When you have a patient who is receiving a flouride treatment with a well child check in a medical providers office, what diagnosis would you use for the flouride treatment?

This would depend on why a physician is administering the fluoride and not the Dentist. The ICD-9-CM code explains why a procedure is being performed. If you are administering fluoride treatment due to gross carries or heavy plaque you would use the appropriate ICD-9-CM code to support your billed charge.