Objective To establish a mathematical model to describe the skeletal class Ⅲ malocclusion of patient dental and basal bone arch form, for providing a data reference and basis for further study. Methods Thirty-five patients with skeletal classⅢmalocclusion were selected in this study for computed tomography CBCT. The data of 3-D image were analyzed, and dental arch marker (Fa) and base bone arch marker (Ba) were determined. The reference plane was determined by least square method. Software Matlab 7.0 was used to calculate two-dimensional coordinate system. Based on this, a mathematical model was established to describe the dental and basal bone arch form and then to validate the mathematical model. Results (1) The mathematical model can be used to describe the dental arch form of skeletal classⅢmalocclusion, maxillary:Y=46.12 [1-(2X/70.99)2]1.052;mandibular:Y=39.16 [1-(2X/64.51)2]1.038. (2) The mathematical model can be used to describe the basal bone arch form of skeletal classⅢmalocclusion, maxillary:Y=43.14 [1-(2X/75.09)2]1.061;mandibular:Y=39.03 [1-(2X/60.63)2]1.021. (3) Fa was located at Ba labial side in the maxilla, the distance was positive. Fa was located at Ba lingual side in the mandibular, and the distance was negative. (4) The fitting correlation coefficient of beta-function curve and each tooth on the dental and basal bone arch of skeletal class Ⅲ malocclusion were greater than 0.7 (P<0.05). Conclusion In this study, the mathematical model can be used to describe the dental and basal bone arch form of the skeletal classⅢmalocclusion, which can guide further research.

Objective: To study the differences of the superficial masseter muscle morphology characteristics between adult high-angle and low-angle facial skeletal types. Methods: The subjects consisted of 37 yellow race adults,17 of them with high-angle facial skeletal type and 20 with low-angle. Ultrasound scanning was used to measure the perimeter, area, width, thickness, and length of masseter muscle. All the items were measured under relaxed, maximal clenching and maximal protrusive mandibular position.Results:①In the various mandibular positions, the masseter muscle size of adults with high-angle facial skeletal type was smaller than that of those with low-angle.②Except for the changes of width from the relaxed to maximal clenching position and from the relaxed to maximal protrusive position(P0.05).③Stature and weight influenced the size of the masseter muscle.Conclusion:The masseter muscle size of adult with high-angle facial skeletal type is smaller than that of those with low-angle.

OBJECTIVETo investigate the correlation between Angle's class III patients' occlusion plane and anterior overbite by controlling the changes in occlusion plane during orthodontic treatment.

METHODSIn total, 90 Angle's class III adult orthodontic patients were selected as the experimental group, and 30 normal adults were selected as the control group. According to the overbite, the class III patients were divided into three groups, and 14 indicators were measured. ANOVA and multiple comparison analysis were used to analyze the difference between class III patients, and linear analysis was used to analyze the correlation between anterior overbite and anterior-posterior occlusion plane.

RESULTSIn class Ill patients, posterior occlusion plane and anterior overbite size were negatively correlated (r = -0.24, P < 0.05), whereas anterior occlusal plane and anterior overbite size were positive correlated (r = 0.23, P < 0.05).

CONCLUSIONThe shape of the occlusion plane varies in different anterior overbite patients. During orthodontic treatment in different overbite class III patients, the vertical height of the posterior teeth and the rotation of the occlusion plane should be controlled.

Adult ; Dental Occlusion ; Humans ; Malocclusion, Angle Class III ; Overbite ; Tooth

Objective To compare changes in dental arch and soft and hard tissue produced by the Damon Q self-ligating bracket and 3M metal bracket with non-extraction treatment in maxillary mild-to-moderate crowding cases. Meth-ods Eighty seven patients were selected in our study, who were assigned to 4 groups by the crowding degree of maxillary and appliance type:ⅠandⅡcrowding degree using Damon Q self-ligating bracket groups (41 cases);ⅠandⅡcrowding de-gree 3M metal bracket groups (46 cases). We measured lateral cephalometric radiographs and dental casts at both beginning and end of treatment. Paired t-tests and group t-tests were used in statistical analysis to compare the alteration in dental arch and soft and hard tissue. Results There was significant increase in width and length of maxillary dental arch by non-extraction treatment withⅠandⅡcrowding degree maxillary, but the results of both groups were not of statistical difference. To compare hard and soft tissue in two groups withⅡcrowding degree maxillary, the reduction of nasolabial angle, angle of inclination of upper lip, angle of upper lip and lower lip had obvious statistical significance and it is more prominent in self-ligating bracket group than in conventional bracket group. Conclusion Using non-extraction treatment, when maxillary crowding is moderate, ,Damon Q self-ligation bracket group result in more prominent changes of upper lip protrusion than 3M bracket with more marked crowding . Therefore, clinical doctors should pay more attention to choose bracket and treat-ment system for patients with marked crowding of maxillary dentition.

OBJECTIVETo study the characteristics of the arch form of skeletal Class III malocclusion and provide references for diagnosis and treatment plan.

METHODS7 indexes in dental casts of 47 patients with skeletal Class III malocclusion and 50 individuals with normal occlusion were measured respectively. And differences between corresponding upper and lower measurements were calculated. Independent samples t-test was employed for comparing between the two groups by SPSS 17.0.

RESULTSCompared with normal occlusion sample, Class III malocclusion group had smaller anterior segment lengths and larger canine angles (P<0.05). Differences between upper and lower first premolar widths were larger in males with skeletal Class III malocclusion. And differences between upper and lower anterior segment lengths were smaller in males with skeletal Class III malocclusion (P<0.05).

CONCLUSIONArch widths of patients with skeletal Class III malocclusion are basically normal. The lengths of anterior segment are smaller and the anterior arch forms are straighter.

Bicuspid ; Dental Arch ; Dental Occlusion ; Female ; Humans ; Male ; Malocclusion, Angle Class II ; Malocclusion, Angle Class III

OBJECTIVEThe purpose of this study was to compare the differences of craniofacial characteristics of adult high-angle and low-angle facial skeletal types.

METHODSThe subjects consisted of 37 yellow race adults (17 high-angle, 20 low-angle). Fifty-three items of cephlometic radiographs were analyzed.

RESULTSThe angle of N-S-Ar and N-S-Ba, the distance of Ptm-A, Co-Go, Po-NB, and S-Go, and the thickness of the mandibular symphysis in high-angle group were smaller than these in low-angle group. The angles of SN-OP, FH-OP, PP-OP, SN-MP, FH-MP, PP-MP, S-Ar-Go, mandibular angle(Ar-Go-Me), Y-angel and SUM, the distance of S-Co, N-Me, and ANS-Me in high-angle group were greater than these in low-angle group. The index of FHI, N-ANS/N-Me, and N-ANS/ANS-Me were smaller, and ANS-Me/N-Me larger in high-angle group. Although the means of Go-Po and FH-RP were smaller in high angle group, but no statistical difference were found.

CONCLUSIONThe craniofacial morphology of adult high-angle and low-angle facial skeletal types demonstrated significant differences, especially in lower facial form.

Adolescent ; Adult ; Asian Continental Ancestry Group ; Cephalometry ; Dental Occlusion ; Facial Bones ; anatomy & histology ; diagnostic imaging ; Female ; Humans ; Male ; Maxilla ; anatomy & histology ; diagnostic imaging ; Radiography ; Reference Values ; Skull ; anatomy & histology ; diagnostic imaging

OBJECTIVEThe purpose of this study was to investigate the effects of Fränkel II appliance on the upper airway of children.

METHODSThe subjects consisted of 20 patients with Angle Class II, division I malocclusion (10 males and 10 females). The ages of all cases were ranged in 9-10 years. Each experimental subject was also served as self-control and cephalometric analysis was conducted.

RESULTSCompared with the results of pretreatment, the distance of PNS-Ba, SPP-SPPW, P-T, V-LPW and the Mcnamara line increased remarkably.

CONCLUSIONThe Fränkel II appliance can improve the sagittal dimensions of the upper airway in children.

Cephalometry ; Child ; Female ; Humans ; Male ; Malocclusion, Angle Class II ; pathology ; therapy ; Orthodontic Appliances, Functional ; Orthodontics, Corrective ; instrumentation ; Pharynx ; anatomy & histology ; Radiography ; Respiratory System ; anatomy & histology ; Skull ; diagnostic imaging

Objective: To investigate the effects of the first molar on the eruption of the third molar by comparing the changes of the third molar position after orthodontic treatment in different tooth extraction modes. Methods: 39 cases of adolescent patients were selected and divided into three groups:the first molar extraction, first premolar extraction and non-extraction.The pretreatment, posttreatment panoramic radiographs were measured to analyze the change of the third molar position among these groups. Results: There were significant differences (P< 0.05) in the average annual variation of the third molar eruption space and angle. The changes in first molar extraction group were larger than that in premolar extraction group and non-extraction group. The average annual variation of the third molar eruption space, three groups were (2.38 ± 1.62) mm, (1.61 ± 0.90) mm and (1.08 ± 1.49) mm; the average annual variation of eruption angle, the three were 1.89° ± 1.93°, 1.37° ± 1.16° and 0.83° ± 1.74°. Conclusion Compared with conventional treatment, mandibular first molar extraction can significantly increase the third molar eruption space and improve its eruption angle, which is beneficial to the eruption of the third molar.

Medical science and technology innovation activities should meet the latest requirements of Opinions Issued to Strengthen Governance over Ethics in Science and Technology. Thus, attention should paid on the challenges facing medical science and technology ethics governance. This study discussed the necessity, responsibilities and operational guarantee elements of establishing an independent and professional regional medical science and technology ethics center. On the one hand, promote the innovation and development of medical science and technology and ensure the compliance with ethical norms, On the other hand, the government needs to carry out top-level design and build a science and technology ethics system with equal emphasis on supervision and technical services.

With the development of more and more multi-center and cross-field cooperative medical research，the establishment of high-quality and efficient ethical collaborative review and mutual recognition systems is an inevitable demand for multi-institutional research，and an inevitable move to implement relevant national policies.Based on the work practice of ethical collaborative review and mutual recognition in Shenzhen，by analyzing the practical challenges of ethical collaborative review and mutual recognition in China，this paper proposed that to ensure the homogeneity and efficiency of review.Government departments need to take the lead，establish an ethical review alliance，and clarify responsibilities and rights.Based on actual needs，system first，and effective communication，ethical collaborative review and mutual recognition of results could be jointly promoted，aiming to provide a reference for our counterparts in China to promote ethical collaborative review and mutual recognition of cross-institutional research.