## 3 Discussion  
The laser-melted metal substructure ensured the necessary rigidity of the connection to the eyeglasses and the minimum thickness to work in the reduced space between the external surface of the prosthesis and the underlining residual skin tissues of the nasal pyramid. The metal females of the connection screws, resin-splinted to the eyeglasses by polymethyl methacrylate (PMMA), allowed for tightening of the fixing screws with a 15 N torque without risk of dislodgment during the long-term follow-up. The option of direct relining to obtain the final silicone prosthesis allowed for the creation of a facial prosthesis  
Figure 10: Final result. Figure 9: Color matching and try-in of the resin prototype. with an extremely thin silicone thickness at the borders, which resulted in very low weight and very high elasticity of the external margins (Figure 10). The low weight determined minimal loading of the substructure at the screw connection; the high elasticity allowed for the optimal elastic adaptation of the prosthetic margins to the facial skin during its function. For this study, having only the patient imaging at the beginning of the rehabilitation treatment (i.e., after resection, with the nose and upper lip already missing), we based the facial reconstruction on the intact face of the patient's daughter as a reference. In detail, we combined the patient's surface scan after resection with the surface scan of the daughter, and the resulting combination (scan REF) was taken as the reference anatomy to aim for nasal-facial rehabilitation. At the end of the rehabilitation, we compared the achieved results, i.e., the final facial scan of the patient wearing the prosthesis (scan_POST) with scan_REF, via a deviation analysis (distance mapping) performed using CloudCompare software (Figure 11). As a result, the maximum deviations (about 4 mm) occurred in correspondence with the nasal profile, while at the edges of the prosthesis, at the interface with the patient's facial surface, there were minimal deviations demonstrating the good adhesion of the prosthesis to the face. Because of the optimal sealing effect of the facial cavity achieved with the prosthesis, the cohabitant relatives registered a better understanding of several phonemes. At last, the improvement of the aesthetic profile increased the self-esteem of the patient and the acceptance of the facial appearance by the relatives. Consequently, the patient gained a better quality of life, confirmed by her improved social relationships and her happiness to be finally understood when speaking. Today, the fabrication of prostheses for facial defect rehabilitation usually uses of CADCAM technologies, taking advantage of digital image processing, 3D virtual modeling, and additive manufacturing procedures. This approach provides faster, cheaper, and more customized solutions and is widely documented in the literature [17; 18; 19]. The first step of the procedure is data acquisition: surface laser scanning, 3D photogrammetry, CT, and an MRI scan, which are standard methods mentioned in the scientific literature [6; 20; 21; 22; 23]. For example, to manufacture an auricular prosthesis supported by craniofacial implants, the overlapping of CT and surface laser scan data ensures the best accuracy thanks to the combination of the skin surface and the bony skull data in a single STL file, which is useful to determine the position of the craniofacial implants in relation to the prosthesis [11]. Moreover, for a nasal prosthesis, laser scanning provides optimal results in terms of aesthetics. At the same time, in the case of wide facial defects, digital stereophotogrammetry represents the gold standard method for data acquisition [24].