Mechanism of fluoride dentifrice effect on enamel demineralization.
Although the anticaries effect of fluoride (F) dentifrices is clearly established, the relative importance of F taken up by dental plaque not removed by brushing and of F products (CaF(2)-like) formed on totally cleaned enamel for the subsequent inhibition of demineralization is not known. Both effects were evaluated using conventional (1,100 microg F/g) and low-F concentration (500 microg F/g) dentifrices in a randomized, crossover, double-blind in situ study. Enamel blocks not treated or pretreated with the dentifrices to form CaF(2)-like deposits were mounted in palatal appliances in contact with a Streptococcus mutans test plaque. Volunteers brushed with non-F (negative control), low-F or conventional dentifrices and inserted the appliance in the mouth. F concentration in the fluid and solid phases of the test plaque was determined after 30 min, and a rinse with 20% sucrose solution was performed. After additional 45 min, plaque was collected and the loss of surface hardness at different test-plaque depths was measured. CaF(2)-like deposition on enamel and F taken up by plaque due to the use of F dentifrices were able to significantly increase F concentration in the fluid phase of the test plaque, but only the latter significantly reduced the loss of hardness because of the 20-30 times higher F concentration. Also, significant differences between the low-F and conventional dentifrices were observed for F on enamel, in plaque and on the subsequent loss of hardness. The results suggest that uptake of F by dental plaque not removed by brushing may be the main cause of the anticaries effect of F dentifrices.
Piracicaba Dental School, UNICAMP, Piracicaba, Brazil. litenuta@fop.unicamp.br
L M A
LM
Tenuta
C B
CB
Zamataro
A A
AA
Del Bel Cury
C P M
CP
Tabchoury
J A
JA
Cury
D000328:Adult; D000704:Analysis of Variance; D002124:Calcium Fluoride / Q000008:administration & dosage* / Q000032:analysis / Q000493:pharmacokinetics; D002327:Cariostatic Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics; D018592:Cross-Over Studies; D003743:Dental Enamel / Q000187:drug effects*; D003773:Dental Plaque / Q000737:chemistry / Q000150:complications / Q000382:microbiology / Q000517:prevention & control; D003802:Dentifrices / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D006244:Hardness / Q000187:drug effects; D006801:Humans; D008875:Middle Aged; D013295:Streptococcus mutans / Q000187:drug effects / Q000378:metabolism*; D017001:Tooth Demineralization / Q000209:etiology / Q000382:microbiology / Q000517:prevention & control; D014093:Tooth, Artificial; D055815:Young Adult
D002327:Cariostatic Agents; D003802:Dentifrices; D002124:Calcium Fluoride