A Call to End the Use of Dental Radiographs for Age Estimation

I was recently reminded of the intersection of dentistry and policy when I read an article in AJPH titled “Dental Radiographs for Age Estimation in US Asylum Seekers: Methodological, Ethical, and Health Issues.”¹ In this article, Kapadia et al. describe the policy of the US government whereby radiographs are taken to ascertain the chronologic age of unaccompanied minor children entering the country who do not have age documentation. The use of radiographs (likely panoramic radiographs, although it is not stated) to establish the relationship between dental age and chronologic age has been and continues to be extensively studied, debated, and employed for orthodontic, anthropologic, and, often, forensic purposes.^2–4 For asylum seekers entering the United States, age is a critical legal threshold—you are either younger than 18 years, in which case you are a minor and afforded those protections and social benefits, or you are 18 years old or older and have reached the age of legal majority. The authors succinctly discussed the ethical and legal implications of this radiographic determination, which are not well, if at all, known to most dentists in the United States. I would like to expand on the scientific basis for this procedure.

Orthodontists are taught that chronologic age is not an accurate way to determine the level of maturation. In William R. Profitt’s textbook Contemporary Orthodontics, it is noted that the correlation between dental and chronologic age is “one of the weakest.”⁵ In addition to other biological indicators, such as pubertal changes, orthodontists rely on the patient’s stage of dental development to assess overall growth and development. Determining a patient’s dental age from a panoramic radiograph is critical for timing treatment and recommending a treatment plan. Dental age and chronologic age are often not aligned, and there is significant variability in dental development not only by chronologic age but also by race/ethnicity and sex.⁶

There are significant concerns regarding the applicability of the specific radiographic method described, namely the “Demirjian method,” to assess chronologic age. In their 1973 seminal article “A New System of Dental Age Assessment,” Demirjian, Goldstein, and Tanner described and illustrated tooth formation as divided into eight stages (A–H).⁷ This classification is based on descriptive criteria and, although it has been modified, remains the best way to assess the dental maturity of an individual child. A dental maturity score indicates whether a child of known age is dentally advanced or delayed compared with the average same-sex child. This method, however, was never designed or intended to estimate chronologic age.⁸

Demirjian’s method was initially applied to a sample of French Canadian children aged 3 to 17 years. The development of seven left permanent mandibular teeth (central incisor to second molar) were rated on an eight-stage ordinal scale from “A” to “H.” Third molars were excluded. Currently, a modified Demirjian method is used to assess the root development of the mandibular third molar to determine whether an individual has reached 18 years. The third molar is used because it is the last tooth to complete development. In this modified classification system, two additional root stages (F1 and G1) were added to improve precision.⁹ If the individual has reached Demirjian stage “H,” she or he has likely reached the age of 18 years.³

Studies of different racial/ethnic populations in the United States show variation in the rates of third molar development.³ American Hispanics are approximately one half year ahead of American Whites, whereas American Blacks are one half year ahead of American Hispanics.⁹ In a study of third molar development in Hispanics, it was found that the mean absolute difference between chronological age and estimated age was plus or minus 3.0 years in females and plus or minus 2.6 years in males.⁹ In addition, the American Board of Forensic Odontology conducted a study of third molar development and concluded that third molars can develop up until the age of 30 years.¹⁰

A study comparing methods to estimate age based on third molar root formation concluded that most methods using third molar root formation had significant bias.¹ In fact, there is a large SD in third molar formation that translates into a 95% confidence interval of between four and six years.⁴ In addition, there is sexual dimorphism: among Hispanic children, males develop their third molars earlier than females.⁹ Overall in fact, third molar root formation and development occur earlier in males than in females—which is the opposite of what we expect for all other earlier-forming teeth.¹⁰ Age in individuals who are dentally advanced will be overestimated, and, conversely, age in those who are dentally delayed will be underestimated. Studies have found that there is consistent overestimation of age by Demirjian’s method.^11,12

Kapadia et al. state that the use of radiographs to assess chronologic age is often the “primary and exclusive” means of age verification for unaccompanied migrant minors.¹ This practice persists, despite its lack of accuracy and reliability, most likely because it is low cost and noninvasive. Several questions come to mind. Who is taking and reading these radiographs? Are they physicians, dentists? Are they trained and calibrated? Is intraobserver and interobserver reliability assessed? Who makes a decision if it is a borderline case? Is this practice justified given that the radiographs are not being used for diagnostic purposes and the determination method is not reliable? Are the individuals who are taking and reading these radiographs aware of the concerns about the misappropriation of this methodology? Is it ethical to expose a child to radiation for nondiagnostic purposes?

I was not aware of this practice of age determination, and I think that I am probably not alone. Although we are living in a highly polarized political climate, I do not think this is a matter of whether one is “red” or “blue.” What matters is the science and our roles as ethical health care providers. I believe it is the responsibility of dentists, and in particular orthodontists who specialize in the growth and development of human dentition, to bring attention to this practice. In Europe, where there are also many asylum seekers, the practice of chronologic age determination by radiographic means has been denounced for both scientific and ethical reasons by prominent medical organizations, including the European Academy of Pediatrics, the British Royal College of Pediatrics and Child Health, the British Royal College of Radiologists, the French Academy of Medicine, the French National Ethic Committee, and the Dutch National Society of Physicians.¹³

Although it is unlikely that we will see greater transparency by the US government regarding these questionable practices, I would like to see our national dental organizations, as well as the boards of the specialties of orthodontics, pediatric dentistry, public health dentistry, and oral and maxillofacial radiology, develop a consensus statement regarding this scientifically and ethically questionable method of chronologic age determination that carries no therapeutic or diagnostic purpose.

Until there is an accurate and reliable diagnostic test to assess chronologic age, I think that as representatives of our distinguished profession it behooves us to have the best interests of vulnerable children in mind and uphold the scientific and ethical principles we were taught.