## 4 Discussion  
In the last decade, the usage of a custom-made simulation bite has been proposed to obtain reproducible and tittatable mandibular protrusion during DISE, overcoming the limitations of a conventional chin-lift maneuver [15; 16]. In this regard, it is critical to establish precisely the therapeutic mandibular advancement and the vertical dimension of the MAD, considering that the amount of mouth opening can reduce the protrusive capacity and increase the posterior position of the mandible [11]. Digital revolution has significantly influenced the clinical work-flow in dentistry and orthodontic fields, with CAD-CAM systems being the new leading process for appliance fabrication. In this regard, CAD-CAM systems provide easier data acquisition, data management and storage processes, better standardization of the procedures and communication tools [17]. In addition, the efficiency and the accuracy of the production of dental manufactures can be significantly improved using dedicated equipment [18; 19]. In the present paper, we propose an easy and versatile full-digital process to generate a customized individual fork for mandibular advancement registration during DISE. Although custom-made simulation bite for DISE can be generated with an analogical procedure using conventional bite registration materials, there are specific advantages in using digital technology and CAD-CAM systems for the same purpose and those that the authors have experienced or assumed in the two clinical cases shown. The first advantage is related to the effectiveness of registration detection. Using an intra-oral scanner and digital bite registrations with [PERSON](tm), it is possible to instantaneously visualize, on the screen, the relationship between the planned mandibular protrusion and the amount of increased vertical dimension (the future vertical dimension of the appliance). In doubtful cases, considering how critical the vertical dimension is for the effectiveness of the MAD, clinicians can request the production of two forks with different vertical dimensions that an otorhinolaryngologist specialist will test during DISE execution, even comparing the respiratory performance using different heights of the fork. The second advantage is related to the quality of the patient's clinical examination. In this regard, it is appropriate to perform a preliminary and accurate evaluation of the TMJ's  
Figure 9: In this frame, the immediate improvement effect on all respiratory parameters with normal saturation values during the mandibular advancement with the fork in place is shown. In addition, masseter muscles are completely suppressed. function and relative range of movements prior to registering the mandibular protrusive positions for DISE. The gnathological examination should be made at the dental chair and must also include information about potential patients' pain and discomfort during prolonged advancement [20]. With the digital system, in cases of no severe limitations, it is possible to design a 3D-printed customized fork within the permitted range of movement for further evaluation with DISE. Lastly, digital systems streamline the diagnostic and clinical work-flow for the production of a customized mandibular advancement fork. Once the dental clinician takes digital registrations, all information is transferred to the lab technician for the production of a customized fork. The otolaryngology specialist receives the 3D-printed customized fork for DISE inspection without the need of preliminary registration. In addition, there is no need for a dental specialist in the operating room, since all functional parameters have been previously assessed at the dental chair. The production process will be even faster, when clinicians who are familiar with in-office 3D printing production can generate the customized appliance and send it to the specialist center or deliver it directly to the patient. As for the handling of the fork, it only took a few seconds to find the indentation of the lower incisors.