When your dentist says you have a cavity, one of the first decisions is what goes in — composite or amalgam. Understanding composite vs amalgam fillings, including what each is made of, how long it lasts, and what it costs, can help you ask better questions before you sit in the chair.

Understanding Composite vs Amalgam Fillings

Amalgam is the silver-colored filling material that has been used in dentistry for more than 150 years. It is a metal alloy — a mixture of metals — made primarily from mercury, silver, tin, and copper. The mercury binds the other components together and makes the material dense and easy to shape during placement. Dental amalgam has been studied extensively and is considered safe for most adults by major health organizations. That said, the FDA updated its guidance in 2024 to recommend that certain groups avoid amalgam where alternatives are suitable — including pregnant individuals, children under 15, and people with kidney conditions. Ask your dentist if any of these apply to you.

Composite is a tooth-colored material made from a blend of plastic resin and fine glass or ceramic particles. It bonds directly to the tooth surface, which means your dentist can often remove less healthy tooth structure than amalgam requires. Because composite matches your natural tooth color, it is the standard choice for any tooth that is visible when you smile.

Both materials are used to restore teeth damaged by decay (commonly called a cavity), a small crack, or surface wear.

How Each Material Holds Up Over Time

Neither material is universally better. Each has real strengths and genuine limitations.

Amalgam

• Extremely durable — fillings commonly last 10 to 15 years or longer with consistent oral hygiene
• Less sensitive to moisture during placement, making it reliable for hard-to-reach back teeth (molars and premolars)
• Generally faster and simpler to place in a single appointment
• Silver-gray in color — noticeable in back teeth when the mouth opens wide
• Over time, some amalgam fillings cause minor tooth discoloration; the metal also expands and contracts with temperature changes, which can stress the surrounding tooth structure

Composite

• Blends with your natural tooth color for a discreet result
• Bonds directly to tooth structure, often preserving more of the original healthy tooth
• Can also repair chips and minor surface damage, not just cavities
• Does not contain mercury — relevant to patients who prefer to avoid it
• Can wear faster under heavy chewing pressure, particularly in large back-tooth cavities, and may need replacement sooner than amalgam in those cases

For front teeth, composite is almost always the right choice — the aesthetics make amalgam impractical there. For molars under heavy bite pressure, your dentist weighs the size of the cavity and how hard you typically chew. A very large cavity sometimes calls for an inlay, onlay, or crown — restorations made in a dental lab that cover more of the tooth than either filling material can handle on its own.

Cost, Insurance, and What to Expect at the Front Desk

Insurance coverage is among the most common patient questions before a filling appointment. Most dental plans cover amalgam for back teeth at the standard benefit rate. For composite fillings in those same teeth, many insurers cover only up to the amalgam allowance — meaning you may pay the difference out of pocket if you prefer tooth-colored material for a back molar. Plans vary significantly, so ask your dental office to verify your specific benefits before the appointment.

Without insurance, amalgam fillings are generally less expensive per tooth. Composite costs more in both materials and chair time, because the bonding process requires careful moisture control and the material is built up in thin layers.

Many dental practices now use AI charting platforms like Rebrief to document treatment decisions clearly — including the clinical reasoning behind material selection. That documentation also supports accurate insurance submissions, which can reduce delays and denials.

Questions to Ask Your Dentist Before Your Appointment

These questions can help you get answers specific to your tooth and situation:

• Which tooth needs a filling, and is it visible when I smile or speak?
• How large is the cavity — is a filling the right restoration, or would an inlay or crown hold up better?
• Does my insurance cover composite for this tooth, and what would my out-of-pocket cost be?
• How long would you expect each material to last given where the tooth sits and how I bite?
• Are there any health reasons I should consider avoiding amalgam?

Tooth location, cavity size, existing restorations nearby, bite force, and your personal health history all shape what your dentist recommends. The right filling for one patient may not be the right choice for another — which is exactly why that conversation matters.

If you want to look up dental terms before your visit, the Rebrief dental glossary explains common vocabulary in plain language. And when you sit down with your dentist, ask them to walk you through the options specific to your tooth — that conversation is the most useful step you can take before any treatment begins.