“…The action of RT lies in the suppression of the proliferation of mesenchymal cells and therefore prevents pluripotent mesenchymal cell differentiation into osteogenic progenitors [5,11,24]. In vitro studies have shown that there is almost no effect on mineralization and osteoinductivity in irradiated cells [38]. On the other hand, the inhibition of HO by indomethacin is probably due to a nonspecific suppression of the prostaglandin-induced inflammatory response which is present in the postoperative period [17], by inhibiting the prostaglandin synthesis mechanism [16,40] and a synchronous direct inhibition of the differentiation of mesenchymal cells into osteogenic cells [39,42].…”