A patient is missing tooth #7, and the space between #6 and #8 is inadequate on the panoramic radiograph for a single implant. What must be corrected?

Correct answer: D. The mesiodistal space must be increased orthodontically

• A. Labiolingual root position affects the buccolingual position of the crown, not the mesiodistal width of the edentulous site.
• B. Occlusogingival (vertical) space governs restorative material selection and abutment height, but the deficiency described here is horizontal.
• C. Angling an implant into inadequate space places threads too close to the adjacent roots, risking root damage, bone loss, and papilla loss.
• D. CORRECT. For a single implant, minimum MESIODISTAL requirements are approximately 1.5–2 mm between the implant and each adjacent natural root, meaning a narrow-diameter (about 3.0–3.5 mm) implant requires roughly 6–7 mm of mesiodistal space. When the space is deficient, orthodontic movement of the adjacent teeth to open the space is the correct pre-prosthetic step. Insufficient space compromises the interproximal bone, the papilla, and the emergence profile.

Note: Spacing rules: 1.5–2 mm implant-to-tooth, 3 mm implant-to-implant. These distances protect the interproximal crestal bone that supports the papilla.