Forensic Dentistry and Anthropology (2023)

introduction

Since physical anthropology focuses on biological variation and human evolution,forensic anthropologyuses the methods of description and analysis of human remains to establish an individual's identity in a medico-legal context. The “medico-legal” context refers not only to possible criminal cases, but also to missing persons cases, mass death incidents, humanitarian crises and the repatriation of human remains, such as missing persons. Physical anthropologists trained in biology and human (particularly skeletal) anatomy can assist in medico-legal investigations by determining sex and estimating race or ancestry, age, and height over a lifetime;^54-56They may also contribute to facial reconstruction, DNA retrieval, and postmortem interval (or time since death, TSD) analysis and estimation, as well as determining “evidence of crime.”⁵⁵

Forensic Archeology and Anthropology

Forensic Archaeologyapplies archaeological methods to the search, discovery, documentation and mapping of human remains in a forensic context. Importantly, forensic archeology's role is to secure evidence and keep the [potential] crime scene intact. Like prehistoric artifacts and fossils, forensic remains are often found incidentally, often through construction or erosion, or, in the case of surface remains, by migrants and hunters.^{55, 57}Forensic archeology differs from the practice of forensic anthropology, which attempts to create a biological profile (i.e., age, sex, race, and height) of an unidentified individual.

Archaeological and anthropological practices overlap in the field of taphonomics, although taphonomic analysis may involve specialists from different scientific fields, including pathology, entomology, and botany. Taphonomy can be described as "the natural and cultural events, processes, and agents that transform human remains from the time of death to the time of analysis".^{55, 58}"[D]ecompositing remains are part of a complex ecosystem,"⁵⁹and these changes include the internal processes of post-mortem decomposition; perimortem trauma and postmortem bodily harm; and environmental activities (including insects and rodents, soil and weather conditions).^{59, 60}Taphonomic analysis can provide valuable clues as to species and time since death.

Anthropological analysis helps identify unknown human remains by creating a biological profile that allows family members, witnesses, or the general public to recognize and identify the individual, or to provide a specific (positive) identification of an individual by matching the dentofacial remains with dental records, add evidence of injury or antemortem surgery to medical records, or take a DNA sample and compare the results to a known individual. The dentition is particularly valuable for forensic identification, as recording patient and treatment history can provide appropriate evidence for a positive identification (see Forensic Dentistry section below).

Gender Determination: Skeletal elements, particularly the pelvis, skull, and long bones, can provide valuable evidence for sex (not sex) determination based on human sexual dimorphism (anatomical variation in shape and size based on biological sex). Morphological and metric differences between adult males and females can estimate sex with between 90% and 98% accuracy.⁶¹The pelvis is the most valuable diagnostic; The taller, narrower shape of the male pelvis contrasts visually with the lower, wider pelvis with a widened ilium and wide pelvic opening in women. Male skulls are typically "larger and more robust" than females (although the mandible, with its high plasticity, is unreliable as an indicator of gender).⁶¹Metric analysis of long bones, including the humerus, radius, ulna, and clavicle, can estimate sex with up to 97% accuracy.⁶¹

Estimate age of death: Age of death can be estimated from various postcranial skeletal elements. A subadult dentition is the most reliable indicator of age (see below), but adult age can be estimated using a combination of techniques to provide an age range when a dentition is not available. The stage of epiphyseal fusion of long bones is useful for estimating age in individuals under 28 years of age, although nutritional status, population, and sex can affect the timing of epiphyseal fusion.^{37, 62, 63}The pelvis is almost as important in determining the age of an adult as it is in determining sex. Degenerative changes in the auricular surface and pubic symphysis throughout adulthood are among the most reliable indicators of age in the adult skeleton.^{37, 64, 65}Other methods of estimating the general adult age range include the sternal end of the ribs,^{37, 56}and closure of the cranial suture.^{37, 63}

Assessment of race or parentage: Gross examination of a human skull without soft tissues can allow classification into three major human populations (or "races"); The shape and angle of the orbits, the shape of the nasal cavity, the extent of prognathism, and the relative width and length of the forehead and skullcap generally correspond to the breed.^{66, 67}The curvature of the human femur has been shown to reliably distinguish races.^{66, 67}

Appreciate height in life: The femur is also important in estimating a person's size in life. Simple formulas can be applied to the length of the femur, as well as other long bones, to estimate height, although they vary with sex and race.^{66, 68, 69}

The most accurate way to provide such forensic identification is a combination of methods and application of statistical analysis provided by software such as FORDISC.^{67, 70}uses the standard measure of bones to estimate adult sex and ancestry, or CRANID, which estimates ancestry using a discriminant analysis of measurements from a skull.^{67, 71}

Forensic Dentistry or Dentistry

Teeth are essential to both forensic anthropology and academic anthropology. In addition to being the most durable part of the human skeleton, teeth are also heavily genetically influenced, and specific developmental traits (such as spacing, wings) and dental treatment increase their importance in positively identifying an individual's remains. "The dental identification of a deceased is a primary task of forensic dentistry",⁷²and forensic dentistry, or dentistry, uses anthropological techniques to identify human remains based on dentition and related orofacial structures. While it is the forensic odontologist's responsibility to analyze and describe the unidentified remains, the forensic odontologist relies on the practicing dentist to provide accurate and comprehensive dental records as evidence of a presumptive identification or to rule out preliminary matches.^73,74

Even without access to dental records, a general description of as yet unidentified dental remains is possible. Forensic odontologists can estimate sex, age, and race or ancestry and provide a general description of the unidentified person while he was alive.

The first step in identifying human remains is to determine whether the remains are human or non-human. Several bones of mammals such as bears and pigs can be confused with human bones, particularly the phalanges. Human teeth are easily distinguishable from other animals, including living great apes.⁷⁵Humans have small, relatively blunt canines and lack the canine-incisor diastema characteristic of apes. Human premolars and molars clearly exhibit low, rounded cusps representative of omnivores, in contrast to the high crests of herbivores and the sharp, conical cusps of carnivores.⁷⁶As with parts of the appendix skeleton, bears and pigs share some similarities in the shape of the molars with humans, although bear and pig molars are significantly larger.^{63, 76}

Estimation of age based on dentition.

Subadult age is easily estimated from the regular development and eruption sequence of deciduous and secondary teeth up to the point of eruption of the third molar. Eruptive sequence diagrams, such as the seminal one by Schour and Massler1941 chart inJADAand more recently theLondon Tooth Development Atlasand eruption are commonly used by academic and forensic anthropologists.^{34, 36}

However, by the time adult dentition is fully developed, age estimation becomes much less reliable and it is more appropriate to classify ages in broad ranges (e.g., "under 45" or "over 50"). Methods for determining tooth age are discussed in ADA White Paper 1077, Human Age Assessment by Dental Analysis, which describes radiological, microscopic, and visual macroscopic examinations of tooth structures after adult dentition. The technical report identifies root translucency, secondary dentin deposition, periodontal attachment, cement apposition, attrition, and root resorption as criteria that can be used to estimate the age of adult teeth.⁷⁷The ADA Technical Report 1077 was adopted by the American Board of Forensic Dentistry as standards and guidelines for determining the age of dentists and was included in the Organization Register of Scientific Area Committees for Forensic Science in November 2021 (see ADA News article).

Sex determination from the adult dentition.

Human deciduous teeth and permanent canines exhibit approximately 7% sexual dimorphism, although affected by ancestry, which exhibits similar dimorphism between black and white Americans.^{63, 78}This difference in size between male and female teeth results in an accuracy of 75 to 80% when determining sex from dentition.⁶³The pulp and dentin of teeth also provide a reservoir of DNA that makes it possible to determine sex even from fragmentary remains.⁷⁹

Judgment of parentage or breed since teething.

As discussed above in the Anthropological Analyzes of Teeth section, various metric and non-metric characteristics can help assess geographic ancestry, although accurate results require analyzes of combinations of characteristics and statistical probabilities: no single tooth characteristic can population or "race" determine. of an individual, but "complexes" of traits help distinguish certain populations from others.^{75, 78, 80}Shovel-shaped incisors are more common in Asian populations, particularly Native Americans, and the expression of the accessory cusps, particularly Carabelli's cusp, varies between populations; These features are most commonly used in forensic identification.^{63, 66, 67, 78, 80, 81}In general, European Americans tend to exhibit such anterior dentition nonmetric dimorphism, while African Americans more commonly exhibit posterior dentition nonmetric variation.⁷⁵African populations generally have larger molars, while European-American teeth are smaller and denser.^{63, 66}In addition, DNA extracted from dental material can be analyzed for general clues to ancestry or physical characteristics, including eye, hair and skin color.^{82, 83}

Other aspects of forensic dentistry: perimortem trauma and bite mark analysis

Assessment of perimortem trauma can be performed by a forensic anthropologist, but this task is usually performed by a licensed forensic pathologist, coroner, or coroner (although any of these could also be a forensic anthropologist). Forensic dentistry has traditionally been involved in the analysis of bite marks, which, rather than identifying a potential victim, can provide identifiable information about an offender who may have left an impression of the front teeth that can be compared to dental records. Although several studies have confirmed the accuracy of basing positive identification on the unique shape of the anterior teeth,^{84, 85}its legal and scientific value has been questioned in recent decades.^86-88

duties of the dentist

Successful positive identification requires not only the work of police officers and forensic anthropologists, but also the maintenance of extensive and detailed records by the practicing dentist. Various ADA guidelines (see ADA Dental Anthropology Guidelines below), standards and specifications (see below) encourage dentists, dental societies and others to assist with forensic examinations as permitted by applicable law and to follow procedures and standards , which are intended to facilitate the positive identification of human remains.⁸⁹

ADA Technical Report #1088provides dental practitioners and others with guidance on methods and best practices for collecting and matching forensic dental data for positive identification based on comparative dental analysis.ANSI/ADA Specification #1058standardizes requirements for documentation of dental information to help forensic odontologists make an unambiguous match between a set or description of human remains and dental records. As defined in ADA/ANSI 1058, the antemortem forensic dental record consists of six components: family record, dental history, dental data, oral data, visual images, and radiographic records.⁸⁹

The ADA Center for Professional Success provides additional guidance to support a forensic investigation inThe dentist's role in forensic identification, which states:

A dentist who receives a request for dental records as part of a forensic investigation must cooperate with authorities who will provide the dentist with a valid and properly served warrant, court order, subpoena or administrative order. State laws, and possibly HIPAA privacy regulations, determine the circumstances in which recordings may be released without a valid warrant or court order. Dentists may wish to consult their private attorney to deal with these situations.

Additional ADA resources for the dentist wishing to be prepared for a forensic examination includeAADA SCDI White Paper 1100-2021: Orthodontic/Craniofacial/Forensic Photographic View Codes, zCopy and/or transmit records of best practice guidelines.