Self-setting β-tricalcium phosphate granular cement at physiological body condition: effect of citric acid concentration as an inhibitor

Abstract

The aim of this study is to investigate the effect of citric acid (CA) concentration as an inhibitor on the properties of β-tricalcium phosphate (β-TCP) granular cement. In this study, β-TCP granules were exposed to an acidic calcium phosphate solution containing 0.01 mol/L, 0.10 mol/L, and 1.00 mol/L of CA at physiological body conditions for 10 min. These specimens were denoted as 0.01 mol/L CA, 0.10 mol/L CA, and 1.00 mol/L CA, and its properties were characterized throughout the study. Physical appearance results showed that increasing citric acid concentration in an acidic calcium phosphate solution up to 1.00 mol/L reduced the self-setting ability of β-TCP granules. Meanwhile, compositional and morphological analyses showed the amount of dicalcium phosphate dihydrate (DCPD) crystals that precipitated and interlocked between β-TCP granules decreased when the concentration of citric acid increased. The decreasing trend of DCPD formation in set specimens increased its porosity and reduced the compression strength up to 27.4%. Therefore, these findings evinced that by altering the concentration of citric acid in an acidic calcium phosphate solution, the setting reaction of β-TCP granules at physiological body condition was inhibited.