What is dental amalgam?
(commonly known as ‘silver fillings’) is used to repair decayed
or broken teeth. It has been in use since the early 1800s
and is generally made up of mercury, silver and tin, with
small amounts of copper and zinc.
The use of amalgam for dental work is declining as dental
health improves and reasonably priced alternative materials
become more widely available.
is the issue?
years, concerns have been raised about dental amalgam because
it contains mercury, a substance that at high levels can be
harmful to human health. Media stories and websites have fuelled
these concerns, but they are sometimes based on inaccurate
information. Repeated worldwide reviews of the scientific
evidence have been unable to link the use of dental amalgam
directly with ill health.
mercury from fillings enter the body?
amounts of mercury are released from the surface of dental
amalgam fillings, mainly as mercury vapour. Grinding teeth,
chewing and tooth-brushing all increase the amount of mercury
released. Some of the vapour is breathed out, but some is
breathed in, or dissolves in saliva and is swallowed. In this
way, some mercury can reach the rest of the body and accumulate
in certain organs, particularly the kidneys.
mercury levels involved are very low, so the amount of mercury
absorbed into the body is very small. The amount of mercury
released from fillings is greatest when fillings are being
inserted or removed.
are the health effects?
of mercury are harmful to human health. These levels of exposure
mainly affect the kidneys and the nervous system, producing
signs such as mood swings, memory loss and development of
tremors. The phrase ‘mad as a hatter’ came about because the
hat makers of the 19th century were exposed to high levels
of mercury, which was rubbed onto cloth as a preservative.
In rare cases, a person may be allergic to mercury.
dental amalgam likely to affect me?
people have different tolerances to chemicals in the environment;
however, in the opinion of the World Health Organization the
levels of mercury exposure from amalgam fillings do not affect
general health. Millions of amalgam fillings have been placed
since mercury was first used in the early 19th century.
There is no
reliable evidence that people with such fillings have a greater
risk of ill health than people without amalgam. A very small
number of people may experience local side effects due to
an allergic reaction to dental amalgam, causing irritation
in the tissues surrounding the tooth. However these local
effects appear quickly, and can be recognised and treated.
the issue in perspective
Of the mercury
found in the body, less is likely to have come from dental
amalgam than from other sources. Mercury is present at low
levels in our environment as a naturally occurring element
in air, water and food.
food, particularly in fish, is often in a form that can be
easily absorbed by the body (in contrast to the mercury in
The use of dental amalgam has been recommended to be phased
out in Scandinavia and other parts of Europe, once satisfactory
alternative materials become available.
for this was mainly concern over the release of toxic substances
into the environment rather than concern about potential health
effects for the individual
should amalgam be avoided?
placement of new amalgam fillings or removal of old ones is
not recommended, because the level of mercury in the blood
tends to rise briefly in these situations. The mercury can
cross the placenta and enter the bloodstream of the fetus.
There is no scientific evidence of any link between amalgam
and birth defects or stillbirths. However, current thinking
is that it is better to avoid dental work involving amalgam
when possible during pregnancy, unless the effects of avoiding
treatment could cause greater problems, eg the loss of a natural
are breastfeeding should also avoid having amalgam fillings
inserted or removed, because mercury can be passed to the
baby through breast milk. Of course, there are some situations
during pregnancy or breastfeeding where dental work using
amalgam might be necessary, and there is no scientific
evidence that this will cause harm.
now generally avoided for filling children’s teeth. Growing
children tend to be more sensitive to the effects of exposure
to any chemical substance in their environment. Several of
the new tooth-coloured materials are suitable for use where
cavities are small, as they often are in children. Also, it
is sometimes possible to treat a child’s tooth with a preventive
filling that stops existing decay and prevents further decay,
rather than inserting an amalgam filling.
levels of mercury exposure may affect the kidneys, people
with kidney disease may be more concerned than others to minimise
exposure to mercury.
amalgam fillings be replaced?
There is no
support in the scientific literature for the idea that the
mercury released from amalgam fillings is harmful to an individual’s
health. The World Health Organization produced the following
statement on dental amalgam in 1999:
There is no
scientific evidence showing that general symptoms are relieved
by the removal of amalgam restorations.
In fact, there
are disadvantages to having amalgam fillings replaced — replacement
can be expensive; it almost always causes more of the natural
tooth to be lost; and, mercury levels in the body rise immediately
after amalgam fillings are replaced due to the manipulation
of the amalgam. Alternative materials such as gold, ceramics
or composite resins (plastics) require more of the tooth to
be removed. Composite resins are also more prone to wear so
they usually do not last as long as amalgam fillings.
If you decide
to have amalgam fillings replaced, your exposure to mercury
can be reduced by using a rubber shielding device called a
‘dental dam’ and having extra suction during the removal.
Dentists can also cut away, rather than drill out the amalgam
filling, to help reduce exposure to mercury. Check that your
dentist uses these measures before undertaking dental amalgam
to replace amalgam fillings is an individual one, and you
should make it in consultation with your dentist. If you feel
that you need further information after reading this information
and talking to your dentist, it may be a good idea to seek
is better than cure
• Brush your teeth and gums twice a day with a fluoride toothpaste.
• Floss between teeth every day with waxed dental floss.
• Visit your dentist regularly.
• Limit the number of sugary or sweetened foods and drinks.
and disadvantages of dental amalgam,
In many respects,
amalgam is an excellent filling material, because:
• It is reasonably
• It is highly durable — apart from gold and some of the new
ceramics, amalgam is the best material for teeth that are
subject to considerable force during chewing and therefore
a lot of wear
(such as molars). Any replacement weakens the natural tooth
that is being filled, so the longer a filling lasts, the better.
• It is pliable
when first mixed and can be moulded into a tooth cavity —
reducing the amount of natural tooth that needs to be removed
in order to fit the filling. Because of these advantages,
dental amalgam is still the most favoured material for repairing
decay in most premolar and molar teeth.
The main disadvantages
of dental amalgam are:
• It is not
• The mercury
in dental amalgam can pollute the environment when dental
wastes are disposed of incorrectly, or bodies are cremated.
• For precautionary
reasons, its use is best avoided in some people, as explained
in the brochure. Although there is no scientific evidence
for harm, it could be regarded as a disadvantage that mercury
is released from amalgam fillings into the body in very small