That's normal ... they do tend to chew on everything they can get their little mouth on. Just make sure she has plenty of hay, chew sticks and a lava stone in her cage at all times. You also have to teach her that chewing on certain things is a 'no-no' and will not be tolerated.
Do they teethe? The answer to that would have to be yes, but in a different way.
We as humans think of teething as growing baby teeth, and/or loosing baby teeth and permanent teeth growing back in to take the place of the baby teeth. With chinchillas, they are usually born with a full set of teeth that stay with them all their life, but these teeth are constantly growing all during their life ... to adjust to the size of the mouth. If a chinchilla chips a tooth, this constant growing can be an advantage ... the tooth will continue to grow and will be worn down smoothly as it grows, if it is not a bad chip. But, should it be a bad chip or break, it can cause the other teeth to no longer be aligned properly, so it is best to get it checked if there is a problem with the tooth.
It is when a chinchilla stops chewing ... that's you should worry.
Jo Ann
That was a good question to ask ... one that brings to everyone's attention the chinchilla's teeth and what is or is not normal.