The question of whether human teeth are ivory is common, and the simple answer is no, though the two share a major biological component. The confusion is understandable because the structural materials are closely related in chemical makeup and originate as mineralized connective tissues. While a tooth is a complex organ with several distinct layers, ivory is defined as a specific material that forms the bulk of certain animal tusks.
What Defines Ivory
Ivory is defined as a hard, white material derived from the tusks and teeth of animals, consisting almost entirely of dentin. This material is primarily associated with the elongated incisors of mammals like elephants, walruses, and narwhals. Chemically, ivory is a biomineral composite composed of an organic matrix mineralized with inorganic compounds. By weight, it is approximately 70% mineral (calcium hydroxyapatite), 20% organic materials, and 10% water.
The Core Material of Human Teeth
The reason human teeth are compared to ivory lies in their core structure, which is composed of a yellowish tissue called dentin. Dentin forms the vast majority of the tooth, surrounding the central pulp cavity that contains nerves and blood vessels. This dentin layer is chemically and structurally analogous to the material that constitutes ivory tusks. Like ivory, human dentin is composed of approximately 70% inorganic hydroxyapatite crystals, 20% organic components, and 10% water.
The organic component of dentin is largely Type I collagen, which provides elasticity necessary to support the tooth’s outer shell and prevent fracture. This combination of mineralized collagen gives dentin its bone-like density and the yellowish hue visible beneath the outer layer. Dentin is considerably softer than the outermost layer of a human tooth, rating about 3 on the Mohs scale of hardness. This elasticity allows it to absorb and distribute the forces generated during chewing.
The Protective Outer Layer
The difference that distinguishes a human tooth from pure ivory is the presence of the highly mineralized outer layer known as enamel. Enamel covers the crown and serves as the primary protective barrier against the physical and chemical stresses of the mouth. This tissue is the hardest substance in the human body due to its high mineral content.
Enamel is composed of about 96% mineral, almost entirely hydroxyapatite, with only about 4% organic material and water remaining. This greater proportion of mineral content makes it harder and more brittle than the underlying dentin. Most ivory tusks are essentially exposed dentin, or they may have only a thin layer of enamel at the tip that quickly wears away. The presence of this dense, non-renewable enamel cap is the structural feature that makes a human tooth different from the material recognized as ivory.