Dental Implants Metal Allergy
Dental implants have revolutionized modern dentistry, providing a solution for missing teeth that very closely resembles natural teeth. Implants replace both the root of the missing tooth and the tooth itself, allowing the implant to both look and function just like a natural tooth would. A dental implant is made of two main parts: an implant fixture, and a dental crown. These two parts are attached with an abutment, which may be built on to the implant fixture or which may be attached to the fixture after it is placed. A dental implant fixture is a small cylindrical post that is implanted into the bones of the jaw where the root of a tooth once was. Once this post has healed into the bone, a dental crown, made to look just like a natural tooth, is attached to the abutment at the tip of the implant fixture. These dental implant posts are usually made of titanium, a metal that has proven to be highly biocompatible and durable. In some people, however, titanium, or other metals, can elicit an allergic reaction. When patients are allergic to titanium, dentists can often use a suitable substitute material, like zirconia, for successful dental implants.
Allergic reactions arise when the body’s immune system responds excessively to a specific foreign substance. Allergic reactions can manifest as minor rashes, or as a complete shutting down of the body’s internal organs -- or as many things in between. People can be allergic to anything, and allergic responses can take many forms. When people are allergic to metals, they are usually allergic only to specific kinds of metals. Nickel, chromium, and cobalt are the most frequently allergenic metals, though people can be allergic to any type of metal. While the majority of allergic reactions to metal are caused by surface contact with the skin, some people can have allergic reactions to the metal in a prosthesis or replacement body part; when this is the case, the body rejects the allergen, thereby rejecting the prosthesis or body part.
Throughout the existence of modern dentistry, a variety of metals have been used by dentists for a variety of reasons. For example, one of the most common uses of metal in dentistry is in the metal amalgam that is used to fill dental caries, or cavities. This metal dental amalgam is a combination of precious metals, like silver or gold, mixed with copper, tin, small amounts of medical-grade mercury, and other metals. Dental amalgam has been used successfully for decades, though there have been some cases of irritation, usually in the form of inflammation or rashes, that are caused by dental amalgam. The biocompatibility of titanium was first discovered in the 1950s, and the material was first used in dental implants in the 1960s. Titanium was chosen as the optimal metal for dental implants, and in other medical applications like replacement hips or knees, because of its uniquely effective compatibility with bone. Titanium encourages bone cells to adhere to the metal and stimulates the growth of healthy bone, creating a permanent bond between the implant and the bones of the jaw and creating a durable foundation for the dental replacement. This process of the implant and bone fusing together is called osseointegration. Titanium is also very unlikely to provoke an allergic reaction, even among people who have allergies to other metals. In fact, in one study of dental implant patients, out of 1,500 patients less than 1% of patients had any reaction whatsoever to titanium.
When titanium implants are placed and the patient is allergic, symptoms include bumps, hives, or a rash in the mouth; patches of dry or irritated gum tissue; inflammation in the gums in the area of the implant; and swelling or sores in the tissues of the mouth. Dentists can use a simple test to test patients for allergic reactions to titanium before placing implants when patients face concerns about titanium allergies. While skin tests for titanium allergies are usually available, some dentists prefer to use a test called a MELISA test. The MELISA test, which stands for memory lymphocyte immunostimulation assay, is a blood test that isolates the white blood cells and exposes them to titanium and then measures their immune response. The MELISA test is more accurate than a skin test and should be used when available.
When an allergy to titanium is present, zirconia implants can be a great alternative. Zirconia dental implants were first introduced in 1987. Zirconia, also known as zirconium oxide, is sometimes referred to as ceramic steel because of how durable and corrosion-resistant it is. Zirconia is an inert ceramic material that presents almost no risk of allergic reaction. Zirconia implants are currently only available as one-piece implants; while this limits the number of situations in which it’s a suitable option, it also helps zirconia implants remain clean and free of plaque buildup. Zirconia resists corrosion, bonds successfully with bone, and is exceedingly durable and very strong. It is also non-conductive, which can help maintain the health and integrity of the mouth. It has been found to fuse to bone as effectively as titanium does, and its white color helps it remain invisible through the thin tissue of the gums. Zirconia was approved for use in dental implants in the United States in 2011, and it has steadily increased in popularity throughout the US and the rest of the developed world. Its increased popularity is attributed to the fact that it fuses to bone as effectively as titanium does; it also provides the added benefit of being non-corrosive. Zirconia implants are currently only available in a limited number of styles, which means they may not be recommended for more complex or elaborate dental restoration needs; for example, if the implant must be placed at an angle because of a shortage of healthy bone, this may not be possible with the currently available types of zirconia implants. As zirconia increases in popularity, however, it is likely that zirconia implants will become available in a wider variety of styles and with more custom components, providing an excellent metal-free dental restoration option for a greater number of patients who are missing one or more of their natural teeth. Placing zirconia implants may also require more care, making them slightly more expensive than their titanium counterparts; again, as more and more dentists offer zirconia implants as an alternative to titanium, they will become easier to place and may also become more affordable.