Although there has been no conclusive research that shows that silver mercury fillings are harmful to your health (regarding mercury leeching), in our experience we have seen a lot of problems that occur underneath these old fillings. These are problems are not easily observed from the surface or with X-Rays and is primarily to do with decay getting under the fillings and cracks in the teeth.
Silver fillings can hide decay
Because silver fillings are opaque to X-Rays, it’s difficult to see a cavity under the filling until they are quite extensive. Research has shown that when you’re examining a patient with silver fillings, if you don’t use any X-Rays you can see 50% of what is going on and with a full set of X-Rays you will still only see about 80 – 85% of what’s going on. So there is 15% – 20% of cavities that we wont be able to see because the metal blocks out this damage.
In some cases, this can mean the difference between getting another filling or having to have a root canal treatment.
Silver fillings are also a factor in teeth cracking
Another factor to consider is the cracks in the teeth, which also won’t show on X-Rays at all. We see this commonly in people in their 40’s or 50’s.
Do tooth coloured fillings prevent teeth cracks or decay?
We know from the research that silver fillings do not strengthen teeth at all. So a silver filling in a tooth, essentially acts like a wedge, and when you bite down on the filling the forces are transmitted to the remaining tooth structure. If the filling is more than about a half of the width of the tooth there is a good chance that the tooth is going to crack, break or chip. If the filling is a third of the size of the tooth it is less likely but still a risk.
Because the silver filling material was usually just packed in, there is no adhesion of the silver filling to the tooth, which we get with the tooth coloured materials. This adhesion means that the chewing forces are distributed over a greater amount of tooth, making the tooth about 15 – 20% stronger with the tooth coloured compared to silver filling.
The force of biting down with the chewing is also distributed across the whole tooth structure more evenly than it is with silver filling, meaning less likelihood of tooth cracking.