Dental age assessment of young Iranian adults using third molars: A multivariate regression study

BackgroundIn recent years, a noticeable increase in forensic age estimations of living individuals has been observed. Radiologic assessment of the mineralisation stage of third molars is of particular importance, with regard to the relevant age group. To attain a referral database and regression equations for dental age estimation of unaccompanied minors in an Iranian population was the goal of this study. Moreover, determination was made concerning the probability of an individual being over the age of 18 in case of full third molar(s) development.Materials and methodsUsing the scoring system of Gleiser and Hunt, modified by Köhler, an investigation of a cross-sectional sample of 1274 orthopantomograms of 885 females and 389 males aged between 15 and 22 years was carried out. Using kappa statistics, intra-observer reliability was tested. With Spearman correlation coefficient, correlation between the scores of all four wisdom teeth, was evaluated. We also carried out the Wilcoxon signed-rank test on asymmetry and calculated the regression formulae.ResultsA strong intra-observer agreement was displayed by the kappa value. No significant difference (p-value for upper and lower jaws were 0.07 and 0.59, respectively) was discovered by Wilcoxon signed-rank test for left and right asymmetry. The developmental stage of upper right and upper left third molars yielded the greatest correlation coefficient. The probability of an individual being over the age of 18 is 95.6% for males and 100.0% for females in case four fully developed third molars are present. Taking into consideration gender, location and number of wisdom teeth, regression formulae were arrived at.ConclusionUse of population-specific standards is recommended as a means of improving the accuracy of forensic age estimates based on third molars mineralisation. To obtain more exact regression formulae, wider age range studies are recommended.     

Development of a Reference Data Set (RDS) for dental age estimation (DAE) and testing of this with a separate Validation Set (VS) in a southern Chinese population

BackgroundMany countries have recently experienced a rapid increase in the demand for forensic age estimates of unaccompanied minors. Hong Kong is a major tourist and business center where there has been an increase in the number of people intercepted with false travel documents. An accurate estimation of age is only possible when a dataset for age estimation that has been derived from the corresponding ethnic population. Thus, the aim of this study was to develop and validate a Reference Data Set (RDS) for dental age estimation for southern Chinese.Materials and methodsA total of 2306 subjects were selected from the patient archives of a large dental hospital and the chronological age for each subject was recorded. This age was assigned to each specific stage of dental development for each tooth to create a RDS. To validate this RDS, a further 484 subjects were randomly chosen from the patient archives and their dental age was assessed based on the scores from the RDS. Dental age was estimated using meta-analysis command corresponding to random effects statistical model. Chronological age (CA) and Dental Age (DA) were compared using the paired t-test.ResultsThe overall difference between the chronological and dental age (CA-DA) was 0.05 years (2.6 weeks) for males and 0.03 years (1.6 weeks) for females. The paired t-test indicated that there was no statistically significant difference between the chronological and dental age (p > 0.05).ConclusionThe validated southern Chinese reference dataset based on dental maturation accurately estimated the chronological age.     

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.     

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 dental age estimation using third molar developmental stages: does a Bayesian approach outperform regression models to discriminate between juveniles and adults?

Dental age estimation methods based on the radiologically detected third molar developmental stages are implemented in forensic age assessments to discriminate between juveniles and adults considering the judgment of young unaccompanied asylum seekers. Accurate and unbiased age estimates combined with appropriate quantified uncertainties are the required properties for accurate forensic reporting. In this study, a subset of 910 individuals uniformly distributed in age between 16 and 22 years was selected from an existing dataset collected by Gunst et al. containing 2,513 panoramic radiographs with known third molar developmental stages of Belgian Caucasian men and women. This subset was randomly split in a training set to develop a classical regression analysis and a Bayesian model for the multivariate distribution of the third molar developmental stages conditional on age and in a test set to assess the performance of both models. The aim of this study was to verify if the Bayesian approach differentiates the age of maturity more precisely and removes the bias, which disadvantages the systematically overestimated young individuals. The Bayesian model offers the discrimination of subjects being older than 18 years more appropriate and produces more meaningful prediction intervals but does not strongly outperform the classical approaches.     

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.     

Dental and skeletal maturation as simultaneous and separate predictors of chronological age in post-pubertal individuals: a preliminary study in assessing the probability of having attained 16 years of age in the living

The goal of this paper is to explore whether combining dental and skeletal maturation data increases the reliability of determining whether an individual is 16 years old or older. This is tentatively done by building probabilistic models for age estimation based on dental and skeletal maturation using a longitudinal sample of eight males, with annual assessments between the ages of 13 and 19, totalling 56 observations. Skeletal maturity was assessed for the radius and ulna using the TW2 method, and dental maturity was assessed for the second and third molars using Demirjian’s scheme. Logistic regression was selected to determine the probability of an individual being 16 years of age and older, by combining dental and skeletal maturity scores and using them separately. The age estimation models combining dental and skeletal maturity scores seem to perform better than either dental or skeletal maturity in isolation. In addition, when in isolation or combination, models based on skeletal maturity scores seem to outperform models based on dental maturity scores. The findings seem to support the notion that dental development is less reliable than skeletal maturity for age estimation in adolescents, but these results have to be confirmed by further studies.     

Radiographic evaluation of Gustafson’s criteria for the purpose of forensic age diagnostics

The main criteria used in dental age estimation in living young individuals are mineralisation and eruption of the third molars. In order to further diversify the spectrum of characteristics after completion of third molar development, tests were undertaken to determine whether the characteristics studied by Gustafson can be ascertained with the required forensic certainty with the aid of the orthopantomogram and whether the evaluation of these could render forensic odontological age diagnoses possible beyond the 18th year of life. For this purpose, 1,299 conventionally produced orthopantomograms of 650 female and 649 male Germans aged from 15 to 40?years were studied. The characteristics of secondary dentin formation, cementum apposition, periodontal recession and attrition were evaluated in all the mandibular premolars. The correlation of the individual characteristics with chronological age was studied with the aid of a multiple regression analysis in which chronological age formed the dependent variable. Depending on the tooth studied, the R values amounted to 0.65 to 0.73; the standard error of estimate was 5.3 to 5.7?years. Basically, the regression equations calculated can be recommended for age estimation in living individuals, although it should be borne in mind that the applicability of the new method presented is limited by the quality of the X-ray images.     

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.     

Age estimation from pulp/tooth area ratio in maxillary incisors among Egyptians using dental radiographic images

Age estimation from dental radiographs is a non-destructive, simple method to obtain information. The aim of this study was to determine the reliability of age estimation from Egyptians' incisors radiographs. 144 periapical radiographs of maxillary (central & lateral) incisors (both sexes) aged 12-60 were used. Digital camera was used to image the radiographs. Images were computed and pulp/tooth area ratios were determined by AutoCAD Program. Data were subjected to correlation and regression analysis which showed statistically significant correlation (r?=?0.23 &P?=?0.006 for maxillary central incisors and r?=?-0.2 &P?=?0.05 for maxillary lateral incisors) between age and pulp tooth area ratio. Linear regression equations were determined separately for both central and lateral incisors along with the corresponding Standard Error of Estimate, which ranged from 1.2 to 5.08 years. Consequently, it was concluded that pulp/tooth area ratios of incisors are reliable for estimation of age among Egyptians in forensic work.     

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.     

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.     

Einfluss der Retention auf die Mineralisationsgeschwindigkeit dritter Molaren

Third molars are of special interest concerning legally relevant age groups in forensic age estimation by means of examination of dental mineralization. This study investigated the influence of wisdom tooth impaction on the mineralization rate. A total of 1,198 orthopantomograms from 629 female and 569 male German individuals (age range 15-40 years) were examined. After assessing the dental mineralization of the third molar in cases with stage H according to Demirjian, wisdom tooth impaction was determined. Females with complete wisdom tooth impaction were 0.7-4.0 years older than those females with incomplete wisdom tooth impaction, in the male group the age difference was 1.6-2.6 years, the lower level for stage H according to Demirjian was between 18 and 20 years in both genders. It was concluded that in German individuals with stage H according to Demirjian it is most likely that these persons have reached a minimum age of 18 years.     

Narrowing of the inferior dental canal in relation to the lower third molars

OBJECTIVES: To assess narrowing of the inferior dental canal in the lower third molar regions using computed tomography (CT) and to determine the value of radiographic markers on rotational panoramic radiographs in assessing the true relationships of the inferior dental canal. METHODS: Patients referred for CT assessment of impacted lower third molars were used in this study. The lower third molars were assessed using CT to determine the position and morphology of the inferior dental canal relative to the roots and the cortical plates. The radiographic markers on rotational panoramic radiographs were correlated with the CT findings when rotational panoramic radiographs were available. RESULTS: The patients referred had 202 lower third molars. Inferior positioning of the inferior dental canal was the most common location on CT. Narrowing of the inferior dental canal was found in relation to the lower third molars in 66.8% of cases. The chance of narrowing of the inferior dental canal as shown using CT increased when at least one of the radiographic markers, superimposition, narrowing, deviation or reduction in density was present on the rotational panoramic radiograph. Deviation of the inferior dental canal on rotational panoramic radiographs was found to be the most significant predictor of narrowing of the inferior dental canal and a close relationship to the roots, as shown in CT. CONCLUSIONS: Narrowing of the inferior dental canal is a common finding when impacted lower third molars are assessed using CT. On rotational panoramic radiographs deviation of the inferior dental canal is the best predictor of narrowing of the inferior dental canal and a close relationship to the roots.     

Application of the Kvaal method for adult dental age estimation using Cone Beam Computed Tomography (CBCT)

Different non-invasive methods have been proposed for dental age estimation in adults, with the Kvaal et al. method as one of the more frequently tested in different populations.The purpose of this study was to apply the Kvaal et al. method for dental age estimation on modern volumetric data from 3D digital systems. To this end, 101 CBCT images from a Malaysian population were used. Fifty-five per cent were female (n = 55), and forty-five percent were male (n = 46), with a median age of 31 years for both sexes. As tomographs allow the observer to obtain a sagittal and coronal view of the teeth, the Kvaal pulp/root width measurements and ratios were calculated in the bucco-lingual and mesio-distal aspects of the tooth. From these data different linear regression models and formulae were built. The most accurate models for estimating age were obtained from a diverse combination of measurements (SEE ±10.58 years), and for the mesio-distal measurements of the central incisor at level A (SEE ±12.84 years). This accuracy, however is outside an acceptable range in for forensic application (SEE ±10.00 years), and is also more time consuming than the original approach based on dental radiographs.     

Dental age estimation among female commercial sex workers in Goa

IntroductionAge estimation is a sub-discipline of the forensic sciences and an important part of every identification process, especially when information relating to the deceased is unavailable.In India, close to 3.5 million women work as commercial sex workers (CSW) of which 1.2 million are under aged.AimTo assess the dental and the skeletal age of rescued female CSWs with an intention of rehabilitation of the minors.MethodologyDental age assessment of 32 rescued female CSWs with unknown age was done based on the radiographic analysis using regression equations derived in a Qualitative and Quantitative study by Dinkar A D. The skeletal age was assessed based on physical and radiological examination of the skeletal bones by Forensic experts.ResultIt was observed that the estimated age of the CSWs ranged from 7 to 22 years out of which 22 cases (68.75%) were found to be below 18 years. When the dental and skeletal age was compared the maximum variation ranged between ±12 months (1 year). Although the CSWs were found to be from different parts of India, maximum number of the cases (50%) was from Andhra Pradesh and one case (3.13%) was from Nepal.ConclusionDental age assessment using qualitative and quantitative method given by Dinkar A D can be thought of a reliable method for dental age assessment as it didn't show much variation when compared to the skeletal age of the 32 CSWs. In the present study 68.75% of the females were minor which shows that the number of minors being trapped in the trade of prostitution is increasing. Rescuing and rehabilitation of these minors is of paramount importance.     

Application of the method of Kvaal et al. to digital orthopantomograms

Estimation of age in individuals has received considerable attention in the forensic literature. The reduction of size of dental pulp cavity as a result of secondary dentin deposit with increasing age could be used as an indicator of age. This regression change, apart from morphological techniques, can also be analysed by radiological techniques. In 1995, Kvaal et al. reported a new method for estimating the chronological age of adults based on the relationship between age and the pulp size on periapical dental radiographs. In 2005, Paewinsky et al. reported specific regression formulae for dental age calculation. The aim of this work was to evaluate the reproducibility of the original method of Kvaal et al. on digital panoramic radiographs as well as to analyse the application of age-estimation formulae reported in the literature. Orthopantomograms (OPGs) of 100 patients aged between 14 and 60 years old from a private radiology department in Bilbao were selected at random. According to the reported technique, three mandibular teeth were evaluated in each orthopantomogram. The results showed that the method reported by Kvaal at al. cannot be applied to direct digital OPGs. The values of age estimation obtained using regression formulae analysed on digital images were so distant from the real ages that this method must be discouraged as being a reliable one to estimate age on a direct digital OPGs sample.     

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.