Last updated: May 2026. Sources: NHS, OHID Delivering Better Oral Health Toolkit, Adult Oral Health Survey 2023, NDEP 2024, NHSBSA, NICE, NHS England, Public Health Scotland, Public Health Wales. NHS dental charges effective 1 April 2026.
TL;DR: Tooth decay (dental caries) is the gradual breakdown of tooth enamel by acid produced when bacteria feed on dietary sugar. Early decay is reversible with fluoride. Once a cavity forms, you need a filling, which costs £76.60 on the NHS. Brush twice daily with 1,350 ppm fluoride toothpaste, spit don't rinse, and cut sugar frequency.
In England, 41% of adults now show obvious signs of tooth decay, up from 28% in 2009 and almost back to 1998 levels [1]. Almost a quarter of five-year-olds have experienced decay [2]. Tooth decay is the single most common reason a child in England is admitted to hospital between the ages of five and nine [3]. The disease is preventable and, in its earliest stages, reversible. Once it gets going, however, it follows a predictable path that ends in pain, infection, and tooth loss.
This guide explains what tooth decay is, the five stages it moves through, the symptoms at each stage, NHS and private treatment costs in 2026, how to prevent it, what changes for children, and when to see a dentist. The clinical detail is drawn from NHS.uk, the Office for Health Improvement and Disparities (OHID) Delivering Better Oral Health toolkit, NHSBSA, NICE, and the most recent UK oral health surveys.
What is tooth decay?
Tooth decay, dental caries, and cavity all describe related but slightly different things.
- Dental caries is the clinical name for the disease: the progressive demineralisation of the hard tissues of a tooth caused by acid.
- Tooth decay is the everyday term for the same process.
- A cavity is the physical hole that forms once the disease has eaten through enough enamel for the tooth surface to break down.
You can have early-stage tooth decay without yet having a cavity, which is why dentists detect decay before you feel any symptoms. The Office for Health Improvement and Disparities (OHID) explains the underlying mechanism in its evidence-based prevention toolkit:
"The disease is caused by dietary sugars that are broken down by micro-organisms in the biofilm on a tooth surface, which produces acids that, over time, demineralise tooth enamel." [4]
The bacteria themselves are part of normal oral flora. The disease arises when the balance tips, when sugars are consumed too often and fluoride exposure is too low, so the cycle of demineralisation outpaces remineralisation [4].
The 5 stages of tooth decay
The clinical literature describes a continuum, not a sudden break. The five stages below are the standard way of mapping that continuum onto something patients can recognise. Stages 1 and 2 are still reversible. From stage 3 onwards, you need clinical treatment.
- Initial demineralisation (white spot lesion). The earliest visible sign of active decay is a chalky, opaque white area on the enamel surface. There is no pain and no cavity. Fluoride exposure (toothpaste, varnish, or fluoridated water) can still rebuild the mineral structure at this stage [4].
- Enamel decay. Demineralisation continues and the enamel weakens, but the surface still has not broken down. The NHS confirms a dentist "can prescribe fluoride treatments like mouthwash or varnish to reverse early tooth decay" [5].
- Dentine decay (cavitation). The enamel surface breaks and bacteria reach the softer dentine underneath. The OHID toolkit describes this as "a position of no return where operative intervention is required" [4]. A filling is needed. Sensitivity to sweet, hot, and cold becomes noticeable.
- Pulp involvement (pulpitis). Decay reaches the pulp at the centre of the tooth, where the nerves and blood vessels live. Inflammation produces persistent toothache. The NHS notes that at this stage "you may need root canal treatment" [5].
- Abscess formation. Bacteria spread beyond the tip of the root and a periapical abscess develops. Symptoms include intense pain, swelling of the face or jaw, and fever [6]. This is a dental emergency, and severe swelling that affects breathing or swallowing needs 999 or A&E.
The five-stage model is not a branded NHS framework, but it maps cleanly onto the clinical progression described by OHID and the NHS. Treat it as a useful patient-facing way of understanding what stage you, or your child, may be at.
Symptoms at each stage
Early tooth decay is silent. By the time it hurts, it has usually been progressing for a while. The NHS lists the following symptoms, in roughly the order they tend to appear [5]:
- Stages 1-2 (often no symptoms): white, chalky, or opaque patches on the enamel. Possibly a slight roughness when you run your tongue over the tooth. No pain.
- Stage 3: sharp pain when you eat or drink something hot, cold, or sweet. Visible grey, brown, or black discolouration. A visible hole or rough edge in the tooth.
- Stage 4: throbbing or persistent toothache that may interrupt sleep. Pain triggered by biting down. Sensitivity that lingers after the trigger has gone.
- Stage 5 (abscess): severe, continuous pain. Swelling of the gum, cheek, jaw, or neck. Bad taste in the mouth or pus visible at the gum line. Fever. Difficulty opening the mouth.
If you have any of the stage 5 symptoms, especially swelling that extends towards the eye or affects swallowing or breathing, treat this as a medical emergency and call 999 or go to A&E [6].
For an in-depth look at where pain comes from and what each type might indicate, see our guide to types of dental pain and what they mean.
What causes tooth decay?
OHID and NHS guidance both single out the same primary modifiable risk: how often you consume sugar, not just how much.
Frequent sugar exposure. Every time sugar reaches your teeth, oral bacteria produce acid for roughly 20 minutes. Six small sugary snacks throughout the day produce six 20-minute acid attacks. One slightly larger one with a meal produces one. The NHS guidance is direct: "reduce the amount and number of times you have foods and drinks that contain added sugars," and "avoid sugary foods and drinks just before bedtime as the saliva flow in the mouth slows down when you sleep" [5].
Inadequate fluoride exposure. Fluoride is what allows enamel to remineralise after each acid attack. Brushing with a fluoride toothpaste of at least 1,350 ppm twice a day is the single most effective domestic measure, according to OHID [4].
Poor plaque control. Plaque is the bacterial biofilm that holds sugar against the tooth surface. Without daily disruption by brushing and interdental cleaning, it thickens, traps more sugar, and the acid cycle accelerates.
Dry mouth (xerostomia). Saliva neutralises acid and carries calcium and phosphate that help remineralise enamel. Reduced saliva flow, often a side effect of medication, raises decay risk substantially [5]. Read more in our guide to dry mouth (xerostomia) in the UK.
Sugar in medicines. The NHS specifically advises patients on long-term oral medications to "use sugar-free medicines" where possible [5].
Smoking. Tobacco use increases decay risk, partly through reduced saliva quality and partly through other oral health pathways [5].
Older age and existing restorations. Adults with multiple existing fillings or crowns face a higher risk of recurrent decay around the margins of those restorations, and root caries (decay on exposed root surfaces) becomes more common with age [4].
Children with prior decay. Past decay is the strongest single predictor of future decay. NICE recommends recall intervals are tailored to risk for this reason [7].
How tooth decay is diagnosed
Dentists detect decay through a combination of visual examination, gentle probing, and bitewing X-rays. X-rays can show interproximal decay (between teeth) before it is visible to the naked eye, which is why the NHS recommends regular check-ups even when you have no symptoms [5]. NICE guideline CG19 recommends that recall intervals be tailored to individual risk, with a maximum of 24 months between adult check-ups and 12 months for under-18s [7].
If you are unsure where to start finding regular dental care, our guide on how to find a good dentist in the UK walks through what to look for on the GDC register, CQC ratings, and practice fundamentals.
NHS treatment costs by stage (April 2026)
NHS dental charges in England are set by the Department of Health and Social Care and changed on 1 April 2026. The same band charge covers the entire course of treatment, no matter how many appointments are needed [8]. Treatments needed for tooth decay are billed as follows.
| Stage of decay | Likely treatment | NHS band | Cost (England, 1 April 2026) |
|---|---|---|---|
| Stage 1-2 (early demineralisation) | Examination, fluoride varnish, oral hygiene advice | Band 1 | £27.90 |
| Stage 3 (cavitation) | Filling | Band 2 | £76.60 |
| Stage 4 (pulpitis) | Root canal treatment | Band 2 | £76.60 |
| Stage 5 (abscess) | Urgent assessment, drainage, emergency root canal or extraction | Urgent | £27.90 |
| Tooth lost or unrestorable | Crown, denture, or bridge | Band 3 | £332.10 |
| Routine extraction | Extraction | Band 2 | £76.60 |
[NHSBSA, "NHS dental charges from 1 April 2026" [8]]
Two practical points the NHS specifically calls out [8]:
- A single course of treatment, even one with multiple appointments, is charged at one band. A check-up plus a filling plus an extraction is one Band 2 charge of £76.60, not three separate charges.
- Further treatment in the same band, or a lower band, within two months of finishing a course of treatment is free.
Our standalone guides go deeper on the typical costs for the most common decay-related treatments: NHS dental filling cost, root canal treatment cost, and tooth extraction cost.
NHS dental charges differ across the four UK nations. Wales has a separate fee schedule, Scotland uses an item-by-item system rather than bands, and Northern Ireland charges patients a percentage of the cost. Always check the NHSBSA, NHS Inform (Scotland), or NHS Wales for the current rate where you live.
Free NHS dental treatment
NHS dental treatment is free for [9]:
- Children under 18, or under 19 in full-time education
- Pregnant women, and people who have given birth or had a stillbirth in the last 12 months (proof: MatEx certificate, MATB1 form, or the baby's birth certificate)
- People receiving income-related Employment and Support Allowance, Income Support, income-based Jobseeker's Allowance, or Pension Credit Guarantee Credit
- Universal Credit recipients with earnings under the qualifying threshold
- Dependants under 20 of any of the above
- People with a valid HC2 certificate from the NHS Low Income Scheme
Partial help (HC3 certificate) is available to those on lower incomes who do not qualify outright. The full eligibility list and how to apply for help is set out in our guide to free NHS dental treatment in the UK.
Private treatment costs
Private fees vary widely by region, practice, and material. London tends to sit at the top of the range, the rest of England below. For up-to-date typical private fees, see our dedicated guides:
The cost of treatment rises sharply with each stage of decay. A £27.90 NHS check-up that catches a white spot lesion is a much smaller bill than the £332.10 NHS Band 3 charge, or four-figure private fee, for a crown after pulp involvement.
How to prevent tooth decay
The OHID Delivering Better Oral Health toolkit and NHS guidance converge on a small set of high-evidence prevention measures.
Brush twice daily with fluoride toothpaste. Adults and children of all ages should use a toothpaste containing 1,350 to 1,500 ppm fluoride [10]. Children under 3 without active decay can use a smear of toothpaste containing at least 1,000 ppm; children aged 3 to 6 should use a pea-sized blob [10]. Brushing should take about two minutes, with one of the two daily sessions being last thing at night [10]. Our how to brush teeth properly guide covers technique step by step.
Spit, do not rinse. The NHS guidance is explicit: "Don't rinse your mouth immediately after brushing, as it'll wash away the concentrated fluoride in the toothpaste" [10]. This single change preserves the protective effect of the fluoride on the enamel for hours afterwards.
Clean between your teeth daily. Brushing alone reaches around 60% of tooth surfaces. The other 40% (the spaces between teeth) is where interproximal decay tends to start. Floss or interdental brushes should be part of the daily routine. See our flossing and interdental brushes guide.
Cut sugar frequency, not just amount. Reducing the number of times sugar reaches your teeth is more important than reducing the total quantity [5]. Confine sugary foods and drinks to mealtimes. Cut bedtime sugar entirely.
Use fluoride varnish. Twice-yearly fluoride varnish application in a dental setting reduces caries by an average of 37% in primary teeth and 43% in permanent teeth [11]. It is included free in NHS care for under-18s, and is now available as a standalone NHS course of treatment for children, applied by a dental nurse without needing a full check-up first [12].
Have regular check-ups. NICE guideline CG19 sets the maximum interval at 24 months for adults and 12 months for under-18s, but the actual interval should be tailored to your individual risk [7].
Stop smoking. Smoking cessation lowers decay risk along with the wider gum and oral cancer risks [5].
If your mouth is dry from medication, ask your dentist about saliva substitutes and adjustments to your oral hygiene routine. Our dry mouth guide covers the options.
Tooth decay in children
Tooth decay is the most common reason for hospital admission in children aged 5 to 9 in England [3]. NHS data shows 31,165 hospital tooth extraction episodes for decay in children and young people aged 0 to 19 in 2022/23, costing the NHS £40.7 million [3]. Decay rates in the most deprived areas are more than twice those in the least deprived [2].
The good news is that almost all childhood decay is preventable, and the rules are simple:
- Start brushing as soon as the first tooth appears, twice a day [10].
- Use the right amount and strength of toothpaste for the age (smear under 3, pea-sized 3 to 6, normal amount thereafter) [10].
- An adult should brush or supervise brushing until the child is around 7.
- No sugary drinks in bottles or sippy cups, and no juice between meals.
- The first dental visit should happen as soon as the first tooth comes through. NHS dental treatment for under-18s is free.
- Take advantage of NHS fluoride varnish twice a year, free for all under-18s [12].
Our child's first dental visit guide walks new parents through what to expect.
England: a £11 million Government supervised toothbrushing programme, announced in March 2025, targets up to 600,000 three-to-five-year-olds in the most deprived areas, in nurseries and reception classes, with first deliveries in June 2025. Every £1 invested is projected to save £3 in treatment costs over five years [13].
Scotland: the long-running Childsmile programme has lifted the share of P1 children with no obvious decay from 45.0% in 2003 to 73.2% in 2024, narrowing the deprivation gap by almost 9 percentage points since 2010 [14].
Wales: the Designed to Smile programme runs in similar form, and decay rates in 12-year-olds have fallen to 25.3% from nearly one in three in 2016/17 [15].
When to see a dentist
The NHS guidance breaks this into three tiers [5][6].
Routine appointment, soon:
- Toothache that lasts more than a day or two.
- Sensitivity to hot, cold, or sweet that does not subside.
- Visible dark spots, holes, or rough edges in a tooth.
Urgent same-day appointment (call your dentist or NHS 111):
- Continuous toothache that disrupts sleep.
- Swelling of the gum, face, or jaw.
- A bad taste in the mouth or pus at the gum line.
- Fever with toothache.
999 or A&E, immediately:
- Difficulty swallowing or breathing because of dental swelling.
- Swelling spreading towards the eye.
- Severe restriction of jaw opening.
- Rapidly growing swelling in the mouth or throat.
If you cannot get a dental appointment quickly, NHS 111 can direct you to urgent dental services in your area. Read our guide on emergency dental care in the UK for what to expect.
What is changing in 2026
A package of NHS dental contract reforms took effect on 1 April 2026, following the Government's consultation response published on 16 December 2025. Three changes matter for tooth decay [12]:
- Urgent care mandate. NHS dental practices with contracts of 100 UDAs or more must now deliver 8.2% of contract value as unscheduled or urgent care, projected to deliver around 700,000 more urgent appointments a year [16].
- Standalone children's fluoride varnish. Dental nurses can now apply children's fluoride varnish as a separate, standalone NHS course of treatment, without needing a full dental check-up to be performed first [12].
- Complex care pathways. New treatment pathways are in place for serious tooth decay and progressive gum disease.
The Government has also continued the consultation on expanding community water fluoridation in the north east of England, an additional 1.6 million people. Its impact assessment confirms that water fluoridation "is an effective and safe public health measure to reduce the prevalence and severity of tooth decay and reduce dental health inequalities" [17].
Frequently asked questions
Can tooth decay be reversed?
Early-stage tooth decay can be reversed before a cavity has formed. Fluoride from toothpaste, mouthwash, or varnish allows demineralised enamel to rebuild its mineral structure. Once decay has broken through the enamel and created a hole, the cavity itself cannot heal and a filling or other clinical treatment is needed.
What does early tooth decay look like?
Early tooth decay typically appears as a chalky white or opaque patch on the enamel, called a white spot lesion. The surface may feel slightly rougher than nearby enamel. There is no pain. Grey, brown, or black discolouration usually means decay has progressed past the early stages and a dental check-up is needed.
What is the difference between tooth decay and a cavity?
Tooth decay (dental caries) is the disease process: the gradual loss of mineral from the tooth caused by acid produced by oral bacteria. A cavity is the physical hole that forms once that process has eaten through enough enamel for the surface to break down. You can have early tooth decay before a cavity is visible.
How much does an NHS filling cost in 2026?
A standard NHS filling in England costs £76.60 as a Band 2 treatment from 1 April 2026. The single charge covers the whole course of treatment, including any examination and X-rays needed, regardless of how many appointments it takes. Children under 18, pregnant women, and certain other groups receive NHS dental treatment free of charge.
What happens if tooth decay is left untreated?
Untreated decay progresses through the enamel into the dentine, then into the pulp at the centre of the tooth, causing severe and persistent toothache. Infection can then spread beyond the tooth root and form a dental abscess, with swelling, fever, and pus. Severe abscesses can spread to the jaw, neck, or beyond and become medical emergencies.
Does sugar cause tooth decay?
Yes, sugar is the primary dietary cause of tooth decay. Bacteria in dental plaque convert sugars into acid that erodes enamel. NHS guidance highlights that the frequency of sugar consumption matters as much as the total amount: repeated small sugar exposures throughout the day cause more damage than a single larger amount with a meal.
Is a scale and polish enough to treat tooth decay?
No. A scale and polish removes plaque and tartar from the tooth surface, which helps prevent decay and treat gum disease, but it does not repair decay that has already formed. Once a cavity exists, it needs a filling. A dentist may combine a clean with restorative treatment in the same NHS course of treatment.
How can I tell if I have tooth decay without a dentist?
In the early stages, there are usually no signs you can detect at home. Visual clues include white, brown, or black spots, visible holes, or rough edges. Symptoms that suggest progression include sensitivity to sweet, hot, or cold, and a persistent dull ache. Only a dental check-up with X-rays can confirm decay reliably.
Can adults get tooth decay around old fillings?
Yes. Decay around the margins of an existing filling, called recurrent or secondary caries, is common, especially as fillings age and small gaps form between the filling material and the tooth. This is one reason regular check-ups matter for adults with restorations: replacement of a worn filling is usually a Band 2 NHS course of treatment.
Is tooth decay inherited?
Tooth decay itself is not directly inherited. The disease is driven by diet, oral hygiene, fluoride exposure, and saliva flow, all of which are modifiable. Some inherited factors, such as enamel structure and tooth shape, can affect individual risk, but they are far less significant than the day-to-day behaviours that drive demineralisation.
Find a dentist on Dentists Closeby
If you have noticed any of the symptoms above, or you are simply due for a check-up, search for a dentist near you. Dentists Closeby lists NHS and private dental practices across the UK, with information on each practice's General Dental Council registration, CQC rating, current availability, and the services they offer. Catching decay early, before it reaches the dentine, is the cheapest, fastest, and least painful path to keeping your teeth.
Sources
- Adult Oral Health Survey 2023: Clinical oral health -- Office for Health Improvement and Disparities, GOV.UK, published December 2025
- National Dental Epidemiology Programme for England: oral health survey of 5 year old schoolchildren 2024 -- OHID, GOV.UK, published 2024
- Hospital tooth extractions in 0 to 19 year olds: short statistical commentary 2023 -- OHID, GOV.UK, published 2023
- Delivering better oral health: an evidence-based toolkit for prevention, Chapter 4 - Dental caries -- OHID, GOV.UK
- Tooth decay -- NHS, last reviewed 13 August 2025
- Dental abscess -- NHS, last reviewed 18 March 2026
- Dental checks: intervals between oral health reviews (CG19) -- NICE
- NHS dental charges from 1 April 2026 -- NHSBSA
- Who can get free NHS dental treatment -- NHS
- How to keep your teeth clean -- NHS, last reviewed 30 June 2025
- Delivering better oral health: an evidence-based toolkit for prevention, Chapter 9 - Fluoride -- OHID, GOV.UK
- Major boost for millions of NHS dental patients -- GOV.UK, published 16 December 2025
- Supervised toothbrushing for children to prevent tooth decay -- GOV.UK, published 7 March 2025
- National Dental Inspection Programme 2024 -- Public Health Scotland
- Tooth decay rates in 12-year-olds in Wales fall, but challenges remain -- Public Health Wales
- Confirmation of urgent/unscheduled care activity requirements for NHS dental contract holders for 2026/27 -- NHS England
- Community water fluoridation expansion in the north east of England - government response -- GOV.UK
