A Magnified Microscopic Image Is Worth More Than A Thousand Words. DARK FIELD MICROSCOPE PHASE CONTRAST MICROSCOPY POLARIZED LIGHT MICROSCOPY FLUORESCENT MICROSCOPY STEREO MICROSCOPE ELECTRON MICROSCOPY

1. RESEARCH
MICROSCOPES
DR. AMITHA G, BDS, MDS
ORAL AND MAXILLOFACIAL PATHOLOGY

2. A Magnified Microscopic Image
Is Worth More Than A Thousand
Words.

3. DARK FIELD MICROSCOPE

4. DARK FIELD MICROSCOPE
Plant spores
Solar eclipse
Stars are shining both night and day, but they
are invisible during the day because the
overwhelming brightness of the sun "blots
out" the faint light from the stars, rendering
them invisible.
During a total solar eclipse, the moon moves
between the Earth and the sun blocking out
the light of the sun and the stars can now be
seen even though it is daytime.
In short, the visibility of the faint star light is
enormously enhanced against a dark
background.

5. Principle :
• It works by illuminating the sample with
light that will not be collected by the
objective lens and thus will not form part of
the image.
• This produces the classic appearance of a
dark, almost black, background with bright
objects on it.

6. USES:
• To view fungi, live bacterium, mounted cell and tissue.
e.g Treponema pallidium, Leptospira, vibrio cholera,
endospore.
• Examination of live blood samples.
• Study cancer cells.

7. PHASE CONTRAST MICROSCOPY

8. • It is an optical-microscopy technique
that converts phase shifts in light
passing through a transparent specimen
to brightness changes in the image.
• Phase shifts themselves are invisible,
but become visible when shown as
brightness variations.
• Used for microscopic observation
of unstained biological material
PHASE CONTRAST MICROSCOPY

9. USES:
• Visualization of internal cellular components.
• Diagnosis of tumor cells.
• To examine living and undistorted cell.
• For studying living and/or unstained material, such as
cells and tissues in culture.
• Specimens that are thin and scattered in the field of view
examination.
• Dental Plaque Bacteria
Epithelial cells
cocciDental Plaque

10. POLARIZED LIGHT MICROSCOPY

11. Transverse wave light whose vibration possess
direction is called polarized light.
Light from an ordinary light source (natural light)
that vibrates in random directions is called
nonpolarized light.
POLARIZED LIGHT MICROSCOPY

12. • Examination of normal and decayed hard tissue structure of
teeth.
• In Dentigerous cysts, thickness of fibers showed greenish
yellow color and thick fibers showed orange- red color.
• To compare the pattern of collagen fibers in odontogenic
cysts.
USES

13. • In OSMF, to analyze collagen distribution in
different stages using the picrosirius red stain under
polarized microscope.
• Protein : Collagen , amyloid, CEOT , keratin are
stained with congo red and examined by polarization
microscopy.
(a) collagen fibers in oral squamous cell carcinoma
microscopy.
(b) collagen fibers in oral squamous cell carcinoma

14. FLUORESCENT MICROSCOPY

15. • Various fluorescent dyes are used which gives
property of fluorescence to only specific part of the
cell and hence it can be focused.
• Depends upon illumination of a substance with a
specific wavelength (UV region i.e. invisible region)
which then emits light at a lower wavelength (visible
region).
FLUORESCENT MICROSCOPY

16. • Bacterial pathogens (e.g., Mycobacterium tuberculosis) can be
identified after staining them with fluorochromes.
• To distinguish live bacteria from dead bacteria by the color they
fluoresce after treatment with a special mixture of stains.
• To diagnose auto immune disease specially vesiculo bullous and
dermatological lesions e.g : pemphigus , pemphigoid
USES

17. STEREOMICROSCOPE

18. STEREOMICROSCOPE
INTRODUCTION
• It was first designed by GREENOUGH in 1897.
• It is also called as BINOCULAR DISSECTING
MICROSCOPE.

19. PRINCIPLE
• It is designed for low magnification observation of a sample, typically using light
reflected from the surface of an object rather than transmitted through it.
• It uses two separate optical paths with two objectives and eyepieces to provide slightly
different viewing angles to the left and right eyes.
• This arrangement produces a three-dimensional visualization of the sample being
examined.

20. • Microdissection of pathological specimen
• In dentistry in the field of endodontics, prostodontics and
implant dentistry
To check surface structure
Micro leakage
Bonding defects
And to see the margins of finished prosthesis
USES
Failure in the root canal filling - yellow circle.

21. ELECTRON MICROSCOPY

22. • Electron Microscopes (EMs) function exactly as their optical counterparts except that
they use a focused beam of electrons instead of light to "image" the specimen and gain
information as to its structure and composition.
• The Transmission Electron Microscope (TEM) is patterned exactly on the Light
Transmission Microscope except that a focused beam of electrons is used instead of
light to "see through" the specimen.
• The Scanning Electron Microscope (SEM) development was due to the electronics
involved in "scanning" the beam of electrons across the sample.
ELECTRON MICROSCOPY

23. SEM
• SEM focuses on the sample’s surface and its
composition and shows only the morphology
of samples.
• SEM allows for large amount of sample to be
analysed at a time
• SEM is used for surfaces, powders, polished
& etched microstructures, chemical
segregation
• SEM, picture is shown on monitor.
• SEM also provides a 3-dimensional image
TEM
• TEM provides the details about internal
composition. show many characteristics of the
sample, such as morphology, crystallization,
stress or even magnetic domains.
• The sample in TEM has to be cut thinner
TEM has much higher resolution than SEM.
• TEM only small amount of sample can be
analysed at a time.
• TEM is used for imaging of dislocations, tiny
precipitates, grain boundaries and other defect
structures in solids
• In TEM, pictures are shown on fluorescent
screens
• TEM provides a 2-dimensional picture.

24. USES
• Preparation of tissues and cells, as well as negative staining
of macromolecules, viruses, and nanoparticles.
• Used to see the ultra structure of cells
• Structure of protein molecules
• Organization of molecules in viruses and cytoskeletal
filaments
• Arrangement of protein molecules in cell membranes

25. THANK YOU