The memoirs of your not so average dentist

Lets get on to business then, starting off with question 1, however before we begin, here’s a disclaimer:  

It’s kind of a long post, so..

What is Forensic Dentistry?

Forensic dentistry or Forensic Odontology is the application of dental knowledge to those criminal and civil laws that are enforced by police agencies in a criminal justice system. Forensic dentists are involved in assisting investigative agencies to identify recovered human remains in addition to the identification of whole or fragmented bodies; forensic dentists may also be asked to assist in determining age, race, occupation, previous dental history and socioeconomic status of unidentified human beings. Identification is done by the comparison of ante mortem and post mortem dental records and using the unique features visible on dental radiographs

Forensic dentists are responsible for six main areas of practice:

•         Identification of found human remains

•         Identification in mass fatalities

•         Assessment of bite mark injuries

•         Assessment of cases of abuse (child, spousal, elder)

•         Civil cases involving malpractice

•         Age estimation

An example of forensic dentistry used to solve a crime was in January 1978 in United States, a serial killer, Ted Bundy. One of the earliest known examples of forensic dentistry involved Agrippina, the mother of Roman emperor Nero. In 49 B.C. Agrippina ordered the death of her rival Lollia Paulina, who was in competition with her to be the wife of Emperor Claudius. Agrippina demanded to see Lollia Paulina's head as proof of her death, but she wasn't sure that her rival was dead until she noticed Lollia Paulina's distinctive discoloured front teeth.

How Forensic Dentistry plays a role in identifying burnt victims?

-    Basic identification is not so difficult a task for the most part, however, when the victim is burned beyond recognition, more complex methods must be utilized as a means by which to establish positive identification. These methods include, DNA fingerprinting, forensic odontology, and cranial base evaluation. With the incorporation of these methods, it has made identification of a severely burned body possible.

-    A body that has been only partially burned can be identified through DNA fingerprinting. 

-    When the body is burned to such a degree that all that is left is skeletal remains, forensic odontology becomes the primary means of victim identification in Canada. Dental records serve as more than merely an accumulation of one's cavity history; rather, they become the link between an unidentifiable fire victim and one who can be recognized by tooth imprints. However, in order for forensic odontology to be effective, the victim's remains must be handled with extreme care so that critical identifying information is not further damaged or destroyed. "A systematic, conservative approach prevents the loss of valuable dental information before a thorough picture of the individual's dental remains has been adequately documented." The process that revolves around forensic odontology entails compiling a comprehensive dental charting that provides information via oral structures intra-oral photographs and radiographs as a means by which to piece together the puzzle that represents forensic odontology. "Utilizing methods of access to the oral structures that maintain the integrity of the dentition through each stage of the evaluation of charred remains will prevent the loss of potential dental information..." While forensic odontology has been extremely instrumental in identifying myriad burn victims, it is not a flawless method of classification due to the inaccuracies inherent to such a process. In order for Canada's forensic odontologists to positively identify a burn victim, the individual's records must be recovered; this initial step might seem rather uneventful, however, with the decrease in dentist visits over the past decades, obtaining accurate records is becoming more and more difficult. Additionally, dentists are under no obligation to maintain detailed records of their patients, which serves to create a wide margin for charting errors and mis-identification when molars resemble one another or because there may have been an extraction at one point that allowed for another tooth to take its place. "The use of high-resolution digital scanners are helping to remove the personal judgement element in the old methods of forensic odontology."

Additional - Using Cranial Base method.

-    Still another technique for identifying the remains of a burn victim is through cranial base evaluation. The fundamental basis of this particular method involves measuring for specific size in order to determine the race and sex of skeletalized victims. "Determination of race (ancestry) is an important step in the identification of individuals in forensic cases. Race is most commonly assessed using cranial traits." While this method is highly effective, its major drawback - the potential for skeletal shrinkage - is quite significant as well. If the cranial base shrinks from its normal size, which is a distinct possibility in the event of fire, the task of sexing the victim becomes even more difficult due to the potential misrepresentation of proportion. The recent upsurge in the study of human genome science has an association with burn victim identification, inasmuch as findings have indicated that there exist a certain number of short tandem repeat (STR) loci in Quebec's French Canadian population. These loci, which "represent a rich source of highly polymorphic markers in the human genome," have proven effective in relation to forensic identification and biological correlation of Canadians. Research indicates that the six STR loci "are informative genetic markers for identity testing purposes in the French Canadian Caucasian population of Quebec." That Canada's research with regard to forensic science has progressed forward at such an advancing rate clearly denotes a tendency to set precedence when it comes to the future of burn victim identification. "...Forensics in Canada has been in the international forefront since the inception of the first forensic laboratory in North America, in Montreal in 1914...Canadians have made significant contributions to the international scene and their credit is deserved."

How does forensic dentistry play a role in identifying victims with bite marks?

• The first step in analysing the bite is to identify it as human. Animal teeth are very different from humans' teeth, so they leave very different bite-mark patterns
• DNA may have been left in the saliva of the biter
• Each individual bite mark is measured and recorded
• Photographs are taken due to the changing nature of the bites
• Bruising can appear four hours after a bite and disappear after 36 hours * The dentist may have to wait until the lividity stage, or pooling of the blood, clears and details are visible
• Bite marks on deceased victims are cut out from the skin in the morgue and preserved in a compound called formalin, which contains formaldehyde
• Dentists then make a silicone cast of the bite mark

Forensic dentists use several different terms to describe the type of bite mark: 

• Abrasion - a scrape on the skin
• Artifact - when a piece of the body, such as an ear lobe, is removed through biting
• Avulsion - a bite resulting in the removal of skin
• Contusion - a bruise
• Hemorrhage - a profusely bleeding bite
• Incision - a clean, neat wound
• Laceration - a puncture wound

There are different types of impressions that can be left by the teeth as well

• A clear impression means that there was significant pressure
• An obvious bite signifies medium pressure
• A noticeable impression means that the biter used violent pressure to bite down

A forensic dentist can tell a lot about the teeth of the biter based on the bite mark

• If there's a gap in the bite, the biter is probably missing a tooth
• Crooked teeth leave crooked impressions and chipped teeth leave jagged-looking impressions of varying depth
• Braces and partials also leave distinctive impressions

Once investigators have identified a suspect, they obtain a warrant to take a mold of his or her teeth as well as photos of the mouth in various stages of opening and biting

• They compare transparencies of the mold with those of the bite-mark cast
• Photos of both the bite mark and the suspect's teeth are compared to look for similarities 

 

By now you are probably feeling that

We know its been a long post so far, but fear not, as..

Lets continue,

Forensic Dentistry in Identification of murder victims

Forensic dentistry is specifically used when the murder victim is so extensively disfigured that it becomes impossible for an individual to visually identify the victim.

There are several causes to the disfigurement including:

• Burnt victims
• Those who had deceased for a long period of time prior to discovery
• Those who are found in water

Teeth are a repository for unique features and they survive most trauma and postmortem event that can disrupt other body structure. This is because enamel is the strongest structure in the human body. Teeth aren't as unique to a person as a fingerprint, but dental evidence can be instrumental in establishing a person's identity.

• The size of teeth can give clues to a person's approximate age because of how fast teeth grow -- about four micrometers a day.
• Different ethnic groups also tend to have distinctive dental features, such as incisors with concave backs.
• The patterns left on teeth over time due to the wear and tear of a person's eating habits and lifestyle can also provide convincing evidence about a person's identity.
• The teeth itself is a fantastic source of DNA because of its resistant nature towards environment insults such as incineration, mutilation, and decomposition.

Teeth are not cataloged in a central database, like DNA, so forensic dentists use antemortem dental records and postmortem dental records in order to make comparisons.

1. Antemortem records are obtained
2. Postmortem records are produced by careful charting and written descriptions of dental structures and radiographs
3. Comparisons are made between antemortem and postmortem records, examining each tooth and the supporting structures in turn
4. Similarities and discrepencies are noted
5. Conclusions are made

With the help of forensic dentistry, we can definitely narrow down the population pool to which the deceased belongs to, and hopefully correspond to the relevance of the case at hand.