Sennerby et al observed bone tissue responses to machined and surface-modified zirconia implants. To achieve a porous surface, the zirconia implants were coated with 2 different slurries containing zirconia powder and a pore-former, which gave different surface structures. Noncoated zirconia implants were used as controls. In addition, titanium implants were used. The coated zirconia implants and the titanium implants showed higher RTQ than the machined zirconia implants.

Gahlert et al evaluated the RTQ values of machined zirconia implants, sandblasted zirconia implants, and SLA titanium implants. The machined zirconia implants showed statistically significant lower RTQ values than the other 2 implant types after 8 and 12 weeks, and the SLA titanium implant showed significantly higher RTQ values than the sandblasted zirconia surface at 8 weeks. The mean RTQ for machined zirconia implants was 25.9 N/cm, the mean RTQ for zirconia rough implants was 40.5 N/cm, and the mean RTQ for SLA titanium implants was 105.2 N/cm.

Alzubaydi et al evaluated the effects of ceramic coatings (hydroxyapatite and zirconia) on the bond strength between bone and implant, as well as the cell compatibility of screw-shaped titanium dental implants. Biomechanical testing was carried out at 2, 6, and 18 weeks healing time points. An increase in RTQ values was noted in the bone-implant interface with time, and the highest increment in bond strength was recorded for implants coated with 50% hydroxyapatite and 50% zirconia. The interface reaction of bone toward coated implants was faster than toward uncoated ones.

Ferguson et al compared the biomechanical properties of 6 types of implant surfaces and found the RTQ values of SLA titanium as 1884 N/mm, SLA and calcium phosphate (CaP)-coated titanium as 1683 N/mm, SLA and anodic plasma chemical surface-treated titanium as 919 N/mm, SLA and bisphosphonate-coated titanium as 1835 N/mm, SLA and collagen-coated titanium as 1593 N/mm, and SLA zirconia as 1005 N/mm. At 8 weeks, RTQ values of zirconia were significantly lower.