Decay, or dental caries, is a slow chemical process rather than a sudden event. Bacteria in plaque feed on sugars and starches and release acid; the acid pulls minerals out of the enamel surface; saliva puts some of them back between meals. When the balance tips towards loss for long enough, the enamel surface first turns chalky and then collapses into a hole. From there the process moves faster through the softer dentine beneath, and eventually reaches the pulp, where the nerve and blood vessels live. Each stage has a corresponding response: early lesions can be re-hardened without drilling, established cavities are cleaned and filled, teeth with extensive loss are rebuilt with onlays or crowns, and a tooth whose nerve has been reached needs root canal treatment or removal. The frustrating feature of decay is that pain is a late sign, so a tooth can be badly damaged before it hurts. Regular examination with X-rays at Wimpole Street is how we catch it while the fix is still small.
Chalky white or matt patches along the gumline or between teeth
The earliest visible stage; enamel has lost mineral but is still intact.
Brown or black staining in the grooves of a molar
May be stain only or may be decay under the surface; a probe and X-ray tell them apart.
Short, sharp twinge with sweet food or cold drinks
Dentine exposed to the mouth as the cavity opens.
Food lodging in a spot where it never used to
A hole between two teeth that is hard to see directly.
A tooth that aches after eating and then settles
Decay nearing the nerve; the pulp is inflamed but still recoverable.
Spontaneous throbbing pain, worse lying down
The pulp is inflamed beyond recovery or has died; root canal territory.
Every exposure to sugar produces roughly twenty to forty minutes of acid attack. Six small sweet snacks or sips of a fizzy drink across a day produce far more damage than the same quantity eaten in one sitting, because the enamel never gets time to recover.
Acid is only produced where bacteria sit. The gumline, the surfaces between teeth and the deep grooves on molars are where brushing is least effective, and they are exactly where cavities start. Missed interdental cleaning is the commonest reason adults develop decay between teeth.
Saliva neutralises acid and carries the calcium and phosphate needed to repair enamel. Medicines, dehydration, mouth breathing, radiotherapy and some medical conditions reduce it, and decay can then appear rapidly in a mouth that was stable for decades.
The junction between a filling or crown and the tooth is a weak point. As it ages, a gap opens, plaque gets in and decay develops beneath the restoration where you cannot see or clean it. This is why old fillings are checked and X-rayed periodically.
Where gums have receded, the root surface lacks enamel and is softened by much weaker acid. Root decay is common in older adults and progresses more quickly than decay in enamel.
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.
Each tooth is checked, and bitewing X-rays reveal decay between teeth and under fillings that cannot be seen in a mirror. We grade each lesion by depth and decide whether to monitor, re-harden or restore it.
About this treatmentEarly enamel lesions without a cavity are treated with high-strength fluoride varnish, changes to diet and cleaning, and rechecked at intervals; many stop progressing and harden.
About this treatmentDeep grooves in molars that trap plaque are sealed with a thin resin coating, preventing decay from starting in the most vulnerable site.
About this treatmentEstablished cavities are cleaned of softened tissue and filled with composite bonded to the tooth, shaped to restore the contact with the neighbour so food no longer catches. From £185.
About this treatmentWhen decay has removed a cusp or undermined a large part of the tooth, a laboratory-made onlay or crown restores strength that a filling cannot. £995.
About this treatmentOnce the pulp is irreversibly inflamed or dead, the canals are cleaned and sealed (£695 front tooth, £895 molar) and the tooth is crowned; a tooth beyond saving is removed from £250 and replacement options discussed.
About this treatmentA new patient examination at Wimpole Street with bitewing X-rays is expected to be £95. Fluoride varnish for early lesions is a modest additional fee and is included in children’s check-ups. White fillings start from £185 for a small single-surface cavity and rise with size and the number of surfaces involved; we quote each one individually after the X-rays.
An onlay or crown is £995. Root canal treatment is £695 for an incisor or canine and £895 for a molar, with a crown afterwards for back teeth. Extraction is from £250. A written plan lists every tooth needing attention, ranked by urgency, so treatment can be phased over months where that suits your budget.
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.
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.
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.
