An occasional Pizza crust is a great thing for a teething puppy to chew on (emphasis on occasional).  

There are several products (such as Grannick's Bitter Apple, Phooey, Sour Grapes, etc.) which can safely be applied to furniture and other items to prevent chewing.  If you catch your puppy chewing on something inappropriate, give a firm verbal correction (No!), then give the puppy something it can  chew on, such as a smoked pig's ear (a Bernese favorite).   For safety's sake, you should always supervise what your puppy chews on.