Role of Orthopantamograph in Forensic Identification: A Retrospective Study Among Chennai Population.

CONTEXT: Identification of unknown corpse can be established by their body features and belongings; when the features are distorted, it becomes a challenge for the forensic experts. Orthopantamograph (OPG) analysis is a simple, noninvasive, economic, and reliable method to sort for identification of the unidentified. AIM AND
OBJECTIVE: The aim of this study was to assess the efficacy of OPG in age and sex determination. The objective of our study was to evaluate various measurements on the mandibular ramus and to correlate them with the age and sex of an individual. SETTINGS AND
DESIGN: A retrospective study was conducted using 150 OPGs that were taken in the Department of Oral Medicine and Radiology using Orthophos XG3 OPG machine. The mandibular ramus measurements were carried out using WebPlot Digitizer v 4.1. The measurement was statistically assessed. STATISTICAL ANALYSIS USED: SPSS version 20 was used for discriminate analysis, correlation, and regression analysis.
RESULTS: The male population showed higher values of ramus measurements compared to the female population. A regression equation was positively drawn to estimate the age of the unknown individual.
CONCLUSIONS: Coronoid height is the main predictive factor in age estimation of an individual irrespective of the gender whereas gonial angle is the extrapolative tool in gender prediction.

INTRODUCTION

Identification and recognition of an individual is very critical when the bodies are damaged beyond recognition.[1] However, age and gender are the prime sought in the identification process; skeletal components plays a vital role in the course. Among the skeletal tissue, skull along with mandible infers a reliable clue.

As the environmental factor influences the characteristics of skeletal system morphology, there exists enormous anatomical difference as per the topography variation. This study focuses on age and gender variation in mandibular ramus and gonial angle using an orthopantamograph (OPG) among Chennai population.

MATERIALS AND METHODS

The study was conducted after obtaining approval from institutional human ethical committee at Sathyabama Dental College and Hospital (IHEC/study no 050). The OPGs taken in the Department of Oral Medicine and Radiology for various diagnostic purposes with complete natural dentition were included in the study, whereas distorted OPGs, OPG with pathology, jaw discrepancies, those with jaw discrepancies, or malocclusion (Class II/Class III) were excluded from the study. Orthophos XG 3 OPG machine was used to make the X-rays.

The study comprised 1000 OPGs out of which only 150 OPGs were subjected to metric assessment considering the inclusion and exclusion criteria. The participants were between the age range of 3–70 years and they were classified into seven categories—group 1: 0–10 years, group 2: 11–20 years, group 3: 21–30 years, group 4: 31–40 years, group 5: 41–50 years, group 6: 51–60 years, and group 7: 61–70 years.

The OPGs were assessed, both left (L) and right (R) mandibular ramus as well as the gonial angle measurements were made. The measurements including maximum ramus width (MaxRW), minimum ramus width (MinRW), condylar height (ConH), coronoid height (CorH), projective ramus height (PH), and gonial angle (A) were recorded bilaterally.[1] All the measurements were recorded in centimeters using WebPlot Digitizer v 4.1 software by mouse-driven method. The obtained values were statistically analyzed with SPSS version 20.

RESULTS

When the measured parameters were statistically evaluated (t test) for gender differences [Table 1], MaxRW (R/L), ConH (R/L), CorH (R/L), CorH (R/L), PH (R/L), and gonial angle (R/L) showed highly significant differences statistically between the genders P < 0.01, whereas MinRW (L) and ConH (L) showed less significance (P < 0.05), and the MinRW (R) did not show any significant difference.

Table 1

Statistical test for significance between the genders (t test)

Parameters	Male	Female	t value	Significance
MaxRW (R)	36.63 ± 0.38	35.08 ± 0.37	2.94	0.004**
MaxRW (L)	36.36 ± 0.35	34.45 ± 0.40	3.59	0.000**
MinRW (R)	31.66 ± 0.32	30.97 ± 0.33	1.47	0.142 NS
MinRW (L)	31.85 ± 0.30	30.74 ± 0.34	2.42	0.016*
ConH (R)	64.87 ± 0.83	61.72 ± 0.73	2.85	0.005**
ConH (L)	64.20 ± 0.88	61.65 ± 0.71	2.26	0.025*
CorH (R)	65.59 ± 0.92	59.22 ± 0.76	5.40	0.000**
CorH (L)	64.39 ± 0.86	58.35 ± 0.72	5.41	0.000**
PH (R)	65.51 ± 0.92	60.33 ± 0.77	4.31	0.000**
PH (L)	65.43 ± 0.89	60.45 ± 0.73	4.34	0.000**
A (R)	122.45 ± 0.56	125.74 ± 0.64	−3.85	0.000**
A (L)	122.33 ± 0.49	125.84 ± 0.61	−4.41	0.000**

L = left , R = right, MaxRW = maximum ramus width, MinRW = minimum ramus width, ConH = condylar height, CorH = coronoid height, PH = projective ramus height, A = gonial angle, NS = nonsignificant

**Significant at P < 0.01

*Significant at P < 0.05

All the mandibular metric values were statistically significant (P < 0.01) between the age groups [Table 2] (analysis of variance), which ranged between 5 and 70 years except for the gonial angle (P < 0.05).

Table 2

Statistical test for significance (analysis of variance) between each age group for various parameters

Parameters	Age group 1	Age group 2	Age group 3	Age group 4	Age group 5	Age group 6	Age group 7	F value	Significance
MaxRW (R)	30.01 ± 0.54	36.44 ± 0.55	36.81 ± 0.54	37.42 ± 0.55	36.17 ± 0.62	38.06 ± 0.20	36.74 ± 0.27	28.85	0.000**
MaxRW (L)	30.21 ± 0.60	36.55 ± 0.63	35.74 ± 0.61	36.28 ± 0.45	35.07 ± 0.87	37.80 ± 0.20	36.79 ± 0.25	19.14	0.000**
MinRW (R)	28.55 ± 0.53	32.17 ± 0.55	32.43 ± 0.64	30.45 ± 0.48	30.70 ± 0.73	32.69 ± 0.36	32.24 ± 0.42	7.50	0.000**
MinRW (L)	28.51 ± 0.54	32.00 ± 0.61	31.88 ± 0.61	30.94 ± 0.47	30.30 ± 0.73	33.16 ± 0.34	32.44 ± 0.28	7.70	0.000**
ConH (R)	49.82 ± 1.09	64.07 ± 0.89	66.89 ± 0.99	64.87 ± 0.66	66.64 ± 1.24	70.46 ± 0.57	62.11 ± 0.43	53.59	0.000**
ConH (L)	49.95 ± 1.09	62.90 ± 0.96	67.21 ± 1.00	64.61 ± 0.59	66.10 ± 1.24	68.62 ± 1.50	62.75 ± 0.49	39.49	0.000**
CorH (R)	47.84 ± 1.30	63.43 ± 0.96	64.38 ± 1.11	67.87 ± 1.21	62.94 ± 1.32	69.17 ± 0.88	62.44 ± 0.51	41.646	0.000**
CorH (L)	47.99 ± 1.23	60.93 ± 1.01	62.64 ± 1.04	66.08 ± 1.06	63.40 ± 1.29	68.84 ± 0.86	61.93 ± 0.48	40.05	0.000**
PH (R)	48.88 ± 1.26	62.44 ± 1.05	66.34 ± 1.05	66.86 ± 1.17	65.83 ± 1.35	70.72 ± 0.67	61.00 ± 0.28	43.84	0.000**
PH (L)	49.48 ± 1.13	61.97 ± 1.02	66.44 ± 1.04	67.11 ± 1.14	65.28 ± 1.29	70.35 ± 0.73	61.52 ± 0.37	43.72	0.000**
A (R)	125.91 ± 1.23	124.25 ± 1.23	123.00 ± 0.99	123.94 ± 0.89	123.26 ± 1.81	123.23 ± 1.05	125.70 ± 0.83	1.03	0.408 NS
A (L)	125.53 ± 1.14	124.58 ± 1.21	124.03 ± 0.97	124.51 ± 0.80	122.34 ± 1.75	123.05 ± 0.83	124.42 ± 0.68	0.83	0.552 NS

L = left , R = right, MaxRW = maximum ramus width, MinRW = minimum ramus width, ConH = condylar height, CorH = coronoid height, PH = projective ramus height, A = gonial angle, NS = nonsignificant

**Significant at P < 0.01

Pearson correlational analysis [Table 3] revealed that there exists definite correlation between the various age groups and mandibular linear measurements but not with the gonial angle.

Table 3

Pearson correlational analysis of the mandibular measurements with age

MaxRW (R)	MaxRW (L)	MinRW (R)	MinRW (L)	ConH (R)	ConH (L)	CorH (R)	CorH (L)	PH (R)	PH (L)	A (R)	A (L)
0.459**	0.415**	0.229**	0.279**	0.469**	0.454**	0.464**	0.526**	0.459**	0.467**	−0.03(NS)	−0.11(NS)

L = left , R = right, MaxRW = maximum ramus width, MinRW = minimum ramus width, ConH = condylar height, CorH = coronoid height, PH = projective ramus height, A = gonial angle, NS = nonsignificant

**Significant at P < 0.01

Multiple linear regression analysis shows the CorH (R/L), MaxRW (R), and gonial angle (R) are significant parameters contributing to the prediction of age of an individual and the equation for age estimation is AGE = −190.68 + 1.065 [MaxRW (R)] − 0.605 [CorH (R)] + 1.766 [CorH (L)] + 0.925 [A (R)] + µ

DISCUSSION

Most often, dentists are sought by the forensic experts in case of mass fatalities and situations where ambiguity over personal identification arises mainly related to the age and gender discrimination. Though there exist variety of methods to for the same, OPG can be applied when the external features are distorted.

Various studies had been conducted by many researchers to understand the applicability of mandibular metric analysis specifically the vertical, horizontal, and angular measurements[23456] in forensic odontology.

Our study reveals that CorH, ConH, and projected height of the mandible increase with age, and at sixth decade, there is slight reduction in values, but the studies by Leversha et al.[1] and Poongodi et al.,[7] show a decrease in ramus height with increase in age. The gonial angle did not show significant difference with age, which is similar to the study by Taleb and Beshlawy[5] but the mean value increased in the early age as well as in the sixth decade; however, other studies report that there is significant difference with age.[257] Studies by Taleb and Beshlawy[5] and Sandeepa et al.[6] reveal that CorH shows fluctuation with aging, which is parallel to our study.

There is statistically significant difference in all the measurements of mandible between the genders except for the minimal ramus width and ConH, which had no significance/very less significance in gender prediction that contradicts few other studies where the minimal ramus breadth and ConH[789] had a greatest sexual dimorphism[3410]; however, the prediction about MinRW coincides with the findings of Sandeepa et al.[6] Damera et al.,[8] states that the projected ramus height is considered as a relevant factor in gender discrimination which is similar to our study. The gonial angle had differences between the male and female, which contradicts the studies conducted by Leversha et al.,[1] Sandeepa et al.,[6] Al-Shamout et al.,[211] but our conclusion is similar to other studies[589] where female had higher values of gonial angle than male; however, the study by Sandeepa et al.[6] reveals male had greater gonial angle. There was no difference between the right and left side gonial angle similar to other studies[2]

CONCLUSION

The use of OPGs in dentistry is not only limited to disease diagnosis and treatment planning; the varied anatomical landmarks reach the interest of forensic odontologist and hence mandibular metric values are proved to be a definite variable in gender and age determination. All the studies confirm that males have a significantly higher values compared to females[234567891011] with a variation in the metric values among various age groups. However, the evaluation of mandible using OPG was assessed by many researchers for its forensic applications. Standard metric values for each population must be drawn and archived in future for convenience and instant reporting.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.