The in vivo dissolution of tricalcium silicate bone cement

Abstract This study aimed to investigate the in vivo dissolution of tricalcium silicate (Ca 3 SiO 5 , C 3 S) bone cement in the rabbit femoral defect. Results indicated that C 3 S paste directly integrated with the bone tissue without the protection of the bone‐like apatite. Calcium silicate hydrate gel (C–S–H gel) and Ca(OH) 2 were the main components of C 3 S paste. The dissolution model of C 3 S paste was a mass loss rather than a decrease in volume. The initial dissolution of C 3 S paste (0 ~ 6 weeks) was greatly attributed to the release of Ca(OH) 2 , and the later dissolution (>6 weeks) was attributed to the decalcification of C‐S‐H gel. Although the mass of C 3 S paste could decrease by more than 19 wt % after 6 weeks of implantation, the created pores (<1 μm) were not large enough for the bone tissue to migrate into C 3 S paste. The loss of Ca ions also resulted in the transformation of SiO 4 tetrahedrons from Q 1 and Q 2 to Q 0 , Q 3 , and Q 4 in C‐S‐H gel. Because only isolated SiO 4 tetrahedrons (Q 0 ) and Ca ions could be absorbed by the bone tissue, C 3 S paste gradually transformed into a silica‐rich gel. The fundamental reason for no decrease in volume of C 3 S paste was that the SiO 4 tetrahedron network still maintained the frame structure of C 3 S paste during the implantation.