Screw Preload as a Biomechanical Determinant of Implant Stability
In two-piece implant systems, mechanical stability is shaped by the interaction of connection geometry and screw mechanics; it cannot be inferred from the nominal insertion torque alone. A primary determinant is screw preload, because it establishes the clamping force across the implant–abutment interface and defines whether the assembly behaves as a unified load-bearing structure or as a joint prone to micromovement, microgap formation, and fatigue. Importantly, the relative weight of these factors is connection-specific: in internal hex designs, stability depends predominantly on maintaining adequate preload to control joint separation and micro-mobility, whereas in conical (Morse taper) connections the conical interface can contribute additional frictional locking and resistance to micromovement—provided the components are fully seated and sufficient preload (and therefore clamping force) is achieved. In clinical
