laser.pptx

 Introduction
 Historical perspectives
 LASER design
 Laser physics
 Classification of Lasers
 Types of lasers
 Advantages & Disadvantages
 Photobiology of lasers
 Therapeutic uses:
› Diagnosis
› Lasers uses in non surgical periodontal therapy
› Lasers uses in surgical periodontal therapy
› Application of laser in the treatment of peri – implantitis
› Wound healing
› Photodynamic therapy
› LANAP
 Laser safety

Introduction
 LASER design
 Laser physics
 Types of lasers
› Diagnosis
› Wound healing
› LANAP
 Laser safety

 A laser is a device that emits light through a process called stimulated
emission.
 The term LASER is an acronym for ‘Light Amplification and Stimulated
Emission of Radiation’.
 concept expounded by Albert Einstein as early as 1917.
 With the recent advances and developments lasers could be applied
for the dental treatment including periodontal, restorative and surgical
treatments.
 A wide range of lasers such as Co2, Nd:YAG, Er:YAG, Diode,
Alexandrite laser etc., are used
 for soft and hard tissue ablation, detoxification of root surface, pocket
debridement, bacterial elimination, calculus removal and various
surgical approaches such as gingivectomy, flap surgery and
mucogingival surgeries.

 Introduction
Historical perspectives
 LASER design
 Laser physics
 Types of lasers
› Diagnosis
› Wound healing
› LANAP
 Laser safety

Concept:
 The dental laser of today have benefited from decades of laser
research and have their basis in certain theories from the field of
quantum mechanics, initially formulated during the early 1990s by
Danish Physicst Bohr.
 Einstein’s article “Zur quantentheorie der strahlung”, on the
stimulated emission of radiant energy, published in 1917, is
acknowledge as the conceptual basis for amplified light.
 Nearly 40yrs later, American physicist Townes first amplified
microwave frequencies by the stimulated emission process and the
acronym MASER (Microwave Amplification by Stimulated Emission
of Radiation) came into use.
 In 1958, Shawlan & Townes, discussed extending the MASER
principle to the optical portion of the electromagnetic field, hence
LASER.

Development:
 In 1960, the first working laser a pulsed ruby instrument was built by
Maiman of Hughes Research Laboratories.
 The CO2 laser which is operated in the infrared portion of the
electromagnetic spectrum was fabricated by Patel & Colleagues in
1964.
 Parallel to these development was the design by Johnson in 1961 of
a Laser with a wavelength 1.06 microns using Neodyminum (Nd)
doped Yettrium Aluminum Garnet (YAG) rod. These early CO2 & YAG
lasers were free beam lasers in the sense that the laser instrument
did not contact the target tissue.
 More recently in the early 1980s, the contact laser concept was
developed by collaboration between Dikuzono & Joffe, who
experimented with synthetic sapphire tips, with the laser energy
conducted in a optical fibers. The tips were designed for various
surgical tasks, and thus the tips had a number of shapes & sizes.

Use in periodontics:
 The history of Laser therapy as applied to periodontics began
in the early 1960s with the development of Argon, CO2 & Nd :
YAG lasers.
 The next major advance in the development of laser
technology for soft tissue use was the introduction of a
contact delivery system for the Nd :YAG Laser in 1984.
 One of the first CO2 lasers used for the oral soft tissue
applications was introduced in 1987. Although CO2 Lasers
were generally used in a non contact mode, the newer hollow
wave guide delivery system allow for focused delivery of the
energy to within 0.1mm of the target tissue, in a cutting mode.

 Introduction
LASER design
 Laser physics
 Types of lasers
› Diagnosis
› Wound healing
› LANAP
 Laser safety

 Introduction
 LASER design
Laser physics
 Types of lasers
› Diagnosis
› Wound healing
› LANAP
 Laser safety

 The mechanism of producing
radiation in a laser relies on
stimulated emission, where energy is
extracted from a transition in an atom
or molecule. This is a quantum
phenomenon discovered by Einstein
 Atoms consists of a nucleus
consisting protons and neutrons and
an electron cloud.
 Atoms can be in different states of
excitation.
 The energy level is the quantum state
of an atom, which ranges from a base
or ground level of 0 or the lowest
possible energy level, to a higher level
in which this atom is driven to a state
of excitation.

 Transition of an atom from higher energy level
to a lower energy level results in the emission
of Radiant energy. This radiant energy is
emitted as a discrete packet of energy termed
a Photon.
 Similarly, transition of an atom from lower
energy level to a higher level takes place by
the absorption of a photon.
 Shift of an atom from one energy level to
another is termed as Transition and in case of
large population of atom, a Population
inversion.

 The gain medium of a laser is a material of controlled purity, size,
concentration, and shape, which amplifies the beam by the process
of stimulated emission
 The gain medium absorbs energy, which raises some electrons into
higher-energy ("excited") quantum states.
 Particles can interact with light by either absorbing or emitting
photons.
 When the number of particles in one excited state exceeds the
number of particles in some lower-energy state, population inversion
is achieved and the amount of stimulated emission due to light that
passes through is larger than the amount of absorption.
 Hence, the light is amplified. By itself, this makes an optical
amplifier.
 When an optical amplifier is placed inside a resonant optical cavity,
one obtains a laser.

Spontaneous Emission
Spontaneous emission can occur when an atom falls from higher energy level
to lower energy level without any application of external energy and results
in emission of radiant energy. The amount of energy emitted is directly
proportional to the difference between the higher level and the lower
energy level.
Spontaneous Absorption
Spontaneous absorption occurs if an atom in lower level absorbs a photon and
is elevated to upper energy level.
Stimulated Emission
At equilibrium, large cohort of the population of an atom in the upper energy
state is much smaller than that in the lowest energy state.
Stimulated emission can occur if an atom can be induced to possess a
population existing in the higher energy levels.
This is considered to be a Population inversion in a laser medium and is a
fundamental prerequisite for laser action.

Inducing Population Inversion by Pumping
The term pumping, as used in laser technology means
providing adequate energy to the atom within a lasing
medium in a form that induces them to proceed a higher
energy level or excited state, thus inverting the population
of atoms from ground level to an excitation level.
There are numerous methodologies of pumping laser media,
such as optical, electrical discharge, radio frequency,
chemical excitation, electron beam, using one laser to
excite or pump another.

 The resonator typically consists of two mirrors
between which a coherent beam of light travels in
both directions, reflecting back on itself so that an
average photon will pass through the gain medium
repeatedly before it is emitted from the output
aperture or lost to diffraction or absorption.
 The gain medium will amplify any photons passing
through it, regardless of direction; but only the
photons in a spatial mode supported by the
resonator will pass more than once through the
medium and receive substantial amplification.

Properties of Laser Light
 Monochromaticity
 Directionality
 Coherence
 Brightness

Continuous – Wave / Pulsed Laser
A laser can be classified as operating in either
continuous or pulsed mode, depending on
whether the power output is essentially
continuous over time or whether its output
takes the form of pulses of light.

 Some applications of lasers depend on a beam whose output
power is constant over time. Such a laser is known as
continuous wave. Many types of lasers can be made to operate
in continuous wave mode to satisfy such an application.
 For continuous wave operation it is required for the population
inversion of the gain medium to be continually replenished by a
steady pump source.
 In some lasing media this is impossible.
 In some other lasers it would require pumping the laser at a very
high continuous power level which would be impractical or
destroy the laser by producing excessive heat. Such lasers
cannot be run in CW mode.

 In other cases the application requires the production of pulses
having as large an energy as possible.
 Since the pulse energy is equal to the average power divided by
the repetition rate, this goal can sometimes be satisfied by
lowering the rate of pulses so that more energy can be built up
in between pulses.
 In laser ablation for example, a small volume of material at the
surface of a work piece can be evaporated if it is heated in a
very short time, whereas supplying the energy gradually would
allow for the heat to be absorbed into the bulk of the piece,
never attaining a sufficiently high temperature at a particular
point.

 Introduction
 LASER design
 Laser physics
Classification of Lasers
 Types of lasers
› Diagnosis
› Wound healing
› LANAP
 Laser safety

LASERs are classified into four broad areas depending on the potential for
causing biological damage.
 Class I - These lasers cannot emit laser radiation at known hazard levels.
 Class I.A. - This is a special designation that applies only to lasers that are
"not intended for viewing," such as a supermarket laser scanner. The
upper power limit of Class I.A. is 4.0 mW.
 Class II - These are low-power visible lasers that emit above Class I levels
but at a radiant power not above 1 mW.
 Class IIIA - These are intermediate-power lasers (cw: 1-5 mW), which are
hazardous only for intrabeam viewing. Most pen-like pointing lasers are in
this class.
 Class IIIB - These are moderate-power lasers.
 Class IV - These are high-power lasers (cw: 500 mW, pulsed: 10 J/cm2 or
the diffuse reflection limit), which are hazardous to view under any
condition (directly or diffusely scattered), and are a potential fire hazard
and a skin hazard. Significant controls are required of Class IV laser
facilities.

 Introduction
 LASER design
 Laser physics
Types of lasers
› Diagnosis
› Wound healing
› LANAP
 Laser safety

Lasers are commonly designated by the type of
lasing material employed.
 Gas lasers
 Chemical lasers
 Dye lasers
 Metal-vapor lasers
 Solid-state lasers
 Semiconductor lasers
 Diode lasers
 Excimer lasers
 Fiber lasers
 Gas lasers
 Free electron lasers
 Optical parametric oscillators

Lasers are commonly designated by the type of
lasing material employed.
 Gas lasers
 Chemical lasers
 Dye lasers
 Metal-vapor lasers
 Solid-state lasers
 Semiconductor lasers
 Diode lasers
 Excimer lasers
 Fiber lasers
 Free electron lasers
 Optical parametric oscillators

 A solid-state laser is a laser that uses a gain medium that is a solid.
 Generally, the active medium of a solid-state laser consists of a glass or
crystalline host material to which is added a dopant such as neodymium,
chromium, erbium, or other ions.
 most common  neodymium-doped YAG.
 Solid state lasing media are typically optically pumped, using either a flashlamp
or arc lamp, or by laser diodes.
(A dopant, also called a doping agent, is a trace impurity element that is inserted
into a substance (in very low concentrations) in order to alter the electrical
properties or the optical properties of the substance)

 The term excimer is short for 'excited dimer’
 'Most "excimer" lasers are of the noble gas halide type
 The first excimer laser was invented in 1970 using a xenon dimer (Xe2)
excited by an electron beam to give stimulated emission at 172 nm
wavelength.
 An excimer laser typically uses a combination of a noble gas (argon,
krypton, or xenon) and a reactive gas (fluorine or chlorine).
 Under the appropriate conditions of electrical stimulation and high
pressure, a pseudo-molecule called an excimer is created, which can
give rise to laser light in the ultraviolet range.

 A gas laser is a laser in which an electric current is
discharged through a gas to produce coherent light.
 The gas laser was the first continuous-light laser.
 The first gas laser, the Helium-neon laser (HeNe),
was invented in 1960.
 It produced a coherent light beam in the infrared
region.

 The laser diode is a laser where the active
medium is a semiconductor.
 A semiconductor laser is simply a super
focused, super powerful LED.
 Generally very small and use low power.

 A dye laser is a laser which uses an organic
dye as the lasing medium, usually as a liquid
solution
 Dye lasers use complex organic dyes such as
Rhodamine 6G , in liquid solution or suspension
as lasing media.
 They are tunable over a broad range of
wavelengths.

 Introduction
 LASER design
 Laser physics
 Types of lasers
Advantages & Disadvantages
› Diagnosis
› Wound healing
› LANAP
 Laser safety

The significant advantages of the laser in surgery are
 its ability to coagulate, vaporize or incise tissue.
 coagulating bleeding vessels and there by providing a relatively dry surgical field.
 There is reduction in the thermal damage to contiguous non target tissue
 reduction in post operative tissue edema presumably arising from reduced mechanical tissue trauma.
 access to target tissue is provided by photo transmission through flexible quartz fibers or waveguides.
 This provides tactile sensation, when contact tips or waveguides are used.
 The laser beam or its energy characteristics can be modified to provide selective tissue ablation and to
provide selective tissue effects by the use of specific tissue photosensitizing agents.
 One can change lasers or laser wavelengths to enhance selective tissue absorption.
 a decreased incidence of post operative pain.
 as well as decrease in wound contraction owing to the reduction in stimulation of tissue myoepithelial
and fibroblastic cellular elements, thus leading to less scarring.

 radiant energy hazards to the patient, surgeon
and operative team from inadvertent exposure,
resulting in laser skin burns, eye damage and
even blindness.
 the great expense of laser equipment and
service fees.
 the need for additional training of the surgeon
and operating team.

 Introduction
 LASER design
 Laser physics
 Types of lasers
Photobiology of lasers
› Diagnosis
› Wound healing
› LANAP
 Laser safety

 The field of study involving the interactions of non
ionizing electromagnetic radiation with biomolecules,
and the resulting biologic reactions, is know as
Photobiology.
 The reaction of radiant energy with organic tsisues
depends on the nature of the light, and on the
character of the tissues exposed.
 All photobiologic effects are wavelength and dose
dependent.
› Photocoagulation,
› Photovaporization,
› Photochemical and
› Photomechanical phenomena.

 Laser radiant energy interacts with all tissues in several
quantifiable ways.
› Reflection,
› Transmission
› Scattering, and
› Absorption.
 Reflection from or Transmission through tissue results in
no observable laser tissue interaction.
 Scattered laser energy is absorbed over a broader area or
volume of tissue, thus diffusing the effects of the energy.

 If a laser incident to tissue with a normal temperature of 37oC
heats the tissues to 60oC for a limited time there is no alteration
in the appearance of the tissue structure.
 However, biologic tissues heated to temperatures over 60oC
undergo coagulation. This coagulation phenomenon is the basis
of most of the surgical applications of lasers.
 As a result of photocoagulation, proteins, enzymes, cytokines,
and other bioactive molecules are heated to temperatures over
60oC, the result being instant denaturation.

 Higher irradiances produce a more rapid
increase in temperature and faster tissue
coagulation eventually exceeding 100oC.
When this temperature is exceeded. the
phenomenon of photo vaporization is
observed.

 By inspection, photocoagulation appears as a whitening of the
tissue surface.
 This surface change is the result of an alteration in the
molecular structure of the tissue constituents mainly collagen.
 When temperatures >60oC are reached, the helical polymer is
disrupted and the coils become randomized.
 The result is that the collagen fibers undergo significant
shrinkage following photocoagulation.
 This physical event affecting collagen has a practical value
during laser surgery:
› the lased tissues constrict against the proximal vasculature and the
vessels shrink as a result of the collagen composition of their walls,
which results in the enhanced hemostasis associated with the use of
the laser.
› Laser damage to erythrocytes attracts a population of platelets,
which encourage intraluminal thrombosis, further decreasing blood
loss.

 Intense, highly focused laser radiation produces
surface temperatures exceeding 100oC, which
cause tissue vaporization.
 There is a thousand fold expansion of cells as
cellular water is converted to steam and
temperatures over 100oC destroy cellular
protein.
 The volume of steam generated cause the cells
literally to explode, releasing the confined
steam.

 The production and explosive release of steam cause
ablation of biologic tissue, which takes the form of a
laser plume that consists of superheated steam and
microscopic particles.
 Debris or particles in the plume that lie randomly within
the path of the laser beam are further heated, resulting
in partial or complete combustion accompanied by
smoke production and flashes of incandescence.
 With the carbon dioxide laser, the ablative process
continues through each newly exposed tissue layer
and is under the control of the laser surgeon.
 Photo thermal or photo vaporization is used for
incision and removal of pathologic tissue.

 During use of the carbon dioxide laser, vaporization of water
prevents temperatures in the most superficial unlased cellular layer
from exceeding 100oC; however, thermal energy conducted to
deeper tissue planes produces a zone of permanent heat damage
evidenced by protein denaturation.
 The volume or thickness of the zone is directly proportional to the
power density of the laser at the superficial lased tissue interface as
well as on the duration of laser energy exposure.
› The heat from the most superficial lased cell layer, which could cause
deeper tissue damage, simply cannot be conducted rapidly enough owing to
the more rapid vaporization of the surface cells. Therefore, deeper
penetration is avoided by the protective effect of rapid vaporization of more
superficial cell layers.
› On the other hand, at lower power densities with equally small volumes of
tissue removal permits penetration of thermal energy to deeper tissue
planes, resulting in a larger zone of injury.
› Similarly, when the laser is applied for longer periods, the deeper tissue
damage is greater.

 Power density varies across the diameter of the
laser beam; the walls of the incision or laser
trench are radiated only obliquely.
 In a deep narrow incision, the injury at the
deepest penetration of the beam can be
marginal, about 0.1mm.
 This observation has implication in using the
laser to create an incision (light scalpel),
avoiding unwanted injury to contiguous tissues.

 Radiant energy possessing a multitude of
wavelength can be used to treat a host of
dermatologic disease by administering a
photosensitizing agent to the patient before
application of the light.
 In this manner, an exogenous photosensitizing
agent acting as a tissue chromophore causes
an alteration of the lesional tissue when light is
applied.

 The generation and propagation of nonthermal, photodisruptive tissue effects were
designed by ophthalmologists to be directed at transparent or translucent tissue
membranes in the eye.
 The generation of photomechanical effects requires the use of extremely high-power Q-
switched or mode locked opthalmic Nd:YAG lasers capable of generating ultrashot
pulses.
 The beam thus produced is focused to an extremely small spot size of 50 microns
diameter, so even lower energy pulses (millijoules) can result in unusually high
irradiances (megawatts per square centimeter).
 Pulse times briefer than 100 femtoseconds are common.
 When a tiny volume of tissue is vaporised instantaneously, there is a massive energy
density build up or is evolved into optical plasma, which may reach 10,000oC in an
extremely small volume tissue.
 The laser effects depend on a hydrodynamic shock wave that occurs after the formation
of plasma and that can disrupt tissue.
 This effect is highly applicable to the semitransparent membranes in the eye.

 Introduction
 LASER design
 Laser physics
 Types of lasers
Therapeutic uses:
› Diagnosis
› Wound healing
› LANAP
 Laser safety

 Diagnosis
 Nonsurgical periodontal therapy
 Surgical therapy
 Treatment of periimplantitis
 Wound healing
 Photodynamic therapy
 LASER-assissted new attachment
procedure

Calculus detection:
 The only commercially available device (Keylaser3; KaVo)
combines detection and treatment in a feedback-controlled
manner for selective removal of calculus.
 The integrated calculus-detection device is based on a 655-
nm InGaAs diode laser for autofluorescence- based calculus
detection,
 whereas a 2940-nm Er:YAG laser is used for treatment.
 The Er:YAG laser is only activated to emit light if a preselected
autofluorescence threshold value for the diagnostic laser on a
scale of 0–99 is exceeded. As soon as the value falls below
the threshold, the Er:YAG laser turns off.
 This combination of a diagnostic and a therapeutic laser was
designed to optimize calculus removal while minimizing the
undesired side effects of the Er:YAG laser.

 20 teeth  were treated with laser.
 The fluorescence threshold varied between 5 (recommended by the
manufacturer as the lowest threshold value) and 1 in order to
potentially increase sensitivity.
 The amount of residual calculus depended on the laser fluorescence
threshold levels.
 The residual cementum was significantly thinner than the untreated
residual cementum.
 Thus, by reducing the threshold level, the sensitivity was increased at
the expense of a reduced specificity, as indicated by the increase of
undesired substance loss.

 Clinical study compared the clinical benefit of autofluorescence-
controlled Er:YAG laser radiation with that of a special ultrasonic device
with vertical vibrations of the working tip, and with hand instrumentation.
 72 singlerooted teeth  randomly treated by
› the laser,
› the Vector ultrasound system,
› conventional hand instruments, or
› remained untreated.
 The ultrasound system left significantly smaller areas of residual calculus
than the two other therapies, but needed a significantly longer
instrumentation time than the laser and the hand instruments.
 However, treatment with the feedback controlled Er:YAG laser still resulted
in significantly less residual calculus and less root-surface alterations than
hand instrumentation.

 clinical study  compared the microbiological effects of the Er:YAG laser, hand instruments, sonic
scalers and ultrasonic scalers.
 The controlled, randomized, single-blinded clinical trial  included 72 periodontal patients.
 The four quadrants per patient were randomly assigned to one of the following four debridement
modalities:
› hand instruments,
› a feedback-controlled Er:YAG laser,
› a sonic scaler or
› a piezoelectric ultrasonic scaler.
 Subgingival plaque samples were obtained at baseline and at 3 and 6 months postoperatively.
 All four treatments resulted in a significant reduction in the amounts of Porphyromonas gingivalis,
Prevotella intermedia, Tannerella forsythia and Treponema denticola after 3 months.
 Laser and sonic instrumentation failed to significantly reduce the amount of Aggregatibacter
actinomycetemcomitans.
 Six months post-treatment, the amount of test bacteria had increased in all study groups.

In conclusion, clinical and histological studies
have shown that laser-based detection and
treatment of calculus can effectively remove
subgingival calculus and preserve root
substance. However, the results were
comparable with hand and ultrasonic
debridement, and controlled long-term
clinical studies are lacking.

CO2 laser
 Wavelength of 10,600nm
 Is used as both a pulsed and a continuous wave
laser.
 Readily absorbed by water and therefore is very
effective for the surgery of soft tissues, which have
a high water content.
Advantage of CO2 laser surgery over the scalpel
 strong haemostatic and bactericidal effect.
 Very little wound contraction
 minimal scarring

Disadvantages:
 produces severe thermal damage, such as
cracking, melting, and carbonization when applied
to hard tissues, its use has been limited to soft
tissue procedures.
 It is also highly absorbed by the mineral
components of hard tissue, especially phosphate
ions (-PO4) in the carbonated hydroxyapatite.
 The energy applied is readily absorbed in the hard
tissue but causes instantaneous heat
accumulation in the irradiated inorganic
components, resulting in carbonization of organic
components and melting of inorganic ones.

Mode of delivery:
 Transmission of the CO2 laser through optical
fibers was very difficult.
 Recently, new flexible fiber optic delivery and
hollow tube wave guiding systems have been
developed, along with the development to
contact tips.
 These advances may render the use of the CO2
laser for periodontal pockets possible in the
near future.

 Spencer et al. found toxic products on the carbonized
layer of the CO2 lased root surface.
 Miyazaki et al. (119) applied CO2 laser irradiation for
pocket treatment on the external surface of the marginal
gingiva. They used a continuous wave mode CO2 laser
(2.0 W, 120 s) and reported decreased inflammation and
probing depth after treatment.
 Barone et al. investigated the effects of the pulsed defocus
mode CO2 laser. They concluded that the pulsed defocus
mode may present the advantage of decontaminating the
root surface.
Thus, the CO2 laser, when used with high-energy
output, especially in a continuous wave mode, is
not appropriate for calculus removal and root
surface debridement due to major thermal side-
effects, such as carbonization.
However, when used with relatively low energy
output in a pulsed and/or defocused mode, this
laser may have root conditioning, detoxification
and bactericidal effects on the contaminated root
surfaces.

Nd : YAG laser
 The Nd:YAG laser is a pulsed wave laser
 wavelength  1,064nm.
 Nd:YAG laser has low absorption in water, and the energy scatters or
penetrates into the biological tissues.
Advantages
 The photothermal effect of the Nd:YAG laser is useful for soft tissues
surgery.
 Due to the characteristics of penetration and thermogenesis, the Nd : YAG
laser produces a relatively thick coagulation layer on the lased soft tissue
surface, and thereby shows strong homeostasis.
 Thus, Nd: YAG laser is effective for ablation of potentially hemorrhagic soft
tissue.
 The Nd:YAG laser is not suitable for ablation of intact hard tissues.
However, caries removal using this laser is possible to some extent.

Er : YAG laser
 Introduced in 1974 by Zharikov et al
 solid state laser
 Wavelength  2,940 nm.
 Of all lasers emitting in the near and mid
infrared spectral range, the absorption of the
Er:YAG laser in water is the greatest.
 Since the Er:YAG laser is well absorbed by all
biological tissues that contain water molecules,
this laser indicated not only for the treatment of
soft tissues but also for ablation of hard
tissues.

Mechanism of tissue ablation with the
Er:YAG Laser

Diode Lasers
 The diode laser is a solid-state semiconductor laser
 uses a combination of Gallium (Ga), Arsenide (Ar) and other
elements such as Aluminium (Al) and Indium (In) to change
electrical energy into light energy.
 wavelength range  800-980 nm.
 The laser is emitted in continuous wave and pulsed modes,
 operated in a contact method using a flexible fiber optic
delivery system.
 Laser is poorly absorbed in water, but highly absorbed in
hemoglobin and other pigments.
 Since the diode basically does not interact with dental hard
tissues, this laser is an excellent soft tissue surgical laser,
indicated for cutting and coagulating gingiva and oral mucosa,
and for soft tissue curettage or sulcular debridement.

 The diode laser exhibits thermal effects
using the ‘hot’tip’ effect caused by heat
accumulation at the end of the fiber, and
produces a relatively thick coagulation layer
on the treated surface .
 The advantages of diode lasers are the
smaller size of the units as well as the lower
financial costs.

Argon Laser
 The argon laser uses argon ion gas as an active
medium
 fiber optically delivered
 continuous wave and pulsed modes.
 This laser has two wavelengths, 488 nm (blue) and 514
nm (blue – green), in the spectrum of visible light.
 The argon laser is poorly absorbed in water and
therefore does no interact with dental hard tissues.
 However, it is well absorbed in pigmented tissues,
including hemoglobin and melanin, and in pigmented
bacteria.
 not widely used in periodontal therapy.

Excimer lasers
 Excimer laser are lasers that use a noble gas halide, which is
unstable, to generate radiation, usually in the ultraviolet region
of the spectrum.
 Excimer laser wavelength depends on the chemical
component serving as the medium of the laser.
 It has been suggested that tissue ablation occurs in the no
thermal process of photo ablation, likely due too an
instantaneous increase of the temperature or a straight
combination of chemical elements .
 However, apparatus cost and size still constitute an obstacle
for clinical application of these lasers.
 Furthermore, ultraviolet rays should be used with caution, as
they may have deleterious effects on biological tissues.

CO2 LASER
The CO2 laser has been shown to be effective
in removing masses of tissue as in phenytoin
induced gingival enlargement and
hypertrophy resulting from other
inflammatory stimuli.
The CO2 laser has not been found to be useful
in the osseous recontouring phase of
periodontal flap surgery.

Nd:YAG LASER
 Laser curettage in suprabony pockets where osseous surgery is not required.
 Gingivectomy and gingivoplasty are carried out easily in a non-contact mode with
pulsed or continuous wave lasers. There is excellent hemostasis and minimal tissue
rebound.
 Gingival troughing with the pulsed Nd:YAG laser is a convenient painless method of
preparing for accurate impressions and is an excellent substitute for retraction cord.
There is no blood in the field and the lased circumferential tissues heal quickly and
painlessly.
 Frenectomies  A laser frenectomy is bloodless and requires minimal anesthesia
and the char layer left over the ablated frenum area allows for little or no discomfort.
The operated area does not heal as quickly as a sutured wound, but lack of
postoperative pain more than compensates for delayed wound healing. This
technique is useful particularly in younger patients.
 Other applications include:
› excision or destruction of lesions such as small areas of leukoplakia or fibromas,
› effective as an aid in hemostasis- when there is fine capillary bleeding as that in palatal donor area
contact mode laser coagulates the vessels and stops the oozing.
› Used in the treatment of apthous ulcers –lessens the pain and duration of these ulcerations.

Er, Cr:YSGG AND Er:YAG:
 They have the highest absorption in water than any
other laser and have a high affinity for
hydroxyapatite.
 Both lasers can ablate soft tissue readily because
of its water content but the haemostatic ability is
limited.
 The advantages of these lasers for restorative
dentistry are that a carious lesion in close proximity
to the gingiva can be treated and the soft tissue
recontoured with the same instrumentation.

Diode Lasers
Used for
› reducing bacteria in periodontal pockets.
› soft tissue curettage,
› incision,
› pocket debridement, and
› ablative excisions.

Pulsed dye lasers:
 The flash lamp pulsed dye laser has been
useful in removing persistent granulation tissue
around dental implants.

 Laser have been widely used for tissue incision in exposing submerged
implants.
 Lasers may be used for decontamination of implants surface and treatment of
peri-implantitis without damaging the implant surface.
 Nd:YAG laser  is not suitable for implant therapy, since it easily ablates the
titanium irrespective of output energy.
 diode lasers do not interact with titanium of the coated material.
 Er-YAG and Co2 lasers 
› Kreisler et al. suggested that the power output must be controlled so as to avoid damage of
implant surfaces.
› Matsuyama et al also observed that the Er-YAG laser causes damage or the titanium
surface at a high energy level but does not result in any morphologic change or major
temperature elevation at a low energy level.
› Schwarz et al observed that the Er-YAG laser at 100mJ/pulse and under water irrigation
does not damage titanium surfaces and does not affect the attachment of osteoblast – like
cells. Their preliminary clinical results have also shown that nonsurgical treatment of peri –
implantitis with an Er-YAG laser led to a statistically significant reduction in pocket depth
and gain in clinical attachment level.
 Laser treatment of peri – implantitis may also be a promising field; however,
further studies are required for applications of lasers in implant maintenance
therapy.

 The principles of wound healing following
either nonsurgical or surgical periodontal
treatment procedures have only been
reported for the CO2, Nd:YAG and Er:YAG
lasers.

 In the first study on CO2 laser application, Williams
et al. compared its efficiency for the removal of
granulation and connective tissue from
interproximal defects with that of conventional
curettes in two dogs suffering from chronic
periodontitis.
 formation of new bone in the laser-treated
specimens was limited to surface areas that did not
show any thermally induced surface changes.
 authors suggested that CO2 laser-induced heat
damage may heal without clinical complications

 Crespi et al  treatment of chronic-type class III
furcation defects in dogs using a CO2 laser.
 it was concluded that CO2 laser treatment of
experimentally induced class III furcation
defects is associated with periodontal
regeneration.

 Yukna RA et al;2007  Periodontal
regeneration at diseased root surfaces was
observed following a Nd:YAG laser-assisted
new attachment procedure in humans.
 All laser-treated sites revealed new cementum
and new connective tissue attachment. By
contrast, the control sites frequently exhibited
the formation of a long junctional epithelium
without signs of new attachment or
regeneration.

 The use of Er:YAG laser radiation during open
flap surgery was evaluated by Mizutani et al. in
an experimental animal study.
 Class III furcation defects were experimentally
induced in six beagle dogs and randomly
treated, according to a split-mouth design, using
either an Er:YAG laser or conventional curettes.
 the authors concluded that this type of laser can
be safely and effectively utilized in periodontal
flap surgery and has the potential to promote
new bone formation

 von Tappeiner coined the term photodynamic.
 Photodynamic therapy basically involves three nontoxic ingredients:
› visible harmless light,
› a nontoxic photosensitizer, and
› oxygen.
 It is based on the principle that a photosensitizer (i.e. a
photoactivatable substance) binds to the target cells and can be
activated by light of a suitable wavelength.
 Following activation of the photosensitizer through the application of
light of a certain wavelength, singlet oxygen and other very reactive
agents are produced that are extremely toxic to certain cells and
bacteria

 The photosensitizer is generally applied in the
targeted area by topical application, aerosol
delivery or interstitial injection.
 The light that activates the photosensitizer
must be of a specific wavelength with a
relatively high intensity.
 With the discovery and development of lasers
that are collimated, coherent and
monochromatic, it became possible to utilize a
homogeneous intensive light with low-level
energy that was suitable for activation of the
photodynamic reaction.

Mechanism of photodynamic therapy action
 after irradiation with light of a specific wavelength (lasers),
the photosensitizer at ground state is activated to a highly
energized triplet state.
 The longer lifetime of the triplet state enables the
interaction of the excited photosensitizer with the
surrounding molecules, and it is generally accepted that
the generation of cytotoxic species produced during
photodynamic therapy occurs in this state.
 The triplet-state photosensitizer follows two different
pathways (type I and II) to react with biomolecules

 Type I reactions involve production of free radicals and radical ions.
These free-radical species are generally highly reactive and interact
with endogenous molecular oxygen to produce highly reactive
oxygen species such as superoxide, hydroxyl radicals and hydrogen
peroxide, which are harmful to cell membrane integrity, causing
irreparable biological damage.
 In the type II reaction, the triplet-state photosensitizer reacts with
oxygen to produce an electronically excited and highly reactive state
of oxygen, known as singlet oxygen, which can interact with a large
number of biological substrates as a result of its high chemical
reactivity, inducing oxidative damage and ultimately lethal effects
upon the bacterial cell by damaging the cell membrane and cell wall.
 the primary cytotoxic agent responsible for the biological effects of
the photo-oxidative process is singlet oxygen.
 Thus, the process of antimicrobial photodynamic therapy is
generally mediated by a type II reaction, which is accepted as the
major pathway in microbial cell damage

Photsensitizing agents:
 Most of the photosensitizers are based on the
tetrapyrrole nucleus, such as porphyrins,
chlorins, bacteriochlorins and phthalocyanines.
› toluidine blue O
› methylene blue
› erythrosine,
› chlorine e6 and
› hematoporphyrin

 In some instances, application of a photosensitizer may
not be required because photosensitizers occur naturally
within some microbial species.
 This is particularly true of the oral black-pigmented
species.
 It has been shown that broadband light ranging from 380
to 520 nm was able to achieve a threefold reduction in the
growth of P. gingivalis, P. intermedia, Prevotella nigrescens
and Prevotella melaninogenica in dental plaque samples
obtained from human subjects with chronic
periodontitis.(Soukos NS et al)

 Laser-assisted new attachment
procedure (the LANAP protocol) is a
surgical therapy designed for the treatment
of periodontitis through regeneration rather
than resection.
 In LANAP surgery, a variable free-running
pulsed neodymium:yttrium-aluminum-garnet
(Nd:YAG at 1064 nm wavelength) dental
laser is used.

 The laser energy selectively removes diseased
or infected pocket epithelium from the underlying
connective tissue. The necrotic epithelium is
stripped from the connective tissue at the
histologic level of the rete ridges. Since the laser
energy is quite selective for diseased tissue, the
underlying pleuropotential connective tissue is
spared, thereby permitting healing and
regeneration rather than formation of a pocket
seal by long junctional epithelium.

 Introduction
 LASER design
 Laser physics
 Types of lasers
› Diagnosis
› Wound healing
› LANAP
Laser safety

Eye protection
 Eye protection is important for the operator,
staff and the patient.
 CO2 laser: protection can be afforded with
clear safety glasses. Wet 2x2 gauze sponges
are placed over a patient’s eye.
 Nd:YAG laser: green safety glasses.
 argon laser: orange safety glasses.
 It is important to note that one cannot be
interchanged for the other.

Instruments to be used:
 Instruments that are highly reflective or that have
mirrored surfaces should be avoided as there could
be reflection of the laser beam.
 Lasers should not be used in the presence of
explosive gases.
 When general anesthesia is performed, a red
rubber and/or a metallically coated tube should be
employed rather than the usual PVC intubation
tube.

Protective clothing:
 Protective clothing such as gloves may be used especially
for the prevention of reflection from the impact of high
output lasers from the target areas.
 Black soft leather gloves according to photodetector
measurements afford more protection than similar gloves
of white leather.
 Barrier creams containing titanium di-oxide or zinc-oxide
also offers protection for the skin, especially skin adjacent
to the target area.

 Class I: is inherently safe.
 Class II: is safe during normal use; the blink reflex of
the eye will prevent damage.
 Class IIIa: involve a small risk of eye damage within
the time of the blink reflex. Staring into such a beam
for several seconds is likely to cause damage to a spot
on the retina.
 Class IIIb: can cause immediate eye damage upon
exposure.
 Class IV: lasers can burn skin, and in some cases,
even scattered light can cause eye and/or skin
damage.

 Lasers have become versatile and valuable
surgical instruments of late.
 However studies are required to widen the
horizons of laser therapy and its application
in periodontics.

 Carranza’s Clinical Periodontology 10th edition.
 Periodontology 2000,
 Vol. 51, 2009, 79–108
 Vol. 51, 2009, 109–140
 Vol. 55, 2011, 143–166
 Vol. 55, 2011, 167–188
 Vol. 55, 2011, 189–204
 Vol. 36, 2004, 59–97
 DCNA Jan2010
 http://en.wikipedia.org/wiki/Laser
 http://en.wikipedia.org/wiki/Laser_construction

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