Silver amalgam fillings are the cheapest type of filling, both with and without insurance. Besides gold, they are also the most durable dental filling material. But because silver fillings contain mercury, many people ask the question: Are amalgam fillings safe?
If you're worried about mercury poisoning from fillings and you want to know the benefits of amalgam fillings vs. composite, you're in the right place. Here you can discover the facts about what fillings are made of, results from scientific studies, and the practical pros and cons of different filling materials.
Are you considering amalgam filling removal, whether for cosmetic or health reasons? Removing mercury fillings is potentially dangerous, so read the arguments for and against replacing silver fillings with white composite ones before you decide what to do.
We hope this information empowers you to make the right choice for your restorative dentistry needs!
Table of contents
- 1 What are dental amalgams made of?
- 2 Amalgam filling vs. composite summary
- 3 Are amalgam fillings safe?
- 4 Amalgam fillings removal
- 5 Conclusion
- 6 Mercury fillings FAQs
What are dental amalgams made of?
The purpose of a tooth filling is to repair, strengthen and protect teeth that have been damaged by tooth decay.
In this article, we're going to focus on the two most common dental filling materials in the US: amalgam (silver metal) and composite (tooth-colored material). If you want to learn about other materials like glass ionomer and gold – and more about fillings in general – check out our full guide to fillings.
Silver amalgam fillings
It's been almost 200 years since dental amalgam was first used in the United States to fill teeth cavities. Its quality has improved greatly over the years, as have the dentistry techniques used to place fillings. It's now the most commonly used type of filling around the world, according to the World Health Organization.
Amalgam fillings may be called ‘silver fillings‘ or ‘black fillings‘ because of their color (they become darker over time). They're also known as ‘mercury fillings‘ because – you guessed it – there is mercury in amalgam fillings. It's this ingredient which has made dental amalgam the subject of continuing controversy, due to concerns about its impact on human health both directly and through environmental pollution. Later in this article, we'll look at whether these concerns are warranted and some of the possible mercury fillings side effects.
Dental amalgam definition
For now, let's look at the basics: what is amalgam dental filling?
Dental amalgam is a metal made by mixing elemental (liquid) mercury with silver, tin and copper in powdered form.
The percentage of mercury in amalgam fillings is around 50%, then about 20% silver, 16% tin, 15% copper plus other trace metals. The exact composition your dentist uses may vary slightly, but there is always between 45% and 55% mercury in an amalgam filling.
Once the mercury is mixed with the other metals, it forms a putty that can be easily pressed into the cavity being filled. It takes around 24 hours to fully harden.
Amalgam vs. composite
Aside from concerns over toxicity, which we'll explore later, the main drawback of amalgam is the ‘metal teeth‘ look. A silver tooth filling might not bother you if it's tucked away at the back of your mouth, but many people don't like the idea of others being able to see their fillings when they smile or laugh.
On the plus side, amalgam fillings are cheaper than any other kind and are most likely covered by your insurance, whether private, through the ACA, Medicaid or CHIP. They are also relatively straightforward to place, meaning you spend less time in the dentist's chair.
From a technical point of view, amalgam is quick and easy to place compared to other types of filling. However, because it doesn't chemically bond with the tooth, some of the healthy tooth structure has to be removed in order to prepare a space that will keep the filling secure.
White composite material
The most common type of amalgam-free filling material is resin composite. There are various different formulae used for dental composite, but they all contain a kind of synthetic resin which gives them a plastic-like composition.
Composites were first introduced in the 1960s and have undergone various changes and refinements in the decades since. Improvements are still ongoing, and it's realistic to expect that composite – or some other alternative – will eventually replace amalgam dental completely.
You'll notice there's no section devoted to the topic “Are composite fillings dangerous?” – simply because there are no real concerns about the safety or toxicity of composite material.
It is worth noting that the majority of composites contain derivatives of BPA – a chemical found in many plastics which can disrupt hormones in the body. No studies have shown that composites containing BPA are harmful to humans. However, BPA-free composites are available to patients who want to avoid this chemical. Ask your dentist about the options if this is something you're worried about.
Composite vs. amalgam
Composites are shaded to match the natural tooth color as closely as possible, making them almost undetectable. Over time, however, resin composite can stain and become more noticeable. It can also shrink slightly, creating small gaps that harbor bacteria.
The process for placing composites requires more time and skill than amalgam. The tooth surface must be kept completely dry while the surface is etched and the filling is built up in layers which are cured one at a time. One benefit of composite is that it chemically bonds to the tooth structure which offers extra support and means that no additional healthy tooth has to be removed in the process.
For a long time, amalgam was regarded as the best direct filling material in terms of strength and durability. Metal fillings last 10-15 years and can withstand a great deal of pressure on biting surfaces of the teeth. However, as composite resins improve, they are edging closer to rivaling amalgam in this regard.
Still, dentists may advise against using composite for large fillings and those in stress-bearing positions because of its physical limitations. White fillings usually need to be replaced after 5-10 years – and sooner if they crack or fracture under pressure.
Amalgam filling vs. composite summary
In the table below you can see a summary of the main differences between silver fillings and white fillings.
In cases where composite is not a suitable replacement for amalgam, a porcelain inlay or crown would be the next option to consider.
Are amalgam fillings safe?
For almost as long as they have been in use in the Western world, people have questioned whether mercury amalgam fillings are safe. Perhaps with good cause – at least initially – since amalgam was mixed and applied somewhat primitively when it was first used.
Now, with much-improved formulae and dentistry techniques, dental amalgam is recognized as safe by numerous health organizations worldwide. Extensive scientific research has been conducted to examine the potential health problems stemming from dental amalgam, but health authorities around the world have found no evidence linking amalgam fillings to adverse health effects.
The Food and Drug Administration (FDA) “considers dental amalgam fillings safe for adults and children ages 6 and above” based on the best available scientific evidence. The NHS, Oral Health Foundation and British Dental Association all take a similar stance.
The only countries that have banned the use of dental amalgam outright are Norway and Sweden. In both cases, a wide range of mercury-based products were phased out for environmental reasons.
A study published by the Norwegian Institute of Public Health in 2016 examined various side effects experienced by patients with amalgam vs. composites. The research found that although patients with an amalgam filling had slightly higher levels of mercury in their urine after both five and seven years than those with composite, there were no significant differences in kidney function, neurological function, and a range of other measures.
“Amalgam poisoning” claims
So why do some people still claim that silver tooth fillings have a detrimental effect on people's health? You don't have to look far online to find long lists of supposed amalgam tooth filling side effects, including serious neurological disorders such as Alzheimer's, Multiple Sclerosis and Parkinson's.
The case against metal fillings usually centers around one or more of the following:
- Allergic reactions to mercury fillings
- Mercury poisoning from tooth fillings (leading to many different side effects)
- Environmental contamination from mercury in amalgam
So let's explore each of these issues in more detail.
Can you be allergic to amalgam fillings?
In short, yes. It's estimated that between 1% and 3% of the population experience sensitivity to one of the metals present in dental amalgam, resulting in an allergic reaction.
Symptoms of an amalgam filling allergy usually present as a rash, inflammation, burning or oral lesions near the filling site. Patients may also experience itching or hives on other parts of their body. After the filling is removed and replaced with another material, these side effects should disappear.
If you experience any of these mercury fillings symptoms or find yourself in severe pain after an amalgam filling, contact your dentist straight away.
Can you get mercury poisoning from fillings?
First, let's acknowledge that mercury is known to be toxic to humans in sufficient quantities. Mercury occurs naturally in water, air and soil, and most of us have a small but measurable amount present in our bodies. Eating fish and seafood contributes to this, but it does also come from dental amalgam used in fillings (and other sources). Exposure to large amounts of mercury can cause poisoning, particularly affecting the brain and kidneys.
So are mercury fillings dangerous? Is there such a thing as mercury fillings leaking, and what are the symptoms?
The highest risk of exposure to mercury comes while placing and removing mercury fillings. Once the filling is in place, only trace amounts of mercury are released from fillings while biting and chewing. People who habitually grind their teeth may be at increased risk since they may gradually grind their fillings down.
Some people claim that having their fillings removed has cured them of mercury poisoning symptoms such as:
- Short-term memory problems
- Mood swings
- Poor attention span
- Physical tremors
However, there is no clinical research to back these claims up. Studies such as this one continue to agree that, despite dental amalgam coming under such tight scrutiny, it has no evident adverse health effects on the general population.
There is also no scientific evidence to suggest that amalgam fillings are responsible for conditions such as autism, Alzheimer's and MS; nor is there any solid proof that the removal of mercury fillings relieves these and other symptoms (except in the case of allergies).
For a more detailed examination of possible mercury amalgam poisoning from tooth fillings, this article is a good read.
The environmental impact of mercury amalgams
By far the biggest known disadvantage of amalgam fillings is the release of mercury into the environment. As things currently stand, the main risk of mercury amalgam poisoning comes not from the fillings in your own teeth, but from other people's old fillings that aren't disposed of correctly.
A 2014 report from the World Health Organization (WHO) states that dental amalgam is often the largest source of mercury in municipal wastewater, and it also contributes towards mercury pollution in the soil and air. Most of this comes directly from dental clinics, but mercury can also end up in the environment through the burial or cremation of deceased people who had silver tooth fillings.
Why is this a problem?
The elemental form of mercury used in fillings is relatively stable. But if this mercury makes its way into the environment it can be converted into toxic methylmercury. This easily enters the food chain, particularly through fish and seafood, and it's in this way that humans become exposed to mercury in its most harmful form.
Banning dental amalgam is one way to stop this problem, but until that happens, the next best solution is to ensure it's disposed of properly.
Some countries have implemented strict regulations for the disposal of dental amalgam. For instance, as of June 14th, 2017, US dentists must install special separators that catch dental amalgam waste, stopping it from being released into sewers. Elsewhere, particularly in developing countries, amalgams can end up in general waste with no special treatment.
The Minamata Treaty of 2013 brought together 140 countries in a commitment to reduce the amount of mercury released into the environment from sources including dental amalgam, batteries and cosmetics. This led to the introduction of new guidelines for participating nations, such as the US, to reduce the toll mercury makes on the environment through various tactics, including developing initiatives to reduce the use of mercury in dental amalgam.
Some campaigners have used this to fuel the argument that dental amalgam is unsafe to use, but it must be stressed that the legislation stems from environmental (rather than health) concerns.
Why do dentists still use silver fillings?
With all this controversy over the use of mercury fillings, you might be wondering why we don't just stop using them. Although some dentists in the US now operate ‘mercury-free' dental practices, the majority still use dental amalgam.
The reason for this is simple: no other filling material is as cheap, durable and easy to place as amalgam. Banning amalgams outright would make basic dental care unaffordable for more people.
There is certainly pressure for dentists worldwide to phase down their use of amalgam, mainly for environmental reasons, so it's likely we will see more and more countries introducing restrictions on amalgam fillings and promoting the use of alternative materials.
Getting dental amalgam fillings during pregnancy and breastfeeding
Pregnancy hormones make women more susceptible to oral health problems such as gum disease, so it's important to continue regular dental checkups while pregnant. Medicaid offers free dental care for pregnant women within a certain income level. Read more about Medicaid dental eligibility.
It's perfectly safe to get your teeth cleaned at the dentist during pregnancy to maintain good oral health. However, dentists may prefer to postpone more intrusive procedures – especially those requiring anesthetic – until after the birth, unless there is an urgent need (e.g. if you are in pain).
If your dentist identifies a dental cavity while you're pregnant, he or she will assess how urgently you need a filling and will advise you accordingly.
Amalgam fillings removal
Having read all of this, you can now make a more informed decision about whether to get amalgam fillings or composite next time the need arises. But what about removing an existing amalgam filling and replacing it with composite?
You might be considering mercury filling removal because of cosmetic reasons, health concerns, or a combination of the two. Or perhaps an old silver filling hurts and there is a medical need to replace it.
Getting silver fillings replaced with white
The general consensus is that the benefits of removing amalgam fillings don't outweigh the benefits of keeping them in place, provided they are still mechanically sound.
The Oral Health Foundation “advises patients not to have their amalgam fillings replaced unless they are certain they are allergic to dental amalgam, as the process of removal can weaken the teeth.”
The American Dental Association takes a similar stance, quoting the New England Journal of Medicine: “There is no clear evidence supporting the removal of amalgams.”
The pros and cons of amalgam filling removal are summed up in the table below:
Because of all the possible risks, dentists will often advise against replacing silver fillings with composite unless:
- You have experienced an allergic reaction to dental amalgam
- An old amalgam filling has cracked, shrunk, come loose, or failed in some other way
- A tooth with a metal filling has developed secondary dental caries (tooth decay under the filling)
That's not to say you'll have trouble finding a dentist willing to remove your amalgam fillings for other reasons, if that's the treatment you choose. Increasing numbers of dentist now specialize in safe removal of mercury fillings because of the growing demand for this procedure.
If you wait until your old amalgam fillings have come to the end of their life and need to be replaced anyway, there is no reason not to replace your silver fillings with white fillings – as long as you're prepared to pay for private treatment (more on costs below).
Removing amalgam fillings and side effects
Mercury amalgam fillings usually last 10-15 years. Once they start to show signs of failing, silver fillings need to be replaced. Because some mercury vapor is released during amalgam filling removal, dentists should take special precautions to protect themselves and the patient from the risk of mercury exposure.
For the most secure mercury tooth filling removal, find a dentist who uses SMART (Safe Mercury Amalgam Removal Technique), a protocol recommended by the International Academy of Oral Medicine & Toxicology (IAOMT).
Safety measures utilized in this technique include:
- Using a filtration system in the room
- Giving the patient an adsorbent solution (often containing charcoal) to rinse and swallow before the procedure
- Fitting a nasal mask to the patient so they have a clean air supply
- Using a dental dam to seal off the tooth being treated
- Using a high-speed saliva evacuator (suction tool)
- Keeping the filling cool during removal
- Removing mercury fillings in as large chunks as possible
- Disposing of the old filling material in a safe way
Dental staff will also use special equipment to protect themselves from exposure to mercury vapor. In the video below you can see how this looks in practice:
Before getting amalgam fillings removed, ask your dentist what technique they use and what special safety measures they have in place during the process. If you feel that they take inadequate precautions, you can always look elsewhere for a clinic that specializes in this procedure.
You might also consider visiting a dentist overseas to save money on filling removal – particularly if you have several teeth that need work. That said, some dentists recommend treating one tooth at a time, with several months between treatments, to minimize the mercury side effects from the process.
What does replacing silver fillings with white cost?
The cost to remove amalgam fillings depends on an important distinction:
If it's your choice to have your silver fillings removed, you should check to see if it's covered by your insurance. The cost of safe amalgam filling removal with a dentist who specializes in this procedure (using the SMART process described above) can be as much as $300 per tooth – plus the cost of the filling. Dentists who don't have quite such extensive safety precautions in place might charge considerably less.
If there is a clinical need to remove your old fillings, this part of the process will most likely be covered by insurance. If you choose to replace your amalgam fillings with composite instead, you may have to pay for the white fillings privately. The cost of a single white filling in the US can be anywhere from $90 to $250 for one tooth, depending on the size of the cavity and other factors.
Some dental insurance policies may cover part of the cost associated with this procedure. You'll need to check your policy for details though. Base-level policies generally have no allowance for elective cosmetic treatment.
There are many factors to consider when deciding whether to get silver or white fillings.
Dentists worldwide are gradually moving away from using dental amalgam, but this is largely because of environmental concerns about mercury toxicity. Regardless of any health concerns, many people wish to avoid metal fillings because of their esthetics. Composites are far less noticeable but aren't as strong and durable as amalgams, especially in stress-bearing positions. Composite also costs more than amalgam.
Replacing silver fillings with composite material for purely cosmetic reasons is generally not advised, due to the risk of exposure to mercury vapor and possible complications. However, many dentists do offer this procedure and take steps to ensure it's done as safely as possible.
If you need a new filling and would prefer not to have amalgam, speak to your dentist about the other possibilities. If a composite won't do the job well enough, a porcelain inlay may work instead.
Mercury fillings FAQs
Can mercury leak from amalgam fillings?
Silver mercury amalgam does emit tiny amounts of mercury vapor, mainly during the placement and removal of the filling. But don't imagine blobs of mercury dripping into your mouth like a leaking tap – the mercury in amalgam fillings is chemically bonded to other metals to make it more stable.
Is it safe to remove amalgam fillings during pregnancy?
There is no scientific evidence to show that your existing amalgam fillings have any harmful effect on the health of you or your infant. But when removed, amalgam fillings release a small amount of mercury vapor. If this enters the mother's body it can be passed onto her infant through the placenta or while breastfeeding.
Therefore, dentists won't remove amalgam fillings during pregnancy unless absolutely necessary, i.e. if a filling is broken or there is further decay requiring urgent treatment.
Can you cover silver fillings with white?
In short, no you can't. Placing a white filling over your existing silver filling would affect your bite, and dentists wouldn't recommend drilling out part of an amalgam filling to cover it with composite because of the potential risks and damage to the tooth structure.
However, there are safe ways to completely remove silver fillings and get white ones in their place.
Can you replace silver fillings with white fillings?
Yes, absolutely. Whether it's because of health concerns or cosmetic preferences, replacing amalgam fillings with composite is a relatively common procedure. The part people don't agree on is whether it's a good idea to remove amalgam fillings before they have come to the end of their natural life. Removing amalgam fillings releases mercury vapor, so many dentists will advise against this unless it's clinically necessary.
Where can I find a SMART mercury removal dentist near me?
You can find a mercury removal dentist that specializes in the safe removal of amalgam fillings by searching for SMART members on the International Academy of Oral Medicine and Toxicology's website. If you continue to be concerned about leaking fillings and the safety of dental mercury, then you may want to find a SMART-certified dentist to remove your mercury dental fillings.