Title: What should I do about my old metal fillings?

A frequent question that I get from my patients is about old metal fillings.  Many patients are concerned about mercury content in old metal “silver” “amalgam” fillings.  They want to know if they are safe and what can be done to replace them if they give the teeth a grey hue that is unsightly.  Sometimes fractures lead patients to ask this question and they want to “up-grade” to tooth-colored fillings.

Okay, so to be clear, the FDA and ADA have looked into the subject of toxicity of metal fillings for many years and both organizations consistently maintain their position that metal fillings with mercury in them are in safe.  They indicate that no scientific research has ever been produced linking mercury in fillings with any health problems.  And it has been studied quite a bit.

As a matter of fact, a dentist telling patients that they can solve health problems by removing metal fillings is malpractice.  Okay, so when do we replace them and under what circumstances?

Metal fillings will leak as all fillings do over time, which is why fillings should be avoided in the first place with fluoride.  However, should decay start again under an old filling, it’s time to replace the filling.

Sometimes metal fillings will hold together just fine, but the tooth breaks around the filling with years of wear.  Teeth do become brittle with age and the metal can act as a wedge, much like splitting wood.  Cracks form in the enamel that can get deeper into the softer parts of the tooth called dentin.  When this happens painful symptoms will develop while chewing harder foods.  This is the first conclusive sign of a deep crack in a tooth.  At this point you need a crown and even possibly a root canal if you have caused excessive trauma to the nerve or “pulp” inside the tooth.

This is a common selling point for doing crowns, to prevent a tooth from splitting with the existing metal fillings.  However, crowns require much trauma to the tooth and make the tooth into a little nub.  It is very invasive on a tooth.

I prefer to delay doing crowns until there is a clear reason driving this decision such as early symptoms of a cracked tooth.  To do a crown for a small “craze line”, much like a crack in the windshield of your car is a bit aggressive if the crack in only inside the enamel.

How do we know it’s only in the enamel? If there are no symptoms it most likely is a shallow “craze line” fracture.  The deeper and softer part of the tooth is adjacent to the nerves and a fracture that is felt is certainly deep enough and completely through the enamel.  This is when a crown is necessary to save the tooth and to remedy these early signs of deep fractures.  If allowed to continue a tooth might fracture badly and you might lose the tooth or require a root canal too.  Waiting too long can mean less chance of success in avoiding root canals.  The more stirred up the nerve of a tooth with more time means a greater chance of needing a root canal.

Okay, I’m not in pain but I don’t like my metal, can I get them replaced?  Sure.  BUT be warned that each time we remove a filling there is a chance that you can lose more tooth structure leading to an eventual crown or root canal.

ALL fillings fail over time so it is necessary to get enough mileage out of each one.  Metal ones have the longest track record of proven longevity.  If you really don’t like the look and it bothers you to the point of accepting this warning, then by all means, let’s make them tooth colored fillings!

I hear that tooth colored fillings don’t last as long, is that true?  Yes and no.  Old versions of tooth colored fillings with weaker bonding strength and unproven techniques failed more quickly.  However, recent advances in tooth colored filling materials and techniques seem to be on par with even metal fillings if done properly.

It is harder to do a tooth colored filling because you have to keep it dry the entire time you do it.  (This is why I still use metal fillings to fill decayed teeth with crowns where the decay goes below the gum line. You can’t get it dry so metal is the only reliable option.)  Metal fillings are easier to do and hard to mess up which is why they are considered so reliable.  However, the new tooth colored materials and techniques if done well are far superior to metal fillings.  Why?

They bond to the tooth so they don’t have the “wedge” effect.  They look much nicer.  They allow the dentist to be more conservative removing less tooth structure.  They don’t have mercury.

But you said mercury in fillings is safe?  Yes, but mercury in our environment is mercury in our environment!  Every time I remove or place a metal filling there are scraps of mercury that go in our environment inadvertently.  PLUS, when I drill out old metal fillings there IS free mercury vapor released which is potentially harmful to the patient and to my staff and I.

That is why I am not eager to remove old metal fillings and would MUCH RATHER leave them be unless there is a reason to remove them like recurrent decay, removing metal for CT scans using techniques such as SureSmile or for dental implant planning.

If I have to remove them I use LOTS of water spray and high volume suction to catch the mercury vapor and to limit vapors by keeping the cutting surface cool.  This also leads to less trauma to the nerve of the tooth leading to less sensitivity following the procedure.

I hope that you have enjoyed this short discussion on metal fillings and that it helps you.  Please ask questions related to this blog and I will answer them each week.

Blessings to you all,

Dr. Reemon Y. Ashoty, DDS