Tooth Coronal Index: Key for Age Estimation on ...

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Forensic Odontology: Original Article

Tooth Coronal Index: Key for Age Estimation on Digital Panoramic Radiographs Ravleen Nagi, Supreet Jain, Priyanka Agrawal1, Swati Prasad2, Sumit Tiwari3, Giridhar S. Naidu 2

Departments of Oral Medicine and Radiology and 3Oral and Maxillofacial Surgery, New Horizon Dental College and Research Institute, Bilaspur, Department of Oral Medicine and Radiology, Rungta College of Dental Sciences and Research, Bhilai, 1Department of Oral Medicine and Radiology, Ekta Hospital, Kondagoan, Chhattisgarh, India

Abstract Background: Assessment of age through teeth is one of the most reliable and simple method than skeletal remains, to calculate age of an individual. Objectives: The study was carried out with an aim to evaluate reliability of dental age assessment through tooth coronal index (TCI) method. Materials and Methods: The digital panoramic radiographs of 100 subjects of Chhattisgarh aged 20–70 years were selected for the study. The measurements were performed on the JPEG images of selected panoramic radiographs by using Adobe Acrobat 7.0 professional software. The height of the crown, i.e., coronal height, and the height of the coronal pulp cavity, i.e., coronal pulp cavity height, of mandibular second premolars and first molars were measured in millimeter (mm) and then TCI was calculated for each tooth. Actual age of a subject was compared with TCI of tooth and the acquired data were subjected to Pearson’s correlation and unpaired t‑tests. Results: Negative correlation was observed between the real age and TCI of mandibular first molar (r = −0.092, P = 0.365) and second premolar (r = −0.168, P = 0.096). Statistically significant difference was observed between real age and TCI for mandibular second premolar and first molar (P = 0.000) by unpaired t‑test. Conclusion: TCI has the potential to estimate age of an individual on dental radiographs. It is simple, cost effective than histological methods and can be applied to both living and unknown dead. Keywords: Age estimation, panoramic radiograph, tooth coronal index

Introduction Forensic odontology is an emerging science that uses teeth for assessment of age of an individual. Accurate age estimation is required for pediatric issues, orthodontic treatments to legal matters, etc.[1] Although skeletal methods could be used for age estimation, but variability of bone maturation is influenced by several environmental factors. Tooth development shows less variability than other developmental features and shows low variability in relation to chronological age.[2] Moreover, dental tissues are more resistant to thermal, chemical, and mechanical stimuli and are less affected by endocrine diseases or nutritional variations than other tissues. Therefore, teeth form a unique and suitable parameter for dental age estimation.[3] Nowadays, they have become important tool for age estimation for both deceased and living person and for medico‑legal purposes.[1,4] In children age calculation from teeth is simple and accurate and is based mainly on stages of development and eruption of tooth. In adults various methods have been developed to Access this article online Quick Response Code:

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DOI: 10.4103/jiaomr.jiaomr_139_17

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calculate age from dental tissue and tooth morphology.[5] These methods are classified as: radiologic and morphologic methods. Morphologic methods are sub classified into clinical, histological, and biochemical examination. Radiographic methods are simple, nondestructive, requires comparatively less duration of time, and expertise than morphologic methods.[3] Several studies have used canine, first premolar, and second premolar on intraoral periapical and panoramic radiograph to estimate dental age as these teeth have good delineation of pulp chamber.[3,6‑9] Some studies used mandibular first molar to predict dental age[4,10,11] and literature also revealed that only few studies Address for correspondence: Dr. Ravleen Nagi, Department of Oral Medicine and Radiology, New Horizon Dental College and Research Institute, Bilaspur, Chhattisgarh, India. E‑mail: [email protected] This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. For reprints contact: [email protected]

How to cite this article: Nagi R, Jain S, Agrawal P, Prasad S, Tiwari S, Naidu GS. Tooth coronal index: Key for age estimation on digital panoramic radiographs. J Indian Acad Oral Med Radiol 2018;30:64-7. Received: 23-12-2017 Accepted: 17-02-2018 Published: 23-04-2018

© 2018 Journal of Indian Academy of Oral Medicine & Radiology | Published by Wolters Kluwer ‑ Medknow

[Downloaded free from http://www.jiaomr.in on Tuesday, June 5, 2018, IP: 80.110.94.101] Nagi, et al.: Tooth coronal index and age estimation in adults

were performed on mandibular second molars to estimate dental age.[4,12] The present study was undertaken in the Department of Oral Medicine and Radiology, New Horizon Dental College and Research Institute, Bilaspur, Chhattisgarh, India with the aim to evaluate reliability of dental age assessment through tooth coronal index (TCI) on digital panoramic radiographs.

Materials and Methods Participants

A total of 100 digital panoramic radiographs, obtained through SINORA ORTHOPHOS XG Panoramic Machine, were selected for the study from the archives of department based on the inclusion and exclusion criteria. The digital panoramic radiographs of 100 subjects of Chhattisgarh aged 20–70 years were analyzed for the following criteria: 1. It should have good contrast and should have no distortion. 2. Radiograph should present good image and good morphology of selected tooth with complete root formation, i.e., mandibular second premolar and mandibular first molar.

Figure 1: Panoramic image showing measurements on right mandibular first molar. To calculate TCI, CH was measured vertically (yellow line) straight from the cervical line to the tip of the highest cusp (represented by red line). CPCH was measured (yellow line) vertically from the cervical line to the tip of the highest pulp horn (red line)

Exclusion criteria

Digital panoramic radiographs with distorted image, carious/grossly decayed second premolar, molars or periapical pathology, prosthesis, restored selected teeth, missing selected teeth, severely attrited or fractured selected teeth, rotated or malaligned selected teeth, and teeth with any developmental anomalies were excluded from the study.

Radiographic measurements

All 100 panoramic radiographs were subjected to radiographic measurements. They were exported to JPEG image format by using trophy Sidexis, Digital Image and Communications in Medicine (DICOM) software (Dentsply, Sirona). The measurements were performed on these JPEG images by using Adobe Photoshop 7.0 software (Adobe, California). All the measurements were recorded in millimeters (mm).

Measurement of TCI

A straight line (cervical line) was traced from the cemento enamel junction, which is the division between anatomical crown and root. Coronal height (CH) was measured vertically straight from the cervical line to the tip of the highest cusp according to Moss et al.[13] Coronal pulp cavity height (CPCH) was measured vertically from the cervical line to the tip of the highest pulp horn according to Ikeda et al.[14] The measurements provided the TCI of each tooth, which was then calculated as follows [Figures 1-3].

Figure 2: Panoramic image showing measurements on right mandibular second premolar to calculate TCI

TCI = CPCH × 100/CH The measurements were displayed in mm along with captured image for further identification and reference. Intra observer measurements of three variables (CH, CPCH, and TCI) were also done. In the present study, mean estimated age by TCI was correlated with the real age of the subject.

Statistical analysis

The calculated data were entered in a Microsoft Excel spreadsheet. Statistical analysis was done using the statistical

Figure 3: Schematic representation of measurements taken of a panoramic radiograph for mandibular first molar and second premolar

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analysis software, Statistical Package for the Social Sciences, Version 20.0 (SPSS Inc.,Chicago,IL,USA). Pearson’s correlation coefficient was applied between the actual age and TCI of mandibular second premolar and first molar. Unpaired t‑test was used to compare the difference between the actual age and TCI for both mandibular first molar and second premolar. P value ≤ 0.05 was considered statistically significant.

Results Digital panoramic radiographs of 100 subjects were analyzed, and by using TCI, there was negative correlation observed between the real age and TCI of mandibular Table 1: Pearson correlation test showing correlation between real age and TCI of mandibular first molar

Original age

TCI mandibular firstmolar

Original age

TCI mandibular first molar

1

−0.092

100 −0.092

0.0365 100 1

0.365 100

100

Pearson correlation Sig. (two‑tailed) n Pearson correlation Sig. (two‑tailed) n

Table 2: Pearson correlation test showing correlation between real age and TCI of mandibular second premolar

Original age

TCI mandibular secondpremolar

Original age

TCI mandibular secondpremolar

1

−0.168

100 −0.168

0.096 100 1

0.096 100

100

Pearson correlation Sig. (two‑tailed) n Pearson correlation Sig. (two‑tailed) n

first molar (r = −0.092, P = 0.365) [Table 1] and second premolar (r = −0.168, P = 0.096) [Table 2]. Using unpaired t‑test, statistically significant difference was observed between the mean real age (38.3100 ± 13.30276) and TCI (36.5847 ± 8.34997) for mandibular first molar with a P-value 0.000 [Table 3]. Also, for mandibular second premolar, the difference between TCI (34.1821 ± 7.511759) and mean real age (38.3100 ± 13.30276) was statistically significant (P = 0.000) [Table 4].

Discussion Determination of age of the individual for administrative, ethical reasons, and medico‑legal purposes is one of the most important aspect for the forensic odontologists, and various studies have suggested that dental pulp size decreases with increasing age due to apposition of secondary dentin, thus making secondary dentin apposition as the best method to estimate age even beyond 25 years.[3,4] “Secondary dentin” is the calcified nontubular substance deposited by the pulp on the walls of the pulp chamber and root canal and it continues throughout the life. As regular secondary dentin is laid down on the pulpal surface of the primary dentin, the pulpal cavity decreases in size with age.[15] It has been reported that this secondary dentin apposition is not uniform all over the pulpal cavity, i.e., in case of molars, it is more over the roof and floor, thus reducing the height rather than width of the pulpal chamber.[3,15] Assessment of age by reduction of secondary dentin apposition can be measured by cross‑sections of teeth, using histological and radiological methods. In our study, we used panoramic radiographs because in the same radiograph all the teeth along with alveolar bone in jaws can be measured, they have high reproducibility, digitization, and computerized storage of panoramic radiographs. Moreover, radiographic techniques are less time‑consuming, need no extraction, can be applied to both living and dead, and there is no use of specialized equipment. Several studies in the literature used digital panoramic radiographs for assessment of age.[3,4,11] Paewinsky et al. measured pulp chamber size of six types of teeth on digital panoramic radiographs of individuals aged

Table 3: Comparison between mean real age and TCIof mandibular second premolar by unpaired t‑test Original age TCI mandibular firstmolar

No. of participants

Mean

Std.deviation

Std.error mean

t‑value

Sig.(two‑tailed)

100 100

38.3100 36.5847

13.30276 8.34997

1.33028 0.83500

28.799 43.814

0.000

Table 4: Comparison between mean real age and TCIof mandibular first molar by unpaired t‑test

Original age TCI mandibular secondpremolar

66

No. of participants

Mean

Std.deviation

Std.error mean

t‑value

Sig. (two‑tailed)

100 100

38.3100 34.1821

13.30276 7.51759

1.33028 0.75176

28.799 45.469

0.000

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14–81 years and found significant correlation between decrease in pulp chamber size with age with r2 highest for maxillary lateral incisors.[16] Talabani et al.[11] measured TCI of 96 mandibular first molars on digital panoramic radiographs and strong negative correlation was observed between TCI and age (r2 = 0.49, P = 0.0000). Gustafson was the first to introduce secondary dentin measurement method for age estimation.[17] In 1925, Bodecker established the apposition of secondary dentin and correlated it with age.[18] Later, various studies were conducted on periapical and panoramic radiographs using TCI and in these correlation of TCI with dental age was also done. In 1995, Kvaal et al. established significant correlation between TCI for molars and premolars and dental age (r2 = −0.650 to −0.799, P