38749406 Cad Cam Dentistry


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A PEER-REVIEWED PUBLICATION Continuing Education © Reprinted from DENTAL PRODUCTS REPORT, November 2005 Printed in U.S.A. Simplifying CAD/ CAM Dentistry Chairside CAD/CAM designing and milling are not as complex as they may seem Authors Dr. Alex Touchstone Dr. Alex Touchstone practices general dentistry with an emphasis on esthetics in Hattiesburg, MS. He is an advanced CEREC® trainer, on the Academy of Computerized Dentistry board of directors, and a member of the IADR and AACD. Dr. Touchston
  Simplifying CAD/CAM Dentistry Chairside CAD/CAM designing and millingare not as complex as they may seem  Advanstar Dental Media is an ADA CERPRecognized Provider SPONSORED BY SIRONA DENTAL SYSTEMS LLC Dr. Alex Touchstone Dr. Alex Touchstone practicesgeneral dentistry with anemphasis on esthetics inHattiesburg,MS. He is anadvanced CEREC ® trainer,on the Academy of ComputerizedDentistry board of directors,anda member of the IADR and AACD. Dr. Touchstone is aninternational speaker and dentalmanufacturer consultant. Authors ®  I  MA  GE  S  C  O UR T E  S Y  OF  S I  R  ONA D E NT A L  S Y  S T E M S L .L . C . Continuing Education  A PEER-REVIEWED PUBLICATION A SUPPLEMENT TO Dr. Randy J. Phillips Dr. Phillips is AssistantProfessor of Clinical Dentistry,a Clinical Group PracticeDirector,and the CourseDirector for the CEREC ® Externship program at theUniversity of SouthernCalifornia School of Dentistry.He was in private practice for26 years and is a Fellow ofboth the International and the American Colleges of Dentists. © Reprinted from DENTAL PRODUCTS REPORT, November 2005Printed in U.S.A.  Dental Products Report (Supplement 1) ❚ November 2005 2 O ne ofthe earliest memories I have offam-ily vacations are those ofa camping tripwe made around my fifth birthday.Weloaded up the station wagon,complete with theobligatory pop-up camper in tow,and set offto aKOA campground to “rough it”for an entire week.The image ofmy Dad fighting with that camper inthe Mississippi heat is one ofmy favorite childhoodrecollections to this day.At daybreak on the secondmorning,Dad took me to the pond for my first-everfishing experience.We caught so many catfish thatday that I naturally fantasized that the key to fish-ing was simply to pick a spot,put the hook in thewater,and pull ’em in as fast as you could.Fishing,it turns out,has as many varied techniquesas fish,each with its own unique tackle and recipefor success.Folks who fish will tell you that each typeis both fun and rewarding.Moreover,the numberoffish one catches is directly proportional to thetime spent with the hook in the water.So it is with chairside computer-aided design/com-puter-aided manufacture (CAD/CAM) dentistry.The science ofCAD/CAM dentistry has expandedrapidly in the last few years.The types ofrestorationspossible using such systems are almost as varied asthe dentists who embrace the technology.The levelofesthetic and functional potential ofCEREC®(Sirona Dental Systems LLC) restorations is limitedonly by one’s imagination and drive to learn. 1,2 Becauseit is currently the only chairside CAD/CAM systemavailable,this article focuses exclusively on the CERECsystem.This chairside CAD/CAM system isapproaching 20 years ofclinical experience and has aproven track record on all relevant aspects ofclinicalperformance,including fit, 3-5 longevity 6-10 and survivalrates,sensitivity, 11 strength, 12-14 and wear. 15 While each CEREC application in and ofitself is simple and straightforward to learn,much like myearly fishing experiences,sometimes CAD/CAMlooks more complex because ofthe many differentoptions it offers.In order to reap the rewardspromised though,one must keep the “hook in thewater”with regard to gaining experience and under-standing ofthe workflow associated with creating each type ofrestoration possible.It is a good idea tofocus one’s learning on a single type ofrestorationand become proficient in that first,before adding new applications to one’s portfolio.The purpose ofthis article is to give the reader aclear understanding ofthe thought processes thatsurround making a decision about which methodto employ when fabricating CAD/CAM restora-tions with the CEREC system,and to illustrate thesimplicity ofthe basic elements ofthose decisions.Two cases illustrate achieving restorative goals withchairside CAD/CAM technology.The first The fast track toCEREC ® excellence Becoming proficient with one mode at a time helpstake the mystery out of CAD/CAM dentistry The use of CAD/CAM technology in dentistry is increasing, bothin the dental laboratory and general practice settings, to fabricateall-ceramic inlays, onlays, crowns, and veneers. Only oneCAD/CAM system is currently available for in-office chairside use,CEREC ® 3D by Sirona Dental Systems. There exists amisconception that the CAD/CAM process is complicated andtime-consuming. However, this CAD/CAM system is simple tooperate, versatile, and precise. All-ceramic restorations can bedesigned and milled chairside, traditional impressions andtemporaries are eliminated, and the patient leaves the appointmentin about an hour with a final restoration in place. Dental CAD/CAMis approaching 20 years of clinical experience and has a proventrack record on all relevant aspects of clinical performance, includingfit, longevity and survival rates, sensitivity, strength, and wear. Thisarticle illustrates the simplicity of the basic skills necessary toachieving restorative goals with chairside CAD/CAM technology.      A     B     S     T     R     A     C     T By Dr. Alex Touchstone This CE program issponsored by an unrestrictededucational grant fromSirona Dental Systems.  Dental Products Report (Supplement 1) ❚ November 2005 3 addresses the precise control ofthe fit and estheticoutcome possible when fabricating veneers withCEREC. 16,17 The second demonstrates that even den-tal students with limited experience can grasp thesimple concepts necessary to design and mill poste-rior restorations with CAD/CAM technology. CASE ONE:Lateral incisor veneers A 34-year-old patient presented with poorly matchedcomposite veneers on teeth Nos.7 and 10.The dis-crepancy was made more dramatic by recent at-home bleaching procedures (Figure 1).Additionally,both veneers were chipped—tooth No.10 to agreater degree than tooth No.7—which ultimatelyresulted in the use oftwo different design techniquesin the process offabricating each veneer (Figure 2).After discussing several restorative options,thepatient chose to have the veneers replaced withCEREC 3D custom-milled restorations.TheCEREC R2005 software includes three design tech-niques:Dental Database (with and without Antag-onist),Correlation,and Replication. 18 Deciding which one to use is influenced by the condition of the tooth before the preparation is started.Ifthetooth has a generally desirable form that the clini-cian wishes to copy,then the Correlation mode isthe technique ofchoice.If,however,one feels thatthe condition ofthe tooth is such that copying itwould result in undesirable tooth form or occlusalrelationship,then either the Replication or DentalDatabase techniques apply.Replication allows theuser to copy and mirror the contra-lateral tooth,thusmaintaining perfect symmetry in the critical ante-rior smile zone.The Dental Database method allowsone to create a new restoration by choosing fromone ofseven different databases ofteeth stored inthe software and offers the greatest freedom for alter-ing tooth morphology (Table 1).  After reading this article,the reader should be able to: DISCUSS some of the advantages to using chairside CAD/CAMtechnology. DESCRIBE the software design modes and the thoughtprocesses involved in deciding which to use for each restorativesituation. EXPLAIN the basic steps of designing veneers with theCorrelation and Dental Database modes. DISCUSS the subsequent restorative material decisionsnecessary to control the esthetic outcome. L E AR NI  N G  OB  J E  CT I  VE  S  FIG. 1: Preoperative smile. FIG. 2: Close-up of chipped veneers. FIG. 3: Tooth preparations. FIG. 4: Contrast medium applied to preparation.  4 Dental Products Report (Supplement 1) ❚ November 2005 DESIGN TECHNIQUERESTORATIVE METHODAPPLICATION Correlation Copy the tooth to berestoredMost often used,very simple Replication Copy any tooth surfaceEnsures bilateral symmetry Dental Database (with Antagonist)Start from scratchMaximum freedom to altermorphology (taking antagonistinto account when designingocclusion) There is a common misconception that anteriorrestorations,particularly veneers,are difficult,time-consuming,and unpredictable with CEREC.Thereverse is actually true.The level ofcontrol over theform ofthe veneer afforded the dentist as well as theesthetic outcome actually make CEREC veneersone ofthe more simple processes ofCAD/CAMdentistry. 18 Once the decision to create a veneer fortooth No.7 by Correlation and a veneer for toothNo.10 by Dental Database was made,the processofpreparing the teeth,fabricating and finishing theveneers,and finally seating them was accomplishedin about 2 hours.The criteria for selecting the Dental Databasetechnique for tooth No.10 were:ã Defects present in the form ofthe tooth(chipping on the incisal third).ãAbsolute symmetry not required for theserestorations (notice the subtle asymmetry of teeth Nos.8 and 9).First,it was determined that the preoperative mor-phology oftooth No.7 corresponded to the desiredoutcome.Therefore,an optical impression oftoothNo.7 was made before it was prepped,to be copiedlater in the design ofthe veneer.The chip in toothNo.10 led the author to use Dental Database todesign the restoration,rather than creating a copy;thus,a pre-operative image ofNo.10 was notrequired.Next,both teeth were prepared with a labialreduction ofapproximately 1 mm (Figure 3).The preparation for tooth No.7 was lightly pow-dered with a contrast medium,and an optical impres-sion was captured (Figure 4).The contrast mediumallows for the accurate registration ofthe exact dimen-sions ofthe preparation and surrounding structuresby the camera and thus is an essential element ofthetechnique. 19-21 The veneer then was designed using the Correlation design technique,with the pre-treat-ment form ofthe tooth copied precisely (Figures 5and 6).There actually are only four main steps to design-ing a veneer in Correlation mode,requiring a total of about 3 to 5 minutes (Table 2).As with developing       T     A     B     L     E     1 CEREC design modes FIG. 5: Defining copying area. FIG. 6: Finished veneer design for tooth No. 7. FIG. 7: Shell in position over prep. FIG. 8: Finished veneer design for tooth No. 10.
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