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cone beam – international magazine of cone beam dentistry

case report _ full-arch restoration I A few days later, we received the framework for try-in. It had a perfect passive fit and was returned to the laboratory for veneering. The metal preparation in thelaboratoryentailedsandblasting,titaniumetching andtheapplicationofopaqueporcelaintoconcealthe metal core. The bisque-baked restoration was then tried in to allow the patient to validate the aesthetics oftherestoration.Thisstepisnecessarytoassessstatic and dynamic occlusion and perform minor adjust- ments(Figs.13a–g).Thebisque-bakedrestorationwas then returned to the laboratory for fine tuning and glazing. _CAD/CAM benefits Although conventional casting techniques have evolved, they are still fraught with inaccuracies owing to the nature of the materials and to their handling. This includes the risk of errors during investment pro- cessing, risk of metal deformation and poor metal homogeneity. The CAD/CAM technologies used for producing metal frameworks are essential to the quality of the final restoration (Fig. 13i). The CT scan dataisconvertedintoaformatthatallowsthe3-Dim- ages to be utilised by the selected treatment planning software.Thecaseisthenplannedinthesoftware. The CAD software has databases that allow the creation of virtual models for the desired restoration using different materials, including zirconia, titanium, cobalt–chromium,IPSe-maxandPMMA. If the dental laboratory has its own scanner, an STL file is sent directly to the production centre by e-mail. Otherwise, both the model and the wax-up are for- wardedtotheproductioncentrebycourier. If the computer settings are correct, one is ensured ofperfectreproducibilityinthemanufacturingprocess andconsistencyintheresult(i.e.atrulypassiveframe- work fit). Optimal setting of the coping thickness parameter or the pontic connection parameter may preventtorsionordeformationoftheframeworkdur- ing firing of the ceramic. Subtractive manufacturing, combinedwithdigitalmodelling,eliminatestheriskof alterationofthematerialstructure.Theresultingmetal frameworkwillhaveoptimalhomogeneityanddensity. As regards fabrication of implant superstructures, machiningisthetechniqueofchoiceforachievinghigh precisionandnearpassivefit.Practitionerscanexpect consistent and reproducible results, excellent frame- workfit,andregular,accurateprostheticseals. _Conclusion Today, dental laboratories are using high-tech scanning equipment, which allows digitisation of the master model (to determine the implant index) and the wax-up. CAD/CAM offers a level of quality and ac- curacy unsurpassed by any of the traditional tech- niques. Passive fit, which is critical to the outcome of an implant-supported prosthesis, is a determinant of the long-term success of a restoration. Passive fit of the framework for a long-span restoration is much easier to achieve and reproduce with CAD/CAM than withthetraditionalpouringtechniques. The use of CAD/CAM machining for implant- supported restorations guarantees a highly accurate andpredictableframeworkfit(<10µ).Inaddition,ma- chining centres can produce restorations using fully biocompatiblematerials,suchastitaniumandzirconia. InordertotakeadvantageoftheaccuracyofCAD/CAM, using safe and reliable implant systems with superior biological and biomechanical characteristics is re- quired. CAD/CAMwillsoonbeessential.CurrentCAD/CAM solutions are easily accessible to any dentist and do not require fundamental changes to his or her work habits._ Acknowledgement: Special thanks to G. Nauzes and J.Bellany,laboratorytechniciansatSocalab. Editorial note: This article was published in CAD/CAM inter- nationalmagazineofdigitaldentistryNo3/2014. Fig. 13i_Overview of Simeda process stages. I 25cone beam1_2015 Fig. 13i Dr Richard Marcelat has a DDS degree in Oral Implantology from the University of Liège and in Basal Implantology from the University of Nice SophiaAntipolis,as well as a Postgraduate Certificate in Implantology from CURAIO in Lyon in France. He can be contacted at richard.marcelat@orange.fr. cone beam_author

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