Treatment Response Of Obstructive Sleep Apnea To Mandibular Advancement Deviceat Different Protrusion Positionswith Constant Vertical Dimension

Objective:This study is to estimate the treatment response of Obstructive Sleep Apnea (OSA) to Mandibular Advancement Device (MAD) at different protrusion positions with constant vertical dimension.Methods:According to both inclusion and exclusion criteria,15mild or moderate male OSA (age=38±9) were collected from the patient coming to Stomatology Hospital of Shandong University (2011.5-2012.5). Both Sleep Apnea Condition (ESS estimation and PSG) and radiography examination (Lateral Cephalograph Radiograph and low-dose spiral CT) were carried out at different mandibular protrusion positions (0%,50%,75%of Maximum Protrusion Position with constant vertical dimension. Based on images acquired from low-dose CT scanner, numerical models of upper airway were rebuilt and measured using Mimics10.01.The changes of anatomical structure of upper airway were reappeared at different protrusion positions. Also, correlation analyses were carried out between objective and subjective parameters (ESS/AHI) and anatomical parameters;resistance of upper airway (R) and anatomical parameters. The relationship between vertical skeletal type (FH-MP)and volume of upper airway was analysized and scatter diagrams were drawn.Results:1. Volume of upper airway, Smin, Smean were gradually increasing with mandibular protrusion from0%protrusion position to75%protrusion position. There were significant difference between0%and50%protrusion positions in the above anatomical parameters (P＜0.05); there were no statistical difference between50% and75%protrusion positions although the anatomical parameters were increasing from50%protrusion position to75%protrusion position.2. AHI was decreasing with the increasing protrusion positions. Compared with0%protrusion position, AHI was significantly decreasing at50%and75%protrusion positions (P＜0.05). AHI was lowest at75%protrusion position (P＜0.05), however, side effects were also increasing with increased protrusion positions.3. There were significant relations between AHI and anatomical parameters of OS A by correlation analysis (P＜0.05); AHI was greater when the Smin、Smean、V of upper airway were decreasing and Percentage of Stenosis was increasing(P＜0.05). The correlationsbetweenESS and anatomical parameters were not significant(P＞0.05).4. There wasno significant correlation between FH-MP angle and AHI (P＞0.05). There was significant relationship between FH-MP angle and volume of Glossopharyngeal(P＜0.05).Conclusion:1. Sleep and respiration conditions and anatomical structure of upper airway of the subject were significantly different at different protrusion positions with constant vertical dimension. Sleep and respiration conditions and anatomical structure of upper airway were improved significantly at50%protrusion position. We recommend coming to a weighted compromise between efficacy and side effects by starting a MAD treatment in the50%protrusion position.2. For OS A, pathology and treatment response to MAD was influenced by vertical skeletal type.The patients with horizontal growth pattern were more inclined to OSA. Fortunately, they had more positive response to MAD.