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.     

Forensic age estimation using the eruption of the second permanent mandibular molar: determining age over 14 years-old

Little is known about the role of the second molar eruption in forensic age estimation; however, in countries where the legal age is 14-years-old, it can provide important information. This study aims to analyse whether the eruption stages of the second mandibular molar can be used for forensic age estimation purposes. The eruption stage of the second left mandibular molar was assessed and correlation between age and stage of eruption was evaluated using Spearman rank order correlation. A Chi-square test was used to assess the correlation between age equal or superior to 14 and stage C or D attainment. The level of significance was defined as p<0.05. Stage C and D attainment and age 14 were significantly related in both sexes (p<0.001). Still, stage 3 was attained by 37% and 44.4% of the males and females younger than 14 years, respectively; stage 4 was attained by 14.8% and 25.6% of the males and females younger than 14 years, respectively. Second molar emergence, particularly stage D, can be used as a dental age indicator. When stage D is attained, particularly in males, there is strong suggestion of age over 14 years. However, other markers should also be used.     

The relevance of body mass index in forensic age assessment of living individuals: an age-adjusted linear regression analysis using multivariable fractional polynomials

In forensic age assessment of living individuals, developmental stages of skeletal maturation and tooth mineralization are examined and compared with a reference population. It is of interest which factors can affect the development of these features. We investigated the effect of body mass index (BMI) on the developmental stages of the medial epiphysis of the clavicle, the distal epiphysis of the radius, the distal epiphysis of the femur, the proximal epiphysis of the tibia, and the left lower third molar in a total of 581 volunteers, 294 females and 287 males aged 12–24 years, using 3 T MRI. BMI values in the cohort ranged from 13.71 kg/m² in a 12-year-old female to 35.15 kg/m² in an 18-year-old female. The effect of BMI on the development of the characteristics was investigated using linear regression models with multivariable fractional polynomials. In the univariable analysis, BMI was associated with all feature systems (beta between 0.10 and 0.44; p < 0.001). When accounting for the physiological increase of BMI with increasing age, the effect of BMI was lower and in the majority of the models no longer clinically relevant. Betas decreased to values between 0.00 and 0.05. When adding feature variables to a model already including age, r² values increased only minimally. For an overall bone ossification score combining all characteristics, the adjusted ß was 0.11 (p = 0.021) and 0.08 (p = 0.23) for females and males, respectively. Low ß and r² values (0.00 (adjusted)–0.16 (crude)) were present in both models for third molar development already in the unadjusted analyses. In conclusion, our study found no to little effect of BMI on osseous development in young adults. Teeth development in both sexes was completely independent of BMI. Therefore, dental methods should be part of every age assessment.

     

Age estimation using third molar maturation based on Demirjian’s criteria

Dental age estimation is routinely used in human identification, in both the living and the dead. Teeth follow a predictable pattern of eruption and maturation that can be assessed radiographically in the living, allowing experts to estimate an individual’s age. Third molars develop much later than the other permanent teeth, and can be used to estimate age of individuals nearing the age of maturity. Ability of third molar maturation when graded using Demirjian’s method in ascertaining whether an individual has attained the medicolegal ages of 16 and 18 years has not yet been verified. The present study involved assessing the third molar maturation of 220 individuals of a training set using Demirjian’s scoring system, generating regression models to estimate age using the third molar maturity scores, applying these models on a test set of 40 individuals, and calculating the mean difference (MD) and the mean absolute error (MAE) between the chronological and estimated ages of the test set participants. It was observed that the lowest mean difference and mean absolute error was observed for the maturation of the left mandibular third molar (MD = 1.05 years, MAE = 2.09 years). Boxplots generated in the study report that the third molar maturation stages given by Demirjian can identify whether an individual has attained the medicolegally significant ages of 16 and 18 years of age.     

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.

     

Above or below 14 years? An orthopantomographic study based on chronological course of eruption of mandibular premolars and second molars in a sample of south Indian children

In the context of dental age assessment, two significant factors can be studied; tooth mineralisation and tooth emergence. Little is known about the role of a second molar eruption in forensic age estimation. This paper aims to contribute to forensic age estimation using an age threshold of 14 years, studying the eruption stages of permanent mandibular premolars and second molars. Totally 640 orthopantomograms (OPGs) of south Indian children, aged between 10 and 18 years, were evaluated using Olze et al. staging of tooth eruption stages (A–D). Spearman's rho correlation showed a strong, positive, and statistically significant correlation between the chronological age and the eruption stages of both sexes' teeth. Accuracy, sensitivity, specificity, likelihood ratios, and post-test probability values were calculated for all tested teeth. The best performance to discriminate individuals above or below 14 years showed stage D in second molars. The sensitivity varied between 89% and 94% and specificity between 75% and 84%, respectively. Receiver operating characteristic curve analysis revealed high diagnostic performance for stage D, with area under the ROC curve (AUC) values of 84% and 85% for tooth 37 and 85% and 83% for tooth 47 in males and females, respectively. In conclusion, it is possible to predict age over 14 years in south Indian children using tooth emergence stages from OPGs with a relatively high interobserver agreement and good diagnostic accuracy. However, there are some limitations and, therefore, must be used in conjunction with other methods.     

Assessment of the radiographic visibility of the periodontal ligament in the lower third molars for the purpose of forensic age estimation in living individuals

The main criterion for dental age estimation in living individuals is the mineralisation of third molars. However, the mineralisation of third molars can be completed before the forensically relevant age of 18 years has been attained. In a material of 1,198 orthopantomograms from 629 females and 569 males aged between 15 and 40 years, the radiographic visibility of the periodontal membrane of fully mineralised third molars was assessed according to stages 0, 1, 2 and 3. Stage 0 first appeared at the age of 17.2 years in females and at the age of 17.6 years in males. Stage 1 was first achieved by females between 18.9 and 20.0 years and by males between 20.1 and 20.2 years. The earliest appearance of stage 2 was between 22.5 and 23.1 years in females and at 22.3 years in males. The occurrence of stage 3 was first found between 24.6 and 25.2 years in females and between 25.4 and 26.2 years in males. If stage 1 is determined, it is, therefore, possible to prove that an individual has already attained the legally relevant age of 18 years. For stages 2 and 3, it can be stated beyond reasonable doubt that a person is over 21 years of age.     

Accuracy of the use of radiographic visibility of root pulp in the mandibular third molar as a maturity marker at age thresholds of 18 and 21

Evaluation of the radiographic visibility of root pulp in mandibular third molars has been suggested as an alternative method for estimation of legal age threshold in living individuals when the root apices are mature. Here, we assessed the accuracy of this method for age thresholds of 18 and 21 years. A sample of 463 panoramic radiographs of individuals aged between 16 and 34 years was examined. The root pulp visibility of the mandibular third molars was scored; the stages ranged from 0 to 3. A receiver operating characteristic (ROC) curve and the area under the ROC curve (AUC) were used to select optimal cut-offs for 18- and 21-year-old thresholds. As prognostic predictors, the selected cut-offs were stages 1 and 2 for the 18- and 21-year-old thresholds of both sexes, respectively. For the 18-year-old threshold, the AUC, sensitivity and specificity were 0.829, 83.1% and 66.7% in females; and 0.930, 89.4% and 90.9% in males, respectively. For the 21-year-old threshold, the AUC, sensitivity and specificity were 0.874, 72.8% and 92.0% in females; and 0.906, 85.5% and 88.2% in males, respectively. The accuracy of the method for estimating the 18- and 21-year-old thresholds ranged from moderate to high. Therefore, the method must be used in conjunction with other age estimation methods, especially to predict whether a female has reached 18 years of age.

     

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.     

Evaluation of the radiographic visibility of the root pulp in the lower third molars for the purpose of forensic age estimation in living individuals

The question of whether an individual has reached the age of 18 is of crucial importance in forensic age estimation practice. In some countries, the age threshold of 21 years is relevant as well. A completed mineralization of third molars is not a sufficient criterion for a diagnosis of a minimum age of 18 years with the required probability. In a material of 1,198 orthopantomograms from 629 females and 569 males aged between 15 and 40 years, the visibility of the root pulp of fully mineralized lower third molars was evaluated according to stages 0, 1, 2, and 3. In females, stage 0 was first noticed at age 17.2 years, in males at age 17.6 years. In either sex, the earliest observation of stage 1 was between 21.0 and 22.4 years. Stage 2 was first achieved by males between 22.3 and 22.7 years, by females between 23.4 and 24.7 years. The occurrence of stage 3 was first found in both sexes between 25.1 and 25.9 years. These findings indicate that for stage 0, an age below 18 years cannot be excluded. However, for stage 1, the examined individual must be over 18 years of age and most probably over 21 years of age. For stages 2 and 3, the age can safely be stated to be over 21 years of age. This method may be a powerful tool for forensic dentists in age estimation in asylum and criminal proceedings.     

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.     

Dental age assessment (DAA): reference data for British children at the 10-year-old threshold

The purpose of this work was to develop a reference dataset for dental age assessment at the 10-year-old threshold. Dental panoramic radiographs of children aged between 9 and 11 years were reused to determine the age of attainment of tooth development stages relevant to the 10-year threshold. These data were used to test the accuracy of the dental age assessment (DAA) on a separate study sample of known chronological age. The study sample comprised 100 radiographs (50 female, 50 male) of known chronological age that did not form part of the reference dataset. For each subject in the study sample, the mathematical procedure used in meta-analysis was applied to all teeth that were still developing. The weighted average of all the developing teeth in a given child was assigned as the dental age for that individual. This was compared to the gold standard of chronological age. Three thousand six hundred sixty-two radiographs comprised the reference sample. The mean difference between the chronological age and dental age estimated for the sample of female subjects was 0.12 years (1.44 months) and for the males was 0.33 years (3.96 months). A method comparison technique was used to evaluate the difference between the chronological age and estimated dental age for each study subject. This showed a good agreement for both females and males. DAA using meta-analysis provides a simple method of estimating the age of subjects of unknown birth date at the 10-year threshold. This is, presently, the most accurate method of age assessment for individuals of unknown date of birth.     

Measurement of open apices in tooth roots in Colombian children as a tool for human identification in asylum and criminal proceedings

Dental age estimation was recognized as an imperative issue in clinical and medico-legal practice. However, very few studies on dental age estimation in children have been published in Colombia. This study evaluated the accuracy of Cameriere's method of measurement of open apices on tooth roots in a sample of 526 digital panoramic radiographs (OPTs) of children (274 boys and 252 girls), aged between 6 and 14 years, from Bogotá, Valle del Cauca, Buga and Villavicencio, in Southwest Colombia. Only first seven permanent lower teeth, except third molar, from the left side of mandible were studied. Difference between dental age and chronological age was evaluated for boys and girls across nine age classes. Intra-class correlation coefficient and Kappa score was used to test intra- and inter-observer agreement error rate. Dental age was overestimated by 0.08 years and standard deviation (±SD) of 0.68 years in boys which was not statistically significant (p = 0.06), while in girls dental age underestimated by −0.25 ± 0.65 years which was statistically significant difference (p < 0.001). The absolute difference between DA and CA or mean prediction error (ME) was 0.57 ± 0.38 years in boys and 0.57 ± 0.41 in girls (p = 0.966) which implies that Cameriere's European formula is similarly accurate in both sexes in this sample of Colombian children.     

Dental development in patients with agenesis

Aim

Recent research concerning tooth development and dental agenesis suggests that specific genes are associated with agenesis, and that these genetic factors could also cause delayed dental development of the remaining teeth. The objective of this study was to evaluate whether dental development of patients with agenesis is delayed, compared to a control group.

Subjects and method

Panoramic radiographs of 1145 patients with dental agenesis were collected (452 males, 693 females) aged 6.2 to 24.8 years. The control group included 2032 panoramic radiographs (977 males, 1055 females) aged 6.0 to 24.4 years. A total of 3177 orthopantomograms were staged according to Demirjian. All left permanent teeth present in the mandible (except third molars) were considered. In order to evaluate the difference between patients with and without agenesis, a developmental score (DS) was calculated. The association between the DS and the number of agenetic teeth was evaluated with a Spearman correlation.

Results

Based on the DS, patients with agenesis have a delayed development compared to patients in the control group (p < 0.0001). Within the agenesis group, there is a weak relation between the number of agenetic teeth and the DS: the higher the number of teeth with agenesis, the lower the DS (p < 0.0001 and p = 0.06 for females and males, respectively).

Conclusion

The obtained results can be an important factor for treatment planning in patients with dental agenesis. Moreover, the presence of agenesis needs to be taken into account when using age estimation methods based on permanent tooth development.

     

A comparison of Demirjian's four dental development methods for forensic age estimation in South Australian sub-adults

The aim of this study was to compare the accuracy of Demirjian's four dental development methods for forensic age assessment in a South Australian population. The sample comprised orthopantomograms (OPGs) of 408 sub-adult individuals (211 male; 197 female) with an age range of 4.9–14.5 years. The OPGs were obtained from various dental schools and clinics in urban Adelaide. The following Demirjian methods were evaluated: the original 7-tooth technique; the revised 7-tooth system; the 4-tooth method; and the alternate 4-tooth approach. The left mandibular teeth in each OPG were assessed and rated according to the eight stages (A–H) defined and illustrated in Demirjian et al.⁵ Differences between chronological and estimated ages were calculated for males and females separately; 95% confidence intervals of mean age differences were calculated and ANOVA used to assess the significance of mean differences.When comparing all four methods there were significant differences overall (and in individual age groups) between mean chronological and estimated age in both sexes. In addition, each method consistently overestimated chronological age. We also demonstrate that the accuracy of the dental age methods evaluated varies in different subsets of an Australian population, a finding that parallels previous research in other global populations. Based on our analyses we conclude that population-specific standards based on dental maturity curves, as opposed to estimated ages, would provide more accurate and statistically robust age estimations.