Tuatara acts as model for false teeth damage

An iconic reptile native to New Zealand has been used as the basis for a 3D computer model investigating how damage to teeth is prevented by the jaw, muscles and brain in the absence of the periodontal ligament.

The research – funded by the Biotechnology and Biological Science Research Council (BBSRC) – used the tuatara, a lizard-like reptile whose teeth are fused into the jaw bone, much like dental implants. The 3D computer model was used to investigate the feedback between the jaw joints and muscles in a creature that lacks periodontal ligaments, and to understand how the animal knows how hard to bite.

“In the sugar-rich western world many people end up losing their teeth and have to live with dentures or dental implants,” said Dr Marc Jones, a BBSRC postdoctoral fellow from University College London, “They’ve also lost the periodontal ligament that would attach their teeth, so we wanted to know how their brains can tell what’s going on when they’re eating.”

 “Humans and many other animals prevent damage to their teeth and jaws when eating because the ligament that holds each tooth in place also feeds back to the brain to warn against biting too hard,” said Dr Neil Curtis, a BBSRC postdoctoral fellow from the University of Hull.

“Tuataras live happily for over 60 years in the wild without replacing their teeth because they have the ability to unconsciously measure the forces in their jaw joint and adjust the strength accordingly,” Dr Curtis added.

Although this explains why tuatara and those with false teeth don’t break them, it’s clear that the periodontal ligament is useful for fine tuning chewing movements. Anecdotal evidence suggests that people with implants and dentures make food choices related to their lack of periodontal ligament, but the tuatara has a broad diet of beetles, spiders, snails and frogs.