Tooth dentin is a vital, yellowish, bone-like tissue that forms the bulk of the tooth and is located beneath the harder, outer layer of enamel in the crown, and cementum in the root.
It provides structural support and essential resilience to the brittle enamel, helping it withstand the forces of chewing.
By weight, dentin is composed of approximately 70% inorganic material (primarily hydroxyapatite crystals), 20% organic material (mostly Type I collagen fibers), and 10% water. This composition makes it less mineralized and softer than enamel but harder than bone.
A distinguishing feature of dentin is the presence of thousands of microscopic channels called dentinal tubules that radiate outwards from the central pulp cavity to the dentin's outer border.
These tubules contain fluid and extensions of the odontoblast cells, which are the cells responsible for forming dentin. When the protective enamel or cementum covering is lost, external stimuli like hot, cold, or sweet substances can cause the fluid within these tubules to move, stimulating the nerves in the pulp and resulting in the sensation of pain or sensitivity.
Unlike enamel, dentin is considered a living, or vital, tissue because it contains living cell processes and can form new dentin throughout life in response to injury or decay (known as tertiary or reparative dentin).
Dentin plays a critical role in tooth health by acting as a protective layer for the sensitive innermost pulp, which contains the tooth's nerves and blood vessels.
Dentin gets decayed when the protective outer layers of the tooth (enamel or cementum) are compromised, allowing acid-producing bacteria to invade its softer, less mineralized structure. Once decay reaches the dentin, it spreads more quickly because dentin is softer than enamel.
The lower mineral content and the presence of these tubules mean the acid and bacteria can spread more rapidly through the dentin than through the enamel. This can quickly lead to infection of the pulp, severe pain, and potentially a dental abscess.
No, dentin decay cannot be reversed with home care or natural methods once a physical cavity (hole) has formed and broken through the protective outer enamel layer.
While dentin is a living tissue and can form a thin protective layer of "reparative dentin" (tertiary dentin) in response to irritation, this is not enough to stop or fully heal a large cavity.
Treatment depends entirely on how far the decay has progressed:
- Fillings: For typical cavities where the decay is limited to the dentin, the dentist will remove the decayed material and fill the hole with a material like composite resin or amalgam.
- Root Canal Therapy: If the decay has advanced deep enough to infect the pulp (the tooth's nerve center), a root canal procedure is necessary to remove the infected pulp and save the tooth.