Osseointegration of Zirconia Dental Implants: A Review of Preclinical Data

Background: Due to its advantageous physical, biological, and esthetic properties as well as its resistance to corrosion, zirconia as a biomaterial to replace missing tooth roots has been the focus of great interest and may become a reliable alternative to titanium implants. Aim: To present and discuss the preclinical data available on osseointegration of zirconia implants placed in the jawbone. Results: A great number of preclinical studies on zirconia implants with histologic and histomorphometric data are available. Zirconia implants were tested with different implant dimensions and designs, different surface treatments (e.g. machined, sandblasted, acid-etched, alkaline-etched, fusion-sputtered, selective infiltration-etched, powder injection molding, laser-treated, plasma-treated, microgrooved), in different species (i.e., rabbit, monkey, sheep, miniature pig, rat, dog) and different anatomical locations (i.e. tibia, femur, pelvis, maxilla, mandible), under different loading conditions, and with different observation periods (i.e. 1-56 weeks). Taken together, the boneto- implant (BIC) values reported in the literature for zirconia implants placed in the jawbone range from 18% to 89% with many values in the order of 50%-75%. All in all, most preclinical studies and reviews concluded that the BIC values did not reveal statistically significant differences between zirconia and titanium implants. Furthermore, most studies and most reviews come to the conclusion that modified zirconia surfaces have higher BIC values than machined ones. Conclusions: Most preclinical studies and reviews conclude that zirconia and titanium implants have similar BIC values. Nevertheless, the survival and success rates of zirconia implants documented in clinical studies are dependent on the implant type/system and somewhat inferior to those of titanium implants. More solid, long-term clinical data on zirconia implants are needed and differences between implant systems and surgical procedures need to be evaluated. Keywords: Zirconia, dental implant, osseointegration, bone-to-implant contact