TRAIT/ FEATURE

                                      METHOD

MICROSCOPE USED

Age Estimation

Cemental Annulations: Longitudinal section of teeth shows dark band (Incremental lines of Salter) expressing the end phase of mineralization with alternate white band. This expression of altered dark and light band is due to change in orientation of bundles of collagen fibers. Combination of an alternate light and dark band is considered as one annulation which when counted microscopically can aid in age estimation. [5]
Secondary Dentin Thickness: Secondary dentin deposition occurs regularly throughout the life, without being affected by external conditions like the periodontal status of tooth leading to reduction in the size and volume of pulp chamber.
It can be measured qualitatively by Gustafson’s method (more reliable) and quantitatively by Kedici’s method. [6]
Surface Alteration: Attrition, Abrasion, change in color, Root-Dentin translucency.
Change in color depends on thickness, texture and orientation of crystals, which varies with age and undergo alterations with increasing age. [7]
Transparent Dentin: Nanotechnology of TEM can be used to detect changes in mineral phase of transparent dentin and can help in estimation of age. [8]

Light Microscope, Phase contrast microscope
(Figure-2)

Polarizing microscope

Stereomicroscope

Stereomicroscope

Transmission Electron Microscope

.Sex Determination

Bar Body in dental pulp: Females have XX chromosomes. In order to prevent transmission of unnecessary information to next generations, one of two X chromosome in inactivated in somatic cells via Ionization. Histologically it can be seen as darkly stained basophilic round to oval body exclusively seen in females. It can be detected in pulp cells. [9]
F body: The Y chromosome is unique in that it is only found in male. A fluorescent dye, quinacrine, binds strongly to the Y chromosome and a bright fluorescent spot (F body) is clearly seen under ultraviolet light. [10]

Fluorescent Microscope
(Figure-3)

Fluorescent Microscope
Stereomicroscope

Cheiloscopy –
Gender & Ethnicity Determination

Study of pattern formed by creases and grooves on the surface of lip is called as cheiloscopy. Being unique to every individual, it can serve as an effective tool in determination of personal identity, race & gender. Commonly found in sexual assault cases, murders, child abuse, domestic violence cases etc.
Most common classification used is given by Suzuki and Tsuchihashi depicting 5 different patterns.
Various studies have shown that men are likely to have different patterns in all 4 quadrants while females tend to have similar patterns in all the quadrants.

Stereomicroscope
(Figure-4)

Dental Anthropology

Special morphological characteristics of tooth : presence of cusp of carabelli, hypocone, protostylid, shovelling of incisors, variation in size and shape, pathologies, wear patterns helps in identifying the ethnicity of an individual.[11]
As some characteristics are predominant in some racial groups.

Light Microscope
Phase contrast microscope
Polarizing microscope
Stereomicroscope
(Figure-5, 6)

Pink Tooth Phenomenon
(Forensic Thanatology)

It denotes cadaveric decomposition and microscopically can be detected in H & E stained decalcified sections by presence of haemoglobin in dentinal tubules, saturated with carbon Dioxide. [12]

Compound Microscope

Rugoscopy

Palatal rugae once formed, only increases in length. Due to its hard structure, it can withstand severe trauma & burns as it is shielded by lips and cheeks. Therefore, it can be used in mass disasters like plane crash accidents, floods, fire accidents etc. for determining personal identity, gender and ethnicity of an individual/ cadaver. It can be used in forensic cases in which finger print and lip print cannot be utilized due to decomposition and incineration.[13]

Stereomicroscope
 

Bite Mark Analysis

A bite-mark refers to an indentation on skin or any substance caused by a bite which in itself is a dynamic process determined by shape and size of dental arch and teeth, motion of muscles, pressure and intention of biter.
Presence of any developmental anomaly of teeth, carious lesion or any restoration can be used effectively by analysing the cast and can therefore be compared to solve the case.[14]

Stereomicroscope
Comparison microscope
(Figure-7)

Ameloglyphics

Enamel rods end on the tooth surface at different levels and in different directions, resulting in specific patterns on the tooth surface. The study of these enamel rod end patterns is known as ameloglyphics. Their study under electron microsocpe determines the uniquness of this pattern in relation to gender as well as type of dentition i.e. primary and permanent. [15]
Eg: In case of fire accidents tooth can serve as a promising evidence as it can withstand high temperature.

Scanning Electron Microscope
(Figure-8)

Tongue Print

Tongue is dynamic organ with unique features which can be of utmost importance for identification on the basis of size, shape, texture, type and pattern of grooves on the dorsal surface of tongue has proved to be beneficial in gender identification. Various studies have shown females tend to have a sharp tip at the apex, while men have septate tip.[16]
Histologically, differences in orientation of muscle fibres especially in the middle region of tongue has shown sexual dimorphism.

Stereomicroscope,
Light Microscope

Microbial Analysis Of Biofilms- Bio imaging

TEM is used in identification of morphological characteristics of bacteriophage.
Dark field and Phase contrast microscopes provide high resolution images of biological samples. [17]

Transmission Electron Microscope

Neonatal Line

It is a hypo-mineralized structure present on the surface of enamel of all primary and permanent first molars & marks live birth. In the field of forensic odontology, it can be used as an evidence of live birth against still birth in cases of neonaticide.
In presence of neonatal line, the amount of hard tissue formed can be used as an evidence to estimate the chronological age. [18]

Compound Microscope
Polarized Microscope
Scanning electron Microscope

Diatoms

In case of drowning, directing the case study by determining the location and characteristics of diatoms which are single celled algae with transparent membrane containing opaline silica. Also helps in reviewing biomineral formation in diatoms. [19]
In criminal cases it helps in determining the time of deposition of bloodstains therefore estimating the time of occurrence of crime

Atomic Force Microscope
(Figure-9)

Forensic Entomology

It is a branch of forensics that helps in estimating the Post Mortem Interval (PMI) by identifying the larva and eggs of insects and other arthropods found on the corpse during the early and late stages of decomposition. Microscope like SEM can help in visualising the morphological changes occuring throughout the life cycle of insect and therefore adequate knowledge of the cycle can help in determining the PMI.[20]

Scanning Electron Microscope
Comparison Microscope

Forensic Anthropology

Mandible being a strong bone can withstand harsh conditions and trauma. In anthropological studies mandible along with coated teeth have been studied for indicating possible cause of death.[11]

Scanning Electron Microscope

Food Composition Analysis

To identify and characterize food elements which can be found in the form of dried vomit deposits on the clothes, any food deposits from the soil or site of interest.
Food products showing bireferenges collected from the site can also be visualized under polarized microscope.[21]

Polarizing Microscope
Stereomicroscope