Polymeric calcium phosphate cements derived from poly(methyl vinyl ether-maleic acid)

Objectives. The purpose of this study was to assess the feasibility of forming polymeric calcium phosphate cements from a mixed powder of dicalcium phosphate/tetracalcium phosphate or only tetracalcium phosphate and poly(methyl vinyl ether-maleic acid) (PMVE-Ma), and to study their setting reaction. Methods. The setting reaction process of the polymeric cements was evaluated by mechanical strength tests, infrared spectroscopy and x-ray diffraction analysis and compared with that of a water-setting calcium phosphate cement. The mechanical strength data were analyzed using ANOVA and Scheffe's multiple comparisons test. Results. Cements prepared from the mixed powder and 25-30 wt% aqueous solutions of PMVE-Ma had high mechanical strength after 24 h storage in distilled water at 37 degrees C. The hardening mechanism depended on an acid-base reaction between the carboxyl groups of PMVE-Ma and the mixed powder, especially its tetracalcium phosphate component. The formation of hydroxyapatite in the polymeric calcium phosphate cement was not detected and is apparently inhibited as a result of the competing reaction of PMVE-Ma with the mixed powder. Significance. The cement-forming reaction was significantly faster than that of a water-setting calcium phosphate cement and slower than that observed with the mixed powder and polyacids such as poly(acrylic acid). The characteristics of the polymeric cements suggest that the materials may be useful in cavity lining or endodontic sealing.