Cad cam in prosthodontics

detailed description of CAD-CAM in prosthodontics

1. CAD-CAM PRESENTED BY – DR. ANIKET SHINDE I ST YEAR PG STUDENT DEPARTMENT OF PROSTHODONTICS

2. CONTENTS Introduction History Components of CAD/CAM Subtractive and Additive techniques Materials for CAD/CAM Common CAD/CAM systems Recent advances Summary References

3. Introduction With the conventional impression procedures and procedures like lost-wax-casting technique in the production of metal castings or frameworks, their accuracy is greatly influenced by the properties of the impression materials, investment and casting Also traditional procedures are time consuming, efforts have been made to replace these techniques with computer-assisted procedures.

4. To produce milled restorations with accurate fit, digitization of the prepared tooth surface and converting the data into control signals for computer-assisted milling is used. Computer-aided design/computer-aided manufacturing (CAD/CAM) technology which was developed in the late 1980s for dentistry, incorporates the above mentioned techniques and it significantly reduced and/or eliminated problems associated with dental castings.

5. History In dentistry, the major developments of dental CAD/CAM systems occurred in the 1980s. Dr. Duret – developer of Sopha System Dr. Moermann - the developer of the CEREC system Dr. Andersson - the developer of the Procera system

6. Dr. Duret fabricated crowns (1971) with the functional shape of the occlusal surface using a series of systems that started with an optical impression of the abutment tooth in the mouth, followed by designing an optimal crown considering functional movement, and milling a crown using a numerically controlled milling machine.

7. Dr. Moermann , the developer of the CEREC system. He directly measured the prepared cavity with an intra-oral camera, which was followed by the design and carving of an inlay from a ceramic block using a compact machine set at chair-side.

8. Dr.Andersson , the developer of the Procera system Fabricated titanium copings by spark erosion and introduced CAD/CAM technology into the process of composite veneered restorations. Later developed as a system with processing centre networked with satellite digitizers around the world for the fabrication of all-ceramic frameworks.

9. CAD/CAM components can be grouped into CAD-CAM COMPONENTS

10. 1. It includes the data collection tools that measure three dimensional jaw and tooth structures and transform them into digital data sets. Basically there are two different scanning possibilities: 1) optical scanners 2) mechanical scanners. SCANNERS

11. It involves the collection of 3D structures in a so-called ‘triangulation procedure’. The source of light and the receptor unit are in a definite angle in their relationship to one another. White light projections or a laser beam can serve as a source of illumination Examples of optical scanners : Lava Scan ST (3M ESPE, white light projections) es1 ( etkon , laser beam). OPTICAL SCANNERS

12. The master cast is read mechanically line-by-line by means of a ruby ball and the three-dimensional structure measured. The Procera Scanner from Nobel Biocare This type of scanner is distinguished by a high scanning accuracy, whereby the diameter of the ruby ball is set to the smallest grinder in the milling system MECHANICAL SCANNERS

13. With such softwares , crown and fixed partial dentures (FPD) frameworks can be constructed. Some systems also offer the opportunity to design full anatomical crowns, partial crowns, inlays, inlay retained FPDs, and telescopic primary crowns. The software available on the market is being continuously improved. DESIGN SOFTWARE

14. The data of the construction can be stored in various data formats. The basis therefore is often standard transformation language (STL) data. Many manufacturers, however, use their own data formats, specific to that particular manufacturer.

15. The construction data produced with the CAD software are converted into milling strips for the CAM-processing and finally loaded into the milling device. Processing devices are distinguished by means of the number of milling axes: 3-axis devices 4-axis devices 5-axis devices. PROCESSING DEVICES

16. This type of milling device has degrees of movement in the three spatial directions, and so the mill path points are uniquely defined by the X -,Y-, and Z – values A milling of subsections, axis divergences and convergences, however, is not possible This demands a virtual blocking in such areas The advantages of these milling devices are short milling times and simplified control by means of the three axis and they less costly Examples of 3-axis devises: inLab (Sirona), Lava (3M ESPE), Cercon brain ( DeguDent ). 3-AXIS DEVICES

17. In addition to the three spatial axes, the tension bridge for the component can also be turned infinitely variably . As a result it is possible to adjust bridge constructions with a large vertical height displacement into the usual mould dimensions and thus save material and milling time. Example: Zeno (Wieland- Imes ). 4-AXIS DEVICES

18. In addition to the three spatial dimensions and the rotatable tension bridge (4th axis), the 5-axis milling device has the possibility of rotating the milling spindle (5th axis) This enables the milling of complex geometries with complex shapes such as denture base resins. Example in the Laboratory Area: Everest Engine Example in the Production Centre: HSC Milling Device 5-AXIS DEVICES

19. Dry processing : Applied mainly with respect to zirconium oxide blanks with a low degree of pre-sintering. Advavtages : Minimal investment costs for the milling device No moisture absorption by the die ZrO2 mould Disadvantages: Higher shrinkage values for the frameworks. EXAMPLES : [Zeno 4030 (Wieland- Imes ), Lava Form and Cercon brain]. MILLING VARI ANTS

20. In this process the milling diamond or carbide cutter is protected by a spray of cool liquid against overheating of the milled material. Useful for all metals and glass ceramic material in order to avoid damage through heat development. ‘ Wet’processing is recommended, if zirconium oxide ceramic with a higher degree of pre-sintering is employed for the milling process. Examples: Everest ( KaVo ), Zeno 8060 (Wieland- Imes ), inLab (Sirona). WET PROCESSING

21. It is another manufacturing approach to build objects, one layer at a time and adding multiple layers to form an object. It is also known as additive manufacturing or rapid prototyping (RP). It may be used for the fabrication of metal structures either indirectly by printing in burnout resins or waxes for a lost-wax process, or directly in metals or metal alloys like FPD and removable partial denture (RPD), polymerized prostheses, and silicon prosthesis. 3D PRINTING

22. A scanning laser fuses a fine material powder, to build up structures layer by layer, as a powder bed drops down incrementally, and a new fine layer of material is evenly spread over the surface. Resolution as high as 60 μm may be obtained, and the structures printed are supported by the surrounding powder SELECTIVE LASER SINTERING

23. Light-sensitive polymer cured layer by layer by a scanning laser in a vat of liquid polymer. It is a widely employed RP technology. It was invented by Charles Hull . It is an additive manufacturing process in which a liquid photocurable resin acrylate material is used. Stereolithography uses a highly focused Ultraviolet (UV) laser to trace out successive cross-sections of a 3D object in a vat of liquid photosensitive polymer It may be used for the fabrication of metal structures either indirectly by printing in burnout resins or waxes for a lost-wax process, or directly in metals or metal alloys like FPD and removable partial denture (RPD), polymerized prostheses, and silicon prosthesis STEREOLITHOGRAPHY

24. Currently, subtractive milling is the most widely implemented computer-aided manufacturing protocol in dentistry and it has been shown to be a suitable method for fabricating intraoral prostheses. Additive methods have the advantage of producing large objects, with surface irregularities, undercuts, voids, and hollow morphology that makes them suitable for manufacturing facial prostheses and metal removable partial denture frameworks MODEL MANUFACTURING

25. Materials for processing by CAD/CAM devices depends on the respective production system Some milling devices are specifically designed for the production ZrO2 frames, while others cover the complete palette of materials from resins to glass ceramics and high performance ceramics. The materials normally processed by CAD/CAM systems include: 1) Metals 2) Resin materials 3) Silica based ceramics 4) Infiltrated ceramics 5) Oxide ceramics MATERIALS FOR CAD-CAM PROCESSING

26. CAD/CAM systems may be categorized as: In-office system Laboratory based system Milling center system COMMON COMMERICAL CAD-CAM SYSTEMS

27. IN OFFICE SYSTEMS : Sirona, with their CEREC line of products, is the only manufacturer that currently provides both in-office and laboratory-based systems. CEREC 1 and CEREC 2 – optical scan of the prepared tooth with a charged-coupled device (CCD) camera, and the system automatically generates a 3D digital image on the monitor Then, the restoration is designed and milled With the newer CEREC 3D, the operator can record multiple images within seconds. This enables the clinicians to prepare multiple teeth in the same quadrant and create a virtual cast for the entire quadrant. On the virtual model, the operator designs the contour of the restoration and electronically transmits the data to a remote milling unit for fabrication. Better marginal adaptation 1.CEREC

28. LABORATORY BASED SYSTEMS : It is a laboratory-based system Working dies are laser-scanned and a digital image of the virtual model is displayed on a computer screen. After designing the coping or framework, the laboratory technician inserts the appropriate ceramic block into the CEREC inLab machine for milling. A wide range of high strength ceramic blocks are available for the inLab system It includes Vita In-Ceram blocs two sintered ceramics: inCoris ZI (zirconium oxide) and inCoris AL ( aluminium oxide) (Sirona Dental Systems, LLC). After milling, the technician manually inspects and verifies the fit of the milled coping or framework on the die and working cast. CEREC inLab

29. Subsequently, the coping will be adjusted to maximize adaptation to the die. The coping or framework then is either glass-in filtrated (Vita In-Ceram) or sintered (zirconium oxide or aluminium oxide), and the veneering porcelain is added

30. MILLING CENTRE SYSTEMS The system is comprised of a Preciscan laser scanner and Precimill CAM multitool milling center. It can scan 14 dies simultaneously and mill up to 30 framework units in a single, fully automated operation. It can mill titanium as well as fully dense sintered zirconia. DSC PRESIDENT

31. Procera / AllCeram was introduced in 1994 Uses an innovative concept for generating alumina and zirconia copings. The master die is scanned and the data is send to the processing center. After processing,the coping is send back to the lab for porcelain veneering. The recommended preparation marginal design for a Procera / AllCeram restoration is a deep chamfer or shoulder with a rounded internal line angle and a well-defined cavosurface finish line. The recommended coping thickness is 0.4 mm to 0.6 mm. PROCERA

32. Nobel Biocare USA LLC has introduced various implant abutments for its Procera system— titanium (1998) alumina (2002) zirconia (2003) Capable of generating alumina (two to four units) and zirconia (up to 14 units) bridge copings. The occlusal-cervical height of the abutment should be at least 3 mm, and the pontic space should be less than 11 mm.

33. NEWER CONCEPTS Wax pattern (coping) with a minimum thickness of 0.4 mm are to be made which is scanned and the Cercon Brain milling unit milled a zirconia coping from proprietary presintered zirconia blanks. The coping then was sintered in the Cercon Heat furnace (1350 C) for 6 to 8 hrs. Allow-fusing, leucite-free Cercon Ceram S veneering porcelain was used to provide the esthetic contour. CERCON

34. In 2005, DENTSPLY Ceramco introduced the Cercon Eye 3D laser optical scanner and Cercon Art CAD design software. Now, as a complete CAD/CAM system, Cercon can produce single units and bridges up to nine units from pre-sintered zirconia milling blocks that are offered in white and ivory shades without any infiltration required

35. Lava system Introduced in 2002. It includes a mobile cart, a touch screen display and a scanner with camera at the end. Camera has LEDs and lens systems Data-send through wireless to the laboratory where the die is cut and margins are marked digitally. LAVA

36. The system offers two possibilities: Scanning for in-office fabrication Sending digital images to the laboratory Transfer is only possible if the laboratory has CEREC CONNECT Light source: LED (blue visible light) The occlusion is recorded by simply scanning the arches, and digital on-screen articulating paper shows where there are contacts. CEREC

37. Image acquisition is more rapid with CERECAC The clinician can verify the preparation and interocclusal clearance The system will also digitally mark the margins and provide a digital version of the proposed restoration prior to its fabrication

38. The Lava C.O.S. system is used for chairside digital impression making Scanner contains 192 LEDs and 22 lens systems with a pulsating blue light It uses continuous video to capture the data that appears on the computer touch screen during scanning 2,400 data sets are captured per arch. Can rotate and magnify the view on the screen Full arch is scanned after the preparation imaging is complete, followed by the opposing quadrant, and the occlusion is assessed Images can be transmitted directly to an authorized laboratory LAVA C.O.S.

39. Laboratory technician digitally marks the margins and sections the virtual model prior to sending this digitally to the manufacturer The model is then virtually ditched, articulated and sent to the model fabrication center for stereolithography (SLA) to create acrylic models

40. Case report

41. summary Newer CAD/CAM systems demonstrate increasing user friendliness, expanded capabilities, improved quality, and greater range in complexity and application. Chairside digital impressions systems allow for the creation of accurate and precise laboratory models and restorations involving less chairside time. Fractures of ceramic FPDs tended to occur in the connector areas because of the concentrated stress. Therefore, the design of the connector, particularly the dimensions, must be made independently depending on the type of ceramic material used for the framework. CAD better guarantees the durability and reduces the risk of fracture. Processing data can be saved and followed up during the functional period for the device.

42. references Anusavice , Shen, Rawls; Phillip’s Science of Dental Materials 2013, 12th edition, Elsevier. NS Birbaum , HB Aoronson ; Dental impressions using 3D digital scanners: Virtual becomes reality; Compendium 2008, 29(8): 494-505. T Miyasaki , Y Hotta , J Kuni et al; a REVIEW OF DENTAL cad/cam: Current status and future perspectives from 20 years of experience; Dent Mater 2009, 28(1): 44-56.

43. AD Bona, AD Noguiera , OE Pecho ; Optical properties of CAD/CAM ceramic sysems ; J Dent 2014, 42: 1202-09 GD Quin, AA Guiseppetti , KH Hoffman; Chipping fracture resistance of dental CAD/CAM restorative materials; Dent Mater 2014, 30(5): e112-e123 Z Zhang, Y Tamaki, Y Hotta , T Miyasaki ; Novel method for titanium crown casting using a combination of wax patterns fabricated by a CAD/CAM system and a non expanded investment; Dent Mater 2006, 22: 681-87.

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