The Effect Of Early Removal Of Distractor And Implantation Of Titanium Nails On The Mandible After Distraction Osteogenesis

ObjectiveUsing cone-beam CT to compare the changes in bone density between the conventional stabilization group and the early titanium nail implantation group,and explore the effect of early removal of the distractor and immediate implantation of titanium nails on the maturation and mineralization of new bone,and to analyze the feasibility of early removal of the distractor and immediate implant repair after distraction osteogenesis for alveolar bone atrophy.Methods12 New Zealand rabbits weighing 2.5～3kg,male and female randomly,and healthy rabbits were selected.Under general anesthesia,a distractor was installed.After 5-day latent period,the mandible was pulled at a rate of 0.5 laps/12h.The rabbits were divided into three groups randomly Group A,Group B and Group C.Group A:removal of the distractor on consolidation period of 4^thweek;Group B:removal of the distractor on consolidation period of 8^th week;Group C:removal of the distractor on consolidation period of 4^th week and implanting titanium nails immediately for 4 weeks.Three groups were taken X-ray films and cone beam CT to observe and measure the changes of bone density after sacrifice.SPSS 23.0 was used to the difference of Bone Mineral Density among three groups.ResultsThe images of X-ray show:The direction of distractor has changed slightly after 8 weeks,and The direction of Titanium Nails did not change significantly after implanting Titanium Nail 4 weeks.CT values were observed by Cone-beam computed tomography and show:The average CT value of group C（289.33±47.60Hu）is similar to the average CT value of group B（290.33±45.65Hu）and the average CT value of NO-Ca（332.56±85.50Hu）（P>0.05）,There was no significantly difference among three sites,higher than the average CT value of group A（78.00±17.00Hu）（P<0.05）,lower than the average CT value of NO-Co（1316.22±76.19Hu）（P<0.01）,There was significantly difference among three sites.The vernier caliper measures the vertical height of the bone at the front of the osteotomy zone is increased by 1.7～2.8mm,Group A 2.29±0.35mm,Group B 2.17±0.34mm,Group C2.29±0.61mm,and the vertical height at the rear of the osteotomy zone has not difference significantly.ConclusionsThe bone density of Group C was significantly higher than group A,It is show that New bones have continued to mature and mineralize after removal of the distractor and immediately implantation of the titanium nail.There is no difference on the bone density of Group C and group B.We can make a preliminary inference that the maturation and mineralization of the new bone have not been affected significantly by the early removal of the distractor and the implantation of titanium nails...