Surface roughness and characteristics of CAD/CAM zirconia and glass ceramics after combined treatment procedures

Abstract

Background The roughening of the inner surface of a fixed ceramic restoration is an important factor for the bonding process. The aim of this study is to investigate the effect of combined surface treatments (acid etching, air-abrasion and Er: YAG Laser) on surface roughness of CAD/CAM fabricated zirconia (ZrO2) and lithium-disilicate glass ceramics (LDS). Methods Sixty ZrO2 (Ceramill Zi) and LDS (IPS e.max CAD) specimens, (5 mm in width, 5 mm in length and 1.5 mm in height) were fabricated using CAD/CAM and sintered according to the manufacturer’s instructions. All specimens subjected to three surface treatment combinations; etching with 4% hydrofluoric acide (HF), airborne-particle abrasion with 110-μm alumina (Al2O3) (AP) and Er:YAG laser (Er:YAG) (Group A—HF + AP; Group B—Er:YAG + AP, and Group C—Er:YAG + HF). Perthometer was used to measure the surface roughness of the specimens before and after the tretments. Results Group A presented the highest Ra (LDS 0.81 ± 0.27 and ZrO2 0.67 ± 0.21 after treatment) and Group C the lowest (LDS 0.45 ± 0.13 and ZrO2 0.26 ± 0.07, after treatment). Compared with before treatment, the Ra were significantly different only in Group A both ZrO2 and LDS after treatment (p < 0.05). Qualitative SEM images suggested the surface topography of the ZrO2 was smoother than the LDS. Less surface changes were observed in the Er:YAG combined procedures than HF + AP. Conclusions HF + AP was significantly succesful in modifying the ceramic surface. Er:YAG did not sufficiently promote the surface topography, even if combined with any other treatments. Overall, surface tretments on ZrO2 not easier than LDS.

The Surface Roughness of Contemporary Indirect CAD/CAM Restorative Materials That Are Glazed and Chair-Side-Finished/Polished

“…Zirconia changes phases disruptively when heated. After cooling from high temperatures, the structure cracks due to significant strains induced by the volume shift brought on by the structure’s transition from tetragonal to monoclinic to cubic [ 46 , 47 ]. It has also been reported as utilizing a finishing and polishing procedure instead of glazing to create a more natural texture because glazing typically wears off over time [ 48 ].…”

Use of Ultra-Translucent Monolithic Zirconia as Esthetic Dental Restorative Material: A Narrative Review

“…However, it is important to realize that a material's hardness does not always indicate that it would cause greater abrasion on the opposing tooth's enamel surface [80]. Conversely, a number of tests revealed that in contrast to glass ceramics with a greater degree of surface roughness, translucent monolithic Zr has less wear effect on the opposing enamel because of its smooth polished surface [81]. The antagonist's natural dentition becomes more abrasive and has a rougher surface when the glass-ceramics microstructure disappears and reveals the crystalline phase.…”