Introduction
In today’s busy life, patients may have trouble when treatment requires multiple appointments to coordinate their work and home schedules. Typically, when the restoration of teeth is related to failing amalgam/composite restorations or caries, teeth may require more extensive treatment than just placing another direct restoration. It will typically require 2 appointments. The first appointment involves the preparation of the teeth to remove the existing restorative material and caries, an impression taken, and a provisional restoration placed. The second appointment is scheduled after lab fabrication of the restoration to insert it intraorally.
Using 3D printing, with its advances in printable resin materials and hardware to create those restorations, allows the practitioner to fabricate those indirect restorations in the office in a single appointment. Additionally, 3D printing resins have advanced, incorporating higher amounts of ceramic particles to improve the materials’ wear and durability. The FDA cleared those resins for definitive crowns, inlays, onlays, and veneers. Ceramic Crown HT resin (SprintRay) features greater than 60% ceramic particles, providing good aesthetics with high translucency. It is currently available in shades A1, A2, and B1 and available on the Midas system in capsule format. Highly filled resins have posed some problems in their use in traditional 3D printing due to their high viscosity compared to traditional 3D printing resins used for the fabrication of restorations.
Advances in 3D printing hardware have allowed higher-quality restorations to be printed with the new resins in shorter fabrication times. The Midas 3D printer (SprintRay) provides those advances and, with its patented Digital Press Stereolithography (DPS), overcomes the challenges of printing those highly filled viscous materials. The patent-pending Resin Capsule System utilized in the Midas unit is designed to handle highly viscous resins that traditional 3D printing technologies may not be able to manage (Figure 1).
Midas eliminates viscosity limitations by removing the boundaries previously faced to change the mechanical properties and aesthetics of the resins being printed. It utilizes a unique, vacuum-sealed resin capsule that simplifies workflow, allowing printing of multiple units in just minutes from a single capsule (Figure 2). This shortens fabrication time while enhancing single-appointment restoration treatment. Most Midas restorations can be completed in less than 10 minutes with the ability to print multiple restorations per capsule and up to 3 capsules simultaneously with no time delays.
Case Report
A 32-year-old female patient presented with cold sensitivity on the upper right posterior teeth. An examination noted old composite fillings in the molars and premolars with recurrent caries evident on each tooth (Figure 3). A bite-wing radiograph was taken to evaluate the extent of the recurrent caries and the dimensions of the current composite restorations (Figure 4). The patient was advised that inlay and onlay style restorations would be the best solution due to the size of the current failing composites and the recurrent caries. This treatment plan would preserve tooth structure as an alternative to full coverage restorations. Our intent was to provide conservative restoration with superior accuracy and definition compared to milling, as well as better predictability and mechanical properties than direct resin composite restorations. The patient’s questions were answered, and she agreed to the suggested treatment. She was informed that the treatment could be completed in a single appointment utilizing 3D printing for restoration fabrication. Since there was time in the schedule that day, we proceeded and the patient was anesthetized with local anesthetic. A pretreatment scan was performed of the arch with an i900 scanner (Medit) to aid in the virtual designing of the planned restorations (Figure 5).
The old composite and recurrent decay were removed with a high-speed handpiece and appropriate burs. Caries detector dye (Caries Finder Caries Disclosing Dye [Danville Materials]) was applied and used to ensure complete decay removal. The preparations were refined for 1.5-mm depth occlusal reduction and verified that no planned restoration margin was present on the occlusal surface, which would be in contact when the patient occluded the teeth (Figure 6). The prepared quadrant, opposing dentition, and occluded arches were then scanned with the i900 scanner and imported into the Medit ClinicCAD design software. The restorations were designed in the software with a cement gap of 0.1 mm and minimum thickness of 0.6 mm to contours, matching the pre-prep treatment scan (Figures 7 and 8). The virtual restorations were removed from the virtual models in preparation for setting up for 3D printing on the Midas unit (Figure 9). Supports were added to the virtual restorations and prepared for 3D printing in the Midas capsule (Figure 10).
Models of the upper and lower quadrants were designed (Figure 11) and then printed in dental Model Resin, stone color (SprintRay) in the Pro2 3D printer (SprintRay) unit. These were designed to articulate together, simulating the patient’s dentition and occlusion. This aids in the finishing and polishing of the restorations (Figure 12).
The restorations were printed on the Midas unit using Crown HT resin with a print time of approximately 9 minutes. A single capsule was used for all 4 restorations. Following printing, the restorations were removed from the Midas unit (Figure 13). Washing and curing were performed, and it took approximately 4 minutes to complete. Restorations were shaken for 6 seconds in a martini shaker-type container, air dried, then sprayed again with 91% isopropyl alcohol, then wiped with a lint-free paper towel and microbrush. The supports were removed from the printed restorations except one to allow something to hold onto during the finishing and glazing process. The restorations were then submerged into a bowl of IPA, and a brush was utilized to remove any surface residue. The restorations were then dried with air and placed into the NanoCure (SprintRay) to complete the processing phase of fabrication. Surface characterization was done with Nu:le Coat resin characterization kit (Yamakin) and cured in NanoCure for one minute. The supports were removed from the printed restorations with a diamond in a high-speed handpiece, and the areas where the supports were present were polished.
The restorations were then pre-polished with an OptraGloss Spiral Wheel (Ivoclar) in a slow-speed handpiece. This was followed by polishing with Universal Polishing Paste (Ivoclar) using a goat hair brush in a slow-speed handpiece. Final polishing was then performed with a clean cotton buffing wheel at high speed. The remaining supports were removed, and the areas polished, completing the fabrication of the 3D printed restorations (Figure 14). The total time from the start of printing to the restorations being ready to insert intraorally was approximately 16 minutes. The printed restorations were tried on the printed models to verify fit and occlusion (Figures 15 and 16).
The completed 3D printed Crown HT resin restorations were taken to the operatory and tried intraorally to verify marginal and interproximal fit. The 3D printed restorations were removed, and the intaglio surfaces were sandblasted in the lab with 50-µm aluminum oxide particles for 8 seconds to prepare the surfaces for bonding. The restorations were then wiped with a cotton swab dipped in alcohol and a microbrush, then dried thoroughly. Adhese Universal bonding agent (Ivoclar) was applied to the intaglio surface of the restorations with a microbrush and allowed to sit for 20 seconds. The restorations were then air thinned and not light cured at this time. Etching gel was applied to the teeth and allowed to sit for 30 seconds before being rinsed off and the preparation air dried. Additional Adhese Universal bonding agent was applied to the teeth with a microbrush and scrubbed into each tooth’s surface for 20 seconds; then air thinned so that an immobile layer was achieved. This was followed by light curing for 5 seconds on Turbo mode (2,000 mW) using Bluephase PowerCure (Ivoclar) on Turbo mode. Variolink Esthetic DC (Ivoclar), a dual-cure resin cement, was applied to the restorations’ intaglio surfaces, and the restorations were seated intraorally. Excess cement at the margins was tack cured for one second and then removed. The restorations were then light cured from the occlusal, buccal, and lingual for 5 seconds on each surface. The excess cement was removed. Glycerin was applied to the margins and cured for 5 additional seconds per surface. The margins were finished and polished intraorally, completing the restorations (Figure 17). A periapical radiograph was taken to verify marginal fit interproximally and that no residual resin cement was present (Figure 18).
Conclusion
In-office 3D printing allows the practitioner to treat teeth requiring an inlay, an onlay, or a crown in a single appointment, eliminating the need for the patient to wear a provisional restoration while waiting on the lab to fabricate the restoration and return it to the practice for insertion. Additionally, this is more convenient for the patient as it eliminates the need for a second appointment. Midas and the high-filled ceramic resins used in its 3D printing unit provide definitive restorations in a single appointment with its short printing time, resulting in highly aesthetic restorations. The improved accuracy, efficiency, predictability, and material science of the Midas printer system opens new doors to another high-quality, same-day-visit dentistry for patient treatment.
ABOUT THE AUTHORS
Dr. Shao is the clinical director for BioMaterial Innovation Lab, a digital dentistry educator, and a full-time clinician at Sunrise Dental Center in Huntington Beach, Calif, where he integrates cutting-edge digital and 3D printing technologies in patient care. He is the founder and president of Unicone Design Consulting, specializing in various design and rapid prototyping in various field. He is also a guest lecturer and educator in digital dentistry for multiple dental schools globally. He can be reached at steven@uniconedesign.com.
Dr. Kurtzman is in private general dental practice in Silver Spring, Md, and a former assistant clinical professor at University of Maryland in the department of Restorative Dentistry and Endodontics and a former AAID 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 900 published articles globally, several ebooks, and textbook chapters. He can be reached at dr_kurtzman@maryland-implants.com.
Disclosure: Dr. Shao is clinical director for Biomaterial Innovation Lab as an independent consultant. He is also a nonpaid clinical advisory Board member for SprintRay No financial compensation was received for the publication of this article. Dr. Kurtzman received compensation from SprintRay for writing this article.
