The question gets asked at almost every appointment where a filling is needed. The answer isn’t a clean win for either side, and anyone who tells you otherwise is overselling the case.
Here’s a straight comparison of the two, drawing on what we see in clinical practice rather than the marketing brochure version. If you’re due treatment and want to talk through which is right for your specific tooth, we discuss this routinely at filling appointments at the practice.
What Each Material Actually Is
Amalgam is an alloy of mercury (roughly 50%) combined with silver, tin, copper, and small amounts of zinc or other metals. It’s been used in dentistry for over 150 years, which makes it one of the most studied restorative materials in medicine. The mercury binds chemically into the alloy when mixed, and the result is a hard, dense, silver-grey filling.
Composite (the white filling) is a resin-based material with finely ground glass or ceramic particles for strength. It bonds to the tooth chemically, hardens under a blue curing light, and is shade-matched to the surrounding enamel. The technology has improved considerably over the past two decades, and current materials behave very differently from the early generation many older patients remember.
That difference matters more than people realise.
Appearance: No Real Contest
White fillings win this one decisively. A well-placed composite is essentially invisible. Amalgam, for all its functional virtues, looks like dark grey metal in your mouth.
For front teeth, amalgam isn’t really an option anyway. The aesthetic compromise is too obvious. For back teeth, it’s a personal call. Some patients don’t care about the appearance of a molar that nobody sees. Others find the visible silver flash when they laugh genuinely bothering. Both responses are reasonable.
It’s worth knowing that amalgam can also stain the surrounding tooth tissue over time, leaving a faint grey shadow even after the filling is removed.
Longevity: Closer Than You Might Think
This is where the conventional wisdom has shifted. The old line was that amalgam lasts twice as long as composite. The current evidence (much of it summarised on the dental restoration overview at Wikipedia) suggests that gap has narrowed considerably for modern hybrid composites placed under good clinical conditions.
Realistic working figures for a well-placed restoration:
| Material | Typical Lifespan | Best Used For |
|---|---|---|
| Amalgam | 10 to 15 years, often longer | Large cavities on back teeth where moisture control is difficult |
| Composite (white) | 7 to 10 years, sometimes longer | Most cavity sizes and positions, particularly visible teeth |
| Glass ionomer | 3 to 7 years | Children’s teeth, root surface decay, temporary restorations |
| Ceramic inlay or onlay | 10 to 20 years | Large defects where composite would be overstretched |
In our experience, the operator’s technique matters more than the material chosen. A composite placed in a well-isolated, dry field by an experienced clinician will outlast an amalgam rushed in without proper care. The reverse is also true. That’s the part the comparison rarely captures.
Beyond raw lifespan, there’s the question of what happens when a filling reaches the end of its useful life. Amalgam typically needs to be drilled out completely, which removes the original filling and a small amount of surrounding tooth. Composite can sometimes be patched or partially replaced, particularly if the failure is at one margin rather than throughout. Over multiple cycles of replacement across a lifetime, this difference adds up.
One of composite’s strongest practical advantages is the conservation of tooth tissue. Because it bonds chemically to the tooth, the cavity preparation only needs to remove what’s diseased. Amalgam, by contrast, needs an undercut shape to lock mechanically into place, which means cutting away healthy tooth tissue to create that retention.
Over a tooth’s lifetime, this matters. Less drilling means more native enamel and dentine preserved. When that filling eventually needs replacing (and they all do, eventually), there’s more healthy tooth left to work with.
Most modern dentistry leans heavily on this principle. It’s why composite has become the default in most non-NHS settings.
The Mercury Question
Amalgam contains mercury. That fact alone makes some patients uncomfortable, regardless of what the regulators say. The relevant authorities (including the UK government, the WHO, and the FDA) continue to consider amalgam safe for general use, but EU and UK rules now restrict its use in pregnancy, breastfeeding, and in children under fifteen.
Actually, the position is more nuanced than that. The UK has signed the Minamata Convention, which commits to phasing down amalgam use over time. The wider direction is clearly away from it, even if outright prohibition isn’t on the immediate horizon. The official guidance from the UK government sets out the current restrictions.
A small minority of patients report sensitivities or symptoms they attribute to amalgam, though the evidence here is mixed. We’ve had patients ask for amalgam removal on these grounds, and we’ll do it where it’s clinically reasonable, though we don’t promote the procedure as a treatment for general health concerns.
Cost: Where the Picture Inverts
On the NHS in England, both materials sit under Band 2 at £76.60 per course of treatment. There’s no price difference at the point of care, though the rules sometimes restrict white fillings on back teeth to private upgrades.
Privately, white fillings cost more than amalgam, typically meaningfully more. The reason is partly material cost but mostly time: a composite restoration done properly takes longer to place because of the layering and curing protocol.
For some patients, the higher private cost is worth it for the appearance and the conservation of tooth tissue. For others, it isn’t. There’s no universal right answer here.
When Each One Still Makes Sense
Despite the shift toward composite, there are situations where amalgam still has a place:
- Very large cavities on back teeth where the cavity extends below the gum and moisture control is genuinely difficult.
- Patients with high decay rates and limited budgets, where durability per pound spent matters most.
- Cases where a temporary, hard-wearing solution is needed before more definitive treatment.
And situations where composite is clearly the better choice:
- Any visible tooth.
- Small to medium cavities, particularly on premolars.
- Patients who want to avoid mercury for personal reasons.
- Pregnant or breastfeeding patients, and children, where amalgam is restricted.
- Teeth where preserving as much healthy tissue as possible matters most.
For most patients in most situations, composite wins on balance. Not every time. But often enough that it’s now the default.
It’s also worth thinking about what happens at replacement. A composite that fails at one margin can sometimes be repaired without removing the entire restoration, which preserves more tooth. Amalgam typically requires complete removal at the point of failure. Over a lifetime of restorative cycles, this conservation principle compounds.
Composite is more technique-sensitive. A poorly placed composite will fail considerably faster than a well-placed amalgam. The technical demands at chairside are higher: better isolation, more careful etching and bonding, layered placement, proper light-curing. None of this is hard for an experienced operator working unhurriedly. All of it is challenging in a rushed appointment.
The honest reading of the evidence is that the two materials, in skilled hands and appropriate situations, are more similar than the loud advocates on either side will admit. The choice should be made tooth by tooth, not as a blanket policy.
The practical guidance for patients weighing up the choice is straightforward. Ask the dentist which they recommend for the specific tooth, and why. A clinician with a reasoned answer for the particular cavity in front of them is generally giving you better advice than one applying a blanket policy.
Talking It Through Locally
If you’re weighing up which material is right for a specific tooth, the decision is best made face to face after we’ve seen the cavity. Our team at Westcliff Dental Practice will walk you through the options for your situation, including realistic costs and the likely lifespan of each. To book a consultation or ask a question, call us on 01702 344 500.
