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    6 steps to a great crown

    A technical overview of CAD/CAM procedures, featuring 3M Lava Esthetic Fluorescent Full-Contour Zirconia.

    The goal of this article is to provide a general overview of the basic processes involved in producing a 3M™ Lava™ Esthetic Fluorescent Full-Contour Zirconia crown in the dental laboratory. The differences in production processes compared to a conventional (non-preshaded) zirconia material will be noted, as well as the many benefits our lab has realized in using this new zirconia.

    Scanning

    The first step in any digital workflow is creating digital versions of the patient’s dentition. There are two major ways to achieve this: First, receive a digital impression scan which the doctor has taken in the clinic. Second, receive a traditional impression from the clinic and scan it with a laboratory scanner.

    Completed crownA completed crownThe first option, if done properly, should result in an accurate digital model of the patient’s teeth straight from the chair. With the second option, a traditional stone

    model will still need to be poured from the impression, which is then scanned using the lab scanner — we use the Identica T500 from Medit. Either option can be a viable way to digitize the dentition, depending on the individual laboratory’s production levels and applications.

    Designing

    Once a digital model is available, it can be imported to a dental design software for the design process. It is important to be cognizant of the varying limitations of not only the material in use but also the individual milling machine that will mill the case. Time spent on remakes and adjustments can be greatly saved through a knowledgeable design process, making this one of the most important processes in the digital workflow.

    Nesting

    After designing procedures are finished, the 3D data of the restoration is transferred to a CAM software for nesting and calculation. A CAM software reads the data of the restoration file and creates directions for the milling machine to follow according to the preset settings and milling strategy.

    Related article: How to place an anterior implant using a digital workflow

    Nesting is a process in which the technician places the restorations within the zirconia disc, or puck, taking into account the varying limitations of a milling process (such as undercuts). Proper nesting is absolutely crucial in ensuring that the resulting restoration is of a desirable outcome.

    For zirconia materials with a built-in shade gradient, such as Lava Esthetic zirconia, it should be noted that in order for the shade gradient of the disc to be properly utilized, all restorations should be nested vertically. Once nesting and sprue placement are finished, the milling is then calculated by the CAM software and the milling process begins.

    Paul Kim, President, DentCore
    Paul Kim is the President of DentCore, a company specializing in supplying dental CAD/CAM products and equipment, including 3M™ Lava™ ...

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