Keywords
age estimation - cone-beam computed tomography - pulp cavity size - secondary dentin
- radiation
Introduction
Age estimation is an integral part of every identification process, especially in
those conditions where the information related to the deceased is unavailable.[1] It is used in everyday casework such as missing people, suspected culprits, terrorists,
refugees with disputed birth records, and in cases of casualties resulting from natural
catastrophes such as Typhoon Nina.[2] Bermudez, Nicolas, and Townsend et al stated that tooth dimensions are influenced
by different factors such as genes, nutrition, hormones, and climate. Hence, a new
method using more straightforward and advanced tools must be developed for age estimation.[3]
Teeth, as compared with other parts of the body, are far less affected by external
factors.[4]
[5] This makes teeth valuable indicators for the estimation of age.[1] Burke and Sammarawickrama stated that dental pulp responds to different aspects.
These factors slowly and gradually, with age, cause the formation of secondary dentin
and decrease the size of the pulp cavity.[6] Kvaal et al developed a standard method for age estimation by measuring pulp cavity
size using two-dimensional (2D) radiographs[7]
A study by Ge et al mentioned that the first molar pulp chamber volume is a convenient
indicator for the human age assessment.[8] A survey by Gulsahi et al notes that maxillary central incisors show the strongest
association between chronological age and pulp volume and tooth volume ratio.[4] Teeth can be categorized into anterior, posterior, upper, and lower quadrants. Therefore,
considering only one kind of tooth will always give us limited information.[9] Secondary dentin deposition can be evaluated using 2D radiographic methods because
it is a noninvasive procedure for age estimation. The main disadvantage of these radiographs
is that they do not show proper three-dimensional (3D) morphological changes in the
pulp cavity and have restricted visualization of dental structures.[10]
Cone-beam computed tomography (CBCT) is a newly developed device that enables 3D visualization
of the teeth. It is a straightforward method that provides accurate measurement of
tooth size and reduces the working time compared with other techniques.[11] The primary aim of this study was to determine the relationship between age and
pulp cavity size and to determine which type of tooth should be considered for age
estimation. Data collected can be used for forensic purposes and in endodontic procedures.
Materials and Methods
Patients aged between 18 and 55 years visiting the Department of Radiology in our
institution who were prescribed a CBCT examination as part of their routine examination
and treatment regimen were enrolled in the study; thus, there was no unnecessary radiation
exposure to the patients. The entire methodology of the study was explained to them,
and their compliance to participate in the survey was ensured. They were assured of
maintaining the confidentiality of their personal data. The date of birth of individuals
was confirmed through a national identity card. All subjects were required to have
fully developed maxillary central incisor and mandibular first molar. Due to the bilateral
symmetry of tooth anatomy, right or left teeth were selected randomly. The subjects
went through clinical and radiographic examinations.
All the images were taken with a Scanora. It consists of a cone-beam-shaped X-ray
source with a rotation of 180 to 360 degrees and a flat panel image detector with
a pixel size of 0.5mm and with field of view size of 75 × 100 that are attached to
a revolving stand. The exposure condition consisted of pulsed exposure at 90 kV, variable
current at 12.5 mA, and a total scan time of 4.9 seconds. When the X-ray source and
detector start revolving around the individual, it produces numerous sequential images
in a single rotation around the concerned area. The images were exported in the DICOM
format using a software program (version 2.21), and the on-demand 3D software was
used to carry out calculations. First, the image of each tooth was cropped in coronal
and sagittal dimensions using the above-mentioned software program. All structures,
including the cortical bone, lamina dura, and the adjacent tooth, were removed in
the next stage except for the concerned tooth. Finally, the object was reconstructed,
and measurements were performed in millimeters using the software program by one examiner.
Pearson correlation coefficient (r) was used to calculate the relationship between chronological age and pulp cavity
size. The linear regression model (R2) was used in which the pulp cavity size was
considered the independent variable, and chronological age was considered the dependent
variable to determine the formula for chronological age estimation. All statistical
analyses were performed using SPSS 22. Statistical significance was set at p-value less than 0.05.
Results
A total of 200 patients were included in the study. The mean (standard deviation)
age was 35.3 (10.6) years. Among total samples, 106 (53%) were males, while 94 (47%)
were females.
No significant difference was present between the right and left sides in both maxillary
central incisor and mandibular first molar pulp cavity size of the tooth ([Table 1]).
Table 1
Agreement between right and left side in both maxillary central incisor and mandibular
first molar pulp cavity size of the tooth
|
Symmetric measures
|
|
Side
|
Value
|
Asymp. std. error
|
Approx. Tb
|
Approx. sig.
|
|
Right central incisor
|
Interval by interval
|
Pearson's R
|
−1.000
|
0.000
|
−394.621
|
0.000c
|
|
Ordinal by ordinal
|
Spearman correlation
|
−1.000
|
0.000
|
−312.330
|
0.000c
|
|
No of valid cases
|
52
|
|
|
|
|
|
Left central incisor
|
Interval by interval
|
Pearson's R
|
−1.000
|
0.000
|
−352.248
|
0.000c
|
|
Ordinal by ordinal
|
Spearman correlation
|
−1.000
|
0.000
|
−291.040
|
0.000c
|
|
No of calid cases
|
48
|
|
|
|
|
|
Right molar
|
Interval by interval
|
Pearson's R
|
−1.000
|
0.000
|
−331.104
|
0.000c
|
|
Ordinal by ordinal
|
Spearman correlation
|
−1.000
|
0.000
|
−288.534
|
0.000c
|
|
No of valid cases
|
50
|
|
|
|
|
|
Left molar
|
Interval by interval
|
Pearson's R
|
−1.000
|
0.000
|
−342.132
|
0.000c
|
|
Ordinal by ordinal
|
Spearman correlation
|
−1.000
|
0.000
|
−288.534
|
0.000c
|
|
No of valid cases
|
50
|
|
|
|
|
|
Total
|
Interval by interval
|
Pearson's R
|
−0.216
|
0.066
|
−3.105
|
0.002c
|
|
Ordinal by ordinal
|
Spearman correlation
|
−0.477
|
0.062
|
−7.629
|
0.000c
|
|
No of valid cases
|
200
|
|
|
|
|
a. Not assuming the null hypothesis.
b. Using the asymptotic standard error assuming the null hypothesis.
c. Based on normal approximation.
The relationship between chronological age and pulp cavity size was statistically
significant. Maxillary central incisor and mandibular first molar showed a strong
relationship between chronological age and pulp cavity size. A significant relationship
between age and pulp cavity size of the tooth was observed ([Table 2]).
Table 2
Maxillary central incisor and mandibular first molar present a statistically significant
relationship between age and pulp cavity size of the tooth
|
Symmetric measures
|
|
Tooth side
|
Value
|
Asymp. std. error
|
Approx. Tb
|
Approx. sig.
|
|
Incisor
|
Interval by interval
|
Pearson's R
|
−1.000
|
0.000
|
−446.626
|
0.000c
|
|
Ordinal by ordinal
|
Spearman correlation
|
−1.000
|
0.000
|
−435.635
|
0.000c
|
|
No of valid vases
|
100
|
|
|
|
|
|
Molars
|
Interval by interval
|
Pearson's R
|
−1.000
|
0.000
|
−404.290
|
0.000c
|
|
Ordinal by ordinal
|
Spearman correlation
|
−1.000
|
0.000
|
−435.635
|
0.000c
|
|
No of valid cases
|
100
|
|
|
|
|
|
Total
|
Interval by interval
|
Pearson's R
|
−0.216
|
0.066
|
−3.105
|
0.002c
|
|
Ordinal by ordinal
|
Spearman correlation
|
−0.477
|
0.062
|
−7.629
|
0.000c
|
|
No of valid cases
|
200
|
|
|
|
|
a. Not assuming the null hypothesis.
b. Using the asymptotic standard error assuming the null hypothesis.
c. Based on normal approximation.
Discussion
The results of this study showed that maxillary central incisor showed strongest relationship
between pulp cavity size and age. The similar results were observed in the previous
studies.[4]
[10]
[12] However, the method used for their study differ from the present one because they
have considered measuring pulp cavity to tooth volume ratio for age estimation, while
in this study changes taking place in the pulp cavity size due to secondary dentin
deposition with age were determined using CBCT.[11]
The main purpose of choosing pulp cavity is because changes happening in the pulp
cavity size is directly related to the age. On the other hand, the tooth volume can
be increased or decreased by different factors. Pulp cavity size measurement is easy
and more accurate as compared with measurement of whole tooth volume.[11]
In the forensic field, age estimation is vital for living and nonliving. It is an
integral part of every identification process, especially in those conditions where
the information related to the deceased is unavailable.[4] The number of methods for age determination is remarkably reduced in adults. In
such a situation, the teeth can be used for age estimation because they are the hardest
structures resistant to external factors.[11]
The deposition of secondary dentin is a slow, continuous process and is not affected
by other external factors; when the individual age increases, the size of the pulp
cavity decreases because of secondary dentin deposition.[4]
[12] The changes in the pulp cavity size with age because of secondary dentin deposition
can be measured by dental radiographs and considered for age estimation.[8]
Panoramic and periapical radiographs describe changes in the pulp cavity size due
to secondary dentin deposition with age. These radiographs are 2D and fail to provide
an accurate measurement. They also do not represent the 3D image of the changes happening
in the pulp cavity.[13] In this study, changes in the pulp cavity size with age were assessed using CBCT.
It is a newly developed device that gives a 3D image of the structure and more accurate
measurement than 2D radiographs.[14]
Numerous studies have considered measuring the pulp cavity-to-tooth volume ratio for
age estimation. In contrast, in this study, changes in the pulp cavity size due to
secondary dentin deposition with age were determined using CBCT.[15] The primary purpose of choosing a pulp cavity is because changes in the pulp cavity
size are directly related to age. On the other hand, the tooth volume can be increased
or decreased by different factors. Pulp cavity size measurement is easier and more
accurate than a whole tooth volume measurement.[11]
Ge et al suggested that the first molar should be considered for age estimation. The
results of this study are concurring with the above research findings which showed
that the mandibular first molar shows a statistically significant relationship between
age and pulp cavity size.[16] Also, our findings are similar to a previous study that revealed that the maxillary
central incisor strongly correlates with pulp cavity size and age.[17] However, in this study, we estimated individual age by measuring pulp cavity size
of maxillary central incisor and mandibular first molar using CBCT. Both of them showed
a significant relationship with age.
This study has some noteworthy limitation such as conducted by one examiner, limited
area, and small sample size.
Conclusions
-
The relationship between age and pulp cavity size of maxillary central incisor and
mandibular first molar is statistically significant as a result both can be used for
age estimation.
-
Relationship between right and left side was strong as a result one can choose either
right or left maxillary central incisor and mandibular first molar for age estimation.
Further studies must be conducted by more than one examiner, advanced techniques must
be used, and large sample size selection, multiple types of teeth from different population,
and both genders must be involved to improve the accuracy of the study
