Permanent teeth development in a Spanish sample. Application to dental age estimation

Incidence of Middle Mesial Canals in Mandibular Molars during Root Canal Treatment and Nonsurgical Retreatment

INTRODUCTION

Large-scale clinical studies on the incidence of middle mesial canals (MMCs) in nonsurgical root canal treatment (RCT) and retreatment of mandibular molars are lacking. The primary aim of this observational study was to determine the incidence of MMCs in mandibular first and second molars that received RCT or nonsurgical retreatment (NSRetx). The secondary aim was to determine factors associated with incidence of MMCs.

METHODS

Included were 3018 mandibular molars that received RCT (n = 1624) or NSRetx (n = 1394) by 3 endodontists in a private practice. Demographic and procedural data were collected. Bivariate and multivariable (Poisson regression model) analyses were performed.

RESULTS

Incidence of MMCs was 8.8% (n = 267). Although the bivariate analysis showed that NSRetx was significantly associated with incidence of MMCs, this association did not reach the threshold for statistical significance after controlling for all covariates (P = .07). Multivariable analysis on the entire cohort showed that incidence of MMCs was significantly associated with younger age (risk ratio [RR] = 1.62; 95% confidence interval [CI], 1.28-2.06), male gender (RR = 1.48; 95% CI, 1.18-1.85), preoperative cone-beam computed tomography (CBCT) (RR = 1.48; 95% CI, 1.17-1.89), and first molar (RR = 2.30; 95% CI:1.74-3.05). Subgroup multivariable analyses revealed that incidence of MMCs was associated with male gender only in the RCT group (RR = 2.26; 95% CI, 1.55-3.30) but not in the NSRetx group (RR = 1.11; 95% CI, 0.82, 1.50); and with preoperative CBCT only in the NSRetx group (RR = 1.78; 95% CI, 1.28, 2.50) but not in the RCT group (RR = 1.10; 95% CI, 0.71, 1.69). Associations with younger age and first molar remained unchanged.

CONCLUSIONS

Overall incidence of MMCs was 8.8%. Incidence of MMCs was significantly higher in younger patients and in mandibular first molars but was not associated with the type of treatment.

Adapting Demirjian Standards for Portuguese and Spanish Children and Adolescents

Estimation of children's chronological age is highly important in human and forensic sciences. The Demirjian method has been reported as accurate for this purpose. The literature review shows some evidence that the accuracy of estimating chronological age via the Demirjian standards is not a straightforward process. The objective of this research is to analyze the reliability of the Demirjian standards in Portuguese and Spanish children and adolescents and adapt it to include sex and group age as contingent factors.

METHODS

Orthopantomographs of 574 Portuguese and Spanish male and female children and adolescents were employed to test the reliability of the Demirjian method. After testing for inter-rater consistency and age estimation using the Demirjian standards, multiple regression analysis was performed controlling for sex and age group.

RESULTS

The Demirjian standards overestimated chronological age for both sexes, mainly for females. Through the development of regression functions, more detailed dental age estimation was performed. The predictive capacities of the Demirjian method and the significant teeth varied as a function of children's age. The Demirjian global standard predicted over 65% of the variance of the chronological age. Taking a tooth-by-tooth approach, the predictive ability increased by over 70%.

CONCLUSIONS

The accuracy of estimating chronological age via the Demirjian method is not as reliable as it might appear, judging from the results found according to age group and according to sex crossed with age group.

Relationship between Physiological Resorption of Primary Molars with Its Permanent Successors, Dental Age and Chronological Age

The aim of the present study was to analyse root resorption of the primary mandibular molars and their relationship with their permanent successors and the age of the patient. Methods: The sample consisted of 408 digital panoramic radiographs. The mesial and distal crown-to-root ratios (CRR) of #74 and #75 were calculated by dividing the measures of the length of each root by its coronal height. The Demirjian formation stage of the premolar was established, and dental age was determined. A descriptive and statistical analysis was performed using SPSS to determine the correlation between the variables (Pearson’s correlation coefficient) and to identify the differences between them (Student’s t-test), with a confidence level of 95%. Results: 723 molars were measured, and tables of CRR depending on dental and chronological age were obtained. The CRR decreased with increasing dental and chronological age, but not uniformly. The CRR of #74 and #75 decreased slightly when the successor premolar was in the initial stages of formation. Gender differences were obtained with respect to chronological age, mainly in girls, because the root resorption of #74 was always more advanced, and the formation of the #34 more advanced. Conclusions: Root resorption of the molar is slight and progressive when the successor premolar begins formation until stage D, and becomes higher starting at stage E. It is possible to determine the state of the child’s maturation and the CRR according to dental and chronological age.

Dental maturation in a Chinese sample using Demirjian method

BACKGROUND

Dental calcification information is relevant for clinical, archaeological, and forensic applications. However, dental maturity measurements in current cohorts of Chinese children are insufficient.

AIM

This study aimed to establish the mandibular dental maturity table and determine the accuracy of dental age estimation using the Demirjian method in a Chinese sample.

SUBJECTS AND METHODS

Permanent mandibular teeth, excluding the third molar, in 2091 panoramic radiographs of 1008 males and 1083 females aged 3-15 were graded, and dental age was estimated according to Demirjian's criteria. Age-of-attainment was calculated with probit regression for each stage by sex, and sex differences were analysed using the Mann-Whitney U test. Dental age was compared with chronological age using paired t-tests.

RESULTS

Although females showed earlier age-of-attainment than males, significant sex differences were only found in stages D-G (p < 0.05). The Demirjian method overestimated the dental age in both males (0.68 ± 1.05 years) and females (0.59 ± 0.97 years).

CONCLUSIONS

The relationship between mineralisation stage and chronological age in this study can be applied as a reference for mandibular dental maturity of Chinese children and adolescents. The Demirjian method overestimated the chronological ages of this sample.

Accuracy of the Demirjian, Willems and Nolla methods for dental age estimation in a northern Chinese population

OBJECTIVE

The objective of the present study was to evaluate the accuracy of the Demirjian, Willems, and Nolla methods for dental age estimation on a sample of the northern Chinese population.

DESIGN

The study consisted of 2000 panoramic radiographs (1000 boys and 1000 girls) with an age range between 5 and 14 years. The mean error and absolute mean error were calculated according to each method, and the accuracy was statistically analysed.

RESULTS

The three methods used for Chinese subjects overestimated the dental age by 1.16, 0.50, and 0.07 years. The absolute mean error was largest in most age groups for the Demirjian method, which was considered inaccurate in age estimation for teenagers, and it was more than 1.00 years for only several age groups for the Willems method and only girls aged 14 years for the Nolla method. The mean error and absolute mean error were lowest for the Nolla method and highest for the Demirjian method.

CONCLUSIONS

Although the Demirjian method is frequently used in Chinese subjects for legal and medical purposes, the Willems and Nolla methods were more reliable than the Demirjian method. Among the three methods, the accuracy in the northern Chinese subjects was highest for the Nolla method. Therefore, it is recommended to evaluate the accuracy of different methods before assessing the age in specific populations.

Accuracy assessment of dental age estimation with the Willems, Demirjian and Nolla methods in Spanish children: Comparative cross-sectional study

Background

The objective of this study was to evaluate and compare the validity and accuracy of the Willems, Demirjian and Nolla methods in predicting chronological age in a Spanish ethnicity population.

Methods

A sample of 604 orthopantomographs of Spanish children aged 4 to 13 years was evaluated by two independent evaluators. Descriptive statistics were applied to calculate the chronological age and dental age, presenting the mean and standard deviation. The difference between dental age and chronological age was calculated for each method. A positive result indicated an overestimation and a negative figure indicated an underestimation. The Wilcoxon test for paired data and Spearman’s correlation coefficient were applied by age groups and sex to compare the chronological age and dental age of each method (that of Willems, Demirjian and Nolla). Statistical tests were performed at a 95% confidence level.

Results

The interexaminer agreement was 0.98 (p = 0.00), and the intraexaminer agreement was 0.99 (p = 0.00). The Willems method significantly overestimated the age of boys (0.35 years (0.93)) and girls (0.17 years (0.88)). The Demirjian method significantly overestimated the age of boys (0.68 years (0.95)) and girls (0.73 years (0.94)). The Nolla method significantly underestimated age in boys (0.44 years (0.93)) and girls (0.82 years (0.98)).

Conclusions

In the Spanish population, the use of the Demirjian method for legal and medical purposes is frequent. This study reveals that the Willems method is more appropriate due to its greater precision in estimating dental age.

Correlation coefficients for predicting canine diameters from premolar and molar sizes

Background/purpose

The permanent canine is the most widely used tooth for sex estimation because it is the tooth with the highest degree of sexual dimorphism; however, there are several factors that can limit the analysis (e.g., pathologies, postmortem loss). The aim of this work was to analyse the correlation between the dimensions of the canines and those of the premolars and molars, and evaluate the correspondence of real and predicted canine dimensions by applying the equations developed.

Materials and methods

The sample was composed of digital models of 80 adult individuals from Temuco, Chile. The buccolingual and mesiodistal diameters of the canine, premolar and molar dental crowns were measured and Pearson's linear regression analysis was performed in order to determine the correlation between the diameters. The equations obtained from the reference subsample were applied to a validation subsample to predict canine dimensions from the dimensions of the postcanine teeth.

Results

Four regression equations were obtained, all for prediction of the size of the lower canines, whose correlation coefficient ranged from 0.701 to 0.738. The regression equations developed with the reference sample were tested on the validation sample using a Student's t-test for paired samples and the intraclass correlation coefficient. The differences between actual dental size and that predicted by the equations were not significantly different, and concordance analysis showed a moderate degree (0.485–0.585).

Conclusion

There is a limited correlation of canine dimensions with respect to premolars and molars. The correspondence between the actual and predicted canines dimensions is moderate.

The applicability of the Demirjian, Willems and Chaillet standards to age estimation of 5-15 year old Indian children

BACKGROUND

Demirjian's method of age estimation has been reported to overestimate age and Willems' method to give consistently more accurate results. Not enough, however, is known about the applicability of Chaillet's standards.

AIM

The present study aimed to compare the accuracy of Demirjian's, Willems' and Chaillet's standards in age estimation of 5 to 15 year-old Indian children.

DESIGN

In this cross-sectional observational study, three methods were compared for accuracy in estimating the age of 1200 Indian children aged 5-15 years.

RESULTS

Demirjian's method overestimated age by +0.24 ± 0.80 years, +0.11 ± 0.81years and +0.19 ± 0.80 years in boys, girls and the total sample, respectively. With Willems' method, overestimations of +0.09 ± 0.80 years, +0.08 ± 0.80 years and +0.09 ± 0.80 years were obtained in boys, girls and the total sample, respectively. Chaillet's method underestimated age by -0.12 ± 0.69 years, -0.45 ± 0.88 years and -0.25 ± 0.83 years in boys, girls and the total sample, respectively. Statistically significant differences were observed between dental and chronological ages with all methods (p < 0.001). Significant sex-based differences were observed only with Demirjian's and Chaillet's methods (p < 0.05).

CONCLUSION

Willems' method was the most accurate in age estimation, followed by Demirjian's and Chaillet's methods. While Demirjian's method was more accurate than Chaillet's in females, Chaillet's method better predicted the age of males.

Assessment of the Dental Age of Children in the Polish Population with Comparison of the Demirjian and the Willems Methods

Background

Dental age is less affected than the bone age by nutritional and hormonal factors. The assessment of dental age in children is of value in clinical and forensic practice. The aims of this study were to compare the Demirjian method and the Willems method in the assessment of dental age in children in Poland and to consider the need to standardize dental age assessment.

Material/Methods

Polish children of Caucasian ethnicity (n=1,002) who were treated at a single orthodontic center between 1994–2016 included girls (n-540) and boys (n=462) aged between 4–17 years, and 1,002 panoramic radiographs were reviewed. Dental age was assessed using the Demirjian method and the Willems method, the findings of the two methods were compared with the chronological age of the study participants.

Results

Following statistical analysis, both the Demirjian method and the Willems method overestimated the dental age of the younger study participants, and underestimated the dental age of the older study participants. Both the Demirjian method and the Willems method had similar accuracy in estimating the chronological and dental age in the Polish population.

Conclusions

In the assessment of dental age in Polish children from panoramic radiographs, both the Demirjian method and the Willems method were accurate and should still be used as a method of choice. However, it seems reasonable to create international standards for the assessment of dentition maturity for this population to obtain a more acceptable range of error values between the dental age and chronological age.

Dental age assessment on panoramic radiographs: Comparison between two generations of young Finnish subjects

Objective

To analyse the accuracy of a meta-analysis-based dental age assessment (DAA) method in Finnish paediatric patients and to compare the dental development between two generations of Finnish children.

Methods

Panoramic radiographs of Finnish Caucasian healthy children from two generations (early: born 1981–1984; subsequent: born 1996–2008) were analysed. All developing teeth on the left maxilla and mandible as well as the third permanent molars were analysed following Demirjian’s classification. For each patient, dental age was calculated and compared with chronological age. Dental maturation patterns between the two groups were compared.

Results

The study included 200 Finnish Caucasian healthy children from two generations (early: aged 7–13 years; subsequent: aged 6–15 years). In the early generation, DAA underestimated the chronological age by a mean of 3.15 years. The underestimation was only 0.11 years in patients < 10 years, but 3.86 years in patients ≥ 10 years. In the subsequent generation, the dental age was overestimated by a mean of 0.34 years; by 0.40 years in patients < 10 years and by 0.08 years in patients ≥ 10 years.

Conclusions

The present DAA method is applicable to current Finnish children. Differences in dental development between two generations of Finnish children were detected.

The applicability of the original and revised Demirjian standards to age estimations of 5-15 year old Indian children

BACKGROUND

The Demirjian method has been the most widely tested method for the estimation of the dental age of children and adolescents. However, only three studies have compared Demirjian's original and revised seven-tooth methods, four-tooth method and alternate four-tooth method, none of them conducted on an Indian population.

AIM

The present study aimed to compare the applicability of the original and revised seven-tooth and four-tooth and alternate four-tooth standards for age estimation of 1200 Indian children aged 5-15 years old.

DESIGN

The study was designed as a retrospective cross-sectional study.

RESULTS

Demirjian's original seven-tooth method overestimated age by 0.64 ± 1.44, 0.75 ± 1.50 and 0.69 ± 1.46 years in boys, girls and the total sample, respectively. Demirjian's revised seven-tooth method overestimated age by + 0.24 ± 0.80, + 0.11 ± 0.81 and + 0.19 ± 0.80 years in boys, girls and the total sample, respectively. Demirjian's original four-tooth method overestimated age by 0.79 ± 1.59, 0.59 ± 2.77 and 0.72 ± 2.30 years in boys, girls and the total sample, respectively. Demirjian's alternate four-tooth method overestimated age by 1.31 ± 1.07, 1.20 ± 1.10 and 1.26 ± 1.08 years in boys, girls and the total sample, respectively. Statistically significant differences were observed between dental and chronological ages with all methods (p <0.001).  Significant gender-based differences were observed only with Demirjian's revised seven-tooth and original four-tooth methods (p <0.05).  Conclusion: The revised seven-tooth standards most accurately predicted the age of the study sample (mean prediction error = 2.28 months), followed by the original seven-tooth, four-tooth and alternate four-tooth standards. The Demirjian original seven-tooth method was significantly more accurate in boys compared to girls, while the reverse was true for the Demirjian revised seven-tooth and original four-tooth methods.

Third molar maturity index (I3M) for assessing age of majority: study of a black South African sample

AIMS

The evaluation of the cutoff value of I_3M = 0.08 for discriminating black South African minors from adults, and its relationship with chronological age.

MATERIAL AND METHODS

A sample of 833 panoramic radiographs of healthy black South African subjects (500 females and 333 males), in the age range of 14 to 24 years (mean age 17.67 years in females and 17.42 years in males), was retrospectively evaluated.

RESULTS

ICC values were 99.10% (95% CI 97.70 to 99.70%) and 99.20% (95% CI 98.00 to 99.60%), for the intra- and inter-observer reliability, respectively. I_3M decreased as the real age gradually increased in both sexes. According to the logistic regression model, the variable sex was not significant when the probability that an individual is 18 years or older was calculated. The I_3M = 0.08 was valuable in discriminating between adults and minors. The overall accuracy (ACC = fraction of accurately classified subjects) is 0.90 (95% CI 0.87-0.91); the proportion of correctly classified subjects (Se = sensitivity) is 0.80 (95% CI 0.76-0.84), and specificity (Sp) is 0.95 (95% CI 0.93-0.97). The PPV (predictive positive value) is 0.96 (95% CI 0.95-0.97), and the negative predictive value is 0.76 (95% CI 0.72-0.80).

CONCLUSION

The results show that I_3M is a valuable method to distinguish subjects who are around legal adult age in South Africa.

Validity and accuracy of three radiographic dental age estimation methods in Brazilians

OBJECTIVE

To validate, analyse accuracy, and construct multiple regression formulae of three age estimation methods - Liliequist and Lundberg, Haavikko, and Mornstad - using mineralization stages of permanent teeth in Brazilians.

METHODS

Panoramic radiographs of 1009 Brazilian children and adolescents (387 males and 622 females) aged 8-15.99 years were analysed using the aforementioned methodologies.

RESULTS

The overall accuracy (absolute difference=AD and dental age-chronological age=DA-CA) of the methods was as follows: Liliequist and Lundberg, AD=0.97 and DA-CA=-0.58; Haavikko, AD=1.42 and DA-CA=-1.35; and Mornstad, AD=2.48 and DA-CA=0.78. After sex-based stratification, the values for males were as follows: Liliequist and Lundberg, AD=0.91 and DA-CA=-0.45; Haavikko, AD=1.80 and DA-CA=-1.75; and Mornstad, AD=2.74 and DA-CA=1.17. In females, the values were as follows: Liliequist and Lundberg, DA=1.01 and DA-CA=-0.67; Haavikko, AD=1.17 and DA-CA=-1.09; and Mornstad, AD=2.31 and DA-CA=0.53. The Liliequist and Lundberg technique predominated, followed by Haavikko and Mornstad when distinction was present between sex and age. Multiple regression formulae were constructed from the data presented for the Liliequist and Lundberg, Haavikko and Mornstad methodologies.

CONCLUSIONS

The validation of the methodologies in the Brazilian population is possible. The Liliequist and Lundberg method most closely represented the Brazilian sample.

Age estimation of Chinese children based on second molar maturity

In forensic medicine and many other fields, age estimation by the use of teeth is of great importance for the purpose of individual identification. In the past, however, age estimation based on the second molar mineralization was scarcely performed. In this study, a total of 1657 panoramic radiographs taken from 834 males and 823 females of northern Chinese origin in the age bracket 5 to 25 years were assessed. The mineralization status of the second molars was determined using the classification described by Demirjian et al. Results showed that the left and right, as well as maxillary and mandibular second molars were generally at similar stages of mineralization. The maxillary left second molars (27) at stage D, mandibular left second molars (37) at stages C, D, F, and G, and mandibular right second molars (47) at stages D, F, and G showed a significantly lower average age in female subjects than in male subjects. In males, fully developed second molars first appeared with 12 years of age; in females, stage H occurred with 11 years at the earliest. One male individual and one female individual with second molars showing stage G were 23 years old. It was concluded that second molars showing stage H do not exclude an age under 14 years and that second molars showing stage G do not exclude an age above 18 years.

A comparative evaluation of the applicability of two adapted Häävikko methods for age estimation of 5-15 year old Indian children

Dental age determination methods that require the assessment of all teeth are tedious and time-consuming. Adapted methods that assess fewer teeth may be more easily applicable. The present study compared the applicability of two adapted Häävikko methods which evaluate seven mandibular teeth (HAM1) and four reference teeth (HAM2) in a population of 5 to 15 year-old Indian children. The HAM1 method underestimated age by -0.17 ± 0.80 years, -0.29 ± 0.83 years and -0.22 ± 0.82 years in boys, girls and the total sample respectively, while the HAM2 method underestimated age by -0.34 ± 0.88 years, -0.51 ± 0.82 years and -0.41 ± 0.86 years in boys, girls and the total sample, respectively. Significant gender-based differences were observed in mean DA-CA with both methods (p < 0.05). While both methods could be used for age estimation of the present population, the HAM1 method was the more accurate of the two.

Third molar maturity index (I3M) for assessing age of majority in a black African population in Botswana

Assessment of legal age, also known as age of majority, is a controversial issue as there are few body biomarkers or evidence during late adolescence differentiating a subject from being a minor or adult. The third molar was recognized as a suitable site for age examination in late adolescence. We analyzed the development of the left mandibular third molar by the third molar maturity index (I3M) and a specific cut-off value of I3M = 0.08, established by Cameriere et al. in 2008 and used it for discriminating between minors and adult black Africans from Gaborone, Botswana. A final sample of panoramic radiographs (OPTs) of 1294 people (582 males and 712 females) aged between 13 and 23 years was evaluated. The real age decreased as I3M gradually increased. There was no statistically significant difference in the third molar development evaluated using I3M between males and females (p > 0.05) across different I3M classes. Results of 2 × 2 contingency tables for different cut-off values indicated that I3M = 0.08 was useful in discriminating between adults and minors. Precisely, for I3M = 0.08, the values of accuracy or overall fraction of correctly classified were 0.91 in males with a 95 % confidence interval (95 % CI) of 0.88 to 0.93 and 0.92 (95 % CI, 0.90 to 0.93) in females. Values of sensitivity of the test or the proportion of participants being 18 years and older were 0.88 (95 % CI, 0.87 to 0.90) in males and 0.88 (95 % CI, 0.90 to 0.93) in females, while values of specificity or proportion of individuals younger than 18 who have I3M <0.08 were 0.94 (95 % CI, 0.91 to 0.96) in males and 0.96 (95 % CI, 0.94 to 0.98) in females. Positive predictive values of the test, where the participants whose I3M <0.08 were adults, were 0.94 (95 % CI 0.91 to 0.96) in males and 0.97 (95 % CI, 0.94 to 0.98) in females, while negative predictive values of the test, where the participants whose I3M was ≥0.08 were minors, were 0.88 (95 % CI 0.85 to 0.90) in males and 0.97 (95 % CI, 0.94 to 0.98) in females. The likelihood ratios of the positive test (LR+) were 13.67 (95 % CI, 9.21 to 21.02) in males and 23.73 (95 % CI, 14.20 to 42.28) in females, while likelihood ratios of the negative test (LR-) were 0.12 (95 % CI 0.10 to 0.16) in males and 0.12 (95 % CI, 0.11 to 0.15) in females. Bayes post-test probabilities, p, were 0.94 (95 % CI 0.90 to 0.98) in males and 0.97 (95 %CI, 0.93 to 1.00) in females. These results indicate with high accuracy that I3M may be a useful alternative method in legal and forensic practice to discriminate individuals of black African origin who are around the legal adult age of 18 years in Botswana. Further studies should address the usefulness of this method and specific cut-off for different adolescent populations.

Time of mineralization of permanent teeth in children and adolescents in Gaborone, Botswana

The mineralization sequence of permanent dentition can be used to assess the stage of development and age of individuals. The most commonly used methods are based on the assessment of developmental stages of target groups of teeth on one side of the lower jaw. When compared with the rest of the world, fewer studies have been done on dental age in Sub-Saharan Africa, particularly in the region of Southern Africa. The aim of this study was to determine the chronology of mineralization of permanent teeth by the evaluation of developmental stages according to the Demirjian's method from 1973 and to evaluate dental age by using sex-specific self-weighted scores for dental stages and 50th percentile conversion tables of total maturity scores of seven mandibular teeth. We used a sample of panoramic radiographs (OPTs) of black African children and adolescents from the city of Gaborone, Botswana, with the aim of forming an appropriate sample to evaluate the development of the teeth in this socio-geographic environment. The final sample consisted of 1760 OPTs (807 males and 953 females) of individuals aged 6-23 years. The developmental stages of the all permanent teeth in the left side of the maxilla and the mandible were evaluated. Comparing the maxilla and the mandible, we found similar development within different stages for most of the teeth. In comparison to the average age at each stage of development, including the third molars between males and females, it is evident that females are slightly faster in developing permanent teeth, but without statistical significance for most of the developmental stages. Applying 50th percentile conversion tables for calculating the dental age for the first seven mandibular teeth, 616 OPTs of the children (299 males and 317 females), aged 6.08-16.80 years, were evaluated and their dental age was calculated. Mean dental age was overestimated in comparison to chronological age by 1.25±1.11 years and 0.72±1.02 years for males and females, respectively (p<0.001). These findings indicate that Demirjian's method from 1973 is not suitable for routine use and that there is a need for establishing specific standards for Botswana children of black African origin for dental age estimation.

Dental age assessment on panoramic radiographs in a Swiss population: a validation study of two prediction models

OBJECTIVES

Dental age assessment methods are widely used for age estimation. This study aimed to analyse the accuracy of a meta-analysis method to estimate dental age in Swiss individuals and to detect potential limitations of the method. Precision of repeated tooth staging using Demirjian's classification on maxillary and mandibular teeth was also assessed.

METHODS

Panoramic radiographs of 50 Swiss white healthy children were analysed. Developing teeth on the left maxilla and mandible and all third permanent molars were staged following Demirjian's classification. Dental age was calculated for each subject, using a random effects model and a fixed effect model, and compared with chronological age.

RESULTS

The mean error of the dental age ranged between -3 and +1 months for both the calculation models. Dental age calculated with the fixed effect model overestimated the age of the subjects (average + 0.10 y, ranging from -1.95 y to +2.16 y) compared with their chronological age, whereas the random effects model underestimated the age (average -0.32 y, ranging from -2.24 y to +1.61 y).

CONCLUSIONS

Demirjian's method allowed a precise repeated staging of maxillary and mandibular developing teeth. For both calculation models, dental age correlated well, on average, with chronological age of Swiss subjects younger than 12 years. The random effects model showed a better accuracy for these subjects than the fixed effect model. However, both models underestimated the chronological age in subjects older than 12 years.

Dental age estimation in living individuals using 3.0 T MRI of lower third molars

In order to increase the validity of age estimation in adolescents and young adults when there is no legitimation for X-ray examinations, it seems desirable to be able to assess the mineralization of third molars using X-ray-free imaging procedures. In the present study, the mineralization stages of lower third molars were determined prospectively in 269 male and 248 female individuals aged 12 to 24 years using 3.0 T MRI. The classification system of Demirjian et al. was used to determine the stages. This study presents the minima and maxima, means and standard deviations, median values, and lower and upper quartiles separately for both sexes, for the mineralization stages B-H. Statistically significant sex differences were observed for the mineralization stages C, E, F, and G, and a faster developmental rate was observed for males. It was concluded that magnetic resonance imaging is an X-ray-free alternative to orthopantomography when assessing mineralization of third molars.

Using Dental Age to Estimate Chronological Age in Czech Children Aged 3-18 Years

The Demirjian methods to determine dental age are based on analysis of orthopantograms. The dental age estimation is based on establishing the tooth development stages. The purpose of this study was to assess the accuracy of estimation of dental age by Demirjian in the use of all of his four methods. 505 Czech healthy boys and girls aged 3 to 18 years were examined radiographically at the Department of Stomatology, Second Faculty of Medicine, Charles University in Prague. It was mentioned the factors of underlying diseases influence the accuracy of the dental age estimation. For statistical evaluation, descriptive statistics was used to compare deviations of the mean values of chronological and dental age in each age group. The resulting difference between dental age and chronological age is not significant in both genders only when using both Demirjian 7-teeth methods of 1973 and 1976. Therefore these may be most appropriately used for forensic age estimation. There are shown standard deviation differences in different countries. Demirjian's original 7-teeth method from 1973 and Demirjian's revised 4-teeth method from 1976 appear to be the best methods for calculating the dental age of healthy Czech children of both genders.

The accuracy of estimating chronological age from Demirjian and Nolla methods in a Portuguese and Spanish sample

BACKGROUND

Age determination has great importance in many clinical decisions, being commonly used in odontopediatrics, orthodontics, pediatrics, and forensic medicine. The Nolla and Demirjian et al. methods have been used for these purposes. However, estimating chronological age by means of the dental mineralization stage is not a straightforward analysis, and it is fundamental to test the validity of these methods and their applicability to populations. In this article we intend to compare the accuracy of estimating chronological age from dental age measured with the Nolla and Demirjian methods in a Portuguese and Spanish sample, considering the variables of sex and age-group.

METHODS

The sample was composed of 821 orthopantomographs of healthy Portuguese (n = 270) and Spanish (n = 551) subjects from 4 to 34 years old. For the Nolla and Demirjian methods, seven mandibular left teeth were examined, staged according to the dental maturity scale of each method. We obtained a good index of inter-rater agreement, a good internal consistency for the teeth assessment, and a good temporal consistency.

RESULTS

Dental age was calculated for each method. The Demirjian et al. method tends to overestimate the real age of participants and the Nolla method tends to underestimate it. The accuracy of both methods varied between the sexes and age groups. Both methods were found to be more precise with males. As the age-group increases, the predictive capacities of both methods diminish. The Nolla method was more accurate than the Demirjian method in early and late childhood for both sexes. Neither method could predict chronological age in adults.

CONCLUSIONS

We can estimate chronological age for early and late childhood, through the Nolla and Demirjian methods, with the former showing greater predictive capacities than the latter. The Demirjian method tends to overestimate age and the Nolla method tends to underestimate it, leading to the importance of forming regression equations adapted to the population studied. Nolla and Demirjian formulas adapted to our sample were created as a function of sex and age-group.