Evaluation of Artificial Aging Effects on Surface Roughness and Atomic Force Microscopy Measurements of Glazed and Polished Zirconia

Context and Aims: This study seeks to evaluate the effects of artificial aging on the surface microtopography of zirconia using atomic force microscopy, comparing glazed and polished finishes across various zirconia types with differing phase compositions. Subjects and Methods: Disc-shaped specimens made of 4 zirconia types were prepared in a standardized fashion: Control (3 mol% yttria-stabilized tetragonal zirconia polycrystals), Prime (multiphase), super translucent multi-layered (STML) (65% cubic phase), and Ultra translucent multi-layered (UTML) (75% cubic phase). Specimens were treated by surface finishing (glazed or polished), and artificial aging in an autoclave (134°C, 2 atm, 12 h) followed. The surface roughness parameters were measured Ra (arithmetic average roughness), Rq (root mean square roughness), Rz (average peak-to-valley height), and Rmax (maximum profile height) before and after the aging process. Results: Surface roughness was greatly impacted by artificial aging, with patterns depending on the material and surface. In the Prime group, high-finish specimens showed a statistically significant increase in surface roughness (mean difference = +13.70 nm, P < 0.001). Glazed specimens had a slight, nonsignificant reduction in Ra (−0.384 nm, P = 0.754). For the STML group, both glazed (−6.19 nm, P = 0.015) and polished (−7.58 nm, P = 0.011) surfaces exhibited reductions in roughness after aging. The UTML group showed the most significant changes, with both glazed (−10.42 nm, P < 0.001) and polished (−10.04 nm, P < 0.001) surfaces demonstrating significant decreases in Ra values. Conclusions: The greater topographical stability associated with high-cubic-phase zirconia and polished surface conditions under hydrothermal conditions justifies their preferential application for long-term restoration.