| Objective1. To establish an animal model for unilateral zygomatic arch defect in young minipig and study the influence of early unilateral zygomatic arch defect on craniofacial development.2. To study the influence of repairing zygomatic arch defect on craniofacial development in young minipig with pedicled deep temporal fascial periosteal cranial outer table flap and free cranial outer table inlay bone grafting and compare the difference of the two methods.3. To study the viability and blood supply of the pedicled deep temporal fascial periosteal cranial outer table flap after inlay bone grafting.4. To give a preliminary clinical evaluation of pedicled deep temporal fascial periosteal cranial outer table flap inlay bone grafting in repairing zygomatic arch defect.Methods1. Both craniofacial sides of five 8-week old Chinese experimental minipigs were randomly divided into the experimental and control side. A 2-cm long zygomatic arch defect was made on the experimental side and the control side was left intact. Skull X ray scan and three dimensional CT scan were performed before and after operation. The prognosis of the zygomatic arch defet was observed. The length of both zygomatic arches, the length and width of skull, and hemicranial angle of both sides were measured and compared.2. Ten 8-week old Chinese experimental minipigs were randomly divided into the experimental and control group. Both craniofacial sides of each animal were randomly divided into the experimental and control side. The control side remained intact. In the experimental group, the 2-cm long zygomatic arch defect was immediately repaired with pedicled deep temporal fascial periosteal cranial outer table flap inlay bone grafting. In the control group, the 2-cm long zygomatic arch defect was immediately repaired with free cranial outer table inlay bone grafting. Each animal underwent skull X ray scan and three dimensional CT scan before and after operation. The length of both zygomatic arches, the length and width of skull, and hemicranial angle on both sides were measured. The decalcified specimens were used for HE stain and CD31 immunohistochemical stain. The non-decalcified specimens underwent hard tissue slicing.HE stain, toluidine blue stain, Masson's trichrome stain and fluorescence microscope scan were performed.3. Both craniofacial sides of two 8-week old Chinese experimental minipigs were randomly divided into the experimental and control side. The 2-cm long zygomatic arch defect on the experimental side was immediately repaired with pedicled deep temporal fascial periosteal cranial outer table flap after inlay bone grafting. On the control side, the zygomatic arch defect was repaired with free cranial outer table inlay bone grafting. Laser Doppler flowmeter was applied to detect the blood flow of the combined cranial outer table flap during operation. Bone scintigraphy was performed regularly after operation to observe and compare the uptake of 99mTc-MDP. Both heads were infused with gelatin to anatomically examine the viability of the grafts and the distribution of microvessels. The specimens underwent histological, cytological and immunological examinations.4. Review the clinical applications of pedicled deep temporal fascial periosteal cranial outer table flap after inlay bone grafting in zygomatic arch defect repairing.Results1. At the end of the experiment, the zygomatic arch defect still existed. Before operation, the length of both zygomatic arches and both hemicranial angles showed no statistical difference. The zygomatic arch length on the experimental side was obviously larger than that on the control side at each observation point after operation. The hemicranial angle on the experimental side was notably less than that on the control side at each observation point after operation.2. Four zygomatic arch defects experienced bone union and one experienced fibrous union in the experimental group. In the control group, one zygomatic arch defect experienced fibrous union and the other four grafts almost totally absorbed. At each observation point, the zygomatic arch length and hemicranial angle on both sides showed no statistical difference in both groups. At the end of the experiment, the length of zygomatic arch on both sides was obviously larger than the-original one in both groups. The bone content of the grafts and the control zygomatic arches showed no statistical difference in the experimental group. In the control group, the bone content of the graft was notably lower than that of the control zygomatic arch. The mean bone density of the grafts and the control zygomatic arches showed no statistical difference in the experimental group. The detection of blood vessel, osteoblasts, osteoclasts and tetracycline fluorescence was positive in the experimental group and negative in the control group.3. A relatively stable blood flow was detected in the combined cranial outer table flap during operation. At each observation point, the uptake of 99mTc-MDP was positive in the middle of the grafts on the experimental side. Less uptake of 99mTc-MDP was detected in the middle of the graft on the control side two weeks after operation. After that, the uptake of 99mTc-MDP was negative in the middle of the grafts on the control side. There were abundant microvessels around the grafts on the experimental side and microvessels were found grown into the periosteum. The grafts were bulky and solid. On the control side, there was no obvious microvessels around the grafts. The grafts were smaller and fragile. The bone content of the grafts on the experimental side was obviously higher than that on the control side. The detection of blood vessel, osteoblasts, osteoclasts and tetracycline fluorescence was positive on the experimental side and negative on the control side.4. There were four clinical cases of repairing zygomatic arch defect with pedicled deep temporal fascial periosteal cranial outer table flap inlay bone grafting.The clinical result was stable and satisfactory. Conclusions1. Early unilateral zygomatic arch defect accelerates its growth in sagittal plane and impedes the hemicranial development in coronal plane. Early repairing zygomatic arch defect is essential to minimize the developmental craniofacial malformations.2. Early repairing zygomatic arch defect can impede the development of craniofacial malformations. The graft can survive and grow in the same speed with craniofacial skeletons after pedicled deep temporal fascial periosteal cranial outer table flap inlay bone grafting. The grafts survive better in quantity and quality after pedicled deep temporal fascial periosteal cranial outer table flap inlay bone grafting than free cranial outer table inlay bone grafting.3. The grafts have a relatively stable blood supply after pedicled deep temporal fascial periosteal cranial outer table flap inlay bone grafting and can ensure its viability.It is better than free cranial outer table.4. Repairing zygomatic arch defect is safe and effective with pedicled deep temporal fascial periosteal cranial outer table flap inlay bone grafting.
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