Impact of Mandibular Advancement Therapy on Occlusal Plane Orientation and Incisor Inclination in Obstructive Sleep Apnea Patients: A Retrospective Observational Study

<b>Objective:</b> This observational study aimed to evaluate occlusal changes in patients with obstructive sleep apnea (OSA) treated with a mandibular advancement device after two years of therapy. <b>Methods:</b> Sixty adult patients with mild to moderate OSA (apnea-hypopnea index 15-30 events/h) were treated with the IMYS MAD for 24 months. Digital dental impressions were analyzed using Autodesk Meshmixer and Fusion 360 to measure sagittal, frontal, and occlusal angles, as well as upper incisor inclination at baseline (T0) and after treatment (T1). In addition, changes in the polysomnographic indices AHI and ODI were evaluated. Statistical analyses were performed using paired <i>t</i>-tests or Wilcoxon signed-rank tests depending on data normality (<i>p</i> < 0.05). <b>Results:</b> No significant differences were found between T0 and T1 in sagittal (IC 95% -2.053,1.433), occlusal (IC 95%, -1.202, 0.722) or frontal angles (IC 95% -1.487, 0.447), or in upper incisor inclination (IC 95%, 0.06,3.04). Polysomnographic parameters improved significantly, with mean AHI decreasing from 27.7 ± 12.3 (IC 95% 24.53-30.87) to 6.2 ± 4.0 events/h (IC 95% 5.17-7.27) and ODI from 19.7 ± 9.4 (IC 95% 17.27-22.13) to 4.7 ± 3.2 (IC 95% 3.82-5.48, <i>p</i> < 0.001). <b>Conclusions:</b> This study found that the IMYS MAD did not induce significant variations in occlusal plane orientation or upper incisors inclination after two years of treatment. These null findings suggest that the IMYS device may provide effective OSA management while minimizing the risk of occlusal or dental side effects. However, the retrospective design and the 24-month follow-up duration should be taken into consideration.