Calcium Phosphate Cement for Periodontal Bone Regeneration

Abstract

Treatment modalities for the regeneration of periodontal osseous defects are reliant on autografts and alloplastic bone substitutes, however, the most successful clinical outcomes are reported with the use of autografts. To overcome some of the limitations of existing bone graft materials, a cement based on calcium phosphate-calcium sulfate (CPC-CSH) with and without a phosphorylated amino acid residue, namely O phospho L serine (OPLS) is reported in this study. CSH is known to enhance the biodegradability and setting time characteristics of CPC cements due to its faster dissolution rate whilst OPLS is believed to stimulate the synthesis of hydroxyapatite in the formation of CPC-CSH cements since it can lead to improved bone growth. CPC and CSH cements were prepared at different weight ratios, with OPLS incorporated at 8 mol% into selected groups. The experimental types of cement were characterized using various techniques, including setting time assessment, compressive strength measurement, Young's modulus, water uptake study, pH measurement, FTIR, SEM, and in vitro biocompatibility assays. The results demonstrated that CSH decreased the setting time of CPC cements which was correlated to the concentration, whilst a further decrease was observed with OPLS in the cement matrix. FTIR spectral analysis confirmed the successful modification of the CPC matrix with CSH and OPLS. The compressive strength of CPC-CSH50 in dry conditions was significantly higher than other formulations, while OPLS enhanced the compressive strength of CPC alone. The inclusion of CSH showed mass loss when immersed in deionized water as expected due to the dissolution of this phase. However, the CPC CSH(50)-OPLS cement did not exhibit an equilibrium due to simultaneous uptake and loss during the process. The net loss in mass was the lowest for CPC-CSH50-OPLS cement due to the network formation initiated by OPLS. SEM analysis revealed increased porosity and the presence of CSD crystals in CSH-containing cements with a nanocrystalline hydroxyapatite structure in OPLS containing cements. In vitro cell viability assays showed that the developed cements were non cytotoxic. In conclusion, the modified CPC formulations incorporating CSH and OPLS demonstrated improved properties, such as reduced setting time, enhanced mechanical strength, tunable degradation, and favourable microstructural changes while maintaining biocompatibility. These findings highlight the potential of the new bone cement for clinical applications in non-load-bearing areas, such as periodontal bone defects. However, further research is needed to optimize the cement formulations and evaluate their performance in vivo to address the current limitations of bone grafts.