Essay on forensic dentistry
In the group evolved to Association adopting a ByLaws and an elected Board. Upon collection of dental evidence, the forensic odontologist analyzes and compares the bite marks. Studies have been performed in an attempt to find the simplest, most efficient, and most reliable way of analyzing bite marks. Bites can occur on both the victim and the suspect; teeth are used as weapon by the aggressor and in self-defense by the victim.
Although they are only a small portion of most forensic dentist's case load, bite marks represent the most challenging aspect of the discipline. In addition to the location of the bite mark the type of severity of the injury may give investigators clues as to the mental state of the offender. Bite marks may be found on the flesh of victims of a violent attack, particularly on the stomach or buttocks. Alternatively they may be found on the suspect, left by the victim during self-defense. Bite marks can be altered through stretching, movement, or change in environment after the bite.
There is also no set standard by which to analyse and compare bite marks. Factors that may affect the accuracy of bite mark identification include time-dependent changes of the bite mark on living bodies, effects of where the bite mark was found, damage on soft tissue, and similarities in dentition among individuals. Other factors include poor photography, impressions, or measurement of dentition characteristics.
Most bite mark analysis studies use porcine skin pigskin , because it is comparable to the skin of a human, and it is considered unethical to bite a human for study in the United States. Limitations to the bite mark studies include differences in properties of pigskin compared to human skin and the technique of using simulated pressures to create bite marks.
Forensic Odontology: The New Dimension in Dental Analysis
In recognition of the limitations of their study, Kouble and Craig  suggest using a G-clamp on an articulator in future studies to standardize the amount of pressure used to produce experimental bite marks instead of applying manual pressure to models on pigskin.
Kouble and Craig compared direct methods and indirect methods of bite mark analysis. In the past, the direct method compared a model of the suspect's teeth to a life-size photograph of the actual bite mark. In these experiments, direct comparisons were made between dental models and either photographs or "fingerprint powder lift-models. Indirect methods involve the use of transparent overlays to record a suspect's biting edges.
ODONT 6012OL - Principles and Methods of Forensic Odontology
Transparent overlays are made by free-hand tracing the occlusal surfaces of a dental model onto an acetate sheet. The use of transparent overlays is considered subjective and irreproducible because the tracing can be easily manipulated. On the other hand, photocopier-generated overlays where no tracing is used is considered to be the best method in matching the correct bite mark to the correct set of models without the use of computer imaging.
While the photocopier-generated technique is sensitive, reliable, and inexpensive, new methods involving digital overlays have proven to be more accurate. Both methods use Adobe Photoshop. Use of the 2D polyline method entails drawing straight lines between two fixed points in the arch and between incisal edges to indicate the tooth width.
Use of the painting method entails coating the incisal edges of a dental model with red glossy paint and then photographing the model. Adobe Photoshop is then used to make measurements on the image.
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A total of 13 variables were used in analysis. Identification for both methods were based on canine-to-canine distance one variable , incisor width four variables , and rotational angles of the incisors eight variables. The 2D polyline method relies heavily on accurate measurements, while the painting method depends on precise overlaying of the images.
Although both methods were reliable, the 2D polyline method gave efficient and more objective results. Recently, the scientific foundation of forensic odontology, and especially bite mark comparison, has been called into question. An investigative series by the Chicago Tribune entitled "Forensics under the Microscope" examined many forensic science disciplines to see if they truly deserve the air of infallibility that has come to surround them.
The investigators concluded that bite mark comparison is always subjective and no standards for comparison have been accepted across the field. The journalists discovered that no rigorous experimentation has been conducted to determine error rates for bite mark comparison, a key part of the scientific method. Critics of bite mark comparison cite the case of Ray Krone , an Arizona man convicted of murder on bite mark evidence left on a woman's breast.
DNA evidence later implicated another man and Krone was released from prison. Although bite mark analysis has been used in legal proceedings since , it remains a controversial topic due to a variety of factors. DeVore  and Barbenel and Evans  have shown that the accuracy of a bite mark on skin is limited at best. Skin is not a good medium for dental impressions; it is liable to have a number of irregularities present before the imprint that could cause distortion. Also, bite marks can be altered through stretching, movement or a changing environment during and after the actual bite.
Furthermore, the level of distortion tends to increase after the bite mark was made. Both studies suggest that for the bite mark to be accurately analyzed, the body must be examined in exactly the same position it was in when the bite occurred, which can be a difficult if not an impossible task to accomplish. Therefore, bite marks found at the scene are often analyzed under the assumption that they have undergone minimal distortion.
The lack of research may largely be due to the fact that such studies are difficult to organize and are very expensive. Bite mark analysis is also controversial because dental profiles are subject to change. The loss of teeth or the alteration of arch configuration through a variety of procedures is common in human populations. The onset of oral diseases such as dental caries has been shown to alter the arch and tooth configuration and must be taken into account when comparing a dental profile to the bite mark after a significant amount of time has passed since the mark was made.
While the methods behind collecting bite mark evidence at the scene are leading toward greater standardization, the methodology behind analyzing bite marks is extremely variable because it depends upon the preference of the specific odontologist. As discussed earlier, there are several methods used to compare bite marks ranging from life-sized photographs to computer enhanced three-dimensional imaging. These methods vary in precision and accuracy, and there is no set standard by which to compare or analyze them. Some odontologists even disagree on whether or not a mark on the body is the result of a bite.
One possible issue facing bite mark analysis is a lack of bite mark uniqueness in any given population. Bite mark analysis is based on the assumptions that the dental characteristics of anterior teeth involved in biting are unique amongst individuals, and this asserted uniqueness is transferred and recorded in the injury. A study performed by MacFarlane et al. They also used plaster of paris as the substrate to simulate skin, yet the two materials have very different properties.
Rawson et al. However, in this study the probabilities used to make this claim are based on the assumption that the position of each tooth was independent of all the others. For example, braces apply force to specific teeth, in order to shift the placement of multiple teeth. One particular case that highlighted the lack of uniqueness in bite marks involved two suspects accused of attacking a man who had sustained a bite mark injury.
They reported conflicting results.
Forensic Odontology (Simplified) - Words | Cram
One found the mark to come from suspect A and the other said it was from suspect B. This disagreement resulted from the fact that even though the two suspects had dental features making them unique, the bite mark itself was not detailed enough to reflect them. Far after decomposition has ended. The oral cavity can be used as evidence, because no one person can have the same dental work and dental structure as another. Using dental forensics to determine an age can be extremely accurate. As age increases, the means to identification vary from person to person. The age of a teenager can be estimated by looking at the third molars, when these teeth come into the mouth at an age ranging from 17 to 25 years old.
Determining the age of an adolescent can be precise because the oral cavity is somewhat at a standstill. When odontology is used to determine the age of an adult or someone referred to as elderly, the age estimation may not be as accurate. After all of the adult teeth have grown in, the oral cavity goes through slight changes. As someone gets older their gum tissues soften and their teeth usually become more mobile as the ligaments attaching the teeth grow weak. This alone is not an accurate indication as to how old an adult is because every adult uses and takes care of their teeth in a different manner.
https://tiotrabletuli.tk Forensic dentists use previously taken FMX full mouth set of x-rays and BWX bitewing x-rays , along with dental records to figure out a subjects identity. When new x-rays are taken, the forensic dentist can try to find x-ray matches in dental records and world wide databases.