OsteoNecrosis from Medications
There are several significant articles about jaw bone death in patients taking certain drugs to reduce bone
resorption. The problem arises more frequently when the drugs are used for cancer treatment or the treatment of
metastasis to the bone and is more severe and frequent with the drugs that are given by injection rather than by
oral pill form.
The American Academy of Oral Medicine issued a position paper based on the review of some distinguished dental
scholars, many of whom I know and trust from personal contact with them in the decades I was active with the AAOM.
You may click on the link below to read their paper from the American Dental Association Journal.
Managing the care of patients with
bisphosphonate-associated osteonecrosis An American Academy of Oral Medicine position paper
US Pharmacology also posted a recent paper which is copied below, detailing the problem and which drugs are
Bisphosphonate-Associated Osteonecrosis of the Jaws: Impact on
Mea A. Weinberg, DMD, MSD, RPh
Clinical Associate Professor of Periodontics
New York University College of Dentistry
New York, New York
Vol. No: 31:05 Posted: 5/15/2006
US Pharm. 2006;5:62-69.
Osteonecrosis of the jaws (ONJ) is a serious oral condition that has been reported more frequently by dentists and
physicians in the last few years in cancer patients receiving chemotherapy, radiation, corticosteroids, or other
cancer treatment regimens concomitant with the use of bisphosphonates. These patients may also present with
comorbid conditions such as anemia, infections, and preexisting oral disease. Although the original published
reports of ONJ involved intravenous bisphosphonates, currently some cases with oral bisphosphonates are occurring.
Patients with ONJ usually present with oral signs and symptoms of painful, exposed, and necrotic bone, primarily of
the mandible and to a lesser extent the maxilla, after dental treatment. This article reviews the development of
osteonecrosis of the jaws, potential risk/precipitating factors, the pharmacology of bisphosphonates, and potential
preventive measures for this oral complication.
Introduced in the mid-1990s, bisphosphonates were prescribed as an alternative to hormone replacement therapies for
osteoporosis and to treat osteolytic tumors and possibly slow tumor development. In 1996, Fosamax (alendronate) was
the first bisphosphonate drug approved for osteoporosis (in which low bone mass and reduced bone strength lead to
fractures of the spine, wrist, and hip) in postmenopausal women (and later, in men); it was approved later on for
treatment of Paget's disease (in which normal bone is replaced with poor-quality bone).
The first studies on the actions of bisphosphonates to block calcification and bone destruction were published in
the 1960s. Didronel (etidronate) was first used over 20 years ago to treat patients with osteoporosis, but they
developed osteomalacia and clinical studies were stopped. In the United States, Didronel is not approved for
treatment of osteoporosis.
In 2005, the Food and Drug Administration approved Boniva (ibandronate sodium) as the first once-a-month tablet for
postmenopausal osteoporosis. Studies showed that it significantly reduced the risk of new vertebral fractures and
increased bone mineral density. 1 In January 2006, the FDA approved Boniva injection, the first injectable
medication for treatment of postmenopausal osteoporosis. Injectables were developed for individuals having
difficulty with oral bisphosphonate dosing requirements, including an inability to sit upright for 30 to 60 minutes
and/or to swallow a pill. Additionally, the injectable product is administered once every three months by a
physician so that monitoring is possible.
The FDA has notified the dental/medical community to the potential problem of osteonecrosis of the jaws (also
referred to as avascular or aseptic necrosis)--primarily of the mandible but also cases of the maxilla--occurring
in association with bisphosphonates. The first reported cases were associated with intravenous bisphosphonates used
to control hypercalcemia in metastatic bone disease2 but there are also anecdotal unpublished reports of oral
bisphosphonates causing ONJ.
Bisphosphonates are synthetic analogues of pyrophosphates, identified in the 1960s as substances present in blood
and urine that prevent the formation and aggregation of calcium phosphate crystal.3 Pyrophosphates are used in
tartar control toothpastes to inhibit the formation of tartar (calculus)--a hard calcium deposit on the tooth.
Bisphosphonates were developed because pyrophosphates were rapidly metabolized in the body. Figure 1 shows the
basic chemical structure of bisphosphonates.
Bisphosphonates are not metabolized; only about 3% of the drug is absorbed after an oral dose.4 Within 24 hours,
about half the absorbed dose is excreted in the urine and the rest is distributed to bone, from which it is slowly
Mechanism of Action
The function of bisphosphonates is still relatively unclear. Bisphosphonates bind and accumulate in bone and remain
there for months after therapy is discontinued. They are potent inhibitors of normal and abnormal osteoclastic bone
resorption that results in metastatic bone disease.5 They also reduce the local release of factors that stimulate
tumor growth (antitumor effect).6 Bisphosphonates are known to inhibit osteoclast attachment to bone, to induce
apoptosis (programmed cell death) of osteoclasts, and to inhibit differentiation of bone marrow precursor cells
into osteoclasts; they may also contribute to inhibition of bone resorption and increase in bone mass.3 Although
they block bone resorption, formation continues for about six to 12 months, after which formation stops. Thus, the
mineral is more densely packed so that the bone density will increase even though the bone volume does not.
Bisphosphonates also act on osteoblasts to inhibit osteoclast activity and osteoclastic function, an integral part
of the normal turnover and maintenance of bone. Osteoclastic function is so severely impaired that osteocytes are
not replaced and the capillary network in the bone is not maintained. This results in avascular bone necrosis. The
net effect is that physiologic bone deposition and remodeling are severely compromised in cancer patients receiving
bisphosphonates.7 The length of drug exposure may play a role in the development of ONJ.8 Patients taking
bisphosphonates for more than six months are at the highest risk for ONJ.9
Formulations and Indications
Table 1 lists the oral and parenteral bisphosphonate products currently available in the U.S. Bisphosphonates are
indicated for both the treatment and prevention of osteoporosis and in cancers metastatic to bone (skeletal
complications of malignancy).6 See Table 2.
Alendronate and risedronate are oral preparations used to treat osteoporosis. Zoledronic acid, pamidronate, and
ibandronate are the only intravenous bisphosphonates that are indicated for treatment of hypercalcemia of
malignancy, such as squamous cell carcinoma of the head and neck, breast cancer, prostate cancer, multiple myeloma,
and renal cancer. The incidence of hypercalcemia in cancer patients is about 20% to 30%; the prognosis is very
poor, and many patients die. The first-generation oral bisphosphonates, such as alendronate and risedronate, are
not useful in the treatment of hypercalcemia of malignancy because they are not as potent as the second- and
third-generation intravenous drugs. Intravenous bisphosphonates are also used with standard antineoplastic therapy
in the treatment of breast, lung, and prostate cancer metastatic to bone to prevent bone complications and in
multiple myeloma by interfering with bone marrow activities (through inhibition of osteoclastic activity).
Risk Factors for Osteonecrosis of the Jaws
Documented risk factors for osteonecrosis of the jaws are listed in Table 3. As mentioned earlier, it is unknown if
dental extraction/surgery is a cause of ONJ or just a precipitating or exacerbating factor that hastens bone
necrosis. Invasive dental procedures that may precipitate osteonecrosis include tooth extractions, placement of
dental implants, and periodontal surgery. Even pressure from dentures, which results in local mucosal infections
beneath the denture, may be followed by bone involvement.
Adverse Events: Reported Cases of Osteonecrosis of the Jaws
Wang et al. reported the first cases of ONJ associated with bisphosphonate therapy in cancer patients.2 These
cancer patients were undergoing many treatments with chemotherapy drugs, corticosteroids, and bisphosphonates.
Marx10 reported on a group of 36 patients receiving intravenously either pamidronate or zoledronate for the
management of bone disease associated with metastatic cancer, multiple myeloma, and osteoporosis, who had developed
avascular necrosis of the jaws. In the majority of cases, the necrosis developed after tooth extractions
(nonhealing extraction sites), and in about 30% of cases it occurred spontaneously.
Instances of osteonecrosis of the jaw bones have been reported for both injectable and oral bisphosphonates and may
be a class effect, according to the FDA, as exhibited by alendronate, zoledronic acid, and pamidronate cases. In a
2005 report, Marx et al.11 studied 119 cases of bisphosphonate-associated bone exposure in patients taking Aredia
(26%), Zometa (40.3%) and Fosamax (3%). The mean time for bone to be exposed in the oral cavity with accompanied
symptoms was 14.3 months. Precipitating events that caused the bone exposure were as follows: 37.8% tooth
extractions, 28.6% advanced periodontal disease, 25.2% spontaneous, 11.2% periodontal surgery, 3.4% placement of
dental implants, and 0.8% root canal surgery.11
Clinical Features of Osteonecrosis of the Jaws
The exact mechanism underlying this reaction is unknown; however, it has been postulated that bisphosphonates
inhibit new vessel formation in the bone, which is associated with absent or delayed hard (alveolar) and soft
tissue healing, usually after dental extractions.12,13 The oral lesions seen in ONJ appear similar to those of
radiation-induced osteonecrosis.13,14 Clinically, there is oral ulceration with exposed underlying necrotic
("dead") bone (Figures 2 and 3 ). This oral condition causes chronic pain and severe, irreversible dysfunction and
disfigurement of the jaw. Other symptoms include soft tissue swelling, infection, and mobility of teeth.
Patients may remain asymptomatic for many weeks or months, and ONJ may be recognized only by the presence of
exposed "painful" bone in the mouth. These lesions most likely become symptomatic when the necrotic sites become
secondarily infected or if there is trauma to the soft tissue.
Although dental surgery or extractions have been identified as precipitants in many of these cases, as ONJ
developed after tooth extraction, there is evidence suggesting that the jaw (alveolar) bone can be involved before
and independent of dental procedures.15 The condition can develop spontaneously.
Treatment management involves educating the dentist (periodontist, oral surgeon, prosthodontist), pharmacist,
physician , and patient about ONJ and preventive measures that need to be taken to avoid these oral complications.
The American Academy of Oral Medicine published a position paper addressing the prevention of bisphosphonate
-associated osteonecrosis and the dental care management of patients with cancer and/or osteoporosis who are taking
bisphosphonates.12 In 2005, The American Academy of Periodontology (AAP) published a statement on bisphosphonates,
making periodontists aware of the need to determine if patients are currently taking intravenous bisphosphonates or
if any patients will be treated with these drugs. The AAP stresses the importance of identifying ONJ and other oral
complications of cancer and cancer therapy.
The FDA and drug companies have published statements for dental health professionals regarding the development of
ONJ in patients being treated for cancer with intravenous bisphosphonates. In late 2004, for example, Novartis had
implemented changes to Zometa and Aredia product labels to include precautions on osteonecrosis of the jaws. The
precaution states that a dental exam and preventive dentistry should be considered prior to treatment with
bisphosphonates in patients with concomitant risk factors such as cancer, chemotherapy, corticosteroids, and poor
oral hygiene. In February 2005, the FDA released a statement that ONJ is a risk of all bisphosphonates, not just
the IV formulations.
Prior to starting on bisphosphonate therapy, patients should be counseled regarding the possible occurrence of
ONJ.16 If possible, invasive dental procedures should be avoided while patients are taking the medications. It is
recommended that dentists perform a thorough soft tissue and dental examination before a patient starts using
bisphosphonate drugs. If bisphosphonate therapy can be briefly delayed without the risk of skeletal-related
complications, dental procedures should be performed on the patient who requires root canal therapy or tooth
extraction, denture adjustment, periodontal surgery, or placement of dental implants.17 Avoiding tooth extractions
while patients are taking bisphosphonates should minimize the incidence of ONJ.18 Once bisphosphonate therapy has
begun, the dentist should monitor the patient's oral health on a regular basis. Early detection is the key.
The pharmacist should counsel the patient taking a bisphosphonate on self-care oral hygiene. Some recommendations
include using a soft-bristled toothbrush, replacing the toothbrush frequently to maintain its shape and
effectiveness, and avoiding alcoholic over-the-counter mouthrinses since the alcohol will "dry" oral tissues.
Dental consultation before initiating bisphosphonate therapy is essential. Dental health and maintenance of oral
tissues are extremely important for cancer patients taking bisphosphonates. Pharmacists and dentists should report
suspected cases of ONJ to the FDA's MedWatch Adverse Event Reporting Program online at
www.fda.gov/medwatch/report.htm or by phone at 1-800-FDA-1088.
Mouthrinses, systemic antibiotics, hyperbaric oxygen, and surgical debridement have been tried as treatments for
ONJ, but no treatment has been proven effective. Marx et al. 11 found that a combination of antibiotics and 0.12%
chlorhexidine mouthrinse was about 90% effective in controlling pain in patients with painful exposed bone.
Discontinuing the bisphosphonate is not recommended once necrosis of the jaws has occurred.19 Focus should be
placed on prevention--the patient should have regular dental examinations and any invasive dental treatment done
before bisphosphonate therapy begins.
Individuals using oral or intravenous bisphosphonates have contact with their pharmacist. Some may report to the
pharmacist that they have oral pain or bleeding from inside their mouth. After consulting with such patients about
their medications and dental visits, the pharmacist should refer the patient to the dentist and/or physician.
The pharmacist, dentist, and physician all play a pivotal role in the patient's chemotherapy regimen. The
pharmacist and dentist are in the best positions to educate the patient about the potential adverse events that can
occur once starting bisphosphonates and of the necessary preventive measures. Complete prevention of ONJ is not
currently possible.11 Therefore, the patient must maintain excellent oral hygiene to reduce the risk of dental and
periodontal infections. Patients should be advised to have routine dental examinations before and during
cancer/bisphosphonate treatment and to report any oral symptoms to their dentists and physicians promptly.
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2. Wang J, Goodger NM, Pogrel MA. Osteonecrosis of the jaws associated with chemotherapy. J Oral Maxillofac Surg
3. Fleisch H. Bisphosphonates--history and experimental basis. Bone 1987;8:Suppl 1:S23-28.
4. Fleish H. Bisphosphonates: pharmacology and use in the treatment of tumour-induced hypercalcaemic and metastatic
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5. Licata AA. Discovery, clinical development, and therapeutic uses of bisphosphonates. Ann Pharmacother
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maxillary bone: an emerging oral complication of supportive cancer therapy. Cancer 2005;104:83-93.
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Strategies for prevention and early recognition. J Am Dent Assoc 2005;136:1675-1681.
15. Purcell PM, Boyd IW. Bisphosphonates and osteonecrosis of the jaw. Med J Aust 2005;182:417-418.
16. Zarychanski R, Elphee E, Walton P, Johnston J. Osteonecrosis of the jaw associated with pamidronate therapy. Am
J Hematol 2006;81:73-75.
17. Katz H. Endodontic implications of bisphosphonate-associated osteonecrosis of the jaws: a report of three
cases. J Endod 2005;31(11):831-834.
18. Gibbs SDJ, O'Grady J, Seymour JF, Prince HM. Bisphosphonate-induced osteonecrosis of the jaw requires early
detection and intervention. Med J Aust 2005;183(10):549-550.
19. Lenz JH, Steiner-Krammer B, Schmidt W, et al. Does avascular necrosis of the jaws in cancer patients only occur
following treatment with bisphosphonates? J Craniomaxillofac Surg 2005;33(6):395-403.
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