New Dimension Of Dentistry, Forensic Odontology; A Boon To Society

Forensic odontology is new dimension of dental sciences which is dealing with proper handling, examination, and evaluation of dental evidence, which are presented for the shake of justice. There are various evidences that could be derived with the help of forensic odontology. We can identify age of person, identification of person, identification of sex of the cases and identify the person to whom the teeth and their mark may belong. Since the dental records may help to identify many information regarding the case which authority are willing to know it require some special knowledge and understanding regarding searching of evidences.

Keiser-Neilson defined forensic dentistry as “that branch of forensic dentistry that in the interest of justice deals with the proper handling and examination of dental evidence and the proper evaluation and presentation of dental findings”.

History of Forensic Odontology

The use of teeth for identification goes back to Roman times

In the first century a.d., the Roman Emperor Claudius had his mistress, Lollia Paulina, beheaded and then demanded to examine the teeth on the body to ensure the right woman had been put to death. He knew she had a discolored front tooth.

The first forensic dentist in the United States was Paul Revere who was known for the identification of fallen revolutionary soldiers. Dr. Joseph Warren, who suffered a severe head trauma during the war, was identified by the small denture that Paul Revere had fabricated for him. Through this identification, it was made possible for Dr. Warren to be buried with full military honors.

Nepal has a long history of aircraft disasters.  There have been more than sixty air crashes over the years 1956 to 2014 and yet no odontologist was involved in the process of DVI.  The year 2012 marks the date in the history   of forensic dentistry in Nepal. As in the year 2012, the first post-mortem dental examination was conducted for Disaster Victim identification (DVI) in Nepal. The attempt was quite commendable as the victims were completely charred and visually unidentifiable with the first timers working on it. The two consultants without DVI background took the initiative to perform the dental charting. Then the dental charts were compared to ante mortem findings to identify the victims. This air crash also has another important addition to the history of identification in Nepal as the co-pilot was the first Nepali to be identified on dental findings. The total of 16 out of 19 victims was identified on dental findings collaborated with other secondary identifiers and the remaining on medical grounds (Dahal et al., 2014). Similarly, post-mortem dental examination had a significant contribution in identification during Nepal airlines crash (2014), mountain air helicopter crash (2015), Nepal earthquake (2015) and Avalanche following earthquake (2015). Other than DVI the Kathmandu autopsy center, Maharajgunj is involved with various other aspects of forensic dentistry on day to day practice such as identification, age estimation, bite mark analysis and research. The services provided by the center are quite commendable due to its unmatchable contribution to judicial system.

The aircraft departed from Pokhara Airport in central Nepal with fifteen passengers and three crew members on board and was scheduled to arrive at Jumla Airport in the northwest of the country at 13:45 Nepal Standard Time (8:00 UTC).Thirty minutes into the flight, the 19-seat Twin Otter was attempting to divert to Bhairahawa Airport because of the weather conditions, resulting in radio contact being lost. The last radio communication with the aircraft crew was at 13:13, when the crew reported their approximate position to Bhairahawa Tower, in Khidim. The aircraft eventually crashed in the jungle of Masine Lek, which is located in Dhikura.

Identification of victims in a disaster is a challenging process and requires use of both primary and secondary identifiers. Development of teeth is one of the routinely used methods of age estimation and helps in establishing deceased biological profile. Two children who lost their lives in 2014 in Nepal .Airlines crash, were looked for the dental developmental status. One of the children had primary dentition, while the other had mixed dentition. This helped us in estimating age of these individuals reconciled with the chronological age provided by the relatives. This led to the identification of both the children, thus, emphasizing teeth as important means of identification in any disaster

SCOPE OF FORENSIC DENTISTRY

• Identifying unknown human remains through dental records, craniofacial bones, serology and DNA comparisons.
• Age estimation
• Recognition and analysis of bite marks found on victims.
• Determining the gender.
• Recognition of signs and symptoms of human abuse.
• Presenting dental evidence as an expert witness.

IDENTIFICATION

ORAL AUTOPSY

CRANIOFACIAL BONES

DENTAL RECORDS

SEROLOGY AND GENETIC (DNA) COMPARISION

ORAL AUTOPSY

• It involves examination of deceased, usually with dissection to expose the organ,  to determine the cause of death.

• Thorough examination of soft tissue injuries, fractures and presence of foreign bodies undertaken and samples of hard and soft tissues may be obtained for further investigation.

Dental record

1. Past record of dental history and physical examination of dentition and supportive oral and paraoral structure.
2. Dental treatment records
3. Result of clinical laboratory test
4. Study cast

PALATAL RUGAE IN IDENTIFICATION

Palatal rugae can be used in identification especially in edentulous patient

CLASSIFICATION OF PALATAL RUGAE

• Given by Lysell
• Primary rugae(>5mm)
• Secondary rugae(3-5mm)
• Fragmentary rugae(2<3mm)

ANALYSIS OF RUGAE PATTERN

1. Manual tracing of rugae patterns
2. computer software programs( RUG FP-IP Match)
3. Digital images
4. Ante and post-mortem comparison of the palatal rugae

Cheiloscopy

Is a forensic investigation technique that deals with identification of humans based on lips traces. The aim is to establish the uniqueness of lip prints which aids in personal identification.

Craniofacial bone

SEX DETERMINATION

Gender can be determined based on data from

-craniofacial morphology and dimension

-sex differences in tooth dimension

-DNA analysis

Amelogenin (AMEL) one of major matrix protein secreted by ameloblast of enamel.The AMEL gene, coding for a highly conserved protein, is located on X and Y chromosomes in human.Thus, two identical AMEL gene (XX) in female but non-identical(XY) in male.

SEROLOGY AND GENETIC (DNA) COMPARISION

Every individual is unique by virtue of his/her chromosomal DNA.The hard and soft tissues of the oral cavity and saliva are often good sources of DNA material.Before 1986, comparison of antigenic markers found on red blood cells and in body fluids among human was traditionally used as a mean of exculpatory evidence.

AGE ESTIMATION

• The age of an individual can be determined from
• Teeth
• Ossification of bones

AGE ESTIMATION IN CHILDREN AND ADOLESCENT

METHODS

1. Tooth calcification and eruption
2. Demirjian’s method
3. Value of third molars

DEMIRJIAN’S METHOD

Valuable indicator of age in the age group of 16-23 years.When all 4 third molars have completely calcified, the chances of individual being 18 yrs old is 96.3% and 95.1% for males and females respectively.When only one  or two third molars present, the lower third molars are best predictor of whether an individual is 18 years old.

AGE ESTIMATION IN ADULTS

• METHODS
• Gustafson’s method
• Boyde’s method
• Amino acid recemization
• Growth in individual bone

GUSTAFSON’S METHOD

1. ATTRITION: Due to wear and tear from mastication, occlusal (upper) surface of teeth is gradually destroyed, first involving the enamel, then dentin, and at last pulp is exposed in old age.
2. PERIODONTITIS: Regression of gums and periodontal tissue surrounding the teeth takes place in advancing age, gradually exposing the neck and adjacent part of roots, due to which teeth become loose and fall out.
3. SECONDARY DENTIN: It is first deposited at pulp chamber and gradually extends downward to the apex, and may completely fill the pulp cavity decreasing the size of cavity
4. SECONDARY CEMENTUM: is slowly and contiunously deposited throughout life, and forms incremental lines. Incremental lines appears as cross-striations on enamel of teeth due to cementum apposition and are thought to represent daily increments of growth.
5.  ROOT RESORPTION: It involves both cementum and dentin which show characteristically sharp grooves. Absorption of root first start at apex and extends upward. It usually occurs in late age
6. TRANSPARENCY OF ROOT: It is not seen until 30 years of age. The canals in the dentin are first wide. With age they are filled by mineral, so that they become translucent gradually and the dentin become transparent due to rarefaction.

BOYDE’S METHOD

The age of an individual can be calculated in terms of days by counting the number of lines from neonatal line onwards.

AMINO ACID RECEMIZATION

Aspartic acid is an amino acid that has rapid rate of recemisation i.e it gets spontaneously converted from one type(L-aspartic acid) to another (D-aspartic acid) with increase in age.Constant change in ratio of L and D aspartic acid at different ages and this ratio may be used for age estimation.Rcemisation rate of aspartic acid is high in root dentin.Age estimates within plus or minus 3years of actual age.

GROWTH IN INDIVIDUAL BONE

BITE MARK

In July of 1979, Theodore “Ted” Bundy was convicted of murder. This may have been the most widely publicized case that involved bite mark evidence. The exhaustive and specific nature of bite registries is to thank, at least in part, for Bundy’s incarceration. Ted Bundy was one of the most notorious serial killers in United States History. He could have been responsible for the deaths of as many as 36 young women from Florida to the state of Washington.

Human bite mark is usually semicircular or crescentic caused by front teeth with a gap at either side due to separation of upper and lower jaw. Bite mark may be abrasions, contusions or laceration or a combination of any two or three Injuries caused by human bites are routinely related to either aggressive or sexual behavior. Sexual bite marks are seen as petechiae producing redness. Bite marks can also be obtained from foodstuffs, such as cheese, fruit, bread, butter, sandwich etc. Specific teeth representative pattern that are recognizable:

Incisor- rectangular marks

    Cuspids- point or triangular pattern

     Maxillary bicuspid- Figure 8

RECORDING AND REPRODUCING METHOD OF BITE MARKS

1. PHOTOGRAPHIC METHOD
2. CASTS
3. DIGITAL IMAGING OF BITE MARKS

HUMAN ABUSE

Dental professionals are likely to encounter more victims of physical, neglective, sexual and psychological abuse as the scopes of problem associated with violent human behavior become more recognised and openly discussed.

CHILD ABUSE

It is the non accidental, physical, mental, emotional or sexual trauma, exploitation or neglect endured by a child younger than 18 years of age while under the care of a responsible person such as a parent, sibling, babysitter, teacher or other person acting as in loco parentis.

SIGN AND SYMPTOMS:

• Laceration of lingual and labial frenum, which result from a blow to a lip or forceful feeding
• Repeated fracture or avulsion of teeth
• Zygomatic arch and nasal fracture
• Bilateral contusion of lip commissures from the placement of gag.
• Bilateral periorbital ecchymosis (raccoon mask)
• Mastoid ecchymosis (Battle sign)  indicating fracture of middle cranial fossa and related traumatic brain injuries.
• Traumatic alopecia secondary to grabbing the head hair of victim while throwing them

PATTERN INJURIES

• Semi-circular or cresentic shape- Bite mark
• Parallel linear patterns- injuries made by a hanger, belt or ruler
• Multiple parallel lines- open handed slap
• Multiple circular, punched out or ulcerated areas- Burning with a cigarette
• Loop patterns- electrical cord, rope and wires.

It is important for a dental professional to recognize signs and symptoms of this and understand the obligation to report and eventually know the mechanism for reporting the recognisation.

DENTISTS AS EXPERT WITNESS

A Witness is a person who gives evidence regarding facts.Expert witness is a person who has been trained or is skilled or has knowledge, experience or education in technical or scientific subjects, and capable of drawing opinions and conclusions from the facts observed by himself, or noticed by others, e.g. doctors, firearm expert, fingerprint expert, handwriting expert, etc.Dental experts assist attorneys and, ultimately, the triers of fact(judges and juries) in understanding the scope and complexities of dental science and practice in relation to question of law. As experts, dentist may be required to testify in civil ligation cases that involve the following situations:

1. Malpractice based on negligence
2. Personal injury
3. Dental fraud
4. Identification of multiple fatality incident victims

Reference:

1. Shafer’s text book of oral pathology
2. Oral and maxillofacial pathology, Neville
3. The essential of forensic medicine and toxicology, Dr.K.S Narayan Reddy