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Forensic Odontology

Forensic Odontology

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Forensic Odontology

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  1. Forensic Odontology

  2. Students Will Be Able To: • Distinguish between odontology and forensic odontology. • Describe the structure of a typical tooth. • Compare and contrast permanent and deciduous human dentition.

  3. Odontology • It is the study of the anatomy and growth of teeth and diseases associated with the teeth and gums.

  4. Forensic Odontology • It is the application of dentistry in legal proceedings deriving from ANY evidence that pertains to teeth

  5. The Field • Requirements • Must have DDS degree • Should have specialized training in the field through lectures (not required) • Help • Identify human remains (individual and mass) • Analyze bite marks • Bite marks are compared to known teeth molds to find origin of bite injuries • Estimate age of the victim and perpetrator • Trace dental malpractice

  6. Why Teeth? • Every human body ages in a similar manner, the teeth also follow a semi-standardized pattern • Help establish relative age of person • Each human has an individual set of teeth which can be traced back to established dental records to find missing individuals • Teeth aremade of enamel (hardest tissue of the body) so it can withstand trauma (decomposition, heat degradation, water immersion, and desiccation) better than other tissues in body • Teeth are a source of DNA: dental pulp or a crushed tooth can provide nuclear or mitochondrial DNA that to help identify a person

  7. Physiology of Teeth • Digestion begins in the mouth as enzymes in saliva break down food particles as the teeth grind and crush large pieces of food

  8. Anatomy of Teeth • Typical tooth has three parts • Crown • Is the part of the tooth above the gum line • Neck • Is the place where the crown and the root meet at the gum line • Root • Is embedded in the bony socket of the jawbone

  9. Anatomy of Teeth • Teeth are contained in the alveolar process of the maxilla and mandible • Maxilla= upper jawbone • Mandible= lower jawbone

  10. Anatomy of Teeth • Composed of dentin • Gives the tooth its shape • Can be calcified or hardened • Often covered by enamel on the crown • Is calcium carbonate and calcium phosphate that helps protect the dentin from acid erosion • Covered by cementum in the root of the tooth • Anchors the tooth to the periodontal ligament • Ensures that teeth stay in proper location • Inside of tooth filled with tissue called pulp • Contains nerves and blood vessels

  11. Anatomy of Teeth • Two forms of teeth exist • Deciduous (baby) • Erupt from the gum around 6 months of age • 20 in all • Begin to fall out around age 6 • Adult (permanent) • Replace deciduous teeth • 32 in all

  12. Anatomy of Teeth • Shape and size of each tooth reflects its functions • Molars • Are broad flat teeth in the back of the mouth that are used to crush and grind food • Premolars • Have two pointed surfaces with which to grind and crush • Canine/Cuspids • Have one pointed surface and are used for tearing and shredding food • Incisors • Are the sharp cutting teeth in the front

  13. Students Will Be Able To: • Recognize the value of odontology in forensic investigations. • Explain how teeth and craniofacial features are helpful in estimating age, ancestry, and sex. • Differentiate between the dentition of humans and other animals.

  14. Use of Teeth to Estimate Physical Characteristics • Are more resistant to burning and decomposition than other tissues • Dental fillings, caps, and bridges often remain intact after death

  15. Physical Characteristics of Teeth • Include • Staining • Enamel erosion • Wear on the surface of the teeth • Shape of teeth • Gaps between teeth • Placement of fillings or dental work • Missing teeth • Broken teeth • Tooth alignment • Can be used to develop a biological profile of a decedent based off personal habits that can be used to match a missing person

  16. Age Estimation • Teeth emerge before age 25 in a predictable pattern • Can be used to develop accurate estimates of the age of victims younger than age 25 • After age 25, estimation is more difficult due to teeth being fully emerged • Less accurate estimate involves looking at eating habits, teeth grinding, dental work, and receding gums • Can be off by 4 years

  17. Ancestry Estimation • Certain craniofacial characteristics can be used to estimate a person’s ancestry • Includes • Prognathism • Orthognathism • Chin point • Size and shape of teeth

  18. Ancestry Estimation • Prognathism • Is the forward projection of the alveolar processes that contain the upper and lower teeth • Exhibited by individuals of Australian and African descent

  19. Ancestry Estimation • Orthognathism • Is the absence of the forward projection of the alveolar processes • Exhibited by individuals of European descent

  20. Ancestry Estimation • Chin point • Is projected in individuals of European and Asian descent • Is rounded in Australian aborigines and South Pacific islanders • Often called rocker jaw • Is intermediate in individuals of African descent

  21. Ancestry Estimation • Size and shape of teeth (incisors) • Individuals of Asian descent have shovel-shaped incisors instead of straight incisors

  22. Sex Estimation • Is difficult • Can be based off size and shape of teeth • Males have larger teeth than females • Canines in females are more pointed than in males

  23. Use of Teeth to Determine Identification • Identifications using dental records and photographs showing teeth are important when personal effects are not present on the person or if the remains have become skeletonized

  24. Dental Records • Teeth, skull, and jawbones are sent to forensic odontologist to make a positive identification • Antemortem records taken during life are compared to postmortem records after death • Dental implants and other dental work are useful for identification due to the presence of serial numbers on them

  25. Analyzing Teeth • The Universal System • Teeth are given a specific number • Primary teeth are given specific capital letter • Any dental work done on surface is noted • Sheets kept on dental file forever • When person is missing, files are transferred to the missing person’s office

  26. Bite Marks • Are impressions left on food, skin or other items left at a scene from an individual’s teeth • Porous surfaces that absorb the impact enough to make an impression • Impressions vary • Depending on the pressure applied, the impression will show accordingly • The more pressure there is, the more detail to the bite

  27. Analyzing Bite Marks • Bite marks are photographed with a scale • Bite marks on skin are taken over repeated intervals • Casts of impression are taken • Impression traced onto transparencies • Casts of suspects teeth are taken • Comparison between suspect cast and bite mark

  28. Animal Bite Marks • Nonhuman bite marks have a different dentition pattern than human bite marks • D0gs have 42 teeth while humans have 32 teeth • Shape of the mouth of an animal is more clearly distinguishable from the shape of a human mouth • Dog has a long, narrow arch compared to a C- or U-shaped arch of humans