Quality Resource Guide –
Lasers in Dentistry 4th Edition
www.metdental.com
Page 2
Fundamental Laser Science
T
he word laser is an acronym for Light
Amplification by Stimulated Emission of
Radiation. Light is a form of energy that
travels in a wave and also exists as a particle,
called a photon. Traveling at the speed of light,
this wave has both energy and size. Size is termed
wavelength, typically measured in meters. Useful
dental wavelengths are measured in billionths of a
meter, or nanometers, abbreviated nm; and current
instruments have emissions in the range of 500 nm
to 10,000 nm. Energy is expressed in joules, and a
useful dental quantity is a millijoule, one thousandth
of a joule.
Laser energy is distinguished from ordinary light by
the following two properties:
• Laser energy is generated as only one color, a
property called monochromaticism. Dental lasers
may emit visible or invisible light.
•
Waves of laser energy are coherent. Each wave
is identical in physical size and shape. This
monochromatic, coherent wave of light emerges
from the laser device as a precise collimated
beam and a uniquely efficient source of energy.
Inside the device, a process occurs called
amplification by stimulated emission of radiation,
which Albert Einstein theorized in 1916.
4
Chemical
elements, molecules, or compounds in the core of
the laser comprise the active medium. The core
is usually a solid but occasionally can be a tube
of gas. This core is surrounded by a pumping
mechanism that supplies the initial photon energy,
either in the form of an electrical current, by the use
of a rapidly strobing flashlamp, or another laser. The
photons interact and stimulate one another. They
are amplified with the aid of mirrors and collimated
by reflection and resonation to ultimately produce
a laser beam. That laser beam is then focused,
adjusted with various controls, and emitted. Figure 1
shows a graphic diagram of a typical laser.
Laser energy is a specific form of electromagnetic
radiation. Its spectrum ranges from gamma rays
with wavelengths only a few trillionths of a meter
in length to radio waves, whose wavelengths can
be thousands of meters long. Additionally, It is
important to note that currently available dental
instruments all produce non ionizing radiation. This
is to be distinguished from ionizing radiation, which
is mutagenic to cellular DNA components.
5
A few dental lasers emit visible light: the KTP laser
(named for a crystal of potassium titanyl phosphate
that modifies the wavelength of the internal Nd:YAG
laser) which has a green color of 532 nm; some
photobiomodulation (nonsurgical power) lasers with
red light emission in the range of 635-660nm; and
another low-level caries detector with a similar red
color at 655 nm.
All other laser devices emit invisible laser energy in
the infrared portion of the electromagnetic spectrum.
The other surgical instruments are, in ascending
wavelength order:
• 800 nm to 830 nm diode, with a semiconductor
active medium of aluminum, gallium, and arsenide;
• 940 nm diode, with a semiconductor medium of
aluminum, indium, gallium and arsenide;
• 980 nm diode with a similar active medium of
indium, gallium and arsenide;
• 1,064 nm diode with a similar active medium of
indium, gallium, arsenide and phosphorus;
• 1,064 nm Nd:YAG, where YAG is a crystal
of
yttrium aluminum garnet, doped (in laser
language this means
coated)
with
the
rare
earth element neodymium;
Table 1
Summary of Laser Types and Procedures (current indications: December 2013)
General Type
Wavelength
Delivery System
Clinical Procedures
(see note below)
KTP
532 nm
Flexible small fiber, bare ended in a
handpiece
Soft tissue surgery, whitening [a]
Photobiomodulation
630-980 nm
Flexible or rigid optic fiber with
accessory tips
Tissue warming, temporary pain relief and increased blood
circulation; photoactivated disinfection [b]
Diode
810, 940, 980,
1064 nm
Flexible small fiber, bare ended or
accessory tips in a handpiece
Soft tissue surgery, sulcular debridement [c], whitening [a];
one 940 nm diode can also be used for tissue warming, as
described above.
Nd:YAG
1064 nm
Flexible small fiber, bare ended in a
handpiece
Soft tissue surgery, sulcular debridement [c], laser assisted
new attachment procedure [d]
Nd:YAP
1340 nm
Flexible small fiber, bare ended
Soft tissue surgery, sulcular debridement, removal of
separated endodontic instruments and posts
Er,Cr:YSGG
2780nm
Semi flexible large fiber, handpiece
and tips added
Soft tissue surgery, hard tissue procedures, including calculus
removal, tooth preparation and osseous surgery; laser
assisted new attachment procedure
Er:YAG
2940 nm
Semi flexible large fiber, hollow
waveguide, articulated ararm.
Handpiece and tips added
Soft tissue surgery, hard tissue procedures, including calculus
removal [e], tooth preparation and osseous surgery; laser
assisted new attachment procedure [d]
CO
2
9300 nm
Articulated arm, handpiece and tips
added
Soft tissue surgery, tooth preparation, osseous surgery
CO
2
10600 nm
Hollow waveguide, articulated arm.
Handpiece and tips added
Soft tissue surgery, sulcular debridement [c], laser assisted
new attachment procedure [d]
Note:
[a] through [e] are for certain, not all, instruments in the wavelength