Fluoride uptake into the developing enamel and dentine of sheep incisors following daily ingestion of fluoridated milk or water.
Incomplete availability of fluoride from fluoride compounds when added to milk is claimed to reduce the effectiveness of fluoridated milk in caries prevention in humans. This study attempts to add to the understanding of the systemic bioavailability of fluoride ingested with milk compared with water, by measuring its uptake into developing incisors of sheep. Twenty-five sheep, aged approximately 10 months, were randomised into five groups and farmed under identical conditions. They were dosed orally each day for 22 weeks with fluoride as sodium fluoride in water or bovine milk. The doses of fluoride were 0.5 or 0.2 mg/kg body weight in milk or water; a control group received no additional fluoride. Tooth length was labelled at the start of dosing with intramuscular injection of tetracycline. After sacrificing, incisors were removed, sectioned, and analysed for fluoride and calcium by proton microprobe scans from the enamel surface to the pulp. Concentrations of ionised fluoride in the milk samples were 30 percent and 20 percent respectively for added fluoride at concentrations of 300 and 750 micrograms/ml. The mean fluoride concentrations in surface enamel, deep enamel, and dentine were dependent on the daily fluoride dose and independent of the carrier (milk or water). The teeth of sheep receiving the higher fluoride dose (0.5 mg/kg body weight) had significantly higher fluoride than those receiving the lower fluoride dose (0.2 mg/kg body weight), which were significantly higher than in the teeth of the control sheep. It was concluded that the bioavailability of fluoride from sodium fluoride mixed with milk or water was similar following metabolism, despite 20-30 percent and 100 percent ionisation in milk and water respectively.
Dental Research Unit, Wellington School of Medicine.
T W
TW
Cutress
G W
GW
Suckling
G E
GE
Coote
J
J
Gao
D000818:Animals; D001682:Biological Availability; D001835:Body Weight; D002118:Calcium / Q000032:analysis; D002327:Cariostatic Agents / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics*; D002417:Cattle; D004396:Coloring Agents; D003743:Dental Enamel / Q000378:metabolism*; D003804:Dentin / Q000378:metabolism*; D004577:Electron Probe Microanalysis; D007180:Incisor; D008892:Milk; D009805:Odontogenesis; D011897:Random Allocation; D012756:Sheep; D012969:Sodium Fluoride / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics*; D013752:Tetracycline; D014881:Water Supply
D002327:Cariostatic Agents; D004396:Coloring Agents; D012969:Sodium Fluoride; D013752:Tetracycline; D002118:Calcium