What is the leading cause of LATE dental implant failure?

Correct answer: A. Peri-implantitis driven by bacterial plaque accumulation

• A. CORRECT. LATE (post-osseointegration) failure is overwhelmingly biological and plaque-driven. Bacterial biofilm at the implant–mucosa interface produces peri-implant mucositis, which progresses to PERI-IMPLANTITIS with progressive marginal bone loss. Implants are more vulnerable than teeth because the peri-implant connective tissue fibres run parallel to the fixture rather than inserting into it, and there is no periodontal ligament or its vascular supply — so the inflammatory front reaches bone faster.
• B. Osteopetrosis is a rare disorder of hypermineralised, poorly vascularised bone that does compromise healing, but it is far too uncommon to be a leading cause of failure in any population.
• C. Osteoporosis affects bone density but has NOT been shown to be an independent contraindication or a major cause of implant failure; osseointegration rates in osteoporotic patients are comparable when surgical protocol is adapted.
• D. Modern titanium fixtures are not subject to clinically significant galvanic failure; corrosion is not a recognised principal failure mode.

Note: ⚑ Read the stem carefully on this family of questions. EARLY failure (before loading) is dominated by surgical and host factors — overheating the bone, lack of primary stability, contamination, and SMOKING. LATE failure is dominated by peri-implantitis and occlusal overload. Smoking is the single most important modifiable RISK FACTOR across both phases, which is why it is such a persuasive distractor.