Mandibular position and three dimensional morphology of upper respiratory tract .
Date Issued
2008
Date
2008
Author(s)
Wu, Chuan-Luen
Abstract
Objectives:The aim of this study is to analyze upper airway morphology changes and dynamic movement at different sections affected by mandible position by using dynamic and static magnet resonance imaging technique. The study also discusses the formation mechanism of obstructive sleep apnea syndromes and function mechanism of the oral appliance, as well as the evaluation of the clinical results of the oral appliance on non-obese male patients with severe obstructive sleep apnea in Taiwan.aterials and Methods:9 non-obese (BMI<25) severe OSA (AHI>30) male patients between the age of 20 to 60 and 9 gender, BMI and age matched control (AHI<5) were recruited for this study. Nine bite index were made for the different mandible positions of the subjects. pper airway was imaged by using static and dynamic MRI of each subject wearing the bite index while lying on the MRI scanning table. This study also measures the circumference and takes the lateral cephalometric imaging of each subject. Oral appliances were made and fitted for the experimental group subjects, who wore them for three months, after which they transferred to the Sleep Center and underwent PSG examination to evaluate therapeutic effects of theappliances.esults:There was no significant difference in upper airway volume between the experimental group or control group in total volume (p=0.998), retropalatal volume (p=1.000), or retroglossal volume (p=0.991). The only statistical difference found between the two sets of lacteral cephalometric imaging was ∠NSBa, in which the experimental group value was smaller than that of the control group (p=0.033). The oral appliance worn by the experimental group shows a significant therapeutic effect in treating sleep apnea, by lowering AHI (p=0.000), lowering oxygen desaturation event (p=0.000), raising average oxygen saturation (p=0.020), increasing lowest oxygen saturation (p=0.003), and decreasing saturation<90％ (p=0.034). he relationship between different mandible positions and upper airway three-dimensional volume is as follows: Among experimental group subjects, when the mandible is at no protrusion level, the upper airway volume of moderate opening position is significantly smaller than that of no opening position (valid for total volume, retropalatal volume, and retroglossal volume); and the volume of moderate opening position is significantly smaller than that of slight opening position (valid for total volume and retroglossal volume). When the mandible is at minimal opening level, the upper airway volume of 75％ maximum protrusion position is significantly larger than that of 50％ maximum protrusion position (valid for retropalatal volume). When the mandible is at slight opening level, the upper airway volume of 75％ maximum protrusion position is significantly larger than that of 50％ maximum protrusion position (valid for total volume and retroglossal volume). When the mandible is at moderate opening level, the upper airway volume of 75％ maximum protrusion position is significantly larger than that of no protrusion position (valid for total volume, retropalatal volume, and retroglossal volume); the upper airway volume of 75％ maximum protrusion position is significantly larger than that of 50％ maximum protrusion position (valid for retropalatal volume).There was no significant change in the total, retropalatal, or retroglossal volumes of the upper airways in control group at different mandible positions.The relationship between different mandible positions and dynamic area of the upper airway is as follows: Among the experimental group subjects, the area of midsagittal section was influenced by interactive effect of protrusion and opening; the area of coronal section is influenced by simple effect of protrusion and opening; the area of retropalatal axial section is simply affected by protrusion; and the area of retroglossal axial section is simply affected by opening. The control group subjects displayed no significant changes, except for an influence of opening on the midsagittal section area. he relationship between different mandible positions and dynamic length of the upper airway is as follows: Among the experimental group subjects, the L length of retropalatal axial section is simply affected by protrusion; the AP length of retropalatal axial section is simply affected by protrusion; the L length of retroglossal axial section is influenced by interaction effect of protrusion and opening; the AP length of retroglossal axial section is not influenced by mandible position. The dynamic length for control group subjects shows no significant change. onclusion: This study shows the significant clinical effect for using of oral appliance on non-obese (BMI≦25) male patients with severe obstructive sleep apnea in Taiwan. In these patients, simply mandible open without protrusion decreases the upper airway volume. The volume of different portion of the upper airway was increased in conscious subjects when protrusion reached sufficient levels (75% maximum protrusion), thus preventing the collapse of airway volume especially in retropalatal volume during sleep. Normal subjects show no significant changes in upper airway volume in any mandible position, and each volume almost was smaller than base line volume. The upper airway is not a channel which enlarges or contracts evenly. For patients with severe obstructive sleep apnea, the midsagittal section area is interactively affected by protrusion and opening; the coronal section area is simply affected by protrusion and opening; the retropalatal axial section area is simply affected by protrusion; and the retroglossal axial section area is simply affected by opening. The L length and AP length of the retropalatal axial section is simply affected by protrusion; the L length of the retroglossal axial section is affected by interaction effect between protrusion and opening; and the AP length of the retroglossal axial section is not affected by mandible position.
Subjects
mandible position
obstructive sleep apnea
magnetic resonance imaging
upper airway volume
oral appliance
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