On the applicability of secondary dentin formation to radiological age estimation in young adults

The literature provides linear regression formulas for dental age estimation that is based on radiological two-dimensional measurements of the pulp size. The aim of the present study was to explore whether the previously presented regression formulas could lead to statistically sound results and to appropriate repeatability when applied to young individuals. Orthopantomograms (OPGs) of 44 Austrian individuals, aged between 13 and 24 years, were selected at random. In accordance with the reported method, six teeth on each OPG were chosen to carry out the measurements. Statistical analysis was performed in order to assess the difference between the estimated and the true chronological age. The regression formulas reported by Kvaal et al. (1995) led to a consistent underestimation; the regression formulas reported by Paewinsky et al. (2005) resulted in a constant overestimation of age. The statistical analysis of intraobserver and interobserver variation revealed a variation width below 2%, respectively.     

Orthodontic Treatment: Real Risk for Dental Age Estimation in Adults?

Dental age estimation becomes a challenge once the root formation is concluded. In living adults, one dental age indicator is the formation of secondary dentine, also associated with orthodontic treatment as well as root shortening. The aim of this study was to establish whether these secondary effects of orthodontic treatment could generate a statistically significant difference in dental age estimations when using Kvaal's method. The study sample included 34 pairs of pre‐ and postorthodontic panoramic radiographs, from different individuals with exactly the same age and sex distribution. Females 65%, median age 17.5 years, and males 35%, median age 22.5 years, were included. After data collection, dental age was estimated per tooth using formulae previously published. The risk of obtaining over‐estimation of age was calculated. (RR = 1.007). The changes caused by orthodontic treatment do not have any significant effect on age estimation when Kvaal et al.'s method is applied on panoramic radiographs.     

Age estimation by measurements of developing teeth: accuracy of Cameriere's method on a Brazilian sample

Developing teeth are commonly the criteria used for age estimation in children and young adults. The method developed by Cameriere et al. (Int J Legal Med 2006;120:49-52) is based on measures of teeth with open apex, and application of a formula, to estimate chronological age of children. The present study evaluated a sample of panoramic radiographs from Brazilian children from 5 to 15 years of age, to evaluate the accuracy of the method proposed by Cameriere et al. The results has proven the system reliable for age estimation, with a median residual error of -0.014 years between chronological and estimated ages (p = 0.603). There was a slight tendency to overestimate the ages of 5-10 years and underestimate the ages of 11-15 years.     

Variations in pulp/tooth area ratio as an indicator of age: a preliminary study

This paper details a method for age determination of adults from single rooted teeth. The sample consisted of 100 Italian white Caucasian patients (46 men, 54 women) aged between 18 and 72 years. The single rooted maxillary right canine was utilized in this preliminary study. Pulp/root ration, tooth length, pulp/tooth length ratio, pulp/tooth area and pulp/root width ratios at three different levels were computed. Pearson's correlation coefficients between age and these variables showed that the ratio between pulp and tooth area correlated best with age (r2 = 0.85). Stepwise multiple regression models yielded a linear relationship between pulp/root width at mid-root level and chronological age and a linear relationship when pulp/tooth area was compared to age. Statistical analysis indicated that these two variables explain 84.9% of variations in estimated chronological age. The median of the absolute value of residual errors between actual and estimated ages was less than four years.     

Dental age assessment: the applicability of Demirjian method in eastern Turkish children

In the literature, little is known about the applicability of this method in Turkish children. The aim of this study was, therefore, to evaluate the reliability of Demirjian method of age estimation when used for eastern Turkish children. A retrospective study was performed on a sample of panoramic radiographs taken from 807 healthy eastern Turkish children. The stages of dental maturity of the mandibular left seven permanent teeth for each subject using the eight radiographic dental maturity stages demonstrated by Demirjian were evaluated. A paired t-test was used for statistical analysis. The mean difference between the chronological and dental ages ranged from 0.2 to 1.9 years in girls and from 0.4 to 1.3 years in boys. The differences between the chronological and dental ages were statistically significant in all age groups. The applicability of Demirjian method is not suitable for eastern Turkish population.     

Age estimation of adults from dental radiographs

Previous studies have shown that with advancing age the size of the dental pulp cavity is reduced as a result of secondary dentine deposit, so that measurements of this reduction can be used as an indicator of age. The aim of the present study was to find a method which could be used to estimate the chronological age of an adult from measurements of the size of the pulp on full mouth dental radiographs. The material consisted of periapical radiographs from 100 dental patients who had attended the clinics of the Dental Faculty in Oslo. The radiographs of six types of teeth from each jaw were measured: maxillary central and lateral incisors and second premolars, and mandibular lateral incisors, canines and first premolars. To compensate for differences in magnification and angulation on the radiographs, the following ratios were calculated: pulp/root length, pulp/tooth length, tooth/root length and pulp/root width at three different levels. Statistical analyses showed that Pearson's correlation coefficient between age and the different ratios for each type of tooth was significant, except for the ratio between tooth and root length, which was, therefore, excluded from further analysis. Principal component analyses were performed on all ratios, followed by regression analyses with age as dependent variable and the principal components as independent variables. The principal component analyses showed that only the two first of them had significant influence on age, and a good and easily calculated approximation to the first component was found to be the mean of all the ratios. A good approximation to the second principal component was found to be the difference between the mean of two width ratios and the mean of two length ratios, and these approximations of the first and second principal components were chosen as predictors in regression analyses with age as the dependent variable. The coefficient of determination (r²) for the estimation was strongest when the ratios of the six teeth were included (r² = 0.76) and weakest when measurements from the mandibular canines alone were included (r² = 0.56). Measurement on dental radiographs may be a non-invasive technique for estimating the age of adults, both living and dead, in forensic work and in archaeological studies, but the method ought to be tested on an independent sample.     

The accuracy of three methods of age estimation using radiographic measurements of developing teeth

The accuracy of age estimation using three quantitative methods of developing permanent teeth was investigated. These were M?rnstad et al. [Scand. J. Dent. Res. 102 (1994) 137], Liversidge and Molleson [J. For. Sci. 44 (1999) 917] and Carels et al. [J. Biol. Bucc. 19 (1991) 297]. The sample consisted of 145 white Caucasian children (75 girls, 70 boys) aged between 8 and 13 years. Tooth length and apex width of mandibular canine, premolars and first and second molars were measured from orthopantomographs using a digitiser. These data were substituted into equations from the three methods and estimated age was calculated and compared to chronological age. Age was under-estimated in boys and girls using all the three methods; the mean difference between chronological and estimated ages for method I was -0.83 (standard deviation +/-0.96) years for boys and -0.67 (+/-0.76) years for girls; method II -0.79 (+/-0.93) and -0.63 (+/-0.92); method III -1.03 (+/-1.48) and -1.35 (+/-1.11) for boys and girls, respectively. Further analysis of age cohorts, found the most accurate method to be method I for the age group 8.00-8.99 years where age could be predicted to 0.14+/-0.44 years (boys) and 0.10+/-0.32 years (girls). Accuracy was greater for younger children compared to older children and this decreased with age.     

Accuracy of different dental age estimation methods on Turkish children

Tooth development is widely used to estimate age or maturation. Dental age estimation is so important for various research works. Numerous methods have been described to estimate dental age based on the dental maturation. The aims of this study were to decide the best method to estimate dental age on Turkish children by reviewing several methods and to illustrate the differences among the methods and to assist future studies. The records of Turkish children between the ages of 7 and 13 years who visited the Department of Pediatric Dentistry of the Faculty of Dentistry of the Süleyman Demirel University in Isparta, Turkey were reviewed and a total of 425 healthy children with complete records, satisfactory panoramic radiographs, similar socio-economic background and ethnic origin were included. Panoramic radiographs were examined with Nolla's, Haavikko's and Demirjian's methods. Dental age was calculated for each method, and the differences between the estimated dental age and the chronological age were compared with paired t-test and Wilcoxon signed rank test. The accuracy of three methods was obtained with ICC (intraclass correlation coefficient). An under-estimation of the dental age was observed by using Nolla's and Haavikko's methods (boys -0.53±0.95, girls -0.57±0.91, both -0.54±0.93; boys -0.60±0.80, girls -0.56±0.81, both -0.58±0.80, respectively) and an over-estimation of the dental age was observed by using Demirjian's method (boys 0.52±0.86, girls 0.75±0.90, both 0.64±0.89). Haavikko's method was more accurate in the dental age estimation compared to the other methods. All of the three methods are not completely suitable for Turkish children and establishment of the population-specific standards is essential and crucial.     

To evaluate the utility of smaller sample sizes when assessing dental maturity curves for forensic age estimation

Dental maturation and chronological age estimation were determined from 144 healthy Western Australian individuals aged 3.6-14.5 years. The results were compared with Farah et al.'s previous study which comprised a larger heterogeneous sample of Western Australian individuals (n = 1450). Orthopantomograms were analyzed with the application of Demirjian and Goldstein's 4-tooth method based on eight stages of dental mineralization. Analysis of variance revealed no significant differences in dental maturity scores in each age group among the males in both studies; similar results were seen in the females. Paired t-tests showed no statistical significance overall between chronological and estimated ages for the males in our sample (p = 0.181), whereas the females showed significant differences (p < 0.001). Our results show that smaller samples may be used when assessing dental maturity curves for forensic age estimation.     

Age estimation by pulp/tooth ratio in canines by peri-apical X-rays

Estimation of age in individuals has received considerable attention in forensic science, in which it is a widely used method for individual identification, together with paleo-demographic analyses to establish mortality patterns in past populations. The present investigation, which is a continuation of a previously published pilot study, was conducted to examine the possible application of the pulp/tooth area ratio by peri-apical images as an indicator of age at death. A total of 200 peri-apical X-rays of upper and lower canines were assembled from 57 male and 43 female skeletons of Caucasian origin, aged between 20 and 79 years. They belong to the Frassetto osteological collection of Sassari (Sardinia) and are housed in the Museum of Anthropology, Department of Experimental and Evolutionistic Biology, University of Bologna. For each skeleton, dental maturity was evaluated by measuring the pulp/tooth area ratio on upper (x(1)) and lower (x(2)) canines. Very good agreement was found between intraobserver measurements. Statistical analysis was performed in order to obtain multiple regression formulae for dental age calculation, with chronological age as dependent variable, and gender, and upper and lower canines as independent variables. Stepwise regression analysis showed that gender did not contribute significantly to the fit (p=0.881) whereas variables x(1) and x(2) and the first-order interaction between them did. These two variables explained 92.5% of variations in estimated chronological age and the residual standard error was 4.06 years. Lastly, two simple linear regression equations were obtained for age estimation using canines from the maxilla and mandible separately. Both models explained 86% of variations in estimated chronological age and allowed an age-at-death estimate with a residual standard error of about 5.4 years.     

The application of Kvaal's dental age calculation technique on panoramic dental radiographs

INTRODUCTION: Literature reports on a method for dental age calculation which is based only on radiological measurements on periapical dental radiographs: the relationship between chronological age and the two-dimensional dental pulpal size was analysed by means of multiple regression analyses. The purpose of the present study was to evaluate whether this approach could be feasible and could lead to statistically sound results with adequate repeatability when applied on panoramic radiographs. MATERIALS AND METHODS: One hundred and ninety seven panoramic radiographs were collected at random from patients of whom the age ranged from 19 to 75 years. According to the reported technique, six teeth were selected on the panoramic radiograph: in the maxilla the central and lateral incisor and second bicuspid, and in the mandibula the lateral incisor, cuspid and first bicuspid. The same exclusion criteria as in the original paper were respected. Statistical analysis was carried out in order to spot significant differences between the chronological age and the calculated age. RESULTS: When the age was calculated based on measurements of all six teeth or of all three mandibular teeth, no significant differences were found between the real age and the calculated one. In all other instances using the individual teeth separately or using all three maxillary teeth statistical analysis revealed significant differences. CONCLUSION: There appears to be no significant difference between applying the original technique on standard long-cone periapical radiographs or on orthopantomograms, especially when carrying out measurements on all six selected teeth.     

Comparative study of Greulich and Pyle Atlas and Maturos 4.0 program for age estimation in a Portuguese sample

Age estimation of living individuals has become one of the big issues of forensic anthropology. The increase of children and adolescents with no valid proof of their chronological age is a legal concern to many countries, especially in situations of illegal immigration, sub adult delinquency and juvenile work. For this purpose, the use of radiological methods for evaluation of skeletal maturation is particularly useful. In this study we compare the two of the most common methods applied in age estimation by hand/wrist radiographs: the Radiographic Atlas of Skeletal Development of the Hand and Wrist made by Greulich and Pyle (GP), 1959,and the Sempé method developed for computer--Maturos 4.0 (MT) program. These methods were applied to a sample of 230 radiographs of the hand and wrist from Portuguese children and adolescents of known sex age and age, aged between 12 and 20 years, who performed medical examination at the University of Coimbra Hospitals during 2005. The methods achieved different performances, depending on the age group. Between 12 and 15 years the bone age with the MT program is closer to the chronological age, whereas in older ages the GP Atlas method is more trustworthy. At the ages with legal consequences in Portugal (16 and 18 years) the GP Atlas method is most accurate, namely to decide whether an individual is younger or older than 18 years. Around 16 years old, although there are doubts in relation to the accuracy of both methods, GP Atlas seems to perform better.     

Is the length of the sternum reliable for estimating adult stature? A pilot study using fresh sterna and a test of two methods using dry sterna

Stature estimation is one of the four attributes of the biological profile obtained from human skeletal remains. The length of the long bones has been consistently used to estimate stature from regression equations, but these may be useless when dealing with fresh or decomposed mutilated remains. Until recently, there was no consistent assessment of the reliability of measurements of the sternum for stature estimation. The purpose of this paper is to test previously developed regression formulae for stature based on measurements of the dry sternum and to assess the reliability of measurements of the fresh sternum in estimating stature. The formulae developed by Menezes et al. and Singh et al. were applied to a sample of 5 known stature skeletons from the identified human skeletal collection curated at the National Museum of Natural History, in Lisbon, Portugal. Testing of these formulae showed that estimated stature confidence intervals do not allow discrimination between individuals with similar stature. The length of the fresh sternum was measured on a sample of 45 male individuals autopsied at the National Institute of Legal Medicine - North Delegation (Porto, Portugal). Cadaver length was regressed on sternum length and a simple linear regression formula was obtained. The regression model provided a 95% confidence interval of 13.32 cm and a correlation coefficient of only 0.329. Compared to other studies, regression formulae based on the length of the sternum provided considerably larger standard errors than that based on long bone lengths. These results suggest that the length of the sternum has limited forensic value and relatively low reliability in estimating stature from mutilated human skeletal remains, either skeletonized or fresh.     

Reproducibility of radiographic stage assessment of third molars

The aim of this study was to determine intra- and inter-observer variability of the developing third molar from panoramic radiographs. Formation of third molars was assessed according to stages described by modified Demirjian et al.'s methods: Moorrees et al. [C.F.A. Moorrees, E.A. Fanning, E.E. Hunt, Age variation of formation stages for ten permanent teeth, J. Dent. Res. 42 (1963) 1490-1502] and Solari and Abramovitch [A.C. Solari, K. Abramovitch, The accuracy and precision of third molar development as an indicator of chronological age in Hispanics, J. Forensic Sci. 47 (2002) 531-535]; in addition, data were also analysed unmodified, i.e. Haavikko [K. Haavikko, The formation and alveolar and clinical eruption of the permanent teeth, an orthopantomograph study, Proc. Finn. Dent. Soc. 66 (1970) 104-170] and Demirjian et al. [A. Demirjian, H. Goldstein, J.M. Tanner, A new system of dental age assessment, Hum. Biol. 45 (1973) 211-227]. The sample was a random selection of 73 panoramic radiographs from patients aged 8-24 years. After training, the left maxillary and mandibular third molars were scored on two separate occasions without knowledge of previous scores. Cohen's Kappa and percentage agreement were calculated for each method, for maxillary, for mandibular third molars and combined. Percentage agreement for stages was also calculated. Intra-observer agreement was greater for mandibular third molars compared to maxillary third molars, and better for methods with fewer stages. Kappa values indicated good agreement for most methods; the best was Demirjian et al.'s method for mandibular third molar with very good agreement (K = 0.80) for the first author, good agreement for the second author (K = 0.75) and good agreement between observers (K = 0.75). The stages with best agreement were Demirjian's stage E [A. Demirjian, H. Goldstein, J.M. Tanner, A new system of dental age assessment, Hum. Biol. 45 (1973) 211-227] and Moorrees et al.'s stage Cc and R1/4 [C.F.A. Moorrees, E.A. Fanning, E.E. Hunt, Age variation of formation stages for ten permanent teeth, J. Dent. Res. 42 (1963) 1490-1502]. CONCLUSIONS: Having clearly defined stages and fewer stages allowed better reproducibility of third molar formation.     

Age estimation by pulp/tooth area ratio in canines: Cameriere's method assessed in an Indian sample using radiovisiography

Age estimation of an individual whether living or dead is an intimidating task in forensic investigations. Since teeth are more resistant to most peri- and post-mortem changes, they are frequently used for identification and age estimation when skeletal remains are in poor condition. However, most methods are destructive and warrant extraction of teeth which is not feasible in living individuals. Cameriere's et al. put forth a radiographic method of age estimation by pulp to tooth area ratio (AR) in canines and revealed a linear regression between age and the AR. In the present study, we estimated the AR in 456 canines (upper, lower and both) in an Indian sample (114 males and 114 females) using radiovisiography technique. Linear regression equations were derived for upper canine, lower canine and both using the AR to estimate chronological age. Additionally, the efficacy of these equations was also evaluated in younger age group (<45 years). The formulas derived, i.e., age = 96.795 ? 513.561x₁ (Eq. (1)) for upper canine, age = 88.308 ? 458.137x₂ (Eq. (2)) for lower canine and age = 99.190 ? 283.537x₁ ? 306.902x₂ + 400.873x₁x₂ (Eq. (3)) for both the canines were applied to predict the chronological age. The mean value of residuals using these regression equations ranged from 4.28 to 6.39 years with upper canine equation generally giving a precise result. When these equations were applied for younger ages (<45 years), the regression equation derived from both canines gave a better result (mean residual 2.70 years). Overall these equations were better able to predict the age in younger ages, i.e., up to 45 years.     

Dental age estimation through volume matching of teeth imaged by cone-beam CT

A custom-made voxel counting software for calculating the ratio between pulp canal versus tooth volume based on cone-beam CT tooth images was developed and evaluated. The aim of this study was to attempt establishing a correlation between the chronological age of a certain individual and the pulp/tooth volume ratio of one of the teeth. Twenty-eight single rooted teeth of 19 individuals with well-known chronological age were scanned by the cone-beam CT (3D Accuitomo, J. Morita, Kyoto, Japan). Next the images were analyzed using the custom-made software. Linear regression analysis was performed. The results of the analysis showed a moderate correlation between the pulp/tooth volume ratio and biological age with a coefficient of determination (R2) of 0.29. Although the present work was limited to a pilot study, the developed technique showed promising results for dental age estimation in a non-invasive manner using cone-beam CT images in living individuals.     

Radiographic evaluation of third molar development in relation to chronological age among Turkish children and youth

A sharp increase in forensic age estimation of living persons has been observed in recent years. However, ethnic populations residing in different countries have been insufficiently analyzed. According to 2004 data compiled by the Essen-based Turkey Research Center, there are 3.8 million Turkish people living abroad, and 3.2 million of them reside in European Union countries. Despite the high number of Turks living abroad, little is known about third-molar development for forensic application in this population. Hence, it was considered worthwhile to determine the developmental stages of the third molar in a group of Turkish population, to assess chronological age estimation based on the developmental stages, and to compare third molar development according to sex, age and location. Orthopantomograms of 1134 Turkish patients, ages 4-20 years were examined and third-molar developmental stages were evaluated based on Demirjian's classifications. Orthopantomograms were scored by two different observers, and Wilcoxon matched-pairs signed-ranks test used to test intra- and inter-observer reliability revealed a strong agreement between both intra- and inter-observer measurements. Linear regression analysis was performed to correlate third-molar development and chronological age, and further statistical analysis was performed to determine the relation between sex, age and location. Results showed a strong linear correlation between age and molar development (males: r(2)=0.57; females: r(2)=0.56). Mineralizations of left and right third molars were compared using Wilcoxon tests, and no statistical differences were found. No significant differences were found in third-molar development between males and females. Mandibular third molar crypt formation was observed in 2.4% of patients at age seven and maxillary third molar crypt formation was observed in 1.3% of patients at age seven. A strong correlation was found between third-molar development and chronological age. Among the Turkish population, third molar crypt formation is observable at as early as 7 years in both the mandible and maxilla. Agenesis can be determined conclusively if no radiolucent bud is present by age 14.     

应用放射影像技术进行牙龄推断

牙龄是年龄推断的重要方法之一，国外学者常将其与骨龄联合应用以提高年龄推断的准确性，但国内尚未普遍开展。大量研究表明，应用放射影像学这一无创的检查手段，可以准确观察牙齿的增龄性变化，如牙冠与牙根的发育程度、牙髓腔的变化等。目前应用放射影像学进行牙龄推断的主要方法有Gleiser和Hunt法、Demirjian法及牙髓腔测量法等。其中Demirjian法的准确性最高，但在推断法定敏感年龄时尚存在局限性。随着放射影像学的发展，尤其是CT的出现，依赖其高分辨率以及相匹配的测量软件，可提高牙龄推断的准确性与可靠性，有望成为今后推断活体年龄的重要手段。     

青少年手腕骨骨龄与生活年龄的差异观察

目的比较以不同骨龄标准所评价的青少年手腕骨骨龄与生活年龄的差异,观察生长发育长期变化对青少年年龄推测的影响。方法从中国5座大中城市抽取11464名（男5873,女5591）3～18岁汉族正常青少年儿童,并另随机抽取950名（男516,女434）12～18岁骨发育正常的汉族青少年作为验证样本。按CHN法和RC法骨龄标准评价手腕部X线片骨龄,并对不同方法评价的骨龄及生活年龄进行统计学分析。结果各年龄组CHN法骨龄中位数大于RC骨龄,其差异具有显著性意义（P〈0．05）。验证样本中,在男12—16．5岁、女12～14．5岁之间,CHN骨龄减生活年龄之差值分别为0．35—1．00岁和0．57～1．16岁（P〈0．01）;RC骨龄减生活年龄的差值分别为-0．26—0．23岁和-0．27～0．06岁（P〉0．05）。在男17～18岁、女15～17岁之间,CHN骨龄减生活年龄的差值分别为-0．52～-1．05岁和-0．16～-1．13岁（P〈0．05）,RC骨龄减生活年龄的差值分别为-0．35～-0．48岁和-0．22～-0．79岁（P〈0．05）。结论CHN法骨龄高于生活年龄,在大部分年龄组RC骨龄与生活年龄基本一致。