Osteonecrosis of the jaw (ONJ) has no unanimously accepted definition or etiology but is generally held to be an oral lesion involving bare mandibular or maxillary bone.
ONJ may occur spontaneously or after dental extraction Osteonecrosis of the jaw (ONJ) Postextraction problems are a subset of dental emergencies that require immediate treatment. These problems include Swelling and pain Postextraction alveolitis Osteomyelitis Osteonecrosis of the jaw read more 
or trauma, high-dose IV bisphosphonate therapy Preserving bone mass Osteoporosis is a progressive metabolic bone disease that decreases bone mineral density (bone mass per unit volume), with deterioration of bone structure. Skeletal weakness leads to fractures... read more 
, or high-dose denosumab 120 mg subcutaneously once/month (eg, for cancer treatment). ONJ may be a refractory osteomyelitis rather than true osteonecrosis, particularly when developing after bisphosphonate use.
There is no evidence that routine use of oral bisphosphonates for treatment or prevention of osteoporosis increases risk of ONJ. Currently, otherwise appropriate bisphosphonate use should not be discouraged. However, it seems reasonable to do any necessary oral surgery before beginning IV bisphosphonate therapy and to encourage good oral hygiene and regular dental care while patients are taking bisphosphonates (1 General references Osteonecrosis of the jaw is an oral lesion involving bare mandibular or maxillary bone. It may cause pain or may be asymptomatic. Diagnosis is by the presence of exposed bone for at least 8... read more , 2 General references Osteonecrosis of the jaw is an oral lesion involving bare mandibular or maxillary bone. It may cause pain or may be asymptomatic. Diagnosis is by the presence of exposed bone for at least 8... read more ).
General references
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1. Hellstein JW, Adler RA, Edwards B, et al: Managing the care of patients receiving antiresorptive therapy for prevention and treatment of osteoporosis: Executive summary of recommendations from the American Dental Association Council on Scientific Affairs. J Am Dent Assoc 142(11):1243−1251, 2011. doi: 10.14219/jada.archive.2011.0108
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2. Khan A, Morrison A, Cheung A, et al: Osteonecrosis of the jaw (ONJ): Diagnosis and management in 2015. Osteoporos Int 27(3):853–859, 2016. doi: 10.1007/s00198-015-3335-3
Symptoms and Signs of ONJ
Osteonecrosis of the jaw may be asymptomatic for long periods. Symptoms tend to develop along with signs, although pain may precede signs. In later stages, ONJ usually manifests with pain and purulent discharge from exposed bone in the mandible or, much less often, the maxilla. The teeth and gingiva may be involved. Intraoral or extraoral fistulas may develop.
Diagnosis of ONJ
Treatment of ONJ
Once established, osteonecrosis of the jaw is challenging to treat and should be managed by an oral surgeon with experience treating ONJ. Treatment of ONJ typically involves limited debridement, antibiotics, and antibacterial oral rinses (eg, chlorhexidine; 1 Treatment reference Osteonecrosis of the jaw is an oral lesion involving bare mandibular or maxillary bone. It may cause pain or may be asymptomatic. Diagnosis is by the presence of exposed bone for at least 8... read more ).
Surgical resection of the affected area may worsen the condition and should not be the initial treatment.
Treatment reference
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1. Hellstein JW, Adler RA, Edwards B, et al: Managing the care of patients receiving antiresorptive therapy for prevention and treatment of osteoporosis: Executive summary of recommendations from the American Dental Association Council on Scientific Affairs. J Am Dent Assoc 142(11):1243−1251, 2011. doi: 10.14219/jada.archive.2011.0108
