Fluoride & Teeth-Dental Fluorosis

Excessive ingestion of fluoride during the early childhood years may damage the tooth-forming cells, leading to a defect in the enamel known as dental fluorosis.
Teeth impacted by fluorosis have visible discoloration, ranging from white spots to brown and black stains.
Teeth with fluorosis also have an increased porosity of the enamel. In the milder forms, the porosity is mostly limited to the sub-surface enamel, whereas in the more advanced forms the porosity also impacts the surface enamel, resulting in extensive pitting, chipping, fracturing, and decay of the teeth.

The discoloration induced by fluorosis - particularly in its advanced forms - can cause significant embarrassment and stress to the impacted child, resulting in adverse effects on esteem, emotional health, and career success.
It is currently estimated that an average of 48% of children living in fluoridated areas now have some form of dental fluorosis, with 12.5% of children having fluorosis significant enough to be of "esthetic concern" (York Review, 2000).
While proponents of water fluoridation dismiss dental fluorosis as being simply a "cosmetic effect," recent research indicates that the rate for bone fracture among children with fluorosis (even in the mild forms) is higher than the bone fracture rates among children with no fluorosis.

As noted by Dr. Hardy Limeback, Head of Preventive Dentistry at the University of Toronto, "it is illogical to assume that tooth enamel is the only tissue affected by low daily doses of fluoride ingestion."
Fluoride & Teeth - Tooth Decay (Caries): (Click for more detail)

According to the current consensus view of the dental research community, fluoride's primary - if not sole - benefit to teeth comes from topical application to the surfaces of teeth (while in the mouth), not from ingestion.

It is also acknowledged by dental researchers that fluoride has little effect on preventing cavities in the pits and fissures (chewing surfaces) of teeth - where the majority of tooth decay occurs.

Perhaps not surprisingly, therefore, tooth decay rates have declined dramatically in all western countries in the latter half of the 20th century - irrespective of whether the country fluoridates its water or not. Today, tooth decay rates thoughout continental western Europe are as low as the tooth decay rates in the United States - despite a profound disparity in water fluoridation prevalence in the two regions.

Within countries that fluoridate do their water, recent large-scale surveys of dental health - utilizing modern scientific methods not employed in the early surveys from the 1930s-1950s - have found little difference in tooth decay, including "baby bottle tooth decay", between fluoridated and unfluoridated communities.
http://www.fluoridealert.org/health/teeth/