INTRODUCTION
The incorporation of digital technology into the dental practice continues to allow the clinician to provide better and more consistent results. The inclusion of digital impression scanning into the office can greatly enhance the predictability of the final restorations given the increased accuracy that it provides.
Many dentists have embraced digital impressions and laboratory data as well, as scanner sales show that there is an increased number of dentists incorporating digital impressions into their office workflow. In many practices, the bulk of the work completed with a digital impression scanner is one or 2 posterior restorations. However, the current technology available with digital impression scanners allows for the inclusion of much more complex cases. It also has the advantage of allowing the dentist to share the patient’s preoperative condition with the ceramist. Then, working together virtually, the dentist and ceramist can create the template (ie, virtual wax-up) to collaborate in developing the final vision of the case. This ability to communicate and collaborate is best demonstrated in cosmetic cases in which not only do the dentist and ceramist need to work together, yet the patient’s input also needs to be taken into consideration.
The following case study demonstrates the essential communication required among all parties to create a treatment outcome that meets everyone’s expectations.
CASE REPORT
Diagnosis and Treatment Planning
A 30-year-old female with a 10-year history of trauma to teeth Nos. 7 to 9 presented for an aesthetic consultation. After the traumatic incident occurred, she had Nos. 7 to 9 treated with root canal therapy (RCT) and PFM full-coverage crowns. Upon presenting to our office, her chief complaint was that she was not happy with the aesthetics of the crowns, and also stated that she was displeased with the appearance of her natural teeth (Figure 1). She said that she has tried several times to whiten her natural teeth using over-the-counter products as well as dentist-administered bleaching materials. Upon further discussion, she also recognized that the lengths of her front teeth were different.
From the clinical and radiographic examinations, it was noted that the RCT that was previously performed was clinically acceptable. Her periodontal findings were within normal limits. The margins of the crowns were intact, but minor staining was present. Aesthetically, the existing PFM crowns did not match her natural teeth. The unrestored natural dentition was a shade A2, and extensive areas of hypocalcification were present. Additionally, there was a notable gingival asymmetry between teeth Nos. 7 and 8 and Nos. 9 and 10. The patient’s high lip-line helped to make this discrepancy even more obvious.
Several treatment options were presented. After a thorough discussion, the patient chose to have an aesthetic restoration that would include all-ceramic, full-coverage crowns to replace all the existing anterior PFM restorations along with porcelain veneers on teeth Nos. 5 and 6, and teeth Nos. 10 to 12. For optimal aesthetics, laser soft-tissue recontouring was also recommended and accepted.
Photographs and digital impressions (CS 3500 [Carestream Dental]) were taken of the patient. This information was then sent electronically to the ceramist (Yes Dental Lab; Tarrytown, NY). In the lab, the ceramist was then able to generate a digital wax-up (Figure 2) of the patient’s case. When the ceramist created this virtual wax-up, he utilized information provided from our chairside discussion with the patient on issues related to her smile design.
The digital wax-up was then printed into a physical model. This model was sent back to our dental office and was used to make a preparation guide and also to fabricate a vinyl polysiloxane (VPS) (Panasil Putty Fast Set [Kettenbach LP]) template for the provisional restorations. The printed model was also used as a communication tool with the patient to demonstrate a physical 3-D interpretation of her aesthetic requests according to what we had previously discussed. This review of the printed model of the digital wax-up helped to ensure that the patient’s aesthetic goals would be met with the final restorations.
Preparation Appointment
At the preparation appointment, the patient was anesthetized. The 2% lidocaine (1:100,000 epi) was buffered (Anutra Medical). The fast and profound onset of the anesthetic allowed for preparation to begin in less than 2 minutes. First using a diode laser (Picasso [AMD LASERS]), the soft-tissue margins of teeth Nos. 7 and 8 were altered to be more symmetrical to teeth Nos. 9 and 10. Care was used to not violate the biological width.
Next, the existing PFM crowns were removed. Upon removal, several small areas of recurrent caries were noted at the margins and removed with a No. 2 slow-speed round bur. All the areas were then checked with a caries detector (Sable Seek [Ultradent Products]) to ensure that all decay was eliminated. Next, an adhesive (Futurabond U [VOCO America]) was applied and a flowable composite (Admira Flow [VOCO America]) was used to fill in these small areas of missing tooth structure. The final crown preparations were completed using medium-grit and fine-grit diamonds.
Following that, teeth Nos. 5, 6, and 10 to 12 were prepared for porcelain veneers. Using a 0.5-mm depth-cutting diamond (No. LVS3 [Brasseler USA]), the minimal amount of facial tooth structure to be removed was outlined. Then a fine chamfer diamond bur (No. 828-026 [Kerr Endodontics]) was used to remove the remaining facial tooth structure as required for the fabrication of the final veneers.
After the lab team received the photographs and the digital pre-op impressions, a discussion took place to decide on the porcelain material to be used. It was agreed that, to provide the optimal aesthetic and functional results desired, a lithium disilicate all-ceramic material (IPS e.max [Ivoclar Vivadent]) would be used for all the restorations in this case. The final preparations were created to fit the parameters of use for this material.
Upon completion of the preparations, the soft tissue was retracted using a size 00 retraction cord (Ultrapak [Ultradent Products]). Areas of tissue irritation that continued to bleed were treated with a combination of diode laser (Picasso) cauterization and use of a retraction paste (Traxodent [Premier Dental Products]) (Figure 3).
Once the bleeding and soft tissue were properly managed, the final impression was scanned using a digital impression scanning system (CS 3500). The final impression was reviewed (Figure 4) and electronically delivered to the laboratory.
The benefits of digital scanning are multifaceted. It is a more comfortable procedure for patients than traditional impression techniques. Digital impressions allow for the practitioner to stop if the patient needs a rest; or if there is an area of contamination on the prepared teeth, these areas can be cleaned up mid-impression and the scanning continued. When the scan is completed, the doctor can then view the digital impression in detail on a 17” monitor, and any defect or inaccuracy in the impression can be rescanned. The potential now exists for the creation of a perfect impression in every patient case. Digital impressions can be sent electronically to the lab team immediately. If needed, the lab team can provide input on the impression and any alterations made. This quick transmission of the digital impression allows the turnaround time to be reduced in many cases. Lastly, the accuracy of digital impressions has consistently been demonstrated to be better than physical impressions made using traditional impression materials, leading to a potentially better fit of the final restorations.
A VPS putty matrix (Panasil Putty Fast Set) (made from the model of the digital wax-up as described earlier) was used to fabricate the provisional restorations. Each of the teeth with veneer preparations were acid etched (Select HV Etch [BISCO Dental Products]) in a small area (dot) at the center of the tooth. Then, the etchant was rinsed thoroughly with water after 30 seconds. All the prepared teeth were then air-dried. The VPS matrix was loaded with a bleach shade of a bis-acryl temporary material (Luxatemp Ultra [DMG America]) and seated fully into place. After 4 minutes, the provisional matrix was removed and excess temporary material was removed using a sickle scaler. Fine finishing was accomplished with several shapes of carbide finishing burs (Composite Finishing Kit [Brasseler USA]) and a No. 12 scalpel blade. The occlusion was then refined, and the entire 8-unit temporary splint restoration was polished using a composite polishing paste (Couture Diamond Polishing Paste [Centrix]). The postoperative instructions were given, and the patient was scheduled to return in 2 weeks.
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| Figure 1. Our patient’s preoperative smile, including 10-year-old PFM crowns. | Figure 2. A digital wax-up was created from a digital scan of the patient’s existing dentition. |
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| Figure 3. The final preparations were ready to scan for the final digital impression (CS 3500 [Carestream Dental]). | Figure 4. The final digital scan was reviewed on a 17” monitor and, once approved, submitted electronically to the dental laboratory team (Yes Dental Lab; Tarrytown, NY). |
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| Figure 5. A printed model was created from the digital scan to assist in the final fabrication of the lithium disilicate restorations (IPS e.max [Ivoclar Vivadent]). | Figure 6. The final strong (500 MPa) and highly aesthetic IPS e.max restorations were ready for try-in. |
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| Figure 7. At the one-week post-op visit, a highly aesthetic result was observed. The patient was very pleased with her new smile. |
Dental Laboratory Work Completed
In the dental lab, the digital scan was then used to design the final restorations based on the virtual wax-up. Any minor changes, as noted by the clinician in the written prescription, were observed and followed. A printed model of the digital impression was created (Figure 5) for the final fit and finish of the 8 strong (500 MPa) and highly aesthetic IPS e.max restorations (Figure 6).
Delivery of the Final Restorations
At the delivery appointment, buffered 2% lidocaine local anesthetic (Anutra Medical) was administered. The temporary restorations were then removed using a sickle scaler and the preparations were cleaned using a slurry of plain pumice and distilled water.
Then, the restorations were tried-in using a translucent try-in paste (Vitique [DMG America]). The restorations were evaluated for fit, function, and aesthetics. The patient was given the opportunity to evaluate the aesthetics, and we proceeded only after she gave her approval.
The restorations were prepared for delivery using a universal cleaning gel (Ivoclean [Ivoclar Vivadent]) and silane (Vitique Silane [DMG America]) was applied to the intaglio surfaces of all the restorations per manufacturer recommendation. The arch was isolated using orthodontic retractors. The veneers were placed using a translucent light-cured resin cement (Vitique), and the crowns were resin bonded using a translucent dual-cured resin cement (Vitique). After final curing, any remaining excess cement was carefully removed, the occlusion was evaluated and refined, and the porcelain (and any areas where adjustments had been done) was properly polished. At the one-week post-op visit, an excellent final aesthetic outcome was observed and the patient was very satisfied with her new smile (Figure 7).
CLOSING COMMENTS
Digital scanning technology has demonstrated the ability to enhance, improve, and increase consistency and predictability when delivering aesthetic dentistry. Using the scanner to improve communication with the dental lab team preoperatively via the creation of a digital wax-up allows the dentist and the ceramist to work closer together in the design process. The use of the scanner for the final impression provides the lab team with a more accurate model, resulting in final restorations that have an excellent marginal fit and contacts. The combination of digital scanning with milled lithium disilicate leads to the creation of durable and highly aesthetic final restorations that accurately match the predetermined case design.
Acknowledgment
The author would like to recognize the artistic talents of the laboratory team at Yes Dental Lab (Tarrytown, NY) for the ceramic artistry presented in this case.
Dr. Radz maintains a private practice in Denver. He maintains a faculty position at the University of Colorado School of Dental Medicine. He is a founding member of Catapult Education and the director of industry relations for SmileSource. He can be reached via email at radzdds@aol.com.
Disclosure: Dr. Radz is a paid consultant for Carestream Dental and DMG America.
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