Which Repair: Filling, Onlay or Crown?
The three ways a damaged tooth can be rebuilt, how we weigh one against another, what each costs, and what to expect at the appointments.
Filling, Onlay or Crown: How Does Your Dentist Choose Which One a Tooth Needs?
Two things decide it: the amount of healthy tooth left, and the force that tooth takes when you bite. A small cavity gets a filling; where a back tooth has a large hole but its outer walls are sound, an onlay is generally the best answer, covering the chewing surface without reducing the whole tooth; and a tooth that is mostly old filling, cracked or root treated usually needs a complete crown. Here at Ferry Smile Studios, white fillings begin at £105, a ceramic onlay costs £750 and ceramic crowns begin at £675.
One Rule Behind All Three Repairs
Our starting point is always the least invasive repair that will genuinely last. Each time a drill touches a tooth, some of it is gone for good, so crowning a tooth that a filling could manage makes no sense. The opposite holds too: squeezing an enormous filling into a tooth whose walls are wafer-thin simply invites a fracture.
| Feature | Filling | Onlay | Crown |
|---|---|---|---|
| Suits | Small to medium cavities and chips | Big cavities in back teeth that still have sound walls | Teeth with little structure left, cracked teeth, root-filled molars |
| Tooth removed | The decay alone | The decay and a thin slice of the chewing surface | A layer around the whole tooth |
| Where it's made | Directly in the mouth, same appointment | By a laboratory, from a digital scan | By a laboratory, from a digital scan |
| Appointments | One | Two, as a rule | Two, as a rule |
| Fee from | £105 | £750 | £675 |
When you come in for your examination, the X-ray and photographs go up on the screen so that you can see exactly what we can.
When a Filling Does the Job
A white composite filling takes care of most cavities and minor fractures. The material is a tooth-coloured resin that bonds directly to the tooth; it goes in as thin layers, each set hard with a blue light, and the whole thing is finished in a single appointment. Because the filling is bonded rather than simply packed into the hole, it can even add some strength to the tooth around it.
What you pay depends on which tooth it is and how many surfaces need covering. On a front tooth, a single-surface filling costs £105; the same on a back tooth is £118. A filling that extends across three surfaces of a molar comes to £165. 1
There is a ceiling to what a filling can do. As composite cures it contracts by a tiny amount, and in a big cavity that contraction can pull the margins open or load the surrounding walls with strain. When a filling would account for the greater part of a back tooth's biting surface, we will generally recommend something more robust.
A Filling That Keeps Breaking, or a Tooth That's Cracked?
Come in for an examination and we'll go through the X-ray with you and explain which repair fits the tooth.
The Case for an Onlay
An onlay is a laboratory-made ceramic piece that takes the place of the damaged section of a back tooth, cusps included, and is bonded to the sound tooth beneath. It sits midway between a filling and a crown. By capping and bracing the top of the tooth it spreads the load of chewing rather than letting it wedge the walls apart, yet the healthy sides of the tooth are left untouched.
It suits:
- A premolar or molar carrying a big old filling that keeps breaking away
- A tooth that has cracked through one cusp while the other walls remain solid
- Plenty of root-filled back teeth, provided the walls are still substantial
- Swapping large metal fillings for something stronger and tooth-coloured
A ceramic onlay costs £750, or £675 if you are on one of our dental plans. 1 Two appointments are needed: shaping the tooth and scanning it with our iTero Lumina comes first, then the completed onlay is bonded into place at the second.
When a Crown Is the Right Answer
A crown wraps around the whole of the tooth above the gum, rather like a thimble on a finger. We suggest one when too little sound tooth remains for an onlay to bond to, or when the tooth has to be held together on every side. That covers teeth split in two, teeth with a crack travelling down one side, teeth flattened by grinding or acid wear, and a good many back teeth once they have had root canal treatment.
We make our crowns in ceramic, matched in shade to the neighbouring teeth, so there is no grey band of metal where crown meets gum. A crown on a back tooth is from £675; on a front tooth, from £750. Where very little of the tooth is left, it may first need a core built up, sometimes anchored with a fibre post at £160. 1 For heavy grinders with limited space on a back tooth, gold remains a perfectly sound choice, and a quote is available on request. There is more on our crowns page.
What Happens at Each Visit
A filling is completed in a single appointment. We numb the tooth, clear away the decay along with any old filling, then build and polish the new composite. Once the anaesthetic has worn off you can eat normally.
An onlay or crown needs two appointments, generally around a fortnight apart.
- Appointment one: the tooth is numbed and shaped, decay and old filling material are removed, and a digital scan takes the place of a mouthful of putty. A temporary is fitted to keep the tooth protected
- In between: a dental laboratory builds your onlay or crown from the scan
- Appointment two: the temporary is removed, the new restoration is tried in for you to check the shade and the fit, and it's then bonded on and the bite adjusted
While you have the temporary, steer clear of chewing gum and toffee on that side of your mouth, and when flossing, draw the floss out sideways instead of lifting it, so the temporary stays put. If it does come away, hang on to it and give us a call.
Every Fee in One Place
| Treatment | Fee | Plan member |
|---|---|---|
| Single-surface composite filling, incisor or canine | £105 | £95 |
| Single-surface composite filling, molar or premolar | £118 | £106 |
| Three-surface composite filling, molar or premolar | £165 | £149 |
| Ceramic onlay | £750 | £675 |
| Ceramic crown on a molar or premolar, from | £675 | £608 |
| Ceramic crown on an incisor or canine, from | £750 | £675 |
| Examination for new patients, including X-rays | £70 | Included in your plan |
Before any treatment starts you receive a written plan confirming the fee, and plan members pay 10% less on each of the three repairs. 1 Should the tooth need a root canal first, that is charged separately; the fees are in our root canal guide. Where treatment is provided under the NHS, clinically necessary fillings and crowns are charged at NHS rates.
Expected Lifespan of Each Repair
Looked after well, a ceramic crown typically gives 10 to 15 years of service and frequently much longer. Onlays last about as long, and a composite filling placed properly in a small cavity can go on for many years too. The size of the repair matters: larger fillings tend to have shorter lives.
It's unusual for a restoration to fail by itself. More often the cause is fresh decay creeping in at the junction between restoration and tooth, gum disease, or grinding. What makes the difference is brushing twice a day, daily floss or interdental brushes between the teeth, and regular examinations so that small problems at the edges are caught early. Clenchers and grinders should consider a night guard at £210, which shields both the repair and the tooth beneath it. The warning signs are described in our teeth grinding guide.
Questions
This guide is general information, not a diagnosis. A dentist needs to examine you to say what is right for your teeth.