Article Type : Review Article
Authors : Tomar N and Patil B
Keywords : CBCT; CT; Forensic odontology
Forensic odontology is “that branch of forensic medicine which in the interest of justice deals with the proper handling and examination of dental evidence and with the proper evaluation and presentation of the dental findings.” Forensics refers to cases that can be used in a judicial setting which are accepted by the law and helps to separate truth from untruth [1]. Identification based on teeth has significantly contributed to identification of dead individuals from history to present, the first case being accepted by the law in the year 1849 [2]. Forensics deals with the identification of the dead using numerous techniques. Multiple methods like uroscopy, bite marks, palatal rugae, photographs, lip prints, etc. are used for identifying the individuals but they depend on soft tissue and it is difficult to get intact soft tissues for identification in forensic scenario. In the human remains, teeth, facial bones are the hardest structures, which are unaffected by the decompositional/ destruction forces and under extreme forces or any temperature variations. Teeth radiography is simple and easy method and becomes an invaluable tool in forensic sciences.
Radiographic identification of teeth and jaws is efficient, easy, simple and records can be obtained in both living and dead person. It has more preference to DNA analysis as it is less expensive. Radiographic identification with specialized radiologic examinations provides and accurate efficient matching of unique features on ante and postmortem radiographs. It also overcomes the radiographic errors, time consuming practices, less accurate images encountered in conventional techniques.
Personal identification, age and gender determination are of paramount importance to the individual and society in case of mass disasters. It is generally seen in the field of forensic odontology that optimum estimates of age and sex can only be achieved through a multifactorial approach; by applying two techniques of assessment to a specific case. There is dental development variation in the individuals of same population and different ethnicity and groups. Thus, calibration of dental age and gender assessment should be done concerned to local population is most accurate to get the desired accurate results.
As such, the following requirements are mandated for the purpose of radiographic assessment for age and sex estimation in forensic context
1. Obtaining appropriate radiographs and specimens from the subject,
2. The obtained material should be like the one used in the selected age prediction method so that direct and valid comparisons can be conducted,
Selection of the appropriate age prediction method is based on one's understanding of the method and its suitability to the subject, besides understanding and compliance with the legal requirements (Ciapparelli; Panchbhai) [3,4]. CBCT can allow the dental examination of dead bodies when mouth opening is impossible and for yields information for screening by investigating unidentified bodies. CBCT has following applications in forensic that is premortem forensic and postmortem forensic premortem forensics include age and sex determination using CBCT and postmortem forensics include frontal sinus use for personal identification, craniofacial reconstruction [5].
The soft tissues are not as accurately visible in CBCT
images as in MRI and ultrasonography (USG).
The resolution of CBCT images is not as high as that of CT
scan the energy of X- rays use in CT scan is of high intensity compared with
CBCT.
The frontal sinuses can provide significant evidence
for forensic identification. The frontal sinus characteristics and its
applicability for criminal investigations have been studied for many years, is
very useful in edentulous individuals. Frontal sinus pattern is unique for
every individual and radiographic assessment aids in personal identification in
forensic applications by using Yoshino classification of frontal sinus [12].
CBCT can provide as a
useful replacement for study of pattern of Frontal sinus with its accuracy.
Some anatomic references for axial and sagittal plane should be identified so
that all sinus boundaries are seen with minimal error margin for morphometric
comparison of ante and postmortem scans. Beani et al. reported a good
success in identification of persons by making 3D models from CBCT scans.
Frontal sinus pattern matching is superior to two-dimensional imaging and thus
provides accurate results [13,14]
CBCT assisted bitemark analysis is nondestructive, accurate and
efficient. CBCT data will have no distortion and 3 D measurement and
orientation is possible. Bitemark analysis can be done even if foodstuff is
left under room temperature for hours [15]. Marques Jet al. found CBCT scans were successful in determining depth of
bite mark in all foodstuffs except pizza. Cone Beam Computed Tomography has the
potential to become an important tool for forensic sciences, namely for the
registration and analysis of bite marks in foodstuffs that may be found in a
crime scene [16].
Sexual dimorphism is an
important aspect in personal identification which helps to narrow down the
identification process. Skull has 95% of accuracy rate for sex determination.
Skull bones are relatively indestructible and denser which are often recovered
intact at crime scene can be applied for sex determination. Studies reporting
anthropometric measurements of structures for sex determination using CBCT are
for following structures 1. Mandibular measurements 2. Foramen magnum 3.
maxillary sinus 4. Frontal sinus 5. mastoid process.
Yang
et al. correlated
the chronological age of an individual and the pulp/tooth volume ratio of teeth
by a custom-made voxel counting software for calculating the ratio pulp tooth
ratio for age determination [17]. Jagannathan et al. calculated pulp tooth ratio
from CBCT scans of 140 individuals for mandibular canine in Indian population
and proposed it to be a useful technique for age estimation [18]. Star et al.evaluated pulp tooth ratio from
CBCT scans of all teeth and found that incisors more accurate in age
determination [19]. Alam et al. evaluated
the tooth size and arch dimension by CBCT scans and found that canines showed
maximum sexual dimorphism [20]. Gamba et
al. studied CBCT images and measured mandibular images by measuring ramus
length, gonion- gnathion length, minimum ramus breadth, gonial angle,
bicondylar breadth, and bigonial breadth for the sexual dimorphism analysis
which was 95% accurate in gender determination [21]. Ilguyet al. reported foramen magnum and mandibular measurements such as
gonial angle and ramus, gonion- gnathion lengths, and bigonial breadth of the
mandible evaluated preexisting CBCT scans to be used for gender determination
in unknown skull remains [22]. Foramen magnum can be used for sexing when other
methods are not applicable was advised by Jaitley Met al., Akay et al also suggested that its sagittal, transverse and
circumference show sexual dimorphism [23,24]. Urooge et al. reported in their study that maxillary sinus CBCT scans can
be used as an aid in forensics for gender determination with overall accuracy
of 71% [25]. Gamba et al. emphasised
combined use of mandibular canal and maxillary sinus for sex determination with
two together with 78.5% accuracy in Dutch population [26]. Pakanahad M et al. supported that height measurement
in maxillary sinus is predictable factor for sex determination from CBCT scans
[27]. Gomes A et al. found that CBCT
measurements of maxillary sinus had 94% precision in Brazilian population for
sex determination [28]. Although above studies reported that CBCT scan software
would accurately and easily measure maxillary sinus dimensions Saccuciet al. reported in their study that
maxillary sinus should not be used for gender determination [29]. Amin et al
reported that mastoid process radiographic study with CBCT correctly identified
gender in 90.6 % cases using discriminant function analysis and inter mastoidal
distance was best determinant for sex in Jornadian population [30]. CBCT and
age estimation studies Pinchi Vet al. reported
CBCT provides easy accurate tooth volume calculation [31]. Rhee et al. used second vertebrae as
predictable marker on CBCT for prediction of bone and forensic age showed good
accuracy. CBCT is the choice to evaluate sphenooccipital synchondrosis for age
estimation around the age of 18 years reported by Sinanoglu et al. CBCT in various age estimation
studies proves to provide a solution which is more accurate, easy to manipulate
and multiple functions can be applied through programs and faster [32].
CBCT
in forensic radiology holds a strong promise through its applications which are
major so possibility of deceased CBCT scans obtaining are high and its accurate
with its high radiographic image quality. CBCT scans of deceased will have high
applications in digital facial reconstruction and bite mark analysis with wide
scope of CBCT software with its simplicity and fast retrieval of results with
high accuracy. CBCT provides a more precise and standardized imaging modality
to conventional radiography for age and gender determination with its high
precision. CBCT is a new age modality and multiple studies which are population
specific should be conducted to provide an evidence scientifically for
application of CBCT in forensic odontology.