Age assessment using molars debunked

Anisha Hall Hoppe, Dental Tribune International

Fri. 11 August 2023

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MALMÖ, Sweden: Determining an individual’s age plays a pivotal role in various medical, legal and anthropological contexts. Traditionally, the development stage of mandibular third molars, specifically Demirjian’s Stage H, has been a tool for such assessments. Researchers in Sweden have conducted a systematic review to examine the reliability of this dental method from statistical, clinical, technical and ethical viewpoints and have found an overwhelming lack of scientific evidence of its validity as an assessment of age.

In 1973, Demirjian et al. introduced a method for assessing chronological age based on dental maturity, distinguishing eight developmental stages (A–H) in tooth formation. Initially, the method was applied to seven permanent teeth in the mandible and later the eighth permanent tooth, the third molar, was incorporated. This tooth is particularly significant in forensic age evaluations for older adolescents and young adults.

Demirjian’s stages of tooth formation are scored using panoramic radiographs, and proper positioning of the patient is crucial for capturing quality images. These radiographs enable dentists to classify the developmental stage of a third molar, using reference data sets to estimate chronological age. Of particular note are Stages G and H. In Stage G, the apices of the root remain open, whereas in Stage H, they close, marking the tooth’s complete formation. While factors like sex, ethnicity and genetics influence tooth formation, environmental stresses usually have minimal effect, but nutrition, high fever episodes and certain drugs can impact tooth morphogenesis.

Researchers at Malmö University and the Swedish Agency for Health Technology Assessment and Assessment of Social Services sought to investigate the correlation between a fully matured mandibular third molar according to Demirjian’s method and chronological age. The core question was the reliability of using Demirjian’s Stage H to determine whether someone has reached 18 years of age.

The review included 15 studies, which spanned 13 countries and involved participants aged 3–27 years. The findings highlighted that, at 18 years of age, the proportion of individuals with a mandibular third molar in Stage H ranged from 0% to 22% for males and 0% to 16% for females. The review could not definitively link Demirjian’s Stage H development of the mandibular third molar with chronological age, indicating that it is unreliable to use this method to determine whether someone is younger or older than 18. Clinically, third molar development rates were found to differ across populations, and their presence is inconsistent owing to congenital absence or other dental issues.

From a technical perspective, image quality is crucial, but radiographs might have undetectable distortions, which affect reliability. Advanced methods like machine learning could revolutionise age assessment in the future, potentially outperforming the traditional manual Demirjian method.

Ethically, using third molar maturity for age estimation presents issues regarding knowledge gaps, consent and potential long-term consequences. The authors suggested that future studies ensure observer training and blinding of radiographs.

The study, titled “How old are you? A systematic review investigating the relationship between age and mandibular third molar maturity”, was published online on 18 May 2023 in PLOS ONE.