INTRODUCTION
Restorative dental emergencies present challenges when they occur. When a patient comes in with a failing crown, traditionally, this would require a 2-visit treatment with preparation of the tooth for a new crown at the first appointment and insertion of a lab-fabricated restoration at a later appointment. This poses issues for both the patient and the dentist by requiring multiple appointments. Advances in technology that include intraoral scanning to replace physical impressions, virtual planning and design of the restoration, and 3D printing all permit treatment that results in more efficient dental care, allowing it to be completed in a single appointment. Below is a case study discussing a patient presenting on an emergency appointment with completion of treatment in a single appointment.
Case Presentation
A 78-year-old male patient indicated a crown had fallen out on his upper left posterior and requested the crown be “recemented.” The examination noted the crown on the maxillary left first premolar was missing intraorally. The tooth was level with the gingiva, gutta-percha was noted on the remaining tooth occlusally, and the old crown contained core material with no post noted in the tooth (Figures 1 and 2). Ferrule was minimal, and reinsertion of the old crown was questionable due to poor stability to the remaining tooth structure. A radiograph was taken, and prior endodontic treatment was confirmed. A 3D CBCT scan helped to rule out the presence of periapical pathology prior to treatment (Figure 3). It was noted that insufficient tooth structure was present supracrestally, with a lack of ferrule to retain a new crown. The patient was informed of the clinical findings and the recommended crown lengthening with Solea CO2 laser (Convergent Dental), followed by placement of a core buildup and preparation for a new crown. He was informed that treatment could be completed at the current appointment utilizing advanced technology and he would be able to leave with the final crown fabricated utilizing 3D printing. The patient agreed to the treatment recommendations and treatment was initiated.
Figure 1. Buccal view of the clinical appearance of the previously restored, endodontically treated, maxillary first premo- lar demonstrating a lack of ferrule and an absence of a restorative post to retain the core buildup.
Figure 2. Occlusal view of the clinical appearance of the previously restored endodontically treated maxillary first premolar demonstrating a lack of ferrule and an absence of a restorative post to retain the core buildup.
Figure 3. A bite-wing radiograph is shown as the patient presented with an old crown off the previously endodontically treated maxillary first premolar.
The old crown was inserted intraorally, and a biocopy scan was performed with a CEREC Primescan intraoral scanner (Dentsply Sirona) (Figure 4). This was performed to aid in the virtual design of the new crown and shorten the design process. An intraoral scan was also performed of the untreated tooth without the old crown present intraorally (Figure 5). The images were acquired with CEREC SW 5.9 software (Dentsply Sirona).
Figure 4. A biocopy scan of the failed crown manually approximated to guide the new crown design on the maxillary first premolar.
Figure 5. Intraoral scan of the quadrant as the patient presented for treatment.
Local anesthetic was administered prior to treatment in order to complete laser crown lengthening. Soft and hard tissue was ablated circumferentially with the Solea laser until approximately 2.5 mm of tooth structure was exposed supracrestally. The tooth was prepared, but a portion of the obturation material was removed to a depth of 4 mm to extend the planned core into the tooth and improve core retention to the remaining tooth. Prior to bonding protocol, the low power setting on the Solea laser was used to decontaminate dentin and microetch the dentin surface to a matte finish for enhanced bonding. The tooth was rinsed and air dried. A total-etch adhesive was applied to all tooth surfaces and light cured. A dual-cure resin core material was injected into the prepared area of the root and over the tooth to a sufficient height for the planned core and then light cured. The tooth was then prepared for a new crown, which achieved a circumferential ferrule on the tooth. A new scan of the reprepared tooth was performed utilizing the CEREC Primescan intraoral scanner and imported into the CEREC SW 5.9 software (Figure 6). The scan of the opposing arch was articulated with the new upper scan in the software to verify sufficient space occlusally for the planned restorative material (Figure 7).
Figure 6. Intraoral scan following placement of the core buildup clinically.
Figure 7. Virtual image of the occluded arches following placement of the core buildup clinically.
Using the design software, the biocopy catalog containing the old crown image was superimposed on the scan of the prepared tooth with the new core to serve as a reference when designing the anatomy of the restoration (Figure 8). The translucency of the virtual crown was altered to visualize the underlying core buildup (Figure 9). The design of the planned crown was completed and was ready to 3D print. (Figure 10).
Figure 8. The crown has been virtually designed in the software.
Figure 9. A virtual design of the crown in relation to the underlying post and core.
Figure 10. A virtual image of the designed crown on the occluded arches.
The 3D printing was performed on the SprintRay Pro S 3D printer with Crown kit (SprintRay) utilizing Ceramic Crown Resin (SprintRay) in shade A2 (Figure 11). Upon completion of printing, the crown was removed from the build plate and the support legs were removed with a diamond in a high-speed handpiece. The crown was cleaned with a dry microbrush and paper towel to remove any remaining uncured resin. A 91% IPA alcohol wash was used, per SprintRay’s recommended protocol. The crown was then placed into the NanoCure unit (SprintRay) for post-curing of the printed restoration, which took approximately 3 minutes.
Figure 11. The 3D printed crown utilizing Ceramic Crown Resin (SprintRay) in shade A2 on the build plate following printing.
The intaglio of the crown was lightly sand blasted with aluminum oxide to enhance bonding. The ceramic resin crown was then polished with Dialite medium and fine ceramic polishers (Brasseler USA). OPTIGLAZE (GC America) was then applied to the exterior of the ceramic crown with a disposable glazing brush to create a smooth, shiny surface, then light cured to complete the restoration (Figure 12).
Figure 12. The final 3D printed crown utilizing Ceramic Crown Resin in shade A2 following removal of the support legs and polishing.
The restoration was taken to the patient in the operatory and tried in to verify fit and occlusion. Adhese (Ivoclar) was applied to the intaglio surface of the ceramic resin crown and allowed to sit for one minute. The intaglio of the ceramic resin crown was then air dried in preparation for cementation. Etching gel was applied to the tooth for 30 seconds, then rinsed and air dried. Adhese was also applied to the etched tooth preparation. A dual-cure resin cement, Variolink Esthetic DC (Ivoclar), was expressed from the automix syringe into the ceramic resin crown. The crown was then seated intraorally and excess cement was removed at the margins and then light-cured. The resin cement was allowed to self cure for an additional 3 minutes to ensure that the areas the curing light was not able to reach were fully cured. The margins were checked to ensure no excess cement remained and occlusion was checked to verify that no high spots were present. The patient confirmed the bite felt comfortable (Figure 13). A radiograph was taken to verify the proper seating and contour of the new ceramic resin crown (Figure 14). The patient was dismissed, with treatment completed in a single appointment.
Figure 13. The final 3D printed crown following cementation intraorally on the maxillary first premolar.
Figure 14. A bite-wing radiograph following completion of the new restoration on the maxillary first premolar.
CONCLUSION
As discussed, single-appointment treatment when crowns are planned aids in improving time management for both the patient and the dentist. The use of 3D printing provides an alternative to in-office CAD/CAM milling restorations that require less technology investment for the practice. Until recently, the resin materials available for 3D printing were not ideal for long-term definitive crowns due to wear issues that were potential with those materials. Recent advances in resin technology have improved those prior issues with ceramic-dominant resins comprised of more than 50% ceramic particles, improving wear and making those restorations comparable in wear factors to other crown materials that are lab-fabricated. The FDA has cleared SprintRay’s Ceramic Resin for definitive full crowns, partial crowns (inlays and onlays), and veneers. Thus, utilization of this new ceramic printed resin permits fabrication of single-appointment, definitive restorations—as shown in the case example—that have good wear characteristics and excellent aesthetics.
ABOUT THE AUTHORS
Dr. Hosseini earned his DDS degree from the University of Illinois Chicago College of Dentistry. Through CEREC intraoral scanning, 3D Cone Beam CT, milling, and 3D printing, he has set his practice apart and has emerged as a leader in many aspects of CAD/CAM dentistry. Since becoming an early adopter of dental 3D printing technology in 2017, Dr. Hosseini has developed relationships with SprintRay as it emerged as the leading dental 3D printing company. He can be reached at drh@ariatadental.com.
Dr. Kurtzman is in private general dental practice in Silver Spring, Md; a former assistant clinical professor at the University of Maryland in the department of Restorative Dentistry and Endodontics; and a former American Academy of Implant Dentistry Implant Maxi-Course assistant program director at Howard University College of Dentistry. He has lectured internationally on the topics of restorative dentistry, endodontics, implant surgery and prosthetics, removable and fixed prosthetics, and periodontics. He has more than 890 published articles globally, as well as several ebooks and textbook chapters. He can be reached at drimplants@aol.com.
Disclosures: Dr. Hosseini has received honoraria for lecturing for SprintRay. Dr. Kurtzman received an honoraria for writing the article.
