Pattern recognition forensic dental identification seminar Mustansiriya University Department of Education Computer Science

1. Lecture slide
By
Israa

2. What is Forensic Science?
• …the application of
science to those
criminal and civil laws
that are enforced by
police agencies in a
criminal justice system.

3. Definition of Forensic
Dental
 Forensic dental, or forensic odontology, is
the application of dental and paradental
knowledge to the solution of legal issues in
civil and in criminal matters.
 This field is very important in identifying
human remains that are decomposed,
mutilated, or visually unrecognizable.

4. The THEORY behind forensic
dentistry is that no two mouths
are alike (even identical twins are
different), and that teeth, like
tools, leave recognizable marks.

5.  During the U.S. Revolutionary War in 1775 , none other
than Paul Revere (a young dentist) helped identify war
casualties by their bridgework.
History
 Teeth are highly resistant to destruction and
decomposition, so dental identification can be made
under extreme circumstances.(1600ºC)
 It was used on Adolf Hitler and Eva Braun at the end
of World War II, the New York City World Trade
Center bombing, the Waco siege, and numerous
airplane crashes and natural disasters.

6. An Understanding of Teeth
• Teeth begin to appear at 6 months of age
and all should have emerged by age 3.
• Humans have 20 deciduous (baby) teeth.
• Between the ages of 7-21 years all of the
deciduous teeth should have been replaced
with permanent teeth.
• Adults have 32 permanent teeth. This
includes the four wisdom teeth.
• Teeth are the hardest substance in the body.

7. Teeth Basics
• Approximately 32 teeth
in adult mouth
• Four types of teeth:
– Molars
– Premolars
– Canine
– Incisors
• Teeth differ in:
– Size
– Shape
– Root type
Types of teeth

8. Identification using Teeth
The forensic dentist compares antemortem (before
death) records with postmortem (after death) findings
to determine if there is a positive match.
 Unusual features including the number and types of
teeth and fillings, the spacing of the teeth, and/or special
dental work (bridges, false teeth, root canals, cavities,
tooth pattern , crown, and general dental health neglect).

9. Age Estimation
 In living individuals, anthropologic age
determinants other than wrist
radiographs are not possible, so dental
age estimation can be valuable.
 In deceased individuals there may be
no skeletal evidence other than dental
structures or teeth to make an age
estimation.

10. DENTAL COMPARISON

11. There are two main purposes for forensic identification
of humans: suspect identification and victim
identification.
 For suspect identification, evidence such as
fingerprints or blood samples are collected at crime
scenes. Based on this evidence, the guilt or innocence
of the suspects can be confirmed.

12. Victim identification can be achieved by matching
antemortem (AM) and postmortem (PM)
• circumstantial evidence :includes a victim's
clothing, jewelry, and pocket contents. circumstantial
evidence can easily be attributed to the wrong person,
particu-larly when there are many victims to be
identifed.
• Physical evidence :is more reliable, and includes
external evidence, internal evidence, genetic
evidence, and dental evidence.

13. • The forensic dentist produces a postmortem record by
carefully charting and writing descriptions of the dental
structures and radiographs.
• Once the postmortem record is complete, a comparison between
the two records can be carried out.
• Similarities and discrepancies are noted during the comparison
process , There are two types of discrepancies :
• explainable :normally relate to the time elapsed between the
antemortem and postmortem records, e.g., teeth extracted .
• Unexplainable :for example a tooth is not present on the
antemortem record but is present on the postmortem record.

14. An example
of
postmortem
dental chart

17.  There are three common types of dental
radiographs (dental X-rays):
• periapical X-rays : show the entire tooth, including
the crown, root, and the bone surrounding the root.
• bitewing X-rays : are taken during most routine
dental check-ups and are useful for revealing cavities
in the teeth.
• Panoramic X-rays :give a broad overview of the
entire dentition (the development of teeth and their
arrangement in the mouth).

18. Three types of dental radiograph series. (a) Full mouth series;
(b) bitew-ing series; (c) panoramic series.

20. 1. Compared to traditional radiographs, only half the
dosage of radiation is needed for obtaining a dental
radiograph of comparable quality .
2. Digital dental radiographs do not require time for
film development.
3. Dentists can take another image instantly if the
acquired image is not good enough.
4. Digital radiographs are easier to store and process .
5. Environmently friendly.

21. • An individual's dental record includes information
about the number of teeth present, the orientation of
those teeth, and dental restorations. Each dental
restoration is unique because it is designed specifically
for that particular tooth. An individual's dentition is
defined by a combination of all these characteristics,
and can be used to distinguish one individual from
another.
• The information about dentition is represented in the
form of dental codes and dental radiographs.
• Forensic identification of humans based on dental
information requires the availability of antemortem
dental records.

22. Fully
automatic
process of
matching one
pair of PM and
AM images.

23. Challenges
• One challenge to future efforts in forensic identification
based on dental codes is the decline in the number of
dental restorations, which is attributed to increased
awareness of healthy dental habits.
• Changes in the dentition over time, such as tooth eruption
and loss, the sliding of neighboring teeth after a tooth is
extracted. These changes cause inconsistent appearances
of teeth in AM and PM radiographs from the same
individual.
• Changes in the imaging angle result in complex
deformations.

24. Changes in the imaging angle result in significant deformations in the
appearances of corresponding teeth in AM (a) and PM (b)

25. Summary
• Dental radiographs contain valuable information to
identify victims when other biometric traits are not
available. For example, in the terrorist attack on Sept. 11,
2001, many victims were identifiable only from pieces of
jaw bones. Dentists were asked to help in identifying the
victims using dental records and about 20% of the 973
victims identified in the first year after the 9/11 attack
were identified using dental records .
• Victims of the 2004 Asian tsunami were also identified
based on dental information: 75% of the tsunami victims
in Thailand were identified using dental records.

26. 1- Cost
Medium
2- Easiest
Easy to use.
3- Authentication
High
4- Identification
Identification can be achieved by matching antemortem (AM)
and postmortem (PM) dental records.
5- Physiological and/or behavioral characteristics
Physiological

27. 6- Ability to applied
High
7- Community Acceptance
Not very acceptance.
8- Automatic (real time)
With the digital radiography system, we get a large, high-
definition X-ray image displayed on computer screen in less than
two seconds.
9- life Cycle
Database need update because dental features do change over time.
10- Maintenance requirement
there is nothing you need to do to maintain your digital X-ray
equipment.

28. Thank
you