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Introduction
Historical Perspective
Fundamentals of dental lasers
Laser Physics
Lasers in Endodontics
Operative & Aesthetic Dentistry
Dental laser safety
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L Light
A Amplification by
S Stimulated
E Emission of
R Radiation
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A laser is a device that transformslight 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 andpower when focused at close range
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Historical Perspective Early 1900s Chinese & Egyptians (Phototherapy)
1960 Theodore Maiman
1965 Dr. Leon Goldman 1970s Nd:YAG
1982 - Pick, Frame & Pecaro
1987 Meyers Portable Laser
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Stern & Sognnaes (1964) and Goldman et al(1964)were the first to investigate the potential uses of theruby laser in dentistry
They began their laser studies on hard dental tissuesby investigating the possible use of a ruby laser toreduce subsurface demineralization
The first laser use in endodontics was reported byWeichman & Johnson (1971) who attempted to seal theapical foramen in vitro by means of a high power-infrared (CO2) laser
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Fundamentals of Lasers
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Light beam is composed of packets of energy known as
PHOTONS
Ground State Atoms are normal position
Atoms are excited by an energy source and move to ahigher energy
As it reverts back to its ground state, energy is emitted Spontaneous Emission
Results without external interference and forms waves thatare in phase
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LightForm of electromagnetic energy
Laser light vs. Ordinary light
Ordinary light is usually white diffused
Sum of many colours of the visible spectrum
Laser light Monochromacity
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Coherency
Same lightwaves
All waves are inphase with oneanother(identical wave
shapes)
Collimation
Specific spatialboundaries
Low Divergence
Insures aconstant shape
& size of thebeam
Efficiency
Most usefulfeature
Providesthermal energy
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Amplification Is a part of a process that occurs inside the laser
An optical cavity is at the center of the laser device &
the core is comprised of chemical elements, moleculesor compounds Active Medium
Lasers are generically named for the material of theactive medium
Gas, Crystals or Semi-Conductors
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Gas Co2 & Argon
Solid state semi conductors : With metals like Gallium, Aluminum, Indium, Arsenic
With solid rods of garnet crystal growth with variouscombinations of Yytrium, Aluminum, Scandium,
Gallium and then doped with elements of Chromium,Neodynium or Erbium.
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The crystal or gas is excited to emit photons of acharacteristic wavelength
These ware amplified and filtered to make a coherentbeam
The effect of this energy depends on whether or notthe WL of the energy is absorbed by the surface or not
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Stimulated Emission Quantum theory of Max Planck & Neils Bohr
Smallest unit of energy
It can be absorbed by electrons, cause brief excitation
and then the quatum is released Process called asSpontaneous Emission
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Radiation Refers to light waves produced by the laser as
electromagnetic energy
EM Spectrum entire range Wavelengths
Higher Photon energy can deeply penetrate biologictissues and produce charged atoms and molecules
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All dental lasers have emission wave lengths of 0.5m
(500 nm) to 10.6m (10,600 nm)
Within the visible or invisible infrared non-ionizingEM range & emit thermal radiation
The dividing line between ionizing and non-ionizingportion is on the junction of ultraviolet and visible
violet light
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Laser consists of a lasing mediumcontained with an optical cavity, with an
external energy source to maintain apopulation inversion so that stimulated
emission of a specific wavelength can
occur, producing monochromatic,collimated and coherent beam of light
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Active medium Gas, liquid or solid
Contained in glass or ceramic tubes
Energy Electric current
Mirrors are added to each end to increase the back and
forth movement of photons
Thus increasing the stimulation of emission ofradiation
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Laser Delivery Systems Coherent, Collimated beam of laser light must be
delivered to the target tissue
Two delivery systems that are employed
Hollow Waveguide or Tube
Glass fiber optic cable
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Flexible Hollow Waveguide (Tube)
Has an interior finish mirror
Laser energy is reflected along this tube and exitsthrough a hand piece
Strikes the tissue in a non-contact manner
An accessory tip of sapphire or hollow metal can beconnected
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Glass Fiber optic cable
More flexible than waveguide
Less weight and less resistance in movement
Smaller diameter (200-600 m)
Glass component is encased in a resilient sheath
Fragile & cant be bent in sharp angles
Used in contact and non-contact mode
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Glass Fiber (Flexible) Waveguide (Tube)
Argon Er
Diode Cr:YSGG
Nd:YAG Er:YAGCO2
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Fiber Optic
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AdvantagesThinner & flexible
Higher carrying capacity
Less energy degradation
Low power consumption
Non inflammable
Light weight
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Laser Emission Modes
Dental lasers can emit light energy in 2 modalities
Constant ON
Pulsed ON/OFF
In Constant or Continuous Wave, the beam is emittedat one power
In Gated Pulse Mode, there are periodic alterations oflaser energy (Blinking light)
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This is achieved by the opening and closing of amechanical shutter in front of the beam path of acontinuous wave emission
All surgical lasers that operate in continuous wavehave this gated pulse feature
Third mode is termed Free running pulsed mode orTrue Pulsed
In this large peak of energy of laser light is emitted fora very short time
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What does the Operator control?
Level ofappliedpower
(Power
Density)
Total energyto be
delivered
(Energy
density)
Rate &Duration of
exposure
(Pulse
Repetition)
Mode ofenergy
delivery
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Lasers Used in Dentistry
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Classifications: Lasers are named according to:
Active mediumWavelength
Delivery systems
Emission modes
Tissue absorption
Clinical Application
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Classifications:I. Based on Active Mediuma) Solid State
b) Gas
c) Semiconductorsd) Excimer
e) Dye
II. Mode of action
a) Contact mode (focused or defocused) - Ho:YAG ;Nd: YAG
b) Non-contact mode (focused or defocused) - CO2
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III.Based as application
a) Soft tissue laser - Argon, Co2, diode; Nd:YAG.
b) Hard tissue laser - Er : YAG
c) Resin curing laser -Argon
IV. Based on Level of energy emission:
a) Soft lasers (Low level energy): He-Neon; Ga-Arsenide.
b) Hard lasers (High level energy): Er:YAG laser ; Nd:YAG laser.
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ArgonActive medium is Argon gas
Fiber optically delivered
Continuous wave & Gated Pulsed modes
Only laser whose light is in the visible spectrum
2 wavelengths are used:
488 nm (Blue) 514 nm (Blue-Green)
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488 nm emission is used to activate camphoroquinone
in composite resins
The beam divergence of this blue light is used in non-contact mode, produces excessive amount of photonsthus providing curing energy
More strength in cured resin when compared to
conventional blue light
Shorter curing time
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514 nm has its peak absorption in tissues containing Hb,Hemosiderin and Melanin
Has excellent hemostatic capabilities
Small diameter flexible glass fiber is used for delivery
Used in contact mode
Used in Surgical Endodontics
Acute inflammatory Periodontal conditions and highlyvascularized lesions such as Hemangioma
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Neither wavelength is absorbed by dental tissues or
water
Their poor absorption by enamel and dentin is anadvantage when used for incising and sculpting
gingival tissues
Minimal interaction and no damage to tooth surface
Both can be used for caries detection
Argon laser light illuminates the tooth, the diseasearea appears dark orange-red colored
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Diode
Is a solid active medium laser
Manufactured from semiconductor crystals usingcombinations of Al, In, Ga and Ar
Available wavelengths are 800 nm (Al) to 980 nm (In),placing them at the beginning of the infra redspectrum
Fiber optic delivered Continuous wave or Gated Pulse modes
Used in Contact mode
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Diode WL are highly absorbed by pigmented tissue anddeeply penetrating, though hemostasis is not as rapid as
with Argon laser
Poorly absorbed by tooth tissues
Soft tissue surgeries can be performed near tooth
Causes a rapid increase in temperature thus, surgical siteneeds to be air or water cooled
Diode is an excellent soft tissue surgical laser
Small size & Portable
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Diagnodent (Kavo) is a visible reddiode with a WL of 655 nm and 1milliwatt power
This red energy excitesfluorescence from carious toothstructure, which is reflected backinto a detector device in the unit
This analyses and quantifies thedegree of caries
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Neodynium:YAG (Nd:YAG)
Has a solid state active medium, which is a garnetcrystal combined with rare earth elements Yytrium &Aluminum doped with Neodynium
Wavelength is 1064 nm
Operate in free running pulsed mode with short pulsedurations
Delivered via fiber optic cable Contact mode
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Laser light is highly absorbed by melanin
Clinical applications include cutting and coagulatingsoft tissues
Energy is slightly absorbed by dental hard tissues butthere is little interaction between sound toothstructure following soft tissue surgery
Pigmented surface carious lesions can be vaporizedwithout removing the healthy surrounding enamel
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Holmium:YAG Consists of a solid crystal of Yytrium, Aluminum
Garnet sensitized with Chromium and doped withHolmium and Thulium ions
Delivered via Fiber optic cable
Free running pulsed mode
Wavelength is 2100 nm
Absorbed by water 1000 times more than Nd:YAG
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Using peak powers it can ablate hard calcified tissues
As a soft tissue laser instrument it does not react withHb or other tissue pigments
Used more in TMJ disorders and Orthopedic cases
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The Erbium Family 2 distinct lasers
Erbium Chromium: YSGG
Erbium:YAG
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Er Cr:YSGG Erbium Chromium:Yytrium Scandium Gallium Garnet
Wavelength 2780 nm
Delivered via fiber optics
Free running pulsed mode
Fiber cable diameter is much larger and requires an airor water coolant
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These 2 WLs have the highest absorption in water and
have high affinity for hydroxyapatite
The laser couples into hydroxyl radical in the apatitecrystal and into water that is bound to the crystalline
structures of tooth
Caries removal and tooth preparation can be easilycarried out
The increased water content in carious lesions allowsthe laser to preferentially interact with diseased tissue
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This is the most efficient laser for drilling and cuttingenamel as its energy is well absorbed byhydroxyapatite
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CO2 Gas active medium laser
Co2 pumped via electrical discharge
current and is present in a sealed tube
Wavelength is 10,600 nm
Delivered via hollow tube or wave guide
Continuous or Gated pulsed mode
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Well absorbed by all biological hard & soft tissues
Can easily cut and coagulate soft tissue
Has a shallow depth of penetration into tissue
The laser energy is delivered by a hollow wave guide in anon contact fashion
This WL has the highest absorption in hydroxyapatite of
any dental laser
Thus tooth must be protected during soft tissueapplication
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Its high thermal absorption makes the CO2 laser lesssuitable for cutting and drilling enamel & dentin as thedamage to the dental pulp may occur
(Ref: Seltzer & Bender, Quintessence 2002)
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Laser Tissue Interaction Laser light has four different interactions with the
target tissue
Amount of energy absorbed by the tissue depends onthe tissue characteristics such as pigmentation andwater content
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Absorbed by tissuesand results and lightenergy is convertedto thermal energy
Light travels indifferent directions,absorbed over agreater surface area
Causes less thermaleffect
Light transfers totissue withoutany interaction &injury
Little or noabsorption
No thermal effecton Tissue
Reflection Transmission
AbsorptionScattering
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Tissue Feature
Hemoglobin Absorbed by Blue & Green WLMelanin Absorbed by short wavelengths
Hydroxyapatite Absorbed by a wide range of WL
Dental structures have different amount of water content,Enamel being the least followed by Dentin, Bone, Calculus,Caries and Soft tissue
Dental lasers have a Photothermal effect
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At low temperatures below 100C, the thermal effects
denature proteins and produce hemolysis
They cause coagulation & shrinkage
Above 400C, carbonization of organic materialsoccurs with onset of some inorganic materials
Between 400C & 1200C, inorganic constituents melt,re-crystallize or vaporize
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In general, shorter WL (500-1000 nm) are wellabsorbed in pigmented tissues and blood elements
Longer WL are more interactive with water andHydroxyapatite
Co2 (10,600 nm) is well absorbed by water and has thehighest affinity for Hydroxyapatite
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Lasers in EndodonticsDentinal Hypersensitivity
Pulp Diagnosis
Pulp Capping & Pulpotomy
Cleaning & Shaping of root canal systemsSterilization
Endodontic Surgery
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Dental Hypersensitivity Characterized as short, sharp pain from exposed
dentin that occurs in response to provoking stimuli
such as cold, heat or chemicals
Not ascribed to any other dental defect or pathology
Can be attributed to non carious tooth loss (Wastingdiseases)
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Various treatment modalities
Blocking the dentinal fluid flow
Application of various agents to exposed dentinaltubule Oxalate salts
Isobutyl cyanoacrylate
Fluoride releasing resins
Reduce Neuronal Responsiveness 5% Potassium Nitrate & 10% Strontium Nitrate
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Laser as a treatment modality
Rationale for laser induced reduction in DH is basedon 2 possible mechanisms
1st mechanism implies direct effect of laserirradiation on the electric activity of nerve fiberswithin the dental pulp
2nd mechanism modification of the tubular structureof dentin by melting and fusing of the hard tissue orsmear layer and subsequent sealing of dentinal tubules
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Lasers for treatment of DH are divided into 2 groups:
Low Output Power Lasers Middle Output Power Lasers
Helium Neon Diode Nd:YAG
Gallium-Aluminum-Arsenidediode
Co2
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Low output lasers were used byKimura et alfor their
anti-inflammatory effect
Have an ability to stimulate the nerve cells
Senda et alwere the first to apply He-Ne lasers
Used a low power output of 6 mW which does notaffect the morphology of dentin and enamel
It allows a small fraction of the energy to reach thepulp
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The mechanism of action is not clear but it wasclaimed that the helium neon laser irradiationaffects the electric activity (action potential) rather
than A- or C-fiber nociceptors
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Gallium-Aluminum-Arsenide diode have 3 WL (780,830 & 900 nm)
Matsumoto et alapplied an output of 30 mW in acontinuous wave for 0.5 3 mins
The analgesic effect was due to a depressed nervetransmission caused by diode laser irradiationblocking the depolarization of C-fiber afferents
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In 1972, Kantola et al used a Co2 laser to create craterson dentin
Microradiography and Electron probe analysisrevealed higher levels of Ca & P in the fused orrecrystallized dentin
At a 1 year follow up, it was observed that in laserirradiated dentin, recrystallization had occurred anddentin had changed to look like the original
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(Ref: IEJ,33, 173185, 2000)
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Helium Neon and Diode laser at a low power of 1 or 2mW
Wavelength is 632.8 nm
Laser beam is directed towards the tooth (to the bloodvessels)
Moving RBC causes the frequency of the laser beam tobe Doppler shifted and some of the light be backscattered out of the tooth
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The reflected light is detected by the photocell on thetooth surface and its output proportional to thenumber and velocity of the blood cells
Advantages over EPT:
Can be used in traumatized teeth
Does not rely on painful sensation to determine vitality
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(REF: Australian Dental Journal 2003;48:3.)
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Pulp Capping & PulpotomyAAE defines Pulp capping as a procedure in which adental material such as Calcium hydroxide or MTA isplaced over a pulpal wound to encourage the
formation of reparative dentin
Pulpotomy is defined as the surgical removal of thecoronal portion of the pulp by means of preserving theremaining radicular tissues
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Pulp Capping & Pulpotomy
Melcer et alused Co2 lasers & demonstrated newmineralized dentin formation without cellularmodifications in pulpal tissues
Shoji et alused Co2 lasers in different WL and reportedthat no damage was detected in the radicular pulp.Charring, coagulation necrosis and degeneration ofodontoblastic layer occurred, with no pulp damage
Jukic et alused Co2 and Nd:YAG lasers on exposed pulptissue and reported that a dentinal bridge was formed
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Moritz et alused Co2 laser for direct pulp capping
The energy level of 1 W at 0.1 second exposure timewith 1 second pulse intervals was applied to theexposed pulp
Teeth were check for vitality after 6 and 12 months and89.4% of the teeth retained their vitality
Lasers can be used for direct or in direct pulp cappingin cases of deep and hypersensitive cavities -
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Co2 and Nd:YAG lasers are well absorbed by thehydroxyapatite of enamel and dentin, causing tissueablation, melting and re-solidification
These lasers do not cause any thermal damage to thepulp tissue and do not increase the intra-pulpaltemperature if used at the correct power, duration of
time and intensity
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Cleaning & Shaping of Root Canal
SystemVarious laser systems can deliver the energy into the
root canal using a thin optical fiber
Various systems that have been used are
Nd:YAG
Er,Cr:YSGG
Argon Diode
Er:YAG
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It has been demonstrated in many studies that thelaser radiation has the ability to remove debris andsmear layer from the root canals
It also has the potential to kill the microorganisms
Bergman et al suggested that lasers is not analternative to the conventional cleaning & shaping, butcan be used as an adjunct
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Limitations for use in Root Canals Emission of laser energy from the tip of optical fiber or
the laser when directed into the root canal is notuniform
There may be thermal damage to the periapical tissues
May be hazardous when the tooth apex is near vitalstructures such as mandibular nerve or mentalforamen
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Stabholz et aldeveloped a new endodontic tip that can beused with Er:YAG laser
It is delivered via a hollow tube allows lateral emission ofthe irradiation (side-firing), rather than direct emissionthrough a single opening
The endodontic side firing spiral tip is designed to fit theshape and volume of the root canals prepared by NiTirotary instruments
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The tip is sealed at its far end, preventing irradiation tothe periapical tissues
In a recent study, the efficacy in smear & debrisremoval of the side firing tip was compared toProTaper
The RCLase Side firing tip was used in extractedmolars and the teeth were then split and examinedlongitudinally
Efficient cleansing of the RC System is achieved
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Researcher Laser Sample
Moritz et al Diode &Nd:YAG
220
Mehl et al Er:YAG 90 E.coli & Staph
aureusFogel & Pashey Diode Smear Layer
removal;
Takeda et al Er:YAG 60
Sousa-Neto et al Co2 40
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Sterilization of root canals Numerous studies into the sterilization of root canals
have been performed using CO2(Zakariasen et al.1986) and Nd:YAG lasers (Rooney et al. 1994, Ebihara
et al. 1994, Fegan & Steiman 1995, Moshonov et al.1995b, Goodis et al. 1995, Sekine et al.)
The Nd:YAG laser is more popular, because a thin
fibre-optic delivery system for entering narrow rootcanals is available with this device
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Many other lasers such as the XeCl laser emitting at308 nm (Stabholz et al. 1993), the Er:YAG laseremittedat 2.64 mm (Gomi et al. 1997), a diode laseremitting at810 nm (Moritz et al. 1997a), and the Nd:YAP laser
emitting at 1.34 mm (Blum et al. 1997) have also beenused
All lasers have a bactericidal effect at high power that
is dependent on each laser
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There appears to exist a potential for spreadingbacterial contamination from the root canal to the
patient and the dental team via the smoke producedby the laser, which can cause bacterial dissemination(Hardee et al. 1994)
Thus, precautions such as a strong vacuum pumpsystem must be taken to protect against spreadinginfections when using lasers in the root canal(McKinley & Ludlow 1994)
Sterilization of root canals by lasers is problematicalsince thermal injury to periodontal tissues is possible
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Aim of Obturation:
Eliminate all avenues of leakage
Seal the RC system from all ends
Rationale in using lasers for obturation is that theirradiation can be used as a heat source for softeningthe GP
Conditioning of the dentin walls can also be done
Laser assisted Obturation
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The photo-polymerization of camphorquinone-
activated resins for obturation is possible using anAr laser emitting at 477 and 488 nm (Potts &Petrou 1990, 1991)
The results indicate that an Ar laser coupled to anoptical fiber could become a useful modality inendodontic therapy
Studies have been performed using the obturationmaterial AH-26 & AH Plus (Zaman et al. 1994) andcomposite resin (Anic et al. 1995)
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An SEM examination revealed that laterallycompacted resin fillings showed fewer voids thanthose obtained by vertical compaction (Kitamura
et al, 2005)
Ar, CO2, and Nd:YAG lasers have been used tosoften gutta-percha (Anic & Matsumoto 1995), and
results indicate that the Ar laser can be used forthis purpose to produce a good apical seal
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The clinical evidence from reported studies for the use
of lasers in obturation is not sufficient
It has not been determined if the use of laser as a heatsource is safe for the surrounding structures of thetooth as well as for other teeth
A suitable wavelength has not been ascertained
Effect on the sealer per se has to be determined
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Retreatment Rationale for using lasers in retreatment is ascribed to
the need to remove foreign material, GP etc bysoftening it by heat
Farge et al used the Nd:YAP (1340 nm)Attempted to remove GP and ZOE sealer
Silver cones and separated instruments
They concluded that lasers alone cannot remove all theobturating materials from the RC
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Yu et al were able to remove the entire filling material
in 70% cases, while broken files in only 55% of thecases using the Nd:YAG laser
Removal of GP and files is always a challenge and
lasers can only assist
A clinical advantage is that toxic solvents like xylenecan be avoided
However the effects of the laser on the tissues andsurrounding teeth remains to be studied
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Lasers in Endodontic Surgery
Weichman & Johnson attempted to seal the apicalforamen of freshly extracted teeth in which the pulphad been removed
Laser is used for the surgery, a bloodless surgical fieldshould be easier to achieve due to the ability of the
laser to vaporize tissue and coagulate and seal smallblood vessels
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If the cut surface is irradiated, the surface is sterilized
and sealed
The potential of the Er:YAG laser to cut hard dentaltissues without significant thermal or structural
damage eliminates the need for mechanical drills
Clinical investigations into laser use for apicectomybegan with the CO2 laser (Miserendino 1988),which
was successful
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The use of this laser seals the dentinal tubules in theapical portion of the root and sterilizes the surgicalsite
On, extracted teeth (Stabholz et al. 1992 Arens et al.1993, Wong et al. 1994), used the Nd:YAG laser andfound that there was a reduction in the penetration ofdye or bacteria within resected roots
When the laser was used for resection itself, either inextracted human teeth in vitro (Maillet et al. 1996),found that tissue repairs was quicker when comparedwith those roots resected with a bur
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Advantages Good hemostasis
Improved visualization of surgical site
Sterilization operative field
Reduced permeability of root surface dentin
Reduction in post operative pain
Reduced risk of contamination of surgical site by
eliminating use of air turbines
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Constraints Time Consuming
Increase temperature
Cause irreversible pulpal damage
Needs precise execution
Increased cost of treatment
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Healing after Laser Surgery
Reports suggest that laser created wounds heal morequickly and produce less scar tissue than conventionalscalpel surgery.
However, contrary evidence from studies in pigs, ratsand dogs indicate thatthe healing of laser wounds isdelayed
More initial tissue damage may result, and thatwounds have less tensile strength during the earlyphase of healing (Pick et al 1990)
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Abergel et al (1984)experimented with cultured
human skin fibroblasts and showed that collagenproduction and DNA synthesis were delayed when thefibroblasts were exposed to Nd: YAG laser radiation
Crespi et alevaluated the effects of CO2 lasertreatment on fibroblast attachment to root surfacesand concluded that CO2 laser treatment in defocused,pulsed mode with a low power of 2W combined withmechanical instrumentation constitutes a useful toolto condition the root surface and increase fibroblastattachment to root surfaces
(Ref: Journal of Periodontology)
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Other Endodontic uses CO2 and Nd:YAG lasers have been used for the
attempted treatment of root fractures (Arakawa et al.1996). However, regardless of the re-approximationtechnique, laser type, energy, and other parametersused, fusion of the fractured root halves was notachieved
Lasers (Ar, CO2, Nd:YAG lasers) have been usedsuccessfully to sterilize dental instruments (Adrian &Gross 1979, Hooks et al. 1980, Powell & Whisenant
1991).
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Results indicated all three lasers (Ar, CO2, Nd:YAGlasers) are capable of sterilizing selected dentalinstruments; however, the argon laser was able to do so
consistenly at the lowest energy level of 1 W for 2 min
A pulsed dye laser emitted at 504 nm was used for theremoval of a calcified attached denticle (Rocca et al.
1994)
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Lasers in Operative & Aesthetic
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Lasers in Operative & Aesthetic
Dentistry
Lasers have become a part of routine operative andaesthetic practice
There are five lasers that are currently in thearmamentarium
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Argon lasers The wavelength is absorbed by Hb
This attribute allows precision cutting, hemostasis &coagulation of vascular tissue
Use of argon lasers have been used for curingcomposites (at low power achieving higher bondstrength)
Transillumination in diagnosis of tooth fractuures
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Plasma Arc Curing (PAC) PAC & Argon laser curing systems have rapid
polymerization of composites
However they increase heat generation and
polymerization shrinkage stresses Studies have shown that they exhibit a narrow spectral
output and do not coincide with the spectralrequirements of all restorative resins
Bleaching of stained teeth
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Co2
Lasers Used for vaporizing, cutting and coagulation of soft
tissue
Used more for soft tissue procedures which includegingival re-modelling and shaping in aestheticdentistry (Perio-Aesthetics)
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Diode Lasers 2 different WL are used
Ga-Al-As Laser (800 nm) & In-Ga-As (980 nm)
These are used in contact mode for cavity preparation,
removal of bacterial contamination and coagulation oftissue
Also used for Diagnosis
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Erbium Family
Er lasers are absorbed by Hydroxyapatite and water
Allows to cut soft tissue, tooth structure and bone
Er:YAG (2940 nm) cuts teeth easily & quickly
Also used for removal of caries (excavation)
Decay present on the facial of the
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Decay present on the facial of themaxillary left lateral incisor
The Erbium laser used to remove thedecay. No anesthesia was required
After caries removal and preparation iscomplete
Definitive direct bonded restorationafter preparation with the Erbium laser
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Etching Laser etching has been evaluated as an alternative to
acid etching of enamel and dentine. The Er:YAG laserproduces micro-explosions during hard tissue ablation
that result in microscopic and macroscopicirregularities
These micro irregularities make the enamel surface
micro retentive and may offer a mechanism ofadhesion without acid-etching
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However, it has been shown that adhesion to dentalhard tissues after Er: YAG laser etching is inferior tothat obtained after conventional acid etching(Martinez-Insua et al., 2000)
The weaker bond strength of the composite to laser-etched enamel and dentine to the presence ofsubsurface fissuring after laser radiation. This fissuringis not seen in conventional etched surfaces
The subsurface fissuring contributed to the highprevalence of cohesive tooth fractures in bonding ofboth laser-etched enamel and dentine
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Caries prevention Studies examined the possibility of using laser to
prevent caries (Hossain et al., 2000; Apel et al., 2003)
It is believed that laser irradiation of dental hardtissues modifies the calcium to phosphate ratio,reduces the carbonate to phosphorous ratio, and leadsto the formation of more stable and less acid soluble
compounds, reducing susceptibility to acid attack andcaries
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Laboratory studies have indicated that enamelsurfaces exposed to laser irradiation are more acidresistant than non-laser treated surfaces (Watanabe etal., 2001; Arimoto et al., 2001)
The degree of protection against caries progressionprovided by the one-time initial laser treatment wasreported to be comparable to daily fluoride treatment
by a fluoride dentifrice (Featherstone, 2000)
(Ref: Archives of Orofacial Sciences 2006; 1: 1-4)
L A i t d Bl hi
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Laser Assisted Bleaching
Two laser-assisted whitening systems have been cleared bythe FDA
The laser is used to enhance the activation of bleachingmaterial, which then whitens the teeth
The argon laser wavelength of 488 nm for 30 seconds toaccelerate the activity of the bleaching gel
After the laser energy is applied, the gel is left in place forthree minutes, then removed. This procedure is repeatedfour to six times
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Another system uses both the argon and CO2 lasers inthe bleaching process
The argon laser is used as previously described, then
the CO2 laser is employed with another peroxide-based solution to promote penetration of thebleaching agent into the tooth to provide bleachingbelow the surface
The entire clinical time for this system ranges from onehour to three hours
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Laser-assisted tooth bleaching, however, still poses a
number of unanswered questions
Because of continuing concerns and unknowns aboutlaser interactions with hard tissue and the lack of
controlled clinical studies, CO2 laser-assistedbleaching is not recommended (FDA)
Based on previously accepted uses of argon lasers andassociated temperature-rise studies, the use of theargon laser in place of a conventional curing light maybe acceptable if the manufacturers suggestedprocedures are carefully followed (FDA)
Dental Laser Safety
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Dental Laser Safety
Safety is an integral part of providing dental treatmentwith lasers
3 aspects to safety: Manufacturing process
Proper operation of the device
Personal protection
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Regulatory Agencies
American National Standard Institute (ANSI)
Food and Drug Administration (FDA)
Center for devices and Radiological Health (CDRH) Occupational safety health administration (OSHA)
Laser Classification
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Laser Classification
Class Laser Properties
I Pose no health hazard e.g. CD Player
II Emit only visible light with low power output & do not poseany health hazards
Maximum allowable output is 1 mWIIIa Emit any WL and have an output power of 0.5 W of visible
light; In this laser light can be viewed only momentarilyCaution label is present
IIIb Hazardous to unprotected eye; Output power no greater
than 0.5 W; eg. Argon Laser curing light; Eye protection ismust
IV Hazardous from direct viewing and may produce diffusereflections; Output power more than 0.5 W; Can producefire and severe skin reactions; Can ignite inflammabledevices
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Fire & Explosion Hazards Use only wet and fire retardant materials in operative
field
Use non combustible anesthetics
Avoid alcohol based topical anestheticsAvoid alcohol moistened gauze or cotton
Fire Extinguisher
Stay informed Follow ANSI regulations
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Guidelines Mention outside
Door Switch
Fire hazards
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Eye Protection In 1962, the awareness to eye
protection began
Eye is a critical target for laserinjury
Class III & IV lasers pose a threat
to the eye
Proper eye wear is a must
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Why the Eye ??? Cornea is made up of 90% Water
Absorbs emissions from all lasers
Cause Corneal Burns
Holium and Erbium lasers affect the Aqueous andVitreous Humor as well as the lens which lead toAqueous Flare & Cataract formation
Retinal damage occurs due to lasers with more depth ifpenetration and is absorbed into the pigments (Argon,Diode, He:Ne)
Th i ti l bl t i j
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The eye is 100,000 times more vulnerable to injurythan the skin
WL from 400-1400
Protective glasses must have an Optical Density of atleast 4
For specific high WL lasers like Nd:YAG & Diodes,there are specific eye wear
Eyewear is designed to have adequate protection for awide range of WLs
Regardless of protection, NEVER look directly into thelaser beam
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Sterilization & Infection Control
Fiber optic cables & handpieces can be autoclaved inpouches
Oil based aerosols must not be used
The wires and protective casing / housing should be
wiped clean and not autoclaved
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In Conclusion
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Lasers New face of Dentistry
Diverse applications
High Cost
Treatment Planning
Adverse Effects
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References Pathways of Pulp (9th Ed.) S.Cohen
Art & Science of Operative Dentistry Sturdevant
Textbook of Endodontics (6th Ed.) Ingle
DCNA 2000, 2005
Journal of Endodontics
International Endodontic Journal
Journal of American Dental Association
British Dental Journal