I digital dentistry _ NobelProcera Safety and reliability with CAD/CAM technology Authors_ Hans Geiselhöringer & Dr Stefan Holst, Germany clinical protocol. Simplicity for the dental technician primarily concerns the time required to design and manufacture a restoration. However, in order to ensure an efficient workflow, a user-friendly software interface and intuitive handling are also of utmost importance. Current scientific findings and clinical experience underscore the need for adequate material manufacture and framework design to minimise clinical failures, such as chipping of veneering ceramics or fracture of frameworks. The most important request, especially when working with zirconia substructures, is that the framework be anatomically designed and require no manual post-processing adjustment. In the past, double scans were performed in order to achieve this goal. New software design tools eliminate these time- and costintensive steps, as anatomic tooth-libraries support the user in ideal coping and framework design. Automatic cut-back functions increase ease of use and provide an additional margin of safety by ensuring homogenous veneering material thickness. An equally important aspect to consider is the design and dimension of the connector cross-section for fixed dental prostheses. Only if minimum connector dimensions are respected will long-term clinical success not be jeopardised. Newly developed software tools support the user in the virtual design of the frameworks and provide immediate feedback on the cross-sectional area, connector height and width, and coping thickness. The most eminent facts for the practitioner are that no major changes in clinical protocol are required when working with CAD/CAM technology and industrially manufactured components. Only when it comes to oxide ceramics are slight modifications of preparation design required for longterm success. These are limited to a slight chamfer margin preparation, provision of an adequate occlusal space of 1.5 to 2 mm and rounded edges (eliminating sharp transitions). The true benefit when working with materials such as zirconia or aluminium oxide is that conventional cementation protocols can be applied. Adhesive luting—a require- Fig. 1a Fig. 1b Figs. 1a & b_Application of zirconia for long-span restorations requires high manufacturing precision and excellent material quality. Only if colouring pigments are equally distributed in the framework will material properties be optimal. _Today, dental technicians and general practitioners are challenged by an ever-increasing number of CAD/CAM systems in the dental market. In order to determine which system is best suited, various aspects need to be considered. While CAD/CAM technology was initially associated with zirconia-based restorations, advanced systems offer an extensive range of materials and solutions for both natural teeth and implants. The benefits are not limited to a more cost-efficient fabrication of dental restorations in the laboratory; practitioners and patients benefit from the technological advancements equally. This article discusses the various aspects that need to be considered in the decision-making process. _Simplicity in clinical and laboratory routines A key aspect of the successful application of new technologies and clinical protocols is the time required to adapt to and utilise a system in a daily routine. This aspect is not only of relevance for the dental laboratory in manufacturing a restoration, but also to the practitioner considering changes in 40 I cosmetic dentistry 4_ 2009