Finite Element Analysis of an innovative Mandibular Advancement Device for people suffering from Obstructive Sleep Apnea Syndrome combined with Periodontitis.

The Obstructive Sleep Apnea (OSA) is a respiratory disorder very common among the population, characterized by episodes of complete or partial obstruction of the upper airways during the sleep. Nowadays, people who suffer from this respiratory disorder are able to cohabit with it without altering too much their day life thanks to non - invasive devices as the Mandibular Advancement Device (MAD). In this work the finite element method has been used to carry out static structural simulations to evaluate the mechanical interaction, in terms of stress and deformation, between the MAD and the anatomical components of the oral cavity. The innovation of this work is the investigation of the OSA syndrome in a condition of periodontitis, an inflammatory disorder that affects the periodontium. In particular, a comparison analysis has been performed between a healthy model and a model where periodontal ligaments and mandibular bone are affected by the first stage of periodontitis (characterized by 15% bone reduction). The 3D models of the MAD and the dental arches representing both a healthy and an inflammatory condition are obtained by means of a Reverse Engineering technique and computer-aided design modelling software. Subsequently, the finite element analyses have been performed through Ansys software and the results obtained for the healthy and pathological condition have been compared. By evaluating the stress and the deformation of teeth and periodontal ligaments, a direct relationship can be established between bone resorption and an increase in stress and deformation in the affected area. The results achieved in this work show that the mandibular teeth deformation increases in the periodontitis condition with respect to the healthy model, ranging between 9% and 11%, while in the maxillary teeth the range is between 3% and 14%. For what concerns the stress over ligaments, the trend is a little bit swinging. The stress value of the mandibular periodontal ligaments of the periodontitis condition ranges between -16% and 24% with respect to the healthy model and between -24% and 14% for the maxillary periodontal ligaments. The results of this work are in line with the articles describing a situation of bone resorption, since greater deformation and stress values are documented in the most worn areas as might be expected. However, not all the results of this work are comparable with the results found in the literature, since this is the first study that investigates the biomechanical effects of a MAD to treat the OSA syndrome coupled with periodontitis making this work innovative. Further studies are planned to analyze in deeper all the other staging of periodontitis and consequently, to evaluate the edentulism phenomenon associated with this disorder.