[Age determination of pre- and postnatal skeletons with special reference to current methodological aspects]

From the remains of ten fetal and neonatal skeletons the standard methods of age estimation by means of dental and osseous criteria as well as diaphyseal length were applied and discussed. The ratio of long bone lengths and change of proportions during the first and second half of pregnancy is a useful indicator for the stage of maturation.

Validity of the Demirjian method for dental age estimation when applied to Norwegian children

Dental age was studied in a sample of 261 Norwegian children by using the maturity standards of Demirjian & Goldstein (1976) to examine the applicability of these standards as a reference for overall dental maturity in a Norwegian population. The sample comprised 128 boys and 133 girls included in 'the Oslo Growth Material', from whom orthopantomograms (total, 783) had been longitudinally obtained, with intervals of about 3 years and covering 3 age spans (5.5-6.5 years, 8.5-9.5 years, and 11.5-12.5 years), each divided into 3 half-year age groups. Reliability was analyzed by repeated assessments of 134 of the radiographs, and the overall mean difference between duplicate dental age determinations was 0.5 months for intra- and 1.8 months for inter-examiner comparisons. The Norwegian children were generally somewhat advanced in dental maturity compared with the French-Canadian reference sample. Among the boys the mean difference between dental age and chronologic age varied in the different age groups from 1.5 to 4.0 months. Among the girls the difference increased with age, varying from 0 to 3.5 months in the younger age groups (5.5 to 9.0 years) and from 4.5 to 7.5 months in the age groups 9.5 years and above. The variability in individual dental age was marked and increased with age. For the older age groups 95% of the individual age estimates were within +/-2 years of the real age. The applied standards appear to be adequate for studying dental age in groups of children from a Norwegian population. Given the considerable individual variation in dental maturity, estimation of chronologic age in individual children should be supplemented by other indicators of biologic maturity.

Ageing Arab horses by their dentition

The dentition of 170 Arab horses of known ages was examined and compared with the dental characteristics of trotter horses and Belgian draft horses of the same ages. The results indicated that inaccuracies in the determination of the age of horses by their dentition may result, at least partly, from differences between the breeds of horse involved because there were some major differences between the three breeds examined. These differences increased as the horses' true age increased. In general, the rate of dental wear was slower in the Arab horses than in trotter horses and Belgian draft horses.

Methods of measuring morphological parameters in dental radiographs. Comparison between image analysis and manual measurements

Measurements of age-related changes in dental tissues are often used when estimating the age of an individual. With the new technology now available, the methods of measurement might be standardized and reproducible. The purpose of the present study was to compare the reliability of manual and computer-assisted measurements of morphological parameters in dental radiographs. Manual measurements were made conventionally using a pair of vernier callipers and a stereomicroscope with a measuring eyepiece. An image analysis software program was employed for the computer assisted measurements. Lengths and widths of tooth and pulp were measured both manually and with computer assistance on periapical radiographs from 40 patients, six teeth in each patient. Statistical analyses showed no significant intra- or inter-observer differences for the manual measurements. Statistically significant intra- and inter-observer differences were, however, found between the manual and computer-assisted measurements. The results implied that, despite advanced technology, conventional methods may be better suited for measuring linear morphological parameters in dental tissue.

Dental age assessment: the applicability of Demirjian's method in south Indian children

The paper concerns the testing of Demirjian's method of age assessment in South Indian children. Since previous studies have shown the inapplicability of Demirjian's method on other populations, an attempt to compile a maturity standard for South Indian children was made. An additional independent indicator of age was employed, namely the skeletal age. The material was 184 South Indian children aged 5 to 15 years and an additional 34 children as the test sample. It was found that Demirjian's method gave an overestimation of 3.04 and 2.82 years in males and females, respectively. The skeletal age was found to differ from the dental and chronologic age. It may be concluded that the accuracy of age estimation based on Demirjian's method is not applicable for the South Indian children. For the population to be tested, it is imperative that individual assessment parameters need to be put forward because of wide ethnic differences.

Dental age assessment: the applicability of Demirjian's method in south Indian children

The paper concerns the testing of Demirjian's method of age assessment in South Indian children. Since previous studies have shown the inapplicability of Demirjian's method on other populations, an attempt to compile a maturity standard for South Indian children was made. An additional independent indicator of age was employed, namely the skeletal age. The material was 184 South Indian children aged 5 to 15 years and an additional 34 children as the test sample. It was found that Demirjian's method gave an overestimation of 3.04 and 2.82 years in males and females, respectively. The skeletal age was found to differ from the dental and chronologic age. It may be concluded that the accuracy of age estimation based on Demirjian's method is not applicable for the South Indian children. For the population to be tested, it is imperative that individual assessment parameters need to be put forward because of wide ethnic differences.

CCTV study of cemental annulations in determining the age from single tooth

Cementum in human tooth is a hard tissue in its root deposited around dentin in layers throughout the life. Microscopically each layer is seen as a set of alternating dark and light bands and called as Cemental Annulations. Intact teeth obtained from subjects of either sex and of known ages processed by ground sectioning manually and mounted on a glass slide. The cemental annulations were then counted by light microscope using CCTV Screen, at the junction of cervical with middle third of root. Age was then determined by adding the eruption age in years of tooth in study to the annulations counted. This was found to be matching with actual age almost to an accuracy of +/- 1-2 years.

Improvement of age estimation using amino acid racemization in a case of pink teeth

Age was estimated from pink teeth using racemization of dentinal aspartic acid. Materials for identification were two lower second premolars. The body was determined to be that of a 40-year-old man; however, the age of the decedent had been estimated to be 29 and 30 years by the conventional method and 30 years from findings in the oral cavity. To clarify the cause of this difference, the powdered teeth were further washed in 0.01 mol/L hydrochloric acid. The racemization ratio (D/L ratio) of ordinary white teeth from persons of known age was slightly lower than that before washing, whereas that of the teeth used for identification was higher than before washing. The calculated age of the decedent using the racemization ratio of his teeth was between 36 and 37 years. These results suggest that age estimated from pink teeth is probably underestimated, but a more accurate age estimate can be obtained after adequate washing.

The biology of bone maturation and ageing

The only indicator of development that is available from birth to maturity is skeletal age. This short review discusses how standard bone ages have been developed from assessment of radiographs, and describes the advantages and disadvantages of the 'atlas' approach as developed by Greulich and Pyle, and the bone by bone approach, as developed by Tanner. As the standards currently available are based mainly on historical series of radiographs from particular populations, it is stressed that national standards should be established and updated regularly if bone ages are to be used to assess development. The question of the clinical relevance of using bone age assessments of the hand and wrist to determine the state maturation of the whole skeleton and particularly, the growth potential is also discussed. It is concluded that, despite the difficulties of assessing bone age, and the assumptions on which the various methods are based, determination of skeletal development is clinically relevant in that it provides the only means of assessing rates of maturational change throughout the growing period.

Incremental lines in root cementum of human teeth: an approach to their ultrastructural nature by microscopy

In ground sections of human teeth, root cementum shows under the light microscope as alternating, almost concentric, dark and light rings. In paleontology and forensic medicine, the number of these incremental lines or annulations is used to derive the age-at-death of the individual. To find the ultrastructural features underlying these cemental annulations, we used bright-field light microscopy (LM), confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and electron-dispersive x-radiation (EDX) in a scanning electron microscope (SEM). Annulations visible in ground sections of about 100-micron thickness were no longer visible in semi-thin sections (thickness, 1-2 microns) of the same specimen in the same area. The assumption that annulations could be caused by super-imposing structures in the depth of field of the light microscope's objective lens was not verified by CLSM. Fiber bundles of higher density than the surrounding matrix in TEM micrographs could not be connected unambiguously with annulations in LM micrographs. After all, the ultrastructural nature of cemental annulations remains an open question.

Ageing draft and trotter horses by their dentition

The accuracy of ageing horses by their dentition was assessed by comparing the dental features with the known dates of birth of 212 trotter horses and 189 Belgian draft horses. The horses ranged in age from two to 25 years. In both breeds it was observed that the shedding of the incisors and the appearance of the dental stars were the most reliable features for age determination. In young animals, the dental configuration was similar in both breeds. With increasing age the incisor teeth of draft horses were more liable to abrasion than those of trotter horses. The sequential changes in appearance of the permanent incisors occurred earlier in draft horses than in trotters.

The genetic contribution to dental maturation

It has been established in the literature that there is a major genetic impact on tooth size (Potter et al., 1976; Corruccini and Sharma, 1985; Sharma et al., 1985), tooth morphology (Kraus and Furr, 1952; Biggerstaff, 1970), and root formation (Garn et al., 1960; Green and Aszkler, 1970). None of the studies concerning root formation, however, used the more advanced method of path analysis and model fitting to estimate genetic influence. The aim of the present study was to determine the genetic and environmental influence on dental maturation. Dental age scores were determined on panoramic radiographs of 58 pairs of twins--26 monozygotic (MZ) and 32 dizygotic (DZ)--with the method of Demirjian et al. (1973). No mirror-image effect was found between the sides of the same individual or between twin members, so dental maturation seems to be symmetrical for both left and right sides of the mandible. Correlation coefficients were significantly higher in MZ than in DZ twins, which suggests a genetic influence. Model fitting showed that the variation in dental age was best explained by additive genetic influences (A-component) (43%) and by environmental factors common to both twins (C-component) (50%). The specific environment (E-component) added only 8% to the model. The importance of the common environmental factor can be explained by the fact that twins, being raised together, share the same prenatal, natal, and immediate post-natal conditions that are of importance for the formation of the teeth.

The coronal pulp cavity index: a biomarker for age determination in human adults

The correlation between reduction of the coronal pulp cavity and chronological age was examined in a sample of 846 intact teeth from 433 individuals of known age and sex. Panoramic (rotational) radiography was used to measure the height (mm) of the crown (CH = coronal height) and the height (mm) of the coronal pulp cavity (CPCH = coronal pulp cavity height) of 425 premolars and 421 molars from 213 males and 220 females. The tooth-coronal index (TCI) after Ikeda et al. [1985] Jpn. J. For. Med. 39:244-250) was computed for each tooth and regressed on real age. The correlation coefficients ranged from -0.92 (molars, combined sample, right side) to -0.87 (female molars), with an S.E. of the estimate ranging from 5.88-6.66 years. Correlations were slightly higher in males than females. The equations obtained allowed estimation of age in a sample of 100 teeth from both sexes (not used for the regression) with an error of +/- 5 years in 81.4% of cases for male molars. The regression formulae for estimating age obtained from the recent sample were tested on a historical sample of 100 teeth from 100-year-old skeletons with an error of +/- 5 years in 70.3% of cases for male molars. This study illustrates the potential value of a little-known aging method which can be easily applied to estimate age in both living individuals and skeletal material of unknown age.

Age estimation from racemization rate using heated teeth

The racemization ratio (D/L ratio) of aspartic acid was determined in soluble peptide and total amino acid extracted from the dentine of experimentally-heated and unheated teeth. The ratio was higher in heated than in unheated teeth for total amino acid, but approximately the same for soluble peptide. Although the estimated age for total amino acid was much greater than the true age for heated teeth, it was approximately the same for total amino acid in unheated teeth and for soluble peptide in heated teeth and unheated teeth. These results suggest that age calculated from the D/L ratio of dentinal soluble peptide from burned bodies is sufficiently accurate for this parameter to be used to estimate age in teeth from burned bodies.

[Comparison of two methods of age determination in teeth of known age from wild carnivores]

Two age-determining methods were conducted on representatives of known age from the Order Carnivora (4 red foxes, 3 tree martens, 3 stone martens, 2 racoons, 2 badgers, 2 polecat and one otter). Age determination employed with the aid of tooth wear nearly agrees with the real age of the animals. Dating based on the formation of the age-dependent cement zone coincided well with the known ages of the individual specimens. However, in real foxes the figure one must be added to the number of cementum layers counted determining the definitive age of individuals. For representation of the cementum layers transverse sections of the apical part of the tooth root of canini, P2 and P3, stained with methylene blue, should be used. It is important to note that the dentino-cemental line should not be considered when counting the year rings in the cement.

Dental emergence among urban Zambian school children: an assessment of the accuracy of three methods in assigning ages

In situations where birth records are unavailable and stated ages are unreliable, the emergence of the permanent dentition can serve as an indicator of age. Due to substantial variation in the timing of tooth emergence, a sample (n = 721) of Zambian school children, with known ages, was examined to provide a tooth emergence reference standard for the area. Three methods for assigning ages were utilized and their accuracy assessed. A random test sample was withheld from the original study in order to further evaluate the methods' accuracy. The three methods-1) number of teeth, 2) regression and 3) probit analysis-were applied to Zambian children, and estimates of age were made. Predicted ages were compared to actual ages to determine the percentage of accuracy in three categories-(+/-) .5, +/- 1.0 and +/- 2.0 years- and paired t-tests were conducted. Each of the three methods was then applied to the test sample, and their accuracy was evaluated in the same manner. Methods 1 and 2 were found to provide the higher percentage of correct ages within +/- .5 years, assigning roughly 39% of both male and female children within this increment. This was also the case at the next increment, with methods 1 and 2 assigning a higher percentage (66-76%) of children to the +/- 1.0 year category, while the accuracy of method 3 was quite a bit lower. The results for the test sample were very similar to those of the main sample. The overall accuracy of methods 1 and 2 was very similar in both the main and test samples, while method 3 had lower accuracy and t-tests indicated significant differences. Therefore, due to ease of application in the field setting, method 1, mean age per number of teeth emerged, is the method of choice.

Estimation of age from teeth by amino acid racemization: influence of fixative

To determine the age of a subject from teeth accurately utilizing the racemization rates of amino acids, standard samples of the same tooth species from the same jaw are necessary as controls, as well as data for identification. However, standard teeth are generally stored in fixatives such as ethanol and formalin. We investigated and compared the degree of progression of racemization of dentinal aspartic acid in teeth stored in 95% ethanol, 10% formalin, or 10% neutral formalin fixatives. The racemization rate of dentinal aspartic acid in teeth stored in 10% neutral formalin was the highest, followed by that for teeth stored in 10% formalin then that for teeth stored in 95% ethanol. Teeth stored in these fixatives at 15 degrees C showed almost no progression of racemization. The racemization ratio (D/L ratio) in teeth extracted 10 years previously was almost unchanged from that at the time of extraction, and allowed an accurate evaluation of the subjects age at tooth extraction.

Some considerations regarding the use of amino acid racemization in human dentine as an indicator of age at death

An HPLC method is described for simultaneously obtaining the enantiomeric ratio of three amino acids (aspartic acid, serine, and glutamic acid) from dental collagen, with a view to using this information for estimating age at death. Results are reported from a sample of twenty three known age modern teeth, six known age 19th C. AD teeth, and two unknown age Romano-British teeth. It was found (as expected) that all three D/L ratios changed significantly with chronological age. Standard calibration techniques were used to estimate ages for the six 19th C. AD specimens from regression equations estimated from the modern specimens, and also to predict (for the first time) the error associated with such estimates. Errors using aspartic acid were found to be similar to those obtained by other methods of age estimation from dental evidence, serine, and glutamic acid providing much poorer age estimates. Additionally, a systematic difference in the age-enantiomeric ratio relationship was observed between modern and older dental samples. It is concluded that there is some fundamental difference in the observed enantiomeric ratios between modern teeth and older samples, possibly as a result of the chemical alteration of the dental proteins.

Third molars in the establishment of adult status--a case report

Teeth are the most durable structures in the human body. The timing and sequence of their development, as contained in dental development charts, have been used as valid criteria for age determination. The third molars however are the last teeth to erupt and are regarded as the most variable in the dentition. Age estimation in a legal context, using developing third molars must be carefully applied otherwise justice may miscarry. A case of wrongful use of the technique is presented here.

Application of dimorphism in teeth to age calculation

The objective of this study was to determine which teeth provide the most reliable data for use in age estimation. We studied 170 teeth from the anterior region (central and lateral incisors, and canines) and used an image analysis technique to analyse a number of morphometric features in thin sections of tooth. Our results showed root translucency to be the variable most clearly related to the subject's age, and the canine teeth to provide the most reliable information on this variable.

A Bayesian approach to adult human age estimation from dental observations by Johanson's age changes

Much of the data which appears in the forensic and archaeological literature is ordinal or categorical. This is particularly true of the age related indicators presented by Gustafson in his method of human adult age estimation using the structural changes in human teeth. This technique is still being modified and elaborated. However, the statistical methods of regression analysis employed by Gustafson and others are not particularly appropriate to this type of data, but are still employed because alternatives have not yet been explored. This paper presents a novel approach based upon the application of Bayes' theorem to ordinal and categorical data, which overcomes many of the problems associated with regression analysis.