A hamsters teeth never stop growing because they take in a lot of calcium, as do gerbils. It causes their teeth to grow at an amazing rate. So keep wood and twigs handy to put in their cage. But do not use Cedar. It kills both gerbils AND hamsters.
Hamster's teeth never stop growing because they belong to the Rodent family. The word "Rodent" means "To Gnaw" and they need to gnaw to keep their teeth nice and short.