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Introduction: The treatment of Class I malocclusion aims to arrange teeth position in a good arch form. The arch form consists of tooth size and arch dimension (intercanine width, canine depth, intermolar width, molar depth). Numerous methods have been used to describe the arch form quantitatively. The aim of this study was to develop a mathematical ratio for identifying arch form (square, oval, tapered) using arch dimension variables (intercanine width, canine depth, intermolar width, molar depth). Materials and Methods: Dental cast pre and post-orthodontic treatments from 190 Indonesian patients were scanned to obtain digital data. All data were measured using “Image Tool.” The measured data (tooth size, intercanine width, intercanine depth, intermolar width, intermolar depth, and arch perimeter) were analyzed statistically using ordered logistic to find out determining variables to the arch form. Results: The validity, reliability, and normality of all the data were analyzed using Stata. From analyzing the data using ordered logistic, intercanine width and intermolar depth showed a reverse relation to the arch form. The shape of the arch form (square, oval, and tapered) can be described quantitatively by using ratio (CD/CW)/(MD/MW); a ratio less than 45.30% indicates square, 45.30–53.37% indicates oval, and more than 53.37% indicates tapered. Conclusions: (CD/CW)/(MD/MW) ratio can be used to describe arch form quantitatively.

Introduction: The objective of this study was to gather information about normal occlusion and arch dimensions in the primary teeth of the children belonging to an Iranian population. Methods: This descriptive cross-sectional study was performed on 68 children from the city of Mashhad in the 3-5 age range. Dental arch dimensions, interrelationships of primary canine and second molars, overbite and overjet were evaluated. Results: Primate space was observed on both sides of the arch in 82.2% of the subjects. The most prevalent type of primary molar relationship was flush terminal plane (52.1%) followed by distal step (31.3%) and then mesial step (16.7%). The primary canine relationship was ranked in the descending order of prevalence as Class I (77.1%), Class II (13.5%), end-to-end (5.2%) and Class III (4.2%). Normal overbite and normal overjet was observed in 50% and 81.3% of cases, respectively. Conclusion: This study provides an insight into the dental arch dimensions, occlusion, spacing and crowding in primary dentition in Iranian children. In most of the cases, primate space and flush terminal plane were observed.

Introduction : A well-balanced face has its good proportions in all three dimensions of space, i.e. transverse, sagittal and vertical. The vertical proportions of the face are important in determining the esthetics and harmony of the face. The objectives of this study were to evaluate the relationship between dental arch dimensions and the vertical facial pattern determined by the Jarabak ratio, and to examine the differences in dental arch dimensions between male and female untreated adults. Materials and methods: Lateral cephalograms and study models were obtained from 90 untreated subjects (45 males, 45 females) between 17 and 24 years of age with no crossbite, no/minimal crowding and spacing. The Jarabak ratio (posterior facial height/anterior facial height) was measured on cephalograms of each patient. Study models were used to obtain comprehensive dental measurements, including maxillary and mandibular cumulative mesiodistal width, intercanine, first interpremolar and first intermolar widths as well as arch perimeter, arch length, overbite, palatal height and curve of Spee. Results: The results showed that, for both males and females, there was a trend that as vertical facial height increased, arch width, arch perimeter and overbite decreased but palatal height and curve of Spee increased and males have significantly larger arch dimensions than those of females. Conclusion: It was concluded that dental arch dimensions were associated with facial vertical morphology and gender. Thus, using individualized archwires according to each patient′s pretreatment arch form and width is suggested during orthodontic treatment.

Esta pesquisa teve como objetivo geral avaliar a discrepância de tamanho dentário, na oclusão normal e nos diferentes tipos de más oclusões e a sua relação com as medidas que determinam a forma de arco e o posicionamento dentário na região anterior. Para tanto, foram estudados 185 pares de modelos de gesso, divididos em 4 grupos: Grupo 1 (composto por 41 pares com Oclusão Normal, sendo 20 do gênero masculino e 21 do gênero feminino); Grupo 2 (composto por 44 pares com má oclusão de Classe I, divisão 1, sendo 22 do gênero masculino e 22 do gênero feminino); Grupo 3 (composto por 54 pares com má oclusão de Classe II, sendo 28 do gênero masculino e 26 do gênero feminino) e Grupo 4 (composto por 46 pares com Classe III, sendo 23 do gênero masculino e 23 do gênero feminino). Observou-se que não ocorreu dimorfismo sexual entre as discrepâncias de tamanho dentário e os diferentes tipos de oclusão dentária; as proporções estabelecidas por Bolton não se aplicaram ao grupo com Oclusão Normal; na Oclusão Normal, Classe I, Classe II e Classe III, houve um predomínio de excesso dentário total (RAZ12) no arco inferior; na Classe I houve uma igualdade na distribuição de excesso dentário anterior (RAZ6) nos arcos superior e inferior; na Oclusão Normal, Classe II e Classe III, ocorreu um predomínio de excesso dentário anterior (RAZ6) no arco inferior, em relação ao arco superior; os excessos dentários não contribuíram na ocorrência das más oclusões e as discrepâncias total e anterior (RAZ12 e RAZ6) não interferiram diretamente nas larguras e comprimentos dos arcos, bem como no posicionamento dos dentes anteriores.The general purpose of this study was to evaluate tooth size discrepancy in normal occlusion and in different malocclusion types and its relationship to measurements which determine arch form and anterior tooth positioning. One hundred and eighty five sets of casts of leucoderms were divided into four groups: Group 1 (consisted of 41 pairs of models with Normal Occlusion, 20 males and 21 females); Group 2 (consisted of 44 pairs of models with Class I malocclusion, 22 males and 22 females); Group 3 (consisted of 54 pairs of models with Class II, div. 1, malocclusion, 28 males and 26 females) and Group 4 (consisted of 46 pairs of models with Class III malocclusion, 23 males and 23 females). No sexual dimorphism was observed between tooth size discrepancies and different types of dental occlusion; the proportions stated by Bolton were not applied to the Normal Occlusion group; in Normal Occlusion, Class I, Class II and Class III there was an overall ratio excess in the lower arch; in Class I there was an equal anterior excess distribution in upper and lower arches; in Normal Occlusion, Class II and Class III there was a prevalent incidence of anterior ratio excess in lower arch; upper arch excess did not contribute to malocclusion occurrence and overall and anterior discrepancies did not interfere with arch width and length, as well as with anterior tooth positioning.

OBJECTIVE : The purpose of this study was to assess the arch dimensions in primary dentition of 3-5 years old children in Chennai and Hyderabad. As no primary to the mixed dentition and determining the existence of sexual dimorphism. METHODS : Children were selected fro various schools of both Chennai and Hyderabad, with complte set of primary dentition. Study casts were made and measurements of arch dimensions were made using digital sliding calipers. The data obtained was subjected to statistical analysis. RESULTS : The mean values and standard deviations of the various arch dimensions are given in the tables. CONCLUSION : Generally boys exhibited a greater arch dimensions than girls in both groups. Some of the dimensions showed a statistically significant mean values.