Changes in Dental Arch and Hard and Soft Tissue Caused by the Self-Ligating Bracket and Conventional Bracket with Non-Extraction Treatment in Maxillary Mild-to-Moderate Crowding Cases / 天津医药

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.

Analysis of dental arch dimensions in three Colombian ethnic groups / Análisis de las dimensiones del arco dental en tres grupos étnicos colombianos

The purpose of this study was to compare dental arch transversal and anteroposterior dimensions in three ethnic groups from Colombia. A digital caliper was used to take 16 transversal and two sagittal measurements, 9 for the upper jaw and 9 for the lower jaw. The sagittal measure determining arch length was drawn from a mesial line traced from first right permanent molar to first left permanent molar, and a perpendicular line from the point of contact between central incisive teeth, both for the upper and lower jaw. The dimensions of upper dental arch in the three ethnic groups showed differences in intercanine distance, as well as between premolar and between molar teeth. The same differences were found for lower dental arches. The populations evaluated show distinctive characteristics in dental arch dimensions, thus the mestizo population had narrow arches while the natives had wide arches.

El propósito de éste estudio fue comparar las dimensiones transversal y anteroposterior del arco dental en tres grupos étnicos de Colombia. Se utilizó un calibrador digital para tomar 16 medidas transversales y dos sagitales, 9 maxilares y 9 mandibulares. La medida sagital para determinar la longitud del arco se elaboró a partir de una línea trazada desde mesial primera molar derecho permanente al primer molar izquierdo permanente, y una línea perpendicular desde el punto de contacto entre los incisivos centrales, tanto para el maxilar y mandíbula. Las dimensiones del arco dental maxilar en los tres grupos étnicos mostraron diferencias en la distancia intercanina, así como entre premolares y molares. Las mismas diferencias se encontraron en la mandíbula. Las poblaciones evaluadas presentan características distintivas en las dimensiones del arco dental, por lo que la población mestiza tuvo arcos estrechos, mientras que los nativos tuvieron arcos anchos.

Posterior arch length of individual normal occlusion of adults in Lanzhou / 中国组织工程研究

BACKGROUND:Posterior arch length deficiency is closely related to the formation and development of malocclusion. OBJECTIVE:To measure the posterior arch length in individual normal occlusions of adults in Lanzhou. METHODS:A total of 102 current col ege students with individual normal occlusions, with a mean age of (19.33±2.67) years (range 18-24 years), including 47 males and 55 females from Gansu Province, were chosen to take lateral cephalograms. Al research objects were divided into three groups according to mandibular plane angle:high angle group (Frankfort mandibular-plane angle>32°), low angle group (Frankfort mandibular-plane angleRESULTS AND CONCLUSION:Posterior arch length of maxil ary arch was slightly longer in male group than that in female group, and the difference was not significant (P>0.05). The posterior arch length of mandibular arch was slightly longer in male group than that in female group, but the difference was no significant (P>0.05). Comparison between groups revealed that the posterior arch length of low angle mandibular arch was significantly longer than that of high angle mandibular arch in male group, and the difference was significant (P<0.05). The results indicate that the gender wil not influence the development of posterior arch length. Different vertical facial types and different genders have different posterior arch length in individual normal occlusions of adults

Evaluation of the lower incisor inclination during alignment and leveling using superelastic NiTi archwires: a laboratory study

OBJECTIVE: The aim of this laboratory study is to evaluate the influence of the shape and the length limitation of superelastic nickel-titanium (NiTi) archwires on lower incisors inclination during alignment and leveling. METHODS: Metal teeth mounted on a typodont articulator device were used to simulate a malocclusion of the mandibular arch (-3.5 mm model discrepancy). Three different shapes (Standard, Accuform and Ideal) of superelastic NiTi archwires (Sentalloy, GAC, USA) were tested. Specimens were divided in two groups: Group I, with no limitation of the archwire length; and Group II, with distal limitation. Each group had thirty specimens divided into three subgroups differentiated by the archwire shape. All groups used round wires with diameters of 0.014-in, 0.016-in, 0.018-in and 0.020-in. The recording of all intervals was accomplished using standardized digital photographs with orthogonal norm in relation to median sagittal plane. The buccolingual inclination of the incisor was registered using photographs and software CorelDraw. RESULTS: The results were obtained using ANOVA and Tukey's test at a significant level of 5%. The inclination of the lower incisor increased in both groups and subgroups. The shape of the archwire had statistically significant influence only in Group I - Standard (11.76º), Ideal (5.88º) and Accuform (1.93º). Analyzing the influence of the length limitation, despite the mean incisor tipping in Group II (3.91º) had been smaller than Group I (6.52º), no statistically significant difference was found, except for Standard, 3.89º with limitation and 11.76º without limitation. The greatest incisor tipping occurred with the 0.014-in archwires.

Changes of the maxillary arch produced by different self-ligating appliance systems during the leveling and aligning phases / 实用口腔医学杂志

Objective:To evaluate the changes in the transverse dimension and the perimeters of the maxillary archs produced by 3 self-ligating appliance systems during the leveling and aligning phases. Methods: 45 patients who had class I skeletal pattern and upper arch crowding 3-6 mm were divided into 3 groups with 15 subjects in every group. The dental casts were analyzed. Results: Statistically significant increases were recorded of all dentoalveolar widths (with the exception of intermolar width measured lingually) and arch perimeters. The increase in arch perimeter showed a significant negative relationship with the individual perimeter of the maxillary arch before treatment. No significant change was found in arch depth. Conclusion: The self-ligating appliance systems produce statistically significant increases in the transverse dentoalveolar width and the perimeter of the maxillary arch during the leveling and aligning phases of treatment.

A study of the arch length discrepancy and the diagnostic analysis / 대한치과교정학회지

Predicting the arch length discrepancy by simply comparing the available arch perimeter with tooth materials is merely a 2-dimensional analysis of the teeth movement. However, the real teeth movement takes place 3-dimensionally and is affected by various factors such as, the arch form, the curve of Spee and the axis of the incisors. The purpose of this study is to clarify the relationship between the decrease in the arch perimeter and the horizontal positional change of the incisors after extraction of the 1st bicuspids, for more analytic evaluation of the arch length discrepancy at pre-treatment model analysis stage. In addition to that to evaluate the effect of the curve of Spee, teeth axis to the basal plane, and the incisional crowding to the treatment outcome. All patients were treated at the department of orthodontics, dental hospital, Yonsei university. Inclusion criteria for patients selection were as follows. -Angle classification I malocclusion with bialveolar protrusion -Extraction of 4 1st bicuspids -No tooth anomaly or prosthesis -No abnormal attrition -No ectopically erupted teeth -Angle classification I canine and molar relationship -Less than 3mm of crowding Model analysis of the above patients was performed and the following conclusions were obtained. 1. When the intercanine distance was maintained, the available space for the distal movement of the mandibular incisors after the extraction of the 4 1st bicuspids was larger than the space provided by the extraction of the 4 1st bicuspids. However the difference was less than 1mm. The more tapered the anterior arch form, the larger the difference. 2. Compared to the situation in which the intercanine distance was maintained, when the intercanine distance was expanded to meet the width of the posterior teeth, the incisors could move about 3mm more distally. 3. The positional difference of the incisal tip was insignificant whether the central incisors were moved by tipping or bodily movement. 4. When the anterior crowding was solved without changing the intercanine distance, the larger the anterior arch length was, the more the anterior movement of the incisors. 5. When the curve of Spee was levelled, the increase in the arch perimeter was less than half of the deepest curve of Spee.

A comparative study of wire and divider methods applied in orthodontic dental model measurement / 实用口腔医学杂志

Objective:To compare the difference between the measurement methods of wire and divider applied in the measurement of arch length at orthodontic dental model analysis.Methods:80 pairs of dental models were selected,including 40 normal occlusion models and 40 crowded models.The arch length of every model was measured by the wire and divider methods respectively,and the casual error and paired t test was subsequently employed to compare the difference between the measurements data.Results:The variance coefficients of the dental lengths measured by the divider method was larger than those measured by the wire method in both crowding and normal occlusion(P

A longitudinal study on the developmental changes of dental arch width and length / 대한치과교정학회지

Developmental changes of dental arch width and length from 6.6 to 13.6 years of age have been studied in twenty boys and thirteen girls in Korean school children. A series of 8 dental casts obtained from each child was measured in the intercanine width, intermolar width and arch length. Afterwards, mean value and each standard deviation of each age group and each gender were obtained, and corresponding graphs were drawn. The finding of this study can be summarized as follows : 1.Maxillary intercanine widths increased until age of 13.5 in males and age of 12.5 in females. On the other hand, mandibular intercanine widths increased until age of 11.5 in males and age of 9.6 in females and after there were on changes. 2. Maxillary intermolar widths increased until age of 13.5 but increments reduce from age of 12.5 in both sex. Mandibular intermolar widths increased until age of 13.5 in males and age of 12.5 in females. Annual increments of maxillary intermolar width greater than those of mandibular intercanine width in both sex. 3. Maxillary dental arch lengths increased until age of 10.6 in both sex, and after decreased until age of 13.6. Mandibular dental arch lengths increased until age of 10.5 in males and of 9.6 in females, and after decreased until age of 13.6. 4. Developmental changes of dental arch width and length showed individual variation.

Causative factors and predictability of arch length discrepancy / 대한치과교정학회지

The purpose of this study was to estimate relative importance among the causative factors of arch length discrepancy(ALD) and possibility of prediction of the ALD in the mixed dentition. The sample consisted of the casts of the 142 young adults who had no abnormal muscle function. no skeletal abnormalities and Class I molar relationship. We classified the sample by gender and the extent of ALD, and measured mesiodistal diameters of each tooth and the dimensions of the dental arch. The computerized statistical analyses was carried out with SPSS win program. The results were as follows ; 1. Most of the variables of spacing group, and some variables of dental arch dimension of crowding group were significantly different between genders. But in normal group, there were few differences. 2. In male crowding and female spacing group, mainly measurements of tooth dimension were significantly different from those of normal group. 3. In male spacing and female crowding group, measurements of dental arch dimension were significantly different from those of normal group. 4. The measurements of dimension of dental arch were highly correlated with ALD in correlation analysis and factor analysis. 5. Prediction equations for adult's ALDs by means of what can be measured in the mixed dentition(mesiodistal dimensions of incisors and first molar, intermolar width and arch length) showed R square from 63% to 80 %.

Dental Anthropologic Study on the High School Students of Che-ju island / 체질인류학회지

This dental anthropological study was performed to analyse male and female students of Che-ju high school students. Cephalometric X-rays and dental casts were obtained of 60 male and 60 female students and the Mean and Standard Deviation were obtained. There was no difference in craniofacial morphology between male and female students but the size of craniofacial skeleton of the male is bigger than that of the female. The distance from NB line to pogonion is longer in the male group, and it meant that mandibular symphysis of the male is well developed than the female. The size of teeth of the male is larger than that of the female and is significant in upper and lower canine and first molar. The size of upper arch width, intercanine width, basal arch width and lower basal arch width of the male is larger than that of the female, but arch length of the male and the female showed no significant difference.