Comparison Of Recombinant Human Parathyroid Hormone 1-34 On Mandibular Distraction Osteogenesis In The Rabbits In Different Phases

Objective Comparison of recombinant human parathyroid hormone 1-34 on mandibular distraction osteogenesis in the rabbits in different phasesExperimental Methods 28 Japanese big-eared rabbits(weight 2.0-2.5 kg) with 3 months which were numbered randomly, were divided into four groups at random. Every group was divided into 7 rabbits and unilateral DO models were established at the right side of the mandible of the rabbits. The first group was injected subcutaneously rh PTH(1-34) of the corresponding dose respectively in the beginning of the Distraction period for 7 days. The second group was injected in the beginning of the consolidation period for 7 days. The third group was injected in the beginning of the consolidation period for 3 weeks and the fourth group was injected in the beginning of the Latency period for 7 days. 28 Japanese big-eared rabbits were executed separately after 3 weeks after completion of experiment, and the specimens of DO were harvested. The gross observation, Micro-CT examination, histological study and immunohistochemical staining of BMPs and VEGF were performed.Results All the experimental animals were tolerated with DO operations. Postoperatively, no infection or other copmplication occurred. 1、General observation: There were new bone formations in all the rabbits in four groups, and the new bone had good.continuity. Among them, the dye color of the new bone of the third group was deeper than that of other groups. The cambium was most closely connected with the margin of the distraction area in third group. The dye color of the new bone of the second group was deeper than that of the first and fourth groups, as well as the combination of the cambium with the margin of the distraction are. 2、Histological observation: The second and the third groups were better than other groups in formations of new vessels and new bone, and the difference was statistical significant. The third group was better than the second group in formations of new vessels and new bone, and the difference was statistical significant. 3、Immunohistochemical display: The expressions of VEGF、BMPs were higher than that of other groups,and the third group was better than the second group in expressions of VEGF BMPs.The differences between them were statistical significant. 4、Observations under Micro CT:The bone density and HU in the third group were higher than that of other groups,The bone density and HU in former three groups were higher than that of the fourth group.The difference of bone density and HU between the second and the third group had no statistical significance.Conclusions Rh PTH(1-34) promotes the formation of new bone in the distracted gap during mandibular DO in rabbits in the early of consolidation period.