Acrylophosphonic acid reactivity with calcium ions and biological apatite.
OBJECTIVE
Acrylophosphonic acid (H(2)L) was reacted with biological apatite originating from dental enamel powder in order to identify and study the reaction products formed during the use of self-etch monomers. Nuclear magnetic resonance spectroscopy (NMR) showed the formation of brushite and a calcium salt of acrylophosphonic acid. This Ca salt was further synthesized and characterized by NMR, Fourier transform-infrared (FT-IR) and chromatography coupled with potentiometric analysis. The results reveal that calcium ions form a compound with two mono-deprotonated acrylophosphonate anions at physiological pH values. Thus, dissolution of the biological apatite by the acid-etch releases phosphate and calcium ions that combine to form brushite. The remaining dissolved Ca neutralize the acrylophosphonic acid to form an ionic salt of formula Ca(HL)(2).


CONCLUSIONS
The stoichiometry of this calcium salt allows us to conclude that, following a self-etch procedure, dissolved Ca ions participate in the formation of crosslinks in the complex photopolymerized copolymer composite network of the hybrid layer.
Bayle
Marie A
MA
Department of Biomaterials, Faculty of Odontology, University Toulouse III, Toulouse, France.
Nasr
Karim
K
Grégoire
Geneviève
G
Sharrock
Patrick
P
D000134:Acid Etching, Dental; D000180:Acrylic Resins / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry; D002130:Calcium Phosphates / Q000138:chemical synthesis; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D004164:Diphosphonates / Q000138:chemical synthesis; D006801:Humans; D006882:Hydroxyapatites / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008964:Molar, Third; D063065:Organophosphonates / Q000737:chemistry*; D044367:Phase Transition; D019279:Resin Cements / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
D000180:Acrylic Resins; D002130:Calcium Phosphates; D017220:Dentin-Bonding Agents; D004164:Diphosphonates; D006882:Hydroxyapatites; D063065:Organophosphonates; D019279:Resin Cements; C494366:calcium phosphate, dibasic, dihydrate; D002118:Calcium