Dentine
Dentine is a calcified tissue that forms the structural bulk of teeth in vertebrates, lying beneath the outer enamel layer. Composed primarily of mineral crystals embedded within an organic matrix of collagen and other proteins, dentine occupies an intermediate position in hardness between bone and enamel. It is less mineralized than enamel but more heavily mineralized than bone, resulting in a material that is harder than bone yet retains greater flexibility than enamel.
Structure and Composition
The tissue is characterized by microscopic tubules that radiate outward from the inner pulp chamber toward the outer surface of the tooth. These tubules contain fluid and extensions of odontoblast cells, which are responsible for dentine formation and maintenance. The organic matrix provides resilience, while the mineral component contributes hardness, creating a composite material well-suited to the mechanical demands of mastication.
Biological Function
Throughout vertebrate evolution, dentine has been a fundamental component of tooth structure, with variations in mineralization and tubule density reflecting adaptations to different diets and feeding strategies. The tissue remains metabolically active throughout life, allowing for continuous remodeling and repair responses to damage. When enamel is worn or damaged, exposed dentine becomes sensitive to temperature, pressure, and chemical stimuli due to the fluid-filled tubules communicating with the pulp chamber.