Alberta-based dentist Michael Zuk bid by phone to buy the molar given to Dot Jarlett by Lennon in the 1960s, the BBC reported.
"Once I heard it was up for sale I had to have it," Zuk said.
The tooth was among a collection of rock memorabilia auctioned Saturday by the former boss of record label Creation Records, Alan McGee. Other items for sale included a painting by Stone Roses guitarist John Squire and gifts from politicians.
Zuk said he plans to display the tooth in his practice as well as take it on a tour of other dental surgeries and schools.
"Some people will think it's gross, others will be fascinated by it," Zuk said.
Karen Fairweather of Omega Auctions described the tooth as "rather gruesome, yellowy, browny with a cavity."
"John Lennon came back from the dentist and gave it to his housekeeper and said to dispose of it 'or better still give it to your daughter as a souvenir,'" Fairweather said.