There are ten recognized specialties in dentistry in Canada. Each of the specialties is considered to be separate from the others, although some of the specialties have certain procedures that are claimed by more than one specialty.
A periodontist is a dentist who has completed a recognized specialty program concerning the periodontium, which is the supporting structure of the teeth. Simply put, this person deals with gums and bone that are holding the teeth in place.
Fluoride that is ingested during the formative years for tooth enamel (up to 9 years old) reduces tooth decay, too much ingested fluoride over a sustained period causes permanent unsightly dark spots on the teeth.
I spent a week with a well-known dental lecturer. He talked about the three main problems the profession has been trying to conquer since many years back: Caries (cavities), periodontal disease, and occlusion.