Dental Fluorosis: Chemistry and Biology

Department of Pediatric Dentistry
Resident’s Name: Murphy Program: Lutheran Medical Center - Providence
Article title: Dental Fluorosis: Chemistry and Biology
Author(s): T. Aoba, O. Fejerskov
Journal: Critical Review of Oral Biology and Medicine.
Year. Volume (number). Page #’s: 2002 V 13, NO 2. 155-170
Major topic: Fluorosis (FL)
Overview of method of research: THOROUGH review

Findings:
Fluoride (Fl) is the most important caries preventative agent in dentistry today. An increase in various fluoride forms and vehicles has caused an increase in mild to moderate FL in many communities. The effect of Fluoride on enamel formation that causes FL in humans is cumulative. This review article was aimed at discussing the pathogenesis of FL in relation to a putative linkage between ameloblastic activities, secreted enamel matrix proteins/multiple proteases, growing enamel crystals, and fluid composition including Ca and Fl ions.

Enamel is very sensitive to free Fl ions. Once Fl is incorporated into the enamel matrix, the ion affects subsequent mineralization process by reducing the solubility of the mineral. Numerous human and animal studies hve proven that enamel hypomineralization in teeth w/ FL is mostly due to the aberrant effects of excess Fl on the rates at which enamel matrix proteins break down, and at which the rate of the by products are withdrawn from the maturing enamel. Any interference with enamel matrix removal could affect crystal growth, resulting in different magnitudes of enamel porosity at the time of eruption. As of right now (2002) there is no evidence that Fl affects proliferation or differentiation of the enamel organ cells, or the production and secretion of enamel matrix proteins/proteases within the dose range that can cause FL in humans.

The article contends that most likely, the Fl ion indirectly interferes with protease activities by decreasing free Ca concentration in the mineralization process. Ca regulation of these activities is extremely important.
Because the cariostatic effect of Fl is not due to its uptake by the enamel during tooth development, it is possible to obtain substantial caries reduction without a risk of dental FL.

Key points/Summary:
FL is caused by long term ingestion of Fl during tooth development. Even very low amounts of Fl intake may result in a low level of FL. The dose-response relationship is linear, and there is no critical threshold for Fl intake below which the effect on enamel will not be seen. Fl exerts its pathogenic role through alteration of Ca activities, and thereby Ca dependent proteases. More research is needed overall

Assessment of Article:
Very long, intense, specific, tedious article filled with an extreme amount of information. I had to read it three times to soak it all in. Biochemistry overload. I hope that the boards will be more general in asking a question about this… hopefully.