Shark teeth could pave the way to new dental therapies for humans

Whilst humans might be able to make do with a set of false teeth once the two sets we have during our lives have worn out, tooth loss is more critical amongst the rest of the animal kingdom. Elephants, for example, have 6 sets of replacement molars and once they have all been worn down the animal will die from starvation - a major cause of death in mature elephants. Sharks however, have developed a strategy to deal with the problem of tooth loss and that is to have unlimited sets of new teeth during their lifetime - something which most other vertebrate lineages have lost.

The genetic basis for tooth regeneration in sharks has recently been investigated by scientists at University of Sheffield using the catshark (Scyliorhinus spp.) as a model. The research indicated that the ancestral condition of vertebrates was likely to be that of constant tooth regeneration and that tooth development in vertebrates is governed by a core set of genes. The team discovered several potential reasons why sharks are able to produce unlimited sets of replacement teeth: firstly having a jaw made of cartilage as oppose to harder, bony material allows new teeth to constantly move forward replacing older, worn out teeth. Secondly sharks have an expanded dental lamina which houses multiple sets of teeth ahead of being required and the team suggests that this is essential for continuous tooth regeneration.

What is significant about these findings is how similar this core set of genes governing dental development is between sharks and our own species; in fact many of the genes which govern tooth development in vertebrates have thought to have remained unchanged for around 450 million years. The research suggests that slight genetic changes to this gene set could be the key to unlimited tooth regeneration as oppose to a finite set of teeth. Understanding how this gene set functions across the vertebrate lineage could contribute to the development of novel therapies for tooth loss in humans.

Rasch,L.J.,et al., An ancient dental gene set governs development and continuous regeneration of teeth in
sharks. Dev.Biol.(2016) http://dx.doi.org/10.1016/j.ydbio.2016.01.038i