RESUMEN
OBJECTIVE: Low dose propranolol has previously been demonstrated to suppress bone remodelling. Therefore, its effect on orthodontic movement was tested. DESIGN: Rats were assigned as follows (n=5): animals with no orthodontic appliance (G1); the remaining groups were fitted with a Ni-Ti closed-coil spring ligated to the upper left first molar and connected to the incisors using metal and resin and received vehicle only (G2), 0.1mg/kg (G3) or 20mg/kg (G4) of propranolol orally. Cone Beam Computed Tomography was performed using high resolution for image capture. The distance between the first and second upper molars, both with and without the orthodontic appliance, was measured in millimetres. Gingival tissue was harvested and assessed for IL-1ß and IL-6 using ELISA and for ICAM-1 and RANKL by Western blotting. RESULTS: The orthodontic appliance induced a significant tooth movement in G2 when compared to the animals without an orthodontic appliance (G1) (p<0.05). The animals from G3 showed a significantly reduction in tooth movement (p<0.05) when compared with rats from G2. Animals treated with 20mg/kg of propranolol (G4) showed tooth movement similar to that of G2. The reduced tooth movement observed in the animals treated with 0.1mg/kg of propranolol (G3) occurred due to decreased amounts of IL-1ß and IL-6, in addition to lower ICAM-1 and RANKL expression. CONCLUSIONS: Low dose propranolol inhibits bone remodelling and orthodontic movement.
