• 1895 – Discovery of X- rays by Wilhelm Conrad Roentgen. • 1896 – Prof. Arthur Schuster used X- rays to demonstrate the presence of lead bullets inside the head of a victim [5]. • In October 1898 issue of the American X-ray Journal, Dr. Fovau d’Courmelles wrote, “Knowing the existence of a fracture in a person who has been burned or mutilated beyond recognition, we can hope to identify him by the x-ray [6].
• In 1921 Schuller compared the radiological images of the frontal sinuses with plates formerly taken [7]. • In 1927 Culbert and Law described the complete radiological identification of the skull by using pneumatic cells of the sinuses [7]. Happonen RP et al. (1991) recommended the use of Orthopantomography in identification which enables visualization of the jaws and related structures as a single radiograph. In the same year Haerting A et al. stated that panoramic dental radiography is the only regularly updated and “ truly reliable identification card” for comparison radiography.
Radiology is also applied in the identification of celebrities like Theodore Roosevelt, Adolph Hitler. Till now, forensic radiology depended almost exclusively on the x-ray and the images captured on the radiograph. The newer modalities, such as computed tomography (CT), cone beam computed tomography (CBCT) and magnetic resonance imaging (MRI) are only gradually being added to the forensic arsenal. Dental identification: When a body of a person is available in burned, decomposed state, any dental remains of the person, such as restorations, teeth present, any missing teeth, prosthesis plays a major role in identifying the dead.
Teeth (maxi. 1000oc) and dental restorations (acryclic 540 oc, gold and amalgam 870 oc, porcelain 1100 oc) are resistant to destruction by fire and therefore useful in identification. Dental identification is based on comparison and exclusion of the radiographs exposed prior to death to those exposed after death. Identification requires a list of the possible persons involved so that appropriate antemortem records can be located. The availability and accuracy of these records determine the success of identification [3], [8]. Regardless of the method used to identify a person, the results of the comparison of antemortem and postmortem data lead to 1 of these 4 situations. Given by American Board of Forensic Odontology (1986) [9]:
1. Positive identification: Comparable items are sufficiently distinct in the antemortem and postmortem databases; no major differences are observed. 2. Possible identification: Commonalities exist among the comparable items in the antemortem and postmortem databases, but enough information is missing from either source to prevent the establishment of a positive identification. 3. Insufficient identification evidence: Insufficient supportive evidence is available for comparison and definitive identification, but the suspected identity of the decedent cannot be ruled out. The identification is then deemed inconclusive. 4. Exclusion: Unexplainable discrepancies exist among comparable items in the antemortem and postmortem databases.
Anatomical identification: Sinus radiography has been used for identification of remains and determination of sex and race. Schuller [10] proposed a classification of frontal sinus taken in the forehead-nose position. He proposed seven characteristics of radiographs • Septum and its deviation • Upper border • Partial septum • Ethmoidal and supra-orbital extensions • Height from planum • Total breadth and • Position of sinus mid-line. Some typical features of frontal sinus morphology are its high variable nature even in genetically identical twins which was proven by Christensen [11], stable structure in adult period, resilient structure having strong bony walls, protects from damage and decomposition [12].
It has high fracture resistance a minimum of 800-1600 foot pounds is required to fracture the frontal sinus. It is helpful in identifying the persons of high impact accidents or gunshot wounds [13]. Cox et al reported in 2009 that superimposition of an antemortem radiograph of the suspected victim’s frontal sinuses over a postmortem radiograph has helped to provide correct identification in 100% of cases [11].
Dental profiling: It is a way to recreate the deceased persons profile prior to death based on clinical and radiological data available. Dental radiology helps in assessing the angulation of anterior teeth that lost after post mortem, and also examination of sockets aid in number and alignment of teeth [14]. Ante-mortem and post mortem radiographic comparison also helps in dental profiling. They allow the observation of anatomical characteristics such as crown shape and size, pulp anatomy, positioning and shape of the alveolar bone crest, in addition to various dental treatments.
Unusual dental anatomy like mandibular premolars which show high variations in pattern and number of grooves and cusps helps in comparison [15]. Radiovisiography allows the spatial resolution of the images and helps in precise analysis of the structures on ante- and post-mortem images, also reduces the number of new exposures, also record keeping and comparison of these images was easy [15]. An ante-mortem CT image provides information which can be utilized in the construction of a post-mortem facsimile image, considering that craniometric points can be precisely located and measurements can be accurately performed [16].
Medico-Legal Cases: Forensic radiology plays a crucial role in medicolegal cases where it helps in identifying the suspect and also helps to evaluate injuries sustained by the deceased or the factors that resulted in death. Radiological evaluation helps in determination of whether the death was accidental or intentional. The arrangement and direction of skull fractures can indicate the point of impact and the direction of impact. Strangulation is indicated by fractures of the hyoid bone or thyroid cornua.
Metabolic abnormalities, infections and dietary deficiencies, bleeding disorders may leave signs on the skeleton that can be appreciated radiographically. Radiographs may provide evidence of bullets or foreign bodies in the soft tissues following fire arm incidents and explosions. Computed Tomography and Cone beam Computed Tomography (CBCT) can be used in the assessing the degree of wound in cases skull injury [17], [18]. Racial& Gender Determination: Forensic dentists along with forensic anthropologists analyzed the calcified structures of body like bones and teeth, this aid them in determining the race and gender of the deceased persons [19, 20].
Important features in identifying the race and gender are tabulated in tables 1 & tables 2 respectively. Cranio-facial re-construction: Cranio-Facial Reconstruction (CFR) is of frequent use in the science of forensic dentistry, medicine, anthropology and anatomy. Most agencies consider reconstructive identification only when there is no putative identification or ante mortem records available. CFR is widely used in the identification of an unknown individual.
The progress in computer science and computer software programs in medical imaging techniques allows the superimposition of known and unknown skull radiographs As clinical use of cross-sectional imaging methods such as CT and MR has increased, many forensic dentists also have begun to evaluate these technologies as potential tools in cranio-facial reconstruction. The use of CT has evolved into the “virtual autopsy” (or “virtopsy”) concept. This involves a complete forensic investigation using CT and MR imaging combined with 3-D reconstruction and postprocessing. The images are taken before the conventional autopsy begins. New multidetector computed tomography (MDCT) scanners increase volume
