Zirconia Dental Implants
Dental implants are an appealing alternative to removable dentures and are used to replace one or more missing teeth. Titanium has been a popular material for multiple medical uses since the 1960s and has proven its success as an option for dental implants, in particular, with a long-term success rate of close to 97%. Zirconia was introduced as a titanium alternative for dental implants in 1987 and quickly gained in popularity in Europe. The FDA approved the use of zirconia dental implants in the United States in 2011, and they have quickly become a popular option for many patients, increasing in popularity as more and more patients seek biomimetic or holistic dental solutions. While titanium dental implants can be a great option for people who want to replace one or more missing teeth, some people prefer to have metal-free dental restoration options, either due to a metal sensitivity or allergy or simply because of personal preference. Zirconia dental implants are an excellent option for these patients who seek dental restorations that don’t use metal. Zirconia is an inert material, which means that it does not react with other materials in any significant way and is therefore suitable for people with allergies or sensitivities to metals. Zirconia is also biocompatible, strong, and highly fracture-resistant, making it an excellent implant option in terms of mechanics and function, and its white color helps zirconia implants blend seamlessly and naturally into dental crowns, enhancing the appearance of the implant and removing the risk of dark metal showing through the crown or being visible at the gumline. Zirconia implants can be made in one-piece or two-piece styles, can be more plaque-resistant and easier to clean than other materials, and have been shown to integrate successfully into the bone, providing a stable foundation for dental restorations. The primary shortcoming of zirconia implants is simply that they haven’t been in use long enough to determine their success in the long term. The clinical studies that do exist report survival rates for zirconia implants that are comparable to those of titanium implants.
Zirconia is a ceramic material that contains inert materials and is white in color. It has been reported to be comparable, if not superior to, titanium in terms of biocompatibility and aesthetics, and can be expected to undergo osseointegration as successfully as titanium. Osseointegration, an integral part of the success of dental implants, occurs when the jaw bone fuses with the dental implant fixture, creating a stable and supportive substitute root for a dental crown that will look and function just like a natural, healthy tooth. Because zirconia is white, it does not pose the risk of being visible through the gum tissue or the crown; the implant is the same color as natural teeth, so there is no risk of dark metal being visible. This is especially important when the teeth that are restored are the front teeth, or those in what is known as the aesthetic zone. There is also evidence that zirconia implants accumulate less plaque, leading to less infection, than titanium implants, and zirconia is corrosion-resistant and non-conductive.
While they are extremely rare, adverse reactions due to metal allergies have been described with titanium implants. Most titanium implants are between 89% and 99% titanium, but these alloys can contain various amounts of other metals, including iron, chromium, manganese, tin, molybdenum, tungsten, and nickel, potentially allergenic elements that may not be listed by the manufacturer. Zirconia actually does contain the metal zirconium, but in its oxidized state, it is non-metallic and poses no risk to people with metal allergies or sensitivities.
Clinical studies have indicated that zirconia may be more likely to degrade at lower temperatures as the material ages, which may lead to a reduction in the strength or resilience of the material, though there have not been enough long-term studies to determine the possible extent of degradation. Initially, zirconia implants were only manufactured as one-piece dental implants, limiting their efficacy in a number of situations; two-piece implants can retain a dental crown at a precise angle that allows the dentist to efficiently use the amount of available bone while still providing a mechanically functional and visually appealing dental alignment, while one-piece implants cannot be angled and are more limited in their positioning. In 2019, two-piece zirconia implants were introduced to the US market, dramatically increasing the number of options for custom zirconia implants, though limitations do still exist. These limitations are more significant when replacing multiple teeth and are generally not a cause for concern with single-tooth replacements. As clinicians continue to research two-piece zirconia implants and learn more about possible improvements to their design or manufacture, we can expect to have more and more access to excellent two-piece zirconia implants in the future.
While zirconia is exceedingly strong when compressed, it is more brittle than titanium. It is also more prone to fracture when bent than titanium. This leads clinicians to expect that zirconia may have a higher likelihood of complications, including fracture, over the long term. Zirconia implants may be more prone to cracking, and zirconia implants that are smaller in diameter may be more prone to fracture than larger zirconia implants. These smaller implants may be necessary because the patient has very little space between the teeth, or particularly thin bone, further limiting the uses for zirconia in certain patients. Zirconia may also be a less-than-ideal option for patients who need to replace most or all of their teeth, as these larger, more complex restorations require a wide variety of component options for ideal positioning and strength, and many of these components are not available in zirconia. Of course, this may change as zirconia continues to be a material of interest for dental implant restorations.
Clearly, zirconia implants provide multiple advantages for the right patient, though it is not a perfect material. Despite its possible shortcomings, however, zirconia is safe, biocompatible, and effective in the shorter term, and it may be a preferable implant choice for people with allergies or sensitivities to metal or for people who prefer to avoid having metal surgically implanted in their bones. Your dentist can help you determine if zirconia implants are a valid or preferable choice for you and your dental implant needs.