Histological assessment of intra-cortical bone formation rate in the mandible. Bone formation rate (BFR, %/year), measured using fluorochrome labels administered toward the end of the experiments, was separately assessed in the alveolar (A) and non-alveolar (B) bone at a region distant from the extraction site, at the extraction site allowed to heal for 4 weeks, and at the extraction site allowed to heal for 8 weeks. At all regions analyzed, the BFR was significantly lower in zoledronic acid-treated (ZOL) animals compared to controls (CON). In both CON and ZOL groups, there was no difference in BFR at 4 weeks post extraction yet significantly higher rates at 8 weeks post-extraction in the alveolar region. p < 0.05 versus non-extraction and 4 week healing region within treatment (#) or versus CON-treatment within region (*).