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 4,420 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This paper describes a carving machine which is the most recently developed module in the suite of CAD/CAM equipment for high technology manufacture and supply of prostheses. It provides the link between the Computer Aided Socket Design (CASD) system and the Rapidform socket manufacturing process. Using the coordinate data produced by the CASD system this machine, under computer guidance, carves from a large block of suitable material a three dimensional object; the equivalent of the rectified plaster model produced by conventional techniques. This provides the form for the fabrication of a socket and the facility completes an integrated system for fabricating, rapidly and cheaply, high quality lightweight prostheses for patients.
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PMID:Prosthetic shape replication using a computer controlled carving technique. 400 Sep 7

Recent advances in the evaluation of the amputation stump, the materials that are available for prosthetic application, techniques of improving socket fit, and prosthetic finishings promise to dramatically improve amputee function. Precision casting techniques for providing optimal fit of the amputation stump using materials such as alginate are described. The advantages of transparent check sockets for fitting the complicated amputation stump are described. Advances in research that promise to provide more functional prosthetic feet and faster and more reliable socket molding are the use of CAD-CAM (computer aided design-computer aided manufacturing) and the use of gait analysis techniques to aid in the alignment of the prosthesis after socket fitting. Finishing techniques to provide a more natural appearing prosthesis are described. These advances will gradually spread to the entire prosthetic profession.
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PMID:Advanced prosthetic techniques for below knee amputations. 409 74

During the next decade CAD/CAM technique will probably become routine in prosthetics and orthotics, not only as a complement to manual techniques, but also introducing new possibilities. However, even complex and sophisticated techniques have errors of measurement that must be considered. Such errors are of two principal kinds: systematic errors and random errors. In this study we have evaluated the Swedish CAPOD system with respect to volumetric determinations. We used two types of reference objects for volume determinations: cylinders and amputation residual limb models. Three different sizes were examined of each type of object. Volume measurements with CAPOD were compared with volumes obtained by water immersion or mathematical calculation (cylinders only). We found a constant, linear systematic error of +2.5%. Such an error can easily be corrected for. The random error, represented by the coefficient of variation, was 0.5%, which means that there is a theoretical possibility to detect volume changes exceeding 1%. We consider the precision sufficient for clinical practice in prosthetics and orthotics. Biological variations due to soft tissue deformation must be added on top of these errors. Such deformations were not evaluated in this study.
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PMID:Volumetric determinations with CAD/CAM in prosthetics and orthotics: errors of measurement. 756 54

Passive fit of the implant prosthesis onto osseointegrated and functional fixtures intraorally is the "Holy Grail" of the discerning implant prosthodontist. There is growing recognition that the old and "tried" clinical procedures and laboratory fabrication methods transferred from traditional fixed and removable partial denture prosthodontics, fall short of achieving true passivity of fit. The stages of impression making, master cast, resin verification jig, waxing, investing, casting, veneer addition and finishing can all add to the final distortion of the prosthesis. Studies are emerging that report the possible distortion associated with each stage. Alternative strategies have also been suggested to by-pass these traditional stages, for example laser welding or the elimination of the impression using optical digitising and CAD-CAM. In the final analysis, totally "passive" fit is probably unachievable. The challenge is to determine a minimum level of distortion and associated stress that is acceptable and that confers adequate clinical longevity to the prosthesis. Developing clinical tests that measure stress levels intraorally as the prosthesis is fitted would be the ideal gold standard by which to judge the accuracy of fabrication procedures. This paper summarises and rationalises the growing body of literature dealing with accuracy of implant prosthodontic procedures.
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PMID:The clinical significance of distortion in implant prosthodontics: is there such a thing as passive fit? 760 83

Reconstruction of craniofacial bone defects by intraoperative modelling of autogenous or alloplastic materials may cause undesirable results concerning the implant shape or the long-term maintenance of this shape. Furthermore, the use of alloplastic materials to be modelled intraoperatively may result in an inflammatory tissue response. Therefore the question is raised whether CAD/CAM-techniques may be used for the pre-operative geometric modelling of the implant based on helical computed tomography data. A numerically based 3-dimensional model of the skull defect serves as the basis for a freeform-surfaces design of the implant shape, position and thickness, using modelling tools and programmes developed for industrial CAD/CAM. The precise and individual fit of the implant results from generating its margins by the borders of the defect, whereas the implant surface is generated by the geometry of the non-affected neighbouring bone contours. The implant data run a numerically controlled milling machine to fabricate the individual implant. The reconstruction of post-traumatic defects of the forehead, of post-surgical temporal defects after intracranial haemorrhage, and of a parieto-occipital defect due to ablative tumour surgery are presented as the first clinical experiences of this new method.
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PMID:Reconstruction of craniofacial bone defects with individual alloplastic implants based on CAD/CAM-manipulated CT-data. 767 45

Cranioplasties using intraoperatively modeled prostheses may fail to create harmonic contours with long-term stability. In contrast, preoperative modeling would allow more sophisticated planning of the contour and better preparation of the implant material, if a sufficiently precise model of the defect-site was available. In this respect, computer aided design and manufacturing (CAD/CAM)-techniques based on helical computed tomography (CT) data are successfully used for the prefabrication of prostheses: An individual computer-based 3-dimensional model of the bony defect is generated after acquisition, transfer and evaluation of the CT data; from this freeform surfaces geometry an individual and "idealized" prosthesis-geometry is derived and fabricated by a numerically controlled milling machine using modern industrial CAD/CAM-systems and design software. The margins of this prosthesis-geometry are generated by the borders of the defect and the surface by considering the non-affected neighbouring contours. Cranioplasties in cases of large postsurgical skull defects are presented as the first clinical applications of this new method, which also allows the use of titanium and fabrication of integrated fixation-devices.
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PMID:Prefabricated prostheses for the reconstruction of skull defects. 778 44

This paper outlines the principles and uses of electric discharge machining (EDM) in the fabrication of prostheses. The three areas of use of EDM are classified as supplementary use, direct fabrication of crowns and bridges and fabrication of titanium copings using a CAD/CAM process. The problems associated with the use of EDM in each area are discussed and the methods employed to overcome these problems are described. The application of numerically controlled (NC) EDM to prosthodontic work is found to be promising. Further refinement and development are necessary before EDM can be widely accepted as a means of fabricating prostheses.
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PMID:Development of fabrication system of prostheses using electric discharge machining. 792 99

The principles, method, and benefits of combining three-dimensional computed tomography (CT) and computer-aided design/computer-aided manufacture (CAD/CAM) technology for development of custom-designed prostheses are applied in the repair of posttraumatic and congenital facial contour deficiencies. Each prosthesis is generated to fit the bone defect exactly, with external contours adjusted to compensate for overlying soft-tissue disparities. Three representative case reports from a series of 17 demonstrate the applications and advantages of using this technique. Some patients had residual defects after primary repair of posttraumatic deformities. Others had defects after orthognathic relapses for congenital deformities. Without a relatively minor surgery and a high degree of predictability, many of these patients would not have pursued further treatment. All but one of the surgeries were performed on an outpatient basis, providing an accurate, simple, and cost-effective method of contour restoration with limited morbidity and reduced operative time.
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PMID:Reconstruction of posttraumatic and congenital facial deformities with three-dimensional computer-assisted custom-designed implants. 797 22

A CAD (computer aided design) analysis software package (CADVIEW) was designed for use with prosthetic and orthotic CAD CAM (computer aided design/computer aided manufacture) systems. Using the Microsoft Windows 3.1 environment, CADVIEW provides a series of anatomical shape viewing and analysis tools. These tools include simultaneous display of multiple sockets and multiple views, two dimensional (2D) and three dimensional (3D) measurement, shape statistics, multi-shape alignment, cross-sectional comparison, colour coded 3D comparison, resolution enhancement, and image copying capabilities. This programme should be of benefit to clinicians and researchers who wish to assess and/or compare CAD data generated by MS-DOS based CAD CAM systems.
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PMID:A CAD analysis programme for prosthetics and orthotics. 799 60

The ability to provide patients with esthetic tooth-colored posterior restorations produced from "factory-standardized" ceramics in a single visit is a unique feature of CAD/CAM technology. Recent improvements in the hardware and computer software of the Siemens CEREC CAD/CAM System have improved its ease of use and the quality of the restoration produced. Attention to tooth preparation requirements and care in the cementing and finishing procedures remain requirements for the production of these restorations.
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PMID:Tooth-colored posterior restorations using Cerec Method (CAD/CAM)-generated ceramic inlays. 799 33


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