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Chemical Interaction of Phosphoric Acid Ester with Hydroxyapatite

2006; SAGE Publishing; Volume: 85; Issue: 10 Linguagem: Inglês

10.1177/154405910608501014

1544-0591

Daisuke Fukegawa, Satoshi Hayakawa, Yasuhiro Yoshida, Kazuomi Suzuki, Akiyoshi Osaka, Bart Van Meerbeek,

Dental Implant Techniques and Outcomes

Among functional monomers used in contemporary dental adhesives, 10-methacryloyloxydecyl dihydrogen phosphate (MDP) has been found to interact chemically with hydroxyapatite (HAp) most intensively and stably. This effect was thought to be the basis of the superior bonding effectiveness of MDP-based self-etch adhesives to enamel/dentin. To elucidate fully the chemical interaction and reactivity of MDP with HAp, we used 31 P CP-MAS NMR spectroscopy and powder x-ray diffraction. In an aqueous ethanol solution, Ca ions were leached from HAp to form, at short term, a MDP-calcium salt (CaMHP 2 ) layered structure on the HAp surface. When MDP was allowed to interact for longer time (< 24 hrs), CaHPO 4 ·2H 2 O precipitated on top of this MDP-calcium salt layered structure. In conclusion, the intense chemical interaction of MDP with HAp must be ascribed to superficial dissolution of HAp induced by the MDP adsorption and subsequent deposition of MDP-calcium salt with a solubility lower than that of CaHPO 4 ·2H 2 O.