Quick answer. Tooth decay (dental caries) happens when bacteria in plaque turn sugar from food and drinks into acid that erodes tooth enamel, eventually forming cavities (holes). It is extremely common and is often painless early on, later causing toothache and sensitivity to sweet, hot or cold. Cavities are treated with fillings (tooth-coloured composite or amalgam), while general tooth sensitivity is managed with desensitising toothpaste, fluoride and treating the underlying cause. Untreated decay spreads to the tooth’s pulp and may need a root canal or extraction, so prevent it with twice-daily fluoride brushing, less sugar and snacking, flossing and 6-monthly dental check-ups; eligible patients can use CHAS subsidies at participating clinics.
Tooth decay is one of the most common health conditions in the world, and Singapore is no exception. The good news is that it is largely preventable, and most cavities are simple to treat if caught early. This guide explains what causes decay and sensitive teeth, how fillings and other treatments work, what they typically cost here, and the everyday habits that keep your teeth healthy.
At a glance
| Issue | Cause | What helps |
|---|---|---|
| Tooth decay / cavity | Plaque bacteria turn sugar into acid that erodes enamel and forms a hole | Fillings (composite or amalgam); early on, fluoride; crown for large cavities |
| Sensitivity from decay | An active cavity reaching the dentine, usually in one tooth | See a dentist; the tooth needs a filling, not just toothpaste |
| General tooth sensitivity | Exposed dentine from gum recession, enamel wear, hard brushing or acid | Desensitising toothpaste, fluoride treatment, soft brush, treat the cause |
| Grinding-related wear / sensitivity | Teeth grinding (bruxism) wearing down enamel | Night guard, desensitising toothpaste, fluoride, dental review |
| Advanced decay / pulp infection | Untreated cavity reaching the nerve, causing severe pain or abscess | Root canal treatment, or extraction if the tooth cannot be saved |
| Early enamel demineralisation | Frequent sugar/acid exposure starting to soften enamel (often painless) | Fluoride toothpaste, less sugar and snacking, professional fluoride; can reverse |
What tooth decay (dental caries) actually is
Your mouth naturally contains bacteria that form a sticky film called plaque on your teeth. When you eat or drink something sugary or starchy, these plaque bacteria convert the sugar into acid. The acid dissolves the minerals on the surface of the tooth, gradually eroding the hard outer enamel.
If this continues, the enamel breaks down and a small hole, or cavity, forms. Left untreated, decay works deeper into the softer dentine underneath and eventually reaches the tooth’s living centre (the pulp), which contains nerves and blood vessels. Decay tends to start in places where plaque collects and is hard to clean: between teeth, in the grooves of back teeth, around the edges of old fillings, and near the gum line.
Symptoms: how to spot decay early
Early decay is often painless and may only be found by a dentist during a routine check-up or on an X-ray. This is exactly why regular visits matter. As a cavity grows, you may notice:
- Toothache or a dull ache, sometimes coming and going
- Sensitivity or short, sharp pain to sweet, hot or cold food and drinks
- A visible hole, pit, or white, brown or black staining on the tooth
- Pain when biting down
- Bad breath or an unpleasant taste
If decay reaches the pulp, the pain can become severe, throbbing or constant, and an abscess (infection) may form. See a dentist before it gets to this stage.
Sensitive teeth vs. cavities: what's the difference?
Both decay and general tooth sensitivity can make teeth react to sweet, hot or cold, so they are easy to confuse, but they are not the same thing.
General sensitivity (often called dentine hypersensitivity) happens when the protective enamel wears thin, or the gums recede and expose the root surface, leaving the inner dentine open to the outside. Dentine contains tiny tubes that lead to the nerve, so stimuli trigger a brief, sharp twinge. Common causes include gum recession, enamel wear, aggressive or hard brushing, acidic foods and drinks, and teeth grinding (bruxism).
A cavity, by contrast, is active decay destroying tooth structure. Sensitivity from generalised causes usually affects several teeth and eases with the right toothpaste; pain from a cavity tends to be localised to one tooth and worsens over time. If sensitivity lingers, is sharp on biting, or is confined to a single tooth, see a dentist to rule out decay.
Treatment: fillings, sensitivity care, and beyond
For cavities: the standard treatment is a filling. The dentist removes the decayed part of the tooth and fills the hole to restore its shape and function. Common materials are tooth-coloured composite resin (matches the tooth, popular for visible areas) and amalgam (a hard-wearing silver-coloured metal filling). Larger cavities may need a crown to cover and protect the tooth.
For general sensitivity: treatment targets the cause. Options include desensitising toothpaste (containing ingredients such as potassium nitrate or fluoride), in-clinic fluoride treatments or varnishes to strengthen enamel, switching to a soft-bristled brush and gentler technique, cutting back on acidic foods, and a night guard if grinding is the issue.
When decay is advanced: if it has reached the pulp, a filling is no longer enough. The tooth may need root canal treatment (removing the infected pulp and sealing the tooth) or, if it cannot be saved, extraction. Treating decay early keeps it cheap, quick and tooth-saving.
Preventing decay and sensitivity
Most decay is preventable with consistent habits:
- Brush twice a day with fluoride toothpaste (at least 1,000ppm fluoride). Fluoride strengthens enamel and can even reverse very early decay.
- Clean between your teeth daily with floss or interdental brushes to remove plaque your toothbrush misses.
- Cut down on sugary and acidic food and drinks – and on how often you snack. Frequent snacking and sipping sweet or fizzy drinks keeps acid attacking your teeth all day.
- Brush gently with a soft brush to avoid wearing enamel and causing gum recession.
- See a dentist regularly – generally every 6 months – for check-ups, scaling and early detection. Dental sealants can protect the grooves of back teeth in children and adults prone to decay.
In Singapore, community water fluoridation has been in place for decades and supports dental health across the population, and the School Dental Service provides check-ups and basic dental care for schoolchildren.
Costs and financing in Singapore
Filling costs vary with the clinic, the size of the cavity and the material used. As a guide, fillings in private clinics commonly start from around $80 and can range to roughly $200+ per tooth; larger or tooth-coloured composite fillings tend to cost more than small simple ones. Subsidised care is available at polyclinics and public dental institutions such as the National Dental Centre Singapore (NDCS) for Singaporeans.
On financing, note that routine dental care (including fillings) is generally NOT MediSave-claimable – MediSave covers only certain surgical dental procedures (for example, surgical wisdom-tooth removal), subject to MOH rules. However, CHAS subsidies help eligible Singapore Citizen cardholders at participating clinics, with simple fillings subsidised by tier (Blue, Orange, Merdeka Generation, Pioneer Generation) up to a capped number per year. Always confirm current rates and your eligibility with the clinic and the official CHAS schedule.
Related guides
- Best Dental Clinics in Singapore — our editorial shortlist
- dental clinics directory
- Gum disease & periodontitis
- Root canal treatment
- Bad breath (halitosis)
Sources
- HealthHub (HPB) – Dental Caries (Tooth Decay)
- SingHealth – Adult Caries (Tooth Decay)
- MOH – Community Health Assist Scheme (CHAS)
- MOH – Guide to Dental Treatment Costs
- National Dental Centre Singapore (NDCS) – Consultation Charges
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