[Effects of local administration of cyclophosphamide on mandibular condyle growth in growing rats]

The purpose of this study was to identify the effects of the local administration of cyclophosphamide (CP) on mandibular condyle growth in growing rats. Sixty three 4-week old male Sprague Dawley rats were used in this study. In the experimental group, CP (50 mg/ml) 0.02 ml was injected into both articular capsules of the condyle, while the control group was injected with physiological saline (Experiment I). Histological observation: The animals were sacrificed either at 3, 5, or 7 days after injection of CP or physiological saline. The condyles were extracted and the sections were prepared for histological and histomorphometric observations. The number of BrdU positive cells, the number of osteoclasts, the thickness of the cartilage layer and the amount of endochondral bone growth in the condyle were measured (Experiment II). Morphological observation : 4-week-old male Sprague-Dawley rats were grouped into control group, CP (25 mg/ml) treated group, and CP (50 mg/ml) treated group. These injections were performed one time at 7-day intervals, and then all rats were killed on the 7 th day after the last injection. The effects of CP local administration on the mandible were investigated morphologically using cephalometric analysis. In experiment I, there was a significant decrease in the BrdU positive cells, the thickness of the cartilage layer, and the amount of endochondral bone growth in the experimental group. In experiment II, the condyle of the CP (50 mg/ml) treated group was significantly shorter than that of the control group. These results demonstrate that local administration of CP into growing condyle inhibited mandibular condyle growth.