Mechanochemical effect-assisted ultrasonic grinding of functional microgrooves on zirconia denture surface

Abstract

Inspired by natural teeth, texturing groove-type microstructures on zirconia implant dentures is an efficient approach to enhance their tribological and antibacterial performances. However, the current surface texturing methods for zirconia ceramic dentures, primarily laser ablation or grinding, often induce severe surface damage due to their high hardness. In this study, a coating-assisted rotary ultrasonic grinding (CUG) process is proposed to fabricate microgrooves on zirconia ceramic. This method aims to improve surface quality by leveraging the local embrittlement caused by the mechanochemical effects of the coating and ultrasonic vibration. A series of surface texturing, grinding, and nanoindentation tests are conducted to evaluate the process performance and underlying mechanism of the CUG. The results demonstrate that compared to conventional grinding (CG), CUG can reduce the surface roughness of the microgrooves by an average of 73.4 % and decrease the cutting force by an average of 72.7 %. The process mechanism of CUG can be attributed to the synergistic effects between the surface coating and ultrasonic grinding, both causing local embrittlement of zirconia ceramics, increasing small local cracks, and reducing larger macro defects. Additionally, the effects of microgrooves on surface performance, including wettability, tribological behavior, and bacteria adhesion, are assessed. Compared to a smooth surface, the CUG textured surface exhibits excellent hydrophobic properties, the friction coefficient reduced by 50.6 %, and an increase in the bacteriostatic rate by 74.7 %.