What Is a Cavity?
A cavity forms when tooth decay — caused by acid-producing bacteria in dental plaque — progresses to the point where the hard structure of the tooth physically breaks down. Plaque is a sticky film that continuously forms on the tooth surface. When sugars from food and drink are consumed, the bacteria in plaque produce acids that dissolve minerals from the enamel, the tooth's protective outer layer.
If this process continues unchecked, the enamel weakens and eventually gives way, creating a hole — or cavity — in the tooth. Once through the enamel, decay can progress more rapidly into the softer dentine layer beneath. Dentine contains microscopic channels that communicate with the tooth's nerve, which is why sensitivity and pain often develop as a cavity deepens.
A cavity represents structural damage to the tooth that cannot repair itself. Unlike very early enamel changes, which may stabilise with preventive care, an established cavity requires professional treatment — typically a filling — to remove the decayed material and restore the tooth's shape and function.
Common Causes of Cavities
Several factors can increase the likelihood of cavities developing. Individual risk varies, and more than one factor is often involved:
Frequent Sugary or Acidic Foods and Drinks
Each time sugar is consumed, plaque bacteria produce acids that attack the enamel. Frequent snacking or sipping on sugary or acidic drinks throughout the day increases the total duration of acid exposure.
Inadequate Brushing and Flossing
When plaque is not removed thoroughly through regular brushing and interdental cleaning, bacteria remain on the tooth surface and continue producing enamel-weakening acids.
Dry Mouth
Saliva helps neutralise acids and wash away food particles. Reduced saliva flow — whether caused by medication, medical conditions, or other factors — diminishes this natural protection and increases cavity risk.
Deep Grooves in Teeth
The natural pits and fissures on the chewing surfaces of back teeth can trap plaque and food debris in areas that are difficult to clean effectively with a toothbrush.
Irregular Dental Check-ups
Without routine professional assessment, early signs of enamel weakening may go undetected, allowing decay to progress to a stage where a cavity forms.
Early Signs and Symptoms
In the earliest stages, cavities may not produce any obvious symptoms. When signs do appear, they are often subtle:
White, Brown, or Dark Spots
Early mineral loss may appear as a chalky white patch on the enamel. As the area progresses, it can darken to brown or black — though not all discolouration indicates an active cavity.
Mild Sensitivity
A brief twinge when consuming sweet or acidic foods may indicate that enamel integrity is beginning to change, even before a visible hole has formed.
No Noticeable Symptoms
In many cases, early cavities produce no discomfort at all. This is why routine dental assessments are valuable — they can detect changes that are not yet causing symptoms.
Symptoms of Advanced Cavities
As a cavity enlarges and reaches deeper layers of the tooth, more noticeable symptoms tend to develop:
Visible Hole in the Tooth
A cavity that can be seen or felt with the tongue indicates that the tooth structure has physically broken down and professional restoration is needed.
Persistent Toothache
Continuous or recurring pain in or around the affected tooth often suggests that the cavity has progressed into the deeper layers of the tooth.
Sensitivity to Hot or Cold
Lingering discomfort after exposure to hot or cold foods and drinks may indicate that the cavity is approaching or has reached the dentine or pulp.
Pain When Chewing
Discomfort when biting down or chewing can occur as the cavity weakens the tooth structure, making it less able to withstand normal biting forces.
Food Getting Trapped
A cavity can create a space where food regularly becomes lodged, which may also accelerate further decay in the area if not addressed.
The presence of these symptoms does not necessarily indicate the tooth cannot be saved. Professional assessment will determine the most appropriate treatment.
Why Professional Assessment Is Important
Once a cavity has formed, it cannot repair itself. The damaged area will generally continue to enlarge if left untreated, eventually affecting deeper layers of the tooth. Early intervention — when the cavity is still small — typically preserves more of the natural tooth structure and allows for a simpler, more conservative restoration.
Cavities are not always visible to the naked eye, particularly when they develop between teeth or beneath existing restorations. Dental imaging, such as X-rays, may be used alongside clinical examination to determine the full extent of the decay and guide treatment planning.
Without timely treatment, a cavity can progress to the point where the dental pulp becomes involved, potentially leading to infection and the need for more complex procedures such as root canal treatment. In some cases, extensive decay may mean the tooth cannot be predictably restored. Regular dental check-ups help to avoid these outcomes wherever possible.
Professional Treatment for Cavities
Treatment for a cavity depends on its size, location, and the extent to which the tooth structure has been affected. Your dentist will recommend the most appropriate approach following assessment:
Dental Fillings
The most common treatment for cavities. The decayed material is carefully removed and the resulting space is filled with a durable restorative material to rebuild the tooth's structure and function.
Replacement of Old Fillings
Existing fillings that have worn, cracked, or developed recurrent decay around their margins may need to be replaced to ensure the tooth remains properly sealed and protected.
Root Canal Treatment
If decay has reached the dental pulp — the soft tissue containing nerves and blood vessels — root canal treatment removes the infected tissue and preserves the outer tooth structure.
Dental Crowns
For teeth with large cavities or significant structural loss, a crown provides a full-coverage restoration that protects and strengthens the remaining tooth.
Tooth Extraction
In cases where the tooth is too extensively damaged to be predictably restored, extraction may be recommended. Your dentist will discuss replacement options where appropriate.
Treatment outcomes depend on individual circumstances. Your dentist will discuss what can reasonably be expected based on the specific findings.
Professional Care for Cavities
Professional dental assessment ensures cavities are properly evaluated and restored to protect long-term oral health. Whether you have noticed a new symptom or simply want a routine review, your dentist can assess the situation and discuss the most appropriate course of action.
Depending on the findings, your dentist may recommend a dental filling, root canal treatment if infection has developed, a protective dental crown for extensive damage, or an emergency dental assessment if symptoms are severe.
Assessment and treatment for cavities are available at our London clinics. You can attend our South Kensington dental clinic or our City of London clinic near St Paul's for a professional dental review.
Can Cavities Heal on Their Own?
In the very earliest stages of the decay process — before a cavity has physically formed — mineral loss from the enamel may stabilise or partially reverse with consistent preventive care. This includes effective oral hygiene, reduced sugar exposure, and adequate fluoride, which supports the natural remineralisation of weakened enamel.
However, once the tooth structure has broken down and a cavity is present, the damage is permanent. The tooth cannot regenerate the lost material, and the cavity will typically continue to enlarge without professional treatment. A filling or other restoration is needed to remove the decayed tissue and rebuild the tooth.
Regular dental check-ups are valuable because they allow your dentist to identify early enamel changes and advise on whether preventive measures are sufficient, or whether active treatment is the most appropriate step.
Preventing Cavities
While individual susceptibility varies, the following habits can help reduce your risk of developing cavities:
- Brush twice daily with a fluoride toothpaste, spending at least two minutes each time
- Clean between teeth daily using floss or interdental brushes to remove plaque from areas a toothbrush cannot reach
- Limit the frequency of sugary snacks and drinks — it is the frequency of sugar intake, not just the amount, that matters
- Drink water regularly to support saliva flow and help rinse food particles from the teeth
- Attend routine dental check-ups so that early signs of decay can be identified before a cavity develops
- Ask your dentist about professional cleaning if plaque or tartar build-up is a concern
