LASER FLUORESCENCE QUANTIFICATION OF REMINERALIZATION IN-SITU OF INCIPIENT ENAMEL LESIONS - INFLUENCE OF FLUORIDE SUPPLEMENTS

The aims of this study were to test the laser fluorescence method for quantification of remineralisation in situ of enamel with incipient le sions and to evaluate the enhancement of remineralisation by fluoride (F) supplements when a F dentifrice was used on a regular basis by hea lthy young subjects. Enamel samples were cut from extracted premolar t eeth with the natural surface kept intact, and subjected to a pH-cycli ng system to produce subsurface demineralisation in vitro. The enamel blocks were then inserted into composite holders bonded to the buccal surfaces of both upper first molars of 12 panelists. Each panelist par ticipated in 3 separate experiments in a randomised order; each lasted for 5 weeks with washout intervals of 2 weeks between experiments; ex periment 1: F dentifrice (0.145% F as NaF) only; experiment 2: F denti frice+F lozenges (0.25 mg Fx6/day); experiment 3. F dentifrice+F chewi ng-gum (0.25 mg Fx6/day). Fluorescence radiance was measured before, d uring, and after in vitro demineralisation, and once a week during the in situ experimental periods. The enamel samples were then sectioned and analysed with transverse microradiography (TMR). Anova and Pearson correlation coefficient were used for the statistical analysis. At th e end of the 5-week in situ periods, fluorescence radiance had been re gained to a level of 80-100% ofthe value before in vitro demineralisat ion, indicating remineralisation ofthe enamel samples. There were no d ifferences in the fluorescence radiance gain between the 3 different F exposures. However, there was a statistically significant time trend (p <0.001), and a highly significant linear dependence (p<0.001) betwe en the final measurements obtained with the laser fluorescence method (LAF) and the data obtained from TMR, r=0.76. It was concluded that: ( 1) with the sensitive LAF method it was possible to register the small changes in the enamel week by week during in situ remineralisation; ( 2) when F dentifrice was used regularly, F supplements such as F lozen ges or F chewing-gum did not significantly enhance the in situ reminer alisation of incipient enamel lesions in healthy, young adults with no rmal salivary flow.