When the Old World Meets the New World
Combining digital dentistry with masterful hand crafting to achieve esthetic success
Adamo E. Notarantonio, DDS
Digital dentistry refers to "the use of dental technologies or devices that incorporate digital or computer-controlled components to carry out dental procedures rather than using mechanical or electrical tools."1The use of digital dentistry allows clinicians to perform dental procedures more efficiently than the use of mechanical tools, both for restorative and diagnostic purposes. One often overlooked aspect of digital dentistry is that it facilitates work and communication with craftsmen in any part of the world. With the vast number of social media networks available, there is now visibility and access to more skilled technicians than dentists may have been exposed to previously.
As 3 billion people currently utilize social media, these networks have enabled communication with a greater number of people on a global scale, providing the opportunity for easier collaboration.2 These networks breed and inspire co-creation and, more importantly, the culture of collaboration.3 The internet allows people from around the globe to easily connect to one another, making collaboration simpler and more effective.
Case Report
A 48-year-old male patient presented for a cosmetic consultation (Figure 1 and Figure 2). His chief complaint was simple: "I need to do something about my teeth; I am sick and tired of not smiling." As with any patient, an in-depth conversation was conducted to discuss his concerns. Because the patient was not originally a patient of record, he was advised that a thorough workup would need to be completed prior to coming up with a final plan. This workup included a full mouth series of radiographs, mounted models on an articulator (Panadent articulator, Panadent) use of a facebow (Kois Dento-Facial analyzer, Panadent), a complete series of 14 diagnostic photographs, a video of the patient speaking, and a comprehensive evaluation of the patient's biomechanical, periodontal, functional, and dentofacial risk assessments. When the patient returned a week later to discuss the findings, the photographs and video were reviewed and an in-depth discussion was had regarding tooth size, gingival display, and tooth position. An orthodontic option was first presented to correct the rotations as well as to intrude tooth No. 10, eliminating the gingival display seen during the patient's smile. The patient rejected the orthodontic treatment option, so he was advised to undergo crown lengthening and gingival recontouring in the area of tooth No. 10 to eliminate these issues. Once again, the patient refused the treatment option and stated that the gingival display did not concern him. His main goal was to close the space between his central incisors and have them line up with a uniform color.
Following a risk assessment analysis, the decision was made to place 12 porcelain veneers to address the dentofacial risk factors and problems discovered in the comprehensive exam. For this case, two different mock-ups would be created for comparison purposes. Digital scans and upper and lower bite registrations were completed using an intraoral scanner (iTERO Element® 2, Align Technology). The STL files were exported and sent to two different laboratories. The laboratories were also sent all of the diagnostic photos, the video, and an in-depth laboratory prescription clearly explaining the patients concerns and final desired outcome. Communication between the doctor, the patient, and the ceramist is the single most important key to achieving esthetic success.
One laboratory was selected to complete the smile design digitally, and another was instructed to print the models and have a master ceramist complete the smile design using the conventional wax method. Remember, when sharing patient information and requesting consultation in the United States, the Health Insurance Portability and Accountability Act (HIPAA) privacy and security rules always need to be considered. If patient information is shared for collaboration within a social network, a secure means of communicating that information must be used. In this particular case, the files were sent to each laboratory via Dropbox™, and all email communications were sent through a secure, HIPAA-compliant mail server.
When both cases were complete (Figure 3 and Figure 4), the patient returned to the office and had the opportunity to try-in both designs via a provisional matrix. Each matrix was filled with an autopolymerizing acrylic resin (InstaTemp®, Sterngold) (Figure 5).The mock-ups exhibited significant differences in the shape, size, and position of the teeth (Figure 3 and Figure 4). When asked which mock-up he preferred, the patient chose the conventional wax mock-up, which was also the preference of the clinician. Although both mock-ups demonstrated a significant improvement, the patient selected the handcrafted one based on his personal preference. Another appointment was scheduled to move forward with preparation, impressions, and provisionalization of the case.
At a preparation appointment involving fewer teeth, the shade is normally taken first, prior to any anesthetic being delivered. The reasoning behind this is to avoid any dehydration of the dentition. A study by Burki and colleagues that used both instrumental and visual assessment showed a significant change in the shade of teeth when dehydrated.4 Teeth became lighter, and the perceivable color change did not return to the baseline shade within 30 minutes of rehydration. Therefore, shade matching procedures should be carried out before the teeth are exposed to anything that could cause dehydration. In this case, because the entire upper arch would be changed, the final shade could be determined by the patient and clinician.
Prior to preparation, the provisional was placed over the existing teeth (Figure 6 and Figure 7). This technique allows the final result to be used as a preparation guide, which is helpful in minimizing unnecessary tooth preparation. In this particular case, certain teeth required a more aggressive preparation to achieve the desired result. As previously mentioned, if orthodontic treatments were performed prior to preparing the teeth, a more minimally invasive approach could have been taken.5 After the provisional was placed, appropriate depth cuts required for the function and esthetics of the final restorative material were made. These depth cuts were marked in pencil, and the final preparations were completed through the provisional material (Figure 8).6 This helps to ensure the least amount of tooth reduction wherever possible, preserving the greatest amount of enamel for bonding.7Studies have shown that enamel conservation, especially at the margins, increases fracture resistance and reduces microleakage.8 Additional studies have shown that veneers bonded to dentin with margins in dentin were 10 times more likely to fail than veneers with margins in enamel.9 The final preparations were completed as conservatively as possible, and adequate reduction based on the wax-up was confirmed with reduction guides provided by the laboratory (Figure 9 and Figure 10).
Next, impressions were completed using the intraoral scanner. Digital impression taking has become a more accepted technique when compared with conventional impression-taking techniques.10 In addition to reducing patient discomfort, increasing time efficiency, and simplifying clinical procedures for the dentist, optical impressions can eliminate the need for plaster models and facilitate better communication with dental technicians and patients. Occasionally, it can be difficult to detect deep margins around prepared teeth using digital scanners; therefore, there is certainly still a place for conventional impression taking. In this case, the conservative nature of the preparations allowed for an accurate impression utilizing a digital technique.
After careful finishing and polishing, especially at the gingival margins, the provisional restoration was inserted (Figure 11). Prior to sending the impressions to the laboratory, the patient was allowed a 24-hour period to evaluate the provisional restoration in terms of tooth shape and size as well as overall esthetics. He was extremely happy with the result, so the provisional was sent to the technician to begin manufacturing the veneers. Had the patient been unhappy, he would have been recalled for further adjustments and a new scan of the provisional. Using a shade guide (VITA Toothguide 3D-MASTER®, VITA) and a mirror, the final shade was determined with the patient, and a creative smiles gallery catalog was used to select the desired surface finish, texture, incisal characteristics, and translucency. The patient did not want a drastic change from his existing shade. Once he selected his preferred shade and all of the characteristics he desired, these selections were communicated to the technician along with the optical impression.
The technician designed the veneers, printed their initial layers using a 3-dimensional printer (Form 2 3D Printer, Formlabs) (Figure 12), pressed them with lithium disilicate porcelain (Shofu Vintage LD, Shofu Dental), and then finished them with additional layers of porcelain (Figure 13 through Figure 16). The layers were completed with a stratification technique that followed the principles of bioemulation,11 using internal layers to resemble dentin, translucent intermediate layers, and a final external coating of opalescent material to simulate the enamel.
After receiving the restorations, the intaglio surfaces of the lithium disilicate veneers were treated with hydrofluoric acid and silanated prior to try-in per the manufacturer's instructions. At the time of insertion, the provisionals were removed and isolation was accomplished using a rubber dam. Further moisture control was achieved by placing size 00 retraction cord in each sulcus (Figure 17). Prior to try-in, each preparation was air abraded (PrepStart™, Zest Dental Solutions) utilizing 50-μm aluminum oxide at 40 psi under a microscope. This technique helps ensure the removal of any provisional cement or debris from the teeth, yielding an ideal surface for bonding.12 Next, the preparations were etched for 15 seconds using 37% phosphoric acid with benzalkonium chloride (Select HV® Etch w/BAC, Bisco Inc.) then thoroughly rinsed for 30 seconds using water only. The surface was blotted dry with a cotton roll to avoid desiccation. Following this, two coats of adhesive (All-Bond Universal®, Bisco Inc.) were applied separately and scrubbed for 15 seconds each with a microbrush. In order to evaporate the excess solvent, a hot air dryer was used for 30 seconds. Finally, the surface was light-cured for 10 seconds per the manufacturer's instructions.
Each veneer was placed using a light-cured resin cement(Choice 2™, Bisco Inc.) and tack-cured under low power for 3 to 5 seconds, which resulted in a gel-like state. The excess cement was removed with a brush prior to final curing (Figure 18). An article by Pereira and colleagues showed that marginal surface polishing has a significant influence on surface roughness for all cement removal techniques.13Cement removal using a brush or microbrush resulted in lower biofilm accumulation when compared with the blade removal technique. After the brush was used, the margins were carefully finished and polished under a microscope to ensure complete cement removal and proper margination. The patient returned 24 hours later for occlusal adjustments and 1 month later for evaluation and final photographs (Figure 19).
Conclusion
Digital technology has changed what is possible in oral healthcare as it relates to both function and beauty. The internet has transformed the profession of dentistry by making large quantities of information accessible with the push of a button or the click of a mouse.14 Arguably, no other discovery or innovation has come close to the impact that digital technology has had regarding sharing ideas and facilitating collaboration between dentists and master craftsmen of dental restorations. The digital future is bright, and clinicians are witnessing an amazing era of craft and art in which computers and other technologies are used in various combinations with traditional techniques.
About the Author
Adamo E. Notarantonio, DDS
Fellow
American Academy of Cosmetic Dentistry
Private Practice
Huntington, New York
Clinical Instructor
Honors Aesthetic Program
New York University
New York, New York
Acknowledgment
The author would like to thank ceramist Julian Cardona, CDT, Guayaquil, Ecuador, for his outstanding work.
References
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