objective: To study the stress distribution of abutment dentin of mandibular complete overdenture based on post core abutment(COBPA). Methods: 3 D FEM was employed to investigate the stress distribution of abutment dentin of mandibular COBPA and natural abutment(NA) on standard model, the data were compared. Results: In the same loading condition, stress concentration was observed at the root end area of dentin in both COBPA and NA. When post core was applied decreased stress distribution area and increased stress value were found aroud tooth neck, decreased stress concentration was found at root end. Conclusion: In COBPA and NA the stress may be transferred to the root end along the axis. Apart from retention, post core can transfer and buffer the stress, change the way of stress transfer, and may result in cervical fracture.

Objective: To enable an artificial mandible substitute to be mostly suitable for mandibular reconstructon in individual patients. Methods: Use rapid prototypinlg and surface imitating as the primary technology for individualized design and manufacturing of the artificial mandible substitute. Results: An individualized artificial mandible substitute was designed and prepared. Conclusion: Rapid prototyping is feasible in individualized bone substitute preparation.

Objective: To enable an artificial mandible substitute to be with individualized shape in the individual patient. Methods: Rapid prototyping and surface imitating were used as the primary technology in the individualized design and manufacturing of the artificial mandible substitute. Results: The shape and size of the manufactured artificial mandibe were almost the same to those of the original natural one. Conclusion: Rapid prototyping may be used in individualized bone substitute preparation.

Objective:To investigate the stress distribution of the edentulous maxilla with unilateral maxillary defect after implant rehabilitation under occlusal loads.Methods:Three dimensional finite element model of the edentulous maxilla with unilateral maxillary defect was build.The stress distribution of the edentulous maxilla under occlusal loads with computer simulated implant rehabilitation was investigated.Results:Regardless of load manner,the stress of the bone around 1 were high when just healthy side implanted,but the stress reduced after implantantion in health side combined with the implantation in zygoma in defect side.Conclusion:Implantation in health side combined with that in zygoma in defect side can reduce the stress of the bone around the implant.

Objective To solve some problem in present cervical spinal disc.MethodsAfter analyzing the function of cervical spinal disc, 2 kinds of materials were chosen to design and fabricate the double-layer cervical spinal disc prosthetic. CAD and ANSYS technologies were used to optimize 4 kinds of the new prosthetic structure.Results and ConclusionThe materials if the prosthetic is proper, and the double-layer column structure of the new prosthetic shows some excellence characteristics,including maximum stress of nucleus and annulus properly, simple structure and can be facilitated and exactly graft.

Focusing on the poor mechanical strength of porous bioceramics bone scaffold, and taking into account of the good mechanical properties of biodegradable magnesium alloy, we proposed a novel method to fabricate magnesium alloy/bioceramics composite bone scaffold with stereolithography double channels. Firstly, a scaffold structure without mutually connected double channels was designed. Then, an optimized bioceramics scaffold was fabricated according to stereolithography and gel-casing. Molten AZ31 magnesium alloy was perfused into the secondary channel of scaffold by low-pressure casting, and magnesium alloy/bioceramics composite bone scaffold was obtained when magnesium alloy was solidified. The compression test showed that the strength of bioceramics scaffold with only one channel and without magnesium alloy was (9.76 ± 0.64) MPa, while the strength of magnesium alloy/bioceramics composite scaffold with double channels was (17.25 ± 0.88) MPa. It can be concluded that the magnesium alloy/bioceramics composite is obviously able to improve the scaffold strength.
Alloys ; Biomechanical Phenomena ; Bone and Bones ; Ceramics ; Humans ; Magnesium ; Materials Testing ; Porosity ; Tissue Scaffolds

Objective Due to the problem of individual matching, exclusivity and loose with pure mechanical fixation for artificial hemi-knee joints made by traditional method, a new manufacturing process based on rapid prototyping technique and custom-made concept is presented.MethodsRapid prototyping was processed to rapidly and accurately shape the prototype of an artificial implant almost with the same shape as the hemi-knee joint of the patient, and the process based on Titanium alloy centrifugal casting technology and biomaterial sintering molding technology was used to fabricate the artificial hemi-knee joint and bioactive proximal tibia artificial bone, respectively.Results and ConclusionThe custom-made knee joint prosthesis has been fabricated and put into clinical use successfully. In comparison with the traditional implants, this system can realize the well matching movement between the artificial hemi-knee joint and its opposite. Meanwhile,the design of functional holes and tibial nails realizes the combination of biological fixation with mechanical fixation for the artificial implant,and the use of bioactive artificial bone promotes bone growth and minimizes the exclusive reaction.

Purpose　To study the main points of the diagnosis and differential diagnosis of the lymphadenitis in CSD. Methods　Expression of CD45, CD3 and CD68 were evaluated immunohistochemically (S-P method). Results　Five cases of microabscess in early stage and 21 cases of microabscess-granuloma were found. The histologic features were the formation of microabscess and granuloma. The early microabscess in the lymphnodes were surounded by B lymphocytes (CD20+) and macrophages (CD68+). The typial microabscess granuloma were surrounded by epitheloid cells (CD68+) and CD3 positive T lymphocytes. Conclusion　The main characteristic of the lymphadenitis of cat scratch disease is the formation of granuloma with microabscess. The immumohistochemical markers are useful to distinguish the proliferative cell types. This lesion may result from bacterial infection which induces the cell immune reaction.

BACKGROUND:At present, there are several limb-preserving methods,such as xenogenic bone joint replacement, artificial metal prothesis replacement and inactivation and replantation of tumor bone segment, etc.Each method has its advantages and disadvantages. In addition, mismatch of xenogenic and autogeneic joints and articular cartilage necrosis in the late stage, which affects joint function, are two important problems for large frozen bone-joint allograft at ultra-low temperature in repair of bone defect following bone tumor resections in extremities.OBJECTIVE:To evaluate a method to obtain outline information on the cartilage surface through spiral CT scanning data, so as to lay foundation for study on individualized artifical semi-knee joint based on rapid prototyping (RP) technique.DESIGN: Open experiment.SETTING: First Department of Trauma, Urumqi General Hospital of Lanzhou Military Area Command of Chinese PLA.MATERIALS: This experiment was carried out at Institute of Orthopaedics, Xijing Hospital, Fourth Military Medical University of Chinese PLA, and Institute of Advanced Manufacturing, Xi'an Jiaotong University from September 2001 to May 2003. CT scanning subject was a 25-year-old healthy male volunteer.METHODS:Distal femur was performed 1 mm in thickness scanning with Picker 6 000 spiral CT. Three-dimensional volume reconstruction was conducted at the Voxel Q Image workstation on Picker 6000 CT, then, two-dimensional tomography image of reconstruction data were downloaded with spacing of 0.1 mm. Data format converter software was self-developed. The downloaded image was treated through smoothing, de-noise and so on.Vector data of two-dimensional borderline outline of tomography image was calculated and input into Surfacer 9.0 software (American Imageware company) for vectorial three-dimensional reconstruction. According to recognition of articular cartilage outline and request of prothesis design, the threedimensional images of interested articular cartilage surface outline were extracted and used in the computer-aided design for individualized artificial semi-knee joint.MAIN OUTCOME MEASURES:Vector converting of CT image and vector image of three-dimensional reconstruction of femoral condyle.RESULTS:Vector converting of CT image dafa had been come true using self-developed medical image vector converter software. Three-dimensional solid model of individualized femoral condyle was constructed with Surfacer9.0 three-dimensional processing software and edited according to design request. Three-dimensional model of articular cartilage requested by artifical semi-knee joint prothesis was extracted for computer-aided design. The constructed articular surface outline could be treated further to complete computer-aided design of artificial semi-knee joint prothesis; The file format was .stl, which could be recognized by RP software and used in engineering.CONCLUSION:Vector reconstruction of articular cartilage outline is performed based on spiral CT data that can obtain precise three-dimensional solid model of articular cartilage outline. The three-dimensional model can be edited, which lays foundation for computer-aided design and RP manufacturing of artificial semi-knee joint prothesis compounded with large segment xenogenic bone; It is easy and practicable in vector converting of medical image information with this method, and it also has good application prospect in biomanufacturing field in orthopaedic and oral maxillofacial surgery.

BACKGROUND:With significantly individual differences in the anatomy of the knee joint, traditional total knee replacement is difficult to accurately predict the position of locating limb alignment, size of the prosthesis and osteotomy amount of patients during operation. OBJECTIVE:To investigate the clinical effect of total knee replacement based on the assistance of medical image reconstruction, computer-aided design technology and 3D-printing personalized surgical navigation template. METHODS:Medical image data of patients were col ected using CT or magnetic resonance scanning equipment. The three-dimensional reconstruction of the bone was conducted by two-dimensional medical image processing technology. The navigation template was designed by computer-aided design technology. The personalized surgical navigation templates were produced by 3D printing technology, and the clinical total knee replacement was conducted. The postoperative results were evaluated using imageology. RESULTS AND CONCLUSION:Arigin 3D Pro (Arigin Medical Co., Ltd.) can accurately reconstruct a three-dimensional model of the lower limb bones. The three-dimensional design software Arigin Surgical Templating by their independent research and development can precisely pinpoint related lower limb axis, including limb alignment, rotation axis of the femur and osteotomy reference point. The personalized navigation template we researched and produced for knee surgery fitted tightly with femoral condyle and tibial plateau bone anatomy during operation, without significant movement. The deviation of patients’ limb alignment was less than 3° after total knee replacement.