INTRODUCTION
CAD/CAM technology for digital scanning and manufacturing is no longer a novelty in dentistry. For more than 30 years, dentists have had access to intraoral scanning devices and the ability to manufacture monolithic restorations in the dental office. Until recently, the main role of intraoral scanners was to image single teeth, or a limited group of teeth, with the intent of designing and manufacturing same-day restorations. Intraoral scanners were used solely as “digital impression materials,” and the associated digital files were not commonly used for any other purpose.
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.
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| 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.
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| 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.
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| Figure 3. Initial presentation with failing and discolored laminate veneers. |
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| Figure 4. Portrait photos required for digital smile design. |
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| 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.
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| 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. |
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| 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. |
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| 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.
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| 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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