Composite vs Amalgam Fillings — A Practical Comparison

Composite is shaded to match the surrounding tooth and is essentially invisible once placed. Amalgam is silver and turns darker over time. For front teeth and visible parts of the mouth, composite is the only realistic option.

Amalgam is highly compressive-strength resistant and historically had a slight edge for very large fillings in heavy-loading back teeth. Modern composites have closed most of that gap for small and medium fillings, and bond-supported designs help spread chewing forces evenly. For very large cavities, an onlay or crown may be more durable than any filling — your dentist will discuss this if it applies.

Composite bonds to the tooth, so the cavity preparation can follow the shape of the decay more closely. Amalgam needs a mechanically retentive shape, which sometimes meant removing more healthy tooth structure than the decay strictly required. This is one of the bigger advantages of composite for smaller fillings.

Both materials can leave a tooth a little sensitive for a few days after placement. Sensitivity to cold is more commonly noticed with composite immediately after the appointment, and it usually settles within one to two weeks. Sensitivity that lingers beyond a few weeks should be reviewed — see our sensitive teeth page.

Both materials can last many years when placed well and looked after. Average lifespans depend heavily on the size of the filling, the location, and how the patient cares for the tooth. We do not quote a fixed number of years because individual results vary widely.

The mercury in amalgam is chemically bound, and a placed amalgam filling is considered safe for use in adults. The Minamata Convention’s phase-down is driven primarily by environmental concerns about mercury at the point of placement, removal, and disposal — and is part of why the dental profession globally is shifting toward composite as a default. We follow current best-practice handling and capture requirements when removing existing amalgam.

Composite fillings generally cost a little more than equivalent-sized amalgam fillings because they take longer to place and require careful moisture control. We provide written quotes with item numbers before treatment so you can compare options.

No, not on that basis alone. Intact amalgam fillings are considered safe for adults. We replace fillings — composite or amalgam — when there is a clinical reason, such as decay around the edge, a crack, or loss of part of the tooth.

Yes. Composite is the standard material we use for fillings in children, and our children’s fillings page covers this in more detail.

For small to medium fillings, modern composites have a comparable lifespan when looked after well. For very large fillings or under heavy grinding loads, your dentist may suggest an onlay or crown for longer-term predictability.

Composite is more technique-sensitive and takes longer to place. Strict moisture control, layered placement, and curing time all add to the chair time.

Yes — composite is routinely used on back teeth in our practice and most others in Australia.

The Minamata Convention’s phase-down focuses on reducing mercury entering the wider environment rather than implying placed fillings are unsafe. As composite has improved and become more reliable, it has become the default material.

It should feel like a natural tooth once placed and adjusted. If something feels "high" when you bite together, let us know — a small adjustment usually settles it within minutes.