Objective： To study the role of mechanical stress on osteoblast-like characteristics expressed by human periodontal ligament cells in vitro. Methods： Human periodontal ligament cells (hPDLC) were cultured by explant method. We investigated the gene expression for osteoblast-like marker proteins in periodontal ligament stimulated by cyclical mechanical force in vitro by in situ hybridization with non-radioisotopic oligonucleotide probe for alkline phosphatase (ALP) and osteocalcin (OCN). Results： Human periodontal ligament cells exhibited a stronger signal for ALP mRNA stimulated by cyclical mechanical force, and exhibited a moderately intense positive signal for OCN mRNA—OCN was a marker of differentiated osteoblast-like cells. Conclusion： These findings suggest that mechanical force plays role in differentiation from hPDLC to osteoblast-like cells.

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 evaluate evaluation of the changes of alveolar bone height in the periodontal patients with anterior teeth displacement before and after combined orthodontic periodontal treatment with circumferential fibrotomy. Methods: Totally 16 periodontal patients with anterior displaced teeth were analyzed after random clinical trialed as groups with and without circumferential fibrotomy of involving teeth followed by orthodontic intrusion. Evaluations of the changes of alveolar bone were given before and after treatment by means of periapical X ray film and CT scan of the involving teeth. Results: Orthodontic treatment with circumferential fibrotomy can increase the height of crest bone. Alveolar bone height was increased in the patients with circumferential fibrotomy followed by orthodontic intrusion of displaced anterior teeth. Alveolar bone height was increase by 1.2 mm on average in circumferential fibrotomy patient. In the patients with symmetric alveolar bone loss, 0.8 mm increase of alveolar bone height was observed following treatment. For the patients with asymmetric alveolar bone loss, 0.9 mm increase of alveolar bone height was detected in mild bone loss patients, but 1.4 mm and 2.2 mm increase of alveolar bone height were found in moderate and severe bone loss patients, respectively. For patients having the orthodontic treatment without circumferential fibrotomy, the alveolar bone height was increased by 0.1 mm only. Statistic significance was found between the circumferential fibrotomy group and non fibrotomy group. Conclusion: Combined orthodontic periodontal treatment with circumferential fibrotomy could correct the malpositioned teeth, and improve the periodontium conditions and gain the crest bone.

Objective　To study the parent-offspring similarity of class Ⅱ division 1 malocclusion. Methods　On the basis of family units, the polygonic curves and superimposed graphs of parents with those of the offspring were compared. Results　(1) Craniofacial structure of most parents of the class Ⅱ division 1 patients have class Ⅱ convex tendency. (2) The curves of the offspring resemble one or two of the parent′s in 84% of the families, and the resemblance mainly concentrates in skeleton. Conclusions　(1) Class Ⅱ division 1 malocclusion is characterized by familial aggregativity. (2) High probability of heredity exists in parent-offspring similarity, and we believe that hereditary factors dominate in skeletal area while in dental area there is a higher probability that environmental factors dominate.

OBJECTIVETo determine the agreement between two-dimensional radiograph and three-dimensional CT in the evaluation of the secondary alveolar bone grafting.

METHODSNine complete cleft lip and palate patients (8 UCLP, 1 BCLP) at least 6 months post secondary alveolar bone grafting were selected. The mean age of the patients was 15.5 years with a range of 12 to 26 years. Occlusal radiographs were taken and the interdental septal height was determined using Bergland criteria. There were 2 type I sites, 2 type II sites, 5 type III sites and 1 type IV site. All the patients had undergone CT scan of the cleft within two months after the radiograph was taken. The plane of scan was parallel to the occlusal plane. Cuts of 2 mm were taken from the infraorbital rim to the gingival third of the crown of the teeth. Three-dimensional reconstruction was performed.

RESULTSThe interdental septal height on the occlusal radiograph was conformed by the CT scan. Labial and palatal notch was found on CT scan at two grafting sides.

CONCLUSIONSThe study provided some evidence to support the continued cautious use of anterior occlusal radiograph in the evaluation of bone-graft success before the orthodontic treatment. When the X-ray examination is not in line with the clinical examination, CT scan is indicated.

Adolescent ; Adult ; Alveolar Process ; diagnostic imaging ; surgery ; Bone Transplantation ; Child ; Cleft Lip ; surgery ; Cleft Palate ; surgery ; Female ; Humans ; Imaging, Three-Dimensional ; Male ; Tomography, X-Ray Computed ; methods

OBJECTIVETo investigate the osteoblast-like functional characteristics exhibited by human periodontal ligament cells (hPDLCs) under mechanical force.

METHODSHuman PDLCs cultured in vitro were stretched by mechanical force. Radioimmunoassay (RIA) was used to measure the expression of secreting alkaline phosphotase (ALP) and osteocalcin (OCN). The non-secreting ALP, OCN and osteopontin (OPN) in cells were determined by immunohistochemistry.

RESULTSIt exhibited increasing of ALP secreted into conditional media, and in the 24 hour period there were two peaks which appeared at the 2nd and 4th hour and the 24th hour (P < 0.01). While in the late of the 24 hours, expression of OCN in conditional media increased (P < 0.05).

CONCLUSIONMechanical force induces hPDLCs to differentiate into functional osteoblast-like cells and plays a role in bone remodeling.

Alkaline Phosphatase ; metabolism ; Cells, Cultured ; Humans ; Osteocalcin ; analysis ; Osteoclasts ; physiology ; Osteopontin ; Periodontal Ligament ; cytology ; Sialoglycoproteins ; analysis ; Stress, Mechanical

OBJECTIVETo investigate the prevalence of malocclusion in China.

METHODSBased on individual normal occlusion and Angle's classification of malocclusion, standard investigation form was made. 25,392 children of different dental ages were evaluated by orthodontic professionals.

RESULTSThe prevalence of malocclusion among Chinese children was 67.82%. The prevalence of malocclusion among children with different dental age and the proportion of the different types of malocclusions were revealed.

CONCLUSIONThe prevalence of malocclusion among Chinese children had increased from 40% to 67% over the last 40 years.

Child ; Child, Preschool ; China ; epidemiology ; Female ; Humans ; Male ; Malocclusion ; classification ; epidemiology ; Mass Screening ; methods ; Prevalence