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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 34  |  Issue : 3  |  Page : 343-347

Assessment of accuracy of two different radiographic methods for age estimation to chronological age – A Comparative CBCT Study


1 Department of Oral Medicine and Radiology, Government Dental College and Hospital, Hyderabad, Telangana, India
2 Department of Oral and Maxillofacial Surgery, Government Dental College and Hospital, Hyderabad, Telangana, India

Date of Submission17-Jan-2022
Date of Decision14-Sep-2022
Date of Acceptance14-Sep-2022
Date of Web Publication26-Sep-2022

Correspondence Address:
Mala Dayanandam
3-15, Kachireddy Gudem, Shankarpally, Rangareddy - 501 203, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiaomr.jiaomr_26_22

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   Abstract 


Introduction: Assessment of age in adults is a difficult task in forensic medicine. In craniofacial structures, the mental, mandibular foramina and teeth are useful in age estimation. Because the pulp-to-tooth area ratio (PTR) based on secondary dentin deposition and the distance between the inferior border of the mental foramen and lower border of the mandible stays largely consistent over the course of a person's life, PTR and position of mental foramen are sensitive age markers. Aim: This study aims to assess an accurate method for age estimation, by comparing the results of the two different age estimation techniques such as mandibular canine's PTR and vertical position of the mental foramen using cone beam computed tomographic (CBCT) images. Materials and Methods: In 80 mandibular CBCT images, the pulp area and tooth area of the canine were measured from the axial section and a ratio was obtained. The same process was used for the sagittal sectional image. Another method involved measuring the mental foramen's four variables (X1, X2, X3, and X4) using a panoramic sectional image. The procured data were subjected to statistical analysis. Results: A negative linear relationship was acquired among the pulp cavity width, the height of the mandible (X1), and the age. Cubic regression analysis was performed, and the regression formulae were acquired. A mean difference of 2.11 years in axial section, 3.93 years in sagittal section, and 11.23 years in the mental foramen vertical position was acquired among the age estimated and chronological age. Conclusion: The sagittal sectional image of the mandibular canine's PTR is more accurate for determining age when compared with the vertical position of the mental foramen.

Keywords: Age estimation, cone beam computed tomography, mental foramen, pulp tooth area ratio


How to cite this article:
Thomas D, Pushpanjali, Dayanandam M, Kondoj N, Anakarla V, Dhanabalan S. Assessment of accuracy of two different radiographic methods for age estimation to chronological age – A Comparative CBCT Study. J Indian Acad Oral Med Radiol 2022;34:343-7

How to cite this URL:
Thomas D, Pushpanjali, Dayanandam M, Kondoj N, Anakarla V, Dhanabalan S. Assessment of accuracy of two different radiographic methods for age estimation to chronological age – A Comparative CBCT Study. J Indian Acad Oral Med Radiol [serial online] 2022 [cited 2022 Dec 10];34:343-7. Available from: http://www.jiaomr.in/text.asp?2022/34/3/343/356958



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   Introduction Top


Age is a principal component for medical and legal conditions. In orofacial region, mental foramen, mandibular canal, and teeth can be used for assessment of age.[1]

Mandible perseveres in a well-preserved state due to dense layer of compact bone. One mandibular feature that is very beneficial for an assessment of age is mental foramen. The interspace between the inferior border of mental foramen to the lower border of mandible remains more or less persistent throughout the life.[2]

The other feature which is less affected by environmental factors is teeth. Teeth remains sound for a long time as it is the strongest tissue of the body. Several developmental methods are available that are highly dependable for assessment of age under 21 years of age. However, in adults it is difficult.[3]

All thorough life, secondary dentin deposition occurs resulting in reduction of the dimensions of the pulp chamber, this principle can be a useful indicator of age.[3]

Age determination by measuring the dimensions of the pulp chamber using radiographs is a noninvasive technique, pertinent to living as well as dead. Data analysis is difficult in 2 dimensional (2D) images with crowding and the measurement is only possible in the mesiodistal direction.[3]

In recent years, cone beam computed tomography (CBCT), a new advancement, facilitated to overcome the limitation of 2D images.[4]

Two distinct age estimation methods are examined in the current study. The first is a dental method based on the mandibular canine's pulp-to-tooth area ratio (PTR), whereas the second is a skeletal method based on the vertical location of the mental foramen.

In this method for computation of PTR, canines were chosen. They have a reasonably simple anatomy, well anchored in the jaws, and frequently remain sound until old age.[5] As opposed to conventional 2D image, a bucco lingual section reveals the overall amount of pulp calcification. The largest secondary dentine deposition occurs in the cervical region, and the sagittal sections show vast tooth and pulp areas, therefore, axial and sagittal sectional images were chosen.

For the measurement of position of mental foramen, four variables were selected from the panoramic image section.[6] According to Phillips et al.[7] (1992), panoramic photographs provide a better and more expansive perspective of the mental foramen than other types of images.

While there have been individual studies on the relationship between PTR and the vertical position of the mental foramen to chronological age using CBCT, the current study was carried out to assess age by comparing these two methods to determine their accuracy in age estimation.


   Materials and Methods Top


Sample size selection

A total of 80 patients among the age of 16–55 years disregarding the sex reported to the department of oral medicine and radiology requiring CBCT of mandible were recruited. The sample size was estimated by point biserial model correlation t test. Power of the test is 95% and level of significance is 5%. Inclusion criteria include the patients with the region of mental foramen and mandibular cuspid, who need CBCT for preorthodontic assessment, dentition assessment, and prosthodontic assessment. Teeth of interest with trauma and other pathologies, history of surgical interventions at the regions of interest (mandibular cuspids and mental foramen) were excluded. After selection of patients, Informed consent was obtained and all relevant information including the chronological age from a valid identity proof were recorded in a prescribed pro forma and referred to a diagnostic center in Hyderabad. This analytical cross-sectional study was approved by The Review board of institutional ethics committee (certificate no. gdch-iec/pg/1902).

Acquisition of CBCT data

Planmeca, helsinki, machine was used for taking CBCT images and the same machine was used throughout to maintain standardization. The study was carried on following the guidelines of International Commission of Radiation Protection (ICRP). Exposure parameters tube current: 10 ma, 86 kvp, exposure time: 11.3 s, field of view: 8 × 8 cm. High-resolution images of 0.4 mm voxel size with 1 mm slice thickness were obtained. The obtained images were exported as DICOM. Finally, each model was selected and PTR and lengths of mental foramen were calculated in millimeters using On Demand 3d Dental software.

Measurements of pulp-to-tooth area ratio

In the present study, from the right- to the left-side tooth whichever looked right on for computation was selected. After selection, sagittal and axial cut sections were selected for the canine.

After fixing the most convex point of the buccal surface of the crown in its buccolingual plane in the axial view, the long axis of the canine is taken from the cusp tip to root apex for the sagittal cut section [Figure 1]a and [Figure 1]b.
Figure 1: (a) Axial section – tooth area. (b) axial section – pulp area. (c) sagittal section -pulp area. (d) sagittal section – tooth area

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The axial cut images were obtained by setting the long axis of the tooth in the axial section at the cement enamel junction region [Figure 1]c and [Figure 1]d.

The pulp area and the tooth area were calculated using the tools from the on demand 3d dental software [Figure 2]. The PTR for each tooth was estimated using the below formula from all the CBCT images.
Figure 2: On demand 3D dental software

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PTR = Pulp Area/Tooth Area.

Measurements of the mental foramen

In the panoramic view using the measurement tools from the software

  1. The entire height of the mandible (H) is measured and marked as X1 [Figure 3]a
  2. Space between the superior border of the mental foramen and the alveolar crest (SM-AC) was denoted by the symbol X2 [Figure 3]b.
  3. Space between the middle of superior border of mental foramen and inferior border of mandible (SM-IB) was marked as X3 [Figure 3]c
  4. Space between the inferior border of mental foramen and inferior border of mandible (IM-IB) was marked as X4 [Figure 3]d.
Figure 3: (a) Height of the mandible –X1. (b) Distance between the superior border of mental foramen to alveolar crest (SM-AC) -X2. (c) Distance between the superior border of mental foramen to inferior border of mandible (SM-IB)-X3. (d) Distance between the inferior border of mental foramen to the lower border of mandible (IM/IB) -X4

Click here to view


The measurements were deliberated by a single observer which included height (H), SMAC, SMIB, and IMIB.

After 15 days, the measurements were performed again on a portion of the sample to evaluate intraobserver variability. A second observer conducted measurements using the same method on a subset of images to measure interobserver variability. The proforma was filled out using the noted values, and SPSS software version 17 was used to do statistical analysis.


   Results Top


The minimum, maximum, and mean values of X1, X2, X3, X4, PTR (axial), and PTR (sagittal) of mandibular canine are shown in [Table 1]. Due to the wide age range of the included individuals, the subjects were further divided into four groups with an age gap of 10 years to provide for a more accurate evaluation. Significant differences were seen between the age groups when the PTR, X1, X2, X3, and X4 values were compared. In addition, various intergroup comparisons are shown in [Table 2].
Table 1: The minimum, maximum, mean, and standard deviation values of PTR (AXIAL), PTR (SAGITTAL), and mental foramen variables (X1, X2, X3, and X4).

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Table 2: Comparison of PTR, mental foramen variables of different sections among the age groups

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The Pearson correlation coefficient for the PTR, X1, X2, X3, X4, and age is presented in [Table 3]. In accordance with [Table 3], strong negative correlations were found between the PTR (AXIAL), PTR (SAGITTAL), and chronological age; weak negative correlations were found between X1 and age, whereas X2, X3, and X4 values yielded insignificant results.
Table 3: Pearson's correlation analysis for age and PTR (AXIAL), PTR (SAGITTAL), mental foramen variables

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Lowest SEE (2.11 years) and the highest R2 (r2 = 96.83%) were observed in the PTR (SAGITTAL) of the mandibular canine as opposed to the axial section (r2 = 89.12% SEE = 3.93 years) and vertical position of the mental foramen (r2 = 11.83% SEE = 11.23 years) suggesting the ascendancy of this section. These findings showed a significant correlation between chronological age and the mandibular canine PTR determined from sagittal sectional pictures [Table 4]. Derived regression equations to predict chronological age are illustrated in [Table 4].
Table 4: Derived regression equation for PTR (AXIAL), PTR (SAGITTAL), mental foramen variables

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In [Graph 1], the scatter plot of predicted age versus chronological age for PTR (AXIAL), PTR (SAGITTAL), and mental foramen variables (X1 X2 X3 X4) are given.



When the initial measurement and repeat measurements were analyzed using kappa statistics for intraobserver reliability, PTR (AXIAL), PTR (SAGITTAL), X1, X2, X3, and X4 showed good agreement. The initial and repeat measurements for inter observer reliability likewise revealed good agreement for all the variables.


   Discussion Top


According to our data, there is a strong correlation between the PTR and chronological age. This is so because the cervical region, where the axial sectional image was taken, has the largest secondary dentine deposition, and the sagittal sections show vast tooth and pulp areas.[6] PTR values decreased with age due to secondary dentin deposition, and there was a negative relationship between PTR and chronological age, similar to the study of Cameriere et al.[8] Between the various age groups, PTR values revealed substantial differences. This can be linked to the possibility that with advancing age there is a large secondary dentin deposition throughout the pulpal dimensions.

In the determination of age by the mental foramen, there was a weak negative correlation linking the age and the height of the mandible that can be explained by the fact as age advances alveolar crestal bone resorption takes place resulting in a decrease in the overall height of the mandible, whereas the other variables showed insignificant results. This can be attributed to the fact that the vertical position of the MF varies in different age groups. These findings were consistent with those obtained by Popa et al.[9] Therefore, as it is showing negligible values in this study, the vertical distance between the mandibular superior border, inferior border, and inferior border should not be further studied.

When the PTR and position of mental foramen variables were compared, the PTR showed a significant correlation with age over mental foramen position.

Furthermore, the predictive power was high in the sagittal section (R2 =96.83% for sagittal planes, R2 =89.12% for axial planes. The results were consistent with the study for maxillary canine teeth conducted by Lee, et al. (2017).[3] When compared with an axial slice, the PTR from a sagittal sectional image was more useful for determining the age, this is because sagittal sectional images have several advantages. The ratio was not altered by image distortion and a large sectional area is measured in the sagittal image. Moreover, the predictive power of the height of the mandible in age estimation is only 11.83% [Table 4].

The overall correlation revealed PTR of the sagittal section was more reliable for predicting age (difference of 2.11 years to the actual age) compared with the axial section (age difference of 3.93 years to the actual age) and vertical position of mental foramen (11.42 years to the actual age) [Table 4].

Limitations

The major limitations of the current study would be confined to the sample selection as CBCT images were advised only for the patients in need. So, further studies would be recommended with a large sample size, also taking into account gender distribution.

Future prospects

The results obtained in this study can be used to compare future studies. More similar studies have to be conducted with larger sample sizes taking into account geographical variations.


   Conclusion Top


The present research explored the relationship between the PTR of the mandibular canine and the vertical position of the mental foramen to chronological age using CBCT image. When the final results of both the methods were compared, the best predictor for age was the sagittal sectional PTR of the mandibular canine.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Key message

Of the various age estimation methods available, this is the first study in the literature wherein two sensitive age estimation techniques—one based on the ratio of pulp-to-tooth surface area (dental method) and the other on the location of the mental foramen (skeletal method)—were compared to determine which was more accurate in determining chronological age.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Hu KS, Koh KS, Han SH, Shin KJ, Kim HJ. Sex determination using nonmetric characteristics of the mandible in Koreans. J Forensic Sci 2006;51:1376-82.  Back to cited text no. 1
    
2.
Wical KE, Swoope CC. Studies of residual ridge resorption. Part 1.Use of panoramic radiographs for evaluation and classification of mandibular resorption. J Prosthet Dent 1974;32:7-12.  Back to cited text no. 2
    
3.
Lee SM, Oh S, Kim J, Kim YM, Choi YK, Kwak HH, et al. Age estimation using the maxillary canine pulp/tooth ratio in Korean adults: A CBCT buccolingual and horizontal section image analysis. J Forensic Radiol Imaging 2017;9:1-5.  Back to cited text no. 3
    
4.
Tardivo D, Sastre J, Catherine JH, Leonetti G, Adalian P, Foti B. Age determination of adult individuals by three-dimensional modeling of canines. Int J Leg Med 2014;128:161-9.  Back to cited text no. 4
    
5.
Farhadian M, Salemi F, Saati S, Nafisi N. Dental age estimation using the pulp-to-tooth ratio in canines by neural networks. Imaging Scie Dent 2019;49:19-26.  Back to cited text no. 5
    
6.
Wical KE, Swoope CC. Studies of residual ridge resorption. Part 1.Use of panoramic radiographs for evaluation and classification of mandibular resorption. J Prosthet Dent 1974;32:7-12.  Back to cited text no. 6
    
7.
Phillips JL, Weller RN, Kulild JC. The mental foramen: 3. Size and position on panoramic radiographs. J Endod 1992;18:383-6.  Back to cited text no. 7
    
8.
Cameriere R, Ferrante L, Cingolani M. Variations in pulp/tooth area ratio as an indicator of age: a preliminary study. J Forensic Sci 2004;49:1-3.  Back to cited text no. 8
    
9.
Popa FM, Stefanescu CL, Corici PD. Forensic value of mandibular anthropometry in gender and age estimation. Romanian J Legal Med 2009;17:45-50.  Back to cited text no. 9
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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