Can this mean my shih tzu was badly bred?

She is perfect in every aspect, everything exactly like a shih tzu, we have her papers. Just because she has an overbite...does that mean she is badly bred? She is perfect size for shih tzu, colour, markings, temperament,eyes, length of legs, muscular chest, perfect gracious tail. I am her third owner so I didn't see the parents or the litter.