Optimised Magnetic Field-Assisted Finishing Improves Surface and Mechanical Performance of CAD/CAM Titanium Abutments

This study investigated how magnetic field-assisted finishing (MAF) parameters affect the surface and mechanical properties of CAD/CAM Ti-6Al-4V implant abutments, aiming to identify optimal clinical conditions.

CAD/CAM-fabricated Ti-6Al-4V discs were polished under different MAF conditions (1000, 1200, and 1500 rpm; 20, 40, and 60 minutes). Two controls were included: baseline polishing with #800 SiC paper and conventional polishing with #2000 SiC paper. A roughness threshold (Ra ≈ 0.2 μm), determined by 2-dimensional (2D) surface profilometry, was used for preliminary screening. Surface morphology, 3-dimensional (3D) roughness, composition, and hydrophilicity were analysed using scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive spectroscopy (EDS), and contact angle measurement. Mechanical properties were assessed by surface microhardness testing using a Vickers hardness tester and residual stress analysis using an X-ray diffractometer. Clinical benchmarking compared the 2D surface roughness and morphology of MAF-treated abutments with prefabricated abutments.

Polishing duration and speed significantly influenced 2D roughness (p < .05), with a notable interaction effect (p < .05). MAF at 1200 and 1500 rpm met the threshold and were further analysed. Compared with conventional polishing, MAF produced smoother, scratch-free surfaces without elemental contamination. MAF maintained hydrophilicity, increased compressive stress, and did not alter microhardness. Clinical benchmarking showed comparable 2D surface roughness and morphology of MAF-treated and prefabricated abutments.

MAF is a highly effective method for polishing CAD/CAM Ti-6Al-4V abutments, capable of simultaneously improving surface and mechanical properties. The optimal condition of 1200 rpm for 40 minutes provides a superior balance of a nanoscale finish, beneficial compressive residual stress, and processing efficiency, supporting its potential for clinical use.

MAF provides uniform polishing for complex CAD/CAM titanium abutments and introduces beneficial compressive stress. This standardised process yields high-quality surfaces that may promote peri-implant soft tissue integration and enhance long-term restoration stability.