Full description of use of laser in prosthodontics...Laser advantages and disadvantages...laser hazards and its management....lasers used in dentistry

1. Presented by:
Dr. Jehan Dordi
2nd Yr. MDS
LASERS IN PROSTHODONTICS
1

2. CONTENTS
2
• Introduction
• History
• Difference between light and laser
• Classification of laser
• Most commonly used lasers in dentistry
• Basic laser science
• Components of Laser
• Dental Laser Wavelength
• Laser delivery system
• Laser interaction with tissue
• Photobiologic effects
• Advantages & Disadvantages of Laser over other techniques

3. 3
• Laser type used in tissue therapy
• Laser unit
• Application of Laser in removable prosthodontics
• Application of Laser in Fixed prosthodontics
• Application of Laser in Implantology
• Application of Laser in Maxillofacial rehabilitation
• Application of Laser in Dental Laboratory
• Risk associated with laser use
• Laser safety measure
• Laser safety classification
• Review of Literature
• Conclusion
• References

4. INTRODUCTION
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5. 5
• In this era of high-tech devices, the dentists are being offered many
sophisticated products designed to improve the quality of treatment rendered to
patient.
• Already frequently used in the medical field, laser has begun to revolutionize
dentistry.
• Laser is the acronym for “Light Amplification by Stimulated Emission of
Radiation” named by Gordon Gould in 1957.

6. 6
• The use of lasers in dentistry has increased over the past few years.
• The first laser was introduced into the fields of medicine and dentistry during
the 1960s.
• Since then, this science has progressed rapidly. Because of their many
advantages, lasers are indicated for a wide variety of procedures.

7. HISTORY
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8. 8
Year Event
1957 Gordon Gould coined the term “Laser”
1960 T.H Maiman invented the first ruby laser using a ruby rod placed in an aluminum
cylinder with reflective internal surfaces
1960 Javan, Bennett and Herriott invented the helium-neon laser
1964 Marcos and Van developed the Neodymium doped yttrium-aluminium-garnet laser
1964 Patel developed the carbon dioxide laser
1966 Sorokin and Lankard developed the dye laser
1963-
1967
Leon Goldman reported on the effects of laser on teeth, caries and other tissues
1990 Terry D Myers and William D Myers developed a laser exclusively for dental
application, the D-Lase 300 (Nd:YAG laser); doped by BIOLASE technology in
2003

9. DIFFERENCE BETWEEN LIGHT AND LASER
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10. 10
Light Laser
Polychromatic (Visible light is the sum of many
colors of the visible spectrum and is thus 'diffuse)
Monochromatic (Laser light is monochromatic in that it
consists of a single color.)
Non-coherent Coherent (Laser light is coherent, i.e., the waves of light
produced by a laser are identical in size and shape; identical
amplitude and frequency of photons)
Non-collimated Collimated (The waves of light produced from a laser are
directed parallel to each other, i.e., focused)
Low energy High energy (Due to coherence and collimation the laser
light has a higher energy output than conventional diffuse
light.)

11. CLASSIFICATION OF LASERS
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12. 12
According to ANSI and OHSA standards lasers are classified as:
• Class I- These are low powered lasers that are safe to use. e.g. Laser beam
pointer .
• Class II a- Low powered visible lasers that are hazardous only when viewed
directly for longer than 1000 seconds, e.g. He-Ne lasers
• Class II b - Low powered visible lasers that are hazardous when viewed for
more than 0.25 seconds.

13. 13
• Class III a - Medium powered lasers that are normally hazardous if viewed for
less than 0.25 seconds without magnifying optics.
• Class III b - Medium powered lasers that can be hazardous if viewed directly.
• Class IV - These are high powered lasers (> 0.5 W) that produce ocular skin
and fire hazards.

14. DIFFERENT TYPES OF LASERS USED
IN DENTAL TREATMENT
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15. 15
• Traditionally, lasers have been classified according to the physical construction
of the laser (e.g., gas, liquid, solid state, or semiconductor diode), the type of
medium which undergoes lasing (e.g., Erbium: Yttrium Aluminium Garnet
(Er:YAG)).

16. 16
Several types of lasers are available based on the their uses.
• The Er:YAG laser possesses the potential of replacing the drill.
• CO2 laser can be used to perform gingivecotomy and to remove small tumor's.
• Argon laser is used in minor surgery.
• Nd:YAG is used in tissue retraction, endodontics and oral surgery.
• The diode laser is effective for oral surgery and endodontic treatment. This
laser helps to correct aesthetics flaws. It is used for soft tissue procedures.

17. MOST COMMONLY USED LASERS IN
DENTISTRY
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18. 18
Erbium laser:
• The erbium family of laser has two wavelengths,
• Er:Cr:YSGG (yttrium scandium gallium garnet) lasers and
• Er:YAG (yttrium aluminium garnet) lasers.
• Erbium:Chromium:YSGG (2780 nm) has an active medium of a solid crystal of
yttrium scandium gallium garnet that is doped with erbium and chromium.
• Erbium:YAG (2940 nm) has an active medium of a solid crystal of yttrium
aluminium garnet that is doped with erbium.

19. 19
• The erbium wavelengths have a high empathy for hydroxyapatite and the
highest absorption of water in any dental laser wavelengths.
• Therefore, the laser of choice for treatment of dental hard tissues.
• In addition to hard tissue methods, erbium lasers can be used for soft tissue
ablation because the dental soft tissue carry a high percentage of water.

20. 20
Carbon Dioxide laser:
• The CO2 laser is a gas-active medium laser that includes a sealed tube holding a
gaseous mixture with CO2 molecules raised via electrical discharge current.
• The light energy, whose wavelength is 10,600 nm, is placed at the end of the
mid-infrared invisible non-ionizing portion of the spectrum, and it is delivered
through a hollow tube-like wave guide in continuous or gated pulsed mode.

21. 21
• The CO2 laser wavelength has a very high empathy for water, occurring in
rapid soft tissue removal and hemostasis with a shallow depth of penetration.
• Although, it has highest absorbance of any laser, disadvantages of the CO2
laser has large size and high cost and hard tissue injurious interactions.

22. 22
Argon
• Argon is laser with an active medium of argon gas that is energized by a high-
current electrical discharge.
• It is fiber-optically delivered in continuous wave and gated pulsed modes and
is the only available surgical laser device whose light is radiated in the visible
spectrum.
• There are two emission wavelengths used in dentistry:
1. 488 nm, which is blue in colour, and
2. 514 nm, which is blue-green.

23. 23
Neodymium Yttrium Aluminum Garnet Laser
• Nd:YAG has a solid active medium, which is a garnet crystal combined with
rare earth elements yttrium and aluminum, doped with neodymium ions.
• This active medium is much different than the semiconductor wafer of the
diode laser, and the pumping mechanism is a flash lamp.

24. 24
• The Nd:YAG wavelength is highly absorbed by the pigmented tissue, which
make a very beneficial surgical laser for cutting and coagulating dental soft
tissues, with good hemostasis.
• The available dental models have an emission wavelength of 1064 nm, which is
in the invisible near-infrared portion of the electromagnetic spectrum.
• In addition to its surgical applications there has been assessing for using the
Nd:YAG laser for non-surgical cellular debridement in periodontal disease and
the Laser Assisted New Attachment Procedure (LANAP)

25. 25
Diode Laser:
• The Diode is a solid active medium laser, manufactured from semi-conductor
crystals using some combination of aluminum or indium, gallium, and arsenic.
• This “chip” of material has optical resonator mirrors joined to its ends, and an
electrical current is used for pumping mechanism.

26. 26
• The available wavelengths for dental use range from about 800nm for the
active medium containing aluminum to 980 nm for the active medium
composed of indium which is putting them at the starting of the near infrared
portion of the invisible nonionizing spectrum.
• Each machine delivers laser energy fiber-optically in continuous wave and
gated pulsed modes and used in contact with soft tissue for surgery or out of
contact for deeper coagulation.

27. BASIC LASER SCIENCE
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28. 28
• The light wave produced by a laser is a specific form of electromagnetic energy
that behaves as a particle and a wave.
• The basic unit of energy is called a photon. The wave of photons produced by a
laser can be defined by 3 measurements, namely:
1. Velocity i.e. speed of light
2. Amplitude (intensity in the wave) - this is the total height of the wave oscillation from the
top of the peak to the bottom of the vertical axis. Larger the amplitude greater is the
performable work
3. Wavelength - this is the distance between any two corresponding points on the wave on
the horizontal axis

29. 29
• Laser light occurs through the amplification of stimulated emission.
• Amplification is part of a process that occurs inside the laser.
• Identifying the components of a laser instrument is useful in understanding how
light is produced.

30. COMPONENTS OF A LASER
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31. 31
• The laser device consists of three active components which produce laser light:
• Active medium
• Pumping mechanism
• Optical resonator
• These three components are collectively referred to as the 'Laser Cavity' (the
center of the laser device)

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Active Medium
• Core of the laser device: may be a solid crystal (Er:YAG; or solid state
semiconductor —diode lasers) or a liquid (dye lasers) or a canister of gas (CO2
laser); Lasers are generally named after the active medium.

33. 33
Pumping Mechanism
• Excitation source could be a flash lamp, electrical circuit or coil. This emission
of energy is multiplied by the process known as "Stimulated emission"
postulated by Albert Einstein in 1916.
• When the outer level electrons are at a higher energy state the excitation source
continues to pump energy around the active medium which results in the already
energized electron absorbing more energy and releasing in two quanta of energy
during conversion to a lower energy state.
• This results in a progressive amplification of the emitted energy which results in
the laser beam .

34. 34
Flowchart of Pumping Mechanism in Laser

35. 35
Optical Resonator
• Consists of two mirrors placed at each end of the laser cavity placed parallel to
each other.
• These mirrors are called optical resonators because they reflect the waves back
and forth and amplify the developing beam.
• One of these mirrors (the one at the collimation end) is partially transparent
allowing the laser beam to be projected outside. the laser cavity.

36. SECONDARY COMPONENTS
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Cooling System
• Heat production is a by-product of laser light propagation.
• It increases with the power output of the laser and hence, with heavy-duty
tissue cutting lasers, the cooling system represents the bulkiest component.
• Co-axial coolant systems may be air- or water-assisted.

37. 37
Control Panel
• This allows variation in power output with time, above that defined by the
pumping mechanism frequency.
• Other facilities may allow wavelength change (multilaser instruments) and
printout of delivered laser energy during clinical use.
Focusing Lens
• Radiation - refers to the light waves produced by the laser as a specific form of
electromagnetic energy.

38. DENTAL LASER WAVELENGTH
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39. 39
• Dental laser systems currently available use emission wavelengths ranging
from 500 to 10,600 nm which places the lasers in the visible or in the infrared
portion of the spectrum.
• This wavelength range is non-ionizing and does not have any mutagenic effect
on cells.

40. 40
Visible light systems
• Argon laser— 488 nm/514 nm
• Frequency double Nd:YAG laser/Potassium Titanyl Phosphate (KTP) 532 nm
• Low level lasers
• Photobiomodulation—600-635 nm
• Caries detection —655 nm

41. 41
Infrared systems
• Diode lasers— 800-1064 nm
• Aluminium Gallium Arsenide —810 nm
• Gallium Aluminium Arsenide—940 nm
• Indium Gallium Arsenide—980 nm
• Indium Gallium Arsenide Phosphate —1064 nm
• Neodymium doped Yttrium Aluminium Garnet (Nd:YAG lasers) — 1,064 nm.
• Erbium—Chromium doped Yttrium Scandium Gallium Garnet (Er:Cr:YSGG)
—2,780 nm.
• Erbium doped Yttrium Aluminium Garnet (Er:YAG lasers)— 2,940 nm
• Carbon dioxide (CO2 lasers) —9,300 nm and 10,600 nm

42. LASER DELIVERY SYSTEMS
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43. 43
Fiber-optic delivery
• It is used for shorter wavelength systems (KTP, Diode Nd: YAG systems)
• Longer wavelengths such as Erbium and CO2 lasers are absorbed by water and
cannot be used with fiber-optic tips.
• The following systems are used for longer wavelength lasers:
• Articulated arm delivery system
• Hollow waveguide delivery system

44. 44
• Laser tips may contact target tissue (contact type) or oriented at a distance
away from tissue (non-contact type).
• Contact type lasers have quartz or sapphire tips.

45. 45
Spot Size:
• The point where the energy of the laser beam is highest is termed as the 'Focal
point'. For contact type lasers this focal point is at the tip of the laser.
• For CO2 lasers (noncontact type) the focal point may be 1-2 mm from the tissue
surface. This allows for a range of interactions with target tissue.
• Focused beam —focal point in contact with target tissue- Excision and
Incision.
• Defocused beam—focal point away from tissue - divergent
• Small distance from tissue — Ablation
• Larger distance from tissue—Haemostasis

46. 46
Emission Modes
• Constant emission (Continuos Wave mode)
• Pulsed emission (Gated Pulse mode)
• Super pulse/Ultra speed
• Free running pulsed mode
Continuous Wave Mode
• The beam is emitted at one power level for as long the switch is pressed.
Gated Pulse
• Periodic alterations of laser energy (laser emission as a short pulse followed by
a pause before another pulse is produced).

47. 47
Super pulse mode
• It is a form of gated pulse where the pulses are produced by a shutter opening
and closing in front of the emitted laser beam.
Free-running pulse
• It is a form of gated pulse where the pulses are produced by manipulation of
the pumping mechanism (rapid pulsing of flash lamps around the active
medium); also known as “True Pulse mode”.

48. LASER INTERACTIONS WITH
TISSUE
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49. 49
Reflection
• Beam is redirected off the surface upon contact with target tissue; one
important consequence of this interaction is that the reflected beam may
contact the operator's eyes.
• To avoid this wavelength specific glasses with side shields should be worn.
• An example of such a situation would be the reflection of CO2 laser from
titanium implant surfaces.

50. 50
Absorption
• Beam is imbibed by the target tissue mostly (desirable effect); absorption is
dependent on the tissue characteristics such as pigmentation and water content
and on the laser wavelength.
Transmission
• Beam passes through the target tissue with no effect on the tissue; highly
dependent on the laser wavelength; water is completely transparent to shorter
wavelengths (diode and Nd:YAG) whereas it readily absorbs longer
wavelengths.

51. 51
Scattering
• Beam is spread throughout the target tissue; weakens the intended energy; heat
transfer adjacent to the surgical site with potential for tissue injury.
• The composition of target tissue and laser wavelength determine the amount of
absorption. The primary absorbers of laser energy are called “Chromophores”.
• Water present in all biologic tissues readily absorbs longer wavelengths (Erbium
and CO2) whereas hemoglobin and pigments (melanin) readily absorbs shorter
wavelengths (diode and Nd:YAG).

52. 52
Penetration Depth
• It depends on laser wavelength. Longer wavelengths are absorbed by water and
the laser energy is scattered resulting in lesser penetration depth; shorter
wavelengths possess more penetration depth.
Extinction Length
• Thickness of substance in which 98% of energy from laser is absorbed. A large
extinction length means that the laser penetrates deep into tissue. Shorter
wavelengths (Nd:YAG) have larger extinction lengths.
Energy Density
• Amount of energy per square millimeter of tissue; also known as fluence.
• Inversely proportional to spot size
• Smaller spot sizes = Larger fluence

53. PHOTO-BIOLOGIC EFFECTS
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54. 54
• They are mainly of 3 types
1. Photothermal effect
2. Photochemical effect
3. Photoacoustic effect

55. 55
Photothermal Effect
• The principle effect of laser energy is photothermal, i.e. the conversion of light
energy into heat.
• The rate of temperature rise plays an important role in this effect and is
dependent on several factors such as
• Cooling of the surgical site
• Ability of the surrounding tissues to dissipate heat
• Various laser parameters such as emission mode, power density and the time of exposure.

56. 56
• With regard to surgical laser-tissue interaction with soft tissue:
• Absorption of incident energy leads to generation of heat
• Ascending heat levels leads to dissociation of covalent bonds (in tissue proteins), phase
transfer from liquid to vapor (in intra and intercellular water), onto phase transfer to
hydrocarbon gases and production of residual carbon.
• Heat generation can lead to secondary effects through conduction.

57. 57
• Assuming a correct incident wavelength, using correct delivery parameters, a
central zone of tissue ablation is surrounded by an area of irreversible protein
denaturation.
• Surrounding this, along a thermal gradient, a reversible, reactionary zone of
edema will develop.
• The depth and extent of this tissue change will differ with laser wavelength,
being more superficial in nature with longer wavelengths, with less edema, and
deeper with greater edema with shorter wavelengths.

58. 58
• The physical change in target tissue achieved through heat transfer is termed
photothermolysis.
• This is further subdivided, subject to temperature change, phase transfer and
incident energy levels, into
1. Photopyrolysis,
2. Photovaporolysis and
3. Photoplasmolysis.

59. 59
Photopyrolysis:
• It is consistent with ascending temperature change from 60°C to 90°C, target
tissue proteins undergo morphologic change, which is predominately permanent.
Photovaporolysis:
• At 100°C, inter and intracellular water in soft tissue and interstitial water in hard
tissue is vaporized.
• This destructive phase transfer results in expansive volume change, which can
aid the ablative effect of the laser by dissociating large tissue elements,
especially seen in laser use in hard dental tissue cutting.

60. 60
Photoplasmolysis:
• It is characterized by high temperatures and explosive expansion at micro tissue
and molecular levels, this is observed in ultra-short pulsed lasers, e.g. Nd:YAG,
Er:YAG, with pulse widths of <100s.
• This phenomenon is adjunctive to photothermolysis, whereby a plasma is
formed by the ionizing effects of the strong electric fields of light waves, and
power densities >1010 W/cm2 are attained.
• Photoplasmolysis is achieved photonically in soft tissue and thermionically in
hard tissue and is characterized by flashes and popping sounds during laser use.

61. 61
• Plasma formation can be beneficial, in that extremely high ablative energies can
be produced, but also disruptive in that it can ‘shield’ the target from further
incident light, through the phenomenon of a plasma acting as a ‘super-absorber’
of electromagnetic radiation.
• It is considered that, within therapeutic levels of laser power used in dental
procedures, photoplasmolysis is a rare occurrence.

62. 62
• The photothermal effects of laser energy on the target tissue are shown:

63. 63
Photochemical Effect
• The laser light can stimulate chemical reactions (e.g. curing of composite resin)
and breaking of chemical bonds (e.g. using photosensitized drugs exposed to
laser light to destroy tumor cells, a process called photodynamic therapy).
Photoacoustic effect
• The pulse of laser energy on a crystalline structure (e.g. dental hard tissues) can
produce an audible shock wave, which could explode or pulverize the tissue
with mechanical energy creating an abraded crater.
• This phenomenon is called the photoacoustic effect of laser light.

64. ADVANTAGES & DISADVANTAGES OF
LASER OVER THE OTHER TECHNIQUES
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65. Advantages
65
• It is painless, bloodless that results in clean surgical field, and fine incision with
precision is possible.
• There is no need for anesthesia if at all anesthesia has to be administered, then it
needs to be used minimally only.
• The risk of infection is reduced as a more sterilized environment is created as
the laser kills bacteria.
• No postoperative discomfort, minimal pain and swelling, generally doesn't
require medication.
• Superior and faster healing, offers better patient compliance.

66. Disadvantages
66
• Lasers cannot be used to remove defective crowns or silver fillings, or to
prepare teeth for bridges.
• Lasers can't be used on teeth with filling already in place.
• Lasers don't completely eliminate the need for anesthesia.
• Lasers treatment is more expensive as the cost of the laser equipment itself is
much higher.

67. LASER TYPES USED IN TISSUE THERAPY
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68. 68
• Anecdotally, there has evolved two groups of lasers, ‘hard’ and ‘soft’, in
distinguishing their effect on tissue.
• ‘Hard’, or surgical lasers are essentially high power lasers which achieve
desired tissue effect through a direct interaction.
• This effect is primarily photothermal, in that incident light energy is absorbed
and converted into thermal energy which causes tissue change.

69. 69
• ‘Soft’, or ‘low-level’ lasers are essentially low power lasers which achieve
desired tissue effect through an indirect interaction, known collectively as
photobiostimulation, e.g. tissue warming, increase of local blood flow an
production of ‘feel-good’ factors, e.g. endorphins.
Examples for Soft Lasers
• Helium-neon laser (633 nm), gallium-arsenide laser (820 nm), diode laser
(GaAs 904 nm, GaAlAs 780–890 nm, InGaAlP 630–700 nm).

70. LASER UNITS
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71. 71
• In comparison to surgical lasers, low-level laser units are much smaller, often
self-contained, hand-held devices, which are either battery-driven or charged via
a pod in a bench-top master unit.
• There is no need for any integral cooling system and their power output levels
often warrant no specific safety rules that apply to surgical laser units.
• The amount of laser energy delivered to a target tissue is termed fluence, or
energy density and is measured in J/cm2.

72. 72
• In clinical practice, low-level laser therapy delivers fluence of 2–10 J/cm2,
depending on the target tissue as follows:
• Oral epithelium and gingival tissue - 2–3 J/cm2
• Transosseous irradiation (target - periapical area) - 2–4 J/cm2
• Extraoral muscle groups/TMJ - 6–10 J/cm2

73. APPLICATION OF LASERS IN
REMOVABLE PROSTHODONTICS
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74. 74
• The creation of removable full and partial dentures depend on the preoperative
analysis of the supporting hard and soft tissue structures and their proper
preparation.
• Lasers may now be used to perform most pre-prosthetic surgeries. These
methods involve
• Hard and soft tissue tuberosity reduction,
• Torus removal, and
• Treatment of inappropriate residual ridges involving undercut and irregularly resorbed
ridges,
• Treatment of unsupported soft tissues, and hard and soft tissue malformation.

75. 75
• Lasers may be used to treat the problem of hyperplastic tissue and nicotinic
stomatitis under the palate of a full or partial denture and ease the irritation of
epulis, denture stomatitis, and other problems related with long term wear of
ill-fitting dentures.
• Stability, retention, function, and esthetics of removable prostheses may be
increased by proper laser manipulation of the soft tissues and underlying
osseous structure.

76. 76
Treatment of unsuitable alveolar ridges
• Alveolar resorption is uniform in vertical and lateral dimensions. Thus,
irregular resorption occurs in one of the dimensions, making an inappropriate
ridge.
• As the available denture, bearing area is decreased, the load on the remaining
tissue increases, which leads to an ill-fitting prosthesis, with irritation.
• To detach sharp bony projections and to smooth the residual ridge soft tissue
lasers surgery to uncover the bone may be produced with any number of soft
tissue wavelengths (CO2, diode, Nd:YAG,) Hard tissue surgery may be
produced with the erbium family of wavelengths

77. 77
Treatment of undercut alveolar ridges
• There are many reasons of undercut alveolar ridges.
• Two of the most common reasons are dilated tooth sockets that result from
inadequate compression of the alveolar plates after an extraction and non-
replacement of a fractured alveolar plate.
• Naturally, occurring undercuts such as those found in the lower anterior
alveolus or where a prominent pre-maxilla is present may be a reason of soft
tissue trauma, ulceration, and pain when prosthesis is moved on such a ridge.

78. 78
• Soft tissue surgery may be produced with any of the soft tissue lasers. Osseous
surgery may be produced with the erbium family of lasers.
• Common surgery includes of detaching wedges of soft tissue from the alveolar
crest until the wound edges are closed. Any of the soft tissue lasers are able to
produce this method.

79. 79
Treatment of enlarged tuberosity
• The most common cause for enlarged tuberosity usually is soft tissue
hyperplasia and alveolar hyperplasia lead the over-eruption of unopposed
maxillary molar teeth.
• The expand tuberosity may stop the posterior extension of the upper and lower
dentures, thereby, decreasing their planning for mastication and their strength.
• The bulk of the hyperplastic tuberosity may rest toward the palate.
• The soft tissue decrease may be accomplished with any of the soft tissue lasers.

80. 80
Surgical treatment of tori and exostoses
• Prosthetic problems may arise if maxillary tori or exostoses are large or
irregular in shape.
• Tori and exostoses are formed mainly of compact bone. They may cause
ulceration of oral mucosa. These bony protuberances also may interfere with
lingual bars or flanges of mandibular prostheses.
• Soft tissue lasers may be used to expose the exostoses and erbium lasers may be
use for the osseous reduction.

81. 81
Soft tissue lesions
• Persistent trauma from a sharp denture flange or over compression of the
posterior dam area may produce a fibrous tissue response.
• Hyper-plastic fibrous tissue may be formed at the junction of the hard and soft
palate as a reaction to constant trauma and irritation from the posterior dam
area of the denture.
• The lesion may be excised with any of the soft tissue lasers and the tissue
allowed to re-epithelialized.

82. APPLICATION OF LASERS IN FIXED/
ESTHETIC PROSTHODONTICS
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83. 83
Crown lengthening
• Clinical scenarios where crown lengthening methods are specified within
esthetic zone, need attention to attain esthetic results. Crown lengthening
methods with the help of lasers are included in following situation:
• Caries at gingival margin
• Cuspal fracture extending apically to the gingival margin
• Endodontic perforations near the alveolar crest.
• Insufficient clinical crown length.
• Difficulty in a placement of finish line coronal to the biological width.
• Need to develop a ferrule.
• Unaesthetic gingival architecture.
• Cosmetic enhancements.

84. 84
• Lasers offer unparallel accuracy and operator control and may be helpful for
finely tracing incision lines and shaping the desired gingival margin outline.
• All the other crown lengthening methods has disadvantages in surgical approach
healing time is longer, post healing gingival margin position is doubtful and
patient compliance is poor as it needs use of anesthesia and scalpel for electro-
surgery, the heat liberated has effect on pulp and bone leading to pulp death or
bone necrosis.

85. 85
Soft tissue management around abutments
• Argon laser energy has peak absorption in hemoglobin, thus, providing
excellent hemostasis and well regulated coagulation and vaporization of oral
tissues.
• These characteristics are beneficial for retraction and hemostasis of the gingival
tissue in preparation for an impression during a crown and bridge method.
• Argon laser with 300 µm fiber, and a power setting of 1.0W, continuous wave
delivery, and the fiber is placed into the sulcus in contact with the tissue. In a
sweeping motion, the fiber is moved around the tooth.
• It is dominant to contact the fiber tip with the bleeding vessels. Provide suction
and water spray in the field. Gingivoplasty may also be done using argon laser.

86. 86
Modification of soft tissue around laminates
• The removal and re-contouring of gingival tissues cover can be easily efficient
with the argon laser.
• The laser can be used as a primary surgical instrument to detach excessive
gingival tissue, whether diseased, secondary to drug therapy or orthodontic
treatment.
• The laser will detach tissue and supply hemostasis and tissues join the wound.

87. 87
Osseous crown lengthening
• Like teeth mineralized matrix of bone contains mainly of hydroxyapatite.
• The water content and hydroxyapatite are responsible for the high absorption
of the Er:YAG laser light in the bone.
• Er:YAG laser has very promising potential for bone ablation.

88. 88
Formation of ovate pontic sites
• There are many causes of the inappropriate pontic site.
• Two of the most common causes are inadequate compression of alveolar plates
after an extraction and non-replacement of a fractured alveolar plate.
• Inappropriate pontic site results in unaesthetic and non-self-cleansing pontic
design.
• For favorable pontic design re-contouring of soft and bony tissue may be
required.

89. 89
• The use of an ovate pontic receptor site is of great value when trying to produce
a natural maxillary anterior fixed bridge. This is easily good with the use of a
laser.

90. 90
Altered passive eruption management
• Lasers can be easily to control passive eruption problems.
• When the patients have clinical crowns that appear too short or when they have
a jagged gingival line creating an uneven smile, excessive tissue can be
detached without the need for blade incisions, flap reflection, or suturing.
Bleaching
• Esthetics and smile are main situation in our modern society. Bleaching of teeth
can be achieved in the Dental OPD.
• Diode lasers are used to bleach teeth without causing much tooth sensitivity and
modification of the complexion of the tooth.

91. 91
Laser troughing:
• Lasers can be used to produce a groove around a tooth before impression
taking.
• This can be restored the require for retraction cord, electrocautery, and the use
of hemostatic agents.
• The results are obvious, well regulated, minimize impingement of epithelial
attachment, cause less bleeding during the impression, decrease postoperative
problems and chair time.
• It changes the biological width of the gingiva. After laser grooving, the
impression is taken and sent to the lab for prosthetic work.

92. 92
• The main function of the marginal finish line is to keep the biological width, it
acts as the termination point of tooth preparation, help in ease of fabrication,
helps in taking a proper impression.
• In brittle teeth to keep the biological width and finish line laser grooving plays
a main role.

93. 93
Removal of veneer:
• Restoration can be removed without cutting with the help of laser beams.
• The laser energy passes through porcelain glass unchanged and is occupied by
the water molecules present in the adhesive.
• Debonding takes place at the junction of the silane and the resin without
causing any trauma to the underlying tooth.
Crown fractures at the gingival margins:
• Er:YAG or Er,Cr:YSGG lasers can be moved out to permit correct exposure of
the fracture margin

94. APPLICATION OF LASERS IN
IMPLANTOLOGY
94

95. 95
Implant recovery
• The placement of implant and its combination into the osseous substrate, the
method of treatment is surgically expose the implant, wait for the tissue to heal
and start with impressions and fabrication of the restoration.
• Uses of lasers can proceed this method because the implant can be exposed,
and impressions can be obtained at the same appointment. All types of lasers
can be used to release dental implants.
• There is minimal tissue shrinkage after laser surgery, which tell that the tissue
margins will continue at the same level after healing.

96. 96
• In addition, the use of laser can detach the trauma to the tissues of flap
reflection and suture placement.

97. 97
Implant site preparation
• Lasers can be used for the placement of mini-implants generally in patients with
potential bleeding problems, to give bloodless surgery in the bone.
Removal of diseased tissue around the implant
• Lasers can be used to restore implants by sterilizing their surfaces with laser
energy.
• Diode, CO2 & Er:YAG lasers can be used for this reason. Lasers can be used to
remove granulation tissue in case there is inflammation around an
osseointegrated implant.

98. APPLICATION OF LASERS IN
MAXILLOFACIAL REHABILATION
98

99. 99
• The use of lasers in the maxillofacial prosthetics is usually for the initial work
up of three- dimensional addition of optical data of the extra-oral defects.
• Laser technology has showed to be useful for designing the shape and position
of the prostheses.
• Lasers can remove the need for conventional impression techniques and related
disadvantages like distortion of the soft tissue and irritation to patients.
• Lasers also overcome the disadvantages of 3D CT and MRI reconstruction as
the patient is not uncovered to considerable radiation and any stress.

100. APPLICATIONS OF LASERS IN THE
DENTAL LABORATORY
100

101. 101
• There is a range of laboratory-based laser applications.
• Laser holographic imaging is a well established method for storing topographic
information, such as crown preparations, occlusal tables, and facial forms.
• The use of two laser beams allows more complex surface detail to be mapped
using interferometry, while conventional diffraction gratings and interference
patterns are used to generate holograms and contour profiles.
• Laser scanning of casts can be linked to computerized milling equipment for
fabrication of restorations from porcelain and other materials.
• An alternative fabrication strategy is to sinter ceramic materials, to create a
solid restoration from a powder of alumina or hydroxyapatite.

102. 102
• The same approach can be used to form complex shapes from dental wax and
other materials which can be sintered, such that these can then be used in
conventional ‘lost wax’ casting.
• A variation on this theme is ultraviolet (helium-cadmium) laser-initiated
polymerization of liquid resin in a chamber, to create surgical templates for
implant surgery and major reconstructive oral surgery.
• These templates can be coupled with laser-based positioning systems for
complex reconstructive and orthognathic surgical procedures.

103. RISKS ASSOCIATED WITH LASER USE
103

104. 104
Laser Beam Risks
• These risks are those that are posed by exposure of non target tissues to laser
beams.
• Because of the intensity of the output beam and the ability of lasers to produce
very high concentrations of optical power at considerable distances, these lasers
can cause serious injuries to the eyes and can also burn the skin.

105. 105
Optical Risks
• The majority of laser-induced ocular injuries are considered due to operator
error.
• In general and with specific reference to lasers used in dentistry, there exist two
groups of wavelengths that can adversely affect the eye.
• Wavelengths from 400–1,400 nm (visible and near infrared) can pass through the
transparent structures in front of the eye and impact on the retina.
• Longer wavelengths 2,780–10,600 nm (mid-to far infrared), will interact with the cornea.
• In terms of the scope for repair, retinal injuries are more serious.
• Due to the focusing ability of the lens, a 1 mW (0.001 W) laser beam, passing
to the back of the eye, results in a retinal irradiance more than 300 W/cm2, well
above the ablation threshold.

106. 106
• Visible wavelengths may selectively destroy red or green cones, resulting in
some color blindness, although the majority of retinal laser burns affect
complete areas of tissue due to the predominance of invisible wavelengths in
dental lasers.
• Retinal injury may initially pass unnoticed, due to the lack of pain receptors.
• Longer wavelengths will interact with structures at the front of the eye, causing
ablation, scarring and distortion of vision non-pigmented structures towards the
front of the eye will be most at risk from longer wavelengths.

107. 107
Skin Risks
• Whilst ultraviolet lasers (<400 nm) are not commercially used in dentistry, there
is a combined risk of ablative damage to skin structure and possible ionizing
effects that may be precancerous.
• All other laser wavelengths can cause ‘skin burns’ due to ablative interaction
with target chromophores.

108. 108
Non-beam Risks
• These risks are associated with possible physical damage arising from:
• Moveable components of a laser, electrical shock and mains supplies
(pressurized air, water).
• Fire risks, through the ignition of tubing, some anesthetic gases or chemicals
(e.g. alcoholic disinfectants), should be identified and avoided.
• The products of tissue ablation, collectively termed a ‘laser plume’ represent a
considerable hazard that can affect the clinician, auxiliary personnel and the
patient.

109. 109
• Whenever non-calcified tissue is ablated, such as in caries removal and all soft
tissue surgery, a complex chemical mixture is emitted.
• This may include water vapor, hydrocarbon gases, carbon monoxide and
dioxide and particulate organic material (including bacteria and viral bodies).
• The effect of plume inhalation can be serious and cause nausea, breathing
difficulties and distant inoculation of bacteria.

110. 110
• The plume arising from mid-infrared wavelength ablation of dental hard tissue
is comparatively less potentially dangerous and can be considered similar to
the debris that is produced with an air turbine.
• Suitable fine mesh face masks specific to surgical laser use, gloves and high-
speed suction aspiration must be used to control the spread of all laser tissue
ablation product.

111. LASER SAFETY MEASURES
111

112. 112
• Safety measures applicable to laser use in dental practice meeting the
worldwide standards can be listed as follows:
• Environment
• Laser protection advisor/Laser safety officer (LPA/LSO)
• Access
• Laser safety features
• Eye protection
• Test firing
• Training.

113. 113
Environment
• The concept of laser beam collimation is only true for transmission in a vacuum,
or at its immediate exit from the laser cavity.
• In air, and certainly through a delivery system with or without focusing devices,
some divergence will occur.
• Accepting the power output, amount of divergence and beam diameter and
configuration, a nominal ocular hazard distance (NOHD) can be assessed. This
is a distance from the laser emission, beyond which the tissue (eye) risk is below
the maximum permissible exposure levels (MPE).
• This is a complex calculation that can be done by a medical physicist, but for a
class IV dental laser, this distance is approximately 3 meters.
.

114. 114
• Consequently, as with ionizing radiation, the concept of a controlled area can be
adopted, within which only those personnel directly involved in laser delivery
can enter and with specified protection.
• The controlled area must be delineated with warning signs that specify the risk,
windows, doors and all surfaces should be non-reflective and access through
ways either supervised or operated by remote interlocks during laser emission.
• A secure locked designated place for the laser key, if applicable, should be
assigned, together with a designated place for all laser accessories. In addition,
a suitable fire extinguisher should be sited for easy access

115. 115
Safety Officers
• Dental practices offering class III-B and IV laser treatment, must appoint a
laser safety officer (LSO).
• The Laser protection advisor (LPA) is usually a medical physicist who will
advise on the protective devices required, maximum permissible exposure level
and nominal ocular hazard distance (NOHD) for any given laser wavelength
being used.
• The laser safety officer is appointed to ensure that all safety aspects of laser use
are identified and enforced. Ideally, this could be a suitably trained and
qualified dental surgery assistant.

116. 116
Duties of the laser safety officer include the following:
• Confirm classification of the laser.
• Read manufacturers' instructions concerning installation, use and maintenance
of the laser equipment.
• Make sure that laser equipment is properly assembled for use.
• Train workers in safe use of lasers.
• Oversee controlled area and limit access.
• Oversee maintenance protocols for laser equipment.

117. 117
• Post-appropriate warning signs
• Recommend appropriate personal protective equipment such as eye wear and
protective clothing
• Maintain a log of all laser procedures carried out, relative to each patient, the
procedure and laser operating parameters
• Maintain an adverse effects reporting system
• Assume overall control for laser use and interrupt treatment if any safety
measure is infringed

118. 118
Access
• During laser treatment, only the clinician, assistant and patient should be
allowed within the controlled area.
• Door locks and warning lights can be activated during laser emission. Those
dental clinics that operate a multi-chair, open-plan environment would need to
address the requirement in greater detail.

119. 119
Laser Safety Features
• All lasers have in-built safety features that must be cross-matched to allow laser
emission. These include:
• Emergency ‘Stop’ button
• Emission port shutters to prevent laser emission until the correct delivery system is
attached
• Covered foot-switch, to prevent accidental operation
• Control panel to ensure correct emission parameters
• Audible or visual signs of laser emission
• Locked unit panels to prevent unauthorized access to internal machinery
• Key or password protection
• Remote inter-locks.

120. 120
Eye Protection
• All persons within the controlled area must wear appropriate eye protection
during laser emission.
• It is considered advisable to cover the patient’s eyes with damp gauze for long
wavelength perioral procedures.
• The laser safety officer should select the correct eyewear for the laser
wavelength being used, these should be free of any scratches or damage and be
constructed with side protection/shields to protect the eyes from reflective laser
energy.

121. 121
• The information about lens protection must be imprinted on the frames of the
glasses or goggles. Generally, protective glasses must have an optical density
(OD) of at least 4 for the particular laser emission and device

122. 122
Test Firing
• Prior to any laser procedure and before admitting the patient, either the clinician
or laser safety officer should test-fire the laser.
• This is to establish that the laser has been assembled correctly, is working
correctly and that laser emission is occurring through the delivery system.
• Protective eyewear is worn and all other safety measures met.
• The laser is directed towards a suitable absorbent material, e.g. water for long
wavelengths and dark colored paper for short wavelengths, and operated at the
lowest power setting for the laser being used.
• Following this, the laser is inactivated and the patient admitted.

123. 123
Training
• All staff members should receive objective and recognized training in the safety
aspects of laser use within dentistry, as with other specialties. However, there is
no legal obligation for this.

124. LASER SAFETY CLASSIFICATION
124

125. 125
Maximum Permissible Exposure (MPE )
• Maximum amount of laser energy which does not produce detrimental effects
on tissue; measured at the human cornea or skin.
• The current classification system is based on the safety requirements of laser
systems provided by the IEC 60825-1 standard (IEC —international Electro-
technical Commission).
• Classes 2 and higher must have a warning label outside the operatory.

126. 126

127. REVIEW OF LITERATURE
127

128. Lopes CB, Pinheiro AL, Sathaiah S, Duarte J, Cristinamartins M. Infrared laser light reduces
loading time of dental implants: a Raman spectroscopic study. Photomedicine and Laser
Therapy. 2017 Feb 1;23(1):27-31.
128
• The aim of this study was to assess, through near-infrared Raman spectroscopy
(NIRS), the incorporation of calcium hydroxyapatite(CHA; ~960 cm1)—on the
healing bone around dental implants submitted or not to low-level laser therapy
(LLLT) (830 nm).
• Fourteen rabbits received a titanium implant on the tibia; eight of them were
irradiated with 830-nm laser, and six acted as control.
• The animals were sacrificed at 15, 30, and 45 days after surgery. Specimens
were routinely prepared for Raman spectroscopy.
• Twelve readings were taken on the bone around the implant.

129. 129
• The results showed significant differences in the concentration of CHA on
irradiated and control specimens at both 30 and 45 days after surgery (p
0.001).
• Authors concluded that LLLT does improve bone healing, and this can be
safely assessed by Raman spectroscopy.

130. Torkzaban P, Kasraei S, Torabi S, Farhadian M. Low-level laser therapy with 940 nm diode
laser on stability of dental implants: a randomized controlled clinical trial. Lasers in medical
science. 2018 Feb 1;33(2):287-93.
130
• The aim of this study was to evaluate the efficacy of LLLT for improvement of
dental implant stability. This randomized controlled clinical trial was performed
on 80 dental implants placed in 19 patients.
• Implants were randomly divided into two groups (n = 40). Seven sessions of
LLLT (940 nm diode laser) were scheduled for the test group implants during 2
weeks.
• Laser was irradiated to the buccal and palatal sides.

131. 131
• The same procedure was performed for the control group implants with laser
hand piece in “off” mode. Implant stability was measured by Osstell Mentor
device in implant stability quotient (ISQ) value immediately after surgery and
10 days and 3, 6, and 12 weeks later.
• Although the mean values of implant stability changed significantly in both
groups over time. Although the trend of reduction in stability was slower in the
laser group in the first weeks and increased from the 6th to 12th week, LLLT
had no significant effect on dental implant stability.

132. Matsuyama T, Aoki A, Oda S, Yoneyama T, Ishikawa I. Effects of the Er:YAG laser irradiation
on titanium implant materials and contaminated implant abutment surfaces. Journal of clinical
laser medicine & surgery. 2018 Feb 1;21(1):7-17.
132
• The purpose of this study was to examine the morphological changes and
temperature increases of the titanium after Er:YAG laser irradiation, and also to
investigate the effect of this laser on debridement of contaminated healing
abutments.
• Experiments were composed of three parts.
• At first, ten titanium round plates were exposed to the Er:YAG laser irradiation
at 30–200 mJ/pulse and the surface changes were observed by stereomicroscope
and scanning electron microscope.

133. 133
• Secondly, the surface temperature changes of 60 titanium plates during and
after Er:YAG laser irradiation at 30 and 50 mJ/pulse were measured by
thermographic equipment
• At last, calculus on the surface of six contaminated healing abutments was
removed by Er:YAG laser or ultrasonic scaler, and the treated surfaces were
examined by stereomicroscope.
• Under 50 mJ/pulse, distinct morphological changes were not observed and the
elevation of surface temperature was minimal, especially in the use of water-
cooling.

134. 134
• The Er:YAG laser at 30 mJ/pulse and 30 Hz with water spray was capable of
effectively removing plaque and calculus on the implant abutments without
injuring their surfaces.
• This study indicates that the Er:YAG laser can be a novel technical modality
for the debridement of implant abutment surface.

135. CONCLUSION
135

136. 136
• Lasers have become a ray of hope in dentistry. When used effectively and
ethically, lasers are an exceptional modality of treatment for many clinical
conditions that dentists treat on a daily basis.
• But lasers has never been the “magic wand” that many people have hoped for.
It has got its own limitations.
• If a clinician decides to use a laser for a dental procedure, he or she needs to
fully understand the character of the wavelength being used, and the thermal
implications & limitations of the optical energy.
• From operative dentistry to periodontics, pediatrics and prosthetics to cosmetics
and implantology, Lasers have made a tremendous impact on the delivery of
dental care in the 21st century and will continue to do so as the technology
continues to improve and evolve.

137. REFERENCES
137

138. 138
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• Torkzaban P, Kasraei S, Torabi S, Farhadian M. Low-level laser therapy with
940 nm diode laser on stability of dental implants: a randomized controlled
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