Surgery-triggered and non surgery-triggered Bisphosphonate-related Osteonecrosis of the Jaws (BRONJ): A retrospective analysis of 567 cases in an Italian multicenter study.

Invasive local procedures are often reported in clinical history of patients suffering from Bisphosphonates-Related Osteonecrosis of the Jaws (BRONJ) but over 40% of spontaneous forms have been also described in literature. We compared age, gender, underlying bone disorders, bisphosphonate therapy, clinical features and surgical outcome of 205 cases (36.2%) of BRONJ non surgery-triggered (group 1) with 362 (63.8%) cases of surgery-triggered forms (group 2). Differences between group 1 and 2 were analysed using Mann-Whitney U and χ(2) tests. Statistical analysis was performed using STATA 8. Zoledronate was the most used type of bisphosphonate (63.4% versus 69.0%) and the mandible was the most frequently involved site (63.9% versus 63.4%) in both groups. BRONJ in group 1 was more frequently multicentric (9.3% versus 5%, p<0.05), had a lower clinical stage (45.9% versus 13.8% in stage 1, p<0.01) and had a better outcome after surgical therapy (improvement in 74.1% versus 58.6%, p<0.05). The high prevalence of non surgery-triggered forms of BRONJ should be considered by oncologists, haematologists and general physicians who are advised to inform their patients regarding the importance of preventive dental protocols to control the possible causes of osteonecrosis not related to dental invasive procedures.