Filling, Onlay or Crown?
The three ways we repair a damaged tooth, the reasoning behind picking one over another, the fees, and what each appointment involves.
How Does a Dentist Decide Between a Filling, an Onlay and a Crown?
It comes down to how much sound tooth is left and how hard that tooth works when you chew. Small holes get a filling; a back tooth with a big hole but solid outer walls is usually best with an onlay, which caps the biting surface without cutting the whole tooth down; and a tooth that's mostly filling, cracked or root filled usually needs a full crown. At Hamilton Smile Studios, white fillings start at £105, a ceramic onlay is £750 and a ceramic crown starts at £675.
Three Repairs, One Principle
We always start with the smallest repair that will do the job properly. Every time a tooth is drilled, a little more of it is lost for good, so there's no sense in crowning a tooth a filling could look after. Equally, packing a huge filling into a tooth with paper-thin walls just sets it up to split.
| Feature | Filling | Onlay | Crown |
|---|---|---|---|
| Best for | Small and medium cavities, chips | Large cavities in back teeth with sturdy walls | Teeth with little left, cracks, root-filled molars |
| How much tooth is removed | Only the decay | Decay plus a thin layer of the biting surface | A layer all the way round |
| Made | In the mouth, same visit | In a laboratory from a scan | In a laboratory from a scan |
| Visits | One | Usually two | Usually two |
| Fee from | £105 | £750 | £675 |
At your examination we'll show you the X-ray and photos of the tooth so you can see what we're seeing.
When a Filling Is Enough
Most cavities and small fractures are repaired with a white composite filling. It's a tooth-coloured resin bonded straight onto the tooth, built up in thin layers and hardened with a blue light, all in one sitting. Because it's glued to the tooth rather than wedged in, it can actually help hold the remaining tooth together.
The fee depends on the tooth and how many of its surfaces are involved. A one-surface filling on a front tooth is £105, and on a back tooth £118. One that wraps over three surfaces of a molar is £165. 1
Fillings have limits. Composite shrinks very slightly as it sets, and in a very large cavity that can leave gaps at the edges or stress the walls. Once a filling would make up most of a back tooth's chewing surface, we'll usually advise something stronger.
Cracked Tooth or a Filling That Keeps Failing?
Book an examination. We'll show you the X-ray and explain which repair suits the tooth.
Why We Often Suggest an Onlay
An onlay is a custom-made piece of ceramic that replaces the damaged part of a back tooth, including one or more of the pointed cusps, and is bonded onto what's left. Think of it as somewhere between a filling and a crown. It covers and braces the top of the tooth, so biting forces are spread out instead of prising the walls apart, but it leaves the healthy sides of the tooth alone.
That makes it a good fit for:
- A molar or premolar with a large old filling that keeps chipping
- A tooth with a crack across one cusp but strong walls elsewhere
- Many root-filled back teeth, where the walls are still thick enough
- Replacing large metal fillings when you want something tooth-coloured and stronger
A ceramic onlay is £750, or £675 on a dental plan. 1 It's a two-visit job: the tooth is prepared and scanned on our iTero Lumina at the first, and the finished onlay is bonded on at the second.
When Only a Crown Will Do
A crown covers the entire visible part of the tooth, like a thimble. We recommend one when there isn't enough sound tooth for an onlay to grip, or the tooth needs holding together all the way round. That includes teeth that have snapped in half, teeth with a crack running down the side, teeth worn flat by grinding or acid erosion, and many back teeth after root canal treatment.
Our crowns are ceramic, colour-matched to the teeth beside them, with no grey metal edge at the gum. A back crown starts at £675 and a front crown at £750. If there's very little tooth left, it may need building up first with a core, sometimes held by a fibre post, £160. 1 For people who grind hard on a back tooth with little room, gold remains a good option and can be priced on request. More detail is on our crowns page.
The Appointments
For a filling, everything happens in one visit. The tooth is numbed, the decay and any old filling are removed, and the new composite is placed and polished. You can eat once the numbness wears off.
For an onlay or crown, there are two visits, usually about two weeks apart.
- First visit: the tooth is numbed and shaped, old filling material and decay are cleaned out, and a digital scan replaces the old tray of putty. A temporary goes on to protect the tooth
- Between visits: a dental laboratory makes your onlay or crown from the scan
- Second visit: the temporary comes off, the new restoration is tried in so you can see the colour and fit, then it's bonded in place and the bite is fine-tuned
While the temporary is on, avoid toffee and chewing gum on that side, and pull floss out sideways rather than lifting it, so the temporary isn't flicked off. If it does come off, keep it and give us a ring.
Fees in Full
| Treatment | Fee | Plan member |
|---|---|---|
| Composite filling on an incisor or canine, single surface | £105 | £95 |
| Composite filling on a molar or premolar, single surface | £118 | £106 |
| Composite filling on a molar or premolar, three surfaces | £165 | £149 |
| Onlay in ceramic | £750 | £675 |
| Crown in ceramic, molar or premolar, from | £675 | £608 |
| Crown in ceramic, incisor or canine, from | £750 | £675 |
| New patient examination with X-rays | £70 | Included in your plan |
Your fee is confirmed in a written plan before treatment, and plan members save 10% on all three repairs. 1 If the tooth needs root canal treatment first, that's a separate fee, set out in our root canal guide. Adults on our NHS list can have clinically necessary fillings and crowns at NHS charges.
How Long Each One Lasts
With good care, a ceramic crown commonly lasts 10 to 15 years and often well beyond. Onlays perform similarly, and a well-placed composite filling in a small cavity can last many years. Size matters: the bigger a filling, the shorter its life tends to be.
Restorations rarely fail on their own. The usual culprits are new decay starting at the edge where the restoration meets the tooth, gum disease, and grinding. Twice-daily brushing, flossing or interdental brushes every day, and regular dental examinations that catch small problems at the margins are what keep them going. If you grind or clench, a night guard, £210, protects the repair and the tooth under it. Our teeth grinding guide covers the warning signs.
Questions
This guide is general information, not a diagnosis. A dentist needs to examine you to say what is right for your teeth.