The PubMed search resulted in 108 articles. The total number of papers that met the inclusion criteria for this review was 37. Of these, 30 were laboratory studies, 3 were clinical studies, 2 were case reports, and 2 were review articles.

Most of the studies were conducted in vitro (1,2,11,18,20-45). Osseointegration and bone-implant contact (BIC) were investigated in 18 articles (2,18,20-35), surface analyses in 4 articles (1,36–38), removal torque testing (RTQ) in 4 studies (1, 39-41), mechanical strength in 4 articles (11,42-44), and stress analyses in 1 article (45). Three clinical studies involved clinical survival rate (46-48). Other published articles were case reports (49,50) and reviews (51,52).

References

1. Gahlert, M., Gudehus, T. Eichhorn, S. Steinhauser, E. Kniha, H. and Erhardt, W. Biomechanical and histomorphometric comparison between zirconia implants with varying surface textures and a titanium implant in the maxilla of miniature pigs. Clin Oral Implants Res. 2007. 18:662–668.
2. Depprich, R., Zipprich, H. Ommerborn, M. et al. et al Osseointegration of zirconia implants compared with titanium: an in vivo study. Head Face Med. 2008. 4:30.
3. Steinemann, S. G. Titanium—the material of choice?. Periodontol 2000. 1998. 17:7–21.
4. Sykaras, N., Iacopino, A. M. Marker, V. A. Triplett, R. G. and Woody, R. D. Implant materials, designs, and surface topographies: their effect on osseointegration. A literature review. Int J Oral Maxillofac Implants. 2000. 15:675–690.
5. Heydecke, G., Kohal, R. and Gläser, R. Optimal esthetics in singletooth replacement with the re-implant system: a case report. Int J Prosthodont. 1999. 12:184–189.
6. Stejskal, J. and Stejskal, V. D. The role of metals in autoimmunity and the link to neuroendocrinology. Neuroendocrinol Lett. 1999. 20:351–364.
7. Tschernitschek, H., Borchers, L. and Geurtsen, W. Nonalloyed titanium as a bioinert metal—a review. Quintessence Int. 2005. 36:523–530.
8. Valentine-Thon, E. and Schiwara, H. W. Validity of MELISA for metal sensitivity testing. Neuroendocrinol Lett. 2003. 24:57–64.
9. Yamauchi, R., Morita, A. and Tsuji, T. Pacemaker dermatitis from titanium. Contact Dermatitis. 2000. 42:52–53.
10. Kohal, R. J. and Klaus, G. A zirconia implant-crown system: a case report. Int J Periodontics Restorative Dent. 2004. 24:147–153.
11. Andreiotelli, M. and Kohal, R. J. Fracture strength of zirconia implants after artificial aging. Clin Implant Dent Relat Res. 2009. 11:158–166.
12. Sennerby, L., Dasmah, A. Larsson, B. and Iverhed, M. Bone tissue responses to surface-modified zirconia implants: a histomorphometric and removal torque study in the rabbit. Clin Implant Dent Relat Res. 2005. 7(suppl 1):S13–S20.
13. Piconi, C., Maccauro, G. Muratori, F. and Brach del Prever, E. Alumina and zirconia ceramics in joint replacements. J Appl Biomater Biomech. 2003. 1:19–32.
14. Piconi, C. and Maccauro, G. Zirconia as a ceramic biomaterial. Biomaterials. 1999. 20:1–25.
15. Ichikawa, Y., Akagawa, Y. Nikai, H. and Tsuru, H. Tissue compatibility and stability of a new zirconia ceramic in vivo. J Prosthet Dent. 1992. 68:322–326.
16. Warashina, H., Sakano, S. Kitamura, S. et al. et al Biological reaction to alumina, zirconia, titanium and polyethylene particles implanted onto murine calvaria. Biomaterials. 2003. 24:3655–3661.
17. Albrektsson, T., Branemark, P. I. Hansson, H. A. and Lindstrom, J. Osseointegrated titanium implants: requirements for ensuring a longlasting, direct bone-to-implant anchorage in man. Acta Orthop Scand. 1981. 52:155–170.
18. Langhoff, J. D., Voelter, K. Scharnweber, D. et al. et al Comparison of chemically and pharmaceutically modified titanium and zirconia implant surfaces in dentistry: a study in sheep. Int J Oral Maxillofac Surg. 2008. 37:1125–1132.
19. Puleo, D. A. and Thomas, M. V. Implant surfaces. Dent Clin North Am. 2006. 50:323–338.
20. Cranin, A. N., Schnitman, P. A. Rabkin, S. M. and Onesto, E. J. Alumina and zirconia coated vitallium oral endosteal implants in beagles. J Biomed Mater Res. 1975. 9:257–262.
21. Nordlund, A., Zetterqvist, L. and Odén, A. A comparative experimental investigation in monkeys between three different implant materials. Int J Oral Maxillofac Surg. 1989. 18:373–377.
22. Franchi, M., Bacchelli, B. Martini, D. et al. et al Early detachment of titanium particles from various different surfaces of endosseous dental implants. Biomaterials. 2004. 25:2239–2246.
23. Franchi, M., Orsini, E. Trire, A. et al. et al Osteogenesis and morphology of the peri-implant bone facing dental implants. Scientific World Journal. 2004. 4:1083–1095.
24. Franchi, M., Bacchelli, B. Giavaresi, G. et al. et al Influence of different implant surfaces on peri-implant osteogenesis: histomorphometric analysis in sheep. J Periodontol. 2007. 78:879–888.
25. Sollazzo, V., Pezzetti, F. Scarano, A. et al. et al Zirconium oxide coating improves implant osseointegration in vivo. Dent Mater. 2008. 24:357–361.
26. Bacchelli, B., Giavaresi, G. Franchi, M. et al. et al Influence of a zirconia sandblasting treated surface on peri-implant bone healing: an experimental study in sheep. Acta Biomater. 2009. 5:2246–2257.
27. Akagawa, Y., Ichikawa, Y. Nikai, H. and Tsuru, H. Interface histology of unloaded and early loaded partially stabilized zirconia endosseous implant in initial bone healing. J Prosthet Dent. 1993. 69:599–604.
28. Akagawa, Y., Hosokawa, R. Sato, Y. and Kamayama, K. Comparison between freestanding and tooth-connected partially stabilized zirconia implants after two years' function in monkeys: a clinical and histologic study. J Prosthet Dent. 1998. 80:551–558.
29. Dubruille, J. H., Viguier, E. Le Naour, G. Dubruille, M. T. Auriol, M. and Le Charpentier, Y. Evaluation of combinations of titanium, zirconia, and alumina implants with 2 bone fillers in the dog. Int J Oral Maxillofac Implants. 1999. 14:271–277.
30. Scarano, A., Di Carlo, F. Quaranta, M. and Piattelli, A. Bone response to zirconia ceramic implants: an experimental study in rabbits. J Oral Implantol. 2003. 29:8–12.
31. Schultze-Mosgau, S., Schliephake, H. Radespiel-Tröger, M. and Neukam, F. W. Osseointegration of endodontic endosseous cones: zirconium oxide vs titanium. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2000. 89:91–98.
32. Kohal, R. J., Weng, D. Bächle, M. and Strub, J. R. Loaded custom-made zirconia and titanium implants show similar osseointegration: an animal experiment. J Periodontol. 2004. 75:1262–1268.
33. Hoffmann, O., Angelov, N. Gallez, F. Jung, R. E. and Weber, F. E. The zirconia implant-bone interface: a preliminary histologic evaluation in rabbits. Int J Oral Maxillofac Implants. 2008. 23:691–695.
34. Depprich, R., Zipprich, H. Ommerborn, M. et al. et al Osseointegration of zirconia implants: an SEM observation of the bone-implant interface. Head Face Med. 2008. 4:25.
35. Depprich, R., Ommerborn, M. Zipprich, H. et al. et al Behavior of osteoblastic cells cultured on titanium and structured zirconia surfaces. Head Face Med. 2008. 4:29.
36. Yang, Y., Ong, J. L. and Tian, J. Deposition of highly adhesive ZrO(2) coating on Ti and CoCrMo implant materials using plasma spraying. Biomaterials. 2003. 24:619–627.
37. Bächle, M., Butz, F. Hübner, U. Bakalinis, E. and Kohal, R. J. Behavior of CAL72 osteoblast-like cells cultured on zirconia ceramics with different surface topographies. Clin Oral Implants Res. 2007. 18:53–59.
38. Stübinger, S., Homann, F. Etter, C. Miskiewicz, M. Wieland, M. and Sader, R. Effect of Er:YAG, CO(2) and diode laser irradiation on surface properties of zirconia endosseous dental implants. Lasers Surg Med. 2008. 40:223–228.
39. Sennerby, L., Dasmah, A. Larsson, B. and Iverhed, M. Bone tissue responses to surface-modified zirconia implants: a histomorphometric and removal torque study in the rabbit. Clin Implant Dent Relat Res. 2005. 7(suppl 1):S13–S20.
40. Alzubaydi, T. L., Alameer, S. S. Ismaeel, T. Alhijazi, A. Y. and Geetha, M. In vivo studies of the ceramic coated titanium alloy for enhanced osseointegration in dental applications. J Mater Sci Mater Med. 2009. 20(suppl 1):S35–S42.
41. Ferguson, S. J., Langhoff, J. D. Voelter, K. et al. et al Biomechanical comparison of different surface modifications for dental implants. Int J Oral Maxillofac Implants. 2008. 23:1037–1046.
42. Minamizato, T. Slip-cast zirconia dental roots with tunnels drilled by laser process. J Prosthet Dent. 1990. 63:677–684.
43. Kohal, R. J., Klaus, G. and Strub, J. R. Zirconia-implant-supported all-ceramic crowns withstand long-term load: a pilot investigation. Clin Oral Implants Res. 2006. 17:565–571.
44. Silva, N. R., Coelho, P. G. Fernandes, C. A. Navarro, J. M. Dias, R. A. and Thompson, V. P. Reliability of one-piece ceramic implant. J Biomed Mater Res B Appl Biomater. 2009. 88:419–426.
45. Kohal, R. J., Papavasiliou, G. Kamposiora, P. Tripodakis, A. and Strub, J. R. Three-dimensional computerized stress analysis of commercially pure titanium and yttrium-partially stabilized zirconia implants. Int J Prosthodont. 2002. 15:189–194.
46. Blaschke, C. and Volz, U. Soft and hard tissue response to zirconium dioxide dental implants—a clinical study in man. Neuroendocrinol Lett. 2006. 27(suppl 1):69–72.
47. Oliva, J., Oliva, X. and Oliva, J. D. One-year follow-up of first consecutive 100 zirconia dental implants in humans: a comparison of 2 different rough surfaces. Int J Oral Maxillofac Implants. 2007. 22:430–435.
48. Pirker, W. and Kocher, A. Immediate, non-submerged, root-analogue zirconia implant in single tooth replacement. Int J Oral Maxillofac Surg. 2008. 37:293–295.
49. Kohal, R. J. and Klaus, G. A zirconia implant-crown system: a case report. Int J Periodontics Restorative Dent. 2004. 24:147–153.
50. Oliva, J., Oliva, X. and Oliva, J. D. Ovoid zirconia implants: anatomic design for premolar replacement. Int J Periodontics Restorative Dent. 2008. 28:609–615.
51. Lacefield, W. R. Materials characteristics of uncoated/ceramic-coated implant materials. Adv Dent Res. 1999. 13:21–26.
52. Wenz, H. J., Bartsch, J. Wolfart, S. and Kern, M. Osseointegration and clinical success of zirconia dental implants: a systematic review. Int J Prosthodont. 2008. 21:27–36.