Investigation Of The Segmental Mandibular Defects In Dogs Reconstructed By Dsitraction Osteogenesis Using The Transport Disc With Tooth Extraction Wound

Objective: The experiments were carried out to certify whether the transport disc with tooth extraction wound can reconstruct the segmental mandibular defects by Transport Distraction Osteogenesis in dogs.Methods:Four dogs and two types of custom-made distractors were applied. Four dogs were randomly divided into two Groups. Type"I"and"T"distractors was separately applied to Group A and Group B. The mandibular defects were made by the resection from the second premolar to the fourth premolar in the right mandibular, at the same time, we pulled out the first molar in the two sides of mandible. The tooth extraction of left mandible wound were served as the controls. The transport disc was completed between the medial trump and the disc with tooth extraction wound of the first molar. Extraoral distractor was activited after 14 days at a rate of 1 mm per day and twice daily. Dogs were sacrificed at 8 weeks after the completion of distraction, and then the mandibular specimens were harvested and detected by X-ray, histology, as well as scanning electron microscopic analysis.Result:In the latency, the transporting disc of Group B were infected and necrotic. No infection of transport disc were happened in two cases of Group A during the distration period and the consolidation period. In A2 dog, new osteogeneration was failure, and the reason is that the screws for fixation of the transport disc were loosened during the consolidation period. Distration Osteogenesis in A1 dog was successful. The resluts of X-ray and histology confirmed that bone regeneration was perfect in the distraction gap of A1 dog. The transport disc shew less radiodense than the native mandibule. Compared with the control side, the transport disc develop a widely intramembranous ossification, and less bone was regenerated.Conclusion:1. It is feasible that using transport distraction osteogenesis of a transport disc with tooth extraction wound reconstructs the mandibular segmental defects.2. The placing area of the screws for the fixation of the transport disc should avoid the extration sockets, or else, the transport disc will be infected and necrotic.3. The reported custom-made distractor for segmental mandibular reconstruction may be applicable in the reconstruction of the mandibular segmental defects.