Calcium silicate-based bone cement incorporated with carbon nanotubes (CNT): In vitro and in vivo

Calcium silicate cements (CaSiO₃) are widely used in bone repair treatments for both medical and dental applications. To meet the demands of tissue engineering, three calcium silicate cements were developed: a control group without carbon nanotubes (CNT) and two experimental groups incorporating CNT nanoparticles at concentrations of 0.2% and 0.5%. The surface topography of the calcium silicate-based cements was analyzed using field emission scanning electron microscopy (FEG-SEM) and X-ray diffraction. Additionally, an in vitro cell viability assay was performed to assess cytotoxicity. An in vivo study was also conducted using 24 Wistar rats, where critical bone defects of 3.0 mm in diameter were surgically created in both tibiae using a trephine drill. A clot group was included as a control. Following euthanasia, the samples were evaluated through histological and histomorphometric analyses, and a three-point flexural biomechanical test was performed. Statistical analysis was conducted using one- and two-way ANOVA, with a significance level set at 5%. The results indicated that none of the cements exhibited cytotoxicity. Regarding bone neoformation, the clot group showed significantly lower values compared to the SiCa and SiCa+0.5%CNT (mass) groups (p < 0.05), while the SiCa+0.2%CNT group did not differ statistically from the others (p > 0.05). The biomechanical test revealed a statistically significant difference between the SiCa+0.2%CNT group and the SiCa and SiCa+0.5%CNT groups, with the SiCa+0.2%CNT group exhibiting lower values (p < 0.05), whereas the clot group showed no statistical difference from the other groups (p > 0.05). These findings indicate that the incorporation of carbon nanotubes (CNT) into calcium silicate cements did not result in significant differences in bone tissue regeneration when compared to cements without CNT.