Chronology of mineralization of the permanent mandibular second molar teeth and forensic age estimation

Development of a microRNA-Based age estimation model using whole-blood microRNA expression profiling

Age estimation is a critical aspect of human identification. Traditional methods, reliant on morphological examinations, are often suitable for living subjects. However, there are relatively few studies on age estimation based on biological samples, such as blood. Recent advancements have concentrated on DNA methylation for forensic age prediction. However, to explore further possibilities, this study investigated microRNAs (miRNAs) as alternative molecular markers for age estimation. Peripheral blood samples from 127 healthy individuals were analyzed for miRNA expression using small RNA sequencing. Lasso regression selected 103 candidate miRNAs, and Shapley additive explanations (SHAP) analysis identified 38 key miRNAs significant for age prediction. Five machine learning models were developed, with the elastic net model achieving the best performance (MAE of 4.08 years) on the testing set, surpassing current miRNA age estimation results. Additionally, we observed significant changes in the expression levels of miRNAs in healthy individuals aged 48-52 years. This study demonstrated the potential of blood miRNA biomarkers in age prediction and provides a set of miRNA markers for developing more accurate age prediction methods.

Radio-morphologic assessment of dental formation leading to permanent teeth and third molar age estimation models

Understanding dental development within populations is essential for clinical and forensic applications, particularly for age estimation in children and adolescents. This study aimed: I) to evaluate the chronology of dental development, eruption, and exfoliation by means of radiographic analysis and II) to propose dental age estimation models based on the development of permanent teeth and third molars. The sample consisted of panoramic radiographs of individuals between 6 and 22.9years. Radiographs were analyzed for deciduous and permanent teeth, including third molars, using established staging systems for development, eruption, and exfoliation. Dental age estimation models were developed for permanent teeth and third molars, separately, using staging techniques. The models demonstrated high accuracy, with coefficients of determination (r2) of 0.94 for maxillary teeth, 0.95 for mandibular teeth, and 0.93 for third molars. The mean absolute errors (MAE) were approximately 0.6years for permanent teeth and 0.93years for third molars. This study contributes to the field of dental age estimation providing frameworks for evaluating subadults in contexts requiring legal or anthropological assessments. Future research should aim to test and validate these models in independent populations.

Evaluating the accuracy of root transparency and periodontosis age estimation models in a Portuguese population

This study aims to evaluate the accuracy of existing dental age estimation models, including the Lamendin, Prince & Ubelaker, Fialho, and modified Fialho methods, within a Portuguese population. Dental techniques, particularly those involving root transparency and periodontosis, are examined due to their relevance in forensic age estimation. A sample of 166 single-rooted teeth from individuals aged 30 to 86 was analyzed. Measurements included root transparency, periodontosis, and tooth and root length. Statistical methods were applied to assess the reliability and accuracy of each model in estimating age, considering the potential influence of environmental and lifestyle factors on dental aging. Root transparency emerged as a robust age indicator, consistently correlating with chronological age. In contrast, periodontosis introduced variability due to external influences, reducing its reliability. The modified Fialho model, which focuses solely on root transparency, showed the highest accuracy, suggesting that eliminating periodontosis from the estimation process may enhance reliability in populations where environmental factors heavily affect dental aging. The findings underscore the importance of population-specific adjustments in dental age estimation models. By refining methods like the modified Fialho model, forensic investigations can achieve more accurate results, particularly in populations where external factors influence periodontosis.

Radiographic Evidence of Dental Complications after Mandibular Distraction Osteogenesis: Inverted-L versus Oblique Osteotomy

BACKGROUND

Patients with micrognathia undergoing mandibular distraction osteogenesis (MDO) for functional and aesthetic improvement are at significant risk for dental complications. The authors investigated the association of 2 osteotomy patterns-oblique and inverted-L-with risk to developing dentition.

METHODS

A senior orthodontist (H.D.N.) performed a retrospective review of dental radiographs of patients undergoing MDO with confirmed oblique or inverted-L osteotomies between 2012 and 2022. Images were assessed for evidence of missing, damaged, or displaced teeth, and proportion of affected hemimandibles by injury type and median number of affected teeth per hemimandible were compared between groups using appropriate statistical methodology.

RESULTS

Analysis included 44 patients (23 oblique, 21 inverted-L) and 85 hemimandibles (45 oblique, 40 inverted-L). Mean age at surgery was 3.1 ± 4.6 years, and mean time to imaging was 4.9 ± 4.1 years; there was no difference between groups ( P = 0.23, P = 0.34, respectively). Oblique osteotomy was associated with greater odds of missing teeth (odds ratio [OR], 13.3, P < 0.001), damaged teeth (OR, 3.2; P = 0.02), and any dental injury (OR, 39.9; P < 0.001) compared with inverted-L, as well as greater number of missing teeth (β = 0.6; P < 0.01), damaged teeth (β = 0.3; P = 0.02), and total number of affected teeth (β = 0.9; P < 0.001). There was no difference in incidence ( P = 0.5) or number ( P = 0.4) of displaced teeth between groups.

CONCLUSIONS

Inverted-L osteotomies were associated with fewer dental complications compared with oblique osteotomy at all ages studied. Although longer-term follow-up and prospective data are needed before definitive recommendations can be made, these data are helpful to surgeons as they plan MDO.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Does third molar agenesis influence the second lower molar mineralization?

Different studies have established that the mineralization stages of the second mandibular molar can be used in forensic age estimation. Nowadays, the estimate's accuracy is an ethical concern, producing as few false positives (individuals incorrectly classified as older than a determined threshold) and false negatives (individuals incorrectly classified as younger than a determined threshold) as possible. Some have hypothesized that changes in teeth number may influence tooth mineralization, altering the age estimate process. This paper analyzes whether third molar agenesis affects the second mandibular molar mineralization time frame. To do so, 355 orthopantomograms were evaluated for third molar agenesis, and the second mandibular molar mineralization stage was assessed using the Demirjian stages. Student's t-test was used to compare the difference in the mean age at which the various stages of 37 mineralization were reached in the groups with and without third molar agenesis. The level of statistical significance was set at 5%. The results pointed to a delay in second mandibular molar mineralization in the case of agenesis, suggesting the need to consider this when estimating age using dental techniques.

Evaluation of radiographic visibility of root pulp in mandibular second molars using cone beam computed tomography images for age estimation

The purpose of this study is to estimate chronological age and determine whether individuals were aged under or over 18 years using root pulp visibility (RPV) in cone-beam computed tomography (CBCT) images. The study included CBCT images of 699 individuals aged between 15 and 75 years. One thousand twenty-three mandibular second molar (2M) teeth were evaluated using Olze's RPV method in four stages. Descriptive statistics of the stages and the relationship between the stages and the chronological age were assessed. The distribution of the stages was analyzed according to the 18-year age threshold. There was a positive correlation between RPV stages and chronological ages in both sexes. For females and males, the mean ages of stage 0, stage 1, and stage 2, for females and males, were found as 27.21, 28.93, and 33.68 years, and 37.69, 40.9, and 44.88 years, respectively. Stage 0 and stage 1 were found both in individuals aged under and over 18 years, and stage 2 and stage 3 were not observed in individuals aged under 18 years. The presence of stage 2 and stage 3 may be an indication that an individual is aged over 18 years according to Olze's RPV age estimation method. For more reliable results, 2M teeth should be examined bilaterally in forensic science.

Age Assessment through Root Lengths of Mandibular Second and Third Permanent Molars Using Machine Learning and Artificial Neural Networks

The present study explores the efficacy of Machine Learning and Artificial Neural Networks in age assessment using the root length of the second and third molar teeth. A dataset of 1000 panoramic radiographs with intact second and third molars ranging from 12 to 25 years was archived. The length of the mesial and distal roots was measured using ImageJ software. The dataset was classified in three ways based on the age distribution: 2-Class, 3-Class, and 5-Class. We used Support Vector Machine (SVM), Random Forest (RF), and Logistic Regression models to train, test, and analyze the root length measurements. The mesial root of the third molar on the right side was a good predictor of age. The SVM showed the highest accuracy of 86.4% for 2-class, 66% for 3-class, and 42.8% for 5-Class. The RF showed the highest accuracy of 47.6% for 5-Class. Overall the present study demonstrated that the Deep Learning model (fully connected model) performed better than the Machine Learning models, and the mesial root length of the right third molar was a good predictor of age. Additionally, a combination of different root lengths could be informative while building a Machine Learning model.

Application of the ratio of the radiopaque calcified area to the dental follicle (RCA/DF) for dental age assessment on orthopantomograms

OBJECTIVES

This study aimed at exploring a new tooth development evaluation method for age assessment and investigating the dynamic alteration and potential trend of tooth development by orthopantomograms (OPGs), in order to provide references for tooth development prediction and forensic purpose.

MATERIALS AND METHODS

A total of 132 OPGs of children aged 3-8 years were collected. The developmental stages of the permanent mandibular second molar (M2)were evaluated by experienced examiners according to the Nolla method and Mimics software, respectively. Quantitative analysis of the ratio of the radiopaque calcified area to the dental follicle (RCA/DF) in different stages, ages, sexes and quadrants were evaluated and compared via descriptive statistics and Spearman's correlation coefficient analysis.

RESULTS

There was a strong, positive correlation between the examiners' evaluation and mimics analysis results. With the age increased, the Nolla stage of M2 observed by OPGs increased, and the RCA/DF showed increased trends both in males and females. There were significant differences of the RCA/DF of the M2 at various ages. The tooth calcification development of female was 9.08% earlier than that of male between 3 and 8 years old. However, teeth of male seemed to develop faster than that of female during this period. There was no significant difference between left and right quadrant either according to the Nolla stage or RCA/DF.

CONCLUSIONS

The RCA/DF value obtained from OPGs of the developmental mandibular second permanent molars could be used as a reliable indicator for tooth maturity and age estimation in children aged 3-8 years.

CLINICAL RELEVANCE

Age assessment based on radiographs is considered as a reliable and efficient indicator for judging different types of malocclusion, making suitable orthodontic treatment plan, deciding the extraction time of retained deciduous teeth in clinic practice.

Testing international techniques for the radiographic assessment of third molar maturation

BACKGROUND

To assess the radiographic third molar maturation with internationally developed techniques for age estimation.

MATERIAL AND METHODS

The study analyzed 1,062 panoramic radiographs of patients treated at the School of Dentistry of the University of Passo Fundo/RS/Brazil, between 2009 and 2020. The patients were separated into ages between 15.00 and 23.99 years and, for each radiograph, the third molars were classified into stages from 1 to 10, with the subsequent application of one of the formulae proposed by Gunst et al. A dichotomous variable indicating whether each individual was younger or older than 18 was calculated from the chronological age of the individuals. A logistic regression model was adjusted to assess whether the third molar stages are correlated with the age of individuals.

RESULTS

The error indicators between estimated and chronological ages showed that mean errors closer to zero are seen in the 18-18.9 and 17-17.9 age groups, respectively. Male individuals were earlier in terms of dental mineralization but there were no significant differences between sexes regarding the applicability of the method. The ROC curve shows that the analysis of a single third molar for age estimation gives a maximum of 70.4% reliability.

CONCLUSIONS

The moderate performance of the technique tested in the present study justify future country-specific corrections to improve age estimation from the radiographic assessment of third molar maturity. Key words:Dental age estimation, forensic dentistry, radiology, third molar.

Dental maturation in a Chinese sample using Demirjian method

BACKGROUND

Dental calcification information is relevant for clinical, archaeological, and forensic applications. However, dental maturity measurements in current cohorts of Chinese children are insufficient.

AIM

This study aimed to establish the mandibular dental maturity table and determine the accuracy of dental age estimation using the Demirjian method in a Chinese sample.

SUBJECTS AND METHODS

Permanent mandibular teeth, excluding the third molar, in 2091 panoramic radiographs of 1008 males and 1083 females aged 3-15 were graded, and dental age was estimated according to Demirjian's criteria. Age-of-attainment was calculated with probit regression for each stage by sex, and sex differences were analysed using the Mann-Whitney U test. Dental age was compared with chronological age using paired t-tests.

RESULTS

Although females showed earlier age-of-attainment than males, significant sex differences were only found in stages D-G (p < 0.05). The Demirjian method overestimated the dental age in both males (0.68 ± 1.05 years) and females (0.59 ± 0.97 years).

CONCLUSIONS

The relationship between mineralisation stage and chronological age in this study can be applied as a reference for mandibular dental maturity of Chinese children and adolescents. The Demirjian method overestimated the chronological ages of this sample.

Application of Cameriere's method for dental age estimation in children in South China

The aim of this study was to evaluate the applicability of Cameriere’s European formula for age estimation in children in South China and to adapt the formula to establish a more suitable formula for these children. Moreover, the performance of dental age estimation based on Cameriere’s method combining the developmental information of permanent teeth (PT) and third molar (TM) was also analysed. Orthopantomographs of 720 healthy children in Group A, and orthopantomographs of 320 children and 280 subadults in Group B were assessed. The samples of Group A were divided into training dataset 1 and test dataset 1, and the samples of Group B were also divided into training dataset 2 and test dataset 2. A South China-specific formula was established based on the training dataset 1, and the comparison of accuracy between the Cameriere’s European formula and the South China-specific formula was conducted with the test dataset 1. Additionally, a PT regression model, a TM regression model, and a combined regression model (PT + TM) were established based on the training dataset 2, and the performance of these three models were validated on the test dataset 2. The Cameriere’s European formula underestimated chronological age with a mean difference (ME) of −0.47 ± 1.11 years in males and −0.69 ± 1.19 years in females. However, the South China-specific formula underestimated chronological age, with a mean difference (ME) of −0.02 ± 0.71 years in males and −0.14 ± 0.73 years in females. Compared with PT model and TM model, the PT and TM combined model obtained the smallest root mean square error (RMSE) of 1.29 years in males and 0.93 years in females. In conclusion, the South China-specific formula was more suitable for assessing the dental age of children in South China, and the PT and TM combined model can improve the accuracy of dental age estimation in children.

Key points

Orthopantomographs of 720 healthy children in Group A, and orthopantomographs of 320 children and 280 subadults in Group B were assessed.

A South China-specific formula was established based on the training dataset 1, and the comparison of accuracy between the Cameriere’s European formula and the South China-specific formula was conducted with the test dataset 1.

A PT regression model, a TM regression model, and a combined regression model (PT + TM) were established based on the training dataset 2, and the performance of these three models were validated on the test dataset 2.

The South China-specific formula was more suitable for assessing the dental age of children in South China, and the PT and TM combined model can improve the accuracy of dental age estimation in children.

Measurement of the open apices of mandibular first and second premolars to test the chronological age over 14 years: Study on a sample of south Indian children

Age estimation is an integral part of forensic medical and dental practice. In many countries, the age threshold of 14 years is set to determine the minimum age for criminal responsibility. In the present study, the authors studied the final maturation of the first (IPM₁) and second mandibular premolars (IPM₂) by Cameriere maturity index and determined cut-offs at the age threshold of 14 years, and validate on the test sample. Orthopantomograms of 960 healthy south Indian children and sub-adults (480 boys and 480 girls) aged between 10 and 18 were analysed, 640 as training sample and 320 as a test sample. The results of logistic regression analysis with age (</≥14 years) as a dependent variable and IPM₁, IPM_2, and sex as predictor variables on training sample showed that both IPM₁ and IPM₂ significantly related to the legal age of 14 years but not the sex (p = 0.052). A receiver operating characteristic (ROC) curve analysis was performed to evaluate the specific cut-off values of IPM₁ and IPM₂ for predicting 14 years. A cut- off value of IPM₁ < 0.01 and IPM₂ < 0.02 were obtained using the highest Youden index value. Our results on test sample showed that the combined predictor, IPM₁ + IPM₂ < 0.02, showed the highest specificity (97.5% in boys and 92.5% for girls), better post-test probability, 97.2% in boys and 91.9% for girls, and a smaller number of false positives (6.8%). In conclusion, the combination of IPM₁ and IPM₂ could be useful in determining the age of over 14 years in south Indian children.

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.

2D vs. 3D Radiological Methods for Dental Age Determination around 18 Years: A Systematic Review

The age of a living human being can be determined by applying a number of different methods; the most diffused are skeletal and dental methods, both principally based on X-rays examinations. This systematic review assesses the current evidence regarding the accuracy and reliability of Cone Beam Computed Tomography (CBCT) vs. Orthopantomography (OPG) in age determination. A computerized systematic literature search of studies published up to January 2020 was conducted without language restrictions in order to identify articles comparing CBCT vs. OPG in dental anatomy evaluation, articles evaluating the accuracy of dental methods for age estimation, both with CT and OPG exams, and articles comparing CBCT vs. OPG in terms of radiation dose. CBCT was found to be more accurate compared to OPG in dental anatomy evaluation. When analyzing young adults, an estimation error of two years is considered forensically acceptable. The radiation dose of a CBCT exam is higher compared to an OPG exam. However, the difference is not as marked with small Fields Of View (FOV) and low-resolution protocols. Final conclusion was that a small FOV CBCT centered on the mandibular angle of a young patient is an accurate and safe method for dental age estimation around the age of 18.

Age estimation by canines' pulp/tooth ratio in an Iranian population using digital panoramic radiography

OBJECTIVE

Age estimation in adults is an important issue in forensic science. This study aimed to estimate the chronological age of Iranians by means of pulp/tooth area ratio (AR) of canines in digital panoramic radiographs.

MATERIALS AND METHODS

The sample consisted of panoramic radiographs of 271 male and female subjects aged 16-64 years. The pulp/tooth area ratio (AR) of upper and lower canines was calculated by AutoCAD software. Data were subjected to correlation and regression analysis.

RESULTS

There was a significant and inverse correlation between age and pulp/tooth area ratio of upper and lower canines (r=-0.794 for upper canine and r=-0.282 for lower canine; p-value<0.001). Linear regression equations were derived separately for upper, lower and both canines. The mean difference between actual and estimated age using upper canine was 6.07±1.7.

CONCLUSION

The results showed that the pulp/tooth area ratios of canines are a reliable method for age estimation in Iranians. The pulp/tooth area ratio of upper canine was better correlated with chronological age than that of lower canine.

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.