There are different classifications given for injuries. The etiological classification categorizes injuries as two kinds: mechanical and thermal. Mechanical injuries are sub-classified into abrasions, contusions, lacerations, stab injury, incised wounds and firearm injuries. Thermal injuries are sub-classified into burns and scalds, frostbite, chemical burns, radial burns and electric burns. Medico-legal classification is based on three grounds: severity, mode of death and moment of death. Injuries based on severity: simple and grievous injuries, based on mode of death: suicidal, homicidal and accidental injuries and based on moment of death: ante-mortem and postmortem.

Incised injuries are made by sharp edged weapons and have clear cut separation of tissues. Length of the injury is greater than the depth. The medico legal importance of incised wounds are:

1.      The nature of weapon can be confirmed to be sharp edged.

2.      Determination of the age of injury was possible.

3.      The direction of application force can be determined from the tail of the wound.

4.      Homicidal incised wounds are frequent.

Abrasion injuries are blunt force injuries and results in the destruction of superficial layers of epidermis. A pure abrasion rarely bleeds and it is a two dimensional injury. The medico legal significances are as follows:

1.      Age of the injury can be determined.

2.      Pattern abrasion can help us identify the type of weapon used.

3.      Abrasions on the face of suspect can indicate struggle.

4.      Suicidal abrasions are rare. They are often seen in accidents and homicides.

Lacerations are tearing or splitting of skin, mucous membrane or internal organs. This is caused by blunt force on the body tissue or skin. Lacerations are three-dimensional and the margins are uneven and irregular. Following are the medico legal aspects:

1.      These injuries can indicate the shape of the blunt weapon.

2.      Determining age in uninfected lacerations is quite useful.

3.      Foreign bodies found in the wound site might help us reconstruct the circumstances during the commission of crime.

4.      These wounds are generally seen in accidents and assaults.

5.      Lacerations are generally considered grievous injuries.

Stab wounds are mechanical injuries where the depth is the greatest dimension when compared to the length and breadth. They can be produced by knives, dagger and sword. The medico legal aspects of such wounds are:

1.      Stab wounds are majorly homicidal or suicidal. Accidental wounds are very infrequent.

2.      The depth of the wound shall signify the penetration force.

3.      Age of the injury can be estimated.

4.      Shape of the wound helps to classify the type and class of weapon. For example, the length, width and thickness of the weapon, whether it is single edged or double edged are the characteristics studied.

Burn injuries are those that are produced on the body by the application of dry heat like flame, fire or radiation. Medico-legal aspects of this category of injury are:

1.      Presence of smoke in the respiratory passage of the victim indicates he or she was alive when fire started.

2.      Raised carboxyhaemoglobin in the blood. The percentage often exceeds 10%.

3.      Presence of red line in the region adjacent to the burns.

A contusion is an effusion of the blood into the tissue due to the rupture of vessels, especially capillaries. They are caused as a result of blunt force trauma.

1.      Self-inflicted bruises are rare.

2.      Contusions can be homicidal, suicidal or accidental.

3.      Shape and size of bruise is similar to the nature of the weapon.

4.      Age of the injury can be determined.

Firearm wounds include both the entrance and exit wounds. The wounds vary in shape and size depending on the range of shooting, velocity of projectile and target site. Medico-legal aspects of firearm injuries include:

1.      Suicidal firearm wounds are often indicated by the firearm in the hands of the victim due to cadaveric spasm.

2.      Accidental firearm injuries are rare in occurrence.

3.      Nature of the firearm can be determined. For instance, whether it is smooth bore or rifled.

4.      Homicidal or suicidal injuries are common.

5.      Range and direction of firing can be calculated.

When electric current passes through the body, it causes various effects such as muscular spasms, contact burns or severe charring. These are the effects of electrocution and some of their medico-legal aspects are:

1.      Suicidal electrocution is rare but might occur in mentally unsound people.

2.      Homicidal electrocutions are more frequent. Electrocution via occurs through accidents.

For instance, circuit may pass through any of the limbs to the head and lead to paralysis of respiratory centre.

3.      The site of entrance may be diagnosed histochemically by seeing deposition of metal particles on the skin.

4.      An arm to arm circuit or left arm to either leg involves heart. Death occurs due to ventricular fibrillation or cardiac arrest without fibrillation.

Simple injury or hurt causes bodily pain, disease or infirmity to any person for a short period and it does not endanger life. On contrary, grievous hurt is caused by certain conditions as mentioned under Section 320 of IPC.

Under Section 320 of IPC, grievous hurt is constituted by the following:

1.      Emasculation

2.      Losing the ability to see by either eye permanently

3.      Losing the power of hearing of either ear permanently

4.      Privation of any member or joint

5.      Destruction or permanent impairment of power of any member or joint

6.      Deformation of head or face permanently

7.      Bone or tooth getting fractured or dislocated

8.      Any hurt which endangers life or which causes severe pain to the individual or he is unable to do his daily activities for 20 days

Emasculation is depriving a male of his masculine vigor.

Permanent loss of sight of either eye not only means lacking the function of a vital organ in the body but also deforming the person. It can be caused by poking eyes or pouring chemicals over it.

Blow on the head or ear or affecting the tympanic membrane or auditory nerves can cause permanent privation of hearing in either ear.

Incapacity of a limb or organ which performs an individual and distinct action is known as privation of any member or joint.

Deprivation of the functions of any of the ability of any limb or joint makes a person a lifelong cripple or physically disabled, thus ruining the normal course of his life.

Disfigure does not mean making an individual incapable physically. It is causing external injuries that have consequences on his or her life. For instance, a scar on the face of an actress can lead to damage to her professional establishment.

Any break or discontinuity in the bone is considered to be a fracture. A bone need not break completely for it to be considered as a fracture. Dislocation means displacement of a tooth or bone from its normal anatomical position.

The injuries which do not fit into any of the aforementioned clauses are included in the eighth clause. An injury may cause serious body pain or might threaten an individual’s survival but does not come under any of the above conditions are included here.

The medico-legal opinion with respect to injuries should contain the whole description and an opinion regarding its legal state. These opinions help the court of law to decide the seriousness of the crime and also in sentence evaluation of the suspect.

References:

·         https://epathshala.nic.in/

·         https://www.researchgate.net/publication/269557204_Medicolegal_Aspects_of_Hurt_Injury_and_Wound

·         https://www.slideshare.net/AkshayDeokar3/injury-forensic-science

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Forensic odontology and orthodontic refers to the study and use of teeth, dentition and tooth marks as evidences to identify the victim, suspect or any other person related with some criminal activity for the purpose of justice. Forensic dentists are either called by the medical examiner or the police offer to assist in the investigation process, helping to identify tooth evidences and marks.

The primary requirement for orthodontic and odontology identification is to have an in-depth knowledge about the anatomy of the oral cavity. Every individual has two dentitions during his or her life: the primary(deciduous)dentition and the permanent dentition. Primary tooth development starts from the fourth month of the fetus in the uterus with tooth eruption beginning from 6 months of age. All twenty primary(milk) teeth erupts by 2 years of age. When the child is in the age group of 6 to 8 years, the adult tooth development begins. The primary teeth are replaced by the permanent dentition. The permanent molar teeth are not preceded by any primary molar tooth and hence it develops without any loss of a primary tooth. Humans have 20 milk teeth and 32 permanent teeth. The last tooth to develop is the wisdom tooth (third molars). They might or might not develop in some people and hence not all humans possess a dentition comprising of 32 teeth in total. The distribution of teeth on maxilla(upper jaw) and mandible(lower jaw) are uniform and equal. However, identification of individuals is possible due to the dental fingerprints each o them possess. Each dental fingerprint is as “unique” and individualistic as fingerprints are. No two teeth of different individuals  or their dentition shall be exactly alike.

Body identification by dental means start with the access to the dentition. Rigor mortis is the stiffening of muscles in the corpse and it often makes it impossible to open the mandible for examination. To break the rigor, a screw is inserted between the first and second premolars and twisted. If due to fire and decomposition reasons, the victim cannot be viewed at the funeral, the jaws can be cut from the mouth and removed. Examination of the jaws outside the body can be conducted.

Age determination by orthodontic is one of most pivotal applications. The development of teeth is uniform and sequential up to the age of 15 years. It allows age estimation within 1 year. As discussed above, development and mineralization of teeth starts from the fourth month (approximately the 14^th week) of intra-uterine life. Due to the metabolic stress induced by the childbirth on tooth-forming cells, a thin band of altered enamel and dentin called the neonatal line is formed. A neonatal line undoubtedly marks the event of birth of an individual. The permanent dentition begins to mineralize at birth and is complete by 14 to 16 years of age. Determination of ages between 15 and 22 years quite heavily depend on the eruption of the third molar or the wisdom tooth. After the age of 22, post-eruptive and degenerative changes are used for age determination. D-aspartic acid allows us to determine age quite precisely and it relies on the time-dependent conversion of L-aspartic acid into D-aspartic acid. Scot suggested that if the root formation is incomplete then the individual is less than 25 years of age.

Tooth structure has also proved efficient in determining the sex of an individual. For most of the teeth, the size and shape for both males and females are quite alike. However, the mandibular cuspid exhibits great sexual dimorphism. A mesiodistal diameter less than 6.7 mm indicates a female whereas a diameter of greater 7 mm indicates a male. The maxillary cuspids are also significant in determining sex. In this case, males have root lengths 3 mm longer than females. Probes of DNA from dental pulp have been used to recognize the sex.

Racial determination by dental means is not a reliable and accurate method. However, a cluster of traits rather than a single trait can be useful in proper diagnosis. Races are divided into three broad categories: Caucasoid, Negroid and Mongoloids. Mongoloids have prominent shovel-shaped maxillary incisors and this trait is present in 85%-99% of their population. The Cusp of Carabelli which is a mesio-lingual accessory cusp found exclusively on the maxillary first permanent molar and its second deciduous molar counterpart is found in 35%-50% of the Caucasoid population. Unlike Mongoloids, Caucasoids lack shovel-shaped maxillary incisors. There are 2 to 3 cusps on mandibular first premolar.

Bite marks are often observed in cases of rape, murder, child abuse and domestic violence. Human bite marks are found on the arms and hands during defensive circumstances. For the proper presentation of bite mark evidence at the court of law, it is necessary to be able to recognize mark pattern, both in animate and inanimate objects. Moreover, it is essential to know what to do after the evidence has been identified as a bite mark. Bite marks on human tissue varies in shape and size and depends on the tissue bitten, biting force and the resistance of the victim to biting. Biting on muscular areas of the body leaves prominent bite marks unlike on fatty tissues. Defensive or aggressive bite marks are less distinct and show more bruising. Bite marks given with consent are prominent and the teeth pattern can be understood well. Hence, they are important evidences to determine the suspect and victim in violent crimes .The time of death can also be estimated using bite marks. In ante mortem bite patterns, diffused bruising is observed. In per mortem bite mark evidences, clear and well-defined bruising pattern results. It is important to note that bite marks can also be analyzed when on inanimate objects like fruits or cheese cubes. They are as promising as those found on a victim’s or suspect’s body.

We have seen bite mark analysis assisting in landmark cases like Nirbhaya rape case in New Delhi which had taken place in 2012. The bite marks on the victim were matched with the cast made from the dentition of the convicts, thus proving them guilty in the court of law. Bite mark analysis has also helped in the conviction of various psychopathic killers, one of whom is Ted Bundy.

In conclusion, I would like to emphasize that cases of genocides and mass disasters have been widely assisted by the help of odontometric evidences. Identification of partially burnt bodies due to bomb blasts, earthquakes and other disasters were made possible through dental remains. However, it is unfortunate that this branch of Forensic Science is yet to develop in our country and techniques in odontology are yet to advance.

References:

1.     1.  deccanchronicle.com

2.     2.  ncbi.nlm.nih.gov

3.      3. An Introduction to Scientific and Investigative Techniques, Third Edition, Stuart.H.James and Jon.J.Nordby

4.      4.Handbook for Forensic Odontology, Dr.Vikram Ahuja

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