Dental cavities (caries) are holes in the two outer layers of a tooth called the enamel and the dentin. The enamel is the outermost white hard surface and the dentin is the tan colored layer just beneath enamel. Both layers serve to protect the inner living tooth tissue called the pulp, where blood vessels and nerves reside. Dental cavities are common, affecting over 90% of the population. Small cavities may not cause pain, and may be unnoticed by the patient. The larger cavities can collect food, and the inner pulp of the affected tooth can become irritated by bacterial toxins, foods that are cold, hot, sour, or sweet-causing toothache. Toothache from these larger cavities is the number one reason for visits to dentists.