Effects of the association of high fluoride- and calcium-containing caries-preventive agents with regular or high fluoride toothpaste on enamel: an in vitro study

Objectives The aim of this in vitro study was to compare the caries-preventive effect of various high fluoride- and calcium-containing caries-preventive agents (> 22.000 ppm F- [ppm]) in adjunct to use of regular (1450 ppm) or high (5000 ppm) fluoride toothpaste on sound as well as demineralized enamel. Materials and methods Bovine enamel specimens (n = 276; 5 mm x 3.5 mm x 3 mm) having one sound surface [ST] and one artificial caries lesion [DT] were randomly allocated to 12 groups. Interventions before pH-cycling were no intervention ([SC1/SC5]), application of varnishes/solutions containing NaF (22,600 ppm; Duraphat [NaF1/NaF5]); NaF + tricalcium phosphate (22,600 ppm; Clinpro White Varnish [TCP1/TCP5]); NaF + CPP-ACP (22,600 ppm; MI Varnish [CPP1/CPP5]); silver diammine fluoride (35,400 ppm; Cariestop 30%[SDF1/SDF5]); and NaF + calcium fluoride (45,200 ppm; Biophat[CaF1/CaF5]). During pH-cycling (28 days, 6 x 120 min demineralization/day) half of the specimens in each group were brushed (10 s; 2 x /day) with either 1,450 (NaF; named, e.g., TCP1) or 5,000 ppm (NaF; e.g., TCP5) dentifrice slurry. Differences in integrated mineral loss ( increment increment Z) and lesion depth ( increment LD) were calculated between values after initial demineralization and after pH-cycling using transversal microradiography. Results After pH-cycling, SC1/SC5 showed significantly increased increment Z(DT)/LDDT values, indicating further demineralization (p < 0.05; paired t-test). Decreased increment Z(DT) values, indicating non-significant remineralization, could only be observed in CaF1/CaF5 (p > 0.05; paired t-test). Additional use of all varnishes/solutions significantly decreased increment increment Z(DT)/ increment increment Z(ST) and increment LDDT/ increment LDST compared to SC1/SC5 (p < 0.05;ANCOVA). Between 1450 and 5000 ppm dentifrices, a significant difference in increment increment Z(DT)/ increment increment Z(ST) and increment LDDT/ increment LDST could only be observed for SC1/SC5 (p < 0.05; ANCOVA). Conclusion Under the conditions chosen, all fluoride varnishes/solutions significantly reduced demineralization. Furthermore, a significant dose-response characteristic for fluoride varnishes could be revealed. However, no additional benefit could be observed, when varnishes were combined with high fluoride instead of regular fluoride dentifrices.

Automated summary

The aim of this in vitro study was to compare the caries-preventive effect of various high fluoride- and calcium-containing caries-preventive agents in adjunct to use of regular or high fluoride toothpaste on sound as well as demineralized enamel. Results showed that all fluoride varnishes/solutions significantly reduced demineralization, with a significant dose-response characteristic for fluoride varnishes, but no additional benefit could be observed when varnishes were combined with high fluoride instead of regular fluoride dentifrices.