A STUDY OF THE REGIONAL DISTRIBUTION OF BONE FORMED AROUND HYDROXYAPATITE IMPLANTS IN THE TIBIAE OF STREPTOZOTOCIN-INDUCED DIABETIC RATS USING MULTIPLE FLUORESCENT LABELING AND CONFOCAL LASER-SCANNING MICROSCOPY

THE PRESENT STUDY WAS DESIGNED to compare the amount and regional dist ribution of bone formation around hydroxyapatite (HA) implants in norm al (control) rats with that of animals with diabetes mellitus (DM), in duced by streptozotocin 2 weeks prior to implant placement. Calcein (G AL), alizarin complexone (AL), and tetracycline (TC) were injected on the 7th, 14th, and 21st days after implantation, respectively, and the rats were sacrificed on the 28th day after implantation. Seventy-mu m undecalcified sections of the HA-bone interface in both groups were t hen prepared for confocal laser scanning microscopy (CLSM) observation . In both groups, bone formation developed from the HA surface to the endosteum, periosteum, or bone marrow. In the control group, around th e HA close to the endosteum and periosteum, the new bone showed an ext ensive lamination pattern of three color layers (GAL, AL, and TC), but in the IDM group the labeling density of TC on the 21st day was low. In contrast, on the lateral part of the HA surface (away from the endo steum and periosteum), there was considerably less bone formation in t he control group, and in the DM group it was almost completely suppres sed. These findings indicate that bone formation around the HA was ini tiated from the HA surface in the control group, while in the DM group , bone formation along the lateral part of the HA away from the endost eum and periosteum was almost completely suppressed. Furthermore, it i s also suggested that in the new bone along the HA close to the endost eum and periosteum, only calcification on the 21st day was depressed.