The influence of impaction on the rate of third molar mineralisation in male black Africans

One of the main criteria used in dental age diagnostics in living adolescents and young adults is assessment of the mineralisation stage of the third molars. In the case of Europid populations, it has been established that impaction status has an influence on the rate of mineralisation of the third molars. In view of this, a study was undertaken to determine whether the chronological process of wisdom tooth mineralisation is dependent upon impaction status in black Africans too. Orthopantomograms (553) of 437 male and 116 female black South Africans with verified birth dates in the age group between 10 and 26?years were studied. Mineralisation stage and impaction status were determined for all third molars. Statistical measures were calculated for the mandibular wisdom teeth at stages F, G and H and for the maxillary wisdom teeth at stage H in the male gender for both impacted and non-impacted third molars. It was ascertained that the minimum age in persons with impacted third molars, depending on the wisdom tooth observed, was 0.19–2.57?years higher than in those with non-impacted wisdom teeth. Test persons with impacted mandibular wisdom teeth at stage F or G were on average between 0.32 and 1.88?years older than those with non-impacted mandibular wisdom teeth. The 50?% probability values of impacted wisdom teeth at stage H were 1.85–3.31?years higher than those in non-impacted wisdom teeth. The conclusion was drawn that in male black Africans, impacted mandibular wisdom teeth mineralise more slowly than non-impacted lower third molars. The presence of impacted mandibular wisdom teeth in mineralisation stage H in male black Africans does not, however, furnish proof of completion of the 18^th year of life beyond reasonable doubt.     

The influence of impaction to the third molar mineralization in northwestern Chinese population

Age estimation by third molar mineralization has been developed for a period of time. Recent studies showed that impaction status has an influence on the rate of the third molar mineralization in Europids and male Black African populations. In this regard, the present study was conducted to determine whether the impaction status could delay the chronological process of third molar mineralization in northwestern Chinese population too. A total of 3,512 digital orthopantomograms of 1,255 male and 2,257 female northwestern Chinese subjects aged from 11 to 26 years were assessed based on the formation stages described by Demirjian et al. with two modifications. Mineralization stage and impaction status were determined for all third molars. Statistical measures were calculated at stages C–H in the male and female gender for both impacted and non-impacted third molars. It was ascertained that the mean ages with impacted third molars at stages C–H were 0.02–1.42 years higher in males and 0.04–1.52 years higher in females than those with non-impacted third molars, but statistical differences were only found at stages C, D, and E in males and stages D and E in females. The probabilities of being under 14, 16, or 18 years of age with non-impacted third molars were all higher than those with impacted third molars. The results prove that impacted third molars show significant slower mineralization than non-impacted ones at stages D and E in both males and females of northwestern Chinese population. It is recommended to consider the influence of impaction on the rate of third molar mineralization for dental age estimation.     

Studies of the chronological course of wisdom tooth eruption in a German population

Forensic age estimation in living subjects has gained increasing significance in recent years. In dental age estimation, tooth eruption is a parameter of developmental morphology that can be analyzed by either clinical examination or by evaluation of dental X-rays. In the present study, we determined the stage of wisdom tooth eruption in 144 male and 522 female German subjects aged 12-26 years based on radiological evidence from 666 conventional orthopantomograms. The results presented here provide useful data on the age of alveolar, gingival, and complete emergence of the third molars in the occlusal plane that can be utilized for the forensic estimation of the minimum and most probable ages of individuals under investigation.     

Dental age diagnostics by means of radiographical evaluation of the growth stages of lower wisdom teeth

The main criterion for dental age estimation in living adolescents and young adults is mineralization of third molars. A total of 1,260 orthopantomograms of 669 female and 591 male subjects aged between 15 and 22 years was examined. Of the orthopantomograms, 1,137 were from patients with Swiss citizenship and 123 were from other European countries. The mineralization status of lower third molars was evaluated based on Demirjian's classification of stages. For the statistical assessment of data, logistic regression and mean value testing were used. The findings show that completed growth in wisdom teeth is observable at ages less than 18. Male individuals were approximately 1 year ahead of females at stage H, and South East Europeans were approximately 6 months ahead of Swiss (Central Europe) at stage H. Mean values led to false conclusions regarding the question of the attained age of 18. Therefore, regression analysis should be used for the statistical assessment of data in dental age diagnostics.     

Comparative study on the chronology of third molar mineralization in a Japanese and a German population

In Germany, a sharp increase in forensic age estimations of living persons has been observed in recent years. German law defines four legally relevant age limits: 14, 16, 18 and 21 years. In these age groups, radiographic assessment of the mineralization status of third molars is of particular importance. So far, the influence of ethnicity on the mineralization rate has been insufficiently analyzed. A total of 3031 orthopantomograms of 1597 Japanese and 1434 Germans aged between 12 and 26 years were examined. The mineralization status of third molars was evaluated on the basis of the classification proposed by Demirjian. For the individual mineralization stages, the study presents the mean values and standard deviations (SD) separately for both populations and sexes. The majority of probands from both the Japanese and the German population achieved the C stage and the late G and H stages of third molar development at similar ages. Significant differences between Japanese and Germans were observed, however, with regard to the D, E and F stages defined by Demirjian. Japanese men and women achieved the D, E and F stages approximately 2-3 years later than German men and women. In addition to forensic age determination in living persons, the presented reference data can also be used for age estimations of unidentified deceased persons and skeletons.     

Chronological age estimation of third molar mineralization of Han in southern China

In order to study the chronology of age of third molar mineralization of Han in southern China, Demirjian staging method was used to determine the stage of four third molars (18, 28, 38, 48) mineralization in 3,100 Han in southern China aged 4.1–26.9 years based on radiological evidence from digital orthopantomograms. The mean age of the 3,100 patients was 15.96 ± 4.73 years, including 1,200 male (mean age, 15.32 ± 4.62) and 1,900 female (mean age, 16.35 ± 4.76). Results show that there was no significant difference in mineralization between 18 and 28 and 38 and 48 of male or female. However, significant difference was observed between 28 and 38 of female at stage C; 28 was 0.25 years earlier than 38. In male, at stage G, 38 was 0.61 years earlier than 28, and 48 was 0.62 years earlier than 18. At stages D, E, F, G, and H, male 48 was 0.34, 0.66, 0.72, 1.34, and 0.76 years earlier than that of female, respectively. At stages A, D, E, F, G, and H, male 38 was 0.73, 0.26, 0.56, 0.91, 1.29, and 0.70 years earlier than that of female, respectively. At stages B, E, F, G, and H, the mineralization mean age of male 18 was 0.54, 0.50, 0.76, 0.92, and 0.58 years earlier than that of female, respectively. At stages E, F, G, and H, the mineralization mean age of male 28 was 0.51, 0.76, 0.92, and 0.49 years earlier than that of female, respectively. After reviewing the literature, the chronological mineralization age of 48, at stages D to G, of Han in southern China was 1 to 4.6 years earlier than that of Japanese and 1 to 3 years earlier than that of German. The mean age at stage H of 48 of Han in southern China was similar to Turkish, Black African, Japanese, and German, but was later than Spanish. Finally, the conclusions are: (1) in the same gender group of Han in southern China, the mineralization ages between two sides in upper or lower jaw are very similar, and (2) the chronology mean age and complete time of third molar mineralization of male were earlier than that of female.     

Validation of common classification systems for assessing the mineralization of third molars

One major criterion for dental age estimation is the evaluation of third molar mineralization. There are various methods for evaluating tooth mineralization based on classification by stages. The aim of the present work is to assess the validity of the common classification systems. To this end, we analyzed 420 conventional orthopantomograms of German females aged 12–25 years old. The mineralization status of tooth 38 was determined using the stages defined by Gleiser and Hunt, Demirjian et al., Gustafson and Koch, Harris and Nortje and Kullman et al., respectively. Of the methods tested, the most accurate results were obtained with Demirjian et al.s classification system, which performed best not only for observer agreement but also for the correlation between estimated and true age. It is argued that this is due to the fact that Demirjian et al.s classification is based on a sufficient number of stages which are defined independently of speculative estimations of length. This leads to the conclusion that the method devised by Demirjian et al. should be used for evaluating the mineralization of third molars for purposes of forensic age determination.     

Validity of a modified Demirjian system based on an Australian dataset – simple maturity score in age estimation

This pilot study is a validation of a modified Demirjian’s System developed for the Australian population by Blenkin and Evans. The study sample comprised orthopantomographs of 230 individuals aged 2.5 to 14.5 years. Seven right mandibular teeth (excluding the wisdom tooth) were assessed and graded according to the Demirjian’s stages of tooth development. Corresponding modified numeric scores for the stages were summed to form a simple maturity score from which age estimates were derived. The mean difference between the estimated and chronological age for girls was 0.02 years, 95% CI [-0.13, 0.17]. Paired-sample t-test results found this difference not to be statistically significant p = 0.81, <0.05. For boys, the method underestimated the age with a mean difference of –0.24 years 95% CI [–0.4, –0.08]. Paired t-test found this to be significantly different (p = 0.003). This study found that the modified Demirjian’s System of Blenkin and Evans is valid for use in the Australian population.     

Validation of reference data on wisdom tooth mineralization and eruption for forensic age estimation in living persons

Estimation of dental age is an important part of forensic age estimation in living persons. As the quality of the values given in population-specific reference studies has a great impact on the estimation, the aim of this study was to validate reference data for wisdom teeth mineralization and eruption of a German population concerning the diagnosis of the age limit of 18 years in persons with known age. Mineralization and eruption was evaluated in 307 orthopantomograms of Central European subjects aged 17.5–18.5 years. Dental age was estimated using reference data and compared to chronological age. Statistical methods were used to analyze the differences and to propose adjusted reference values. Estimation of dental age relying on mineralization resulted in overestimations of 2 years on average in 76% of the males and 82% of the females. Using eruption, all men and 75% of the women were overestimated by up to 7 years. The differences between estimated and chronological age in both men and women were associated with the mineralization and eruption stage, respectively. The higher the stage, the higher was the risk of overestimation. The mineralization stages up to stage E were associated with underestimations. Using the proposed adjusted reference values resulted in more accurate estimations of dental age. Validation of reference values for dental age estimation showed great overestimations resulting in high error rates with numerous persons being younger than the estimated dental age. Adjustments are proposed which reduce differences between estimated dental age and chronological age.     

Dental age estimation from the developmental stage of the third molars in Iranian population

A sharp increase in forensic age estimation of living persons has been observed in recent years. However, ethnic populations residing in different countries have been insufficiently analyzed. The aim of this study was to achieve a referral database and regression equations for dental age estimation of unaccompanied minors of Iran nationality. A total of 1200 orthopantomograms were collected from original Iran and equally divided in age categories between 10 and 27 years. On the radiographs, the developmental stage of the third molars was scored applying a Demirjian et al. scoring technique. Inter- and intra-observer reliabilities were tested using kappa statistics. Correlation between the scores of all four wisdom maxillary and mandibular third molars teeth and left/right symmetry were evaluated with spearman correlation coefficient. Student’s t-test on asymmetry was performed and regression formulas were calculated. The present database was the first to assemble third molar developmental scores on radiographs of Iran individuals and provided more appropriate dental age estimation of unaccompanied Iran minors. To enhance the accuracy of forensic age estimates based on third molars mineralization, the use of population-specific standards is recommended.     

Forensic age estimation in living subjects: the ethnic factor in wisdom tooth mineralization

Radiological assessment of the mineralization stage of third molars is a major criterion for age estimation of living people involved in criminal proceedings. To date insufficient knowledge has been obtained about how the ethnic origin can influence tooth mineralization. A comparative study of wisdom tooth mineralization was carried out on three population samples: one German, one Japanese and one South African. To this end, 3,652 conventional orthopantomograms were evaluated on the basis of Demirjians stages. The Japanese subjects were on average 1–2 years older than their German counterparts upon reaching stages D–F, whereas the South African subjects were on average 1–2 years younger than the Germans when displaying stages D–G. To enhance the accuracy of forensic age estimates based on wisdom tooth mineralization we recommend the use of population-specific standards.     

The usage of third molars to determine legally relevant age thresholds in Turkey

From a forensic perspective, attaining the ages of 12, 15 and 18 is particularly important with respect to the Turkish Penal Code (TPC). The aim of this study is to obtain data regarding third molar development in the Turkish population for age estimation and to investigate the contribution of third molar development to age estimation in relation to the TPC. The study was applied with panoramic radiography on 379 male and 405 female subjects. The mineralization status of the third molars were evaluated on the basis of Demirjian’s classification system. It was determined that ‘0’ and ‘A’ stages for under-12 years of age, ‘B’ and ‘C’ stages for under-15, ‘D’ stage for under-18, ‘E’ and ‘F’ stages for over-12, ‘G’ stage for over-15 and ‘H’ stage for over-18 were specific stages for both genders. Specific stages that are detected according to the developmental stages of the third molars were not found to be adequately precise for distinguishing legal age thresholds. However, this study shows that matured third molars (reaching H stage) are indicative of an individual’s being over 18 years of age for both genders in Turkey.     

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.

     

Untersuchungen zum zeitlichen Verlauf der Weisheitszahnmineralisation bei einer deutschen Population

In Germany a sharp increase in forensic age estimations of living individuals has been observed in recent years. With regard to the relevant age group, radiological assessment of the mineralization stage of the third molars is of particular importance. However, the influence of ethnicity on the rate of mineralization has been insufficiently analyzed. A total of 1,437 orthopantomograms from 860 female and 577 male Germans aged between 12 and 26 years were examined. The mineralization stage of the third molars was evaluated based on the classification of stages proposed by Demirjian. For the individual mineralization stages, the study presents the means and standard deviations for the genders separately. Statistically significant differences in the chronology of third molar mineralization between maxilla and mandible or between the two sides could not be observed. A comparison between genders did not reveal significant differences either.     

Age estimation of teenagers from Monterrey (Mexico) by the evaluation of dental mineralization after multi-slice helical computed tomography

Current social conditions require more accurate methods to determine the age of people, either living or deceased. The aim of this study was to determine chronological age by measuring the mineralization of third molars. Volunteers (n = 137), aged between 14 and 22 years and of either gender, were recruited from north-eastern Mexico. Sampling was probabilistic and at random. The mineralization stage of third molars was evaluated with the use of multi-slice helical computed tomography and the Mincer-modified Demirjian amended scale. The correlation coefficient, mean difference and linear estimation were determined. There was a linear correlation between age and the mineralization of third molars. Third molars of adults had a degree of mineralization above Demirjian stage F, whereas the third molars of minors had stages between A and F. Hence, a method was obtained to determine the chronological age from the evaluation of dental mineralization of third molars by multi-slice helical tomography. These results are useful as a diagnostic support in forensic dentistry.     

Discrepancy between chronological age and evaluated dental age using the Demirjian system in Western Australian children

The aims of this work were to assess dental age using the Demirjian system and to evaluate the discrepancy between chronological and dental age among children residing in Western Australia. Forty panoramic radiographs of 5- to 11-year-old children taken at the paediatric clinic of a dental hospital in Western Australia were selected. The developmental stage of each left permanent mandibular tooth excluding the third molar was assessed by three trained examiners. Estimated dental age using the Demirjian system was compared with the chronological age of each child. The accuracy of the Demirjian system in this group of children was 42.5%. The difference between chronological age and dental age was significant (t = 4.066, df = 39, p < 0.001). Dental age estimation for Caucasian children had greater accuracy (χ² = 5.013, df = 1, p = 0.025). Gender and orthodontic concerns were not related to the accuracy of the Demirjian system (p ≥ 0.481). The discrepancy between chronological and dental age using the Demirjian system was significant when assessing the Western Australian population although it was more accurate for Caucasian children. The accuracy was similar between subjects with and without orthodontic concerns.     

Investigation into stutter ratio variance

The number of criminal cases involving Turkish juveniles has increased in recent years. To date, there is no method for chronological age estimation according to third-molar mineralization in Western Turkish children and adolescents. The aim of this study was to investigate the mandibular third molar development according to the eight stages (A–H) of the Demirjian method and to compare third-molar development according to gender and age with previous data. The digital orthopantomograms of 1120 white Turkish children (406 boys, mean age 15.17 ± 3.80 years, and 714 girls, mean age 16.83 ± 3.59 years) aged 7 to 22 years, from the Western Anatolia region were retrospectively reviewed. The Turkish population reached stage H at a mean age of 20 years in both genders. Dental mineralization in Western Turkish children was delayed at stages D–G but advanced at stage H compared with that in Turkish children in other regions. Third molar root development can reliably estimate the mean age and age range for a juvenile of unknown chronological age, especially compared with the standard deviation obtained using other techniques for calculating the skeletal age of the hand-wrist or long bones.