Adverse mandibular bone effects associated with kidney disease are only partially corrected with bisphosphonate and/or calcium treatment

Bone Biology Laboratory http://www.iupui.edu/~bonelab/ Department of Anatomy and Cell Biology Indiana University School of Medicine Department of Biomedical Engineering IUPUIBackground/Aims: Patients with chronic kidney disease (CKD) have high prevalence of periodontal disease that may predispose to tooth loss and inflammation. The goal of this study was to test the hypotheses that a genetic rat model of progressive CKD would exhibit altered oral bone properties and that treatment with either bisphosphonates or calcium could attenuate these adverse changes. Methods: At 25 weeks of age, rats were treated with zoledronate, calcium gluconate, or their combination for 5 or 10 weeks. Mandible bone properties were assessed using micro-computed tomography to determine bone volume (BV/TV) and cementenamel junction to alveolar crest distance (CEJ-AC). Results: Untreated CKD animals had significantly lower BV/TV at both 30 (-5%) and 35 (-14%) weeks of age and higher CEJ-AC (+27 and 29%) compared to normal animals. CKD animals had significantly higher PTH compared to normal animals yet similar levels of C-reactive protein. Zoledronate-treatment normalized BV/TV over the first 5 weeks but this benefit was lost by 10 weeks. Calcium treatment, alone or in combination with zoledronate, was effective in normalizing BV/TV at both time points. Neither zoledronate nor calcium was able to correct the higher CEJ-AC caused by CKD. Calcium, but not zoledronate, significantly reduced serum parathyroid hormone (PTH) while neither treatment affected C-reactive protein. Conclusions: 1) this progressive animal model of chronic kidney disease shows a clear mandibular skeletal phenotype consistent with periodontitis, 2) the periodontitis is not associated with systemic inflammation as measured by C-reactive protein, and 3) reducing PTH has positive effects on the mandible phenotype.This work was supported by NIH grant (AR058005). We would like to thank Dr. Xianming Chen, Mr. Alex Carr and Mr. Drew Brown for their assistance with the biochemical assays, breeding colony and micro CT scanning/analysis, respectively