New block graft of α-TCP with silicon in critical size defects in rabbits: Chemical characterization, histological, histomorphometric and micro-CT study

The study characterized Si-containing α-TCP blocks designed for graft application and examined their osseintegration in rabbit tibiae using histological, histomorphometric and micro-CT techniques. The block grafts were inserted into the critical size defects of 15 rabbits, using both tibiae, and examined at 15, 30 and 60 days. Results showed that new bone grew in direct contact with the block grafts and that the presence of silicon improved the stability and osseointegration of the material. Silicon doped TCP grafts showed enhanced mesenchymal cell differentiation and increased osteoblast activity compared with α-TCP. Furthermore, blocks with the highest concentration of silicon (3% C ₂S, 97% TCP) showed better dimensional stability and increased bone-to-implant contact values after 60 days (67.6 ± 5% lateral bone contact and 57.3 ± 3% base bone contact). None of the implanted materials were seen to produce any adverse inflammation. The study found that α-TCP ceramic blocks containing 3% C ₂S, offer good bioactivity, biocompatibility and allow new bone growth around the block and within the graft body, making this an ideal block graft material.