## 2 Case Study  
A 70-year-old patient presented with a forehead defect, approximately 3 cm in diameter (Figures 1 and 2). He reported that the lesion around the glabella had developed about six months before first appointment at the Maxillo-Facial Clinic. At that time, due to the COVID-19 pandemic, he was wearing a visor, which pressed the forehead [6]. The lesion resembled a carbuncle [7] and the patient was referred to a dermatologist; however, his local condition had since deteriorated. He gave a history of myeloid leukemia diagnosed 6 years earlier. The disease had been regularly monitored and treated with Imatinib. A sample of secretion from the frontal sinus was positive for _Staphylococcus aureus_. An antibiogram test was performed to administer the right antibiotic. Histopathological examination showed chronic inflammation of the frontal sinus. The patient underwent a non-contrast CT scan (Revolution Evo system, 64 rows, GEHealthcare). The obtained image revealed a defect of bone and soft tissue in the glabella area, about 3 cm in diameter, and an overgrowth of bone tissue across the entire width of the nasofrontal duct. (Figure 3A,B)  
Figure 1: Initial condition. Figure 2: Condition pro the procedure. At a medical case meeting, a team of laryngology and maxillofacial surgery specialists made the decision to apply a two-stage procedure. The first stage was aimed at achieving physiological drainage and ventilation of the sinus. The second stage was planned to be performed after approximately 10-14 days in order to reconstruct the cavity of the glabella. The patient was presented with the following treatment options:  
- [PERSON]'s double pedicle flap [8] Figure 4  
- radial forearm flap [9]  
- temporoporarietal fascia free flap [10]  
During the procedure, the ethmoid bone was resected bilaterally and the hypertrophic mucosa was removed. Hypertrophic lesions were resected from the left and right frontal sinus drainage pathways and the hypertrophic mucosa was removed. Using a cutter, the bone margin of the anterior wall of the right and left frontal sinuses and the ethmoid bone were removed bilaterally, along with a fragment of the nasal septum. Two drains were inserted bilaterally through the anterior wall of the frontal defect and brought out through the nasal meatuses. Tampons were inserted anteriorly into both nasal meatuses (Figures 5 and 6). Figure 4: [PERSON]’s flap diagram on a plastic model of the skull. (**A**) Defect and the incision site-front view. (**B**) Defect and the incision site-lateral view. (**C**) Inserting the flap to replace the defect. (**D**) Final model. Figure 3: (**A**) Condition after the first CT scan-sagittal plane. (**B**) Condition after the first CT scan-transverse plane. (**C**) CT scan 14 days after first procedure-sagittal plane. (**D**) CT scan 14 days after first procedure-transverse plane. Fourteen days following the laryngeal procedure, the created canal was found to be overgrown and the nasofrontal duct lacked patency. A repeat CT scan of the facial part of the cranium confirmed that the canal was overgrown with soft tissue compared with the previous examination (Figure 3C,D). Another medical case meeting was held, this time with specialists in neurosurgery and maxillofacial surgery. Frontal sinus obliteration was planned: however, a defect was noted in the posterior wall of the frontal sinus (Figure 7) together with a 10 mm-wide fluid space in the temporoorietal region (Figure 8) with a density of 15 Hounsfield units, a dilated Sylvian fissure. Therefore frontal sinus cranialization was eventually proposed. However, the patient refused to undergo the procedures due to complications that developed during the initial stages and the uncertain prognosis. A team of oral and maxillofacial surgeons created a 3D-printed acrylic \"space maintainer\" through segmentation of bone structures. (Figure 9A). In the next step, two maintainers were designed, one (No. 1) with a split end intended to fit the right and left nasal passages (Figure 9B,C) and another (No.