Bisphosphonates (BPs) are commonly used medications to treat primary and metastatic bone cancer, as well as osteoporosis. Though BPs improve bone mineral density, reduce fracture risk, and reduce hypercalcemia of malignancy, many patients develop osteonecrosis of the jaws. BP related osteonecrosis of the jaws (BRONJ) is a devastating complication, presenting as clinically exposed bone in the maxillofacial region for more than 8 weeks. BRONJ is associated with severe pain, swelling, infection, fistulae, and jaw fracture, all of which significantly impact patients'quality of life. Despite the increasing number of BRONJ cases since the first report in 2003, the pathophysiology of the disease remains largely unknown. Two major impediments in exploring BRONJ etiology exist. First, many of our assumptions concerning alveolar bone (AB) cell function and differentiation are extrapolated from experimental models using cells from other skeletal sites. Second, there is no well-established BRONJ animal model to study the in vivo parameters of disease initiation and progression. In this application, we have addressed these two gaps. We have established a method for isolating AB marrow stromal cells (MSCs) and have demonstrated differences in the osteoblastic potential of AB vs. long bone (LB) MSCs, providing a relevant in vitro model to study differences between the craniofacial and appendicular skeleton. Moreover, AB MSCs express lower RANKL mRNA levels and are more sensitive to oxidative stress than their LB counterparts. Published studies and our own preliminary data demonstrate a significant role for dental disease in the pathophysiology of BRONJ. Excitingly, we have developed a rodent model of BRONJ. Equipped both with a model to study AB MSC differentiation in culture and with a BRONJ animal model, our objective is to explore molecular and cellular mechanisms of BRONJ. Based on our preliminary data, we hypothesize that BPs robustly suppress AB resorption at the area of periodontal inflammation. The high oxidative stress environment around the inflammatory nidus strongly decreases AB healing capacity and increases cell apoptosis. The net result of these processes is AB necrosis that presents clinically as BRONJ. To achieve our objective and test our hypothesis, we propose three specific aims: (1) To explore the necessary and sufficient requirement of bisphosphonate treatment and periodontal disease for BRONJ development in the rat;(2) To investigate the ability of AB vs. LB marrow to support osteoclastogenesis in the presence or absence of bisphosphonates;and (3) To investigate the AB vs. LB MSC sensitivity to oxidative stress in the presence or absence of bisphosphonates. The proposed studies will begin uncovering the mechanisms underlying BRONJ pathophysiology and will provide evidence for BP and dental disease involvement in BRONJ incidence. Understanding the mechanisms by which the oral environment is sensitive to oxidative stress and BP inhibition of bone remodeling may lead to novel therapeutic approaches to reduce BRONJ frequency, progression, and severity.

Public Health Relevance

Bisphosphonates are drugs used to treat bone metastasis in cancer patients and osteoporosis. However, bisphosphonate use has been associated with significant oral complications including exposure of the jaw bone, abscesses and jaw fractures. No treatment for these complications exists, because we do not understand the mechanisms of their development. In this application, we explore mechanisms of bisphosphonate related jaw necrosis and establish an animal model of the disease. Results of this research can potentially lead to novel therapeutic approaches that can reduce the incidence, severity, and progression of BRONJ.

National Institute of Health (NIH)
National Institute of Dental & Craniofacial Research (NIDCR)
Research Project (R01)
Project #
Application #
Study Section
Skeletal Biology Development and Disease Study Section (SBDD)
Program Officer
Wan, Jason
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of California Los Angeles
Schools of Dentistry
Los Angeles
United States
Zip Code
de Molon, Rafael Scaf; Hsu, Chingyun; Bezouglaia, Olga et al. (2016) Rheumatoid Arthritis Exacerbates the Severity of Osteonecrosis of the Jaws (ONJ) in Mice. A Randomized, Prospective, Controlled Animal Study. J Bone Miner Res 31:1596-607
de Molon, Rafael Scaf; Shimamoto, Hiroaki; Bezouglaia, Olga et al. (2015) OPG-Fc but Not Zoledronic Acid Discontinuation Reverses Osteonecrosis of the Jaws (ONJ) in Mice. J Bone Miner Res 30:1627-40
Hiyari, S; Atti, E; Camargo, P M et al. (2015) Heritability of periodontal bone loss in mice. J Periodontal Res 50:730-6
Aghaloo, Tara; Hazboun, Renna; Tetradis, Sotirios (2015) Pathophysiology of Osteonecrosis of the Jaws. Oral Maxillofac Surg Clin North Am 27:489-96
Pirih, F Q; Hiyari, S; Barroso, A D V et al. (2015) Ligature-induced peri-implantitis in mice. J Periodontal Res 50:519-24
Aghaloo, Tara L; Cheong, Simon; Bezouglaia, Olga et al. (2014) RANKL inhibitors induce osteonecrosis of the jaw in mice with periapical disease. J Bone Miner Res 29:843-54
Aghaloo, Tara L; Dry, Sarah M; Mallya, Sanjay et al. (2014) Stage 0 osteonecrosis of the jaw in a patient on denosumab. J Oral Maxillofac Surg 72:702-16
de Molon, Rafael Scaf; Cheong, Simon; Bezouglaia, Olga et al. (2014) Spontaneous osteonecrosis of the jaws in the maxilla of mice on antiresorptive treatment: a novel ONJ mouse model. Bone 68:11-9
Chaichanasakul, Thawinee; Kang, Benjamin; Bezouglaia, Olga et al. (2014) Diverse osteoclastogenesis of bone marrow from mandible versus long bone. J Periodontol 85:829-36
Cheong, Simon; Sun, Shuting; Kang, Benjamin et al. (2014) Bisphosphonate uptake in areas of tooth extraction or periapical disease. J Oral Maxillofac Surg 72:2461-8

Showing the most recent 10 out of 19 publications