Digital Full-Arch Maxillary Rehabilitation

Innovative scanning techniques and in-office 3D printing facilitate highly accurate and efficient treatment

Isaac Tawil, DDS, MS | Daniel Domingue, DDS | Scott D. Ganz, DMD

When taking a digital approach to full-arch implant cases, the use of proper imaging techniques is essential to the accuracy of diagnosis, treatment planning, finalization, and tracking patient advancement. In addition to an increase in the use of cone-beam computed tomography (CBCT), intraoral scanning has gradually displaced the use of traditional dental impressions, and it is now being integrated with facial scanning to provide an enhanced method of capturing the oral anatomy and other information about the smile to be used in treatment planning. To deliver superior full arch implant-supported restorations, clinicians should develop a comprehensive understanding of the capabilities and constraints of each imaging modality and be prepared to address the challenges related to provisionalization as well as the prosthetic and surgical considerations.

Intraoral and Facial Scanning

Intraoral scanning offers clear advantages in many cases,¹ delivering high precision and accuracy while enhancing the efficiency of treatment.² However, its implementation into implant procedures presents unique challenges, particularly those involved in capturing edentulous arches.³ Tackling these challenges requires innovative strategies, such as linking or bonding the scan bodies over multi-unit abutments.⁴ Another approach to mitigate intraoral scan stitching issues using traditional multi-unit abutments involves the use of elongated scan bodies, some of which have unique individual shapes, to minimize the gaps between implants and permit continuous intraoral scanning without interruptions. These distinct scan body shapes prevent the scanner acquisition software from duplicating, overlapping, or confusingly scanning the same object. Regarding the use of 3D facial scanning, clinicians and laboratory technicians are now using cutting-edge hardware and software to integrate intraoral scans with 3D facial scans.^5,6 This integration transfers depth information about the face, providing a comprehensive view of facial contours, volumes, and spatial relationships. With more realistic depth visualization the accuracy of diagnosis and treatment planning are improved.

Immediate 3D Printed Provisional Prostheses

Once a full-arch treatment plan has been approved, clinicians face several decisions, including the choice of either freehand surgery or guided surgery, an immediate loading protocol or delayed loading protocol for the implants, and provisional restorations that are prefabricated or fabricated after implant placement.⁷ Traditionally, denture conversion and delayed loading were the only options; however, the emergence of in-office 3D printing has enabled the delivery of same-day or next-day provisional prostheses.⁸ Recent advancements in 3D printers and resin materials have enhanced clinicians' control of a provisional restoration's shape, color, and fit as well as significantly increased the strength of full-arch provisional restorations, reduced the time required to print them, and made coping-free solutions achievable in less than 15 minutes. When a treatment plan involves delivering a 3D printed provisional solution, accurately capturing the postsurgical implant position and relating it to the preoperative plan is critical to expedite conversion and printing.⁹ In dentate cases, this process can be simplified by retaining a triad of scannable teeth, which enables the pre- and postsurgical positions to be quickly matched. The following case report demonstrates the use of these advanced digital dentistry techniques to improve the accuracy and efficiency of full-arch implant cases.

Case Report

A 57-year-old female patient with a noncontributing medical history presented with the need for maxillary rehabilitation and the replacement of missing mandibular posterior teeth. After radiographs were acquired (RVG 6200, Carestream Dental) (Figure 1), a CBCT scan was obtained (CS 9600, Carestream Dental) to evaluate the viability of the remaining teeth and the bone levels (Figure 2). Dental scans, including intraoral scans (AoralScan3 Wireless, Shining 3D) and facial scans (MetiSmile, Shining 3D), were then captured, merged (Figure 3), and transferred into the treatment planning software (RealGUIDE^™, Zimmer Biomet) (Figure 4). During the facial scan, the patient appeared to experience difficulty smiling, which was likely a result of being conditioned to minimize her smile due to the poor esthetic value of her teeth. A final treatment plan was created, which consisted of six maxillary implants to support a prosthesis, as well as a crown on one of the remaining maxillary molars, and four mandibular implants for individual restorations to restore posterior occlusion. It was presented to the patient and accepted.

A digital wax-up was performed using the facial and intraoral scans in CAD software (DentalCAD, Exocad), with the CBCT scan also playing a significant role. Segmentation of the teeth to create a virtual extraction model enabled proper evaluation of the implant positions. A workflow was established that would involve a guided surgical protocol and the same-day delivery of a 3D printed provisional prosthesis. Because two of the patient's maxillary molars were already planned for preservation, the decision was made to temporarily retain an additional maxillary lateral incisor to create a triad of teeth, simplifying the matching of the pre- and postsurgical scans. Finally, a surgical guide was designed (Figure 5), printed (AccuFab-L4D, Shining 3D) with surgical guide resin (Rodin^®, Pac-Dent), and confirmed on a 3D printed model (Model resin, Shining 3D) (Figure 6), then the patient was scheduled for surgical intervention.

Implant Placement and Provisionalization

After anesthetizing the patient, the planned extractions were carried out utilizing elevators (Elvatome^® 2.0, TBS Dental) and forceps (FRINGS, TBS Dental) (Figure 7). The extracted teeth were then pulverized (Smart Dentin Grinder, Kometa Bio) (Figure 8 and Figure 9), washed, sterilized, and treated with platelet-rich fibrin (PRF) obtained from the patient to create "sticky bone" for augmentation. Next, debridement of the sites was achieved, and the osteotomies were created. This was followed by scalloping of the osteotomies and pontic sites using shaping burs (Universal Shapers, Universal Shapers) (Figure 10). Ten implants (AnyRidge^®, Megagen America) were then placed, including six in the maxilla and four in the mandible. Following placement, the maxillary implants were loaded with straight multi-unit abutments (Figure 11), and the mandibular implants were second-staged with healing abutments. The sites were then augmented with the sticky bone graft, covered with a PRF membrane, and sutured.

After scan bodies were inserted into the multi-unit abutments, intraoral scans were acquired with the triad of teeth remaining in place (Figure 12). The lateral incisor was then extracted as planned and grafted, covered with a PRF membrane, and sutured. Finally, healing abutments were placed.

The files were promptly transferred to a design service, where the design technician incorporated all of the pre- and postsurgical scans, along with the approved initial provisional design (Figure 13), into a final design for the provisional prosthesis. Any modifications to the implant positions or tissue changes were taken into account, and a new design was created within an hour of uploading the files and emailed to our office. The provisional prosthesis was then 3D printed using a strong and esthetic resin (Rodin^® Sculpture 2.0 [shade A2], Pac-Dent) (Figure 14) and post-processed (FabWash, Shining 3D) per the manufacturer's guidelines for the material. After curing and polishing, a glaze was applied to the provisional prosthesis, and it was recured (Figure 15).

Following removal of the healing abutments, the coping-free prosthesis was delivered with appropriate prosthetic screws (Vortex^™ screws, Voxel Dental) and hand-tightened into place. The occlusion was manually checked and then confirmed with a digital articulation device (OccluSense^®, Bauch), which indicated no need for equilibration. A postoperative panoramic radiograph was acquired to confirm full seating of the provisional restoration (Figure 16). Because the prosthesis was radiolucent and lacked metal copings, proper seating of the screws could be visualized. The access holes were plugged with PTFE tape and sealed with a temporary material (Telio^®, Ivoclar), and then the patient was provided with postoperative, dietary, and oral hygiene instructions and dismissed.

Delivery of the Final Restoration

The patient attended postoperative visits over the next 3 months, during which time the healing was uneventful, and no complaints or concerns were reported. Inspections of the screws were performed to ensure that the prosthesis remained properly seated. At each successive postoperative visit, the patient's mood noticeably improved, and she smiled more frequently, seemingly satisfied with her enhanced esthetic appearance (Figure 17). New scans were captured, including intraoral scans and a facial scan. Intraoral scans were acquired of the provisional prosthesis with the soft tissue, the mandibular posterior implants, and the occlusion. After the provisional prosthesis was removed, the multi-unit abutments and implants were checked, and additional intraoral scans were acquired. The soft tissue had healed remarkably well (Figure 18), and the integration of the implants was successfully completed; therefore, it was determined that the case could be finalized. Next, an intraoral scan using uniquely shaped scan bodies (Archbridge^™, ROE Dental Laboratory) to span the edentulous space was acquired for confirmation (Figure 19). Regardless of whether a clinician decides to use an innovative scan body solution or photogrammetry, it is advisable to retorque the multi-unit abutments prior to final scanning per the manufacturer's recommendations. Finally, an extraoral scan of the provisional prosthesis was conducted by attaching scan analogs to it (iJig^™, ROE Dental Laboratory) and scanning it with a desktop scanner (AutoScan DS-EX Pro, Shining 3D) (Figure 20). Although this process could also have been completed with an intraoral scanner, the simplicity and accuracy are significantly enhanced when a desktop scanner is used.

All of the files were uploaded to the cloud-based software, and comments from the restorative clinician were incorporated, including minor changes to the shape, material, and shade desired. Given the patient's satisfaction with the provisional restoration, the decision was made to advance directly to a final screw-retained, coping-free, full-arch, zirconia restoration. A new design was finalized in the CAD software by the laboratory and then forwarded to the restorative clinician through a web viewer for review and approval. Following a thorough review with the patient, the design was deemed to be satisfactory and approved. In addition to the maxillary zirconia prosthesis, orders were placed for "screwmentable" titanium abutments and zirconia crowns for the mandibular posterior implants. Subsequently, the restorations were milled and prepared for insertion (Figure 21).

After removing the provisional restoration, a final inspection of the multi-unit abutments and implants was conducted. The insertion of the final maxillary screw-retained prosthesis proceeded smoothly, with the prosthetic screws torqued to 15 Ncm. The final mandibular screw-retained crowns were torqued to 35 Ncm. A final panoramic radiograph was acquired to confirm proper seating (Figure 22), and all of the access holes were closed with PTFE tape and flowable composite. The patient exhibited extreme excitement upon receiving her final FP1 restoration (Figure 23). During the 6-month follow-up appointment, she returned with a large smile and exuded confidence (Figure 24), marking a true change in both her appearance and overall personality when compared with her initial presentation. Her function and esthetics were excellent, and she reported no concerns.

Acknowledgement

The authors would like to thank ROE Dental Laboratory in Independence, Ohio, for performing the design work on this case.

About the Authors

Isaac Tawil, DDS, MS
Founder and Co-director
Advanced Implant Education
Private Practice
Brooklyn, New York
Daniel Domingue, DDS
Private Practice
Lafayette, Louisiana

Scott D. Ganz, DMD
Co-Director
Advanced Implant Education
Private Practice
Fort Lee, New Jersey

References

1. Lee SJ, Betensky RA, Gianneschi GE, Gallucci GO. Accuracy of digital versus implant impressions. Clin Oral Implants Res. 2015;26(6):715-719.

2. Mangano FG, Hauschild U, Veronesi G, et al. Trueness and precision of 5 intraoral scanners in the impressions of single and multiple implants: a comparative in vitro study. BMC Oral Health. 2019;19:101.

3. Alkadi L. A comprehensive review of factors that influence the accuracy of intraoral scanners. Diagnostics (Basel). 2023;13(21):3291.

4. Tawil ID, Ganz SD. Fully digital full arch? Continued advancements in full-arch implant restorations. Dent Today. 2023;42(4):50-57.

5. Hou X, Xu X, Zhao M, et al. An overview of three-dimensional imaging devices in dentistry. J Esthet Restor Dent. 2022;34(8):1179-1196.

6. Pozzi A, Arcuri L, Moy PK. The smiling scan technique: facially driven guided surgery and prosthetics. J Prosthodont Res. 2018;62(4):514-517.

7. Ganz SD, Tawil I. Full-arch implant surgical and restorative considerations: utilizing a full template guidance technique. Dent Today. 2019;38(9):72-78.

8. Ferguson R. Simplifying full-arch treatment with in-house 3D-printed surgical guides and immediate fixed provisional prostheses using only CBCT data. Compend Contin Educ Dent. 2020;41(10):521-526; quiz 527.

9. Lepidi L, Galli M, Grammatica A, et al. Indirect digital workflow for virtual cross-mounting of fixed implant-supported prostheses to create a 3D virtual patient. J Prosthodont. 2021;30(2):177-182.