This document describes a case study of a full-mouth reconstruction using digital techniques. A 46-year-old woman presented needing esthetic and restorative treatment. Her treatment plan involved veneers for the anterior teeth and single crowns for previously crowned posterior teeth. Digital impressions were taken of both arches using intraoral scanning. Working models and soft tissue casts were made from the digital data. Restorations were designed and milled from the digital files. The reconstruction involved veneers for 12 teeth and single crowns for the remaining 12 teeth, all fabricated using digital workflows.
This document describes a case study of a full-mouth reconstruction using digital techniques. A 46-year-old woman presented needing esthetic and restorative treatment. Her treatment plan involved veneers for the anterior teeth and single crowns for previously crowned posterior teeth. Digital impressions were taken of both arches using intraoral scanning. Working models and soft tissue casts were made from the digital data. Restorations were designed and milled from the digital files. The reconstruction involved veneers for 12 teeth and single crowns for the remaining 12 teeth, all fabricated using digital workflows.
This document describes a case study of a full-mouth reconstruction using digital techniques. A 46-year-old woman presented needing esthetic and restorative treatment. Her treatment plan involved veneers for the anterior teeth and single crowns for previously crowned posterior teeth. Digital impressions were taken of both arches using intraoral scanning. Working models and soft tissue casts were made from the digital data. Restorations were designed and milled from the digital files. The reconstruction involved veneers for 12 teeth and single crowns for the remaining 12 teeth, all fabricated using digital workflows.
This document describes a case study of a full-mouth reconstruction using digital techniques. A 46-year-old woman presented needing esthetic and restorative treatment. Her treatment plan involved veneers for the anterior teeth and single crowns for previously crowned posterior teeth. Digital impressions were taken of both arches using intraoral scanning. Working models and soft tissue casts were made from the digital data. Restorations were designed and milled from the digital files. The reconstruction involved veneers for 12 teeth and single crowns for the remaining 12 teeth, all fabricated using digital workflows.
PROSTHODONTICS as Western Europe and the United States. 7
Only a few years ago, euphoric statements were made that impressions and computer- generated abutments would likely replace traditional restorative protocols and become the standard for dentistry. 9 Today, this would seem to be truewith the exception of scanning large edentulous areas, digital techniques are already capable of replac- ing conventional workows. 7,911
In advertisements and dental journals, computer-based procedures are often praised as being safer and more economi- cally efcient, comfortable, and precise than their predecessors. 9,12,13 And indeed, although conventional putty impressions are considered equally precise as digital impression techniques, 11 other benets associated with computer-aided design/ computer-assisted manufacture (CAD/ CAM)generated dental restorations include access to new, nearly defect-free, industrially prefabricated and controlled materials; an increase in quality and repro- ducibility; data storage commensurate with a standardized chain of production; an improvement in precision and planning; and an increase in efciency. 7,8 As a result of continual developments in technology, new methods of production and new treat- ment concepts are to be expected. 7
Clinicians must have certain basic knowl- edge if they are to benet from these new procedures. This article describes the full- mouth reconstruction of a patient using an entirely digital workow. A combination of public media, 1 new ma ter- ials, and advanced techniques have fueled an esthetic cultural revolution 2 that has left clinicians to address the esthetic expecta- tions of todays patients. Since positive effects on a patients self-esteem and qual- ity of life were identied during this revolu- tion, 3 an emphasis on enhancing personal appearance is demonstrated in patients increasing demands for esthetic proce- dures. 2
Another important development has been the use of computers in dentistry, which has led to new research foci and new opportunities with regard to clinical work- ows and dental restoration manufactur- ing. 48 Production stages in dentistry are becoming increasingly automated, as is the case in many other industries. 7 The price of dental laboratory work has become a major factor in treatment planning and therapy, and automation could enable more com- petitive production in high-wage areas such 1 Private Practice, Munich, Germany; formerly, Assistant Professor, Department of Prosthodontics, Propedeutics, and Dental Materials, Christian-Albrechts University at Kiel, Kiel, Germany. 2 Director, Byrnes Dental Laboratory, Wheatley, Oxfordshire, United Kingdom. 3 Chair, Department of Prosthodontics, Propaedeutics, and Dental Materials, Christian-Albrechts University at Kiel, Kiel, Germany. Correspondence: Dr Christian Mehl, Volkartstrasse 5, 80634 Munich, Germany. Email: cmehl@proth.uni-kiel.de, christian. mehl@hardermehl.de Prosthodontics in digital times: A case report Christian Mehl, DDS, Dr Med Dent 1 /Soenke Harder, DDS, Dr Med Dent 1 / Ashley Byrne, Dental Technician 2 /Matthias Kern, DDS, Dr Med Dent, PhD 3 Dentistry has not been exempt from changes in this era of technology-driven revolution. Entire workows are already digitalized, and restorations are designed and manufactured using computer-aided solutions. This case report describes the reconstruction of 24 teeth using digital techniques. (Quintessence Int 2013;44:2936) Key words: CAD/CAM, case report, ceramic, crown, digital, imaging, polyurethane, scanning, veneer 30 VOLUME 44 NUMBEP 1 JANUAPY 2013 QUI NTESSENCE I NTERNATI ONAL Mehl et al Fig 2 An esthetic wax-up of the anterior teeth to determine the extent of the preparation. Fig 1 The initial situation. CASE REPORT A 46-year-old woman presented with a need for conservative and prosthodontic treatment. Esthetically, the patient was unhappy about the position and color of her teeth, as well as the large composite res tor- ation in the maxillary right central incisor. In addition, she lacked the condence to smile wholeheartedly due to the discolored mar- gins of her posterior teeth (Fig 1). Clinically, the composite restorations in the maxillary and mandibular anterior teeth were suf- cient, and the overall periodontal situation was stable. The patient decided to proceed with veneers on the maxillary and mandibu- lar anterior teeth as an elective and entirely cosmetic procedure. In the premolar and molar regions, the teeth had previously been restored with porcelain-fused-to-metal (PFM) crowns with insufcient margins. Additionally, all crowns were splinted, thereby complicating interdental oral hygiene. The posterior teeth had been con- servatively treated with clinically unaccept- able resorcinol-formaldehyde resin root oanal hllings (Pussian rod) 14,15 and had loose and leaking core buildups. The con- servative treatment plan consisted of an oral hygiene phase, the replacement of all root canal treatments, and new core build- ups. The prosthodontic phase included veneering the maxillary and mandibular right canines through left canines and plac- ing single crowns on the previously crowned posterior teeth. Clinical procedure Following a professional cleaning, an algi- nate impression (Alginat Super, Pluradent) was taken. After mounting the stone casts in an articulator, a wax-up up of the maxillary and mandibular right canines through left canines was made in the dental laboratory (Fig 2). With the help of thermoformed splints, the wax-up was tried on as a mock- up to ensure that the patient was making an informed decision with regard to electively placing veneers on otherwise intact anterior teeth. After the patient opted to proceed, the posterior crowns were removed and the root canal llings revised. The previous clin- ician had used a toxic resorcinol-formalde- nydo rosin root oanal hlling matorial (Pussian red), which led to heavy discoloration of the teeth that was, in some cases, impossible to remove and replace. 14,15 After nishing the b a VOLUME 44 NUMBEP 1 JANUAPY 2013 31 QUI NTESSENCE I NTERNATI ONAL Mehl et al Fig 3 Teeth prepared for taking impressions. Fig 4 Stylized image of digital impressions using parallel confocal imaging. root canal treatments, core buildups were adhesively placed (Clearl DC Core, Kuraray) and the teeth covered with cement- ed provisional restorations (Luxatemp, DMG). Three months after the endodontic treatment, none of the posterior teeth showed apical pathologies or caused pain, and the restorative treatment was started. After the application of a local anesthetic (Septanest, Septodont), the maxillary and mandibular teeth were prepared and digi- tally scanned on two consecutive days using triple zero retraction cords (Ultradent) (Fig 3). Prior to scanning, a small perma- nent bonding (Tetric EvoFlow, Ivoclar Vivadent) was placed on the unprepared mandibular right second molar. Also, removable interocclusal records were built on the maxillary and mandibular left second molars and on the all four central incisors as a front jig (Tetric EvoCeram, Ivoclar Vivadent) to ensure a proper transfer of the bito to tno digital data sot. Booro tno digital impression was taken, an astringent gel (Expasyl, Piorro Polland) was plaood or 1 minute. After thorough rinsing of the gel with water, the digital impressions were taken (iTero, Align Technologies) (Fig 4). At rst, the maxillary arch was digitally scanned. On the following day, a digital impression of the mandibular teeth, as well as the interocclu- sal records, were taken (Fig 5). The digital scans were performed using parallel confocal imaging, which utilizes laser and optical scanning to digitally cap- ture the surfaces and contours of teeth and gingival structures. This technique cap- tures 100,000 points of reected laser light in a focus at 300 focal depths of the tooth structure. These focal depth images are spaced approximately 50m apart. Booauso tno intorooolusal rooords nad to be taken on three different areas (right, left, and anterior teeth), two of the three records were always placed on the antago- nistic sides. After taking the digital impres- sions, the astringent gel was again placed for 1 minute and rinsed. Conventional impressions were then taken as controls (Pim-look trays, Pormadyno, 3M ESPE). Tno provisional restorations were cemented with a liner (Kerr Life, Kerr) to allow stability and at the same time, retrievability of the restor- ations. After sending the case to the labora- tory, the initial digital le (STL format) was cleaned and processed with computer soft- ware (Align Technologies). The nalized STL le was received at the dental labora- a b 32 VOLUME 44 NUMBEP 1 JANUAPY 2013 QUI NTESSENCE I NTERNATI ONAL Mehl et al Fig 5 Digital images of the scanned teeth after marking the preparation mar- gins in the dental laboratory. Fig 6 Working and soft tissue casts made of polyurethane material using the digital set of data from the scanning procedure. a b d c VOLUME 44 NUMBEP 1 JANUAPY 2013 33 QUI NTESSENCE I NTERNATI ONAL Mehl et al Fig 8 Choosing the height of the cobalt-chromium metal blank to mill the framework of the fxed dental prosthesis in one piece. Fig 7 Virtual design of the anatomically reduced framework using the digital set of data from the scanning procedure. Fig 9 Anatomically reduced milled ceramic frame- works before individualized feldspathic veneering. tory computer workstation (iTero CAD work- station, Align Technologies), and the cast was designed virtually. Additionally, the removal dies and contact points were con- gured. The occlusion and margins were checked by the laboratory before transfer- ring the digital le to a milling center (Straumann European Milling Centre). The casts were milled from a solid block of polyurethane (Fig 6). The STL scan le was exported (Fig 7) to the CAD/CAM sys- tem (CS2, Straumann). Using the CAD soft- ware, the restorations were designed and checked at the dental laboratory for porce- lain support and that they tted within the milling blook sizo (Fig 8). Postorations or the maxillary right through left rst molars and mandibular right rst molar through left canine were milled as individual anatomi- cally reduced lithium disilicate glass-ceram- ic crowns/veneers (IPS e.max CAD, Ivoclar) (Fig 9), which provided excellent clinical results. 1618 The xed dental prosthesis for the mandibular left rst premolar to second molar was milled from a solid cobalt-chro- mium alloy block (Coron, Straumann) b c a 34 VOLUME 44 NUMBEP 1 JANUAPY 2013 QUI NTESSENCE I NTERNATI ONAL Mehl et al Fig 10 Finished laboratory work on the cast produced from the digital set of data. (Fig 9). Each restoration was checked for t and passivity before being veneered with porcelain (Initial, GC) and hand-polished to achieve natural esthetics (Fig 10). The occlusion was checked and adjusted before the restorations were sent to the dental ofce. Three weeks after the impressions were taken, the ceramic crowns were tried in clinically. After cleaning the teeth with pum- ice and a chlorhexidine solution, radio- graphs were taken to check the t of the restorations. All full-coverage restorations were cemented with glass-ionomer cement (Ketac-Cem, 3M ESPE), while the veneers were bonded to the teeth using rubber dam and transparent adhesive cement (Variolink II, Ivoclar Vivadent). Figures 11 and 12 show the restorations at a recall visit 3 months after cementation. DISCUSSION Digital techniques are already capable of replacing traditional workows. 7,9,11 With the exception of scanning large edentulous areas, digital impressions showed trueness and precision equal to conventional tech- niques. 11,19 One advantage of digital impres- sions compared with the conventional techniques with putty is that missing areas or imperfections can easily be rescanned and added to the existing virtual model, thus reducing discomfort for the patient. Another major advantage of the computer technique is the availability of the data of the virtual model and the restoration, allow- ing technicians to rst check function and esthetics. 20
A useful tool in the iTero CAD worksta- tion is the measurement of the interocclusal distance immediately after the scanning procedure. 4 Clinically, this helps to ensure the correct material thickness and also make sure that there is enough space for the technician to design anatomically cor- rect occlusal surfaces. For the dental tech- nician, various benets emerge from the use of digital dentistry. The manufactured polyurethane casts have a higher resis- tance to wear when used in the dental labo- ratory and have a plasterlike color similar to conventional casts. With the exception of a total loss of the jaw relationship, there is no need to take the bite. The occlusal jaw rela- tionship is scanned directly and transferred to a standardized articulator, which signi- cantly reduces time for both the clinician and dental technician. 4 Moreover, casts can easily be replicated with the same quality since the same set of data can be reused. 4
With regard to esthetics, the use of one cast, which serves as a working and master model when soft tissue structures are still intact, reduces valuable chair time, since fewer try-ins are necessary. 4 Furthermore, digitalization of clinical and laboratory work- ows enables the industry to process homogenous, standardized materials, which reduces material-induced failures. 8,20 Notwitnstanding all tno bonohts or patients, clinicians, and dental technicians, the use of digitalization in dental proce- b a VOLUME 44 NUMBEP 1 JANUAPY 2013 35 QUI NTESSENCE I NTERNATI ONAL Mehl et al Fig 12 The fnished situation with single individu- ally veneered crowns and a fxed PFM dental pros- thesis. Fig 11 Finished work clinically with retracted lips. dures still has its limitations. Digitalization cannot be utilized when removable prosth- odontic concepts are applied, since the digital scanners are not able to stitch and merge large edentulous areas. 20
Furthermore, the computer resources and stability of the software are compromised when larger sets of data are produced. Additionally, the handling of the scanner head, which can be heavy, requires prac- tice. The greatest time and workow benet can be drawn from digital scanning sys- tems when small restorations in one or two quadrants are placed. CONCLUSION Compared with conventional techniques, digital workows benet patients, clinicians, and dental technicians alike in terms of cost and precision. Future studies are neces- sary, however, to determine whether the longevity of restorations is also positively inuenced. b a c 36 VOLUME 44 NUMBEP 1 JANUAPY 2013 QUI NTESSENCE I NTERNATI ONAL Mehl et al REFERENCES 1. Theobald AH, Wong BK, Quick AN, Thomson WM. The impact of the popular media on cosmetic den- tistry. N Z Dent J 2006;102:5863. 2. Priest G, Priest J. Promoting esthetic procedures in the prosthodontic practice. J Prosthodont 2004;13:111117. 3. Davis LG, Ashworth PD, Spriggs LS. Psychological efects of aesthetic dental treatment. J Dent 1998; 26:547554. 4. Garg AK. Cadent iTeros digital system for dental impressions: The end of trays and putty? Dent Implant Update 2008;19:14. 5. Kachalia PR, Geissberger MJ. Dentistry a la carte: In-ofce CAD/CAM technology. J Cal Dent Assoc 2010;38:323330. 6. Kachalia PR. iDentistryrecent advances within the digital restorative arena. J Cal Dent Assoc 2010;38:321322 7. Beuer F, Schweiger J, Edelhof D. Digital dentistry: An overview of recent developments for CAD/CAM generated restorations. Br Dent J 2008;204:505511. 8. Mehl A, Hickel R. Current state of development and perspectives of machine-based production meth- ods for dental restorations. Int J Comput Dent 1999;2:935. 9. Priest G. Virtual-designed and computer-milled implant abutments. J Oral Maxillofac Surg 2005;63:2232. 10. Birnbaum NS, Aaronson HB. Dental impressions using 3D digital scanners: Virtual becomes reality. Compend Contin Educ Dent 2008;29:494505 11. Ender A, Mehl A. Full arch scans: Conventional versus digital impressionsAn in vitro study. Int J Comput Dent 2011;14:1121. 12. Pieper R. Digital impressionseasier than ever. Int J Comput 2009;12:4752. 13. Ziegler M. Digital impression taking with reproduc- ibly high precision. Int J Comput 2009;12:159163. 14. Gound TG, Marx D, Schwandt NA. Incidence of fare-ups and evaluation of quality after retreat- ment of resorcinol-formaldehyde resin (Russian Red Cement) endodontic therapy. J Endod 2003;29:624626. 15. Schwandt NW, Gound TG. Resorcinol-formaldehyde resin Russian Red endodontic therapy. J Endod 2003;29:435437. 16. Gehrt M, Wolfart S, Rafai N, Reich S, Edelhof D. Clinical results of lithium-disilicate crowns after up to 9 years of service [epub ahead of print March 2012]. Clin Oral Investig 2012 doi: 10.1007/s00784- 012-0700-x. 17. Kern M, Sasse M, Wolfart S. Ten-year outcome of three-unit fxed dental prostheses made from monolithic lithium disilicate ceramic. J Am Dent Assoc 2012;143:234240. 18. Valenti M, Valenti A. Retrospective survival analysis of 261 lithium disilicate crowns in a private general practice. Quintessence Int 2009;40:573579. 19. Del Corso M, Aba G, Vazquez L, Dargaud J, Dohan Eherenfest DM. Optical three-dimensional scan- ning acquisition of the position of osseointegrated implants: An in vitro study to determine method accuracy and operational feasability. Clin Implant Relat Res 2009;11:214221. 20. Reich S, Ganz S, Weber V, Wolfart S. Digital process- es in implant dentistry [in German]. Implantologie 2011;19:263271.