One study evaluated stress analysis. Kohal et al observed the stress distribution patterns of zirconia implants (ReImplant), which were found to have low, well distributed, and similar stress distribution compared with titanium implants. These patterns could be characterized as favorable or nondestructive. Stress values were found to be similar for both models for all regions.

Three clinical studies investigated zirconia implants. Blaschke et al reported that dental implants made from zirconia are a feasible alternative to titanium dental implants. In addition to excellent cosmetic results, zirconia implants allow a degree of osseointegration and soft tissue response that is superior to that of titanium dental implants. Oliva et al reported the first clinical evaluation of 100 zirconia implants (CeraRoot, Barcelona, Spain) with 2 different surface roughnesses in humans after 1 year of follow-up. Two implants failed after 15 days. These failed implants were placed in situations where sinus elevation was required. The overall success rate was reported as 98%. Given the sinus elevation requirement, future investigators may exclude patients with less than 5 mm residual bone. Pirker et al placed a zirconia implant to the maxillary first premolar region immediately and evaluated the clinical outcome of this implant. At 2-year follow-up, a stable implant and an unchanged peri-implant marginal bone level were observed. No bleeding was detected on probing.

Kohal et al presented the first clinical case report of a zirconia dental implant in the literature. A custom-made 2-piece zirconia implant was used to replace a left upper central incisor with zirconia abutment and a zirconia-based single crown. Furthermore, Oliva et al reported the first clinical case of an ovoid zirconia dental implant. An anatomically oriented ovoid zirconia implant (CeraRoot Type 14), which was specially designed to replace a missing premolar, was discussed.

On the basis of available peer-reviewed data, osseointegration of zirconia dental implants may be comparable with that of titanium implants. They were also found to have low, well distributed, and similar stress distribution when compared with titanium implants. Furthermore, zirconia particles used for surface modifications of titanium implants may have the potential to improve initial bone healing and resistance to removal of torque. The surface roughness of zirconia was found to be comparable with that of titanium implants. Although fabrication of surface modifications for zirconia is difficult, CO₂ lasers revealed distinct surface alterations to zirconia, and additional studies about this technique may help to improve surface roughness. Coated or surface-modified zirconia implants showed higher removal torque values than machined zirconia implants. To fulfill biomechanical requirements, restoring zirconia implants with high-strength ceramics or metal ceramics would be beneficial. Although a few short-term clinical reports are available and provide satisfactory results, controlled clinical trials with a follow-up of 5 years or longer should be performed to properly evaluate the clinical performance of zirconia implants and to recommend them for routine clinical use.