for better understanding download videos of mechanism of laser formation from youtube for pg students

1. LASER IN DENTISTRY

2. outline
•Definition
•The invention of laser
•Early dental laser research
•Laser components
•Fundamental of laser
•Designs
•Basic principles
•Types of dental laser
•Applications
•Advantages
•Disadvantages
•Laser hazards
•Limitations

3. INTRODUCTION
• The word "laser" is an acronym for
Light
Amplification
by the
Stimulated
Emission
of
Radiation
• A device that creates a uniform and coherent light that is very
different from an ordinary light bulb.

4. • The use of light for t/t of various pathology:“PHOTOTHERAPY”
• In 1903, a Danish physician named Niels Finsen developed a
technique known as carbon arc phototherapy – t/t of lupus
vulgaris.
• The first laser was developed by Theodore H. maiman in1960.
• MASER – microwave amplification by stimulated emission of
radiation, 1st
reported in 1958 by Schawlaw and
Townes.

6. L stands for Light.
• Monochromatic.
– one specific wavelength of light (one specific color).
– The wavelength of light is determined by the amount of
energy released when the electron drops to a lower orbit.
• Coherent
– “organized” -- each photon moves in step with the others.
This means that all of the photons have identical wavelength
and frequency .
• Very directional
- A laser light has a very tight beam and is very strong and
concentrated and focused i.e. collimated

8. • These characteristics are very different from light from a
lightbulb.
• Lightbulb light:
– has many colors mixed together
– doesn't come in a narrow beam
– cannot be focused to as small a spot
– cannot be as intense as a laser without expending
tremendous amounts of energy.
• Lasers are special because they allow us to control light in
new and important ways.

9. A in laser stands for amplification
• Amplification means that a very bright intense beam of light can
be created.
• The laser may be activated by a few photons,
but then many, many more are generated.
• The initial light is amplified to make a very
bright compact beam.

10. S in laser stands for stimulated
• Stimulated means that the photons are amplified by stimulating
an atom to release more photons.
• An atom can exist in an excited state,
similar to a bow when it is stretched.
When the atom relaxes it emits a photon.

11. E in laser stands for emission
• Emission refers to the giving off of photons.
• The excited atom emits a photon when another photon comes
by.
• In 1917, Einstein described this process as Stimulated
Emission.
• The photons bounce between
the two mirrors until enough
photons have been emitted,
some pass through the
semi-silvered mirror on one end,
which are seen as the laser
beam.

12. R in laser stands for radiation
• It is a general term for anything that is radiated, or given off by
an object.
• For lasers, radiation refers to the photons which are being
emitted.

13. History and
development of
laser

14. EARLY DENTAL LASER RESEARCH
• Dental research began in 1963 at university of California at Los
angeles school of dentistry, with investigators Stern and
Sognnaes.
• RUBY LASER:
- 1st
laser constructed by Maiman
- Emitted light of 0.694µm.
- reported :
- development of cratering and glass like fusion of enamel
- penetration and charring of dentin(500-2000J/cm²)
(Stern, 1964)

15. • In 1974, Stern observed resistance to acid penetration into
enamel, suggesting role of laser in caries prevention.
• In 1965 – Taylor and Associates reported extensive
hemorrhagic necrosis and disruption of odontoblastic layer .
• CO2 laser: 1970
- more effective for hard tissues as its wavelength of 10,600 nm
is well absorbed by enamel.
High affinity for hydroxyapatite
- In 1984, Melcer et al reported successful t/t over 1,000
patients in clinical trails of caries removal and in1987,concluded
that laser could induce secondary dentin formation and
sterilization of dentin and exposed pulp.

16. • Neodymium laser:
- 1974, Yamamoto and Ooya in Japan
- Determined as an effective tool for inhibiting the
formation of incipient caries both in vivo and vitro.
•In 1995 FDA cleared a laser device for gingival surgery
•On may 7, 1997 FDA cleared the use of laser in treatment of tooth
decay and in 1998 October , given clearance for use in children

17. LASER COMPONENTS
• An optical cavity:
- 2 parallel mirror placed on either side
- Mirror(M1) is totally reflective and other Mirror(M2) partially transmissive
- photon bounce off the mirrors and re-enter the medium to
stimulate the release of electrons
• Laser medium:
- suspended as a gas, a liquid, a solid sate
- homogenous population of atoms or molecules pumped
up to the excited state
• A pump energy source
• Cooling system

18. BASIC PARTS OF A LASER
DEVICE
• The laser production device has the following parts:
1. Optical cavity: in which all the other components of laser
are housed
2. Active medium: the main component present in the core of
the optical cavity which helps in the production of light
3. External energy source: A flash lamp or electric arc device
4. Optical mirrors: one totally reflective and one partially
transmissive mirror
5. Optical resonator: Helps to prevent the scattering of
radiation in the optical cavity
6. Lens: helps in convergence of the light to a focal point.

20. LASER DELIVERY SYSTEM
• 2 delivery system
• hollow guide or tube
• flexible glass fiberoptic cable
– fragile and can not be bent sharply
– Various sizes of diameter
– Encased in resilient sheath
– Fit into hand piece with bare end or attached
glass like tip

21. • Laser action is explained by the theories of
quantum mechanics and thermodynamics
• Postulated by Danish physicist Bohr

25. Fundamental of laser
• To make the laser work, the material is excited or "pumped,"
with light or electricity.
The pumping excites the electrons in the atoms, causing them
to jump to higher orbits
"population inversion."
• Few of the electrons drop back
to lower energy levels spontaneously,
releasing a photon (quantum of light).

26. 1.High-voltage electricity causes
the quartz flash tube to emit an
intense burst of
light,exciting
some
of the
atoms
in the ruby crystal to
higher energy levels.

27. 2. At a specific energy level, some atoms
emit particles of light called photons. At f
irst the photons are emitted in all directio
ns. Photons from one atom
stimulate emission
of photons
from
other
atoms
and the
light intensity is rapidly
amplified.

28. 3. Mirrors at each end reflect the photons
back and forth, continuing this process
of stimulated emission
and amplification.

29. 4. The photons leave through the partially
silvered mirror
at one end.
This is laser
light.

30. Mode of light emission
• Continuous wave:
- beam emission is at one power level continuously as long
as the device is activated.
• Gated-pulse mode:
- periodic alteration of the laser energy being on and off
( few milliseconds)
• Free running pulse mode:
- large peak laser energy emitted for an extremely short time
span (µs) followed by long time laser off

31. CLASSIFICATION
OF
LASERS

32. 1. According to ANSI and OSHA standardization
Class I: Low powered lasers which are safe to view by the
naked human eye. Eg. Laser pointer device
Class II a: Low powered lasers which are hazardous if
viewed for more than 1000seconds by the naked eye. Eg
He:Ne lasers.
Class II b: Low powered visible lasers that are hazardous if
viewed for more than 0.25 seconds.
Class III a: Medium powered lasers that are normally
hazardous if viewed for more than 0.25 seconds without
the use of magnifying optics.
Class III b: Medium powered lasers (0.5 W max.) which are
hazardous if viewed directly.
Class IV: High powered lasers (> 0.5 W) which produce
ocular, skin and fire hazards.

33. 2. Based on wavelength:
Ultraviolet lasers (140- 350nm)
Visible lasers (350-750nm)
Infra red lasers (750nm and above)
3: Based on penetration power:
I-- Hard lasers/ Thermic lasers/ Surgical lasers
II-- Soft lasers/ Athermic lasers
4. Based on pulsing as:
I--Pulsed lasers
II--Non pulsed lasers

34. 5. Based on the type of active medium used:
Gas lasers: a gas or mixture of gases is used as
active medium Eg: He: Ne lasers, CO2 laser
Liquid lasers: Ions of rare earth or organic
fluorescent dye dissolved in liquid are used as
active medium. Eg: Dylase
Solid state lasers: Solid material are used as
active medium eg: Ruby lasers, Nd:YAG lasers.
Semiconductor lasers: Semiconductor materials
are used as active medium. Eg: Gallium
-arsenide laser

35. STATE MEDIUM
Gas- CO2 , Argon laser CO2 ,Nitrogen, Helium gases
Solid state-
Nd:YAG
Er:YAG
Ho:YAG
Yttrium, Aluminium, Garnet
crystals ( Neodymium,
Ergium, Holmium)
Semiconductor- Diode laser
semiconductor chips work
like electrode
- layer of p-type material (carrier of
+ve charge or electron holes), a
nonconductive band gap layer
(junction), a layer of n-type material
( carrier of –ve charge or free
electrons.)

36. Most commonly used Lasers in dentistry
CO2
Er:YAG(erbium-doped yttrium aluminium garnet)
Nd:YAG(neodymium-doped yttrium aluminium garnet)
Diode
Argon

37. • To be continued…….

38. • First laser used routinely for
soft tissue surgery in dentistry.
• Since the human body contains about 85 % water and the
value for soft tissue is even higher, the CO2 laser will be
absorbed in the water part of all soft tissues.
• Wavelength-10,600nm
• Deliver through a hollow tube like wave guide in continuous or
gated pulse mode

39. suitable for application of teeth
• sealing of pits and fissures
• welding of ceramic material to enamel
• prevention of dental caries
• Used in non contact manner for tissue ablation
heat diffusion and heat accumulation occurs.
coagulation of small blood vessels in the depth of the tissue
prevents bleeding from those vessels

40. Irritation fibroma on buccal
mucosa
Excisional biopsy with co2 laser
Underlying surface dry, no suture placed 6 wks after surgery

41. Maxillary midline frenum causing
pull on marginal and interdental
papillae.
Immediately after co2 lasing, the
char layer and lack of suture
2mnths after surgery

42. Advantages of the CO2 laser
• less or no bleeding, resulting in a dry
surgical field
• reduction of surgical time due to better
visibility
• reduced swelling
• reduced pain due to the fact that
superficial nerve endings are
coagulated
• less or no sutures, resulting in shorter
treatment time
• less scaring.
It was reported the use of the CO2 laser was unfavourable
because of the loss of the odontoblastic layer (Wigdor et
al., 1993)

43. • Wavelength-2940nm( coincides with the absorption
peak of water)
Excellent absorption in apatite crystals and water
• With Er:YAG laser, minimal thermal damage to
dentin seen, and removed infected and softened
carious dentin to the same degree as the
bur treatment.
• The advantage of these lasers for soft tissue is that, with
very high absorption by water, only a few layers of
tissue are removed with each pulse of laser energy, so
removal and reshaping can proceed with precision

44. APPLICATION
• Caries detection and removal
• Removal of dental fillings
( composite and GIC )
Amalgam Χ – potential release of mercury vapour
• Removal of gold and ceramic fillings – not possible
• Apiectomy, osteotomy of bone, impacted teeth – excellent bone
healing capacity.
• Laser irradiation adjacent to pulp
local damage occurs = mechanical injury by burs.

45. • Caries prevention :
• Laboratory studies shown laser t/t of enamel can inhibit
caries progression by 50%.
• One time laser t/t = daily fluoride t/t
• laser irradiation of dental hard tissues modifies the
calcium to phosphate ratio, reduces carbonate to
phosphorous ratio, and leads to the formation of more
stable and less acid soluble compounds.
• Threshold pH for enamel dissolution was reportedly
lowered from 5.5 to 4.8 and the hard tooth structure was
four times more resistance to acid dissolution.

46. • Wavelength-1045nm
• Solid medium, a crystal of yttrium- aluminum and garnet
doped with neodymium
• readily absorbed in blood and tissue pigment
• These instruments are ideal both for the treatment of
periodontitis and for excisions of vascularized lesions
(excellent hemostatic ability).
• Their energy is transmitted through water, and are very
minimally interactive with hard tissue
• Applications similar.

47. BDJ, VOL 187, 1999
- Laser soft tissue surgery was well accepted by child patients.
- The Nd:YAG laser is a very useful additional clinical tool for dentists treating
children.

48. • A crystal of yttrium-aluminum garnet doped with holmium
• Wave length- 2120 nm
• High affinity to H2O absorption by soft tissues
• Useful for soft tissue excision
• Less affinity for pigmented tissue and tooth structure
• Frequently used for arthroscopy in TMJ
• Compared to CO2 Laser – Ho:YAG offers better
homeostasis and is safe and effective to use bone and
cartilage.

49. PortablePortable
No special power
No cooling connection
No heat
Quiet
AffordableAffordable
More powerful, less traumatic
wavelenght-800-980nm, invisible
Well absorbed by soft tissue and poorly absorbed by
hard tissues
Expand PracticeExpand Practice
•Gingival contouring
•Sulcular debridement
PortablePortable
No special power
No cooling connection
No heat
Quiet
AffordableAffordable
More powerful, less traumatic
wavelenght-800-980nm, invisible
Well absorbed by soft tissue and poorly absorbed by
hard tissues
Expand PracticeExpand Practice
DIAODE LASER
SEMICONDUCTOR LASER change
electric energy to light energy
Gallium Arsenide chip and Al
Delivery system-fibroptically in
continuous wave or gated pulse
Portable
No special power
No cooling connection
No heat
Quiet
Affordable
More powerful, less traumatic
wavelength-800-980nm, invisible
Well absorbed by soft tissue and poorly
absorbed by hard tissues

50. • Wavelength - 488nm and 514nm
peak absorption in red pigments and tissues with abundance
Hb, hemosiderin and melanin.
• Enamel and dentin – not well absorbed, poorly absorbed by
water.
• Tissues effects – thermal nature
• Specific uses :
1. Root planning and curettage – photocoagulation and
vaporization of tissues within periodontal pockets.
2. Gingival retraction – excellent homeostasis and
coagulation

51. • creates a tissue temp. 90ºC - 100ºC coagulate the blood
vessels and remove the sulcular epith.
3. Gingivectomy and gingivoplasty
4. Oral lesion therapy: removes the surface epithelium and
necrotic tissues, disinfect the wound
laser is applied until lesion has dessicated appearance
and necrotic cells have glazed appearance.
5. Tissue welding : arterial welding
adv : preserve the mechanical properties of tissues and
decrease hyperplasia
6. Used for curing composite.

52. Lichen planus on buccal
mucosa
Blistering of the tissues by
laser
After blistering lesion
peeled away
Immediately after peeling, a light char
layer, left to heal by secondary intention. 12wks later, postoperatively

53. Labial hemangioma Excision of lesion
Postoperative appearance, complete
hemostasis
2weeks postoperatively, normal
appearance

54. Biolase Waterlaser
• Developed in 1998, October, Doctor Haselhorst
• Uses a process which gently washes away
decay with laser-energized water droplets.
• Hydrokinetic energy is produced by combining
a spray of atomized water with laser energy.
• The result is the energized water gently and precisely
removes a wide range of tissue including tooth enamel, and
soft tissue (gum tissue) with no heat or discomfort in most
cases.

55. • The Waterlase laser does not require being pressed on
to the tooth, so this discomfort is not experienced.
• Modern dentistry now has a dental laser made by
Biolase which allows the dentist to perform certain
procedures without anesthesia.
• Quick and painless
DRILL-LESS
DENTISTRY

57. EXCIMER LASER
• It is the only one laser that offers precise ablation of tissues,
fiber delivery, bactericidal effects, good transmission through
water and enamel surface conditioning in one system.
• 308nm
• Very expensive and time consuming
• Used for RCT
• Temp.elevation within pulp chamber ≤180ºC
• Produces opening of dentinal tubules free of smear layer or
necrotic tissues, and allow O2 and medicinal fluids to enter
the tubuli and apical delta.
not possible with conventional procedures.

58. Laser effects in dentistry
Factors which determine the interaction are:
•Wavelength of laser
•Power density
•Difference in delivery system
Tissue factors which determine the effect of laser include:
•Chemical composition
•Spatial structure
•Isotropic composition
Radiant energy interacts with the tissue in 4 different ways:
– A portion may be reflected without any interaction
– A portion may be transmitted
– A portion may be absorbed
– A portion may be absorbed and scattered without
producing any useful effect

59. Laser effects in dentistry

60. Absorption
• Amount absorbed energy depends on tissue
characteristics:
– Pigmentation
– Water content
– Laser wavelength
– Emission mode

62. Absorption characteristics of
dental lasers

63. Reflection
• No effect on target
tissue.
• E.g; caries detecting
laser device.
• Laser beam becomes
more divergent with
increasing distance
from the handpiece.

64. Scattering
• Weakening the
intended energy
• No useful biologic
effect.
• Heat transfer to
adjacent tissue:
unwanted damage.
• One advantage:
facilitate curing of
composite resin or
covering broad area.

65. Laser effects

66. Transmission
• Depends on the wavelength of laser light
• Depth of beam varies with speed of
movement and power density.

67. Tissue effects can be of 4 types:
•I. Photochemical interaction --- Biostimulation
--- Photodynamic therapy
•II. Photothermal interactions---Photoablation
---Photopyrolysis
•III. Photomechanical interactions---Photodisruption
---Photoaccoustic
•IV. Photoelectrical interactions
Biologic interactions of laser photons with the tissue occurring
along the radiation are termed as linear effects.
Linear effects can be of 3 types --Photochemical, Photothermal
and Photomechanical.
The ability of laser light to produce a biologic response after
being reflected, deflected, scattered or absorbed are called as
non linear effects.

68. Laser effects in dentistry
• Oral soft tissue is largely composed of water which
predominantly controls the tissue effects of lasers in the
infrared spectrum.
• Tissue elements which exhibit a high coefficient of absorption
for a particular wavelength are called as chromophores. Other
chromophores in the tissue may include hemoglobin, melanin
etc Hemoglobin readily interacts with 488-514nm
wavelengths, thus accounting for the greater ability of argon
laser for coagulation and hemostasis. In soft tissue, the
effects of laser are quiet predictable as compared to hard
tissues.

69. Laser effects in dentistry
• Thermal effects:
- 45ºC - 60ºC : Denaturation
- >60ºC : Coagulation and necrosis
- 100ºC : Water inside the tissues vaporizes
- >300ºC :Carbonization and pyrolysis ( muller et al, 1990).
• Mechanical effects:
- photoablation fast thermal explosion
mechanical shock waves
- photodisruption nonlinear tissue behaviour
optical breakdown
mechanical shock waves

70. • Chemical effects:
- alteration in the chemical and physical properties of the
irradiated tissues
• Laser interaction with living tissues is very complex
mechanism and not yet completely understood.
• Biologic effects of laser on dental tissues depends on a
number of factors
- properties of laser itself ( wavelength, energy density and
pulse duration)
- optical properties of hard tissues.

71. EFECTS ON HARD TISSUES
• Microcracks and zone of necrosis
• Carbonization
• Cracks on enamel and dentin
• Microhardness of dentin increases
• Organic matrix burns off
• Crystalline structure of HA changes
• Transformation of apatite to tricalcium phosphate
• Inhibition of enamel subsurface demineralization
prevention of dental caries
(Yamamoto and Ooya , 1974)

73. EFFECTS ON DENTAL PULP
• Recent evidence suggests that a normal odontoblastic layer,
stroma and viable epithelial root sheath can be retained
following laser radiation provided damage threshold energy
densities are not exceeded i.e < 60 J/cm²( Abt el at, 1992)
• If pulp temp > 5ºC , odontoblastic layer may not be present.
• Use of air and water combination before, during or
immediately after laser irradiation may be effective for temp.
control and reduction of heat transfer to the pulp.
• Continous wave – pulpal necrosis, but pulsed mode may
result in new dentin formation ( Melcer et al, 1987)

74. LASER HAZARDS IN DENTAL
PRACTICE
As Martin Strassl said
“Only twice you can make
mistake with Lasers, First
you loss one eye and second
your other”

75. LASER HAZARDS IN DENTAL PRACTICE
• Ocular injury:
- retinal and corneal injury
( 400 – 780nm visible, 780 – 1400 infrared)
• Tissue hazards:
- >21ºC above normal body temp cell destruction and
denaturation of cellular enzymes and proteins
- Happens if by mistake hands come in the way of path of laser
- Should change the laser to the standby mode whenever
interruption in laser use is encountered

76. • Environmental hazards:
- inhalation – resp. system
- Smoke, the byproduct of laser surgery
- Laser plume
– Steam, carbon particles and cellular product
– Contains many toxic substances such as
formaldehyde, hydrogen cyanide
Use of high volume laser smoke evacuation

77. Combustion hazard
• Flammable solids, liquids and gases within the surgical
settings
• Particular concern : flammable gases and endotracheal tubes
due to their proximity during head and neck procedures.
• Use of polypropylene surgical gloves/drapes and use of laser
safe endotracheal tubes
Electrical hazards:
• Grouped as electrical shock hazards/ electric fire hazard/
explosion
• Insulated circuitry, shielding, grounding, housing of high
voltage electrical components – adequate protection

78. LASAR HAZARDS CONTROL MEASURE
• Recommended by ANSI
• Personal protection
- eyewear ( goggles and
safety glasses, saline
soaked gauze)
- clothing and masks
• Administrative controls
- standard operative
procedures
- warning signs
- protective devices
- training and education
• Engineering controls
- equipments label
- key switch
- protective housing
- warning systems
- beam enclosures
• Special controls
- fire and explosion
- repair and maintenance
- fibre optic delivery system

79. ADVANTAGES
May cause less pain in some instances, therefore,
reducing the need for anesthesia
May reduce anxiety in patients uncomfortable with the
use of the dental drill
Minimize bleeding and swelling during soft tissue
treatments
May preserve more healthy tooth during cavity removal

80. DISADVANTAGES
Lasers can't be used on teeth with fillings already in place.
Lasers can't be used to fill cavities located between teeth,
around old fillings, and large cavities that need to be prepared
for a crown. In addition, lasers cannot be used to remove
defective crowns or silver fillings, or prepare teeth for bridges.
Traditional drills may still be needed to shape the filling, adjust
the bite, and polish the filling even when a laser is used.
Lasers do not eliminate the need for anesthesia
Laser treatment are more expensive since the cost of the laser
is much higher than a dental drill. ( $39,000 and $45,000
compared to about $600 for a standard drill).

81. Laser diagnostic
• Laser Doppler Flowmetry
- To monitor pulpal and gingival blood flow
- To assess tooth vitality
• Laser Fluorescence for detection of caries
• Laser Doppler Vibrometry to measure tooth
mobility.

82. Laser Fluorescence (DIAGNOdent)
• Detection for occlusal and smooth surface caries.
• Uses diode laser light sources and a fiber-optic cable that
transmits the light to a hand-held probe with a fiber optic eye
in the tip.
• Emitted fluorescence is collected at the probe tip, transmitted
through ascending fibers, and processed and presented on a
display window as an integer between 0 and 99.
• fluorescence : carious state, > 20
• Results in vitro studies indicated diagnodent
readings show a very good correlation with
histologic evidence of caries but not with the depth of the
lesion into dentin.

83. Hard tissue application
• Selective removal of caries -Nd:YAG,CO2 laser, Er:YAG,
excimer ,Waterlase
• Cavity preparation : Excimer,Nd:YAG,Er:YAG*,Waterlase
• Pit &Fissure sealant : Er;YAG
• Composite curing: Argon laser(488nm) (5 secs),
Bond strength and surface adhesion is ↑

84. • Bleaching : Argon, Nd:YAG and CO2
• Laser light is converted to heat as it strikes
the bleaching gel accelerate the oxidation of
peroxide
• Immediate result and more convenient
improved appearance

85. • Pulpal therapy
- time consuming and messy
laser amputed pulp stumps hemostasis,
bactericidal effects, surface coagulation.
- fiberoptic system ( fibers size 200µ), highly flexible and
introduced to the apex.
- Research with Nd:YAG and co2 laser has verified the
value of avoiding formacresol.

86. Pulp capping and pulpotomy
• CO2 laser is used because
– Arrest bleeding
– Disinfect dentinal exposure of 1sqmm size
– Success rate is 91% in younger group compared to 68%
where Ca(OH)2
– Pulpotomy has shown higher success rate
Excimer, Ar, Nd:YAG, Er:YAG, Ho:YAg
• In 1996, Wilkerson et al evaluated the clinical, radiographic
and histologic effects of argon laser on vital pulpotomy
and the results showed that all soft tissues remained
normal and all teeth exhibit normal mobility.
• Reparative dentin formation was noted histologically.
(J Clin Las Med and Surg,1996,14).

87. When a fistula is present
laser fiber is passed thru the fistula canal to the site of the
abscess formation.
disrupt the infection temporarily and reduce the symptoms
• In 1985, Ebinara reported the effects of Nd:YAG laser on
the wound healing of amputated pulps and
reported better healing in pulps exposed
to laser than in controls in 1st
week and
facilitation of dentinal bridge formation in
5th
and 12th
postoperative weeks.
(J Conserv Dent,32,1989)

88. Root canal wall preparation by laser
• Straight and slightly curved canals
• The laser tip slide gently from the apical portion to the
coronal portion pressing the laser tip to the canal wall
under spray.
• When laser is unable to be inserted into the canals, t/t
should be carried out after usual root canal preparation
using reamers and files.

89. • Various studies have shown the smear layer was removed
completely and the dentinal tubules on the root canal wall
were opened using this technique.
• Rooney et al reported sterilization rates of 80%- 90%
whereas others reported 60% depending on the condition
of the root canals, type of laser, technique and application
parameters.
• Levy reported that and experimental Nd:YAG laser system
was more effective in cleaning and shaping root canals
than conventional hand instrumentation.( J Endod 1992 ;
18)S

90. • First used in Endodontics by Weichman and Johnson in
1971 who attempted to seal the apical foreman using a CO2
• Takeda et in 1999 used Er:YAG to disinfect canals. The
irradiated canals showed no smear layer and open tubules
in the apical and middle 3rd
• L. Bergams et in 2004 used Nd: YAG against Actinomyces
Naeslundi and S.Anginosus were discernable but only 99%
of E.facelis were killed, a complete sterilisation was not
achieved.

92. ROOT CANAL FILLING BY GUTTA PERCHA AND LASER
• GP is thought to be melted by laser heat energy.
• Anic and matsumoto(1995) attempted to perform root
canal filing using sectioned GP segments and a pulsed
Nd:YAG laser
• This was shown to be possible by vertical condensation
method, but time required is too much.
• At present, the technique is not practical, requires further
research.

93. DESENSITIZATION OF HYPERSENSITIVY OF
DENTIN AND TEETH BY LASER STIMULATION
• Laser devices: semiconductor diode laser, pulsed Nd:YAG
laser, CO2 laser
• Procedure:
after drying the hypersensitive dentin, the laser tip is placed
in direct contact with the tooth surface, which is then
irradiated for a period of 30 secs – 3mins.
• Clinical assessment after a postoperative period of 4months,
73% of cases of slight cervical dentin hypersensitivity, 19% of
mild cases, and 14% cases of severe pain showed a reduction
in hypersensitivity.

94. • The mechanism of pain reduction by the laser stimulation
is thought to be clarified by electrophysiologic and laser
transmission studies.
indicates local changes around the dentin and the nerve
endings as well as changes in the central pulp neuron.
• Recently Gelskey et al reported that Nd:YAG laser reduced
thermal dentinal desensitivity by 58% and mechanical
stimulation by 61%.

95. limitation
• Special training and attention for
safety
• No single laser can perform all
desired dental application
• Expensive

96. Refrences
Laser in Dentistry, Leo J.Miserendino/Robert M.pick, 1995
Laser in dentistry: Dental clinic of North America Vol.44,no. 4 Oct. 2000
Naresh Thukral; Laser in General Dental practice: SOLEZE-Journal of Laser
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