The X-Cephalometric Studies Of Upper Airway And Hyoid Position In Natural Head Position In Normal Occlusion People

Obstructive sleep apnea syndrome (OSAS) is a common sleep disorder, which is characterized by repetitive episodes of complete or partial obstruction of the upper airway during sleep. These conditions usually result in oxygen desaturation, affecting the function of circulatory syste, respiratory system, nervous system, endocrine system and so on. Now, the syndrome arouses people's attention in clinic gradually.The obstruction of the upper airway during sleep may be relevant to the abnormal anatomy of the upper airway in patients with OSAS. Skull, jaw, palate bone, the hyoid bone and other facial hard tissues uphold the upper airway, the shape change of them can affect the position and the tension of soft tissues, which is attached to or surrounds them, thus affecting the size and stability of the airway, abnormal upper airway structures have positive correlation with the severity of OSAS. It has been a consensus call that the hyoid position change was an important factor in the onset of OSAS.If we want to know whether the upper airway space and hyoid position is normal in patient with OSAS, we must compare the patient's upper airway space and hyoid position with normal's. So we did the X-Cephalometric reseach of upper airway and hyoid position in natural head position in normal occlusion people.ObjectiveThe purpose of this study was to obtain the X-Cephalometric value of the upper airway and hyoid position of 61 normal occlusion persons from guangdong province and compare the measurements between males and females.61 persons from Guangdong province, who are with normal occlusion and face structure, and have no upper airway diseases, were chosen.Lateral cephalograms of the subjects were taken respectively with a roentgenographic cephalometer.61 cephalometric films were taken at the natural head positon.Materials & Methods1. Subjects We examed about 7000 students form two professional college in guangzhou.61subjects(20 males and 41 females) were selected. The mean age of the sample was 18.77±1.72 years old. The age range of the sample was 16.00-22.08 years old. The criteria for selection were based on:①Neutral relationship of molar and canine, normal anterior overbite and overjet.②Dentitions complete(except the third molars), good tooth alignment and good occlusion.③Normal visual harmony of facial and skeletal profile, the lips in light contact when the teeth in occlusion.④No previous orthodontic treatment or orthognathic surgery, no previous uvulopalatopharyngoplasty.⑤No history of snoring and excessive daytime sleepiness, no upper airway diseases such as chronic rhinitis, hyperplasia of conchae and tonsil and so on. No chronic respiratory diseases such as tracheitis, asthma, emphysema and so on.⑥The degree of mouth opening and the open-closed type are normal. No temporomandibular joint diseases.⑦Parents of guangdong origin. No history of obesity or assessed as clinically overweight, no habitual mouth breathing, no history of operation and irradiation to the head and neck area.⑧Good health, no mental disorders.⑨All participants understand the objective and process of this experiment, and signed informed consent forms.⑩Brent Hassel's mature stage was used as a reference, all the subjects must be in the completion stage.⑾Normal facial structrue. ClassⅠjaw relationship:0.7°<ANB<4.7°, normal vertical facial type:27.3°<gogn-SN<37.7°.2. Research equipments①SIRONA Orthophos XG PLUS roentgenographic cephalometer.②chinese lenovo C200 computer, japan RISE company Winceph7.0.③Serile dental equipment: mouth mirrors, probes, tweezers,75% alcohol cotton balls, sterile dry cotton ball, barium sulfate paste and so on; Head posture auxiliary positioning devices:Mirrors (4 0×25cm), plumb and plumb line, etc.3. Experimental methods and process(1)subject selectingHistory collection Design the examination table, mainly includes genetral basic information of participants(name, gender, date of birth, race, native place, heigh-t, weigh, etc.), oral history (history of dental disease.whether or not have previous orthodontic treatment, orthognathic surgery, uvulopalatopharyngoplasty, etc. history o-f dental treatment. history of maxillofacial and neck disease and trauma. history of upper airway diseases and snoring, systemic health status,mental and psychological conditions and systems history and so on.Clinical examination①Facial examination:genetral basic information of maxillofacial,include facial symmetry,lateral profile and so on.②Oral examination: dental health, the arrangement of teeth, occlusal relationship and so on. Is there hypertrophy of tonsil and adenoid, ect.③Examination of temporomandibular joint: Whether or not temporomandibular joint have clicking or pain under functional movement? Is there tenderness in joint region? Is the degree of mouth opening normal? Is there a limited ability to open mouth? Is the open-closed type normal?④X-ray examination:The measurements showed that 0.7°<ANB<4.7°,27.3°< gogn-SN<37.7°.(2)Take lateral cephalogramsLateral cephalograms of the subjects were taken respectively with a SIRONA Orthophos XG PLUS roentgenographic cephalometer. X-ray tube is away from the median sagittal plane about 150cm. The linear magnification rate is 11%. The magnification factor was adjusted by Winceph7.0. Let the subjects walk slightly on the spot. The subjects were then asked to stand at rest in a relaxed manner, namely"self-balance position". Stared at his or her own eyes in the mirror in front of their body. In the case of line of sight was parallel with the ground plane, namely"mir ror position", also called natural head position. Special care was taken to ensure that the head was not moved when the ear posts were carefully inserted. All subjects were asked not to swallow, and to contact their teeth lightly while the lateral cephalometric radiographs were being taken. The latter were taken with the lips in light contact, the teeth in occlusion and the subject were at the end of breath. Taking films in the end of breath can eliminate the compensatory effect of the upper airway muscle, which can remove the tractional effect of muscle on the trachea. Before taking films, coated the tongue with thin layer of barium sulfate to enhance imaging.4.Data collection and statistical analysisLandmarks on cephalometric radiographs were digitised by one person in a series time and the measurements were made using a computer programme Winceph7.0. The statistical package used was SPSS13.0. The means and standard deviations(X±S) of all the status were calculated. Cephalometric variables for male and female subjects were compared using the Student's t-test. Satterthwaite separate variance estimation t-test was used when the variance is heterogeneous. A random sample of 30 scanned cephalometric tracings was selected and digitised. The measurements were completed twice on two separate occasions,4 weeks apart, by the same investigator. The mean value of the variables measured on each of the two occasions were compared using paired t tests to detect any systematic error in measurements made. A P-value less than 5% was considered significant.Results1. Obtain the X-Cephalometric value of the upper airway and hyoid position of 61 normal occlusion persons from guangdong province.2. Bony nasopharynx:PNS-S were significantly greater in male than in female (t=4.628, P< 0.001. PNS-Aa were identical between the sexes. soft tissue nasopharynx PNS-ad1, PNS-ad2 were identical between the sexes. oropharynx:P1-P2 were greater in male than in female (t=2.212, P=0.031), Ve1-Ve2 were identical between the sexes. hypopharynx:Pas 1-Pas2 (t=2.031,P=0.047),Ph1-Ph2 (t=2.165, P=0.034),Va1-Va2 (t=2.405,P=0.019) were greater in male than in female. 3. The angle between the hard and soft palate(PNS-P1/NL) was more abrupt in women than in men (t=-4.065, P<0.001), indicating a more upright position of the soft palate in men. The soft palate maximal thickness (SP1-SP2) were greater in male than in female (t=3.161, P=0.002),while the soft palate length(PNS-P1) were identical between the sexes.the tongue length(Va1-T) (t=3.328, P=0.002) height(TD-VT) (t=4.178, P<0.001) were greater in male than in female.Va1-PNS were significantly greater in male than in female (t=9.246, P<0.001). Va1-H (t=2.833,P=0.009) and Va1-CVP (t=3.068,P=0.003) were greater in male than in female.Va1-Gpost were identical between the sexes.4. Va1-CVP/SN were identical between the sexes. Va1-H/SN (t=2.190, P=0.038) and Va1-PNS/SN (t=4.170, P<0.001) were greater in male than in female.5. All the angular measurements of the hyoid bone were identical between the sexes except H-Gpost-Bo. H-Gpost-Bo were greater in male than in female (t=2.583, P=0.012)6. The linear measurements reflecting the distances between the hyoid bone and the cervical spine:H-CV4ia (t=5.173,P<0.001), H-CV4ip(t=7.027, P<0.001) H-CV3ia (t=7.208, P<0.001), H-CV2ia (t=8.489, P<0.001) and H-CVT (t=8.408, P<0.001) were significantly greater in male than in female. H-Bo (t=9.589, P< 0.001), H-Ar (t=10.159, P<0.001), Hm-S (t=10.606, P<0.001), H-NSL (t=9.253, P<0.001), H-RL (t=4.606, P<0.001) and H-NL (t=7.668, P<0.001) were significantly greater in male than in female. H-Me(t=-2.430, P=0.018)and H-MP/GN (t=-2.362, P=0.022) were smaller in male than in female. H-Gpost, H-Pg, H-MP and H-NSLP/N were not statistically significant different between sexes. The averages of H-Gpost and H-Pg were smaller in male than in female.7. The rates between the distances and SN were greater in male than in female: H-CV4ia/SN (t=2.770,P=0.009), H-CV4ip/SN (t=3.754,P=0.001), H-CV3ia/SN (t=4.736,P< 0.001), H-CV2ia/SN (t=5.631, P<0.001), H-Bo/SN (t=4.964, P <0.001), H-Ar/SN(t=5.088, P<0.001), Hm-S/SN (t=4.480, P<0.001), H-RL/SN (t=3.244,P=0.002),H-CVT/SN (t=4.606,P<0.001),H-NSL/SN (t=3.838,P< 0.001, H-NL/SN (t=4.294, P<0.001). the former were the distances which were greater in male than in female and showed statistically significant differences between genders.Conclusions1. Soft tissue nasopharynx, bony nasopharynx (PNS-Aa) and the minimal distances of the oropharynx were identical between the sexes. The soft palate maximal thickness were greater in male than in female, the soft palate length were identical between the sexes. The tongue length, height were larger in male than in female. The vallecula was lower in males, while it's identical between the sexes at horizontal orient.2. Hyoid bone position was lower and more anterior in males. The angular measurements of the hyoid bone axis were not significantly different among sexes. The variation of the the hyoid bone axis is great.