Electrochemical mineralization of iron-tannate stain on HAp and bovine enamel-A non-peroxide approach

Abstract

Prolonged treatments for the destaining of teeth using high concentrations of hydrogen peroxide may cause secondary unwanted effects such as tooth hypersensitivity and gingival irritation. Hence, it is aimed to develop a non-peroxide-based method to oxidize iron-tannate (Fe-TA) stained hydroxyapatite (HAp) and bovine enamel (BE) samples. Constant current electrolysis (CCE) experiments were carried out on Pt working electrode in aqueous NaCl, KCl and KI solutions at discrete concentrations under continuous experiment and a non-continuous experiment. CCE shows that in the presence of iron tannate (Fe-TA) stained HAP, approximately 30 ppm of iodine was generated using 0.1M KI and nearly 40 ppm was produced with 0.2 M KI. By using a non-continuous CCE process, the lowest amount of chlorine was generated from NaCl solution, which was well within the safety limits for oral applications. Depending on the experimental conditions used, between 13 ppm and 124 ppm of chlorine was generated. CCE of Fe-TA stained on HAp using KCl reveals that at the lowest current density of 10 mA/cm 2 , the amount of hypochlorite generated was 20 ppm on Pt electrode having a surface area of 6 cm 2 . Ion chromatographic (IC) analysis revealed that non-continuous CCE of Fe-TA-BE in NaCl generated a low concentration of sodium perchlorate (0.8 ppm), whereas the continuous process generated no perchlorate, but a considerable higher quantity of chlorate for Fe-TA-BE (37 ppm) and Fe-TA-HAp (140 ppm) samples.