Lasers in Endo

7/31/2019 Lasers in Endo

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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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https://decs.nhgl.med.navy.mil/DIS65/diagnodent2.jpg


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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

Lasers in Endo

Documents