The application of frontal sinus index and frontal sinus area in sex estimation based on lateral cephalograms among Han nationality adults in Xinjiang.

The frontal sinus, due to its unique anatomical features, has become an important element in research for individual identification. Previous studies have demonstrated the use of frontal sinus as an indicator for sex discrimination; however, the sex discrimination rate using frontal sinus was lower compared to that using the traditional morphological methods. In order to improve the sex discrimination percentage, we developed a new method involving the measurement of the frontal sinus index and frontal sinus area from lateral cephalogram radiographs. In this study, 475 digital lateral cephalograms of adult Han citizens from Xinjiang were included. The maximum height, depth, and area of the frontal sinus were calculated using the NemoCeph NX software. The frontal sinus index (ratio of the maximum height to the depth of frontal sinus) was also computed. Statistical analysis results showed significant differences in the frontal sinus index and area between males and females. Discriminant function equation derived from this study differentiated between sexes with 76.6% accuracy. The results demonstrated that the use of frontal sinus index and area for sex discrimination was more accurate than using the frontal sinus index alone.

[Measurement of anterior teeth widths in 236 Uygur teenagers].

PURPOSE: In order to provide reference for orthodontic and esthetic dentistry, we measured anterior teeth widths, and analyzed the ratio between the teeth in 236 Uygur teenagers. METHODS: Two hundred and thirty-six samples were selected from Uygur population,Vernier calipers was used to measure the widths of the anterior teeth. SPSS21.0 software package was used for independent sample t test, paired t test and REG regression. RESULTS: Except for mandibular lateral incisors, significant difference was observed in anterior teeth widths between males and females, the ratio between the upper and lower central incisors in males was nearly 1.618; the ratio between upper central incisor and lower central incisor, upper central incisor and lower lateral incisor, upper canine and lower lateral incisor in females was not approaching 1.618, i.e. There was no "golden proportion". There was significant correlation between anterior teeth of Ugyur teenagers. CONCLUSIONS: No "golden proportion" was found in anterior teeth widths of Ugyur teenagers, but a specific ratio exists.

[Anatomy of temporomandibular joint and condyle position in Uygur adult patients evaluated with cone-beam CT].

PURPOSE: To compare the anatomy and condyle-fossa relationship difference between Uygur adult patients with Class I and Class II division 1 malocclusion by three dimensional cone-beam CT (CBCT). METHODS: Sixty-four patients with Class I and Class II division 1 malocclusion were selected, and the CBCT scans of their temporomandibular joints were taken.The difference of the condylar morphology and location between Class I and Class II division 1 patients was analyzed with SPSS 17.0 software package. RESULTS: The position of condyle in the TMJ fossa was not significantly different between the two groups; in Class II division 1 malocclusion group, the mandibular fossa depth, anterior joint space and the superior joint space were significantly bigger (P<0.05), but the posterior joint space was significantly smaller than those in Class I malocclusion group (P<0.05). CONCLUSIONS: There were difference in condyle position and TMJ morphology between Class I and Class II division 1 malocclusion group in Uygur adult patients.

The study on facial soft tissue thickness using Han population in Xinjiang.

Facial profile is an important aspect in physical anthropology, forensic science, and cosmetic research. Thus, facial soft tissue measurement technology plays a significant role in facial restoration. A considerable amount of work has investigated facial soft tissue thickness, which significantly varies according to gender, age, and race. However, only few studies have considered the nutritional status of the investigated individuals. Moreover, no sufficient research among Chinese ethnic groups, particularly Xinjiang population in China, is currently available. Hence, the current study investigated the adaptability of facial soft tissue to the underlying hard tissue among young adults of Han population in Xinjiang, China; the analysis was performed on the basis of gender, skeletal class, and body mass index (BMI). Measurements were obtained from the lateral cephalometric radiographs of 256 adults aged 18-26 years old. Differences in soft tissue thickness were observed between genders and among skeletal classes. With regard to gender, significant differences in soft tissue thickness were found at rhinion, glabella, subnasale, stomion, labrale superius, pogonion, and gnathion among different BMI groups. Thus, nutritional status should be considered when reconstructing an individual's facial profile. Results showed that the thinnest and thickest craniofacial soft tissues existed in rhinion and lip regions, respectively. Overall, this research provides valuable data for forensic facial reconstruction and identification of young adults in Xinjiang, China.

Reliability of mandibular canine and mandibular canine index in sex determination: A study using Uyghur population.

Sex determination is a key process that is required to establish the forensic profile of an individual. Mandibular canine index (MCI) method yields fairly positive results for sex determination. However, this method has been challenged by a few authors. This study aimed to examine the reliability of MCI in Chinese Uyghur population and to establish its normal value for this ethnic group. Dental casts of 216 students (117 males and 119 females) from the College of Stomatology of Xinjiang Medical University in China were used to determine the sexing accuracy of MCI. The mesiodistal (MD) dimension of mandibular canine crowns, the inter-canine distance, and the MCI were calculated. The accuracy of the standard MCI derived from the current data was compared with that of the standard MCIs derived from previous data. Results were statistically described using the independent-samples t-test. The MD dimension of mandibular crown, the inter-canine distance, and the MCI exhibited statistically significant sexual dimorphism. Sex determination using the MCI derived from the current data revealed fairly reliable results. Therefore, MCI is a reliable method for sex determination for Uyghur population, with 0.248 as standard MCI value.

Finite element analysis of rapid canine retraction through reducing resistance and distraction.

OBJECTIVE: The aims of this study were to compare different surgical approaches to rapid canine retraction by designing and selecting the most effective method of reducing resistance by a three-dimensional finite element analysis. MATERIAL AND METHODS: Three-dimensional finite element models of different approaches to rapid canine retraction by reducing resistance and distraction were established, including maxillary teeth, periodontal ligament, and alveolar. The models were designed to dissect the periodontal ligament, root, and alveolar separately. A 1.5 N force vector was loaded bilaterally to the center of the crown between first molar and canine, to retract the canine distally. The value of total deformation was used to assess the initial displacement of the canine and molar at the beginning of force loading. Stress intensity and force distribution were analyzed and evaluated by Ansys 13.0 through comparison of equivalent (von Mises) stress and maximum shear stress. RESULTS: The maximum value of total deformation with the three kinds of models occurred in the distal part of the canine crown and gradually reduced from the crown to the apex of the canine; compared with the canines in model 3 and model 1, the canine in model 2 had the maximum value of displacement, up to 1.9812 mm. The lowest equivalent (von Mises) stress and the lowest maximum shear stress were concentrated mainly on the distal side of the canine root in model 2. The distribution of equivalent (von Mises) stress and maximum shear stress on the PDL of the canine in the three models was highly concentrated on the distal edge of the canine cervix. . CONCLUSIONS: Removal of the bone in the pathway of canine retraction results in low stress intensity for canine movement. Periodontal distraction aided by surgical undermining of the interseptal bone would reduce resistance and effectively accelerate the speed of canine retraction.

Finite element analysis of rapid canine retraction through reducing resistance and distraction

Objective: The aims of this study were to compare different surgical approaches to rapid canine retraction by designing and selecting the most effective method of reducing resistance by a three-dimensional finite element analysis. Material and Methods: Three-dimensional finite element models of different approaches to rapid canine retraction by reducing resistance and distraction were established, including maxillary teeth, periodontal ligament, and alveolar. The models were designed to dissect the periodontal ligament, root, and alveolar separately. A 1.5 N force vector was loaded bilaterally to the center of the crown between first molar and canine, to retract the canine distally. The value of total deformation was used to assess the initial displacement of the canine and molar at the beginning of force loading. Stress intensity and force distribution were analyzed and evaluated by Ansys 13.0 through comparison of equivalent (von Mises) stress and maximum shear stress. Results: The maximum value of total deformation with the three kinds of models occurred in the distal part of the canine crown and gradually reduced from the crown to the apex of the canine; compared with the canines in model 3 and model 1, the canine in model 2 had the maximum value of displacement, up to 1.9812 mm. The lowest equivalent (von Mises) stress and the lowest maximum shear stress were concentrated mainly on the distal side of the canine root in model 2. The distribution of equivalent (von Mises) stress and maximum shear stress on the PDL of the canine in the three models was highly concentrated on the distal edge of the canine cervix. . Conclusions: Removal of the bone in the pathway of canine retraction results in low stress intensity for canine movement. Periodontal distraction aided by surgical undermining of the interseptal bone would reduce resistance and effectively accelerate the speed of canine retraction. .

[The prevalence of orthodontic treatment need in Urumqi Han's adolescent].

OBJECTIVE: To assess the severity of malocclusion and the need for orthodontic treatment in Urumqi Hans' adolescent. METHODS: 562 children aged from 11-19 years old were chosen randomly and were investigated. The severity of malocclusion and the need for orthodontic treatment were assessed using the Malocclusion Severity Index (MSI, Hill PA 1992). RESULTS: The MSI scores for this population were 21.91 +/- 17.09 in male and 22.28 +/- 17.26 in female, respectively, there were no significant differences between sexes (P > 0.05). According to the classifications of MSI scores, the rates of the need for orthodontic treatment were 54.55% in male and 55.40% in female. CONCLUSIONS: (1) The rates of orthodontic treatment need in Urumqi Hans' adolescent were highly frequent. (2) The MSI is a simple precise valid index for assessing the orthodontic Treatment Need. It is suggested to be used widely.