Before tooth-coloured white fillings became the new standard, metal amalgam fillings were used to repair decayed and damaged teeth for more than 150 years. These fillings combine several metals including copper, mercury, tin, zinc and occasionally silver, creating strong and long-lasting restorations.
Metal fillings are still an option today, but since most patients prefer the natural look of white composite fillings, fewer dentists offer them. There are also concerns about the presence of toxic mercury in metal fillings and its effects on health and the environment. For these reasons, some people with mercury fillings choose to have them replaced with tooth-coloured fillings.
Amalgam removal may be chosen for aesthetic reasons, if you want a whiter smile, or if an old metal filling is worn or damaged and needs to be replaced. However, if you want to remove metal fillings due to health concerns, this can sometimes be more hazardous than leaving them in place.
Dangers of mercury exposure
Mercury exposure can have harmful effects on the body. Ingesting mercury can cause kidney toxicity and corrosion of the gastrointestinal tract. Inhaling mercury vapour can affect the digestive, immune, nervous and respiration systems and at high levels may even be fatal. It can also be a catalyst for other health complications.
However, the amount of mercury contained in amalgam fillings is not thought to be significant enough to cause these problems. Having metal fillings increases mercury levels in blood and urine, but mercury exposure can also come from other sources, such as eating certain types of fish.
Common symptoms of mercury toxicity or overload can include:
- loss of coordination
- mood swings or irritability
- muscle spasms or weakness
- stinging sensations
- vision problems
If you have any unusual symptoms and you're not sure of the cause, you should consult your doctor for a professional diagnosis.
Adverse health effects of metal fillings
Dental amalgam fillings release a small amount of mercury, which is absorbed by the body and can be detected in blood and urine samples. People with more metal fillings or larger fillings have higher levels of mercury than those with fewer or smaller fillings.
The risk of exposure is highest when fillings are first placed or removed, if the dentist performing the procedure is inexperienced and the correct hygiene procedures aren't followed. More mercury may be released if a metal filling is damaged by trauma, biting hard foods, tooth grinding (bruxism) or rough brushing.
However, this exposure is not thought to significantly increase health risks. According to the study The Dental Amalgam Toxicity Fear: A Myth or Actuality, published in 2012, there is no evidence that mercury released from fillings results in adverse health effects in the general population, with the exception of causing allergic reactions in some patients.
The Australian Dental Association (ADA) and National Health and Medical Research Council (NHMRC) support the continuing use of amalgam fillings in Australia, but suggest restricting their use for higher risk patients including:
- pregnant or breastfeeding women
- people with kidney disease
Allergic reactions to metal fillings
Metal fillings containing mercury can cause allergic reactions in patients with mercury hypersensitivity. This is when the immune system reacts to the presence of mercury, even at low levels, which can affect the skin and mouth.
Possible symptoms of amalgam allergy include:
- itchy or swollen lips
- lesions in the mouth
- skin rashes around the mouth, head or neck
These symptoms may go away on their own after a few days, but those that persist may benefit from having metal fillings removed and replaced with a different material. Allergic reactions are more likely to happen with older metal fillings that have corroded or were improperly placed.
Is it safe to remove amalgam fillings?
There are various reasons why people choose to replace their metal amalgam fillings with a different material. This may be:
- for a more natural-looking smile
- to avoid allergic reactions to mercury
- to replace loose, worn or damaged fillings that expose the underlying tooth to bacteria
It's important to choose a qualified dentist who has experience of the procedure, as strict protocols must be followed when placing or removing metal amalgam fillings and disposing of amalgam waste to avoid exposure to mercury. In Australia, this is covered by ISO 24234:2015 'Dentistry - Dental amalgam'.
How are metal fillings removed?
Your dentist will explain the possible complications of amalgam removal so you can decide if it's the right choice for you. To protect you and the dental staff, strict safety protocols will be followed during the procedure. Please speak to your dentist before having mercury fillings removed if you would like to know their protocol.
Once the filling has been removed, the hazardous mercury waste will be disposed of in ways that prevent contamination with people or the environment.
What are the alternatives to metal fillings?
If you want to avoid metal fillings, or you're thinking about having your existing amalgam fillings replaced, your dentist will explain the options they offer at their clinic.
All types of dental restorations have associated clinical risks that your dentist will make sure you're aware of. These risks can be minimised when you choose a qualified and experienced dentist.
Your dentist will also make sure you know what dental treatments cost and what support is available, such as health insurance or payment plans, so you can make a well informed decision.
The most common alternatives to mercury fillings are:
Tooth-coloured 'white fillings' are made from a composite of materials that can be adjusted to match the colour of your teeth for natural-looking results. Although these are less durable than metal fillings, they can still stand up to pressures in the mouth and can last for many years when you take good care of your oral health.
White fillings may be made from either:
- Composite resin – a tooth-coloured composite of plastic and glass. These are the standard fillings used for most adult teeth, unless a cavity is too large or more support is needed.
- Glass-ionomer cement – less strong than composite resin, this is typically used for children's fillings or adult fillings in teeth that are put under less pressure. GIC fillings release a small amount of fluoride over time that helps to protect the tooth against plaque.
If more of your tooth is damaged, or it needs more support than a white filling can provide, your dentist may suggest inlays or onlays.
A middle ground between a filling and a crown, inlays/onlays are custom made out of composite resin or porcelain after taking impressions of your teeth. Once made, they can be bonded to your tooth like a crown, but more of the tooth's structure can be retained.
- Inlays sit inside the biting cusps of the tooth
- Onlays can also rebuild the outer tooth
If a tooth has been badly damaged and has less of its structure remaining, your dentist may recommend placing a dental crown. These provide more support than a filling, but they also take longer and cost more.
A crown is custom made by taking impressions of your tooth or teeth. These are then sent to a dental laboratory that manufactures your custom crown out of porcelain, ceramic or other materials and can match your original tooth colour.
Once the crown is ready, your dentist will bond it into place. Dental clinics equipped with CEREC CAD/CAM systems can design, manufacture and place a dental crown all in one visit.
If a tooth is too severely damaged to be repaired, or a filled tooth has deteriorated, it may need to be extracted. Dentists only recommend extraction in severe cases when there's no chance of restoring a tooth.
To help preserve your other teeth, your jaw and your facial structure, your dentist will recommend replacing an extracted tooth once the gum has had time to heal. Options include:
How to avoid a filling
Fillings are usually placed in teeth that have been damaged by tooth decay. This is an oral disease caused by bacteria that live in plaque on the teeth. You can help to prevent plaque build-up, tooth decay and the need for fillings by:
- Brushing your teeth twice a day with fluoride toothpaste
- Flossing before brushing once a day
- Cutting down on sugar that feeds plaque
- Drinking plenty of water (especially tap water containing fluoride that helps to protect teeth)
- Seeing a dentist once or twice a year for a check-up and clean
Metal amalgam removal in Sydney
Rathore M, Singh A, Pant VA. The dental amalgam toxicity fear: a myth or actuality. Toxicol Int. 2012;19(2):81–88. doi:10.4103/0971-6580.97191
Australian Dental Association. Policy Statement 6.18 – Safety of Dental Amalgam [Online] 2017 [Accessed April 2021] Available from: https://www.ada.org.au/Dental-Professionals/Policies/Dental-Practice/6-18-Safety-of-Dental-Amalgam/ADAPolicies_6-18_SafetyofDentalAmalgam_V1.aspx
Healthdirect. Dental fillings [Online] 2019 [Accessed April 2021] Available from: https://www.healthdirect.gov.au/dental-fillings