Applicability of the Moyers' Probability Tables in Adolescents with Different Facial Biotypes

Introduction:

The Moyers’ probability tables are used in mixed dentition analysis to estimate the extent of space required for the alignment of canines and premolars, by correlating the mesiodistal size of lower incisors with the size of permanent canines and premolars.

Objective:

This study intended to evaluate the applicability of the Moyer's probability tables for predicting the mesiodistal space needed for the correct location of premolars and permanent canines non-erupted, in adolescents of the city of Cordoba, Argentina, who show different facial biotypes.

Materials and Methods:

Models and tele-radiographies of 478 adolescents of both genders from 10 to 15 years of age were analyzed. The tele-radiographies were measured manually in order to determine the facial biotype. The models were scanned with a gauged scanner (HP 3670) and measured by using Image Pro Plus 4.5 software.

Results:

According to this study, the comparison between the Moyer´s probability table, and the table created at the National University of Córdoba (UNC) (at 95%, 75%, and 50%) shows that, in both tables, a higher value of mesiodistal width of lower incisors corresponds to a bigger difference in the space needed for permanent canines and premolars; being the need for space for permanents canines and premolars bigger in the UNC´s table. On the other hand, when contrasting the values of mesiodistal space for permanent canines and premolars associated with each facial biotype, the discrepancies between groups were not statistically significant (P >0.05). However, we found differences in the size of the space required according to the mesiodistal width range of the lower incisors for each biotype:

a) The comparison of lower-range values, with a mesialdistal width of lower incisors less than 22 mm, the space required for permanent canines and premolars resulted smaller in patients with dolichofacial biotype than in patients with mesofacial and braquifacial biotypes. The latter biotypes have meager differences between them.

b) The comparison of mid-range values, with a mesialdistal width of lower incisors from 22 to 25 millimeters, shows that the values of required alignment space are similar in the three facial biotypes.

c) Finally, the comparison of upper range values, with a mesialdistal width of lower incisors greater than 25 millimeters, indicates that the space required for dolichofacial biotypes tends to be higher than in mesofacial and brachyfacial biotypes.

Conclusion:

The Moyer´s probability tables should be created to meet the needs of the population under study, with no consideration of patients’ facial biotypes.

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.

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.

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.

Applicability of Two Universally Accepted Mixed Dentition Analysis on a Sample from Southeastern Region of Andhra Pradesh, India

BACKGROUND

Most of the universally accepted mixed dentition analyses are based on the data derived from northwestern European descent. However, the accuracy of these methods when applied to different ethnic population is questionable.

AIM

The present study is aimed to evaluate the applicability of Tanaka and Johnston (TJ) and Moyers (50(th) and 75(th) percentile) mixed dentition analysis in a sample from south-eastern region of Andhra Pradesh, India.

SUBJECTS AND METHODS

Study models were prepared from a sample of 100 patients (50 males and 50 females) in the age range of 13-15 years. The mesio-distal dimension of the teeth was measured using a Digital Vernier calipers. The actual values of permanent canine and premolars on the casts were compared with the predicted values from TJ and Moyers analysis. The values derived from this study were statistically analyzed using SPSS version 17.0 (IBM, Chicago, USA). Pearson's coefficients were used to evaluate the correlations between the groups of teeth.

RESULTS

Overestimated values were noticed in males and females of both arches with TJ equation; Males showed no significant difference at Moyers 50(th) percentile (50/100), in both the arches where as females showed higher values in mandibular arch and underestimated values in maxillary arch. At Moyers 75(th) percentile, overestimated values were noticed in males for both the arches whereas in females lesser values were observed.

CONCLUSION

As the values showed significant deviation from TJ and Moyers both at 50 and 75 percentile, its applicability to the present population is limited. So, new regression equations were derived.

Validity of moyers mixed dentition analysis for Saudi population

Objectives:

To evaluate the applicability of Moyers probability tables and to formulate more accurate mixed dentition prediction tables in the Saudi population.

Methods:

A cross-sectional study was conducted at the College of Dentistry, Kind Saud University, Saudi Arabia. The data were collected from 410 (203 males and 207 females) orthodontic study models, which had erupted mandibular permanent incisors, maxillary, mandibular canines and premolars. The mesiodistal widths were measured using a digital caliper with an accuracy of 0.01 mm. Student’s paired t-test was used to compare the mean width values derived from this study with the values derived using the Moyers table. Simple linear regression was used to evaluate the linear relationship between the combined mesiodistal widths of the mandibular permanent incisors and the canine-premolar segments in each dental arch.

Results:

The regression equations for the maxillary canine-premolar segment (males: Y=10.27+0.48X; females: Y=11.71 + 0.39X) and the mandibular canine-premolar segment (males: Y=9.71 + 0.40X; females: 11.28 + 0.39X) were used to formulate new probability tables on the Moyers pattern. Statistically significant differences were observed between predicted widths in our subjects and the widths obtained using Moyers tables.

Conclusions:

The new prediction tables derived in this study provided a more precise mixed dentition space analysis than Moyers prediction tables in estimating tooth dimensions in the Saudi population.

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.

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.