Chemical Interaction of a Self-Etch Adhesive Containing 10-MDP and HEMA with Dentin by Infrared and NMR Spectroscopies
Marc Vedrenne, Yann Prigent, Yasin Ahmed, Maria-Lorenzina Fiallo, Geneviève Grégoire.
Objectives: Physico-chemical interactions between human dentin and a self-etching adhesive containing 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP), 2-Hydroxyethyl methacrylate (HEMA), methacrylate-modified polyacrylic acid and ethanol has been investigated in order to highlight the functional monomer’s actions.
Methods: In vitro application of this self-etch adhesive on dentin was studied using Fourier Transform Infrared and Nuclear Magnetic Resonance spectroscopies.
Results: The infrared spectra illustrate the changes that occurred when the dentin powder were demineralized and infiltrated by the studied adhesive. The carbonate peaks are replaced by sharper vibrations related to smaller organic functional groups.
1D 1 H NMR spectrum in the mixture adhesive + dentin exhibits different percentages than adhesive alone showing that HEMA is consumed. 1D 31P spectrum of adhesive + dentin shows two wide signals. These wide signals indicate the presence of different phosphorus compounds. These are calcium salts due to the demineralization of dentin by 10-MDP. There is the formation of a mineral layer composed of 10-MDP-Ca salts absorbed on amorphous calcium phosphate or 10-MDP salts - phosphates. These salts formations are not disturbed by HEMA. The mixture adhesive + dentin, highlights that Bis-GMA is not consumed, 10-MDP partially and HEMA entirely.
Conclusion: The tested self-etching system produced different interactions with dentin. There are calcium salts due to the demineralization of dentin by 10-MDP. These salts formations are not disturbed by HEMA.
Clinical Significance: Understanding the molecular interactions between an adhesive and dentine is a major challenge to evaluate adhesive solutions that lead to the formation of an impermeable and durable resin/dentine interface. Functional monomers used in the adhesive must not interact negatively. Our results show that in the system tested 10-MDP does not inhibit the action of HEMA
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