BACKGROUND:Studies have confirmed that the nano-hydroxyapatite/chitosan/alginate composite materials have a certain flexibility and strength and possess a bioactivity similar to human bone.
OBJECTIVE:To explore the effect of the nano-hydroxyapatite/chitosan/alginate composite materials on the repair of rabbit mandible defects.
METHODS:Bilateral mandibular defect models of 10 mm × 5 mm × 5 mm were made in 18 healthy New Zealand white rabbits. Then, the rabbits were divided into two groups:experimental group was implanted with nano-hydroxyapatite/chitosan/alginate composite material, and control group was implanted with hydroxyapatite/chitosan composite. At 4, 8 and 12 weeks after implantation, cone-beam CT was applied to observe implant degradation, cal us growth and bone connection in the defect area;new bone formation was observed by hematoxylin-eosin staining.
RESULTS AND CONCLUSION:The gray values of the bone density in the experimental group and control group gradual y increased with time, and there were remarkably significant differences between the two groups at different time points (P<0.01). At the same time point, the experimental group was superior to the control group in gross observation, cone-beam CT observation, gray value of CT and histological observation (P<0.05). At 4-8 weeks after implantation, the implant materials in the two groups were gradual y degraded with a blurred junction between the defect and bone tissue, and a smal amount of new bone formed tightly integrated to the recipient bone tissue, in which the experimental group was more significant. And during 8 to 12 weeks, the degradation of implanted materials in the two groups was basical y complete, and the implant began to merge with the recipient bone tissue, with further generation of new bone tissue and gradual repair of bone defect area, in which, the experimental group was more obvious. Results show that the nano-hydroxyapatite/chitosan/alginate can repair bone defects effectively, and promote the new bone formation.

Objective To analyze MRI manifestations of post-traumatic syringomyelia and its formation mechanism.Methods A retrospective analysis of the clinical data of 31 patients with post-traumatic syringomyelia was carried out.Morphous and signal features of spinal cord and syringomyelia was observed by MRI.Results Among 31 patients,11 cases had syrinx extending to cervical cord,6 cases extending to cervicothoracic cord,4 cases extending to thoracic cord,5 cases extending to thoracolumbar cord,5 cases extending to whole spinal cord.5 cases of 31 patients had syrinx ascending to medulla oblongata,1 cases ascending to pons.The post-traumatic syringomyelia had signal intensities similar to cerebrospinal fluid on T1-weighted sequences and uniformed or ununiformed signals of increased intensity on T2-weighted sequences.23 cases of all patients can demonstrate adhesion and traumatic tethering by MRI.Conclusion MRI can not only demonstrate the characteristics of post-traumatic syringomyelia but also describe the range of spinal cord,arachnoid and dura mater adhesions,which is of value in deciding how to perform operations.

Objective To compare the three-dimensional eephalometric and three-dimensional CT measurements of adult zygomatic complex among a Sanjiang population.Methods 120 female natives of Sanjiang region from Chinese Han between 19 to 23 years of age (mean 21.4 years),were randomly selected from students of Jiamusi University.Three-dimensional cephalometric and CT measurements of the face and skull were taken,with reference to zygomatic size measurement by Prof.Qi Zuo-liang,for the comparative study, which included the upper,mid and lower facial width followed by the length,width and angle of malar process,and width of the facial bone.Statistical analysis was done with the obtained measurements.Results Three-dimensional CT analysis showed facial width ratio of 0.83 and 0.79 and skeletal facial profile width ratio of 0.81 and 0.77,respectively,when compared with three-dimensional cephalometric analysis that showed facial width ratio of 0.84 and 0.77.Both values showed no statistical significance (P>0.05).Conclusion Three-dimensional CT measurement as the same to three-dimensional cephalometric can be used in the diagnosis of prominent malar complex.