Implant Spacing — ORE Part 1 MCQ
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Correct answer: D — 3 mm
The best answer is **A, 3 mm**. For adjacent implants, 3 mm is the conventional minimum horizontal spacing used to preserve the interimplant bone crest and permit predictable papilla formation. In a clinical study, papillae were absent at 2.0–2.5 mm spacing but present most often when implants were 3.0–4.0 mm apart. Therefore, 2 mm is too close, and 1 mm is not an appropriate routine planning distance; isolated modern implant-system reports of narrow spacing do not replace the conventional standard. A 5 mm or 7 mm gap is not a minimum and may compromise restorative emergence profile or create an excessively broad embrasure. This question concerns implant-to-implant spacing, distinct from the contact-point-to-bone-crest vertical distance, which also influences papilla fill.
Reference: Gastaldo JF, Cury PR, Sendyk WR. Effect of the vertical and horizontal distances between adjacent implants and between a tooth and an implant on the incidence of interproximal papilla. Journal of Periodontology. 2004;75(9):1242–1246. https://pubmed.ncbi.nlm.nih.gov/15515340/