Estimation of age from teeth is quite a viable tool in human identification. There are many age determination methods to determine the relative age of a person, and with this article, we try to cover all the dental age estimation techniques that are important for the examination point of view.
So, in this concise article on the age estimation from teeth, we are going to list down all the techniques along with tables for the age determination of child, adolescent, and adult.
Importance of Age Estimation by Teeth
These are mainly the three-pointers that can state why age estimation from teeth is important?
- With a relative estimated age, the search can be significantly narrowed down which increases the chance of identification.
- When there is a case of mass disaster or any cluster victim situations, determining the age from the teeth is generally employed for the identification.
- Determination of age from teeth can be also helpful to law enforcement to aid cases such as child labor, status of minority, rape, adoption, eligibility for marriage, etc. when there is no legal birth certificate is issued or available.
Age Estimation from Teeth Before 25 Years
There are many dental age determination techniques but the majority of them can estimate a person’s age (before 25 years) by visual analysis and incremental counting measures.
In the visual age determination technique, visual observation of the eruption and calcification of the teeth is used to depict the stage of development of teeth.
The visual method of age determination is based on the sequence of eruption and morphological changes such as attrition, change in color, etc. which is an indicator of aging.
Note: Age of eruption of teeth depends upon heredity, environment, nutrition, and endocrine factors.
These are the list of tables that are important as per the examination point of view. So, surely bookmark the page for future references.
Difference between Temporary and Permanent Teeth
|S.No.||Traits||Temporary Teeth||Permanent Teeth|
|1||General||Smaller, lighter, narrower, except temporary molars which are longer than permanent premolars||Heavier, stronger, broader, except permanent premolars|
|2||Direction||Anterior teeth are vertical||Anterior teeth are inclined forward|
|3||Ridges||Present at the junction of crown and root||No ridges|
|5||Root||Roots of molars are smaller, more divergent||Roots of molars are larger, less divergent|
|6||Incisors||Smooth incisal edge||Ridged, especially on incisal surface|
|7||Neck||More constricted||Less constricted|
Age Estimation from Eruption of Temporary (Deciduous/Milk) Teeth
|S.No.||Tooth||Number of Teeth||Eruption (months)|
|1||Lower Central Incisor||2||6–8|
|2||Upper Central Incisor||4||7–9|
|3||Upper Lateral Incisor||6||7–9|
|4||Lower Central Incisor||8||10–12|
Age Estimation from Eruption of Permanent Teeth
|S.No.||Tooth||Eruption (in Years)|
Age Estimation from Calcification of Temporary (Deciduous/Milk) Teeth
|S.No.||Tooth||Calcification Starts||Calcification of Root Completed||Resorption of Root Begins|
|1||Lower Central incisor||5–6 months||1 year 6 months to 2 years||4th year|
|2||Upper Central incisor||5–6 months||1 year 6 months to 2 years||5th year|
|3||Upper Lateral incisor||5–6 months||1 year 6 months to 2 years||5th year|
|4||Lower Central incisor||5–6 months||1 year 6 months to 2 years||5th year|
|5||First Molar||5–6 months||2 years to 2 year 6 months||6th year|
|6||Canine||5–6 months||2 year 6 months to 3 years||8th year|
|7||Second Molar||5–6 months||3 years||7th year|
*Calcification is the process of the deposition of calcium salt on the dental enamel.
**Resorption is the term associated with the loss of a part or whole tooth.
Age Estimation from Calcification of Permanent Teeth
|S.No.||Tooth||Calcification Starts||Calcification of Root Completed|
|1||First Molar||At birth||9 to 10 years|
|2||Central Incisor||3 to 4 months||10 years|
|3||Lateral Incisor||1 year||11 years|
|4||First Premolar||1 year 6 months||12 to 13 years|
|5||Second Premolar||2 years||12 to 14 years|
|6||Canine||4 to 5 years||12 to 13 years|
|7||Second Molar||2 years and 6 months to 3 years||14 to 16 years|
|8||Third Molar||8 to 10 years||18 to 25 years|
Age Estimation using Dental Crown Formation of Temporary Teeth
|S.No.||Tooth||Crown Formation Completed|
|1||Lower Central incisor||12 to13 weeks|
|2||Upper Central incisor||6 to 7 weeks|
|3||Upper Lateral incisor||12 -13 weeks|
|4||Lower Central incisor||3 months|
|5||First Molar||6 month|
|7||Second Molar||10 to 11 months|
Age Estimation using Dental Crown Formation of Permanent Teeth
|S.No.||Tooth||Crown Formation Completed|
|1||First Molar||2 year 6 month to 3 years|
|2||Central Incisor||3 to 5 years|
|3||Lateral Incisor||4 to 5 years|
|4||First Premolar||5 to 6 years|
|5||Second Premolar||6 to 7 years|
|6||Canine||6 to 7 years|
|7||Second Molar||7 to 8 years|
Age Estimation in the Period of Mixed Dentition
Mixed dentition is a period where both the temporary and permanent teeth are present. And this time duration is called the period of mixed dentition.
In general, the period of mixed detention starts from the day of the eruption of the first permanent molar to the eruption of the last permanent canine which usually has a time phrase of 6 to 11 years, but in some cases persistent until 12 to 13 years.
Age Determination Based on Number of Teeth
|S.No.||Age (years)||No. of Teeth||Feature||Type of Dentition|
|2||6||21–24||Eruption of 1st permanent molars||Mixed|
|3||7–9||24||12 permanent– 8 incisors, 4 molars | 12 deciduous—4 canines, 8 molars||Mixed|
|4||10||24||16 permanent—8 incisors, 4 molars, 4 premolars | 8 deciduous—second molars and canines||Mixed|
|5||11||24||20 permanent—8 incisors, 4 molars, 8 premolars | 4 deciduous—canines||Mixed|
|6||12–14||25–28||Eruption of 2nd permanent molars||Permanent|
|8||17–25||29–32||Eruption of 3rd molars||Permanent|
Age Estimation by Teeth for Infants and Fetus
Generally, there are two methods of age determination of infant and fetus but both are viable only in the case of a dead infant. These methods are:
- Stack’s method
- Boyde’s method
Stack’s Method of Age Estimation of Infant and Fetus
Stacks’ method of age determination from teeth is based on the weight of the erupting teeth of infants and fetuses.
According to him, by weighting the teeth, age estimation can be done but only with the age in between 5 months in utero to postnatal age of 7 months. The following is the table for Stack’s method.
|S.No.||Age (weeks)||All teeth weight (mg)|
Boyde’s Method of Age Estimation of Infant
In Boyde’s method of age estimation, counting the number of cross striations on the enamel of the teeth (also called incremental lines) from the neonatal line onwards can depict the age of the dead infant.
These neonatal lines are formed soon after the birth and can be seen using an electron microscope within 1-2 days of infant birth. And with the naked eye, it can be seen in about 3 weeks.
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Age Estimating Techniques From Teeth Beyond 25 Years
There are basically five common methods for determination of the age of the person using teeth beyond 25 years. These are listed below:
- Gustafson’s Method
- Miles Method
- Aspartic Acid Racemization
- Chemical Method
- Radiocarbon Dating
Gustafson’s Method for Age Estimation from Teeth
Gustafson’s method of age estimation depends on the physiological changes encountered in the dental tissues which are merely interpreted by the microscopic examination of the longitudinal section of the central part of the tooth. These physiological changes are due to the wear and tear of the teeth with aging.
The most favorable age group for dental age estimation using Gustafson’s method is 25 to 60 years. It is also noted that the Gustafson method is only employed in the case of a dead body or skeletal remains because the teeth are needed to be extracted for the examination.
Moreover, there are a total of six criteria that are used for the age estimation using Gustafson method, listed as:
1. Attrition: Wear and tear of the occlusal (upper) surface of the teeth followed by enamel, then dentin, and lastly the pulp. Attrition depends generally on two factors: one is the daily use of teeth, and the other is the hardness of enamel.
2. Periodontosis: Retraction of the gum and periodontal tissues that surround the teeth results in a loosen gum margin exposing the necks and the adjacent part of roots. Periodontitis is due to poor oral hygiene.
3. Secondary Dentin: Progressive infilling of the walls within the pulp cavity, and decreasing the size of the cavity which also may cause complete obliteration of it. In this process, the deposition is first seen at the pulp chamber and gradually extends downwards to the apex, which might also completely fill the pulp cavity. Contributing factors are aging and pathological conditions like dental decay and periodontitis.
4. Cementum Apposition: Increase in cementum thickness near the end of the root, mainly because of the change in tooth position which tends to continuously deposit throughout life. These depositions are in the form of incremental lines as cross striation on the enamel.
5. Root Resorption: Characteristically sharp grooves are shown on both cementum and dentin. Root absorption begins from the apex and extends upwards. They are relatively seen in the late ages and are mainly due to some pathological changes.
6. Root Transparency: It is the most reliable criterion among all the Gustafson criteria. Root transparency is generally not seen until about 30 years of age and is generally due to rarefaction of the dentin tissue. In the lower jaw, it occurs from below upwards while in the upper jaw from above downwards.
Procedure for Estimating Age using Gustafson’s Method
The following is the step-by-step procedure for the age determination from teeth using Gustafson’s method.
- Estimated the degree of periodontitis before extracting the tooth.
- Now, the tooth is grounded down about 1mm on glass slabs from both sides for estimation of transparency.
- Further, 1/4th mm of the tooth is grounded down for the microscopic examination.
Gustafson’s Allocations Points along with Structural Changes
Allocation of points: Based on the degree of changes, 0-3 points are allotted
- 0 indicates ‘No’ change
- 1 indicates ‘Beginning’ of change
- 2 indicates ‘Obvious’ change
- 3 indicates ‘Maximum’ change
|S.No.||Criteria||Ranking and Details|
|1.||Attrition (A)||A-0: No attrition|
A-1: Attrition lying within the enamel
A-2: Attrition reaching the dentin
A-3: Attrition reaching the pulp
|2.||Periodontosis (P)||P-0: No periodontosis|
P-1: Periodontosis just begun
P-2: Periodontosis along first 1/3rd of root
P-3: Periodontosis along 2/3rd of root
|3.||Secondary Dentin (S)||S-0: No deposition of secondary dentin tissue in the pulp cavity|
S-1: When secondary dentin tissue starts depositing at the upper part (in case of the lower jaw and reverse in case of the upper jaw) of the cavity
S-2: When about half of the pulp cavity from above is occupied by secondary dentin tissue
S-3: When almost whole of the cavity is filled by the dentin tissue
C-1: A layer little greater than normal
C-2: A thick layer
C-3: A heavy layer
|5.||Root Resorption (R)||R-0: No visible resorption|
R-1: Resorption only on small isolated spots
R-2: Greater loss of substance
R-3: More cementum and dentin affected
|6.||Root Transparency (T)||T-0: Transparency not present|
T-1: Transparency is just noticeable
T-2: Transparency over apical 1/3rd of root
T-3: Transparency over apical 2/3rd of root
• Anterior teeth are most suitable and the third molar is quite unsuitable. Meanwhile, the order of suitability is from anterior teeth to posterior teeth i.e merit decreases from incisors to premolars, and the third molar is the least viable tooth.
• All changes and criteria are absent at 15 years.
• Error is of ± 10–15 years.
• The limit of error increases above 50 years of age.
Miles’ Method for Age Estimation from Teeth
Miles’s method of age estimation is based on the comparison to the baseline of molars that is due to the wear of the three permanent molars which occur at a comparable rate.
He also proposed a method of age determination at death by measuring the thickness of enamel and dentin from the neonatal line and dividing it by the appropriate daily rate of formation.
Aspartic Acid Racemization for Dental Age Estimation
The foundation of age estimation from teeth using aspartic acid racemization is based on estimating the conversion of optically active aspartic acid into an optically inactive aspartic acid form.
For instance, aspartic acid is an organic chemical compound and a protein amino acid that is present in many human tissues including tooth dentin. And, these are the most prone to racemization due to their one asymmetric carbon atom resulting in two enantiomers L and D.
In short, the principle of aspartic acid racemization is that all living organisms contain the L form of enantiomer which over time gets partly converted into D form by racemization. So, when a person dies, this conversion stops and makes it possible to determine the relative age of the person at death by the extent of the racemization of amino acids.
In addition, the aspartic acid racemization technique for age determination is more accurate than other eruption techniques because of its chemical nature. Moreover, a standard estimation error using this method is ±2.95–4.84 years.
• Amino acid racemization is considered to be the most reliable destructive method of dental age estimation.
• Both tooth enamel and crown dentin is used for the analysis. However, the analysis of dentin gives a more accurate age estimation than enamel.
Other Chemical Method of Age Determination by Teeth
The estimation of a specific component of teeth chemically can lead to an estimated age group of the person. Some of the common chemical measures to estimate the age using teeth are:
- Nitrogen content increases with age. So, quantitative estimation of the nitrogen content of enamel could lead to relative age.
- Carbonate content decreases with age.
- The concentration of ions such as copper, selenium, and iron increase with age.
|S.No.||Elements||Trait with Age|
Radiocarbon Dating For Age Determination Using Teeth
With the use of radioactive 14C dating of teeth, a precise date of birth of the person can be determined. The technique relies on the naturally occurring process of 14C that is produced by cosmic rays interacting with atmospheric nitrogen.
Procedure for Dental Age Estimation from Teeth
While depicting the procedure for the dental age estimation, there are three distinct categories that are classified on the basis of age:
- Children (Birth to puberty)
- Adolescent (puberty to approx age 20)
Flow Chart for the Procedure of Dental Age Estimation of Children
To identify the dental age of the children, either living or deceased, there are a total of three common techniques i.e. visual method, radiographic method, and biochemical method.
In general, a visual method (based on the eruption of teeth) is employed for both living and deceased children. While radiographic and biochemical methods are used in the case of deceased children. The following is the flow chart for the age determination of infants and children.
Flow Chart for the Procedure of Dental Age Estimation of Adolescents
As the person ages to puberty, a majority of biological changes tend to happen, and as puberty reaches the age of 20, the changes are not that prominent that can help in depicting the age using teeth. Therefore, while estimating the adolescent age, there are two subdivisions of early adolescents and late adolescents.
In early adolescence, the age of a person can be determined with the help of visual, radiographic, and chemical methods. But in the case of late adolescence, the visual method is not a viable technique for the age estimation from teeth eruption and calcification.
Flow Chart for the Procedure of Dental Age Estimation of Adults
In the case of living adults, the morphological radiographic technique is useful while for deceased adults, along with morphological radiographs, the postformation technique can also be employed.
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Classification of Dental Age Estimation Techniques
These are some other dental age estimation techniques that are proven helpful in the determination of age from teeth.
Presence or Absence of Mamelons
The term “mamelons” is used to describe the protuberance humps present at the cutting edge of the permanent central and lateral incisors. As the child gets older these humps are smothered out by chewing over time.
As they are present on the permanent incisors, it can help in differentiating the temporary and permanent dentition and somehow also helps in age determination.
A study by Gorea et.al. (2010), conclusive correlates the relevancy of the mamelons in age estimation. Moreover, the study also points out that mamelons are majorly present in children of age 10 and they become smoother with the increase in age due to wear.
One other pointer is that mamelons are more prominent in lower central incisors and persist more in females than males.
Atlas Style of Dental Age Estimation
Atlas style of age estimation is generally a chart based on tooth development and alveolar eruption for individuals whose age is between 28 weeks in utero to 23 years. These are commonly three main atlas-based methods that are proposed by different authors, listed as:
- Schour and Massler Method
- Ubelaker Method
- Alqahtani Method
Schour and Massler Method
The Schour and Massler method is based on the histological analysis of teeth development from the age of 4 months to 21 years. They stated a numerical chart for their finding in 21 chronological steps. These findings are accounted for by the foundation of three major characteristics. These characteristics are:
- Teeth that have erupted
- Amount of resorption of roots of primary teeth
- Amount of development of permanent teeth
Ubelaker And Alqahtani Method
Ubelaker’s atlas method defines a tooth eruption from a point when the tooth emerges through the gingival tissue. Conversely, Alqahtani’s chart defines tooth eruption as the emergence through the alveolar bone.
Moreover, the Alqahtani atlas method is widely accepted for the determination of the age of children and adolescents based on dental development and alveolar eruptions. The Alqahtani atlas consists of a total of 31 diagrams with the age group of 30 weeks in utero to 23.5 years. In addition, this chart is more helpful in age determination after the age of 16 years.
Incremental Staging Method
In the incremental staging method, there are five techniques that are used for the age estimation using radiographs. These are
- Moorrees et al. Method
- Nolla’s Method
- Demirjian et al. Method
- Mincer et al. Method
- Anderson et al. Method
- Kohler et al. Method
- B.M. Balraj et.al Method
Moorrees, Fanning, and Hunt Method of Dental Age Estimation
According to the Moorrees et al. longitudinal radiographic study on the individuals from birth to the age of 20 years, the chronological dental age estimation can be depicted using the data of permanent mandibular posterior teeth and data related to developmental stages of permanent incisors.
In this age estimation technique, there are two major development schemes i.e. 13 stages of single-rooted teeth and 14 stages of development of mandibular molars. So, with this method, using developing single and multirooted staging of permanent teeth, the age of the person can be determined by taking the mean of corresponding stages.
Nolla’s Method of Estimation of Age from Teeth
In Nolla’s method of dental age estimation, the calcification of permanent teeth is illustrated by the 10 development stages i.e. from 1 to 10.
Nolla’s method is quite viable in finding the age of adolescents because his study relies on the series of radiographic studies on 25 girls and boys each, with an average age of 4.6 to16.6 years for boys, and 5.7 to 16.8 years for girls.
The major advantage of Nolla’s method is:
- Age can be estimated with or without the use of the third molar
- The data is categorized separately for girls and boys
Demirjian et al. Method
Demirjian et al. proposed a method that is widely accepted in 1973 and was called to be the seven teeth method which involves the age group of 2 to 20 years. Initially, this method involves the radiographic study (especially on orthopantomogram) of the mineralization of seven teeth (from the left of the central incisor to the second molar) with an eight developmental staging modal.
But later in 2004, Demirjian et al. included the third molar that extends the study to a wider age group. This also leads to the increment of two more developmental stagings resulting in a total of ten from 0 to 9. Moreover, each maturity stage score has a separate value for the boys and girls which again increases its acceptance.
• For the Indian population, the standard error rate is ±1.17 for males and ±1.6 for females.
• In the case where a tooth is missing from the left side, its analogous mandibular right side tooth can be used for radiographic age estimation.
Mincer et al. study is based on the radiographic study of the third molar to estimate the dental age of an individual between the age of 14 to 25 years. Moreover, the development of the maxillary third molar gives more promising results than the maxillary third molar.
The study also concluded that the root formation is seen earlier in females as compared to males. However, Mincer’s method for age estimation from teeth is generally used to predict whether a person is 18 years old or not.
Anderson et al. Method
Anderson’s method is similar to Moorrees et al.’s staging system but with a different nomenclature to the stages. This age determination system also uses maxillar and mandibular teeth including the third molar to evaluate the stages of mineralization. Anderson et al. study paints a four-chart system that assesses the ages for both the sexes separately.
The key finding of this study is that it states the order of variability in specific teeth for both sexes which decreases in the following order:
• For Males: 1st premolar and 3rd molars > 2nd premolar and 2nd molars > canine> incisors >1st molar
• For Females: 3rd molars > 2nd molars > canine and premolar > incisors > 1st molar.
Therefore, the most reliable tooth is the 1st molar because of the least variability that can be used in dental age determination of later childhood and early adolescence.
Kohler et al. Method
Earlier, Köhler’s method of age determination by teeth is based on the study of the maturation and development of all third molars. Later, in 1955, the method is modified by Gleiser and Hunt which now includes a grading system of 10 developmental stages.
Among 10 stages, 3 stages are used for grading the crown formation while the rest 7 stages grading is based on the root formation. With this method, the examiner can depict (with more accuracy) whether or not an individual’s age is more than 18 years.
B.M. Balaraj et.al Method
With the use of Demirjian’s method, Balaraj and Nithin conducted a radiological study describing the dental formation stages of the closure of apical foramen and the completion of root formation. The study conclusively shows the facts of determining the age of adolescents aged from 14 to 16 years using both of the permanent mandibular second molars. The key finding of the study are:
- For boys: In 94% cases, apical foramen closed at 15 years, 5 months.
- For girls: In 95% cases, apical foramen closed at 14 years, 9 months.
So, in the general scenario:
- For boys: Closed apical foramen means age is greater than 15 years. If open apical foramen, the age will be lesser than 17 years.
- For girls: Closed apical foramen means age is greater than 14 years while in case of open apical foramen, the age will be lesser than 16 years.
Therefore, with the B.M. Balaraj method of age estimation using mandibular 2nd molars, the medicolegal age of 14 to 16 years can be determined.
Open Apex Method of Dental Age Determination
Open Apex method is given by Cameriere et al. which is based on the relationship between the age and measurement of the open apex. The study is performed on an age group of 5 to 15 years old with seven left dentitions of permanent mandibular teeth, excluding the third molar.
The open apex method uses the ratio of the height of the calcifying teeth and the width of the “open” apex. Moreover, if teeth have an entirely developed root and closed apical ends, it is denoted by N0. Additionally, for teeth with two roots, the average of both distance is taken.
The calculation part consists of the sum of normalized open apices (s) and the numbers of teeth with root development complete (N0).
Age = 8.971 + 0.375 g + 1.631 × 5 + 0.674 N0 − 1.034 s − 0.176 s. N0
where g is a variable equal to 1 for boys and 0 for girls
‘S’ is the normalized open apices
The above-mentioned open apex method’s regression formula is a viable method for the estimation of dental age from 5 years to 15 years with a median residual error of 0.035 years.
Guidelines for Dental Age Estimation
The following are the guidelines that a forensic odontologist should follow that are developed by the American Board of Forensic Odontology, Age Estimation Committee (ABFO, 2012).
A. Identification Data
- Case number
- Referring agency
- Name of the examiner(s)
- Date of the examination
- If known, the individual’s name and stated date of birth
- Other pertinent informational dataDental Age Estimation
B. Evidence Collected and Measured
- Specific teeth used in the evaluation
- When known, the sex, ancestry, and population specificity
- Age estimation criteria include but not limited to
- Morphologic developmental staging
- Root translucency, secondary dentin apposition, attrition, or any other measured dental developmental or postformation characteristics
C. Other Information as Indicated
- Information from a dental examination
- Oral hygiene
- Nutritional health
- Systemic disease
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- K.S.N. Reddy, The Essentials of Forensic Medicine and Toxicology, [link]
- Manual of Forensic Odontology, CRC Press. [link]
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- ABFO Diplomates Reference Manual, 2012. [link]
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