Choosing the Right Filling for Your Tooth
Your dentist can repair a cavity with more than one material. They differ in colour, in how long they last, and in how much healthy tooth they need removed. The best choice depends on which tooth needs the repair and how big the cavity is.
This page compares the options side by side. For how a filling is placed and the signs you need one, read our guide to tooth fillings.
Tooth-Coloured Fillings or Silver Fillings?
This is the choice most patients ask about. Tooth-coloured fillings (composite) are bonded resin that matches your enamel. Silver fillings (amalgam) are a hard metal mixture.
Composite is now the usual choice at our Johannesburg practices. It bonds to the tooth, so your dentist removes less healthy structure. Amalgam needs a deeper cut to lock it in place.
Amalgam still has one advantage. It stands up to heavy chewing force better than composite. That is why it lasted so well in large back-tooth repairs.
Filling Materials Compared
| Material | Colour | Best suited to | Wear resistance |
|---|---|---|---|
| Composite (white) | Matches your tooth | Front teeth, small to medium cavities | Good |
| Glass ionomer | Close to tooth colour | Children, baby teeth, gum-line cavities | Lower |
| Amalgam (silver) | Dark metal | Large back-tooth cavities | Very high |
| Ceramic or porcelain | Matches your tooth | Large cavities needing an inlay or onlay | Very high |
No filling lasts forever. Size, position and your own habits matter more than the material on its own. A small composite in a front tooth often outlives a large one in a molar.
Composite (tooth-coloured)
Pick composite when appearance matters and the cavity is small to medium. It sets in one visit and bonds directly to the tooth. Composite wears faster than metal or ceramic under heavy grinding.
Glass ionomer
Pick glass ionomer for children, for baby teeth, and for cavities near the gum line. It releases fluoride into the tooth over time. It is softer, so your dentist avoids it on surfaces that take hard chewing.
Amalgam (silver)
Amalgam suits large cavities in back teeth where strength matters more than appearance. It shows as a dark patch. Dental authorities regard amalgam as safe for most adults. Some countries still limit its use in young children and during pregnancy. Ask your dentist if this affects you.
Ceramic and porcelain
Once a cavity grows too large for a filling, a laboratory-made piece holds the tooth better. That means an inlay or onlay, or a crown for the largest repairs. Ceramic matches your tooth colour and resists wear well.
Which Filling Suits Which Tooth?
- Front teeth: composite, every time. Appearance decides it.
- Small back-tooth cavities: composite holds up well.
- Large back-tooth cavities: your dentist weighs an onlay or a crown against a filling.
- Baby teeth: glass ionomer, because the tooth falls out anyway.
- Cavities at the gum line: glass ionomer bonds well to root surfaces.
A filling needs healthy tooth around it to hold onto. Once decay undermines the cusps, your dentist moves to a stronger repair rather than a larger filling.
Can You Replace Silver Fillings With White Ones?
Yes. Many patients ask us to swap old amalgam for composite so the repair stops showing when they laugh.
Your dentist checks the old filling first. Swapping a sound filling purely for appearance removes more tooth structure, so it is a decision worth talking through. When an old filling has cracked, worn down or leaked, replacing it makes clinical sense as well as cosmetic sense.
If the tooth beneath has decayed badly, you may need root canal treatment before any new filling goes in.
What Your Dentist Weighs Up
- How large the cavity is and how much healthy tooth remains
- Which tooth it is, and how much chewing force it takes
- Whether the repair will show when you smile
- Whether you grind your teeth at night
- Your age, and whether the tooth is a baby tooth
- Any allergy or sensitivity you have reported
Nobody can pick the right material from a photograph or a phone call. Your dentist examines the tooth, takes an X-ray, and shows you what the cavity actually looks like.
Talk Through Your Options
Bring us the tooth and we will walk you through the choice. Our dentists explain what each material would mean for that specific tooth, and you decide before treatment starts.
See all the ways we repair damaged teeth, or read more about tooth decay and how it starts.
Related Reading
- Tooth Fillings – how a filling is placed, start to finish
- Inlays and Onlays – the step up from a large filling
- Dental Crowns – for teeth needing full coverage
- Root Canal Treatment – when decay reaches the nerve
- Tooth Decay – how cavities start