A 16-year-old lioness at the Wellington Zoo in New Zealand recently got her 11-centimetre long tooth operated.

Djembe (pronounced Jem-by), underwent a four-hour root canal operation performed on a lower canine by a team of 20 people. Veterinarian Angus Fechney, who specialises in animal dentistry, led the procedure.

The operation was a little more complicated than the usual because it was difficult to get the dirt out of the long tooth, Vet Sarah Alexander said, according to News Hub website.

"She is a dangerous animal and dangerous animals have the potential to cause real havoc during their procedures. So if they wake up we can be in a bit of trouble, that's one of the reasons we've got specialist anaesthetists helping us today," Dr Alexander said.

"Luckily Djembe hasn't shown any sign of pain or infection with her tooth, it's just that we noticed there was a little hole on top and that's where the root goes down," Dr Alexander added.

To know if a lion needs to undergo a root canal, the zoo keepers use techniques that make the animal open its mouth. The keepers then check all of its teeth, Dr Alexander said, News Hub website reported.

Dr Alexander also said that the lioness's age was an extra risk during the operation.

"She is really a geriatric lion. Lions live perhaps into their early 20's in captivity. As they get older we tend to run into age related problems like arthritis, additional teeth problems, kidney-problems etc."

Dr Fechney who carried out the procedure is said to have also performed a root canal on a bear this year.

"We're looking at booking him in for a baboon and an otter, so we're keeping him very busy," Dr Alexander said.

Djembe was given a reversal drug to wake her up and was sent to her enclosure while she was still under anaesthesia.