Age estimation using Demirjian’s method and Foti’s method: A comparative study

Introduction

Age estimation is an important consideration for biological identification in several forensic fields, such as forensic odontology, forensic medicine, forensic anthropology, and forensic osteology.¹ The determination of physiological age is based on the assessment of degree of maturation of different tissue systems. Different sorts of biological age have been established: skeletal age, morphological age, secondary sexual character age and dental age. Dental age assessment is important for dental treatment planning as wel.^l as in forensic odontology.² In forensic odontology and archaeology, age estimation methods can aid the identification of age at death of a deceased individual and also give important information with regard to populations of the past. It also proves valuable when birth data is lacking or doubted in the management of immigration to help determine physiological age.³ Teeth consist of brady trophic tissues which do not undergo continuous remodeling process.⁴ The present study was to compare dental age with chronological age using orthopantomogram by Demerjian’s and Foti’s method.

Materials and Methods

The present research was a radiographic retrospective study which comprised of 50 OPG’s taken at Department of Oral Medicine and Radiology from stored database. Among 50 subjects 25 were males and 25 females, aged between 7 to 20 years.  Their chronological age was estimated using date of birth and Dental age was estimated using orthopantomogram   by Demirjian’s method as well as  Foti’s method. Demirjian et al.  described the stages of tooth development from crown formation, to closure of the root apices in permanent tooth. Each stage of tooth development were given a specific score and total score was calculated then substituted in specific formula for male and female to estimate the age.

• Male, Age= 27.431 - (0.0097 * S2) + (0.000089 *S3) 
• Female, Age= 23.7288 – (0.0088 * S2) + (0.000085 * S3) 

In Foti’s method, thenumber of erupted permanent upper1st molars, number erupted permanent upper 2nd molars, number of erupted upper 3rd molars, number of erupted lower 3rd molars, number of tooth germs on radiographs (except wisdom tooth germs) were counted and substituted in Model 1 regression equation.

• Age= 16.088 - (0.226 x No. of erupted permanent upper first molars) + (1.564*No. of erupted permanent upper second molar) + (0.832 x No. of upper erupted third molars) + (0.912 x No. of lower erupted third molars) - (1.699 x No. of germs on radiographs, except third molar tooth germs).

Inclusion criteria:

The inclusion criteria included Patient aged between 7 to 20 years old, Panoramic radiographs of good quality, and Patient with no systemic condition.

Exclusion criteria:

The exclusion criteria includedPatient with congenital anomalies,,Patient with a history of previous orthodontic treatment, dental anomalies, missing teeth, any pathological condition like cyst and tumour, and Panoramic radiograph of insufficient quality.

Results

A total of 50 patients were enrolled in the study, comprising of 25 males and 25 females.Mean and standard deviation were used to describe the age assessed by Demirjian’s and Foti’s methods. Paired t –test was used to evaluate the statistical significance. All the analysis was done using SPSS 20 and significance was observed at P<0.05 level.

On comparing Chronological age with Demirjian’s and Foti’s method the P value was 0.067, which is not significant, on the other hand there was a significant difference found between Chronological age (CA) and Foti’s method (FS), Demirjian’s method (DS) and Foti’s method (FS) [Table -1, Graph-1].

On comparing Chronological age with Demirjian’s and Foti’s method in male and female the P value was 0.256 and 0.151 respectively which is > 0.05; therefore there was  nostatistically significant difference found between Chronological age(CA) and Demirjian’s method (DS). On the other hand, there was significant difference found between Chronological age (CA) and Foti’s method (FS); Demirjian’s method (DS) and Foti’s method (FS); with p value <0.001.[Table -2,3, Graph-2,3].

On comparing Chronological age with Demirjian’s and Foti’s method among age group <15 years and in age group >15 years, the P value was 0.118 and 0.257 respectively which is >0.05, there was no statistically significant difference found between Chronological age(CA) and Demirjian’s method (DS). On the other hand there was significant difference found between Chronological age (CA) and Foti’s method (FS), Demirjian’s method (DS) and Foti’s method (FS),p value was <0.001. [Table -4,5 Graph-4,5].

Discussion

Estimation of age of an unknown individual can be performed by correlating the physical, skeletal and dental maturity. Among the entire growth systems, the dental maturity has the highest stability and hence it provides the most accurate way of assessing growth and development.⁵ Dental development is more reliable as an indicator of biological maturity in children.⁶

An invasive or non-invasive method of dental age can be carried out. Non-invasive methods are sequential tooth eruption and/or emergence, development by means of calcification and/or root maturation, root development stages, morphological tooth parameters, and tooth measurements. Invasive methods are biomarkers, root dentine translucency, and incremental lines, there are four different categories for dental age estimation.

1. Clinical or visual methods.
2. Radiographic methods.
3. Histological methods.
4. Physical and chemical methods.⁷

Age estimation, using radiographic tooth formation, has been found to be a more accurate method because it is primarily genetically influenced and as such is less likely to be affected by nutritional and environmental factors[8].There various radiographic methods, which include Nolla’s, Demirjian’s,  Anderson’s,  Cameriere’s and Foti’s methods etc.^7,5

Demirjian’s method was first proposed in 1973 and it is one of the widely accepted methods for dental age estimation in children and adolescents of the age group of 2–20 years.⁷ A meta - analysis of 12 studies by Jayaraman et al., which used the Demirjian’s method, found an average overestimation of age of patients by more than 6 months and Suggested the use of this dataset in global populations with caution.The adaptation of the system to the local population was therefore considered essential for optimal age prediction. Genetic influences, socioeconomic status, nutritional conditions, and dietary habits have been reported as the possible reasons for variations in skeletal and dental maturity among different populations and ethnic groups and different groups within the same population.

Our study was based on the studies of Acharya et al. who derived the Indian formula  for age assessment, had deduced an Mean Absolute Error (MAE) of 1.43 years, with 44% of samples within ±1 year, 36% within ±1.1 to ±2 years, and 20% beyond ±2 years, the sample size being 597.⁹

The Foti’s method was done using the Foti’s Model 1 regression formula which helps in determining the age of an individual from radiographs showing teeth and dental germs. Foti’s method was as simple and accurate as Demirjian’s method. Moreover, it covers the period between 6 and 20 years of age. The reliability of formulas was proved to be equal to that of Demirjian’s method.¹⁰

In the present study, on comparing chronological age with Demirjian’s method the result were not significant and slightly overestimated chronological age by about 6.17%. This results were similar to the study done by Gupta et al¹¹, Naik et al [4] because dental maturation demonstrates few pubertal changes and thus is a poor indicator of pubertal growth spurt.

On comparing chronological age with Foti’s method the results were significant and overestimated the chronological age by about 6.3%. The results were similar to the study done by Faiz et al⁵, this significant in chronological age was due to the regression model 1 equation was derived for European population, so it should be modified to Indian population.On comparing Foti’s method with Demirjian’s method the result was significant which was due to the difference in methodology. In Demirjian’s method 8 teeth and ten stages of teeth was assessed but in Foti’s method, the presence or absence of tooth was assessed.

In the present study, on comparing chronological age with Demirjian’s method in male and female the result was not significantly different, which is in accordance with the study done by Wolf et al[12], Gopalakrishnan M et al.¹³ This probably could be because of the fact that we used Indian formulas for age estimation in male and female. On comparing chronological age with Foti’s method among males and females the result had significant difference, which was contradictory to study done by Javadinejad et al.¹⁴ because in their study they used Foti’s four regressive models but we used Foti’s model-1 regression.

On comparing chronological age with Demirjian’s method among age groups <15 years and >15 years the result had no significant difference which is in accordance with study done by Chaudhary et al.⁷ They stated that the Demirjian’s method were widely accepted method for children and adolescents. On comparing chronological age with Foti’smethod among age groups <15 years and >15 years, the result had significant difference and over-estimated the age, which is in accordance with the study done by Faiz et al⁵, because in our study we took sample of uneven size of distribution with age. In the present study, age estimated in subjects above 15 years had dental age closer to their chronological age. However, sample size was less, therefore better results may be obtained if wide range of age group is evaluated.

 Conclusion

Age estimation poses a complex problem which requires considerable expertise in ididentifying significant changes and facilitating variation within any given population. The present study concluded that Demirjian’s method was better in estimating age in males, females aged between 7- 20 years when compared to Foti’s method. Though Foti’s method was very simple compare to other method, age was over-estimated than the chronological age and therefore, this method is inappropriate for our population.