To uncover the chemical mechanisms of tooth renewal Professor Cheng-Ming Chuong and colleagues studied repetitive tooth formation in American alligators.

Most vertebrates can renew teeth throughout their lives whereas humans’ are naturally replaced only once.

Alligators have an average of 80 teeth in their mouth at any one time - and 50 sets of replacements to last their lifetime.

Alligators have well-organised teeth with traits similar to those of mammals - such as secondary palates and implantation in sockets of the dental bones - and are capable of lifelong tooth renewal.

Through a combination of molecular aqnalysis and scanning techniques the researchers showed each alligator tooth is a complex unit of three components in different developmental stages.

These are structured to facilitate replacement once they are dislodged, says the study published in Proceedings of the National Academy of Sciences.

Early on the alligator dental lamina forms a bulge at its tip that houses stem cells. Molecular analysis revealed that the initiation of the tooth cycle corresponds with the dynamic expression of an array of signaling chemicals.

The researchers believe the findings could help adults who have lost teeth or have ones that appear in addition to the regular number - a common condition called supernumerary teeth.