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Digital impressions

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Digital impression technology and systems

Publié dans : Santé

Digital impressions

  3. 3. INTRODUCTION  Today,digitaltechnologycontrolsalmostevery aspectofourlife, anddentistryis noexceptiontoit.  Millions ofimpressions aretakenevery yearforthe productionofcrowns,bridges, andpartialdentures.  Making impressionswith elastomericimpression materialis aneverydayprocedurein almostevery general dentalpractice.  A new wayto dispensetraysandimpression materialsis nowavailablethatcreatedigital impressionsofa patient’steeth.  The digitalimpression conceptis emerging rapidlyonthe horizonanditis believed thatdigital impressions willsolvethe challenges anddifficultiesoftheconventionalimpressions.
  4. 4. Back-ground of Current Impression Materials  The historyoftoday’straditionalimpressionmaterialsbegan in the mid-1930’swiththe introductionof reversible hydrocolloids.  This wasthefirstmaterialthatmade theimpression ofundercuts possible.  Bythe1955,polysulphideswereintroducedandforthe firsttime anelastomericimpressionmaterialwasused.  Therewasagreat improvementin reproducingthe characteristicsofpreparedteeth,butstill therewereinherent problemslike shrinkageofmaterial.
  5. 5.  In 1966, further improvements in impression materials occurredwith the introduction of polyether. This material proved tobefar superior to the hydrocolloid followed by silicones in 1976.  Though they are hydrophobic by nature buteven in the presence of a moist environment, they are highly dimensional stable resulting in a superior elastic recovery.  With the advancement of time and technology improvements are made to these materials to reduce tearing, chair time and enhance the patient comfort.
  6. 6. DISADVANTAGES OF CURRENT IMPRESSION TECHNIQUES  Errors in tray selection.  Limitations inthe impression material’s flow and hydrophilicity.  Short workingtime.  Patient movement .  Tearingand deformation of the impression duringremoval.  Dimensional stability of the set impression.  Required disinfection.  Inadequate wetting and voids when pouringthe cast.  Messy materials.  Tedious and time taking.  Tongueand saliva.  Discomfort to patient.
  7. 7. Evolution of Digital Impressions  Dr.Duretfirstintroducedthe CAD/CAMconcepttodentistryin 1973in Lyon,Francein his thesis entitledEmpreinteOptique,whichtranslatestoOpticalImpression.  The conceptofCAD/CAM systemswasfurtherdeveloped byDr.Mormann,aSwiss Dentist,andMr. Brandestini,whowas anelectricalengineer.  Thefirstcommerciallyavailabledigitalimpression systemforusein thefield ofdentistrywas introducedin 1980pioneered byPROCERAandCEREC.  Over thelast10years,systemslike 3M LavaC.O.S., CadentiTero, E4DDentist,and3ShapeTrioshave been introduced.  Todate,variousCAD/CAM systemsare nowavailablefordentalapplications.Eachemploysaspecific, distincttechnique formaking impressions.
  8. 8. Intraoral scannersare usedto create a digital imageof the patient’s teeth Theneed for traditional impression materials eliminated. Using either a laser orvideo, animageis acquired witha digital scanning device. Patient’s dentition and bite relationship optically recorded. Lightis projected from the tipof the scanner,anda cameracollects data, Manipulation done to produce a digital model of the patient’s dentition
  9. 9. PRE-REQUISITE OF DIGITAL IMAGING  Digital camera.
  10. 10. Software to create image using CAD/CAM system. & Connection to export the image
  11. 11. Milling unit to fabricate the prosthesis (in house or in lab).
  12. 12. DIGITAL IMPRESSION TECHNIQUES  In-Office CAD/CAM Impression Techniques  CEREC (Sirona)  E4D Technologies  Chairside Digital Impression Techniques  iTero  CEREC  Lava C.O.S.systems.
  13. 13. CEREC In-office fabrication Sendingthe digitalimages directly tothe laboratory. CEREC AC gives dentists the choice of implementing
  14. 14. Thescanner operates using visible blue light emanating from light emitting diodes (LEDs) with shorter wavelengths of light than previous CEREC models, increasing the accuracy ofthe scan. LIGHT USED
  15. 15. IMAGE ACQUISITION Image acquisition is more rapid with CEREC AC than with previous models due to the continuous capturing of a series of images by the scanner oncein position.
  16. 16. Theocclusion is recordedby simply scanning the arches, and digital on-screenarticulating papershows where there arecontacts. Images of interdigitation of the opposing teeth also show if there is sufficient interocclusal clearancefor the prosthesis. RECORDING OCCLUSION
  17. 17. MILLING After the clinician has verified the digital preparation the CEREC MC XL milling center can beused to createfull contour crowns in six minutes. Alternatively, the MC L Compact Milling Unit can beused.
  18. 18. E4D TECHNOLOGIES TheE4D can beused for all fixed prosthesis except bridges and implants. TheE4D has separate scanning and milling units within a cart, with automated interunit communication.
  19. 19. TheE4D (D4D TECHNOLOGIES) takes several images using a red light laser to reflect off of the tooth structure, oscillating at 20,000 cycles per second to capture the series of images and createa 3-D model. LIGHT USED
  20. 20. IMAGE ACQUISITION Thescanner is held at a specific distance above the tooth, aided by rubber stops on the scannerhead, and the area is centered forimaging (aided by a bull’s-eye on-screenguide).
  21. 21. Theocclusion and occlusal height ofmilled restorations areassessed from the preparation’s arch and an image of a physical registration bitehence there is no requirement toscan the opposing arch. RECORDING OCCLUSION
  22. 22. MILLING Themilling component includes a touch-screenpanel that provides guidance during the process. The digital scan is transferred to the milling machine(with wireless orwired transmission), and the restoration is milled from both sides simultaneously.
  23. 23. iTero TheiTero chairside digital impression scanner utilizes parallel confocal imaging to capture a 3D digital impression of the tooth surface, contours and gingival structure. Thescanner has the ability to capture preparations for crowns, bridges.
  24. 24. LIGHT USED TheParallel confocal imaging uses laser and optical scanning to digitally capture thesurface and contours of the tooth and gum structure. The Cadent iTero scannercaptures 100,000 points of red laser light and has perfect focus images of more than 300 focal depths of the tooth structure. All of these focal depthimages arespaced approximately 50 μmapart. This system does not require the use of powder.
  25. 25. IMAGE ACQUISITION During scanning, a series of visual and verbal prompts are giventhat are customized for the patient beingtreated and guide the clinician through the scanning process. Foreach preparation, a facial, lingual, mesio-proximal and disto-proximal viewis recordedin around 15 to 20 seconds, after which the adjacentteeth are scanned from the facial and lingual aspect.
  26. 26. RECORDING OCCLUSION Theocclusion is captured by taking two interocclusal views with the patient in centric, after which the dentist can viewthe image within 30 seconds and ascertain that the interocclusal clearance is sufficient for the planned prosthesis prior to the patient leaving. No bite registration material is required.
  27. 27. MILLING Themilling of the models is done on a 5-axis milling machine,using a proprietary resin material. Simultaneously, the dental laboratory technician can export the digital impression file to his orher CAD/CAM system and begin fabrication of copings and/or prosthesis.
  28. 28. Lava C.O.S. systems TheLava C.O.S.system is used for chairside digital impression making.
  29. 29. LIGHT USED TheLava C.O.S.scanner contains 192 LEDs and 22 lens systems with a pulsating blue light and uses continuous video to capture the data that appears onthe computer touch screenduring scanning. Almost 2,400 data sets are captured per arch.
  30. 30. IMAGE ACQUISITION After scanning the tooth preparation, the dentist is able to rotate and magnify the view on the screenand can also switch from the 3-D image to a 2-D view. The full arch is scanned after the preparation imaging is complete, followed by the opposing quadrant.
  31. 31. RECORDING OCCLUSION Theocclusion is assessed by scanning from the buccal aspect with the teeth in occlusion and viewing the arches digitally. Theimages aretransmitted directly to laboratory where the laboratory technician digitally marks the margins and sections the virtual model priortosending this digitally to the manufacturer.
  32. 32. MILLING Themodel is virtually ditched, articulated and sentto the model fabrication center for stereolithography (SLA) to create acrylic models.
  33. 33. Differentiation between various camera available CEREC E4D iTero LAVACOS Full-archdigital impressionsindicated YES NO YES YES PowderingRequired YES NO NO Some AcquisitionTechnology Blue light LED Redlight LASER Confocal Bluelight LED video In-OfficeMilling YES YES NO NO ConnectivitytoLabs YES NO YES YES RestorationDesign (CAD) Software YES YES NO NO Indicationforbridges YES NO YES YES
  34. 34. HOW IT IS DONE?
  35. 35. A dentist holds a scanning wand which is connectedto a digital camera
  36. 36. This uses blue wavelength light to record images of the teeth to make a 3D computer model.
  37. 37. A 3D model created by the scanning wand is displayed on a computer screen.
  38. 38. Blocks of dental ceramic material that will be used to createdental restorations.
  39. 39. A milling machinelocated inside the dental office carves a restoration from a block of ceramicmaterial.
  40. 40. A computermodel showing howthe final restorations will look is sent tothe milling machine for fabrication.
  41. 41. Thefinal prosthesis, placed the same day.
  42. 42. Processing steps in the dental practice Conventional impressions Prepare the impression tray Make silicone impression Transfer impression Disinfect Complete orderform Dental laboratory steps Clean Trim impression Pour stone material Trim arch Pin Trim base Perform saw-cut Ditching Fabrication of prosthesis Finished model Apply Optispray Acquire digital impression Complete order form Data transfer Connect portal Dental laboratory steps Confirm receipt of data Check accuracy ofdata in 3D Finished model Digital Impressions
  43. 43. BENEFITS OF DIGITAL IMPRESSION  Accuracy of impressions  Opportunity to view, adjust and rescan impressions  No physical impression for patient  Savestime and one visit for in-office systems  Opportunity to viewocclusion  Accurate restorations created on digital models  Potential for cost-sharing of machines
  44. 44.  Accurate, wear- and chip-resistant physical CAD/CAM derived models  No layering/baking errors  No casting/soldering errors  Cross-infection control  Patient is comfortable
  45. 45. DISADVANTAGES OF DIGITAL IMPRESSIONS  Digital equipment is very expensive.  Digital equipment’s are complex and trained operator is required to operate and maintain the device.  Good and up-to- date laboratory support is required.  Those with small mouths may have difficulty with this procedure.
  46. 46. CONCLUSION With the numerous advantages of digital impressions over traditional impressions and the ability to benefit from digital impression taking and/or CAD/CAM, more and more dentists are purchasing digital impression systems. It will likely be a routine procedure in most dental offices in the near future, as dentists, laboratory technicians, and patients all reap the benefits.
  47. 47. REFERENCES  iData Research Inc., 2007, U.S. Market for Dental Prosthetic Devices.  Beuer F, Schweiger J, Edelhoff D. Digital dentistry: an overview of recent developments for CAD/CAM generated restorations. Br Dent J. 2008;204(9):505-11.  Nathan S. Birnbaum; Heidi B. Aaronson;Chris Stevens; Bob Cohen. 3D Digital Scanners: A High-Tech Approach to More Accurate Dental Impressions; Inside Dentistry; April 2009; 5, (4).  Puri S. Maximizing and simplifying CAD/CAM dentistry; www.ineedce.com
  48. 48.  Svend Carlsen. Witnessing the evolution of digital impression solutions; Dental Tribune U.S. Edition | May 2012  Sabiha S. Bunek, DDS; Chris Brown, BSEE. The Evolving Impressions of Digital Dentistry ; Inside Dentistry; January 2014  Sankalp Sharma,1 Swatantra Agarwal,2 Divya Sharma,3 Sanjeev Kumar,4 Nishtha Glodha. IMPRESSION; DIGITAL VS CONVENTIONAL: A REVIEW ; Annals of Dental Specialty Vol. 2; Issue 1. Jan – Mar 2014