OBJECTIVEThe purpose of this study was to investigate the center height of clinical crowns and the difference among individuals, together with the regularity of the Spee curve in mandible and compensating curve in maxilla for the people with normal occlusion in Chengdu area.

METHODSThe data were derived from systematically collected people with normal occlusion in Chengdu area, including 36 males and 39 females (ranged from 18 to 35 years). The values of center height of clinical crowns, the depths of Spee curve and curve formed by the center of clinical crowns in mandible were obtained by measurement. Afterwards, the distribution of the center height of clinical crowns was analyzed, as well as the depth of curve formed by the center of clinical crowns in mandible and its correlation with depth of Spee.

RESULTS(1) The distribution of the center height of clinical crowns accord with normal distribution and the standard deviation was minor(< 0.5 mm); (2) There was no statistical difference between male and female for the center height of clinical crowns; (3) The depth of curve formed by the center of clinical crowns in mandible and the depths of Spee curve showed highly correlation (gamma = 0.986, P < 0.0001).

CONCLUSION(1) The difference of the center height in clinical crowns among individuals with normal occlusion in Chengdu area was minor; (2) There was no significant difference on the center height in clinical crowns between male and female; (3) Provide a recommended bracket placement chart suitable for people of Chengdu area in clinical practice; (4) The brackets of the pre-adjusted appliance should be placed in the center of clinical crowns, despite some adjustment are needed in some special circumstances.

Adolescent ; Adult ; Anthropometry ; Dental Arch ; anatomy & histology ; Dental Occlusion ; Female ; Humans ; Male ; Mandible ; anatomy & histology ; Maxilla ; anatomy & histology ; Orthodontic Brackets ; Reference Values ; Tooth Crown ; anatomy & histology

The shape of dental arch for orthodontic diagnosis and treatment is of great significance. This paper presents an automated method for detecting the dental arch form. Firstly, 3D teeth data model is retrieved by the 3D-optical measuring system. Secondly, the occlusal plane is computed by interactively picking up four feature points. Thirdly, the feature point set is filtered by the rule and two-step curve fitting method is used to obtain the dental arch form. Finally, some examples are tested in this work and the results demonstrate that the proposed algorithm is effective and feasible.
Computer Graphics ; Computer Simulation ; Dental Arch ; anatomy & histology ; Dental Models ; Humans ; Imaging, Three-Dimensional ; methods ; Malocclusion ; diagnosis ; therapy ; Pattern Recognition, Automated

Occlusal-maxillo-facial structural change of crossbite malocclusion after orthodontic therapy by modified ACTIVATOR appliance was investigated. Eighty crossbite cases of deciduous dentition and mixed dentition were treated by modified ACTIVATOR. Through pre- and post-treatment analysis of stone model, Schuller's position X-ray and craniofaciometrics, the change in craniofacial length, width and height in early-phase crossbite malocclusion was studied. The results showed that there was no significant change in the width of maxillary and mandibular dental arch. Maxillary length and protrusion was increased significantly, upper incisors slopped labially. The lower incisors slopped lingually, mental angle decreased more severely. The lower and posterior facial height was increased to normal level.
Cephalometry ; Dental Arch/anatomy & histology ; Dental Stress Analysis ; Dentition, Mixed ; Malocclusion/*therapy ; Maxilla/*anatomy & histology ; Maxilla/growth & development ; *Orthodontic Appliances, Removable ; Orthodontics, Corrective/*instrumentation ; Orthodontics, Interceptive/instrumentation ; Tooth, Deciduous

Occlusal-maxillo-facial structural change of crossbite malocclusion after orthodontic therapy by modified ACTIVATOR appliance was investigated. Eighty crossbite cases of deciduous dentition and mixed dentition were treated by modified ACTIVATOR. Through pre- and post-treatment analysis of stone model, Schuller's position X-ray and craniofaciometrics, the change in craniofacial length, width and height in early-phase crossbite malocclusion was studied. The results showed that there was no significant change in the width of maxillary and mandibular dental arch. Maxillary length and protrusion was increased significantly, upper incisors slopped labially. The lower incisors slopped lingually, mental angle decreased more severely. The lower and posterior facial height was increased to normal level.
Cephalometry ; Child ; Child, Preschool ; Dental Arch ; anatomy & histology ; Dental Stress Analysis ; Dentition, Mixed ; Female ; Humans ; Male ; Malocclusion ; therapy ; Maxilla ; anatomy & histology ; growth & development ; Orthodontic Appliances, Removable ; Orthodontics, Corrective ; instrumentation ; Orthodontics, Interceptive ; instrumentation ; Tooth, Deciduous

OBJECTIVETo investigate the development of third molar embryo and establish the normal value of posterior arch length of adolescence in Chengdu.

METHODSThe samples consisted of 40 males and 41 females with Class 1 dentitions, normal second molar occlusion, no history of orthodontic treatment, and good facial balance. Cephalometry and statistic analysis were conducted for all the subject.

RESULTSThe normal value of posterior arch length of maxilla in male was(16.52 +/- 2.35) mm and in female was(16.42 +/- 2.55) mm. The normal length of mandible was(13.00 +/- 2.44) mm in male and(12.43 +/- 2.18) mm in female. But statistic analysis showed no gender difference. Most of the third molar embryo had been formed and their tooth crowns had been calcified, the occurrence ratio was 84.0% in maxilla and 85.2% in mandible. Most of them located in the middle and inclined mesially.

CONCLUSIONThe data obtained in this study will be valuable for our clinical practice and be helpful for the study concerning dento-facial growth and development.

Adolescent ; Alveolar Process ; anatomy & histology ; diagnostic imaging ; Cephalometry ; Child ; Dental Arch ; anatomy & histology ; diagnostic imaging ; Dental Occlusion ; Dentition ; Female ; Humans ; Male ; Mandible ; anatomy & histology ; diagnostic imaging ; Maxilla ; anatomy & histology ; diagnostic imaging ; Molar, Third ; anatomy & histology ; diagnostic imaging ; Radiography ; Reference Values ; Tooth Migration

OBJECTIVEThe purpose of this study was to study the changes of available spaces of posterior arch segments in mandible dentitions (ASPAS) from ages of 11 to 20 years, which would provide information on normal growth and development of the dental arches in teenagers in Chengdu area.

METHODSThe data were derived from systematically collected preorthodontic lateral cephalograms of 526 patients, including 232 males and 294 females from the Orthodontic Department of West China College of Stomatology, Sichuan University during the period of 1999-2000 (aged 11-20 years). The values of ANB angle, FH-MP, ASPAS were obtained using the cephalometric analysis. Afterwards, the growth changes of ASPAS from the subjects and their correlations with age, gender, angle malocclusion types and vertical skeletal patterns were analyzed.

RESULTSASPAS was related to age and class II angle malocclusion. Though gender was not associated with ASPAS, significant differences in curves of ASPAS were found between males and females. The growth changes of ASPAS in the patients with skeletal Class III malocclusion were more obvious than in patients with Class I and II malocclusion.

CONCLUSIONOur results reveal that significant differences were demonstrated in growth change values in posterior available spaces of patients with different races and angle malocclusion types.

Adolescent ; Asian Continental Ancestry Group ; Dental Arch ; anatomy & histology ; pathology ; Dentition ; Female ; Humans ; Male ; Malocclusion ; diagnostic imaging ; pathology ; Mandible ; anatomy & histology ; diagnostic imaging ; pathology ; Orthodontics, Corrective ; Pilot Projects ; Radiography ; Reference Values