When different metals are linked together by an acidic “bridge,” it can create an electric current. This current may not be very strong, but it does accelerate the corrosion of one of the metals. This is called galvanic corrosion, after Luigi Galvani who discovered the phenomenon that dissimilar metals created currrents. This is the reason why the Statue of Liberty was endangered. The copper exterior was accelerating corrosion and stealing material from the iron supports.
In our mouth, the presence of ions and even a slightly acidic environment can create a situation where two different types of metals will link into a galvanic circuit, and one of them will suffer accelerated corrosion. Does this mean that having metal fillings will threaten your dental implants?
The Galvanic Series and Metal Amalgams
After Galvani (and his contemporary Alessando Volta) discovered that different metals created currents, other people began to explore which metals could be used to create currents, and, therefore, which metals would be corroded in the presence of each other. This led to the creation the galvanic series, which charts which metals are likely to be corroded in the presence of each other.
On this listing, the metals most resistant to corrosion are at the top. You can see that titanium, the metal used for dental implants, is toward the top of the list. This means that very few things threaten to initiate corrosion of dental implants. Gold or palladium in a noble metal crown is a threat to dental implants.
Most of the metals found in metal amalgam fillings–tin, copper, and zinc–are far down at the other end of the series. They are much more likely to be corroded than to cause corrosion in other metals, such as dental implants.
However, mercury, which constitutes about 50% of the composition of metal amalgam fillings is more noble than titanium, and contact between metal amalgam and dental implants in the oral environment could lead to corrosion of dental implants.
Adding Dental Implants to a Mouth Full of Metal
If you already have many oral restorations that use metal, dental implants might be at risk, but that doesn’t mean you have to worry.
First, all the metal in a dental implant should be covered by your gum tissue and the ceramic crown on the top of the implant. If you avoid peri-implantitis, your dental implant should be safe from corrosion.
But if you have a history of periodontal disease or you’re concerned about what could happen if you introduce titanium into the environment of metal restorations, we have a number of solutions. First, we can remove metal restorations like amalgam fillings and metal crowns, replacing them with highly attractive and corrosion-free ceramics or composites.
Or we can use a metal-free dental implant that isn’t susceptible to corrosion at all. These implants are just as successful as titanium implants, but protect against this and other effects of metal in the mouth.