While teeth do not “burn” in the same manner as organic materials like wood or paper, they are significantly altered by intense heat. Unlike other body tissues, teeth exhibit remarkable resistance to fire and extreme temperatures, undergoing physical and chemical changes instead of complete combustion. This unique resistance stems from their distinct composition, enabling them to survive conditions that destroy most other biological structures.
The Unique Makeup of Teeth
Teeth consist of specialized tissues that contribute to their durability. Enamel, the crown’s outermost layer, is the hardest human substance. It is approximately 96% inorganic material, mainly hydroxyapatite, making it dense and degradation-resistant.
Beneath enamel is dentin, forming the tooth’s bulk. Dentin is about 70% inorganic material, 20% organic (mostly collagen), and 10% water. Though softer than enamel, it provides significant strength. The tooth’s core contains the pulp, a soft tissue with nerves, blood vessels, and connective tissue. This organic-rich pulp is the most vulnerable part of the tooth to heat damage.
Teeth’s Response to Intense Heat
When exposed to intense heat, teeth undergo a predictable sequence of changes. Water content initially evaporates, causing dehydration and shrinkage. This loss of moisture can lead to cracks as tooth components expand and contract at varying rates, potentially causing the tooth to fragment.
As temperatures increase, organic components within the dentin and pulp begin to char, leading to distinct color changes. Teeth may progress from their natural white to yellow, then brown, and eventually black. At even higher temperatures, typically above 600°C (1112°F), the organic matter is completely consumed in a process called calcination, leaving behind a brittle, chalky white or gray mineral residue. While teeth are highly resistant, prolonged exposure to extremely high temperatures, such as those exceeding 1200°C (2192°F), can eventually cause some melting or pulverization of the mineral components. However, this level of destruction requires conditions rarely encountered outside of specialized laboratory settings.
Their Role in Identification
Teeth’s remarkable heat resistance makes them invaluable in forensic science, particularly in cases involving severe fires or mass disasters where other forms of identification are compromised. They are often among the last biological structures to survive such incidents. Their unique characteristics, including individual tooth morphology and any existing dental work like fillings, crowns, or root canal treatments, remain largely intact even after significant heat exposure.
Forensic odontologists compare these post-mortem dental features with ante-mortem (pre-death) dental records, including X-rays and dental charts, to establish a positive identification. This comparison relies on the fact that every individual’s dentition, or set of teeth, is unique. Even a single tooth with sufficient unique features can be used for identification. The ability of teeth to withstand extreme conditions provides a reliable method for identifying human remains when visual recognition, fingerprints, or DNA evidence are unavailable.