A person suffering from caries may not be aware of the disease.[12] The first sign of a new carious lesion is the appearance of a chalky white spot on the surface of the tooth, indicating an area of enamel peeling away. This is referred to as a white spot lesion, primary necrotic lesion or “microgravity”.[13] As the lesion continues to demineralise, it can turn brown but will eventually develop into a cavity (“cavity”). Before a cavity forms, the process is reversible, but once a cavity forms, the lost tooth structure cannot be regenerated. A lesion that appears dark brown and shiny indicates that caries was previously present but that the process of demineralization has stopped, leaving a stain. Active decay is lighter in color and dull in appearance. [14]
When the enamel and dentin are destroyed, the cavity becomes more visible. The affected areas of the teeth change color and become soft to the touch. Once the decay has passed through the enamel, the tubules, which have passages to the dental nerve, become exposed, resulting in pain that can be transient, and temporarily worsen with exposure to heat, cold, or sweet foods and drinks.[15] Teeth weakened by extensive internal decay can sometimes suddenly collapse under normal chewing forces. When the decay has advanced enough to allow bacteria to overrun the pulp tissue in the center of the tooth, toothache can occur and the pain becomes more constant. Pulp tissue death and infections are common consequences. The tooth will no longer be sensitive to hot or cold, but it may feel more stressed.
Tooth decay can also cause bad breath and bad tastes.[16] In very advanced cases, infection can spread from the tooth to the surrounding soft tissues. Complications such as cavernous sinus thrombosis and Ludwig’s angina can be life-threatening.[17][18][19]
