3.2.4 Manufacturing: Milling and Rapid Prototypingof the Apparatus
Once the planning session is concluded, the finalized data sets are manufactured with additive and subtractive manufacturing machines. The body of the provisional is milled from a monolithic PMMA material, and a support bar is milled out of medical-grade titanium. All items are manufactured, inspected, and assembled in the dental lab for the final fit, finish, and artisan work .
3.2.5 Laboratory Validation
The production of all finished parts, pieces, and prostheses is quality controlled according to the surgical reports and validated by the quality control team using dry model surgery techniques developed by nSequence® Guided Prosthetics™(nSequence Center for Advanced Dentistry, www.nsequence.com) to ensure that the ostectomy, as well as every osteotomy site, is accurately planned. The surgical report is followed on dry patient models (Fig. 3.2). These steps are necessary to determine if the desired result in the surgical and prosthetic workflow will equal the digital workup that was done in the implant planning software. This process is intended to remove all guesswork from the procedure.
3.2.6 Surgery and Insertion
The surgical technique begins with the validation of the original occlusal bite registration. A clear splint is made to confirm the bite and is tried in the mouth before anesthetizing the patient (Fig. 3.3). Once the original bite is confirmed, the tissue is reflected, leaving the teeth and bone exposed to the borders, which are determined during the virtual planning session. The teeth are extracted, and the proprietary nSequence® bone foundation guide™ is set and fixed in place with anchor pins. Prior to pin fixation, the specific location of the bone foundation guide is verified with a bite index and the opposing arch (Fig. 3.4). The guide struts are then removed, and the intended ostectomy is completed to the level of the guide. At this point the bone is ready to receive the implants. The surgical guide is pin indexed onto the bone foundation guide. Next, the appropriate surgical drilling sequence is followed to complete the osteotomies for implant placement. The implants are then loaded with the guided surgery mounts and placed through the guide to the prescribed and predetermined trajectory, depth, and rotation. The implant mounts and surgical guide are removed, and transmucosal abutments are placed along with pre-cut temporary cylinders. These multi-unit abutments are preselected for height and angulation as per the digital and clinical evaluation. After each one is placed, the prosthesis is positioned to verify proper position and angulation. The copings have also been pre-cut to the correct horizontal dimension for proper fit with the prosthesis. A silicone gasket is positioned onto the bone foundation guide to position the prosthesis at the correct vertical and centric relationship and to preserve the predetermined tissue height. This is done in lieu of a rubber dam to prevent locking in the prosthesis. The long-term provisional (LTP) is then coated with a thin layer of petroleum jelly and placed over the temporary cylinders with a clear occlusal guide to lock in the occlusal position during the pickup process. The patient is instructed to bite into the occlusal registration, and flowable composite material is placed into the facial and buccal holes to pick up the prosthesis to the temporary cylinders (Fig. 3.5). The composite is then light cured. No conversion is necessary due to the precise planning of the implants as they relate to the finished LTP. The bridge is then unscrewed from the multi-unit abutments and contoured with acrylic out of the mouth (Fig. 3.6). Soft-tissue closure is accomplished using 4-0 vicryl suture. Minimal time is required for this step due to the accuracy of the pre-planning and guides [9, 10].
3.2.7 Clear Duplicate Pickup
The next step is to repeat the pickup process with a clear duplicate of the LTP with a new set of temporary copings. The purpose of the clear duplicate is to record the dental implants at abutment level, maintain the patient’s vertical and centric relationship, and translate the aesthetic and orthodontic position of the LTP. The clear duplicate replaces the appointments needed for an open-tray abutment-level impression, verification jig, bite block, and wax try-in all at the time of implant surgery and provisionalization. After the clear duplicate has been used to pick up the second set of pre-cut temporary cylinders, the dental lab technician can then pour up a new abutment-level soft-tissue master cast using abutment-level lab analogues and the same bite registration used to pick up the clear duplicate in the mouth to remount the dental arch to the opposing arch on the original articulator. This allows the dental lab to proceed to the definitive prosthesis, or at the very least mill the final titanium bar and move forward with a wax try-in with teeth.
3.2.8 Occlusal Management
Immediate implant placement and provisionalization offer a potential for premature loading, which could prevent osseointegration. The LTP occlusal contacts can be adjusted to the opposing arch and will produce simultaneous bilateral contact and group function in eccentric movements to help spread the occlusal forces evenly across the arch form.
3.2.9 Final Prosthesis Wax Try-In with Denture Teeth and Titanium-Milled Bar
Using the clear duplicate protocol at stage 1 implant surgery eliminates the need for a conventional abutment-level impression (Fig. 3.13). At this time the final fit, function, phonetics, aesthetics, and tissue contours are checked and recorded.
3.2.10 Final Prosthesis Delivery
The definitive prosthesis is delivered at this patient appointment. It can be made of milled zirconia or of denture teeth and acrylic on a milled titanium bar in addition to other prosthetic designs and materials as per the clinician’s preference .
3.3 Patient Presentation
This guided full-arch immediate-function treatment modality is well demonstrated with the following patient. A 59-year-old female presented to the office with existing maxillary and mandibular teeth in poor condition. She expressed her unhappiness with her teeth both from an aesthetic and functional perspective.
The clinical and CBCT sequential digital diagnostic radiographic evaluation revealed moderate–severe periodontal involvement of the remaining teeth (Figs. 3.7 and 3.8). The clinical evaluation included information regarding maxillary lip length and support, occlusion, restorative space, and phonetics. It also revealed a high smile line that would require maxillary bone reduction to provide appropriate restorative space. A graft-less solution was then presented to the patient that included full-arch immediate teeth in both the maxilla and mandible, all delivered via a fully guided immediate-function approach at one appointment that would include placement of prefabricated, monolithic PMMA bar-supported maxillary and mandibular fixed provisional prostheses.