Microelements: Part II: F, Al, Mo and Co

Ultratrace element is a relatively new term, and is defined as those elements with an established, estimated, or suspected dietary requirement of minute amount, generally of the order of µg/day. This chapter focuses on fluorine (F), aluminium (Al), molybdenum (Mo), and cobalt (Co). Whilst diet is the principal source of Al, Mo, and Co found in the body, inadvertent ingestion of dental hygiene products accounts for a significant proportion of F intake. Apart from F, the influence of other ultratrace elements on oral health, and in particular dental caries, has not been fully established. The calcified tissues contain 99% of body F. During tooth development, ingested (systemic) F is incorporated into the apatite crystals of the developing tooth which helps in improving resistance to acid demineralisation. However, the presence of low but constant levels of topical F in the fluid phase at the tooth enamel surface are more important in controlling tooth decay in people of all ages. An adequate intake, from all dietary and non-dietary sources, is estimated as 0.05 mg/kg body weight/day for children older than 6 months and adults, based on estimated intakes that have been shown to reduce the incidence of dental caries while minimising adverse health effects such as dental fluorosis. An inverse relationship between incidence of dental caries and levels of Al in drinking water, food, and soils has been indicated by some epidemiological studies. Co and Mo, whilst occasionally showing potential beneficial oral health effects in laboratory experiments, do so at concentrations much higher than found in vivo.