats was measured by Vernier caliper. The numbers of osteoclasts were observed through TRAP staining. The change of micro-structure of alveolar bone was evaluated by Micro-CT. Results: The trends of the distance of teeth movement and numbers of osteoclast were the same: isoproterenol group> saline group> propranolol group> negative control group (P<0.05). Absorption lacuna increasing at the pressure side of alveolars could be observed through HE staining in isoproterenol group, saline group, and propranolol group and the isoproterenol group was the most. The result of Micro-CT scan showed that isoproterenol could reduce BV/TV and MTPD, and increase Tb.sp, while propranolol was on the opposite. Conclusion: Isoproterenol could promote the resorption of alveolar bone at the pressure side and increase the osteoclast numbers so that the alveolar bone became looser which was beneficial to the movement of orthodontic tooth. On the contrary, propranolol could inhibit the proliferation of osteoclast, increase the density of alveolar, and slow down the movement of tooth.

Key words: β2 adrenergic receptor, Orthodontic tooth movement, Osteoclast, Alveolar bone remodeling