Demirjian's Stages Research Articles

A quick method of determining the age of 8years old: Based on the first premolars on Eastern Chinese population.

Whether an individual is over 8years old is of great significance in clinical medicine and law. The Demirjian, Willems and Cameriere methods are one of the most widely used methods of dental age estimation, but neither method was suitable in Eastern China. And all of them are time-consuming for clinical work. A new and time-saving method for judging whether an individual is 8years old is yet to be proposed on Eastern Chinese population. The paper proposes a method for judging whether an individual is 8years old based on the relationship between age and the first premolar maturity index (I1PM), which is related to the measurement of the open apices of the first premolar. It is a retrospective study where orthopantomograms of 748 children (356 female and 392male) aged 5-13years were collected and analyzed. Linear regression was used to infer the value of I1PM for eastern China. Furthermore, this method was compared to those based on Demirjian's stages F. A cutoff value of I1PM=0.35 was taken. The sensitivity of this test was 90.0% and specificity was 93.3%. Furthermore, the proportion of individuals with a correct classification was 90.9%. The results of the test showed that Demirjian's stage F performance was lightly better than I1pm<0.35. However, the sensitivity, specificity, and overall accuracy of both are greater than or equal to 90.0%, and the differences are not very significant.

Spontaneous space closure following the extraction of the first permanent mandibular molar.

The aim of this study was to determine the prognostic factors, such as the developmental stage of second permanent molar (SPM), the angulation of SPM, and presence/absence of the third molar associated with the spontaneous space closure after the mandibular first permanent molars (FPM) extraction. A total of 177 mandibular SPMs were evaluated in this cross-sectional study. The prognostic factors determining successful space closure such as SPM developmental stage, SPM angulation, and presence/absence of the third molar were evaluated. The mean age of the patients at the time of extraction of SPM was 9.4 years and post-extraction assessment at the time of the study was 12.7 years. Of the total 177 mandibular SPMs, 36 SPMs (20.3%) were at Demirjian stage D, 63 (35.6%) at stage E, 60 (34%) at stage F, 18 (10.1%) at stage G. 18 SPMs (10.1%) had distal angulation, 23 SPMs (13.0%) had mesial angulation and 136 SPMs (76.9%) had upright angulation. At the time of radiographic assessment, 79.1% of the mandibular quadrants showed evidence of third molar formation. Of the 177 mandibular SPMs, 93 (52.5%) exhibited successful space closure in the mandibular arch. There is no statistical significance between the chronological age and the developmental stage of the mandibular SPM with regard to the successful spontaneous space closure at the time of the dental extraction of FPMs. The presence of the mandibular third molar may be a consideration for spontaneous space closure in the mandibular arch.

Inter-observer agreement in the radiographic interpretation of Demirjian's developmental stages in the mandibular second and third molars - A comparative study.

Background:The developmental stages of the teeth in the radiographs are graded on an ordinal scale. The present study was conducted using 123 digital orthopantomograms from individuals in the age group of 5 to 22 years and to analyze and evaluate the inter-observer agreement in grading the developmental stages of second and third molars. Four observers with different levels of practical experience in age estimation participated in the study. The development stages of both the molars in the lower left quadrant (3rd quadrant) were assigned based on the Demirjian's 10 stage chart. The percentage agreement and Kappa statistics were used to test the agreement between the observers. The data of the observer 1 were used as the standard for the comparison.RESULTS:There was 70.0%–75.6% agreement among the observers in staging second molar and 52%–68.3% for the third molars. There was an excellent agreement (k > 080) between observer 1 and observer 2 and a good agreement (k = 060–0.79) between observer 1 and the other two observers for both the molars. The Fleiss Kappa revealed moderate to a good overall agreement for both the molars (k = 0.51–0.66). The Freidman's test revealed a significant difference in the grading of third molars between all the raters (χ2= 25.02, df 3, P < 0.001) and for the second molar the difference was not significant (χ2= 3.89, df 3, P > 0.05). The stage-wise overall agreement was fair for Stage 3 in the second molar and Stage 9 and Stage 4 in the third molar.Conclusions:In conclusion, proper training in the radiographic interpretation of developmental stages may minimize the errors during the age estimation methods.

Mandibular third molar maturation stage as indicator for the legal adult age in an Egyptian sample.

Determination of the age of majority is of critical importance in forensic and legal practice. This study aimed to assess the mandibular third molar maturation stage in discriminating adults and minors in an Egyptian population sample using two methods: Cameriere's third molar maturity index (I3M) and Demirjian's stage of maturation; further, the I3M cut-off value of < 0.08 for age 18 years and older was tested. The study included 350 digital panoramic radiographs of 14-24 years old participants. The effectiveness of I3M < 0.08 and Demirjian's stages were assessed using sensitivity, specificity, accuracy, post-test probability, positive likelihood ratio, and negative likelihood ratio. Receiver operating characteristic (ROC) curves were constructed to detect the overall effectiveness of I3M and Demirjian's stages to determine adults. I3M < 0.08 showed accuracy, sensitivity, specificity, post-test probability, positive and negative likelihood ratios of 88.65%, 91.74%, 83.67%, 90.6%, 5.62 and 0.10 respectively in males, and 82.76%, 80.16%, 87.04%, 91.03%, 6.18 and 0.23 in females. Stage H showed the best specificity and post-test probability within Demirjian stages; 91.84% and 94.06% in males and 90.74% and 91.84% in females. Both I3M and Demirjian's stage H of the mandibular third molar were useful indicators for discriminating between Egyptian adults and minors. The cut-off value of I3M < 0.0625 in males and I3M < 0.104 in females showed a better discrimination performance than I3M < 0.08 among Egyptians.

Reclassification of Demirjian's mandibular premolars staging for age estimation based on semi-automated segmentation of deep convolutional neural network

Abstract The accuracy of age estimation using radiographic approach is important in forensic application. Despite its inconsistency, Demirjian method has been widely used to estimate age in children and young adults. This study aims to develop a semi-automated segmentation of dental development based on first (P1) and second (P2) permanent mandibular premolars and to correlate the mean age of the novel staging method with Demirjian. A stratified sample of six-hundred-fifty-seven panoramic radiographs was retrospectively collected. All training datasets underwent image segmentation process to form training dataset for the classifier. By implementing the Deep Convolution Neural Network (DCNN), 80% of the dataset was assigned for training and validation while the remaining 20% for testing. Classification performance was measured using confusion matrix. With the maximum number of 10-epochs assigned in DCNN, 92.5% of classification accuracy was obtained. On the tested image, differences between predicted age (PA) of the digital processing and the chronological age (CA) were calculated and expressed in mean error. The PA for P1 is underestimated by 0.17 (95% CI: 0.16-0.51) in male while female is overestimated by 0.22 (95% CI: 0.51-0.07). P2 exhibited better accuracy with an overestimation of 0.02 (95% CI: 0.24-0.20) and 0.03 (95% CI: 0.34-0.27) for male and female, respectively. A new sub-stage of stage D was introduced. The overall performance of the presented classification method to stage premolars development on panoramic radiographs was superior as compared to the original method, and modification of mandibular premolar staging in Demirjian method is established in this study.

Socioeconomic differences in permanent teeth mineralization of Portuguese girls and boys from Porto, Portugal.

Purpose: Socioeconomic differences in dental maturation can be used to examine the impact of environmental factors on dental maturation. The purpose of this study is to assess socioeconomic differences in dental maturation of the seven permanent mandibular teeth (I1-M2). Methods: A total of 2114 panoramic radiographs of Portuguese children, adolescents and young adults were studied. The sample was divided into a high socioeconomic status (SES) (n = 925), and a low SES group (n = 1189). Ages ranged between 5 and 26 years. Demirjian's stages were used to assess the maturation of the seven mandibular teeth on the left side. Median-age of attainment of each stage and each tooth was calculated and compared between groups using binary logistic regression. Results: Low SES girls showed a consistent advancement in dental maturation across the entire dentition. Low SES boys, however, showed more often a delayed maturation relative to their high SES counterparts, but this pattern was not consistent and a clear socioeconomic difference seems to be absent in boys. Conclusions: While this study was not able to further explore the causes of the dental advancement in girls, it is hypothesized that it might be related to a higher prevalence of overweight/obesity, and possibly caries, in low SES girls, compared to the SES difference in prevalence in boys.

Validation of Roberts' method using root canal width patterns as a mandibular maturity marker in determining the 18-year threshold.

The South African Bill of Rights and the Children's Act define a 'child' as a person under the age of 18 years. The age of 18 years is therefore significant for legal purposes in South Africa. The third molar is an important indicator in determining the 18-year threshold. Human biological growth markers are accepted indicators of a subject attaining the age of 18 years. A recent study by Roberts et al. suggested that the relative width of the distal root canals (RCW) of the lower left permanent molars (Fédération Dentaire Internationale notation 36, 37 and 38) as visualised on dental panoramic radiographs can be used as such a growth marker. This study aimed to validate this human biological growth marker in both black and white populations living in South Africa according to Roberts' method. The findings of this validation study were in agreement with this method which showed that individuals with Demirjian stage H left molars and category RCW-C were indeed over the 18-year threshold. Important aspects regarding the rationality and application of Roberts' method are discussed. The authors conclude that this method should not be used in isolation but as an adjunct with other age estimation methods.

Development of the third molar in Chileans: A radiographic study on chronological age

This study aimed to evaluate the ages of attainment of the different stages of third molar development in Chileans. We evaluated of 1236 panoramic radiographs of individuals aged between 13 and 26 years. Demirjian's stages of dental development for the upper and lower third molars were recorded in relation to chronological age, and further statistical analysis was performed. The maxillary third molars reached almost all stages of development earlier than the mandibular third molars in both male and female individuals, but with significant differences in the chronological mean ages only at stages F and H for male individuals, and F, G, and H for females. The third molar tended to mature faster in male than in female individuals, but significant differences were found only at stage H for both the maxilla and mandible, and at stages F and G for the mandible. Comparison between the mean ages of Chileans with the mean ages reported previously in a Caucasian North American population showed that the Chilean sample had an earlier maturation of the third molar in stages D to G, up to 2.52 years. The data obtained in this study might be useful for the identification of modern Chilean human remains with incomplete third molar development.

Forensic age estimation in migrants: Where do we stand?

AbstractMany countries have to respond to an influx of an increased number of refugees and asylum seekers, whose management depends on if they are minors. The age estimation, including forensic opinion, is complex and has serious implications. Several guidelines were published, in particular by The Study Group on Forensic Age Diagnostics of the German Association of Forensic Medicine (Schmeling et al., 2008, 2016). Forensic age estimation must contain, at first, an investigation into the medical history of the individual, to identify diseases or treatments that could interfere with growth. The skeletal development is, along with the dental development, the most important criterion for this estimation. For the skeleton, we use the comparison of hand and wrist radiographs with the atlas of Greulich and Pyle (Greulich, 1959), and the Schmeling's method (Kellinghaus et al., 2010) with a CT‐scan of the medial extremity of the clavicle, defining stages, and substages of ossification according to Kellinghaus et al. Dental imaging allows an evaluation of the stage of development of the crown and root, using Demirjian's stages (Demirjian et al., 1973). These methods are minimally irradiating, which is essential as they are used for a nonmedical goal. We know that, even using multiple methods, it is impossible to define a precise age, due to variability among the individuals and their respective origins. The results have to be expressed as minimum age, and the mean age with standard deviations. The majority and the claimed age have to be addressed. It is necessary to have a multidisciplinary evaluation carried out by qualified individuals.This article is categorized under: Forensic Anthropology &gt; Age Assessment

A new model of classification of third molars development and its correlation with chronological age in a Brazilian subpopulation.

The present study correlated the mineralization of third molars to chronological age using a modified classification based on Demirjian's stages in a Brazilian subpopulation and compared with the original classification. A total of 1082 patients with age ranging from 6 to 26years were included in the sample, with at least one third molar on panoramic radiographs. The third molars were classified according to the original Demirjian classification (8 stages) and a new model based on the Demirjian method, where the original stages were grouped into four stages: AB-enamel mineralization; CD-crown dentin mineralization; EFG-root formation; and H-complete development. Statistical analyses were performed by Kruskal-Wallis/Dunn tests (α = 0.05) and the multinomial logistic regression model. Data were analyzed according to percentiles for the probability of an individual being over 18years old. The mean ages of the stages in both classifications did not present a significant difference between superior and inferior arches (p < 0.05). The differences in mean ages between all the stages of mineralization were statistically significant (p < 0.001) only for the 4-stage classification. Males attained root formation and complete formation earlier than females (p < 0.05) in the 4-stage classification. The modified classification system showed dependence between chronological age and mineralization stages of third molars, simplifying the age estimation process. At stage H, females present a 95.7% chance of being over 18, while for males, this probability is 89.6%. This modified classification system simplifies the dental age estimation process based on third molars and can be used as a reference for future studies.

Correlations among chronological age, cervical vertebral maturation index, and Demirjian developmental stage of the maxillary and mandibular canines and second molars.

Estimation of growth spurt from chronological age or dental development is of clinical interest to orthodontists. Since results in this regard are highly controversial and limited, this study was conducted to investigate associations among chronological age, skeletal development (cervical vertebral maturity [CVM]), and dental calcification (Demirjian) in girls and boys, independently. Panoramic radiographs and lateral cephalographs of 112 boys and 112 girls were evaluated. Demirjian stages of dental development of the bimaxillary canines and second molars were determined. CVM stages of skeletal growth were as well estimated. Correlations among these were assessed. Differences between sexes and between maxilla/mandible arches were assessed. Cutoff points in Demirjian and chronological age reflecting skeletal growth spurt were found using receiver operator characteristic curve (α = 0.05, β = 0.9 separately for girls and boys). Sex dimorphism existed both in CVM index and in Demirjian indexes. Compared to dental development and calcification, chronological age was the best predictor of skeletal growth and maturation. In estimating chronological age by radiography means, in girls, Demirjian method was better than CVM. In boys, Demirjian was better than CVM in the case of the molars but not canines. The cutoff points estimated for chronological age and dental calcification that can reflect skeletal growth spurt (between CS-3-and-CS-4) were as follows: in boys, age of 12years; in girls, age between 11 and 12years; the upper and lower canines: between G and H; the maxillary and mandibular second molars: between F and G; in the case of all teeth: between F and G.

Radiographic analysis of dental maturation in children with amelogenesis imperfecta: A case-control study.

To assess dental maturation in children with amelogenesis imperfecta (AI) and compare their estimated dental age with the age of non-AI children. Panoramic radiographs of children with (n=27) and without (n=54) AI were retrospectively collected in the ratio of 1:2. The former consisted of case group, while the latter figured as control group. Both groups were paired by sex and age (P>.05). Dental maturation was assessed in each radiograph using Demirjian's staging technique and Willems' method. Intra- and interexaminer reproducibility reached>0.8. The mean estimated dental age in subjects with AI was 12.5 ± 2.69 years, while in subjects without AI it was 11.73 ± 2.48 years (P=.21). The comparison of mean chronological (12.26 ± 2.6 years) and estimated dental age (12.5 ± 2.69 years) in subjects with AI did not reveal statistically significant differences (P=.38). This study highlights the similarity of dental maturation between subjects with and without AI from the radiographic perspective of crown-root formation.

Third molar development by Demirjian's stages and age estimation among Brazilians

Abstract Objective: To correlate the stages of 3M mineralization with the chronological age of South Brazilians and assess the prevalence of complete mineralization in the threshold of 18 years old (age of legal majority). Study Design: The sample consisted of 1,013 panoramic radiographs from South Brazilian subjects aged between 15 and 23 years old. Demirjian's Tooth Development Stages (1973) was applied to classify the 3M mineralization into 8 stages (from A to H). Results: Stages D, E, F and G were more associated with subjects aged under 18 years old, while stage H was associated with subjects older than 18 years old. A smaller part of the sample ageing 18 years old or above it, was found to be on stages D to G (9.1% and 16.9% for upper and lower 3M, respectively). Considering exclusively stage H, the probability of someone being above 18 years old is 96.4% for upper 3M for male and 88,2% for female, and for lower 3M, 95,1% and 78,4%, respectively. Males presented an earlier development of this dental element, but at stage H, this age difference was significant only for the lower arch (p=0.018). Conclusion: Demirjian's Tooth Development Stages can be a useful tool to assess 3M mineralization for age estimation. When analyzing the stage H, the probability of the individuals were above 18 years old is high, both male and female, in upper 3M or lower 3M. This sample has shown future studies should consider the influence of ethnic and genetic factors over 3M development.

Mandibular Canine Calcification Stages as an Indicator of Skeletal Maturity.

ABSTRACTAims:The aim of this study was to verify whether there is significant relationship between stages of mandibular canine calcification and skeletal maturation and to determine whether the same can be used as a reliable diagnostic aid to assess skeletal maturity.Materials and Methods:The sample consisted of 50 males and 50 females aged between 8 and 15 years. Two radiographs namely orthopantomograph and handwrist radiograph were taken for this study. Skeletal age was ascertained from handwrist radiographs according to the method introduced by Fishman L.S. The developmental stages of mandibular canine were assessed according to Demirjian’s stages of dental calcification.Results:The relationship between canine stage calcification and skeletal maturity index was statistically significant in all stages.Interpretation and Conclusion:Mandibular canine calcification stages can be recommended as a supplemental diagnostic aid. Similar studies may be conducted in different population to rule out any possible racial and regional influences on growth characteristics.

Prediction of agenesis of the maxillary second premolar based on the developmental stages of the maxillary canine, first premolar, and second molar

ObjectiveThis study aimed to suggest criteria for the early diagnosis of agenesis of the maxillary second premolars (U5) based on the developmental stages of the maxillary canines (U3), first premolars (U4), and second molars (U7). DesignOverall, 303 control patients and 72 patients with agenesis who met the inclusion criteria were analyzed among 5136 patients aged 5–11 years for whom panoramic radiographs were obtained at Seoul National University Dental Hospital from June 2008 to December 2009. All developmental stages of U3, U4, U5, and U7 in both groups were evaluated and categorized into the stages proposed by Demirjian et al. To confirm the delayed dental development in the agenesis group, the Wilcoxon rank sum test was used. For verifying the tooth with the most similar developmental pattern to U5, the Kendall tau Rank Correlation and Bootstrap methods were used. Moreover, survival analysis and leave-one-out-cross-validation were performed to identify the earliest developmental stages of U3, U4, and U7 at which agenesis of U5 can be confirmed. ResultsThe developmental stage of U4 in the agenesis group was significantly delayed compared with that in the control group at ages 5–10. All of the stages of U3, U4, and U7 showed high correlation coefficients with U5. ConclusionU5 agenesis can be confirmed with high prediction accuracy when at least two of the three conditions are satisfied: U3, U4, and U7 in Demirjian stages E, D, and C, respectively.

Comparison of three methods to estimate dental age in children.

In 1973, Demirjian and colleagues introduced a staging for tooth mineralization. Staging of the teeth of the left mandible generates a dental maturity score and an estimate of dental age. An update of this method was published in 2001 by Willems and colleagues. The London Atlas (2008) is another method used to assess dental age. This study compared the precision of these three methods for forensic age estimation. A total of 500 panoramic images of 251 boys and 249 girls aged 6-16years had dental maturity evaluated by the same observer using the London Atlas and the methods of Demirjian and Willems. Individuals with syndromes potentially affecting dental maturation were excluded. The three methods were compared with respect to their precision in estimating chronological age. Age estimates using Willems' method were significantly more precise than those obtained using Demirjian's method, while estimates obtained using the London Atlas method were comparable with both the others. The highest precision was obtained using the average of age estimates from Willems' method and the London Atlas. To estimate age in individuals suspected of being below 16years of age, we suggest first applying the London Atlas then computing age from the Demirjian stages of particular teeth using Willems' method, and finally using the average age estimate of both methods. Combining the London Atlas and Willems' scoring method provides more precise estimates of dental age than the current practice of applying a single preferred method.

Extracción oportuna de los primeros molares permanentes severamente afectados en dentición mixta

The aim of this study was to establish a guide for general dentists that allow identifying the ideal moment to extract the first permanent molars with poor prognosis, in the hope of obtaining a spontaneous closure of space, regarding that the first permanent molar is more susceptible to develop dental caries in children due to its early eruption in the oral cavity and molar incisor hypomineralization affects them the most. Methods: we proceed to search for the articles in databases PUBMED and SciELO, selected articles published from 1998 a 2018 were analyzed based on inclusion and exclusion criteria. Conclusion: Our review suggests that a full evaluation of the compromised first permanent molar should be performed before planning an extraction. It can be concluded that the ideal stage to extract a first permanent molar with bad prognosis is in the Demirjian stage E or D evaluated with radiographs, which is generated at a chronological age of 8 to 10.5 years, ideally in the presence of third molars

Correlation of Cervical Vertebral Bone Age and Demirjian&amp;#39;s Stages of Dental Maturation for Lower Left Permanent Canine and Second Molar

To evaluate and correlate cervical vertebral bone age(CVBA) and Demirjian's stages of dental maturation for lower left permanent canine(CMS) and second molar (MMS). A cross-sectional radiographic study was conducted on 264 participants with age group of 7-18 years who were further categorized into six subgroups having an interval of 2 years chronologic age. The CVBA, CMS, and MMS were assessed for the same patient. The assessment of CVBA of the participants involved in the study was derived from the equation given by Mito et al. The height and width of the 3rd and 4th cervical vertebra was measured with the help of IC measure software. The dental maturation was assessed as per the morphologic classification method given by Demirijian. Analysis of variance (ANOVA), Tukey's multiple comparisons and Spearman's correlation coefficient was utilized to determine the significance and correlation between the age groups, CVBA, CMS, and MMS. The multiple comparison levels were set at 0.05 level of significance. Significantly different CVBA was observed among each individual stage of CMS and MMS. Significant changes in the dimensions of the cervical vertebra were observed when the dental maturation stage progressed from F to G and G to H stage. Chronologic age had a moderate correlation with CVBA. CVBA was significant for all the stages of maturation of CMS and MMS. Females revealed a higher level of maturation. A significant difference in the vertebral bone age was observed in the transition of stage F to G and G to H of dental maturation of canine and molar. Both CMS and MMS revealed a significant strong positive correlation with CVBA. Cervical vertebral bone age can be utilized as an adjunct in identifying the stages of dental maturation of lower left permanent canine and second molar.

Age estimation and comparison by dental and skeletal maturity in the age range of 9-18 years in the Mumbai region.

Background:Age estimation is crucial in the identification of juveniles in conflicts with law, survivor of sexual assault, sportsperson, and civil cases.Aims:To estimate and compare the age (9–18 years) by dental and skeletal maturity in the Mumbai region.Settings and Design:This was a cross-sectional study.Materials and Methods:A total of 70 cases from 9 to 18 years of age were studied in 1 year in the urban population of the Mumbai region. Among 70 cases, 45 were males and 25 were females. Orthopantomogram and elbow joint radiographs were taken to assess the dental age through modified Demirjian's method and the radiological age through Sangma et al. staging method, respectively.Statistical Analysis:Data were analyzed using SPSS Statistics Version 26; descriptive statistics and regression statistics were used in the study.Results:Dental age by Demirjian's method in males with standard deviation was 15.25 (2.17), with a mean difference of 1.08 and significant P = 0.03. However, in females, dental age by Demirjian's method with standard deviation was 14.30 (1.94) with a mean difference of 0.74 and insignificant P = 0.07. Interclass correlation coefficient of dental age with chronological age, in males and females, showed 0.85 and 0.87 correlation, respectively. Correlation between the skeletal maturity and the dental age was reflected by the association of Demirjian stage 9 in the second molar with radiological stage 5 in males and stage 4 in females.Conclusions:It was concluded that Demirjian's method shows a significant correlation and P value for the age estimation in males of the Mumbai region.

Age assessment by Demirjian's development stages of the third molar: a systematic review.

Radiographic evaluation of the wisdom teeth (third molar) formation is a widely used age assessment method for adolescents and young adults. This systematic review examines evidence on the agreement between Demirjian's development stages of the third molar and chronological age. We searched four databases up until May 2016 for studies reporting Demirjian's stages of third molar and confirmed chronological age of healthy individuals aged 10-25years. Heterogeneity test of the included studies was performed. We included 21 studies from all continents except Australia, all published after 2005. The mean chronological age for Demirjian's stages varied considerably between studies. The results from most studies were affected by age mimicry bias. Only a few of the studies based their results on an unbiased age structure, which we argue as important to provide an adequate description of the method's ability to estimate age. Observed study variation in the timing of Demirjian's development stages for third molars has often been interpreted as differences between populations and ethnicities. However, we consider age mimicry to be a dominant bias in these studies. Hence, the scientific evidence is insufficient to conclude whether such differences exist. • There is significant heterogeneity between studies evaluating age assessment by Demirjian's third molar development. • Most of the studies were subject to the selection bias age mimicry which can be a source of heterogeneity. • Presence of age mimicry bias makes it impossible to compare and combine results. These biased studies should not be applied as reference studies for age assessment.