Just like with people, it is possible to have a puppy who has a bite that is not lined up exactly perfectly. Either an underbite or an overbite-----it is even desired in certain breeds! We do not breed parents who have bite issues, or intentionally produce puppies with imperfect bites, but it can still happen that a pup has a bit of a misalignment. This is not something that changes their wellbeing except in very extreme circumstances-----which we would not anticipate. It can be perfectly normal for a puppy's bite to be "off" at sometime in it's growth period as the jaws can grow at different rates. Leaving spay or neuter until after growth is completed can help in this situation. However, if you think your dog has an issue with his or her bite that you think is causing a problem for them, check with you vet. In some cases, a vet may suggest removing a tooth, or even surgery. However, if they suggest anything that you feel is drastic, a second opinion would be a great idea. Canine dentistry and even orthodontics are a growing field, but the cases in which surgical approaches are necessary for anything more than cosmetics should be extremely rare in either of our breeds.