In the light of new developments and studies on dental amalgam a request was submitted by
the Commission to update the SCENIHR opinion produced in 2008 on the safety and
performance of both dental amalgam and possible alternatives, such as resin-based
composites, glass ionomer cements, ceramics and gold alloys.
This updated 2015 Opinion evaluates the scientific evidence on the potential association
between amalgam and possible alternatives and adverse health effects, such as allergies and
neurological disorders.
The SCENIHR recognises that dental amalgam is an effective restorative material and is a
material of choice for specific restorations.
Currently in the EU, there is a shift away from the use of dental amalgam in oral health care
towards an increased use of alternative materials. Because dental amalgam is neither toothcoloured
nor adhesive to remaining tooth tissues, alternative tooth-coloured filling materials
have become increasingly used. The change is indicated by trends in education on dental
treatment towards an increased use of alternative materials instead of amalgam. This
reduction is in line with concern about the use of mercury, the metallic element used in dental
amalgam and the general aim to reduce mercury use within the European Union.
The exposure of the general population to mercury is mainly due to fish consumption (organic
mercury, methyl mercury) and dental amalgam (elemental mercury, inorganic mercury). The
present Opinion reviews only the toxicology of elemental and inorganic mercury being relevant
to amalgam safety considerations.
Local adverse effects in the oral cavity are occasionally seen with dental amalgam fillings,
including allergic reactions and an association with clinical features characteristic of lichen
planus, but the incidence is low (< 0.3% for all dental materials in general) and usually readily
managed. Regarding systemic effects, elemental mercury is a well-documented neurotoxicant,
especially during early brain development. Inorganic mercury also constitutes a hazard to
kidney function. In some scientific reports the presence of dental amalgam has been suggested
to be associated with a variety of systemic adverse effects, particularly developmental
neurotoxicity as well as neurological and psychological or psychiatric diseases. However, the
evidence for such effects due to dental amalgam is weak.
The most recent in vitro evidence provides new insight into the effects of mercury on
developing neural brain cells at concentrations similar to those accumulated in human brain
and found in post mortem specimen. The effects of genetic polymorphism concerning mercury
kinetics may influence the degree of individual susceptibility with regard to mercury internal
exposure and consequently toxicity. This may raise some concern for possible effects on the
brain of mercury originating from dental amalgam. However, so far such effects have not been
documented in humans, although some evidence on alteration of mercury dynamics have been
reported.
Placement and removal of dental amalgam fillings results in transient short-time exposure to
the patients compared to leaving the amalgam intact. There is no general justification for
unnecessarily removing clinically satisfactory amalgam restorations, except in those patients
diagnosed as having allergic reactions to one of the amalgam constituents. However, as with
any other medical or pharmaceutical intervention, caution should be exercised when
considering the placement of any dental restorative material in pregnant women.
The mercury release during placement and removal also results in exposure of dental
personnel. Recent studies do not indicate that dental personnel in general, despite somewhat
higher exposures than patients, suffer from adverse effects that could be attributed to mercury
exposure due to dental amalgam. However, exposure of both patients and dental personnel
could be minimised by the use of appropriate clinical techniques.
The alternative materials also have clinical limitations and toxicological hazards. They contain a
variety of organic and inorganic substances and may undergo chemical reactions within the
tooth cavity and adjacent soft tissues during placement. The SCENIHR Opinion “The safety of
the use of bisphenol A in medical devices” (2015) concluded that release of BPA from some
The safety of dental amalgam and alternative dental restoration materials for patients and users
5
dental materials was associated with only negligible health risks. A similar detailed risk
assessment has not been performed for other compounds released from other alternative
dental materials. Some of the monomers used are cytotoxic to pulp and gingival cells in vitro.
There is in vitro evidence that some of these alternatives are also mutagenic although longterm
health consequences are unclear. Allergies to some of these substances have been
reported, both in patients and in dental personnel. However, information on the toxico