Lasers in orthodontics /certified fixed orthodontic courses by Indian dental academy

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


INTRODUCTION
• The theoretical concept of the laser was
proposed by Einstein in 1917
• Lasers were developed in early 1960’s and
rapidly found a number of uses in medicine and
surgery.
• Laser introduced into general dentistry in 1994
and they have been used in orthodontics for
number of years.www.indiandentalacademy.com

LASER
• The term laser is an acronym of “light
amplification by the stimulated emission of
radiation”, a process that can efficiently
transmit energy through an electro optical
device in the form of a concentrated beam of
light.

BASIC PRINCIPLE
• When an atom of a substance in an excited state
undergoes a spontaneous decay it emits a photon.
• In laser that photon interacts with another
energized atom and stimulates the emission of
another photon with precisely the same wave
characteristics, further stimulates atoms and
produce additional identical photons.

Teruo Matsumoto

Colour atlas laser surg, Ishiyaku Euro America, Inc Publ.,)

• The light waves generated in the way are reflected
back and forth repeatedly between mirrors set on
either end of the laser chamber.
• The laser beam leaves, the chamber through a
hole at center of the partially reflective mirror.


BASIC LASER PROPERTIES
Laser light has 3 basic properties:
• It consists almost exclusively of one wave
length advancing in the same direction
(coherence)
• The light is traveling in a parallel plane with
no divergence. (collimation)
• All laser energy intensifies at one wavelength
and barely deviates (Monochromaticity).

CLASSIFICATION
According to
•

Physical Construction of the laser
Gases – Excimer (is that the laser are generated
from gas mixture of halogens
(F, Cl, Br) and rare gases.
- Argon
- Krypton, CO2
Solids

Liquid

- NaCl
YAG
- Ruby
- Rhodamine dye

- Teruo Matsumoto


• The types of medium which undergoes lasing
Eg:

- Erbium
- Yttrium
- Aluminum
- Garnet

• The degree of hazard to the skin (or) eye
following inadvertent exposure.

COMMON LASER TYPES USED IN
DENTISTRY
• Argon
• Helium
• Diode
• Nd: YAG
• Er: Cr: YSGG
• Er: YAG
• CO2

( L J Walsh, Australian dental journal 2003)

• The main applications for lasers in orthodontics
are for
- Laser scanning
- Holography
- Soft tissue lasers
- Hard tissue lasers
(Robert Harry, BJO1994)

LASER SCANNING
• This is a method of three dimensional image
capture which has been described by Arridge et
al (1985) and further developed by Moss et al
(1988).
• A low power, Helium – Neon, type II laser is
fanned across subject face or body and the
reflected beam is captured by a video camera.

- (Robert Harry, BJO1994)

• The information is then analyzed by specially
developed software and stored on a computer.
• The image can then be viewed on a computer
screen and rotated in any direction so that all the
individual features can be viewed.
• Super imposition of serial scans is now possible
and therefore longitudinal assessment of facial
growth or the results of facial surgery can be
assessed.


Three dimensional dental cast analyzing system
using laser scanning
(Tajayuki Kuroda et al. Am.J.Ortho 1996, Br.J Ortho 1994)

• The three dimensional dental cast analyzing
system with laser scanning
• Its preliminary clinical application is that the
system is composed of a measuring device with
a slit ray laser projector and two sets of coupled
charged devised video cameras, an image
processing unit.
• A 16 bit personal computer as a controller and

an engineering workstation as a post processor.

• The dental cast is projected and scanned with a
slit ray beam, the coordinates of the target are
determined with an image processor.
• Triangulation
is applied to determine the
location of each point.
• Generation of 3-D graphics of a dental cast takes
40 minute.
• The measurement error is less than 0.5 mm.
• Beside the conventional linear and angular
measurement of the dental cast is able to
demonstrate the size of the palatal surface area
and the volume of the oral cavity.

• The advantage of this system is that it facilitates
the other wise complicated and time consuming
mock surgery necessary for treatment planning
in orthognathic surgery.
• In

orthodontic

treatment

the

information

obtained from the dental cast is invaluable not
only for the diagnosis, however it has been
difficult

to obtain quantitative information

regarding probable changes in volume of the
oral cavity of the treatment. It is the set of
treatment goal.


HOLOGRAPHY
• Holographs can be used for three dimensional
record collection and stress analysis in hard
tissue subjected to various loading forces.
• This is also used for three dimensional facial
image recording, their main application in terms
of record collection is as a substitute for
orthodontic study casts. (Robert Harry, BJO1994)

• Holograms

are

about

the

same

size

as

radiographs or photographs and are resistant to
damage.
• A special camera is required which will take
white laser light reflection holograms from study
casts.


• Disadvantage: Lack of familiarity with the hologram
and the fact that some views of the teeth were
poor, particularly in assessing overbite and
actually measuring the over jet.
• Because of above disadvantage, an interesting
development is, the use of ‘reverse’ holography.
• (ie). A system might be developed that could take
holograms directly of the patient teeth, without
having to use study casts or dental impression at
all.


SOFT & HARD TISSUE APPLICATION
• CO2 lasers have been used in oral techniques for
operating on both hard and soft tissue (Shoji et
al 1985).
• Drawback - due to the wave length of the
emitted light (10.6 microns), the guiding system
has to consists of a number of joined arms with
mirrors to reflectwww.indiandentalacademy.com
the beam

• This

makes

this

type

of

unit

extremely

unyielding and because this wavelength is
largely absorbed by water molecules.
• It will cut many tissue, both hard and soft and
has to be used with caution.


Nd:YAG (Neodymium: Yttrium – Aluminium –
Garnet) laser.
• It was developed by Ceusic in 1964
• A wave length of 1.06 microns and can be
transmitted via a fibre optic cable to handpieces
which resemble conventional dental instrument
in size and shape.
• It is possible to cut soft tissues relatively
painlessly.


• Unlike the Co2 laser, Nd:YAG laser beam
because

of its near infrared

range can be

delivered through a pure optical fiber.
• The laser beam is delivered through a silica
fiber 320 µm in diameter.
• Nd: YAG laser uses a helium - neon (red) laser
for aiming the beam, it can be delivered either
contact or non contact system.

• The soft tissue surgery can be performed
without the need for local anesthetic which may
be useful for removing opercula from partly
erupted teeth.
• This type of laser cannot be used on bone
because

it

will

destroy

bone

cells

at

a

considerable depth, producing necrosis.
• Eg: not suitable for
fraenectomies.

mucoperiosteal flaps,


• It can be used for exposure of teeth where no
flap is raised
• The use of soft, non-cutting laser has been
suggested for various dental applications
including the desensitization of hypersensitive
dentine, to aid the healing of dry sockets
promote healing and reduce the discomfort
associated with aphthous ulcer.

• Disadvantage:
associated

One

with

of

the

the

early

application

problems
of

laser

technology to dental hard tissue was that laser
irradiation of teeth generate too much heat. A
temp rise of 6° C may result in an invisible pulpal
reaction which can lead to pulpal necrosis.


TISSUE REACTION
• Each tissue type has a specific energy absorption
pattern.
• Laser absorbed by tissues and laser are strictly
frequency and tissue dependent.
• Because of the limitations of laser physics &
tissue biophysics, one laser cannot be applied to
all the various tissue types with complete
efficacy.

• When laser light interacts with oral tissue, it is
either

absorbed,

partially

transmitted,

scattered, or back scattered.
• Only the absorbed laser light has an effect on
tissues.
• Tissue absorption is low with Nd:YAG lasers;
has optical scattering with deeper and uniform
penetration within tissue.
• CO2 lasers have the most absorption, with
basically negligible scattering followed by the
argon laser.


HARD TISSUE APPLICATIONS
• Nd: YAG

laser cannot be used on bone

because of the resultant necrosis, it has been
used for a variety of other dental procedures.
• These include cavity preparation,(removal of
soft

caries)

endodontics

(to

access

the

extremely fine root canals) and as a substitute
for acid etching www.indiandentalacademy.com
of teeth.

Laser tooth whitening:
• The whitening effect with the use of argon
laser is achieved by a chemical oxidation
process. once the laser energy is applied, the
hydrogen peroxide (H2O2) breaks down to water
(H2O)

and

a

free

oxygen

radical,

which

combines with and thus removes the stains
molecule.


Laser etching of enamel for direct bonding and with an
Er: YAG and Er, Cr; YSGG, hydrokinetic laser system
(Bor-Shiunn Lee et al. AO 2003, AJO 2002)
• Irradiation of enamel with laser energy changes the
physical and chemical characteristics of the enamel
surface and these alteration hold for the conditioning
enamel for bonding procedure ,
• Normal minimum time etching (orthophosphoric acid) 15 seconds, followed by
15 – 30 seconds, washing
(30-45 sec)
Laser etching and drying

5 – 10 sec for drying
20 – 25 seconds

• Allowing immediate placement of bracket saving 10 to 50
seconds per tooth. www.indiandentalacademy.com

Curing with laser
• Curing with lasers is possible and comparable to the
conventional curing lights.Wavelengths required for light
curing ranges from400-800Nm.
• Photo sensitivity of camphoroquinone, the photo activator
in almost all the composite resin restorative materials can
be activated by laser light .
• Thus the laser beam can activate, the polymerization like
visible light curing sources.

LASER CURING
• The wavelengths produced by argon lasers
include a 488µ segment, that is an exact match
with photo sensitivity of camphoroquinone, the
photo activator in almost all the composite
resin restorative materials.
• The laser beam activates the polymerization
much faster than a visible curing source.
(Laser in pediatricswww.indiandentalacademy.com dentistry)
and adolescent

• Within 10 sec for filled resins and 5 sec for unfilled
resins there is significant time savings especially
with

layered

resin

placement

the

physical

properties are also improved with the laser curing,
dimetral strength, surface hardness readings, and
bond strengths all are enhanced.

• Shrinkage is similar but occurs more quickly.


• Layering management is recommended. Because
the filler particles in composite resins block the
penetration of curing lights, both laser and
visible light curing, the recommended 2-mm
depth of curing holds for both methods.


Mark Kurchak et al in 1997 (JCO)
study shows region laser produce wavelength of
457-514 Nm and in a peak of 488 Nm, can be used
as curing light.

Argon laser have been found to cause no
damage to pulp or enamel levels of 1.6
to 6 watts.

Sergio J. Weisberger et al in 1997 (A.O)
study shows there is no difference noted in
bonded system between laser and light cured
brackets.
• The laser cured specimens exhibited a
significantly higher incidence of cohesive failure.
• Chemically cured bonding system may be
superior to laser or light cured bonding system
because of then decreased risk of enamel
damage.

• Travis Q Talbot et al., (2000) compared the effect
of argon laser energy level on curing visible light
cure orthodontic adhesive system and concluded
that there was no apparent effect with increasing
energy level from 200 mw to 300 mw and 10
seconds. Argon laser bonding produced bond
strength comparable to 40 seconds conventional
visible light curing. AJO DO 2000 .


• Lalani. N et al., (2000) conducted a study to
determine the efficiency of an argon laser in
polymerizing a light-cure orthodontic adhesive
and concluded that a 5-second cure using an
argon laser produced bond failure loads
comparable to those obtained after 40 seconds
of conventional light cure, with less than half
the frequency of enamel fracture at debond.
Angle Orthod 2000


LASER DE-BONDING OF CERAMIC
BRACKETS
(Ezz Azzeh & Paul J. Feldon et al. AO 2003 AJO
1992, 1997)
• Laser energy degrades the adhesive resin used to
bond brackets consequently, lower forces can be
used

than

when

mechanical

debonding

is

performed, reducing the risk of enamel damage.
• The heat produced by some laser can damage vital
pulp, selecting the appropriate laser, resin and
bracket combination can minimize risks and make
debonding more efficient.

Mechanism of laser debonding
(According to Tocchio et al.AJO 2003
Laser energy can degrade the adhesive resin by 3
methods
• Thermal softening
• Thermal ablation
• Photo ablations
Thermal softening - occur when the laser heats
the bonding agents until it softens.

• Thermal ablation - occurs when heating is fast
enough raise the temp of the resin into its
vaporization range before debonding by thermal
softening occur.
• Photo ablations - occur when high energy laser
light interacts with the adhesive material and the
energy level of the bonds b/w the adhesive resin
atom rapidly rises above their dissociation energy
levels resulting in decomposition of material. {CO 2
YAG lasers}


• Time span for debonding in the laser less than 4
second (2.9 ± 0.9 seconds)
• Debonding force is reduced in laser. Risk of
enamel damage and bracket fracture is reduced.
• No pulpal injuring occur when the max intra pulpal
temp rise stayed below 2°C.
• The effect of lasting time on intrapulpal temp
increased and tensile debonding force with a 18
watt carbondioxide laser.
• Ceramic bracket can also be debonded by laser
debonding pliers. www.indiandentalacademy.com

Surface roughness of orthodontic arch
wire via laser specular reflectance
(Robert P.Kusy et al EJO. & AJO 1998)
• The

surface

roughness

of

orthodontic

archwires is an essential factor that determines
the

effectiveness

of

arch

guided

tooth

movement
• Using the non-destructive technique of atomic
force

microscopy

(AFM),

laser

specular

reflectance and profilometry, the roughness of
wire is measured.

• In

orthodontic,

surface

archwires

additionally

aesthetics

of

the

roughness

may

appliance

of

affect

the

and

the

performance of sliding mechanics but its
influence on the co-efficient of friction
• Guiding a tooth along the archwire results in
tipping and rotating of the tooth and in a
contact between the bracket and the guiding
wire.


• Consequently frictional forces may reduce the
orthodontic force by 50% or more
• The loss due to friction depends on a larger
number of mechanical parameters of the
combination of arch wire and brackets being
used
• Above all the material parameters of the
guiding archwire are dominant factors

EFFECT OF LOW POWER LASER IRRADIATION
ON BONE REGENERATION IN MID PALATAL
SUTURE DURING EXPANSION IN RATS
(Shiro Saito and Noriyoshi Shimizu. AJO, 1997)
•The low power laser irradiation can accelerate
bone regeneration, in mid palatal suture during
rapid palatal expansion and that this effect is
dependent not only on the total laser irradiation
dosage but also on the timing and frequency of
irradiation.


• Laser therapy may be of therapeutic benefit in
inhibiting relapse and shortening the retention
period

through

acceleration

of

bone

regeneration in the mid palatal suture.
• Low power laser source, gallium- aluminium
arsenide diode laser device was used.


INTRA ORAL LASER MICROWELDING OF ORTHODONTIC
APPLICANCES
(Leich E. Colby & Richard R. Bevis. AJO, 1978)

• A common task for industrial lasers is the
fusion of two metals without the aid of
soldering agents.
• It was not surprising to find such an obviously
practical process the center of more in dental
research.
• Shifting the emphasis from intraoral use to
laboratory procedures.
• It is clearly documented that laser welding is
stronger than solder joints of comparable size.

• This factor plus the low thermal distortion
which accompanies the welding process makes
the lab welding of prostheses very attractive.
• The work has been carried out safely.
• The rapid and repeatable action of the pulsed
neodymium laser micro welder used in
simulating intra oral welding strongly suggests
that safe intra oral welding can be done with
proper controls on a routine basis with no
damage to hard tissue.

LASER FLUORESCENCE STUDY OF WHITE
SPOT LESION IN ORTHODONTIC PATIENT
(Susan Al-Khateeb et al. AJO, 1998)
• Enamel

demineralization

with

white

spot

formation on buccal surface of teeth is a
relatively common side effect from orthodontic
treatment with fixed appliance.
• Enamel decalcification or formation of white spot
lesion during orthodontic treatment presents of
significant problem in orthodontic patients.

•Fixed orthodontic appliances complicate the
removal of food debris that result in the
accumulation of plaque.
•There

will

be

increase

in

number

of

streptococcus mutans and lactobacillus species
in oral cavity after placement of fixed orthodontic
appliances.
•Plaque bacteria produce organic acids that

cause the dissolution of calcium and phosphate

ions from the enamel surface, this dissolution
can cause white spots (or) carious lesions to
form in 4 weeks.
• There is a evidence that suggests that, such
small area of superficial enamel demineralization
may remineralize.
•The QLF method (quantitative version of laser
fluorescence) method is to monitor longitudinally
small changes in incipient enamel lesions.

•This method is useful for investigation of the effect
of preventive and therapeutic measures in various
cariogenic risk groups.
•When enamel demineralization take place, minerals
will be replaced mainly by water, causing a
decrease in the light path in the tooth substance.
•QLF test for assessment of mineral changes in
artificial lesions during demineralization.

• This will result in reduction of light absorption
by enamel because fluorescence is a result of
absorption, the intensity of fluorescence will
decrease in demineralized region of the enamel
which appear darker than the sound tooth
structure.


• The white spot lesions formed around the fixed
orthodontic appliance recover partly over a
relatively long period of time.
• To prevent (or) reduce enamel decalcification
during orthodontic treatment.Including fluoride
application,

hygiene

regimens,

modified

appliances designs, the use of Argon laser in
dentistry has been proposed for polymerization
of resin materials and bleaching of enamel.

ii. Photoactivated dye disinfection using lasers
• This technique shown to be effective for killing
bacteria

in

complex

biofilms,

such

as

subgingival plaque, which are resistant to the
action of anti microbial agents.
• It can be used effectively in carious lesion,
since visible red light transmits well across
dentine and can be specific by tagging the dye
with monoclonalwww.indiandentalacademy.com
antibodies.

• This dye can be applied for killing gram
positive and negative bacteria, fungi and
viruses.
Photodynamic therapy
• More powerful laser – initiated photochemical
reaction is photodynamic therapy, which has
been

employed

in

the

treatment

of

malignancies of the oral mucous, particularly
multi focal squamous cell carcinoma.

– Laser procedures on dental hard tissue
• Er-based dental lasers can be also used to
remove composite resin and glass-ionomer
cement restorations and to etch tooth surface.
• These laser system can be used for effective
caries removal and cavity preparation without
significant thermal effects collateral damage to
tooth structure (or) patient discomfort.

Soft tissue laser procedures
• Which can be performed with lasers by
reducing bleeding in intra operatively and less
pain post operatively compared it conventional
techniques such as electro surgery.


LASER SAFETY
• Eye protection is important for the operator,
staff, and the patient. Different lasers require
different safety glasses.
•

CO2 laser protection can be afforded with
clear safety glasses, such as those that are
normally worn during dental procedures.

• Clear safety glasses are worn by the patient as
well, and as a back up measure, wet gauze
sponges are placed over the patient eyes.

• For protection from Nd:YAG laser energy, both
the doctor and staff need to wear green safety
glasses. For the argon laser, orange safety
glasses.
• Instruments that are highly reflective or that
have mirrored surfaces should be avoided as
there could be reflection of the laser beam.

CONCLUSION
• Understanding the various uses of lasers ,is
simply to accept, the cutting edge of present day
orthodontics.
• From the daily bonding procedure including
surface

preparation,

bonding,

debonding,

scalpel-less cutting,tooth bleaching
• Record maintenance ,cast analysis in 3-D, can
be done using lasers.

• With its numerous uses in dentistry and its ever
growing uses in orthodontics,the safety
precautions,and its disadvantages should also be
kept in mind.
• Future of painless & faster dentistry, in an
orthodontics practice, can all be achieved, to the
one that understands the use of lasers in the field
of orthodontics.
To conclude, lasers are our tools of tomorrow,
only if we are ready with the knowledge of it
today !*

Leader in continuing dental education


Lasers in orthodontics /certified fixed orthodontic courses by Indian dental academy

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