| Sagittal split ramus osteotomy (SSRO) for mandibular deformity is a classic clinical surgical treatment in orthognathic surgery. Some Classâ…¡skeletal deformity patients are companion with hypertrophic mandibular angle. Using SSRO for treating dental deformity is necessary, besides it, treatments of these cases should be operated by mandibular angle reduction plasty to reach a more aesthetic face shape. By the way, in some cases of long face syndrome, the shape of mandibular angle will lead to a dissatisfied aesthetic effect when used SSRO for adjusting the jaw position. So,mandibular angle reduction plasty is also needed for these cases. But when treating patients with the clinical performances described above, it needs two-step procedures even more for satisfied face shape, because blood supply at mesial segment is always a problem when widely stripping masticatory muscles attached. So it will cause much inconvenience to patients, and a financial burden.The main purpose of this research is to verify the security and justifiability of the simultaneous mandibular sagittal split ramus osteotomy and mandibular angle reduction plasty. Blood supply postoperative is the biological basis of Orthognathic surgery. This research start from the blood supply, if the blood supply restored after surgery, then the simultaneous surgery is feasibleIn this study, the adult New Zealand white rabbits were used as subject,mandibular ostectomy is simulated for SSRO, and masticatory muscle dissection is simulated to the mandibular angle plasty. The simultaneous surgery of mandibular ostectomy and masticatory muscle dissection was as the experimental group,while the unilateral mandibular osteotomy was as a control group. The first 72nd hours after surgery, 1st week, 4th week, 6th week, 8th week, the blood supply of bone segment which was ostectomied in both two groups was observed by SPECT, and then compared with after mandibular osteotomy it blood supply of bone segment. The results are as follows:1. There is no remarkable necrosis of bone segment in mandibular gross specimen,the stump of bone healing could be achieved in the case of strict infection control. The appearance of the non-surgical mandibular angle was rich than the surgical side after operation, and operated side mandibular angle is less than non-surgical side.2. After operation,experimental rabbits and control rabbits was similar to the recovery:both two groups had experienced the compensation period and the recovery period of compensation, the blood supply can normally recover at the 8th week. The difference was not significant, P> 0.053. The difference of the blood supply among other periods is significant (p <0.05),however ,the difference at 6th week to 72nd hours and 8th week is not significant (p> 0.05), prompted that blood supply of the mandibular bone segments are Recoverable.Conclusion: The blood supplies of bone segments after the simultaneous mandibular osteotomy and the masticatory muscles dissection could basically recover. Healing of the bone segment could be observed, and there is no significant bone necrosis. SSRO can determine the initial plastic surgery and mandibular blood supply can be resumed. This study established the ideal animal model of simultaneous mandibular sagittal split ramus osteotomy and mandibular angle reduction plasty to detect the blood supply for bone segments after surgery. New orthognathic surgical procedures on the mandibular could be expected to design if further studies for promting recover of blood supply postoperative. |
