Shark Teeth in Humans: Potential Breakthrough for Dental Health

Scientists are studying how sharks regenerate teeth, a trait that could transform human dental care. Unlike humans, who develop only two sets of teeth in a lifetime, sharks continuously replace theirs, reducing issues like decay and loss. Understanding this process may lead to breakthroughs in regenerative dentistry, potentially eliminating the need for implants or dentures.

Physical Structure And Composition

Shark teeth are uniquely structured for durability and continuous replacement. Unlike human teeth, which are anchored in the jawbone, shark teeth are embedded in a soft, fibrous tissue called the dental lamina. This flexible attachment allows for seamless shedding and replacement. The outer layer of shark teeth consists of enameloid, a highly mineralized tissue similar to human enamel but composed primarily of fluorapatite, which enhances resistance to acid erosion.

Beneath the enameloid is dentin, a calcified tissue forming most of the tooth structure. Unlike human dentin, which contains microscopic tubules housing nerve endings, shark dentin is more compact and lacks direct innervation, reducing sensitivity. This dentin is reinforced with orthodentin, a microstructure that enhances strength and prevents fractures. The combination of fluorapatite-rich enameloid and dense dentin ensures durability.

Sharks have multiple rows of teeth that move forward in a conveyor-belt system, ensuring a constant supply of functional teeth. The rate of replacement varies by species, with some regenerating teeth every few weeks. This rapid turnover is driven by stem-like progenitor cells within the dental lamina, which continuously generate new teeth throughout a shark’s life.

Mechanisms Of Regeneration

Sharks regenerate teeth throughout their lives, thanks to specialized cellular activity within the dental lamina. Unlike mammals, where this tissue regresses after permanent teeth form, sharks retain it indefinitely, allowing for continuous renewal. Cellular signaling pathways, including Wnt/β-catenin and fibroblast growth factors (FGFs), regulate the proliferation and differentiation of progenitor cells, ensuring orderly tooth formation.

The process begins with stem-like cells in the dental lamina generating epithelial and mesenchymal tissues necessary for new teeth. Sonic hedgehog (Shh) signaling helps coordinate the spatial arrangement of developing teeth, preventing disorganized growth. As teeth mature, they migrate forward, replacing older ones that are naturally shed.

The rate of regeneration depends on diet and mechanical wear, with species experiencing higher tooth attrition replacing teeth more frequently. Some sharks regenerate thousands of teeth over a lifetime, with certain species replacing individual teeth every two weeks. This ensures they maintain effective feeding capabilities despite constant tooth loss.

Differences Compared To Human Teeth

The structural and functional differences between shark and human teeth reflect their distinct evolutionary roles. Human teeth are anchored in the jawbone by the periodontal ligament, which provides stability and shock absorption for precise chewing. In contrast, shark teeth are set within soft tissue, allowing for continuous shedding and replacement without healing periods.

Human enamel consists primarily of hydroxyapatite, a crystalline calcium phosphate structure that provides hardness but lacks regenerative capacity. Once damaged, human enamel cannot repair itself, requiring intervention such as fillings or crowns. Shark enameloid, composed of fluorapatite, is more resistant to acid erosion and supports continuous renewal, helping sharks avoid cavities despite frequent tooth loss.

Humans develop only two sets of teeth—deciduous and permanent—limiting replacements. Once permanent teeth are lost, regeneration is not possible, making prosthetics necessary. Sharks, however, retain an active dental lamina that continuously generates new teeth, ensuring they always have functional dentition. This fundamental difference highlights the limitations of human dental evolution and the potential for regenerative medicine.

Research On Dental Integration

Scientists are exploring whether shark tooth regeneration mechanisms can be applied to human dentistry. Research has identified genetic and cellular pathways responsible for continuous tooth renewal, with a focus on reactivating similar processes in humans. At the University of Sheffield, researchers found that the Wnt signaling pathway, involved in shark tooth regeneration, also exists in human dental tissue. By activating this pathway in lab models, they successfully induced the formation of additional tooth buds, suggesting humans may retain a dormant regenerative ability.

Tissue engineering approaches are also being investigated. Studies have shown that stem cells derived from human gum tissue can form tooth-like structures when exposed to molecular signals that drive shark tooth formation. Research published in Developmental Biology demonstrated that bioengineered dental lamina tissues could serve as a foundation for regenerating natural teeth. These findings pave the way for treatments that could replace traditional implants by stimulating natural tooth regrowth.