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Reaction characteristics of a tooth‐bleaching agent containing H 2 O 2 and NaF: in vitro study of crystal structure change in treated hydroxyapatite and chemical states of incorporated fluorine
Author(s) -
Tanizawa Y.
Publication year - 2005
Publication title -
international journal of cosmetic science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 62
eISSN - 1468-2494
pISSN - 0142-5463
DOI - 10.1111/j.0142-5463.2005.00275_2.x
Subject(s) - x ray photoelectron spectroscopy , fluorine , chemistry , dissolution , fluoride , hydrogen peroxide , nuclear chemistry , solubility , hydrogen fluoride , inorganic chemistry , chemical engineering , organic chemistry , engineering
This in vitro study was performed to elucidate the reaction mechanism of sodium fluoride (NaF), which is added to tooth‐bleaching agents to lessen the adverse effect of hydrogen peroxide (H 2 O 2 ) on teeth. Both hydroxyapatite (HAP) and dihydrated dicalcium phosphate (DCPD), model substances for dental hard tissues, dissolved easily in a simple H 2 O 2 solution. In the H 2 O 2 /NaF solutions, however, fluorine compounds that could not be identified by X‐ray diffraction (XRD) due to the smallness of the products were formed on the surface of the HAP. X‐ray photoelectron spectroscopy (XPS) studies demonstrated that fluoridated hydroxyapatite (FHAP) was formed on HAP, and that calcium fluoride (CaF 2 ) formation was accelerated by increasing the concentrations of fluorine and H 2 O 2 along with the partial dissolution of HAP. In H 2 O 2 /NaF solution, DCPD also transformed easily to FHAP and CaF 2 , which are favorable to the remineralization process on the tooth surface. Thus, the mechanism of NaF was elucidated, and its use together with H 2 O 2 for tooth bleaching was proved to be effective. Methodologically, the XPS two‐dimensional plot made it possible for the first time to directly estimate the ratio of FHAP and CaF 2 in the reaction products, in contrast to the conventional wet‐analytical method, which is simply based on the difference in solubility of the two components.