Final Copy Of Lasers In Dentistry Dr.nikhil Saran
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13/10/2009
THE HOLY GRAIL OF MODERN DENTAL PRACTICE.
LASERS IN DENTISTRY (A REVIEW) 1
CONTENTS INTRODUCTION SIGNIFICANCE IN MODERN DENTAL PRACTICE REVIEW OF HISTORY AND DEVELOPMENT FUNDAMENTAL OF LASER PHYSICS AND ITS COMPONENTS
a)Laser principles b)Laser properties c)Measurements of laser d)Laser generation e)Beam Profile and Spot Geometry f) Power Density(PD) 2
Cont…
LASER DELIVERY SYSTEM LASER EMISSION MODE LASERS AND TISSUE INTERACTION a)OPTICAL PROPERTIES OF TISSUE b)TISSUE EFFECT OF LASER IRRIDIATION
CLASSIFICATION OF LASERS TYPES OF LASERS SOFT AND HARD TISSUE APPLICATION OF LASERS IN DENTISTRY 1.Laser in endodontics 2.Laser in operative and esthetic dentistry
LASERS SAFTY IN DENTAL PRACTICE CONCLUSION REFRANCES
3
INTRODUCTION LASERS can be defined as 1. A device that utilizes the natural oscillations of atoms or molecules between energy levels for generating coherent electromagnetic radiation usually in the ultraviolet, visible, or infrared regions of the spectrum -Merriamwebster.com 1. A device which amplifies electromagnetic energy at various optical frequencies into an extremely intense small and nearly non divergent beam of bright light of a single color. Capable of mobilizing intense heat and power when focused at a close range, it is used as tool in surgical procedure , in diagnosis and in physiological studies. 4
cont. To d a y
La se rs a re e m p lo ye d fo r va rio u s p u rp o se s ra n g in g fro m Ømeasuring distances of the far planets, Øcreate laser guided warfare, Øentertainment, Øinstrumentation Øand even those that record the price of our groceries. And many more ……….
5
6
CONT… But
out of all odds the main and most advantageous purposes of is found in the field of HEALTH CARE INDUSTRIES.
7
SIGNIFICANCE IN MODERN DENTAL PRACTICE.
Today's dream and tomorrow's reality
lasers can be used to enhance the once clinical practice and the treatment out come also.
Dentist should become laser literate, consumer wise and that’s how increasing the potential of its use in day to day clinical practice with patient acceptance.
To understand the differences between variety of lasers and their vivid application.
Understanding lasers in an easy and understandable
8
Worldwide laser sales by application
9
REVIEW OF HISTORY AND DEVELOPMENT
Use of light for treatment of various pathologies is referred to as phototherapy.
Ancient Greece sun for heliotherapy, by exposure of the body to the sun for the restoration of health .
Late 1700s the Chinese used the sun to treat conditions such as rickets, skin cancer, and even psychosis.
In 1400 B.C. INDIANS used psoralens(a plant extract),to treat vitiligo.
10
cont… 1903,
a Danish physician Niels Finsen used carbon arc phototherapy for the treatment of lupus vulgaris by using UV rays.
11
Foundation of laser development
In 1917 Albert Einstein, in his “The Quantum Theory of Radiation”, laid the foundation for the invention of the laser and its predecessor, the maser,
In 1928, Rudolf W. Ladenburg confirmed the existence of stimulated emission and negative absorption.
In 1939, Valentin A. Fabrikant predicted the use of stimulated emission to amplify "short" waves.
In 1947, Willis E. Lamb and R. C. Retherford
12
Development of the lasers
The earliest use of photochemotherapy, or the use of an exogenous photosensitizerto absorb light and render a therapeutic effect
In 1974 it is evidenced that psoralens combination with exposure to ultraviolet radiation was indeed effective in the treatment of psoriasis and vitiligo.
Theodore H. Maiman of Hughes Aircraft Corporation in 16 May 1960 developed the first laser, or “ MASER“ an acronym for "Microwave Amplification by Stimulated Emission of Radiation,".
Snitzer in 1961 developed neodymium laser
Carbon dioxide laser -Kumar Patel in 1964 13
T h e o d o re H . M a im a n
Le o n G o ld m a n 14
Cont…
In 1965 Taylor et al studied histological effect of laser on the pulp
In 1968 Lobene et al used carbon dioxide laser in dentistry
Weichman & Johnson 1971 used laser for the first time in sealing of the apical foramen in vitro by means of a high power-infrared (CO2) laser
In 1974 Yamamoto et al used Nd:YAG laser for caries prevention
In 1977 Lenz et al used laser for the first time in maxillofacial surgery
15
R e f:- la se rs in d e n tistry b y
16
RECENT DEVELOPMENTS
1987 Meyer and mayer developed a Portable Laser
1990 FDI permitted the use of the same in the dentistry
The FDA approved oral soft tissue surgery in 1995 and sulcular debridement in 1998 by means of a diode laser
Hibst et al. 1999-2001 developed a novel laser 17 for caries detection (Diagnodent-KaVo,
FUNDAMENTAL LASER PHYSICS
The word LASER is an acronym for Light Amplification by Stimulated Emission of Radiation.
L A S E R
Light Amplification by Stimulated Emission of Radiation 18
UNDERSTANDING LIGHT
Form of electromagnetic energy that behave as a particle and a wave as well. light produced by a table lamp, for example, is usually a white diffused glow, although it is the sum of the many colors of the visible spectrum—violet, blue, green, yellow, orange, and red. A prism can be used to separate the individual colors in the same way that raindrops break up sunlight into the colors of a rainbow.
19
AMPLIFICATION
The initial light is amplified to make a very bright compact beam
20
STIMULATED
means that the photons are amplified by stimulating an atom to release more photons.
An atom can exist in an excited state, similar to a bow when it is stretched.
21
EMISSION
Refers to the giving of photons.
The excited atom emits a photon when another photon comes by.
Einstein(1917) Stimulated Emission.
22
RADIATION
For lasers, radiation refers to the PHOTONS which are being emitted.
23
Properties of LASER light
Monochromatic (single wavelength)
Collimation
( specific boundary)
Coherency
(in same phase)
Efficiency
(how good it works)
Directional (narrow cone of divergence)
24
monochromaticity Laser
light is one specific color, a property called monochromacity; in dental applications that color may be visible or invisible.
25
collimation
Collimation refers to the beam having specific spatial boundaries, which insures that there is a constant size and shape of the beam emitted from the laser cavity. A dental x-ray machine produces radiation with this property.
26
coherance
Coherency means that the light waves produced in the instrument are all the same. They are all in phase with one another and have identical wave shapes; that is, all the peaks and valleys are equivalent.
27
Efficiency and its measurement
The clinically useful feature of laser is efficiency.
Three measurements that can define the wave of photons in a laser.
The first is velocity, which is the speed of light.
The second is amplitude, which is the total height of the wave. It indication of the amount of intensity in the wave.
The third property is wavelength, which is the distance between any two corresponding points on the wave on the horizontal axis.which is important in determining 28 how the laser light is delivered to the surgical site and to
Electromagnetic Waves
Amplitude
Wavelength
Velocity
Frequency is the number of complete oscillations of the wave per second. 29
directionality
30
Laser generation
31
32
33
Components of Laser system
La sin g a ctive m e d iu m .
Energy or
Pumping source.
Optical chamber.
34
Lasing medium: A
material, capable of absorbing the energy produced by an external extension source through the subatomic configuration of its component molecules, atoms or ions. subsequently give off this excess energy as photons of light.
35
Energy or pumping source An
energy source is used to excite or pump the atoms in the lasing medium to their higher energy levels that are necessary for production of laser radiation.
36
Optical Chamber The
lasing medium is located within resonating chamber which has cylindrical structure with a fully reflecting mirror on one another.
37
Core cavity
The core cavity or the optical cavity is comprised of chemical elements, molecules, or compounds which is called the active medium, which can be container of gas, a crystal, or a solid state conductor. The other devices are either solid state semiconductor wafers made with multiple layers of metals such as gallium, aluminum, indium and arsenic.
High Voltage Power Supply
= atoms
cathode
100% Reflective Mirror
anode
Beam output
Active Medium 98% Reflective Mirror
38
39
Beam Profile and Spot Geometry
There are more photons concentrated in the core of the beam and that the light intensity diminishes at the edges. Often in a well-tuned cavity the transverse cross section (profile) is the normal gaussian curve. This is referred to as the TEMoo (transverse electromagnetic mode: 00), also called the "fundamental mode“) Other modes are possible such as the "Donut" mode (TEM10), which has a cold spot in the center.
40
Power Density(PD) Power
density is simply the concentration of photons in a unit area. Watts per area in square centimeters. Therefore, PD = W/cm2
(This is the average PD. Notice from the beam profile that the PD in the center of the spot is higher and that at the edge of the spot it approaches 0). 41
Cont…
The terms focused and defocused when working with lasers refers to the position of the focal point in relation to the tissue plane.
When
working on tissue, the laser should always be used either with the focal point positioned at the tissue surface (in focus) or positioned above the tissue surface (defocused or out of focus).
The
laser should never be positioned with the focal spot deep or within tissue
42
43
Laser delivery system
Contact lasers It works on the “hot tip” principal It improves cutting efficiency for low-power instruments Requires cleaning or cleaving the fiber to attain desired results
Non contact lasers Noncontact surgery relies completely on the pigments and water present in the tissue. Noncontact surgery requires significantly greater power settings than contact surgery. The techniques and principles are similar, only the feel is different. During noncontact surgery, the clinician operates with the aid of an aiming beam or by44
Laser delivery medium
Articulated arm- consist of a series of rigid hollow tubes with mirrors at each joint (called a knuckle) that reflect the energy down the length of the tube.
DISADVANTAGES 1. Bulky 2. Awkward three-dimensional maneuverability 3. Alignment of the mirrors 4. Articulated arm delivery systems are noncontact systems 1.
2. 45
Fiberoptic delivery system-The fiberoptic cables are attached to a small handpiece similar in size to a dental turbine. Advantages 1. Relatively flexible 2. Easy transmission of the laser energy throughout the oral cavity 3. Fiberoptic technology allows for contact with the target tissue Disadvantage 1. Costly 2. 3. 4.
46
Hollow waveguide delivery system – waveguide is a single long, semiflexible tube, without knuckles or mirrors. The laser energy is transmitted along the reflective inner lumen of this tube and exits through a handpiece at the end of the tube Advantages 1. Can be used as contact and non contact mode 1. Various attachments for hand piece Disadvantages 1. Available with co2 laser and erbium system only
47
Air-cooled fiberoptic delivery system – This type of delivery system is unique to the erbium family of lasers. A conventional fiberoptic delivery system cannot transmit the wavelength of the erbium family of lasers, owing to the specific characteristics of the erbium wavelength. These special air-cooled fibers terminate in a handpiece with quartz or sapphire tips. These tips are used slightly (1–2 mm) out of contact with the target tissue.
48
Laser Emission Modes
Emission of energy in 3 modalities
Continuous wave : Beam emitted at only one power level for as long as device is operated by pressing the foot switch
Gated pulse Mode: Periodic attenuations of laser energy being on & off similar to blinking light. The duration is as small as a few mille sec
Free running pulsed mode: large peak energies are emitted for an extremely short time span followed by long time of which laser is off. It is 49 computer controlled.
50
Several means are available for achieving pulsed output from a continuous wave laser. These are:
Mode locking
Q switching
Pulses from pico sec.
to micro sec Cavity dumping
Pump pulsing
from one microsecond to
a large fraction of sec 51
WHATS IN THE HAND OF OPERATOR?
52
Tissue effects of laser irradiation Broadly
the tissue effects of lasers can be groups as. 1.Photo 2. 3.Photo 4. 5.Photo 6. 7.Photo
chemical interaction thermal interactions mechanical interactions electrical interaction 53
Photo Chemical Interactions:
Specific wavelength absolved by naturally occurring chromophores
Wavelength specific light absorption substances are able to induce certain biochemical reactions at the cellular level.
Photo Chemical interactions are subdivided into
1.Photodynamic Therapy
2.
54
Photodynamic therapy Therapeutic use of lasers to induce reactions in tissues for treatment of pathologic conditions
Biostimulation The stimulatory effects of the laser light on biochemical & molecular processes that normally
55
Photo thermal Interactions:
Radiant energy absorbed by tissue -> transformed into heat energy which produces tissue effect.
The amount of light energy absorbed in tissue depends on:
1.Wavelength of radiant energy from laser.
2.Laser parameters such as spot size, power density, pulse duration & frequency.
3.Optical properties of tissue. 56
Laser heating and tissue temp
What Occurs when , if energy is absorbed 1.Hyperthermia- temp . Increase but not destroyed, tissue whitening or blanching 2.Coagulation –Irreversibly damages the tissue, by congealing tissue liquid into semisolid mass, good to archive homeostasis 3.Welding -Adherence of the layers because of stickiness due to the collagen molecule’s helical unfolding and intertwining with adjacent segments 4.Vaporization - tissue containing water is elevated to a temperature of 100 c, process also called as ablation 5.Carbonization - about 200 c, dehydrated 57
Thermal effects at different temp.
Temperature
Tissue Effects
37-50
Hyper thermia
60-70
Coagulation, protein denaturation
70-80
Tissue Welding
100-150
Vaporization and ablation
>200
Carbonization & charring (As in DCNA 2004 vol.48;759)
58
THE ZONE OF LASER INTERACTION WITH THE TISSUE
59
Photo Mechanical & Photo Electrical Effects
Photon disruption or photo disassociation which is breaking apart of structures by lasers
Photo acoustic effects which involve removal of tissue with shock wave generation
Photo plasmolysis describes how tissue is removed through the formation of electrically charged ions & particles that exist in a semi gaseous high energy state. 60
laser action manifests clinically as:
Photo ablation or removal of tissue by 1.Vaporization 2.Super heating of tissue fluids, 3.Coagulation, 4.Homeostasis 5.Photo pyrosis or burning away of
61
Optical properties of tissue
62
63
Absorption and laser interaction with hard tissue
Dental structures have different amount of water content, Enamel being the least followed by Dentin, Bone, Calculus, Caries and Soft tissue Dental lasers have a Photo thermal effect At low temperatures below 100°C, the thermal effects denature proteins and produce hemolysis and they cause coagulation & shrinkage Above 400°C, carbonization of organic materials occurs with onset of some inorganic materials 64 Between 400°C & 1200°C, inorganic
In general, shorter WL (500-1000 nm) are well absorbed in pigmented tissues and blood elements Longer WL are more interactive with water and Hydroxyapatite Co2 (10,600 nm) is well absorbed by water and has the highest affinity for Hydroxyapatite
Tissue Hemoglobin Melanin Hydroxyapatite WL
Feature Absorbed by Blue & Green WL Absorbed by short wavelengths Absorbed by a wide range of 65
66
Classifications of lasers
In general lasers can be classified into no. of ways.
But chiefly on the potential of the primary laser beam or the reflected beam to cause biologic damage to the eyes or skin.
The ANSI Standard Z136.1-2000 documents set the standards for classification in the United States.
OSHA and the American Conference of Governmental Industrial Hygienists also use this standard as a source. Other countries subscribe to these standards and have their own similar regulatory agencies.
67
Based on the potential danger posed to the exposed skin and eye Class
I - Low powered lasers that are safe to view Class IIa - Low powered visible lasers that are hazardous only when viewed directly for longer than 1000 sec. Class IIb - Low powered visible lasers that are hazardous when viewed for longer than 0.25 sec. Class IIIa-Medium powered lasers or systems that are normally not hazardous if viewed for less than 0.25 sec without magnifying optics. Class IIIb-Medium powered lasers (0.5w max) that can be hazardous if viewed directly. 68
Classification OF LASERS Based
on Active Medium 1.Solid State 2.Gas 3.Semiconductors 4.Excimer 5.Dye
Mode
of action 1.Contact mode (focused or defocused) Ho:YAG ; Nd: YAG 2.Non-contact mode (focused or defocused) CO2 3. 69 4.
CONT… Based
as application 1.Soft tissue laser - Argon, Co2, diode; Nd:YAG. 2.Hard tissue laser - Er : YAG 3.Resin curing laser - Argon
Based
on Level of energy emission: 1.Soft lasers (Low level energy): He-Neon; Ga-Arsenide. 2.Hard lasers (High level energy): Er:YAG laser ; Nd: YAG laser.
70
71
72
Diode 812nm Diode (980nm) ErCr:YSGG 2.78 µm Ex c i m e r KTP (532nm) Er:YAG ( 2.94µm) KrF (248nm) XeF(351 nm) CO2 (9.6 or 10.6µm) HeNe (632nm)
Ultraviolet
Visible
Infrared
100 nm 400 nm ArF (193nm) XeCl (308 nm)
Ruby (694nm) 750 nm Ho: YAG 10,000 nm Argon (514 nm) Nd: YAG (2,08 µm) (1,06 µm) Argon (488 nm)
γ -rays 10-12
x-rays
UV 10 - 9
visible IR microwaves 10 - 6
1 0 -3
radio waves 1
acoustic waves
103 wavelength, meters 73
74
75
Laser Wavelengths Used in Dentistry Argon laser
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 The only available surgical laser device whose light is radiated in the visible spectrum. There are 2 emission wavelength used in dentistry: 488 nm, which is blue in color & 514 nm which blue green. 488 nm emission activate camphoroquinone(photo initiator), causing polymerization. The 514 nm wave length has its peak absorption in tissues containing hemoglobin, hemosiderin & melanin.Thus it has excellent haemostatic capabilities. 76
usages
Used in Surgical Endodontics
Both can be used for caries detection
Argon laser light illuminates the tooth, the disease area appears dark orange-red colored
Neither wavelength is absorbed by dental tissues or water
Their poor absorption by enamel and dentin is an advantage when used for incising and sculpting gingival tissues
77
Diode laser
A solid active medium laser, manufactured from (Gallium arsenide) semi conductor crystals using combination of aluminum or indium, gallium, and arsenic.
Wavelengths for dental use range are 800 nm for active medium containing aluminum to 980 nm for active medium containing indium.
Optic fiber delivery system with contact mode.
All of diode wavelength are highly absorbed by
pigmented tissue and are deeply penetrating 78
Neodymium :YAG 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.
Operates at wavelength of 1064nm in a high inter pulsed wave form.
It emits light in near invisible infrared area of spectrum.
Fiber optic cable to divert the light to a hand piece & lens to produce free beam of laser light 79
Common clinical applications are: For cutting & coagulating of dental soft tissues & debridement.
Offers good hemostasis during soft tissue procedures
For attaining pulpal analgesia
Advantages: Facilitates a clear operating field
Flexible delivery system.
Disadvantage: Is unnecessary collateral damage due to its depth of penetration.
Wound healing in soft tissue will be delayed
80
Holmium:YAG
solid crystal of yttrium aluminum garnet sensitized with chromium and doped with holmium and thulium ions Fiber optically delivered and free running pulsed mode Operates at a wavelength of 2100 nm and uses a pulsed waveform.
It is absorbed by water 100 times greater than Nd: YAG
At high peak powers, can abrade hard, calcified tissue.
An aiming device is used, as the light produced is invisible.
81
Erbium Family lasers
Erbium: YSGG (2780nm) with solid crystal of yttrium scandium gallium garnet doped with erbium & chromium
Erbium : YAG (2940nm) has crystal of yttrium aluminum garnet doped with erbium .
The delivery systems are a hollow wave guide and fiber optics in free running pulse mode.
The highest absorption in water & have a high affinity for hydroxyapatite.
82
Uses:
Caries removal and Cavity preparation
In preparation of root canals.
Facial resurfacing,
83
Carbon dioxide laser
It was developed by Patel in 1964.
A gas active medium laser that incorporates a sealed tube containing a gaseous mixture with Co2 molecules pumped via electrical discharge current.
Operates at wavelength of 10,600nm.
It is operated in a gated wave form or continuous form through a hallow tube like wave guide.
Wavelength is well absorbed by water.
It can easily cut & coagulate soft tissue & has a shallow depth of penetration into tissue.
Emits light in the invisible mid infrared portion.
84
Uses: Excision and ablation of various types of superficial lesions & for skin resurfacing
Excellent Hemostasis,
Advantages: Clear field of view.
Post operative pain is minimal
Disadvantages: Wound healing is delayed Difficult to uses (articulated arm)
85
newer lasers systems KTP Lasers (excimers)
Modified version of Nd: YAG laser:
Addition of frequently doubling crystal operates at 532nm.
It uses fiber optic cable with a hand piece.
It is similar to argon laser in absorption characteristics
Used in the treatment of vascular & pigmented lesions, tattoo removal 86
Flash Lamp pumped pulsed Dye Laser
Produces yellow visible light in 400–1000nm range & is commonly used at 510, 577, 585nm.
The desired wavelength can be used for specific tissue to be removed, offering great flexibility
510 nm melanin can be targeted & various benign melanin containing tissues can be ablated
585nm targets oxy-hemoglobin with in vascular abnormities.
Thus it is used in treatment of cancer, ablation of salivary 87
Copper Vapor Laser
Wavelengths of 511-578 nm.
Similar
to both KTP & Argon lasers.
Its
medium is heated copper which produces copper gas.
Delivered
mode
by fiber optic cable in pulsed
Effective
in treatment of port wine stains or large superficial telangiectasias, nevi &
88
Medical Applications of laser
Argon laser in ophthalmology 1968
Otorhinolaryngology
Dermatology & plastic surgery
Neurosurgery
Urology
Gastroinstestinal surgery 89
Why to select laser for treatment? Patients
choice Clinicians choice Treatment outcome assessment Utilizing benefits of lasers
Patient
comfort & acceptance Reduced
postoperative complications Hemorrhage control Reduced need for postoperative analgesics Advantage
over the cold steel surgical procedure 1.Dry and bloodless surgery 2.Instant sterilization of the surgical site 3.Reduced bacteremia 4.Reduced mechanical trauma 5.Minimal postoperative swelling and scarring
90
Types of Lasers
Hard lasers or high level lasers. Cavity Preparation on tooth surface Transillumination Photo polymerization Cortical bone ablation
91
Soft
tissue laser or low power
Temperature 37-50 60-70 70-80 100-150 >200
Tissue Effects Hyper thermia Desiccation protein denaturation Tissue Welding Vaporization and ablation Carbonization & charring (As in DCNA 2004 vol.48;759) 92
Hard and soft tissue difference Hard
Lasers: Have
longer wavelength more then 450nm Produces thermal effect, which cut the tissue by coagulation, vaporization & carbonization. These lasers are used for surgical hard tissue applications.
Soft
or low-level lasers Low
thermal energy wavelengths of less than about 450nm with minor temperature increase of less than 1C. Stimulate circulation and cellular activity. Anti-inflammatory, Muscle relaxation, Analgesia 93
Laser application in vivacity of dentistry
Biopsies
Tongue lesions
Aphthous ulcers
Herpetic lesions
Coagulation and hemostasis
Exposure of implants
Scaling and root planing
94
Lasers in Endodontics
95
Laser in dentinal hypersentivity Rationale
for laser induced reduction in DH is based on 2 possible mechanisms
1st mechanism – implies direct effect of laser irradiation on the electric activity of nerve fibers within the dental pulp 2nd mechanism – modification of the tubular structure of dentin by melting and fusing of the hard tissue or smear layer and subsequent sealing of dentinal tubules
96
Lasers for treatment of DH are divided into 2 groups Low Output Power Lasers Output Power Lasers Helium – Neon Diode Nd:YAG Gallium-Aluminum-Arsenide diode
Middle
Co2
97
Pulp Diagnosis Laser
Doppler flowmetry (LDF) was developed to assess blood flow in microvascular systems, e.g. in the retina, gut mesentery, renal cortex and skin (Morikawa et al. 1971, Riva et al. 1972)
98
Helium – Neon and Diode laser at a low power of 1 or 2 mW of wavelength is 632.8 nm
Laser beam is directed towards the tooth (to the blood vessels)
Moving RBC causes the frequency of the laser beam to be Doppler shifted and some of the light be back scattered out of the tooth
The reflected light is detected by the photocell on the tooth surface and its output proportional to the number and velocity of the blood cells.
Advantages over EPT:
99
100
Pulp Capping & Pulpotomy
The energy level of 1 W at 0.1 second exposure time with 1 second pulse intervals was applied to the exposed pulp
Teeth were check for vitality after 6 and 12 months and 89.4% of the teeth retained their vitality
Lasers can be used for direct or in direct pulp capping in cases of deep and hypersensitive cavities
Co2 and Nd:YAG lasers are well absorbed by the hydroxyapatite of enamel and dentin, causing tissue ablation, melting and re-solidification
101
Cleaning & Shaping of Root Canal System
Various laser systems can deliver the energy into the root canal using a thin optical fiber
Various systems that have been used are
Nd:YAG Er,Cr:YSGG Argon Diode Er:YAG
It has been demonstrated in many studies that the laser radiation has the ability to remove debris and smear layer from the root canals It also has the potential to kill the microorganisms Bergman et al suggested that lasers is not an alternative to the conventional
102
Limitations for use in Root Canals
Emission of laser energy from the tip of optical fiber or the laser when directed into the root canal is not uniform
There may be thermal damage to the periapical tissues
May be hazardous when the tooth apex is near vital structures such as mandibular nerve or mental foramen
Sterilization of root canals by lasers is
103
104
Laser assisted Obturation
Aim of Obturation: Eliminate all avenues of leakage Seal the RC system from all ends
Rationale in using lasers for obturation is 1. Irradiation can be used as a heat source for softening the GP 2. Conditioning of the dentin walls can also be done
The clinical evidence from reported studies for the use of lasers in obturation is not sufficient.
It has not been determined if the use of laser as a heat source is safe for the surrounding structures of the tooth as well as for other teeth
A suitable wavelength has not been ascertained
Effect on the sealer per se has to be determined
105
LASERS IN Retreatment
Rationale for using lasers in retreatment is ascribed to the need to remove foreign material, GP etc by softening it by heat
Nd:YAP
(1340 nm) in used to remove GP and ZOE sealer Silver cones and separated instruments but lasers alone cannot remove all the obturating materials from the RC
A
clinical advantage is that toxic solvents like xylene can be avoided 106
Lasers in Endodontic Surgery
Laser is used for the surgery as 1. a bloodless surgical field 2. the ability of the laser to vaporize tissue 3. coagulate and seal small blood vessels. 4. Irradiation causes, surface sterilization
The potential of the Er:YAG laser to cut hard dental tissues without significant thermal or structural damage eliminates the need for mechanical drills
Clinical investigations into laser use for apicectomy began with the CO2 laser (Miserendino 1988), which was successful
When the laser was used for resection it is found that
107
Advantages
Cont…
1.Good hemostasis 2.Improved visualization of surgical site 3.Sterilization operative field 4.Reduced permeability of root surface dentin 5.Reduction in post operative pain 6.Reduced risk of contamination of surgical site by eliminating use of air turbines 7.Reports suggest that laser created wounds heal more quickly and produce less scar tissue than conventional scalpel surgery.
8.
Constraints 1.Time Consuming 2.Increase temperature 3.Cause irreversible pulpal damage 4.Needs precise execution
108
Other Endodontic uses CO2
and Nd:YAG lasers have been used for the attempted treatment of root fractures (Arakawa et al. 1996). However, after using various parameters, fusion of the fractured root halves was not achieved
Lasers
(Ar, CO2, Nd:YAG lasers) have been used successfully to sterilize dental instruments in shorter time.
A
pulsed dye laser emitted at 504 nm was used for the removal of a calcified attached denticle (Rocca et al. 1994)
109
Lasers in Operative & Aesthetic Dentistry Lasers
have become a part of routine operative and aesthetic practice
There
are five lasers that are currently in the armamentarium 1.Argon laser 2.Plasma arc laser 3.CO2 laser 4.Diode laser 5.Erbium family of lasers 110
Argon lasers The
wavelength is absorbed by Hb
This
attribute allows precision cutting, hemostasis & coagulation of vascular tissue
Use
of argon lasers have been used for curing composites (at low power achieving higher bond strength)
Transillumination
fractuures
in diagnosis of tooth 111
Plasma Arc Curing (PAC) PAC
& Argon laser curing systems are used in rapid polymerization of composites However they increase heat generation and thus causing polymerization shrinkage Bleaching
of stained teeth
112
Co2 Lasers Used
for vaporizing, cutting and coagulation of soft tissue
Used
more for soft tissue procedures which include gingival re-modelling and shaping in aesthetic dentistry (Perio-Aesthetics)
113
Diode Lasers 2
different WL are used Ga-Al-As Laser (800 nm) & In-Ga-As (980 nm) These are used in contact mode for cavity preparation, removal of bacterial contamination and coagulation of tissue Also used for Diagnosis 114
Erbium Family Er
lasers are absorbed by Hydroxyapatite and water
Allows
to cut soft tissue, tooth structure and bone
Er:YAG
(2940 nm) cuts teeth easily & quickly
Also
used for removal of caries
115
Operative dentistry
Detection of caries
Surface etching.
Removing decay painlessly and atraumatically without affecting the surrounding healthy tissues.
For removal of defective restoration as composite, GIC, Compomer restorations quickly and easily without the use of analgesia.
Bleaching of teeth (Power Bleaching).
Argon laser – alter surface characteristics-
decreased acid solubility
Nd:YAG laser- APF application after laser irradiation increased
Decay present on the facial of the maxillary left lateral incisor
The Erbium laser used to remove the decay . No anesthesia was required
After caries removal and preparation is complete
Definitive direct bonded restoration after preparation with the Erbium laser
Angle tip towards the buccal aspect Of the central groove, defocused, with VERY slow movement from mesial To distal create a initial groove.
Note penetration angled towards Buccal direction. Also note Conical concentration of laser Energy from end of tip.
Cut viewed from occlusal
Next, angle towards lingual, pass 3 times mesial to distal and open OTHER side of central groove
Again, note conical shape of cut Where laser energy is concentrated.
Finish prep by then going Straight down central groove, exposing Dentin , thereby opening up entire prep For ease of disease detection and Removal.
Etching
Laser etching has been evaluated as an alternative to acid etching of enamel and dentine.
The Er:YAG laser produces micro-explosions during hard tissue ablation that result in microscopic and macroscopic irregularities
However, it has been shown that adhesion to dental hard tissues after Er: YAG laser etching is inferior to that of conventional acid etching.
The weaker bond strength of the composite to laseretched enamel and dentine is due to the presence of subsurface fissuring which is absent126 in conventional etched surfaces
Caries prevention
Laboratory studies have indicated that enamel surfaces exposed to laser irradiation are more acid resistant than non-laser treated surfaces (Watanabe et al., 2001; Arimoto et al., 2001)
The degree of protection against caries progression provided by the one-time initial laser treatment was reported to be comparable to daily fluoride treatment by a fluoride dentifrice (Featherstone, 2000)
It is believed that laser irradiation of dental hard tissues modifies the calcium to phosphate ratio, reduces the carbonate to phosphorous ratio, and leads to the formation of more stable and less 127 acid soluble compounds, reducing susceptibility
Laser Assisted Bleaching
Two laser-assisted whitening systems have been cleared by the FDA
The laser enhances the activation of bleaching material, which then whitens the teeth
The argon laser wavelength of 488 nm for 30 seconds to accelerate the activity of the bleaching gel
After the laser energy is applied, the gel is left in place for three minutes, then removed. This procedure is repeated four to six times
CO2 laser is employed with another peroxide- based solution to promote penetration of the bleaching agent into the tooth. 128
Dental Laser Safety Safety
is an integral part of providing dental treatment with lasers
3
aspects to safety: Manufacturing process Proper operation of the device Personal protection
129
Regulatory Agencies American
National Standard Institute
(ANSI) Food
and Drug Administration (FDA)
Center
for devices and Radiological Health (CDRH)
Occupational
safety health administration (OSHA)
130
Laser Classification
(on bases of potential hazards)
Class
Laser Properties
I
Pose no health hazard e.g. CD Player, pointer
II
Emit only visible light with low power output & do not pose any health hazards Maximum allowable output is 1 mW
IIIa
Emit any WL and have an output power of 0.5 W of visible light; In this laser light can be viewed only momentarily Caution label is present Hazardous to unprotected eye; Output power no greater than 0.5 W; eg. Argon Laser curing light; Eye protection is must Hazardous from direct viewing and may produce diffuse reflections; Output power more than 0.5 W; Can produce fire and severe skin reactions; Can ignite
IIIb IV
The lasers used in dentistry fall in class IV category
The type of hazards can be grouped as :
1.Ocular hazards
2. 3.Tissue damage
4. 5.Reparatory depression
6. 7.Fire & explosion
8. 9.Electrical Shock
132
Fire & Explosion Hazards Use only wet and fire retardant materials in operative field Use non combustible anesthetics Avoid alcohol based topical anesthetics Avoid alcohol moistened gauze or cotton Fire Extinguisher Stay informed Follow ANSI regulations and local body regulations
133
Guidelines Mention
outside Door Switch Fire hazards
134
Laser safety control measures & recommendation
ENGINEERING CONTROLS
Protective housing
Interlocks
Beam enclosures
Shutters
Service panels
Equipment labels
ADMINISTRATIVE CONTROLS
Warning system
Key switch
Laser safety officer Standard operating procedures Out put limitations Training and education Maintenance and alignment Warning sign Protective devices Medical surveillance
Eye Protection In
1962, the awareness to eye protection began Eye is a critical target for laser injury Class
III & IV lasers pose a threat to the
eye Proper
eye wear is a must
136
Why the Eye ???
Cornea is made up of 90% Water
Absorbs emissions from all lasers
Can cause Corneal Burns
Retinal damage occurs due to lasers with more depth if penetration and is absorbed into the pigments
The eye is 100,000 times more vulnerable to injury than the skin
WL from 400-1400 is dangerous
Protective glasses must have an Optical Density of at least 4
137
Sterilization & Infection Control Fiber
optic cables & handpieces can be autoclaved in pouches
Oil
based aerosols should not be used
The
wires and protective casing / housing should be wiped clean and not autoclaved
138
Recent advancement Waterlase
MD (All-Tissue Laser)
1.Works on teeth, gums and bone 2.FDA cleared for most clinical procedures of any dental laser 3.Cuts over 50% faster 4.Recent root canal clearance 5.Works on Hydrophotonics principle 1.It’s the interaction between laser energy and water 2.Most procedures can be performed without anesthesia 3.Can coagulate while cutting 139 4.Reduced healing time and tissue trauma
Cutting with Waterlase Optimization of the cutting efficiency:
Air / Water balance
TOO little TOO wam •Water and Air settings in Spray should should be based on power settings and type of the tip
* charring * slo
Waterlase Hydrokinetic Cutting Mechanisms O Excitation of Water Molecules
H
H
Expansion
Laser + Water Spray
Photo-acoustic
Effective Tissue Cutting
WATERLASE (MD) TIPS Relative shapes of the tips, approximate beam divergence and radiation spot sizes (at 2-3 mm distance)
BIOLASE Engineering
Length and Shape
09/23/04
(M)G6, (M)G4
SAPPHIRE TIPS
750
(M)T4
(M)S75
400
750
750
(M)C6
1200
750
(M)C12
600
1200
(M)C3 (cone side)
1200
(M)C3 (flat side)
1200
300
1200
600
1200
QUARTZ TIPS
(M)Z2 240
(M)Z4 460
(M)Z3 380
(M)Z6
640
Laser technology in future
Caries detection and prevention
Tetra hertz pulse imaging
Endodontic canal lasing and curing
Computer Aided Design/Manufacturing (CAD/CAM)
Low Level Laser Therapy (LLLT)
Holographic imaging
No cut ,no sew and no pain
conclussion
But does not prove to be a holy grail
Many ethical issue questioning the risk benefit ratio
Mostly a tool of dentist with golden spoon in mouth
Patient pay capability is in question, as it is 10 times costly
Future is hopeful
As cost and the availability will be in reach of common man
As portability and versatility of the commercial products will increase144
145
146
References and literature review
147
1.www.goolge.com 2.www.yahoo.com 3.www.pubmed.com
2000 and
148
THANK YOU FOR YOUR PATIENCE LISTENING
149
THE HOLY GRAIL OF MODERN DENTAL PRACTICE.
LASERS IN DENTISTRY (A REVIEW) 1
CONTENTS INTRODUCTION SIGNIFICANCE IN MODERN DENTAL PRACTICE REVIEW OF HISTORY AND DEVELOPMENT FUNDAMENTAL OF LASER PHYSICS AND ITS COMPONENTS
a)Laser principles b)Laser properties c)Measurements of laser d)Laser generation e)Beam Profile and Spot Geometry f) Power Density(PD) 2
Cont…
LASER DELIVERY SYSTEM LASER EMISSION MODE LASERS AND TISSUE INTERACTION a)OPTICAL PROPERTIES OF TISSUE b)TISSUE EFFECT OF LASER IRRIDIATION
CLASSIFICATION OF LASERS TYPES OF LASERS SOFT AND HARD TISSUE APPLICATION OF LASERS IN DENTISTRY 1.Laser in endodontics 2.Laser in operative and esthetic dentistry
LASERS SAFTY IN DENTAL PRACTICE CONCLUSION REFRANCES
3
INTRODUCTION LASERS can be defined as 1. A device that utilizes the natural oscillations of atoms or molecules between energy levels for generating coherent electromagnetic radiation usually in the ultraviolet, visible, or infrared regions of the spectrum -Merriamwebster.com 1. A device which amplifies electromagnetic energy at various optical frequencies into an extremely intense small and nearly non divergent beam of bright light of a single color. Capable of mobilizing intense heat and power when focused at a close range, it is used as tool in surgical procedure , in diagnosis and in physiological studies. 4
cont. To d a y
La se rs a re e m p lo ye d fo r va rio u s p u rp o se s ra n g in g fro m Ømeasuring distances of the far planets, Øcreate laser guided warfare, Øentertainment, Øinstrumentation Øand even those that record the price of our groceries. And many more ……….
5
6
CONT… But
out of all odds the main and most advantageous purposes of is found in the field of HEALTH CARE INDUSTRIES.
7
SIGNIFICANCE IN MODERN DENTAL PRACTICE.
Today's dream and tomorrow's reality
lasers can be used to enhance the once clinical practice and the treatment out come also.
Dentist should become laser literate, consumer wise and that’s how increasing the potential of its use in day to day clinical practice with patient acceptance.
To understand the differences between variety of lasers and their vivid application.
Understanding lasers in an easy and understandable
8
Worldwide laser sales by application
9
REVIEW OF HISTORY AND DEVELOPMENT
Use of light for treatment of various pathologies is referred to as phototherapy.
Ancient Greece sun for heliotherapy, by exposure of the body to the sun for the restoration of health .
Late 1700s the Chinese used the sun to treat conditions such as rickets, skin cancer, and even psychosis.
In 1400 B.C. INDIANS used psoralens(a plant extract),to treat vitiligo.
10
cont… 1903,
a Danish physician Niels Finsen used carbon arc phototherapy for the treatment of lupus vulgaris by using UV rays.
11
Foundation of laser development
In 1917 Albert Einstein, in his “The Quantum Theory of Radiation”, laid the foundation for the invention of the laser and its predecessor, the maser,
In 1928, Rudolf W. Ladenburg confirmed the existence of stimulated emission and negative absorption.
In 1939, Valentin A. Fabrikant predicted the use of stimulated emission to amplify "short" waves.
In 1947, Willis E. Lamb and R. C. Retherford
12
Development of the lasers
The earliest use of photochemotherapy, or the use of an exogenous photosensitizerto absorb light and render a therapeutic effect
In 1974 it is evidenced that psoralens combination with exposure to ultraviolet radiation was indeed effective in the treatment of psoriasis and vitiligo.
Theodore H. Maiman of Hughes Aircraft Corporation in 16 May 1960 developed the first laser, or “ MASER“ an acronym for "Microwave Amplification by Stimulated Emission of Radiation,".
Snitzer in 1961 developed neodymium laser
Carbon dioxide laser -Kumar Patel in 1964 13
T h e o d o re H . M a im a n
Le o n G o ld m a n 14
Cont…
In 1965 Taylor et al studied histological effect of laser on the pulp
In 1968 Lobene et al used carbon dioxide laser in dentistry
Weichman & Johnson 1971 used laser for the first time in sealing of the apical foramen in vitro by means of a high power-infrared (CO2) laser
In 1974 Yamamoto et al used Nd:YAG laser for caries prevention
In 1977 Lenz et al used laser for the first time in maxillofacial surgery
15
R e f:- la se rs in d e n tistry b y
16
RECENT DEVELOPMENTS
1987 Meyer and mayer developed a Portable Laser
1990 FDI permitted the use of the same in the dentistry
The FDA approved oral soft tissue surgery in 1995 and sulcular debridement in 1998 by means of a diode laser
Hibst et al. 1999-2001 developed a novel laser 17 for caries detection (Diagnodent-KaVo,
FUNDAMENTAL LASER PHYSICS
The word LASER is an acronym for Light Amplification by Stimulated Emission of Radiation.
L A S E R
Light Amplification by Stimulated Emission of Radiation 18
UNDERSTANDING LIGHT
Form of electromagnetic energy that behave as a particle and a wave as well. light produced by a table lamp, for example, is usually a white diffused glow, although it is the sum of the many colors of the visible spectrum—violet, blue, green, yellow, orange, and red. A prism can be used to separate the individual colors in the same way that raindrops break up sunlight into the colors of a rainbow.
19
AMPLIFICATION
The initial light is amplified to make a very bright compact beam
20
STIMULATED
means that the photons are amplified by stimulating an atom to release more photons.
An atom can exist in an excited state, similar to a bow when it is stretched.
21
EMISSION
Refers to the giving of photons.
The excited atom emits a photon when another photon comes by.
Einstein(1917) Stimulated Emission.
22
RADIATION
For lasers, radiation refers to the PHOTONS which are being emitted.
23
Properties of LASER light
Monochromatic (single wavelength)
Collimation
( specific boundary)
Coherency
(in same phase)
Efficiency
(how good it works)
Directional (narrow cone of divergence)
24
monochromaticity Laser
light is one specific color, a property called monochromacity; in dental applications that color may be visible or invisible.
25
collimation
Collimation refers to the beam having specific spatial boundaries, which insures that there is a constant size and shape of the beam emitted from the laser cavity. A dental x-ray machine produces radiation with this property.
26
coherance
Coherency means that the light waves produced in the instrument are all the same. They are all in phase with one another and have identical wave shapes; that is, all the peaks and valleys are equivalent.
27
Efficiency and its measurement
The clinically useful feature of laser is efficiency.
Three measurements that can define the wave of photons in a laser.
The first is velocity, which is the speed of light.
The second is amplitude, which is the total height of the wave. It indication of the amount of intensity in the wave.
The third property is wavelength, which is the distance between any two corresponding points on the wave on the horizontal axis.which is important in determining 28 how the laser light is delivered to the surgical site and to
Electromagnetic Waves
Amplitude
Wavelength
Velocity
Frequency is the number of complete oscillations of the wave per second. 29
directionality
30
Laser generation
31
32
33
Components of Laser system
La sin g a ctive m e d iu m .
Energy or
Pumping source.
Optical chamber.
34
Lasing medium: A
material, capable of absorbing the energy produced by an external extension source through the subatomic configuration of its component molecules, atoms or ions. subsequently give off this excess energy as photons of light.
35
Energy or pumping source An
energy source is used to excite or pump the atoms in the lasing medium to their higher energy levels that are necessary for production of laser radiation.
36
Optical Chamber The
lasing medium is located within resonating chamber which has cylindrical structure with a fully reflecting mirror on one another.
37
Core cavity
The core cavity or the optical cavity is comprised of chemical elements, molecules, or compounds which is called the active medium, which can be container of gas, a crystal, or a solid state conductor. The other devices are either solid state semiconductor wafers made with multiple layers of metals such as gallium, aluminum, indium and arsenic.
High Voltage Power Supply
= atoms
cathode
100% Reflective Mirror
anode
Beam output
Active Medium 98% Reflective Mirror
38
39
Beam Profile and Spot Geometry
There are more photons concentrated in the core of the beam and that the light intensity diminishes at the edges. Often in a well-tuned cavity the transverse cross section (profile) is the normal gaussian curve. This is referred to as the TEMoo (transverse electromagnetic mode: 00), also called the "fundamental mode“) Other modes are possible such as the "Donut" mode (TEM10), which has a cold spot in the center.
40
Power Density(PD) Power
density is simply the concentration of photons in a unit area. Watts per area in square centimeters. Therefore, PD = W/cm2
(This is the average PD. Notice from the beam profile that the PD in the center of the spot is higher and that at the edge of the spot it approaches 0). 41
Cont…
The terms focused and defocused when working with lasers refers to the position of the focal point in relation to the tissue plane.
When
working on tissue, the laser should always be used either with the focal point positioned at the tissue surface (in focus) or positioned above the tissue surface (defocused or out of focus).
The
laser should never be positioned with the focal spot deep or within tissue
42
43
Laser delivery system
Contact lasers It works on the “hot tip” principal It improves cutting efficiency for low-power instruments Requires cleaning or cleaving the fiber to attain desired results
Non contact lasers Noncontact surgery relies completely on the pigments and water present in the tissue. Noncontact surgery requires significantly greater power settings than contact surgery. The techniques and principles are similar, only the feel is different. During noncontact surgery, the clinician operates with the aid of an aiming beam or by44
Laser delivery medium
Articulated arm- consist of a series of rigid hollow tubes with mirrors at each joint (called a knuckle) that reflect the energy down the length of the tube.
DISADVANTAGES 1. Bulky 2. Awkward three-dimensional maneuverability 3. Alignment of the mirrors 4. Articulated arm delivery systems are noncontact systems 1.
2. 45
Fiberoptic delivery system-The fiberoptic cables are attached to a small handpiece similar in size to a dental turbine. Advantages 1. Relatively flexible 2. Easy transmission of the laser energy throughout the oral cavity 3. Fiberoptic technology allows for contact with the target tissue Disadvantage 1. Costly 2. 3. 4.
46
Hollow waveguide delivery system – waveguide is a single long, semiflexible tube, without knuckles or mirrors. The laser energy is transmitted along the reflective inner lumen of this tube and exits through a handpiece at the end of the tube Advantages 1. Can be used as contact and non contact mode 1. Various attachments for hand piece Disadvantages 1. Available with co2 laser and erbium system only
47
Air-cooled fiberoptic delivery system – This type of delivery system is unique to the erbium family of lasers. A conventional fiberoptic delivery system cannot transmit the wavelength of the erbium family of lasers, owing to the specific characteristics of the erbium wavelength. These special air-cooled fibers terminate in a handpiece with quartz or sapphire tips. These tips are used slightly (1–2 mm) out of contact with the target tissue.
48
Laser Emission Modes
Emission of energy in 3 modalities
Continuous wave : Beam emitted at only one power level for as long as device is operated by pressing the foot switch
Gated pulse Mode: Periodic attenuations of laser energy being on & off similar to blinking light. The duration is as small as a few mille sec
Free running pulsed mode: large peak energies are emitted for an extremely short time span followed by long time of which laser is off. It is 49 computer controlled.
50
Several means are available for achieving pulsed output from a continuous wave laser. These are:
Mode locking
Q switching
Pulses from pico sec.
to micro sec Cavity dumping
Pump pulsing
from one microsecond to
a large fraction of sec 51
WHATS IN THE HAND OF OPERATOR?
52
Tissue effects of laser irradiation Broadly
the tissue effects of lasers can be groups as. 1.Photo 2. 3.Photo 4. 5.Photo 6. 7.Photo
chemical interaction thermal interactions mechanical interactions electrical interaction 53
Photo Chemical Interactions:
Specific wavelength absolved by naturally occurring chromophores
Wavelength specific light absorption substances are able to induce certain biochemical reactions at the cellular level.
Photo Chemical interactions are subdivided into
1.Photodynamic Therapy
2.
54
Photodynamic therapy Therapeutic use of lasers to induce reactions in tissues for treatment of pathologic conditions
Biostimulation The stimulatory effects of the laser light on biochemical & molecular processes that normally
55
Photo thermal Interactions:
Radiant energy absorbed by tissue -> transformed into heat energy which produces tissue effect.
The amount of light energy absorbed in tissue depends on:
1.Wavelength of radiant energy from laser.
2.Laser parameters such as spot size, power density, pulse duration & frequency.
3.Optical properties of tissue. 56
Laser heating and tissue temp
What Occurs when , if energy is absorbed 1.Hyperthermia- temp . Increase but not destroyed, tissue whitening or blanching 2.Coagulation –Irreversibly damages the tissue, by congealing tissue liquid into semisolid mass, good to archive homeostasis 3.Welding -Adherence of the layers because of stickiness due to the collagen molecule’s helical unfolding and intertwining with adjacent segments 4.Vaporization - tissue containing water is elevated to a temperature of 100 c, process also called as ablation 5.Carbonization - about 200 c, dehydrated 57
Thermal effects at different temp.
Temperature
Tissue Effects
37-50
Hyper thermia
60-70
Coagulation, protein denaturation
70-80
Tissue Welding
100-150
Vaporization and ablation
>200
Carbonization & charring (As in DCNA 2004 vol.48;759)
58
THE ZONE OF LASER INTERACTION WITH THE TISSUE
59
Photo Mechanical & Photo Electrical Effects
Photon disruption or photo disassociation which is breaking apart of structures by lasers
Photo acoustic effects which involve removal of tissue with shock wave generation
Photo plasmolysis describes how tissue is removed through the formation of electrically charged ions & particles that exist in a semi gaseous high energy state. 60
laser action manifests clinically as:
Photo ablation or removal of tissue by 1.Vaporization 2.Super heating of tissue fluids, 3.Coagulation, 4.Homeostasis 5.Photo pyrosis or burning away of
61
Optical properties of tissue
62
63
Absorption and laser interaction with hard tissue
Dental structures have different amount of water content, Enamel being the least followed by Dentin, Bone, Calculus, Caries and Soft tissue Dental lasers have a Photo thermal effect At low temperatures below 100°C, the thermal effects denature proteins and produce hemolysis and they cause coagulation & shrinkage Above 400°C, carbonization of organic materials occurs with onset of some inorganic materials 64 Between 400°C & 1200°C, inorganic
In general, shorter WL (500-1000 nm) are well absorbed in pigmented tissues and blood elements Longer WL are more interactive with water and Hydroxyapatite Co2 (10,600 nm) is well absorbed by water and has the highest affinity for Hydroxyapatite
Tissue Hemoglobin Melanin Hydroxyapatite WL
Feature Absorbed by Blue & Green WL Absorbed by short wavelengths Absorbed by a wide range of 65
66
Classifications of lasers
In general lasers can be classified into no. of ways.
But chiefly on the potential of the primary laser beam or the reflected beam to cause biologic damage to the eyes or skin.
The ANSI Standard Z136.1-2000 documents set the standards for classification in the United States.
OSHA and the American Conference of Governmental Industrial Hygienists also use this standard as a source. Other countries subscribe to these standards and have their own similar regulatory agencies.
67
Based on the potential danger posed to the exposed skin and eye Class
I - Low powered lasers that are safe to view Class IIa - Low powered visible lasers that are hazardous only when viewed directly for longer than 1000 sec. Class IIb - Low powered visible lasers that are hazardous when viewed for longer than 0.25 sec. Class IIIa-Medium powered lasers or systems that are normally not hazardous if viewed for less than 0.25 sec without magnifying optics. Class IIIb-Medium powered lasers (0.5w max) that can be hazardous if viewed directly. 68
Classification OF LASERS Based
on Active Medium 1.Solid State 2.Gas 3.Semiconductors 4.Excimer 5.Dye
Mode
of action 1.Contact mode (focused or defocused) Ho:YAG ; Nd: YAG 2.Non-contact mode (focused or defocused) CO2 3. 69 4.
CONT… Based
as application 1.Soft tissue laser - Argon, Co2, diode; Nd:YAG. 2.Hard tissue laser - Er : YAG 3.Resin curing laser - Argon
Based
on Level of energy emission: 1.Soft lasers (Low level energy): He-Neon; Ga-Arsenide. 2.Hard lasers (High level energy): Er:YAG laser ; Nd: YAG laser.
70
71
72
Diode 812nm Diode (980nm) ErCr:YSGG 2.78 µm Ex c i m e r KTP (532nm) Er:YAG ( 2.94µm) KrF (248nm) XeF(351 nm) CO2 (9.6 or 10.6µm) HeNe (632nm)
Ultraviolet
Visible
Infrared
100 nm 400 nm ArF (193nm) XeCl (308 nm)
Ruby (694nm) 750 nm Ho: YAG 10,000 nm Argon (514 nm) Nd: YAG (2,08 µm) (1,06 µm) Argon (488 nm)
γ -rays 10-12
x-rays
UV 10 - 9
visible IR microwaves 10 - 6
1 0 -3
radio waves 1
acoustic waves
103 wavelength, meters 73
74
75
Laser Wavelengths Used in Dentistry Argon laser
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 The only available surgical laser device whose light is radiated in the visible spectrum. There are 2 emission wavelength used in dentistry: 488 nm, which is blue in color & 514 nm which blue green. 488 nm emission activate camphoroquinone(photo initiator), causing polymerization. The 514 nm wave length has its peak absorption in tissues containing hemoglobin, hemosiderin & melanin.Thus it has excellent haemostatic capabilities. 76
usages
Used in Surgical Endodontics
Both can be used for caries detection
Argon laser light illuminates the tooth, the disease area appears dark orange-red colored
Neither wavelength is absorbed by dental tissues or water
Their poor absorption by enamel and dentin is an advantage when used for incising and sculpting gingival tissues
77
Diode laser
A solid active medium laser, manufactured from (Gallium arsenide) semi conductor crystals using combination of aluminum or indium, gallium, and arsenic.
Wavelengths for dental use range are 800 nm for active medium containing aluminum to 980 nm for active medium containing indium.
Optic fiber delivery system with contact mode.
All of diode wavelength are highly absorbed by
pigmented tissue and are deeply penetrating 78
Neodymium :YAG 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.
Operates at wavelength of 1064nm in a high inter pulsed wave form.
It emits light in near invisible infrared area of spectrum.
Fiber optic cable to divert the light to a hand piece & lens to produce free beam of laser light 79
Common clinical applications are: For cutting & coagulating of dental soft tissues & debridement.
Offers good hemostasis during soft tissue procedures
For attaining pulpal analgesia
Advantages: Facilitates a clear operating field
Flexible delivery system.
Disadvantage: Is unnecessary collateral damage due to its depth of penetration.
Wound healing in soft tissue will be delayed
80
Holmium:YAG
solid crystal of yttrium aluminum garnet sensitized with chromium and doped with holmium and thulium ions Fiber optically delivered and free running pulsed mode Operates at a wavelength of 2100 nm and uses a pulsed waveform.
It is absorbed by water 100 times greater than Nd: YAG
At high peak powers, can abrade hard, calcified tissue.
An aiming device is used, as the light produced is invisible.
81
Erbium Family lasers
Erbium: YSGG (2780nm) with solid crystal of yttrium scandium gallium garnet doped with erbium & chromium
Erbium : YAG (2940nm) has crystal of yttrium aluminum garnet doped with erbium .
The delivery systems are a hollow wave guide and fiber optics in free running pulse mode.
The highest absorption in water & have a high affinity for hydroxyapatite.
82
Uses:
Caries removal and Cavity preparation
In preparation of root canals.
Facial resurfacing,
83
Carbon dioxide laser
It was developed by Patel in 1964.
A gas active medium laser that incorporates a sealed tube containing a gaseous mixture with Co2 molecules pumped via electrical discharge current.
Operates at wavelength of 10,600nm.
It is operated in a gated wave form or continuous form through a hallow tube like wave guide.
Wavelength is well absorbed by water.
It can easily cut & coagulate soft tissue & has a shallow depth of penetration into tissue.
Emits light in the invisible mid infrared portion.
84
Uses: Excision and ablation of various types of superficial lesions & for skin resurfacing
Excellent Hemostasis,
Advantages: Clear field of view.
Post operative pain is minimal
Disadvantages: Wound healing is delayed Difficult to uses (articulated arm)
85
newer lasers systems KTP Lasers (excimers)
Modified version of Nd: YAG laser:
Addition of frequently doubling crystal operates at 532nm.
It uses fiber optic cable with a hand piece.
It is similar to argon laser in absorption characteristics
Used in the treatment of vascular & pigmented lesions, tattoo removal 86
Flash Lamp pumped pulsed Dye Laser
Produces yellow visible light in 400–1000nm range & is commonly used at 510, 577, 585nm.
The desired wavelength can be used for specific tissue to be removed, offering great flexibility
510 nm melanin can be targeted & various benign melanin containing tissues can be ablated
585nm targets oxy-hemoglobin with in vascular abnormities.
Thus it is used in treatment of cancer, ablation of salivary 87
Copper Vapor Laser
Wavelengths of 511-578 nm.
Similar
to both KTP & Argon lasers.
Its
medium is heated copper which produces copper gas.
Delivered
mode
by fiber optic cable in pulsed
Effective
in treatment of port wine stains or large superficial telangiectasias, nevi &
88
Medical Applications of laser
Argon laser in ophthalmology 1968
Otorhinolaryngology
Dermatology & plastic surgery
Neurosurgery
Urology
Gastroinstestinal surgery 89
Why to select laser for treatment? Patients
choice Clinicians choice Treatment outcome assessment Utilizing benefits of lasers
Patient
comfort & acceptance Reduced
postoperative complications Hemorrhage control Reduced need for postoperative analgesics Advantage
over the cold steel surgical procedure 1.Dry and bloodless surgery 2.Instant sterilization of the surgical site 3.Reduced bacteremia 4.Reduced mechanical trauma 5.Minimal postoperative swelling and scarring
90
Types of Lasers
Hard lasers or high level lasers. Cavity Preparation on tooth surface Transillumination Photo polymerization Cortical bone ablation
91
Soft
tissue laser or low power
Temperature 37-50 60-70 70-80 100-150 >200
Tissue Effects Hyper thermia Desiccation protein denaturation Tissue Welding Vaporization and ablation Carbonization & charring (As in DCNA 2004 vol.48;759) 92
Hard and soft tissue difference Hard
Lasers: Have
longer wavelength more then 450nm Produces thermal effect, which cut the tissue by coagulation, vaporization & carbonization. These lasers are used for surgical hard tissue applications.
Soft
or low-level lasers Low
thermal energy wavelengths of less than about 450nm with minor temperature increase of less than 1C. Stimulate circulation and cellular activity. Anti-inflammatory, Muscle relaxation, Analgesia 93
Laser application in vivacity of dentistry
Biopsies
Tongue lesions
Aphthous ulcers
Herpetic lesions
Coagulation and hemostasis
Exposure of implants
Scaling and root planing
94
Lasers in Endodontics
95
Laser in dentinal hypersentivity Rationale
for laser induced reduction in DH is based on 2 possible mechanisms
1st mechanism – implies direct effect of laser irradiation on the electric activity of nerve fibers within the dental pulp 2nd mechanism – modification of the tubular structure of dentin by melting and fusing of the hard tissue or smear layer and subsequent sealing of dentinal tubules
96
Lasers for treatment of DH are divided into 2 groups Low Output Power Lasers Output Power Lasers Helium – Neon Diode Nd:YAG Gallium-Aluminum-Arsenide diode
Middle
Co2
97
Pulp Diagnosis Laser
Doppler flowmetry (LDF) was developed to assess blood flow in microvascular systems, e.g. in the retina, gut mesentery, renal cortex and skin (Morikawa et al. 1971, Riva et al. 1972)
98
Helium – Neon and Diode laser at a low power of 1 or 2 mW of wavelength is 632.8 nm
Laser beam is directed towards the tooth (to the blood vessels)
Moving RBC causes the frequency of the laser beam to be Doppler shifted and some of the light be back scattered out of the tooth
The reflected light is detected by the photocell on the tooth surface and its output proportional to the number and velocity of the blood cells.
Advantages over EPT:
99
100
Pulp Capping & Pulpotomy
The energy level of 1 W at 0.1 second exposure time with 1 second pulse intervals was applied to the exposed pulp
Teeth were check for vitality after 6 and 12 months and 89.4% of the teeth retained their vitality
Lasers can be used for direct or in direct pulp capping in cases of deep and hypersensitive cavities
Co2 and Nd:YAG lasers are well absorbed by the hydroxyapatite of enamel and dentin, causing tissue ablation, melting and re-solidification
101
Cleaning & Shaping of Root Canal System
Various laser systems can deliver the energy into the root canal using a thin optical fiber
Various systems that have been used are
Nd:YAG Er,Cr:YSGG Argon Diode Er:YAG
It has been demonstrated in many studies that the laser radiation has the ability to remove debris and smear layer from the root canals It also has the potential to kill the microorganisms Bergman et al suggested that lasers is not an alternative to the conventional
102
Limitations for use in Root Canals
Emission of laser energy from the tip of optical fiber or the laser when directed into the root canal is not uniform
There may be thermal damage to the periapical tissues
May be hazardous when the tooth apex is near vital structures such as mandibular nerve or mental foramen
Sterilization of root canals by lasers is
103
104
Laser assisted Obturation
Aim of Obturation: Eliminate all avenues of leakage Seal the RC system from all ends
Rationale in using lasers for obturation is 1. Irradiation can be used as a heat source for softening the GP 2. Conditioning of the dentin walls can also be done
The clinical evidence from reported studies for the use of lasers in obturation is not sufficient.
It has not been determined if the use of laser as a heat source is safe for the surrounding structures of the tooth as well as for other teeth
A suitable wavelength has not been ascertained
Effect on the sealer per se has to be determined
105
LASERS IN Retreatment
Rationale for using lasers in retreatment is ascribed to the need to remove foreign material, GP etc by softening it by heat
Nd:YAP
(1340 nm) in used to remove GP and ZOE sealer Silver cones and separated instruments but lasers alone cannot remove all the obturating materials from the RC
A
clinical advantage is that toxic solvents like xylene can be avoided 106
Lasers in Endodontic Surgery
Laser is used for the surgery as 1. a bloodless surgical field 2. the ability of the laser to vaporize tissue 3. coagulate and seal small blood vessels. 4. Irradiation causes, surface sterilization
The potential of the Er:YAG laser to cut hard dental tissues without significant thermal or structural damage eliminates the need for mechanical drills
Clinical investigations into laser use for apicectomy began with the CO2 laser (Miserendino 1988), which was successful
When the laser was used for resection it is found that
107
Advantages
Cont…
1.Good hemostasis 2.Improved visualization of surgical site 3.Sterilization operative field 4.Reduced permeability of root surface dentin 5.Reduction in post operative pain 6.Reduced risk of contamination of surgical site by eliminating use of air turbines 7.Reports suggest that laser created wounds heal more quickly and produce less scar tissue than conventional scalpel surgery.
8.
Constraints 1.Time Consuming 2.Increase temperature 3.Cause irreversible pulpal damage 4.Needs precise execution
108
Other Endodontic uses CO2
and Nd:YAG lasers have been used for the attempted treatment of root fractures (Arakawa et al. 1996). However, after using various parameters, fusion of the fractured root halves was not achieved
Lasers
(Ar, CO2, Nd:YAG lasers) have been used successfully to sterilize dental instruments in shorter time.
A
pulsed dye laser emitted at 504 nm was used for the removal of a calcified attached denticle (Rocca et al. 1994)
109
Lasers in Operative & Aesthetic Dentistry Lasers
have become a part of routine operative and aesthetic practice
There
are five lasers that are currently in the armamentarium 1.Argon laser 2.Plasma arc laser 3.CO2 laser 4.Diode laser 5.Erbium family of lasers 110
Argon lasers The
wavelength is absorbed by Hb
This
attribute allows precision cutting, hemostasis & coagulation of vascular tissue
Use
of argon lasers have been used for curing composites (at low power achieving higher bond strength)
Transillumination
fractuures
in diagnosis of tooth 111
Plasma Arc Curing (PAC) PAC
& Argon laser curing systems are used in rapid polymerization of composites However they increase heat generation and thus causing polymerization shrinkage Bleaching
of stained teeth
112
Co2 Lasers Used
for vaporizing, cutting and coagulation of soft tissue
Used
more for soft tissue procedures which include gingival re-modelling and shaping in aesthetic dentistry (Perio-Aesthetics)
113
Diode Lasers 2
different WL are used Ga-Al-As Laser (800 nm) & In-Ga-As (980 nm) These are used in contact mode for cavity preparation, removal of bacterial contamination and coagulation of tissue Also used for Diagnosis 114
Erbium Family Er
lasers are absorbed by Hydroxyapatite and water
Allows
to cut soft tissue, tooth structure and bone
Er:YAG
(2940 nm) cuts teeth easily & quickly
Also
used for removal of caries
115
Operative dentistry
Detection of caries
Surface etching.
Removing decay painlessly and atraumatically without affecting the surrounding healthy tissues.
For removal of defective restoration as composite, GIC, Compomer restorations quickly and easily without the use of analgesia.
Bleaching of teeth (Power Bleaching).
Argon laser – alter surface characteristics-
decreased acid solubility
Nd:YAG laser- APF application after laser irradiation increased
Decay present on the facial of the maxillary left lateral incisor
The Erbium laser used to remove the decay . No anesthesia was required
After caries removal and preparation is complete
Definitive direct bonded restoration after preparation with the Erbium laser
Angle tip towards the buccal aspect Of the central groove, defocused, with VERY slow movement from mesial To distal create a initial groove.
Note penetration angled towards Buccal direction. Also note Conical concentration of laser Energy from end of tip.
Cut viewed from occlusal
Next, angle towards lingual, pass 3 times mesial to distal and open OTHER side of central groove
Again, note conical shape of cut Where laser energy is concentrated.
Finish prep by then going Straight down central groove, exposing Dentin , thereby opening up entire prep For ease of disease detection and Removal.
Etching
Laser etching has been evaluated as an alternative to acid etching of enamel and dentine.
The Er:YAG laser produces micro-explosions during hard tissue ablation that result in microscopic and macroscopic irregularities
However, it has been shown that adhesion to dental hard tissues after Er: YAG laser etching is inferior to that of conventional acid etching.
The weaker bond strength of the composite to laseretched enamel and dentine is due to the presence of subsurface fissuring which is absent126 in conventional etched surfaces
Caries prevention
Laboratory studies have indicated that enamel surfaces exposed to laser irradiation are more acid resistant than non-laser treated surfaces (Watanabe et al., 2001; Arimoto et al., 2001)
The degree of protection against caries progression provided by the one-time initial laser treatment was reported to be comparable to daily fluoride treatment by a fluoride dentifrice (Featherstone, 2000)
It is believed that laser irradiation of dental hard tissues modifies the calcium to phosphate ratio, reduces the carbonate to phosphorous ratio, and leads to the formation of more stable and less 127 acid soluble compounds, reducing susceptibility
Laser Assisted Bleaching
Two laser-assisted whitening systems have been cleared by the FDA
The laser enhances the activation of bleaching material, which then whitens the teeth
The argon laser wavelength of 488 nm for 30 seconds to accelerate the activity of the bleaching gel
After the laser energy is applied, the gel is left in place for three minutes, then removed. This procedure is repeated four to six times
CO2 laser is employed with another peroxide- based solution to promote penetration of the bleaching agent into the tooth. 128
Dental Laser Safety Safety
is an integral part of providing dental treatment with lasers
3
aspects to safety: Manufacturing process Proper operation of the device Personal protection
129
Regulatory Agencies American
National Standard Institute
(ANSI) Food
and Drug Administration (FDA)
Center
for devices and Radiological Health (CDRH)
Occupational
safety health administration (OSHA)
130
Laser Classification
(on bases of potential hazards)
Class
Laser Properties
I
Pose no health hazard e.g. CD Player, pointer
II
Emit only visible light with low power output & do not pose any health hazards Maximum allowable output is 1 mW
IIIa
Emit any WL and have an output power of 0.5 W of visible light; In this laser light can be viewed only momentarily Caution label is present Hazardous to unprotected eye; Output power no greater than 0.5 W; eg. Argon Laser curing light; Eye protection is must Hazardous from direct viewing and may produce diffuse reflections; Output power more than 0.5 W; Can produce fire and severe skin reactions; Can ignite
IIIb IV
The lasers used in dentistry fall in class IV category
The type of hazards can be grouped as :
1.Ocular hazards
2. 3.Tissue damage
4. 5.Reparatory depression
6. 7.Fire & explosion
8. 9.Electrical Shock
132
Fire & Explosion Hazards Use only wet and fire retardant materials in operative field Use non combustible anesthetics Avoid alcohol based topical anesthetics Avoid alcohol moistened gauze or cotton Fire Extinguisher Stay informed Follow ANSI regulations and local body regulations
133
Guidelines Mention
outside Door Switch Fire hazards
134
Laser safety control measures & recommendation
ENGINEERING CONTROLS
Protective housing
Interlocks
Beam enclosures
Shutters
Service panels
Equipment labels
ADMINISTRATIVE CONTROLS
Warning system
Key switch
Laser safety officer Standard operating procedures Out put limitations Training and education Maintenance and alignment Warning sign Protective devices Medical surveillance
Eye Protection In
1962, the awareness to eye protection began Eye is a critical target for laser injury Class
III & IV lasers pose a threat to the
eye Proper
eye wear is a must
136
Why the Eye ???
Cornea is made up of 90% Water
Absorbs emissions from all lasers
Can cause Corneal Burns
Retinal damage occurs due to lasers with more depth if penetration and is absorbed into the pigments
The eye is 100,000 times more vulnerable to injury than the skin
WL from 400-1400 is dangerous
Protective glasses must have an Optical Density of at least 4
137
Sterilization & Infection Control Fiber
optic cables & handpieces can be autoclaved in pouches
Oil
based aerosols should not be used
The
wires and protective casing / housing should be wiped clean and not autoclaved
138
Recent advancement Waterlase
MD (All-Tissue Laser)
1.Works on teeth, gums and bone 2.FDA cleared for most clinical procedures of any dental laser 3.Cuts over 50% faster 4.Recent root canal clearance 5.Works on Hydrophotonics principle 1.It’s the interaction between laser energy and water 2.Most procedures can be performed without anesthesia 3.Can coagulate while cutting 139 4.Reduced healing time and tissue trauma
Cutting with Waterlase Optimization of the cutting efficiency:
Air / Water balance
TOO little TOO wam •Water and Air settings in Spray should should be based on power settings and type of the tip
* charring * slo
Waterlase Hydrokinetic Cutting Mechanisms O Excitation of Water Molecules
H
H
Expansion
Laser + Water Spray
Photo-acoustic
Effective Tissue Cutting
WATERLASE (MD) TIPS Relative shapes of the tips, approximate beam divergence and radiation spot sizes (at 2-3 mm distance)
BIOLASE Engineering
Length and Shape
09/23/04
(M)G6, (M)G4
SAPPHIRE TIPS
750
(M)T4
(M)S75
400
750
750
(M)C6
1200
750
(M)C12
600
1200
(M)C3 (cone side)
1200
(M)C3 (flat side)
1200
300
1200
600
1200
QUARTZ TIPS
(M)Z2 240
(M)Z4 460
(M)Z3 380
(M)Z6
640
Laser technology in future
Caries detection and prevention
Tetra hertz pulse imaging
Endodontic canal lasing and curing
Computer Aided Design/Manufacturing (CAD/CAM)
Low Level Laser Therapy (LLLT)
Holographic imaging
No cut ,no sew and no pain
conclussion
But does not prove to be a holy grail
Many ethical issue questioning the risk benefit ratio
Mostly a tool of dentist with golden spoon in mouth
Patient pay capability is in question, as it is 10 times costly
Future is hopeful
As cost and the availability will be in reach of common man
As portability and versatility of the commercial products will increase144
145
146
References and literature review
147
1.www.goolge.com 2.www.yahoo.com 3.www.pubmed.com
2000 and
148
THANK YOU FOR YOUR PATIENCE LISTENING
149
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