Corrected and Republished Applicability of Boston University approach for prediction of mesiodistal width of canines and premolars in the primary schoolchildren of rural Bengaluru An in vivo study

Introduction: Boston University (BU) approach is a method for early prediction of unerupted permanent mandibular teeth widths based on the mesiodistal widths (MDWs) of primary mandibular canines and first molars. The present study was conducted to test the validity of BU approach by comparing it with Tanaka–Johnston (T/J) approach in the contemporary population. Aims and Objective: The aim of the study was to determine the applicability of BU approach for prediction of the MDWs of canines and premolars in the primary schoolchildren of rural Bengaluru. Materials and Methods: The study was conducted in 100 healthy schoolchildren of rural Bengaluru aged between 7 and 11 years. The MDWs of canines and premolars were predicted using both T/J and the considered BU approaches for all the children and were compared. Results: The correlation coefficient showed a statistically significant correlation between the predicted tooth size from the two predicted methods in the upper and lower arches (P < 0.001), with Pearson's correlation coefficient showing the very strong positive relationship (r = 0.7). Significant differences were seen between the mean predicted width of canines and premolars by both the approaches (P < 0.001). Conclusion: In spite of the limitations, we recommend the use of BU approach to predict arch length-tooth material discrepancy at an early age and to get at least an approximate estimation of the required space. We also advocate the necessity of further research on this approach prospectively.

Applicability of Boston University approach for prediction of mesiodistal width of canines and premolars in the primary schoolchildren of rural Bengaluru An in vivo study

Introduction: Boston University (BU) approach is a method for early prediction of unerupted permanent mandibular teeth widths based on the mesiodistal widths (MDWs) of primary mandibular canines and first molars. The present study was conducted to test the validity of BU approach by comparing it with Tanaka–Johnston (T/J) approach in the contemporary population. Aims and Objective: The aim of the study was to determine the applicability of BU approach for prediction of the MDWs of canines and premolars in the primary schoolchildren of rural Bengaluru. Materials and Methods: The study was conducted in 100 healthy schoolchildren of rural Bengaluru aged between 7 and 11 years. The MDWs of canines and premolars were predicted using both T/J and the considered BU approaches for all the children and were compared. Results: The correlation coefficient showed a statistically significant correlation between the predicted tooth size from the two predicted methods in the upper and lower arches (P < 0.001), with Pearson's correlation coefficient showing the very strong positive relationship (r = 0.7). Significant differences were seen between the mean predicted width of canines and premolars by both the approaches (P < 0.001). Conclusion: In spite of the limitations, we recommend the use of BU approach to predict arch length-tooth material discrepancy at an early age and to get at least an approximate estimation of the required space. We also advocate the necessity of further research on this approach prospectively.

Scleral Dellen after Routine Uneventful Pterygium Surgery.

Occurrence of Scleral Dellen is rare but serious complication with stromalinflammation with tissue loss and scarring. Scleral dellen results from localdehydration & thinning of scleral tissues with exposure of underlying uvea leading toblueish colour. Occular surgical causes of occurrence of scleral dellen are strabismussurgery, pterygium excision (with or without use of adjunctive treatment like betaradiation, conjunctival autograft and Mitomycin C), cataract extraction.1,2 Patientscomplain of foreign body sensation & mild discomfort. Treatment consists ofreduction or elimination of contributing perilimbal elevation, & rapid rehydrationwith artificial tears, eye ointment and patching3. If treated properly dellen usuallyresolves completely without permanent sequelae. We report a case of severe scleraldellen that occurred 14 days after the uneventful surgical excision of primarypterygium without adjuvant therapy. We describe a patient with scleral dellen, whichoccurred after an uneventful pterygium excision without adjunctive therapy.

ViVan Ratio for Maxillomandibular Tooth Material Discrepancy.

According to the guidelines of the American and Indian Boards of Orthodontics, it is essential to include second molars, while managing an orthodontic case. Therefore, the present study was planned to determine maxilla-mandibular tooth material discrepancy.METHODSThe study sample consisted of study casts of 300 subjects in the age range of 18-30 years. Samples having a full complement of teeth with Angle’s Class I molar and canine relationships, good intercuspation, normal overjet and overbite and minimal crowding and spacing were included in the study. Tooth dimensions were measured using digital vernier caliper (accurate to 0.01 mm) and overall ratio was calculated. The data was statistically analysed for range, mean, standard deviation and coefficient of variation.RESULTSViVan ratio was found to be 90.79 with standard deviation of 3.13, variance of 9.81 and range was 83.55 - 95.82.CONCLUSIONSIdeal tooth proportions play an important role in achieving good occlusion at the end of orthodontic treatment. The ViVan ratio obtained in the study included second molars and this would benefit the orthodontist in proper treatment planning. This ratio will add importance for improved results at the finish of orthodontic treatment.

Comparison of Bolton s Ratio for Evaluation of Tooth Size Discrepancy between Maxillary and Mandibular Arches in Vidarbha Population

Bolton’s ratio is an indispensable parameter used in orthodontic diagnosis to evaluate the tooth size discrepancy. However, these norms have been established for Caucasian population and population variations necessitate the evaluation of these ratios for Vidarbha population. The objectives of the present study were to determine Bolton’s ratio for Vidarbha population, compare them with original Bolton’s ratios and determine the clinical significance of these differences.METHODSThe study sample consisted of study casts of 300 subjects in the age range of 18-30 years, all belonging to Vidarbha population, having a full complement of teeth. Tooth dimensions were measured using digital vernier caliper and Bolton’s overall ratio and anterior were calculated. The data calculated was statistically analysed for range, mean, standard deviation and coefficient of variation. Unpaired t-test was applied to draw a difference between the results of this study and the results from Bolton’s study.RESULTSBolton’s overall and anterior ratio norms for Vidarbha population sample were found to be 88.15 and 78.50, respectively, with standard deviation of 3.27 and 3.19, respectively. The range of overall ratio noted was 80.36–98.44, and the range of anterior ratio was 67.74–89.70.CONCLUSIONSIn general, the values obtained from this study for the Vidarbha population differ from the data of Caucasian population. So, it can be inferred that the established Bolton’s values for Caucasians cannot be used for the Vidarbha population. Hence, population specific standards are necessary for clinical assessment.

ViVan Formula- A Modified Formula for Estimating the Mesiodistal Width of Maxillary Central and Lateral Incisor

It is a frequent occurrence that teeth especially maxillary incisors are either completely avulsed or fractured due to trauma in facial region. Replacement of these missing teeth always possess a challenge if there are no prior dental records of the patient. Also, maxillary lateral incisors are frequently smaller in size – “Peg shaped” or congenitally absent. Aesthetic correction or/and replacement of this tooth also poses a problem when prior records are missing.METHODSTotally, 300 study casts were taken from the patients and digital vernier caliper was used to measure the mesiodistal width of maxillary central and lateral incisors and mandibular lateral incisors on both the sides. The mean and the standard deviations of the width was assessed. Similarly, the proportion between the widths of the maxillary lateral incisor and mandibular lateral incisor was also assessed and based on the proportions, the ViVan formula was derived.RESULTSBased on the proportions, ViVan Formula for Central Incisor and Lateral Incisor is derived.CONCLUSIONSViVan ratio determined the mesiodistal width of central and lateral incisor with the help of mandibular lateral incisor. This formula provides results accurately and with minimum error. One of the important diagnostic tools is the use of diagnostic model for estimation of tooth size. Tooth size must be proportionate to jaw size so as to avoid tooth size arch length discrepancy.

Prevalence of Median Diastema in a Sample of Iraqi Population Concerning on the Mesiodistal Width of Anterior Teeth and Frenal Attachment as Etiological Factors

Aim: The purpose of this study was to evaluate the prevalence of mid line diastema between the group of Iraqi students of Dentistry College in Baghdad University, and to determine the etiological factors of this diastema whether it is due to height frenal attachment or due to the discrepancy in the width of the anterior teeth as etiological factors or/and another cause and to determine the gender difference. Materials and methods: Out of 600 students aged between 18-23 years were clinically examined; only 41 students (30 females and 11 males) fulfilled the inclusion criteria and were having diastema. Maxillary median diastema and mesiodistal width of the sex upper anterior teeth was measured directly (intra orally) with stainless steel vernier calipers. Results: Results showed that about 30 females and 11 males were only having maxillary midline diastema from the total sample. There was no significant difference between males and females concerning the width of maxillary middiastem. In both sexes, the mesiodistal width of all anterior teeth was nearly equal except the maxillary left lateral incisors which were significantly wider in females than in males. Conclusion: In dentally aware societies the presence of diastema was un-aesthetic so many students improved such appearance by orthodontic treatment or restorative veneer, therefore Iraqi students had less prevalence of maxillary diastema than other studies. Females express more prevalence of maxillary midline diastema than male. Mesiodistal width of upper anterior teeth is nearly within the normal range of Iraqi norms. Another etiological factor such as hereditary, genetic or oral habit can be considered as a cause of diastema in our sample who have diastema without high frenal attachment or tooth width discrepancy.

Comparison of interpupillary distance and combined mesiodistal width of maxillary central incisor teeth in two ethnic groups of Northeast India: An in vivo study

Anthropometric measurements of the face can be used as a guide in selecting proper sized anterior teeth. Aim: The aim of this study is to evaluate the relationship between the interpupillary distance (IPD) and the combined mesiodistal width of maxillary central incisors (MDW of MCIs) to establish their morphometric criterion and their significance in two ethnic groups of Northeast India. Methodology: A total of 120 participants consisting of 60 indigenous students each from Assam and Meghalaya in the age group of 18–25 years were selected after taking their written consent. Standardized facial frontal photographs of all the participants were taken using a digital camera in such a manner that maxillary anterior teeth were visible. The photographs were uploaded onto the computer and saved in a file. Anthropometric measurements of IPD and combined MDW of MCIs in centimeters were made using both Adobe Photoshop® 7.0 software program and manually using a digital vernier caliper on the developed photographs to a same size of 15 cm × 10 cm. Data obtained were tabulated and analyzed using Student ”t”-test and Pearson correlation test. Results: The present study reveals a positive correlation with a high degree of statistical significance between IPD and combined mesiodistal width of maxillary central incisors among all the samples irrespective of gender and ethnicity where P < 0.01. Conclusion: IPD can be used as a guide in determining the suitable mesiodistal dimension of the maxillary central incisors.

Evaluación de la exactitud de métodos de Tanaka-Johnston y Moyers en pacientes chilenos del Postgrado de Ortodoncia UNAB Santiago, Chile

Objetivo: Determinar la exactitud del Índice de Tanaka-Johnston e Índice de Moyers mediante el análisis de modelos de estudio iniciales con dentición definitiva de pacientes chilenos del Postgrado de Ortodoncia de la Universidad Andrés Bello sede Santiago. Materiales y métodos: Se seleccionaron por conveniencia 100 pares de modelos según los criterios de inclusión y exclusión establecidos, correspondientes 50 al género femenino y 50 al masculino, y se realizó medición directa con un pie de metro manual, de la suma incisiva inferior y suma de segmentos canino-premolar. La medición fue realizada por dos examinadores previamente calibrados. Se determinó la exactitud de cada uno de los métodos y presencia de diferencias estadísticas significativas. Resultados: Para mujeres, Moyers 65% en maxilar superior y Moyers 50% en maxilar inferior presentan mayor exactitud en predicción de tamaño mesiodistal de caninos y premolares permanentes no erupcionados; en cambio, para hombres, Moyers 75% en maxilar superior y Moyers 65% en maxilar inferior son más exactos. El método de Tanaka-Johnston a pesar que solo presenta diferencias estadísticamente significativas en maxilar inferior en el género femenino (p<0,05), es menos exacto tendiendo a sobrestimar valores reales en mujeres, y a subestimar en hombres. Conclusión: Método de Moyers es más exacto en la predicción del espacio necesario en pacientes chilenos, su nivel de confianza varía según género y maxilar. Diferencias son explicadas por dimorfismo sexual y variaciones étnicas con respecto a la población de origen de métodos de predicción.

Objetive: Determine the accuracy of Tanaka-Johnston and Moyers indexes through the initial analysis of study models with permanent teeth of Chilean patients of the Graduate School Orthodontics of University Andres Bello in Santiago. Materials and Methods: 100 pairs of models were selected by convenience as the inclusion and exclusion criteria established, corresponding to 50 female and 50 male. Direct measurement was performed with a manual caliper gauge by two examiners previously calibrated. The sum of permanent mandibular incisors and sum of segments canine-premolar were measured. The accuracy of each of the present methods and statistical differences were determined. Results: In females, the prediction of width of unerupted canines and premolars is more accurate on maxilla with Moyers 65% and mandible with Moyers 50%. For males, Moyers 75% on maxilla and Moyers 65% in mandible are more accurate. Tanaka-Johnston method although only presented statistically significant differences in mandible of female gender (p <0.05), is less accurate tending to overestimate actual values in women as in men underestimated. Conclusion: Moyers method is more accurate in predicting space required in Chilean patients, the confidence level varies according to gender and jaw. Differences are explained by sexual dimorphism and ethnic variations from the source population of prediction methods.

Does the maxillary anterior ratio in Korean adults follow the Golden Proportion?

PURPOSE: The purpose of this study was to determine the effect of changes in the horizontal plane angle on the mesiodistal width ratios of the maxillary anterior teeth during the acquisition of frontal view photographs, derive these ratios for Korean adults on the basis of the data obtained, and analyze them using the Golden Proportion as a reference. MATERIALS AND METHODS: In experiment I, 30 plaster casts were mounted on an articulator and positioned on the angle-measuring device with a center setting of 0°. The device was rotated to 10° in 1° increments in a counterclockwise direction. At each angle, photographs were obtained and analyzed. Experiment II was based on 60 patients who visited the Department of Prosthodontics at Kyungpook National University Dental Hospital from February 2012 to February 2015. The patients were divided into three groups [Male (M), Female (F), Total (M + F)]. Frontal views were obtained for all groups and analyzed. RESULTS: From 1° to 10°, the relative mesiodistal width ratios for the maxillary anterior teeth showed no significant differences from those at 0°. In all three groups, the relative width ratio of the maxillary central incisor was smaller than that specified in the Golden Proportion; the opposite was true for the canine. CONCLUSION: Our results suggest that the mesiodistal width ratios of the maxillary anterior teeth do not follow the Golden Proportion in Korean adults, and that a change in the horizontal plane angle from 1° to 10° during frontal photography does not affect these ratios.

Relationship between mesiodistal width and enamel thickness in mandibular incisors / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to investigate the relationship between the enamel thickness of proximal surfaces and the morphologic features of mandibular incisors. METHODS: Mesiodistal/faciolingual (MD/FL) index, MD width, and height of contour width/cervical width ratio were measured in 40 incisors extracted from Koreans. For determining the height of contour width/cervical width ratio, the cervical width was measured as the distance between proximal cementoenamel junctions. Then, the labial surface was ground to the height of the contour level to measure enamel thickness. Pearson correlation analysis was used to investigate the correlation between enamel thickness and morphologic features. RESULTS: Enamel thickness was 0.75 +/- 0.07 mm per side, and MD width was 5.56 +/- 0.40 mm. Enamel thickness and MD width were significantly correlated. However, a significant relationship was not observed between enamel thickness and MD/FL index or the height of contour width/cervical width ratio. CONCLUSIONS: The results suggest that enamel thickness is affected only by MD width. Therefore, if the MD width is the same for mandibular incisors with a large MD/FL index or triangular shape and mandibular incisors with normal shape, then the limit of enamel reduction for reproximation will be the same.

Valoración de la ecuación de Tanaka-Johnston en estudiantes cubanos con oclusión normal / Assessment of Tanaka-Johnston equation in Cuban students presenting normal occlusion

El análisis de Tanaka-Johnston, mundialmente empleado para la predicción del espacio de caninos y premolares no brotados, ha sido muy cuestionado por la variabilidad en el tamaño dentario entre las diferentes poblaciones, y por haber sido realizado en un grupo étnico no aplicable a todos. Se realizó un estudio descriptivo transversal, con el objetivo de determinar el ancho mesiodistal de incisivos, caninos y premolares mandibulares, así como de caninos y premolares maxilares, y comparar la suma real de estos dientes con los estimados por Tanaka-Johnston, según el sexo y la arcada. El universo de esta investigación estuvo constituido por 50 estudiantes de la Facultad de Estomatología de La Habana, 25 del sexo femenino y 25 del sexo masculino, con oclusión normal, sin antecedentes de tratamiento ortodóncico; todos descendientes de cubanos. En los resultados se observó que los anchos mesiodistales de los incisivos, caninos y primeros premolares inferiores y de caninos y segundo premolar izquierdo superiores fueron significativamente mayores en el sexo masculino que en el femenino. La suma real de caninos y premolares superiores e inferiores fue mayor en el sexo masculino que en el femenino. Cuando se comparó la suma real de caninos y premolares, con lo estimado según la ecuación de Tanaka-Johnston, se halló que la esta sobrestimó los valores de caninos y premolares, ya que los resultados fueron significativamente menores(AU)

The Tanaka-Johnston analysis used at worldwide to predict the space of non-erupted canines and premolars has been questioned due to the variability in the teeth size among different populations and also to be carried out in non-applicable whole ethnic group. A cross-sectional and descriptive study was conducted to determine the mesiodistal width of mandibular incisives, canines and premolars, as well as of danines and premolar-maxillary and to compare the real sum of these theeth with the estimates by Tanaka-Johnston, according to sex and the arcade. Universe of this research included 50 students of Stomatology Faculty of havana (25 males and 25 females) presenting with normal occlusion, without a history of Orthodontics treatment all of them descendants of Cubans. In results it was noted that the mesiodistal widths of incisives, canines and first lower premolars and of canines and second left premolars upper are greater in male sex than in the female one. The real sum of upper and lower canines and premolars was greter in male sex than in the female one. Comparing the real sum of canines and premolars with that estimated according Tanaka-Johnston, it was noted that it overestimated the values of canines and premolar since the results were significantly lower(AU)

Anchos mesiodistales de dentición temporal en niños de la ciudad de Concepción, Chile y su correlación con el tamaño de coronas metálicas preformadas de stock / Mesiodistal width in temporary molars of Chilean children of Concepción and his correlation with standard preformed steel crowns

Las coronas metálicas preformadas son el tratamiento de elección al restaurar extensas caries en molares temporales. Para lograr un óptimo tratamiento es necesario conocer los anchos mesiodistales de las piezas involucradas en la terapia restauradora. En nuestro medio se utilizan los anchos mesiodistales de otras poblaciones, al conocer que pueden existir diferencias significativas con nuestra población en particular decidimos estudiar el ancho mesiodistal en nuestros pacientes. El propósito de esta investigación fue determinar anchos mesiodistales de molares temporales sanos en niños chilenos, analizando dimorfismo sexual, simetría intraarcada y con la pieza contralateral, así como la concordancia con los tamaños estandarizados de las coronas metálicas preformadas. Se realizó un estudio descriptivo odontométrico, seleccionando 34 niños (17 hombres y 17 mujeres) que asistían a la Clínica de Odontopediatría. Se procedió a medir anchos mesiodistales con un calibre ortodóncico en modelos de yeso obtenidos de cada paciente. Simultáneamente se midieron anchos mesiodistales de coronas metálicas preformadas. No se observan diferencias estadísticamente significativas entre los diámetros de piezas derechas e izquierdas ni entre géneros. Molares inferiores presentaron mayor ancho mesiodistal que los superiores. El promedio de ancho mesiodistal de molares temporales se corresponde de manera significativa con un solo tamaño de corona metálica preformada, salvo en las piezas 5.5 y 8.5 donde la correlación es con 2 tamaños de coronas metálicas.

Metallic preformed steel crowns are the best treatment choice to restaurate extense cavities in temporary molars. To achieve optimal results it is necessary to know the mesiodistal width of the temporary teeth involved. We currently use other population’s data regarding mesiodistal width, and since we believe there could be significant variations in between populations we decided to study mesiodistal width in our patients. The purpose of this investigation was to determine mesiodistal widths of healthy temporary molars in Chilean children.Sexual dimorphism, interarch symmetry and with the contralateral tooth, and comparison with the standard preformed steel crown were analyzed. This is a descriptive odonthometric study. 34 children (17 male, 17 female) assisting to the Pediatric Clinic were selected. Mesiodistal widths were assessed with an orthodontic caliper on a plaster model obtained from each patient. Simultaneously, preformed steel crown mesiodistal widths were measured. Results and conclusions: There were no statistically significant differences between right and left teeth’s mesiodistal width, nor between genders. The mean mesiodistal width of temporary molars corresponds with only one size of preformed steel crown, except on 5.5 and 8.5. In these teeth the width corresponds with two sizes of the preformed steel crown.

Validación de la ecuación de Tanaka-Johnston en una población de escolares yemenita / Validation of Tanaka-Johnston equation in Yemeni schoolboys

El anàlisis del espacio requiere una comparación entre el espacio disponible y el espacio necesario para la alineación de los dientes. El ampliamente usado análisis del espacio de Tanaka-Johnston es cuestionado cuando es aplicado a diferentes poblaciones. Por tanto el propósito de este estudio fue determinar el ancho mesiodistal de incisivos, caninos y premolares mandibulares y caninos y premolares maxilares, para validar el anàlisis de Tanaka-Johnston según el sexo en 100 estudiantes yemenitas comprendidos entre las edades de 12 a 16 años. Se encontró diferencias estadísticamente significativas en el ancho mesiodistal de caninos y premolares según el sexo, excepto para el segundo premolar maxilar. La ecuación de Tanaka-Johnston sobreestima el ancho mesiodistal de los segmentos bucales en esta población(AU)

In space-analysis it is necessary a comparison between the available space and the necessary space in teeth alignement. The well-used Tanaka-Jhonston space analysis is questioned when it is applied in different populations; thus, the aim of present study was to determine the mesiodistal width of mandibular incisives, canines and premolar and of maxillary canines and premolar to validate the Tanaka-Johnston analysis according to sex in 100 Yemeni students aged from 12 to 16. There were statistically significant differences in mesiodistal width of canines and premolars according sex, except for the second maxillary premolar. The Tanaka-Johnston equation overrates the mesiodistal width of oral segments in this population(AU)

An evaluation of the adequacy of PONT's index / 대한치과교정학회지

Dental arch expansion in one of the method used to solve the dental crowding problem by non-extraction. Many formulae using tooth size have been suggested to predict ideal inter-premolar and inter-molar width. The purpose of this study was to evaluate the adequacy of some of some upper dental arch width prediction methods, namely Pont's method, Schmuth's method and Cha's method. The sample consisted of the casts of 119 Korean young adults who had no muscular abnormality, no skeletal discrepancy, and Angle's Class I molar relationships. Measurements were obtained directly form plaster casts; they included mesiodistal crown diameters of the four maxillary incisors, as well as maxillary inter-first-premolar and inter-first-molar arch widths as specified by Pont. The correlation coefficients between the sum of incisors(SI) and upper dental arch width were calculated. The differences between predicted width and actual width wee classified as overestimated, properestimated, and underestimated. The data obtained from each group were analyzed for statistical differences. The results were as follows : 1. Upper dental arch width indices were calculated from SI in normal occlusion (81.96 : premolar index, 62.55 : molar index). 2. Low correlations between SI and arch width were noted in normal occlusion (0.50 in the inter-premolar width, 0.39 in the inter-molar width). 3. Pont's formula and Schmuth's formula tended to overestimate the inter-premolar. A more even distribution of estimates was noted in Cha's formula. 4. Cases within 1mm range of observed inter-premolar width were 45% in the Pont's formula, and 39% in the Schmuth's formula. 5. All formulae had a tendency to underestimate the inter-molar width, but Cha's formula had better predictability than others. 6. Cases within 1mm range of observed inter-molar width were 40% in the Cha's formula, 29% in the Pont's formula, and 13% of Schmuth's formula. The data presented in this study dose not support the clinical usefulness of ideal arch width prediction methods using the mesiodistal width of maxillary incisors.

A study of dental crowding and its relationship to mandibular incisor shape by model analysis in adolescents / 대한치과교정학회지

Mandibular incisor crowding is one of the most common features of malocclusion and is interesting characteristic in view of relapse and stability after orthodontic treatment. There are many potential factors in the etiology of lower anterior crowding. The tooth size variation is one of them, but biologic significance for the faciolingual width of the teeth has been overlooked. Peck and Peck reported that persons with ideal mandibular incisor alignment were shown to have incisor with smaller mesiodistal and larger faciolingual dimensions than persons with incisor crowding. On the basis of these findings they suggested MD/FL index as a clinical guideline for the assessment for lower incisor crowding. The present study was undertaken to examine the relationship between mandibular incisor crowding and mandibular incisor dimension, and determine their correlation with arch length discrepancy. 154 dental casts of people from 11 to 17 years of age were made, and were divided into normal group with irregularity index less than of 1, and crowding group with irregularity index greater than 1. The casts were measured and analyzed statistically. The results were as follows. 1. The mean mesiodistal width for mandibular incisor was larger in crowding group, and has significant difference in central incisor measurement. There are no significant differences in the faciolingul width and MD/FL index. 2. Irregularity index has significant correlation coefficients with mesiodistal width and MD/FL index for mandibular incisor in crowding group, but no correlation with faciolingual width. It also has correlation with maxillary and mandibular arch length discrepancy, total tooth material, mandibular intercanine width, and mandibular inter first premolar width. 3. Upper and lower arch length discrepancy have significant correlation with mesiodistal width of mandibular incisor and overbite, but have no correlation with faciolingual width. Lower arch length discrepancy has significant correlation with MD/FL index for mandibular incisor and upper arch length discrepancy has correlation with MD/FL index for mandibular lateral incisor. 4. Significant differences were observed between normal and crowding group for the mandibular arch length discrepancy and overbite.