Filling, Onlay or Crown?
What separates a filling from an onlay or a crown, how we choose between them, what each costs and how the appointments run.
How Do I Know Whether My Tooth Needs a Filling, an Onlay or a Crown?
The deciding factor is how much sound tooth remains. A small cavity is repaired with a filling. If the biting surface is damaged but the side walls are still strong, an onlay protects the tooth while keeping more of it than a crown would. When most of the tooth has gone, or a back tooth has been root filled, a crown holds it together. At Peninsula Dentists on Greenwich Peninsula, white fillings start at £105, ceramic onlays at £650 and ceramic crowns at £650, with your fee set out in a written plan before we begin.
How We Choose
Two things guide the decision: how much sound tooth is left once decay or an old filling has been removed, and how hard that tooth works when you chew. We always start from the smallest repair that will do the job, which is usually a filling. The difficulty comes when a cavity is large. Pack a big filling into a tooth and the walls around it become thin, and thin walls crack under biting pressure. At that stage the tooth needs something that wraps over and supports it, not just something that plugs the gap.
| What we find | What usually suits it |
|---|---|
| A small area of decay or a minor chip | Filling |
| A damaged biting surface with sturdy walls | Onlay |
| Most of the tooth lost, or a root-filled back tooth | Crown |
Before anything is decided, we talk you through your X-ray and the scan of your tooth on screen, so you can see the reasoning for yourself. Keeping as much of your own tooth as possible is always the aim.
When a Filling Is Enough
Fillings are for cavities and small chips. Ours are white composite, shade-matched to the tooth and bonded to it, so the filling helps hold the remaining tooth together as well as sealing it. Everything happens in a single appointment with the tooth numbed. We clear out the decay, clean and prepare the surface, then build the composite up layer by layer, hardening each one with a curing light. Once the anaesthetic wears off you can eat normally.
A one-surface filling on a front tooth starts at £105, and on a back tooth at £118; the more surfaces involved, the higher the fee.2 Small and medium cavities are where fillings work best. If the repair would cover most of the chewing surface, or an old filling has broken more than once, an onlay is usually the stronger and longer-lasting answer.
Broken, Cracked or Heavily Filled Tooth?
Book a dental examination and we'll show you which repair suits it, with the fee in writing first.
What an Onlay Does
An onlay is a ceramic restoration made in a dental laboratory to the exact shape of your prepared tooth and then bonded on. It replaces the biting surface, including one or more of the cusps, but leaves the sound side walls alone. Compared with a crown, far less healthy enamel is removed, yet the tooth still gains protection against splitting.
We often recommend onlays for back teeth with a big cavity or a failing filling, for cracked teeth whose walls are still firm, and for many premolars and molars after root canal treatment. Ceramic onlays start at £650, or £585 on one of our dental plans.2 We take a digital scan with our iTero Element rather than a putty impression, and the work is done over two visits: preparation and scanning first, then fitting.
When a Crown Is the Better Choice
A crown is a cap that covers all of the tooth above the gumline. We suggest one when there isn't enough strong tooth left for an onlay or filling to protect: after a large break, for a cracked tooth that is painful to bite on, where a big filling is failing, where grinding or acid erosion has worn the tooth down, or on a back tooth that has had root canal treatment. Root-filled molars and premolars become more brittle, so covering them guards against fracture.
We make most crowns in ceramic, colour-matched to the neighbouring teeth, so they blend in at the front of the mouth and the back. Ceramic crowns start at £650 for a front tooth and £650 for a back tooth.2 For heavy grinders, or where space is very tight, gold remains a sound option on a back tooth because it can be made thinner than ceramic; we price gold on request. Every crown is designed from an iTero Element scan. You can read more on our crowns page.
Fees for Each Option
Your exact fee is set out in a written treatment plan before we start, and members of our dental plans receive 10% off fillings, onlays and crowns.2
| Treatment | Fee | Plan member |
|---|---|---|
| Front tooth white filling, from | £105 | £95 |
| Back tooth white filling, from | £118 | £106 |
| Ceramic onlay, from | £650 | £585 |
| Front tooth ceramic crown, from | £650 | £585 |
| Back tooth ceramic crown, from | £650 | £585 |
| New patient dental examination, including two X-rays | £30 | Included in your plan |
Where root canal treatment has to come first, it carries its own fee, which our root canal guide explains. Bills of £1,500 or more can be paid monthly through Chrysalis Finance, subject to status. Our fee guide lists everything else.
The Appointments, Step by Step
Fillings are normally finished in one appointment; onlays and crowns need two. Both visits are easy to fit around work, and Canary Wharf is five minutes away on the Jubilee line.
- Assessment. We examine the tooth, take an X-ray if one is needed and explain which repair we recommend and why, along with the fee, before any work begins.
- Preparing and scanning. With the tooth numbed, we remove decay and any old filling and shape what remains. For an onlay or crown, a quick iTero Element scan records the tooth in 3D, and a temporary covers it while the laboratory makes the final piece.
- Fitting. At the second visit we try the onlay or crown in, check the fit and shade with you, bond it permanently and fine-tune your bite until it feels natural.
While the temporary is on, chew on the opposite side, avoid toffee and other sticky foods, and draw floss out sideways instead of lifting it back up through the contact. If the temporary does come away, keep it safe and ring us so we can refit it.
Helping Your Repair Last
Looked after well, a crown usually gives 10 to 15 years of service and frequently more, and onlays and good fillings can also last a long time. The usual reasons they fail are decay starting at the margin, gum disease and the forces from grinding. Prevention is simple: brush twice daily, clean between your teeth once a day paying particular attention to where the restoration meets the tooth, and keep up your regular dental examinations so we can spot a weak edge early.
If you clench or grind, a custom night guard from £135 protects a crown or onlay as much as your natural teeth, and our teeth grinding guide covers the warning signs. Try not to crunch ice or chew pens and fingernails. Should a repair chip or loosen, save any fragments and call 020 8788 6688; ring before 9.30am, Monday to Saturday, and we can see you the same day.
Questions
This guide explains the options in general terms. Only an examination can tell you which of them suits your own teeth.