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This study proposed to evaluate the precision of Nicodemo, Moraes and Médici method and the method proposed by Demirjian and compare both methodologies in relation to the efficiency and applicability in the Brazilian population. The sample consisted of 124 panoramic radiographs of subjects in the age group from 7 to 16 years old, 66 patients female and 58 male. For the comparison of the genders in relation to the average percentage difference, the t-Student test was considered. In average the method of Nicodemo, Moraes and Médici presented for the female gender an estimated result 14.7% lower than the real age. For the male gender the estimative obtained was that for each year of variation of the real age the method of Nicodemo estimates a variation of 0.48 years, with a confidence interval of 95% given by (0.43; 0.54). For the method of Demirjian the result was that for each year of variation of the real age the method of Demirjian estimates a variation of 1.00 year, with a confidence interval of 95% given by (0.85; 1.15) for the male gender and 0.96 years, with a confidence interval of 95% given by (0.84; 1.08) for the female gender. It is concluded that the Method of Nicodemo, Moraes and Médici tends to underestimate the real age and that as the real age increases this underestimate becomes higher. Now, the method of Demirjian tends to over- estimate the real age in 8.2 months for the male gender and in 7.1 for the female one in average.

The term age represents the life stages of the human being, in other words, it is related to the development of the individual’s maturation [

The age estimation can be given through the dental clinical analysis and through the radiographic investigation of the dental elements. Different methods have been recommended to estimate the age through the dental development, among them we find Nicodemo, Moraes and Médici [

In 1974, Nicodemo, Moraes and Médici [

For the use of the table of Nicodemo, Moraes and Médici [

The method of Demirjian et al., presented in 1973 [

At the present time, to estimate the age in Brazilians, it has been recommended the use of the mineralization chronology table of the permanent teeth developed by Nicodemo, Moraes and Médici [

tion of this methodology in Brazilian individuals in order to compare the results obtained with the table recommended by Nicodemo, Moraes and Médici [

The initial sample will consist of 124 panoramic radiographs from the Dentistry College of the University of São Paulo, leucodermic subjects, in the age group from 7 to 16 years old, 66 patients of the female gender and 58 of the male gender. The age estimation of the sample was obtained through the method of Demirjian and through the method of Nicodemo, Moraes and Médici as described in the literature. For the radiographic interpretation, 3 operators were calibrated for both methods, this way a standardization of the radiographic analysis was obtained. The panoramic radiographs were numbered from 50 to 176 randomly. The data; age—years and months—and gender, were recorded in a form. The operators estimated the age of the sample firstly through the method of Demirjian and later through the method of Nicodemo, Moraes and Médici.

The method of Demirjian; the seven mandibular teeth, left side, in the following radiographic sequence: second molar, first molar, second premolar, first premolar, canine, side incisor and central incisor were analyzed and according to its root development, through comparison, it was attributed a stage to each tooth according to the eight stages proposed by Demirjian. Then it was attributed the value (score) to each phase according to the tables proposed by Demirjian, which take into consideration the gender. The values obtained were add and converted in age using the conversion table proposed by Demirjian.

The method of Nicodemo, Moraes and Médici; the radiographic images of the permanent teeth present in the panoramic radiographs with the eight development stages proposed by the authors were compared. Then it was applied the chronologic table of the permanent teeth mineralization among Brazilians proposed by the authors. It was obtained to each of the permanent teeth a score or value in months for the age. The most discrepant maximum and minimum values were eliminated when these existed. And then, it was determined, from the maximum and minimum values found, an age average of the individuals age in months.

The results obtained through the methodology of Demirjian were transformed in months and tabulated, as well as the results obtained through the method of Nicodemo, Moraes and Médici. In the statistical analysis for the evaluation of the estimated age variation of the different methods in relation to the real age variation it was considered the estimation of the angular coefficient through the linear regression model. For the evaluation of the different methods quality in the real age estimation, it was considered the Bland-Altman model, where for the evaluation of the bias between the estimated age and the real age, it was considered the test of Student for paired samples. For the estimation of the method error, it was considered the variance components model, with the estimation of the interclass correlation coefficient. Confidence intervals were constructed with 95% of confidence and values of p lower than 0.05 indicated statisticcal significance.

For the use of the radiographic data of the individual it was obtained together the Orthodontics department of the University of São Paulo the consent previously given, by the responsible ones, authorizing the use of the data to the purpose of researching.

For the method of Nicodemo, Moraes and Médici in all the age estimative, the average, the maximum and minimum and for both genders, it tested at first the null hypothesis that for each year of variation of the real age the method estimates a variation of one year, versus the alternative hypothesis that for each year of variation in the real age the method of Nicodemo estimates a different variation of one year. The result of the statistical test indicated the rejection of the null hypothesis (p < 0.001).

1) Evaluation of the age estimation through the method of Nicodemo, Moraes and Médici—Average estimated age.

The estimative obtained for the male gender was that for each month of variation of the real age the method of Nicodemo, Moraes and Médici estimates a variation of 0.48 months, with a confidence interval of 95% given by (0.43; 0.54). The method sub estimates the real age, increasing this sub estimation as the real increases (

The bias in the real age estimation depends on the age, as it can be observed in the figure below, where it can be observed that for higher ages the method tends to

sub estimate the real age (

The estimative obtained with the female gender was that for each month of variation of the real age the method of Nicodemo estimates a variation of 0.41 months, with an confidence interval of 95% given by (0.36; 0.45). The method sub estimates the real age, increasing this sub estimation as the real age increases (

The bias in the estimation of the real age depends on the age, as it can be observed in the figure below, where it can be observed that for higher ages the method tends to sub estimate the real age (

2) Evaluation of the age estimative through the method of Demirjian.

At first it was tested the null hypothesis that for each month of variation of the real age the Demirjian’s method estimates a variation of one year, versus the alternative hypothesis that for each year of variation of the real age the Demirjian’s method estimates a different variation of one year. The result of the statistical test indicated the non rejection of the null hypothesis for the male gender (p = 0.979) and for the gender female (p = 0.517).

The Demirjian’s method estimated a variation of 1.00

months, with a confidence interval of 95% given by (0.85; 1.15) for each month of variation of the real age it for the male gender (

Defining the bias as it being the difference between the result of the real age and the estimated age through the method of Demirjian, it was tested the null hypothesis that the average bias is equal to 0 versus the alternative hypothesis that the bias differs from 0.

The estimated bias for the male gender was of −8.2 with a confidence interval of 95% given by (−11.74; −4.62). The result of the statistical test indicated the rejection of the null hypothesis in the significance level of 5% (p < 0.01), indicating that the hypothesis of absence of bias between the results of real age and estimated age through the method of Demirjian is rejected. These results indicate that in average the results of the real age are 8.20 months lower than the results of estimated age through Demirjian. The interval (−11.74; −4.62) has 95% of chance of containing the real average difference (bias) (

For the female gender the estimated bias was −7.1 with a confidence interval of 95% given by (−10.97; −3.31). The result of the statistical test indicated the rejection of the null hypothesis in the significance level of 5% (p < 0.01), indicating that the hypothesis of absence of bias between the results of real age and estimated age through the method of Demirjian is rejected. These results indicate that in average the results of the real age are 7.10 months lower than the results of the estimated age by Demirjian. The interval (−10.97; −3.31) has 95% of chance of containing the real average difference (bias)

(

The diagram of dispersion with the average of both results and the difference between them is presented in the chart bellow, where it can be seen the concordance limits and the estimated bias.

3) Method’s error.

For the method of Demirjian the estimated error for the method was corresponding to 5.29 months. The

estimated intra-class correlation was equal to 89.58%, indicating a good repeatability among the results of the evaluators. And for the method of Nicodemo Moraes and Médici the estimated error for this method was corresponding to 2.93 months. The estimated intra-class correlation was equal to 85.32%, indicating a good repeatability among the results of the evaluators.

The studies developed by Nicodemo [^{ }and Médici [

In the present study it was verified that for each month of variation of the real age the method of Nicodemo, Moraes and Médici [^{ }[

In this study the percentage of difference between the estimated and the observed result for each one of the methods in relation to the different ages show that the higher the real age the higher is the sub estimation of the method of Nicodemo, Moraes and Médici [

The method of Nicodemo, Moraes and Médici [^{ }tends to underestimate the real age and as the real age increases, higher becomes this underestimate. While, the method of Demirjian et al. [