It’s hard to find many people over the age of 30 in the United States who have not had at least one silver filling in their lifetime. In fact, it’s really only been in the last 35 years that comparable alternative materials have been developed for fillings in the back teeth. Our back teeth can take a beating over a lifetime. Average chewing forces alone in the molars can exert about 70 pounds per square inch, but for people who clench and grind regularly this force can increase by 6 to 10 times as much, or more. Obviously, any material used to restore the back teeth needs to be strong and durable.
For many years, the argument for silver fillings has been based on their strength, durability, ease of placement, and cost. Silver fillings are the least expensive filling material available on the market and require the least amount of preparation work on the tooth in order to place them. Yes, silver fillings contain metals and mercury, but proponents believe that the risks of mercury exposure or metal sensitivity are low. Certainly, dental insurance companies would prefer to only pay for silver fillings rather than more expensive metal- and mercury-free alternatives. And for the low-income population without insurance or additional resources, proponents believe a silver filling is better than no filling at all.
There is some truth to that statement. However, the ease and inexpense of the initial placement of a silver filling is not the only cost associated with that filling over a lifetime. The truth is that no filling material will last forever, but silver fillings by their very nature can set up more long-term damage in the teeth than other alternative materials now available. Even if we set aside all the valid concerns about metals and mercury, silver fillings just aren’t the best materials on the market anymore.
Silver fillings are not bonded to the teeth, which means that the margins are not actually sealed. That unsealed microscopic channel between the edge of the silver filling and the tooth makes it nearly impossible to protect the margins, even with exquisite home care. Inadequate or irregular home care will definitely leave these unsealed margins extremely vulnerable to recurrent decay, causing the filling to need replacement with larger and larger silver filings over time. But that’s not the only weakness that a silver filling can present.
Silver fillings also expand and contract in relation to temperature changes in the mouth at a very different rate than the healthy tooth surrounding them. Over time, as we eat hot and cold foods, these differing expansion rates can set up fracture lines in the tooth enamel that leave the tooth even more vulnerable to recurrent decay and breakage. No filling material on the market can exactly match the expansion and contraction rate of enamel yet, but silver fillings are the most likely to set up these kinds of expansion fractures in the shortest period of time.
So if the mercury content, unsealed margins, and the expansion/contraction rate of silver fillings are all of concern, why are silver fillings still in use? The answers are simple: it’s cheaper and easier than newer, better materials. Cheaper and easier may make sense in the short term, but the more we learn about silver fillings and the long-term consequences for the health of our teeth, our bodies, and our environment, those silver fillings may be far more expensive over time than we realize.
In my practice, I have not placed a silver filling in any patient in more than 20 years. I would not place a silver filling in my own mouth, in my children, or in my grandchildren. I do agree that when the only option is a silver filling or no filling, then the silver filling is the better choice. But I do not agree that silver fillings are cheaper in any way other than the initial cost of placement. We can do better across the board and especially by our low-income population, and it is my sincere hope that by keeping the conversation open and continuing to make as much information available as possible, that someday we will.
To learn more about silver fillings and all the other options available in dental filling materials, please visit my newest resource article, A Comparison of Dental Filling Materials.