Effect of internal connection parameters on the fatigue limit of narrow-diameter implants – a finite element study

OBJECTIVE: To evaluate the influence of internal connection parameters on the fatigue limit of narrow-diameter dental implants using finite element analysis (FEA). METHODS: A narrow-diameter dental implant (3.0 mm, Morse taper connection) and its corresponding abutment and screw were scanned using micro-computed tomography (micro-CT). High-resolution 3D models were reconstructed (Simpleware, Synopsis), and six geometric parameters defining the internal connection were extracted. A reference 3D assembly was built in SolidWorks, and systematic dimensional variations (±20%) of the six design parameters were introduced based on a Taguchi orthogonal array (DOE++, Reliasoft), resulting in 27 modified assemblies. Static FEA was performed in ABAQUS according to ISO 14,801:2016 geometry. Fatigue performance was estimated using Fe-safe software, and sensitivity analyses were conducted to identify the most influential parameters on the predicted fatigue limit. RESULTS: The reference model presented a fatigue limit of 193 N. Dimensional optimization based on FEA improved the fatigue limit up to 295 N, representing a 52.3% increase compared to the original design, with the cervical opening diameter (CID) showing a significant effect on fatigue performance. CONCLUSIONS: Systematic variation of internal connection geometry significantly affected the fatigue resistance of narrow-diameter implants. Identifying critical parameters enables the development of more durable and reliable implant-abutment assemblies, maximizing the treatment success in anatomically compromised sites. CLINICAL SIGNIFICANCE: Optimizing the internal geometry of narrow-diameter implants can improve load distribution, minimize mechanical complications, and increase the longevity of implant-supported rehabilitations in areas with reduced bone volume.