Problems may arise with a hamster's teeth if it does not have sufficient opportunities to wear them down during normal feeding and gnawing activities. The incisors and molars may both be affected, however generally only overgrowth of the incisors will be noticed by the owners. These front teeth will appear overly long and may curl slightly; the hamster will also have difficulty feeding. Sometimes the problem is caused by malocclusion i.e. the teeth not rubbing together naturally when feeding, perhaps due to damage caused by gnawing on metal bars of the cage.
Your vet can clip the overgrown teeth back which will enable your pet to feed normally once more. You can try to prevent the problem recurring by providing your hamster with pieces of wood to chew on; (take care , some woods may be toxic, I would recommend fruit wood such as apple or pear). However if the problem is essentially one of malocclusion then regular teeth clipping will be required, probably once every month or less.