Introduction

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A man is born with an identity and justifies dying with the same. All human beings inhabited this earth belong to the same species i.e. Homo sapiens. No two individuals are exactly alike, even monozygotic twins differ in some aspects. There is certain body structure which have tendency to undergo change in varying degree from birth to death, in health & disease. In the development of skeleton various factors have an effect on producing variance in skeletal proportion among different geographic regions. Anthropometry is the technique of quantitative measurement of the human body used for identification, whether on living or dead or on skeletal evidence. Forensic medicine is a multidisciplinary science mainly deals with scientific examination and assessment (qualitative as well as quantitative) of individuals who have been or are suspected to have been injured or killed by external influence such as trauma or intoxication [1].

The uniqueness of anatomical structures and their discrepancy provide the basis for forensic identification of unknown diseased persons [2]. Fingerprint analysis, DNA matching, & anthropological studies can aid the process of individual recognition. French police officer, Alphonso Bertillion (1853-1914) fabricated the first anthropometric scientific system based on the physical measurement for identifying criminals in 1880 [3].

Skull has exponential potential in identifying an individual, which is attributed to the presence of several structures that can be used in identification, such as dentition, cranial patterns, paranasal sinuses & nasal septum [3].

Frontal sinuses (FS) are not evident at the time of birth and begin to develop during the second year of life [4]. Frontal sinus (FS), the most anterior & superior paranasal sinus located within the frontal lobe is the last sinus to develop & is comprised of two symmetric pneumatic compartments divided by a septum which continued with the Crista galli & cribriform plate of the ethmoid inferiorly. It is lined by a mucous membrane illustrated respiratory epithelium with variable normal thickness of 0.07-2mm, able to secret a moistening & protective fluid which provide immune defense & air filtration. It serves various functions such as: reducing the weight of skull, humidifying & regulating air temperature [5].

Radiographically frontal sinus is not visible until the age of five yrs. Belaldavar C et al ascertained that the development of the frontal sinus is completed by about 20 yrs of age & remains stable until further enlargement of the chambers which occurs as a consequence of bone resorption during advanced age [4].

Frontal sinus which is very resistant to trauma, likely to remain preserved in dismembered or burn corpses after mass disasters such as air crush [6].

In 1921, Schuller first studied frontal sinus & revealed its uniqueness in shape, complexity & individuality. Along with nasal septum patterns frontal sinus provides most interesting & significant information in forensic identification [7].

In the late nineteenth century the first detailed and systematic anatomical and physiological description of the paranasal sinuses were published by Zukerkandle [8].

As cone beam computed tomography is a precise & fast method it can be used to evaluate high resolution images depicting structural details. 3D scanning of area of interest, reduced radiation dosage & exposure time, and rendering superior quality images make CBCT better choice compared to conventional computed tomography (CT) [9].

The purpose of the present study was to inspect & identify the various frontal sinus patterns & nasal septum patterns present and assess their usefulness in personal identification in forensics using CBCT radiographs.

Materials and Methods

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The study was carried out on 150 CBCT projections between the age group of 20 and 50, visiting the Department of Oral Medicine and Radiology, at Subharti Dental College and Hospital, Meerut. The radiographic data/slices were observed for frontal sinus and nasal septum patterns. The frontal sinus was evaluated for symmetrical, asymmetrical (right or left), unilateral aplasia (right or left) and bilateral aplasia. (fig.1) [10].

Figure 1

The formula for calculation of symmetry was the greatest dimension horizontally was measured from the central septum on both sides. The difference between the right and left side dimensions was divided by the greatest dimension and then multiplied by 100 [10].

If the percentage was below 20 it was considered symmetrical and vice versa.

[Right side dimension ~ Left side dimension] x 100
Greatest dimension

The nasal septum was classified according to deviation in septa as straight, simple deviation to the right or left side, sigmoid & reverses sigmoid type. (fig.2) [10]. The combined frontal sinus & nasal septum was recorded for each individual and all the results obtained were tabulated and statistically analyzed (figure 3,4).

Figure 2

Figure 3

Figure 4

Based on the age, the study was carried out in 3 groups:

Group I: consisted of 50 CBCT images obtained from age ranges from 21-30 years.

Group II: consisted of 50 CBCT images obtained from age ranges from 31-40 years.

Group III: consisted of 50 CBCT images obtained from age ranges from 41-50 years.

The frontal sinus symmetry was observed in 97 individuals (53 males &44 females) (64.67%). Asymmetry was observed in 36 individuals (14 males & 22 females) (24%). Unilateral Aplasia of frontal sinus was seen in 12individuals (6 males & 6 females) (8%). The frontal sinus was absent (bilateral Aplasia) in 5 individuals (2 males & 3 females) (3.33%).

Table 1

Graph 1

Straight nasal septum pattern was seen in 15 individuals (5 males & 10 females) (10.00%). Sigmoid pattern was noticed in 10 individuals 94 males & 6 females) (6.67%) and reverse sigmoid pattern was observed in 1 individual (1male & o female) (0.67%) (Table & Graph 2) (Table 3-5)

In our study the dimension of frontal sinus of each individual was observed and found to be unique. This clearly depicts the uniqueness of frontal sinus in forensic identification.

Table 2

Graph 2

Table 3

Table 4

Table 5

Discussion

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Identification of gender of unknown persons is of utmost important in forensic investigations, like anthropologic, medical and dental forensic studies [11]. The uniqueness of the frontal sinus anatomical cavity, which is not even repeated in monozygotic twins, establishes its significance in forensic community [12]. Combined frontal sinus & nasal septum patterns may also be helpful for identification and gender determination of an individual in forensic study [13].

Radiographic assessment of various skeletal structures together with skull is potentially effective for identification either in human remains or in living person [14].

Compared to CT, the low dosing requirements, high-quality bony definition and the compact design afforded by CBCT scanners have made them appealing for office-based and intra-operative scanning of frontal sinuses [15].

As the development of frontal sinus goes up to 20 years and the growth of nose increases up to 18 years of age, the study included the individuals from the age group of 20-50 years.

Our study showed symmetrical frontal sinus seen in 97 patients (64.67%) which was in accordance with that of the study conducted by Kavita Verma [16] et.al. (77.50%). K Saraswathi Gopal et al. [3] studied on 80 individuals & observed that frontal sinuses were absent (bilateral Aplasia) in four individuals (5%). Unilateral Aplasia was seen in two individuals (2.5%), in our study B/L Aplasia seen in 3.33% & U/L Aplasia seen in 8% individuals. The variation may due variation in sample size, while symmetrical & asymmetrical patterns of frontal sinus resembles to our study. Isabela G. G. Choi [12] conducted a study in which absence of frontal sinus (B/L Aplasia) was not observed in their study while our study showed 3.33% B/L Aplasia of frontal sinus. The present study differed from that done by Taniguchi M et al., [17] in various aspects. They demonstrated that, 43.1% cases had symmetry of frontal sinus and 56.6% had asymmetrical patterns which are contrary to findings of our study (64.67% symmetrical and 24% asymmetrical patterns of frontal sinus). Our findings were consistent with the results reported by Maria Priscilla David et al. which showed that Frontal sinus symmetry was observed in 29 (58%) individuals and asymmetry was observed in 16 (32%). Complete absence of frontal sinuses (bilateral aplasia) seen in two individuals (4%). Unilateral aplasia was noticed in three individuals (6%) [10].

Maria Priscilla David et al. conducted study and noticed that the straight nasal septum was seen in 22%, right deviation in 42%, and left deviation in 30% individuals [10]. Sigmoid was seen in 2%, reverse sigmoid in 2% which were 6.67% & 0.67% respectively in our study. Taniguchi et al. [17] reported highest cases of left deviation of nasal septum 36.7% whereas present study showed highest reported case of right nasal septum 43.33%. Straight nasal deviation noted in 13% individuals in Taniguchi et al. study which is consistent with our study 10%. K Saraswathi Gopal et al [3] observed Sigmoid & reverse sigmoid data (5% & 8.75% respectively) which were varied as compared to our case with 6.67% & 0.67% respectively.

The drawback of our study is smaller sample size. In future further study with large sample size is required to study this correlation and significance.

Conclusion

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The parameter discussed in our study showed considerable individual variation in the nasal septum and frontal sinus pattern as viewed in full skull cone beam computed tomography images. In present study the mean value of horizontal dimensions was greater for males than females in North Indian population. The mean dimension of left FS (≈ 28mm) was comparatively larger in males while the right FS dimension (≈ 26mm) was larger in females (Table 6 & 7)

The significant difference was also observed in nasal septum patterns for male & female. In male’s deviation is more on right side as compared to females which is more on left side. So it is concluded that male nasal septum is righter and the female septum is more left.

No statistically significant difference was found between age groups and measurements of frontal sinus.

Thus, our findings show that frontal sinus and nasal septum parameters can be used along with other factors for personal identification in mass disaster, crime scenes or if the body is severely decomposed.

Further studies are recommended to carry out research on a wide population size to achieve the accuracy level in gender determination.

Table 6

Table 7

References

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