Obstructive sleep apnea hypopnea syndrome(OSAHS) has been the main research area of the Dental Therapy Center for Sleep Apnea,Peking University School and Hospital of Stomatology.The basic research in the center includs: epidemic survey of OSAHS and snoring in a Beijing population,setting up the cephalometrc and MRI standard of airway and surrounding structures for non-snoring Chinese,aetology exploring OSAHS from views of airway size,craniofacial form,neck circumference and genioglossus muscle activity.Clinically,different dental appliances were developed.The treatment effects of the oral appliances for OSAHS patients were evaluated quantitatively.Two and three dimension changes of the airway and surrounding structures,genioglossus muscle activity,as well as snoring loudness following mandible advancing and opening were studied.Besides,research was expended to OSAHS in children recently.Under the support of National Nature Science Foundation 7 PhD and 3 MS students have graduated.More than 60 papers were published domestically and abroad and two awards were received from the National Ministry of Education and Chinese Medical Association in the past 10 years.This paper is a review of the past and current situation of dental research on OSAHS in China.

Biological Evolution ; China ; Humans ; Stomatognathic Diseases

Objective:To study the effect of surrounding tissues on the minimum cross-section area(minCSA) of upper airway in non-snoring males.Methods: Upper airway scanning by magnetic resonance imaging(MRI) was conducted in 83 non-snoring males aged 22 to 57 years. The correlation between the minCSA of upper airway and the linear, area and volume measurement items about the morphology of the surrounding tissues was analyzed. Results: The minCSA was in velopharynx or glossopharynx. In non-snoring males,the main relative factors to minCSA were transverse dimension/ transverse distance between mandible(r=0.700), transverse dimension/ pharyngeal wall thickness(r=0.680), and parapharyngeal fat volume(r=-0.290). The velopharynx was more prone to be affected by the surrounding tissues than the glossopharynx. The location of the parapharyngeal fat, the lateral pharyngeal wall and parapharyngeal fat volume had the most obvious influence on the velopharyngeal size in sequence. While the thickness of the lateral pharyngeal wall was the main factor which influenced the size of glossopharynx. Conclusion: The feature of surrounding tissues has certain influence on minCSA of upper airway in non-snoring males.

砄bjective: To study the relationship between respiratiory mode and dental occlusion. Methods: UI SN, LI MP, UI LI, OB, OJ and M1～M2 were measured with cephalometric technic in 34 oral breathing children and 34 nasal breathing children (aged 11～14 years) . Results: UI LT and OB in the children with oral breathing were smaller than those in the children with nasal breathing( P 0.05). Conclusion: The children with oral breathing may have smaller oberbite and more proclined dental arch.

Objective:To study the teeth of the ancients in Xia Dynasty,the first dynasty in Chinese history about 4 000 years ago,and acquaint ourselves with their incidences of periodontal disease,and the evolution of oral diseases.Methods:The teeth and jaws excavated in Erlitoou,Henan Province and Youyao,Shanxi Province were observed with clinical methods.The specimens totaled 56 individuals(male 38,and female 18),including 894 teeth,and 86 dental arches.The objects were all permanent teeth.The major observation items were periodontal disease.The prevalence of periodontal disease of the people in Chinese Xia Dynasty were outlined.Results:The prevalence rate of periodontal disease was 19.80% in the 894 teeth,while prevalence rate was about 42.86% among the individuals.The premortal tooth lossrate was 7.45% in the observed teeth.Conclusion:Periodontal disease is an aging-related disease without sex difference and commonly seen in the mandible,which is quite similar to the situation at present.The periodontal disease was the main reason for tooth loss in people of Xia Dynasty.

Objective: To determine the changes of upper airway morphology induced by mandible position from central relation to advancement position in patients with obstructive sleep apnea syndrome. Methods: Nineteen patients (17 males and 2 females) suffering from obstructive sleep apnea syndrome were confirmed with polysomnography. Occlusal wax record was made with mandible in advancement position. Helical computed tomography was performed on each patient in central relation and mandibular advancement position with wax record in situ respectively. On each slice, anteroposterior and transverse diameters were obtained. Airway shape was expressed as the anteroposterior/transverse (AP/T) diameter ratio. Paired samples t test was employed to compare the measurements. Results: With mandibular advancement, average and minimal diameters of glossopharynx and hypopharynx were increased significantly. Compared with it, the change of transverse diameter was more prominent. All segments of upper airway were increased significantly except hypophaynx laterally. Moreover, the change of velopharynx shape was observed on axial planes. Ellipse with transversal long axis became more compressed. Conclusion: Upper airway morphology of all segments was influenced by mandibular advancement whether in the sagittal or transverse plane of space, or airway shape. Not only anatomic connection but also regulation of the nerve system and other still unknown mechanism make contribution to the changes of upper airway morphology in patients with obstructive sleep apnea syndrome. The changes of upper airway morphology above mentioned constitute the rationale of treatment of obstructive sleep apnea syndrome with oral appliances.

Objective: To obtain the data about morphology of upper airway and surrounding tissues of non-snoring males from three age groups. Methods: Through questionnaires and clinic examinations, 83 non-snoring males (20-60 years) were selected from 453 volunteers and involved in the following research. There were 30 volunteers aged from 22 to 29 (mean 23.60?2.58 years), 31 volunteers aged from 36 to 45 (mean 40.10?2.64 years) and 22 volunteers aged from 46 to 57 (mean 49.55?3.45 years). Magnetic resonance imaging (MRI) of upper airway of each volunteer was acquired under strict posture-control conditions. The dimensions and cross-section area of nasopharynx, velopharynx, glossopharynx, hypopharynx and whole upper airway with its surrounding tissues were measured with MRI intrinsic software. Volumes of upper airway and surrounding tissues were also calculated. Results: There were 93 items about morphology of the upper airway and surrounding tissues of non-snoring males from the three age groups.With increase in age, some nasopharynx items showed increase tendency, while little change showed in velopharynx, glossopharynx and hypopharynx. Fat volume, tongue volume, anterior and posterior pharyngeal dimension showed age-related increase tendency, but fat deposition rate slowed down in elder age in non-snoring males, which supplies the reason why non-snoring males avoided becoming sleep apnea patients. Conclusion:We provide age-related reference data of upper airway and its surrounding tissues for further sleep and respiration research.

Objective:To compare the morphology of dental arch and base bone between oral breathing and nasal breathing children.Methods: A simultaneous measurement system was applied to test oral and nasal respiration.34 oral breathing children and 34 nasal breathing children aged 11 to 14 years old were selected.The parameters of the morphology of dental arch a nd base bone were measured on the record models.Results:① The oral breathing children showed higher palatal vault,and narrower maxillary b ase bone.The configurations of maxillary base bone were comparatively narrower a nd longer.②The oral breathing children's medial and posterior parts of arches o f maxilla were longer,and the configurations of maxillary arch were comparativel y narrower and longer.The configurations of mandible posterior arch were compara tively narrower and longer too.Conclusion:Oral breathing m ay lead to morphological changes in dental arch and base bone in children.

Objective: To design and develop a preadjusted appliance based on Chinese normal occlusion, and to apply it in treatment of malocclusion cases.Methods: According to the results of the research performed in Department of Orthodontics, School of Stomatology of Peking University about teeth position and morphology of 67 Chinese with normal occlusion, the preadjusted appliance with the optimal prescription for Chinese has been designed and developed (Z1 appliance). Z1 appliance has been used in treatment of malocclusion cases. The efficiency of Z1 appliance was evaluated. Results:The treatment of 30 non-extraction cases and 16 extraction cases has been completed with Z1 appliance. A quite good result of clinical application of Z1 appliance was represented. Conclusion: Z1 appliance could be used in treatment of Chinese malocclution. The bracket base for anterior teeth was too thick and need more improvement.

Objective:To investigate changes in the circum-maxillary sutures during alternate maxillary expansions and constrictions in a rat model.Methods:Twenty-two male Sprague-Dawley rats (6 weeks old)were used and divided into three groups.In maxillary expansion (ME)group (n=9),an expander was activated for 5 d,and then sacrificed.In alternate maxillary expansions and constrictions (Alt-MEC) group (9 animals),an alternate expansion and constriction protocol (5 d expansion and 5 d constriction for one cycle)was conducted for 2.5 cycles (25 d total),and then sacrificed.The control group com-prised 4 animals with no appliances used,each of two sacrificed on day 5 and day 25 ,respectively.Cir-cum-maxillary sutures (mid-palatal,maxillopalatine,premaxillary,zygomaticotemporal,and frontonasal suture)in each group were characterized histologically.Results:Histological findings of circum-maxil-lary sutures:in control group,the normal sutures were divided into 5 zones,the center was polygon mesenchyme zone,the lateral was mature chondrocyte zone,the next lateral was bone tissue.In ME group,the mid-palatal suture was expanded after ME,the fibre and connective tissue were extracted and invaded into cartilage zone.Osteoblast hyperplasia and new bone formation occurred.The orientation of the new bone trabecula was consistent with force.The osteoclast appeared in some area.Findings of other sutures were similar with those of control group,osteogenesis was active in some area without obvious re-construction in Alt-MEC group,mid-palatal suture and other sutures in some area were widened after Alt-MEC with much more osteoblast hyperplasia and new bone formation.Fibre and connective tissue were extracted,distorted or even broken.Sutures in some areas were narrowed with osteoblast cytopenia and osteoclast hyperplasia.Fibre and connective tissue compressed because of the different force and orienta-tion.Osteoclast count results showed that compared with the control group,the number of the osteoclast was increased only in the palatal suture in ME group (P<0.05 ).Other sutures did not show obvious changes (P>0.05).In Alt-MEC group,the numbers of the osteoclast in circum-maxillary sutures were the most,and had statistical significances (P<0.05 ).Conclusion:These results suggested that cir-cum-maxillary sutures were actively reconstructed after Alt-MEC.while only midpalatal suture had active reaction after ME.