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Evidence of chemisorption of maleic acid to enamel and hydroxyapatite
Author(s) -
Fu Baiping,
Yuan Jun,
Qian Weixin,
Shen Qingyi,
Sun Xuemei,
Hannig Matthias
Publication year - 2004
Publication title -
european journal of oral sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.802
H-Index - 93
eISSN - 1600-0722
pISSN - 0909-8836
DOI - 10.1111/j.1600-0722.2004.00149.x
Subject(s) - maleic acid , x ray photoelectron spectroscopy , enamel paint , chemistry , aqueous solution , nuclear chemistry , inorganic chemistry , chemisorption , materials science , polymer chemistry , organic chemistry , chemical engineering , adsorption , polymer , copolymer , composite material , engineering
Maleic acid has been used as an etchant or non‐rinse conditioner in adhesive dentistry. However, the inherent mechanisms of the interaction of maleic acid with hydroxyapatite/enamel have never been fully elucidated. The purpose of this study was to provide evidence for the chemisorption of maleic acid onto hydroxyapatite/enamel, and to identify the reaction products obtained following the interaction of maleic acid with hydroxyapatite. Hydroxyapatite particles were dissolved in a 15% (w/v) aqueous solution of maleic acid (pH = 0.98). Half of the solution was dried to obtain a desiccated mixture. This mixture, hydroxyapatite, maleic acid and self‐prepared calcium maleate were analysed by X‐ray diffraction (XRD). Acetone was added to the other half of the solution to obtain a precipitate. This precipitate, hydroxyapatite, maleic acid, unetched enamel and maleic acid‐etched enamel were analysed by X‐ray photoelectron spectroscopy (XPS). The precipitate was also analysed by 1 H NMR. A new binding energy, indicating carboxylate groups, was detected by XPS on the precipitate and maleic acid‐etched enamel surface. XRD data indicated the formation of calcium maleate and calcium hydrogen phosphate after the reaction. NMR data revealed that one carboxylic group of maleic acid reacted with hydroxyapatite. Hence, maleic acid can chemisorb to hydroxyapatite and enamel via ionic interactions.