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Fosamax (Alendronate) and Osteonecrosis of the Jaw: Risk Factors and Epinephrine Myths

Medication-Related Osteonecrosis of the Jaw (MRONJ)

MRONJ (formerly bisphosphonate-related ONJ/BRONJ) is exposed necrotic bone in the maxillofacial region persisting >8 weeks in a patient on antiresorptive/antiangiogenic therapy without prior radiation to the jaws.

Risk Stratification

Risk CategoryPatient ProfileIncidence
HighIV bisphosphonates (zoledronic acid) or denosumab for malignancy; >2 years0.5–2% (IV); up to 5–10% with dental surgery
ModerateOral bisphosphonates (alendronate/Fosamax) >3–4 years; or + corticosteroids0.01–0.1%
LowOral bisphosphonates <3 years; no other risk factors<0.01%

Additional Risk Factors

  • Concurrent corticosteroids, chemotherapy, antiangiogenics (bevacizumab)
  • Dental procedures: extractions, implants, periodontal surgery (traumatic)
  • Poor oral hygiene, periodontal disease, ill-fitting dentures
  • Diabetes, smoking, alcohol use, rheumatoid arthritis
  • Age >65

Epinephrine in Local Anesthesia: No Direct Causal Link

There is no evidence that epinephrine-containing local anesthetics (e.g., lidocaine 2% with 1:100,000 epinephrine) cause or precipitate MRONJ. Epinephrine causes transient vasoconstriction, but:

  • Studies show no increased MRONJ risk with epinephrine vs. plain anesthetic
  • Vasoconstriction is short-lived (30–60 min)
  • Adequate hemostasis from epinephrine may actually reduce surgical trauma

Clinical Recommendations (AAOMS 2022)

  1. Pre-treatment dental exam before starting antiresorptives; complete needed extractions/surgery
  2. Oral hygiene optimization during therapy
  3. Drug holiday? For oral bisphosphonates >4 years: consider 2-month holiday before/after invasive dental surgery (case-by-case; no proven benefit)
  4. Denosumab: Do NOT stop without alternative (rapid BMD loss, vertebral fracture risk)
  5. Atraumatic surgery: Primary closure, antibiotics (penicillin/amoxicillin), chlorhexidine rinses
  6. Monitor: Exposed bone, pain, infection, paresthesia

Signs Requiring Urgent Evaluation

  • Exposed bone/necrotic tissue in mouth >8 weeks
  • Pain, swelling, purulence, paresthesia
  • Loose teeth, non-healing extraction socket

Fosamax (oral alendronate) carries low absolute MRONJ risk. Epinephrine in dental anesthetic is not a risk factor. Preventive dental care and atraumatic surgery are key.

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