Papers by Author: Wen Zheng Wu

Abstract: Mandible defect and the lack of dentition may result in facial deformity and chewing organ defects. It happens after the surgery of oral and maxillofacial tumors. This study aims at this problem. In this study, Finite Element Analysis (FEA) was employed to reconstruct the implanted mandible for customized patient. The 3D FEA model has great importance for biomechanical analysis. Though the analysis of the biomechanical situation with different numbers of dental implants, we can optimize the location and quantity of the implants. In this way, we can improve the quality of the implants, reduce the pain of patients, reduce the operation cost and avoid secondary surgery.

Abstract: Aiming at the implanted mandible titanium plate in chewing movement under the action of repeated load is prone to fracture, leading to problems such as secondary surgery. This study makes fatigue simulation analysis for customized implanted titanium plate of fatigue damage. It also analyzes the minimum service life position and low service life area on different loading. Simulation analysis of deformation is done. The analysis contains the deformation area and the maximum deformation degree with a variety of bite condition. This study also analyzes and forecasts the fatigue failure area, which provides basis for preventing fatigue failure for implanted titanium plate. It has important significance to improve titanium plate service life and strength. It also could alleviate patients’ sufferings.

Abstract: Design methods for medical rapid prototyping (RP) of personalized cranioplasty implants are presented in this paper. RP offers an easier way to design customized implants and manufacture them within a very short period. Computed tomography (CT) scans were acquired on a General Electric CT scanner and converted to solid models using Mimics software from Materialise. Stereo lithography patterns were prototyped using Objet build style on a Eden 250.The models helped the surgeons plan and rehearse the surgery well in advance. RP biomedical model is greatly convenient to diagnosis and treatment planning. It could decrease the operation time and the risk of misinterpretation of the medical problem. A physical biomedical model also facilitates surgery planning and makes the rehearsal and simulation of the operation possibly.

Abstract: The most frequent cause of defect in the mandible is tumor-related surgery. Larger defects cause severe morbidity due to disturbances in function and esthetics. A fibular free flap is one way of filling a bony hole in either the upper or lower jaw. It is one of the common ways of replacing bone that has been removed for cancer treatment. Doctors use a free fibular flap which is grafted from the patient who needs a transplant operation to fit the defect. In this study, a new method combining preoperative planning and rapid prototyping for mandibular fibula free flap reconstruction after tumor surgery was made based on Mimics software simulating surgery on a workstation. The preparatory work of surgery is divided into two parts: software simulation and model building. During software simulation the authors were able to choose the best site for the osteotomies regarding circulation and the model building can increase the precision and speed of treatment. A description of our surgical approach is presented and is supplemented by an illustrative case.

Abstract: Patients suffering from mandible tumors often require a reconstructive surgery to repair the defects caused by large tumors. The particular type of reconstructive surgery studied in this paper is called free fibular flap reconstruction, which uses fibular segments to replace removed sections of the mandible and a titanium plate to provide strength. In order to decrease the dependence on design experience, decrease surgery time, and enhance the participation of surgeons in the design process, Rapid Prototyping (RP) biomedical models were employed to enable good visualization of the original and reconstructed geometry and for use as forming guides for the customized titanium plates. This study reports on one male and one female patients who underwent mandibular reconstruction. In one case, the operation time was reduced 2 hours and the other one was reduced 1.8 hours. The customized titanium plate shapes conformed to the patients’ mandible anatomy and were thick enough to provide the strength and stiffness needed to fix the mandible until the bone grafts and soft tissues heal.

Abstract: Aiming at the filature of titanium plates and screws after defective mandible reconstruction surgery, a method named Finite Element Analysis （FEA）was conducted in this paper through FEA software Abaqus with which a 3D model of defective mandible was established. The mandible 3D model was input into the Magics and remeshed. The mandible model was output in the format of .inp file from the Magics and import to Abaqus for converting from triangular meshes to tetrahedral meshes. The tetrahedral meshes totally had 71057 tetrahedral elements and 10720 nodes. The boundary constraints of the mandible 3D model were arranged. The force was applied separately in the direction of vertical, 15° and 30° with the occluding plane (teeth force range when occluding) to analyze the force. The mandible 3D model was established and prepared to be done a biomechanical analysis.

Abstract: Under the conditions of the mode of production drifting towards extensive collaboration mode, the process capacity oriented to machining factory should be analyzed and estimated, which is the essential precondition for factory to decide whether to accept a piece of manufacturing order form. Based on the situation, with the production quality checking and analysis focused, a kind of process capacity analysis and estimation was brought forward for the collaborational machining factory under the mode of quality control. The model based on quality driven for the process capacity estimation was provided to solve the critical problem. And the network service system of process capacity estimation was established, by making full use of quality function analysis (QFD), similar procedure query and rough set theory combined with the character parameters such as work-part size tolerance, surface roughness, manufacturing time, cost and etc. Furthermore, some key enabling technologies were instigated in detail, including quality control technology oriented low volume customization and process capacity analysis technology based on rough set (RS) theory.

Abstract: Aiming at a clinical case of a 52-year-old male patient, the patient’s mandible will be 3 Dimensional (3D) reconstructed and the surgery will be planed. This patient who suffered from mandibular tumor needed to undergo surgery. This study used a Toshiba 64-row Spiral CT to scan patient’s maxilla and mandible. 368 layers consecutive maxillary and mandibular CT images which scanning slice thickness is 1mm were obtained. The original images which format were DICOM were import to Mimics. After decided the bone threshold value the contour lines of every layers were extracted. Every image was passed the processing steps of edge division, selective editing, filling holes, wiping off redundant data and 3D reconstruction. After these steps the 3D geometric model of maxilla and mandible was obtained. The dimension of mandibular tumor and accurate location of the removal part were determined. These steps provide accurate original data for the manufacture of mandibular Rapid Prototyping (RP) model.