Please activate JavaScript!
Please install Adobe Flash Player, click here for download
ePaper created 2015-05-11, 15:34:22 | version 1.33.01
7Lab Tribune Italian Edition - Maggio 2015 Tendenze << pagina 6 The dental laboratory of the future will be more of a hybrid: milling and casting where desirable but with ad- ditive manufacturing as a top alter- native. “Add on versus take away,” I like to call it. In summary, the cast- ing process, from the cast object to the finished product, is usually very time-consuming and can lead to dis- tortion, especially with large-span res- torations. With additive technology, we achieve contour accuracy more easily than with milling. Our work- places in dental technology are also cleaner thanks to CAD/CAM: less dust, bonding agent, glue, and outgassing. Ultimately, the deciding factor is qual- ity. Compared with casting and mill- ing, additive printing processes are creating entirely new ways of thinking in terms of production, workflow and the products themselves. How are these changes expressed? We need to look at different levels here. First is the transition from man- ual craftsmanship to high-precision, high-accuracy industrial CAD/CAM production. Milled non-precious metal restorations have significant disadvantages owing to material con- sumption: high production costs and system-related lower quality in terms of fit and shape retention. During casting, we also encounter disadvan- tages in terms of low material density, mould costs, production time and re- work. Nearly all of these disadvantag- es disappear with laser melting. By us- ing proven materials like remanium star CL and rematitan CL from Den- taurum with our Mlab cusing R, we have been very satisfied with the qual- ity of our system-manufactured prod- ucts. In the case of large-volume resto- rations, any excess tension that arises can be alleviated through subsequent heat treatment, thus avoiding any po- tential distortion. Of course, the same applies to cobalt–chromium alloys or titanium. You mentioned changes to the products. What changes were you referring to? I’m quite optimistic. I’ll describe a couple of them. First, the geometric flexibility of prostheses is enabling a new way of looking at shapes or functions. In the future, imagine res- torations with channels into which medications can be fed. The dentist or orthodontist can provide treat- ment, and the patient will not have to deal with temporaries. The second major change is the selective density of a component made possible by the process. Thus, for example, not only can bridges with more than ten sec- tions be manufactured in a one-step process tension-free, but they can also be increasingly applied in heav- ily utilised areas, such as cantilevers, edges or brace elastics. In model cast- ing, that is not always an easy prob- lem to solve. Geometric freedom is a genuine plus for us, as it opens up new possibil- ities for restoration design. For ex- ample, brace elements can be made much finer while retaining sufficient mechanical properties. These new options also increase the longevity of dental products. In casting or mil ling, we have to deal with cost, ma- terial waste and lower material den- sity; in casting especially, we have oversized dimensions and much lower material den sities. With cast restorations, breakage is always an issue. But it does not have to be that way. Another benefit is the ability to create combinations through mod- ule or multicomponent construction methods. Base elements implanted into the jawbone are used as primary structures. An additively manufac- tured foundation element is then put into place as a secondary structure, on to which a secure, durable veneer such as HeraCeram is ap- plied. Another aspect relates to new mate- rials, such as non-pre- cious metal titanium. Titanium is hard and biocompatible. Titanium is the ideal material for allergy sufferers, for example. In combination with laser melting and ve- neering, we can max- imise its biological benefits. From a visual standpoint, titanium restorations offer a risk-free silver-grey lustre. Manufacturers of non-precious met- al alloys have spread pseudoscientific criticism regarding the aesthetics of titanium. Low-dose fluoride in toothpaste or mouthwash, for example, has no impact on ap- pearance. We cannot deny the reality that titanium has not only caught up with non-precious metal alloys in importance, but also surpassed them. This is precisely why, in 2012, Unicim invested in an Mlab cusing R system for titanium applications from Concept Laser, which allows us to process reactive titanium materi- al in a closed system. The unit can be used with dental materials certified under the German Medical Devices Act, such as rematitan CL from Den- taurum. Because of the high amount of material waste, milling-based pro- cessing of titanium is too expensive and casting is highly impractical. What are some of the problems that arise in the casting of titanium? The reaction of titanium with oxy- gen causes the formation of an al- pha-case layer on the outside. This leads to embrittlement of the surface and must be removed. If not removed, it can lead to problems with the adhesion of veneering. With LaserCUSING, no alpha-case lay- er forms. This makes laser melting with titanium powder excellent for processing. The very fine-grained microstructure of the laser-fused parts of this titanium alloy allows greater firmness than with conven- tional castings. The dentist receives a high-performance, long-life alter- native that is easy to work on and more affordable than a precious metal solution. Finally, dentists and patients can benefit from a quality product that is both durable and nat- ural in appearance. How does titanium compare in terms of price? The price of the Dentaurum titanium powder we use is currently around €595 per kilogram; a four-unit bridge weighing 4 g thus costs €2.40 in ma- terial alone. Why has laser melting been so slow to catch on in the dental industry? The reasons for this are many. The process is relatively new, so the learn- ing curve is long. The fact that the quality of laser-fused products is better than conventionally manu- factured dental restorations remains largely unknown. Its reputation con- tinues to be tarnished by ignorance or misconceptions. Keep in mind, too, that dental technician training takes four years in Switzerland, and theoretical instruction is slow to in- corporate new technologies. In ad- dition, Swiss dental laboratories are very small. The Association of Swiss Dental Technicians estimates that there are some 1,200 centres, many of which operate with just one or two people. Therefore, investments in la- ser melting are carefully considered. Unicim, as a digital production cen- tre, acts as a service provider to other laboratories. Right now, I see it as an outsourcing area while we wait for it to take hold in the market. What is the position of dentists regarding this issue? Interest is undoubtedly growing, not least because it is impossible to ig- nore the technical, timesaving and affordability benefits. But we also need to look at the process chain. In order to prepare the data for manu- facturing, it must be in STL format. STL data from different scanners can be processed using the CAM- bridge or AutoFab Mlab data-pro- cessing software available from Concept Laser. Nowadays, conventional dental im- pressions form the basis for CAD data. The accuracy of the data de- pends on the preciseness of the work performed the dentist. Higher accuracy is essential. A high-qual- ity intra-oral scanner costs about CHF20,000. If we had complete data migration from the dentist to the dental laboratory, we would be one step further. In the long term, how- ever, that is unavoidable. Quality as- surance and documentation needs will make open, manufacturer-in- dependent data transfer an increas- ingly critical requirement. Especially in terms of affordability, the topic of laser melting is becoming more im- portant. All images courtesy of Concept Laser GmbH, Lichtenfels, Germany. This article was published in CAD/CAM international magazine of digital dentistry No. 3/2013. Tailor-made dental technologies: Master Dental Technician Dieter Spitzer offers traditional manu- facturing along with CAD/CAM methods, such as laser melting of metals for dental restorations. Non-precious titanium alloys: Mlab cusing R from Concept Laser at Unicim. Crowns and bridges manufactured using laser melting technology. Cast parts manufactured with LaserCUSING.