A patient has a full-arch maxillary SCREW-RETAINED implant prosthesis. Which is a necessary part of routine maintenance?

Correct answer: D. Periodic retightening of the prosthetic screws to the specified torque

• A. Full-arch implant prostheses require MORE maintenance than natural dentition, not less: professional recall every 3-6 months, radiographic monitoring of marginal bone, probing around implants, and assessment of the prosthesis for wear, fracture and screw integrity.
• B. The patient CANNOT remove a screw-retained fixed prosthesis. That describes an overdenture or a removable implant-supported prosthesis. The patient cleans beneath a fixed full-arch prosthesis with superfloss, interdental brushes and a water irrigator.
• C. Abutments are replaced only when damaged, worn or when the prosthetic design changes — never on a routine annual schedule.
• D. CORRECT. A screw-retained full-arch prosthesis is FIXED (patient cannot remove it) but RETRIEVABLE by the clinician. Its defining maintenance requirement is periodic removal at recall so that the fit surface and abutments can be cleaned, the soft tissues inspected and probed, and the screws re-torqued to the manufacturer's specification with a calibrated torque driver. SCREW LOOSENING is the single most common mechanical complication of implant prostheses, and settling of the screw joint after initial placement means the first re-torque is usually recommended within the first weeks.

Note: Screw-retained vs cement-retained is a recurring exam theme. SCREW-RETAINED: retrievable, no cement to be left subgingivally, needs adequate interocclusal space and correctly angled implants, screw access hole in the occlusal/lingual surface. CEMENT-RETAINED: better aesthetics and passive fit, but residual excess cement is a leading cause of peri-implantitis.