The effect of high concentration of zoledronic acid on tooth induced movement and its repercussion on root, periodontal ligament and alveolar bone tissues in rats.

Zoledronic acid (ZA) is often prescribed for osteoporosis or resorptive metabolic bone disease. This study aims to evaluate the effect of ZA on orthodontic tooth movement (OTM) and root and bone resorption and its repercussion on root, periodontal ligament and alveolar bone tissues. The experimental group consisted of 72 Wistar rats divided in four subgroups: Naive, Saline and Zoledronic Acid groups at the concentration of 0.2 mg/kg [ZA (0.2)] or 1.0 mg/kg [ZA (1.0)]. The animals were subjected to i.v (dorsal penile vein) administrations of ZA or saline solution, on days 0, 7, 14 and 42. Under anesthesia, NiTi springs were installed in the first left maxillary molar with 50gf allowing the OTM, except for the negative control group (N) for mesial movement of the left first maxillary teeth. The animals were sacrificed and maxillae were removed for macroscopic and histopathological analyzes, scanning electron microscopy, computerized microtomography and confocal microscopy. Treatment with ZA decreased the OTM and the number of osteoclasts and loss of alveolar bone when compared to the naive and saline groups. Reduction of radicular resorption, increased necrotic areas and reduced vascularization in the periodontal ligament were observed in the ZA groups. ZA interferes with OTM and presents anti-resorptive effects on bone and dental tissues associated with a decreased vascularization, without osteonecrosis.