The last decade saw a rapid increase in manufacturers offering digital intraoral scanning technologies. In addition to new color scanners that allowed easier, faster, and powder-free data acquisition, many manufacturers began opening their platforms to allow digital files to be exported and used in different ways. Popular scanners now include Primescan (Dentsply Sirona), iTero (Align Technology), TRIOS (3Shape), CS 3600 and CS 3700 (Carestream Dental), Emerald (Planmeca) and Medit i500 (Medit), among others. Instead of being limited to specific hardware and software, clinicians are now able to use their digital scans for in-office manufacturing, or they can export the scanned data digitally to a dental laboratory of their choice for processing and fabrication of the restoration(s). Incremental software updates can be installed and used with existing hardware to substantively improve system capabilities without replacing the entire system. Open architecture platforms allow the clinician to implement and utilize technology at his or her own pace. Instead of using digital scanning primarily for same-day procedures, dentists are able to outsource larger cases, as needed, with increased complexity. Essentially, digital techniques can be now utilized for any case, not only for same-day monolithic restorations.

Figure 1. The operatory is equipped to broadcast intraoral scans in real time, allowing the patient to watch during scan acquisition.

There is now a paradigm shift occurring with regard to the scope and role of intraoral scanning in the dental practice. In addition to replacing physical impression materials, intraoral scans are becoming a vital component in patient education protocols, diagnosis and treatment planning, and long-term management. Emerging non-restorative uses of digital technology are redefining how intraoral scanners are being used. When selecting a system today, dentists need to consider not only scanner accuracy but also the delivery system, form factor, shade-matching capability, same-day workflow options, non-restorative options, integrated smile design, patient monitoring, and caries diagnostic capabilities. Dental technology companies are responding to clinicians’ needs by creating integrated platform ecosystems that support a variety of hardware and software to improve ease of use, user experience, and workflow efficiency.

Figure 2. The prosthetic timeline sequence of milestone intraoral scans used for dataset comparison for restorative treatment.

In our practice, intraoral scanning has moved beyond being used for manufacturing alone and is used at every new patient visit as well as during annual recalls. Intraoral scans are a prominent feature of a patient’s initial visit, and they are used as an education tool to explain findings and create engagement as well as to provide a unique patient experience. The operatory is designed to be able to simulcast the intraoral scan as it is being acquired so the patient can be involved in the scanning process (Figure 1). This allows patients to visually engage with their dental findings, creating a powerful communication tool for the provider. Once findings and options are generated, the scans are shared at subsequent follow-up conferences in non-clinical consultation spaces to finalize treatment planning in a co-diagnostic manner. When possible, patients are annually scanned so that scans taken over time can be overlaid, allowing subtle changes to be identified using digital patient monitoring software.

Intraoral scans and patient monitoring software can also be utilized in concert for treating indirect restorative cases. Prosthetic timelining, a workflow concept developed by the author, refers to a treatment protocol whereby the clinician obtains intraoral scans during specific milestones of treatment to allow dataset comparison with monitoring software during the process (Figure 2). Combining digital smile design software with patient monitoring software to envision and communicate a desired clinical outcome allows for precise digital dataset comparisons, and this has led to the development of protocols that can improve the predictability of restorative treatment.

Figure 3. Initial presentation with failing and discolored laminate veneers.

Figure 4. Portrait photos required for digital smile design.

Figure 5. A 2-D wireframe digital smile design of the proposed outcome.

CASE REPORT
A 59-year-old female presented to our office for comprehensive examination. Her chief concerns were related to swelling on her upper right, and she was also unhappy with her upper front teeth due to discolored and uneven laminate veneers placed 20 years prior.

The patient had adult-onset diabetes and hypertension; both were under control with medication. She had no known drug allergies, and her medical history was otherwise non-contributory.

A temporomandibular exam was found to be unremarkable with a normal range of motion noted that was without deviations or joint sound, a maximum opening of 50.0 mm, and no pain upon muscle/joint palpation.

The patient presented with a heavily restored dentition with existing dental implants and a combination of full-coverage crowns and direct restorations. The patient also presented with gingival recession, recurrent caries, and marginal breakdown on the existing laminates on teeth Nos. 7 to 10 (Figure 3). The upper right posterior implants had crestal bone loss with inflammation noted. There was generalized early bone loss and localized advanced loss around tooth No. 4. There was localized bleeding on probing on tooth No. 4, and probing depth was 10-plus mm to the apex.

The patient was referred to a periodontist to address the peri-implantitis as well as failing tooth No. 4. The patient underwent a comprehensive periodontal examination and diagnosis to address our initial clinical findings. She returned after acute conditions were treated and resolved with the desire to replace the upper ceramic laminates followed by replacement of tooth No. 4 with a dental implant.

The restorative treatment plan was to replace and restore teeth Nos. 5 to 12 with new ceramic restorations, followed by a single-tooth implant restoration for tooth No. 4.

Data collection for case planning was completed with a preoperative intraoral milestone scan (TRIOS Color Pod [3Shape]) and a digital full-mouth series of radiographs (DEXIS), and studio-style smile and retracted portraits (Figure 4) were taken to complete a digital smile design (Figure 5) (TRIOS Smile Design [3Shape]). The patient was involved in the smile design process by showing her multiple potential tooth shape libraries to help design the shape and contour of the intended restorations. Once the patient and dentist came to an approved 2-D smile design, the intraoral scan, 2-D smile design photo, and other photos were sent to the digital dental laboratory. In the laboratory, the intraoral scan was aligned to the portrait photographs, and a 3-D digital wax-up was completed in harmony with the initial patient-approved design (Figure 6). The digital wax-up model file was then sent electronically in STL format to the dentist, and then the model was printed in the dental office (Form 2 [Formlabs]). A putty matrix was created using the digital wax-up model, and the patient returned to have a bis-acryl (EXACTA Temp Xtra [EXACTA Dental]) mock-up fabricated directly over the untreated teeth (Figure 7). This allowed the patient and clinician to confirm the quality of the 2-D smile design in a reversible manner prior to tooth preparation. This is a critical step to verify that the 2-D virtual smile design translates to a functional, aesthetic, and phonetically desired result for the patient. In addition, the mock-up was intraorally scanned at this visit to provide yet another milestone dataset. After the mock-up was transferred using bis-acryl provisional material, tested, approved, and scanned, the treatment could commence.

Figure 6. Intraoral scan aligned to the smile design facial portrait used for the digital wax-up.	Figure 7. Bis-acryl mockup applied directly over untreated teeth.
Figure 8. Depth cuts made through the bis-acryl mockup, ensuring conservative tooth preparation design.	Figure 9. Digital intraoral scan of the preparations, opposing dentition, and bite relationships.

Figure 10. Final restorations.

The patient returned for the preparation appointment. Local anesthesia was administered (2% lidocaine with 1:100,000 epinephrine), and a lip/cheek retractor was inserted (OptraGate [Ivoclar Vivadent]). The bis-acryl mock-up was reapplied and scanned to create another data milestone scan prior to beginning the preparations. Depth cuts were made through the mock-up to ensure the removal of existing of tooth structure was as conservative as possible (Figure 8). Upon completion of the tooth preparations, the same putty matrix was used again to create the bis-acryl provisionals. The preparations were retracted and scanned in (Figure 9), and the provisionals were delivered in conventional fashion. The scans were sent to the laboratory team with instructions to hold off on further work until the patient returned one week later for a postoperative visit. At this visit, aesthetics and phonetics were evaluated, and the final shade determination was made. Also, an intraoral milestone scan was taken of the approved provisionals. The laboratory team was then instructed to digitally align this intraoral scan with the original scans sent to copy the contours of the provisionals.

The patient returned 2 weeks later for try-in and delivery. The provisional restorations were removed, and the preparations were cleaned using pumice. The restorations (IPS e.max [Ivoclar Vivadent]) were individually tried in with water, then as a group. Once approved by patient and clinician, the restorations were cleaned (Ivoclean [Ivoclar Vivadent]), and the intaglio surfaces were treated using a universal primer (Monobond Plus [Ivoclar Vivadent]), and then they were seated with resin cement (Variolink Esthetic LC [Ivoclar Vivadent]) and light-cured (VALO [Ultradent Products]) according to manufacturer protocols (Figure 10). Excess cement was removed, and the restorations were finished and polished using fine diamonds and ceramic polishing points. The occlusion was checked in maximum intercuspation and in protrusion, working, and crossover excursions.

A one-week post-insertion visit was completed where all parameters were evaluated once again. Post-op photos were taken, and a final milestone intraoral scan was done.

DISCUSSION
This case provides an example of leveraging digital technologies not only to complete the restorative portion of treatment, but also to connect with, educate, engage, and communicate with the patient as well as to collaborate with the laboratory team. A diagnostic intraoral scan was taken during the patient’s initial visit and was broadcast on the operatory monitors in real time. The patient was able to see her mouth in great detail, allowing for a co-discovery process related to the findings and co-diagnosis of her conditions. Digital photography used to superimpose tooth libraries during the process of digital smile design allowed her to visualize the proposed changes to her teeth and to also be an active participant in the treatment planning process. The workflow essentially helped the clinician to explain the risks and benefits of various treatment options and in providing proper informed consent prior to beginning treatment.

Figure 11. Digital patient monitoring software was used to compare prosthetic timelining milestone datasets (top) and 2-D cross-sectional analysis of milestone datasets (bottom).	Figure 12. Virtual smile design created with digital smile design software prior to treatment (top). The completed case (bottom).

By utilizing prosthetic timelining, a series of digital datasets was acquired during the course of planning and treatment. Milestone scans consisted of the pre-op presentation, mock-up, provisionals, and provisionals one week post-op and again after final delivery. By using dataset comparison and patient monitoring software, we were able to align the prosthetic timeline scans and compare each scan critically against others. This allows the treating clinician to determine how the case is progressing through each phase and identify if any deviations occur during the treatment. Digital patient monitoring software allows the user to visualize one scan compared to another graphically, with time-lapse video and also in 2-D cross-section (Figure 11). Cross-sectional analysis allows for precise measurements of the different datasets down to a tenth of a millimeter. These kinds of tools are already routinely used by technicians using dental CAD software.

Patient monitoring software now allows the clinician similar tools to assess, evaluate, and critique a case at levels of detail not possible without current digital technology. If desired, an additional prosthetic timeline milestone can be obtained by scanning the final restorations placed on the printed models using an intraoral scanner. This can be especially valuable with hand-layered restorations to verify that the layered ceramic does not deviate significantly from the other datasets in the timeline (ie, the approved mock-up and provisionals). Via this technology, the clinician can now evaluate laboratory work and predict how well a try-in visit will go prior to actually trying the units in the patient’s mouth. The benefit of prosthetic timelining to both clinician and patient is the ability to design an outcome virtually and to predictably be able to deliver that design in reality (Figure 12). The final milestone scan of the completed restorations also provides an important dataset of the finished case. In the event there are changes in the future or a need for a remake due to breakage, a future intraoral scan can be taken and compared against the final milestone scan.

CLOSING COMMENTS
Intraoral scanning was once mainly considered as a replacement for physical impression materials. However, advances in digital scanning hardware and software applications allow dentists to use intraoral scanners to communicate with, engage, and educate patients better than ever before. Digital smile design, patient monitoring software, and prosthetic timelining protocols allow unprecedented collaboration and predictability in prosthetic dentistry.

Dr. Rajan is a general practitioner in Mendham, NJ, delivering restorative, implant, and aesthetic services. He has been involved with digital dentistry in his private practice since 2007, focusing on optimizing intraoral scanning and developing digital workflow protocols. He lectures internationally as a key opinion leader for 3Shape, Straumann, and Henry Schein. Dr. Rajan attained Fellowship in the AGD and has had postgrad training at both Spear Education and the Pankey Institute. He is actively involved in dental education as the assistant director of digital dentistry at the Touro College of Dental Medicine and founding member and faculty at CADPro Academy, a digital dentistry education center in Woodbury, NY. He can be reached at rnarendmd@gmail.com.

Disclosure: Dr. Rajan is a paid speaker and key opinion leader for 3Shape.

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How to Prep Porcelain Veneers

INTRODUCTION
Since the introduction of the implant-retained denture principle in 2004, there has been an exponential increase in patient awareness and demand for these types of procedures. Studies have shown this protocol to be a very successful long-term restorative option¹; however, over the last few years, its predictability has come under scrutiny. This is especially true in upper-arch applications where peri-implantitis, caused by ridge-lapped designs, has been identified as the probable cause of implant failures. Many articles address the restorative value of prosthetically driven surgical plans combined with guided surgery.² When planned, used in the correct application, and processed without an overlap, restoring a patient with a hybrid implant-retained prosthesis, even in the maxilla, has proven to be predictable. These hybrids are extremely well received by patients and ultimately lead to word-of-mouth referrals to the restoring clinician.

Initial workflows were unpredictable, and restoring a hybrid was a daunting task, often requiring 5 or more appointments. Technology has transformed the way we restore these hybrids, making this protocol one of the most predictable in a clinician’s arsenal. In the past, material options were limited to denture teeth wrapped with acrylic over a titanium frame. Because of the inherent weakness in acrylic, these hybrids were processed with additional bulk to strengthen them, and this ultimately leads to complications with cleanability.³ The interaction between the rigid titanium frame and flexible acrylic causes accelerated material fatigue and, ultimately, prosthetic failure. Today, these acrylic hybrids are notorious for failures, and this, in turn, is causing doubt in patients and concerns within the restorative community.⁴

Initially, zirconia hybrids were touted to be the ultimate restorative solution, but most high-strength zirconia materials exhibited bright and unnatural aesthetics.⁵ These aesthetic challenges forced technicians to layer ceramics over the substructures, thus negating the predictability of the digital workflow and reducing the strength monolithic materials offer.

Hybrid full-arch restorative techniques and materials have undergone a substantial evolution over the last decade. The modern-day restorative clinician has efficient and predictable workflows at his or her disposal to help restore these once-daunting cases. Combining these workflows with the latest high-strength and translucent zirconia materials⁶ finally allows the team to restore hybrids with exceptional accuracy, superb aesthetics, and a high-strength monolithic occlusion. This article will discuss some of these options and show how to predictably restore an implant-retained fixed hybrid.

Figure 1. Scan flags were placed, and the hybrid was digitized.	Figure 2. Digital STL file of the scanned opposing arch and bite.
Figure 3. PMMA-printed hybrid replica.	Figure 4. The replica was split between implants, and a transfer tray was fabricated.
Figure 5. The replica was placed in segments.	Figure 6. The units were luted together.

Data Gathering Appointment
In the past, a surgically converted prosthesis was mostly seen as a comfort device for the patient. Technology now allows the clinician to use this prosthesis as a tool to predictably combine multiple clinical appointments. The clinical steps to effectively utilize the converted prosthesis are as follows:

• Remove the conversion denture
• Place scan flags and digitize the hybrid (Figure 1)
• Replace and scan the opposing arch and bite
• Capture smile pictures and make diagnostic notes

After data capture, the STL file (Figure 2) is transferred to the dental laboratory with diagnostic notes and patient pictures. The laboratory team will then use this data to digitally design (Figure 2) and print a device in PMMA (Figure 3) that closely mimics the original hybrid but also has any requested diagnostic changes. Implant interfaces are digitally placed, the hybrid replica is split between implants, and a loading tray is fabricated (Figure 4).

The replica is now shipped to the clinician to capture a verified impression, diagnostic try-in, and bite registration, all in one clinical appointment.

Data Capture Appointment
The clinician will remove the conversion hybrid and replace it with the hybrid replica. Transferring the replica is accomplished using the supplied delivery tray. After positioning the replica, the clinician will secure it to the abutment level. This transfer can be done in one piece or in segments, if required (Figure 5). Care is taken to ensure that individual pieces are not contacting each other, and adjustments are made as needed. After aligning the pieces, the units are luted together with a tooth-colored composite or a temporary acrylic (Figure 6). This step effectively ties the implants together and, by doing so, verifies the impression. After luting is completed, bite, incisal edge, and all other required functional and aesthetic adjustments are made to the hybrid replica (Figure 7). Then smile pictures are taken along with any relevant diagnostic notes. To complete the data capture appointment, the clinician will flow a light-body vinyl polysiloxane (VPS) or polyether impression material into the intaglio surface of the replica (Figure 8). This will index a horseshoe impression of the tissue surface in relation to the hybrid replica. This impression technique allows for a neutral tissue position indexing, which is very important for an accurate pontic-to-tissue adaptation in the final prosthesis.

After this appointment, the clinician will have:

• A verified impression
• A patient-approved tooth try-in
• A verified bite
• Smile images with documented patient aesthetic expectations

Lab Process: Prototype
The laboratory team now places lab analogs into the replica, injects soft tissue, and pours a model into the hybrid replica. After pouring, the replica is mounted with the opposing arch using the supplied bite registration. The replica is now digitized using a bench-type scanner. The data is then imported into digital design software, and all requested diagnostic changes are made to the replica in digital format. After design changes are made to the digital media, the prototype is fabricated. If the prototype is to be used as a dual-use device (try-in and long-term emergency denture), the file is milled with a more aesthetic and durable double-cross-linked PMMA material. If the prototype will be discarded after the try-in, it is printed with a more economical tooth-colored photo-polymer material. Milling with a double-cross-linked PMMA material, such as Temp Esthetic 95 (Harvest Dental), allows the lab team to fabricate a highly aesthetic prototype that can be delivered to the patient as an emergency hybrid backup. (A variation is if the restorative team is confident that the hybrid replica accurately represents the patient expectations, bite, and tooth setup, the prototype appointment can be eliminated in lieu of a final delivery appointment. Although delivery can be successful without a prototype, it is suggested to not omit this very important step.)

Figure 7. The bite was checked, and the required adjustments were made.	Figure 8. Impression material was flowed into the intaglio of the replica.
Figure 9. The double-cross-linked PMMA prototype was tried in.	Figure 10. Digital scan of the prototype for the copy-mill of the final.
Figure 11. MiYO Liquid Ceramic (Jensen Dental) was applied to the base structure to create gingival architecture.	Figure 12. Final delivery of the upper and lower zirconia hybrid.
Figure 13. Artistic changes were added to the captured data.	Figure 14. Translucent transition exhibited by advanced, high-strength zirconia materials.

Prototype Try-in
At the prototype try-in appointment, the clinician will remove the converted hybrid and replace it with the prototype for patient evaluation and final adjustments, if required. In case of any uncertainty, a double-cross-linked PMMA prototype hybrid (Figure 9) can be delivered as a transitional device. This allows the patient and clinician time to fine-tune any adjustments and/or resolve any aesthetic questions before transitioning to the final prosthesis.

Prototype to Final Prosthesis
Once patient approval with the prototype is acquired, the prototype will be used to copy-mill the final prosthesis.

Modern-day digital workflows, incorporated with advanced, high-strength translucent zirconia materials, offer a huge advantage to the restorative team. This workflow allows for no data loss and, thus, extremely predictable final deliveries. In the past, data gathering was negated by layering ceramics over zirconia frames. With today’s advanced zirconia materials, the need for layering ceramics has been eradicated, producing a flawless copy process of what the patient and clinician have approved.

Option 1: The clinician removes the prototype and returns it to the lab, with the original models, for the final fabrication of the hybrid.

Option 2: The clinician digitizes the hybrid intraorally (Figure 10) and sends the STL file to the lab for model matching of the adjusted hybrid with the original design files. The laboratory will digitally adjust the initial design file to match the intraoral file before milling of the final hybrid. This process (proprietary to Absolute Dental Services, Durham, NC) is achieved by digitally indexing the final prototype with fiduciary markers before delivery for prototype try-in. This process allows the patient to remain in the prototype during the final fabrication process and greatly increases patient acceptance and comfort during the fabrication process.

An exact copy of the patient-approved captured data is now delivered in the final prosthesis (Figures 11 and 12). Close attention is paid to maintaining the integrity of the captured data, and it is only altered to accommodate artistic and small diagnostic changes as requested (Figure 13).

A predictable hybrid outcome is very dependent on processing with one of today’s modern materials in combination with a fully digital workflow.

Multiple materials exhibit these requirements, ranging from polymer-reinforced nanoceramics (Crystal Ultra [Digital Dental]) supported by carbon acetal substructures (TriLor95 [Harvest Dental]) to high-strength, translucent monolithic zirconia materials (Argen HT+ [Argen Corporation]). It is highly recommended that only zirconia materials with a 1,000-MPa or greater flexural strength be used for monolithic zirconia hybrids.

To achieve a predictable and fully digital workflow with a high-strength result, this hybrid was processed with Argen HT+ zirconia. Although this material is not a multilayer or transitional material, the inherent translucency, combined with its high strength, allows the modern-day technician to produce an extremely aesthetic result exhibiting a very natural appearance (Figure 14).

High-strength, highly translucent zirconia materials in this category includes Argen Corporation’s Argen HT+ (1,250 MPa), Dentsply Sirona’s Cercon HT (1,200 MPa), Ivoclar Vivadent’s e.max ZirCAD Prime (1,200 MPa), Kuraray America’s KATANA Zirconia HT (1,125 MPa), and Aidite’s SuperfectZir HT (900 MPa).

Layering ceramics to achieve aesthetics is labor intensive, negates the accuracy of the digital workflow, and reduces the strength of a monolithic material. Furthermore, it adds unnecessary additional costs and brings unpredictability to the hybrid workflow.

CLOSING COMMENTS
The patient shown in this article was introduced to the team after multiple implant failures. These failures were caused by many years of surgical mistakes compounded with multiple attempted corrective surgeries. This case emphasizes the importance and effectiveness of prosthetically driven surgical planning and guided surgery combined with a digital workflow.

Acknowledgments:
The prosthetics shown in this article were fabricated by Jack Marrano, director of Signature Prosthetics at Absolute Dental Laboratory, in conjunction with his Advanced Restorative Team (Absolute ART).The definitive case was kindly donated by restorative contributions from Dr. Mark Scurria, a prosthodontist from Triangle Restoration Dentistry in Durham, NC. Drs. James Davies and Stefan Simoncic from High-House Oral Surgery in Cary, NC, donated their time to stabilize the patient by removing failing implants and strategically replacing them with new implant fixtures. Absolute Dental Services donated the prosthetics, and Nobel Biocare donated the implants and restorative components.

References

1. Balshi TJ, Wolfinger GJ, Slauch RW, et al. A retrospective analysis of 800 Brånemark System implants following the All-on-4 protocol. J Prosthodont. 2014;23:83-88.
2. Block MS. Maxillary fixed prosthesis design based on the preoperative physical examination. J Oral Maxillofac Surg. 2015;73:851-860.
3. Soto-Penaloza D, Zaragozí-Alonso R, Penarrocha-Diago M, et al. The All-on-4 treatment concept: systematic review. J Clin Exp Dent. 2017;9:e474-e488.
4. Ladetzki K, Mateos-Palacios R, Pascual-Moscardó A, et al. Effect of retention design of artificial teeth and implant-supported titanium CAD-CAM structures on fracture resistance. J Clin Exp Dent. 2016;8:e113-e118.
5. Özkurt-Kayahan Z. Monolithic zirconia: a review of the literature. Biomed Res. 2016;27:1427-1436.
6. Yamashita I, Machida Y, Yamauchi S. Highly translucent, high strength zirconia ceramics with nano-sized tetragonal domain. In: Bansal NP, Castro RHR, Jenkins M, et al, eds. Processing, Properties, and Design of Advanced Ceramics and Composites II: Ceramic Transactions, Volume 261. Westerville, OH: The American Ceramic Society; 2018.

Mr. Rensburg is the owner and head of the dental implant division at Absolute Dental Service in the Research Triangle of North Carolina. He graduated under full scholarship with a 4-year baccalaureate degree from Pretoria Technical College in 1992. He is certified with an ND in technology and specialized with an NHD in fixed prosthetics. He is a member of the prestigious Platform for Education, Exchange, Research and Sharing prosthodontic association and the Academy of Osseointegration (AO), is registered with the National Association of Dental Laboratories and North Carolina Dental Laboratory Association, and is certified by the South African Dental Technicians Council. He has specialized in fixed dental prosthetics with an emphasis on dental implants since the early 1990s. He can be reached at absolutedentallab.com or at conrad@absolutedentalservices.com.

Disclosure: Mr. Rensburg is an accredited speaker for Dentsply Sirona Prosthetics, Dentsply Sirona Implants, and the Argen Corporation.

Screw Retained: The Future of Implant Dentistry

Smile Design: A Modern Approach

Future Trends in Implant Dentistry

“It’s all about communication.”

Sound familiar?

The Merriam-Webster Dictionary describes communication as “a process by which information is exchanged between individuals through a common system of symbols, signs, or behavior.” Communication is a 2-way street. It involves a verbal exchange that includes speaking or writing and, importantly, listening. After the dentist writes on a prescription pad, it is then up to the dental laboratory team to understand exactly what the dentist wants. The clinician envisions how the restoration should look, then often communicates details verbally to the lab technician as well. The lab technician then interprets all the promulgated information and creates the restoration or prosthesis that he or she understands to be what the dentist and patient desire. To a large degree, the successful execution of this process depends on the clinical skill of the dentist, as well as the technical skill of the technician. And fundamental to success is the need for accurate communication between the doctor and the lab team. When such communication is optimized, it becomes collaboration. In the ever-expanding schema of digital dentistry, communication and collaboration both rely increasingly on another critical component: data.

Expectations vs Communication
Restorations are created to restore form and function and provide aesthetic outcomes that meet the needs and expectations for the dentist and the patient. By reliance on an aggregate of these components, the essence of communicating with a dental laboratory technician is for him or her to reproduce a restoration or prosthesis exactly to the specifications the restorative dentist requested, including tooth shape, size, and position within the dental arch; occlusal relationship; emergence profile; interproximal contacts; and incisal edge position.

Figure 1. Preoperative images of an existing maxillary prosthesis and mandibular dentition in need of restoration.	Figure 2. Pre-op CBCT image showing the frontal view of dental and osseous structures to be restored.

The aesthetic outcome is dependent on communicating color (chroma, hue, and value), translucency, and surface texture. The underlying challenge for the dentist is to determine all of these parameters accurately and then be able to successfully communicate the details and expectations for the patient case. The challenge for the lab team is to then understand exactly what the dentist is asking for and successfully implement the information received in the restorative product.

In the traditional way of doing things, the dentist will provide the lab technician with a written prescription describing what is expected. Of course, the detailed prescription needs to be accompanied by impressions, diagnostic casts, a bite registration, face-bow records, and clinical photos.

Doctor-Technician Communication
The digital approach now has the ability to optimize what, and how, relevant clinical information (STL files, DICOM files, digital photos, and/or videos) gets to the lab team and how the instructions and directions for restorative fabrication take place.

A substantial body of literature has been published on individual aspects of digital workflows in the prosthetically driven implant placement clinical setting, including several recent systematic reviews.^1-4 In general, these reviews report an overall time reduction in providing multi-unit prostheses. Joda et al4 state the need for more studies focusing on patient-reported outcome measures in this area. Abduo and Elseyoufi3 reviewed studies that included 12 intraoral scanning systems and identified considerable variability among them. They caution that intraoral scanners are vulnerable to inaccuracies, especially in long-span scanning applications.³ An in vitro comparative study by Amin et al⁵ identified a superior accuracy of digital impressions using intraoral scanners compared to conventional impressions for full-arch prostheses. Literature addressing the advantages of all aggregate facets of a digital workflow are scarce; the author published an initial report on the initial promise of digital dentistry in 2016.⁶

In a digital workflow, communication between the doctor and the lab team becomes much more transparent, accessible, and collaborative to both individuals. Table 1 presents contrasting steps between conventional and digital workflows.

Digital Workflow
• Diagnostic digital wax-up:

Using a laser introral scanner (eg, TRIOS [3Shape]), the dentist will send scans of the existing dentition to be restored to the lab technician who then creates the proposed restorations in the virtual 3-D model using dental design software. The dentist then views the design remotely and has an exchange with the technician about any aspects of the design. It can then be improved or modified, and the process continues until both are satisfied with the results.

• Cone-beam computed tomography (CBCT):

Central to the theme of digital dentistry is the capability for 3-D imaging afforded by CBCT scanning. Such scans provide the core of data accessible to every other virtual modality of treatment planning. Although there are some software incompatibility issues, CBCT scans form the basis for accurate digital implant placement and restoration.

Figure 3. Scan image showing the mandibular anterior ridge after virtual extraction of teeth Nos. 20, 21, 23, 24, 25, 26, and 28; the virtual augmentation of the mandibular anterior ridge; and prepared teeth Nos. 22, 27, and 29.	Figure 4. Virtual view showing 6 implants supporting the provisional in occlusion with the existing maxillary prosthesis.
Figure 5. A digitally milled surgical guide (the first of 2) in place on the lower arch for initial placement of the distal-most implants in position Nos. 19 and 31.	Figure 6. Surgical guide in place on the lower arch after extraction of nonviable teeth (all except Nos. 22, 27, and 29) following the placement of implants in position Nos. 20, 23, 26, and 30.
Figure 7. Photos of the original dentition with individual provisionals and the full-arch provisional after the extraction of teeth Nos. 23, 24, 25, 26, and 28.	Figure 8. Panoramic radiograph, showing 6 implants in place prior to the initial round of the extraction of teeth (Nos. 24, 25, 26, and 29).
Figure 9. Panoramic radiograph, showing 6 implants in place prior to fabrication of the PMMA provisional.	Figure 10. Virtual comparison showing the angle of implants relative to screw-access holes of the planned provisional.
Figure 11. PMMA provisional in place immediately after the final extractions of teeth Nos. 22 and 27. Data from scans of the provisional were shared with the laboratory for the milling of the final prosthesis.	Figure 12. The final milled All-on-6, screw-retained zirconia prosthesis.

In the case of smile design, the digital wax-up can be printed or milled using a variety of materials and sent to the dentist to be further reviewed and, if desired, tried in the patient’s mouth. Provisionals can then be fabricated from the approved design. This works extremely well in the case of full-mouth reconstruction. The patient will wear the provisional restoration for an appropriate amount of time. When all form, function, and aesthetic parameters have been addressed, the provisional result can be scanned in the patient’s mouth, and then the definitive restoration can be copied exactly from that provisional. We have followed this process in our practice for a number of years with numerous cases and consistently find that only minimal adjustments are necessary at the final seating appointment.

Summary of General Steps in a Digital Workflow

• Obtain a preoperative CBCT and intraoral scans of the patient
• Print or mill the approved proposal
• Insert
• Scan and copy
• Fabricate the definitive restoration

Digital Orthodontics
Orthodontists and restorative dentists can treatment plan using a variety of software platforms. These include Invisalign (Align Technology), SureSmile (Dentsply Sirona), and Reveal Clear Aligners (Henry Schein), just to name a few. These software technologies allow the dentist to send photos, radiographs, CBCT and intraoral scans, and other digital files in an electronic prescription with specific instructions. Proposed tooth and root movements are again made available for the clinician to modify, if needed, and approve. For fixed orthodontics, wires can be pre-bent robotically by the lab team and, in the case of aligners, they are all fabricated from the digital design.

Digital imaging of the airway can also provide diagnostic information on potential sleep-related breathing disorders.

Challenges
Going digital doesn’t simply mean “buying a scanner.” Rather, it involves adopting new workflows, and this requires a commitment from the dentist, as well as the entire team, in order to obtain a level of mastery that, in turn, creates consistency, reliability, and clinical accuracy. Proper technique and proficiency with the equipment are necessary to reliably scan and relay the resulting digital files to the lab team.

As is frequently the case with medical imaging software, compatibility issues can pose obstacles to the digital workflow. Each manufacturer uses some proprietary file format that may or may not require the lab to have the same licenses to view and work with those files. While there is some interoperability between different scanners and the design software in the laboratory (eg, 3Shape and exocad Dental CAD), challenges persist in sharing designs across different platforms.

Solutions
Digitally communicated workflows have become ubiquitous in implant planning for restoratively driven implant placement. The sharing of STL and DICOM files on a variety of platforms, such as Dropbox, has improved clinical outcomes in many ways. It has led to successful communication not only between the dentist and the lab team, but also between the lab team that fabricates the surgical guides, the clinician who places the implants, and the dentist responsible for placing the restorations. For example, DDx Solution (Henry Schein) allows for the exchange of lab data from Dentrix to the lab team. Other manufacturers’ platforms, such as Planmeca Romexis, Dentsply Sirona Connect, NobelGuide, or Straumann DTX, enable more-seamless communication.

For case discussions, dentists and their lab teams can collaborate with widely used communication software such as Zoom, GoToMeeting, LogMeIn, and others. Group interface software, such as TeamViewer, can also optimize digital collaboration among restorative and specialty clinicians by allowing them to view the files and screens of all collaborators.

CASE REPORT
Diagnosis and Treatment Planning
A healthy 57-year-old man with no significant medical conditions, no known drug allergies, and taking no medications presented for a full rehabilitation of his mandibular arch. He had recently undergone an immediate-load, full-arch, maxillary rehabilitation and wanted to have a similar treatment on his lower arch. A traditional all-on case would have required significant alveolar bone reduction, which would have limited the overall A-P spread of the implants or reduced the implant sizes. The patient did not want to wear an interim removable prosthesis, so the decision was made to stage the case with a transitional fixed bridge on 3 existing teeth as abutments while the implants fully integrated.

Clinical Protocol
Implants were placed in the mandible and prepared to support a transitional provisional fixed prosthesis that enabled the patient to avoid a removable provisional prosthesis. The preparation and planning allowed for an efficient appointment in which the extraction of the anterior teeth, the guided placement of all 6 implants in one appointment, and the insertion of the fixed provisional took place in an uneventful workflow.

Figure 1 shows a pre-op scan image of the mandibular dentition in occlusion with the existing maxillary prosthesis to digitally capture the vertical dimension of occlusion. Figure 2 shows a frontal CBCT image of hopeless anterior teeth resulting from pronounced osseous defects. Figure 3 shows a virtual image produced from a scan of the remaining mandibular dentition after the virtual extraction of mandibular incisors and premolars, with teeth Nos. 22, 27, and 29 prepared to support the virtually milled provisional.

A computer rendering of the proposed prosthesis in occlusion with the existing maxillary prosthesis, consistent with restorative-driven implant treatment planning, is shown in Figure 4.

Next, the workflow used the first of 2 digitally milled surgical guides to place the first 2 implants in position Nos. 19 and 31 (Figure 5). The second surgical guide (Figure 6) was then placed over implants in position Nos. 19 and 31 and prepared teeth Nos. 22, 27, and 29 after the extraction of teeth Nos. 20, 23, 24, 25, 26, and 28. The remaining 4 implants were then placed in position Nos. 20, 23, 26, and 30. None of the implants were loaded at the time of placement. All implants were placed using full facial and lingual flap reflection at the same appointment.

Next, the fixed provisional was placed using abutment Nos. 22, 27, and 29 (Figure 7). A panoramic radiograph showing 6 implants immediately after placement, and the 3 remaining abutment teeth to support the immediate fixed PMMA provisional, is pictured in Figure 8. Figure 9 shows a panoramic radiographic view of the provisional abutments attached to the implants immediately after the extraction of teeth Nos. 22, 27, and 29.

After 3 months of healing to allow for osseointegration, the 6 implants were uncovered, had scan bodies placed, and were scanned at the fixture/tissue level. Figure 10 shows virtual relative angulation of the screw access holes and implants. Teeth Nos. 22, 27, and 29 were virtually extracted, and a full-arch, mandibular, implant-supported provisional was fabricated. Next, teeth Nos. 22, 27, and 29 were extracted, and the screw-retained provisional was secured to the 6 implants (Figure 11). Time was allowed for tissue healing, and a definitive screw-retained, milled zirconia prosthesis was placed (Figure 12).

CLOSING COMMENTS
The case example above serves to demonstrate how complex implant restorative dentistry can be achieved. This treatment provided the patient with immediate function on existing teeth or? integrated implants in fewer appointments and with greater predictability using a digital workflow as compared to the risks and limitations associated with a traditional-load all-on case dentist-lab team exchange.

Acknowledgment:
The author extends his appreciation to Dr. Evan Chafetz, DMD, oral-maxillofacial surgeon, Scarsdale, NY, and Robert Schulman, DMD, prosthodontist, White Plains, NY.

References

1. Lo Russo L, Caradonna G, Biancardino M, et al. Digital versus conventional workflow for the fabrication of multiunit fixed prostheses: a systematic review and meta-analysis of vertical marginal fit in controlled in vitro studies. J Prosthet Dent. 2019;122:435-440.
2. Mühlemann S, Kraus RD, Hämmerle CHF, et al. Is the use of digital technologies for the fabrication of implant-supported reconstructions more efficient and/or more effective than conventional techniques: a systematic review. Clin Oral Implants Res. 2018;29(suppl 18):184-195.
3. Abduo J, Elseyoufi M. Accuracy of intraoral scanners: a systematic review of influencing factors. Eur J Prosthodont Restor Dent. 2018;26:101-121.
4. Joda T, Derksen W, Wittneben JG, et al. Static computer-aided implant surgery (s-CAIS) analysing patient-reported outcome measures (PROMs), economics and surgical complications: a systematic review. Clin Oral Implants Res. 2018;29(suppl 16):359-373.
5. Amin S, Weber HP, Finkelman M, et al. Digital vs. conventional full-arch implant impressions: a comparative study. Clin Oral Implants Res. 2017;28:1360-1367.
6. Kaye G. Restorative digital dentistry, part 1: the journey to new paradigms. Dent Today. 2016;35:22-27.

Dr. Kaye graduated from the Columbia University School of Dental Medicine, where he received awards in endodontics, prosthodontics, and geriatric dentistry. He has practiced comprehensive dentistry since 1993 and has built successful multispecialty group practices in and around New York. He is a graduate of the Dawson Academy of Comprehensive Dentistry and has published and lectured on ceramics, occlusion, and the adoption of digital dentistry. He consults with dentists, dental schools, and manufacturers on all aspects of digital dentistry. Dr. Kaye serves as the digital editor for Dentistry Today. He can be reached at drgarykaye@nycdd.org.

Disclosure: Dr. Kaye reports no disclosures.

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My Digital Dentistry Journey

INTRODUCTION
Dental implant therapy and clear aligner therapy occupy polar opposite ends of the dentistry spectrum. After all, implants treat edentulism and failing dentitions, while clear aligners treat the healthiest of mouths. Yet the same technological advances are revolutionizing both of these fields—2 of the currently fastest-growing clinical segments of the dental market with great future potential. This article series will utilize clinical case examples in the fields of both implantology and clear aligners to help paint the picture of where each of these fields will be in 24 months and to open the discussion on new and exciting opportunities now available for clinicians.

Both fields are experiencing enormous growth with huge potential for continued development. In fact, a recent article in Forbes states, “…Align Technology estimates there are 10 million orthodontic cases each year…the Invisalign product is applicable to 6 million of those, [and] they have only 9% of those cases. That leaves plenty of room for growth—especially when you find out they are creating these aligners on a fleet of 3D printers.”¹

The savvy clinician will anticipate where these fields are headed and position his or her services to reap success from the next revolution in clinical dentistry.

Current Clinical Climate of Implants and Aligners
Private equity, DSOs, and institutional investors have been increasingly focusing on both the implant and aligner markets in the last several years. Large implant centers have been adding more locations, and aligner therapy locations are going up by the dozens. Hundreds of millions of dollars have been spent to bring patient awareness in both the implant and aligner fields to all-time highs. At first glance, these developments may appear to be a negative to the private practitioner. Yet, incredible opportunity has been created for the private practitioner and the dentist-owned dental service organization (DDSO). This national marketing spend has created an unprecedented demand for both services, and this demand is at a level never before seen in the United States. Furthermore, add to this the reality that a patient would rather receive dental services in-house from his or her dentist of record. This means that patients are becoming aware of the benefits of implant and aligner therapy through mass marketing but, at least the majority of the time, are seeking those services with their home private dental practices. This trend is expected to continue, which opens a promising opportunity to put to use the clinical techniques explored in this series.

In-House 3-D Printing of Implant Guides and Aligner Models
Only a few years ago, it was not thought feasible for a clinician to efficiently and cost effectively print surgical implant guides and models for in-house aligner therapy. Clinicians who adopted in-house 3-D printing protocols early have positioned themselves to benefit the most from dentistry’s next big revolution. These clinicians are now producing guides and sets of aligners at a fraction of the retail cost of such appliances and have outsourced the majority of the workload to staff, creating very scalable growth. And, for clinicians yet to adopt these new technologies, there is still good news. Only recently have the printers and software for aligner therapy become efficient, user-friendly, and accurate enough to warrant the investment. At present, the minor investment to get into 3-D printing as a private practitioner creates multi-fold ROI possibilities. In fact, a recent article² described in great detail how a college student used software to plan his own case and 3-D printed 12 models, procured clear aligner material from eBay, and successfully treated his own case. While this enterprising student had no dental training or experience and, as a result, put himself at great risk, the example still serves to demonstrate the relative simplicity of this technology, and, indirectly, it highlights the dawn of the 3-D printing revolution that can be beneficial for both doctor and patient when implemented professionally and with proper training.

The following cases will give clinical nuggets and offer analysis of the economic benefit to the clinician and, in turn, the patient.

CASE REPORTS
Case 1: In-House 3-D Printed Aligner
Let’s look at a typical case (Figures 1 to 3, courtesy of Kevin Ison, DDS) that could be routinely seen in any dental practice. The patient presented with a Class I bite relationship with minor tooth movements necessary to achieve an ideal aesthetic result. This type of case is an ideal situation for scanning, 3-D printing, and providing completely in-house aligner therapy at a fraction of the cost of sending the case out to a retail aligner lab.

Case 2: In-House 3-D
Printed Implant Guide
Figures 4 to 13 (courtesy of Peter Stover, DDS) demonstrate the modern workflow of guided implant dentistry.

Guided implant surgery has evolved much like the rest of digital dentistry. We began with complex systems that required custom impressions with radiographic markers and milled guides that were very expensive and sometimes inaccurate. Software and hardware improvements have improved the workflow and reliability of guided surgery, but nothing has opened the platform of guided surgery like the advent of 3-D printing. Three-dimensional printers are now affordable, accessible, and reliable.

CLOSING COMMENTS
From these case studies and from trends in the marketplace, it is clear that the 3-D printing revolution, as it relates to implants and aligners, is well underway. Prudent clinicians will prepare themselves and their own private practices, DSOs, or DDSOs for the bell curve of demand that is estimated to peak in the next 2 to 3 years. Allow the heavy marketing budgets of “big dental” to help fill your practice full of fee-for-service patients from the advantageous clinical fields of implant and aligner therapy.

In the next article in Dentistry Today related to these technology-related topics, we will describe more clinical techniques and share tips that will allow the clinician to take action as the innovations in the 3-D printing arena intensify. Five steps to building your implant or aligner 3-D printing ecosystem in the most cost-effective path possible will also be presented. Keeping in mind that minor investments in equipment and supplies are producing big dividends and a reduced overhead percentage for up-to-date practices around the country, the next article will also include a detailed low-, medium-, and high-cost breakdown for scanners and information on 3-D printers, printer resin, software, post-processing boxes, thermoformers, and labor and packaging ideas to help begin your 3-D printing journey.

References

1. McCue TJ. 3D printing moves align technology toward $1.3 billion in sales. Forbes. September 14, 2017. https://www.forbes.com/sites/tjmccue/2017/09/14/3d-printing-moves-align-technology-toward-1-3-billion-in-sales/#224d62835378. Accessed December 1, 2019.
2. MacDonald F. A college student has 3D-printed his own braces for less than $60. Science Alert. March 21, 2016. https://www.sciencealert.com/a-college-student-has-3d-printed-his-own-braces-for-less-than-60. Accessed December 1, 2019.

Dr. Frank is an international clinical and business lecturer, an inventor, and founder of multiple companies in the dental and real estate development spaces. Since graduating from Marquette University School of Dentistry in 2001, he has been the founder and co-owner of multiple private dentist-owned groups. He can be reached at bradyfrank74@gmail.com or at ddsolive.com and ddsostrategies.com.

Dr. Ison operates a multi-location DDSO in Ohio, Missouri, and Arizona. A board-certified orthodontist, Dr. Ison enjoys mentoring both his colleagues and partners in efficient clear aligner therapy and opening a 3-D printing center of their own. He is the clinical director of the DDS Aligner Institute with training locations throughout the nation. He can be reached via email at ison3@hotmail.com.

Dr. Stover is a 2002 graduate with honors of the University of Oklahoma College of Dentistry (OUCOD). He is a CEREC trainer for Patterson Dental and beta tester for Clear Correct digital workflow. He has lectured on topics around the CEREC Guide 2.0 implant protocol throughout the Midwest, conducted live webinar education series for Blue Sky Bio implant integration with Sirona, and lectured on 3-D printing for Patterson Dental. Additionally, he has hosted study clubs at OUCOD for printing surgical guides and restoring implants and beta tested products for Blue Sky Bio. Dr. Stover operates both pilotplusdental.com and premier3dlab.com with the goal of helping to simplify surgery with more predictable outcomes. He can be reached at petestoverdds@gmail.com.

Dr. Anderson, a graduate of the University of Minnesota School of Dentistry, is a general dentist in private practice in the Twin Cities. He is the owner of 5 independent offices. He thrives on mentoring associates and catapulting their experience, both clinically and from an owner’s perspective, thus creating excellent partners. He trains other dentists on the art of 3-D printing aligners. Dr. Anderson can be reached at drtmanderson@gmail.com or by calling (651) 353-6651.

Disclosure: The authors have a financial interest in some of the products mentioned but received no compensation for writing this article.

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Digital dentistry encompasses a wide world of convenience and new treatment options for clinicians and patients alike. With new tools—such as in-office milling systems and intraoral scanners—at our disposal, we have the ability to offer patients high-quality treatments in a fraction of the time compared to traditional methods. In many cases, this can be the key to a successful outcome for the patient.

As digital techniques have become more widespread in the industry, clinicians are continually finding new cases that are ideally treated with the use of these advanced tools. The fact that digital methods allow us to provide patients with the same high-quality restorations that they would get via traditional lab-fabrication methods in a minimal amount of time makes this type of treatment the ideal solution for patients in need of immediate and convenient services.

The case below is a prime example of one in which digital treatment was not only the preferred treatment, it was the recommended course of action.

Figure 1. Preoperative view of the patient’s condition as presented. Recurrent decay and a fracture had led to the failure of the existing composite resin restoration on tooth No. 30, which had, in turn, compromised the distofacial and distolingual cusps surrounding it. The patient desired a long-lasting replacement that would be strong enough to withstand the occlusal demand caused by his occasional bruxing.

CASE REPORT
Diagnosis and Treatment Planning
A male patient in his 50s presented with good periodontal health and a history that included a few previously placed restorations and bruxism. His job was in the transportation industry, so he was constantly on the road performing demanding tasks. For this patient, time was of the essence as his schedule was not really conducive to numerous dental visits. Upon examination, it was discovered that he had a failed composite resin restoration on tooth No. 30. Recurrent decay and a fracture in the current restoration had led to the failure of the restoration; the resultant damaged tooth structure was large enough that the distofacial and distolingual cusps were compromised (Figure 1). Per the patient, this was the third time this particular restoration had required replacement. It was time to explore some other options that could lead to a more favorable outcome.

The patient was offered the following treatment options:
1. Replace the failing composite resin restoration with another direct composite restoration. The downside of this type of approach would be the expected relatively lower longevity of the restoration as compared to other restorative material options. Per the patient’s own history, this type of simple direct restoration had already failed him twice in the past, so, consequently, this was not his first choice.
2. The affected portion of the tooth could be replaced with a partial coverage restoration. Although this is an option used frequently in our office, his bruxing habit would not be beneficial to the longevity of this restoration.
3. Replace the restoration with a full-coverage monolithic crown. Due to the location, occlusal stresses, and his bruxing habit, it was decided that this would be a beneficial option for the patient.

The patient appreciated my assessment and chose to move forward with a full-coverage, monolithic restoration. In his words, he wanted a long-lasting restoration that he “would not have to worry about” for some time to come. In addition, he wanted it completed in as timely a manner as possible.

In terms of selecting a full-coverage restoration, it is my opinion that the newer monolithic material options are an ideal combination of aesthetics and strength for situations such as this one. In particular, the occlusal demands of this patient’s case made it ideally suited to the use of a BruxZir NOW (Glidewell Laboratories) solid zirconia restoration. The recent adoption of the glidewell.io In-Office Solution (Glidewell Laboratories) in our office has made it possible for us to offer our patients BruxZir restorations in a single visit. With glidewell.io, we are able to design, mill, and deliver fully sintered zirconia crowns within an hour, allowing our patients to receive the same high-quality restorations they would receive from the dental laboratory without the need for a second visit. In this case, with the limitations on the patient’s schedule as well as his need for a strong restoration due to bruxism, creating a BruxZir restoration and delivering it within the same appointment was the ideal solution.

Clinical Protocol
To begin the process, the patient was given anesthesia, and the failed composite resin restoration was removed along with all recurrent caries. A build-up (Filtek Supreme Bulk Fill [3M]) was placed to replace the void left by the previous restoration and caries. The built-up tooth was then prepped according to the recommended guidelines for BruxZir restorations (Figures 2 and 3).

Figure 3. The prep design includes drafted sides, smooth surfaces, a chamfer margin, and axial and occlusal reductions of 1.5 mm.	Figure 4. Once the intraoral scan is completed, the iTero Element 2 Scanner (Align Technology) automatically transfers the data to the fastdesign.io Software (Glidewell Laboratories), which presents the clinician with an automated crown proposal based on data from millions of past cases on file at Glidewell Laboratories. Created with artificial intelligence algorithms, these automated proposals typically require little adjustment, but the clinician is free to revise the proposal as he or she sees fit. In this case, minor adjustments were made to the margin of the restoration to ensure it met the parameters that would provide the best fit.
Figure 5. Other tools provided in fast-design.io allow the clinician to adjust the contacts of the proposed restoration. In this case, adjustment was not necessary, and the automatically generated contacts were simply confirmed before finalizing the crown design.	Figure 6. Occlusal view of the finalized restoration proposal, which was examined from all angles prior to milling. I was pleased with the preview provided and felt assured that the final milled restoration would be successful.
Figure 7. Buccal view of the proposed restoration in place. This side view provided by the fastdesign.io Software was useful in determining that the contacts of the crown were properly set and would meet the patient’s occlusal requirements.	Figure 8. Prior to sending the crown proposal to the fastmill.io In-Office Mill (Glidewell Laboratories) for milling, its placement on the milling sprue was confirmed via the preview provided in fastdesign.io.

Following preparation and retraction (achieved with a No. 1 braided cord with a hemostatic agent), the preparation, the working quadrant, and the opposing quadrant were scanned using the iTero Element 2 intraoral scanner (Align Technology). The prescription for the restoration was filled on the scanner and sent directly to the fastdesign.io Software and Design Station (Glidewell Laboratories) (Figures 4 to 7). Within a matter of minutes, the restoration was received and processed by the design software. Creating the proposal design itself was as simple as marking the margins, accepting the proposal generated by the software, and sending the completed proposal to the fastmill.io In-Office Mill (Glidewell Laboratories) for in-office milling.

Prior to sending the crown proposal to the fastmill.io for milling, its placement on the milling sprue was verified via the preview provided in fastdesign.io. (Figure 8).

To complete the milling process, the appropriate milling block (in this case, an A2 BruxZir NOW block) was selected and placed into the mill. The milling process was started and completed within 38 minutes. Following the milling process, the restoration was detached from the mandrel. While polishing is not required for BruxZir NOW restorations, it was decided that, for this restoration, it would help ensure a better match to the patient’s existing dentition. The author prefers the ASAP+ Indirect Polishers (CLINICIAN’S CHOICE Dental Products) because a high luster polish can be easily achieved within a matter of minutes (Figure 9).

Delivery of the completed restoration was the final step. Cementation is a matter of preference and a matter of the retentiveness of the prep. If the prep is retentive (< 5° to 6° of taper and with 3.0 to 4.0 mm of axial wall height), a resin-modified glass ionomer cement may be used. If the prep is not deemed retentive, the use of a resin cement is advised to aid in a higher bond strength. Regardless, all chairside fabricated (in-office) zirconia restorations should be air abraded on their intaglio surfaces (25 to 50 µm aluminum oxide at 1.5 to 2 bar). (Note: For lab-fabricated restorations, this step is done in the dental lab prior to delivery to the dental office and need not be repeated at the chair.) The use of a universal primer (such as Monobond Plus [Ivoclar Vivadent]) or zirconia primer (such as Z-Prime Plus [BISCO Dental Products]) is beneficial when luting zirconia restorations with a resin cement. In this case, the restoration was abraded with 50 µm aluminum oxide at approximately 2 bar, Monobond Plus was used to prime the intaglio surface, and then the restoration was seated using a self-adhesive resin cement (RelyX Unicem 2 [3M]) (Figure 10).

An evaluation of the fit, occlusion, and aesthetics was done. The patient was very happy that he was able to leave the office with a completed restoration in place and that no follow-up appointments would be required. It was a great feeling to have been able to provide this patient with the same high-quality restoration that he would have received with a traditional lab-fabricated technique in a fraction of the time and with the help of the latest digital dentistry tools.

CLOSING COMMENTS
Digital technologies are proving to be a tremendous asset to our profession. The explosive growth of the various technologies being introduced and implemented in dentistry has also made treatment more predictable and consistent. In turn, the attributes allow us, as clinicians, to provide quality care in an efficient manner. The results satisfy the needs of our most demanding patients.

Dr. Duplantis is a graduate of the University of Texas Health Science Center at San Antonio School of Dentistry. He is also a Fellow in the AGD. He serves as a key opinion leader for Glidewell Laboratories and various other dental manufacturers. In addition, he is a member of the Catapult Education Speaker’s Bureau. He has written several articles regarding digital dentistry, restorative implant dentistry, and cementation and bonding. Dr. Duplantis maintains a private practice in Fort Worth, Texas, and lectures internationally on various topics pertaining to clinical dentistry. He can be reached at drduplantis@gmail.com.

Disclosure: Dr. Duplantis is a key opinion leader for Glidewell Laboratories and CLINICIAN’S CHOICE. No honorarium was received for this article.

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