| Abstract|| |
Aim: To estimate the age by evaluating the length of dentin translucency in ground sections of extracted teeth using digital scanner and tools of GIMP 2.8 software for dental age estimation. Materials and Methods: Fifty extracted single-rooted permanent teeth from 50 different individuals and their 0.25-mm thick sections were prepared. Each tooth section was scanned and the length of dentin translucency was measured in GIMP 2.8 software. Results: A linear relationship was observed between dentin translucency and age in the regression analysis. Pearson's correlation analysis showed that there was positive correlation (r = 0.93, P = 0.001) between dentin translucency and age, and the difference between the chronologic age and real age is ± 4.88 years. Conclusion: Dentin translucency in the apical part of the tooth can be used for estimating the age of an individual. A method to digitally select and measure translucent root dentin length was used here. This software method is easy to use and less time-consuming. The measurements obtained using this method are more precise and thus help in more accurate age estimation. Considering these benefits, this study recommends the use of digital method to assess translucency for forensic purpose.
Keywords: Age estimation, dentin translucency, forensic odontology, GIMP 2.8 software
|How to cite this article:|
Shah JS, Ranghani AF, Limdiwala PG. Age estimation by assessment of dentin translucency in permanent teeth. Indian J Dent Res 2020;31:31-6
|How to cite this URL:|
Shah JS, Ranghani AF, Limdiwala PG. Age estimation by assessment of dentin translucency in permanent teeth. Indian J Dent Res [serial online] 2020 [cited 2021 May 11];31:31-6. Available from: https://www.ijdr.in/text.asp?2020/31/1/31/281809
| Introduction and Review|| |
Age is the length of time that a person has lived or a thing has existed. Age plays an important role in every aspect of life. Teeth and the oral structures play an important role in identification of an individual. Age estimation by dentition is an important subspecialty of forensic sciences. Forensic odontology is a major branch of forensic science, as the dental tissues are the strongest tissue in the human body, and therefore their characteristics remain unchanged even after long periods of stay in extreme environment.,
Several methods have been developed to estimate age based on dental tissue and tooth morphology. Morphologic and radiographic methods (Schour and Massler's method, Demerijian's methods, Willem's methods, from third molar and Kvaal's method) are useful in living individuals at children and adult age, whereas histological and biochemical methods (Gustafson's technique, Johanson's technique, Bang and Ramm technique, cemental annulations, and aspartic acid racemization) are useful in dead victims.
Dentin forms the major bulk of the tooth. Dentin develops uniformly from the infancy to adolescence. After adolescence, the dentin undergoes physiological changes such as sclerosis. In the dental method of identification, the Gustafson's morphohistologic approach is a most widely used method and includes the following six parameters, that is, attrition, gingival recession, thickness of secondary dentin, cementum apposition, root resorption, and root dentin translucency. All these parameters considered were in intact teeth. Among these parameters, dentin translucency is the sole significant parameter for dental age estimation as dentin translucency is least afflicted by environmental and pathological processes, demonstrating symmetrical distribution on both sides of the jaws.,
Miles states that the translucency of root apex seems to be the most reliable or the closest straight line relationship with age. Bang and Ramm first examined the roots of intact teeth with naked eye, measuring the total length of the root and the distance between the apex and the borderline between translucent and opaque dentin. At a later stage, they examined ground longitudinal sections. The image of each section was projected onto paper, and the area of total dentine and translucent dentine was outlined and then measured. They concluded that there is a significant increase in root transparency with age. They found translucency of root dentine to start at the apex of the tooth and to gradually extend more coronally with age.
Traditionally, measuring the age based on dentin translucency was done with an aid of Vernier caliper. With technological advancement, digitalization by software method seems to be a better alternative., Acharya described a method to measure translucency on sectioned teeth using commercially available computer hardware and Adobe Photoshop software. Translucency measurements on 81 tooth sections were obtained using digital method and compared with those obtained using a caliper. Correlation coefficients of translucency measurements to age were statistically significant for both methods (P < 0.001) and marginally higher for the digital approach (r = 0.49). He concluded that computer-based translucency measurement contributed best to estimate age than Vernier caliper method. Hence, the purpose of this study is to estimate the age by evaluating the length of dentin translucency in ground sections of extracted teeth using digital scanner and tools of GIMP 2.8 software for forensic purpose.
| Materials and Methods|| |
Fifty extracted human permanent teeth from the individuals of age ranging from 20 to 75 years were obtained from the Department of Oral and Maxillofacial Surgery, Govt. Dental College and Hospital between 2015 and 2017. Institutional ethical clearance was obtained for the same. Single-rooted permanent teeth extracted for various therapeutic reasons such as malocclusion/orthodontic treatment, periodontal disease, or prosthetic purpose were taken for the study. Grossly decayed teeth, impacted teeth, teeth with severe attrition, abrasion, and erosion, teeth with external and internal resorption, and multirooted teeth were excluded from the study.
The age and sex of the patient from whom teeth were extracted was recorded along with date and reason for extraction, and consent from the patient was taken. Immediately after extraction, the tooth was preserved in 10% neutral formalin, and following fixation, first manual grinding was done with micro motor and diamond disks and then hand grinding using Arkansas stone, one side rough and the other side fine. Grinding was done first on the rough side of the stone by making approximately equal grinding movements on either side so as to reach the center of the tooth. The teeth were sectioned longitudinally to 250 μm in the buccolingual plane. The thickness of sections was measured using digital Vernier caliper. All specimens were labeled and stored for record purpose [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5].
Digital translucency measurement
The computer hardware used in the method included a HP 2.2 GHz CPU with 4 GB RAM and a 15.6-inch LCD monitor and a Canon scanner (Canoscan Lide 100, Canon, Canoscan). The long axis of the section was aligned parallel to the y-axis of the scale. Prior to scanning, the scanner setting was verified to be 100% of the original to ensure life-size scanned images. Subsequently, an image of 600 dpi resolution of the section with scale was obtained. The scanner lid was kept open while scanning and ambient light conditions kept to a minimum [Figure 6]. (Note: keeping the lid closed obstructs passage of the optical scanning light through the translucent zone, rendering the entire tooth section opaque.)
Scanned images were imported to GIMP 2.8 software for viewing and measuring the extent of translucency. Translucent dentin appears as a dark region on the tooth section when compared with the other dental tissues. Translucency was measured using a number of tools available on GIMP 2.8 software. For measuring translucency, GIMP's in-built “rulers” were activated along the edges of the image; if they are not visible, hold down Ctrl + Shift + R to activate it. The units were ensured to be in millimeters in the Status Bar. Once the rulers were activated, guides were placed corresponding to the apical and coronal extent of root dentin translucency by clicking the cursor within the x-axis (horizontal part) of the ruler and dragging onto the image. To move a guide to the desired location, the Move Tool was used. Once the respective guides had been placed at the apical and coronal extents of root dentin translucency, the distance between them was obtained using the Measure Tool on the Toolbox. Using this tool, a line was drawn between the guides; the distance (D1) was displayed in the Status Bar [Figure 7]. To assess potential interobserver variation, translucency length was again measured by the second observer on all 50 tooth sections and translucency length was recalculated.
|Figure 7: Measurement of transparency by using GIMP 2.8 software (a) Group A, (b) Group B, (c) Group C, (d) Group D, (e) Group E|
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The data were coded and entered into Microsoft Excel spreadsheet 2013. Analysis was done using SPSS version 20 Windows software program. The independent t-test (for quantitative data within two groups) and analysis of variance (for quantitative data within three groups) were used for quantitative data comparison of all clinical indicators. Multivariate test regression analysis was also used to compare study variables. Level of significance was set at P ≤ 0.05. Pearson's correlation coefficients obtained for both observers were noted and the regression equations derived. A linear relationship between dentin translucency length and age in the regression analysis was found. Regression analysis showed the following results:
- Intercept: 19.03
- Coefficient of slope: 4.81
- Correlation coefficient (r): 0.93 denotes the correlation between age and length of translucency
- Spearman correlation: 0.945906
- Pearson correlation: 0.945851.
Based on the available data, the regression equation derived was
- Predicted age = 19.03 + 4.81 × length of dentin translucency (mm).
| Results and Discussion|| |
The study was carried out on 50 extracted teeth, and of these 9 were central incisors, 17 were lateral incisors, 4 were canine, 10 were first premolars, and nine were second premolars. These 50 samples were equally divided into five groups according to age, that is, groups A, B, C, D, and E. Each group consisted of 10 samples. The mean difference of length of dentin translucency between male and female in groups A, B, C, D, and E was 0.09, 0.3, 0.47, 1.39, and 1.41, respectively. Accordingly, P values were 0.71, 0.49, 0.63, 0.14, and 0.28, respectively. This suggests that gender has no significant influence on age estimation with advancing age when root dentin transparency is considered [Table 1]. Similar results were found in previous studies.,
|Table 1: Genderwise distribution of length of translucency for groups A-E|
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The mean length of dentin translucency in groups A, B, C, D, and E was 1.9, 2.97, 5.49, 7.01, and 9.41, respectively, for observer 1 and 2.05, 2.99, 5.28, 7.95, and 10.11, respectively, for observer 2. P value was 0.001 which was highly significant [Table 2]. In this study, a strong correlation (0.93) between the length of translucency and advancing years of age was found. A definite and gradual increase in the extent of the root dentin translucency with advancing years of age was noted. Previous studies have demonstrated that the extent of the root dentine translucency can be a reliable indicator of individual's age.,,,,,,,,,,,,
|Table 2: Comparison of length of dentin translucency among observer 1 and 2 in various age group|
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The age group selected for this study was from 20 to 75 years. The reason behind this selection of age group is that sclerosis begins at the root apex after the individual has reached the age of 20 years, so less than 20 years of age will give inaccurate results. Above 75 years of age due to reduction in the stimulus for formation of sclerotic dentine, underestimation of age may occur.
Multirooted teeth were not included in this study because these teeth are very strong and hard and it is difficult to make ground section. Puneeth et al. used multirooted teeth in their study using a hard-tissue microtome. Also, teeth with severe attrition, abrasion, erosion, and grossly decayed teeth were excluded from the study because these pathologic conditions stimulate translucency of teeth.,
In this study, manual method for sectioning of teeth was used due to easy availability of diamond disc and Arkansas stone rather than hard-tissue microtome. Acharya attempted a similar study wherein the teeth were sectioned using hard-tissue microtome.,
There are compelling reasons for using the digital method over the conventional method for obtaining translucency measurements. Digital method allows better visualization of the junction between translucent and nontranslucent zones, giving scope for “fine-tuning” the measurements. A magnifier can also be used in the conventional method; however, irrespective of magnification, an impediment to caliper-based measurements is that the caliper beaks cannot always be stabilized on thin tooth sections as there is risk of damaging it. On the other hand, the “touch-free” or “noninvasive” digital evaluation prevents potential damage to thin tooth sections. The scanned images can be easily stored and conveniently retrieved for future use, irrespective of the condition of the actual tooth section. Various authors also concluded that computer-based translucency measurements contributed best to estimate than age.,,,,,,,
Dentin translucency seems to be the most reliable in predicting the actual age. Root dentin transparency develops due to progressive sclerosing of the tubules, first at the root apex, and then advancing coronally. This appears dark in reflected light and transparent in transmitted light. This can be visualized in ground sections of the teeth. The smaller diameter and less number per unit area of dentinal tubules toward the root apex and root surface have been considered as reasons for the commencement of translucency from the root tip and periphery. De Jonge reported that the average width of dentinal tubules is about 3.2 μm in young individuals, narrowing to about 1.5 μm at 50 years and down to 1.2 μm at 70 years of age thereby causing increased translucency as age advances.
Tomes was the first investigator to describe translucent dentine. He wrote that translucency is the result of the consolidation of the dentinal tubules and he noticed that if the air in the dentinal tubules of a tooth is replaced by water, the tooth becomes more translucent. Bang and Ramm were the first to use dentin translucency alone for estimating age and reported significant increase in root translucency with age. The underlying process behind translucency of dentin is a result of fatty degeneration, physiological hardening during the life-time of the tooth due to increased deposition of the calcific matter, consolidation of the dentinal tubules, equalization of the normally different indices of refraction of the tubules and of the calcified dentine matrix, decreased diameter of dentinal tubules caused by increased intratubular calcification, and difference in refractive indices between intratubular organic and extratubular inorganic material is equalized, resulting in increased translucency of the affected dentin.,,
Dentin translucency as a parameter to assess age has distinct advantages over the other methods. It is one of the simplest methods to assess and estimate age. Moreover, it is least affected by environmental factors and the pathological process. It also shows symmetrical distribution on both sides of the jaws. Furthermore, translucency can be assessed macroscopically on intact teeth, although tooth sections provide better detail. Hence, in this study, the 250-μm sectioned teeth were used for best visualization of translucency.,,,,
In some cases, discrepancies were seen between actual age and age obtained from dentine translucency due to different reason. In group C, one sample showed overestimated age with discrepancy of 18.5 years [Figure 8]. Tooth was clinically sound, but after preparing the ground section, deep caries was present that involved underlying pulp. Increased translucency was due to caries that involved pulp which stimulated mineralization. In group E, one sample showed underestimated age with discrepancy of 5.8 years. This could be due to slowing down of sclerotic dentin formation because it might have attained the highest level by blocking almost all the dentinal tubules thereby giving a static value of translucency while one sample showed overestimated age with discrepancy of 6 years due to attrition which stimulated mineralization of dentin [Figure 9].
| Summary and Conclusion|| |
The following conclusions can be drawn from this study:
- In this study, correlation coefficient (r) = 0.93. The strong positive correlation between age and length of translucency which denotes significant increase in root translucency with advancement of age [Figure 10] and coefficient of determination (r2) = 0.98 which denotes this study was accurate.
- In this study, the difference between the chronological age and real age is ± 4.88 years.
- The formula generated from this study is age = 19.03 + 4.81 × length of dentin translucency (mm)and can be used for forensic purpose.
- Dentin translucency in the apical part of the tooth can be used for estimating the age of an individual. A method to digitally select and measure translucent root dentin length was used here, and it produced a positive correlation between age and translucency of dentin.
- The custom-built software program used in this study is a commercially available and widely used image editing software. Furthermore, this method is easy to use and less time-consuming. The measurements obtained using this method are more precise and thus help in more accurate age estimation. Considering these benefits, this study recommends the use of digital method to assess translucency for dental age estimation.
|Figure 10: Correlation between age and length of dentin translucency (Age group=20 to 75 years (Scatter plot of X and Y)|
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Conflicts of interest
There are no conflicts of interest.
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Ashish F Ranghani
Department of Oral Medicine and Radiology, Government Dental College and Hospital, Asarwa, Ahmedabad, Gujarat
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]
[Table 1], [Table 2]