Sub-Adult Age: Tooth Formation and the London Atlas

From Demirjian's eight-stage scoring system to AlQahtani's London Atlas, sub-adult dental age estimation is the most precise window in forensic odontology. This topic explains the main methods, their stages, and how they are applied from panoramic radiographs.

Last updated: 9 Jun 2026

Of all the age windows that forensic odontologists work in, the sub-adult years are the most precise. A radiograph of a twelve-year-old's developing teeth carries enough information to put that child within two years of their true age, often tighter. The reason is that multiple teeth are forming simultaneously on a predictable schedule, and each tooth at each stage of development provides an independent data point. Cross-check enough of them and the estimate narrows.

The methods available for this window range from the classic Moorrees, Fanning, and Hunt stages of 1963, through Nolla's ten-stage system for permanent teeth, to the Demirjian eight-stage scheme that became the field's workhorse after 1973. More recently, AlQahtani, Hector, and Liversidge published the London Atlas of Tooth Development and Eruption in 2010, which unified formation and eruption data into a single visual reference derived from an exceptionally large skeletal sample. Each method has its strengths and its known biases.

This topic walks through the practical mechanics of sub-adult dental age estimation, stage by stage, from the first signs of deciduous calcification in the embryo to the last closed third-molar apex in the early twenties. It explains what each method scores, how the scores become age estimates, and where the population-fit problem bites hardest.

Key terms

Demirjian stages (A-H): Eight illustrated calcification stages covering a tooth from initial cusp formation (A) to complete root apex closure (H), scored from a standardised radiographic view. Developed by Demirjian, Goldstein, and Tanner in 1973 from a Montreal reference sample.
London Atlas: A visual atlas published by AlQahtani, Hector, and Liversidge in 2010 showing expected tooth development and eruption for all deciduous and permanent teeth from birth to age 23.5, derived from a large documented skeletal collection.
Calcification stage: A discrete described increment of tooth mineralisation, from initial deposition of the crown cusps through completion of root and apex. Calcification staging is performed on radiographs and is the primary sub-adult age signal.
Eruption sequence: The order in which teeth emerge into the oral cavity. Less precise than calcification staging because eruption timing shows more individual variation, but useful when only clinical examination is available.
Panoramic radiograph: A single wide-field dental X-ray showing all teeth simultaneously in both jaws. The standard imaging tool for sub-adult dental age assessment because it shows every tooth's formation stage at once.
Population bias (dental methods): The systematic difference between the reference sample on which a method was calibrated and the study population to which it is applied. Demirjian's original sample was French-Canadian; applying it to other populations without adjustment tends to overestimate age.

Deciduous development: prenatal to age 6

The first teeth start forming six weeks after conception, and their formation stages can pin a foetal age with surprising precision.

Calcification of the primary dentition begins in utero. The primary first molar and central incisor show initial mineralisation at around 14 weeks of gestational age. The primary second molar is the last to initiate, typically at 18-19 weeks. Because the timing is well-documented and varies less than many other fetal biometric parameters, the state of deciduous tooth mineralisation on a radiograph or CT of perinatal remains is a useful age indicator.

By birth, all twenty primary crowns are partially formed. Root development continues postnatally, with the last primary roots closing (the deciduous second molar roots) at approximately 2.5 to 3.5 years of age. The primary teeth then serve as the age reference for the preschool years. Their eruption timeline, from the lower central incisor at around 6-8 months to the upper second molar at 25-33 months, provides a rough ladder for early childhood age estimation without radiography.

The Demirjian system: stages, scoring, and how to use it

Eight stages, seven teeth, one panoramic radiograph.

Arto Demirjian and colleagues published their staging system in 1973, derived from longitudinal radiographic data on 1,446 French-Canadian boys and girls aged 2-20. The system scores the seven permanent teeth in the left mandibular quadrant (central incisor, lateral incisor, canine, first and second premolar, first and second molar) against eight stages illustrated in the original paper.

Stage A: Initial cusp points
Mineralisation begins at the tip of one or more cusps. No fusion of separate calcification centres yet visible.
Stage B: Cusp fusion
Mineralisation of the cusps has fused to outline the tooth crown shape. No dentine is visible yet.
Stage C: Crown one-third complete
Dentine is visible at the occlusal surface. Crown formation is about one-third complete.
Stage D: Crown complete to the cervical margin
The crown is complete down to the cementoenamel junction. Root formation has not yet begun.
Stage E: Root length less than crown length
Root formation has begun. The root length is shorter than the crown length. Walls of the root canal are still diverging.
Stage F: Root length equals crown length
The root walls are now parallel. The apex is still wide open.
Stage G: Root complete, apex still open
The root has reached its final length. The apical canal walls are still diverging slightly; the apex is not yet closed.
Stage H: Apex closed
The apex is fully closed. The periodontal ligament space around the apex is uniform in width. This is the final stage.

Each stage score is converted to a numerical value using sex-specific tables. The seven tooth scores are summed to a total, which is then looked up in the reference population chart to yield a dental age. The main limitation is the reference sample: applying the original French-Canadian tables to other populations introduces a systematic overestimation of age that ranges from a few months to more than a year in some groups. Multiple regional recalibrations exist, and choosing an appropriate one is methodologically important.

Demirjian scoring workflow for sub-adult age estimation.

Moorrees, Fanning, Hunt and the Nolla method

Fourteen stages for the detail-oriented, ten stages for a simpler count.

Before Demirjian, the dominant staging system was published by Moorrees, Fanning, and Hunt in 1963. Their scheme describes 14 stages of formation for multi-rooted teeth (and a slightly smaller number for single-rooted teeth), giving more granularity in root development than Demirjian's eight-stage system. The stages include intermediate points like 'root one-quarter complete' and 'root three-quarters complete' that sit between Demirjian's broader E, F, G categories.

The additional granularity has a cost in reproducibility. Observer agreement on the finer Moorrees stages is lower than on Demirjian stages, and the reference data is older and drawn from a smaller sample. In current practice, the Moorrees system is most commonly used as a supplemental check or when working with isolated teeth that cannot be scored by the seven-tooth Demirjian scheme.

Nolla's ten-stage system (1960) was developed from a Michigan longitudinal study and scores each permanent tooth individually on a scale from 0 (absence of crypt) to 10 (apex closed). It provides a simpler single-tooth score that is useful when only one or two teeth are available for assessment. The Nolla method is less widely used in forensic contexts than Demirjian but remains part of the method repertoire.

The London Atlas: unifying formation and eruption

A visual atlas built from a skeletal collection, not a living study, changes what the reference data can tell us.

In 2010, Sakher AlQahtani, Martin Hector, and Helen Liversidge published the London Atlas of Tooth Development and Eruption. The atlas was derived from 704 documented individuals from the Grant Collection at the University of Toronto and the Spitalfields Collection at the Natural History Museum, London. Both are skeletal collections with verified ages at death, which means the atlas charts are anchored to true age rather than to self-reported age or parental report.

The atlas presents a chart for each year of age from birth to 23.5 years, showing the expected state of every tooth crown and root in both jaws. An analyst compares the patient's panoramic radiograph to the illustrated age stages and selects the closest match. The visual matching format makes it accessible and fast, and inter-rater agreement is reported as good. The atlas also integrates eruption into the same visual reference, which is useful when formation data and eruption status can be checked against each other.

London Atlas visual matching approach.

The third molar: the last sub-adult marker

When only wisdom teeth remain forming, the error band widens and the stakes often rise.

By the mid-to-late teens, all other permanent teeth have completed formation. The third molar is the only tooth still developing and therefore the only developmental age marker available for individuals aged approximately 14-22. Its formation stages can be scored using the same Demirjian scheme or other systems, but the third molar is notoriously variable in both its presence (15-25% of populations show agenesis of at least one) and its developmental timing.

The forensic importance of the third molar is acute precisely because this is the age window where legal thresholds concentrate: the juvenile/adult divide in criminal justice, the age of majority for immigration, and the 18-year threshold in child protection. This creates a tension between the demands of the legal system and the inherent imprecision of the only biological marker available in this range. The question of whether third-molar staging alone can reliably distinguish under-18 from over-18 is one of the most actively debated in forensic odontology, and is covered fully in the topic on living-person age assessment.

Worked example

Age estimation on an unknown child from a humanitarian context

When a panoramic radiograph is available and the child's documents are not.

A paediatrician requests a dental age assessment for a child who arrived without documentation. Clinical examination shows a full primary dentition with the first permanent molars and lower central incisors recently erupted. No panoramic radiograph is available yet, but a bitewing series is taken.

From the clinical examination alone, the eruption pattern is consistent with approximately 6-7 years. The first permanent molars and lower central incisors erupt at around 6-6.5 years on average. The bitewing confirms that the upper central incisors are beginning to erupt and the upper first molars are fully erupted. The first premolars and second premolars are not yet visible in the mouth.

London Atlas comparison. The bitewing stages for the visible permanent teeth are compared to the London Atlas reference charts. The state of the first molar roots and the partial eruption of upper central incisors best matches the 6.5-7 year chart pages.
Eruption cross-check. The eruption state (lower central incisors and first molars fully erupted, upper central incisors beginning emergence) is consistent with 6-7 years in the London Atlas eruption reference.
Estimate and uncertainty. The combined estimate is 6-7.5 years. A full panoramic radiograph would narrow this further by showing all developing teeth and enabling a Demirjian score, which is recommended as the next step.

The report notes the limitation of bitewing-only assessment and recommends the panoramic follow-up. The purpose of the assessment is humanitarian documentation, not a criminal threshold determination, so the wider range is acceptable for the current stage. This illustrates how the goal of the assessment shapes how precisely you need to push and which methods are worth the clinical burden.

Check your understanding

Question 1 of 4· 0 answered

In the Demirjian system, how many teeth are scored, and which jaw?

Key Takeaways

The Demirjian system scores seven left mandibular teeth on eight stages (A-H) from calcification onset to apex closure, converting scores to age via sex-specific reference tables; its main limitation is a French-Canadian reference sample that overestimates age in many other populations.
Moorrees, Fanning, and Hunt's 14-stage system provides more granularity in root formation than Demirjian but with lower observer reproducibility; Nolla's 10-stage system scores individual teeth and is useful when few teeth are available.
The London Atlas (AlQahtani, Hector, Liversidge 2010) offers a visual reference for all deciduous and permanent teeth from birth to 23.5 years, anchored to verified skeletal-collection age data and integrating both formation stages and eruption.
The third molar is the sole developmental marker after age 14 and shows high variability; third-molar agenesis occurs in roughly one-fifth of individuals and must not be misread as an age indicator.
Accuracy is tightest in the mixed-dentition years (typically one to two years); all sub-adult reports should state the reference population used and any population-fit limitations.

What are Demirjian stages?

Demirjian stages are eight calcification stages (A through H) that describe the progressive mineralisation of a tooth from initial cusp formation to apex closure. Developed by Arto Demirjian and colleagues in 1973 from a Montreal French-Canadian sample, they remain the most widely used sub-adult dental age system.

What is the London Atlas of Tooth Development and Eruption?

The London Atlas, published by AlQahtani, Hector, and Liversidge in 2010, is a visual reference chart that maps the development and eruption of all deciduous and permanent teeth from birth to age 23.5 years. It was derived from a large skeletal collection and uses direct age-at-death data rather than a living study population.

What is the difference between the Moorrees, Fanning, and Hunt stages and the Demirjian stages?

Moorrees, Fanning, and Hunt (1963) described 14 stages of formation for multi-rooted teeth, providing more granularity in root development than Demirjian's eight stages but at the cost of greater observer variability. Demirjian's eight stages are simpler and more reproducible, which is why they dominate clinical and forensic use.

How is a Demirjian assessment performed in practice?

An analyst scores the seven left mandibular teeth on the panoramic radiograph against the eight-stage illustrated criteria. The stages are converted to a numerical score using sex-specific tables, and the summed score is looked up against the reference population table to yield an age estimate.

When is eruption status more useful than calcification stage?

Eruption status is particularly useful when a radiograph is unavailable but clinical examination is possible. However, eruption is more variable than calcification, so calcification staging is preferred when radiographs are available.

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Key Takeaways

The Demirjian system scores seven left mandibular teeth on eight stages (A-H) from calcification onset to apex closure, converting scores to age via sex-specific reference tables; its main limitation is a French-Canadian reference sample that overestimates age in many other populations.

Moorrees, Fanning, and Hunt's 14-stage system provides more granularity in root formation than Demirjian but with lower observer reproducibility; Nolla's 10-stage system scores individual teeth and is useful when few teeth are available.

The London Atlas (AlQahtani, Hector, Liversidge 2010) offers a visual reference for all deciduous and permanent teeth from birth to 23.5 years, anchored to verified skeletal-collection age data and integrating both formation stages and eruption.

The third molar is the sole developmental marker after age 14 and shows high variability; third-molar agenesis occurs in roughly one-fifth of individuals and must not be misread as an age indicator.

Accuracy is tightest in the mixed-dentition years (typically one to two years); all sub-adult reports should state the reference population used and any population-fit limitations.

What are Demirjian stages?

What is the London Atlas of Tooth Development and Eruption?

What is the difference between the Moorrees, Fanning, and Hunt stages and the Demirjian stages?

How is a Demirjian assessment performed in practice?

When is eruption status more useful than calcification stage?

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Key Takeaways

Key Takeaways