CAD/CAM - international magazine of digital dentistry

I 33 feature _ interview I CAD/CAM 3_2013 a hybrid: milling and casting where desirable but with additive manufacturing as a top alternative. “Addonversustakeaway,”Iliketocallit.Insummary, the casting process, from the cast object to the fin- ished product, is usually very time-consuming and can lead to distortion, especially with large-span restorations. With additive technology, we achieve contour accuracy more easily than with milling. Our workplaces in dental technology are also cleaner thanks to CAD/CAM: less dust, bonding agent, glue, and outgassing. Ultimately, the deciding factor is quality.Comparedwithcastingandmilling,additive printing processes are creating entirely new ways of thinking in terms of production, workflow and the products themselves. _Howarethesechangesexpressed? We need to look at different levels here. First is the transition from manual craftsmanship to high- precision, high-accuracy industrial CAD/CAM pro- duction. Milled non-precious metal restorations have significant disadvantages owing to material consumption:highproductioncostsandsystem-re- latedlowerqualityintermsoffitandshaperetention. During casting, we also encounter disadvantages in terms of low material density, mould costs, produc- tion time and rework. Nearly all of these disadvan- tages disappear with laser melting. By using proven materials like remanium star CL and rematitan CL from Dentaurum with our Mlab cusing R, we have been very satisfied with the quality of our system- manufactured products. In the case of large-volume restorations, any excess tension that arises can be alleviated through subsequent heat treatment, thus avoidinganypotentialdistortion.Ofcourse,thesame applies to cobalt–chromium alloys or titanium. _You mentioned changes to the products. What changeswereyoureferringto? I’mquiteoptimistic.I’lldescribeacoupleofthem. First, the geometric flexibility of prostheses is en- abling a new way of looking at shapes or functions. In the future, imagine restorations with channels into which medications can be fed. The dentist or orthodontistcanprovidetreatment,andthepatient will not have to deal with temporaries. The second major change is the selective density of a compo- nent made possible by the process. Thus, for exam- ple,notonlycanbridgeswithmorethantensections bemanufacturedinaone-stepprocesstension-free, but they can also be increasingly applied in heavily utilised areas, such as cantilevers, edges or brace elastics. In model casting, that is not always an easy problem to solve. Geometric freedom is a genuine plus for us, as it opens up new possibilities for re- storationdesign.Forexample,braceelementscanbe mademuchfinerwhileretainingsufficientmechan- ical properties. These new options also increase the longevityofdentalproducts.Incastingormilling,we have to deal with cost, material waste and lower materialdensity;incastingespecially,wehaveover- sizeddimensionsandmuchlowermaterialdensities. With cast restorations, breakage is always an issue. But it does not have to be that way. Another benefit istheabilitytocreatecombinationsthroughmodule or multicomponent construction methods. Base el- ements implanted into the jawbone are used as pri- mary structures. An additively manufactured foun- dation element is then put into place as a secondary structure, on to which a secure, durable veneer such as HeraCeram is applied. Another aspect relates to newmaterials,suchasnon-preciousmetaltitanium. _Titaniumishardandbiocompatible. Titaniumistheidealmaterialforallergysufferers, for example. In combination with laser melting and veneering, we can maximise its biological benefits. Fromavisualstandpoint,titaniumrestorationsoffer a risk-free silver-grey lustre. Manufacturers of non- precious metal alloys have spread pseudoscientific criticism regarding the aesthetics of titanium. Low- dose fluoride in toothpaste or mouthwash, for ex- ample, has no impact on appearance. We cannot denytherealitythattitaniumhasnotonlycaughtup with non-precious metal alloys in importance, but also surpassed them. This is precisely why, in 2012, UniciminvestedinanMlabcusingRsystemfortita- niumapplicationsfromConceptLaser,whichallows us to process reactive titanium material in a closed Fig. 2_Non-precious titanium alloys: Mlab cusing R from Concept Laser at Unicim. Fig. 2