This happened to two of my friends, both told they had over 10 cavities at a dental visit. They were both seeing a new dentist, one had not been seen by a dentist in three years but the other had been in the past year. Both got a second opinion, one was told he had four caviities that he got filled by the second dentist. The other guy had never had a cavity in his life, the second dentist told him he had a few small brown spots but they just needed watched, and he never did need the fillings.