The Root Guide by Drs. N. Cory Glenn and Daniel Domingue

A socket-indexed, prosthetically driven guided-surgery workflow for maxillary FP1 full-arch rehabilitation

by Drs. N. Cory Glenn and Daniel Domingue

FP1 full-arch therapy in a high-smileline patient requires accurate transfer of more than implant positions. The Root Guide technique uses the patient’s preoperative root anatomy as a socket index to carry the virtual prosthetic plan into surgery after the teeth have been removed.


Introduction
Full-arch implant treatment is often described as prosthetically driven. In an FP1 reconstruction, however, the case must also be tissue driven. The implants must emerge through the planned crowns in positions that permit natural-looking cervical contours, and the gingival architecture and underlying bone must sit where the final prosthesis requires them. Those demands become especially unforgiving in a patient with a high smile line, because even small discrepancies in tooth position or soft-tissue level can show in the finished smile.

The authors previously reported a similar FP1 case using a staged digital workflow that combined a tooth-supported guide, a scalloped bone-reduction guide, and a stackable implant guide.¹ That approach successfully transferred a facially driven digital plan to surgery, but the guide was complex to plan and fabricate, and it required extensive flaps to seat on the alveolar bone.

The authors developed the Root Guide (patent pending) as an alternative guided approach. It offers a much simpler design process; easy, stable seating without extensive flaps or retention pins; better drilling accuracy in sloped socket walls; and the ability to visualize proposed tooth positions in situ during surgery. Unlike most guides, which seat on remaining teeth, soft tissue, or the external bone surfaces of the jaw, the Root Guide engages the walls of fresh extraction sockets.

The following case demonstrates the technique in an adult female patient treated with full-mouth extractions, a maxillary FP1 restoration, and a mandibular FP2 restoration. Because the Root Guide was used primarily to solve the aesthetic and surgical demands of the maxillary arch, this article focuses on the maxillary digital planning, guide design, and surgical execution.


Case report
Diagnosis and treatment rationale
The patient presented with a terminal dentition and extensive caries. Many of the posterior teeth demonstrated circumferential, advanced decay that would have required significant restorative, endodontic, and periodontal intervention to retain. Several anterior teeth were potentially restorable, but their prognosis could not be considered independently from the patient’s primary aesthetic concern: a very high smile line with excessive gingival display associated with vertical maxillary excess (Fig. 1).

A comprehensive restorative option would have required treatment of the posterior disease as well as major alteration of the anterior tooth and gingival positions. To place the maxillary incisal edges and occlusal plane at the desired level, the anterior teeth would have required substantial preparation and apical repositioning of the gingival margins and supporting bone. The cumulative treatment burden, prognosis, and aesthetic goals were discussed with the patient, and after considering the alternatives she elected full-arch implant rehabilitation. The final plan was an FP1 restoration in the maxilla and an FP2 restoration in the mandible.

Facially driven digital planning
The aesthetic plan began with the face rather than the implants. A digital smile design and diagnostic wax-up established the desired incisal edge position, occlusal plane, tooth proportions, and gingival architecture. In this patient, the maxillary incisal edges and occlusal plane needed to move apically, and the planned teeth were lengthened vertically so that less gingiva would be displayed during a full smile (Fig. 2).

Fig. 1: Preoperative condition. The patient presented with a terminal dentition, extensive posterior caries, vertical maxillary excess, and a high smile line with excessive gingival display.

Fig. 2: Digital smile design and wax-up. The planned incisal edges and maxillary occlusal plane were moved apically, and tooth proportions were modified to reduce the amount of gingiva displayed in the smile.

The wax-up made it clear that achieving the desired FP1 result would require both soft-tissue reduction and osseous contouring. The planned gingival margins were not an intraoperative estimate: They were defined in the virtual prosthetic design first, and the surgical workflow was then built around transferring those positions accurately to the patient.

Implant planning backward from the wax-up
The cone beam computed tomography (CBCT) scan, intraoral scan data, and digital wax-up were merged in Blue Sky Plan. Six maxillary implants were positioned from the final tooth positions backward, with depth and angulation selected to provide favorable emergence through the planned crowns and adequate prosthetic support (Fig. 3).

The existing dentition remained visible during planning so that the relationship among the current teeth, future teeth, alveolar bone, and planned implants could be evaluated simultaneously. Because the desired maxillary tooth positions were several millimeters apical to the existing tooth positions, the implants had to be placed considerably deeper subcrestally, and it was clear that bone reduction would be needed to create a scalloped bone form approximately 3 mm apical to the proposed tooth positions.

Maintaining the digital reference through extraction
Another challenge in immediate full-arch treatment is registration. Once the remaining teeth are removed, a final intraoral scan can no longer be stitched directly to the preoperative dentition using those teeth as common landmarks. To preserve a reliable bridge between the preoperative and postoperative datasets, the two most distal maxillary implants were placed first, with a conventional tooth-supported guide designed in Blue Sky Plan. Tooth No. 3 was virtually removed in the guide design to provide access (Fig. 4).

Fig. 3: Six maxillary implants were planned prosthetically from the digital wax-up, with implant depth and angulation selected to support an FP1 emergence profile.

Fig. 4: The two distal implants were planned for initial placement with a tooth-supported guide. An intermediate intraoral scan then linked those implants to the preoperative dataset through the teeth that were still present.

After those posterior implants were placed, an intermediate intraoral scan was obtained while the remaining teeth were still present. That scan contained two critical sets of common data: the remaining natural teeth, which tied the scan to the preoperative record, and the two posterior implants, which would remain after the rest of the teeth were extracted.

Following extraction and placement of the remaining implants, the final intraoral scan could therefore be related back to the preoperative plan through the two common posterior implant positions. This staged scan strategy preserved the digital chain of reference while the dentition itself was being removed.


Root Guide design
The Root Guide is designed entirely in Blue Sky Plan by combining the digital prosthetic wax-up with the patient’s preoperative root anatomy. In this case, the maxillary roots were segmented from the CBCT and merged with the planned teeth and pontics from the wax-up to form a single solid object. However, because of the divergent anatomy of the roots, this object would be impossible to insert back into the sockets. A blockout model was therefore generated to remove the interfering undercuts and establish a common path of insertion (Fig. 5a).

Subtracting the blockout from the combined root-and-wax-up design produced a single roundhouse guide with root-shaped extensions that could seat into the post-extraction sockets along one path of draw. Guide tubes corresponding to the remaining planned osteotomies were then incorporated into the design (Fig. 5b). In practical terms, the patient’s roots become the indexing anatomy, while the coronal portion of the guide reproduces the future tooth and gingival positions.

Fig. 5a–b: Root Guide design. (A) The segmented roots were merged with the prosthetic setup and an undercut blockout model was generated. (B) The blockout was subtracted to create a shared path of draw, and guide tubes were added to the socket-indexed prosthetic form.

The final guide was exported and 3D printed for surgery (Fig. 6). Because the planned cervical contours are physically present on the guide, the device carries more information than implant trajectories alone. It also provides a direct visual and tactile reference for the intended gingival margin positions and, indirectly, for the osseous correction required to support those margins.


Surgical execution
Socket seating and gingival reduction
After the remaining maxillary teeth were removed, the Root Guide was seated into the fresh extraction sockets. The common path of draw allowed the root extensions to enter the sockets without binding despite the divergent original root anatomy, and seating the guide immediately restored the relationship between the surgical field and the digital prosthetic plan.

The patient required approximately 2 to 3 mm of gingival reduction around the maxillary arch. Because the guide reproduced the planned cervical contours, the proposed gingival margins were visible directly in the mouth. The gingivectomy could therefore be performed to the cervical outline of the Root Guide rather than estimated from the preoperative gingival margin (Fig. 7).

Fig. 6: The 3D-printed Root Guide. Root-shaped extensions index the guide into the extraction sockets; the coronal form represents the planned prosthetic contours and contains the implant guide tubes.

Fig. 7: After extraction, the Root Guide was seated into the sockets. The planned cervical contours provided a direct reference for the gingivectomy and transfer of the future gingival margins.

Guided osteotomies
With the guide seated, the osteotomies for the remaining implants were prepared through the integrated guide tubes using keyless guided drills (Fig. 8). Implant positions planned from the wax-up could therefore be transferred after the teeth were no longer present, without switching to a separate tooth- or bone-supported reference for the remaining sites.

Fig. 8: Osteotomies for the remaining maxillary implants were prepared through the Root Guide with keyless guided drills.

Osseous reduction from the prosthetic gingival plan
Bone reduction was also required to create the planned gingival architecture and reduce the excessive gingival display, and the Root Guide provided a simple way to transfer that target to the alveolus. With the guide seated and the flap reflected, a sterile pencil was used to mark the bone approximately 3 mm apical to the planned prosthetic cervical contours. The guide was then removed and the bone contoured to the transferred line (Figs. 9a–b).

This sequence is one of the most useful aspects of the technique. The surgeon is not reducing bone to a generic horizontal level or to an arbitrary distance from the preoperative teeth; the reduction is referenced to the scalloped gingival architecture of the actual planned FP1 restoration.

Fig. 9a–b: Osseous reduction. (A) The planned cervical contours were used to mark the bone approximately 3 mm apical to the intended gingival margins. (B) The guide was removed and the maxillary bone was contoured to the transferred line before final digital records were obtained.

Digital conversion and provisionalization
Following implant placement and osseous contouring, final intraoral scans and a photogrammetry scan were obtained, and the data were brought into Exocad for the immediate conversion. Because the prosthetic wax-up had been completed preoperatively, there was no need to design the immediate-load prosthesis from scratch. Instead, the existing wax-up was converted to the implant-supported prosthesis, Vortex screw channels were incorporated and angulated into the available restorative volume, and the intaglio was refined (Fig. 10).

The patient returned the following morning for delivery of the 3D-printed maxillary FP1 provisional (Fig. 11). Because limited suturing had been performed, the provisional seated passively without a second surgical procedure. The provisional itself served as a full-arch tissue-forming restoration, allowing the soft tissue to heal against the contours that had already been established in the digital plan.

Fig. 10: Immediate digital conversion in Exocad. The preoperative FP1 wax-up was related to the postoperative implant records, screw channels were incorporated, and the intaglio was refined for the provisional restoration.

Fig. 11: Next-day delivery of the 3D-printed maxillary FP1 provisional. The planned cervical contours functioned as a tissue-forming provisional during healing.

Definitive restorations and outcome
After several months of healing, the multi-unit abutments were retorqued and new photogrammetry records were obtained. The definitive restorations were fabricated in zirconia by Louisiana Dental Implant Lab. The final prosthetic classification was FP1 in the maxilla and FP2 in the mandible. The maxillary result reproduced the planned tooth position while markedly reducing the excessive gingival display that had been one of the patient’s chief concerns (Fig. 12).

Fig. 12a–b: Definitive outcome. Left: definitive intraoral zirconia restorations after healing. Right: preoperative and postoperative facial views demonstrating the change in smile line and gingival display.

Conclusion
This case illustrates a simple principle: A digital plan is only valuable if its critical references survive the transition to surgery. In a high-smile-line FP1 case, those references include not only implant positions but also tooth position, gingival architecture, and the bone level required to support the planned emergence profile. The principle may be simple, but the surgical and prosthetic execution is not. The authors have found this guide design and technique to be one of the most effective ways to achieve the desired result, particularly for FP1 restorations.

There are important limitations. The accuracy of the Root Guide depends on accurate CBCT-to-scan registration, root segmentation, guide design, printing, and complete seating. It is not an option when no extraction sites are available, or when the available sites are too few or inadequately spaced to provide a stable index. It is also less suitable when more extensive bone reduction is required, generally greater than 4 to 5 mm, as is often the case with an FP3 approach. In appropriate cases, however, the Root Guide can be invaluable.

By combining the digital wax-up with segmented root anatomy and creating a shared path of insertion, the Root Guide uses the patient’s extraction sockets to re-establish the prosthetic plan after the teeth are removed. In this case, the same guide helped transfer the planned gingival margins, guide the remaining osteotomies, and establish the reference for osseous correction. The result was a maxillary FP1 restoration that addressed both the terminal dentition and the patient’s excessive gingival display while maintaining continuity from virtual planning to definitive treatment.

Reference
1. Glenn NC, Domingue D. FP1 full-arch implant restorations. Dentistry Today. March 2025:58–62.

Dr. Cory Glenn is a dentist, speaker, trainer and tech developer residing in Winchester, Tennessee. He is an avid speaker on digital dentistry worldwide and operates a training center in his hometown, where he imparts digital workflows and techniques to fellow dentists. Website: coryglenn.org

Dr. Daniel Domingue received his bachelor’s degree from Louisiana State University in Baton Rouge and his DDS from the LSU School of Dentistry in New Orleans. Domingue was awarded the Certificate of Achievement from the American Academy of Implant Dentistry and a fellowship from the International Congress of Oral Implantologists, and received an associate fellowship from the American Academy of Implant Dentistry. He was also awarded Diplomate from the American Board of Oral Implantology. In addition, Domingue is a member of the American Dental Association, the Acadiana District Dental Association and the American Academy of General Dentistry.

Dr. Glenn and Dr. Domingue are the developers of the Root Guide technique, which is patent pending.