What causes a nerve to become damaged or die?
It may be from a cavity where the decay has penetrated the enamel and dentin and has reached the nerve. Once the nerve is exposed to the toxins and bacteria in the decay, the nerve becomes progressively irritated until symptoms occur (usually pain to cold or heat). If left untreated, the nerve will always die and decompose. Other causes of irritation to a nerve are: trauma, such as a blow; heat and vibration from the drill during routine dental procedures like fillings and crowns; advanced periodontal disease; rapid orthodontic movement, etc. The irritation causes inflammation and pressure inside the nerve canal (nerves at this stage hurt to cold and/or heat). If the pressure from the swelling inside the nerve is great enough, the flow of blood (and the oxygen it carries) to the nerve is interrupted and the nerve begins to die.
