Lasers

Question 1

What does LASER stand for?

Answer 1

Light Amplification by Stimulated Emission of Radiation

Question 2

Lasers are by definition…

Answer 2

Coherent, Monochromatic, and Collimated

Question 3

Coherent?

Answer 3

Synchronized in motion (all in same phase due to same source)

Question 4

Monochromatic?

Answer 4

Single color (due to single wavelength)

Question 5

Collimated?

Answer 5

Travels in a straight line

Question 6

The distance a photon travels through one oscillation

Answer 6

wavelength

Question 7

Laser light travels in a straight line until it is…

Answer 7

absorbed, reflected, or refracted

Question 8

power density=?

Answer 8

watts/cm2

Question 9

Unit if energy, or ability to do work

Answer 9

Joule

Question 10

Unit of Power, or rate of doing work

Answer 10

Watt

Question 11

1 watt=?

Answer 11

1 J/second (1,000mJ/second)

Question 12

Continuous wave mode

Answer 12

The laser is on as long as the foot pedal is pressed. This creates hot and thermal damage

Question 13

Gated/Chopped Pulse Mode

Answer 13

A period of thermal relaxation between pulses. This allows target tissue to warm slowly

Question 14

Free-running Pulse Mode

Answer 14

Extremely short pulses and relatively long thermal relaxation

Question 15

This mode of laser usually uses water and or air to assist in cooling of tissues?

Answer 15

Free-Running Pulse Mode

Question 16

Zones of laser ablation (from outer to inner)

Answer 16

Zone of Denaturation; Zone of Vacuolization; Zone of Carbonization

Question 17

Class 1 lasers

Answer 17

Safe from all hazards (CD players)

Question 18

Class 2 Lasers

Answer 18

Damage could occur after prolonged exposure (laser pointers)

Question 19

Class 3a lasers

Answer 19

(1-5mW) Direct viewing could be hazardous to eyes

Question 20

Class 3b lasers

Answer 20

(5-500mW) Direct viewing and reflections can be hazardous

Question 21

Class 4 lasers

Answer 21

(>500mW) this is the class we use in dentistry

Question 22

Standards, Organizations, and Regulatory Requirements

Answer 22

• FDA center for devices and radiological health (CDRH)
• American National Standards Institute (ANSI)
• OSHA
• State and Local regulatory agencies

Question 23

% reduction in post op pain after using lasers

Answer 23

90%

Question 24

Diode Lasers

Answer 24

810-980nm
Soft tissue, low level therapy, laser whitening
highly absorbed by pigment

Question 25

Nd:YAG lasers

Answer 25

1064nm (near infrared portion of spectrum)
Solid state laser (crystal)
soft tissue only

Question 26

Erbium Lasers

Answer 26

Er,Cr:YSGG= 2780nm
Er:YAG=2940nm
mid infrared portion
Water and hydroxyapatite (minimal heat transfer)

Question 27

CO2 lasers

Answer 27

10,600nm
Soft tissue and bone
absorbed by pigment, water, and hydroxyapatite