Tooth decay occurs due to the formation of plaque on the teeth and gums, notes WebMD. Bacteria in plaque feed on the sugars in the food, making acids that attack the teeth and destroy the enamel.
Acids in plaque cause tiny holes in the enamel, allowing the bacteria and acids to reach the next layer of the teeth, called dentin, which is softer than enamel, explains Mayo Clinic. As the bacteria and acids reach pulp, which is a material that contains nerves and blood vessels, they cause irritation, resulting in swelling, sensitivity and a severe pain. Eating foods high in sugar, not getting enough fluoride, not having enough saliva and not brushing and flossing the teeth regularly may contribute to tooth decay, reports WebMD.