Objective The facial soft tissue features were studied in Urumqi adolescent with skeletal Ⅱ malocclusion by using a polar coordinate system. Methods Sixty samples of Urumqi adolescent with skeletal Ⅱ malocclusion were selected, each one underwent cephalometrics analysis and 32 cephalometric parameters from the samples were measured. The mean and standard deviations of each measurement were compared by statistical analysis (t-test). Results Polar distance in male was larger than female, showing significant difference between male and female. Po-Ns/Po-Li, Po-Ns/Po-Bs, Po-Ns/PoPgs, Po-Ns/Po-Gns, and Po-Ns/Po-Mes showed significant difference between male and female. Polar angles in female were larger than male, with a significant difference between male and female.Conclusion Statisticalstudies on features of facial soft tissue show significant differences between male and female. The polar coordinate analysis system is a good index to study the growth magnititude and direction of facial soft tissue during growth and development or before treatment and after treatment.

BACKGROUND: Palatal implant could be an effective type of anchorage that can afford long-term stress, and bone thickness and bone density of the implant placement will affect the success of the implant stability. Presently, actinoscopy commonly used in stomatological clinic cannot provide the precise information of palatal bone thickness and bone mineral density such as toroidal slide plate photograph and skull lateral projection. OBJECTIVE: To measure the thickness and density of median palatine suture, and to provide the consultation for implant anchorage using spiral CT. DESIGN, TIME AND SETTING: A measurement study was performed at the Medical Imaging Center, First Affiliated Hospital of Xinjiang Medical University from July to December in 2008 PARTICIPANTS: The sample consisted of 194 cases undergoing 64 slice CT at the Medical Imaging Center of First Affiliated Hospital of Xinjiang Medical University, including the scope of the hard palate and maxillary dentition. They were aged from 18 to 50, and divided into three groups by age, 18-30-year-old group, 31-40-year-old group, and 41-50-year-old group. METHODS: Measurement of palatal raphe area first three-dimensional reconstruction of images at up to nasion plane centerline, whichever was determined as a reference surface plane, selection one point on incisor cervix in this line, to measurement of the available palatal bone height; sagittal views were selected at 6 mm dorsally from the incisive canal. The available bone height was defined as the distance from the palatal baseline (lower cortical border of the palate) to the nasal cavity (upper cortical border of the nasal cavity). Bone mineral density can also be measured at the same site, take the average of the cortical and cancellous bone. MAIN OUTCOME MEASURES: The palatal bone thickness and bone thickness density were measured at 6 mm dorsally from the incisive canal. RESULTS: Male in the palatal bone thickness and bone mineral density were significantly higher than female (P < 0.05); there were no significant difference between Han and Uygur (P>0.05). In different age's group of men and women, the palatal bone thickness and bone mineral density showed no statistical difference (P > 0.05). Age, palatal bone thickness and palatal bone mineral density had no significant correlation. CONCLUSION: Spiral CT can be used in different parts of mandible thickness and density measurement and analysis. The palate raphe can be implant as orthodontic anchorage if it measured exactly.

Objective To establish a three-dimensional finite element model of rapid canine tooth movement by reducing resistance and distracting procedures,and to discuss canine distal movement and force distribution of periodontium,and to provide theory basis for its clinical application.Methods Through 64-slice spiral scanning,temporomandibular joint (TMJ),the mandible,lower jaw denture section phantom DICOM data were obtained.Mimics software,Geomagic Studio 8.0 software,Unigraphics NX software,and Ansys11.0 software were mixed,and the three-dimensional finite element model were established under the conventional condition to move the canine (model 1 ),rapid canine movement through distracting osteggenesis of the periodontal ligament (model 2),rapid canine movement tooth movement through reducing resistance and distracting method (model 3),the strength were carried on three kind of models and the canine,the pericementum,the tooth socket bone stress distribution were observed.Results The biggest displacements on those three models occured in canine crown on 1/3,biggest displacement quantity:model 3 ＞model 2 ＞model 1,and the canine crown displacement reduced gradually from crown to the root point; in the model 1 most greatly equivalent stress mainly concentrated in the middle of distal alveolar crest,but in the models 2 and 3 most greatly equivalent stress centralism area shifted liguodistal alveolar crest.Conclusions In the process of canine distal movement,reducing bone resistance,can accelerate the tooth moving speed effectively and simultaneously,the canine has distal motion tendency.While under the action of force,the canine tends to move ligually with the canine distal movement,and thus appropriate measures should be taken to prevent canine lingual rotation in clinical work.

BACKGROUND:The cytokine has an effect of immunoregulation and immediate induction in the reconstruction of periodontal tissue. At present, the role and mechanism of hepatocyte growth factor involving the reconstruction of periodontal tissue under orthodontic force are stil unclear.
OBJECTIVE:To explore the mechanism underlying hepatocyte growth factor in the tooth movement and periodontal tissues remodeling under the inflammation periodontal tissue condition.
METHODS:Thirty Sprague-Dawley rats, aged 8 weeks, were used to establish periodontitis model. The obtained model was randomly divided into two groups:inflammatory control group and inflammatory force group. In the force group, rats were treated with the fixed orthodontic appliance by 50 g forces in the maxil ary first molars. After 1, 3, 5, 7 and 14 days of tooth movement, five rats were sacrificed respectively. Hematoxylin-eosin staining and immunohistochemistry methods were used to analyze the expression and distribution of hepatocyte growth factor in the periodontium for rats at different tooth movement stages.
RESULTS AND CONCLUSION:Hematoxylin-eosin staining results showed that, remodeling of periodontal tissues existed in al groups. (2) The immunohistochemical results showed that hepatocyte growth factor had positive expression in periodontal tissue, and the distribution was even in the control group. In the force group, hepatocyte growth factor expression was increased and reached the peak on day 5, then began to decline. Osteoblast, fibroblast and osteoclast were strongly expressed. The findings indicate that, hepatocyte growth factor is involved in the periodontal tissues remodeling under orthodontic force, and inflammation can increase the expression of hepatocyte growth factor in periodontal tissue.

BACKGROUND:As an important cytokine, interleukin-6 regulates immune responses in inflammation sites and has an autocrine/paracrine activity that stimulates osteoclast formation and bone resorption, which is related to bone remodeling during orthodontic tooth movement.
OBJECTIVE:To investigate the effects of orthodontic force on the expression of interleukin-6 mRNA in the periodontal tissue of rats.
METHODS:In situ hybridization was performed to measure the expression of interleukin-6 mRNA at 1, 3, 5, 7, 10 and 14 days after the application of orthodontic force on the maxil ary first molars of rats.
RESULTS AND CONCLUSION:The expression of interleukin-6 mRNA was observed at a low level in the normal periodontal tissue of rats. After the application of force, the induction of interleukin-6 mRNA was observed to reach a maximum on day 3 and to decline thereafter. The expression of interleukin-6 mRNA can be evoked by orthodontic force but with a certain self-limiting. As a multifunctional cytokine, interleukin-6 plays a very important role in periodontal remodeling during orthodontic tooth movement.

BACKGROUND:Cigarette smoking can seriously damage the periodontal tissues and root, and the nicotine in tobacco accelerates the progression of periodontal diseases. OBJECTIVE: To investigate the effect of different doses of nicotine on the expression of cyclooxygenase-2 mRNA in the periodontal tissue during orthodontic tooth movement. METHODS: Totaly 110 Sprague-Dawley rats were randomly divided into blank control group (n=10), normal saline group (n=25), 0.5 mg/kg nicotine group (n=25), 0.75 mg/kg nicotine group (n=25), 1 mg/kg nicotine group (n=25). Rats in the normal saline groups were injected intraperitonealy with 0.1 mL normal saline, and those in the three nicotine groups were respectively injected with 0.5, 0.75, 1 mg/kg nicotine tartrate solution. Except the blank control group, the unilateral maxilary first molars of rats in the other four groups were exposed to 50 g force. At 1, 3, 5, 7, 14 days under force, the rats were sacrificed to take the maxilary tissues. Hematoxylin-eosin staining was used to observe the changes of periodontal tissues, immunohistochemical staining was employed to count positive cels, andin situ hybridization staining was adopted to detect the mean absorbance value of cyclooxygenase-2 in the periodontal tissues. RESULTTS AND CONCLUSION:The number of odontoclasts and the expression of cyclooxygenase-2 in the nicotine groups were higher than those in the non-nicotine groups. With the increasing dose of nicotine, the number of odontoclasts gradualy increased, and the difference was statisticaly significant (P < 0.05). At 7 days under force, the number of odontoclasts reached the peak. With the increasing dose of nicotine, the positive expression intensity of cyclooxygenase-2 was also increased, and the difference was statisticaly significant (P < 0.05). The expression of cyclooxygenase-2 reached peak at 5 days under force. These findings indicate that with the increasing dose of nicotine, the number of odontoclasts and the expression intensity of cyclooxygenase-2 are both increased at the same time point under force. During the orthodontic tooth movement, the intake of nicotine can damage the periodontal tissue, and the dose of nicotine can directly influence the severity of damage to the periodontal tissue.

Objective:To investigate the effects of bone morphogenetic protein 2(BMP-2)expression in the related periodontal tissue on bone remodeling under different distracting force during rapid tooth movement by resistance reduction and distraction. Methods:1 2 Beagle dogs were randomly divided into 4 groups as follows:5 d distraction,1 5 d distraction,1 5 d distraction and 1 0 d retaining and 1 5 d distraction and 90 d retaining.4 4 were distalized.6 teeth in each group were randomly assigned to re-sistance and distracting method,resistance and conventional method and conventional method,and there were 2 teeth in each group.Moving teeth models were prepared regularly.BMP-2 expression was examined by immunohistochemistry.Results:The BMP-2 positive expression of the 3 groups of different distraction schedule showed similar distribution area,and it reached peak at the end of 1 5-day distration,but the group of resistance and distracting method showed the maximum peak(P <0.05)and maximum tooth movement(P <0.01 ).In different stages of distraction,the positive expression in the group of resistance reduc-tion and conventional method was higher than in the group of conventional method but lower than the group of resistance reduction and extraction method(P <0.05).There was no significant difference in BMP-2 positive expression among 3 groups when retai-ning was 90 d(P >0.05).Conclusion:Resistance reduction with sustained strong distracting force can significantly increased the positive expression of BMP-2 and effectively accelerate new bone formation in periodontal tissue.

BACKGROUND:It is very important to appreciate the Sagittal discrepancy during the diagnosis and therapy in orthodontics patients.At present,ANB angle,AXB angle,Beta angle and APDI value were often used to evaluate the mandible and maxilla relationships in orthodontic clinic.Correlation and variance degree among these parameters were analyzed to judge the reliability.OBJECTIVE:To compare the reliability of ANB angle,AXB angle,Beta angle and APDI value in assessing sagittal discrepancy between mandible and maxilla in transitional dentition cases with Angle's class Ⅲ malocclusion.METHODS:Totally 56 patients of Angle's class Ⅲ malocclusion in transitional dentition at the Department of Orthodontics,First Affiliated Hospital of Xinjiang Medical University,between January 2004 and June 2009,were selected.ANB angle,AXB angle,Beta angle and APDI value of Angle's class Ⅲ malocclusion in transitional dentition were measured on the cephalometric radiographs.The radiographs were scanned by Microtek Phantom 9800 XL scanner at proportion of 1:1 with 300 dpi pixels,and saved as JPG format.The JPG pictures were fixed-point using Photoshop 8.0 to measure ANB angle,AXB angle,Beta angle and APDI value,the mean value was obtained after 3 times measurement.The correlation and variance degree among these parameters were analyzed.RESULTS AND CONCLUSION:Significant correlation was found among ANB angle,AXB angle,Beta angle and APDI value (P＜0.05).The coefficients of variation for the 4 indexes were 1.35,0.75,0.07 and 0.04,respectively.The results demonstrated that,it is accurate to use ANB angle,AXB angle,Beta angle and APDI value as cephalometric norm to evaluate sagittal discrepancy of maxmandibul in transitional dentition cases with Angle's class Ⅲ malocclusion.However,the APDI value is more reliable as cephalometric norm.

BACKGROUND:Beta angle,as a new index for the assessment of sagittal jaw relationship,has been widely used by clinical doctors.However,hand-made measurement but not academic software is still adopted in some hospital.OBJECTIVE:To study the beta angle of different skeletal patterns in Urumqi city for the clinical use of the method to assess the sagittal jaw relationship,and verify the possibility of Photoshop software to measurement of beta angle.DESIGN,TIME AND SETTING:An observational experiment and measurement design was performed at Department of Orthodontics,the First Affiliated Hospital of Xinjiang Medical University from July 2006 to May 2009.PARTICIPANTS:A total of 262 malocclusion cases including 94 males and 168 females were lived in Urumqi City.They were divided into three groups based on type of facies ossea,including type Ⅰ group (n=119),type Ⅱ group (n=74),and type Ⅲ group (n=69).METHODS:Lateral position of skull was photographed using X-ray,and beta angle was measured using Photoshop 8.0 software.Sex and type of facies ossea were compared using one-way analysis of variance and t test.MAIN OUTCOME MEASURE:Beta angle of male and female;beta angle of the types Ⅰ,Ⅱ,and Ⅲ.RESULT:There was no significant difference in beta angle between males and females (P>0.05).Beta angle of type Ⅰ was (34.15±3.88)°,that of type Ⅱ was (26.42±2.65)°,and that of type Ⅲ was 42.41°±1.88°.There was significant difference in beta angle among three types of facies ossea (P<0.01).CONCLUSION:Beta angle is an index for the assessment of sagittal jaw relationship.The reference range of the beta angle is 30°-38°.Photoshop 8.0 software is a novel tool to measure cephalometry.

BACKGROUND:To make a better preparation for orthodontic tooth, we investigate the changes in the localization of the anterior wal of the maxilary sinus and maxilary tuberosity, analyze the development of the maxila, and detect the bone mass of the maxila and development timing. However, the use of Auto-CAD software has not been reported to localize the anterior wal of the maxilary sinus and maxilary tuberosity. OBJECTIVE: To investigate the localization and growth of the anterior wal of the maxilary sinus and maxilary tuberosity in 300 children aged 4-14 years from the Han ethic group in Urumqi, Xinjiang Uygur Autonomous Region, China. METHODS: Totaly 300 children, 4-14 years of age, admitted at the Stomatological Hospital of Urumqi, Xinjiang Uygur Autonomous Region, China, were enroled. According to Helman’s dental developmental staging, these children were divided into five groups: groups IIA, IIC, IIIA, IIIB, IIIC. Auto-CAD software was used to analyze the panoramic radiographs of the maxila and mandible. The tracing of each radiograph was digitized by translating the reference points onto an X-Y coordinate system. The straight line that passed the point where the nasal septum intersected with the hard palate (point O) and the point where the medial wal of maxilary sinus intersected with the hard palate (point PA) was designated as the X axis. The straight line that was vertical to the X axis and passed through the point O at a right angle was designated as the Y axis. The X and Y coordinate values of reference point were calculated. And then O point was set as (0, 0), and the point where the posterior wal of maxilary tuberosity intersected with the hard palate (PP) was set as (PPX, PPY). Colected data were analyzed statisticaly to understand the changes in the localization of PA and PP at different stages of dental development. RESULTS AND CONCLUSION:The change of point PA had on significant differences between the five groups (α > 0.05). Point PP grew obviously in a horizontal rearward and vertical downward manner from stage IIA to IIIA; this point only presented a horizontal rearward growth from stage IIIA to IIIB and only a vertical downward growth from stage IIIB to IIIC. This period was the time of the second molar eruption, indicating that the second molar eruption is helpful to the vertical growth of the maxila.