Obstructive sleep apnea syndrome indexes in patients treated with oral appliances with different vertical dimension: a preliminary study

BACKGROUND: Mandibular reposition devices (MRDs) are a viable option for addressing snoring and mild to moderate obstructive sleep apnea syndrome (OSAS) as another possibility to continuous positive airway pressure (CPAP) ventilation during sleep. The aim of the study was to evaluate the efficacy of OSAS MRDs with variation in vertical dimension, considering the OSAS indexes: Apnea Hypopnea Index (AHI), Oxygen Desaturation Index (ODI) and Snoring Index. METHODS: Eleven patients with different level of OSAS were enrolled in this study. The patients in the study were evaluated at three different times (T0, T1, T2). At T0 the patients underwent a basal polysomnography (PSG) without any oral appliance. At T1, the PSG was executed using MRD at 70% of protrusion and a vertical dimension consequent of protrusion. The vertical dimension determined by a protruded position is the one that is caused by the repositioning of the mandible. At the T2, the patients used the same appliance with 70% of protrusion, adding a uniform 6-mm bite resin plane between the existing upper and lower splints of the MRD, in the lateral area. The patients enrolled in this study did not tolerate the CPAP. T-test for paired samples was used to assess the possible statistical differences between AHI and ODI (T0, T1 and T2). The snoring indexes were analyzed through Friedman test for corelated sample. RESULTS: The mean value of AHI (T0) was 30.17 +/- 19.51. The mean AHI of T1 was 10.60 +/- 9.35, while the mean value of T2 was 5.41 +/- 3.25. The mean value of ODI (T0) was 29.02; SD +/- 20.74. The mean ODI of T1 was 10.46 +/- 9.48, while the mean value of T2 was 5.40 +/- 3.41. Analyzing AHI and ODI, there was a significant statistical difference between T0 and T1 (P<0.05), between T1 and T2 (P<0.05) and between T0 and T2 (P<0.05). There was not any statistical difference for snoring indexes between T0, T1 and T2. (P>0.05). CONCLUSIONS: According to the results of this study, the major improvement of AHI and ODI is reached through the usage of MRD with an increase of vertical dimension. Considering all the limits of the study, it is possible to affirm that research should still take account of the vertical dimension as a possible factor when treating OSAS with oral appliance.