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Commercial zirconia implant systems CeraRoot (Oral Iceberg, Barcelona, Spain) Sigma (Incermed, Lausanne, Switzerland) White Sky (Bredent Medical, Senden, Germany) Z-systems (Z-systems, Konstanz, Germany) Zit-z (Ziterion, Uffenheim, Germany) Source: International Journal of Prosthodontics (January-February 2008, Vol. 21:1, pp. 27-36). |
Tooth-colored, biocompatible, and made of the hardest stuff next to diamonds, zirconia seems like a natural material for implants. So it's no surprise to hear that they're already being marketed in Europe and on their way to the U.S.
Oral Iceberg, a Spanish company, is hoping to get FDA approval for the CeraRoot all-zirconia implants this year, with four other companies lining up to compete. Nobel Biocare obtained FDA clearance in 2007 for its zirconia implant, but has not yet brought the product to market. Straumann has announced plans to bring a zirconia-titanium alloy to market this year. Experiments using zirconia implants suggest that they integrate into bone as well as titanium.
"CeraRoot implants are white [and] corrosion-free," wrote Xavi Oliva Ochoa, CEO of Oral Iceberg, in an e-mail to DrBicuspid.com. "Dental plaque is less attached to them; there are no subgingival prosthetic connections: this means better periodontal health."
Some patients dislike the idea of having metal in their mouths, and some allergies to titanium have been reported.
Kim Gowey, D.D.S., a Medford, WI, dentist and past president of the American Academy of Implant Dentistry can see the advantages to an all-zirconia implant. Even when you use a zirconia abutment on a titanium implant, the gray color of the titanium can show through. "And tissue likes zirconia really well." The gingiva is more likely to stay snug against the implant.
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This video, provided by Oral Iceberg, shows an upper central incisor being replaced with an all-zirconia implant. |
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So is zirconia going to replace titanium?
Maybe, maybe not, he says. Dr. Gowey remembers polycrystalline alumina implants, which came onto the market in the 1970s. "They were aesthetically nice and integrated, but over time they snapped off," he said. "The bone would reheal and you'd have to grind the thing out."
He worries that, over the long term, zirconia implants could end up failing in a similar way because zirconia is subject to hydrolysis; over time, it absorbs water, becoming prone to fracture.
Manufacturers use a glaze that repels water, but if you need to grind the implant to adjust it -- for example, if it's too close to the opposing teeth -- you'll remove some glaze. "The less grinding the better," agreed Dr. Ochoa.
Also, a one-piece implant can only work in one position, unlike a two-piece implant for which angled abutments are available. Oral Iceberg is working on other shapes for multiple positions, but they're not available yet.
While there hasn't been a lot of long-term research on zirconia implants, that data is on its way as well. A June 2008 review of the subject in Periodontology 2000 (Vol. 47:1, pp. 224-243) reported unpublished data from an ongoing study at the University of Freiburg in Germany. In that study, only 4 out of 119 zirconia implants had been lost a year after being placed, for a survival rate of 96.6%.
Likewise, a January-February 2008 review in the International Journal of Prosthodontics (Vol. 21:1, pp. 27-36) reported that studies in animals found that zirconia implants were comparable to or even better than titanium implants.
Still, both papers concluded that the data is too preliminary to recommend zirconia just yet. "Prospective clinical investigations are needed," wrote the Periodontology 2000 authors.
But Dr. Ochoa feels his company's product is ready to go. "At this moment, CeraRoot implants can be implanted in favorable cases," he said. "Restoring a unitary tooth in the front area is very easy and very predictable."
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