We report the case of a 55-year-old male patient with a highly atrophic maxilla and the wish for further treatment in 2019. The patient had no allergies or diseases and was in good health. Due to the extensive bone volume losses (according to Terheyden bone loss classification stage three), the surgeon decided to use two CAD/CAM manufactured allogeneic bone blocks and two eternal sinus lifts to regain enough bone for the planned implantation. Therefore, during the first appointment, an intraoral photo status, an orthopantomography (OPT), and a cone beam computed tomography (CBCT) in DICOM format were taken (Fig. 1). The gained DICOM data was sent to the manufacturer (Zimmer Biomet Dental, USA) where the individual blocks were made (Fig. 2). To further enhance the fitting of the blocks on the alveolar ridge, the surgeon as well as the manufacturer designed the block with a special overlapping “J-shape-design” (Fig. 3). After the surgeon was satisfied with the block design, the manufacturer fabricated the two allogeneic bone blocks using (Puros® Allograft, Zimmer Biomet Dental, USA) CAD/CAM technology and further processed it with the Tutoplast® process [23]. The grafts were processed with alkaline, osmotic, oxidative, solvent, and irradiation treatment to eliminate the possibility of disease transmission without compromising its biological or mechanical properties.
After delivery of the allogeneic bone grafts as well as two three-dimensional models of the upper maxilla, the second appointment took place. The patient was given a 0.12% CHX mouth rinsing solution (GSK-Gebro Consumer Healthcare, Austria) and subsequently was locally anesthetized with Ultracain D-S forte with added epinephrine 1:100000 (Sanofi, France). An incision along the alveolar ridge of the maxilla was performed and a mucoperiosteal flap in both quadrants was created to allow a better overview for the later application of the bone blocks.
Then, the surgeon performed two external sinus lifts in both quadrants of the maxilla in the molar and premolar regions. One sinus window on each side was created using the modified Caldwell-Luc approach, and then, the Schneiderian membranes were carefully elevated with a sinus curette. The surgeon filled the sinus cavities with cancellous allogeneic bone particulates (Puros® Cancellous Particulate Allograft, Zimmer Biomet Dental, USA). After that, the first try-in of the CAD/CAM manufactured allogeneic bone blocks was performed. The two blocks seemed to fit the defect areas perfectly and were therefore considered suitable for further placement. The blocks were fixated to the alveolar ridge using osteosynthesis screws (Craniofacial Modular Fixation System, DePuy Synthes, Johnson & Johnson, USA) which were made out of corrosion-resistant medical steel (Fig. 4). Then, the transition between the bone blocks and the alveolar ridge was smoothed and a bovine pericardial membrane (CopiOs® Zimmer Biomet Dental, USA) was subsequently placed over the augmented area in sense of a guided bone regeneration. Finally, the mucoperiosteal flap was readapted and closed with non-resorbable polypropylene sutures 4-0 (Ethicon, Johnson & Johnson, USA) with a single button and mattress sutures in a saliva-proof and tension-free manner.
After a healing period of 7 months following the augmentation, the third appointment for further implantation took place. With the same procedure as last time, the patient was anesthetized, a mucoperiosteal flap was created and six implants (Straumann® BLX, Switzerland) in the sense of all-on-six were placed in regions 11, 13, 15, 21, 23, and 25. The implant diameters and lengths were 3.75×10mm for regions 11, 13, 21, 23, and 3.75×12mm for regions 15 and 25. The implants showed proper primary stability (>35 Ncm). The mucoperiosteal flap was sutured tension-free with non-resorbable polypropylene sutures 4-0 (Ethicon, Johnson & Johnson, USA). After the operation, an OPT was taken to show the position of the implant placement in coordination with the digitally generated bone blocks (Fig. 4).
After an additional healing time of 7 months, the patient had an appointment for impression-taking of the situation. The impressions were used to create the definitive restoration of the maxilla. In the meantime, the patient was provided with a removable complete denture for the maxilla and was monitored every 3 months to prevent the risk of pressure marks of the denture.
Finally, 19 months after the bilateral bone block augmentation, the patient was provided with a screw-retained prosthetic construction with a milled titanium framework with acrylic veneers (Fig. 4).
