Surface analyses were performed in 4 studies. In the first study, Yang et al investigated zirconia with 4% CeO₂ and zirconia with 3% Y₂O₃ coatings, which were deposited on titanium and CoCrMo implants using the plasma spraying technique. Adhesive, morphologic, and structural properties of the plasma-sprayed coatings were evaluated. The average surface roughness of zirconia with 3% Y₂O₃ and of zirconia with 4% CeO₂ was correlated with the starting powder size and substrates. The size of zirconia with 3% Y₂O₃ powders was 40–100 µm, and the size of zirconia with 4% CeO₂ powders was 10–20 nm. No significant difference was observed between the hardness of all coatings and substrates. The adhesive strength of zirconia with 4% CeO₂ coating to titanium and CoCrMo substrates was higher than 68 MPa and significantly greater than that of zirconia with 3% Y₂O₃ coatings (32.3 MPa for titanium and 24.7 MPa for CoCrMo).

In the other study, machined zirconia, sandblasted zirconia, and SLA zirconia surfaces were evaluated. The surface roughness of zirconia was increased by airborne particle abrasion and additionally by acid-etching. Cell proliferation revealed statistically significant greater values at 3 days for surface-treated zirconia as compared with machined zirconia. However, no differences were observed between the zirconia groups and SLA titanium at 6 and 12 days.

In another study, Gahlert et al examined zirconia implants with a machined or a sandblasted surface and compared them with SLA titanium implants. Surface analyses revealed that the highest surface roughness was measured for the SLA titanium implant, followed by the sandblasted zirconia implant and the machined zirconia implant. In the last study conducted by Stübinger et al,38 the influence of erbium-doped yttrium aluminium garnet (Er∶YAG), carbon dioxide (CO₂), and diode laser irradiation on surface properties of polished zirconia implants was evaluated. SEM analyses demonstrated that diode and Er∶YAG lasers did not cause any visible surface alterations. However, the CO₂ laser produced distinct surface alterations to zirconia.