Tooth pain from caries usually appears as soon as the damage reaches the dentin, and its intensity increases as it approaches the core of the tooth. While it passes through the enamel, the infection progresses without any symptoms bothering the patient.
It is the pulp that contains nerve endings that are highly sensitive to pain. Faced with some external stimulus such as pressure, cold or heat, the pulp reacts and can irritate for a few seconds after the stimulus is removed.
As dentin is affected by the action of caries bacteria, the inflamed area is larger and the pain may be more intense. This is why it is essential to act as soon as possible, to minimize harm and discomfort to the patient.