## 3 Results  
An analysis of the results was performed based on the different surgical areas. A Reconstructive surgery  
All the patients treated with the 3D CAD/CAM printing protocol were afflicted by oral squamous cell carcinoma. Three patients were male, and one was female, with an average age of 62 years (the patients' ages ranging from 45 to 75 years). In three cases, metastatic lymphadenopathies of the neck after modified radical neck dissection (MRND) were found and post-surgical radiotherapy (RT) was performed. The mean follow-up period was 13 months. In all cases, the fibula flap was set with a skin island to reconstruct the mucous portion of the alveolar ridge. In two cases the flap of the fibula was planned with two bone segments. In the remaining cases, a \"double bar\" with three segments and a \"single bar\" with four segments were designed to restore the mandibular continuity and allow for subsequent implant prosthetic rehabilitation. All the patients underwent post-surgical CT. Using the InVeselius software, the STL files were processed to obtain the digital volume of the mandibular reconstruction. Through the Cloud-Compare software (software for the elaboration of meshes and 3D point clouds, Open-Source Project), the STL volume obtained from our digital planning procedure was superimposed on that coming from the post-surgical CT scan. Using the \"alignment\" tool, the highest point match was obtained and using the \"mesh cloud\" function the standard deviation was calculated by the software. The discrepancy between the model overlap and the points was visualized through a fusion image of the color map in all the cases treated. A standard deviation of 5.496 mm (ranging from 1.966 to 8.024 mm) was calculated from the 3D volume overlap analysis. About 6 m of Bioflex medical PLA filament were used to produce the model and the guide at a total cost of 3.6 euro per case. The total time spent designing the virtual schedule was about 3 h and the printing process and subsequent sterilization took about 6 h.  
B.1 Traumatology: Orbital floor fractures  
Using the iPlan Cranial 3.0 (Brainlab, AG, USA, 2010) software, the correct position was quantified by comparing the in vivo positioned mesh with that planned digitally. A good overlap between the preoperative digital planning and the postoperative result was highlighted in all cases. The average distance between each of the three corners of the mesh and the corresponding points on the surface of the digitally programmed orbital floor was 0.71 \(\pm\) 0.23 mm (0.566 mm, 0.533 mm, 0.766 mm, and 1 mm). Statistical analysis (ANOVA) with the [PERSON]'s method showed a significant result at p \(<\) 0.05. (f-ratio value = 4.88848; \(p\)-value = 0.007665). B.2 Traumatology: Fractures of the zygomatic arch  
Of our group of patients, eleven (68.8%) were male and five (31.2%) were female. Analyzing the causes of the trauma, we noticed that in seven cases (43.8%) the fracture occurred after a car accident, in four cases (25%) after a sports injury, and in five cases (31.5%) after an accidental fall. The median age was 34 years (ranging from 23 to 62 years old). The post-operative CTs performed revealed an excellent positioning of the device on the skin surface and a correct reduction of the fracture in all the cases analyzed. The tolerability of the device was evaluated with a multiple-choice questionnaire. The reliability of the questionnaire administered was confirmed by the [PERSON]'s alpha test with a score equal to 0.730. Only one patient left the study due to a total intolerability of the device. The average total score was 9.4. C The COVID-19 Pandemic: Face masks and face shields  
Six masks were produced and supplied to six surgeons who used them in their activities. The 3D printer took about 6 h to print the mask body, 1 h for the filter slot and 3 h for the face shield. The cost of the filament used was estimated at 1 euro for the mask body, 0.30 euro for the filter slot and 1.50 euro for the face shield.