The Experimental Research On The Mechanism Of The Distraction Osteogenesis In Craniofacial Bone And Developing Of A New Device For Mandibular Distraction

The application of the technique of distraction osteogenesis (DO) on craniofacial bone deformity in clinic and animal experiment has been universally accepted. The basic research involved in the related subject progressed slowly; it was hardly vacant at home even though there were few papers published since 1996.The present research designed an animal experimental model for DO on craniofacial bone after a review of the related articles in which the DO method was studied mostly on the extremities in orthopedic surgery.Objectives: To develop and produce a new internal fixed mandible distraction device accommodate to craniofacial and plastic surgeries; To demonstrate the corresponding histological and biomechanical changes of the mandible and paramandible during DO process and to evaluate the advantages and disadvantages of the device. To gain experiences on application of the device for clinic use in future; To try to find out the mechanism of bone regeneration under the DO process; to raise out the basic principle and monitoring method for DO applications on craniofacial bone deformities.Material and method: The pure TAi2 was adopted as the metal material to fabricate the device in mechanic way. 15 native mongrel dogs aged 7 months to 1.5 years were selected as subjects to the experiment model. The self-made type MS-1 internal fixed mandible distraction device was used, through an extroral incision on skin inferior to the mandible marginal area. The corticotomy was performed at the area between the first and the second molar in mandibular body. After a latent period of 7 days postoperatively, the distraction rate was 1mm, and the distraction frequency was once per day respectively. The distraction tasted for 20ds while the mandible bone was lengthened for 20mm in length. Then, the retention period continued for 1～20 weeks with the device fixed to the mandibles, while the consolidation of the new bone generated in the distracted gap occurred. The new bone was marked by tetracycline injected via muscles. The X-ray examination was conducted once per week, and the photograph, casting of the dentures was taken pre and postoperatively too. The histological examination of the new bone and the perioperative soft tissues such as muscles,...