The in vivo dissolution of tricalcium silicate bone cement.

This study aimed to investigate the in vivo dissolution of tricalcium silicate (Ca SiO , C S) bone cement in the rabbit femoral defect. Results indicated that C 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) were the main components of C S paste. The dissolution model of C S paste was a mass loss rather than a decrease in volume. The initial dissolution of C S paste (0 ~ 6 weeks) was greatly attributed to the release of Ca(OH) , and the later dissolution (>6 weeks) was attributed to the decalcification of C-S-H gel. Although the mass of C 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 S paste. The loss of Ca ions also resulted in the transformation of SiO tetrahedrons from Q and Q to Q , Q , and Q in C-S-H gel. Because only isolated SiO tetrahedrons (Q ) and Ca ions could be absorbed by the bone tissue, C S paste gradually transformed into a silica-rich gel. The fundamental reason for no decrease in volume of C S paste was that the SiO tetrahedron network still maintained the frame structure of C S paste during the implantation.