- Amalgam is an alloy of 65% silver, 29% tin, 6% copper, 2% zinc and 3% mercury. It has been used for 200 years.
- On mercury, the national health portal says systematic research has confirmed it is not harmful, and cites the American Dental Association.
- Gold resists corrosion and is strong. It is described as stable for 10 years or more and suitable for replacing a defective amalgam.
- So what decides replacement is not the mercury but the current condition of the amalgam filling.
"I was told I should replace all my old silver fillings." We often hear this at Reset Dental Clinic in Seomyeon, Busan, sometimes from patients worried about mercury. For patients living in or visiting Korea, we provide 1:1 English interpretation from your first consultation through the end of treatment.
This column explains how published sources look at amalgam, and what the real reasons for replacing a filling are. It is based on the national health portal's guides on amalgam, gold inlays and tooth-colored inlays.
We also use Asan Medical Center's guide on tooth decay. Finally, we draw on the national health portal's guide to preventing oral disease.
What is an amalgam filling made of?
The national health portal gives the ingredients as numbers. Amalgam is an alloy made of the following metals:
- silver: 65%
- tin: 29%
- copper: 6%
- zinc: 2%
- mercury: 3%
Its strengths are clear. It is a material that has been used for 200 years. Treatment is done in one visit, and the filling is strong.
It also has weaknesses. Because its color is different from a tooth, it looks less natural. It also takes about 24 hours to fully harden.
You may remember being told not to chew anything hard on the day of your filling. Those 24 hours are the reason.
So amalgam has real advantages as well as drawbacks. Being old or silver-colored does not, by itself, make an amalgam filling a problem.
If you have amalgam fillings in your back teeth, knowing what they are made of is a good first step. It helps you decide what to do with them.
Is the mercury in amalgam a health concern?
This is the question we are asked most often. So we will pass on what the source says as closely as we can.
As listed above, mercury makes up 3% of the alloy. Many patients still feel uneasy about it, and that is understandable.
On the concern about mercury, the national health portal says that systematic research has confirmed it is not harmful. It also cites the American Dental Association, which has said that amalgam carries almost no risk to the human body.
So this source gives no basis for saying that amalgam must be removed just because it contains mercury. That is as far as the evidence in the source goes, and we will not go beyond it.
There is another side to consider. Removing a sound amalgam filling for no reason means cutting away more of the remaining tooth.
Tooth structure that has been cut away does not come back. So removal is not a neutral step, even when it feels like the safe choice.
When should an amalgam filling be replaced?
The deciding factor is not the material but its condition. The gold inlay guide lists the cases where gold is a good fit:
- teeth that are badly worn
- large cavities
- replacing a defective amalgam
The word "defective" is the key. It covers three situations: the edge of the filling has broken, a gap has opened between the tooth and the filling, or decay has started again through that gap.
Age alone does not decide it. An old amalgam filling in good condition is not the same as one with a broken edge.
Why a gap matters
Asan Medical Center's guide on tooth decay explains why a gap is a problem. Decay starts in plaque, the film of bacteria on the tooth surface.
When those bacteria break down sugar and starch, they make acid. That acid dissolves the enamel, the tooth's outer layer.
A gap is an ideal place for that film of bacteria to settle, and a toothbrush cannot reach it. Decay can then grow under the filling.
That decay can be hard to notice. According to the guide, while decay is limited to the enamel, there is almost no pain.
That is why we take X-rays even when a tooth looks fine. The same guide states that X-rays are essential for diagnosis, along with a visual check and probing with an instrument.
| Stage or step | What the guide says |
|---|---|
| Cause | Plaque bacteria break down sugar and starch, and the acid attacks the enamel |
| Decay limited to the enamel | Almost no pain |
| Decay at the enamel-dentin boundary | Sensitive to cold, and sensitive to sweet things |
| Diagnosis | Visual check and probing, with X-rays essential |
| Treatment | The decayed part is removed completely, then filled with gold or tooth-colored resin |
The last row matters for old fillings. If decay is found under an amalgam filling, the decayed part has to be removed completely before a new filling goes in.
This is one more reason to catch a gap early. The smaller the decay, the less tooth has to be removed to clean it out.
| Reason given | What the sources and this column say |
|---|---|
| It contains mercury | The source says systematic research has confirmed it is not harmful |
| It is old | Age alone does not decide it |
| It is defective | The gold inlay guide lists this as a case suited to replacement |
| It looks fine | Decay limited to the enamel causes almost no pain, so X-rays are checked too |
What can replace an old amalgam filling?
The national health portal describes the materials one by one. Each has its own strengths and weaknesses.
Gold resists corrosion and is strong, so it lasts a long time. The guide describes it as stable for 10 years or more.
It is suited to badly worn teeth, large cavities and replacing a defective amalgam. Its weaknesses are its color, which makes it unsuitable for front teeth, the time needed to make it, and two or more visits.
Tooth-colored inlays are mainly made of composite resin or porcelain (ceramic). Porcelain is widely used for back teeth too.
Resin looks natural and is simple to make. It wears the opposing teeth less, needs less tooth removed, and is elastic, so it absorbs impact well.
Porcelain is highly biocompatible and looks natural. It used to break easily, but that weakness has recently improved.
The guide also lists weaknesses of tooth-colored inlays. They depend on the dentist's skill and take longer in the chair. There is also a risk of fracture in people who grind their teeth, and two visits are needed.
| Material | Strengths | Weaknesses |
|---|---|---|
| Amalgam | Used for 200 years, done in one visit, strong | Looks less natural, takes about 24 hours to harden |
| Gold | Resists corrosion, strong, stable for 10 years or more | Color (unsuitable for front teeth), making time, two or more visits |
| Tooth-colored inlay (resin or porcelain) | Resin needs less tooth removed and absorbs impact; porcelain is biocompatible and natural-looking | Depends on the dentist's skill, longer chair time, fracture risk with teeth grinding, two visits |
Gold or ceramic for a back tooth?
Following the sources, gold is stable for 10 years or more, but its color is different. Porcelain is biocompatible and natural-looking, but it carries a fracture risk if you grind your teeth.
Resin needs less tooth removed and absorbs impact well. The choice depends on these factors:
- your chewing force
- whether you grind your teeth
- how much natural tooth is left
- whether the tooth shows when you smile or talk
If you grind your teeth, keep that point in mind. Your chewing force and habits are part of choosing the material.
Why not replace every amalgam filling at once?
The reason is that cutting a tooth cannot be undone. To remove an amalgam filling and place a new material, the area has to be shaped again.
Each time this happens, the tooth becomes a little thinner.
A filling that is replaced today may itself need replacing one day. Every round takes a little more of the natural tooth, so it makes sense to replace a filling for a real reason.
The source rejects the claim that amalgam is harmful. It also limits replacement to cases where the amalgam is defective.
Given both points, there is no basis for replacing every sound amalgam filling. Often, when someone has several old fillings, one or two of them need attention.
How can you look after old amalgam fillings in Busan?
Instead of replacing everything, we check regularly. The national health portal's guide on preventing oral disease recommends a checkup once a year, or every six months if you have had dental treatment.
If you have several fillings, the six-month interval applies to you. Each checkup looks at whether any filling has a broken edge, a gap or new decay underneath.
The same guide gives simple daily habits. They help protect the edges of fillings, where plaque likes to settle.
- Brush at least twice a day with fluoride toothpaste.
- Brush for at least two minutes each time, looking in a mirror.
- Use dental floss, which the guide calls essential.
- Keep up checkups every six months if you have fillings.
If a filled tooth starts to feel different, do not wait for the next checkup. Sensitivity to cold or sweet things can be a sign that decay has reached the boundary between enamel and dentin.
A checkup can then show whether the change is coming from under the filling or from something else. Either way, it is better to know early.
Frequently asked questions
Does mercury from amalgam build up in my body?
The source says systematic research has confirmed amalgam is not harmful. It also cites the American Dental Association, which said it carries almost no risk to the human body. That is what the source confirms, and we will not claim more.
My amalgam filling is old. Shouldn't it be replaced?
Age alone does not decide it. The gold inlay guide lists a defective amalgam as the case for replacement. We look at whether the edge has broken, whether there is a gap and whether there is decay underneath, using X-rays as well.
My filled tooth feels sensitive. Should the amalgam be replaced?
We first find out why it is sensitive. The tooth decay guide says that once decay reaches the boundary between enamel and dentin, the tooth becomes sensitive to cold and sweet things. A checkup shows whether decay is growing under the filling or something else is the cause.
Can I get amalgam replacement advice in English in Busan?
Yes. We offer 1:1 English interpretation from the first consultation through the end of treatment. The clinic is near Seomyeon Station Exit 2 (5-min walk), opposite Lotte Hotel Busan, and you can call 010-8555-2854 (+82-10-8555-2854 from abroad).
The reason to replace an amalgam filling is its condition, not the mercury.
A broken edge, a gap or new decay underneath
is what calls for a change.
A sound filling can be watched at regular checkups.
If you have old fillings and live in Busan, Reset Dental Clinic offers 1:1 English interpretation from your first consultation through the end of treatment. Call 010-8555-2854 to book a checkup.
References
- KDCA National Health Information Portal, "Amalgam and Inlays (Amalgam)" — the composition of amalgam, its strengths and weaknesses, and the statement that systematic research has confirmed it is not harmful, citing the American Dental Association
- KDCA National Health Information Portal, "Amalgam and Inlays (Gold Inlay)" — gold's corrosion resistance and strength, stability for 10 years or more, suitable cases including replacing a defective amalgam, and its weaknesses
- KDCA National Health Information Portal, "Amalgam and Inlays (Tooth-Colored Inlay)" — composite resin and porcelain, their strengths, and weaknesses including fracture risk in people who grind their teeth
- Asan Medical Center Disease Encyclopedia, "Dental Caries" — how plaque bacteria make acid that attacks enamel, symptoms by stage, diagnosis with X-rays as essential, and treatment with gold or tooth-colored resin
- KDCA National Health Information Portal, "Preventing and Managing Oral Disease" — brushing at least twice a day with fluoride toothpaste for two minutes, flossing, and checkups once a year or every six months after treatment
Written by Reset Dental Clinic Support Team
Medical review Dr. Kim Hyun-joo, Head Dentist · Integrated Dentistry Specialist
Last updated: September 19, 2026
This column is for general information and does not replace diagnosis or treatment for individual patients. If you have symptoms, please see a dentist.
