The End of Amalgam: Why We No Longer Place Mercury Fillings

For most of the twentieth century, if you had a cavity filled at a dental practice anywhere in the world, the result was a small, dark metallic patch that you carried in your mouth for years — sometimes decades. The material was dental amalgam. The colloquial name was the silver filling. It was, for the better part of 150 years, the standard of care.

Understanding why amalgam was so dominant, why that dominance has waned, and what has replaced it is useful context for any patient who is either considering restoration work or carrying old fillings they have questions about.

What amalgam is

Dental amalgam is not silver, despite the name. It is a blend of metals — primarily mercury, which constitutes approximately 50% of the total composition — alongside silver, tin, and copper. The mercury functions as a binding agent, reacting with the other metals during mixing to produce a pliable alloy that hardens after placement. Once set, the material is dense, mechanically robust, and highly resistant to the compressive forces of biting.

The history of its use is longer than most patients realise. Dental amalgam has a history dating back to ancient China, where similar mixtures of metals were used for dental repairs. Its widespread popularity surged in the 1800s due to its durability, low cost, and ease of application. By the mid-twentieth century, it was the dominant restorative material globally, placed in the posterior teeth of hundreds of millions of patients across every income level and healthcare system.

Why amalgam worked as well as it did

The clinical case for amalgam was, for a long time, genuinely strong — and being honest about that matters when explaining why it persisted for as long as it did.

Amalgam restorations demonstrated superior longevity, with median survival times exceeding 16 years, compared to 11 years for composite restorations. It was also straightforward to place. The material was forgiving in technique, tolerant of moisture during placement, and required no adhesive bonding system. For dentists working in high-volume public health settings, or in environments without sophisticated equipment, these properties were practically significant.

Its popularity as a restorative choice was well-founded due to its strength, longevity, and affordability — particularly for posterior teeth, where it withstood substantial occlusal loading reliably.

There was, however, a clinical cost that was understood from early in amalgam's history but largely managed through the argument that the benefits outweighed the risks.

The mercury question

The defining problem with amalgam is what constitutes approximately half of its composition. Mercury is not an inert filler material. It is considered by the WHO as one of the top ten chemicals of major public health concern, with neurological and behavioural disorders observed after inhalation, ingestion, or dermal exposure. Symptoms include tremors, insomnia, memory loss, neuromuscular effects, headaches, and cognitive and motor dysfunction.

The concern specific to dental amalgam is mercury vapour release. Studies demonstrated that elemental mercury is released from amalgam as a vapour in the human mouth — a continuing, ongoing process whose rate increases significantly during periods of chewing or mechanical stress. The exposure accumulates over years of wearing a filled tooth through ordinary daily function.

The debate around whether this exposure translates into measurable clinical harm in patients has been long and, at points, genuinely contested. What became progressively harder to contest was the effect on the people placing these restorations. Symptoms attributed to mercury frequently appeared in dental personnel working with amalgam. Studies in this population showed elevated mercury levels in urine as well as neurological symptoms, respiratory disorders, and other signs consistent with chronic exposure.

Alongside the human health dimension, the environmental picture was equally difficult to dismiss. The WHO has noted that just 0.6 grams of mercury — the average amount in a single filling — can pollute 100,000 litres of water, rendering it unsafe to drink. Mercury released through crematoria, dental waste streams, and the environment accumulates in ecosystems over time and re-enters the human food chain through fish consumption.

The global response

The international regulatory response has been systematic and is now reaching a decisive point. At the Sixth Conference of Parties to the Minamata Convention on Mercury in November 2025, 153 nations agreed to phase out mercury-containing dental amalgam globally by 2034. While 50 countries, including all 27 EU member states, have already phased out dental amalgam, many others continue to permit its use.

The European Union's position is now unambiguous. Under strict EU rules in force since January 2025, dental amalgam can no longer be used for fillings except in very limited cases where it is deemed strictly necessary by the treating dentist. The United Kingdom completed a full ban reinforced by the same date.

South Africa has not yet legislated a specific ban on amalgam, and some practices continue to use it. However, the trajectory is clear: amalgam is being phased out of the global dental landscape, and the material science that once made it the only practical option for posterior restorations no longer applies.

What has replaced it

The argument for amalgam was always strongest when the alternatives were weakest. The composite resins available in the 1970s and 1980s were not clinically suitable for high-load posterior teeth — they wore too quickly, absorbed moisture, and shrank during polymerisation in ways that compromised the seal between filling and tooth. Amalgam's longevity advantage in that environment was real.

That gap has closed substantially. Modern composite formulations — particularly nanohybrid and nanofill resins — have closed the durability gap significantly, and composite now accounts for over 70% of all direct restorations placed in the United States. The durability gap that once justified amalgam's dominance has largely narrowed.

The clinical advantages of tooth-coloured composite over amalgam are now material across several dimensions.

Composite bonds directly to tooth structure through an adhesive process. This means less healthy tooth structure needs to be removed compared with amalgam fillings, which required undercuts to achieve mechanical retention. The principle of minimally invasive dentistry — preserving as much natural tooth as possible — is architecturally incompatible with traditional amalgam placement, which demanded the removal of sound tooth tissue to create a mechanically retentive cavity shape.

Because composite resin is bonded to the tooth, the dentist only needs to remove the decayed portion. This minimally invasive approach preserves as much healthy tooth structure as possible, and the bonding process itself can help strengthen and reinforce the remaining tooth, making it more resistant to fracture.

Composite fillings are also metal-free and do not expand or contract as much as amalgam, reducing the risk of tooth cracks or sensitivity. Amalgam's thermal expansion and contraction over years of temperature cycling created micro-fractures in the surrounding enamel — a well-recognised clinical consequence that modern materials do not produce to the same extent.

Beyond direct composite restoration, ceramic and porcelain inlays and onlays now offer an indirect restorative option — fabricated from a digital scan and precision-milled — that exceeds the durability and aesthetics of either amalgam or direct composite for larger restorations.

What patients with existing amalgam restorations should know

Patients who carry amalgam fillings placed years or decades ago are a common presentation at ADI. The question of whether to replace them is one that requires individual clinical assessment rather than a blanket answer.

Intact amalgam restorations that show no signs of marginal breakdown, secondary caries, or tooth cracking should not be replaced without clinical indication. The act of removing an amalgam restoration releases a higher concentration of mercury vapour than the filling produces passively over years of wear, and this process should be managed carefully using a specific removal protocol when clinically indicated. Elective replacement purely on aesthetic grounds, while understandable, is a decision that should be made in consultation with the treating dentist, with the benefits and exposure considerations clearly understood.

Where amalgam restorations have failed — through fracture, secondary caries, or marginal leakage — replacement with a tooth-coloured composite or ceramic alternative is the clear clinical choice. The same applies where restorations adjacent to planned aesthetic work would compromise the overall result.

The broader picture

Amalgam's history in dentistry is not a story of recklessness. It is a story of a material that genuinely served its purpose, under the constraints of the technology and evidence available at the time, until better alternatives emerged and the cumulative evidence against it became impossible to set aside.

The shift away from amalgam reflects something consistent with how dentistry is evolving broadly: toward materials that work with tooth structure rather than against it, toward interventions that are as conservative as the clinical situation permits, and toward a standard of care that takes the whole patient — not just the cavity — into account.

At ADI, amalgam has no place in our restorations. The materials available today are more precise, more conservative, more aesthetically credible, and free of the concerns that have accumulated around mercury for the better part of a century.