Comparison of two nonradiographic methods of predicting permanent tooth size in the mixed dentition

Mixed Dentition Analysis in and around Kanpur City: An Existential and Illustrative Study

Context

Mixed dentition space analysis helps in determining the discrepancy between the available and required space in each dental arch during the mixed dentition period; further, it helps to diagnose and plan the treatment of developing malocclusion.

Aim

The aim of this study is to evaluate the applicability of Tanaka and Johnston's and Moyer's methods of predicting the size of permanent canines and premolars and compare the tooth size between the right and left sides between males and females, and also to compare the predicted values of mesiodistal widths of permanent canines and premolars from Tanaka and Johnston and Moyer's method with the measured values.

Materials and methods

The sample consisted of 58 sets of study models, of which 20 were girls and 38 were boys, that were collected from the children of the 12-15 year age-group. A digital vernier gauge, whose beaks were sharpened, was used to measure the mesiodistal widths of the individual teeth in order to increase accuracy.

Statistical analysis

The two-tailed paired t-tests were used to assess the bilateral symmetry of the mesiodistal diameter of all measured individual teeth.

Results and conclusion

It was concluded that Tanaka and Johnston's method could not accurately predict the mesiodistal widths of unerupted canines and premolars of children of Kanpur city due to the high variability in estimation, whereas the least statistically significant difference was obtained only at 65% level of Moyer's probability chart for male, female, and combined sample.

How to cite this article

Gaur S, Singh N, Singh R, et al. Mixed Dentition Analysis in and around Kanpur City: An Existential and Illustrative Study. Int J Clin Pediatr Dent 2022;15(5):603-609.

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.

Applicability of two non-radiographic tooth size prediction methods of unerupted permanent canine and premolars, for Galle district, Sri Lanka

Introduction:

Mixed dentition space analysis necessitates accurate prediction of size of the unerupted permanent teeth. The methods commonly employed are the radiographs, correlation and regression equations, or a combination. Much interest was developed on the application of prediction tables and regression equations to avoid the radiation exposure. However, the predicted values and equations have been reported to be inaccurate on populations other than on which they were developed on. We intended to evaluate the applicability of the Moyer’s probability table and Tanaka Johnston equation in estimating the mesiodistal widths of mandibular and maxillary permanent canines and premolars in adolescents of the Galle District.

Material and Methods:

Data were collected from study models of 318 randomly selected school students aged 13– 16 years with fully erupted, intact dentitions and no significant malocclusion. The measurements were obtained by a digital caliper with a Vernier scale calibrated to the nearest 0.01 mm. The data were subjected to statistical analysis to compare the actual and predicted values from Moyer’s probability table and Tanaka Johnston equation.

Results:

There was a statistically significant difference when Pearson correlation two-tailed significance test was used. The actual mesiodistal width of permanent canines and premolars and predicted widths from Moyer’s probability chart at all levels for males and females showed a statistically significant difference at 0.01 level. The values from Tanaka Johnston equation also showed a statistically significant difference at P = 0.01/R = 0.47.

Conclusion:

Moyer’s prediction table and Tanaka Johnston equation must be carefully used for children in Galle District, Sri Lanka. Therefore, it might be safer to develop regression equations for our population.

New regression equations for mixed dentition space analysis in Nepalese mongoloids

BACKGROUND

Mixed dentition space analysis methods using regression equations, namely, Moyers' analysis and Tanaka-Johnston analysis are commonly used around the world. However, the applicability of these analyses among different racial groups have been questioned. The primary objective of this study was to assess the applicability of the Moyers' and Tanaka-Johnston analyses among Nepalese Mongoloids and to develop regression equations for the same population if needed.

METHODS

One hundred (50 males and 50 females) pre-treatment study models of the Nepalese Mongoloid patients undergoing orthodontic treatment were retrieved from the archives of the department of Orthodontics. The mesiodistal widths of mandibular incisors and widths of canines and premolars of all 4 quadrants were measured by a single investigator using a digital caliper to the nearest 0.01 mm. Predicted widths of canines and premolars were obtained using standard Moyers' and Tanaka-Johnston analyses and then compared with the measured widths.

RESULTS

The measured widths of canines and premolars were significantly different from the predicted widths obtained from Moyers' and Tanaka-Johnston analyses. Strong and positive correlations were found between the sum of mesiodistal widths of mandibular incisors and the sum of mesiodistal widths of canines and premolars in males (0.73 for maxillary arch and 0.68 for mandibular arch) and females (0.64 for maxillary arch and 0.79 for mandibular arch).

CONCLUSIONS

The Moyers' and Tanaka-Johnston analyses did not accurately predict the mesiodistal width of unerupted canines and premolars for Nepalese Mongoloid population. Hence, new regression equations have been developed for this population. However, validation studies should be conducted to confirm the applicability and accuracy of these equations.

Mixed dentition space analysis among Nepalese Brahmins/Chhetris

BACKGROUND

Mixed dentition space analysis forms an important part of orthodontic diagnosis and treatment planning. Regression equations are widely used for mixed dentition analysis which can vary among races. This study aimed to find out the new regression equation in estimating the size of unerupted canines and premolars for Nepalese Brahmins/Chhetris.

METHODS

Hundred Nepalese Brahmins/Chhetris (50 males and 50 females) who met our criteria were selected among the patients attending to the Orthodontic Out-Patient Department, Institute of Medicine, Kathmandu. The mesiodistal widths of all mandibular permanent incisors; maxillary and mandibular canines and premolars were measured and analyzed. The results were also compared with predicted values from the Moyers and the Tanaka and Johnston methods. Correlation and linear regression analyses were performed between the predicted and actual tooth sizes for Nepalese Brahmins/Chhetris and standard regression equations were developed.

RESULTS

No significant differences were observed when the sum of canine and premolars of one quadrant is compared between sides and sex. Significant and high positive correlations were found between the mandibular incisors and the combined mesiodistal widths of the canines and premolars for the maxillary (r = 0.72) and mandibular (r = 0.73) segments. Significant differences were observed between the measured values from this study and from Moyers (50 % and 75 % probability) and Tanaka-Johnston methods.

CONCLUSIONS

The equations and charts commonly used for North American children (50(th) or 75(th) percentile) did not accurately predict for our sample, so new regression equations and tables were developed for Nepalese Brahmins/Chhetris children.

Primary Dentition Analysis: Exploring a Hidden Approach

Background: Accurate prediction of the mesiodistal widths (MDWs) of canines and premolars in children with primary dentition facilitates interception of malocclusion at an early age. Boston University (BU) approach is one, i.e., based on primary teeth for predicting canine and premolar dimensions.

Aim: To predict the canine and premolar dimensions, in the contemporary population, using BU approach and compare with the values obtained using Tanaka-Johnston (T/J) approach.

Design: Children in the age range of 7-11 years with presence of all permanent mandibular incisors and primary maxillary and mandibular canines and first molars were included in the study. Those with interproximal caries or restorations, abnormalities in shape or size and history of orthodontic treatment were excluded. Impressions of both arches were made using irreversible hydrocolloid and poured with dental stone. The MDWs of the required teeth were measured on the models using electronic digital vernier caliper from which widths of permanent canines and premolars were predicted using both T/J and BU approaches.

Results: Statistically significant (p = 0.00) positive correlation (r = 0.52-0.55) was observed between T/J and BU approaches. A statistically significant (p = 0.00) strong positive correlation (r = 0.72-0.77) was observed among girls, whereas boys showed a statistically nonsignificant weak positive correlation (r=0.17-0.42) based on gender.

Conclusion: Boston University approach can be further studied prospectively to make it possible as a prediction method of permanent tooth dimensions for children in primary dentition stage.

How to cite this article: Nuvvula S, Vanjari K, Kamatham R, Gaddam KR. Primary Dentition Analysis: Exploring a Hidden Approach. Int J Clin Pediatr Dent 2016;9(1):1-4.

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.

Mixed dentition space analysis in a Sudanese population

OBJECTIVE

To test the applicability of the Tanaka and Johnston equation for prediction of the mesiodistal width of unerupted permanent teeth in a Sudanese population and to develop a new prediction equation for this specific population if necessary.

DESIGN

A descriptive, cross-sectional study.

SETTINGS

School-based study.

SUBJECTS AND METHODS

Two hundred and fifty subjects (118 males and 132 females) age 13 - 19 years were randomly selected from two public secondary high schools in Khartoum State. Mesiodistal widths of the upper and lower permanent canines, first and second premolars (CPM) as well as the mandibular permanent incisors (MPI) were measured manually on the dental casts using a digital caliper. The predicted values of the mesiodistal widths were statistically compared with the respective actual sum of the canine and premolars of the same quadrant.

RESULTS

Moderate correlation coefficients were found between the sum of the mesiodistal width of the MPI and the sum of the CPM in males (0.618 for mandibular arch and 0.626 for maxillary arch) and females (0.726 for mandibular arch and 0.680 for maxillary arch). A low coefficient of determination was recorded (0.45 and 0.48) in both jaws for combined genders.

CONCLUSIONS

The Tanaka and Johnston equations overestimated the actual mesiodistal width of CPM in both arches for males and females. New prediction equations with more accurate regression parameters were proposed for the Sudanese population.

How to test validity in orthodontic research: a mixed dentition analysis example

INTRODUCTION

The data used to test the validity of a prediction method should be different from the data used to generate the prediction model. In this study, we explored whether an independent data set is mandatory for testing the validity of a new prediction method and how validity can be tested without independent new data.

METHODS

Several validation methods were compared in an example using the data from a mixed dentition analysis with a regression model. The validation errors of real mixed dentition analysis data and simulation data were analyzed for increasingly large data sets.

RESULTS

The validation results of both the real and the simulation studies demonstrated that the leave-1-out cross-validation method had the smallest errors. The largest errors occurred in the traditional simple validation method. The differences between the validation methods diminished as the sample size increased.

CONCLUSIONS

The leave-1-out cross-validation method seems to be an optimal validation method for improving the prediction accuracy in a data set with limited sample sizes.

Dimensions of central incisors, canines, and first molars in subjects with Down syndrome measured on cone-beam computed tomographs

INTRODUCTION

The literature on tooth dimensions in subjects with Down syndrome (DS) is scarce. To our knowledge, no studies have yet been published in which the morphometry of the teeth in DS subjects has been determined using computed tomography.

METHODS

The study group consisted of 40 subjects with DS, aged 10 to 40 years. An age- and sex-matched control group was selected. Cone-beam computed tomography images were retrieved from the archive of the Santiago de Compostela University in Spain. The maxillary central incisors, canines, and first molars were evaluated. The following variables were analyzed: overall tooth length, crown height, root length, mesiodistal diameter, vestibular-palatine diameter, crown-to-root ratio, and cervical circumference.

RESULTS

The teeth of subjects with DS were smaller than those of the controls, although the crown-to-root ratio was maintained. No clear sexual dimorphism was detected, but the root lengths of the incisors were greater in male subjects. Crown height, mesiodistal diameter, and crown-to-root ratio showed progressive reductions with age. There appeared to be a degree of "fluctuating dental asymmetry" with respect to vestibular-palatine diameter and cervical circumference.

CONCLUSIONS

Our findings confirm microdontia of the permanent teeth and progressive reductions in tooth sizes with age in persons with DS. These variations might be relevant to orthodontic treatment planning.

Applicability of the Tanaka-Johnston and Moyers mixed dentition analyses in Northeast Han Chinese

OBJECTIVES

To assess applicability of the Tanaka-Johnston and Moyers prediction methods in a Han ethnic group from Northeast China and to develop prediction equations for this same population.

DESIGN

Cross-sectional study.

SETTING

Department of Orthodontics, School of Stomatology, Jiamusi University, Heilongjiang, China.

PARTICIPANTS

A total of 130 subjects (65 male and 65 female) aged 16-21 years from a Han ethnic group of Northeast China were recruited from dental students and patients seeking orthodontic treatment. Ethnicity was verified by questionnaire.

MATERIAL AND METHODS

Mesio-distal tooth width was measured using Digital Vernier calipers. Predicted values were obtained from the Tanaka-Johnston and Moyers methods in both arches were compared with the actual measured widths. Based on regression analysis, prediction equations were developed.

RESULTS

Tanaka-Johnston equations were not precise, except for the upper arch in males. However, the Moyers 85th percentile in the upper arch and 75th percentile in the lower arch predicted the sum precisely in males. For females, the Moyers 75th percentile predicted the sum precisely for the upper arch, but none of the Moyers percentiles predicted in the lower arch.

CONCLUSIONS

Both the Tanaka-Johnston and Moyers method may not be applied universally without question. Hence, it may be safer to develop regression equations for specific populations. Validating studies must be conducted to confirm the precision of these newly developed regression equations.

Mixed dentition analysis - Applicability of two non-radiographic methods for Chennai school children

AIM

To evaluate the applicability of the Tanaka and Johnston (1974) and Moyers (1988) methods in predicting the size of permanent canines and premolars in Chennai school children.

MATERIALS AND METHODS

470 sets (127 female and 343 male) of cast models were included in the sample. Mesio-distal (m-d) widths of all teeth from left to right first molars were measured and compared with the predicted values derived from Tanaka and Johnston and Moyers methods.

RESULTS

There was significant bilateral symmetry and sexual dimorphism in teeth sizes seen in both the sexes. Sum of the m-d diameter of permanent mandibular incisors can be used reliably to predict the sum of m-d diameters of unerupted canines and premolars.

CONCLUSIONS

Tanaka and Johnston's method cannot accurately predict the m-d widths. Moyers' prediction tables can be used to estimate the m-d widths of unerupted canines and premolars closer to 50% probability level.

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.

Comparison of space analysis performed on plaster vs. digital dental casts applying Tanaka and Johnston's equation

OBJECTIVE: The purpose of this study was to compare dental size measurements, their reproducibility and the application of Tanaka and Johnston regression equation in predicting the size of canines and premolars on plaster and digital dental casts. METHODS: Thirty plaster casts were scanned and digitized. Mesiodistal measurements of the teeth were then performed with a digital caliper on the plaster and digital casts using O3d software system (Widialabs©).The sum of the sizes of the lower incisors was used to obtain predictive values of the sizes of the premolars and canines using the regression equation, and these values were compared with the actual sizes of the teeth. The data were statistically analyzed by applying to the results Pearson's correlation test, Dahlberg's formula, paired t-test and analysis of variance (p<0.05). RESULTS: Excellent intraexaminer agreement was observed in the measurements performed on both dental casts. No random error was present in the measurements obtained with the caliper and systematic error (bias) was more frequent in the digital casts. Space prediction obtained by applying the regression equation was greater than the sum of the canines and premolars on the plaster and digital casts. CONCLUSIONS: Despite an adequate reproducibility of the measurements performed on both casts, most measurements on the digital casts were higher than those on the plaster casts. The predicted space was overestimated in both models and significantly higher in the digital casts.

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.

Development of a prediction equation for the mixed dentition in a Pakistani sample

INTRODUCTION

Regression equations are widely used for mixed dentition analysis. However, estimations from these equations can vary in different population groups. The aim of this study was to produce simple linear equations and tables for Pakistani children.

METHODS

Two hundred subjects of Pakistani descent who met our criteria (ages, 13-15 years; 100 boys, 100 girls) were selected from local schools. The mesiodistal widths of all mandibular permanent incisors, canines, and premolars were measured and analyzed by using paired t tests. The results were also compared with predicted values from the Moyers and the Tanaka and Johnston methods. Correlation and linear regression analyses were performed between the predicted and actual tooth sizes for Pakistani children, and standard regression equations were developed.

RESULTS

No significant differences were observed for measured canine and premolar antimeres and sex. Significant and high positive correlations were found between the mandibular incisors and the combined mesiodistal widths of the canines and premolars for the maxillary (r = 0.65; P <0.001) and mandibular (r = 0.59; P <0.001) segments.

CONCLUSIONS

The equations and charts commonly used for North American children (75th percentile) did not accurately predict for our sample. The regression equations and tables developed in this study can be used for orthodontic treatment planning for children in Pakistan.

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

INTRODUCTION

Estimating the mesiodistal widths of unerupted permanent canines and premolars is an essential aspect of mixed dentition analysis. Several methods are used to predict tooth width. The best methods demonstrate high values of correlation and determination coefficients. In this study, we aimed to determine a linear regression equation that would predict the sum of the mesiodistal widths of mandibular permanent canines and premolars based on the sum of the widths of the 4 mandibular permanent incisors and first permanent molars.

METHODS

The sample consisted of 500 dental casts, obtained from white Brazilian patients (250 male, 250 female; average ages, 13.8 and 14.4 years, respectively). Mesiodistal tooth widths were measured with an electronic digital caliper. Intraclass correlation coefficients were used to determine measurement consistencies. Paired and unpaired Student t tests were used to determine right/left side and sex differences, respectively. A paired Student t test was also used to compare the predicted and actual sums of the mandibular permanent canines and premolars.

RESULTS

We found high values of correlation (r) and determination (r2) coefficients, varying from r = 0.795 to r = 0.81, and r2 = 0.599 to r2 = 0.656. These values are among the highest described in the literature for nonradiographic prediction methods. On average, there was no difference between predicted and actual widths of the mandibular permanent canines and premolars, and the standard errors of estimation were 1.49 mm for males, 1.36 mm for females, and 1.44 mm for the total sample (considering right and left sides of the mandibular arch together).

CONCLUSIONS

The proposed method showed good accuracy and was easy to use, but it must be tested in other populations.

Influence of sex and ethnic tooth-size differences on mixed-dentition space analysis

INTRODUCTION

Most mixed-dentition space analyses were developed by using subjects of northwestern European descent and unspecified sex. The purpose of this study was to determine the predictive accuracy of the Tanaka-Johnston analysis in white and black subjects in North Carolina.

METHODS

A total of 120 subjects (30 males and 30 females in each ethnic group) were recruited from clinics at the University of North Carolina School of Dentistry. Ethnicity was verified to 2 previous generations. All subjects were less than 21 years of age and had a full complement of permanent teeth. Digital calipers were used to measure the mesiodistal widths of all teeth on study models fabricated from alginate impressions. The predicted widths of the canines and the premolars in both arches were compared with the actual measured widths.

RESULTS

In the maxillary arch, there was a significant interaction of ethnicity and sex on the predictive accuracy of the Tanaka-Johnston analysis (P = .03, factorial ANOVA). The predictive accuracy was significantly overestimated in the white female group (P <.001, least square means). In the mandibular arch, there was no significant interaction between ethnicity and sex (P = .49).

CONCLUSIONS

The Tanaka-Johnston analysis significantly overestimated in females (P <.0001) and underestimated in blacks (P <.0001) (factorial ANOVA). Regression equations were developed to increase the predictive accuracy in both arches.

Mixed dentition space analysis in a Jordanian population: comparison of two methods

AIMS

To test the reliability of the Moyers charts and the Tanaka and Johnston equations in Jordanians and to derive coefficients of correlation between the combined mesiodistal widths of the four permanent mandibular incisors and the combined widths of the canine and premolars of the maxillary and mandibular quadrants.

METHODS

The dental models of the dentition of 130 male and 96 female Jordanian subjects (age range is 14-16 years) with complete permanent dentition were randomly selected. The mesiodistal width of the four permanent mandibular incisors, maxillary and mandibular canines, and premolar teeth were measured using a vernier gauge caliper to the nearest 0.1 mm. The actual teeth measurements were then compared with the predicted values derived from the Tanaka and Johnston equations and Moyers probability tables. Correlation and linear regression analyses were performed between the predicted and actual tooth size for Jordanian children and standard regression equations were developed.

RESULTS

Except for the maxillary arch in male subjects, Tanaka and Johnston regression equations underestimated the mesiodistal widths of permanent canines and premolars. On the other hand, there were no statistically significant differences between actual mesiodistal widths of canines and premolars and the predicted widths from Moyers charts at the 65% and 75% level for the lower and upper arches in male subjects and at the 85% level for the upper and lower arches in female subjects. For the newly developed regression equations, the correlation coefficients between the sum of the mandibular four incisors and the sum of the canine and premolars were 0.60 (for lower) and 0.51 (for upper) in male subjects and 0.59 and 0.64, respectively, in female subjects.

CONCLUSIONS

(1) Tanaka and Johnston prediction method was not accurate when applied to a Jordanian population. (2) Moyers method for prediction can be used for Jordanian children at different probability levels for male and female subjects.

Dental arch space and permanent tooth size in the mixed dentition of a skeletal sample from the 14th to the 19th centuries and 3 contemporary samples

Dental arch space and permanent tooth size in the mixed dentition were studied in 4 cohorts: (1) 48 skulls from the 14th to the 19th centuries from The Schreiner Collection in the Department of Anatomy, University of Oslo; (2) 39 boys and 34 girls of Sami origin born in the 1980s living in northern Norway; (3) 31 boys and 30 girls born in the 1960s living in southern Norway; and (4) 32 boys and 26 girls born in the 1980s living in the same part of southern Norway as the previous group. The sexes were unknown in the skeletal sample, and the groups were analyzed with the sexes pooled. The crown sizes of the permanent teeth in the mixed dentition of the Norwegian children who had lived between the 14th and the 19th centuries were smaller than those of contemporary children living in the same country. Probable reasons for this increase in tooth size include improved nutrition and reduced morbidity, because this study ruled out attrition as a major cause of the discrepancy in tooth size. The relative space (arch perimeter minus tooth size) in the group born in the 1960s deviated from that in the other 3 groups, indicating a greater degree of crowding in this group. The relative space in the skulls did not differ significantly from that in the groups born in the 1980s. This means that the improved caries situation during the last decades has changed the dental arch space in these populations. The irregularity index of the 4 mandibular permanent incisors was larger in the skulls than in the modern samples.