Changes of dentinal tubules following fluoride iontophoresis

Fluoride(F) iontophoresis is preferred over topical application to provide long lasting dentin desensitization. The purpose of this study was to evaluate the changes in dentinal tubules following fluoride iontophoresis under SEM observation. Teeth were divided mainly into 3 groups: controls, NaF treated teeth with iontophoresis and those without inotophoresis. A battery operated device was used to apply electric current to teeth. All the teeth were prepared for scanning electron microscopy after treatments. Fluoride treatment, either non-iontophoretic or iontophoretic, produced granular precipitation in dentinal tubules and reduced tubular diameter. In 5-minute non-iontophoretic NaF treated teeth, the depth of precipitate penetration was 75 microns on average where the granules were small and sparse. In the 5-minute iontophoretic NaF treated teeth, the average penetration of precipitation reached 250 microns in one application whereas in three applications to teeth the average depth of penetration reached 830 microns. Fluoride iontophoresis resulted in obstruction of dentinal tubules. Both the frequency and duration od treatment under constant current and voltage affected the size of particles, the form of precipitation and the depth of penetration. Larger particle size and deeper fluoride penetration were observed in iontophoresis treated teeth compared to non-iontophoresis treated teeth. Therefore, repeated fluoride iontophoresis treatment is suggested to ensure long lasting densensitization effects.