Mandibular permanent first molar and incisor width as predictor of mandibular canine and premolar width

Prediction of excess cement residues using a regression model to avoid peri-implant diseases: An in vitro study

Dental implant restorations attached to cement can potentially result in peri-implant mucositis and peri-implantitis if cement residues are present. Effectively predicting and eliminating such dental cement residues is crucial for preventing complications. This study focuses on creating a regression model using the pixel values to predict the Excess Cement Residues (ECR) by employing an octagonal surface imaging approach. A model featuring gingival imitation, ten abutments, and ten crowns was created, and the cemented implants underwent thorough photographic and analytical assessment. The ECR was determined through two distinct approaches: the Computerized Planimetric Method (CPM) and the weighing method. Across ten implants in this in vitro study, ECR varied from 0.3 to 21 mg, with an average of 5.69 mg. The findings reveal a higher amount of ECR on the distal, mesiobuccal, and mesial sides. Utilizing Pearson's correlation, a coefficient value of r = 0.786 signifies a strong correlation between CPM and the weighing method. The regression model further aids in predicting ECR based on pixel values. The octagonal surface imaging approach not only vividly captures information about ECR in the implant cementation region but also emphasizes the feasibility of ImageJ as an effective tool for detecting ECR. The congruence between CPM and the weighing method results supports the application of the regression model for precise ECR prediction.

Comparison of the different methods of width estimation in unerupted canine and premolars

BACKGROUND

There are different methods for determining the required space for unerupted teeth. However, the accuracy of these techniques varies depending on ethnic differences. Therefore, the current study was performed to compare the accuracy of four methods for estimating the mesiodistal width of unerupted canines and premolars in a population of northern Iran.

METHODS

The present cross-sectional study was conducted on 50 pairs of dental casts of patients aged 12-24 years old. The mesiodistal width of the teeth was measured with a digital caliper by two observers (ICC < 0.9), and the mean value was recorded. The space required for eruption of canines and premolars was obtained by the Tanaka-Johnson formula and the Moyers tables and compared with the actual value by paired t test.

RESULTS

The Tanaka-Johnson formula had overestimation in the maxilla and mandible, which was statistically significant (p < 0.001). The values obtained from the Moyers tables in different confidence levels were not accurate. However, the 65% level for the mandible had almost no difference from the actual value (P = 0.996 and r2 = 0.503). Furthermore, linear regression was obtained based on the total mesiodistal width of the maxillary first molar and mandibular central incisor (maxilla: Yx= 0.613X + 2.23 and mandible: Ym= 0.618X + 1.6) and the total mesiodistal width of the mandibular first molar and maxillary central incisor in each jaw (maxilla: Yx = 0.424X + 5.021 and mandible: Ym = 0.447X + 3.631).

CONCLUSION

The Tanaka-Johnson method was overestimated in the population of northern Iran. The 85% and 75% confidence levels of the Moyers table have the best clinical results for the maxilla and mandible, respectively. Regression based on maxillary first molars and mandibular central incisors has better results.

Prediction of mesio-distal dimensions of the unerupted permanent canines and premolars using measurements of different groups of erupted teeth: retrospective cross-sectional analysis of digital records in Western Australians

PURPOSE

Recently, other combinations of teeth are claimed to be better predictors for size estimation of permanent canine and premolars. The present study aimed to determine which combinations of teeth presented an appropriate predictor in Western Australians using digital technology.

METHODS

A total of 500 (323 females, 177 males) participants meeting the inclusion criteria were randomly selected from private orthodontic clinics. Mesiodistal dimensions of selected teeth obtained from pre-orthodontic treatment digital records were analyzed using SPSS 20. Fifteen possible combinations of teeth were used to determine the best prediction capability.

RESULTS

Different combinations of teeth showed a higher correlation with the sum of permanent canine and premolars. In females, group 13 (Mandibular incisors and maxillary first molars) and in males, group 15 (mandibular incisors, maxillary central incisors, and first molars) and group 14 (mandibular incisors and first molars) showed a higher correlation in maxilla and mandible respectively. Linear regression equations were developed based on the best predictor for each arch and gender.

CONCLUSION

Permanent mandibular incisors may not be better predictors when used alone. Newly developed equations, based on different combinations of teeth, more accurately predicted the sum of mesiodistal dimensions of permanent canine and premolars in the Western Australian population.

Comparison of measured and predicted mesiodistal tooth-widths of 13-17 years old Kenyans: a descriptive cross-sectional study to develop a new prediction equation for use in the mixed dentition in a Kenyan population

BACKGROUND

The Tanaka and Johnson equation is commonly used in mixed dentition analysis. However, the analysis is based on  a Caucasian population making clinical decisions challenging when used in different ethnic groups. This study developed a prediction equation based on a Kenyan population.

DESIGN

A descriptive cross-sectional study done in 68 13-17 years old Kenyans of African descent in two boarding secondary schools. Alginate impressions were taken, study models obtained, and mesiodistal tooth-widths measured on upper and lower study models from the first molar to the contralateral first molar. Descriptive statistics, paired t-tests and independent t-tests were conducted and Pearson product-moment correlation coefficients calculated (p < 0.05).

RESULTS

The mean age was 13.78 years (SD ± 0.70), females were 59%. The mesiodistal tooth-widths of the permanent canines and premolars were different between males and females (p ˂ 0.1). The Tanaka and Johnston equation significantly under-estimated the mesiodistal tooth-widths of the permanent canines and premolars (p ˂ 0.05). The addition of lower first permanent molars to the permanent lower incisors provided higher correlation coefficients than the Tanaka Johnston equation.

CONCLUSIONS

A new equation that includes the permanent lower incisors and first permanent molars as predictor teeth seems to be more suitable for mixed dentition analysis for this Kenyan population. A larger study is needed to validate these findings.

The Importance of the Maxillary and Mandibular Incisors in Predicting the Canines and Premolars Crown Widths

Background

The purpose of the present study was to use the combined mesiodistal crown widths of the mandibular and maxillary incisors as predictors for the combined mesiodistal crown widths of mandibular and maxillary canines and premolars.

Materials and Methods

One hundred and twenty pairs of study models belong to 120 Iraqi adult subjects with normal dental and skeletal relations were included in the study. The crown widths of the mandibular and maxillary incisors, canines, and premolars were assessed at the maximum mesiodistal dimension on the dental casts using a digital electronic caliper with 0.01 mm sensitivity. The correlation between combined mesiodistal crown widths of the mandibular and the maxillary incisors and combined mesiodistal crown widths of mandibular and maxillary premolars and canines has been determined using Pearson's coefficient correlation test for each arch and gender. Using simple regression analysis, the equations predicting the widths of the mandibular and maxillary premolars and canines were established. The predicted and the actual mesiodistal crown width values have been compared with the use of a paired sample t-test.

Results

According to the findings of the present study, males had significantly wider teeth compared to females. Correlations between the measured parameters ranged from moderate to strong. A nonsignificant difference between actual and predicted mesiodistal crown widths was discovered.

Conclusions

With a high degree of accuracy, the combined mesiodistal widths of the maxillary and the mandibular incisors could be utilized for predicting the combined mesiodistal crown widths of the mandibular and maxillary canines and premolars.

Size estimation of unerupted canines and premolars using various independent variables: a systematic review

INTRODUCTION

Prediction of unerupted permanent teeth is an essential part of orthodontic diagnosis and treatment planning. This prediction is done by mixed dentition space analysis based on the estimation of mesiodistal dimensions of unerupted permanent canine and premolars from already erupted permanent teeth. Permanent mandibular incisors are most commonly used for prediction. Recent literature reveals that mandibular incisors are not accurate predictors and other independent variables have been introduced to make a more accurate and precise prediction. The objective of this paper was to evaluate the literature in light of a variety of independent variables and their predictive accuracy.

METHODS

Electronic databases such as MEDLINE, PubMed, Scopus, Embase, Web of Science, CINAHL Plus were searched to identify articles published until September 2021.

RESULTS

The search resulted in a total of 1098 articles, of which 24 papers met our inclusion criteria and were included in this review. Articles using permanent mandibular incisors only as a predictor were excluded during the eligibility assessment. The results show that various independent variables including mesiodistal and vestibulo-oral dimensions of permanent maxillary and mandibular incisors and molars, molar basal arch length, intermolar distance, maxillary and mandibular arch and gender have been used as predictors to more accurately determine mesiodistal width of unerupted canine and premolars in different populations.

CONCLUSION

Ethnic tooth size variations strongly emphasize the need to determine which independent variable gives a more accurate prediction of unerupted permanent teeth to develop a population-specific prediction model. This will play a significant role in managing space problems and developing malocclusions.

Predicting Canine and Premolar Mesiodistal Crown Diameters Using Regression Equations

OBJECTIVES

The current study aimed to predict the combined mesiodistal crown widths of maxillary and mandibular canines and premolars from the combined mesiodistal crown widths of maxillary and mandibular incisors and first molars.

MATERIALS AND METHODS

This retrospective study utilized 120 dental models from Iraqi Arab young adult subjects with normal dental relationships. The mesiodistal crown widths of all teeth (except the second molars) were measured at the level of contact points using digital electronic calipers. The relation between the sum mesiodistal crown widths of the maxillary and mandibular incisors and first molars and the combined mesiodistal crown widths of the maxillary and mandibular canines and premolars was assessed using Pearson's correlation coefficient test. Based on this relation, regression equations were developed to predict the sum widths of maxillary and mandibular canines and premolars; then, the predicted mesiodistal crown sum widths were compared with the actual one using a paired sample t-test.

RESULTS

Statistically, the predicted mesiodistal crown sum widths were nonsignificantly different from the actual ones.

CONCLUSIONS

The combined mesiodistal widths of maxillary and mandibular canines and premolars can be predicted successfully from the combined mesiodistal widths of the maxillary and mandibular incisors and first molars with a high degree of accuracy reaching to more than 86%.

Applicability of Different Mixed Dentition Analyses among Children Aged 11-13 Years in Chennai Population

Introduction

Mixed dentition is the stage where both primary and permanent teeth are present and hence is the time for developing occlusion. Mixed dentition analysis forms an essential part of an orthodontic assessment. Moyer's method which is commonly used for this analysis is based on data derived from a Caucasian population. Tanaka–Johnston developed prediction tables comparable with that of Moyer's from teeth measurement study models.

Aim

To test the reliability of Moyer's and Tanaka–Johnston's mixed dentition space analyses among children in Chennai.

Materials and methods

The mesiodistal measurements of the mandibular incisors, maxillary canines, and premolars were taken by measuring the greatest distance between the contact points on the proximal surfaces using a dental digital caliper set on dental casts of 1,000 children. Predicted values were obtained using Moyer's probability analysis at the 75th percentile and Tanaka–Johnston method. The statistical analysis for both sexes was done using Student's t test and unpaired t test.

Results

On application of the statistical analysis after the collection of data, it was found that the mean value in males was higher than the actual values in maxillary right and left sides when compared with the mandibular right and left sides while employing Moyer's method. The standard deviation (SD) was higher in the actual values when compared with the predicted values. Statistically significant values were obtained for the maxillary left side and the mandibular left side, but there was no statistical difference in the maxillary and mandibular right sides. Among females, it was found that the actual values had a higher mean value in the maxillary arch when compared with the mandibular arch than the values obtained when Moyer's formula was applied.

Conclusion

Both Moyer's and Tanaka–Johnson's mixed analyses when applied to children in Chennai tended to show that predicted values were higher than actual values with no significant differences observed among the regression equations.

How to cite this article

Ravinthar K, Gurunathan D. Applicability of Different Mixed Dentition Analyses among Children Aged 11–13 Years in Chennai Population. Int J Clin Pediatr Dent 2020;13(2):163–166.

Applicability of Tanaka Jhonston Method and Prediction of Mesiodistal Width of Canines and Premolars in Children

INTRODUCTION

Essential part of diagnostic procedures in mixed dentition analysis is to determine adequate space available for the erupting permanent teeth. Various methods of analysis for mixed dentition are available; among them Tanaka Johnston method of space analysis for children was developed for North American children and is widely used. Its reliability among different racial and ethnic groups is yet to be determined.

AIM

To check the applicability of Tanaka Jhonston method and to derive the mesiodistal width of unerupted canines and premolars and also derive new regression equations for Bangalore population.

MATERIALS AND METHODS

Considering the selection criteria, 400 subjects of Bangalore aged 13-16 years were randomly selected and study models were prepared. Mesiodistal widths of permanent lower incisors, canines and premolars were measured. Estimated width of upper, lower canines and premolars were also derived using Tanaka Jhonston method. Data was utilized to predict mesiodistal widths of erupting permanent canines and premolars. Descriptive analysis, independent student t-test, correlation and regression analysis were carried out.

RESULTS

Measured and estimated widths of upper and lower canines and premolars were compared and the results showed that estimated widths of upper and lower canines and premolars over estimated as to the actual measurements. A new regression equation was developed by using the formula Y=a+b(X) where Y= predicted width of canine and premolars, "a" and "b" are the constants and X= lower incisal width. Regression equations for males and females were derived separately.

CONCLUSION

The original Tanaka Jhonston method over estimated for local Bangalore population. New regression equations and prediction tables were derived for males and females separately, which should be more conveniently used chairside by the clinician.

New prediction equations for the estimation of maxillary mandibular canine and premolar widths from mandibular incisors and mandibular first permanent molar widths: A digital model study

OBJECTIVE

The primary aim of the study was to generate new prediction equations for the estimation of maxillary and mandibular canine and premolar widths based on mandibular incisors and first permanent molar widths.

METHODS

A total of 2,340 calculations (768 based on the sum of mandibular incisor and first permanent molar widths, and 1,572 based on the maxillary and mandibular canine and premolar widths) were performed, and a digital stereomicroscope was used to derive the the digital models and measurements. Mesiodistal widths of maxillary and mandibular teeth were measured via scanned digital models.

RESULTS

There was a strong positive correlation between the estimation of maxillary (r = 0.85994, r(2) = 0.7395) and mandibular (r = 0.8708, r(2) = 0.7582) canine and premolar widths. The intraclass correlation coefficients were statistically significant, and the coefficients were in the strong correlation range, with an average of 0.9. Linear regression analysis was used to establish prediction equations. Prediction equations were developed to estimate maxillary arches based on Y = 15.746 + 0.602 × sum of mandibular incisors and mandibular first permanent molar widths (sum of mandibular incisors [SMI] + molars), Y = 18.224 + 0.540 × (SMI + molars), and Y = 16.186 + 0.586 × (SMI + molars) for both genders, and to estimate mandibular arches the parameters used were Y = 16.391 + 0.564 × (SMI + molars), Y = 14.444 + 0.609 × (SMI + molars), and Y = 19.915 + 0.481 × (SMI + molars).

CONCLUSIONS

These formulas will be helpful for orthodontic diagnosis and clinical treatment planning during the mixed dentition stage.

Prediction of canine and premolar size using the widths of various permanent teeth combinations: A cross-sectional study

AIMS

To suggest the best predictor/s for determining the mesio-distal widths (MDWs) of canines (C) and premolars (Ps), and propose regression equation/s for hitherto unreported population.

METHODS

Impressions of maxillary and mandibular arches were made for 201 children (100 boys and 101 girls; age range: 11-15 years) who met the inclusion criteria and poured with dental stone. The maximum MDWs of all the permanent teeth were measured using digital vernier caliper. Thirty-three possible combinations (patterns) of permanent maxillary and mandibular first molars, central and lateral incisors were framed and correlated with MDWs of C and Ps using Pearson correlation test.

RESULTS

There were significant correlations between the considered patterns and MDWs of C and Ps, with difference noted between girls (range of r: 0.34-0.66) and boys (range of r: 0.28-0.77). Simple linear and multiple regression equations for boys, girls, and combined sample were determined to predict MDW of C and Ps in both the arches.

CONCLUSIONS

The accuracy of prediction improved considerably with the inclusion of as many teeth as possible in the regression equations. The newly proposed equations based on the erupted teeth may be considered clinically useful for space analysis in the considered population.

Validity of Moyers Mixed Dentition Analysis and a New Proposed Regression Equation as a Predictor of Width of Unerupted Canine and Premolars in Children

INTRODUCTION

The Moyer's mixed dentition analysis forms an essential part of diagnostic procedures to determine adequacy of the space available for the erupting permanent teeth. However, its reliability among different racial groups has been questioned.

OBJECTIVES

The objectives of this study were to test the reliability of Moyer's method and to produce new regression equation for Bangalore population for predicting the mesiodistal diameters of the unerupted permanent canines and premolars.

MATERIALS AND METHODS

Data was collected from study models of 400 randomly selected Bangalore subjects aged 13 to 16 years with fully erupted, intact dentitions and no significant malocclusion. The mesiodistal widths of the incisors, canines and premolars of both arches were measured. This data was then utilized to predict the mesiodistal widths of canines and premolars and further compared with Moyer's table.

CONCLUSION

It was found that 50% is more applicable to boys and 75% to girls. The canine premolar segment in both arches is statistically larger in men than in women (p<0.05). New regression equation was formulated, the accuracy of which needs to be evaluated further in a larger sample.

Effect of intermaxillary tooth-size discrepancy on accuracy of prediction equations for mixed dentition space analysis

AIM

Correlation-statistical methods are widely used for prediction of size of unerupted permanent canines and premolars in mixed dentition space analysis. The present study was planned to evaluate the effect of selecting dental study casts with no intermaxillary tooth-size discrepancy on the accuracy of predicting mesiodistal widths (MDWS) of permanent canines and premolars.

STUDY DESIGN

Bolton ratios were calculated for all the screened study dental casts fulfilling the inclusion criteria. Subjects were divided into two groups. Group A: all subjects with no intermaxillary tooth-size discrepancy within ±2 SD (Standard deviation) of the mean values. Group B: increased percentage of subjects with intermaxillary tooth-size discrepancy beyond ±2 SD (Standard deviation) of the mean values.

STATISTICS

Linear regression equations were established for both maxilla and mandible in both the groups, with different tooth combinations as independent variables. Validation of best possible regression equations was done on an independent set of 40 subjects. The actual and predicted values of MDWS of permanent canines and premolars were compared by paired samples t test in both groups, for both arches.

RESULTS

The accuracy of equations derived from group A was higher than those derived from group B. The difference between actual and predicted values was statistically insignificant in group A and statistically significant in group B.

CONCLUSION

The results confirm the accuracy of simple linear regression equations derived from a sample of children with no intermaxillary tooth-size discrepancy.

Evaluation of mixed dentition analyses in north Indian population: A comparative study

INTRODUCTION

Mixed dentition regression equations analyses (Moyers, Tanaka-Johnston) are based on European population, reliability of these methods is questionable over other population.

MATERIALS AND METHODS

The present study was conducted on total 260 study models. This study was done in two phases. In the first phase, linear regression equations were made. In the second phase, comparison of actual values of sum of mesiodistal width of canine, first and second premolars with the predicted values proposed by Moyers, Tanaka-Johnston, and the new proposed mixed dentition analysis for North Indian population were made.

RESULTS

Set of four linear regression equations for predicting sum of mesiodistal width of permanent canine, first premolar and second premolar in North Indian population from sum of mesiodistal width of mandibular incisors and mandibular first molars, were proposed as; (a) for males, maxillary arch, Y = 2.9 + 0.40X, (b) mandibular arch Y = 3.91 + 0.37X (c) for females, maxillary arch Y = 0.56 + 0.45X (d) mandibular arch Y = 1.14 + 0.42X. Moyers and Tanaka-Johnston, mixed dentition analysis, is found to be overestimating the mesiodistal width of unerupted canine and premolars in North Indian population.

Mandibular permanent first molars and incisors as predictors of mandibular permanent canine and premolar widths: applicability and consistency of the method

INTRODUCTION

Estimating the mesiodistal widths of the mandibular permanent canines and premolars is an essential aspect of mixed dentition analysis. A method is proposed to predict the sum of the mandibular permanent canine and premolar widths based on the sum of the mandibular permanent first molars and incisors. In this study, we aimed to test the applicability and reliability of this method in a population in Belo Horizonte, Minas Gerais, Brazil. The methods of Moyers and of Tanaka and Johnston were also tested.

METHODS

The sample consisted of 200 orthodontic study models, obtained from white Brazilian patients (123 female, 77 male). The mesiodistal widths of the teeth were measured with an analog caliper. Paired Student t tests with a significance level of 5% were used to compare the actual and predicted values.

RESULTS

No statistically significant differences were found between the predicted and actual values of the sum of the mandibular permanent canine and premolar widths when using the new method. The differences were 0.6 mm for the male sample, 0.5 mm for the female sample, and 0.6 mm for the total sample; the standard deviations were 1.9, 2.1, and 2.2 mm, respectively. However, overestimated predicted values with differences of 1.4 and 1.9 mm (male and female) in the Moyers method and 1.9 and 3.3 mm (male and female) in the Tanaka and Johnston method were found.

CONCLUSIONS

The new method is consistent and applicable to the population of Belo Horizonte. The other 2 methods tended to overestimate the actual values of the permanent canines and premolars.

A new proposed regression equation for mixed dentition analysis using the sum of permanent mandibular four incisors and first molar as a predictor of width of unerupted canine and premolars in a sample of North Indian population

OBJECTIVE

The objective of this study was to establish a new regression equation for North Indian and to compare and correlate the predicted width of unerupted canine and premolars obtained from the proposed regression equation of the present study in the North Indian population sample, Moyer's prediction table and also from Melgaco regression equation with the actual width; in order to check the applicability of various methods of mixed dentition analysis for the North Indian population.

MATERIALS AND METHODS

The sample consisted of 200 dental casts obtained from the North Indian patients and students which consists of 100 males and 100 females with the average age of 20.12 ± 4.70 years for males and 19.54 ± 3.16 years for females. Mesiodistal tooth widths of mandibular arch from permanent right first molar to left first molar were measured with an electronic digital caliper. Student t-test was used for comparison and Pearson's correlation coefficient was used to correlate the actual sum and the predicted width of the permanent mandibular canines and premolars obtained from various methods.

RESULTS

The difference between the actual and predicted width was statistically insignificant using the regression equation obtained for the North Indian sample population (correlation r = 0.78) in contrast to the significant difference with predicted width obtained from Melgaco equation (r = 0.61) and Moyer's prediction table (r = 0.42).

CONCLUSIONS

A new proposed regression equation for the North Indian population was established. Amongst the three regression equations devised, the proposed regression equation formulated in the present study; gave the most accurate results confirming racial variation in tooth size. This method is considered as an easy and practical way to predict the size of unerupted canines and premolars.

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.

Sagittal changes in lower incisors by the use of lingual arch

OBJECTIVE: The objective of this study was to evaluate a sagittal variation on the lower incisors with the use of the lingual arch on the transition from mixed to permanent dentition. METHODS: The sample was constituted of 44 Caucasian patients (26 girls and 18 boys), divided in two groups: CG, control group, monitoring the lower arch space with no orthodontic/orthopedic treatment during the rated period (n = 14); EG, experimental group, presenting anterior inferior mild crowding and installation of the lingual arch for space maintenance (n = 30). The position of the lower incisors was analyzed on computerized cephalometric tracings performed at the beginning of the monitoring (T1) and at the end, on the permanent dentition (T2). In order to evaluate the position of the incisors it was used Tweed and Steiner measurements: IMPA, 1.NB and 1-NB. The alterations were analyzed through the "t" test for paired samples, while the differences between the groups were analyzed through the "t" test for independent samples, as for sexual dimorphism. RESULTS: The values in T2 were greater in relation to T1 for all measurements on EG (IMPA, p = 0.038; 1.NB, p = 0.007 and 1-NB, p < 0.0001). On comparing the differences (T2-T1) between CG and EG, it can be gauged differences significantly superior for measure 1.NB (p = 0.002) and 1-NB (p < 0.0001) on EG. There was no statisticaly significant difference between genres. CONCLUSION: It was concluded that the lower incisors were projected after using the lingual arch to control the space on the transition from mixed to permanent dentition, however, within acceptable standards, not having difference between genres.

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.

How to predict the timing of eruption of mandibular second premolars

OBJECTIVE

To evaluate the relationship between the stages of dental formation and the timing of eruption of mandibular second premolars.

MATERIALS AND METHODS

The sample comprised panoramic radiographs of 25 children, 7 to 12 years old, observed by space supervision during development of dentition. The initial radiograph (T1) was taken in the mixed dentition period and the progress radiograph (T2) close to the eruption of mandibular second premolars. The stages of dental formation were determined by the proportion between crown length and total length (CL/TL) as well by the Simpson and Kunos index. Average values between right and left sides (35, 45) were correlated to the time elapsed until dental eruption (T2-T1). Statistical analysis was performed by Pearson correlation analysis.

RESULTS

The proportion CL/TL presented higher correlation index with time to eruption than the Simpson and Kunos index. The linear regression equation for prediction of timing of eruption showed high coefficient of determination, low deviation, and good accuracy. According to survival analysis, mean deviation at 95% confidence level was between 3.6 and 6.4 months. There was no difference in contralateral measurements, with high intraclass correlation coefficient for both CL/TL proportion and Simpson and Kunos index.

CONCLUSIONS

More advanced stages of dental formation indicate less time until dental eruption. The strong correlation with crown length/total length proportion (CL/TL) provides a linear regression equation for prediction of the timing of eruption of mandibular second premolars.

Reliability of permanent mandibular first molars and incisors widths as predictor for the width of permanent mandibular and maxillary canines and premolars

AIM

Preventive measures are necessary to prevent a potential irregularity from progressing into a more severe malocclusion. The determination of the tooth size-arch length discrepancy in mixed dentition requires an accurate prediction of the mesiodistal widths of the unerupted permanent teeth.

MATERIALS AND METHODS

For the study, 200 subjects in the age group of 16-25 years were selected from various colleges of M. M. University. The mesiodistal width of permanent mandibular incisors, first molars, canines and premolars of both arches were measured on the subject cast using an electronic digital caliper. Statistical analysis showed a significant difference between mesiodistal tooth widths of males and females. Linear regression equation was determined to predict the sum of mandibular and maxillary permanent canines and premolars using mandibular first molars plus the four mandibular incisors as predictors.

RESULTS

There was no significant difference between the actual and predicted width of sum of permanent canines and premolars using regression equations. The predicted widths of both arches using Tanaka and Johnston equations showed significant differences. Determined regression equations for males were accurate in male samples and determined regression equation for females were accurate in female samples for both arches.

Demonstration of a sex difference in the predictability of widths of unerupted permanent canines and premolars in a Japanese population

OBJECTIVES

(1) To identify any differences in the accuracy of the prediction of the summed widths of unerupted permanent canines and premolars for males vs females and, if differences are identified, (2) to examine the sex differences in the best combination of independent variables and (3) to evaluate the practical accuracy using our models for both sexes, respectively.

MATERIALS AND METHODS

Records for 200 orthodontic patients (100 males and 100 females) with discernible tooth crowding in the permanent dentition were selected. Mesiodistal tooth crown widths, dental arch widths, and basal arch lengths were measured. Predicted sum widths of permanent canines and premolars in both dental arches were calculated using stepwise regression analysis.

RESULTS

Among male subjects, the best combinations of independent variables were the widths of the upper central and lateral incisors (U1, U2) and the first molar (U6) for the maxilla (R(2) = 0.615) and the mandible, lower central and lateral incisors (L1, L2), and the first molar (L6) (R(2) = 0.685), whereas in females, the best combinations for prediction were found to be U1, U2, U6, and the maxillary arch width for the maxilla (R(2) = 0.429) and L1, L2, L6, and the basal arch length for the mandible (R(2) = 0.426). Correlation coefficients between each independent and dependent variable in the female subject group were found to be weaker than those for the male subject group.

CONCLUSIONS

We found the sex differences in the accuracy of prediction and the best combination of independent variables for predicting the summed widths of unerupted canines and premolars. These new models should be clinically useful, providing highly accurate prediction.

Análise de dentição mista: tomografia versus predição e medida radiográfica

OBJETIVO: o objetivo dos autores desse estudo foi comparar o método de análise de dentição mista que utiliza tomografia computadorizada de feixe cônico para avaliar os diâmetros dos dentes intraósseos com os métodos de Moyers, Tanaka-Johnston e radiografias oblíquas em 45º. MÉTODOS: foram realizadas medidas, na arcada inferior, dos diâmetros mesiodistais dos incisivos permanentes irrompidos, nos modelos de gesso com auxílio de paquímetro digital e estimativa do tamanho de pré-molares e caninos permanentes ainda não irrompidos utilizando-se a tabela de Moyers e a fórmula de predição de Tanaka-Johnston. Nas radiografias oblíquas em 45º, caninos e pré-molares foram medidos utilizando-se o mesmo instrumento. Nas tomografias, as mesmas unidades dentárias foram aferidas por meio de ferramentas do programa Dolphin. RESULTADOS: a análise estatística revelou elevada concordância entre o método tomográfico e o radiográfico, e baixa concordância entre o tomográfico e os demais avaliados. CONCLUSÃO: a tomografia computadorizada de feixe cônico mostrou-se confiável para análise da dentição mista e apresenta algumas vantagens em relação aos métodos comparados: a observação e mensuração dos dentes intraósseos individualmente, com a possibilidade, contudo, de visualizá-los sob diferentes perspectivas e sem superposição de estruturas anatômicas.