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

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 (ZrO(2)) and lithium-disilicate glass ceramics (LDS). METHODS: Sixty ZrO(2) (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 (Al(2)O(3)) (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 ZrO(2) 0.67 ± 0.21 after treatment) and Group C the lowest (LDS 0.45 ± 0.13 and ZrO(2) 0.26 ± 0.07, after treatment). Compared with before treatment, the Ra were significantly different only in Group A both ZrO(2) and LDS after treatment (p < 0.05). Qualitative SEM images suggested the surface topography of the ZrO(2) 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 ZrO(2) not easier than LDS.