## 2 Materials and Methods  
Participants were selected prospectively from the clinics of the School of Orthodontics at the University of Ferrara and the Otorhinolaryngology and Pneumology departments of the Sant'Anna Hospital in Cona (FE) between January 2020 and March 2022, according to inclusion criteria describe in the Table 1. The diagnosis of OSA's and the selection for intraoral device therapy were made by a specialized Otorhinolaryngology physician based on a comprehensive type III polysomnographic examination [13]. \begin{table}
\begin{tabular}{l} \hline \hline
**Inclusion Criteria** \\ \hline Patients with simple snoring \\ \hline Patients with mild (AHI = 5–15), moderate (AHI = 15-30), or severe OSAS who cannot tolerate or refuse to use CPAP. \\ \hline Sufficient number of dental elements for good retention of the intraoral device (>6–8 per arch) \\ \hline Absence of ongoing periodontal disease and/or tooth mobility \\ \hline No functional limitations in mandibular protrusion movement \\ \hline \textgreater{}18 years old \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Inclusion Criteria. The study group consisted of 19 patients, 15 males and 4 females, with ages ranging from 26 to 69 years (mean age 49.6 years, standard deviation 14.6). The patients were treated by the same operator ([PERSON]) at the same dental clinic. Table 2 describe initial records collected for all patients. Subsequently, the impressions, disinfected with 2% glutaraldehyde solution, were sent to the dental laboratory for the fabrication of the F22 MAD. This is a bi-block device made of thermoplastic polyurethane, DURASOFT(r) (Scheu-Dental, Iserlohn, Germany) reinforced with low-shrinkage acrylic resin, providing complete occlusal coverage. It consists of an upper block with a titanium pin in a retro-incisal position with a spherical tip, and a lower block with a curvilinear slot extending from canine to canine, featuring a spherical cavity for engaging the metal pin in the upper block (Figure 1). This mechanism allows the mandible to be locked in a protruded position and prevents mouth opening while maintaining lateral mandibular movement through the sliding of the metal pin within the slot. The initial position is determined during the registration of the advancement bite, at approximately 75% of the maximum protrusion achievable by the patient, or identified as the maximum comfortable protrusion that the patient can achieve [21]. The device is fixed during impression taking by construction bite registration, and can be increased by varying the position of the metal pin at the level of the upper block. Subsequent advancements after the first should be made gradually, increasing by 1 mm at a time, allowing for gradual adaptation of the musculature. Upon device delivery, the patient receives one lower block and three upper blocks, each with the metal pin positioned 1 mm apart in the anteroposterior direction: STEP 0, STEP \(-\)1, STEP \(+\)1 (Figure 2). \begin{table}
\begin{tabular}{l} \hline \hline
**Initial Records** \\ \hline Assessment of daytime sleepiness using the Epworth Sleepiness Scale questionnaire [20] \\ \hline Dental arch impressions, either analog or digital, to obtain initial study models \\ \hline Construction bite in an advanced position, recorded using the George Gauge fork, either analog or digital. \\ \hline Intra- and extra-oral photographs of patients taken before and after application of the \\ F22 MAD device \\ \hline Polysomnography or full night cardio-respiratory monitoring of type III \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Initial Records. Figure 1: The design of the F22 MAD. Figure 2. Intraoral photo of the F22 MAD. STEP 0 corresponds to the initial advancement position, which is the degree of propulsion measured using the Gauge fork (Figure 3) at the time of the fingerprint recording. Figure 3. [PERSON] fork.