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Mechanical Strength of Various Types of Calcium Phosphate Cements

Published

Author(s)

Y Matsuya, S Matsuya, Joseph M. Antonucci, S. Takagi, Laurence Chow, A Akashi, A Akamine

Abstract

It has been reported that organic or polymeric calcium phosphate cements can be made from reactive calcium phosphates with various organic acids or poly(alkenoic acids). Some of these cements are already commercially available for use as bioactive liners or bases in restorative dentistry. However, little is known of their relative mechanical properties. In this study, the mechanical strength and in vitro durability of several types of calcium phosphate cements were assessed.Two commercial cements and four experimental cements were tested in this study. Three sizes of tetracalcium phosphate (TTCP) particles, fine, medium and coarse, were used as the powder component of the experimental polymeric cements. The cement liquids used in this study were an aqueous solution (mass fraction = 25 %) of poly(methyl vinyl ether-maleic acid) (PMVE-Ma) and an aqueous solution (mass fraction = 50 %) of polyacrylic acid (PAA). Relative molecular masses of PMVE-Ma and PAA were about 50,000 and 5,000, respectively. The powder and liquid components of the commercial cements were examined by x-ray powder diffraction (XRD) analysis and nuclear magnetic resonance spectroscopy, respectively. Compressive, diametral and flexural strengths (CS, DTS, FS, respectively) were compared for these cements after 1 d storage in water. For CS, long term measurements also were carried out on water-stored specimens. After the CS measurement, the cement samples were ground and characterized by means of XRD.The DTS values of the commercial cements and of the experimental TTCP cement prepared using PAA ranged from 2.5 MPa to 6.0 MPa, with no significant differences between them. For the cements prepared using PMVE-Ma, DTS was not calculated, because the test specimens showed plastic deformation. The commercial cements and the experimental cement prepared from PAA showed higher CS values than the cements prepared from PMVE-Ma. However, these PMVE-Ma cements showed much higher FS values than the other cements tested in this study. A cement prepared with PAA having a relative molecular mass of 20,000 set too fast to be handled clinically. One of the commercial cements and the experimental cements prepared from PAA/fine TTCP or PMVE-Ma/coarse TTCP kept their 1 d CS strength after 3 months storage in water. On the other hand, the CS of the experimental cements prepared from fine and medium TTCP powders and PMVE-Ma decreased with aging time. This lowering of CS seemed to be related to hydroxyapatite (HA) formation in the set material. However, the HA-forming experimental cement using fine TTCP powder still had a value of the CS of 23.2 MPa ± 1.5 MPa (n = 6; mean ± standard uncertainty) after more than 1 year-storage in water. This value was comparable to the 1 d CS strength of the dental calcium hydroxide cement, Dycal, which does not maintain its CS on aqueous storage. Supported in part by Kyusu Univ., NIST, ADAHF and NIH grant DE11789.
Citation
International Symposium on Advanced Materials With Biomedical Applications

Keywords

apatite, calcium phosphates, cements, polymers, strength, x-ray diffraction

Citation

Matsuya, Y. , Matsuya, S. , Antonucci, J. , Takagi, S. , Chow, L. , Akashi, A. and Akamine, A. (2021), Mechanical Strength of Various Types of Calcium Phosphate Cements, International Symposium on Advanced Materials With Biomedical Applications (Accessed April 21, 2024)
Created October 12, 2021