Influence of highly concentrated fluoride dentifrices on remineralization characteristics of enamel in vitro.

OBJECTIVES

The aim of this in vitro study was to evaluate the role of highly fluoridated dentifrice on remineralization characteristics of lowly and highly pre-demineralized enamel artificial caries lesions.

METHODS

Bovine enamel specimens were prepared (pH 4.95; 21 days) and discriminated in either lowly [L] or highly [H] pre-demineralized artificial caries lesions. Specimens with a mean ΔZ (95% CI) of 5120 (4995; 5245) vol.% × μm and a mean ΔZ of 8187 (8036; 8339) vol.% × μm were selected and randomly allocated to 12 groups (n = 20). Treatments during pH-cycling (28 days; 6 × 60 min demineralization/day) were brushing 2×/day with fluoride-free (0 ppm F [L/H]), 1100 ppm F [L/H], 2800 ppm F [L/H], 5000 ppm F [L/H], 5000 ppm F + glycerin [L/H], and 5000 ppm F + TCP [L/H] containing dentifrices. Dentifrice slurries were prepared with deionized water (1:3wt/wt). After cycling specimens presenting lesion surface loss were discarded and for the remaining 202 specimens, transversal microradiographic (TMR) analyses (ΔZ/LD) were performed again. Changes in mineral loss (ΔΔZ = ΔZ - ΔZ) and lesion depth (ΔLD = LD - LD) were calculated.

RESULTS

Significant differences for ΔΔZ could be found between L, L, and L as well as H, H, and H/H (p ≤ 0.01; ANCOVA). Except for 0 ppm F, higher ΔΔZ could be found in highly compared with lowly demineralized specimens (p ≤ 0.004; ANCOVA). After pH-cycling, a second lesion front could only be observed in H and H. The correlation between ΔΔZ and F was moderate for lowly and highly demineralized lesions (r = 0.591; p < 0.001; r = 0.746; p < 0.001), indicating a fluoride dose response for both.

CONCLUSION

For both baseline substrate conditions, a dose response for fluoride could be revealed.

CLINICAL SIGNIFICANCE

Remineralization characteristics of enamel directly depended on baseline mineral loss.