Laser development started from a knowledge of the composition of light. According to modern physics, light has a dual nature, with properties of waves or particles (photons = carrier of energy). It depends on the wavelength and on certain circumstances that determine which character will dominate.

2. Laser In Dentistry : Benefits and
Drawbacks
By
Romissaa Aly Esmail
Assistant lecturer of Oral Medicine,
Periodontology, Diagnosis and Dental
Radiology (Al-Azhar University)

3. Contents:
• Introduction
• Properties of the Laser
• Laser tissue interaction
• Different Types of laser and its application

5. Laser development started from a
knowledge of the composition of light.
According to modern physics, light has a
dual nature, with properties of waves or
particles (photons = carrier of energy).
It depends on the wavelength and on
certain circumstances that determine
which character will dominate.

6. Laser light is based on having
photons in the same phase and
frequency (monochromatic light)
and in the same direction (e.g.
parallel beam).
Every laser has an
active medium (e.g.
atoms or molecules to
produce the laser light)
which can be agas, fluid
or solid state.
Typical laser can emit
the visible and adjacent
areas of the UV and IR
wavelengths (from
158nm down to the
10μm of the CO2 laser),
comprise a large group.
Diode and rare-earth
lasers (e.g. solid state
lasers based on the rare-
earth ions erbium,
neodymium, holmium) as
well as transition metal
(e.g. chromium) solid
state lasers are most
common in dentistry.

10. Properties of the Laser

11. With the term laser is identified a physical
principle leading to the production of
electromagnetic radiation, which differs from
the usual light in the following properties
● Coherence: Wave streaks remain parallel and
welldefined even in large distances. The light
has spatially the same phase (the waves are “in
tune”).

12. ● Collimation: The laser beam can give a localized spot
when something is in its way. This has the practical
advantage that the light can be well focused.
● Monochromatism: All wave streaks have the same
wavelength, the same frequency, and thus the same
energy.
The wavelength of the light plays a critical
role in medicine and determines today the exact clinical ranges of
application

23. The Laser Cavity
• From the practical standpoint, a laser device
contains the following components:
● The laser medium (active medium), which generates
the laser light (this is the “brain” of the system).
● The optical resonator (reflecting system)
● The laser pumping mechanis

32. Laser tissue
interaction

38. Absorption areas of the visible
and near infrared (a), mid-
infrared and far infrared (b),
middle ultraviolet and near
ultraviolet (c) wavelengths.

46. Photochemical Effects
The laser beam can
chemically change a tissue’s
molecules or warm a tissue,
when higher power densities
are applied.
As a result, different effects
may occur:
● formation of ions (photo-
ionization)
● isomerization of the
macromolecules
(photoisomerization)
● decomposition of the
molecules (photo-
dissociation).
These effects of the laser
energy can be applied
during biostimulation,
photodynamic therapy, or
also
acupuncture.
The chemical changes of the
tissue molecules due to
the photochemical effect of
the laser light can be shown
schematically as follows:
● photo-ionization: AB →
AB+
● photo-isomerization: AB →
BA
● photo-dissociation: AB →
A+B

53. • Different Types of laser and its
application