Histological and immunohistochemical evaluation of biphasic calcium phosphate and a mineral trioxide aggregate for bone healing in rat calvaria

This work focused on the process of bone repair of defects in standardized calvaria of Wistar rats treated with biphasic calcium phosphate (BCP), mineral trioxide aggregate (MTA), or a combination of the two. Eighty Wistar rats were divided into four treatment groups and were examined at 2 and 8 weeks. A surgical defect was created in the calvaria using a 6-mm diameter trephine drill. The cavity was treated with BCP, MTA, or BCP + MTA; untreated rats with clot formation served as controls. Samples were evaluated histologically and by immunohistochemical staining for areas of new osteoid tissue and new bone tissue, as well as the percentage of labelled cells using anti-bone morphogenetic protein receptor type 1B (anti-BMPR1B) antibodies. Statistically significant differences were found for all dependent variables (area of new osteoid tissue, area of new bone, and percentage immunostaining) by group (P < 0.0001) and time (P < 0.0001), and for the interaction of the two (P < 0.0001). The MTA group at 8 weeks showed the highest amount of osteoid tissue. The same group also exhibited the highest amount of bone tissue formation. The 2-week MTA samples and 2-week BCP + MTA samples exhibited the highest percentages of stained cells. The best results in terms of the area of osteoid and bone tissue formation and the percentage of BMPR1B were observed for the MTA group, confirming that the combination of BCP + MTA does not result in a significant improvement.