The Tooth and Nothing But the Tooth

September 2009

By: Dr. Scott R. Harden

Teeth form by an amazing complex process of embryonic cells that develop and interrelate to ultimately form the tooth, its roots and connection to the bone. The top of the tooth forms first and then the roots form second. The tooth has four key elements. The outside armor coating of “enamel”. The next layer is what causes your tooth to appear yellow, called “dentin”. The nerve supply of your tooth is the “pulp”. Lastly, the tooth connects to the bone through a thin layer on the root called “cementum”.

Enamel is the hardest substance of the body, and is composed of proteins not found anywhere else in the body. Mature enamel has no cells and is not alive. Enamel is made up of a high concentration of minerals (calcium salts mostly) that cause it to be very hard and resistant to bacterial attack. Enamel provides an amazing defense to bacteria. The weakest areas of enamel are the grooves and pits in our teeth (especially back teeth) that are best protected by good daily brushing, fluoride and sealants.

Dentin forms prior to the formation of enamel and is initiated by dentin-producing cells called “odontoblasts” located in the pulp. Unlike enamel, dentin continues to form throughout life and can be initiated in response to stimuli, such as tooth decay or attrition. Dentin consists of microscopic channels, called “dentinal tubules” (like little straws) that spread outward through the dentin from the pulp to the exterior cementum or enamel border. These tubules contain fluid and therefore cause dentin to have a degree of permeability that can increase the sensation of pain and the rate of tooth decay. Dentin consists of “primary dentin” that forms most of the tooth when you are young, “secondary dentin” that forms after root development and much slower than primary dentin and “tertiary dentin” that is an on-going reparative process throughout life in response to decay and other damaging etiologies.

The pulp is what we term the “nerve” in our teeth and is comprised of arteries, veins and nerves. God gives each tooth a root canal system to transport the pulp through (as seen in the photo above). The slang “root canal” actually refers to root canal therapy, which is performed by a dentist, and involves the removal of the nerve because it has died and become infected from bacteria. When there is a problem involving a tooth, the pulp transfers feeling from your tooth to your brain to let your know there is a dental problem. Tooth decay does not always create a toothache, because tooth decay is very slow and gradual, the body adapts to the problem and often disguises the pain so we do not get a signal. This explains why severely broken down teeth sometimes never hurt.

Cementum is a thin layer of bonelike material covering the roots, that helps your tooth attach to the bone. It is yellowish and softer than either dentin or enamel. Cementum is similar to dentin in the fact that they are both produced by the body throughout your life, especially in response to stresses. In humans, as your teeth wear down from chewing or grinding, new cementum is deposited on the roots (down in the bone area) so that the tooth gradually rises higher and maintains good tooth function.