Examination and X-ray
We look at how much tooth remains, whether decay has spread beneath the old filling, whether the nerve is healthy and whether there is a crack, so that the right restoration is chosen first time.
About this treatmentDental condition · Wimpole Street, Marylebone
Lost filling: what has been exposed, how long you have, and how it is put right
Fillings do not last for ever. A piece breaks away while you are eating, or a whole filling comes out in one lump, and suddenly your tongue finds a hole with sharp edges where there was a smooth surface a moment ago. Sometimes it is painful; often it is merely strange. What has happened is that the seal between filling and tooth has failed, usually because the filling had been leaking or the tooth around it had weakened for some time beforehand. The cavity that is now open is lined with dentine, which is softer than enamel and connected to the nerve, so it may react to cold, sweet and pressure, and it will pick up food and bacteria at every meal. Left uncovered for weeks, decay restarts and the thinned walls of the tooth can fracture. Most lost fillings are replaced straightforwardly at a single visit; a minority reveal a tooth that now needs more than a filling. Our Wimpole Street dentists will tell you which, and why.
Recognising it
How it usually feels
A hole or rough crater your tongue keeps finding
The cavity that the filling occupied, now open to the mouth.
A hard fragment in your food or mouth
Part or all of the filling, occasionally with a sliver of tooth attached.
Twinges with cold, sweet or air
Exposed dentine transmitting sensation to a live nerve.
Food packing into the tooth at every meal
The open cavity acting as a trap; also causes a bad taste.
Pain on biting that was there before the filling fell out
Suggests a crack or decay was undermining the filling for some time.
Behind the symptoms
What's going on
- 01
Decay beneath the filling
Bacteria creep in along a margin that has stopped sealing and soften the tooth underneath. The filling loses its foundation and eventually lifts out, often leaving a cavity noticeably bigger than the filling that fell from it.
- 02
Old age of the restoration
Amalgam and composite both fatigue over years of thermal cycling and chewing. Margins chip, the material shrinks or corrodes, and the bond weakens. Fillings that have been in place for fifteen or twenty years have done well; some fail sooner.
- 03
A fractured tooth wall
A large filling leaves thin walls of tooth around it. Under a hard bite one wall can break away, taking the filling with it. When you look at the fragment and see enamel as well as filling material, this is what has happened.
- 04
Grinding and clenching
Repeated heavy loading flexes fillings and the tooth around them. Bruxists lose fillings and fracture teeth far more often than other patients, and the same forces will act on the replacement unless protected.
- 05
Sticky and hard foods
Toffee and chewing gum can pull out a filling whose bond has already failed; a nut, olive stone or crusty bread can crack one. They are the trigger rather than the underlying cause, which is nearly always a filling that had been quietly failing.
Before your appointment
What you can do today
- Keep the tooth clean with a soft brush; avoiding it because it is sensitive allows plaque to build up in the hole.
- Chew on the other side and avoid very hot, cold or sugary foods until the tooth is sealed.
- A pharmacy temporary filling material can be pressed into the cavity to cover the dentine for a few days; follow the pack instructions and do not use anything else.
- Take pain relief as directed on the pack if the tooth aches, and note whether the ache is fleeting or lingers, which helps us judge the nerve.
These are holding measures, not a substitute for an examination. Use any pain relief exactly as directed on the pack and check with a pharmacist if you take other medicines.
In the chair
How we treat it at Wimpole Street
A new white filling
Any softened tooth is removed, the cavity is shaped and a bonded composite filling is placed, sculpted and polished in a single appointment. This is the outcome for most lost fillings.
About this treatmentOnlay or crown for a weakened tooth
When the cavity is large or a wall has broken away, a filling will not hold. A bonded ceramic onlay or a crown covers and protects the remaining tooth and lasts considerably longer.
About this treatmentRoot canal treatment where the nerve is involved
If decay under the old filling has reached the nerve, or the tooth is giving lingering pain, the nerve is treated before the tooth is restored.
About this treatmentProtection against grinding
If wear or cracks show that heavy forces caused the failure, a night guard protects the new restoration and the rest of your teeth.
About this treatmentReview of other old fillings
A failed filling is often the first of a generation. We check the others for leakage and staining so that they can be replaced on your terms rather than when they break.
About this treatmentFees
Costs to expect
An appointment at Wimpole Street to assess and replace a lost filling is expected to be around £95 for the examination and X-ray, with a white filling from £185 depending on its size and how many surfaces it covers. In most cases the filling is placed at the same appointment.
Where the tooth needs more, an onlay or crown is indicative from £995, and root canal treatment where the nerve has been affected is around £695 for a front tooth or £895 for a molar, quoted in addition. A night guard for grinders is £795. You are told before we start whether a filling is realistic or whether the tooth needs something stronger.
Figures are indicative prices for Wimpole Street and are confirmed in a written plan once a dentist has examined you. Fees match our South Kensington and St Paul's clinics.
Don't wait if
When to see a dentist
- Any filling, or part of one, has come out.
- The tooth is sensitive to cold or sweet since the filling went.
- A piece of tooth came out with the filling.
FAQ
Common questions
No. Unlike a crown, a filling is bonded or locked into the tooth at the time it is placed and cannot be re-seated once it has come out. The cavity also usually needs cleaning of decay first, so its shape changes. There is no need to keep the fragment.
Because decay had been hollowing the tooth out underneath the filling, sometimes for years. The filling was the roof over a growing space. Once it goes, the full extent becomes visible, and once the softened tooth is removed the cavity is larger still, which is why some lost fillings end up as onlays.
It is still worth treating promptly. A tooth that has previously had a large filling or a root canal may have little sensation, and decay can advance painlessly. The open cavity also weakens the tooth structurally, and fractures do not give warning.
We place tooth-coloured composite as standard. It bonds to the tooth, which supports the remaining walls, needs less removal of healthy tissue than amalgam and is the material most patients prefer. Where a cavity is very large or deep below the gum, we will discuss whether a filling of any material is appropriate or whether an onlay is the sounder choice.
A well-placed composite in a moderate cavity typically lasts seven to twelve years, and longer with good hygiene and no heavy grinding. Very large fillings fail sooner, which is one reason we suggest an onlay or crown when little tooth remains; those restorations commonly last fifteen years or more.
Marylebone, W1
Wimpole Street opens 1 October 2026
Leave your details and we will be in touch when the Marylebone diary opens. If the problem cannot wait, the same clinicians are already seeing patients in South Kensington and at St Paul's.
Related conditions
Opening 1 October 2026
Wimpole Street is not yet seeing patients. Until then, please book or call our South Kensington clinic on 020 7183 2362 or our St Paul's clinic on 020 7183 3709. Questions about the new clinic: wimpolestreet@md.co.uk.
Until we open
Need an appointment before 1 October 2026?
The same clinical team already works from two other Medical & Dental clinics. Book at either one now and, if you prefer, move your ongoing care to Wimpole Street once the doors open.
South Kensington
- 20 Old Brompton Road, London SW7 3DL
- Open seven days a week
- 020 7183 2362
St Paul's, City of London
- 5 Ave Maria Lane, London EC4M 7AQ
- Open Monday to Friday
- 020 7183 3709
