Abstract
L-Ascorbic acid 2-[3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-1-benzopyran-6-yl-hydrogen phosphate] potassium salt (EPC-K1) is a conjugate of vitamin C and vitamin E that is water-soluble and stable at room temperature. EPC-K1 has been developed as a hydroxyl radical (·OH) scavenger and antioxidant. In a previous tooth whitening experiment, it was accidentally found that tooth (dentin) blocks were dissolved by EPC-K1 with H2O2. In the current study, high concentrations of EPC-K1 (2.5, 25 mM) with 3% H2O2 dissolved and caused the collapse of dentin blocks. Similar concentrations of EPC-K1 without 3% H2O2, however, dissolved the dentin blocks without collapse over a 3-week period. In these cases, a ·OH-like signal was detected using an ESR spin-trapping method. The volume of calcium in solution (including the dentin block) increased on the addition of EPC-K1 in a concentration-dependent manner. In addition, the calcium : phosphorus ratio changed from 2 : 1 in sound dentin to 1 : 2 in the collapsed dentin block. High concentrations of EPC-K1 are therefore considered to have calcium chelating and dentin dissolving activity. The dentin dissolving activity was enhanced when EPC-K1 was used with H2O2. EPC-K1 had no protective effect when used in tooth whitening with H2O2.
