Dental Notes: July 2017

The Role of Dentist in Person Identification NOTES

INTRODUCTION

Odontological examinations are a critical determinant in search for the identity of individual human remains.
The most reliable means of identification include:
Fingerprints, Dental comparisons and biological methods such as DNA profiling

HISTORY

The first treatise on Forensic Odontology as a subject in its own right was written in 1898 by Dr. Oscar Amedo, who is the father of Forensic Odontology.
Though this particular science has been given importance recently, on the contrary, teeth have been used for identification for more than 2000 years.
One of the earliest known “Authentic cases of the application of dental information leading to the identification of an individual was that of Lollia Paullina in the year 49AD, she was the second wife of Claudius, the Emperor of Rome and was identified by her teeth which have certain distinct characteristics.
The first formally reported a case of dental identification was that of the 80-year-old English warrior John Talbot, who fell in the battle of Castillon in 1453.
The scientific employment of dental evidence in the identification of individuals began only in 17th century.
Some Examples are…

1692: Bite marks evidence were used to prove the guilt of Reverend George Burroughs who solicited young women into witchcraft.
1850: Dr. George Parkmen was identified through dental evidence, by a partial denture and portion of the jaw which was incinerated and then disposed of in privacy.
1870: Bite marks were used to prove the guilt of Mr. Robinson by bite marks on the body of the victims and model of his teeth.
1897: After a mass disaster by fire, dental identification was used.

COMMON REASONS FOR IDENTIFICATION OF FOUND HUMAN REMAINS

CRIMINAL
MARRIAGE
MONETARY
BURIAL
MASS DISASTERS
CLOSURE
Teeth are the most durable organs in the body and can be heated to temperatures of 1600°C without appreciable loss of micro structure.

BASIS FOR DENTAL IDENTIFICATION

The basis for dental identification is based on the fact that human dentition is never the same in any two individuals.
Although teeth are relatively resistant to environmental insults after death, during life they are susceptible to physiological and pathological changes.
The number of combinations 16 missing teeth can produce is approximately 600 million.
Four missing and four filled teeth in a mouth combined can produce more than 700 million combinations.

DENTAL IDENTIFICATION PROCEDURES

There are essentially two forms of dental identification-The first known as comparative identification and the second, reconstructing identification or dental profiling.
Dental profiling is undertaken when virtually no clue exists about the identity of the deceased.
It is a conventional method of postmortem dental identification and includes four steps namely:

ORAL AUTOPSY
OBTAINING DENTAL RECORDS
COMPARING POST- AND ANTE-MORTEM DENTAL DATA
WRITING A REPORT AND DRAWING CONCLUSIONS

ORAL AUTOPSY

It involves examination of deceased, usually with dissection to expose the organs, to determine the cause of death.
It has a systemic protocol starting with the critical examination of external features of the body such as gender, ethnicity, build, wounds, scars, tattoos.
Oral examination is an essential part of post-mortem procedure.
A thorough examination of soft tissue injuries, fractures, and the presence of foreign bodies is undertaken and samples of hard and soft tissues may be obtained for further investigations.
All this information is entered on to the standard “Interpol post-mortem form” which is color coded in pink.

OBTAINING DENTAL RECORDS

Dental records contain information of treatment and dental status of a person during his/her lifetime.
Such records may be in the form of dental charts, radio graphs, casts and/or photographs.
The contents of all available dental records should be transcribed onto the standard “Interpol antemortem form” which is color coded in yellow.

COMPARING POST- AND ANTE-MORTEM DENTAL DATA

Once the post-mortem evidence and dental records are available, the data can be compared.
Features compared include tooth morphology and associated bony structures, pathology and dental restorations.

WRITING A REPORT AND DRAWING CONCLUSIONS

One needs to remember that any attempt at establishing identity is addressed to the legal authorities. Therefore, a detailed report and factual conclusion, based on the comparison, must be clearly stated.
Acharya and Taylor have suggested a range of conclusions, which include:

Confirms Identification
Probable Identification
Possible Identification
Insufficient Information
Excludes Identification

IDENTIFICATION FROM DENTAL DNA

The conventional method of dental identification described thus far requires one basic element that may not always be readily available-adequate or complete dental records.
Since teeth can resist extreme conditions, they are the excellent source of DNA.
Routinely applied technique in forensic investigations, known as polymerized chain reactions allow amplification of even highly degraded DNA.
This facilitates comparison with the known biological antemortem sample of the person such as hair, epithelial cells from a tooth brush or a biopsy specimen.
If the person's antemortem sample is unavailable, the DNA pattern may be compared to a parent or a sibling, thus allowing identification.

DENTAL PROFILING

Dental profiling includes extracting a triad of information-the decedents ethnic origin, gender, and age.
The information from this process will enable a more focused search for antemortem records.

IDENTIFYING ETHNIC ORIGIN FROM TEETH

Anthropologists have divided race into following broad groups
(i) Caucasoid
(ii) Negroid
(iii) Mongoloid
(iv) Eskimos
(v)American Indians
(vi) Orientals

The size of teeth: Both deciduous and permanent dentitions are considered. The size of the teeth varies in different races

Larger teeth are seen in Australian, South American Indian tribes.
Lateral incisor is relatively large compared to central incisor in mongoloids.
Intermediate sized teeth are seen in Taiwanese Aborigines and Australian whites respectively.

GENETIC AND ENVIRONMENTAL INFLUENCES ON TEETH

Scott and Turner suggested that characteristic dental features have evolved over time as a result of genetic and environmental factors that have influenced different population groups.
Dental features used to describe population differences are broadly categorized as a metric (tooth size) and non-metric (tooth shape).
Metric features are based on measurements and non-metric in terms of presence or absence of a particular feature, eg: whether Ccarabellis cusp is present or absent.

NONMETRIC DENTAL FEATURES

More than 30 non-metric features of the tooth crown and root have been described and analyzed by Scott and Turner.

CROWN FEATURES

Shoveling
Double shoveling
Carabelli’s feature
Three cusped upper 2nd molar
Cusp 5
Cusp 6
Winging
Five cusped lower second molar
Lower molar groove pattern
Interruption groove
Enamel extension
Odontome
Lateral incisor variants
Distal accessory ridge
Premolar accessory ridge
Premolar lingual cusp
Mesial marginal complex of upper molars
Parastyle
Protostylid

ROOT FEATURES

Two-rooted upper premolar
Two rooted upper molar
Two rooted lower canine
Tomes root
Three rooted lower molar
Single rooted lower molar

SEX DETERMINATION

Determining the sex of unknown human remains is the second step in building a dental profile.
Gender can be determined based on data from---
1. CRANIOFACIAL MORPHOLOGY AND DIMENSIONS
2. SEX DIFFERENCES IN TOOTH SIZE
3. TOOTH MORPHOLOGY
4. SEX DETERMINATION BY DNA ANALYSIS.

Amelogenin (AMEL) is one of the major matrix proteins secreted by the ameloblasts of the enamel.
The AMEL gene, coding for a highly conserved protein, is located on X- and Y-chromosomes in humans.
Thus the females(XX) have two identical AMEL genes but the males(XY) have two nonidentical genes.
Preparing DNA from teeth by ultra-sonification, and subsequent PCR amplification, these authors obtained 100% success in determining the sex of the individual.

DENTAL AGE ESTIMATION

The final step in the triad of dental profiling, age estimation is an important subspecialty of forensic sciences.

DENTAL AGE ESTIMATION METHODS

Dental age estimation makes use of morphologic, radiographic, histologic and biochemical methods to examine the age dependent changes in teeth
It is grouped into three phases:

Ageing in prenatal, neonatal and early postnatal.
Age estimation in children and adolescents.
Age estimation in adults.

AGE ESTIMATION IN ADULTS

Following completion of growth, changes in the dentition used to estimate age “are influenced not only by age of the individual but also by numerous endogenous and exogenous factors, such as disease, nutrition, and physical strain.”
The different methods used are:
1) Gustafson’s method
2) Dentine translucency
3) Radiographic method of Kvaal and associates
4) Amino acid racemization
5) Other methods

1. GUSTAFSON’S METHOD

This method is based on morphological and histological changes of the teeth.
This assessed regressive changes such as:

a. Amount of occlusal attrition(A)
b. Coronal secondary dentine deposition(S)
c. Loss of periodontal attachment(P)
d. Cementum opposition at the root apex(C)
e. Root resorption at the apex(R)
f. Dentine translucency(T)

For each of these regressive changes or variables, different scores ranging from 0-3 were assigned.
Adding the allotted score for each variable(Eg : A3+S2+P2+C1+R2+T1 = X ) ,a total score was obtained.
Age was estimated using the formula
Age = 11.43 + 4.56X.
It was found that an increase in the total score corresponds to an increase in age.

2.DENTINE TRANSLUCENCY

Bang and Ramm were the first to use dentine translucency alone for estimating age.
Root dentine starts to become translucent during the third decade of life beginning at the apex and advancing coronally.
Therefore dental root translucency increases with advancing age.

3.AMINO ACID RACEMISATION

Helfman and Bada first suggested a relationship between dentinal age and the extent of aspartic acid racemization in dentine.
Aspartic acid has a rapid rate of racemization.
Therefore, there is a constant change in the ratio of L- and D-aspartic acid at different ages and this D-L ratio may be used for age estimation.
This method is accurate with age estimates within plus/minus three years of actual age.

CRIME INVESTIGATION

Forensic dentist plays a vital role in criminal investigation.
Crime investigation includes investigation of bite marks, child abuse, and lip prints.

BITE MARKS

Bite marks have been defined by MacDonald as “a mark caused by the teeth either alone or in combination with other mouth parts.
Bite marks may be caused by humans or animals; they may be in tissue, food items, or other objects.
Human bite mark is broad U shaped and somewhat circular or oval whereas bite mark of animal is narrow in anterior aspect and is V shaped
Bite marks are usually associated with physical abuse, violent fights, child abuse and theft.

IDENTIFYING THE INJURY AS BITE MARK

Sweet suggested that a human bite mark can be identified by following features:
1. GROSS FEATURES- A circular or elliptical mark found on the skin with a central area of ecchymosis.
2. CLASS FEATURES- This enables one to differentiate between different types of teeth. Incisors produce rectangular marks; canines are triangular or rectangular depending on the amount of attrition; premolars and molars are spherical or pinpoint.
3. INDIVIDUAL FEATURES- These include characteristics such as fractures, rotations etc.

BITES AND CHILD ABUSE

Child abuse has been defined by Vale as “any act of commission or omission that endangers or impairs a child’s physical or emotional health and development.
Child abuse may be broadly classified as physical abuse, sexual abuse, emotional abuse and neglect of the child.
Kenney and Clark have cited numerous researches that suggest approximately 50% of injury in child abuse cases occur in the oral and perioral region.

BITE MARK INVESTIGATION

A. Preliminary questions
B. Bite mark evidence collection from the victim

The bite mark evidence should be collected when it is first presented and observed.
If the suspected bite mark is criminal in nature, it must be reported to the law of enforcement agencies.
The protocol for bite mark evidence collection includes the following steps, as suggested by American Board of Forensic Odontology

VISUAL EXAMINATION
PHOTOGRAPHY
SALIVA SWAB
IMPRESSIONS

BITE MARK ANALYSIS AND COMPARISON

It is important to consider uncommon characteristics of bite marks such as presence or absence of a particular tooth, rotation, fracture, diastema, and other unusual features, as these may help in implicating a suspect.

CONCLUSIONS OF BITE MARK ANALYSIS

Any bite mark analysis has three likely outcomes.
1) Positive identification
2) Possible identification
3) Excludes identification

LIP PRINTS

The imprint produced by grooves is termed as ‘lip print’, the examination of which is termed as ‘cheiloscopy’.
Lip prints, therefore, can constitute material evidence left at a crime scene similar to fingerprints.
Lip prints were classified by Santos thus:

SIMPLE WRINKLES

Straight line
Curved line
Angled line
Sine-shaped curve

COMPOUND WRINKLES

Bifurcated
Trifurcated
Anomolous

Tsuchihashi later proposed a separate classification, dividing the pattern of grooves into six types.
I. TYPE-Clear-cut vertical grooves that run across the entire lip.
II. TYPE-Similar to type1, but do not cover the entire lip.
III. TYPE-Branched grooves
IV. TYPE-Intersected grooves
V. TYPE-Reticular grooves
VI. TYPE-Grooves that cannot be morphologically differentiated

DISADVANTAGES OF LIP PRINTS

The permanence of lip patterns is uncertain.
The anatomic position of lip grooves on the zone of transition is close to vermillion border—a zone which is extremely mobile.

CONCLUSION

Although we have attained civilization and culture, still we see deaths due to suicides, homicides, accidents, natural disasters and also sudden, unexpected deaths.
Every citizen should help the noble cause of the defense of the ‘innocent and punishment of the guilty’.
Major dental clues, once upon a time neglected, are now increasingly used to solve a crime.
Hence it is the public duty of dentist to assist in problems involving medico legal identification of the unknown body.
Dental evidence plays a vital role in establishing the identity of the dead.
The realm of forensic odontology can represent the most challenging and rewarding aspect in the field of dentistry.

REFERENCES

SHAFFERS
HIREMATH

Updated Post:
The Role of Dentist in Person Identification NOTES (Repost)

The Role of Dentist in Person Identification PPT

https://youtu.be/aMHy4Wmfq54

Investigation of Epidemic NOTES

INVESTIGATION

EPIDEMIC

CONTENTS

INTRODUCTION
DEFINITION
OBJECTIVES
STEPS IN INVESTIGATION OF EPIDEMIC
CONCLUSION

INTRODUCTION

Epidemiology is a scientific study of factors, conditions related to disease as they occur in people.
The word epidemic (epi = among, demos= people).
Epidemiology has an important role to play in the investigation of an epidemic.
Epidemic investigation is a set of procedures used to identify the cause i.e, the infectious agent responsible for the diseases, it is also used to identify the people affected.

DEFINITION

PARKIN (1873) defines epidemiology as “the branch of medical science which deals with the treatment of epidemics”.

Epidemic is an outbreak of disease that attacks many people at about same time and may spread through one or several communities.

OBJECTIVES OF INVESTIGATION OF EPIDEMIC

To define the magnitude of the epidemic outbreak or involvement in terms of time, place and person.
To determine the particular conditions and factors responsible for the occurrence of the epidemic.
To identify the cause, source of infection, and modes of transmission to determine measures necessary to control the epidemic; and
To make recommendations to prevent recurrence.

STEPS IN INVESTIGATION OF EPIDEMIC

Verification of diagnosis
Confirmation of existence of an epidemic
Defining the population at risk
Rapid search for all cases and their characteristics
Data analysis
Formulation of hypotheses
Testing of hypotheses
Evaluation of ecological factors
Further investigation of population at risk
Writing the report

VERIFICATION OF DIAGNOSIS

Verification of diagnosis: First step in an epidemic investigation.
Spurious, and arise from the misinterpretation of signs and symptoms by the lay public.
Not necessary to examine all the cases to arrive at a diagnosis.
A clinical examination of a sample of cases may well suffice.
Laboratory investigations wherever applicable, are most useful to confirm the diagnosis but the epidemiological investigations should not be delayed until the laboratory results are available.

CONFIRMATION OF EXISTENCE OF AN EPIDEMIC

The next step is to confirm if epidemic exists.
This is done by comparing the disease frequencies during the same period of previous years.
An epidemic is said to exist when the number of cases (observed frequency) is in excess of the expected frequency for that population, based on past experience.
Often the existence of an epidemic is obvious needing no such comparison, as in the case of common-source epidemics of cholera, food poisoning, and hepatitis A.
These epidemics are easily recognized. In contrast, the existence of modern epidemics (e.g., cancer, cardiovascular diseases) is not easily recognized unless the comparison is made with previous experience.

DEFINING THE POPULATION AT RISK

A) Obtaining a map of the area :

Before beginning the investigation, it is necessary to have a detailed and current map of the area.
If this is not available, it may be necessary to prepare such a map.
It should contain information concerning natural landmarks, roads and the location of all dwelling units along each road or in isolated areas.
The area may be divided into segments, using natural landmarks as boundaries.
This may again be divided into smaller sections.
Within each section, the dwelling units (houses) may be designated by numbers.

B) Counting the population :

The denominator may be related to the entire population or sub-groups of a population.
It may also be related to total events.
For this purpose lay health workers in sufficient numbers may be employed.
Using this technique it is possible to establish the size of the population.
The population census will help in computing the much-needed attack rates in various groups and subgroups of the population later on.
Without an appropriate denominator of “population at risk” attack rates cannot be calculated.

RAPID SEARCH FOR ALL CASES AND THEIR CHARACTERISTICS

A)Medical survey :

Concurrently, a medical survey should be carried out in the defined area to identify all case including those who have not sought medical care, and those possibly exposed to risk.
Ideally, the complete survey will pick up all affected individuals with symptoms or signs of the disorder.
Lay health workers may be trained to administer the "epidemiological case sheet or questionnaire to collect relevant data.

B)Epidemiological case sheet:

The epidemiologist should be armed with an "epidemiological case sheet" for collecting data from cases.
The epidemiological case sheet or "case interview form" should be carefully designed to collect relevant information.
The information collected should be relevant to the disease under study.

C)Searching for more cases:

The patient may be asked if he knew of other cases in the home, family, neighborhood school, work place having an onset within the incubation of the index case.
Cases admitted to the local hospitals should also be taken into consideration.
This may reveal not only additional cases but also person-to-person spread.

DATA ANALYSIS

The data collected should be analysed on ongoing basis using the classical epidemiological parameters

time
place
person

Time:

Prepare a chronological distribution of dates of onset and construct an "epidemic curve".
An epidemic curve may suggest

Time relationship with exposure to a suspected source
Whether it is a common-source or propagated epidemic.
Whether it is a seasonal or cyclic pattern suggestive of a particular infection.

Place :

Prepare a "spot map" (geographic distribution of cases, and if possible, their relation to possible sources of infection.
Clustering of cases may indicate a common source of infection.
Analysis of geographic distribution may provide evidence of the source of disease and its mode of spread.
This was demonstrated by John Snow in the cholera outbreak in the Golden Square district, London.

Person:

Analyse the data by age, sex, occupation and other possible risk factors.
The purpose of data analysis is to identify common event or experience and to delineate the group involved in the common experience.

FORMULATION OF HYPOTHESIS

On the basis of time, place and person distribution or the agent-Host-Environment model, formulate hypotheses to explain the epidemic in terms of
a) possible source
b) causative agent
c) possible modes of spread
d) the environmental factors which enabled it to occur

Formulation of a tentative hypothesis should guide further investigation.
Testing of hypotheses: All reasonable hypotheses need to be considered and weighed by comparing the attack rates in various groups for those exposed and those not exposed to each suspected factor.
This will enable the epidemiologist to ascertain which hypothesis is consistent with all the known facts.
Therefore it is instructive to turn back to arguments which have been tested by the subsequent course of events.

EVALUATION OF ECOLOGICAL FACTORS

An investigation of the circumstances involved should be carried out to undertake appropriate measures to prevent further transmission of the disease.
Ecological factors which have made the epidemic possible should be investigated such as sanitary status of eating establishments, water and milk supply: atmospheric changes such as temperature, humidity and air pollution, population dynamics of insects and animal reservoirs.
Further investigation of population at risk:

A study of the population at risk or a sample of it may be needed to obtain additional information. This may involve the medical examination, screening tests, examination of suspected food, feces or blood samples, biochemical studies, assessment of immunity status, etc.
The approach may be retrospective or prospective.

WRITING THE REPORT

The report should be complete and convincing
The report provides local public health departments an explanation of the parameters and the epidemics cause which enables timely and effective public health action.
Report should identify the risk factors that resulted in the epidemic.
Also report can be distributed to other public health professionals to help prevent a future similar problem.

CONCLUSION

It may be necessary to implement temporary control measures at the commencement of an epidemic on the basis of known facts of the disease.
These measures may be modified or replaced in the light of new knowledge acquired by the epidemic investigation.