|FORENSIC ODONTOLOGY: ORIGINAL ARTICLE
|Year : 2018 | Volume
| Issue : 2 | Page : 148-152
Validity of Demirjian 8-teeth method for age estimation by orthopantomogram – A prospective study
Nidhi Dehankar1, Giridhar S Naidu1, Ramanpal S Makkad1, Ravleen Nagi1, Supreet Jain1, Utkarsha Deshmukh2
1 Department of Oral Medicine and Radiology, New Horizon Dental College and Research Institute, Bilaspur, India
2 Department of Ophthalmology, Late Shri Lakhiram Agrawal Memorial Medical College, Raigarh, Chhattisgarh, India
|Date of Submission||23-Mar-2018|
|Date of Acceptance||01-Jun-2018|
|Date of Web Publication||16-Jul-2018|
Dr. Ravleen Nagi
Department of Oral Medicine and Radiology, New Horizon Dental College and Research Institute, Bilaspur, Chhattisgarh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Demirjian et al. (1973) put forth a method of age prediction, which used seven mandibular teeth on the left side. The technique has been widely applied but revealed variations in age estimates in other populations, including Indians. The aims and objectives of our study were to validate the Demirjian 8-teeth method using orthopantomogram to estimate the reliability of age estimation after incorporating the third molar and to predict the accuracy of age estimation using Indian-specific formulae. Materials and Methods: The study was conducted on the local population with 49 subjects (mean = 18, f = 31) less than 18 years of age. The soft copies of the radiographs of selected subjects were retrieved from the computer attached to the digital orthopantomogram machine (Orthophos XG5; Sirona Dental Systems). Staging of each tooth of left mandibular side was done using Demirjian 8-teeth method. Dental age was calculated using the modified formula given by Acharya et al. and statistical methods were used to compare it with chronological age. Results: The overall mean absolute error (MAE) of the 49 subjects was 0.911 ± 1.65. The highest MAE was in the 13-year age group (1.82 years) while it was lowest in the 18-year age group (0.43 ± 1.10 years). In all, 15 subjects (30.6%) had an error in age estimation which is less than 1 year and 12 subjects (24.5%) had an error of more than 2 years The accuracy of age estimation was found to be better in 16–18 years age group as compared to younger age group, probably because of better development of the third molar by this age. Conclusion: The reasonably good results obtained in this study assert the use of Demirjian's 8-teeth method with Indian cubic functions in the local population.
Keywords: Age estimation, Demirjian, orthopantomogram, third molar
|How to cite this article:|
Dehankar N, Naidu GS, Makkad RS, Nagi R, Jain S, Deshmukh U. Validity of Demirjian 8-teeth method for age estimation by orthopantomogram – A prospective study. J Indian Acad Oral Med Radiol 2018;30:148-52
|How to cite this URL:|
Dehankar N, Naidu GS, Makkad RS, Nagi R, Jain S, Deshmukh U. Validity of Demirjian 8-teeth method for age estimation by orthopantomogram – A prospective study. J Indian Acad Oral Med Radiol [serial online] 2018 [cited 2021 Dec 2];30:148-52. Available from: https://www.jiaomr.in/text.asp?2018/30/2/148/236729
| Introduction|| |
The broadening frontiers of dentistry have taken the dentist as an expert witness in legal room proceedings and in the field of forensic sciences. But forensic odontology for long had been a less explored area of dentistry. Age estimation forms one of the most important subdisciplines of forensic sciences and is of paramount importance in medico-legal issues. Age estimation of children and adolescents is essential to answer a variety of legal questions. In the current scenario, most of the age estimation modalities are invasive, requiring lengthy processing times, use of expensive instruments, and the services of an experienced pathologist to deduce the age of the person.
Demirjian et al. put forth a method of age prediction, which used seven mandibular teeth on the left side. The technique has been widely applied but revealed variations in age estimates in other populations, including Indians. A drawback of the original method was that it excluded the third molar owing to its tendency to be congenitally missing and also because of wide variation in its development. It was in this background that Demirjian et al. classified the development of teeth into eight stages and arrived at an age estimation method.
The aims and objectives of our study were to validate the Demirjian 8-teeth method using orthopantomogram to estimate the reliability of age estimation after incorporating the third molar and to predict the accuracy of age estimation using Indian-specific formulae.
| Materials and Method|| |
The study was conducted on the local population with 50 subjects less than 18 years of age who had come for routine check up in the Outpatient Department of Oral Medicine and Radiology, New Horizon Dental College and Research Institute, Bilaspur, Chhattisgarh. Chronological age was documented using a valid age proof. The time frame of the study was from June 2017 to July 2017. The soft copies of the radiographs of selected subjects were retrieved from the computer attached to the Sirona digital orthopantomogram machine (Orthophos XG5; manufactured by Densply Sirona, Germany). The study protocol was approved by the ethical committee of the college. All the observations and analysis were done by a single skilled observer.
- Subjects indicated for panoramic radiographs
- Age of the patient
- Subject who has volunteered to give a valid date of birth proof for the study
- Where correct inferences regarding tooth development stage cannot be drawn due to poor quality radiographs
- Developmental anomalies of index teeth
- Exclusions based on criteria of Demirjian method
Orthopantomogram of the selected subjects was taken at 60 kVp, 8 mA, and exposure time of 14.1 s, and staging of each tooth of left mandibular side was done using Demirjian 8-teeth method [Figure 1] and [Figure 2]. Each stage of the mandibular eight teeth (central incisor to third molar) was allocated a score, and the sum of the scores gave a total maturity score (S) [Figure 3].
|Figure 1: Representative stages of Demirjian's method based on the development of mandibular third molar as seen on the radiographs used during the study|
Click here to view
- Dental age was calculated using the following formula, as per the relevant method described by Demirjian and modified by Acharya et al.:
- Males: age = 27.4351- (0.0097 × S 2) ± (0.000089 × S 3)
- Females: age = 23.7288- (0.0088 × S 2) ± (0.000085 × S 3)
The data collected were subjected to appropriate statistical methods using Statistical Package for the Social Sciences (version 21.00: SPSS, Chicago, IL, USA). While all analyses were performed separately on males and females considering differences in the rate of dental development, the results are pooled wherever possible to facilitate comparison of the effectiveness of the formulas across the sexes. The correlation between the chronological age and dental age was calculated using Pearson's correlation coefficient.
Analysis of variance was used to calculate the mean absolute error (MAE) comparisons between and within the various age groups. Mathematical calculations were performed on an Excel spreadsheet (2007, Microsoft Office). A P value < 0.05 was considered statistically significant.
| Results|| |
The study consisted of 31 females and 18 males. The mean chronological age of the sample was 16.1224 ± 1.6025 years, while the mean dental age was 15.2112 ± 2.2654 years. The mean chronological age for males was 16.3333 ± 1.41421 years and that for females was 16.0000 ± 1.71270 years. The mean dental age for males was 15.4217 ± 2.23247 years and that for females was 15.0891 ± 2.31200 years [Table 1] and [Figure 4], [Figure 5].
MAE in the age estimation was classified by dividing the sample into seven different age groups which ranged from 12 to 18 years. The overall MAE of the 49 subjects was 0.911 ± 1.65. The highest MAE was in the 13-year age group (1.82 years), while it was lowest in the 18-year age group (0.43 ± 1.10 years) [Table 2]. In all, 15 subjects (30.6%) had an error in age estimation which is less than 1 year and 12 subjects (24.5%) had an error of more than 2 years [Table 3].
There was a remarkable difference between chronological and dental age in the lower age groups, that is, 12–14 years; but as age increases, that is, around 16–18 years the difference narrows down, which signifies greater accuracy in dental age estimation [Figure 6].
|Figure 6: Scatter plot – comparison of chronological and dental age of the subjects|
Click here to view
| Discussion|| |
The estimation of age is an important aspect in medico-legal practice. The need for age estimation has certain important reasons at certain specific age groups in the Indian context:
(1) 12 years: children below this age are not liable for certain offences; (2) 14 years: a child cannot be employed below 14 years; (3) 18 years: determines the status of majority and the legally permissible age for marriage in females; (4) 21 years: the legally permissible age of marriage in males.
In 1973, Demirjian et al. introduced the method of age estimation based on the radiological appearance of the seven teeth on the left side of the mandible. The Demirjian method is widely used to estimate chronological age due to its simplicity, reproducibility, and ease of standardization. The estimation of age is based on the developmental stages of teeth, taking into consideration associated calcification process. Moreover, tooth maturation is a better indicator of dental age than tooth eruption which is influenced by various exogenous factors such as infection, extraction, crowding, and ankylosis.
The original Demirjian's method excluded the third molar due to the variability in its development, eruption, and anatomy. However, the pitfall of its exclusion was that age prediction by the original Demirjian's method is not feasible after about 16 years of age, since by this age all the permanent teeth, except the third molar, would have completed their development. Therefore, the third molar offers the only reliable radiological parameter for age determination in the age group of 16–23 years.
In a study carried out by Mincer et al., it was concluded that the third molar may provide reasonable accuracy for the prediction that a person is at least 18 years of age, rather than giving the exact chronological age, due to the absence of any other marker in the late adolescence.
Chaillet and Demirjian modified their method to incorporate the third molar and developed a new maturity score based on a French population. Another major modification made in this study was that the stages of teeth were modified to include two additional stages of non-formation of tooth (Stage “0”) and crypt development (Stage “1”); furthermore, the stage of development was assigned numerals which were designated as 0–9 for easier calculation and developed a multiple regression formula based on cubic function which gave better reliability when the third molar was incorporated into the study. In this study, modified Demirjian method showed positive correlation between mean chronological (16.1224 ± 1.6025 years) and dental age (15.2112 ± 2.2654 years), although chronological age of males (16.3333 ± 1.41421 years) was observed to be slightly more than females (16.000 ± 1.71270 years).
Indian studies have shown overestimation ranging from 2 months to over 3 years., 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 that this dataset should be used with caution in global populations. Consequently, the method's adaptation to the local population was 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.
Acharya et al. (2011), who derived the formula which was used in this study for age assessment, had deduced an 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. In this study, MAE (0.9114 years) for the overall sample was similar to the original study, with 30.61% subjects within 1 year of chronological age and 24.48% subjects beyond 2 years of the chronological age.
In the study conducted by Jayanth Kumar et al. (2011), with a sample size of 121, the MAE for 58% of sample was within ±1 year, and that for 10.75% beyond ±2 years. Sai Kiran et al. in their study (2015) conducted on 250 subjects found an error of <1 year in 54.40% and that of >2 years in 20% of the sample. Rath et al. (2017) found that the MAE was <1 year error in 50% and >2 years error in 23.6% in their study with a sample size of 106.
The MAE in previous studies by Jayanth Kumar et al. (2011), Sai Kiran et al. (2015) and Rath et al. (2017) was found to be 1.18, 0.83, and 1.3 years, respectively, which when compared to our study results (MAE = 0.9114 years), proves that Demirjian method is a reliable and accurate method for age estimation of individuals in 16–18 years age group.
| Conclusion|| |
To conclude, the Indian formula was reliable in approximately 30% of our cases with the MAE of the total sample being less than 1 year. The accuracy of age estimation was found to be better in 16–18 years age group as compared to younger age group, probably because of better development of the third molar by this age. The drawback of our study was the comparatively small sample size.
The reasonably good results obtained in this study assert the use of Demirjian's 8-teeth method with Indian cubic functions in the local population. It is a worthwhile exercise to apply Indian formulas locally within specific regions, possibly in larger samples. This would in future lead to the development of regional database in various populations.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3]