Dentists in Singapore will gradually reduce the use of mercury in tooth fillings, but will not eliminate it entirely.
While tooth-coloured materials such as composite resin, porcelain (ceramic) and glass ionomer are the preferred option in most cases, several dentists told The Straits Times that mercury-based dental amalgams — used for more than 175 years — remain the most suitable choice for deep cavities where maintaining a dry field is challenging.
These amalgams, which contain around 50% mercury, are less sensitive to moisture during placement, they explained.
In Nov, the World Health Organisation (WHO) called for a global phase-out of mercury-based dental amalgams by 2034, a move intended to transform dental practice worldwide. Mercury is listed by WHO as one of the top 10 chemicals of major public health concern, described as “toxic to human health.” Phasing out amalgam fillings also helps reduce environmental mercury emissions.
The Singapore Dental Association (SDA) stated that while the country’s dental community supports the global direction, it is reducing amalgam use carefully to ensure patients continue to receive safe, effective and appropriate care. Amalgam is now reserved for a small number of cases where it is clinically indicated.
Dr Alethea Foong, prosthodontics consultant at the department of restorative dentistry, National Dental Centre Singapore, said material selection for fillings depends on clinical factors including tooth location, cavity size, caries risk and patient needs.
“Amalgam is used to restore large, load-bearing back teeth where durability and longevity are prioritised over aesthetics. It is also preferred when moisture control is difficult, for patients with high caries risk or poor oral hygiene, and where cost-effectiveness and reduced chair time are important,” she explained.
Resin-based composites are the most widely used alternative, particularly for back teeth, due to their aesthetic advantages and adequate mechanical properties.
“However, composites carry a higher risk of restoration failure and secondary caries compared with amalgam. They also require strict moisture control and are more technique-sensitive,” Dr Foong added.
Ultimately, the choice between mercury-based amalgam and alternative materials depends on the dentist’s evaluation of the patient’s oral condition and the suitability of amalgam for the specific case. For example, teeth subjected to high biting forces may benefit from the strength of amalgam, while factors such as allergies or other health conditions are also considered.
Existing amalgam fillings in the population, including older patients, are generally considered stable and durable if properly maintained, though there is no local data on their prevalence, a spokesperson from the faculty of dentistry at the National University of Singapore (NUS) said. Dental amalgams release small amounts of mercury vapour, which is unlikely to pose health risks.
Mercury vapour and ions are released through continuous evaporation from the surface, corrosion, and mechanical wear caused by chewing, brushing, and consumption of hot foods and beverages. Small amounts may also be emitted during placement, polishing or removal. International reviews confirm that exposure from intact fillings is generally low and below established safety thresholds.
Dr Foong explained: “Daily mercury vapour exposure from amalgam fillings is estimated at 0.2-0.4μg per tooth surface, or 0.5-1μg per tooth, equivalent to a speck of dust.”
Large randomised trials in children and epidemiological studies in adults show no significant differences in neuropsychological function, IQ or kidney outcomes over five years between those with amalgam and composite restorations, despite higher urinary mercury levels in the amalgam groups.
“The amount of mercury released is proportional to the number and surface area of amalgam restorations, especially on biting surfaces. This exposure remains well below occupational thresholds associated with toxicity, which are 20-50μg per litre of urinary mercury,” she said.
Source: The Straits Times
