Digital technologies like guided implant placement and computer-assisted prosthetic planning and manufacturing have the capacity to significantly facilitate diagnosis, treatment planning and surgical procedures, and therefore provide treatments in a more predictable and efficient way^{5, 6}. In particular, surgically advanced procedures like full arch reconstructions may significantly benefit from these advantages, which may reduce chair time and invasiveness for the patient^{5, 7}.

Access to digital technologies may be hindered by financial and time constraints, as well as by a steep learning curve that has been associated with such technologies^{8, 9}. Recently, digital workflows have become available as part of an outsourced service: Smile in a BoxTM. This may help practitioners using conventional workflows readily benefit from the advantages of digital technologies without first having to overcome the hurdles associated with their first-time access.

This case report describes a successful immediate conversion of a conventional complete denture into an immediate full arch restoration by applying an outsourced fully digital workflow provided by Smile in a Box^TM. The application of a Straumann® Pro Arch protocol, combined with Smile in a Box^TM, allowed us to readily access a fully digital workflow that could efficiently be integrated into our conventional prosthetic workflow, providing a highly satisfying clinical result.

Initial situation

A 65-year-old fully edentulous male restored with conventional acrylic full dentures presented in our clinic complaining of unsatisfactory mandibular denture retention and associated problems, including poor speech and masticatory function, specifically related to his lower denture. Clinical examination revealed a round to knife-edge mandibular ridge form, and adequate vertical but inadequate horizontal bone availability specifically in the posterior aspects¹⁰.

The diagnostic panoramic radiograph revealed a mandibular arch presenting with a moderate atrophy of class III to IV, with a fair volume of relatively dense cortical bone of type I – II present in the interforaminal area.

The patient had well-controlled type II diabetes and well-controlled hypertension. No systemic or local risk factors or contraindications that would have excluded the patient from implant treatment were identified. After a thorough discussion about the various treatment options and their advantages and limitations, the patient expressed his preference for an implant-supported mandibular restoration combined with a new conventional full upper denture.

Treatment planning

The treatment strategy included the determination of the maxillomandibular relationship, occlusal vertical dimension and teeth position using conventional complete denture techniques, which were used as prosthetic references for the delivery of the fixed mandibular restoration¹¹. Fig. 3 shows the corresponding maxillary and mandibular occlusal rims on master casts, the prosthetic wax-up and the final conventional acrylic dentures.

Data acquisition for the generation of the virtual patient model was based on dual cone beam computed tomography (CBCT) scans using a radiographic template that was prepared based on the new conventional dentures (Fig. 5) ¹². Equidistant radiopaque fiducial markers (gutta-percha) were positioned along the vestibular rim of the template to allow for the precise matching of the individual DICOM data sets of scans of the patient wearing the radiographic template and that of the template alone.

Conversion of the lower mandibular conventional denture into a fixed implant-supported restoration was accomplished using an outsourced fully digital workflow (Straumann® Smile in a Box^TM). DICOM data sets from dual CBCT scans were used by the Smile in the Box^TM team to establish the virtual patient model. Based on this model, the team explored possible concepts for the implant restoration and associated surgical protocols and surgical guides using coDiagnostiX® surgical planning software. Subsequently, the team designed the immediate provisional restoration using CARES® Visual software. Specific details and aspects of the planned restorations and treatment concepts were explored, validated and approved during virtual planning sessions between the Smile in a Box^TM team and the clinicians. Following approval, the surgical templates, provisional restoration, implants, as well as any additional prosthetic parts and surgical tools required for the full surgical treatment procedure, were conveniently assembled by the Straumann team and delivered in an all-in-one shipment to our clinic.

Specifically, the plan involved a 1st molar-to-1st molar prosthetic restoration supported by four interforaminal BLX Roxolid® SLActive® implants consisting of two anterior Ø 3.75 x 12 mm implants in positions 32 and 42, and two Ø 4.75 x 12 mm implants in positions 35 and 45. Inclination of the posterior implants by 17 degrees increased the A/P spread and helped to reduce the distal prosthetic cantilevers, obviating the need for any augmentative procedures (Fig. 6)¹³.

The planned surgical templates consisted of a combination of a pin guide for pin fixation and a surgical guide for implant placement. Both guides were supported by crestal mucosa and four anchoring pins in positions 36, 33, 43 and 46 (Fig. 7).

Surgical procedure

Surgery was carried out under local infiltration anesthesia. Figures 8 and 9 show the intraoral conditions prior to treatment on the day of surgery, and after placement of the pin guide, respectively. Proper seating and positioning of the mandibular pin guide on the alveolar crest was verified with the upper radiographic template in occlusion (Fig. 9). After the correct positioning of the anchoring pins, the pin guide was removed and the surgical guide was placed and secured with anchoring pins (Fig. 10).

Osteotomy preparation was carried out according to the corresponding instructions and surgical protocols as provided by coDiagnostiX®, and included the preparation of a defined access profile to the alveolar bone with a mucosa punch (Ø 4.7mm), flattening of the alveolar ridge with a milling cutter (mesial Ø 3.5 mm, distal Ø 4.2 mm) and pilot drilling with a Ø 2.2. mm pilot VeloDrillTM at 800 rpm (Fig. 11). All osteotomies were prepared to a final diameter of Ø 2.8 mm with the aim of achieving good primary stability and retaining a high degree of surgical flexibility^14–16. Straumann® BLX implants were placed using a motorized handpiece followed by manual insertion and final verification of appropriate insertion torque of > 35 Ncm (Fig. 12).

Prosthetic procedure

The surgical procedure was directly followed by immediate provisionalization. Fig. 13 illustrates (from left to right) the situation after implant placement, followed by installation of screw-retained abutments (SRAs) with a torque of 35 Ncm, and after try-in and pin fixation of the temporary provisional. An optimal fit of the pre-manufactured provisional restoration with the prosthetic emergence profiles of the implant restoration was achieved.

Next, titanium copings were adjusted in length to suit the contours of the provisional, and mounted on the implant restoration. Subsequently, the immediate provisional was mounted, secured with anchoring pins and fixed to the titanium copings using flowable composite (Fig. 14).

Treatment outcomes

Fig. 16 illustrates the successful delivery of the prosthesis on the day of surgery. Optimal results were achieved in terms of functionality and esthetics thanks to the digital pre-planning. There was satisfactory occlusal fit with the maxillary complete denture, and no adjustments were required. The patient showed optimal immediate phonetic and functional adaptation to the new provisional and reported that he was very pleased and satisfied with the esthetic and functional result of the immediate provisional.

Discussion

The presented case illustrates the conversion of a mandibular conventional complete denture into an implant-supported fixed full arch restoration using Straumann® Pro Arch and Straumann® Smile in a Box^TM. Conversion of the existing restoration included the delivery of a new set of stable conventional dentures after re-establishing the maxillomandibular relationships and occlusal vertical dimensions by conventional laboratory workflows.

Smile in a Box^TM facilitated quick and easy access to a digital workflow, with the associated advantages of precise prosthetically driven implant planning, guided flapless implant placement and immediate restoration^{6, 8}. The outsourced workflow could be perfectly integrated into our existing clinical and prosthetic set-up. Key success criteria that contributed to a seamless integration of the outsourced workflows and an optimal result for the patient included appropriate and accurate data collection and communication with the Smile in a Box^TM team. This allowed for a straightforward definition and approval of the virtual planning models based on the visualizations from coDiagnostiX® and CARES® Visual provided by the team. Efficient communication with the team also ensured that all other critical factors related to immediate implant placement and immediate restoration were appropriately addressed, without having to overcome the initial learning curves associated with digital techniques⁸.

Conclusion

The application of Smile in a Box^TM on a Straumann® Pro Arch protocol allowed for convenient and seamless access to a digital workflow for the immediate conversion of a conventional complete denture into a fixed full arch restoration.