medical problem 3 4
TRANSCRIPT
Islam Kassem, BDS , MSc, MOMS RCPS Glasg,
FFD RCSI
Consultant Oral & Maxillofacial Surgeon
Medical Topics in Orthodontics
Criteria of selected technique
Effect on healing
Effect on pain
Effect on edema
Effect on intra operative bleeding
Effect on Tooth structure
L A S E R
Light Amplification
by
Stimulate
d
E mission
of
Radiation
Lasers Laser theory
Model of an atom by Niels Bohr
Born in Copenhagen
1922: Nobel Physics Prize winner
Lasers Laser theory - basics
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
Lasers Design of a laser
Fully reflecting mirror
Resonator
Reflector Semipermeable mirror
Reflector
Medium
Flash lamp
Laser medium
Laser Classifications
According to laser medium
Solid(ND:YAG Liquid (Dye) Gas (CO2)
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
Lasers Effect of the laser on biological tissue
Damage
reversible irreversible
Vaporization
Carbonization
Coagulation
Laser beam
Tissue
Hyperemia
Laser tissue interaction Photo thermal (CW)
Photo chemical (CW ,Pulsed
Photo ablation Pulsed)
Effects on human tissue
Transmission
Absorption
Reflection
Lasers Laser-tissue interaction: Beam trajectory
Dispersion
A therapeutic effect is attained only if the tissue absorbs the laser energy!
Lasers Laser-tissue interaction
Chromophores
According to the optical properties of tissues. For example CO2 Water
This Character is strongly affected by the laser physical properties .
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
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.
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 .
Laser Hazards
Class I Laser videodisk Class II Laser Pointer Class III Surgical laser Class IV Fire laser
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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