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Laser Dentistry > Laser Dentistry > Flashcards

Laser Dentistry Flashcards

1
Q

What is the height of wave called in EM Spectrum?

A

Amplitude

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2
Q

What is the distance between 2 corresponding points in a periodic wave called? (the distance a photon travels in one complete oscillation)

A

Wavelength

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3
Q

What is # of complete oscillations of a wave called? (Cycles/Sec=Hz) also Inverse. proport. to WL

A

FREQUENCY=”Repetition Rate”=Hertz (Hz) (also “Emission Cycles” or “Pulses” per Second)

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4
Q

What is the velocity of a photon?

A

Speed of Light=186,282 miles/sec (300,000 km/hr)

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5
Q

How Laser Light is different than Visible Light? (Both are EM Radiation, traveling at the speed of light, as a wave and particle)

A

1) Man-made (doesn’t exist in nature)
2) special, unique form of light
3) found in WLs-UV,Visible,IR

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6
Q

What is a Photon?

A

EM particles associated with light=”quanta” of EM energy traveling at the speed of light

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7
Q

Who defined that energy was emitted in quantifiable form?

A

Max Planck=Quantum Physics=Planck’s Constant (h) =”Quanta packets” E=hv E=hc/wl

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8
Q

What physicist developed Quantum Theory=”photons”=”quanta of light”?

A

Neil’s Bohr

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9
Q

What physicist is responsible for the theory of “Stimulated Emission of Energy”?

A

Albert Einstein

if artificially stimulated, excited atoms can absorb “quantum of energy”

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10
Q

Who patented the term LASER?

A

Gordon Gould in 1957

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11
Q

Who developed the 1st Functional LASER? (credited for 1st LASER) 1st Functional Dental Laser?

A

1) Theodore Maiman in 1960 (inserted a Ruby Crystal into a photographic flashlamp
2) 1989 - 1st true dental laser

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12
Q

Who created the first LASER?

A

Charles Townes=MASER=Microwave Amplification by Stimulated Emission of Radiation

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13
Q

Laser Light or Visible Light?

  • multiple wavelengths
  • non-directional/focused
  • unorganized/incoherent
  • non-collimated
A

Visible Light

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14
Q

Laser Light or Visible Light?

  • one wavelength
  • directional/focused
  • organized/coherent
  • collimated (“parallel beam”)/monochromatic
A

Laser Light

  • reflected back and forth by precise mirrors
  • monochromatic=”one wavelength=one color”
  • coherent=”light waves in phase”
  • collimated=”non-divergent”
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15
Q

What is the definition of Coherence?

A

every wave is of the SAME WL/IN PHASE (Amplitudes Aligned)…the photons are well-ordered and travel parallel to each other

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16
Q

What is Amplification? (Amplitudes are aligned=”coherent”=thus maximizing wave energies)

A

a process that occurs in OPTICAL RESONATOR…where stimulated emission produces a population inversion

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17
Q

What part of the dental laser that is responsible for Amplification/Coherence of light waves?

A

OPTICAL RESONATOR=”AMPLIFIER”

Collimated Beam+Coherent Energy…responsible for Laser accuracy

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18
Q

Can you affect the MONOCHROMATICITY and COLLIMATION of Laser Light?
(Collimation=non-divergent)

A

Monochromaticity…can altar WL by passing laser light through “frequency dbling crystals” (i.e. Alexandrite Laser
Collimation…pass laser light through any medium>density than air-see some divergence (i.e. c.f. Lens convergence)

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19
Q

What does LASER acronym stand for?

A

Light Amplification by Stimulated Emission of Radiation

(atom in a “stimulated” state-stimulated by another quanta of energy…produce 2 “COHERENT quanta of energy”

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20
Q

What are the components of a LASER?

A

1) Pumping Mech 2) Active Medium
3) Optical Resonator (pumping mech/amplifier)
4) Delivery System 5) Cooling System (“fan”) 6) Control System= foot switch/display panel/safety mech

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21
Q

Name 2 types of Pumping Mechanisms in Dental Lasers?

“EXCITATION SOURCE”=”EXTERNAL ENERGY SOURCE”

A

1) FRP (Free running pulsed) = rapidly strobing Flashlamp (Er:YAG,Nd:YAG)
2) CW (Continuous Wave) = Electric Induction Coil (Diode or CO2)
* *can be Pulsed or Gated (“Chopped”)

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22
Q

Creates…population inversion within the active medium to cause continued stimulated emission of radiation or “Amplified Light” by mechanism to reflect photons back and forth?

A

OPTICAL RESONATOR = Pumping Mechanism in Dental Laser

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23
Q

3 Types of ACTIVE MEDIUM in dental lasers

A

1) Liquid=Excimer Dye
2) Gas=CO2 or Argon
3) Solid
a) YAG or YSGG Crystal
b) Diode Capacitor = Al (or IN), Ga, As

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24
Q

What is the “laser cavity” where light AMPLIFICATION occurs?

A

OPTICAL RESONATOR=”Amplifier”

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25
Q

What are the components within an OPTICAL RESONATOR?

A

1) Active Medium=Solid, Liquid or Gas

2) Mirrors (for amplification)

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26
Q

Definition of POPULATION INVERSION=

A

an environment that produces more atoms with electrons in higher energy orbitals that in the ground state…

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27
Q

LASER LIGHT is MONOCHROMATIC, meaning =

A

only a specific wavelength is preferentially stimulated from the “excited” atoms

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28
Q

LASER LIGHT is COHERENT, meaning =

A

the wavelengths of the stimulated photons line up with the passing photons

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29
Q

What type of Dental Laser uses a solid crystal active medium “sandwiched” between silicon wafers”

A

DIODE LASERS

the crystal is polished to act as mirrors

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30
Q

What type of Dental Lasers have wavelengths in the VISIBLE and NEAR-INFRARED EMS?

A

DIODE LASERS 800 nm-980 nm

(810,940,980,1064 nm)

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31
Q

What is the range of wavelengths on EMS spectrum for VISIBLE LIGHT?

A

WL = 400 nm -750 nm

blue-green-orange-yellow-red

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32
Q

EMS SPECTRUM = “The larger the wavelength, the ________ penetration into tissues”…The lower the wavelength, the __________ penetration into tissues”

A

“LESS”

“DEEPER”

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33
Q

What is the range of wavelengths on EMS spectrum for IONIZING RADIATION?

A

WL < 400 nm

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34
Q

Name the 3 types of INVISIBLE IONIZING RADIATION?

A

1) Gamma Rays
2) X-Rays (<100 nm)
3) Ultraviolet (>100 nm)

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35
Q

WAVELENGTH IS INVERSELY PROPORTIONAL TO FRQUENCY = “If Double the Frequency then _________ the wavelength”

A

“HALVE”…“The shorter the wavelength, the higher the frequency, and vice versa” Wavelength =c/v (frequency)
c=speed of light

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36
Q

PHOTON ENERGY IS INVERSELY RELATED TO WAVELENGTH

A

E = PLANCKS CONSTANT (h) * c / Wavelength

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37
Q

Photons with greater Energy have ______ Frequency and _______ wavelengths

A

Higher Frequency and Shorter Wavelengths

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38
Q

Type of Radiation that penetrates oral tissue, can disrupt DNA and overexposure can be harmful=

A

IONIZING RADIATION (DOES NOT vaporize by thermal radiation)

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39
Q

Type of Radiation that penetrates oral tissue, DOES NOT disrupt DNA and overexposure can be harmful=

A

NON IONIZING RADIATION (DOES vaporizes by thermal radiation)

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40
Q

What are the 3 types of DELIVERY SYSTEMS in dental lasers, to direct laser energy to target tissue?
LLLT-delivery is by hand-held units

A

1) Optical Fiber WLs-100 nm-Near IR
2) Art Arm-Sapphire tip (CO2/ErYAG)
* Er:YAG 2 delivery systems
a) Art Arm b) NON-quartz Fiber)
3) hollow-waveguide-Sapphire tip (CO2)

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41
Q

What are the 3 components of OPTICAL FIBERS used in soft tissue dental lasers?

A

1) CORE=quartz (or silica and/or sapphire)
2) CLADDING-Amine coating (“reflective”)
3) JACKET-silicone rubber

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42
Q

Which type of OPTICAL FIBER has a high -OH content? and therefore good for NEAR INFRARED WL?

A 
Quartz Fiber ("not absorbed in water") w/ Sapphire Tip
"the higher WL (MID/FAR INFRARED) are highly absorbed in water so Quartz Fiber not a good option (ie Erbium and CO2 lasers)"
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43
Q

What type of garnet crystal is in a YAG laser?

What is the crystal doped with?

A

Yttrium Aluminum Garnet

Doped with=Erbium OR Neodynium

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44
Q

What type of garnet crystal is in a YSGG laser?

What is the crystal doped with?

A

Yttrium Scandium Gallium Garnet

Doped with=Erbium AND CHROMIUM

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45
Q

What determines the NAME of the Laser?

A

THE ACTIVE MEDIUM b/c it determines the WAVELENGTH being emitted

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46
Q

What are the 3 different ACTIVE MEDIUMS used in DIODE lasers?

A

1) AL (Aluminum) or IN (Indium)

2) GA (Gallium) 3) AS (arsenic)

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47
Q

Which dental lasers use a CONTINUOUS WAVE Emission mode (Electric Induction Coil)?

A

1) DIODE 2) CO2 “No colon in the name”

* *PULSED - GATED (“chopped”) is acquired CW = Ultrapulsed/Super-pulsed/Micro-pulsed/Q-switched**

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48
Q

Which dental laser uses a FREE-RUNNING PULSED (FRP) Emission mode?

A

Er:YAG 2940 nm “Rapidly strobing flashlamp”

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49
Q

Calculate the percentage (%) of “on time” that a laser is actually emitting energy during a pulsed, chopped or gated emission cycle?

A

DUTY CYCLE = EMISSION CYCLE = “Ratio between time the emitted energy is ON during the pulse”
DUTY CYCLE= Hz X PULSE DURATION = %
(10 Hz X .05 sec = .5 = 50% Duty Cycle) OR
.5 sec PULSE Width/1 sec PULSE DURATION=.5=50%

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50
Q

Amt of time power is actually being admitted during one pulse or “on-time” during one pulse?

A

PULSE DURATION or PULSE WIDTH

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51
Q

Solve for PEAK POWER (Rate of Energy Flow per pulse)?

if AVG POWER = 1.5 Watts and Duty Cycle = 25%

A

PEAK POWER=AVG POWER/Duty Cycle

1.5 Watts/.25 = 6 Watts

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52
Q

Solve for AVG POWER (Rate of Energy Flow averaged over 1 full time interval)?
(if Peak Power=6 watts, Duty Cycle = 25%)

A

AVERAGE POWER=PEAK POWER X DUTY CYCLE

6 Watts X .25 = 1.5 Watts

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53
Q

ALD BASIC TENET=

A

“Always use the MIN POWER levels necessary in order to achieve your desired clinical result”

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54
Q

Calculate Peak Power for Free-Running Pulsed Mode at 10 Hz and Pulse Duration of 200 microseconds?
if AVG POWER=2 Watts

A

Duty Cycle=10 X .0002 secs = .002 = .2% (Laser On Time)
Peak Power = 2 Watts / .002 = 1000 Watts
Laser is off 99.8 % of the time - TRT

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55
Q

The total Energy delivered for a laser procedure is measured with what? How is power measured (the rate of energy conversion or transfer with respect to time)?

A

Energy=Joules (milliJoules)=”Ability to do work”
Power=Watts=Joules/sec=”Rate of doing work”
Energy=Power (Watts) X Time (secs)=Joules

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56
Q

Amount of POWER delivered to the tissue surface area, at the point of tissue interaction?

A

POWER DENSITY=”INTENSITY”=mW/cm2=mJ/sec per Area (affected by Energy+Exposure Time+spot size)

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57
Q

Amount of ENERGY emitted per unit area at the point of tissue interaction, per tissue surface area?

A

ENERGY DENSITY=FLUENCE=mJ/cm2

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58
Q

This type of Laser-Tissue Interaction has no effect on Target Tissue?

A

1) REFLECTED Laser Photonic Energy

***TRANSMITTED (and scattered) Energy-depends-can have an indirect effect; Used in caries detection

59
Q

This type of Laser-Tissue Interaction effects Target Tissue depending on Laser WL, Pigmentation,H2O,Tissue type

A

ABSORPTION= 1) Photothermal 2) Photochemical (curing lights) 3) Photoaccoustic (Er Hard tissue lasers)

60
Q

4 types of compounds in dental tissues that ABSORB Laser Light and are called “Chromophores”?

A

1) H2O 2) Melanin 3) Hb and OxyHb 4) cOH-“carbonated Hydroxyapatite

61
Q

Measurement of the amt of absorption of Laser Energy/per unit area?

A

ABSORPTION COEFFICIENT (higher means greater absorption of a WL’s photonic energy w/i chromophore)

62
Q

Chromophore Content of Dental Tissues?

A

SOFT TISSUE H2O=72-77% Hb=3-4% Melanin=1-2% ENAMEL cHA=95% H2O=4%
BONE cHA=60-70% H2O=10-20%

63
Q

Which Laser WL’s delivers NON-ABLATIVE Photothermal (non-contact) Energy (treat oral ulcers/herpetic lesions)?

A

Near IR=Diode and Nd:YAG (uninitiated laser tip emits “pure radiant energy”=Radiation=Thermal “Heat” Transfer)
TRUE LASER EFFECT

64
Q

Near IR Laser has less collateral thermal tissue damage - soft tissue surgeries (“thermal ablation”)?

A

1064nm Nd:YAG Chromo=Hb/Melanin/ Granulation Tissue=FRP allows tissue relaxation time, more time to cool

65
Q

Which Laser WL is absorbed by Porphryin rings in bacteria, causing Laser Fluoresence?

A

DiagnoDent=655 nm Diode

***377 nm Solid

66
Q

What is the KEY to maximizing the Laser-Tissue Interaction (“ABSORBANCE OF LASER LIGHT”)?

A

Choose the LASER WL that matches the CHROMOPHORE OF THE TARGET TISSUE

67
Q

List the PHOTOBIOLOGICAL effects of LASERS?

A

1) PHOTOTHERMAL=temp effects (LAPT,Ablation,Cautery)
2) PHOTOACCOUSTIC=Disruption,Plasma Effect
3) PHOTOCHEMICAL=PDT,+chemical bonds (curing lights)
4) BIOSTIMULATION=+collagen,wound healing,analgesia
5) Laser-Induced Fluorescence=caries detection

68
Q

Laser Tissue Interaction, VAPORIZATION, occurs at what temperature (in Celsius)?

A

100 degrees Celsius (Tissue Welding=70-90 degrees Celsius, > 200 degrees Celsius=Carbonization)

69
Q

Laser-Assisted Perio occurs at what temperature, in Celsius, a “photothermal” effect on tissue”?

A

> 60 degrees Celsius=protein denaturation + coagulation

can inactivate some non-sporulating bacteria at 50 C

70
Q

Do Near IR Lasers (Diodes/Nd:YAG/Nd:YAP) ablate soft tissues by Thermal Ablation or Photothermal Ablation?

A

THERMAL ABLATION by Thermal Conduction=”Hot Tip”

NOT PHOTOTHERMAL ABLATION

71
Q

Thermal transfer (heat generated by Lasers) can occur in 3 ways?

A

1) CONDUCTION - direct contact of heat w/ target tissue
2) CONVECTION - Heat moved in lg volumes near target
3) RADIATION - non-contact waves absorbed by target from source = “TRUE LASER EFFECT”

72
Q

In Laser-Tissue Interaction, The BIOLOGIC EFFECT of Lasers depends on?

A

1) ENERGY DENSITY 2) TISSUE TYPE 3) WL+EMISSION MODE 4) Duration of Exposure + Amt of Cooling

73
Q

Time during which the target tissue is allowed to cool, the time that the laser energy is OFF during a pulse?

A

THERMAL RELAXATION TIME

74
Q

Characteristics of Target Tissue?

A

1) Tissue Profile=hypertrophic/fibrotic or thin/friable
2) Degree of Melanin Pigmentation
3) How much keratinized tissue?

75
Q

What does LAPT stand for?
Indications for LAPT 1) Bleeding on Probing
2) Calculus 3) Attachment Loss

A

Laser Assisted Periodontal Therapy…
LA/Ultrasonic scaler w/ antimicrobial agent/light hand scaling/use Laser to removed dz epithelial lining and for coagulation-bacterial reduction

76
Q

What are the results of Laser use in Periodontal Therapy (LAPT), after SR/P?

A

1) Reduction in bacterial flora
2) up to 97% reduction in bleeding when probing
3) decreased pocket depth
4) overall better gingival health

77
Q

What is most important in performing LAPT?
Diode CW .5 Watts 12-15 secs/pocket site
Nd:YAG Pulsed 1.5 Watts (30 mJ,50 Hz) 40 secs/site
CO2 10,600 nm 2 Watts (40 mJ,50 Hz) 30 secs/tooth

A

1) Lase w/i 2 mm of pocket depth 2) place fiber in sulcus before firing/angle away from tooth 3) keep fiber moving
4) probing depths-Pre-op/3 mo post op
* *Nd:YAG-no need to condition fiber tip

78
Q

POWER DENSITY (Watts/cm2) can be changed by…

A

1) changing the power setting (Watts)
2) changing the spot size/spot dia
3) use a lense to change spot size
4) moving tip toward or away (defocusing)

79
Q

Laser ablation of GRANULATION tissue require more or less power?

A

Less Power (can defocus beam to decrease power) (Nd:YAG 1064 nm most effective on granulation tissue)

80
Q

What is the Power Density Effect-Inverse Square Rule?

A

Decrease spot size 1/2=2 (squared)=4X increase in power

81
Q

DIVERGENCE=How much does energy decrease when laser light diverges from the delivery system?

A

@ 1 mm out of contact=<=44% energy decrease

CO2-Optimal Distance=Focal Spot=3.5 mm-10 mm

82
Q

Non-contact lasers, Hollow Waveguides and Articulated Arms minimize power loss due to DIVERGENCE by?

A

FOCUSING LENSES (ie 7 mm from tip) minimize divergence and resultant decrease in energy

83
Q

How do non-contact laser systems achieve coagulation/hemostasis?

A

PHOTOTHERMAL CONVECTION- “Hot” effect” by defocusing beam - “Radiant Heat” > 60 degree C
(Contact Lasers-by Thermal Conduction-seals BVs)

84
Q

What are the sizes of Sapphire Tips used Lasers wih hollow-wave guide or articulated arm delivery systems?

A

Sapphire Tips sizes = 200 microns-1300 microns

  • Sapphire is a lower OH fiber*
  • **Diode Sapphire Tip sizes=200 microns-1200 microns
85
Q

The DUTY CYCLE of a 810 nm laser w 1 sec pulse?

1 sec pulse-emitted energy is ON=.5 sec and OFF=.5 sec

A

DIVIDE….5 sec PULSE WIDTH/1 sec PULSE DURATION =50% DUTY CYCLE

86
Q

What is a cold laser?

A

Very short WL UV lasers that react on a molecular basis NO PHOTOTHERMAL interaction. 1) ArF 2) XeCl

87
Q

What is the difference between Hard Lasers (high power) and Soft Lasers (low power)?

A

Soft Lasers- LOW POWER lasers interact INDIRECT with biological tissues 1) biostimulation 2) PDT
3) Caries detection 4) aiming beam

88
Q

What is the laser wavelength range for Photobiomodulation (PBM or LLLT) Soft Lasers?

A

600nm-1060 nm (HeNe 633 nm Vet Med) milliWatts

1) BIOSTIMULATION (Primary Therapy)
2) PDT-Photodynamic Therapy (Secondary Therapy) 3) Caries Detection (680 nm)

89
Q

What are the results of BIOSTIMULATION with a Soft Laser (PBM/LLLT)?
Sm doses over periods of time are more effect than closely sched txmts at higher doses

A

1) +local blood flow,macrophages,fibroblasts
2) -pain receptor mechanisms/+”feel good factors”
3) Used post-surgery, TMD,Trigeminal neuralgia, hypersensitivity, herpes, apthous ulcers

90
Q

What happens at the cellular level in PBM/LLLT Soft Laser Therapy?

A

Light Photons-absorbed by the Mitochondria of the cell…alters cell membrane/permeability…+mRNA synthesis 1) Biostimulation 2) Anti-inflammation 3) Analgesic

91
Q

Hard Tissue WLs?

A

Argon 488-513nm (visible/bleaching/curing)

Diode 800-980 nm Nd:YAG 1064 nm Er,Cr:YSGG 2790 nm Er:YAG 2940 nm CO2 9300 nm

92
Q

Which wavelengths can cause more Edema due to deeper penetration into tissues?

A

Shorter WLs 1) Diode 2) Nd:YAG

93
Q

What was the first dental WL available?

A

Nd:YAG 1064 nm Hb/Melanin
1) dental sensitivity to close dentinal dentubles 2) Endo- remove pulpal tissues…depth of penetration is 2 mm, lase 2 mm < working length (apex)

94
Q

Why do we use the minimum power to reach treatment objective?
TEMP to underlying tissue is related to POWER

A

No difference in cutting efficiency when increase power, temp increases as power increases/Coagulation starts @ 50 Hz-100 Hz start cutting at 50 Hz, when increased coagulation is needed, increase to 100 H

95
Q

Which laser can cause problems with Edema in periostal bone if use too much power?

A

Nd:YAG too much power, too much heat…if see carbonization too much power=”hot tip”-depth of penetration is too much…have to move quickly, don’t use too long

96
Q

If use Nd:YAG on tooth structure, what happens?

A

Depth of Penetration is too much - too much heat generated and transmittance of energy to pulpal tissues

97
Q

Why aren’t Erbium pulsed lasers good for use in soft tissue surgeries?

A

Cuts vessel-No coagulation…microsecond pulse so fast, no heat generated (which is good for pulp when cutting hard tissues)

98
Q

What is the temp of the H2O in Enamel/Dentin heated up Er:YAG lasers?

A

Walls of Prep=800-1000 degrees Celsius
(Need to keep Pulp Temp rise <4 C)
similar to HS handpiece with H2O

99
Q

How do higher WL lasers (Er:YAG, Er,Cr:YSGG, CO2 affect hydroxyapatite?
CO2 @ 9.6 micrometer=8000=Absorp Coeff
(Er:YAG @ WL=2.94 micrometer=only 770 Absorp Coeff)

A

Higher WL lasers change carbonated cHA to HA-more acid resistant form (can add Fl ions to change HA to Fluorapatite, increases acid resist even more)
(400-900 C) Er:YAG Er,Cr,:YSGG CO2 lasers

100
Q

What is the melting Temp of Enamel?

A

1000 degrees Celsius (Er:YAG laser heats Enamel to 400-900 degrees Celsius-cHA converts to HA-“stronger”)

101
Q

Why is Er:YAG laser better with bone surgery than high speed drill? (for Bone surgery-use Nd:YAG or CO2)

A

No smear layer when using laser…Rotary Drill creates “smear layer” and if not removed creates sig inflammation post-operatively (pain)…plus thermal cracking

102
Q

What Laser WLs can be used for Laser Bleaching?

A

1) Argon=200 mJ (low power/best choice) 2) Nd:YAG low power=100 mJ/10 Hz 3) CO2 low power=1 Watt CW

103
Q

Which Laser has selective absorption in bacteria only (Calculus or carious lesions)?
doesn’t ablate healthy Dentin/Cementum

A

Alexandrite=377 nm w/ Frequency Doubled

*selective Calculus/Caries removal w/o harm to Cementum or Dentin (explodes bacteria to remove)

104
Q

What is PHOTOTHERMAL ABLATION seen in Med/Far IR Lasers?

A

LIGHT ENERGY is changed into HEAT during ABSORPTION by the target tissue (H2O=chromophore)

105
Q

What is the tissue-interaction that occurs when Mid IR Lasers (Erbiums) are used in soft tissue surgeries?

A

PHOTOTHERMAL vaporization of H2O=100 degrees C

106
Q

What is the tissue-interaction that occurs when MID/FAR IR Lasers are used in soft tissue surgeries?

A 
PHOTOTHERMAL ABLATION ("vaporization") of H2O in soft tissue (also vaporizes H2O in enamel,dentin,bone)
**Heals by secondary intention**
107
Q

Does the explosion of H2O in hard tissue by Erbium Lasers generate heat?

A

No-minimal heat transfer to surrounding tissue…water spray from handpiece acts as heat sink…keep tip moving
(Pain w/ Erbium would be from heat/close to pulp)

108
Q

Why does Erbium WLs have preferential selectivity for dental disease?

A 
Dental Caries ("carious tooth structure") >H2O content than Healthy Dentin > H2O content than Enamel
**Erbiums remove the smear layer***
109
Q

How is a CO2 laser @ 9300nm WL different than Erbiums?

A
  • CW that is Micropulsed=<10,000 Hz/Pulse Width=300-100 msecs/HIGH ENERGY DENSITY LEVELS=10-20 J/Cm2
  • Bacteriocidal (Erbiums only reduce bacteria in soft tissue)
  • Char-free Ablation-heal by secondary intention
110
Q

What is the 3 gases in the active medium of CO2 Lasers?

A

1) CO2 2) Nitrogen 3) Helium

111
Q

Diff between Isotopic CO2 Laser @ 9,300 nm and CO2 Laser at 10,600 nm? (Both=char-free soft tissue ablation)
(Both=low level of penetration=50-100 microns/pulse)

A

9,300 nm = Hard Tissue removal (Solea)

10,600 = Soft Tissue surgeries (Light Scalpel)=H2O chromophore=spot size=100,200,500 microns

112
Q

Which NEAR IR Laser can be used for new LANAP (bone regeneration) procedure (Alternative to Perio surgery)?

A

Nd:YAG LANAP=”Laser Assis New Attach Procedure”

*cementum-mediated new PDL attachment to root surface in the absence of long junctional epithelium

113
Q

NEAR IR Laser-used for Endo (retreatment, removal of files/canal obstructions) and Peri-implantitis Txmt?
Which NEAR IR Laser is used in canal -bacteria?

A

Nd:YAP (“Perovskite”) 1340 nm FRP laser/Fiber DIRECT-contact-THERMAL ABLATION of soft tissues
Can use to ablate Fx endo file*
Er,Cr,:YSGG=radial tip-antimicrobial-dentinal tubules

114
Q

How is PDT (Photo Dynamic Therapy, Soft Laser @ 630 nm) with SOFT LASERS used for Cancer Therapy?

A

*Selective malignant tumor destruction-low WL laser light to ABLATE TUMOR (IV injection of haemoporphorin derivative, absorbed by tumor site then expose site to laser light, nascent O2 radicals released)

115
Q

BIOSTIMULATION (PBM therapy)-what is the Fluence (Energy Density) levels in the therapeutic window (“Arndt-Schultz Curve”)? 540 nm-830 nm

A

Cell Stimulation >2 J/cm to 6 J/cm2 < Cell Inhibition

  • HIGHER FLUENCE=6-10 J/cm2=ANTI-INFLAMMATORY
  • HIGHEST FLUENCE=20-50 J/cm2=ANALGESIC (“acute”)
116
Q

LLLT/PBM applications in Dentistry?

soft laser or cold laser < 1 Watt of energy

A

Post-surgery Healing, Bone/Nerve Regeneration, Paresthesia, Pain, Dentin Hypersensitivity, Herpes, Mucositis, TMD, Trigeminal Neuralgia

117
Q

Applying or systemically introducing a material that in the presence of laser energy will be transformed into a useful material/create the release of singlet O2 that will cause disruption of cellular membrane, is called what?

A 
PHOTODYNAMIC THERAPY (PDT)=Photo-activated Medication Delivery=Photosensitizer agents+O2+
LLL Light=ROS (Reactive O2 Species)=Microbial reduction or Selective Destruction of Tumors
118
Q

What are uses of PDT (photodynamic therapy) in dentistry? “photo-sensitive liquid injected into body …selectively accumulates within unhealthy cells”

A

Localized Osteitis, Perio Dz, Herpes/Apthae, mucositis, Peri-implantitis/Perio-mucositis, Endo (-bacteria), post-invasive tooth prep and oral cancer (Photophrin dye)

119
Q

Which visible (“green” Laser @ 532 nm is used for bleaching (“red alkaline gel”), photoablation and photocoagulation?

A

KTP LASER = FREQ DOUBLED (2X) Nd:YAG Laser …directed through a POTASSIUM-TITANYL-PHOSPHATE CRYSTAL (“less heat”) PERIOENDO*PBM

120
Q

Which CO2 laser can be used to altar the surface structure of tooth enamel to render it resistant to caries?

A

9600 nm-Absorp Coeff=8000 (ENAMEL REMODELING)

*changes to enamel surface occur w/o harming pulp

121
Q

The distance between the APICAL END of the GINGIVAL SULCUS to the CREST of ALVEOLAR BONE is called?
Keep finish lines approx .5 mm subgingival*

A

Biologic Width of Attachment (BWA)APPROX 2.79 mm (1.77 mm-2.43 mm?)…allow 3 mm (BWA+Connective Tissue Attach+Junct Epi+Gingival Sulcus)

122
Q

LASER Excisional Biopsies Technique…

A
  • 45 degree angle towards tissue base/slight tension
  • Biopsy should include normal tissue margins
  • do not carbonize lesion/biopsy report state used laser
123
Q

APTHOUS ULCER (HERPETIC LESION) Technique…

  • can use most WLs (CO2s/Erbiums-no H2O spray)
  • *should take 1-2 min total…poss need anesthetic?
A
  • start at CW=.5 W around lesion border for 30 secs
  • each 30 sec pass increase power until evap exudate
  • Uninitiated Fiber=2mm out of contact=Radiant Heat”
124
Q

What is the most efficient way to cut enamel with Hard Tissue Lasers?

A
  • Tip should be parallel to the direction of the enamel rod exit @ target interface-DO NOT aim into groove
  • Prep will be spoon or bowl shaped
  • Bevel Enamel cavosurface-seal photochemical bond
125
Q

How to achieve LASER ANALGESIA?
Physical Effects: 1) Occlude narrow dentinal tubules
2) Evaporation of intra-tubular transmitter fluid

A
  • Defocus Fiber Tip (Erbium 1 cm for 1-2 min)
  • Reduce Power
  • Increase H2O
  • Increase Frequency (+Hz)
126
Q

LASER ANALGESIA using GATE CONTROL THEORY…

Lasers at Lower Power/Frequencies…

A

+C Fibers (larger)=increase inhibitory neuron influence…GATE IS CLOSED to “pain perception
*A beta Fibers (smaller)=reduce inhibit neuron influence …OPENS GATE to “pain perception”

127
Q

Effect of Er:YAG on Pulp vs HS drill (in study of rats)?

*Mid IR Laser pulp chamber temp - < 5 degrees C

A

Er:YAG is less damaging to pulp and faster rate of repair (calictonin gene-related peptide immunoreative fibers)

128
Q

Treatment Technique for Peri-implant Mucositis…

PD < 4mm w/o bone loss (BOP/SOP)

A
  • Soft Tissue Incision/uncovering implant (most WLs)

* Osseous Tissue Prep - use Erbium Lasers (want less hemostasis-improved perfusion)

129
Q

Which laser is absorbed by camphor quinone?

A

ARGON Laser 488-512 nm Visible/CW/Fiber(“contact”)

1) cure composite resin 2) Bleaching 3) Melanin/Hb (good scalpel/hemostasis)

130
Q

Advantages of Laser use in non-Contact Mode?

A

1) Defocused beam reduces power density
2) Greater area of tissue exposed to beam
3) Greater control of Laser-Tissue Interaction:LOWER
RISK OF DEEP PENETRATION OF LASER ENERGY

131
Q

Disadvantages of Laser use in non-Contact Mode?

A

1) Defocused beam reduces power density
2) Greater area of tissue exposed to beam
3) GREATER RISK OF COLLATERAL DAMAGE
4) May mimic LLLT action

132
Q

SUMMARY POINTS FOR LASERS IN DENTISTRY:

OPTIMAL EFFECTS only occur with energy ABSORPTION by target tissue

A
  • Delivery modes can influence power levels

* Laser-tissue interactions obey the laws of optical physics

133
Q

IDEAL LASER TISSUE INTERACTION SUMMARY:

CHOOSE CORRECT WL FOR MAXIMUM INTERACTION

A

*Use MINIMUM POWER to achieve desired tissue interaction *Expose tissue to laser light for MINIMUM TIME to achieve interaction * Achieve MAXIMUM THERMAL RELAXATION to prevent collateral thermal damage *Prevent unwanted damage episodes

134
Q

LASERS USED IN ENDO PROCEDURES

A

1) Nd:YAG - remove files/disinfect canals 2) Nd:YAP

2) Diodes - Disinfect canals 3) Er,Cr:YSGG

135
Q

ADV of Laser Excision vs Scalpel

Less Post-op pain but “NOT QUICKER” healing

A

Accuracy/Ease of Access/No bleeding (depends on WL)/No sutures/Reduced Inflammatory response/Reduce bacterial contamination-“more sterile”

136
Q

Tissue Reaction with NO CHANGE IN WL

A

1) REFLECTION 2) SCATTERING 3) TRANSMISSION

137
Q

What is Q-SWITCHING (“Giant Pulse Formation”)?

Controlled Pulse vs “Free Running Pulses w/ Flashlamps

A

“Controlled Pulse”…allows a laser to produce one High Very High Power Peak per “pulse”…(ie Selective ablation of calculus, Lasers used to remove TATOOS)

138
Q

CONTENTS OF PLUME?

A

toxic gases/vapors, polycyclic aromatic hydrocarbons and particulates (carcinogens, mutagens, irritants,fine dusts,blood fragments,bacterial spores and viruses

139
Q

What causes Photokeratitis?

A

UV rays causes “sunburn” to CORNEA,CONJUNCTIVA

140
Q

What are examples of PHOTOACOUSTIC Effects?

A

…localized vaporization of tissue or fluids …then a rapid increase in pressure produce by VAPORIZATION-creates mechanical shock waves, causing disruption/damage

141
Q

What is HeNe (“gas/DC electrical charge”) laser used for?

RED=632.8 nm or GREEN=543.5 nm

A

1) LLLT

2) Aiming beam for dental lasers

142
Q

What does the FLUORESCENCE in caries detection mean?

A

…when exposed to light-also “emits light” (the WL of emitted light is LONGER that the ABSORBED LIGHT)

143
Q

BEST PRACTICE in Laser Dentistry includes the following:

A

1) Knowledge of the laws of Biophysics and Safety

2) Application of knowledge and Clinical Skill

Laser Dentistry (2 decks)

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