Keywords
forensic anthropology - maxillary sinus - paranasal sinus
Introduction
The rapid urbanization and development of big cities and towns have led to an increase
in the graph of crime rate; as a result, we come across unknown dead bodies or skeletons
with unknown causes of death, few skeletons are badly disfigured or fragmented, as
such medico-legal cases are of great concern and are dealt by forensic medicine. Despite
rapid progress in various diagnostic methods, identifying skeletons and decomposing
human remains is one of the most challenging tasks in forensic medicine. The primary
concern of any skeleton analysis is the determination of gender and age.[1] It is of great importance since it is an initial step in personal identification,
and it can be used to rebuild biological profiles and narrow down diagnosis toward
correct possibilities of any unknown skeletons.[2] When bones that were used conventionally for estimation of gender are recovered
in fragmented, incomplete, or in a mixed state, gender and age determination can be
done using structures protected by denser bones and recovered intact. Thus, the maxillary
sinus (MS) can be used to estimate age and gender since it is undamaged even if the
skull or other bones are poorly disfigured.[3]
The anatomy of MS varies from person to person. The environmental conditions, genetic
diseases, and any past infections may affect the pneumatization process of MS; thus,
these complications lead to the anatomic and pathologic variation of MS.[4] An uncommon condition such as hypoplasia of MS may be seen unilaterally in 7 to
8% of cases and bilaterally in 2% of adults, and an extremely rare condition, aplasia
can also be seen in some cases.[5]
MSs differ significantly in shape, position, and size in different individuals, on
each side of the same individual, and in people with varying groups of age.[6]
[7] The MS extends to the roof of permanent teeth after deciduous teeth fall off. It
originates as an evagination of nasal mucosa into the maxilla; thus, such development
leads to an enormous quantity of anatomical variation in the MS of individuals.[8]
The sinuses develop within the bone of the viscerocranium and the MS is the first
paranasal sinus (PNS) to form. They are small at birth and after birth, enlarge with
the growing maxilla, and fully develop after the eruption of permanent dentition.[9]
Different dimensions of the MS can differentiate between gender and different age
groups.[10] The radiological modalities are considered as a gold standard for evaluation of
the actual anatomy of sinuses and are commonly used in forensic anthropology for gender
and age determination as they are very simple, cheap, and take less time compared
with conventional biochemical and histopathological methods.[11] The MS can be investigated by different imaging techniques and modalities, including
cone-beam computed tomography (CBCT), CT, and clinical examination of MS by either
intra- or extraoral methods.
CT is a noninvasive method that acquires an image using an X-ray. It can be used for
the evaluation of the MS. CT images are used to locate the anatomic structure and
give information about the different dimensions of the bone and its morphology.[4] It overcomes all the limitations of CBCT, like reducing CB-related artifacts in
images, providing higher resolution images, and decreasing scan time. It substitutes
the traditionally used X-ray imaging like plain radiographs, fluoroscopy, or dental
radiographs.[12]
CT scan provides an accurate assessment of PNS and craniofacial bones and gives a
precise measurement of the different dimensions of MS, that is, its width, height,
length, and volume. It also produces a three-dimensional (3D) image that allows complex
evaluation of the MS anatomy.[13]
MS dimensions by CT tools can reveal age and gender when other methods are indecisive.
CT is a magnificent imaging modality in recognizing unknown remains because it produces
higher resolution images and thus can evaluate sinus anatomy and provide precise measurements
of MS.[14]
[15]
This study was designed to adjudge the usefulness of MS volume for gender determination
using CT in forensic anthropology. Two-dimensional (2D) and 3D images were used for
measuring different dimensions of the MS and the sinus volume was measured to find
the variation in volume concerning different age groups and gender.
Materials and Methods
It was a retrospective study performed in the Department of Radiodiagnosis, Justice
K.S. Hegde Charitable Hospital, after receiving ethical clearance from the institutional
ethical committee. The study included a total of 90 patients (male 49 [54.4%] and
female 41 [45.6%]) from 18 to 55 years of age referred for CT PNS in our institute.
Patients were excluded based on the history of trauma related to MS. All scans were
performed on GE Elite Bright Speed (16-slice multidetector CT), and data was collected
from the Digital Imaging and Communications in Medicine (DICOM) software. Patients
were categorized into three different age groups: 18 to 25, 26 to 40, and 41 to 55
years of age.
The measurements were taken on 2D and 3D reconstructed images of both MSs. Measurements
were done using an inbuilt electronic caliper into a DICOM viewer software. The largest
linear measurements of the diameters like anteroposterior (AP), superioinferior (SI),
and mediolateral (ML) and distance between right (RMS) and left MS (LMS) were performed
on coronal and sagittal planes, and volume of the sinus was calculated using the formula
AP × ML × SI × 0.625.
The measurements were as follow:
AP diameter was measured on the sagittal images from the most anterior point to the most posterior
point of the RMS and LMS on 2D and 3D images.
ML diameter: It was measured on coronal images from the longest distance perpendicular from the
medial wall of the MS to the outermost point of the lateral process of both RMS and
LMS on 2D and 3D images ([Figs. 1] and [2]).
Fig. 1 (A) Measurement of anteroposterior (AP) diameter on two-dimensional (2D) and three-dimensional
(3D) images. (B) Measurement of mediolateral (ML) diameter on 2D and 3D images.
Fig. 2 (A) Measurement of distance between right and left maxillary sinus (MS) on two-dimensional
(2D) and three-dimensional (3D) images. (B) Measurement of superioinferior (SI) diameter on 2D and 3D images.
SI diameter: It was measured on coronal images from the longest point of sinus floor to sinus
roof of both MS on 2D and 3D images.
Distance between two
MSs: Measured on coronal planes of both 2D and 3D images.
Data and Statistical Analysis
Data and Statistical Analysis
The collected data was computed on Microsoft Excel 2010 and was analyzed using a Statistical
Package for Social Science version 20.0 (SPSS-IBM). The mean and standard deviation
of all individuals were calculated. An independent t-test was performed to compare dimensions and volume in males and females. Comparison
of dimensions and volume in different age groups using analysis of variance and a
paired t-test were used to compare LMS and RMS in both genders.
Result
The dimensions and volume of both the MS were greater in males than in females on
2D and 3D measurements. A significant difference was noted in the AP diameter of both
MS, in males and females on 2D and 3D images (p < 0.005). The mean AP diameter was greater in males than females, with a mean difference
of around 1.8 mm. The ML diameter was statistically insignificant in males and females
on both sides (p > 0.005). A significant difference was also noted in SI diameter in males and females
on a 2D image with a mean difference of 2.283 mm. The mean distance between the male
RMS and LMS was 29.37 ± 3 and 29.45 ± 3.79 mm on 2D and 3D, respectively. Females
had a mean of 28.21 ± 4.32 mm on 2D and 28.27 ± 4.31 mm on 3D; the distance was greater
in males than females but was statistically insignificant in genders. The MS volume
showed a significant difference in genders with p < 0.001, larger MS volume was seen in males than females. The mean volume of both
the MS on 2D was 21.87 ± 4.95 and 18.37 ± 3.94 cm3 for males and females, respectively (mean difference of 3.98 cm3 between genders). The mean volume of RMS and LMS on 3D was 21.206 ± 4.7 and 18.956 ± 3.94 cm3 for males and females, respectively, with a mean difference of 2.25 cm3 in genders ([Table 1]).
Table 1
Analysis of different parameters of maxillary sinus in genders
|
Parameters
|
Males (49)
|
Females (41)
|
MD
|
t-Value
|
p-Value
|
|
Mean
|
Mean
|
|
AP right MS (2D)
|
37.15 ± 3.23
|
35.30 ± 2.40
|
1.855
|
3.115
|
0.002
|
|
AP left MS (2D)
|
37.22 ± 3.23
|
35.33 ± 2.41
|
1.889
|
3.167
|
0.002
|
|
AP right MS (3D)
|
37.50 ± 3.13
|
35.71 ± 2.54
|
1.788
|
2.934
|
0.004
|
|
AP left MS (3D)
|
37.58 ± 3.12
|
35.76 ± 2.52
|
1.824
|
3.006
|
0.003
|
|
ML right MS (2D)
|
27.00 ± 4.16
|
25.86 ± 3.34
|
1.145
|
1.419
|
0.159
|
|
ML left MS (2D)
|
27.05 ± 4.15
|
25.91 ± 3.34
|
1.144
|
1.422
|
0.159
|
|
ML right MS (3D)
|
26.10 ± 3.38
|
25.60 ± 2.81
|
0.501
|
0.754
|
0.453
|
|
ML left MS (3D)
|
26.19 ± 3.39
|
25.64 ± 2.80
|
0.549
|
0.826
|
0.411
|
|
SI right MS (2D)
|
34.94 ± 3.15
|
32.66 ± 4.15
|
2.283
|
2.959
|
0.004
|
|
SI left MS (2D)
|
35.00 ± 3.17
|
32.70 ± 4.15
|
2.298
|
2.975
|
0.004
|
|
SI right MS (3D)
|
34.39 ± 3.67
|
33.18 ± 4.07
|
1.215
|
1.487
|
0.141
|
|
SI left MS (3D)
|
34.46 ± 3.67
|
33.22 ± 4.05
|
1.239
|
1.519
|
0.132
|
|
Volume right MS (2D)
|
21.87 ± 4.95
|
18.37 ± 3.49
|
3.498
|
3.655
|
< 0.001
|
|
Volume left MS (2D)
|
21.87 ± 4.95
|
18.37 ± 3.49
|
3.498
|
3.655
|
< 0.001
|
|
Volume right MS (3D)
|
21.20 ± 4.7
|
18.95 ± 2.25
|
3.498
|
3.655
|
< 0.001
|
|
Volume left MS (3D)
|
21.20 ± 4.7
|
18.95 ± 2.25
|
3.498
|
3.655
|
< 0.001
|
|
Distance between right and left MS (2D)
|
29.37 ± 3.78
|
28.21 ± 4.32
|
1.162
|
1.361
|
0.177
|
|
Distance between right and left MS (3D)
|
29.45 ± 3.79
|
28.27 ± 4.31
|
1.180
|
1.379
|
0.171
|
Abbreviations: 2D, two-dimensional; 3D, three-dimensional; AP, anteroposterior; MD,
mean difference; ML, mediolateral; MS, maxillary sinus; SI, superioinferior.
Patients were classified into three different age groups. A total of 28 patients were
included under the age group of 18 to 25 years (male = 14, female = 14). The mean
value for all the dimensions is found to be least in this age group, suggesting that
MS is growing. A total of 35 patients were included in 26 to 40 years of age (male = 19,
female = 16). A partial increase in the mean value of the dimensions is noted in this
age group. The third group included 27 patients of 41 to 55 years (male = 16, female = 11).
Showing a maximum means value resulting from maximum growth of MS in that age compared
with all other age groups. No statistically significant difference was noted in the
parameters of both the MS in different age groups on 2D and 3D images ([Table 2]).
Table 2
Analysis of maxillary sinus in different age groups
|
Parameters
|
Age groups
|
Mean
|
F
|
p
|
|
AP right MS (2D)
|
18–25
26–40
41–55
|
35.68 ± 2.73
36.18 ± 2.87
37.11 ± 3.38
|
|
|
|
1.593
|
0.209
|
|
AP left MS (2D)
|
18–25
26–40
41–55
|
35.72 ± 2.71
36.26 ± 2.91
37.16 ± 3.39
|
|
|
|
1.604
|
0.207
|
|
AP right MS (3D)
|
18–25
26–40
41–55
|
36.09 ± 2.99
36.62 ± 2.75
37.40 ± 3.26
|
|
|
|
1.321
|
0.272
|
|
AP left MS (3D)
|
18–25
26–40
41–55
|
36.14 ± 2.98
36.69 ± 2.73
37.47 ± 3.26
|
|
|
|
1.392
|
0.254
|
|
ML right MS (2D)
|
18–25
26–40
41–55
|
25.91 ± 4.08
26.76 ± 3.80
26.71 ± 3.67
|
|
|
|
0.439
|
0.646
|
|
ML left MS (2D)
|
18–25
26–40
41–55
|
25.96 ± 4.07
26.81 ± 3.80
26.76 ± 3.65
|
|
|
|
0.449
|
0.640
|
|
ML right MS (3D)
|
18–25
26–40
41–55
|
26.07 ± 2.75
26.06 ± 2.90
25.42 ± 3.78
|
|
|
|
0.390
|
0.678
|
|
ML left MS (3D)
|
18–25
26–40
41–55
|
26.12 ± 2.75
26.15 ± 2.90
25.49 ± 3.78
|
|
|
|
0.402
|
0.670
|
|
SI right MS (2D)
|
18–25
26–40
41–55
|
34.03 ± 3.62
34.55 ± 3.79
32.92 ± 3.93
|
|
|
|
1.432
|
0.244
|
|
SI left MS (2D)
|
18–25
26–40
41–55
|
34.07 ± 3.63
34.62 ± 3.79
32.98 ± 3.94
|
|
|
|
1.430
|
0.245
|
|
SI right MS (3D)
|
18–25
26–40
41–55
|
33.88 ± 4.28
33.58 ± 3.87
34.14 ± 3.58
|
|
|
|
0.162
|
0.851
|
|
SI left MS (3D)
|
18–25
26–40
41–55
|
33.90 ± 4.27
33.65 ± 3.86
34.20 ± 3.57
|
|
|
|
0.151
|
0.860
|
|
Volume right MS (2D)
|
18–25
26–40
41–55
|
19.38 ± 4.58
20.79 ± 4.54
20.54 ± 5.44
|
|
|
|
0.716
|
0.492
|
|
Volume left MS (2D)
|
18–25
26–40
41–55
|
19.38 ± 4.58
20.79 ± 4.54
20.54 ± 5.44
|
|
|
|
0.716
|
0.492
|
|
Volume right MS (3D)
|
18–25
26–40
41–55
|
19.87 ± 3.85
19.99 ± 4.15
20.72 ± 5.24
|
|
|
|
0.303
|
0.740
|
|
Volume left MS (3D)
|
18–25
26–40
41–55
|
19.87 ± 3.85
19.99 ± 4.15
20.73 ± 5.24
|
|
|
|
0.306
|
0.737
|
|
Distance between right and left MS (2D)
|
18–25
26–40
41–55
|
28.56 ± 3.75
29.53 ± 4.16
28.25 ± 4.22
|
|
|
|
0.850
|
0.431
|
|
Distance between right and left MS (3D)
|
18–25
26–40
41–55
|
28.61 ± 3.77
29.61 ± 4.17
28.31 ± 4.22
|
|
|
|
0.879
|
0.419
|
Abbreviations: 2D, two-dimensional; 3D, three-dimensional; AP, anteroposterior; ML,
mediolateral; MS, maxillary sinus; SI, superioinferior.
Comparison between RMS and LMS in males and females was done using paired t-test. A significant side difference was noted in AP, ML, and SI diameter on 2D and
3D images (p < 0.005). No significant side differences were seen regarding the MS volume, either
in males or females. The LMS showed a higher value in all dimensions compared with
the right side ([Table 3]).
Table 3
Analysis of parameters in right and left maxillary sinus in males and females
|
Parameters (f)
|
Mean difference (MD)
|
t-Value
|
p-Value
|
|
Males
|
Females
|
Males
|
Females
|
Males
|
Females
|
|
AP right MS (2D)
AP left MS (2D)
|
−0.071 ± 0.093
|
−0.036 ± 0.073
|
−5.345
|
−3.194
|
< 0.001
|
0.003
|
|
AP right MS (3D)
AP left MS (3D)
|
−0.079 ± 0.163
|
−0.043 ± 0.080
|
−3.412
|
−3.480
|
0.001
|
0.001
|
|
ML right MS (2D)
ML left MS (2D)
|
−0.051 ± 0.064
|
−0.051 ± 0.084
|
−5.499
|
−3.903
|
< 0.001
|
0.000
|
|
ML right MS (3D)
ML left MS (3D)
|
−0.091 ± 0.176
|
−0.043 ± 0.083
|
−3.641
|
−3.354
|
0.001
|
0.002
|
|
SI right MS (2D)
SI left MS (2D)
|
−0.063 ± 0.083
|
−0.048 ± 0.095
|
−5.310
|
−3.281
|
< 0.001
|
0.002
|
|
SI right MS (3D)
SI left MS (3D)
|
−0.063 ± 0.069
|
−0.039 ± 0.080
|
−6.344
|
−3.114
|
< 0.001
|
0.003
|
|
Volume right MS (2D)
Volume left MS (2D)
|
–
|
−0.002 ± 0.015
|
–
|
−1.000
|
–
|
0.323
|
Abbreviations: 2D, two-dimensional; 3D, three-dimensional; AP, anteroposterior; ML,
mediolateral; MS, maxillary sinus; SI, superioinferior.
Discussion
In our study, the sizes of all dimensions of MS were found to be greater in males.
However, significant differences were noted in gender only concerning SI, AP diameter,
and volume of MS. The mean AP diameter in the present study for RMS was 37.155 ± 3.23
and 35.3 ± 2.4 mm in males and females, respectively. The mean for LMS was 37.266 ± 3.23 mm
in males and 35.336 ± 2.4 mm in females. In a study performed by Sharma et al, having
102 individuals of 20 to 40 years of age from the Gwalior region of India was found
to have a slight variation in mean AP diameter. It was 34.89 ± 3.2 and 35.03 ± 3.5
in RMS and LMS in males. The females showed a mean of 33.20 ± 2.9 and 33.59 ± 2.9
for the right and left sides. The mean values were comparatively higher in our study,
and this variation might be due to differences in the study population concerning
geographical factors.[10] Another similar study by Urooge and Patil in the Indian population of Karnataka
state, including a total of 100 patients, showed almost similar results like the present
study having a mean AP of RMS as 38.1 ± 0.33 in males and 37.6 ± 0.23 in females and
LMS mean as 37.8 ± 0.33 and 37.1 ± 0.29 in males and females, respectively.[16]
Comparison of the study by Teke et al performed on the Turkish population showed a
considerable variation in mean AP diameter.[17] The mean AP for males was 47.63 ± 6.4 mm for RMS and 47.21 ± 6.5mm for LMS. In females,
it was 45.11 ± 4.6 and 43.64 ± 4.4 for RMS and LMS. A wide variation was noted in
the Indian and Turkish populations, suggesting that Turkish people possess a larger
AP diameter for MS. This variation might be due to racial and ethnic factors.
The study by Uthman et al on the Iraq population showed a minimal difference in AP
diameter.[18] In males, it was 39.3 ± 3.8 and 39.4 ± 3.7 in RMS and LMS. The diameter was 36.9 ± 3.8
and 37 ± 4 in females' RMS and LMS. Indian and Iraq population do not show a massive
difference in the AP diameter.
The SI diameter in the present study was also significantly different in males and
females. The Turkish population showed the largest SI diameter with a mean of 42.58 ± 7.9
and 43.71 ± 7.7 of RMS of males and females. Whereas LMS mean was 37.819 ± 5.6 and
37.60 ± 6.04 in males and females. The present study showed the least SI value with
a mean of 34.94 ± 3.15 and 32.66 ± 4.15 mm of RMS in both males and females. The mean
for LMS was 35 ± 3.17 mm in males and 32.7 ± 4.15 mm in females. The mean height of
MS in Iraq and Turkish population was nearly the same. The studies on the Indian population
showed a mean from 35 to 36 mm in males and 32 to 35 mm in females.
The ML diameter in our study was found to be insignificant in males and females. This
result was similar to the study of the Gwalior region. At the same time, the ML was
significantly different in the Iraq population, with a mean of 24.7 ± 4 and 22.7 ± 3.2
of RMS in males and females, respectively. The LMS showed a mean of 23 ± 4 in females
and 25.6 ± 4.4 in males. The significance in ML diameter of genders might be seen
due to the equal distribution of males and females in that study. The Turkish population
showed a ML value of 27.18 ± 5.4 in males and 26.82 ± 5.5 in females on the right
side and 24.44 ± 3.6 and 24.27 ± 3.9 on the left side in males and females, respectively.
The mean value of the Turkish population was almost similar to the present study.
The volume of MS was also significant in genders. The mean volume for both MS was
21.87 ± 4.71 cm3 in males and 18.37 ± 3.94 cm3 in females. In the study at the Gwalior region, the mean volume on both sides was
16.147 ± 5.99 cm3 in males and 13.92 ± 4.299 cm3 in females. In the study of Karakas and Kavakli on 91 Turkish population of 5 to
55years of age, the mean volume was comparatively less than the present study. The
MS volume in males was 14.74 ± 5.79 cm3 in RMS and 14.55 ± 4.72 cm3 in LMS. In comparison, females had a mean of 14.29 ± 3.42 cm3 on the RMS and 13.78 ± 3.41 cm3 on LMS.[19] The vast difference of volume in both studies might be due to differences in patients'
age groups since they included patients from 5 years, which suggests that MS is in
its growing period, which might lead to a decrease in the mean volume.
Comparison with other studies showed that MS could be used for gender determination,
and it also varies according to geographical and ethnic factors. The AP, SI diameter,
and volume of MS were found to be the standard discriminative parameter for gender
determination. The mean values of all parameters were higher in males compared with
females. This gender-related difference may be due to energetic intake, nutrition,
body composition, and genetics.
Our study also performed age estimation using MS dimensions and volume. Patients were
categorized into three different age groups. In a prospective study performed by Abed-Allah
and Mahdi on 110 cadavers, data was categorized into four age groups from 20 to 29,
30 to 39, 40 to 49, and 50 to 59 years.[20] Group 1 (20–29 years) showed a smaller mean value than other age groups. Similarly,
in the present study the lowest value was seen in the age group of 18 to 25 years,
suggestive of MS in its growing stage during that period. Group 2 (30–39 years) showed
growth in the width and length of MS, whereas the age group of 40 to 49 years showed
a partial increase in length and width, indicating the maximum height of MS in the
comparative study. The last age group in both studies showed a maximum mean value.
There was no significant difference noted in both the studies concerning age. It only
showed the growth of the MS in each decade of life. A slight variation was noted in
both studies for mean values, and the mean was larger in the present study. This difference
might be due to the study sample, since the comparative study included a cadaver.
There might be variation in MS dimensions as the skull ages or dries up due to the
resorption of the maxilla following the loss of dentition.
In addition, a comparison between both the MS showed a significant side difference
for AP, ML, and SI diameter of MS (p < 0.005). No significant differences were seen in the MS volume in males and females.
The LMS showed a higher value for all dimensions. A study of Najem et al on 82 CBCT
images showed no bilateral significant difference for MS length, width, and height
in males and females.[11] In a study by Uthman et al, there was no significant side difference for the length
of MS.[18] The significant difference was seen in mean width and height of LMS and RMS only
in males, and the side difference was insignificant in females.
The distance between RMS and LMS in the present study was insignificant in genders
and age groups. A reliability test was also performed to check the consistency of
the 2D and 3D measurements.
The intraclass coefficient (ICC) value of 0.5 to 0.7 was considered moderately reliable,
values 0.75 to 0.9 indicated good reliability, and values greater than 0.9 were considered
excellent consistency. The comparison between the AP and ML diameters in 2D and 3D
showed moderate reliability with an ICC value of nearly 0.6 to 0.7. The maximum reliability
in 2D and 3D measurements was seen with respect to volume and distance between the
MS with an ICC value of 1.0. In contrast, SI 2D and 3D measurements showed good reliability
between the two measurements.
Thus, the measurement of MS dimensions and volume using CT can be used in forensic
anthropology and other methods for gender determination and to know the growth of
MS in different age groups. It can also be helpful to study racial and geographical
differences. The variation in the results of MS dimensions and volume in our study
compared with other studies might be due to sample size. There was no equal distribution
of males and females in our study. We did not include any patient below 18 years and
above 55 years and a combination of other factors like patient's size, body stature,
physic of individuals, genetic, and environmental factors.
Conclusion
The MS dimensions and volume comparison showed a significant difference in both males
and females. The mean values are higher in males than females. The age group 3 (41–55
years) was found to have the highest mean value compared with other age groups. There
is a significant difference noted in both RMS and LMS dimensions in males and females,
with LMS having a larger value. When comparing 2D and 3D measurements, there is a
consistency maintained in both the measurements. Thus, the measurements of MS dimensions
and volume using 2D or 3D CT images may be a helpful tool for gender determination
and to know the growth of MS dimensions in different age groups.
