Full-arch implant treatment is increasingly being offered to restore failing or lost dentition. Typically, the implants are planned, followed by guided placement, and a lab-fabricated provisional prosthesis is retrofitted intraorally to the implants to deliver a hybrid prosthesis. The time involved chairside tends to be long as the provisional prosthesis is retrofitted, and this process is frequently accomplished by a lab technician. This can complicate the practice’s schedule, as the operatory is occupied for an extended period of time limiting other patients from being treated that day.
Advances in technology have led to decreases in chairside time for delivering the provisional prosthesis and providing superior hybrid prosthetics utilizing virtual planning and 3D printing. Preplanning with virtual planning software allows the process to be potentially less complicated than older, traditional methods that involved fabrication of a physical denture setup. Utilizing a virtual approach is less time consuming, accelerating the treatment process. Additionally, 3D printing resins have improved, providing stronger prosthetics that permit long-term usage compared to traditional acrylic resins that are typically used for provisional crown-and-bridge prosthetics.
Traditionally, provisional hybrid prosthetics have been fabricated using methyl methacrylate (MMA) resins that are used for provisional crown-and-bridge restorations and dentures. These were usually created by lab replication of a denture wax-up that was tried intraorally prior to implant placement when immediate provisionalization was planned to verify the occlusion with the opposing arch. The implants were then planned, and a surgical guide created along with the MMA provisional with holes created at the planned sites. The provisional at this stage appears like a denture with denture flanges to allow stability intraorally during the pickup process chairside.
At the surgical appointment, following implant placement, temporary abutments are placed on the implants and the MMA hybrid is seated over the arch to verify that it fully seats on the ridge and is not in contact with the abutments. The abutments are then luted chairside to the hybrid with MMA using a powder/liquid material. Following setting of the resin, the hybrid is removed, and additional resin is applied to the connector portion of the abutment to blend it with the surrounding acrylic. The coronal aspect of the abutments can then be adjusted if they project past the occlusal surface of the hybrid. The final step is elimination of the flanges to develop a proper contour gingivally for the hybrid to allow for oral homecare by the patient. These steps, as mentioned, are time consuming chairside and decrease practice efficiency. 3D printing and planning has eliminated time-consuming steps chairside, making the process of provisional delivery more efficient.
Polymethyl methacrylate (PMMA)–milled hybrid restorations have been presented in recent years as an alternative to the traditional method. Although this does offer a stronger alternative to MMA-based prosthetics, it does require fabrication at the lab as few practices have the capability to mill these prostheses in-office. 3D printing provides a comparable product that can be fabricated in-office at the time of implant placement with reduced production time.
OnX Tough 2.0 3D Printing Resin
Resin technology has made recent advances with 3D printing, resulting in stronger hybrid prostheses with less chairside time required at lower cost due to the ability to print them in-office vs sending them to the lab. OnX Tough 2.0 resin (SprintRay, sprintray.com) has received FDA clearance for use for fixed hybrid prosthetics. This resin utilizes cutting-edge NanoFusion™ technology, setting an industry standard offering exceptional durability and visual quality.
The resin provides high flexural strength (126 MPa) with high flexural modulus (4281 MPa), which prevents distortion that can lead to material fracture. Additionally, OnX Tough 2.0 has a fracture resistance of >900 J/m2 and a fracture toughness of 2.9 KIc. The resin is strong and durable, lending itself for use as a long-term hybrid prosthesis when needed. OnX Tough 2.0 is available in A1, A2, Bleach, and Hollywood White shades and allows customization with tints following printing to yield natural esthetics.
Workflow consists of intraoral scanning prior to the surgical visit, which allows for virtual design of the prosthesis in preparation for the implant placement appointment. Following implant placement, a scan is taken intraorally to capture implant connector positions. This is imported into the software and merged with the previously planned hybrid prosthesis. That is then sent to the 3D printer and the prosthesis is printed in 25 minutes. The prosthesis is washed and cleaned (10 minutes), then finished by removing the supports. Post curing is performed (5 minutes) and then the prosthesis is polished.
Characterization can be added using Akzent LC™ (VITA North America, vitanorthamerica.com) to the gingival aspects or tooth aspects of the hybrid. Typically, this process takes 60 to 90 minutes in the office’s lab area and can be done by trained staff, freeing up the doctor to treat other patients during that fabrication process time. The patient can remain in the operatory during that in-house lab process or sit in the waiting area, freeing up the operatory for other procedures and allowing the patient to relax more comfortably than sitting in the operatory chair for a long period of time.
Case Example
A 58-year-old male patient presented with a complaint of mobile teeth on the lower right, seeking a more stable situation. The patient was wearing a mandibular partial denture and the only remaining teeth on the lower arch was the left second molar (No. 18), as well as the first and second premolars bilaterally. An intraoral exam noted mobility on teeth Nos. 28 and 29. The patient was missing all maxillary molars, and the remaining maxillary dentition was stable periodontally. A panoramic radiograph was taken to evaluate the dentition and associated anatomy (Figure 1). Radiographically, significant bone loss was noted on the right mandibular premolars.
A treatment plan was developed and discussed with the patient that would involve edentulation of the mandibular teeth and placement of four implants spread on the arch respecting the anatomy and inferior alveolar nerve bilaterally. Following immediate implant placement, a provisional prosthesis would be fabricated via 3D printing and immediately placed. The patient agreed to the treatment plan presented.
Intraoral scans were accomplished with a DEXIS IS 3800W (DEXIS, dexis.com) scan of the maxillary and mandibular arches. The mandibular arch was also scanned with the current partial denture intraorally and in occlusion with the maxillary arch. The patient was dismissed and appointed for the surgical treatment and delivery of the prosthesis.
The intraoral scans were imported into DTX Studio software (DEXIS) to begin the implant and prosthesis planning (Figures 2 and 3). A virtual prosthesis was designed to articulate with the maxillary dentition (Figure 3). Implants were planned at four sites in the mandibular arch (Figure 1).
The patient presented for the surgical appointment and the consent form for implant placement was reviewed with the patient and signed. Local anesthetic was administered. The mandibular dentition was extracted atraumatically. Osteotomies were accomplished with placement of Nobel RP conical connection implants (Nobel Biocare, nobelbiocare.com) at No. 19 (5 x 10 mm), No. 23 (4.3 x 13 mm), No. 26 (4.3 x 13 mm), and No. 29 (4.3 x
15 mm). Multi-unit abutments were placed on the implants at 0° with a 1.5-mm cuff height on Nos. 19, 23, 26, and at 30° with a 3.5-mm cuff height on No. 29. Scan flags (ICam, Imetric 4D, imetric4d.com) were placed on the four implants, the arch was scanned with a DEXIS IS 3800W scanner intraorally, and the scan was imported into the planning software. The scan bodies were removed intraorally, and white Nobel healing caps were temporarily placed on the implants to prevent soft tissue closure while the prosthesis was being designed and printed. An alginate impression was taken using a printed denture with gray model resin, and was printed on the SprintRay Pro 55 S printer. That impression was then scanned with a Medit T710 tabletop scanner (Medit USA, medit.com) and was then imported into the ICam software to merge the soft tissue with the implant positionings. The merged STL file was then imported into exocad (exocad America, exocad.com) for the final design. A panoramic radiograph was taken to document implant position related to the surrounding anatomy (Figure 5).
The previous virtual-designed prosthesis was merged with the scan of the implants. Modification of the hybrid design was accomplished creating the intaglio surface related to the implant connections and soft tissue (Figures 6 and 7). Emergence of the screw-access holes on the occlusal surface allowed sufficient prosthetic material around them to prevent fracture of the prosthesis during function (Figure 7). The virtual implant analogs were removed virtually, and the prosthesis design was completed in preparation for printing (Figure 8 through Figure 10). The hybrid prosthesis was printed on the Pro 55 S printer, utilizing OnX Tough 2.0 resin. Following 3D printing, the prosthesis was removed from the build plate with its supports present (Figure 11). The supports were removed with an acrylic bur and the surfaces were finished (Figures 12 and 13). Akzent LC gingival tone resin (VITA North America) was applied to the gingival aspects of the hybrid prosthesis and cured to provide a natural esthetic appearance.
The 3D-printed prosthesis was taken to the operatory for insertion. The healing abutments were removed, and the hybrid prosthesis was inserted intraorally. A panoramic radiograph was taken to verify the seating of the prosthesis on the implants (Figure 14). The fixation screws (DESS 19.018 screws, DESS, dess-usa.com) were tightened to 15 Ncm per the implant manufacturer’s recommendations. The screw-access holes were then sealed with teflon tape and Gingitech gingival masking material (Ivoclar Vivadent, ivoclar.com). Occlusion was checked and no adjustments were required (Figures 15 and 16). The patient was shown a mirror and indicated satisfaction with the esthetics of his new smile (Figure 17). The patient was appointed for a follow-up visit to check occlusion and verify the patient was not having any issues with the prosthesis.
The patient returned at 1 week and indicated no issues with the occlusion nor any discomfort intraorally. He was seen periodically over the following 6 months to check his comfort and confirm integrity of the prosthesis. No wear was noted nor fracture of the OnX Tough 2.0 prosthesis over that time period. This also allowed the patient to test drive the occlusion and esthetics before fabrication of the final prosthesis. The patient indicated he was satisfied with esthetics and no changes were needed for the final prosthesis.
A final hybrid prosthesis was created utilizing the virtual design of the provisional prosthesis and STL files were sent electronically to Nobel Procera (Nobel Biocare) for milling of the final restoration. The hybrid was CAD/CAM-milled utilizing Nacera 3Y zirconia. The gingival aspects of the zirconia hybrid were colored gingivally with MiYO stain and glaze (miyoworld.com) to create a natural esthetic appearance. The patient returned and the OnX Tough 2.0 hybrid was removed intraorally and the final zirconia hybrid prosthesis was inserted intraorally. The fixation screws were tightened to 15 Ncm and the screw-access holes were sealed with teflon tape and flowable composite (Premise A1 flowable, Kerr Dental, Brea, California).
Conclusion
3D printing has revolutionized dental treatment, allowing in-office fabrication of prosthetics in a single appointment setting. This has transferred to full-arch implant treatment, allowing a hybrid prosthesis to be created while the patient waits following implant placement. Efficiency and patient satisfaction are enhanced when implants are placed in a single appointment—either immediately after extractions or, in the case of an edentulous arch, with the patient leaving the office with a prosthesis. Timing may also require the patient to use that hybrid prosthesis for an extended period of time. OnX Tough 2.0 is a high-strength material permitting its use either long term or, in some cases, as a final prosthesis when patient finances will not allow for conversion to a zirconia prosthesis, or when other life factors are present.
Acknowledgement
The authors would like to thank Sura Aldulaimi (surgical assistant) for her assistance with case treatment and providing the images.
Disclosure
Joe Mehranfar, DMD, is a paid key opinion leader for SprintRay and DEXIS. Both Joe Mehranfar, DMD, and Landon Winters are global experts for Nobel Biocare.
ABOUT THE AUTHORS
Joe Mehranfar, DMD
Diplomate, American Board of Implantology/Implant Dentistry
Co-Founder and Clinical Director, Implant Education Company, LLC
Founder, Aria Dental Implant Center
Phoenix, Arizona
Gregori M. Kurtzman, DDS
Private Practice
Silver Spring, Maryland
Landon Winters
Clinical Director, Dental/Partner Implant Education Company
Lab Director and CAD Designer,
Aria Dental Implant Center
Phoenix, Arizona
Figures and Images
Joe Mehranfar, DMD
Gregori M. Kurtzman, DDS
Landon Winters
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