Metal bars aren’t very good for your hamster’s teeth - they’re too hard to get through, and they can cause serious tooth problems by breaking them and pushing them out of their normal alignment. If hamsters regularly chew bars, then they can suffer from problems such as broken teeth, misaligned teeth, and mouth and facial injuries.
If your hamster keeps biting the bars of its cage, then there may be some things that you need to do to improve your pet’s life. Gnawing on the bars of the cage can indicate one of a number of things, including boredom, a lack of space, or overgrown teeth.
Bar rub can be caused by a number of factors
For the most part, your hamster will entertain themselves. However, lots of owners recommend that they are brought out of their cage and played with at least once every 24 hours. If your hamster is chewing its bars, then the first thing to do is bring it out of its cage for some play time. Try increasing the frequency with which you play with your hamster for a while, and see if this reduces the bar-chewing behaviour.
Another thing to try is to provide your hamster with something to chew. Hamsters have very long teeth that are constantly growing, and if they don’t have enough hard food to chew then they’ll gnaw whatever they can get their paws on - if there’s nothing else this can mean that your pet may resort to nibbling the bars of its own cage. A possible solution to this is to buy a hamster chew or gnaw. This is a special piece of wood that is safe for your pet to munch on, and allows your pet a more comfortable, safer way of wearing down their teeth.
Finally, if you’ve tried the above two options for a few days, then the problem may be the cage itself. Your hamster may be trying to escape because their cage is too small - if they’re somewhere they don’t want to be, and there’s no obvious way out, then the obvious thing that they’ll try to do is attempt to gnaw their way out.
If none of these options work, then you may want to purchase a large glass cage that doesn’t have any bars. These are often reclaimed aquariums, and thus are quite a good size, but it’s a good idea to get the measurements before you purchase any new home for your pet.