## 2 Case Presentation
### Patients
#### 2.2.3 Case 3  
Implant treatment planned on a 72-year-old male smoker with no reported systemic conditions who previously used removable partial dentures. Panoramic imaging confirmed left and right maxillary sinus pneumonia with atrophied ridges. The height of the residual crestal bone on the panoramic radiography taken before surgery was approximately 1.0 mm in the right maxillary sinus and about 3 mm in the left maxillary sinus (Figure 3a,b). The CBCT taken before surgery confirmed no thickening of the Schneiderian membrane and thin lateral bone present over intended surgical site without the presence of the posterior superior alveolar artery. The maxillary ostium was open left and right (Figure 3c,d). In the lateral window approach performed in the right maxillary sinus, perforation of the Schneiderian membrane did not occur during the sinus floor elevation. The lateral bone lid was removed (Figure 3e). Osteon III (Genoss, Suwon, Korea) was filled in the elevated sinus, and the lateral window site was covered with a collagen membrane (Genoss, Suwon, Korea) (Figure 3f). The mucoperiosteal flap was closed (Figure 3g). In the lateral window approach performed on the left maxillary sinus, the membrane was perforated during sinus floor elevation. The lateral bone lid was pushed up while attached to the sinus membrane (Figure 3h). According to the modified proposed protocol of the open lateral window technique, the sinus floor was filled with Osteon III (Genoss, Suwon, Korea) and the upper part of the lateral window site was opened. Lateral window sites were not covered with a collagen membrane (Figure 3i). The mucoperiosteal flap was closed (Figure 3j). Post-operatively, intermittent nasal bleeding on the perforated sinus side with minor facial swelling and pain were noted for one week. Thereafter, no sinonasal complications were observed. In the coronal image of the CBCT taken immediately after surgery, no displacement of the bone graft particle was observed in the left and right sinus bone grafts (Figure 3k). In the coronal image of the CBCT taken 6 months after surgery, there was little change in the volume of the left and right sinus bone grafts, and minimal membrane thickening was observed only in the left maxillary sinus bone graft. All exposed bone graft substitutes were covered with soft tissue (Figure 3l). Figure 3: Case 3. (**a**) Preoperative panoramic radiograph. The right maxillary sinus was preumatized and the residual alveolar bone was extremely insufficient. On the other hand, the left maxillary sinus was preumatized, but some amount of residual alveolar bone was present; (**b**) Panoramic radiograph of preoperative CBCT scan. There was slight membrane thickening on the sinus floor, but the overall maxillary sinus was healthy; (**c**) Coronal image of preoperative CBCT scan. No blood vessels were observed  
at the site where the lateral window was to be formed, and the ostium was also open; (**d**) Axial image of preoperative CBCT scan. Sinus membrane thickening was not found. Lateral window approach with unintentional split-mouth design. (**e**) In the right maxillary sinus, there was no membrane perforation during sinus floor elevation. The MSA was performed using Osteon III. The lateral window site was covered with a collagen membrane; (**f**) In the left maxillary sinus, the Schneiderian membrane was widely perforated during sinus floor elevation. After bone grafting with Osteon III only on the sinus floor, the upper portion of the lateral window site was opened; (**g**) The flap was closed; (**h**) The left maxillary sinus was widely perforated during sinus floor elevation via the lateral window approach. Lateral bone window was pushed up; (**i**) Bone grafting was performed only on the sinus floor, and the upper lateral window site was opened. Membrane covering was not applied; (**j**) The mucoperiosteal flap was closed. (**k**) Coronal image of CBCT taken immediately after surgery.