The effect of iontophoresis delivery of fluoride in stannous fluoride desensitizing toothpaste on dentin permeability in human extracted teeth

This study aimed to determine the effect of iontophoresis delivery of fluoride in stannous fluoride (SnF(2)) toothpaste on dentin permeability in human extracted third molars. For dentin permeability test, 26 dentin specimens were randomly divided into 4 groups; SnF(2) without-iontophoresis (n = 10), SnF(2) with-iontophoresis (n = 10), no SnF(2) without-iontophoresis (n = 3), and no SnF(2) with-iontophoresis (n = 3). The hydraulic conductance of dentin (HD) was measured after smear layer removal, immediate treatment, 7 days, and acid challenge. The other 26 specimens were also prepared under these different conditions to assess degree of dentinal tubule occlusions using scanning electron microscopy (SEM). Percentage decrease of HD in SnF(2) without-iontophoresis after immediate treatment, 7 days and acid challenge were 38.38 ± 13.61, 56.92 ± 17.22 and 33.07 ± 23.57%. The corresponding values in SnF(2) with-iontophoresis were 42.16 ± 14.49, 62.35 ± 15.67 and 50.01 ± 12.60%, respectively. There was a significant difference between without- and with-iontophoresis groups after acid challenge (p < 0.05). For SEM, after 7 days, SnF(2) with-iontophoresis showed deeper dentinal tubule occlusion (p < 0.05) and more resistance to acid challenge than SnF(2) without-iontophoresis. No significant change was observed in groups of no SnF(2) treatment. Cathode iontophoresis could enhance the effect of SnF(2) toothpaste in decreasing dentin permeability and increasing resistance to acid challenge.