Treatment of Dentine Hypersensitivity by Iontophoresis: In Vitro Pilot Study

Objectives: The purpose of this study was to evaluate, using scanning electron microscope, the ability of iontophoresis to block patent dentinal tubules using different agents. Methods: Dentine discs were obtained from recently extracted none carious human third molars. The crowns and roots were transversely removed and 1.5mm thick dentine discs were sliced using low speed diamond edge-coated microslice mounted on a milling machine (Paraskop® M, BEGO, Germany) with water irrigation. Dentine discs were then smoothened using Arkansas stone manually and prepared for agents application. Each disc was divided into four quadrants, the first quadrant served as negative control, the second was treated with iontophoresis with distilled water, the third was treated with the agent without iontophoresis, the forth was treated with iontophoresis with agent. Four agents were used these include 2% NaF, 0.4% SnF Gel, 3% potassium oxalate, and (6% NaF, 6%CaF)fluoride varnish. Dentine discs were prepared for SEM imaging. Surface imaging and analysis was applied by the same examiner. Results: No treatment quadrant showed completely patent dentinal tubules. Iontophoresis with distilled water quadrant showed loss of dentine surface characteristics with complete closure of dentinal tubules. Agent quadrants treatment revealed either complete dentine surface coverage when (6% NaF, 6% CaF) fluoride varnish was used, or almost no effect with patent dentinal tubules with other agents. 2% NaF, 0.4% SnF, and 3% potassium oxalate iontophoresis revealed complete blockage of dentinal tubules. Iontophoresis ruptured the surface layer of fluoride varnish and revealed patent dentinal tubules beneath the surface. Conclusion: In vitro evaluation of iontophoresis use with 2%NaF, 0.4% SnF, and 3% potassium oxalate appears to be efficient in blocking dentinal tubules. Iontophoresis seems to have a physical effect on dentine surface as it melted the dentine surface and closed dentinal tubules when used with distilled water.