The FT-IR and FT-Raman spectra of the calcium phosphates, hydroxyapatite {dollar}rm (Casb{lcub}10{rcub}(POsb4)sb6(OH)sb2),{dollar} fluroapatite {dollar}rm (Casb{lcub}10{rcub}(POsb4)sb6Fsb2),{dollar} monocalcium phosphate monohydrate {dollar}rm (Ca(Hsb2POsb4)sb2Hsb2O),{dollar} dicalcium phosphate dihydrate {dollar}rm (CaHPOsb4cdot 2Hsb2O),{dollar} anhydrous dicalcium phosphate {dollar}rm (CaHPOsb4),{dollar} have been recorded at ambient and high pressure ({dollar}<{dollar}50 kbar). Several pressure-induced phase transitions were detected. Some new information and general conclusions about the structure, chemical bonding and hydrogen bonding in these materials are presented. The high-pressure experimental method was improved.; The interactions between dentin, collagen and hydroxyapatite and the dental materials, 2-hydroxyethylmethacrylate and dipentaerythritol pentaacrylate phosphoric acid ester were explored by FT-IR, FT-Raman and NMR spectroscopy. Vibrational bonds were assigned for these materials. The results suggest that some hydrogen bonding or chemical reactions occur on the interface of dentin and dental materials. The interaction between dentin and 2-hydroxyethlmethacrylate mainly takes place between collagen and 2-hydroxyethylmethacrylate. On the other hand, the interaction between dentin and dipentaerythritol pentaacrylate phosphoric acid ester primarily occurs between hydroxyapatite and dipentaerythritol pentaacrylate phosphoric acid ester. The interaction of maleic acid with 2-hydroxyethylmethacrylate was studied by FT-Raman and NMR spectroscopy. The results show no evidence for a chemical reaction happening between these two compounds. The high-pressure FT-IR spectra of some restorative materials were also recorded and the results were interpreted.
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