Root Caries Inhibition By Different Fluoride Varnishes In Vitro U. Schiffner* (Department Of Conservative And Preventive Dentistry, University Of Hamburg, Germany) Rising numbers of teeth in elderly people require regimens for root caries prevention. Thus, the aim of the study was to investigate in an artificial mouth device the root dentin demineralization inhibiting effect of the fluoride varnishes Bifluorid 12® (group I, sodium fluoride and calcium fluoride, 55900 ppm fluoride) and Fluoridin Gel N5 (group III, sodium fluoride, 22600 ppm) in comparison with Duraphat® (group IV, sodium fluoride, 22600 ppm) and a control group without any fluoride application. Beside this comparison, the effect of an experimental varnish (group II, corresponding to Bifluorid 12® but without CaF2; sodium fluoride, 27120 ppm) was studied.   90 root dentin slabs were prepared from surgically removed human third molars. The slabs of group I to IV were treated once with the different fluoride varnishes according to manufacturers’ recommendations. All varnishes were allowed to affect the dentin slabs for 24 hrs. before the varnishes were removed. For formation of root dentin demineralizations the slabs were transferred to an artificial mouth device which mimics caries promoting factors (application of a S. mutans suspension and 5% sucrose solution, saliva formed pellicle) as well as caries inhibiting factors (steady flow of saliva, remineralizing artificial saliva) following a given schedule. At the end of the demineralizing period of 6 weeks the slabs were cut and ground to appr. 100 µm thin sections. Using polarized light microscopy, lesions’ depths (in µm) were determined as given in the table:   Group I Group II Group III Group IV Group V (Bifluorid 12®) (experimental) (Fluoridin Gel N5) (Duraphat®) (control) 36.6 ±18.6 33.3 ±16.3 43.6 ±12.3 48.9 ± 5.2 78.4 ±10.3   All fluoride preparations inhibited lesion formation to a statistically significant degree (multiple t-test for independent samples, correction procedure according to Fisher). This effect was most pronounced in the groups with the highest fluoride concentrations (grp. I and II). There were statistically significant differences between group I and IV, II and III as well as II and IV. Lesions of the groups I and II did not differ statistically under the present experimental setup.   In conclusion, single applications of fluoride varnishes are able to affect distinct inhibitions of root dentin demineralization over a period of six weeks of caries promoting in vitro conditions. The presence of calcium fluoride in a fluoride varnish does not result in a further inhibition of root dentin demineralization.