FORENSIC ODONTOLOGY AND BITE MARKS ANALYSIS

FDI defines as ‘that branch of dentistry which, in the interest of justice, deals with proper handling of dental evidence, and with proper evaluation and presentation of dental findings’

• History dates back to 66 AD

• Adolph hitler‐ dental identification

Role of forensic odontologist

• Identification of human remains through dental records and assisting at location of mass disaster

• Gender identification

• Age estimation of the both, the living and the deceased

• Bite mark analysis

• Presenting evidence in court

Identification

• Identity‐ Characteristics by which a person may be identified

• Traditional methods‐ visual recognition, personal property

• Physical features – Acquired and inherited features

• Dental – resistant to post mortem decomposition

Basis for dental identification

• Teeth – hardest in human body

• Resistant to decomposition – teeth, fillings Human Identification

• Comparison of ante mortem data with post-mortem data

• Presumptive vs. positive identification

Positive identification

• Dental record comparison

• DNA

• Fingerprints

• Radiological

Types of Evidence

• Inclusive

– The evidence is included in the population of items that came from the crime scene

• Exclusive

– The evidence is excluded from the items in the crime scene

• Direct

– Known by personal knowledge

• Circumstantial

– Knowledge by inference

Activity

• Look at dental x‐ rays and mark major features on the dental chart provided

• Look for

– Cavities

– Fillings

– Bridgework

– Missing teeth

Crime investigation

                                                            BITE MARKS

Mark made by the teeth either alone or in combination with other mouth parts  ( Mc Donald)

Patterned injury

Cameron and Sims Classification

1. Agents: a. Humans b. Animals c. Mechanical

2. Materials:

a. Skin and body tissues

b. Food substances

c. Other materials chewed habitually

Mc Donald’s classification

€Tooth pressure marks

€Tongue pressure marks

€Tooth scrape marks

€Complex marks

Webster’s Classification

• Type I ‐ Limited depth of tooth penetration

• Type II – Considerable depth of tooth penetration

• Type III – Complete or near complete penetration

FACTORS INFLUENCING THE BITE MARKS

€Type of tissue

€Age

€Sex

€Medical status

€Time

TYPES OF BITE MARK INJURY

• Indentations

• Contusions or Bruises

• Lacerations

• Avulsions

Indentations: Compression of the skin surface due to tooth pressure during a bite

Contusions or Bruises: Reddish / purplish discoloration of skin surface due to blood escape in to subcutaneous tissue

Lacerations: Break in integrity of skin surface due to the bite

                                  IDENTIFICATION OF BITE MARK

• Gross features

• Classical features

• Individual features

Gross features

Circular / Elliptical mark

Classical features: Pattern present in the bite mark.

Individual: Represents teeth with fractures or rotations.

                                                          SITE OF BITE MARKS

1. Sexual (male): Abdomen, Chest, Arm….

2. Sexual (female): Breast Thigh, Anterior Shoulder, Neck, Arm, Pubic area ETC

HISTOPATHOLOGICAL STAGES

• Stage 1 – 0 to 18 hrs – Scab formation

• Stage 2 – 30 to 70 hrs‐ epithelial regeneration

• Stage 3 – 5 to 12 days ‐ Sub epidermal granulation

• Stage 4 – after 12 days – Regression

                                                          BITE MARK INVESTIGATION  

1. Preliminary questions

2. Bite mark evidence collection from the victim and Suspect

3. Bite Mark analysis and comparison

4. Conclusion of bite mark analysis 

BITE MARK ANALYSIS

• Metric Analysis –odontometric triangle method

• Pattern Association

• Test bites

• Other methods

1. Trans illumination of tissue

2. Scanning electron microscopy

3. Video superimposition 4. Stereo microscopy

Odontometric triangle method

• Triangle made on bite marks and teeth models by marking three points

• Two reference points on outer most convex point of canines and one in the center of centrals

• Three angles measured and compared.

CONCLUSION

‰Positive Identification

‰Possible Identification

‰Excludes Identifications