The question of whether sharks experience tooth decay like humans do is intriguing, given their fearsome dental reputation. Understanding the unique biology of shark teeth provides insight into their oral health.
The Simple Answer
Sharks do not get cavities. This immunity stems from biological adaptations that protect their teeth from decay common in many animals. These mechanisms, inherent to their dental structure and life cycle, ensure healthy, functional teeth throughout their lives.
Built-In Dental Protection
Shark teeth possess an outer layer, enameloid, which differs from human enamel. This enameloid is highly mineralized and contains a significant amount of fluoride, sometimes as much as 100% in species like makos and tiger sharks. This high fluoride content forms fluoroapatite, a substance that is more resistant to acid erosion than the hydroxyapatite that makes up human enamel, providing a natural, cavity-proof coating.
Sharks exhibit continuous tooth replacement, known as polyphyodonty. Sharks have multiple rows of teeth, and new teeth are constantly developing behind the functional front rows. When a tooth is lost or damaged, a replacement tooth moves forward on a conveyor-belt-like system to take its place. Replacement can occur rapidly, sometimes every few weeks or even days, quickly shedding any potential decay or wear with the old tooth. A single shark can go through tens of thousands of teeth in its lifetime.
Their carnivorous diet contributes to preventing cavities. Sharks consume fish, squid, and marine mammals, lacking sugary carbohydrates often linked to human tooth decay. The absence of these fermentable sugars means less acid production by bacteria in their mouths, reducing the risk of enamel breakdown.
The marine environment also contributes to their oral health. Seawater contains beneficial minerals, and the constant flow of water through a shark’s mouth rinses away food particles and debris. Though not a primary defense against decay, this natural rinsing complements their inherent biological protections.
Beyond Cavities
While sharks are immune to cavities, their teeth are still subject to wear and tear. During hunting and feeding, shark teeth can experience damage like breakage, chipping, or wear from impacting prey or hard surfaces. Species that feed on prey with thick bones or hard shells may show more signs of wear and damage on their teeth.
These issues, however, are not problematic for a shark’s oral health or feeding efficiency. The continuous tooth replacement system ensures that any broken, worn, or lost teeth are quickly replaced by sharp, new ones. This constant renewal cycle means that a shark maintains a functional and effective set of teeth, mitigating the impact of individual tooth damage.