Behavior of plaster of Paris-calcium carbonate composite as bone substitute. A study in rats.

Calcium sulfate, also known as plaster of Paris (POP), is probably the oldest biomaterial used for bone grafting and considered to be a fast degradable material that allows complete resorption before the bone defect area is completely filled by new bone. The aim of this study was to investigate the possibility to combine POP with calcium carbonate in order to increase the the osteoconductivity of this material. Twenty four male Sprague Dawley rats, 5-months-old and weighing 300-350 g, were used in the study. Various treatment groups were created by the implantation of cylindrical samples of POP-100, POP-075 and POP-050 into the femoral condyles. After 1 and 4 weeks of implantation, rats were sacrificed and the implanted areas and the surrounding tissue were retrieved for histological analysis. The study was completed by an in vitro experiment, which included the soaking of the experimental materials into simulated body fluid. The results indicated that the composites were appropriate to be used as bone grafting material. The incorporation of CaCO3 into POP did decrease the degradation rate of the cements and induced faster bone formation, thus provides promising properties to this material.