A Modified Technique for Simplifying Full-Arch Screw-Retained Implant Rehabilitation With Rapid Digital Conversion: A Case Report

Since the advent of dental implants, the landscape of dental implant therapy for full-arch rehabilitation has grown in popularity. Today’s patients have come to anticipate effective treatments and streamlined procedures that ensure comfort and esthetic excellence. In response to these evolving expectations and mounting evidence suggesting that immediate loading of full-arch implant prostheses does not compromise implant longevity,^1,2  dental professionals have embraced the concept of immediate-load provisionalization for implant-supported full-arch prostheses.

Yet, the conventional, analog methods for fabricating these provisional restorations have long presented challenges, which lead to extended chair time and increased potential for complications. Traditional methods for fabricating these provisional restorations have relied on analog techniques that are both technique-sensitive and time-intensive. Typically, this process first involves analog impressions of the immediate post-surgical site, which can be complicated by blood present in the surgical site and potentially interfere with the stability of sutures. Next, these impressions must be poured and be allowed to set in the lab before a resin jig can be created and a preprepared denture hollowed out in the locations of the placed implants. Chairside, the work continues when the denture must be relined on the resin jig intraorally with cold-cure acrylic.³ 

After removing the prosthesis, more work must be done in the lab to remove the denture flanges and fill any voids in the intaglio. Finally, occlusion must be verified and adjusted in a sometimes arduous process, depending on the accuracy of the preprepared immediate denture and the bite during the relining process. These potential inaccuracies allow for parallel inaccuracies in the vertical dimension of occlusion (VDO) and centric relation (CR). The final provisional, consisting of conventional denture acrylic and cold-cure acrylic added in the mouth, can be prone to fracture, mainly if the occlusion needs to be corrected. Overall, although this method has been helpful for providers who aim to offer same-day provisionalization of the immediate full arch, its significant time requirements, back and forth between lab and chairside work, difficulty in achieving the correct occlusion, and risk of complications render this method less than ideal.

In parallel, the rise of digital dentistry has marked a pivotal paradigm shift in the field. Digital tools empower dental practitioners to capture accurate, meticulous impressions while circumventing the need for conventional and often cumbersome impression materials. Digital restoration design empowers providers to exert direct control over the quality of their restorations, allowing for swift fabrication and same-day delivery. This feature resonates with patients seeking efficient and discomfort-free treatment options. The integration of digital dentistry into today’s practice holds the potential to attract new patients by promising efficient treatment and eliminating the discomfort typically associated with conventional analog impression methods. Despite digital dentistry’s remarkable improvements, these techniques remain challenging when restoring the implant-supported full-arch.

To digitally design a provisional prosthesis for immediate postsurgery restoration, obtaining accurate digital impressions of the arch of interest, opposing arch, and occlusal relationship is essential. However, traditional digital scanning has presented several challenges for practitioners. One significant challenge lies in the inaccuracy of edentulous arch scan data. Intraoral scanners often struggle to collect accurate scan data without fixed dentition. Additionally, the presence of blood in the surgical site immediately postprocedure can pose a further challenge to the accuracy of a digital scan. Another challenge of digital scans to restore the implant full arch is capturing the occlusal relationship. The precise scan of the jaw relationship in centric relation (CR) position at the desired vertical dimension is crucial for designing an ideal full-arch implant-supported prosthesis.⁴  However, without fixed dentition remaining in the lower arch, the patient cannot occlude. This renders it difficult to determine the correct vertical dimension in CR. Finally, another major challenge lies in inaccuracies involved in the merging of intraoral and extraoral scans. Research has indicated that extraoral desktop digital scanning of models provides more precise digital files for full-arch implant-supported prostheses.⁵  Therefore, to achieve maximum accuracy for full-arch conversion while maintaining the benefits of digital impression methods, practitioners must combine information from extraoral model scans and intraoral scans. However, this presents a challenge, as digital technology may need help merging 2 scans of an edentulous arch without fixed points of similarity, such as teeth. Typically, digital software merges 2 scans of the same arch by recognizing fixed points, often teeth, present in both scans. However, finding identical fixed points in two scans of an edentulous arch proves to be a genuine challenge. Inaccurate data merging between intraoral and extraoral scans can defeat the goal of accuracy inherent in using extraoral desktop (Lab) scanning to capture a full arch.

Several technologies have been introduced in digital dentistry to address these challenges. Cutting-edge techniques like photogrammetry and facial scanning are examples of such introductions.

Photogrammetry, a method that involves capturing and analyzing a series of photographs to generate precise 3-dimensional (3D) models, has emerged as a promising tool in dentistry.⁶  Photogrammetry improves upon standard digital dental scanning by utilizing fixed physical points to verify scans. Although photogrammetry holds promise in dentistry for creating detailed 3D models, its limitations related to verifiability, complexity, patient cooperation, and other factors should be carefully considered in implementing it within clinical workflows.

Facial scanning is another pivotal application within digital dentistry.⁷  This technique enables capturing a patient’s facial features, allowing for integrating facial esthetics with dental restoration design. By incorporating facial scanning into the treatment workflow, providers can tailor restorations to harmonize with a patient’s unique facial features, enhancing both function and esthetics. However, implementing facial scanning and its integration with dental procedures pose challenges that warrant consideration.

While these advancements hold immense promise, they also introduce certain complexities and challenges. Integrating photogrammetry and facial scanning into full-arch implant-supported rehabilitation aims to enhance the speed and success of treatment while minimizing chair time and complication risk. However, the intricate nature of these techniques requires training, a deep understanding, and increased costs to achieve optimal outcomes.

The following case report introduces an innovative technique for the provisionalization of implant-supported full-arch prostheses, addressing common hurdles associated with analog and digital methodologies. This technique harnesses the strengths of digital approaches while maintaining a grounding in analog verification. With its simplicity, efficacy, and minimal chair time requirement, this approach presents a promising protocol for practitioners striving to deliver efficient and successful implant-supported full-arch treatments, catering to the preferences of both digital- and analog-leaning dentists.

A 50-year-old Caucasian female presented for dental treatment with the chief concern of improving her lower teeth and enhancing the esthetics of her smile. The patient reported no significant medical history. Upon clinical examination, the lower dentition was diagnosed as terminal. Based on this evaluation, the proposed treatment plan included extracting all remaining lower teeth (#20 through #30), strategically placing 6 implants, and restoring the lower arch. The recommended restoration was an FP3 prosthesis—a specialized design that replaces teeth and a segment of the soft tissue, incorporating pink-colored restorative material for highly esthetic results.⁸ 

Based on existing literature highlighting the increased predictability and success rates achieved by guided surgery, a partially guided approach was selected for the upcoming implant surgery.⁹  In today’s clinical landscape, many implant-planning software options are accessible, facilitating the merging of digital scans of a patient’s dentition and soft tissues with DICOM data extracted from cone-beam computerized tomography (CBCT) scans. This convergence of data empowers practitioners to formulate a comprehensive implant positioning strategy, factoring in both bone availability evident in CBCT scans and desired prosthetic tooth alignment discernible in digital scans.

For this patient, an intraoral digital scan of the teeth and soft tissues was performed in addition to a CBCT scan. The resulting files were combined within implant-planning software, and implant positions were planned based on the ideal prosthetic esthetics, midline, vertical dimension, and bone volume. To aid in the surgery, a custom tooth-borne guide was meticulously designed and milled (Figure 1). This guide featured windows for real-time verification of its accurate placement during the procedure. The guide was customized to be compatible with the Ritter guided implant surgery system (Uniqa Dental), which offers a wide range of drill widths and lengths to accommodate all available implant sizes.

To ensure the patient’s comfort during the procedure, local anesthesia was administered (5.1 mL of 4% articaine hydrochloride with 1:100k epinephrine and 3.4 mL of 2% lidocaine with 1:100k epinephrine; 204 milligrams of articaine and 68 milligrams of lidocaine total; 84 micrograms of epinephrine total).

Atraumatic extractions were performed for teeth #20, #21, #23, #26, and #28. Teeth #22, #24, #25, #27, and #31 were retained to support the surgical guide. Once the guide’s stability was confirmed, it was temporarily removed to create a full-thickness flap.

Utilizing the Ritter surgical guide kit, implants were accurately positioned in areas #19, #21, #23, #26, #28, and #30. Each implant site achieved a torque value of 30 Ncm or higher. Subsequently, the remaining teeth were extracted, and alveoplasty was performed to ensure optimal contours of the alveolar ridge. In preparation for soft tissue healing and the future placement of a prosthesis, 4-mm-tall straight multi-unit abutments were affixed to all the implants. The soft tissue flaps were then carefully repositioned using 4–0 chromic gut sutures, employing horizontal mattress and simple interrupted suturing techniques.

Based on the evidence that extraoral model scanning is more accurate for full-arch restoration, a single verified and unmounted working model is required for the arch of interest. This model aids in scanning accuracy and enables the practitioner to verify the fit of the prosthesis. The approach used in this case for functional model fabrication significantly reduced the time spent in the dental chair compared to traditional techniques.

When dealing with full-arch prostheses, precise impressions are crucial, achieved through an open-tray technique that captures impression copings that are bonded together using resin jigs. This guarantees that the final prosthesis fits passively, avoiding unwanted torque forces.¹⁰  However, crafting a resin jig for multiple implants has historically been a time-intensive challenge. Traditionally, this process involved tying floss around all copings and meticulously applying slow-setting GC resin over the floss base using a salt-and-pepper application. The intraoral placement of floss around the copings can be problematic, extending chair time. Alternatively, the jigs could be prepared extraorally between appointments, necessitating additional impressions, patient visits, and chair time for both provider and patient. The innovative approach employed in this instance adeptly surmounts the issues posed by these conventional methods by efficiently fabricating a resin jig chairside.

Open-tray impression copings were fully seated onto the multi-unit abutments and hand tightened. Resin jig “plates” (S plates), 3D printed in advance (using TriMech Form 3B+ 3D printer and dental LT clear resin manufactured by Formlabs Dental), featured apertures that could easily slip over multiple copings and were easily adjusted chairside (Figure 2). Three S plates, placed over the impression copings, provided a foundation for the resin jig, eliminating the need for floss and significantly reducing the resin required to bond copings together. Three S plates were seated over the copings to ensure proximity, and light-cure pattern resin (primopattern) was used to adhere them rigidly (Figure 3 a-d). The use of light-cure resin in place of traditional cold-cure GC resin further reduced the chair time required. With this innovative approach, preparation time for the conventional open-tray jig was decreased to approximately 14 minutes. The impression-taking process itself was also expedited. Polyvinyl siloxane putty and light-body wash were used to encase the jig without using an impression tray (Figure e, f). Once the material was fully set (intraoral setting time of 2 minutes), the copings were unscrewed, and the copings, jig, and impression were removed from the oral cavity.

This impression was used to create an accurate model (Figure 4). Multi-unit lab analogs were connected to the impression copings and hand tightened. Soft tissue material was injected around the coronal portion of each analog and the ridge to create a soft tissue replica. For added stability of the analogs within the model, S plates were seated onto the analogs and bonded together with pattern resin in the same manner as previously described. Finally, the working model was built using cold-cure resin material, as the setting time of this material is a fraction of that of traditional model stone. The entire process of creating the model, from removing the impression from the mouth to the complete setting, lasted approximately 20 minutes.

In this case, a novel approach was implemented to precisely document the jaw relationship, the VDO, and the patient’s midline while seamlessly combining data from intraoral and extraoral scans. This method involved using a custom-made device known as the anterior scanning device (ASD). The ASD served as a stable reference point in the anterior section of the patient’s oral cavity, facilitating consistent occlusion and VDO, midline recording, and easy transfer to and from the working model (Figure 5).

After implants and multi-unit abutments were placed, the ASD was created by relining a prepared 3D printed immediate denture (using Form 3B+ 3D printer and denture teeth resin) over 2 copings in the anterior region of the patient’s mouth. Subsequently, the denture flanges and all teeth posterior to the incisors were removed, leaving only an anterior fixed occlusion point. This ensured the patient possessed a stable and repeatable occlusion and VDO that could be assessed and adjusted. Changes were made to the occlusion or vertical dimension by adding or subtracting material. The midline was also marked on the ASD (Figure 6).

Once perfected, the ASD was digitally scanned intraorally to capture the bite, vertical dimension, and midline (Figure 7). The ASD was then transferred to the working model and scanned extraorally, along with the rest of the model (Figure 8). This dual-scan strategy with the same ASD object effectively tricked the scanner into capturing the working model in occlusion. This yielded precise scans and an accurate occlusion record without needing external mounting of models. This method facilitated a seamless merging of data scanned intraorally, which captured jaw relationships within the patient’s mouth, with data scanned extraorally, which accurately captured implant positions on a verified model.

To capitalize on the improved accuracy of the previously mentioned extraoral desktop scanning technique, an additional scan using the inEos X5 Lab scanner was performed. This scan captured the working model with attached scan bodies. The resulting single STL file, obtained externally, was seamlessly merged with the previous scan from the Primescan intraoral scanner of the model, along with the ASD attached. This merging process, aided by computer software (specifically the InLab software), automatically and precisely aligned the 2 scans of the identical model (see Figure 9). The intraoral scanner’s scan of the model, with the ASD attached to the 2 anterior lab analogs, provided crucial data on occlusion, vertical dimension of occlusion (VDO), and midline alignment. Simultaneously, the extraoral Lab scan of the verified model, featuring scan bodies attached to the lab analogs, contributed valuable information on implant placement and soft tissue characteristics. The resulting merged STL files constituted an exceptionally accurate compilation of all necessary data required for the precise and optimal restoration of the edentulous arch.

Data acquired over the course of this method was then used to design a full-arch FP3 prosthesis (using Exocad software) at the ideal occlusion and with an accurate midline (Figure 10). As this prosthesis was a provisional restoration to be worn during healing, the prosthesis was designed with implant attachments that connect directly to the multi-unit abutments using Rosen screws eliminating the need for cementation of copings into the prosthesis intaglio. The design was then milled in PMMA material using a Roland DWX-53DC dry dental milling machine in the shade chosen at the time of the scan. The gingival portions of the prosthesis were treated with a mix of OPTIGLAZE™ colors from GC America to enhance the esthetics of the gingiva. The mixture included 2 drops of pink (item number 008422), 1 drop of white (item number 008412), and 1 drop of red brown (item number 008417).

Sixteen hours after the surgery, the provisional prosthesis was delivered. The passive fit of the PMMA prosthesis was verified on the master model, ensuring stability without rocking. An intraoral check confirmed the absence of rocking after seating onto the multi-unit abutments. Passive fit is critical in full-arch implant-supported prostheses, as impassivity can exert unwanted forces on implants and negatively affect healing.¹⁰  Once the passivity, midline, occlusion, and shade of the prosthesis were confirmed, the prosthesis was attached to the abutments using Rosen screws. These screws are uniquely designed to allow direct attachment to multi-unit abutments, streamlining the process.¹¹  Given the prosthesis design was based on accurate scan data and incorporated all information needed about VDO, midline, and occlusion, minimal adjustment was necessary at this visit. Screw access channels were temporarily closed with Teflon tape and composite material (Figure 11).

This case report presents a new approach to the digital design of the implant-supported full-arch prosthesis that exceeds analog and digital methods in its efficacy and simplicity for the provider and patient (Figure 12).

Introducing an anterior scanning device exemplified by the anterior segment of a lower printed immediate denture, into the protocol of postsurgical provisionalization eliminates many of the challenges traditionally faced in these procedures, drastically reduces chair time required, and increases the accuracy of gathered data to improve outcomes. In today’s world of implant dentistry, growing numbers of patients are interested in treating ailing and failing dentitions with full-arch implant-supported prostheses. These patients expect efficient treatment, with comfortable and esthetic provisionals, during implant healing. Same or next-day provisionalization of full-arch implant-supported prostheses has traditionally posed many challenges and required an unreasonable amount of time from the provider.

Traditional techniques for restoration of the implant-supported full-arch have been burdensome to the provider, involving painstaking procedures and significant time both chairside and in the lab between visits. Digital dentistry has proven to be a revolutionary introduction to dentistry, promising reduced treatment time and eliminating messy and burdensome traditional techniques. However, even digital dentistry needs to catch up regarding the immediate provisionalization of the implant-supported full arch. Inaccuracies present in full-arch scan data, merging of intraoral and extraoral scans, and recording of VDO, occlusion, and midline into the scan have rendered this process difficult for providers striving to complete this process digitally.

In this innovative technique, however, these challenges are overcome by using an anterior scanning device (ASD). The ASD gives the patient a repeatable, fixed occlusal point that can record VDO, jaw relationship, and midline. This ASD also improves the accuracy of digital scans for the full arch, making merging intraoral and extraoral scans seamless. Easily transferred from the patient’s oral cavity to a verified model, the ASD ingeniously “tricks” the scanner into continuing an intraoral scan extraorally. Extraorally, a precise model is quickly and clearly captured away from saliva and blood in the mouth, yet still in the correct occlusal position. This meticulous scan can then be merged with extraoral Lab scan data to increase the data’s accuracy further. This technique potentially supersedes analog and digital methods for converting the implant-supported full arch, as it combines their best aspects and avoids their pitfalls. Using a verified model, it draws on the strengths of analog practices. At the same time, its digital approach to obtaining data and designing the restoration utilizes the full potential of modern dental tools to enhance accuracy and eliminate messy materials.

While this case report describes the application of this method on the day of surgery and for restoration with an FP3 prosthesis, this has a much broader application potential. This innovative and efficient approach to obtaining accurate digital data can be applied to any full-arch implant restoration. Further, this method can be utilized at any point in the healing period. As described in this report, this method is helpful for immediately loading the full arch. However, it is equally applicable shortly after implant placement for early loading, or even after full healing time is complete, for final restoration in a delayed fashion. The versatility of this method also applies to the details of model fabrication described in this case. As mentioned, this technique requires a single verified model of the arch of interest for maximum accuracy. An efficient yet accurate approach to fabricating this working model was described in this case report. However, this model can be fabricated using any method the practitioner prefers. This underscores the potential of this method. It presents an efficient, seamless, and versatile approach to restoration of the implant full arch, applicable to various cases at any point in the postsurgical healing process.

The protocol described in this case study presents an efficient and effective method for next-day provisionalization of full-arch implant-supported prostheses via digital scanning and design. This method eliminates many technique-sensitive aspects of traditional methods for restoring the implant-supported full arch. Meanwhile, it also preserves the best qualities of conventional analog and digital methods, creating an enhanced technique that both digital- and analog-preferring dentists can accept.

An ASD records several pieces of critical information for the case in one step and enables accurate data merging from intraoral and extraoral sources. This protocol applies to a large population of patients, who are more often than ever interested in undergoing efficient treatment for full-arch replacement of ailing and failing teeth. This method can be applied to a wide range of full-arch implant cases and at any time during healing, beginning from immediate postimplant placement and extending to the completion of a delayed healing time. Due to the simplicity of the protocol, this method is achievable by both specialists and general dentists or used in conjunction as part of collaborative interspecialty patient treatment.

The current literature points to extraoral desktop model scanning as the more accurate scanning method for full-arch restorations.⁵  Techniques such as photogrammetry and facial scanning have been introduced to increase the accuracy of intraoral digital scanning.^6,7  Still, these methods incorporate additional expense, time, and learning curves into the process. In the protocol described in this case study, the materials included are low cost, efficient, easy to utilize, and highly accurate. With continued improvements to intraoral scanners in the coming years, the accuracy of scanning extraoral models with intraoral scanners may one day be improved to match that of extraoral model scanning with desktop Lab scanners.

This article is dedicated to the memory of Fayez Salloum, Dr. Salloum’s father, whose words inspired the author to share knowledge as a means of growth. Dr. Salloum expresses his deep gratitude for his father’s influence in shaping his character and instilling in him the enduring values of diligence, dedication, and generosity.