Influence of Milling Tool and Prosthetic Materials on Roughness of the Dental CAD CAM Prostheses in End Milling Mode

Abstract

Dental prostheses are machined by computer-aided design and manufacturing (CAD/CAM) tools. The integrity of the surface obtained, which must be suitable to meet expected clinical requirements is influenced by the milling parameters programmed. The integrity of the occlusal prosthesis surface obtained by the end milling mode, that is milling with a diamond rotary cutting tip, plays a major role in the clinical requirements desired. This study aims to investigate the impact of the tool-biomaterial couple in the CAD/CAM end milling mode on surface integrity (through roughness). Two CAD/CAM tools and four CAD/CAM biomaterials, both combined to four feed rates are tested. The surface roughness (Ra, Rt, Rz, Sa, Sq, and Sz) is observed for each couple. Finally, pairwise comparisons (Kruskal-Wallis test) of tool-biomaterial couples are performed. The results indicate that all the machined surfaces reveal isotropic surface topology. The roughness depends on the hardness of the biomaterial and not on the feed rate. The statistical tests reveal a significant difference in roughness depending on the tool used. To conclude, when milling the functional occlusal shape, biomaterial hardness and the tool used are key factors for achieving a given roughness consistent with clinical requirements.