"Making sure your offspring know how to clean their teeth appears to be as important to monkeys as to humans.
Female monkeys in Thailand have been observed showing their young how to floss their teeth - using human hair.
Researchers from Japan said they watched seven long-tailed macaques cleaning the spaces between their teeth in the same manner as humans.
They spent double the amount of time flossing when they were being watched by their infants, the team said.
This suggests the mothers were deliberately teaching their young how to floss, Professor Nobuo Masataka of Kyoto University's Primate Research Institute said.
"I was surprised because teaching techniques on using tools properly to a third party are said to be an activity carried out only by humans," he told the AFP news agency.
He said the study, carried out in Lopburi, north of Bangkok, is still in the hypothesis stage.
"We would like to shift our focus to the baby monkeys to check whether the mothers' actions are effectively helping them learn how to clean their teeth," he added. "