forensic test one (Forensic Odontology)

Teeth characteristics~

•Crown, neck, root

•20 deciduous teeth: 10 maxillary, 10 mandibular arch

•2 incisors, 1 canine, 2 molars (5 teeth x 4 = 20 baby teeth)

•32 adult teeth: 16 maxillary, 16 mandibular arch

•2 incisors, 1 canines, 2 bicuspids (premolars), & 3 molars

•(8 teeth x 4 = 32 permanent teeth)

•# of roots depends on tooth type & location (upper –vs- lower arch)

Teeth characteristics (cont.)~

•Dentine= calcified connective tissue w/ Ca²⁺ salts ~70% dry wgt

•Layer of enamel (95% Ca²⁺ salts) covers crown

•Layer of bone-like cementum covers root

•Center of tooth is the pulp cavity, containing connective tissue, blood vessels, nerve endings

Emergence of 2 sets of dentitions~

•Deciduous teeth: ~6 months first emergence occurs, then a pair monthly until 20 teeth have erupted

•begin loosing baby teeth ~6 yrs until ~12 yrs, while being replaced w/ permanent teeth

•Permanent teeth: additional molars erupt

•wisdom teeth (3^rd molars) may erupt after ~17 yrs, or not at all

Identifications~

•Victim is decomposed, mutilated, burned, or skeletonized such that photo/visual ID is of no assistance

•—Dentition may be virtually unaffected & ID made w/ great certainty

•Other forms of ID produce conflicting conclusions

•No fingerprints available (ante- or postmortem)

•—Dental records can be obtained

•Bone trabeculation patterns &/or sinus cavity configuration of edentulous (no teeth) or partially edentulous victims can provide possible-to-positive ID

•Estimation of age

•‘neonatal line’: enamel deposited in a series of striae

•Subadult emergence of teeth (Table 4.1)

•Potential to age individual teeth??

•Gender and racial origin

•Difficult to ID gender, yet DNA in pulp may possibly available

•Some morphological (slight) differences can be used as traits to suggest race

•Shovel-shaped incisors of mongoloid ancestry

•Dentition, mandibular arch, etc.

Mass Fatalities~

•Lrg # of IDs occur simultaneously, sorting & ID of possible co-mingled remains

Bitemark Evidence~

•Child abuse, rape, aggravated assaults, homicides

•Comparison of teeth (& position in arch) can provide:

•aging of 2+ bites

•inclusion or exclusion of an individual from a grp of possible biters

•Determination of human –vs- non-human

•Analysis of other materials (gum, food, non-foodstuffs) that may have been bitten & left @ crime scene

•FO should inspect potential victim bite(s) on suspected perpetrator, thus, preserving the bitemark evidence

photograph & study models of the victim’s dentition

Child Abuse~

•Examination of intraoral & extraoral injuries, as well as, pre-existing oral conditions indicating neglect or previous trauma

•Bitemarks found on child abuse victims should be photographed & documented immediately by a FO to preserve the evidence

Other~ when to use a FO

•Pieces or a whole tooth found at a crime scene can be analyzed regarding:

•human or animal; belonging to victim or perpetrator; & potentially placing individual(s) at the crime scene

•Estimations of age, sex, & ethnicity

•Charting dental info for unID persons into federal computer program (FBI) for use of comparing missing persons data

Visual~

•Not scientific & often unreliable, but most frequent means of ID

Fingerprints~

•Most widely method used if available, but begin to deteriorate @ death

•Requires previous record (antemortem) & sufficient postmortem fingerprint material

DNA~

•Established technology that has replace dental & fingerprint IDs as the most definitive means of identifying remains

•BUT expensive & time consuming

•Must have antemortem genetic material for positive ID (material from family members only prove relationship)

•Methods exist for extracting DNA from teeth

dental

•A scientifically reliable method of ID providing the greatest accuracy in the most timely manner

•Postmortem changes are very slow…thus, survivability of dental evidence is tremendous

•—resistant to environmental effects & destruction by fire (i.e., can w/ stand harsh environments)

•—found intact in fires ~1600 ^oF due to protections by soft tissue & alveolar bone

•—dental restorations & prostheses even more resistant to physical & chemical deteriorations

•Potentially infinite # of points of comparison (i.e., individual characteristics)

•—each tooth could be: unrestored, restored, missing; the 160 tooth surfaces may have restorations, prosthetic appliances, etc.; tooth/crown morphology, pulp/root form

•Excellent antemortem data base since large % of general population visit a dentist

•—routine radiographs & dental records of antemortem dental conditions

•—records usually maintained for long periods of time & radiographs provide ‘hard’ evidence not subject to human error

•Relatively fast & easy to obtain

Skeletal Remains~

•Comparisons of ante- & postmortem images (healed fractures, unique bone morphology, etc.)

•Anthropologist can estimate sex, age, race

Identification by Exclusion~

•Method refers to comparison of postmortem data of deceased to known antemortem data from a finite # of suspect possibilites

•Not definite & used as a last resort

data gathering

Antemortem data~

•Dental x-rays, charts

•Military records, prison records

•Medical charts, x-rays

•Dental appliances, study models

Postmortem data~

•Dental remains collected from severely fragmented, decomposed, severely burned, or skeletonized bodies

•Charting & x-rays

data comparison

•Identification based on comparison antemortem records to postmortem remains

Panorex~

•Panoramic or whole mouth x-ray

•Shows teeth & supporting bone, maxillary sinuses, TMJ, nasal aperature, & inferior eye orbit

Bitewing X-rays~

•Most common dental x-ray

•Shows crown portion of posterior teeth

•May not show unerupted or impacted teeth, root canal treated teeth, or bone pathology & anomalies

Periapical X-rays~

Detailed x-rays of individual teeth that displays entire tooth & supporting bone

Equipment & personnel~

•Dental identification kit (instruments & supplies)

•Dental forensic forms (ante- & postmortem forms, ID summary forms)

•Portable x-ray unit & film developing/processing equipment

•Dental ancillary support (dental radiology techs, hygienists, assistants)

Processing remains includes:

•Cleaned w/ H₂O₂ or bleach

•Thorough charting of existing oral & dental conditions

•Radiology of remains

•Acquire antemortem records

Most common points for comparison~

•# of teeth (lost teeth PM need to be noted)

•Malposition & rotation of teeth

•Restorations & prostheses

•Dental caries

•Anomalous tooth formation

•Root canal therapy

•Bone pattern

•Occlusion

•Oral pathology

•Occupational & socioeconomic pattern of dentition