Approximately how long after implant placement does organised COLLAGEN formation begin in the peri-implant wound?

Correct answer: D. Around 4-7 days

• A. Twelve weeks corresponds to the conventional loading interval for a mandibular implant, by which time substantial lamellar bone remodelling has occurred.
• B. At 48 hours the wound is still in the inflammatory phase — clot, neutrophils and early macrophages. Fibroblast recruitment has barely begun and there is no meaningful collagen matrix yet.
• C. By 4 weeks, healing is well past the onset of collagen deposition — woven bone has formed and remodelling is under way. This is far too late to mark the BEGINNING of collagen formation.
• D. CORRECT. Peri-implant healing follows the standard wound healing cascade. The first 1-3 days are the INFLAMMATORY phase, with clot formation, platelet degranulation and neutrophil then macrophage infiltration. The PROLIFERATIVE phase begins around day 3-5, and it is here that fibroblasts arrive and begin depositing COLLAGEN into the provisional fibrin matrix, with the collagenous granulation tissue well established by roughly the end of the first week. Woven bone follows from about week 1-2, and the slow REMODELLING to lamellar bone occupies months.

Note: Osseointegration timeline in summary: clot and inflammation (days 0-3), granulation tissue and angiogenesis with collagen deposition (days 3-7), woven bone formation (weeks 1-6), replacement by lamellar bone and remodelling (months 3-12). Conventional loading protocols of roughly 3 months in the mandible and 4-6 months in the maxilla derive from this sequence.