How can teeth be used to determine age

Scientists can also use fossils of teeth to figure out information about human diets throughout history. Scientists study fossilized teeth to determine various types of information including how teeth have changed over time, as well as patterns that can give clues to the types of food consumed by ancient animals.

If a scientist discovers that a species teeth have changed shape or size over time, they are able to learn information about changes in diet, and even social behavior, as well as information about the way the species moved locomotion.

Patterns on the teeth can clue scientists in to a species diet. Molar surfaces that are heavily pitted will suggest a diet that consisted of brittle, harder food such as nuts, bones, or hard seeds. On the other hand, shearing patterns on molars can indicate that teeth were used for shearing foods such as meat or leaves.

While teeth are not as unique as a fingerprint, they can be used to help identify a person. Scientists can determine the approximate age of a person by the size of their teeth. Ethnicity can also be determined by looking at teeth, as different ethnic groups will have distinct dental features.

Forensic dentistry, or forensic odontology, has proven to be an invaluable tool for law enforcement in both helping to identify people, as well as to analyze and compare bite marks to help solve crimes. By examining teeth, we can learn tons of information about health, diet, identity, and more. Teeth can give clues to various health issues, along with clues to humans and animals of the past. Ultimately, they are an important part of the human and animal body that can be used to learn information not only in life but also in death.

The teeth a test of age, considered with reference to the factory children: addressed to members of both Houses of Parliament. London: H. Renshaw, Google Scholar. Time and duration of eruption of first and second permanent molars: a longitudinal investigation.

Community Dent Oral Epidemiol ; 31 : — Article Google Scholar. Fanning E A. A longitudinal study of tooth formation and resorption. N Z Dent J ; 57 : — Gustafson G, Koch G.

Age estimation up to 16 years of age based on dental development. Proc Finn Dent Soc ; 25 : — A new system of dental age assessment. Hum Biol ; 45 : — Rosen A A, Baumwell J. Chronological development of the dentition of medically indigent children: a new perspective. J Dent Child ; 48 : — Radiographic evaluation of third molar development in Spanish children and young people.

Forensic Sci Int ; : — Haavikko K. The formation and the alveolar and clinical eruption of the permanent teeth; an orthopantomographic study. Suom Hammaslaak Toim ; 66 : — Demirjian A, Goldstein H. New systems for dental maturity based on seven and four teeth. Ann Hum Biol ; 3 : — Root development of the lower third molar and its relation to chronological age. Swed Dent J ; 16 : — Kullman L. Accuracy of two dental and one skeletal age estimation method in Swedish adolescents. Forensic Sci Int ; 75 : — Analysis of orthopantograms to evaluate the potential of forensic age determination based on third molar developmental stages.

Eur J Med Res ; 6 : — Dental age evaluation: a new six developmental stage method. Clin Prev Dent ; 6 : 18— PubMed Google Scholar. Validation of common classification systems for assessing the mineralization of third molars. Int J Legal Med ; : 22— Accuracy of age estimation of radiographic methods using developing teeth. Leandro G. Meta-analysis in medical research. Book Google Scholar. The measurement of observer agreement for categorical data.

Biometrics ; 33 : — An analysis of variance test for normality complete samples. Biometrika ; 52 : — Stata corporation.

Stata user's guide release 9. Version 8. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet ; 1 : — Lin L. A concordance correlation coefficient to evaluate reproducibility. Biometrics ; 45 : — Boonpitaksathit J. Development of reference standards for age assessment in Caucasians using third molar development.

London: University College London, MSc Thesis. Effects of ethnicity on skeletal maturation: consequences for forensic age estimations. Int J Legal Med ; 13 : — Dental maturity in children with chronic renal failure assessed from dental panoramic tomographs.

J Int Assoc Dent Child ; 20 : 54— A cephalometric analysis of patients with recessive dystrophic epidermolysis bullosa. Angle Orthod ; 72 : 55— The coronal pulp cavity index [ 86 ] calculates the correlation between the reduction of the coronal pulp cavity and the chronological age. Only mandibular premolars and molars were considered on panoramic radiographs. The tooth-coronal index TCI is calculated for each tooth and regressed on the real age of the sample using the formula.

Pulp-to-tooth ratio method : Kvall et al. It is available to remove doubt as to whether a person is under 18 years of age and to calculate the age above this level. They measured pulp length and width as well as root length and width. Because of magnification and angulation on the radiographs, different ratios between root and pulp were measured.

Level A, the level of the cementoenamel junction CEJ. Level B, midpoint between levels A and C. Level C, mid-root level between the CEJ and root apex. Also, the most marked reduction in volume ratio was observed between the second and the fifth decades of life in lower first and second premolars and between the second and the third decades of life in lower first premolars [ 87 ].

This method is limited in finding the subjects retaining all the six teeth that were measured in this method. Also, there will be a certain amount of distortion when the curved arch of the jaws is projected on to a flat film.

It would be better to use the parallel technique. Rotated teeth, teeth with enamel overlap, teeth with restorations, cavities, attrition and periapical pathological process cannot be used in this method, as well.

Vandevoort et al. Yang et al. It includes the most accurate and often referenced morphological and radiological techniques that are reported in literature.

The great advantage of the program is the immediate dental age estimation results. The borders of the pulp and tooth are automatically selected that minimizes the required time to obtain the area of tooth and pulp chamber, in addition, avoiding the calculating errors, the error associated with the observer, when performing the area selection reduces [ 89 ]. Also it enables the forensic odontologist to apply different techniques and provides a more reliable result.

Cameriere et al. Given that, upper canines have certain advantages, such as their longer survival, less wear and the big size of the pulp chamber [ 91 ]. Once dental development is complete, developmental stages could not be used for age estimation instead the indicators showing that dental structures undergo changes through life are being used. Morphological methods are based on assessment of ex-vivo teeth for age estimation of adults.

The samples of the extracted tooth can be sectioned or unsectioned and observed with the eye or with microscope [ 1 ]. However, these methods may not be acceptable due to ethical, religious, cultural or scientific reasons. In literature, many morphological methods are encountered. Gustafson [ 92 ], Dalitz [ 93 ], Bang and Ramm [ 94 ], Johanson [ 2 ], Maples [ 95 ] and Solheim [ 96 ] developed various morphological methods.

The first technique was published by Gustafson in [ 92 ]. Gustafson [ 92 ] and Thoma [ 97 ] described the morphological changes occurring in the dental tissues by increasing age and noted the following changes: Attrition of the incisal or occlusal surfaces due to mastication [A].

Each criterion was ranked and allotted 0, 1, 2 and 3 points. The score values of each age change are added according to the following formula:. This method cannot be used in a living person, only in dead when extraction of a tooth is allowed [ 96 ]. It is a subjective method [ 94 ] and time-consuming [ 95 ]. Periodontitis is often impossible to determine due to the decomposition of a soft tissue [ 95 ].

It neglects the possible interrelationships among the criteria [ 94 ] and population differences in diet habits with a resultant effect of attrition on tooth. He mentioned that root resorption and secondary cementum formation could be disregarded.

In this method, 12 anterior teeth are evaluated; bicuspids and molar teeth are not taken into account. Johanson made a more detailed study of the root transparency and stated that it is more clear when the thickness of the ground section of the tooth was 0. Where A is attrition, S is secondary dentine formation, P is periodontal attachment loss, C is cement apposition, R is root resorption and T is apical translucent [Q]. He recommended not using this method on mandibular canines and second premolars because of the weakest relationship between the parameters and age on these teeth.

Two set of formulas were presented: one including sex and color and the other without them, because these factors were not always determinable in deceased individuals. The color may be differentiated due to changes or reactions to the environment and compared with teeth from living individuals; teeth removed from deceased bodies were darker. Bang and Ramm [ 94 ] presented a simple and accurate method for age estimation based on the measurement of only one criterion: the length of the apical translucent zone of only incisors and cuspids Figure 5.

Apical translucent zone. The authors mentioned that transparency of the root dentin advances during the third decade starting at the tip of the root and extending coronally with age.

The teeth were sectioned. The length of the root was measured buccally from the cementoenamel junction to the apex. With this method, good results are obtained by measuring intact roots only. The method is simple, objective and rather fast compared to other methods and can be applied without extensive training or expensive equipment.

However, it was difficult to make accurate measurements in molars and bicuspids [ 94 ]. Differently, not only the translucency but also the periodontal tissue level is determined as well. And the measurements are made only on the entire extracted single rooted tooth—the incisors or canines—without any preparation. In their method, the age in years at death is obtained by the following formula:. This method is simple and differences between observers are low.

However, it is not suitable in young adults as the translucency due to the deposition of hydroxyapatite crystals in the dental tubuli begins after the age of In addition, it gives unreliable age estimation on elder subjects with periodontal disease. The major adversity of this method is the absence of single root tooth that is frequently seen in the elderly or disturbed skeletal remains.

Also, it has to be taken into consideration that if there is a long postmortem interval [at least decades] the translucency of the root might be affected by taphonomic factors. With this method, researcher error is expected to be lessened.

Teeth with broken crowns, lost cementum and periodontal attachment may still give accurate age estimates. As it does not evaluate the attrition, the bias due to the dietary differences is expected to be decreased [ 41 ]. In prenatal stage, up to 6 months, radiological methods cannot be accurate in dental age estimation given that the dentin and enamel images are radiolucent. It was demonstrated that the dry weight of the mineralized tooth cusps gives an approximate age of the child by using gravimetric methods.

Fetal age is linearly related to the square root of the weight of mineralized tissue in the deciduous anterior teeth during the last trimester. At 6 months intrauterine life, the weight is 60 mg; in the newborn child, the teeth weigh 0. Deutsch et al. In adults, following completion of the growth period, age estimation by radiological methods becomes not sufficiently accurate [ 10 , ]. Alternative methods such as biochemical and histological methods are preferred in adults. The biochemical methods determine alterations in ion levels with age.

In literature, aspartic acid racemization [ , ] has been studied for the aim of developing age estimation standards in adults. Although aspartic acid racemization is affected by environmental factors, such that with increasing temperature, racemization increases also, it is demonstrated to be an accurate age estimation method [ ]. However, the mentioned method is invasive and expensive and also requires specialized equipment and expertise [ , ].

In addition, it is not suitable in living individuals [ ]. The biochemical methods are based on the racemization of amino acids. The racemization of amino acids is a reversible first-order reaction and is relatively rapid in living tissues in which metabolism is slow. Aspartic acid has been reported to have the highest racemization rate of all amino acids and to be stored during aging.

In particular, l -aspartic acids are converted into d -aspartic acids, and so, the levels of d -aspartic acid in human enamel, dentine and cementum increase with age. The racemization rate of the cementum shows the fastest reaction than enamel and dentine. On the other hand, dentine showed the highest correlation with actual age [ ]. With this method, age determination is not suitable with extensive crown destruction in postmortem examination [ ] rather than the extraction of the teeth.

Ritz et al. The extension of aspartic acid racemization is higher in deep layers, so biopsy layer had a noteworthy influence. The cavities are then treated with filling materials. This technique is more appropriate for postmortem situations. In prenatal stage, up to 6 months, the dentin and the enamel images are not radiopaque enough to be visualized on radiographs. The histological methods can detect mineralization before being detected in the radiographs. Prenatal dental maturity can be assessed by using dissection and alizarin staining of fetal tooth germs [ 9 ].

Initiation of mineralization, as visualized by alizarin staining, takes place in the first permanent molars between 28 and 32 fetal weeks with the mandibular germs being slightly in advance than those of the maxilla [ 9 ].

The estimation period of survival of an infant in perinatal period using neonatal line as a line of reference can give the exact age of the baby in days [ ]. The neonatal lines, present in both enamel and dentin of the permanent teeth, are an optical phenomenon produced due to alteration in the dimension, degree and mineralization of enamel prisms caused due to the sudden change from intrauterine to extrauterine environment [ ].

Observing the neonatal lines can be used for assessing the amount of pre- and postnatal enamel formation. In primary enamel, the rate of enamel formation is 2. Cross striations are seen across enamel rods representing the daily incremental deposition of enamel [ ], and this can be used to find the exact age of the baby in days by counting the cross striations from the neonatal line [ ]. Neonatal lines can be used to differentiate between live birth and still birth and are an important tool in forensic cases and for preepidemiological studies.

However, the absence of the neonatal line is not always an indicator of still birth [ 30 ]. The main limitation of using neonatal line for estimation is that a couple of days of survival is necessary for the neonatal line to develop.

Besides, the detection of neonatal line depends on various factors like axis of tooth section, thickness of the section and light source used. Cementum annulations indeed are a reflection of age, as well. The incremental lines in the tooth cementum can be used as a marker more reliable than any other morphological or histological traits in the human skeleton [ 4 , 51 ].