Restoring the edentulous arch – John C. Minichetti, DMD, traces the steps to a fixed implant-supported prosthesis
Patients often present to the office with compromised dentitions. RevitaliZe™ Patient Solutions (Zimmer Dental) shall enable the dentist to provide patients with a fixed implant-supported prosthesis in an economical, predictable, and efficient manner. Not only should this be a permanent solution to failing dentitions, but clinicians may provide their patients with full-arch, immediate-load, screw-retained provisional restorations while allowing the implants to fully integrate.
Surgical protocols should allow the surgeon to place implants in positions to avoid critical anatomic structures.
The preoperative CBCT scan illustrates a hopeless maxillary dentition with low maxillary sinuses. The postoperative radiograph shows implant placement angled to avoid the maxillary sinus while increasing the anterior-posterior spread for better occlusal load distribution (Figures 1-2).
Implant placement: The osteotomies are prepared using the appropriate drilling sequence based upon the bone quality of the implant site. The goal is to achieve an adequate insertion torque to allow for immediate loading. The hex on the fixture mount/transfer is used to align the implant correctly for the Angled Tapered Abutments (Figure 3).
Seating the Abutments
Utilization of Tapered Abutments, straight or angled (15º or 30º), should allow the prosthetic screws to be positioned within the prosthesis. The Delivery Tool is used to carry and seat the Angled Tapered Abutments. The 1.25 mm Hex Driver is used to tighten the abutment screws. The Delivery Tools are then removed. Care should be taken as they disengage quickly from the abutment (Figure 4).
Provisionalization: The provisional can be fabricated utilizing the patient’s existing denture or a new immediate denture. It is modified to help create a screw-retained provisional restoration (Figures 5-6).
Healing Caps are threaded onto the Tapered Abutments and the tops marked with a Thompson’s Stick. The denture is tried-in. Ink marks indicate where holes should be drilled through the denture. Temporary Titanium Copings are mounted on the Abutments and are picked up in the denture using resin material with a brush-bead technique. Once the resin has set, the coping screws are loosened and the denture removed. The intaglio surface of the denture is inspected. Any excess resin should be removed and voids filled. The flanges and palate of the denture are removed and the borders rounded to facilitate hygiene. The provisional restoration is finished and polished.
The provisional restoration is placed on the Tapered Abutments and the Coping Screws tightened. Radiographs are taken to verify complete seating (Figures 7-8).
Final restoration: A final impression is made and a soft tissue master model poured (Figure 9). An acrylic verification jig is fabricated and tried-in to help assure an accurate master model (Figure 10). The master model, verification jig and trial setup are sent to the Zimmer Zfx Milling Center with the Zimmer Zfx Bar Order Form.
Bar design and fabrication: The case is scanned on the Zfx™ Evolution Scanner. A virtual design of the bar is created based on the tooth set-up. Once the design is approved, the bar is precision-milled from a solid puck of titanium (Figures 11-12).
The trial setup is transferred to the bar and tried-in. Once all adjustments are made, the prosthesis is processed, finished, and polished. The fixed-detachable restoration is seated on the Tapered Abutments and the Prosthetic Screws tightened. Occlusal adjustments are made as needed (Figure 13). A radiograph is taken to ensure complete seating (Figure 14). The screw access openings are sealed and the patient placed on a recall schedule.