Lasers in operative dentistry

Lasers in
Operative
Dentistry
Presented by
Dr. Himani Thawale
JR-III

CONTENT
• Introduction
• History of lasers
• Components of lasers
• Types of lasers
• Application of lasers in operative
dentistry
• Hazards associated with lasers
• Safety precautions
• Recent advances
• Conclusion
• References

• Conventional procedures of cavity preparation with
low and high-speed handpieces produce noise,
uncomfortable vibrations and stress for patients.
• Lasers were introduced with a hope to overcome the
drawbacks posed by the conventional dental
procedures.
INTRODUCTION
Carmen dm Todea. Laser applications in
conservative dentistry. TMJ; 20014:54:4:392-405

dental laser as an alternative treatment tool at time of
coronavirus pandemic
Dental Laser As An Alternative Treatment Tool At
Time Of Coronavirus Pandemic
• Dental lasers generate significantly reduced levels of aerosols and
droplets compared to high speed dental headpieces and ultrasonic
instruments.
• As well, with dental lasers will be no or reduced need for anesthesia
and minimal bleeding following surgical dental procedures.
• With the aforementioned qualities of dental lasers, the risk of infection
with COVID-19 and other viruses/bacteria will, potentially, be

Laser is an acronym for
Light
Amplification by
Stimulated
Emission of
Radiation.
Laser is a device that transforms light of various frequencies into a chromatic
radiation in the visible, infrared and ultraviolet regions with all the waves in
phase, capable of mobilizing immense heat and power when focused at close
range.
DEFINITION
Applications of Light Amplification by Stimulated Emission of Radiation (Lasers) for Restorative Dentistry S hariq Najeeb,
Zohaib Khurshid ,Muhammad Sohail Z , Syed Ajlal . M ed Princ Pract 2016;25:201–211 D OI: 10.1159/000443144

A device that concentrates high energies into an intense narrow beam of nondivergent
monochromatic electromagnetic radiation; used in surgery, cauterization and for a variety
of diagnostic purposes; various types available depending on the laser wavelength, probe
characteristics and the laser energy; types include the carbon dioxide, Nd:YAG, argon and
xenon chloride excimer lasers.
According to Glossary of Endodontic

History
1917
•Albert Einstein-Proposed the theory of
wavelength
1953
• Charles Townes-Invented first-ever microwave
amplification by the stimulated emission of radiation
(MASER)
1960
• Theodore Maiman - developed a ruby laser, made of
aluminum oxide, that emitted a deep red-colored beam.
1960
•Javan et al.- Invented the first gas laser
Applications of Light Amplification by Stimulated Emission of Radiation (Lasers) for Restorative Dentistry S hariq Najeeb, Zohaib Khurshid
,Muhammad Sohail Z , Syed Ajlal . M ed Princ Pract 2016;25:201–211 D OI: 10.1159/000443144

1961
• Snitzer – developed Neodymium laser
1966
• Lobene et al - used co2 lasers in dentistry
1974
• Yamamota et al - used Nd:YAG lasers in
prevention of caries
1989
• Er:YAG laser – was used on the tooth.

LASER DEVICE- Parts of laser
Applications of Light Amplification by Stimulated Emission of Radiation (Lasers) for Restorative Dentistry S hariq Najeeb, Zohaib Khurshid ,Muhammad Sohail Z , Syed Ajlal . M ed Princ
Pract 2016;25:201–211 D OI: 10.1159/000443144

PROPERTIES OF LASER
The characteristics of laser light:

Soft tissue lasers generally utilize diodes.
Clinical applications includes:
healing of localized osteitis,
healing of aphthous ulcers,
reduction of pain and
treatment of gingivitis.
Soft tissue lasers in clinical use are:
1. Helium-Neon (He-N) at 632.8 nm
2. Gallium-Arsenide (Ga-As) at 830 nm
Based on level of energy emission:
Soft Tissue
Laser
Hard tissue lasers (surgical) can cut both soft
and hard tissues.
Commonly used hard lasers are:
1. Argon lasers (Ar) at 488 to 514 nm
2. Carbondioxide lasers (CO2) at 10.6 micro-
meter
3. Neodymium-doped Yttrium Aluminium
Garnet
(Nd:YAG) at 1.064 micrometer.
4. Neodymiumm Yttrium-Aluminum-
Perovskite
(Nd:YAP) at 1,340 nm
Hard tissue laser

UV Light
a. Spectrum is 100 nm – 400 nm
b. Use: Not used in dentistry.
Visible Light
a. Spectrum is 400 nm – 750 nm
b. Use: Most commonly used in dentistry
Infrared light
a) Spectrum is 750 nm – 10000nm
b) Use: Most dental lasers are in this
spectrum.
Classification of laser based on its spectrum:

CLASSIFICATION OF LASER
Based on source and wavelength
Art and science of operative dentistry, Sturdevants– 5th edition
15
TYPE SOURCE WAVELENGTH (nm) MODE
Infrar
ed
CO2 10,600 Continuous
Er,Cr:YSGG 2780 Continuous, pulsed
Er:YAG 2940 Continuous, pulsed
Ho:YAG 2060 Pulsed
Nd:YAG 1064 Pulsed, continuous
Diode laser 812;980 Pulsed, continuous
Visibl
e
He-Ne 633 Continuous
KTP 532 Continuous
Argon 488,514 Continuous
Ultra
violet
(Exci
mer)
XeF 351 Pulsed
XeCl 308 Pulsed
KrF 248 Pulsed

Classification Of Laser According To The
Material Used:
Gas lasers
Argon
Carbon-dioxide
Liquid
Dye laser
Solid:
• Nd:YAG
• Er: YAG
• Diode
Semiconductor
Hybrid silicon
laser
Excimers
Argon-fluoride
Krypton-fluoride
Xenon-fluoridesers

Class I- Safe
under normal
conditions
Class III (b)-
Denotes laser
system that is
hazardous.
Class II- Low
power visible
laser system
Class IV-
Hazardous
Class III(a)-
denotes laser
system having
caution label
ANSI has classified lasers on their safety
parameters.

18
V. Based on pulsing:
Pulsed - The beam is not continuous, i.e. of short duration.
Non- pulsed - The beam is continuous and of fixed duration.
VI. Mode of action
• Contact mode (focused or defocused) - Ho:YAG ; Nd: YAG
• Non-contact mode (focused or defocused) - CO2

Photo-
thermal
Ablation
Photo-
mechanical
ablation
Photo-
chemical
effects
Mechanism Of Action Of Lasers

LASERS USED IN OPERATIVE DENTISTRY

CO2 Laser -10600nm
Nd:YAG Laser- 1064nm
Argon Laser-
488-514nm
Er:YAG Laser-
2940nm
Excimers

Caries detection
Caries Removal & Cavity
preparation
Caries Prevention
Restoration removal
Etching of enamel & Dentin &
Photopolymerization
Treatment of Dentinal Hypersensitivity
Bleaching
Clinical
Applications Of
Laser
In Operative
Dentistry

Lasers used for caries detection:
 Quantitative Laser Fluorescence(QLF)
 Infrared Laser Fluorescence Technique using
DIAGNOdent.
 Optical Coherence tomography
Wadhawan R, Solanki G, Bhandari A, et al: Role of laser therapy in

Quantitative Laser Fluorescence(QLF)
Used for detection of smooth surface and fissure caries at an early stage.
In this method tooth is illuminated by a beam
of blue-green light(448nm) from argon laser.
After exposure, enamel produces yellow
flouorescence.
These florescent images are captured using a
color video camera & analysed in software
Demineralized area appears- darker images
against the florescent background of sound
enamel.

Demineralized tissues absorb dyes like fluorol TGA, Sodium
Fluorescence.
Also referred to as dye enhanced laser fluorescence.

1) Convenient &
Relatively Fast Method.
2) Natural Lesions with
diameter of less than
1.0mm & depth of 5-
10mm have been detected.
3) Suitable for quantifying
mineral loss around
different restoration.
1) Only discerns enamel
demineralization
2) Potential for operator bias as
it relies upon a subjective
analysis of a stored tooth
image.
3) Inability to detect
interproximal lesions.
4) Limited to measurement of
enamel lesions.
Advantages
Disadvantages
dentistry: a review. Int J Biomed Res 2014; 5: 153–157.

• Diagnodent, a 655 nm diode laser, aids in the detection
of incipient caries is called laser-induced fluorescence.
• When the laser irradiates the tooth, the light is
absorbed by organic and inorganic substances present
in the dental tissues, as well as by metabolites such as
bacterial porphyrins.
• These porphyrins showed some fluorescence after
excitation by red light.

• Since bacteria are present in the carious lesions, carious tissue exhibits
more fluorescence as compared to the healthy tissue which distinguish
between the carious and sound tooth structure.
29Wadhawan R, Solanki G, Bhandari A, et al: Role of laser therapy in

1. 90% success to diagnose pit and fissure caries.
2. High Reproducibility & Reliability.
3. Readily Transportable
4. Non invasive and painless
5. Safe, no X RAY Exposure
6. Promotes Minimally invasive treatment.
ADVANTAGES

Disadvantages
• False result with presence of plaque and calculus
• Cant distinguish between hypo mineralized and carious
structure.
• Readings do not relate to amount of dentinal decay.
• Limited accessibility to the embrasure prevents accurate reading
of interproximal surfaces

• Composite resins can fluoresce, prompting elevated readings; hence the
DIAGNOdent should not be used on these materials.
• Caries underneath amalgam restorations is measured accurately only if there
is caries at the margin, however if the caries is under the floor of the amalgam
the reading will not be accurate.
• If used in deep preparations, in close proximity to the pulp; elevated values
may be obtained, possibly resulting from fluorescence of underlying pulp and
not necessarily as a result of caries
Barcellos DC, Santos VMM, Niu L, et al: Repair of composites: effect of laser and different
surface treatments. Int J Adhes Adhes 2015; 59: 1–6.

• Chaza Kouchaji, 2013 Results showed a strong relationship between examination
with the diagnodent and visual inspection.
• Diagnodent’s sensitivity and specificity were 97% and 52%, respectively,
indicating that the laser fluorescence diagnodent pen is a reproducible and
accurate diagnostic tool that may be very helpful in conjunction with visual
examination in the detection of occlusal caries in permanent molars in children.

Optical Coherence Tomography
• Detect & diagnose very early stages of disease in teeth.
• Early demineralization, remineralization, recurrent caries, tooth and
restorative failures can be imaged and monitored in real time on computer
monitor.
• OCT provide cross sectional “optical- biopsy” of tissue upto 3mm in depth
from the surface. The image has an axial resolution of 1-10u.Barcellos DC, Santos VMM, Niu L, et al: Repair of composites: effect of laser and different

• Laser light of wavelength such as 840 to 1310nm is used.
• OCT shows sound enamel causes high intensity back scattering at tooth surface
that decreases rapidly with depth.
• In contrast, incipient lesions cause higher light back scattering at tooth surface
and subsurface indicative of porosity caused by demineralization.

• Bright zone indicates the increased light scattering in porous demineralized tissue (blue
arrow)
• A strong reflection penetrating along the DEJ indicates the lesion is “cavitated” (red arrow)

• Laboratory studies have indicated that enamel surfaces exposed to laser irradiation
are more acid resistant than non-laser treated surfaces (Watanabe et al., 2001; Arimoto
et al., 2001).
• It is believed that laser irradiation of dental hard tissues modifies the calcium to
phosphate ratio, reduces the carbonate to phosphorous ratio and leads to the
formation of more stable and less acid soluble compounds further reducing
susceptibility to acid attack and caries.

• The degree of protection against caries progression provided by the one-
time initial laser treatment was reported to be comparable to daily
fluoride treatment by a fluoride dentifrice (Featherstone, 2000).
• The threshold pH for enamel dissolution was reportedly lowered from
5.5 to 4.8 and the hard tooth structure was four times more resistance to
acid dissolution.
• Commonly used lasers for this purpose are
CO2 Laser
Nd:YAG Laser
Excimers Laser

CARBON DIOXIDE LASER
Ideally suitable as
- Long wavelength can easily absorbed by enamel.(10.6um)
- Only shallow depth is affected thereby minimizing harmful effects on
pulp.
Nd:YAG LASER
• Used as pit and fissure sealant.
• Removes inorganic and organic debris in pit and fissure without injuring
the surrounding healthy enamel.
• The laser effect would weld hydroxyl apatite crystals blocking the
pits/fissures.Barcellos DC, Santos VMM, Niu L, et al: Repair of composites: effect of laser and different

• Cavity preparation by using lasers has been an area
of major research interest ever since lasers were
initially developed in the early 1960s.
• At present, several laser types with similar
wavelengths in the middle infrared region of the
electromagnetic spectrum are being used commonly
for cavity preparation and caries removal.
Caries
Removal
Buchalla W, Attin T: External bleaching therapy with activation by heat,

Lasers cut at a point of their tip
To be used with up and down motion
Rough edges that need hand instruments
such as excavators to carry away the
ablation products
Removes smear layer
Considered safe in cases of unexpected
patient movement
Burs produce abrasive cutting from their
sides and are also cut at the end
Side brushing action is also used along
with end cutting
Produces smooth edges
Produces a smear layer
Considered unsafe in cases of
unexpected patient movement
Laser assisted cavity
preparation
Conventional cavity
preparation
Buchalla W, Attin T: External bleaching therapy with activation by heat, light

Lasers commonly used for cavity preparation are:
- CO2 LASER
- Nd:YAG Laser
- Er:YAG Laser
- Er, CR: YSGG Laser

• The Er:YAG Laser has shown more promising results.
• It is absorbed by water and hydroxyapatite, which partially accounts for its
efficiency in cutting enamel and dentin.
• There should be at least 1mm of clearance between the end of the laser tip
and the tooth structure.
Frequency range: 2 to 20 hz
Pulse energies : 50 to 1000 mj
Power: 1-8 w (depending on the type of tissue.)

ADVANTAGES
• Laser Induced Analgesia (No Need For Local Anesthesia)
• Less Post-operative sensitivity because dentin may be fused.
• Access to subgingival caries is greatly improved since lasers vaporize
gingival tissues.
• Due to alterations of surface structure, the lased tooth becomes resistant to
decay. In case of root caries, placement of restorative material may not be
necessary after laser application.

Drawbacks:-
1) Patient feels slightly warm sensation.
2) Usually Lasers produce too much heat, melt the enamel and
damage the pulp.
3) It has been observed that uncooled laser ablation of enamel can
lead to a temperature rise as high as 300–800 ° C that may lead
to permanent damage to the dental pulp

• A systematic review by Jacobsen et al evaluated randomized clinical trials
that studied the efficacy of erbium lasers. It was suggested that lasers are as
effective as conventional rotatory instruments in removing dental caries.
• However, thermal injury to the dental pulp and the longevity of the
restorations could not be assessed due to a lack of follow-up. Patients
preferred laser ablation over conventional dental burs for being more
comfortable.

• Precisely cut hard materials including tooth enamel and dentin
with less temperature rise than conventional lasers.
• Lasers have also been used to increase the adhesion of bonding
agents with dentin by increasing the wettability.
Cavity Preparation Using Ultra-Short Pulsed Lasers
Lasers in Conservative Dentistry: An Overview, GauranGi KaKodKar, ida de noronha de ataide, rajdeep
pavasKar Journal of Clinical and Diagnostic Research. 2012 May (Suppl-1), Vol-6(3):533-536

• In a recent study Nd:VO4, USPLs were evaluated in terms of ablation rate and
temperature changes for ablating dental hard tissues using radiation of variable
wavelengths (355, 532, 1,045 and 1,064 nm).
• In general, USPLs demonstrated less temperature fluctuation and better ablation
rate compared to erbium lasers.

Restoration removal
• The Er: YAG laser is capable of removing cement, composite resin and glass
ionomer (Dostalova et al., 1998; Gimbel, 2000).
• Lasers should not be used to ablate amalgam restorations.
• The Er: YAG laser is incapable of removing gold crowns, cast restorations and
ceramic materials (Keller et al., 1998).
• USPLs could be used an alternative conservative means to remove restorative
materials so as to retain the protective dentin as much as possible.

• Laser etching has been evaluated as an alternative to the acid etching of
enamel and dentine.
• Lasers used for etching of enamel are
- CO2 Laser
- Nd:YAG Laser
- Er:YAG Laser
Etching of Enamel & Dentin With Lasers
Thukral S. Laser Etching..Solaze. J Las dent 2007;1(1)14-16.

• The Er:YAG laser produces micro-explosions during hard tissue ablation that
result in microscopic and macroscopic irregularities.
• These micro-irregularities make the enamel surface microretentive and they
may offer a mechanism of adhesion without acid-etching.
• Dye penetration done for laser treated cavities showed irregular cavity surface
with the use of Er:YAG thus enhancing the adhesion and sealing.
Thukral S. Laser Etching..Solaze. J Las dent 2007;1(1)14-16.

• Etching with dentin, results in carbonization or charging due to
its high organic content.
• Moreover, the dentin structure is changed. It shows presence of
fungi form projections and there is localized melting on dentinal
surface causing sealing of dentinal tubules thereby reducing
micro-leakage and enhancing the bond of final composite
restoration.

Upendra et al 2014,evaluated the shear bond strength of composite
resin bonded to enamel which is pretreated using acid etchant and
Er,Cr:Ysgg and he concluded that for enamel surface, mean shear bond
strength of bonded composite obtained after laser etching were
significantly lower than those obtained after acid etching.

• In the laser-etched enamel preparations, the high prevalence of cohesive tooth fractures suggests that
disruption as a result of "micro-explosions weakened the enamel and gave rise to a more
heterogeneous surface than that obtained by acid etching.
• In contrast to acid etch treatment, laser etching produced extensive surface fissuring and less regular
and less homogeneous surface patterns arising from the union of different craters.
•
The physicochemical changes caused by laser etching can be expected to decrease long-term
susceptibility to acid attack and caries.

Photopolymerization Of Composite Resins

• The argon laser is one promising source, as the wavelength of the light which is
emitted by this laser is optimal for the initiation of polymerization of the
composite resins.
• The argon laser at 488nm (blue) is used.
• The argon wavelength activates camphorquinone , a photoinitiator that causes
polymerisation of the resin composites.

• The argon laser radiation also alter the surface
chemistry of both the enamel and the root surface
dentine, which reduces the probability of the
recurrent caries.
• It is used at 250+_ 50 mw/ cm2 for 5-8 seconds

Shorter
Curing
Time
Better
physical
propertie
s.
Increase
depth of
cure
Better
Polymerization
Reduced
polymerization
shrinkage.
Advantages For
Using Laser For
Photopolymerization

Treatment of Dentin Hypersensitivity

• Dentin hypersensitivity is usually secondary to a number of conditions such
as caries, gingival recession (exposed roots), tooth wear and microcracks.
• This is a very common clinical issue and lasers have been used to reduce
dentin hypersensitivity by irradiation of dental hard tissues.
for example CO2,
Er:YAG,
GaAIAs,
Nd:YAG & He-Ne

Mode of action
• He-Ne lasers alter electrical activity in the pulpal nerve cells to make them less
sensitive to pain .
• Also, it has been speculated that GaAIAs lasers depress the C-fiber conductivity
to reduce pain sensation.
• The Nd:YAG and CO 2 lasers have been thought to occlude the dentinal tubules,
thereby reduced dentin sensitivity.
• The Nd:YAG lasers can be combined with fluoride varnish to produce an effective
protocol for treating dentin hypersensitivity
Miyazaki T, Hotta Y, Kunii J, Kuriyama S, Tamak Y. A review of dental
CAD/CAM: current status and future perspectives from 20 years of

Clinical note: Er:YAG 30mJ and 10 Hz with water spray, for 2
minutes. OR
Nd:YAG , 30mJ, 10Hz for 2 minutes.
Miyazaki T, Hotta Y, Kunii J, Kuriyama S, Tamak Y. A review of dental CAD/CAM: current status and
future perspectives from 20 years of experience. Dental Materials Journal 2009; 28(1): 44-56.

• More recently, an Er:YAG laser has been used in combination with a dentin-
sensitizing agent to reduce discomfort.
• In a systematic review, randomized controlled clinical trials using various
lasers to reduce dentin hypersensitivity were analyzed. It was suggested that
Er:YAG lasers had a higher efficacy in reducing dentin sensitivity compared to
Er,Cr:YSSG and GaAIAs

Ozlem et al 2018, compared the efficiency of the glutaraldehyde-containing
agent (GCA), Nd:YAG, Er,Cr:YSGG lasers, and the combination of them on
the dentin hypersensitivity (DH) treatment and concluded that Er,
Cr:YSGG laser with or without GCA application is the most effective
modality in the treatment of DH.
The GCA and Nd:YAG laser seem have similar effects in the treatment of
DH.

• Dental erosion is caused by a series of extrinsic and intrinsic factors.
• Carbondioxide lasers have been mostly used in the prevention of erosion, due to
its
efficient interaction with hydroxyapatite crystals.
• Some studies showed partial beneficial results with the use of Nd:YAG lasers.
Treatment Of Tooth Erosion

Three dental lasers approved by Food & Drug Administration for
tooth whitening-
I) Argon Laser- 488nm
II) CO2- 10,600nm
III) GaAIAs Diode Laser- 980nm
IV) Photochemical laser whitening- Smart
Bleach
Watts A, Addy M: Tooth discolouration and staining: a
review of the literature. Br Dent J 2001;

Argon Laser
• Available in form of blue light with the wavelength of
480nm.
Results in whitened tooth surface

Co2 LASER
• Used for enhancing the effect of argon lasers.
• Laser penetrates only 0.1mm into water & H2O2,
where it gets absorbed.

Results in whitened tooth surface
Argon laser which emits blue light is used first to
activate the bleaching gel.
This blue light will be absorbed by dark stains &
become less effective as the tooth whitens
Then CO2 laser, which emits invisible infrared
energy is used to achieve deeper penetration of
energized oxygen
Resulting in deeper, more efficient tooth whitening.

Diode Laser
Semiconductor lasers with a wavelength of 980nm is usually used for
bleaching.
Different forms available are:
1) Infrared diode has wavelength of 790nm
2) Lasers with blue light emission diode wavelength of 467nm.
3) GaAIAs diode:
surface temperature- 86C with 3W.
Pulpal Temperature increases from 4.3C to 16 C.
Bleaching agent utilized 38% H2O2Watts A, Addy M: Tooth discolouration and staining: a

Limitations
• The commercial hydrogen peroxide system has the potential
to affect dental enamel because of acidic pH(5.0-6.0)
• The concentrated solution of hydrogen peroxide (30%) can
transiently reduce the microhardness of enamel and dentin.
• These lasers also result in posttreatment sensitivity.

Photochemical Laser Whitening
With the new smart bleach technique these problems do not
occur as
pH- approximately 9.5% (alkaline)
Action- Photochemical and not photothermal.
Prehydoxyl radical is produced compared to superoxide
Particularly used for bleaching tetracycline stained teeth

Tetracycli
nes
Hydroxy
apatite
Forms Red quinone
product dimethyl
amino tetracycline.
This product is relative resistant to oxidation from peroxide but can be broken
down by green light (512-540nm) & ensures complete and irreversible
belaching.

• Exposure to low-level light/lasers (GaAIAs) reduces pain and induces
tissue repair.
• A clinical study conducted on 26 patients undergoing fixed orthodontic
treatment suggested that low level light/laser therapy (LLLT) was
beneficial in alleviating pain and inflammation.
• Nevertheless, more studies are needed to ascertain whether LLLT could
be beneficial in reducing the discomfort of patients who have undergone
restorative dental procedures such as fillings and crown preparations.
Pain Control Using Low-Level Light/Laser Therapy

Laser scanners take an optical impression of a prepared tooth and the
opposing dentition and they take a bite registration to produce an
interactive three-dimensional image.
This three-dimensional laser-based imaging technology enables the dentist
to take an optical impression and to create a computer file with this data.
A virtual model is created, based on the transmitted data and a precise
master model is made. The physical model is sent to the laboratory where
a final restoration is made.
CAD/CAM Technology
Miyazaki T, Hotta Y, Kunii J, Kuriyama S, Tamak Y. A review of dental CAD/CAM: current status and future perspectives from 20
years of experience. Dental Materials Journal 2009; 28(1): 44-56.

Gingival retraction with Lasers
During impression procedures many laser systems have been used for
gingival retraction procedures.
Lasers used most commonly for this purpose are:
Argon Laser
Co2 laser

Argon laser has peak absorption in heamoglobin thus; leading itself
to provide haemostasis and efficient coagulation and vaporization of
oral tissues.
These characteristics are beneficial for retraction & haemostasis with
a 300nm.
Power setting of 1.o W continuous wave delivery fibre is inserted in
sulcus in contact with tissue.

This technique will create tissue temperatures of 90C -100C
at fibre tip which will
coagulate the small bleeding vessels,
remove sulcular epithelium and
allow for clean impression.

:
Laser
Hazards
Effect
on Eyes
Effect
on skin
& other
tissues
Environm
ental
Hazards
Electrical
Hazards

• Primary ocular injury which might result from a laser accident is retinal or coronal
damage.
• Retinal injury is possible with emission in the visible (400-780nm) and near
infrared(780-1400nm) wavelengths.
• May cause “Scotoma” – Loss of vision in the path of visual field; Blind Spot.
Effect on Eyes

The maximum permissible exposure limit for
visible lasers is less than 0.003 watts/cm for a
0.25 sec exposure.

SAFETY precautionsEYE PROTECTION
• Eyewear used specifically with particular wavelength of laser radiation to
prevent occular damage.
TYPE OF EYE SHIELD TO BE USED
• Co2 laser – clear glass or plastic
• Nd: YAG- goggles with green tint
• Argon lasers: amber-orange colors
91Applications of Light Amplification by Stimulated Emission of Radiation (Lasers) for Restorative Dentistry S hariq Najeeb, Zohaib Khurshid

• Laser induced damage to the skin and other non- target tissue can result from
thermal interaction of radiant energy with tissue proteins.
• Non thermal tissue interactions are thought to induce injury through
photochemical and photo acoustic mechanism
• These types of interaction occur with single or repetitive pulses of very short
duration (<10 µ sec).
92
TISSUE HAZARDS
Temperature elevation of 21C above normal body temperature can
produce cell destruction by denaturation of cellular enzyme and
structural proteins, which interrupts basic metabolic processes.

• During ablation of oral tissue with Co2 laser a carbonized layer of tissue
residue or char layer forms on the surface as more volatile & liquid components
within the tissue are vaporized.
• The carbon metal is strong absorber of most wavelength of laser light.
• It acts as a heat sink that transfers thermal energy to surrounding tissues; the
extent of collateral damage is therefore greatly influenced by presence of this
char layer.

The deleterious effect of lasers on enamel and dentin are:
• Enamel exhibits gross cratering from 0.1-1.1mm deep depending on amount of
energy delivered to target area.
• In deeper penetration, dark speckling of exposed dentin can be seen.
• Dentin shows shallow, irregular craters 0.1mm deep.
• Three distinct zones of dentinal destruction are
- Central zone of complete dentinal destruction.
- an immediate surrounding area of partial dentinal
destruction

with SKIN HAZARDS
SKIN PROTECTION
• A double layer of saline saturated surgical towels, sponges, or lap pads
should be used to protect all exposed skin and mucous membrane of the
patient outside the surgical field.
• Draping should be moistened time to time to prevent drying.
95
• 5-20 watts - burn injury into the skin.
• Ultraviolet laser wavelengths- may lead to skin carcinogenesis.

• Air borne Bio Hazardous materials are produced during surgical
application of lasers.
• Inhaled air borne contaminants are emitted in the form of smoke.
• Smoke - particulate matter, cellular debris, carbonaceous material
and potentially produce Bio hazardous active viruses.
ENVIRONMENTAL HAZARDS

SAFETY REQUIREMENTS FOR LASERSMOKE EVACUATION
• Two separate suction setups should be used with lasers
• First suction – smoke and steam evacuation
• Second suction – surgical suction tip for the aspiration of blood and mucous from
the operating field
• A laser warning signal should be placed outside the dental clinic.
• The laser equipment should be serviced and checked regularly.
97

ELECTRICAL HAZARDS
• Class IV surgical lasers often use very high currents and high voltage power
supplies. They are grouped as electrical shock hazards, electric fire hazards,
explosion hazards.
• Within the surgical setting, laser is exposed to conductive liquid resulting in
electrical hazard.
• To avoid an electrical hazard, the operatory must be kept dry. The control panel
and its electrical power unit should be protected from any kind of splashing.

• For operative dentistry, the use of a rubber dam must be mandatory. Special
care must be taken when choosing the dental clamp.
• According to laser safety rules, the clamp should not produce specular
reflection. Therefore, a plastic, anti-reflective, or even a sandblasted clamp must
be used.
• A less reflective clamp minimizes accidental reflection during laser irradiation.

• The rubber dam sheet color should not be dark, particularly black.
• A dark rubber dam can intensely absorb the energy produced by laser, and
this could pierce or tear the dam if it were irradiated accidentally instead of
the enamel or dentin.
• In all procedures, irrespective of the laser production, a high vacuum
aspiration system (HVAC) must be used directly pointed towards the air-
water spray or to the smoke to prevent it from spreading and risking
contamination resulting from the aerosolized particles

• According to the new biosafety standards, considering the imminent risk of
performing procedures in asymptomatic or presymptomatic patients, a face
shield must be worn by dental staff during dental procedures.
• The choice of a facial shield must take into account the space between
the shield and the eyes; it must allow the correct adaptation
of the laser safety glasses.

The safety glasses must be properly
decontaminated after each procedure.
In addition, an appropriate fitted N-95 mask
should be worn to protect the dentist from
inhaling the aerosolized particles and smoke that
escapes from the HVAC.

• Furthermore, dentists should prefer laser systems used with disposable
optic fiber tips whenever possible.
• If not available, laser handpieces must be sterilized after each use.
• New insights or scientific evidence could allow us to improve the biosafety
measures and prevent cross contamination when dealing with new
infectious diseases such as COVID-19.

RECENT ADVANCES
• The YSGG laser was used in combination with
water spray, laser beam and air (Waterlase unit;
Biolase).
• They are used for tooth preparation, caries
removal, enameloplasty.
• They have the advantage of temperature
regulation in the cutting area limiting the tissue
damage.
105

LiteTouch™ Er:YAG Laser
• Less aerosol in the dental clinic
• LiteTouch™ utilizes between 1-8 levels of air and water in which the air
pressure is as low as 8.5 psi and the water spray as low as 4 ml/min.
• In a COVID-19 emergency environment the LiteTouch™ Laser,
compared to the drill, significantly reduces aerosols and splash, through
less water flow and air pressure. The LiteTouch™ Laser disinfects and
does not spread scratch material from the oral cavity to the environment.

• With the newest LiteTouch™ feature, both air and water spray can be
completely turned off, which enables dentists to choose between 4 options
– working without air and water spray,
-working with air only (no water spray),
-working with water only (no air spray) or
- working with both water/air spray between the 8 levels
possible with the LiteTouch™.

Advantages &
Disadvantages Of Lasers

Advantages of lasers
• It is painless, bloodless that results in clean surgical field and fine
incision with precision.
• The risk of infection is reduced as a more sterilized environment
is created, as laser kills microorganisms.
• No post-operative discomfort, minimal pain and swelling,
generally doesn't require medication.

• Superior and faster healing, offers better patient compliance
• Reduced operator chair time.
• Minimal invasive cavity preparation • Bactericidal effect
• Haemostatic effect
• Increase in the success of direct and indirect pulp capping procedures
• Increased depth of penetration; makes it possible to cure thicker
increments of composite resin.

Disadvantages of laser
• Relatively high cost.
• Requires specialized training for the clinician.
• Modification of clinical technique is required.
• Harmful to eyes and skin of both clinician and patients if exposed
adversely.
• No single wavelength of laser will optimally treat all dental diseases
• Lasers don't completely eliminate the need for anesthesia.

• Lasers represent cutting edge technology for a wide range of restorative dental
applications with promising outcomes.
• Despite the remarkable benefits, lasers are not commonly used for many
procedures, particularly in developing countries.
• Many factors contribute to this, such as high cost, technique sensitivity, and lack
of training and updates among dental professionals.
CONCLUSION

• Considering recent developments as a result of continuous research and
technology advancement, a remarkable increase in the applications of lasers for
dental application is expected in the near future.
• In order to cope with the rapidly growing laser technology, it is highly
recommended that dental professionals consider updating their knowledge and
skills by means of continuous professional development, training courses and
literature updates.

References
1) Applications of Light Amplification by Stimulated Emission of Radiation (Lasers) for
Restorative Dentistry S hariq Najeeb, Zohaib Khurshid ,Muhammad Sohail Z , Syed Ajlal .
M ed Princ Pract 2016;25:201–211 D OI: 10.1159/000443144
2) Carmen dm Todea. Laser applications in conservative dentistry. TMJ; 20014:54:4:392-405
3) Wadhawan R, Solanki G, Bhandari A, et al: Role of laser therapy in dentistry: a review. Int J
Biomed
Res 2014; 5:153–157.
4)
5) Lasers in Conservative Dentistry: An Overview, GauranGi KaKodKar, ida de noronha de
ataide, rajdeep pavasKar Journal of Clinical and Diagnostic Research. 2012 May (Suppl-1), Vol-
6(3):533-536

5) Alrahabi M, Zafar MS, Ahmed N: Effects of handpiece speed on the performance of
undergraduate dental students in preclinical training. J Taibah Univ Med Sci 2015; 10: 50–
55.
6) Honkala E: Primary oral health care. Med Princ Pract 2014; 23: 17–23.
7) Hakeberg M, Berggren U, Carlsson SG: Prevalence of dental anxiety in an adult
population in a major urban area in Sweden. Community Dent Oral Epidemiol 1992; 20:
97–101.
8) Myers DR, Pashley D, Whitford GM, et al: Tissue changes induced by the absorption of
formocresol from pulpotomy sites in dogs. Pediatr Dent 1983; 5: 6–8.

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