Preparation, Material Properties and Biocompatibility of New Calcium Phosphate Cements

Objectives:'' There is a high clinical demand for synthetic bone substitution materials, due to drawbacks associated with biological bone grafts. New polymeric calcium phosphate cement composites (CPCs) were developed. Methods:'' Cement powder consisting of 60 wt% tetracalcium phosphate, 30 wt% dicalcium phosphate dihydrate, and 10 wt% tricalcium phosphate was combined with either 35% w/w poly methyl vinyl ether maleic acid or polyacrylic acid to obtain CPC-1 and CPC-2 respectively. Commercial hydroxyapatite cement was selected as control. The setting time and compressive and diametral tensile strength of the CPCs were evaluated and compared with that of commercial hydroxyapatite cement. Set cements ( n=6) were placed in cell culture in direct contact with ROS 17/2.8 osteoblast-like cells for (24 hr, 48 hr, and 1 wk) after which cellular function was assessed using the MTT assay. MTT activity was expressed as percentage of Teflon negative controls. In vivo biocompatibility of CPC-1, CPC-2 and hydroxyapatite cement (control) was assessed by subcutaneous implantation in rats for (7, 30 and 90 days) post implantation periods. Implant sites were excised, formalin fixed and prepared for histology. Sections of 6um were stained with hematoxylin and eosin and assessed by light microscopy. The inflammatory reactions were analyzed using descriptive histopathological analysis. Tissue respnses were graded as mild, moderate or severe. Results:” The setting time of the cements was 5–15 min. CPC-1 and CPC-2 showed significantly higher compressive and diametral strength values compared to hydroxyapatite cement. CPC-1 and CPC-2 were equivalent to Teflon controls after 1 week. CPC-1, CPC-2, and hydroxyapatite cement elicited a moderate to intense inflammatory reaction at 7 days which decreased over time.Conclusion:" CPC-1 and CPC-2 demonstrated reasonable setting times and high mechanical properties. By virtue of these characteristics, coupled with their in vitro and in vivo biocompatibility, CPC-1 and CPC-2 have properties that show promise for dental and orthopedic applications.