Skeletal remains often show intact teeth, leading to a misconception that teeth are simply another type of bone. While teeth share some similarities with bones, such as their hardness and the presence of calcium, they are distinctly different in their composition and biological properties. This distinction explains why teeth often persist long after other parts of the body, including bones, have deteriorated.
The Unique Composition of Teeth
Teeth are specialized structures composed of four primary tissues: enamel, dentin, cementum, and pulp. Enamel, the outermost layer covering the visible crown of the tooth, is the hardest substance in the human body, even stronger than bone. It consists of approximately 96% minerals, primarily calcium phosphate in the form of hydroxyapatite, with minimal water and organic material. Beneath the enamel lies dentin, which makes up the bulk of the tooth structure. Dentin is similar to bone in composition, containing collagen and calcium phosphate, but it is more porous and less mineralized than enamel.
The root of the tooth is covered by cementum, a bone-like connective tissue that helps anchor the tooth to the jawbone. The innermost part of the tooth is the pulp, a soft tissue containing nerves, blood vessels, and connective tissue. Unlike bone, which has bone marrow and can regenerate, enamel is not a living tissue and cannot repair itself once significantly damaged. Dentin has limited regenerative abilities, but teeth lack the extensive self-repair mechanisms found in bones.
Why Teeth Endure
The durability of teeth, particularly their enamel layer, contributes to their longevity in skeletal remains. Enamel’s high mineral content and dense crystalline structure make it highly resistant to physical wear and chemical degradation. This dense, non-living outer layer acts as a barrier, protecting the softer internal tissues from decay-causing bacteria and environmental factors.
Teeth are less susceptible to microbial degradation than bone because their most mineralized parts, like enamel, lack living cells and blood supply, making them less appealing as a food source for microorganisms. Their inherent density and protective layers allow them to withstand conditions such as fire, water, and natural disasters, often remaining intact even when other soft tissues and bones have decomposed. The resilience of teeth makes them valuable for forensic identification, as they can provide unique information long after other evidence has vanished.
Teeth and the Skeletal System
While teeth are not bones, they are functionally integrated with the skeletal system, specifically embedded within the jawbones (the maxilla and mandible). They are held firmly in their sockets by a specialized connective tissue called the periodontal ligament, which also acts as a shock absorber. This attachment provides stability for their primary roles in the body.
Teeth are essential for mastication, the mechanical breakdown of food, which is the first step in digestion. They also play a role in speech articulation, helping to form various sounds clearly. Furthermore, teeth contribute to maintaining the structural integrity and shape of the face.