Bone tissue response to an oily calcium hydroxide suspension in tibial defects. An experimental pilot study in minipigs.

OBJECTIVES The present study was conducted to evaluate the bone tissue response after the application of an oily calcium hydroxide suspension (OCHS) into defects created in the tibial bone of minipigs. MATERIALS AND METHODS Standardized defects (2 ccm) were created into the tibia of 4 Goettinger minipigs. Defects in the test group (n = 4) were filled with OCHS (Osteora, DFS-Diamon, Riedenburg, Germany). Defects in the control group (n = 4) were filled with venous blood. Animals were sacrificed after healing periods of 4 and 8 weeks. Tibias were dissected, soft tissues removed and processed for histological analysis. Digital images (×200) were evaluated using the software CellD (Soft Imaging System, Münster, Germany). The following histomorphometrical landmarks were identified: defect size, mineralized tissue, non-mineralized tissue and residual OCHS. RESULTS Healing was uneventful in all four animals. In the test group, new bone formation was observed in the vicinity of the defect margins whereas the centre of the defect was dominated by non-mineralized tissue. Mean percentages of mineralized tissue after 4 weeks were 23.01% in the test group vs. 43.45% in the control group. The mean value for residual OCHS was 7,11% at 4 weeks. After 8 weeks mean percentages of mineralized tissue were 28.15% in the test group vs. 44.39% in the control group as well as 7.05% for residual OCHS. CONCLUSION Within the limits of the present pilot study it can be concluded that OCHS did not have a beneficial effect on new bone formation. To prove an osteoinductive potential of OCHS further studies based on a higher number of samples are needed.