For decades, dentists have relied on their skills and

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1 Digital transition The collaboration between dentists and laboratory technicians on CAD/CAM restorations Alex Touchstone, DDS; Tom Nieting, CDT; Norbert Ulmer, MBA For decades, dentists have relied on their skills and those of laboratory technicians to provide patients with a wide array of dental restorations. The techniques they used to fabricate restorations, such as lost-wax casting, date back to the 12th century. 1 Given the emergence of technologies such as computer-aided design/computer-aided manufacturing (CAD/CAM) used to produce dental restorations across the past two and one-half decades, traditional work flows and techniques are overdue for reassessment. 2 Until recently, the uses of in-office and laboratory CAD/CAM technology were independent of each other. The dentist had access to chairside CAD/CAM and could produce restorations by means of digital impressions with a high degree of reliability and longevity. 3 Laboratories could scan models made from physical impressions and use CAD/CAM to produce restorations. 4 Recent developments in the handling of the digital impression procedure and further processing of the digital data have affected the quality of digital impressions positively, which allows dentists and laboratories to use their respective technologies in a more complementary and synergistic way. Many dentists who previously expressed no interest in using CAD/CAM now are considering using the technology to convert their conventional impressions to digital impressions while leaving the restorative work to the laboratory, whereas others are embracing it comprehensively by using a combination of chairside and laboratory digital work flows. 5,6 In this article, we present a case in which the in-office and laboratory technologies were used conjointly. The work flow we describe involves digitally capturing full-arch maxillary and mandibular impressions, filling out a digital laboratory prescription, submitting a digital case to the laboratory, fabricating a digital model, and designing and fabricating the restoration in the laboratory (Table and Figures 1 and 2). Although other emerging systems (for example, itero, Cadent, Carlstadt, N.J.; E4D Dentist, D4D Technologies, Richardson, Texas; and Lava COS, 3M ESPE, St. Paul, Minn.) offer similar work flows, we used the CEREC Acquisition Center (AC) with Bluecam system (Sirona Dental Systems, Charlotte, N.C.) ABSTRACT Background. Computer-aided design/ computer-aided manufacturing (CAD/CAM) systems, especially digital impression systems, are connecting dental offices and dental laboratories, resulting in enhanced communication and restorative processes. Methods. The authors present a case report in which they feature the combined use of in-office and laboratory CAD/CAM technologies that include making full-arch maxillary and mandibular digital impressions, filling out a digital laboratory prescription, digitally submitting the case to the laboratory, fabricating digital models and designing and fabricating restorations in the laboratory. Results. The authors enhanced the smile of a 63-year-old woman who was concerned about the appearance of her existing dental restorations and her overall smile by using milled CAD/CAM all-ceramic polylithic restorations. Conclusions. Digital restorative dentistry has matured. Although it previously was limited to the chairside single-visit treatment concept, it now can be applied to almost any restorative situation, including full-mouth rehabilitation. Key Words. CAD/CAM; communication. JADA 2010;141(6 suppl):15s-19s. Dr. Touchstone maintains a private practice in Charlotte, N.C. Address reprint requests to Dr. Touchstone at Touchstone Dentistry, 4835 Sirona Drive, Suite 300, Charlotte, N.C , alex@alextouchstone.com. Mr. Nieting is a laboratory technician and co-owner, DENTATRUST, Charlotte, N.C. Mr. Ulmer is co-owner, DENTATRUST, Charlotte, N.C. JADA, Vol June S

Designing and Fabricating a Full-Contour Restoration or Framework, if Required* Fabricating Model* Finishing Restoration Handwritten Courier, one to three days Must wait for model work, additional

2 TABLE Comparison of traditional work flow with digital work flow. WORK-FLOW STEP TRADITIONAL WORK FLOW DIGITAL WORK FLOW Taking Impressions 10 minutes per arch Two minutes per arch (Figure 1) Filling Out Laboratory Prescription Submitting Case to Laboratory Designing and Fabricating a Full-Contour Restoration or Framework, if Required* Fabricating Model* Finishing Restoration Handwritten Courier, one to three days Must wait for model work, additional day Die stone, sectioning, with potential for error Work flow varies according to the selected materials (for example, monolithic or polylithic materials) Digital prescription entered on screen (Figure 2) in combination with the CEREC inlab and CEREC Connect (both Sirona Dental Systems) systems. CASE REPORT A 63-year-old woman came to our office concerned about the appearance of her existing dental restorations and her smile overall. She recently had completed chemotherapy after undergoing a mastectomy as treatment for breast cancer. Her oncologist cleared her to receive dental care. We performed a comprehensive evaluation that included periodontal probing and diagnosis, a full-mouth series of intraoral radiographs, clinical photographs, diagnostic mounting and wax-up, cone-beam computed tomography (CBCT) (Galileos, Sirona Dental Systems) and a detailed clinical examination that included caries and oral cancer assessments. We interpreted the CBCT scan in-office at the restorative dentist s (A.T. s) level of expertise and then sent it to an oral and maxillofacial radiologist for further interpretation. We found that the patient had multiple failing restorations possibly due, in part, to xerostomia exacerbated by chemotherapeutic medications, as well as an esthetically compromised appearance (Figure 3). Tooth no. 22 was abscessed, and tooth no. 31 had localized advanced periodontitis that was partially a result of improper crown contour and the patient s resultant inability to clean the area effectively. The patient had an arch-width discrepancy resulting in posterior crossbite. Incidental radiologic findings included carotid atheroma on the right side, for which we referred the patient to a cardiologist for assessment and treatment. We discussed treatment options, including the risks and benefits, with the patient. The treatment plan involved extracting tooth no. 31, removing existing restorations and decay, Electronic portal, 10 seconds Completed from digital model Stereolithography models built overnight during framework creation Work flow varies according to the selected materials (for example, monolithic or polylithic materials) * This step is not necessary for computer-aided design/computer-aided manufacturing production of monolithic restorations. Figure 1. Digital Impression captured with CEREC Acquisition Center Bluecam (Sirona Dental Systems, Charlotte, N.C.). Figure 2. Digital prescription form with patient s name, restoration type, material, stump shade, final restoration shade and tooth number selection. Image of inlab reproduced with permission of Sirona Dental Systems, Charlotte, N.C. ABBREVIATION KEY. AC: Acquisition Center. CAD/CAM: Computer-aided design/computer-aided manufacturing. CBCT: Cone-beam computed tomography. FPD: Fixed partial denture. SLA: Stereolithography. 16S JADA, Vol June 2010

22. After assessing the amount of remaining sound tooth structure, the dentist produced custom gold posts and cores for teeth nos. 3, 4 and 14.

3 Figure 3. Retracted view of the patient s preoperative condition showing failing restorations and unesthetic appearance. Figure 4. Digital image of maxillary and mandibular prepared and articulated teeth. Image of CEREC inlab reproduced with permission of Sirona Dental Systems, Charlotte, N.C. and performing endodontic therapy on tooth no. 22. After assessing the amount of remaining sound tooth structure, the dentist produced custom gold posts and cores for teeth nos. 3, 4 and 14. After the dentist placed the gold posts and cores, he placed composite core buildups where necessary and then prepared the remaining teeth by using reduction matrices from the diagnostic wax-up to achieve ideal preparation geometry. The dentist refined the preparations for the entire maxillary arch, as well as for teeth nos. 20 through 22. The dentist generated digital impressions of the preparations by using CEREC AC with the CEREC Connect software. The technique used for capturing a full-arch digital impression involved isolating one-half of the arch, applying a light coating of a reflective medium and placing the camera in overlapping positions from the distal to the mesial aspects while crossing the midline slightly. This process was repeated on the opposite side, and software joined the two halves of the full-arch digital impressions (Figure 4). The dentist opened the CEREC Connect Web portal to fill out the prescription, upload the digital impressions and digital photos, and digitally submit the case to the laboratory. The dentist provisionalized the preparations by using matrices of the wax-up. When the dentist completed the digital impressions and submitted the case to the laboratory, both the dentist and the laboratory technician (T.N.) were able to review the digital case while the patient still was in the dental chair. They were able to verify that the preparations fit the guidelines for the materials that that had been chosen for the restorations (Figure 4). Although they did not identify any problems in this area, if any had occurred, the dentist would have made a revised digital impression after adjusting the preparations. This process would have saved the patient time and prevented her from having to undergo new impression procedures during an additional visit. After reviewing the digital data in the laboratory, the laboratory technician sent the digital impression data to infinident (Sirona Dental Systems), the CEREC Connect model production center, for model fabrication. The resin models were processed with stereolithography (SLA) technology. After the dentist received the models from the laboratory, they were mounted on an adjustable articulator (Figure 5). The dentist had made an earbow transfer registration and centric relation record at the preparation appointment to facilitate proper mounting of the SLA models. The laboratory designed the understructures for the restorations directly from the digital impression data it received from the dentist without having to rescan the SLA models. For all restorations, the laboratory used high-strength zirconium oxide (IPS e.max ZirCAD, Ivoclar Vivadent, Amherst, N.Y.) with an IPS e.max Ceram (Ivoclar Vivadent) porcelain veneer layer. The design on the right side of the patient s mouth was straightforward and simple. The single preparations were nicely spaced and positioned. Because there was more space for the fixed partial denture (FPD) from teeth nos. 9 through 11 compared with the space for the single crowns (teeth nos. 6 through 8), the digital design had to take into account how these factors would affect the final outcome. Adequate support of the veneering layer by the zirconia substructure was ensured, because the substructure was designed with full anatomy and occlusion and then the shape was reduced virtually JADA, Vol June S

Figure 6. Retracted view of final restorations. Figure 5. Final restorations on articulator ready for delivery. by the desired veneering porcelain thickness.

The purpose of the SLA models was to give the laboratory technician the ability to build the veneering porcelain to full contour and to establish proper occlusal and interproximal relationships.

The dentist removed the provisional restorations, cleaned the preparations and evaluated the restorations for marginal fit.

4 Figure 6. Retracted view of final restorations. Figure 5. Final restorations on articulator ready for delivery. by the desired veneering porcelain thickness. After the laboratory finished the restorations by using the SLA models, the restorations were returned to the dentist for seating (Figure 5). The purpose of the SLA models was to give the laboratory technician the ability to build the veneering porcelain to full contour and to establish proper occlusal and interproximal relationships. When the dentist placed the restorations, local anesthetic was administered to the patient to keep her comfortable. The dentist removed the provisional restorations, cleaned the preparations and evaluated the restorations for marginal fit. The crowns were trial-seated in pairs and then tried sequentially to verify that there were appropriate interproximal contacts. The dentist seated all of the restorations together and evaluated them for overall occlusal and interproximal adaptation, which was determined to be clinically exceptional. Because the material chosen for the patient s restorations was a polylithic combination of materials composed of a zirconia core, the dentist cemented the restorations conventionally with resin-modified glass ionomer cement (Fuji II, GC America, Alsip, Ill.). After cementing the crowns, the dentist performed a final occlusal check and removed minor interferences in lateral excursive and protrusive movements with a ceramic polishing point. He then polished the adjusted areas to a high shine Figure 7. Final smile demonstrating improvement in appearance. Tooth no. 7 would have benefited from crown lengthening via gingival sculpting. with progressively finer-grained rubber points. The dentist saw the patient again two weeks later for reverification of her occlusal scheme and made minor adjustments at that time. Three months after that, when the extraction site had had sufficient time to heal, the dentist used the same work flow to create an FPD that was double abutted to teeth nos. 28 and 29 with a distal cantilever pontic for missing tooth no. 30. The dentist saw the patient again on three occasions during the next six months to reassess her comfort level and the occlusal stability and harmony of the restorations and to ensure that she maintained periodontal health (Figures 6 and 7). She is following a three-month follow-up regimen. RESULTS The case we report illustrates the benefits of using a digital work flow to improve treatment outcomes. Key areas that both the dentist and laboratory technician observed as beneficial were immediate verification of the quality of the digital impressions, creation of marginal areas of the res- 18S JADA, Vol June 2010

5 toration (substructures in this case) directly from the digital data, ability to work on substructures while SLA models are processed, automatic reduction of full-contour proposed restorations in the design process to account for ideal veneering porcelain thickness and support, decreased turnaround time owing to these efficiencies and decreased number of postinsertion adjustments. Areas that would benefit from being further incorporated into the digital work flow we described include digitally fabricated wax-up; elimination of earbow transfer by using CBCT data, which may be possible because of the lack of distortion in CBCT data 7 ; digitally created functionally correct articulation; and recording, assessing and subsequent adjusting of occlusion by using a digital recording device. CONCLUSIONS In the past, dental CAD/CAM was either a chairside or a laboratory restorative concept. The technology now allows dental professionals to combine these two concepts and create synergies by making it easy to use the dentist s and the laboratory technician s expertise as appropriate and required. As with making conventional impressions, it also is possible to generate bad digital impressions. When this occurs, an examination of the virtual model that can be magnified on the monitor allows the dentist, laboratory technician or both to identify the deficiency and correct it without the delay that may happen when making a conventional impression. Although full-arch digital impressions are somewhat novel, the results of one study 8 suggest that precision improves with use of this digital technology. Digital processes have the potential to reduce errors and introduce cost savings by eliminating conventional impression materials and their subsequent manual manipulation. These processes also can provide a more comfortable experience for patients. Although technology can be fascinating for its own sake, the ultimate justifier of new technology should be enhancing the overall level of dental care while increasing patients comfort. Disclosures. Dr. Touchstone has received honoraria for educational programs from Sirona Dental Systems, Charlotte, N.C. Mr. Nieting has been employed by Sirona Dental Systems and has served as a consultant and presented training courses for Sirona Dental Systems. Mr. Ulmer has been employed by Sirona Dental Systems and has served as a consultant and presented marketing courses for Sirona Dental Systems. 1. Theophilus. On Divers Arts: The Foremost Medieval Treatise on Painting, Glassmaking and Metalwork. Hawthorne JG, Smith CS, trans. Mineola, N.Y.: Dover; Spear F, Puri S, Manji I. In-office CAD/CAM: the future of your practice? Dent Today 2009;28(3):68, Fasbinder DJ. Clinical performance of chairside CAD/CAM restorations. JADA 2006;137(9 suppl):22s-31s. 4. Miyazaki T, Hotta Y, Kunii J, Kuriyama S, Tamaki Y. A review of dental CAD/CAM: current status and future perspectives from 20 years of experience. Dent Mater J 2009;28(1): Christensen GJ. Impressions are changing: deciding on conventional, digital or digital plus in-office milling. JADA 2009;140(10): Christensen GJ. Successful use of in-office CAD/CAM in a typical practice. JADA 2008;139(9): Mehl A. 2009: the quantum leap for intraoral optical measurement? Int J Comput Dent 2009;12(1): Ziegler M. Digital impression taking with reproducibly high precision. Int J Comput Dent 2009;12(2): JADA, Vol June S

Digital Smile Design using the M Proportions and GPS 2D to 3D Digital Facebow: Clinical Case 1

Digital Smile Design using the M Proportions and GPS 2D to 3D Digital Facebow: Clinical Case 1 Dr Alain Méthot Dr Marco Delcorso A young female patient previously suffering from gastric reflux came to