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At least 199 records · Page 11Linked to original sources
PubMed1985

Experimental fittings of sockets for below-knee amputees using computer aided design and manufacturing techniques.

The experiments showed that it is possible to successfully design a socket using a computer based socket model. Variability of results, however indicates the existence of shortcomings. These were identified as inadequacies in the caliper method used to measure the stumps; inability to make the sockets total contact; lack of flexibility of the design process in the Round #1 computer CASD system. It was shown by results of the MERU fittings that an iterative procedure in the hands of an inexperienced person would lead to a degree of success comparable to that achieved by experienced persons using judgement. Also indicated was that experienced prosthetists were able to transfer their skills to the CASD system. This is indicated by the fact that they achieved 5 Class IV results with 8 sockets as compared to 2 Class IV results with 10 sockets achieved by the inexperienced operator.

Amputation Stumps↗
PubMed2003

Computer aided design of large-format prefabricated cranial plates.

The authors' objective in this project was to replace current state-of-the-art manual methods for preoperative production (i.e., prefabrication) of large-format (>100 cm2) cranioplasties with a system for computer-aided design and direct computer-aided manufacture of the implant's shape. This system uses standard 3D CT data, requires no specialized training, and produces an accurately fitting cranioplasty that can be recast in the physician's material of choice (e.g., polymethylmethacrylate [PMMA] or pre-bent titanium plating). The authors begin by locating the cranial defect margin on a skull surface image generated from a 3D head CT-scan. A right-to-left mirrored or average 3D skull surface template image is then fit to the patient's skull surface image. The area around the defect is cut out and stitched to the previously isolated defect margin. This defect-filling surface is then tapered and 3D printed. The 3D printed implant model is then recast in a biocompatible material. Manually generated cranial implants produced for five patients were compared with implants resulting from this new computer-based method. All five computer-generated implants were better fitting and more cosmetically suitable than the manually generated skull plates received by these patients. These well-fitting implants are more likely to protect the brain from trauma and infection. Therefore, the authors conclude that their new production method provides a better result with less expense than current methods for preoperative or intraoperative fabrication of large-format cranioplasties.

Adult↗
PubMed1993

The polar phase response property of monopolar ECG voltages using a Computer-Aided Design and Drafting (CAD)-based data acquisition system.

The present paper discusses a Computer-Aided Design and Drafting (CAD) based data acquisition and polar phase response study of the ECG. The scalar ECG does not show vector properties although such properties are embedded in it. In the present paper the polar phase response property of monopolar chest lead (V1 to V6) ECG voltages has been studied. A software tool has been used to evaluate the relative phase response of ECG voltages. The data acquisition of monopolar ECG records of chest leads V1 to V6 from the chart recorder has been done with the help of the AutoCAD application package. The spin harmonic constituents of ECG voltages are evaluated at each harmonic plane and the polar phase responses are studied at each plane. Some interesting results have been observed in some typical cases which are discussed in the paper.

Algorithms↗
PubMed2006

[Computer aided design for fixed partial denture framework based on reverse engineering technology].

OBJECTIVE: To explore a computer aided design (CAD) route for the framework of domestic fixed partial denture (FPD) and confirm the suitable method of 3-D CAD. METHODS: The working area of a dentition model was scanned with a 3-D mechanical scanner. Using the reverse engineering (RE) software, margin and border curves were extracted and several reference curves were created to ensure the dimension and location of pontic framework that was taken from the standard database. The shoulder parts of the retainers were created after axial surfaces constructed. The connecting areas, axial line and curving surface of the framework connector were finally created. RESULTS: The framework of a three-unit FPD was designed with RE technology, which showed smooth surfaces and continuous contours. CONCLUSIONS: The design route is practical. The result of this study is significant in theory and practice, which will provide a reference for establishing the computer aided design/computer aided manufacture (CAD/CAM) system of domestic FPD.

Computer-Aided Design↗
PubMed1998

Computer-assisted design and manufacture of posterior full crowns.

OBJECTIVE: To build an experimental system for the computer-assisted design (CAD) of full crowns and to obtain data for computer-assisted manufacturing (CAM) of full crowns. MATERIALS AND METHODS: Three steps are involved in building the system: measuring the prepared tooth, the adjacent mesial and distal teeth, and the opposing teeth by means of digital speckle correlation; reconstructing the shape of the measured teeth; and developing CAD for full crowns. The standard shape of the corresponding tooth was modified to fit the defective tooth on the basis of buccolingual and occlusal-gingival distance as well as the occlusal relationship of the defective tooth. RESULTS: CAD for full crowns was developed and was obtained for CAM of posterior full crowns. CONCLUSIONS: The CAD method for full crowns is convenient and economical and can be used for anterior and posterior crown design, copying, and veneer.

Bicuspid↗
PubMed1990

Right ventricular function and three-dimensional modeling using computer-aided design.

Right ventricular (RV) volumetric and morphological analysis is complicated by the trabeculations and geometric configuration of the RV chamber. To improve RV analysis, custom computer-aided design programs were employed to obtain RV volumes and three-dimensional models from biplane ventriculograms. Biplane RV ventriculograms were analyzed from 14 anesthetized dogs and 22 RV casts. Computed volumes were highly correlated with reference RV volumes (r = 0.98, n = 36, P less than 0.01) with a range of 5-73 ml. Three-dimensional wire-frame and solid models constructed from the ventriculographic images provided excellent detail and a new perspective in chamber shape. This modeling technique was then used to examine RV volumes, geometric conformation, and regional shortening in 10 pigs during inotropic stimulation and preload reduction. Changes in RV volumes, ejection fraction, and regional motion were detected as well as alterations in chamber conformation. In summary 1) computer-aided design offers an accurate and simplified means to compute RV volumes using basic microcomputer equipment, and 2) three-dimensional reconstruction provided a unique view of RV geometry and a means to examine regional RV function.

Animals↗
PubMed2006

[Application of functionally generated path technique in computer-aided-design modeling of occlusal surface of full crown].

OBJECTIVE: To apply the functionally generated path (FGP) technique for modeling the occlusal surface of a computer-aided-design (CAD) posterior full crown to obtain anatomic morphology. METHODS: A patient with defected left mandibular first molar was employed. After tooth preparation and impression making, the gypsum working cast and die were scanned with a digitized mechanical scanner and the surface data was acquired. The interocclusal records at intercuspal position (ICP) and FGP were made in the patient's mouth. These records were placed on the working cast and their surfaces were scanned. In the process of the computer-aided designing full crown, the cusps and fossae of the occlusal surfaces were accurately modified according to the digitized information of ICP and FGP interocclusal records. RESULTS: A full crown was designed and the occlusal morphology of the restoration was adapted to dynamic occlusion as well as static occlusion. CONCLUSIONS: The FGP technique was practical for the CAD of full crown and could avoid potential occlusal interferences with opposing teeth during function.

Adult↗
PubMed2000

Computer-aided design and experimental investigation of a hydrodynamic device: the microwire electrode

The development and application of a new electrochemical device using a computer-aided design strategy is reported. This novel design is based on the flow of electrolyte solution past a microwire electrode situated centrally within a large duct. In the design stage, finite element simulations were employed to evaluate feasible working geometries and mass transport rates. The computer-optimized designs were then exploited to construct experimental devices. Steady-state voltammetric measurements were performed for a reversible one-electron-transfer reaction to establish the experimental relationship between electrolysis current and solution velocity. The experimental results are compared to those predicted numerically, and good agreement is found. The numerical studies are also used to establish an empirical relationship between the mass transport limited current and the volume flow rate, providing a simple and quantitative alternative for workers who would prefer to exploit this device without the need to develop the numerical aspects.

Journal Article↗
PubMedDate not supplied

Optical data acquisition for computer-assisted design of facial prostheses.

PURPOSE: The conventional impression technique for manufacturing facial prostheses has the disadvantage of deforming the soft tissues because of the tension caused by the impression material, as well as causing discomfort to the patient. The purpose of this study was to establish a system that allows contact-free reproduction of the facial surface combined with computer-assisted design and fabrication of facial prostheses. MATERIALS AND METHODS: Three-dimensional data of the facial surface were obtained using an optical acquisition system based on the method of phase-measuring profilometry. A sensor head with a fringe projector and two CCD cameras for photogrammetric triangulation were used in connection with a PC for measurement control and data evaluation. Software for computer-assisted design of the facial surface to be reconstructed was developed. A prototype facial prosthesis was fabricated using stereolithography. The system was tested using a modified puppet head. First clinical tests were performed with a patient who had undergone maxillofacial surgery including the resection of one eye. RESULTS: Three-dimensional data acquisition and imaging allow visualization of a whole face without causing tension or neuromuscular reaction. As surface brightness is also part of the digital model, it is even more realistic than a plaster cast. The stereolithographic object showed good marginal fit and satisfactory shape. CONCLUSION: The presented technique allows three-dimensional data reproduction of the facial surface, computer-assisted design of a facial prosthesis, and transfer to a rapid prototyping unit. The system has obvious advantages over conventional impression techniques. Further clinical trials are planned to evaluate the clinical success of the technique.

Computer-Aided Design↗
PubMed1996

Computer-aided design optimization with the use of a fast dose model for linear-accelerator-based stereotactic radiosurgery.

In order to efficiently plan non-spherical radiosurgical targets we have used computer-aided design optimization techniques with a fast dose model. A study of the spatial dose distribution for single or multiple non-coplanar arcs was carried out using a 18 cm diameter spherical head model. The dose distribution generated from the 3D dose computation algorithm can be represented by a simple analytic form. Two analytic dose models were developed to represent the dose for preset multiple non-coplanar arcs or a single arc: spherical and cylindrical. The spherical and cylindrical dose models compute dose quickly for each isocentre and single arc. Our approach then utilizes a computer-aided design optimization (CAD) with the use of two fast approximate dose models to determine the positions of isocentres and arcs. The implementation of CAD with fast dose models was demonstrated. While the fast dose models are only approximations of the true dose distribution, it is shown that this approximate model is sufficient to optimize isocentric position, collimator size and arc positions with CAD.

Computer-Aided Design↗
PubMed2002

Femoral anatomy, computed tomography and computer-aided design of prosthetic implants.

Precise digital data of the internal femoral anatomy are necessary to develop new prosthetic implants with computer-aided design (CAD) techniques. Thirty human cadaveric femurs of central European origin were analysed by high precision computed tomography (CT) using thin slice and high resolution imaging. The CT data were image processed with thresholding to obtain a reconstruction of the cortical bone geometry. The CT threshold for cortical bone was optimized by comparison with saw cuts of macerated femurs. For each specimen a three-dimensional (3D) model of the cortical femur was calculated by the CAD system based on the processed CT data. Virtual 3D models of the 30 femurs were used to adjust a hypothetical stem to the proximal femur anatomy by repeated virtual implantations. The CAD system allowed for evaluation of anatomical parameters after hip reconstruction, amount of bone removal, and cortical bone contact. The fit and fill of the stem could be tested before clinical application and implant-related problems could be corrected.

Aged↗
PubMed1999

Effects of computer mouse design and task on carpal tunnel pressure.

Computer mouse use has become an integral part of office work in the past decade. Intensive mouse use has been associated with increased risk of upper extremity musculoskeletal disorders, including carpal tunnel syndrome. Sustained, elevated fluid pressure in the carpal tunnel may play a role in the pathophysiology of carpal tunnel syndrome. Carpal tunnel pressure was measured in 14 healthy individuals while they performed tasks using three different computer mice. Participants performed a multidirectional dragging ('drag and drop') task starting with the hand resting (static posture) on the mouse. With one mouse, an additional pointing ('point-and-click') task was performed. All mice were associated with similar wrist extension postures (p = 0.41) and carpal tunnel pressures (p = 0.48). Pressures were significantly greater during dragging and pointing tasks than when resting the hand (static posture) on the mouse (p = 0.003). The mean pressures during the dragging tasks were 28.8-33.1 mmHg, approximately 12 mmHg greater than the static postures. Pressures during the dragging task were higher than the pointing task (33.1 versus 28.0 mmHg), although the difference was borderline non-significant (p = 0.06). In many participants the carpal tunnel pressures measured during mouse use were greater than pressures known to alter nerve function and structure, indicating that jobs with long periods of intensive mouse use may be at an increased risk of median mononeuropathy. A recommendation is made to minimize wrist extension, minimize prolonged dragging tasks and frequently perform other tasks with the mousing hand.

Adult↗
PubMed2002

Microsurgical tissue transfer and individual computer-aided designed and manufactured prefabricated titanium implants for complex craniofacial reconstruction.

From 1994 to 2000 187 individual computer-aided designed and manufactured (CAD/CAM) prefabricated titanium skull implants were inserted at 37 clinical centres. Since the processing chain of construction and fabrication of implants has become routine the clinical success totally depends on the condition of the soft tissues at the recipient site. In three patients in our own department with a history of up to 18 surgical interventions, and additional previous irradiation in one case, these conditions were so bad that a microsurgical tissue transfer had to be made before insertion of the implant. A latissimus dorsi free flap with submandibular microsurgical anastomosis had to be used in all three cases. However, the aetiology of the soft tissue deficits differed, and they were at a different tissue level in each case: anterior skull base, subcutaneous temporal area, and frontoparietotemporal skin. This series of patients therefore demonstrates the variability of possible combinations, which also require special timetables and principles of construction of the CAD of the implant. In all cases the cranioplasties were done three to five months after the transfer of the flaps and fulfilled the criteria of greatest precision and the best possible aesthetic outcome with minimal stress for the patients. These applications are surgical strategies for extreme cases but also illustrate the elaborate interdisciplinary approach in Computer Assisted Surgery.

Adult↗
PubMed2006

Computer-based design of novel protein structures.

Over the past 10 years there has been tremendous success in the area of computational protein design. Protein design software has been used to stabilize proteins, solubilize membrane proteins, design intermolecular interactions, and design new protein structures. A key motivation for these studies is that they test our understanding of protein energetics and structure. De novo design of novel structures is a particularly rigorous test because the protein backbone must be designed in addition to the amino acid side chains. A priori it is not guaranteed that the target backbone is even designable. To address this issue, researchers have developed a variety of methods for generating protein-like scaffolds and for optimizing the protein backbone in conjunction with the amino acid sequence. These protocols have been used to design proteins from scratch and to explore sequence space for naturally occurring protein folds.

Algorithms↗
PubMed2003

A large scale test of computational protein design: folding and stability of nine completely redesigned globular proteins.

A previously developed computer program for protein design, RosettaDesign, was used to predict low free energy sequences for nine naturally occurring protein backbones. RosettaDesign had no knowledge of the naturally occurring sequences and on average 65% of the residues in the designed sequences differ from wild-type. Synthetic genes for ten completely redesigned proteins were generated, and the proteins were expressed, purified, and then characterized using circular dichroism, chemical and temperature denaturation and NMR experiments. Although high-resolution structures have not yet been determined, eight of these proteins appear to be folded and their circular dichroism spectra are similar to those of their wild-type counterparts. Six of the proteins have stabilities equal to or up to 7kcal/mol greater than their wild-type counterparts, and four of the proteins have NMR spectra consistent with a well-packed, rigid structure. These encouraging results indicate that the computational protein design methods can, with significant reliability, identify amino acid sequences compatible with a target protein backbone.

Amino Acid Sequence↗
PubMed1999

A 3D computer-aided design system applied to diagnosis and treatment planning in orthodontics and orthognathic surgery.

The purpose of this article is to describe a newly developed 3D computer-aided design (CAD) system for the diagnostic set-up of casts in orthodontic diagnosis and treatment planning, and its preliminary clinical applications. The system comprises a measuring unit which obtains 3D information from the dental model using laser scanning, and a personal computer to generate the 3D graphics. When measuring the 3D shape of the model, to minimize blind sectors, the model is scanned from two different directions with the slit-ray laser beam by rotating the mounting angle of the model on the measuring device. For computed simulation of tooth movement, the representative planes, defined by the anatomical reference points, are formed for each individual tooth and are arranged along a guideline descriptive of the individual arch form. Subsequently, the 3D shape is imparted to each of the teeth arranged on the representative plane to form an arrangement of the 3D profile. When necessary, orthognathic surgery can be simulated by moving the mandibular dental arch three-dimensionally to establish the optimum occlusal relationship. Compared with hand-made set-up models, the computed diagnostic cast has advantages such as high-speed processing and quantitative evaluation on the amount of 3D movement of the individual tooth relative to the craniofacial plane. Trial clinical applications demonstrated that the use of this system facilitated the otherwise complicated and time-consuming mock surgery for treatment planning in orthognathic surgery.

Algorithms↗