Atomic level observation and structural analysis of phosphoric-acid ester interaction at dentin

Kumiko Yoshihara, Noriyuki Nagaoka, Yasuhiro Yoshida, Bart Van Meerbeek, Satoshi Hayakawa

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

The functional monomer 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP), used in many dental adhesives, self-assembles in nano-layers at adhesive-tooth interfaces. Recently, several states of the P[sbnd]OH groups of 10-MDP_Ca salts were suggested, while their actual status has not been elucidated yet. We mechanistically investigated 10-MDP_Ca-salt nano-layering at adhesive-dentin interfaces, correlatively using scanning transmission electron microscopy with energy-dispersive X-ray spectrometry (STEM-EDS), X-ray diffraction (XRD) and solid state nuclear magnetic resonance (NMR). STEM-EDS confirmed the presence of Ca and P in each nano-layer. Both XRD and NMR revealed that the two terminal P[sbnd]OH groups of 10-MDP reacted with Ca. This twofold P[sbnd]OH interaction of 10-MDP with Ca was stable in water and is therefore expected to contribute to durable nano-layering of 10-MDP_Ca salts in the hybrid and adhesive layer. Statement of Significance: The functional monomer 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP), commonly used in dental adhesives with favorable long-term clinical outcome, has been documented to self-assemble into nano-layers at adhesive-tooth interfaces. Characterizing ultra-morphologically (STEM) and chemically (STEM-EDS, XRD, NMR) the mechanisms of interaction of 10-MDP with bulk dentin in a similar manner as what occurs clinically, it was found that the water stable 10-MDP_Ca salts consist of CaRPO4, meaning that the two [sbnd]OH groups of the phosphate group of 10-MDP ionically reacted with Ca. This stable structure is expected to contribute to durable nano-layering of 10-MDP_Ca salts in the hybrid and adhesive layer and hence to clinical longevity of the adhesively bonded tooth restoration.

Original languageEnglish
Pages (from-to)544-556
Number of pages13
JournalActa Biomaterialia
Volume97
DOIs
Publication statusPublished - Oct 1 2019

Keywords

  • Dentin
  • Functional monomer
  • Hydroxyapatite
  • Solid state NMR
  • TEM
  • XRD

ASJC Scopus subject areas

  • Biotechnology
  • Biomaterials
  • Biochemistry
  • Biomedical Engineering
  • Molecular Biology

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