To understand how a cavity works, we need to have a basic understanding
of the anatomy of the tooth. A tooth is composed of several layers. The outermost
layer (above the gum-line) is called the enamel. Enamel is the hardest
and most mineralized substance in the body. Beneath the gum-line, a substance
called cementum covers the tooth roots. Under the enamel and cementum
is the dentin. The dentin is about as hard as bone, and, unlike the
enamel, dentin contains nerve endings. Beneath the dentin is the dental
pulp. The pulp is a vascular tissue, composed of capillaries, larger
blood vessels, connective tissue, nerve fibers, and cells including odontoblasts,
fibroblasts, macrophages, and lymphocytes. The pulp is needed to nourish
the tooth during its growth and development. After a tooth is fully mature,
the only function of the pulp is to let us know if it is damaged or infected
by transmitting pain.
