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.     

Studies on the chronology of third molar mineralization in a Japanese 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, radiologic assessment of the mineralization stage of the third molars is of particular importance. Still, the influence of ethnicity on the pace of mineralization has been insufficiently analyzed. A total of 1615 orthopantomograms of 929 female and 686 male Japanese subjects aged between 12 and 30 years was examined. The mineralization stages of third molars were evaluated on the basis of Demirjian's stages modified in accordance with Mincer's model. For the individual mineralization stages, the study presents the means and standard deviations for the genders separately. No statistically significant differences in the chronology of third molar mineralization between maxilla and mandible and between sides were observed. A comparison between genders largely did not render significant differences either. Apart from forensic age determination in living subjects, the presented reference data can also be used for age estimations of unidentified corpses and skeletons.     

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.     

Evaluation of the effect of impaction on the mineralization of mandibular third molars and forensic age estimation in a sample of south Indian children

Assessment of third molar mineralization is a basic forensic odontological method available for age estimation in children and adolescents. Due to their protracted development into the late adolescence, their development has become the subject of interest and acquired great forensic importance. It is clearly evident in the literature that impaction factor has an influence on the rate of maturation of the third molars. In this regard, the present study was undertaken to test the relationship between impaction and its concomitant effect on the mineralization of the third molar and forensic age estimation. A total of 520 digital orthopantomograms (OPG) of 260 males and 260 females of south Indian origin were assessed retrospectively. Maturation of the third molars (I3M) was assessed using the method of Cameriere et al. (Int J Leg Med 122 (6):493–497, 2008). Impaction status was determined according to the position of lower right and left third molars in relation to the long axis of the second molars. Out of the total sample, 68.1% of lower left third molars and 71.2% of lower right molars were impacted. Statistical measures for I3M were calculated in the males and females for both impacted and non-impacted third molars. It was ascertained that the mean age and I3M values were higher in impacted third molars, indicating the slower rate of maturation than non-impacted ones. The sensitivity and specificity of the test (I3M < 0.08) was 96.2% and 72.4% for non-impacted third molars and 46.2% and 87% for impacted third molars, respectively. Our findings indicate that the cut-off value of I3M < 0.08 resulted in greater number of age misclassifications (false negatives) for impacted molars, highlighting the need for new cut-off value of I3M to meet the legal standards. It was concluded that the mineralization of impacted third molars was slower compared to non-impacted ones in south Indian males and females. Further studies are warranted to validate these findings among a larger and more diverse sample.

     

The applicability of Willems’ and Lee’s dental age estimation methods for Japanese children and the comparison with the Korean population

This study aimed to examine the applicability of Willems’ and Lee’s methods in a Japanese population and to find the differences in teeth development between Japanese and Korean children by comparing the accuracy of their estimated age using the two methods. The developmental status of the lower left permanent teeth in 1,475 orthopantomograms of Japanese children were evaluated based on Demirjian’s criteria, and the ages were estimated using Willems’ and Lee’s methods. The errors in estimated ages were calculated and compared with equivalent Korean population data. The accuracy of both methods for estimating the age of the Japanese population was similar to that in the Korean population except for that of Lee’s method used in Japanese males. The results showed that there might be differences in teeth development between the Japanese and Korean boys. To increase the accuracy of the dental age estimation, the method that is derived from their own population data should be applied in forensic practice.     

Human dental age estimation combining third molar(s) development and tooth morphological age predictors

In the subadult age group, third molar development, as well as age-related morphological tooth information can be observed on panoramic radiographs. The aim of present study was to combine, in subadults, panoramic radiographic data based on developmental stages of third molar(s) and morphological measurements from permanent teeth, in order to evaluate its added age-predicting performances. In the age range between 15 and 23?years, 25 gender-specific radiographs were collected within each age category of 1?year. Third molar development was classified and registered according the 10-point staging and scoring technique proposed by Gleiser and Hunt (1955), modified by K?hler (1994). The Kvaal (1995) measuring technique was applied on the indicated teeth from the individuals’ left side. Linear regression models with age as response and third molar-scored stages as explanatory variables were developed, and morphological measurements from permanent teeth were added. From the models, determination coefficients (R ²) and root-mean-square errors (RMSE) were calculated. Maximal-added age information was reported as a 6?% R2 increase and a 0.10-year decrease of RMSE. Forensic dental age estimations on panoramic radiographic data in the subadult group (15–23?year) should only be based on third molar development.     

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.     

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.     

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.     

Verification of delayed menarche evaluation system based on morphological differences in Korean females

In the present study, delayed menarche in Korean females was individually verified by the interval between age at menarche and the age at the maximum peak velocity (MPV) of height derived by the wavelet interpolation method (WIM). However, an evaluation system for delayed menarche has not been established for Korean females. For this reason, the evaluation system for delayed menarche is derived from regression analysis between age at menarche and age at MPV of height. Health examination records of 400 Korean females in their second year at a high school were reviewed from the first grade of elementary school until the second year of high school (from 1997 to 2008). The longitudinal data of height were obtained from the health examination records. The ages at menarche were researched by questionnaires and interview. Finally, 391 subjects for which data were complete were used for the analysis. Least-squares approximation polynomials of age at menarche for age at MPV of height from the first to the third order were constructed for the evaluation in delayed menarche, and the regression equation of the second order was valid. So the quadratic regression evaluation of age at menarche for age at MPV of height was applied for each subject. The morphological factors of fat-thin body and tall-short height types did not affect evaluative judgements of delayed menarche. However, although no significant difference was seen in the short height type, a small significant difference (p<0.1) was seen with the χ² test in the distribution of the average height type. In any event, constructing a system to evaluate delayed menarche in Korean girls and judging delayed menarche from morphological differences has considerable significance.     

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.     

Radiological age estimation: based on third molar mineralization and eruption in Turkish children and young adults

Radiographic evaluation of mineralization and eruption stages of third molars using dental panoramic radiographies can be an efficient tool for chronological age estimation in both forensic sciences and legal medicine. The third molar tooth is utilized for dental age estimation about the age span of 15–23?years because it represents the only tooth still in development. The aim of this study is to obtain and analyze data regarding third molar development and eruption in Turkish population for dental age estimation. A total of 744 dental panoramic radiographies of 394 female and 350 male subjects aged between 8 and 22?years were examined. Third molar development was determined according to the Nolla classification system, and eruption was assessed relative to the alveolar bone level. Mandibular and maxillary third molars were generally found at similar stages of development on both sides. Nolla stage 6 (completed crown calcification) was reached at around the age of 15 in both maxillary and mandibular third molars in both sexes. Alveolar emergence was at around the age of 16 in males and around age of 17 in females. Although third molars’ eruption shows greater variability than development of third molars, data which were obtained from this study about eruption of these teeth can be supportive to development data for age estimation.     

Human age estimation combining third molar and skeletal development

The wide prediction intervals obtained with age estimation methods based on third molar development could be reduced by combining these dental observations with age-related skeletal information. Therefore, on cephalometric radiographs, the most accurate age-estimating skeletal variable and related registration method were searched and added to a regression model, with age as response and third molar stages as explanatory variable. In a pilot set up on a dataset of 496 (283 M; 213 F) cephalometric radiographs, the techniques of Baccetti et al. (2005) (BA), Seedat et al. (2005) (SE), Caldas et al. (2007) and Rai et al. (2008) (RA) were verified. In the main study, data from 460 (208 F, 224 M) individuals in an age range between 3 and 26 years, for which at the same day an orthopantogram and a cephalogram were taken, were collected. On the orthopantomograms, the left third molar development was registered using the scoring system described by Gleiser and Hunt (1955) and modified by Köhler (1994) (GH). On the cephalograms, cervical vertebrae development was registered according to the BA and SE techniques. A regression model, with age as response and the GH scores as explanatory variable, was fitted to the data. Next, information of BA, SE and BA + SE was, respectively, added to this model. From all obtained models, the determination coefficients and the root mean squared errors were calculated. Inclusion of information from cephalograms based on the BA, as well as the SE, technique improved the amount of explained variance in age acquired from panoramic radiographs using the GH technique with 48%. Inclusion of cephalometric BA + SE information marginally improved the previous result (+1%). The RMSE decreased with 1.93, 1.85 and 2.03 years by adding, respectively, BA, SE and BA + SE information to the GH model. The SE technique allows clinically the fastest and easiest registration of the degree of development of the cervical vertebrae. Therefore, the choice of technique to classify cervical vertebrae development in addition to third molar development is preferably the SE technique.     

The chronological age estimation of third molar mineralization of Han population in southwestern China

The purpose of the study was to estimate the chronology of third molar mineralization in Han population of southwestern China and find its unique characteristics so that it would provide a reference in several legal cases like forensic age estimation. The study used Demirjian's staging method to study 2192 orthopantomograms of 984 male and 1208 female subjects aged between 8 and 25 years. The statistical data was analyzed by Student's t test and ANOVA.The conclusions of the study are: (1) The chronological mineralization age of third molars of Han population in Southwestern China is similar to the Turkish and the Japanese, was earlier than the Austrian and Han of South China, but later than the Spanish. (2) The mineralization timing of the third molars between two sides in maxilla or mandible has no significant differences in the same gender group. (3) There is no significant difference in mineralization of third molars between male and female, except for tooth 48 in Demirjian's stage E. (4) The mineralization of third molar in maxilla is earlier than mandible.     

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.     

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.     

Studies on the chronology of third molar mineralization in First Nations people of Canada

Forensic age estimation of living subjects has become increasingly important in recent years. One main criterion for dental age estimation in the relevant age group is the evaluation of third molar mineralization. In the present study, we determined the stages of third molar mineralization in 347 female and 258 male First Nations people of Canada aged 11 to 29 years based on radiological evidence from 605 conventional orthopantomograms. The results presented here provide useful data on the mineralization stages of third molars that can be used for forensic estimation of the minimum and most probable ages including the range of scatter of investigated persons.     

Evaluation of chronological age based on third molar development in the Spanish population

A cross-sectional study was carried out to assess chronological age estimation based on the stages of third lower molar development, following the eight stages (A–H) method of Demirjian et al. The final sample consisted of 1,054 orthopantomograms from Spanish individuals of known chronological age (range 14–21 years) and gender (462 males and 592 females). Results showed a stronger correlation for males (r²=0.54) than for females (r²=0.45). Root formation occurred earlier in males than females, in stages 5, 6 and 7. The mean difference between chronological and estimated age was –0.10 years (±1.23 SD) for left third molar, and –0.07 years (±1.22 SD) for right third molar, with slight variations regarding sex. Comparative tables are provided regarding medicolegal questions concerning age 18 prediction in the Spanish population, showing that legal age is reached in stage 7 (G) by women and in stage 8 (H) by men. No differences have been observed between sides (p<0.0001). Differences were observed between Spaniards and other previously studied populations. Third molar maturity takes place earlier in the Spanish than French-Canadian, Scandinavian, American, German, Japanese and South African populations and is more similar to US Hispanics in root development.