Screw Loosening
A prosthetic complication in which the abutment or prosthetic retaining screw loses its preload torque, causing the restoration to become mobile or detached.
Full Definition
Screw loosening is one of the most frequently reported prosthetic complications in implant dentistry, arising when the clamping force (preload) generated during screw tightening is reduced over time by micromovements, cyclic loading, and settling of the prosthetic components. It must be distinguished from screw fracture, which is irreversible. Editors reviewing clinical complication tables should confirm that authors report screw loosening events per implant and per patient, as the denominators affect interpretation. Recommended tightening torque values (usually expressed in Ncm) are manufacturer-specific and should be cited with the appropriate reference. Screw loosening rates are a primary outcome measure in many implant RCTs.
Usage
Usage note: Report as a rate per implant, not per patient only, to align with systematic review reporting standards (e.g., ITI consensus).
In Context
- "Screw loosening was the most common prosthetic complication, recorded in 12 of 87 implants over the five-year follow-up." — Retrospective cohort study results
- "The manuscript conflates screw loosening with screw fracture in Table 2; these are distinct complications and should be reported separately." — Editorial review comment