MRONJ refers to non-healing bone in the mandible or maxilla that persists for more than eight weeks in a person who received a systemic drug known to cause osteonecrosis of the jaws but who has not received radiation to the jaws. To date Bisphosphonates, RANK-L inhibitors and anti-angiogenic medications have been implicated in the onset of MRONJ.
Bisposphonates work by binding to the hydroxyapatite crystals in bone and inhibiting bone resorption by the osteoclasts. They do so by not only killing the osteoclasts directly, but also by inhibiting osteoclast precursor cells. By reducing breakdown of bone, there is less mineral release back into circulation and consequently, serum calcium levels are lowered.
Oral bisphosphonates are often used in the treatment of osteoporosis. Osteoporosis is a disease where reduced bone strength increases the risk for fracture. Osteoporosis may be due to lower than normal peak bone mass and greater than normal bone loss, making bisphosphonates a nearly perfect drug to use to treat it.
Oral bisphosphonates, including Fosamax, Actonel and Boniva are also often used to treat osteopenia. IV versions for cancer have a similar, exceedingly long half life like the oral bisphosphonates but are up to 10,000 times more potent, leading to increased risk of MRONJ with their use.
The next class of drugs shown to be associated with MRONJ is RANK-L Inhibitors. RANK-L is a protein that works to control bone regeneration and remodeling. These drugs work by arresting the development and maturation of osteoclasts as well as inhibition of the function of mature osteoclasts. These drugs do not irreversibly bind to the mineral matrix within bone and have a half-life of only 26 days. It comes in two forms, Prolia: which is given subcutaneously for the treatment of osteoporosis and Xgeva, also given subcutaneously in the treatment of bony metastases.
Prevention is the best form of treatment. Early screening and interceptive dental care will lead to a 3-fold reduction in incidence of osteonecrosis. Extraction of hopeless teeth, periodic recall, and fluoride trays should be provided.
Despite prevention, surgery does arise for those who have begun therapy. If therapy is for cancer, the patient can have routine dental care, no osseous surgery, and root canal therapy with coronectomy for non-restorable teeth.
For patients being treated for osteoporosis, if they have been treated for less than 4 years and have not been on corticosteroids, anti-angiogenic medications then no alteration or delay in planned surgery is necessary. However it is recommended to obtain informed consent with implant placement. In patients who have been treated with bisphosphonates for greater than 4 years, it is recommended to stop bisphosphonates 2 months prior to surgery and restart after osseous healing has occurred.
It always best to have an oral and maxillofacial surgeon to care for these patients as they may need extensive follow up and care with wound management. Let Dr. Benjamin Yagoubian care for your patient with advances medical conditions.