LOCAL APPLICATION OF THE BISPHOSPHONATE ZOLEDRONATE TO PROVIDE MAXIMUM ANCHORAGE FOR EXTRACTION SPACE CLOSURE IN RATS

Introduction: Orthodontists traditionally have used various compliance-dependent physical means such as headgears and various intraoral appliances to prevent anchorage loss. The aim of this study was to determine if local application of the bisphosphonate zoledronate could be used to prevent anchorage loss during extraction space closure in rats. Methods: The upper left 1st molar was extracted and the upper left 2nd molar was protracted into the extraction space with a 10g NiTi closing coil for 21 days. Fifteen controls received a local injection of phosphate-buffered saline, while fifteen experimentals received 16 g of the bisphosphonate zoledronate. The solution was also delivered directly into the extraction site and left undisturbed for five minutes. Cephalograms and incremental thickness gauges were used to measure tooth movements. Tissues were analyzed by CT and histology. Results: The control group demonstrated significantly greater tooth movements, beginning in the second week. The experimental group showed no significant tooth movement after the first week. CT and histological observations in the control group revealed significant bone loss in the extraction site and around the 2nd molar, while the experimental group demonstrated bone preservation and bone fill. There was no evidence of bisphosphonate-associated osteonecrosis in any of the samples. Conclusions: A single, small, locally-applied dose of zoledronate safely provided maximum anchorage while preventing significant bone loss. Zoledronate holds great potential to be used in dentistry