Bridging the Translation Gap in Full-Arch FP1 Rehabilitation: A Case Report

The successful fixed rehabilitation of the edentulous arch begins with the face, not the residual ridge. Facially generated treatment planning (FGTP) establishes the ideal 3-dimensional position of the maxillary incisal edge relative to the patient’s facial dynamics before integrating functional, structural, and biological requirements.¹ When this idealized design is superimposed over the existing anatomy, the spatial relationship between the cervical margin of the planned tooth and the residual ridge determines the defect classification. A tooth-only defect, where the ridge meets the planned cervical margin, supports a fixed prosthesis 1 (FP1) design emerging directly from the native mucosa.²

In patients with medium to high smile lines, the FP1 design is unforgiving. Implant position and emergence profiles directly influence the visible esthetic outcome and must be precise, while passive fit, although not visible, is critical for long-term biological and mechanical success. An FP3 prosthesis may seem to offer greater margin for error through its compensating pink acrylic, but in these patients the transition zone itself becomes the liability. Concealing it may require aggressive alveolar bone reduction, paradoxically converting a manageable tooth-only defect into a major skeletal deficiency. An FP1 approach preserves the native alveolar architecture and maintains biological capital for any future revision.

Achieving the accuracy required for an FP1 result is challenging. The “translation gap” between the virtual plan and the clinical outcome arises from three principal sources: deviation during guided surgical transfer, error during 3-dimensional implant registration, and loss of coordinate system continuity between planning and prosthetic design.

Surgical transfer error is well documented, with Tahmaseb et al reporting mean deviations of 1.2 mm at the entry point, 1.4 mm at the apex, and 3.5 degrees in angulation.³ For FP1 prostheses, even minor deviations can compromise emergence profiles and produce visible prosthetic interfaces at the tissue level.

Implant registration captures the 3-dimensional positions of the placed implants for transfer into the prosthetic design. Intraoral scanners have become the standard for digital impressions, but their accuracy degrades over extended edentulous spans as stitching algorithms accumulate error in the absence of distinct anatomical landmarks.^4,5 This limitation is compounded in the immediate post-surgical environment, where blood, saliva, tissue swelling, and patient discomfort can further compromise scan quality and limit acquisition time.

Revilla-León et al have classified various approaches that were developed to address this situation into five categories: non-splinting, noncalibrated splinting, calibrated implant scan bodies, calibrated frameworks, and reverse impression methods.⁶ Splinted techniques have demonstrated improved accuracy compared to non-splinted approaches,⁷ and photogrammetry has shown superior trueness compared to intraoral scanning.^8,9 More broadly, extraoral scanning methods have demonstrated significantly better trueness than direct intraoral scanning.¹⁰ OptiSplint® (Digital Arches, Inc., digitalarches.com) is a noncalibrated splinting device that rigidly connects single-use horizontal scan bodies to a honeycomb metal framework with low-shrinkage composite resin. The manufacturer’s protocol specifies removal of the splinted assembly and scanning with a laboratory scanner.^11,12

A third source of the translation gap, as noted above, is the loss of coordinate system continuity. When the presurgical plan and post-surgical implant data exist in separate digital environments, the prosthetic design must be recreated from the surgical outcome alone. In immediate loading protocols, this challenge is amplified by the compressed design timeframe. A physical fiducial marker present in both preoperative and post-surgical scans can link these datasets and preserve the relationship to the original facially generated treatment plan.

This case report describes a complete digital workflow for full-arch FP1 rehabilitation integrating noncalibrated splinted implant registration with extraoral laboratory scanning, fully guided surgery with swappable guides, and a palatal fiducial marker for coordinate system continuity. (Written informed consent was obtained from the patient for publication of this case report and accompanying images.)

Case Report

Patient Presentation

A 42-year-old female patient presented to the Postgraduate Prosthodontics Clinic at the University of Pennsylvania with a chief complaint of dental instability, saying, “I just want to have my teeth be stable.” The patient’s medical history included mild chronic obstructive pulmonary disease, osteoarthritis, and post-traumatic stress disorder.

Extraoral examination revealed a high smile line exposing the full clinical crowns and several millimeters of gingival tissue during maximum animation. Intraoral examination revealed a partially dentate maxillary arch with a failing, heavily restored dentition, generalized inflammation with bleeding on probing, and a class II malocclusion with limited interarch distance. In this context, any discrepancy between the planned and delivered tooth position would be immediately visible to the patient (Figure 1 and Figure 2).

The FP1 Decision

Facially generated treatment planning was performed using a digital smile design/dental treatment planning platform (Smilecloud 3DNA, Smilecloud SRL, smilecloud.com) by superimposing portrait photographs, intraoral scans recorded in centric relation at the established occlusal vertical dimension, and cone-beam computed tomography (CBCT) data. A biometric tooth library was selected with the patient and positioned relative to her lip dynamics. The incisal edges were moved apically 1 mm to 2 mm to reduce gingival display, and the prosthetic volume was shifted palatally 0.5 mm to 1 mm to address the class II relationship and in anticipation of post-surgical tissue shrinkage (Figure 3).

Superimposition of the idealized design over the native ridge confirmed a tooth-only defect, supporting an FP1 prosthesis, which preserves alveolar architecture and avoids the bone reduction required for an FP3 transition zone. The case was classified as complex (surgical), advanced to complex (prosthodontic), and high esthetic risk per the straightforward, advanced, complex (SAC) 2.0 edentulous esthetic risk assessment (EERA) criteria.^13,14

Surgical Planning and Guide Design

Six implants (PrimeTaper EV, Dentsply Sirona, dentsplysirona.com) were planned with the following dimensions: site No. 3, 4.8 mm x 9 mm; site No. 5, 4.2 mm x 13 mm; sites Nos. 8 and 9, 3.6 mm x 13 mm; site No. 12, 3.6 mm x 9 mm; and site No. 14, 4.2 mm x 8 mm. Prosthetically driven implant positions were established in implant planning software (RealGUIDE®, 3DIEMME, 3diemme.it) relative to the CBCT anatomy (Figure 4 and Figure 5). Implant positions were determined by the prosthetic plan, accounting for ideal emergence depth relative to the planned gingival zeniths, prosthetic component dimensions, anteroposterior distribution, screw-access channel orientation, and available bone volume. Implant-to-buccal plate distance was assessed to anticipate grafting needs at immediate placement sites.

The sequential guide design addressed a fundamental challenge: sites Nos. 3, 5, 12, and 14 could be accessed with teeth still present via guide A, but sites Nos. 8 and 9 required prior extraction of the anterior teeth. A dual swappable guide protocol was designed to maintain positional continuity across this transition (Figure 6):

• Guide A (tooth–mucosa supported): flapless placement of implants at sites Nos. 3, 5, 12, and 14
• Guide B (mucosa supported): immediate placement at sites Nos. 8 and 9 following extraction of the remaining anterior teeth

Both guides shared fixation pin locations, ensuring that spatial accuracy was maintained as the arch transitioned from dentate to edentulous. A palatal fiducial marker (ArchTracer™, Digital Arches, Inc.) was incorporated into the plan to serve as a stable coordinate reference linking the preoperative esthetic plan to the post-surgical data.

Surgical Phase

Surgery was performed under nitrous oxide sedation with local anesthesia. The palatal fiducial marker was placed in a position that did not interfere with guide A seating (Figure 7). A preoperative intraoral scan (scan 1) was completed using an intraoral scanner (Medit i700, Medit, medit.com) with the fiducial marker in situ.

Guide A was secured with three fixation pins: two were placed buccally in the right and left canine regions, and one was placed in the midpalatal region. Pin positions were selected according to available bone volume, the positions of the retained roots, and the planned implant sites. Retained roots at sites Nos. 4, 6, and 7 were extracted, and four implants were placed flaplessly through the guide with crestal sinus lifts at sites Nos. 3 and 14. The remaining anterior teeth were extracted atraumatically. Guide B was positioned using the same fixation pin locations, and implants Nos. 8 and 9 were placed immediately (Figure 8 through Figure 10). Multi-unit abutments (MUAs) (MultiBase Abutment EV, Dentsply Sirona) were connected and torqued per manufacturer specifications. All implants achieved primary stability exceeding 35 Ncm insertion torque, and immediate loading was carried out.

Jumping distance gaps at sites Nos. 8 and 9 and extraction sockets were grafted with cancellous particulate allograft (Puros®, Zimvie, zimvie.com). An allograft (AlloDerm, BioHorizons, biohorizons.com) was placed buccally from sites Nos. 5 through 13.

Implant Registration

Horizontal scan bodies (OptiSplint) were secured onto the MUAs. The honeycomb metal framework was positioned, and the scan bodies were luted to it using a dual-cure composite (OptiWeld™, Digital Arches, Inc.), creating a rigid splinted assembly (Figure 11 and Figure 12). Radiographic verification confirmed full seating of all components on the MUA platforms.

Digital capture was followed in two stages:

Scan 2 (extraoral): The splinted assembly was removed from the mouth and scanned using a laboratory scanner (Medit T710, Medit), recording the 3-dimensional implant coordinates as a single rigid geometry (Figure 13).

Scan 3 (intraoral): A separate intraoral scan (Medit i700) captured the post-surgical soft-tissue contours with ScanCaps (Digital Arches, Inc.) on the MUAs and the palatal fiducial marker in situ (Figure 14).

Data Alignment and Prosthesis Design

MUA analogs were connected to the OptiSplint scan bodies and a type IV stone verification model was poured to provide a physical checkpoint for prosthesis fit (Figure 15 and Figure 16). Three datasets required alignment: the preoperative esthetic plan (FGTP wax-up and diagnostic scans), the post-surgical soft tissue (scan 3), and the extraoral implant positions (scan 2).

The palatal fiducial marker, present in both scan 1 (preoperative) and scan 3 (post-surgical), served as the common reference: scan 1 was registered to the diagnostic base; scan 3 was matched to scan 1 through the fiducial marker; and scan 2 was aligned using the ScanCaps visible in scan 3. This chain preserved the spatial relationship between the original facially generated plan and the actual implant positions.

Using a computer-aided design software (exocad, exocad GmbH, exocad.com), the functional diagnostic wax-up was directly copied to design the immediate-load prosthesis, preserving the planned tooth positions, occlusal scheme, and vertical dimension.

Prosthesis Delivery and Verification

The immediate-load prosthesis was milled from polymethyl methacrylate (PMMA) with direct-to-MUA connections without the use of titanium bases. Passive fit was first verified on the physical verification model before clinical try-in. Intraoral passive fit was then assessed using the modified Sheffield screw test. No detectable rocking or gap was observed at any abutment interface, and occlusal contacts were consistent with the planned scheme without adjustment. The esthetic outcome was consistent with the facially generated plan (Figure 17 through Figure 20).

The patient’s post-treatment smile confirmed tooth position and gingival display consistent with the facially generated plan (Figure 21). A postoperative panoramic reconstruction from CBCT demonstrated the six maxillary implants and MUAs (Figure 22).

Discussion

The central challenge in FP1 rehabilitation is that accuracy requirements span the entire workflow, yet each stage is typically managed independently. This case report describes a digital workflow that integrates three components to maintain spatial continuity from the facially generated plan through the delivered prosthesis: swappable guided surgery, noncalibrated splinted extraoral scanning, and a palatal fiducial marker.

The threshold for clinically acceptable passive fit remains debatable. Jemt defined 150 micrometers as clinically acceptable, and Sahin and Çehreli argued that absolute passive fit is a theoretical ideal.^15,16 Papaspyridakos et al demonstrated that framework misfit is associated with screw loosening, marginal bone loss, and prosthetic fracture.¹⁷ Abduo and Judge, however, found that negative biological sequelae could not be confirmed from the available evidence.^18,19 In contemporary full-arch prostheses, connection at the MUA level rather than the implant platform positions any residual misfit further from the crestal bone, potentially attenuating peri-implant strain.

In the present case, a laboratory scanner was used for the extraoral scan, consistent with the manufacturer’s recommended protocol. The rationale for laboratory scanning is that it provides higher point density and controlled scanning conditions compared to intraoral scanners, potentially improving the accuracy of the captured implant coordinates. Whether this difference is clinically significant requires further investigation in controlled comparative studies.

In vitro data suggest improved trueness with noncalibrated splinting compared to direct intraoral scanning, although photogrammetry has recorded the lowest deviation values.¹¹ Whether the use of a laboratory scanner as specified by the manufacturer further improves registration accuracy compared to intraoral scanners used extraorally has not been established.^11,12

Implant registration is one of several stages where error accumulates in the prosthetic workflow. Component tolerances at the implant–abutment and abutment–scan body interfaces, digital processing variables such as scan body library alignment, and manufacturing tolerances all contribute to the final fit.²⁰ Improving registration accuracy addresses one stage but does not eliminate the others. This is consistent with the observation by Nagai et al that misfits occurred across all registration methods.¹²

Variables specific to noncalibrated splinting such as polymerization shrinkage of the luting resin and jig deformation during removal also warrant consideration.²¹ These variables have not been quantified. The use of single-use components avoids progressive wear and sterilization-related changes in scan body geometry that affect reusable systems.

This workflow also generates a physical verification model through MUA analogs connected to the scan bodies, providing a tangible checkpoint for verifying fit outside the mouth. This is particularly valuable when cumulative digital errors are difficult to quantify at each stage.

The palatal fiducial marker served a distinct function from registration. While the splinting device captured implant positions, the fiducial marker linked those positions to the preoperative FGTP plan, preserving the planned tooth positions, occlusal scheme, and facial parameters. Papaspyridakos described a similar concept using the dual digital scan technique, where radiopaque markers enable alignment of two post-surgical scans.²² The present workflow extends this principle by bridging presurgical and post-surgical datasets, preserving the original facially generated plan rather than linking two datasets captured after surgery.

In conventional immediate-load workflows, prosthetic design begins after surgery. The clinician must re-establish centric relation in a swollen, anesthetized patient, pick up the prosthesis chairside with acrylic resin, and accept whatever occlusal scheme results. Each of these steps introduces uncontrolled variability. By preserving coordinate system continuity, the present workflow transferred the presurgical design, with its established tooth positions, occlusal contacts, and vertical dimension, directly into the prosthesis, eliminating the need to recreate these parameters under compromised clinical conditions.

Milling with direct-to-MUA connections without titanium bases reduced the number of interfaces in the assembly, each of which represents a potential source of rotational tolerance and vertical discrepancy. While long-term evidence for direct-to-MUA connections in definitive prostheses is still emerging, the rationale is consistent with the cumulative error principle and well suited to an interim prosthesis.

Because this is a single case report, the findings cannot be generalized. Passive fit was assessed using clinical methods, which have limited sensitivity for detecting small misfits.²³ The workflow involves a learning curve across multiple integrated components that may affect reproducibility. Long-term clinical and radiographic follow-up data are needed to assess the biological and mechanical outcomes of this workflow.

Conclusion

This case report describes a digital workflow for immediate full-arch FP1 rehabilitation integrating facially generated treatment planning, swappable fully guided surgery, noncalibrated splinted registration with extraoral laboratory scanning per the manufacturer’s recommended protocol, and fiducial-based design continuity. Further studies are needed to evaluate the accuracy, reproducibility, and long-term clinical outcomes of this approach.

ACKNOWLEDGMENT

The authors thank The Dental Lab (Bristol, Pennsylvania) for laboratory fabrication of the prosthesis, Dimitrios Charoulis, DMD, MSc, PhD, for surgical execution, and Moomen Osama, BDS, for assistance with surgical guide design.

DISCLOSURE

The ArchTracer and OptiSplint system were provided by Digital Arches, Inc. for use in academic cases and research projects. The authors received no financial compensation and had no other conflicts of interest to report.

ABOUT THE AUTHORS

Harshiv Karia, BDS, MPros RCS (Eng)
Assistant Professor of Prosthodontics, Department of Prosthodontics, University of Connecticut School of Dental Medicine, Farmington, Connecticut

Selina Guo, DMD, MS
Adjunct Faculty, Division of Prosthodontics, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania; Associate Prosthodontist, Private Practice, Durham, North Carolina

Markus B. Blatz, DMD, PhD
Professor of Restorative Dentistry, Chair, Department of Preventive and Restorative Sciences, and Assistant Dean, Digital Innovation and Professional Development, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania

Nupur Patel, BDS, DMD, MS
Assistant Professor of Clinical Restorative Dentistry, Division Chief, Division of Prosthodontics, and Director, Postgraduate Prosthodontics Program, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania

Figures and Images

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Figure 1

Pretreatment portrait, frontal smile photograph.

Figure 2

Pretreatment panoramic radiograph. The post-and-core–retained crown at tooth No. 7, visible radiographically, became dislodged before acquisition of the pretreatment portrait shown in Fig 1.

Figure 3

Facially generated smile design using digital smile design/dental treatment planning platform, showing biometric tooth library positioned relative to the patient’s facial landmarks and soft-tissue contours.

Figures 4 & 5

Implant planning software showing prosthetically driven implant positions relative to the functional wax-up. Fig 4: frontal view; Fig 5: occlusal view.

Figure 6A

Guided surgery sequence. Left to right: preoperative situation; guide A for placement of implants at sites Nos. 3, 5, 12, and 14.

Figure 6B

Guided surgery sequence. Left to right: Post-extraction ridge; guide B for placement of implants at sites Nos. 8 and 9.

Figure 7

Maxillary occlusal view of the palatal fiducial marker in situ, captured during the preoperative intraoral scan (scan 1).

Figure 8

Surgical guide A tried in prior to fixation.

Figure 9

Surgical guide A seated and secured with fixation pins.

Figure 10

Surgical guide guide B positioned for implant placement at sites Nos. 8 and 9.

Figure 11

Splinting device implant registration. Horizontal scan bodies on MUAs prior to luting.

Figure 12

Splinting device implant registration. Scan bodies luted to the honeycomb framework with dual-cure composite.

Figure 13

Frontal view of the assembled splinting device with luted scan bodies on the honeycomb framework, prior to extraoral laboratory scanning (scan 2).

Figure 14

The scannable caps seated on the MUAs with the fiducial marker in situ, ready for post-surgical intraoral scan (scan 3).

Figure 15

Stone verification model, occlusal view.

Figure 16

Milled PMMA prosthesis seated on the verification model.

Figure 17

Milled monolithic PMMA prosthesis with direct-to-MUA connections, intaglio surface.

Figure 18

Occlusal view of the prosthesis showing screw-access holes.

Figure 19

Prosthesis delivery, frontal view.

Figure 20

Occlusal view of delivered prosthesis.

Figure 21

Post-treatment portrait, frontal smile photograph.

Figure 22

Post-treatment panoramic reconstruction from CBCT showing the six maxillary implants and MUAs. The immediate-load PMMA prosthesis was not radiopaque and, therefore, not visible radiographically.