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Tooth decay. Signs and symptoms

author icon By Dr. George Ghidrai


A person experiencing caries may not be aware of the disease, particularly when cavities are small and the decay acts only upon the enamel. Enamel does not contain any blood vessels or nerves; therefore, enamel damage is painless.

Once the decay passes through enamel, the dentinal tubules, which have passages to the nerve of the tooth, become exposed, resulting in pain that can be transient or more pronounced (this varies from individual to individual).

Tooth sensitivity may temporarily worsen with exposure to heat, cold, or sweet foods and drinks.

tooth decay enamel

small decay that affects only the enamel

tooth decay dentin

a larger decay that has passed the enamel and affects the dentin

Large cavities can hold food fragments and may cause bad breath and foul tastes.

When the decay has progressed enough to allow the bacteria to penetrate the pulp tissue, a toothache can result and the pain will become more constant. This condition is called pulpitis and involves the inflammation of the pulp tissue.

dental decay progression

dental decay progression

Clinical signs

The earliest sign of a new carious lesion is the appearance of a chalky white spot on the surface of the tooth (image below), indicating an area of demineralization of enamel.

early tooth decay

As the lesion continues to progress, it can turn brown and it will eventually turn into a "cavity".

Before the cavity forms, the process can be reversible: a lesion that appears dark brown and shiny and is hard to the touch suggests dental caries were once present but the demineralization process has stopped, leaving a stain (image below).

a dental decay was once present but the demineralization process has stopped

As the enamel and dentin are destroyed, the cavity becomes more noticeable.

cavity becomes noticeable

cavity becomes noticeable

The affected areas of the tooth change color and become soft to the touch. A tooth weakened by extensive internal decay can sometimes suddenly fracture under normal chewing forces

large cavity with advance tooth destructions

large cavity with advance tooth destructions

Medical examination

Initially, decay may appear as a small chalky area, which may eventually develop into a large cavitation. Sometimes, caries may be directly visible or they are felt by the patient.

Primary diagnosis involves visual and tactile inspection (palpation) of all visible tooth surfaces using a good light source, dental mirror, and explorer. Large cavities are often apparent to the naked eye, but smaller lesions can be difficult to identify.

A dental X-ray may show dental caries before it is otherwise visible, particularly when the decay is small or it is located between the teeth. Generally, a bitewing radiograph can best identify hidden lesions.

visual and tactile inspection using a dental mirror and explorer

visual and tactile inspection
using a dental mirror and explorer

dental decay on bitewing x-ray

a bitewing radiograph can be used
to detect decays between teeth

At times, pit and fissure caries may be difficult to detect. Bacteria can penetrate the enamel to reach dentin, but then the outer surface may remineralize. The consequence is that visual examination of the tooth would show the enamel intact or minimally perforated.

However, these caries will still be visible on dental x-rays.


  1. Dental pulp infections

    Dental pulp infections (also known as pulpitis) are mainly caused by bacteria from dental caries that penetrate through the enamel and dentin and reach the pulp.

    Pulp infections that are not properly treated will spread in the surrounding periapical tissues leading to acute or chronic inflammatory lesions (also known as apical periodontitis).

    dental decay progression in the periapical tissue

    a dental decay can gradually lead
    to infections in the surrounding tissues

    These infections can develop into dental abscesses or can lead to the infection and subsequent resorption of the bone that surrounds the tooth (which will eventually result in tooth loss).

  2. Destruction of the hard tissues of the teeth

    In advanced stages, dental decays can cause massive demineralization and destruction of the hard tissues of the teeth. If extensive loss of tooth structure occurs, the tooth will be no longer restorable.

    In these situations, even if infection is not very advanced, extraction may be the only treatment option.

Last review and update: August 2021

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