Signs of Tooth Decay

Signs of tooth decay are findings that may suggest mineral loss in tooth tissue or progression of decay. Discolouration, a cavity, food trapping, sensitivity or pain may occur, but early decay can be symptom-free. The cause of these findings is determined through clinical examination and, when needed, radiological imaging.

Summary: Tooth decay is a disease in which repeated acid exposure damages the mineral structure of teeth. White, brown or dark areas, sensitivity, cavities or pain when chewing are possible signs. These signs alone do not indicate the depth of decay. The disappearance of pain does not mean the problem has resolved; when the pulp loses vitality, infection may progress as pain subsides. Rapidly increasing swelling, difficulty breathing or the other warning signs described below require emergency help.

What Is Tooth Decay and How Does It Develop?

Tooth decay develops when acids produced by oral bacteria from fermentable carbohydrates cause loss of minerals from the tooth structure. The process depends on the balance between dental plaque, eating frequency, saliva’s protective effect, fluoride exposure and oral care. A single symptom does not show how far the process has progressed.

Dental plaque on the tooth surface produces acid when exposed to foods containing sugar or starch. Saliva helps restore balance in the mouth and replace some lost minerals. When acid exposure becomes frequent, mineral loss may predominate.

The main contributing conditions include:

• Dental plaque remaining on tooth surfaces for long periods
• Eating sugary or starchy foods throughout the day
• Dry mouth or reduced protective action of saliva
• Inadequate cleaning between teeth
• Previous decay or oral conditions that make cleaning difficult
• Insufficient use of fluoride according to individual needs

Initially, minerals may be lost without collapse of the surface. If the process continues, enamel integrity may be compromised and dentine affected. The need to view decay as a dynamic disease process is discussed in Dental caries: an updated medical model of risk assessment (2014; PMID 24331852).

What Are the Signs of Tooth Decay?

Signs of tooth decay may include sensitivity to hot, cold or sweet foods, discolouration, surface loss, food trapping, discomfort when chewing or spontaneous pain. Early lesions may be completely symptom-free. During clinical assessment, the dentist distinguishes the causes, significance and relationships of these findings.

Possible findings include:

• A white, dull, brown or dark area
• Roughness or a visible cavity on the tooth surface
• Sensitivity to hot, cold, sweet or acidic foods
• Pain in a specific area when biting or chewing
• Food repeatedly collecting in the same place
• Dental floss catching or fraying in a particular area
• An unpleasant taste that persists despite oral care
• Pain that starts without a trigger or interrupts sleep

Prevalence of dentin hypersensitivity: Systematic review and meta-analysis assessed the prevalence of dentine hypersensitivity in different populations (2019; PMID 30639724). The study was not designed to determine the cause of sensitivity on its own. Decay should therefore not be diagnosed at home from symptoms; clinical differentiation should be left to the dentist.

Can a Decayed Tooth Be Noticed If It Does Not Hurt?

A painless decayed tooth may sometimes be noticed through a change in colour or surface, but changes where teeth touch may not be visible externally. Absence of pain does not rule out decay or prove that it remains superficial. Symptom-free areas are assessed through clinical examination and, when needed, radiological imaging.

Changes that may be noticed include:

• New dull, white or dark areas
• Food repeatedly getting stuck in the same area
• Dental floss consistently fraying at a particular point
• Surface collapse, breakage or a cavity
• A new change in colour or integrity at the edge of a filling

These observations provide information to share at an examination, but are not a home test. The dentist determines the nature and activity of the area. Radiographs may help assess the surfaces where teeth meet. The need for imaging depends on individual findings (Radiology of Dental Caries, 2021; PMID 34051924).

How Does Tooth Decay Progress?

Decay may progress from initial mineral loss to disruption of enamel integrity, involvement of dentine and then deeper tissues. These stages are not intended for classifying your own condition. The dentist assesses the extent and activity of the change and the appropriate course of action based on examination findings.

Findings do not necessarily follow a fixed sequence and cannot be used to determine the stage at home. Progression is not equally rapid in every person or tooth; individual risk factors and the lesion’s clinical features are assessed together.

Pain may suddenly lessen or disappear completely. This is not proof of healing. When the pulp becomes necrotic, meaning the tooth’s living tissue loses vitality, pain may stop while infection silently spreads around the root and into neighbouring tissues. Do not cancel a scheduled assessment solely because the pain has gone.

Where Can Pain from Tooth Decay Spread?

Pain associated with decay may be felt in neighbouring teeth, the jaw, around the ear, the temple or the face. Because pain can be referred, the place where it is felt does not always identify the source tooth correctly. The area to which pain spreads does not prove the depth of decay either; its source is determined by examination and, when needed, imaging.

Pain may be perceived in the following areas:

• Neighbouring teeth in the same row
• Along the upper or lower jaw
• Around the ear
• The temple or head
• The cheek or a particular part of the face

Similar symptoms can arise from different mechanisms involving the mouth, jaw, sinuses or ear. Patients cannot reliably make this distinction themselves. The dentist considers the onset, location, spread and triggers of pain, together with accompanying findings and a clinical examination.

How Is Tooth Decay Diagnosed?

Decay is diagnosed by jointly assessing health history, oral examination, the characteristics of the suspicious area and individual caries risk. Radiological imaging may be needed for spaces between teeth that cannot be seen directly or areas around existing restorations. Pain, discolouration or an image alone may not provide a definitive answer.

Assessment may include:

• Colour and tissue integrity of tooth surfaces
• The presence of cavities or loss of tooth substance
• Clinical features of the suspicious area
• The onset and course of sensitivity
• Previous decay, oral care and eating habits
• Individual conditions that may affect saliva production
• Agreement between imaging findings, if available, and the examination

The role of radiological assessment is discussed in Radiology of Dental Caries (2021; PMID 34051924). The approach to clinical assessment of lesion activity is described in Organization for Caries Research-European Federation of Conservative Dentistry Consensus Report on Clinical Recommendations for Caries Diagnosis Paper II: Caries Lesion Activity and Progression Assessment (2024; PMID 38684147).

How Are Treatment Options Assessed?

Treatment options are not determined solely by visible colour or the description of pain. The dentist considers tissue loss, lesion activity, pulp condition, whether the tooth can be preserved and individual risk factors together. For readers, the key decision is to clarify the reasons for the options, their limitations and follow-up needs during an examination, rather than to choose a method themselves.

General information about fillings, without procedural steps, is available on the dental fillings service page. Minimal intervention aims to preserve as much healthy tissue as possible (Minimal intervention dentistry for managing dental caries – a review: report of a FDI task group, 2012; PMID 23106836).

No method suits everyone, and a definite outcome cannot be guaranteed. Interventional options may have limitations such as sensitivity, effects on the pulp, the need to reassess the restoration later or an inability to preserve the tooth. The significance of these possibilities varies with individual circumstances; suitability is determined by clinical examination and, when needed, radiological imaging.

What Can Be Done to Reduce the Risk of Tooth Decay?

Reducing decay risk involves regular brushing, cleaning between teeth, using fluoride according to individual needs and limiting how often sugary foods are consumed. These measures may reduce risk, but they do not repair existing tissue loss at home or remove the need for professional assessment of a current symptom.

The following points matter in daily care:

• Brush tooth surfaces regularly and carefully
• Clean between teeth with an appropriate tool
• Avoid frequent sugary snacks throughout the day
• Avoid sipping sugary drinks over long periods
• Avoid sugary foods after your nightly oral care
• Supervise children’s oral care
• Report dry mouth or conditions that make cleaning difficult at your examination

Scraping decay with a sharp tool, trying to clean a cavity at home or placing chemicals on a tooth may damage tooth tissue or gums. Early childhood caries affecting baby teeth also requires assessment (Early Childhood Caries, 2018; PMID 30213355).

When to Contact Your Doctor

Discolouration, a cavity, recurring sensitivity, pain when chewing, an unpleasant taste or spontaneous pain requires dental assessment. Any one of the findings below is enough to seek care. Call 112 or go to the nearest emergency department for signs of airway risk, spreading infection, persistent bleeding or serious trauma.

Call 112 or go to the nearest emergency department immediately

One or more of the following is sufficient:

• Rapidly increasing facial swelling.
• Rapidly increasing swelling beneath the jaw.
• Rapidly increasing neck swelling.
• Difficulty breathing.
• Difficulty swallowing.
• A change in voice.
• Inability to open the mouth. This poses an airway risk; do not wait.
• Swelling spreading around the eye.
• Swelling spreading to the neck.
• Fever.
• Chills.
• Deterioration in general condition.
• Bleeding that does not stop despite pressure, including bleeding after tooth extraction.
• A changed bite after facial or jaw trauma.
• Inability to move the jaw after facial or jaw trauma.
• Suspected jaw fracture.
• Loss of consciousness after trauma.
• Vomiting after trauma.
• Dizziness after trauma. This requires emergency assessment for a possible head injury.

Assessment on the same day or without delay

One or more of the following is sufficient:

• A tooth completely knocked out by trauma. Time is critical; do not wait until morning. If you are unsure whether it is a baby or permanent tooth, do not delay while trying to distinguish them. Do not dry the tooth; hold it by the crown, do not rub the root surface and do not let it dry during transport.
• A broken tooth.
• A cracked tooth.
• A displaced tooth.
• A bump on the gum.
• Discharge on the gum.
• A persistent unpleasant taste in the mouth.
• Persistent bad breath.
• Swelling inside the mouth.
• Toothache that interrupts sleep.
• Progressively worsening toothache.
• A filling falling out.
• A crown falling out.
• A bridge falling out.
• An orthodontic wire poking into tissue.
• Injury from an orthodontic wire.
• A non-healing mouth sore lasting longer than two weeks.
• A white patch in the mouth lasting longer than two weeks.
• A red patch in the mouth lasting longer than two weeks.
• An area of firmness in the mouth lasting longer than two weeks.
• Gum bleeding unrelated to brushing.
• Loose teeth.
• Widening gaps between teeth.
• Jaw joint locking.

Reduced pain does not remove the need for assessment. Pain may stop when the pulp loses vitality, while infection continues to progress.

How Can You Prepare for the Examination?

Before your examination, noting when symptoms began, what triggers pain, whether it arises spontaneously and previous treatments can help the assessment. Tell the dentist about medicines, known illnesses, pregnancy, allergies and any existing radiological images. This information does not replace diagnosis.

Questions you can ask the dentist include:

• What could cause these findings apart from decay?
• What do the clinical features of the suspicious area indicate?
• Why is radiological imaging considered necessary or unnecessary?
• How was the extent of tissue loss assessed?
• What options are available to preserve the tooth?
• What are the limitations and possible risks of each option?
• Which changes matter if assessment is delayed?
• Which conditions affect my individual risk of decay?
• Which findings will determine the review interval?

Planning is individual. The scope, limitations and feasibility of the options are considered according to personal circumstances after the necessary examination is complete.

Frequently asked questions

Frequently asked questions about decay usually concern the spread of pain, progression, causes in children and possible home treatment. The answers below offer general information to support decisions; they do not establish the diagnosis, tissue involvement or treatment needs of a particular tooth on their own.

Where can pain from tooth decay spread?

Pain associated with decay may be felt in neighbouring teeth, the jaw, around the ear, the temple or the face. Referred pain means the affected tooth cannot be identified solely by where pain is felt. Clinical examination and, when needed, radiological imaging are required to distinguish the source; the spread of pain alone does not indicate the depth of decay.

What can happen if decay becomes very advanced?

Progressing decay may affect dentine, the pulp or tissues around the root; spontaneous pain, discharge, swelling or loss of tooth tissue may develop. Even if pain later disappears, the problem is not necessarily resolved; infection may progress silently after pulp necrosis. The appropriate option is determined by examination and, when needed, radiological imaging.

What problems can tooth decay cause?

Decay can cause sensitivity, food trapping, discomfort when chewing, an unpleasant taste, tissue loss or spontaneous pain. Discharge or swelling may occur as the process spreads to surrounding tissues. Because other oral and dental problems can cause the same symptoms, a dentist should assess their cause and significance.

Why can tooth decay develop in two-year-old children?

In young children, frequent sugar exposure, inadequate oral care after night feeds and limited adult support can affect decay risk. Saliva, tooth structure and eating habits are also assessed. Decay in baby teeth should not be dismissed; the approach should be determined by examination.

How can early tooth decay be recognised?

Early decay may sometimes appear as a dull or white area on a tooth surface, or cause no symptoms at all. A brown appearance or sensitivity alone does not establish active decay. The dentist assesses the surface, activity and progression risk of an early change during clinical examination.

Can tooth decay be cleaned out at home?

Decay cannot be treated at home by scraping it, cleaning it with a sharp object or placing chemicals on the tooth. Such attempts can damage healthy tissue or gums. Regular oral care helps reduce the risk of further mineral loss, but a dentist determines the state of existing tissue loss and the appropriate approach.

What happens if a decayed tooth is not extracted?

Not every decayed tooth needs extraction; whether it can be preserved depends on assessment of the remaining tissue, pulp and surrounding tissues. Decay progressing without assessment may cause pain, infection, an abscess or further tissue loss. Disappearance of pain does not prove healing or remove the need for a planned assessment.

References

The studies below were used for the disease model of decay, radiological assessment, lesion activity, the prevalence of dentine hypersensitivity across populations and childhood caries. These sources do not provide an individual diagnosis or recommend a specific treatment. Clinical decisions are based on examination findings and, when needed, radiological imaging.

• Early Childhood Caries (2018). PMID 30213355.
• Dental caries: an updated medical model of risk assessment (2014). PMID 24331852.
• Prevalence of dentin hypersensitivity: Systematic review and meta-analysis (2019). PMID 30639724.
• Radiology of Dental Caries (2021). PMID 34051924.
• Organization for Caries Research-European Federation of Conservative Dentistry Consensus Report on Clinical Recommendations for Caries Diagnosis Paper II: Caries Lesion Activity and Progression Assessment (2024). PMID 38684147.
• Minimal intervention dentistry for managing dental caries – a review: report of a FDI task group (2012). PMID 23106836.

This information is for educational purposes and does not replace diagnosis and treatment. Please consult your doctor about your symptoms.