Islam Kassem, BDS , MSc, MOMS RCPS Glasg,

FFD RCSI

Consultant Oral & Maxillofacial Surgeon

Medical Topics in Orthodontics

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Criteria of selected technique

Effect on healing

Effect on pain

Effect on edema

Effect on intra operative bleeding

Effect on Tooth structure

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L A S E R

Light Amplification

by

Stimulate

d

E mission

of

Radiation

Lasers Laser theory

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Model of an atom by Niels Bohr

Born in Copenhagen

1922: Nobel Physics Prize winner

Lasers Laser theory - basics

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The laser – a very special light

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Laser Characteristics Monochromatic

Collimated

Coherent

High energy

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Coherence:

Temporal and spatial synchronization of wave movement

Lasers Laser theory – Basics: laser light

Normal light Laser light (coherent)

Temporal coherenc

e

Spatial coherenc

e

Laser

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Lasers Design of a laser

Fully reflecting mirror

Resonator

Reflector Semipermeable mirror

Reflector

Medium

Flash lamp

Laser medium

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According to wave length

IR Visible Ultraviolet

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According to delivery

Articulated arm

Wave guide

Fiber optic

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Laser Classifications

According to laser medium

Solid(ND:YAG Liquid (Dye) Gas (CO2)

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According to mode

CW Pulsed Super and

Ultra pulsed

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Laser tissue Interaction

Laser may be

Scattered Reflected Absorbed

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Warm-up

37 – 60°C

none

none

Penetration of protein

60 – 65°C

Whitish-gray coloration, increased dispersion

Decomposition

Desiccation

90 – 100°C

Constant dispersion

Shrinkage, dehydration

Carbonization

Several hundred °C

Black coloration, increased absorption

Strong mechanical damage

Vaporization Combustion

Formation of smoke and gas

Ablation

Temperature

Process

Optical change

Mechanical change

Lasers Interactions between laser light and tissue

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Lasers Effect of the laser on biological tissue

Damage

reversible irreversible

Vaporization

Carbonization

Coagulation

Laser beam

Tissue

Hyperemia

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Laser tissue interaction Photo thermal (CW)

Photo chemical (CW ,Pulsed

Photo ablation Pulsed)

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Effects on human tissue

Transmission

Absorption

Reflection

Lasers Laser-tissue interaction: Beam trajectory

Dispersion

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A therapeutic effect is attained only if the tissue absorbs the laser energy!

Lasers Laser-tissue interaction

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Chromophores

According to the optical properties of tissues. For example CO2 Water

This Character is strongly affected by the laser physical properties .

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Carbon dioxide laser

Patel et al., working in Bell laboratories in 1964, were the first to develop the CO2 laser.

Carbon dioxide (CO2 ) lasers have been used in dentistry in the specialty practice of oral surgery and periodontology since the early 1980s, in the past five years, the use of these lasers has extended into general practice.

CO2 laser was the first laser approved by the FDA

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Of greatest significance is the high degree of absorption by oral mucosal tissues, which are composed of 90% water. Absorption of the laser by intracellular water results in a photo thermal effect that is manifested by cellular rupture.

This cellular vaporization is the basis for the use of the CO2 laser as a surgical tool.

Heat is generated and conducted into surrounding tissues, creating a zone of lateral thermal damage; this zone of necrosis has been found to be 500 mm or less Lateral thermal damage results in coagulation of vessels up to 500 mm in diameter and is clinically manifested by homeostasis.

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Post surgical bacteremia also has been found to be greatly reduced with laser use as a result of sealing of blood vessels and lymphatic compared with other methods of incision Laser wounds exhibit histological features that confer significant advantages over those created by scalpel .

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Laser Hazards

Class I Laser videodisk Class II Laser Pointer Class III Surgical laser Class IV Fire laser

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Laser Safety & Protection

1- Eye protection

2- protection to lips , skin of the face

3- Protection from fire , toxic gases .

4- Laser reflection from surgical instrument.

5-Hazards of laser smokes

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Clinical applications

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Low level laser

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My Contact

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You can ge the lectures form

http://www.slideshare.net/islamkassem/newsfeed

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