Avaliação da adaptação marginal de diferentes tipos de restaurações obtidas por CAD/CAM e métodos convencionais

The past few decades have brought many changes to the dental practice and the technology has become ready available. The result of a satisfactory rehabilitation treatment basically depends on the balance between biological and mechanical factors. The marginal adaptation of crowns and prosthetic structures is vital factor for long-term success. The development of CAD / CAM technology in the manufacture of dental prostheses revolutionized dentistry, this technology is capable of generating a virtual model from the direct digital scanning from the mouth, casts or impressions. It allows the planning and design of the structure in a computered software. The virtual projects are obtained with high precision and a significant reduction in clinical and laboratory time. Thus, the present study (Chapters 1, 2 and 3) computed microtomography was used to evaluate, different materials, different CAD/CAM systems, different ways of obtaining virtual model (with direct or indirect scanning), and in addition, also aims to evaluate the influence of cementing agent in the final adaptation of crowns and copings obtained by CAD / CAM. Furthermore, this study (Chapter 4, 5 and 6) also aims to evaluate significant differences in vertical and horizontal misfits in abutment-free frameworks on external hexagon implants (HE) using full castable UCLAs, castable UCLAs with cobalt-chromium pre-machined bases and obtained by CAD / CAM with CoCr or Zirconia by different scanning and milling systems. For this, the scanning electron microscopy and interferometry were used. It was concluded that the CAD / CAM technology is capable to produce restorations, copings and screw-retained implant-supported frameworks in different materials and systems offering satisfactory results of marginal accuracy, with significative reduction in clinical and laboratory time.

CAD Files and European Design Law

Three-dimensional printing (“3DP”) is an additive manufacturing technology that starts with a virtual 3D model of the object to be printed, the so-called Computer-Aided-Design (“CAD”) file. This file, when sent to the printer, gives instructions to the device on how to build the object layer-by-layer. This paper explores whether design protection is available under the current European regulatory framework for designs that are computer-created by means of CAD software, and, if so, under what circumstances. The key point is whether the appearance of a product, embedded in a CAD file, could be regarded as a protectable element under existing legislation. To this end, it begins with an inquiry into the concepts of “design” and “product”, set forth in Article 3 of the Community Design Regulation No. 6/2002 (“CDR”). Then, it considers the EUIPO’s practice of accepting 3D digital representations of designs. The enquiry goes on to illustrate the implications that the making of a CAD file available online might have. It suggests that the act of uploading a CAD file onto a 3D printing platform may be tantamount to a disclosure for the purposes of triggering unregistered design protection, and for appraising the state of the prior art. It also argues that, when measuring the individual character requirement, the notion of “informed user” and “the designer’s degree of freedom” may need to be reconsidered in the future. The following part touches on the exceptions to design protection, with a special focus on the repairs clause set forth in Article 110 CDR. The concluding part explores different measures that may be implemented to prohibit the unauthorised creation and sharing of CAD files embedding design-protected products.

An approximate method for the solution of an influence function foil rolling model

Fleck and Johnson (Int. J. Mech. Sci. 29 (1987) 507) and Fleck et al. (Proc. Inst. Mech. Eng. 206 (1992) 119) have developed foil rolling models which allow for large deformations in the roll profile, including the possibility that the rolls flatten completely. However, these models require computationally expensive iterative solution techniques. A new approach to the approximate solution of the Fleck et al. (1992) Influence Function Model has been developed using both analytic and approximation techniques. The numerical difficulties arising from solving an integral equation in the flattened region have been reduced by applying an Inverse Hilbert Transform to get an analytic expression for the pressure. The method described in this paper is applicable to cases where there is or there is not a flat region.