Effect of a 5000 ppm fluoride toothpaste and a 250 ppm fluoride mouth rinse on the demineralisation of dentin surfaces

Abstract

Background: The purpose of this study was to test the null hypothesis that there is no difference between the effect of (1) a 5000 ppm fluoride toothpaste, and (2) a 250 ppm fluoride mouth rinse on demineralized human dentin surfaces, against the alternative hypothesis of a difference.

Findings: Dentin specimens were obtained from the cervical regions of 45 extracted human third molars. Half the surface of each specimen was sealed with a self-etching adhesive system and served as the reference surface. The dentin specimens were randomly assigned to one of the three groups, 5000 ppm fluoride toothpaste (Duraphat), 250 ppm fluoride mouth rinse (Meridol) and distilled water (negative control).An intraoral appliance was made for one volunteer. In each test cycle, 15 specimens were inserted in the appliance and worn for 24 hours a day, over a period of three weeks.Once daily, the appliance was immersed in the agent being tested; either toothpaste slurry, mouth rinse or distilled water for 60 seconds.Demineralization was assessed in terms of lesion depth (microm) and mineral loss (vol. % x microm) by transversal microradiography. Data analysis was accomplished using Kolmogorov-Smirnov test and ANOVA (SPSS 12.0).Statistically significant differences for mineral loss and lesion depth were found between the toothpaste and the mouth rinse as well as between the toothpaste and the control group, but not between the mouth rinse and the control group.

Conclusion: Within the limitations of this study, the results suggest that treatment of demineralised dentin with a toothpaste containing 5000 ppm fluoride may considerably reduce mineral loss and lesion depth on exposed dentin.

Figure 1

Appliance design and flow chart of the procedures of the experimental design. The dentin specimen with test and reference sites, T: test site; R: Reference site (left) and the intraoral appliance with the incorporated dentin specimen adapted to the cast of a volunteer. The dentin specimen inserted into the mandibular appliance (right).

Figure 2

Mineral loss (Vol. % × μm) in dentin treated with fluoride (n = 15). The mean mineral loss from dentin was significantly lower in the group treated with 5000 ppm fluoride compared to the 250 ppm fluoride group and the control group. Mineral loss was not statistically significantly different between the 250 ppm fluoride and control group. (**p < 0.01, ***p < 0.001).

Figure 3

Lesion depth (μm) in dentin treated with fluoride (n = 15). The lesion depth in dentin of the 5000 ppm fluoride group was significantly lesser than in the 250 ppm fluoride group and the control group. In addition, the lesion depth of the 250 ppm fluoride group and the control group were not statistically significantly different. (*p < 0.05, **p < 0.01).