The Influence of Mandibular Advancement Device Treating OSAHS on Primary Prevention of Ischemic Stroke

1. The purpose of this study is to detect the differences of carotid atherosclerosis severity between patients with or without OSAHS(Obstructive Sleep Apnea and Hypopnea Syndrome) in a cross-sectional study in a large sample.
2. Then a longitudinal control study is conducted to observe the progress of the carotid atherosclerosis by vascular ultrasonography and the occurrence of cerebrovascular events after the intervention of the oral appliance for treating OSAHS，and finally explore the feasibility of using oral appliance to treat OSAHS in primary prevention of ischemic stroke.

1. the relevance of OSAHS and carotid atherosclerosis Patients are distributed questionnaire and recruited from neurology clinic，vascular ultrasonography clinic of Xuanwu Hospital if they match the inclusion criteria. After initial screening, carotid atherosclerosis patients with skeptical OSAHS are sent to sleep center for polysomnography examination to determine the severity of OSAHS. At least 50 patients for mild, moderate, severe OSAHS each are recruited for OSAHS Group. At least 100 patients without snoring from questionnaire and without OSAHS after PSG screening are recruited for non OSAHS Group. Vascular ultrasonography examination for carotid are done for the two groups. Data of carotid vascular plaque from two groups are collected. Statistics are done to detect differences of carotid atherosclerosis severity between patients with and without OSAHS, also the severity of OSAHS.
2. the relevance of the progress of carotid atherosclerosis and oral appliances intervention for treating OSAHS All carotid atherosclerosis patients with OSAHS are from patients of the first study. If they consent the treatment of oral appliances, they are recruited into this second study. At least 100 patients are recruited. They are divided into 2 groups by randomized block design by Evidence-based Medicine Center of Xuanwu Hospital. One group is oral appliance intervention group, the other group is no intervention group. The intervention group patients accept oral appliance treatment, and no intervention group patients do not accept OSAHS treatment. The two groups both accept anti-hypertension treatment or anti-diabetes treatment, or anti-hyperlipidemia treatment according to their own situation in neurology clinic.

At timepoint of initial time, one month after oral appliance treatment, one and a half year after oral appliance treatment, the intervention group should accept PSG(Polysomnography) examination to monitor the treatment of OSAHS.

At timepoint of initial time, one month after oral appliance treatment, one and a half year after oral appliance treatment, the two groups should accept breath holding test to monitor the cerebral vascular reserve.

At timepoint of initial time, one and a half year after oral appliance treatment, the two groups should accept carotid vascular ultrasonography examination to monitor the progress of carotid atherosclerosis.

Cerebrovascular events and death are recorded from initial time. Statistics are done to detect the influence of treatment of OSAHS on carotid atherosclerosis.

Eligibility Criteria:
Inclusion Criteria:

* diagnosed with atherosclerosis by vascular ultrasonography
* diagnosed with OSAHS by polysomnography

Exclusion Criteria:

* patients who have stroke already
* patients who can not wear oral appliances according to experiment requirements
* patients who have bad periodontal condition or teeth number less than 20