The effect of 1,450 and 5,000 ppm sodium fluoride on polished dentin after citric acid erosion using change in step height.

Purpose: To measure step height change, using profilometry on dentin, after pre-treatment with sodium fluoride at 1,450 and 5,000 ppm and then erosion with citric acid. .

Methods: Dentin specimens (n= 150), sectioned from the coronal aspect of extracted human molars were randomly divided into three groups of 60 samples each and fully immersed in deionized water (control), or solutions of NaF with 1,450 ppm (F1450) or 5,000 ppm (F5000) for 3 minutes and then artificial saliva (not containing proteins) for 30 minutes. The samples were eroded for 10, 15, 20 or 25 minutes in 0.3% citric acid at pH 2.7. The mean step height change was calculated using confocal non-contact white light laser profilometry. .

Results: The mean (SD) step height for the control group at 25 minutes of acid exposure was 9.08 µm (± 0.74), for the F1450 fluoride group 8.74 μm (± 0.58) and for F5000 group 7.01 µm (± 0.56) µm, respectively. There were no statistically significant differences between the control group to the F1450 at any immersion times, whereas at F5000 there were statistically significant differences at all times (P< 0.0001). Within the limitations of this in vitro study, step height in dentin increased with time of exposure to citric acid and 5,000 ppm of sodium fluoride significantly reduced step height with artificial saliva.

Clinical Significance: 5,000 ppm NaF better protected dentin in an erosion model than concentrations commonly found in toothpastes.