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Medicines that strengthen bone in cancer, such as zoledronic acid and denosumab, can rarely cause a patch of jawbone to break down, usually after a tooth is taken out. Before you start, see a dentist so any problem teeth can be treated first, keep your mouth very clean, and tell your dentist about the medicine. Report any jaw pain, loose teeth or exposed bone in the mouth.
MRONJ is exposed bone, or bone that can be probed through a fistula, in the jaw for more than 8 weeks in someone who has had a bone-modifying agent (BMA) or angiogenic inhibitor, with no radiotherapy or metastasis to the jaw (MASCC/ISOO/ASCO 2019). In cancer the doses are much higher than in osteoporosis (denosumab 120 mg monthly against 60 mg every 6 months), so the risk is greater: the Korean 2025 statement cites an incidence with zoledronate of 1.6 to 4 per cent in the first 2 years, rising after that, and finds that pretreatment dental care cut MRONJ by 77.3 per cent in one meta-analysis of people on high-dose bisphosphonates.
MASCC/ISOO/ASCO recommend a comprehensive dental assessment when a BMA is started, discussion of modifiable risk factors, and avoiding elective dentoalveolar surgery during treatment; whether to stop the BMA before necessary surgery is uncertain. The Korean statement makes dental evaluation mandatory before high-dose therapy for cancer, ideally before it begins, with extraction of teeth that cannot be saved, treatment of gum and root infections, adjustment of ill-fitting dentures and education on oral hygiene and warning signs. NICE NG101 asks that the risk of jaw osteonecrosis be discussed before adjuvant bisphosphonates in breast cancer. Established MRONJ is staged by an experienced clinician and treated conservatively first (MASCC/ISOO/ASCO), whereas the Korean statement favours earlier surgery.
Why: Most jaw osteonecrosis follows a tooth extraction or an infection; dealing with problem teeth first lowers that risk.
“In patients who initiate a BMA, preventive care includes comprehensive dental assessments, discussion of modifiable risk factors, and avoidance of elective dentoalveolar surgery (ie, surgery that involves the teeth or contiguous alveolar bone) during BMA treatment.”
Why: The doses used in cancer carry a far higher risk than those used for osteoporosis.
“For patients scheduled to receive high-dose antiresorptives for oncologic indications, this dental evaluation is considered mandatory and should be completed ideally before therapy begins.”
Why: Each of these is a way bacteria or pressure can reach the bone and start osteonecrosis.
“Extraction of non-restorable teeth or teeth with a poor prognosis”
Why: Smoking, poor oral hygiene, steroids and other drugs add to the risk, and some can be changed.
“Discuss the benefits and risks of bisphosphonate treatment with women, particularly the risk of osteonecrosis of the jaw, atypical femoral fractures and osteonecrosis of the external auditory canal.”
Why: Early signs found quickly are easier to treat, and the dentist can plan care around the medicine.
“Patient education on the importance of maintaining excellent oral hygiene and the signs and symptoms of MRONJ”
Why: Surgery on the jaw is the most common trigger while the medicine is in use.
“In patients who initiate a BMA, preventive care includes comprehensive dental assessments, discussion of modifiable risk factors, and avoidance of elective dentoalveolar surgery (ie, surgery that involves the teeth or contiguous alveolar bone) during BMA treatment.”
Why: Pausing may help the jaw heal but may raise the risk of fractures or bone problems from the cancer.
“It remains uncertain whether BMAs should be discontinued before dentoalveolar surgery.”
Why: Conservative care, such as antimicrobial mouth rinses, comes first; surgery is for cases that do not settle.
“Staging of MRONJ should be performed by a clinician with experience in the management of MRONJ. Conservative measures comprise the initial approach to MRONJ treatment.”
How care is usually carried out, read from the guidelines and standards cited. Your own team's protocol and their judgement come first; this page is for understanding it, not for doing it yourself.
The MASCC/ISOO/ASCO guideline (2019) is the only oncology-specific international guideline and was read only as an abstract: dental assessment when a bone-modifying agent starts, attention to modifiable risk factors, no elective dentoalveolar surgery during treatment, uncertainty about pausing the drug before necessary surgery, staging by an experienced clinician and conservative treatment first. The Korean 2025 position statement, read in full, agrees on prevention and goes further: it makes the dental check mandatory before high-dose cancer treatment, sets drug-specific pauses before dental surgery, and favours early surgery for established MRONJ. It reports that the AAOMS 2022 position paper deliberately removed fixed drug holidays for lack of evidence. On pausing and on surgery, the sources disagree, and the oncology guideline leaves it open.
MASCC, ISOO and ASCO, Journal of Clinical Oncology 2019 · Five Korean societies, Endocrinology and Metabolism 2025 · NICE 2018
Where it differs: Sets pauses before invasive dental procedures: 2 months for oral bisphosphonates in long-term users, 6 to 12 months for intravenous zoledronate, and surgery 3 to 4 months after the last denosumab injection, with 6 to 8 weeks of healing afterwards; the denosumab timing is built around the 6-monthly osteoporosis dose.
Evidence: Expert consensus from literature review and three rounds of surveys; the statement itself calls drug holidays one of the most controversial issues and notes that AAOMS (2022) offered no fixed holidays. MASCC/ISOO/ASCO say it is uncertain whether to stop the drug at all.
Five Korean societies, Endocrinology and Metabolism 2025 · MASCC, ISOO and ASCO, Journal of Clinical Oncology 2019
Where it differs: Advocates early and active surgical treatment at all stages of MRONJ, where MASCC/ISOO/ASCO start with conservative measures.
Evidence: The Korean statement cites better long-term outcomes with surgery than with conservative care; MASCC/ISOO/ASCO's position rests on its 2019 systematic review, which found only 10 randomised trials among 132 publications.
Five Korean societies, Endocrinology and Metabolism 2025 · MASCC, ISOO and ASCO, Journal of Clinical Oncology 2019
| Recommendation | Grade, as printed | Source |
|---|---|---|
| Pretreatment dental evaluation and preventive care in cancer patients on high-dose bisphosphonates “One meta-analysis reported that pre-treatment dental evaluation and preventive care reduced MRONJ incidence by 77.3% in cancer patients receiving high-dose BPs” | meta-analysis cited by the Korean statement: 77.3 per cent fewer cases | Five Korean societies, Endocrinology and Metabolism 2025 |
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