Aplicabilidad del método Tanaka-Johnston para la estimación del diámetro mesiodistal de caninos y premolares en pacientes de 12-18 Años / Applicability of the Tanaka-Johnston method for the estimation of the mesiodistal diameter of canines and premolars in patients of 12-18 years old

El método Tanaka-Johnston es utilizado mundialmente para predecir el diámetro de caninos y premolares no erupcionados por la conveniencia de no necesitar tablas ni radiografías para su uso. Sin embargo, durante los últimos años investigadores de varios países han demostrado que al ser utilizado en una población diferente para la que fue diseñado, puede sobrestimar o subestimar los valores. En Cuba, donde el patrón facial de la población difiere del ideal para este método, ha sido muy empleado, pero prácticamente no existen estudios donde se valide la confiabilidad o exactitud de las predicciones de este. Por tanto, el objetivo de esta investigación es determinar la aplicabilidad del método Tanaka-Johnston para la estimación del diámetro mesiodistal de caninos y premolares en pacientes de 12-18 años. Se desarrolló un estudio descriptivo y transversal desde junio de 2019 hasta enero de 2020 con una población de 140 pacientes de ambos sexos de entre 12 y 18 años de Cuba. Se efectuaron las mediciones de los anchos mesiodistales de los incisivos inferiores, todos los caninos y premolares. Se realizaron distribuciones de frecuencia a las variables estudiadas y los resultados se presentaron en tablas estadísticas. Para comprobar la existencia de diferencias significativas se utilizó la prueba estadística t-Student. Los resultados principales obtenidos fueron que el método Tanaka-Johnston tiende a sobrestimar los valores para el sexo femenino y subestimarlos para el masculino, ambos entre los 0,2 y 0,3 mm, pero esta diferencia no resulta significativa. Se concluye que el método Tanaka-Johnston puede ser aplicado en la población estudiada para la predicción del ancho mesiodistal de caninos y premolares no erupcionados.

The Tanaka-Johnston method is used worldwide to predict the diameter of canines and premolars not erupted for the convenience of not needing boards or x-rays for use. However, in recent years researchers from several countries have shown that when used in a different population for which it was designed, it can overestimate or underestimate the values. In Cuba, where the facial pattern of the population differs from the ideal for this method, it has been highly used, but there are very few studies where the reliability or accuracy of the predictions of the same is validated. Therefore, the objective of this research is to determine the applicability of the Tanaka-Johnston method for estimating the mesiodistal diameter of canines and premolars in patients aged 12-18 years. A descriptive and cross-cutting study was conducted from June 2019 to January 2020 with a population of 140 patients of both sexes between 12 and 18 years of age from Cuba. Measurements were made of the mesiodistal widths of the lower incisors, all canines, and premolars. Frequency distributions were made to the variables studied and the results were presented in statistical tables. The t-Student statistical test was used to verify significant differences. The main results obtained were that the Tanaka-Johnston method tends to overestimate the values for the female sex and underestimate them for the male, both between 0,2 and 0,3 mm, but this difference is not significant. It is concluded that the Tanaka-Johnston method can be applied in the population studied for the prediction of the mesiodistal width of unerupted canines and premolars.

Incisor size analysis to predict mesiodistal diameter in unerupted canine and premolar crowns in native and non-native Chilean population / Análisis del tamaño de incisivos para predecir el diámetro mesiodistal de coronas de caninos y premolares no erupcionados en población chilena nativa y no nativa

SUMMARY: The principal orthodontic problems observed in the mixed dentition phase are related to arch length and tooth size discrepancy. In order to identify such space discrepancies different methods of mixed dentition space analyses have been introduced. For this reason the purpose of this study is to generate a new regressive equation to predict the diameter of cuspid and bicuspid teeth through mesiodistal widths of lower incisors in a Chilean population sample between native and non-native population. The study was conducted at the Araucania Dental Clinic in Temuco, and the sample comprised of historical dental casts from 200 school children (93 boys and 107 girls) from Temuco, Chile, between 13-16 years of age. The native Mapuche population consisted of 107 students and the non-native of 93 students. Measurements of the mesiodistal widths of mandibular incisors, maxillary and mandibular canines and premolars were carried out with the help of Vernier gauge calipers calibrated to 0.01 of a millimeter. The results show that there are differences in the mesiodistal diameter size of incisors, and canines and premolars in the two studied groups. There is a low correlation of the variables studied. In conclusion, significant sexual dimorphism in tooth sizes exists in the native sample, and there is no difference in non-native population. It is necessary to develop a predictive formula that is greater than 70 % of accuracy for clinical application. Resonance imaging (MRI).

RESUMEN: El principal problema ortodóncico observado en la etapa de dentición mixta está relacionado con la longitud del arco y la discrepancia del tamaño de los dientes. En orden a identificar tal discrepancia de espacio, diferentes métodos de análisis de espacio en dentición mixta han sido introducidos. Por esta razón el objetivo de este estudio fue generar una nueva ecuación regresiva para predecir el diámetro mesiodistal de caninos y premolares a partir del ancho de los incisivos centrales inferiores en una muestra de población chilena nativa y no nativa. El estudio fue realizado en la Clínica de Ortodoncia Araucanía en Temuco. La muestra fue seleccionada de una colección histórica de modelos dentales, 200 escolares (93 niños y 107 niñas) de la ciudad de Temuco, Chile con edades entre 13 y16 años. La población nativa fueron 107 estudiantes Mapuches y los no nativos fueron 93 estudiantes. Las mediciones del ancho mesiodistal de los incisivos mandibulares, caninos maxilares and mandibulares y premolares fueron realizadas con la ayuda de un medidor Vernier calibrado a 0.01 de milímetro. Los resultados muestran que hay diferencias en el diámetro mesiodistal de incisivos, y caninos y premolares en los grupos estudiados. Hay una baja correlación de las variables estudiadas. En conclusión, hay diferencias significativas en el tamaño de dientes entre hombres y mujeres en la muestra de nativos, y no hay diferencias en la población no nativa. Es necesario desarrollar una fórmula predictiva que sea mayor a 70 % de seguridad para aplicaciones clínicas.

[Unerupted first deciduous molar located higher to the first premolar: a case report].

Tooth eruption is defined as the movement of a tooth from its site of development within the alveolar process to its functional position in the oral cavity. The process of tooth eruption can be divided into different phases: pre-eruptive bone stage, alveolar bone stage, mucosal stage, preocclusal stage, occlusal stage and maturation stage. Any disturbance in these phases can lead to eruptive anomalies. The incidence of unerupted teeth is usually higher among permanent teeth than among deciduous ones. Of the primary teeth reported as unerupted, second deciduous molars are the teeth most frequently involved, followed by primary central incisors. At present almost no coverage is seen about the impaction of the first deciduous molar. In this case, a 4-year-old boy who presented with an impacted left maxillary first deciduous molar came to the Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology. This tooth, located higher to the left maxillary first premolar, was well near to the maxillary sinus. The family and medical histories were noncontributory and his physical findings were within normal limits. The mother was reported as having experienced no illness or other complications and taken no medications during pregnancy. His clinical extraoral examination was noncontributory. His clinical intra-oral examination revealed that the maxillary left first primary molar was not present. No enlargement of the area was apparent visually or on palpation. The remaining primary dentition was well aligned and in good condition. His oral hygiene was good, although there were incipient occlusal carious lesions in the mandibular second primary molars. There was no history or evidence of dental trauma. A diagnosis of a left maxillary first deciduous molar was made on the basis of the clinical and radiographic evidence. Numerous local etiologic factors have been described for impacted teeth. These include anomalous teeth, malposition, fusion with adjacent or supernumerary teeth, odontoma, dentigerous cysts, tumors, underdevelopment of the jaws, keratinized epithelial lining, hereditary conditions, and trauma. In this case, the reason for impaction was not clear. After the comprehensive clinical evaluation, treatment consisted of placement of a space maintainer, the periodic examination was indicated for the follow-up, so that early interventions, such as subsequent surgical intervention and orthodontic traction could be recommended timely to manage orofacial disfigurement and to avoid consequent problems with resultant proper functioning and good periodontal health.

Accuracy and evaluation of a new regression equation in predicting the width of unerupted permanent canines and premolar teeth.

AIM: To assess the applicability of two regression equations based on mixed dentition analysis and to propose and evaluate a new regression equation using the mandibular incisors and first permanent molars as predictors in calculating the size of unerupted permanent canines and premolar teeth in school children. METHODS: Dental study casts of 100 children (50 males and 50 females) aged 11-14 years from schools situated in Moradabad, Uttar Pradesh, India were used. The analysis of Tanaka Johnston, Bernabe Flores-Mir and the proposed equation were tested on the casts. RESULTS: The analysis of Tanaka Johnston and Bernabe Flores-Mir tended to overestimate the mesio-distal width of the canines and premolars. The proposed equation also overestimated but the mean difference showed a closer approximation with the actual measured values compared to the other two equations. CONCLUSION: Validating studies with a similar population must be conducted to confirm the applicability and precision of the proposed equation.

Complicação pós-cirúrgica por extração de dente incluso: abscesso retrofaríngeo ­ relato de caso / Postoperative complications due to inclusive tooth extraction: retropharyngeal abscess ­ case report

A extração do terceiro molar é um procedimento comum dentro da área cirúrgica da odontologia e, como todo procedimento dessa natureza, está sujeito a intercorrências e complicações como hemorragias, trismo e infecções. Os abscessos de origem odontogênica são casos comumente encontrados nos atendimentos de urgências odontológicas e quando bem tratados geralmente evoluem com melhora do quadro, porém essa infecção pode evoluir com disseminação para espaços faciais e cervicais, acarretando piora do quadro e podendo levar o paciente a óbito. O objetivo desse relato é descrever um caso clínico de abscesso retrofaríngeo, por origem de foco odontogênico, ressaltando suas particularidades e a importância do diagnóstico precoce para controle e resolução do caso. Conclui-se que é importante uma rápida intervenção e acompanhamento multidisciplinar em um serviço de referência estruturado e capaz de fazer evoluir o caso com suporte e segurança (AU).

Third molar extractions are frequent procedures within the surgical area of dentistry and, like any procedure of this nature, these extractions are susceptible to intercurrences and complications such as hemorrhages, trismus and infections. Abscesses of odontogenic origin are common in dental emergency services. When well treated, they usually evolve with improvement of the condition, but these infections can also evolve with dissemination to facial and cervical spaces, leading to condition worsening and even death. The objective of this report is to describe a clinical case of a retropharyngeal abscess of odontogenic origin, highlighting its particularities and the importance of early diagnosis for the control and resolution of the case. It was concluded that a rapid intervention and multidisciplinary follow-up is important in a structured reference service capable of evolving the case with support and security (AU).

Crown shape of maxillary molars with delayed eruption.

The purpose of this study was to explore the crown shapes of maxillary molars with delayed eruption (DEMo1) at the position distal to the maxillary second premolar. Included teeth erupted later than the average for the maxillary first molar eruption in Japanese females (6.58 ± 0.67 years) by more than two standard deviations. Crown shapes of 12 four-cusped left DEMo1 teeth were compared with those of 25 four-cusped left maxillary first molars (U6n) and 25 four-cusped left maxillary second molars (U7n) from different patients with normal eruption. Seven landmarks were established on the reference plane containing the mesiobuccal, distobuccal and mesiolingual cusp tips of the molars; the origin was defined as the center of gravity of these three points. According to the obtained discriminant function (percentage of correct classifications, 84%), five DEMo1 teeth were classified as U6n and the other seven as U7n. The DEMo1 teeth were also classified into two subgroups, the U6n-close and U7n-close groups, according to the location of the distolingual cusp tip. These results suggest that DEMo1 teeth could include U6 and U7 with delayed eruption or could be an intermediate between U6 and U7, according to their crown shapes.

MIXED DENTITION SPACE ANALYSIS OF A SOUTHERN ITALIAN POPULATION: NEW REGRESSION EQUATIONS FOR UNERUPTED TEETH.

Mixed dentition analysis forms a critical aspect of early orthodontic treatment. In fact an accurate space analysis is one of the important criteria in determining whether the treatment plan may involve serial extraction, guidance of eruption, space maintenance, space regaining or just periodic observation of the patients. The aim of the present study was to calculate linear regression equations in mixed dentition space analysis, measuring 230 dental casts mesiodistal tooth widths, obtained from southern Italian patients (118 females, 112 males, mean age 15±3 years). Student’s t-test or Wilcoxon test for independent and paired samples were used to determine right/left side and male/female differences. On the basis of the sum of the mesiodistal diameters of the 4 mandibular incisors as predictors for the sum of the widths of the canines and premolars in the mandibular mixed dentition, a new linear regression equation was found: y = 0.613x+7.294 (r= 0.701) for both genders in a southern Italian population. To better estimate the size of leeway space, a new regression equation was found to calculate the mesiodistal size of the second premolar using the sum of the four mandibular incisors, canine and first premolar as a predictor. The equation is y = 0.241x+1.224 (r= 0.732). In conclusion, new regression equations were derived for a southern Italian population.

Predicting the size of unerupted canines and premolars using primary maxillary first molar.

AIM: One of the most important aspects of interceptive orthodontic diagnosis and treatment planning is space analysis. To date all methods use the size of permanent teeth to predict the dimensions of unerupted teeth. The aim of this study was to predict the permanent teeth size using maxillary primary first molar. METHODS: The size of primary maxillary first molars and permanent canines and premolars of 80 subjects was measured on their dental casts. Regression equations were determined between the size of primary maxillary first molars and permanent canines and premolars. RESULTS: The new regression equations for predicting permanent tooth size in the maxilla and mandible were, respectively, Y = 2.2X + 13 and Y = 2.4X + 9.5 among females and Y = 2.7X + 5.5 and Y = 2.4X + 9.5 among males. CONCLUSIONS: The results show that the primary maxillary first molar size can be used to predict the size of unerupted permanent teeth.

Prediction of unerupted canines and premolars in a Syrian sample.

BACKGROUND: The current study aimed to evaluate the applicability of the methods of Moyers and of Tanaka and Johnston to estimate the mesiodistal widths of permanent canines and premolars in Syrian individuals, to determine whether the predicting equations differ by sex, and to develop more accurate regression equations using various teeth groups as predictors. METHODS: A total of 670 pretreatment pairs of casts belonging to 342 female patients and 328 male patients were selected from the archives of orthodontic clinics in Damascus University and Al-Baath University. All relevant teeth were measured to the nearest 0.01 mm. Paired t tests were used to test the applicability of the Moyers method and the Tanaka and Johnson equation on Syrian individuals. New regression equations were constructed. RESULTS: The predicted values of permanent canines and premolars derived from Moyers' charts at the 50th percentile levels tended to underestimate the actual values for the male subjects but were comparable to the actual values for the female subjects. However, the predicted values derived at the 75th percentile levels tended to be comparable to the actual values for the male subjects and to overestimate the actual values for the female subjects. The predicted values calculated by Tanaka and Johnston's equations tended to overestimate the actual values in both study groups. CONCLUSIONS: The Moyers method was more accurate for the mixed dentition analysis for Syrian individuals. However, the proper percentile level is determined by sex. The use of the equations constructed using the Syrian sample is advised.

Applicability of Moyers analysis in mixed dentition: A systematic review.

INTRODUCTION: Moyers analysis is widely used for analyzing mixed dentition, however, the accuracy of its theoretical probability tables has been recently questioned. Taking into consideration the fact the mixed dentition analysis is of paramount importance to precisely determine the space needed for alignment of canines and premolars, this research aimed at objectively assessing in the literature such an important step for orthodontic diagnosis. METHODS: A computerized search involving articles published on PubMed and Lilacs between 1990 and September, 2011 was conducted in accordance with the method described in the Cochrane 5.1.0 handbook. RESULTS: The research resulted in a sample composed of 629 articles. The inclusion criteria were: Articles using the Moyers analysis with a sample greater or equal to 40 patients. Conversely, the exclusion criteria were: Dental casts of patients with syndromes or oral cleft, researches conducted with a literature review, only, or clinical case reports and researches conducted before 1990. For this systematic review, 19 articles were selected. CONCLUSIONS: Based on the literature available, we can conclude that Moyers mixed dentition analysis must be carefully used, since the majority of the articles analyzed showed that the probability of 75% was not as accurate as expected, leading to the need of adapting the probability levels depending on the study population.

Applicability of Moyers analysis in mixed dentition: A systematic review

INTRODUCTION: Moyers analysis is widely used for analyzing mixed dentition, however, the accuracy of its theoretical probability tables has been recently questioned. Taking into consideration the fact the mixed dentition analysis is of paramount importance to precisely determine the space needed for alignment of canines and premolars, this research aimed at objectively assessing in the literature such an important step for orthodontic diagnosis. METHODS: A computerized search involving articles published on PubMed and Lilacs between 1990 and September, 2011 was conducted in accordance with the method described in the Cochrane 5.1.0 handbook. RESULTS: The research resulted in a sample composed of 629 articles. The inclusion criteria were: Articles using the Moyers analysis with a sample greater or equal to 40 patients. Conversely, the exclusion criteria were: Dental casts of patients with syndromes or oral cleft, researches conducted with a literature review, only, or clinical case reports and researches conducted before 1990. For this systematic review, 19 articles were selected. CONCLUSION: Based on the literature available, we can conclude that the Moyers mixed dentition analysis must be carefully used, since the majority of the articles analyzed showed that the probability of 75% was not as accurate as expected, leading to the need of adapting the probability levels depending on the study population.

INTRODUÇÃO: a análise de Moyers é amplamente adotada para a análise da dentição mista, porém, recentemente, a acurácia das suas tabelas de probabilidade está sendo questionada. OBJETIVO: sabendo-se da importância da análise da dentição mista, na determinação mais precisa possível do espaço necessário para o alinhamento de caninos e pré-molares, o objetivo dessa pesquisa foi avaliar de forma objetiva na literatura este importante passo do diagnóstico ortodôntico. MÉTODOS: foi realizado um levantamento computadorizado de artigos publicados entre os anos de 1990 a setembro de 2011 nas bases de dados PubMed e LILACS, segundo o método descrito no manual Cochrane 5.1.0. RESULTADOS: a estratégia de busca resultou em 629 artigos. Para ser selecionado, o artigo deveria utilizar a análise de Moyers e ter uma amostra superior ou igual a 40 pacientes. Os critérios de exclusão foram: modelos de gesso de pacientes com algum tipo de síndrome ou fissurados, pesquisas cuja proposta era apenas uma revisão da literatura ou apenas relato de um caso clínico, e pesquisas anteriores ao ano de 1990. Para essa revisão sistemática, 19 artigos foram selecionados. CONCLUSÕES: com base na literatura disponível, pode-se concluir que a utilização da análise de Moyers na análise da dentição mista deve ser utilizada de maneira cautelosa, pois, na maioria dos artigos avaliados, 75% não apresentou a acurácia desejada, necessitando de adaptações nos níveis de probabilidade, dependendo da população em estudo.

Prediction of the mesiodistal size of unerupted canines and premolars for a group of Romanian children: a comparative study.

OBJECTIVES: The aim of the present study was to develop an optimization method of multiple linear regression equation (MLRE), using a genetic algorithm to determine a set of coefficients that minimize the prediction error for the sum of permanent premolars and canine dimensions in a group of young people from a central area of Romania represented by a city called Sibiu. MATERIAL AND METHODS: To test the proposed method, we used a multiple linear regression equation derived from the estimation method proposed by Mojers, to which we adjusted regression coefficients using the Breeder genetic algorithm. A total of 92 children were selected with complete permanent teeth with no clinically visible dental caries, proximal restorations or orthodontic treatment. A hard dental stone was made for each of these models, which was then measured with a digital caliper. The Dahlberg analyses of variance had been performed to determine the error of method, then the Correlation t Test was applied, and finally the MLRE equations were obtained using the version 16 for Windows of the SPSS program. RESULTS: The correlation coefficient of MLRE was between 51-67% and the significance level was set at α=0.05. Comparing predictions provided by the new and respectively old method, we can conclude that the Breeder genetic algorithm is capable of providing the best values for parameters of multiple linear regression equations, and thus our equations are optimized for the best performance. CONCLUSION: The prediction error rates of the optimized equations using the Breeder genetic algorithm are smaller than those provided by the multiple linear regression equations proposed in the recent study.

Prediction of the mesiodistal size of unerupted canines and premolars for a group of Romanian children: a comparative study

Objectives The aim of the present study was to develop an optimization method of multiple linear regression equation (MLRE), using a genetic algorithm to determine a set of coefficients that minimize the prediction error for the sum of permanent premolars and canine dimensions in a group of young people from a central area of Romania represented by a city called Sibiu. Material and Methods To test the proposed method, we used a multiple linear regression equation derived from the estimation method proposed by Mojers, to which we adjusted regression coefficients using the Breeder genetic algorithm. A total of 92 children were selected with complete permanent teeth with no clinically visible dental caries, proximal restorations or orthodontic treatment. A hard dental stone was made for each of these models, which was then measured with a digital calliper. The Dahlberg analyses of variance had been performed to determine the error of method, then the Correlation t Test was applied, and finally the MLRE equations were obtained using the version 16 for Windows of the SPSS program. Results The correlation coefficient of MLRE was between 51-67% and the significance level was set at α=0.05. Comparing predictions provided by the new and respectively old method, we can conclude that the Breeder genetic algorithm is capable of providing the best values for parameters of multiple linear regression equations, and thus our equations are optimized for the best performance. Conclusion The prediction error rates of the optimized equations using the Breeder genetic algorithm are smaller than those provided by the multiple linear regression equations proposed in the recent study. .

New regression equations for mixed dentition space analysis in an Iranian population.

AIMS: Prediction of the mesiodistal crown width of unerupted canines and premolars is an important aspect of mixed dentition analysis. The accuracy of Tanaka-Johnston equations, the most commonly method, is questionable when it is applied to different ethnic groups. In this study, we aimed to develop a new regression equation for this prediction in an Iranian population. MATERIALS AND METHODS: The dental casts of 120 Iranian subjects with complete permanent dentition were selected. Mesiodistal crown widths of teeth were measured with digital caliper. In the first part of the study, the correlation and linear regression equations between four mandibular incisors and the canine-premolars segments of both arches were developed (modified Tanaka-Johnston equation). In the second part, as a new method, correlation and linear regression equations were developed between the sum of mandibular central incisors-maxillary first molars and the canine-premolars segments. RESULTS: It was found that the correlation coefficients between the sum of mandibular central incisors-maxillary first molars and the maxillary and mandibular canine-premolars segments were higher (r = 0.66, 0.68 respectively) than the one between the four mandibular incisors and the canine-premolars segments (r = 0.58. 0.64). CONCLUSION: New linear regression equations were derived. In this study, the sum of mandibular central incisors and maxillary first molars was better predictor for unerupted canines and premolars. This novel approach allows the prediction of width of unerupted canines and premolars to take place at earlier age. CLINICAL SIGNIFICANCE: Using the new method, orthodontists could take advantage of mixed dentition analysis at earlier age. Moreover, to test the derived equations on a larger sample size and in other ethnicities is highly recommended.

Prediction of width of un-erupted incisors, canines and premolars in a Ugandan population: a cross sectional study.

BACKGROUND: Accurate prediction of the space forms an important part of an orthodontic assessment in the mixed dentition. However the most commonly used methods of space analysis are based on data developed on Caucasian populations. In order to provide more accurate local data we set out to develop a formula for predicting the widths of un-erupted canines and premolars for a Ugandan population and to compare the predicted widths of the teeth from this formula with those obtained from Moyers' tables, and Tanaka and Johnston's equations. METHODS: Dental casts were prepared using mandibular and maxillary arch impressions of 220 children (85 boys/135 girls) aged 12-17 years recruited from schools in Kampala, Uganda. The mesio-distal width of the mandibular incisors, mandibular and maxillary canines and premolars were measured with a pair of digital calipers. Based on regression analysis, predictive equations were derived and the findings were compared with those presented in Moyers' probability tables, and Tanaka and Johnston's equations. RESULTS: There were no statistically significant differences between the tooth widths predicted by our equations and those from Moyers' probability tables at the 65th and 75th percentile probabilities for the girls and at 75th level in boys in the mandibular arch. While in the maxillary arch no statistically significant differences at the 75th and 95th levels were noted in girls. There were statistically significant differences between predicted tooth sizes using equations from the present study and those predicted from the Tanaka and Johnston regression equations. CONCLUSIONS: In this Ugandan population, Moyers' probability tables could be used to predict tooth widths at specific percentile probabilities, but generally, Tanaka and Johnston technique tends to overestimate the tooth widths.

Applicability of two methods of mixed dentition analysis in a contemporary Indian population sample.

AIM: More than 10 years experience in implementing the Tanaka Johnston and Moyers methods has shown that they overestimate the sizes of unerupted canines and premolars when used in populations other than the Caucasian. This study was designed to assess the applicability of the two most commonly used methods of mixed dentition analysis and to attempt to derive a more accurate and precise formula to predict the sizes of the unerupted premolars and canines in a sample of Indian population. MATERIALS AND METHODS: The sample included 200 study models (100 male, 100 female). Tanaka Johnston's and Moyer's equations were applied to this sample and the mean differences between the actual and estimated tooth widths were determined. New regression equations were derived using lower first molars and incisors as the predictors. RESULTS: The mean difference between the actual and estimated values of canines and premolars using Tanaka Johnston's and Moyers methods were clinically and statistically significant. Therefore new regression equations were derived taking lower first molars and incisors as the predictors for both sexes. On validation, these equations were found to be accurate and precise for this population. CONCLUSION: It is recommended to use these equations as a method of mixed dentition analysis for the Indian population.

Design and implementation of a hybrid genetic algorithm and artificial neural network system for predicting the sizes of unerupted canines and premolars.

The aim of this study was to develop a novel hybrid genetic algorithm and artificial neural network (GA-ANN) system for predicting the sizes of unerupted canines and premolars during the mixed dentition period. This study was performed on 106 untreated subjects (52 girls, 54 boys, aged 13-15 years). Data were obtained from dental cast measurements. A hybrid GA-ANN algorithm was developed to find the best reference teeth and the most accurate mapping function. Based on a regression analysis, the strongest correlation was observed between the sum of the mesiodistal widths of the mandibular canines and premolars and the mesiodistal widths of the mandibular first molars and incisors (r = 0.697). In the maxilla, the highest correlation was observed between the sum of the mesiodistal widths of the canines and premolars and the mesiodistal widths of the mandibular first molars and maxillary central incisors (0.742). The hybrid GA-ANN algorithm selected the mandibular first molars and incisors and the maxillary central incisors as the reference teeth for predicting the sum of the mesiodistal widths of the canines and premolars. The prediction error rates and maximum rates of over/underestimation using the hybrid GA-ANN algorithm were smaller than those using linear regression analyses.

Mixed dentition space analysis for a northern Italian population: new regression equations for unerupted teeth.

OBJECTIVE: The aim of this study was to determine linear regression equations for a Northern Italian population to predict mandibular permanent premolars and canines widths, and particularly, second premolar widths, using the sum of the widths of the four mandibular incisors, canines and first premolars. MATERIALS AND METHODS: Mesiodistal tooth widths were measured from 230 dental casts obtained from Northern Italian patients (130 females and 100 males). Student's t-test or Wilcoxon test for independent and paired samples were used to determine right/left side and male/female differences. Correlation coefficients and linear regression equations were constructed to evaluate the relationship between 1) the combined mesiodistal widths of the permanent mandibular incisors (independent variable) and the combined mesiodistal widths of the canine and premolars (dependent variable); 2) the combined mesiodistal widths of the incisors, canines and first premolars (independent variable) and the widths of the second premolars (dependent variable). Significance value was set a priori at 0.05. RESULTS: A linear regression equation was found, y=0.585x+7.927 (r=0.734) considering right and left sides of mandibular arch together, to predict canines and premolars widths. For second premolar width, the linear regression equation was y=0.201x+2.149 (r=0.641), even when considering the right and left sides of the mandibular arch together. CONCLUSIONS: New regression equations were derived for a Northern Italian population.

A digital method to predict the mesiodistal widths of canines and premolars in an Egyptian sample.

OBJECTIVE: Treatment planning in the mixed dentition is important for proper tooth alignment. A mixed dentition analysis, should accurately predict the mesiodistal widths of unerupted permanent teeth. The aim of the present study was to determine which sum of mesiodistal widths (MDW) of permanent teeth will be the best predictor for MDW of unerupted permanent canines and premolars. STUDY DESIGN: The study was conducted on 102 Egyptians, 51 males and 51 females, mean age 16.7 +/- 0.5 years with fully erupted permanent teeth, and intact proximal surfaces. Dental casts were obtained and scanned to produce digital images that were used on a specially designed software program to measure the MDW of permanent teeth. Casts were divided into training and validation sets, where 9 models of tooth combinations were used to develop a regression equation that describes the relation between them and sum of MDW of erupted maxillary or mandibular canines, first and second premolars. The validation set was used to test the accuracy of the proposed equation. RESULTS: R2 of regression models ranged from 0.3 (for models #2, 4, 5 and 8) to 0.36for model #1. The highest regression in model #1 (sum of MDW of lower first permanent molars and upper central incisors) indicated a high linear association between the sum of MDW of tooth combination model #1 and the MDWofmaxillary and mandibular permanent canines and premolars. There was no significant difference between the actual and the predicted MDW when the proposed equation was checked for its accuracy in the entire validation set (p > 0.05). CONCLUSION: The combination of the sums of lower permanent first molars and upper permanent central incisors was the best predictor for the MD W of both maxillary and mandibular permanent canines and premolars. The newly proposed prediction equation may be considered clinically useful for mixed dentition analysis in Egyptian subjects.

The validity and reliability of mixed-dentition analysis methods: a systematic review.

BACKGROUND: The authors conducted a literature review to determine the validity and reliability of mixed-dentition analysis (MDA) methods used to predict permanent tooth size in the mixed dentition and to evaluate the effect of relevant variables. TYPES OF STUDIES REVIEWED: The authors searched eight online databases for studies of MDA. They selected 39 articles. Inclusion criteria included assessment of mesiodistal tooth width predictions of canines and premolars, use of study-model measurements with or without radiographs, reliability and validity of MDA values and a minimum sample size of 10. RESULTS: All MDA methods had positively correlated validity and high intrarater reliability. Mean differences were less than 2 millimeters with correlation coefficients that tended to be above 0.6. Correlation coefficients were less variable with multiple linear regression equations (MLREs) than with simple linear regression equations (SLREs) with the study-model method, but the opposite was true with the radiographic method. Polymorphisms based on ethnicity, sex, jaw or side of mouth did not meaningfully influence the validity of SLRE predictions, but some differences were apparent with the use of MLRE predictions. CLINICAL IMPLICATIONS: The results of this review call into question the clinical implications of the multiple variations of MDA that have been described in the literature.