Tooth filling materials Dental amalgams & alternative materials
5. What are the possible health effects of alternative tooth filling materials?
- 5.1 How toxic are the different components of alternative materials ?
- 5.2 What are the possible negative effects on health associated with alternative materials ?
5.1 How toxic are the different components of alternative materials ?
Composites are typically hardened using light
Tooth fillings are increasingly done using alternative
materials such as
composites, glass ionomer
cements, compomers, giomers and
sealants. Some of these
alternative materials are chemically very complex and not
necessarily free from concerns about health effects.
contain many different components, including a resin
base and ceramic filler. The product is supplied as a paste that
is filled into the tooth
cavity. The resin is then typically hardened using
visible blue light.
Used since the 1970s, glass ionomer cements
are formed when glass powder and a type of
polymer react with each
other. The reaction hardens the material and attaches it firmly
to the tooth.
Other materials, such as compomers have been introduced since
the 1990s to combine specific advantages of
are pastes or liquids that are used to seal small
surface defects such as pits and fissures in permanent teeth to
Clearly these alternative restorative materials are complex
chemically, with different components, properties, and setting
reaction mechanisms. They can thus interact with the patient’s
tissues in many
Substances of particular concern are:
- ions leaching from different types of glass used as
filling material ;
- acids used to etch teeth and set the fillings; and
- the small organic
molecules (monomers) that react to form polymers, the basis
of many alternative materials. Some of the monomers may not
have reacted during placement and therefore low levels may
remain in the set filling.
Although there is very limited data available, some monomers
are known to be toxic to
cells and others
cause allergic reactions. Some of these substances are irritants
when used by themselves. The effects they cause vary depending
on the substance and on the type of body tissue with which they
come into contact. In addition, many alternative materials
release ions. In vitro
studies have shown that some of these releases (such as
beneficial or too low to be harmful, while others (such as
copper, aluminium and iron) may reach concentrations capable of
As restorations degrade or erode over time, they release
substances that can be
absorbed through the skin,
the gut, and through the lungs. It is very difficult to
determine exposure to the different substances because there are
no obvious indicators that could be measured and because the
volumes of the materials used are very small and these materials
set quickly. In addition, the starting materials change
chemically when they set and it is likely that their toxicity
Although laboratory studies show that some of these leached
substances are harmful to
cells, the concentrations
emitted by restorations during placement and thereafter are
usually too small to be considered a significant health problem.
When some alternative materials set, they shrink and leave a
gap between the tooth and the restoration. Improvements in
techniques and products have led to smaller gaps but some
microorganisms can fit underneath restorations and cause harmful
effects to the dental
Dental workers are exposed to some of the components of
alternative materials when they prepare and place fillings.
There is very limited information on the level of exposure to
components of alternative materials present in the air.
5.2 What are the possible negative effects on health associated with alternative materials ?
Alternative tooth-coloured materials contain a complex mixture
of chemicals that react with each other inside the
tooth cavity and
also interact with the surrounding
tissues. Some of the
components of these materials are highly
toxic to gum and
cells grown in the
laboratory and others can cause
these properties may not necessarily lead to negative health
effects in dental patients.
Many of the components of alternative materials and their
degradation products can cause local allergic reactions in
dental patients (mouth) and workers (hands). Such allergic
reactions can also affect other parts of the body such as the
face, arms or legs. Allergic reactions are more common in dental
workers than in patients, probably because the exposure is
highest when handling resin-based restorative materials.
Wearing gloves when handling these materials does not prevent
very small molecules released from alternative materials to
reach the skin, and these molecules may induce reactions in
persons sensitive to them. Such reactions can be avoided by not
touching these substances even when wearing gloves.
Many alternative materials are hardened by shining visible
blue light onto them. The powerful light sources now used for
this purpose may constitute an additional risk for adverse
effects, both to patients and dental personnel. Eye protection
is extremely important. Though these dental curing units are
generally considered safe certain people should avoid their use,
for instance individuals with certain cataract and other
eyesight problems, patients sensitive to light or those on
photosensitising medication. Certain electrical equipment used
for dental curing may pose a risk to people with electrical
implants such as pacemakers.
The full chemical specification of alternative restorative
materials is not always divulged and it may be difficult to
ascertain exactly what they contain. In the absence of data, it
may not be possible to provide a scientifically sound statement
on the safety of individual products. There are very limited
scientific data available concerning exposure of patients and
dental personnel to these substances.
Nevertheless, these alternative materials have now been in
clinical use for well over thirty years, and this use has
revealed little evidence of clinically significant adverse
events. The commercially available materials have either changed
substantially or been improved considerably during this time,
with reduced exposure to harmful components through improved