Effects of acidic calcium phosphate concentration on setting reaction and tissue response to β‐tricalcium phosphate granular cement

Abstract Beta‐tricalcium phosphate granular cement (β‐TCP GC), consisting of β‐TCP granules and an acidic calcium phosphate (Ca‐P) solution, shows promise in the reconstruction of bone defects as it sets to form interconnected porous structures, that is, β‐TCP granules are bridged with dicalcium phosphate dihydrate (DCPD) crystals. In this study, the effects of acidic Ca‐P solution concentration (0–600 mmol/L) on the setting reaction and tissue response to β‐TCP GC were investigated. The β‐TCP GC set upon mixing with its liquid phase, based on the formation of DCPD crystals, which bridged β‐TCP granules to one another. Diametral tensile strength of the set β‐TCP GC was relatively the same, at ∼0.6 MPa, when the Ca‐P concentration was 20–600 mmol/L. Due to the setting ability, reconstruction of the rat's calvarial bone defect using β‐TCP GC with 20, 200, and 600 mmol/L Ca‐P solution was much easier compared to that with β‐TCP granules without setting ability. Four weeks after the reconstruction, the amount of new bone was the same, ∼17% in both β‐TCP GC and β‐TCP granules groups. Cellular response to β‐TCP granules and β‐TCP GC using the 20 mmol/L acidic Ca‐P solution was almost the same. However, β‐TCP GC using the 200 and 600 mmol/L acidic Ca‐P solution showed a more severe inflammatory reaction. It is concluded, therefore, that β‐TCP GC, using the 20 mmol/L acidic Ca‐P solution, is recommended as this concentration allows surgical techniques to be performed easily and provides good mechanical strength, and the similar cellular response to β‐TCP granules. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:22–29, 2020.