Which factor is MOST commonly associated with dental implant failure?

Correct answer: D. Smoking

• A. Osteopenia and osteoporosis have not been shown to be strong independent predictors of implant failure; bone quality at the site matters more than a systemic DEXA score.
• B. Controlled hypertension is not a risk factor for implant failure.
• C. Osteopetrosis (dense, avascular, poorly remodeling bone) is a genuine contraindication because of impaired healing and osteomyelitis risk — but it is a RARE disease and therefore not the most common cause of failure.
• D. CORRECT. SMOKING is the most prevalent and best-documented modifiable risk factor for implant failure, roughly doubling failure rates and markedly increasing peri-implantitis and marginal bone loss. Nicotine causes vasoconstriction and impairs neutrophil function, oxygen delivery, and osteoblast activity. It is also common enough in the population to account for far more failures than any rare bone disorder.

Note: ⚠️ NOTE: the recall marked osteopetrosis. Read the stem wording carefully — 'most critical' contraindication could arguably be osteopetrosis, but 'most COMMON cause of failure' is unambiguously smoking. Worth clarifying with the group.