The dentist has found a cavity and asked a simple question: tooth coloured or silver? It sounds like a choice about looks, but it is also a choice about how long the filling lasts, how much tooth has to be drilled, and what the filling is made of. The short answer on composite vs amalgam fillings: composite (tooth-coloured filling) is the usual choice today for most teeth, while amalgam (silver filling) still has a place for large fillings in back teeth that take heavy chewing.
Neither is wrong. Amalgam has been used for more than 150 years and has a long track record for strength. Composite has caught up a great deal in the last two decades and now bonds to the tooth, needs less drilling and is invisible once placed.
This guide compares the two on the things that matter to you, so that when the dentist asks the question, you already know what you want and why.
What are composite and amalgam fillings made of?
Amalgam (silver filling) is a mix of metals. Roughly half is mercury, and the rest is a powder of silver, tin and copper. When mixed, the paste is packed into the cavity, where it hardens within minutes and reaches full strength in about a day. It has been used for more than 150 years and its strength in back teeth is well proven.
Composite (tooth-coloured filling) is a resin, a type of plastic, filled with fine glass or ceramic particles for strength. It comes as a soft paste in many shades, so the dentist matches it to the colour of your tooth. It is placed in thin layers, each hardened with a blue light in a few seconds, and a bonding agent glues it to the tooth so the dentist removes only the decayed part.
Amalgam does not stick to tooth. It stays in place because the cavity is shaped with a wider base than opening, like a keyhole, so the filling is locked in. That means the dentist has to remove some healthy tooth to make the shape.
Glass ionomer is a third, softer tooth-coloured material that releases fluoride and is used for milk teeth and fillings near the gum line. For most adult cavities, though, the real choice is between composite and amalgam.
Which filling lasts longer, composite or amalgam?
On composite vs amalgam fillings and lifespan, the honest answer is that amalgam still has the edge in back teeth, though the gap has narrowed. A Cochrane review of trials comparing the two in adult back teeth found that composite fillings may fail more often than amalgam and may be more likely to develop new decay around the edges, though the evidence was of low certainty (Worthington et al., 2021).
In practice, a well-placed amalgam in a molar commonly lasts 10 to 15 years or more. A well-placed composite in the same tooth typically lasts 7 to 10 years, sometimes longer. The size of the filling matters more than the material. A small composite in a premolar may outlast a huge amalgam in a molar that is cracking around it.
Why the difference? Amalgam is very hard and does not wear or shrink. Composite shrinks slightly as it sets, which can open a tiny gap at the edge if the layering is not done carefully. Composite also needs a dry tooth during placement, and a back molar with saliva pooling around it is a difficult place to keep dry.
That is why technique matters so much with composite. Rubber dam isolation, careful layering and proper light curing make a large difference to how long it lasts.
Results vary from person to person; our dentists assess this for you at the consultation. Chewing habits, teeth grinding at night (bruxism), sugar intake and brushing all affect how long any filling lasts.
Which one looks better and needs less drilling?
Composite is matched to the shade of your tooth and is invisible from arm’s length. Amalgam darkens to grey or black over the years. For any tooth that shows when you smile, composite is the clear choice.
The drilling difference is less visible but just as important. Because composite bonds to the tooth, the dentist removes only decayed tissue and keeps the healthy walls of the tooth. Because amalgam needs a locking shape, more healthy tooth comes out. A tooth with less drilling is a stronger tooth, and it keeps more of its original structure for any future work.
Because composite is glued to the walls of the cavity, it holds them together under chewing pressure. Amalgam does not grip the walls, and a tooth with a large old amalgam can crack around it, which is a common reason such teeth eventually need a crown (cap).
A composite can also be repaired by adding fresh material to a chipped edge, while a failed amalgam is usually replaced whole, which means more drilling each time.
Composite does take longer to place, typically 30 to 45 minutes for a molar compared with 20 to 30 for an amalgam, and it costs more because of the time, skill and materials involved. You can eat on a composite once the numbness wears off, while an amalgam needs about 24 hours to reach full strength. The dental filling cost page explains what affects the price of a filling.
Is the mercury in silver fillings safe?
Amalgam contains mercury, and mercury in some forms is toxic. In amalgam, the mercury is bound into a solid alloy with silver, tin and copper. Very small amounts of mercury vapour are released during chewing.
The United States FDA states that amalgam is safe for the majority of people, while advising that certain groups may wish to avoid it where possible: pregnant and breastfeeding women, women planning pregnancy, children under six, people with kidney problems, people with existing nerve conditions, and anyone with a known sensitivity to mercury (FDA, 2020).
Separately, the Minamata Convention on Mercury, an international treaty that India has joined, calls for a gradual phase-down of amalgam use to reduce mercury in the environment, not because of a danger to patients but because of mercury released in waste water and cremation (UNEP, 2013). This is why many clinics now use amalgam less and composite more.
Removing sound amalgam fillings to reduce mercury exposure is not recommended. Drilling out an amalgam releases more vapour than leaving it in place. If an old silver filling is intact, has no decay around it and does not hurt, the usual advice is to leave it alone and replace it only when it fails.
Composite contains resins that some people have questioned, but there is no evidence of harm from properly set composite fillings. If you have a known allergy to any dental material, tell your dentist before the filling is chosen.
If you have a cavity and are unsure which filling suits it, a check at Apollo Dental Vadavalli takes under 30 minutes and you can book for the same day on +91 88705 04111.
Which filling is right for a front tooth, a molar or a child?
The right material depends on where the cavity is, how big it is, and who the patient is.
Front teeth and premolars
Composite, almost always. These teeth show when you talk and the chewing forces are lower.
Back molars with a small or medium cavity
Composite is the usual choice now, especially when the cavity can be kept dry during placement. Ask about rubber dam isolation for back teeth, as it makes a real difference to how long the composite lasts.
Back molars with a large cavity
This is where amalgam still earns its place, particularly in a lower molar that is hard to keep dry, in a person who grinds their teeth, or where cost is a concern. If the cavity is very large, the dentist may suggest a crown (cap) instead, since neither filling material does well with little tooth left to support it.
Children’s milk teeth
Glass ionomer or composite are preferred. Glass ionomer releases fluoride and is quick to place, which matters with a wriggly child. Amalgam is used much less in children now, in line with the FDA and Minamata guidance.
Fillings near the gum line
These are hard to keep dry and are under less chewing force, so glass ionomer or a composite designed for the purpose is often used. A cavity here is often linked to gum recession and sensitivity, and the sensitive teeth page explains that connection.
Should you replace your old silver fillings with composite?
Many adults have amalgam fillings from school days and wonder whether to swap them for tooth-coloured ones. The answer depends on why.
If the reason is looks, and the filling is in a tooth that shows, replacing it with composite is reasonable. The dentist will first check that the tooth underneath is healthy and has enough structure for a bonded filling. Replacing a filling always means drilling a little more tooth, so it is not a step to take lightly.
If the reason is health worry, see the section above. Most dentists will not recommend removing sound amalgam for this reason alone.
Signs an old filling does need replacing
- A dark line or shadow at the edge of the filling, which may mean new decay underneath
- A chipped or cracked edge you can feel with your tongue
- Sensitivity to hot, cold or sweet that has started recently around the tooth
- Pain when biting on that tooth
- A piece of the filling that has come out
- Food that always packs between that tooth and the next
Any of these means the filling has stopped sealing the tooth. A new filling, or a crown if the tooth is weak, is needed. If the tooth is aching rather than just sensitive, the tooth pain guide explains what the different types of pain mean. A yearly check-up with an RVG digital X-ray catches a failing filling before it hurts.
When should you see a dentist about a filling?
See a dentist as soon as you notice a hole you can feel with your tongue, a dark spot on a tooth, food packing in one place, or sensitivity to sweet, hot or cold that keeps returning. A cavity caught early needs a small filling. Left for a year, it may need a large one, a crown, or a root canal.
The choice between composite and amalgam is made at the visit, after the dentist has looked at the tooth with an intraoral camera and taken an RVG X-ray to see how deep the decay goes. A good dentist will explain why one material suits your tooth better, and will respect a preference for tooth-coloured fillings where the tooth allows it.
The dental fillings page covers the full process, from numbing to polishing, the materials used, and how to care for a new filling. Every specialty at the clinic has doctors with more than 5 years of experience, autoclave sterilisation with single-use items is standard, and the clinic is open every day from 10 AM to 8 PM with same-day appointments.
Whichever material you choose, the filling that lasts longest is the one placed early, in a small cavity, with good technique, and looked after with twice-daily brushing and a yearly check-up.
Frequently asked questions
Which is better, composite or amalgam filling?
It depends on the tooth. Composite (tooth-coloured) is the usual choice for front teeth, premolars and small to medium cavities in molars, because it looks natural, bonds to the tooth and needs less drilling. Amalgam (silver) still suits large fillings in back molars that are hard to keep dry or take heavy chewing.
How long do composite fillings last compared with amalgam?
A well-placed amalgam in a molar commonly lasts 10 to 15 years or more. A composite in the same tooth typically lasts 7 to 10 years, often longer when placed in a dry field with careful layering. A Cochrane review found composite may fail somewhat more often in back teeth. Size of the filling and chewing habits matter as much as material.
Are silver fillings safe because of the mercury?
The FDA and other health bodies consider amalgam safe for most people, as the mercury is bound into a solid alloy. As a precaution, the FDA advises that pregnant and breastfeeding women, children under six and people with kidney or nerve conditions may prefer other materials. Removing intact amalgam to reduce exposure is not recommended.
Should I replace my old silver fillings with white ones?
Only if they are failing or you want a better look in a tooth that shows. Replacing a filling means drilling more tooth, so intact amalgam with no decay around it is usually left alone. Signs a filling needs replacing include a dark edge, a chip, new sensitivity, pain on biting or food packing.
Can I eat right after a filling?
After a composite filling, yes, once the numbness wears off, because the material is fully hard as soon as it is light-cured. After an amalgam filling, chew on the other side for about 24 hours while it reaches full strength. With either, avoid very hot food until you can feel your lip and tongue again.
Why does my tooth feel sensitive after a new filling?
Mild sensitivity to cold or biting for a few days to two weeks is common with both materials, especially deep fillings close to the nerve. It usually fades as the tooth settles. If sensitivity is severe, lasts more than a month, or there is pain on biting, the filling may be slightly high or the nerve may be inflamed, and a review is needed.
If you have a cavity and want an honest answer on whether a tooth-coloured or silver filling suits that tooth, call +91 88705 04111 to book a same-day check at Apollo Dental Vadavalli.
This article is general information and not a substitute for a dental consultation. Results vary from person to person.