Osteoprotegerin and zoledronate bone effects during orthodontic tooth movement

Structured Objectives To assess the effects of local delivery of recombinant fusion protein osteoprotegerin (OPG‐Fc) and bisphosphonate zoledronate on bone and periodontal ligament in a rat tooth movement model. Materials and methods Maxillary first molars of 36 male Sprague–Dawley rats were displaced mesially using a calibrated spring connected to an anterior mini‐screw. Two different drugs were used: a single dose of Zoledronate (16 μg) and a twice‐weekly dose of OPG‐Fc (5.0 mg/kg) were injected. Tooth movement was measured on scanned plaster casts. Structural and immunohistochemical analysis of the orthodontic‐induced changes in bone included receptor activator of nuclear factor ĸ (RANK), Runx, type 1 collagen, matrix metalloproteinases (MMPs) 2 and 9, tissue inhibitors of metalloproteinases (TIMPs) 1 and 2, and vimentin. Results Both groups showed a reduction in mesial molar displacement. Animals receiving OPG‐Fc demonstrated only 52%, 31%, and 21% of the total mesial molar displacement compared to control rats at 7, 14, and 21 days, respectively (*p