The 99mTc-medronate scintigrams of patients with skeletal metastases and BP use (n = 40) were individually matched with cancer patients without BP exposure (n = 40) and controls with neither malignancy nor BP use (n = 40). Patients with established ONJ or intense focal abnormalities in the studied regions were excluded. Mandibular (MBT) bone turnover was quantified relative to the femur by defining regions-of-interest with correction for background activity.
The patients with BP exposure (34 female, 6 male) had a median age of 63 years (range 25–81) and received a median number of 11 zoledronic acid administrations (range 1–44). Most patients suffered from breast cancer (n = 30). The mean ratio of the MBT in cancer patients with BP use over non-users was 0.88 (95 % CI 0.80–0.96; p = 0.003), and 0.83 (95 % CI 0.73–0.94; p = 0.001) when BP using oncological patients were compared with controls without malignancy or BP use. The ratio of MBT’s between BP naive patients was 0.95 (95 % CI 0.83–1.07; p = 0.8). No dose–response effect between the number of BP administrations and MBT could be demonstrated (r = 0.02; p = 0.9).
These findings suggest that, relative to the femur, BP exert a stronger effect on mandibular bone turnover, which strengthens the hypothesis that the inhibition of bone turnover may be important in the pathophysiology of ONJ.