ppt on lasers in conservative dentistry

1. LASERS IN
CONSERVATIVE
DENTISTRY
DR DEETI PRIYA RANA ,
MDS (SENIOR LECTURER),
DEPARTMENT OF CONSERVATIVE
DENTISTRY & ENDODONTICS.

2. •INTRODUCTION
•HISTORY
•CLASSIFICATION OF LASERS
•LASER PHYSICS
•PROPERTIES OF LASER
•LASER DESIGN
•LASER DELIVERY SYSTEMS AND EMISSION MODES
•LASER- TISSUE INTERACTION
•TYPES OF LASERS

3. •APPLICATIONS IN CONSERVATIVE DENTISTRY
•ADVANTAGES AND DISADVANTAGES
•LASER HAZARDS
•LASER HAZARDS CONTROL MEASURES
•CONCLUSION
•REFERENCES

4. LASER

5.  LASER is acronym for ‘Light Amplification
by Stimulated Emission of Radiation.’
 Laser light is different from normal regular light.
 It has a single wavelength and it can be focused in a
very narrow beam.
 Wavelength of laser determines the effective depth of
penetration.
 Effects of laser are dependent on the type of laser used
and on the type of tissue it is used.
 There is rapid development in the field of laser
technology, modern lasers with a wide range of
characteristics are now available and being used in the
field of dentistry, most importantly in the field of
conservative dentistry.

6.  In 1917- Albert Einstein: Theory of
spontaneous emission of radiation.
 In 1954- Charles Townes invented 'MASER'
which is 'Microwave Amplification by
stimulated Emission of Radiation‘.
 In May 1960- Theodore Maimen :
first laser-> Ruby laser at Hughes Aircraft
company.

7.  In 1964- Stern and Goldman: Lasers in
dentistry.
 In 1964- Geusic developed first Nd:YAG
laser.
 In 1964- Patel developed first CO2 laser.
 In 1971- Weichman and Johnson : Lasers
in Endodontics.

9.  According to ANSI and OHSA standards,
lasers are classified as:-
 CLASS I : low powered laser that are safe to use.
 CLASS II a : low powered visible laser, hazardous
only when viewed for > 1000 sec
 CLASS II b : Low powered lasers , hazardous >
0.25 sec
 CLASS III a: medium powered, hazardous if
viewed for <0.25 sec without magnifying optics
 CLASS III b: medium powered lasers ( 0.5 W) that
can be hazardous if viewed directly
 CLASS IV: high powered lasers ( >0.5 W) that can
produce occular skin and fire hazards

10.  Based on penetration power of beam:
 A) Soft tissue lasers
 Soft tissue lasers generally utilize diodes.
 USES: healing of aphthous ulcers, treatment of
gingivitis.
 Eg- Helium-Neon (He-N), Gallium-Arsenide(Ga-As)
lasers.
 B) Hard tissue lasers
 Hard tissue lasers (surgical) can cut both soft and
hard tissues.
 Eg- Argon lasers (Ar), Carbon dioxide lasers (CO2),
Neodymium-doped Yttrium Aluminium Garnet
lasers (Nd:YAG) .

11.  Based on the wavelength of the beam:
 1) UV Light-100 nm to 400 nm
 2) Visible Light- 400 nm to 750 nm
 3) Infrared light- 750 nm to 10000 nm

12.  According to type of laser material used :
 A. Gas lasers:
Argon
Carbon-dioxide
 B. Liquid:
Dye laser
 C. Solid:
Nd:YAG
Erbium: Yttrium Aluminum Garnet (Er: YAG)
Diode
 D. Semiconductor:
Gallium-Arsenide laser
 E. Excimers:
Argon-fluoride

13.  Based on pulsing:
 Pulsed mode
 Continuous/Nonpulsed mode
 Gated mode
CONTINUOUS WAVE
MODE
GATED MODE
PULSED MODE

14.  Laser is a form of electromagnetic energy that
travels at a constant velocity in form of waves.
 The basic unit of light is called a photon or a particle
of light.
 Laser is a device that converts electrical or chemical
energy into light energy.

16. The interaction of light (a photon) with an atom.
Three processes are shown;
A) the absorption of a photon by an atom in a low-energy state,
B) the spontaneous emission of a photon from an atom in an excited
state and
C) the stimulated emission of a photon by a second photon of the
same wavelength from an excited state atom.
B
A
A
A
C
A

17.  When an atom is struck by a photon, there is an energy
transfer causing increase in energy of the atom.
 This process is termed as ABSORPTION.
 The photon then ceases to exist, and an electron within the
atom pumps to a higher energy level. This atom is thus
pumped up to an excited state from the ground state.
 In the excited state, the atom is unstable and will soon
spontaneously decay back to the ground state, releasing the
stored energy in the form of an emitted photon. This process
is called SPONTANEOUS EMISSION.
 STIMULATED EMISSION can occur only when the
incident photon has exactly the same energy as the released
photon.
 When the number of atoms in an excited state are more than
the number of atoms in ground state, then population
inversion occurs which is a necessary condition for
LASING.

18.  Monochromatic: Means single wave length.
The laser has one specific colour.
 Collimated: having specific spatial boundaries and a very
low divergence, ensuring constant size and shape of the beam
 Coherency: light waves produced by a laser have specific
form of electromagnetic energy which is in phase with one
another.
 Intense: light beam produced is intense in nature.

20.  The laser consists of following components:
 LASER MEDIUM OR ACTIVE MEDIUM:
 This can be a solid, liquid or gas.
 Determines the wavelength of emitted light from the laser.
 HOUSING TUBE OR OPTICAL CAVITY:
 Made up of metal, ceramic or both.
 This structure encapsulates the laser medium.
 MIRRORS:
 It consists of two mirrors, one fully reflective and the other partially
transmittive, that are located at either end of the optical cavity and
allows reflection of photons of light in back and forth direction across
the chamber.
 EXTERNAL POWER SOURCE:
 This external power source excites or “pumps” the atom in the laser
medium to their higher energy levels.

22. Fig. 2:
The optical resonating chamber of a CO2 laser.
The gas molecules are excited by an electric current.
The gas is cooled by a water jacket.
The two mirrors provide the optical feedback for the amplification.
The emitted light is coherent, monochromatic, and collimated.
The light can be focused to a small point with an external lens.

23.  Two Delivery Systems:
1. FLEXIBLE HOLLOW TUBE
It is a hollow wave guide tube or a tube which
have a mirror finish.
Used in noncontact mode.
2.GLASS FIBER OPTIC CABLE
It is a glass tube encased in resilient sheath.
It is fragile and non flexible.
It can be used in both contact and noncontact
mode.

24. Continuous mode
Gated mode
Pulsed mode
Focussed mode/Cut mode-- laser beam hits the tissue at its focal
points or smallest diameter.
Defocussed mode/Ablation mode--By defocusing the laser beam or
moving the focal spot away from the tissue plane, beam size
hits the tissue has a greater diameter and causes wider area of
tissue to be vaporized.
Contact mode- fiber tip is placed in contact with the tissue.
Non-contact mode- Fiber tip is placed away from the target tissue.

27.  Photochemical effects
 Photomechanical effects
 Photothermal effects.
 Photoelectrical effects

28. A) Photo chemical
Biostimulation---stimulatory effects of laser light on
biochemical and molecular processes that normally occur in
tissues.
B) Photo mechanical
Photo disruption--breaking apart of structures by laser light.
Photo acoustic- Removal of tissue with shock wave generation.
C) Photo thermal
Photo ablation---removal of tissue by vaporization
Photo pyrolysis--burning away of the tissue.
D) Photo electrical
Photoplasmolysis—tissues are removed through the formation
of electrically charged ions.

31.  Active medium –
solid crystal of aluminum, yttrium-garnet doped
with Neodymium,
Delivery system- fiber optic free running pulse
mode, contact mode mostly
wavelengths- 1064 nm.
USES- treatment of dentinal hypersensitivity, root
canal sterilization, pulp capping and soft tissue
procedures.

32. Active medium– aluminum, gallium and arsenide(solid).
Continuous and pulsed mode
Mostly in contact mode
Delivery system- fiber optic
wavelength- 800-980nm.
USES:- Soft tissue laser used in precise cutting and
coagulation of gingiva.

33. ARGON LASER
Active medium. – argon gas
Delivery system- fiber optic
Continuous and pulsed mode
Wavelengths- 488nm: blue in colour
514nm: blue green(Visible light).
USES:- Curing of composites and bleaching.
514 nm - haemostasis

34.  Active medium :–
Er,Cr:YSGG: Solid crystal of yttrium-Scandium-
garnet doped with erbium and chromium
Er YAG: Solid crystal of yttrium, aluminum and
garnet doped with erbium.
Delivery system- fiber optic free running pulse
mode.
Wavelengths- Er,Cr:YSGG –2790nm
Er YAG- 2940nm
USES- Ideal for caries removal and tooth
preparation.
Hard tissue cutting and drilling.

35.  C02 LASER.
Active medium – C02 gas
Delivery system- hollow tube
Wavelengths- 10,600nm.
Highly absorbed by both hard and soft tissues but has
shallow depth of penetration.
Not suitable for hard tissues- deleterious thermal absorptive
effect on pulp
USES:- Ideal laser for soft tissues especially in cutting
dense fibrous tissues.

37.  A) LASER AUTO FLUORESCENCE (LAF)
 Uses visible light for detection of smooth surface and
fissure caries at an early stage.
 Argon laser emitting blue green light detects carious
lesions and its extent of demineralisation.
 B) QUANTITATIVE LASER FLUORESCENCE
(QLF)
 Detects incipient carious lesions.
 Uses Argon laser emitting blue light which indentifies
caries with reduced flourescence over the sound tooth.

38.  C) DIAGNODENT (Laser induced fluorescence)
 DIAGNODENT is a recently designed instrument to facilitate
the detection of dental caries and calculus by emitting a
nonionising laser beam at a wavelength of 655nm.
 Used for detection of caries on occlusal & smooth surface.
Source of light is
Diode laser.
This red laser light
indentifies caries
with increased
flourescence over
sound tooth.

39.  2) CAVITY PREPARATION:
 The "Laser Drill" has been successful in replacing the
conventional bur for cavity preparation.
1) Lasers cut at a point of their tip
2) Lasers should be used in up and down motion
3) Lasers also help in the removal of smear layer
 Erbium lasers are used for tooth preparation.
 There should be at least 1mm of clearance between the
end of the laser tip and the surface of tooth structure.

41.  3) RESTORATION REMOVAL:
 The Er: YAG laser is capable of removing cement,
composite resin and the glass ionomer.
 Lasers should not be used to ablate amalgam restorations
due to potential release of mercury vapour.
 The Er: YAG laser is incapable of removing gold crowns,
cast restorations and ceramic materials because of low
absorption of these materials and the reflection of the
laser light.

42.  4) ETCHING:
 As an alternative to the acid etching of enamel and dentine.
 The Er: YAG laser produces micro-explosions during hard
tissue ablation that result in microscopic and macroscopic
irregularities.
 These micro-irregularities make the enamel surface
microretentive and offers a mechanism of adhesion without
acid-etching.

43.  5) PHOTOPOLYMERISATION OF
COMPOSITE RESIN
 Argon laser at 488nm (blue) is used.
 Argon laser activates camphorquinone (photoinitiator) that
causes polymerisation of the resin composites.
 MECHANISM- Ability to alter the surface chemistry of both
enamel and dentin which reduces the probability of the
recurrent caries.

44.  6) PREVENTION OF DENTAL CARIES:
 Argon laser can be used for prevention of dental caries.
 MECHANISM- Increases the resistance to dental
caries by reducing the rate of demineralization of
substance of enamel & dentin.

46.  7) DENTINAL HYPERSENSITIVITY:
 First mechanism--- Direct effect of laser irradiation on the
electric activity of nerve fibers within the dental pulp.
 Second mechanism--- Modification of tubular structure of
dentin by melting and fusing of the hard tissue or smear layer
and subsequent sealing of the dentinal tubules .
 Low output power lasers (helium-neon and gallium/ diode)
and middle output power lasers (Nd:YAG and CO2).

47.  8) TREATMENT OF TOOTH EROSION:
 CO2 lasers have been mostly used due to its
efficient interaction with hydroxyapatite crystals
by increasing the enamel resistance to
demineralization.

48.  9) CAD/CAM TECHNOLOGY:
 This technology eliminates the need for conventional
intra-oral impression materials.
 Laser scanners take an optical impression of a
prepared tooth and the opposing dentition and they
take a bite registration to produce an interactive three-
dimensional image.

49. VARIOUS USES OF LASERS IN
DENTISTRY
A. DIAGNOSIS
a) Detection of pulp vitality
1. Doppler flowmetry
2. Low level laser therapy (LLLT)
b) Laser fluorescence - detection of caries, bacteria and dysplastic
changes in the diagnosis of cancer .
B. HARD TISSUE APPLICATIONS
a) Caries removal & cavity preparation
b) Recontouring of bone (Crown lengthening)
c) Endodontics Root canal preparation, sterilization and
apicoectomy
d) Laser etching

50. C. SOFT TISSUE APPLICATIONS
a) Laser assisted soft tissue curettage and periapical surgery
b) Bacterial decontamination
c) Gingivectomy and gingivoplasty
d) Aesthetic contouring, frenectomy
e) Gingival retraction for impressions
f) Implant exposure
g) Biopsy incision and excision
h) Treatment of aphthous ulcers
i) Hemostasis
j) Tissue fusion - replacing sutures
k) Laser assisted flap surgery
l) Removal of granulation tissue
m) Pulp capping, pulpotomy and pulpectomy
n) Operculectomy and vestibuloplasty
o) Incisions and draining of abscesses
p) Removal of hyperplastic tissues and fibroma

51. D. LASER INDUCED ANALGESIA
E. LASER ACTIVATION
a) Bleaching agents
b) Restorations (composite resins)
F. OTHERS
a) Removal of root canal filling material and fractured
instrument.
b) Softening of gutta percha.
c) Removal of moisture/ drying of canal

52.  Painless
 Bloodless
 No anesthesia
 Reduce bacterial infections
 Preserves more healthy tooth structure during cavity
preparation
 Faster healing
 Reduces anxiety
 Reduces noise

53.  High cost
 Lack of knowledge: use & safety
 Requires specialized training for the clinicain.
 Harmful to eyes and skin of both clinician and
patients if exposed adversely.

54.  Ocular injury:
Cause: Eye abrasion occurs by direct emission from
laser source or by reflection of laser light from mirror
surfaces.
 Tissue hazards
Cause: Thermal interaction with tissue proteins &
cumulative effect of radiation exposure
 Respiratory hazards
Cause: Release of biohazardous gases during surgical
application

55.  Fire explosions:
Cause: By flammable materials
flammable solids--clothing, paper products, plastics
flammable liquids—acetone
flammable gases– O2
 Electrical hazards:
Electrical shock, fire , explosion.

56.  A) FIRE AND ELECTRICAL CONTROLS:
 Operating area must be dry to avoid electrical hazard.
 Control panel and electrical power unit protected from
splashing.
 B)CONTROL OF AIRBORNE CONTAMINATION:
 Controlled by ventillation, evacuation and adequate
suction.
 Laser filtration masks used to prevent air borne
contamination

57.  C) PERSONAL PROTECTIVE EQUIPMENT:
 All personal within the dental treatment room must
wear adequate eye protection, including the patient.
 Use of eyewear and safety glasses.
 Optical density, wavelength permissible emission
and max permissible exposure limit are some of
the factors for selection of eyewear.

58.  D) PROCEDURAL CONTROLS:
 Some dental procedures require general anesthesia.
 If general anesthesia is used during dental procedure, in
place of the standard PVC intubation tube, a red rubber
or silastic tube should be used.
 A wax spatula or periosteal elevator should be used to
shield the tissue near the teeth.
 Always check the foot switch before each procedure to
make sure it does not get stuck in position while
operating.

59. Lasers provide the clinicians, the ability to better
care for patients with advanced diagnostic methods
and improved treatment techniques.
Further scientific and medical research in the
development of advanced laser systems will
revolutionise its clinical use much more
significantly in the field of conservative dentistry.

60. 1) Nisha Garg, Textbook of Endodontics, 2nd edition.
2) Grossman, Endodontic Practice,13th edition..
3) Cohen, Pathways of Pulp, 10th edition.
4) Sturdevant,Art and science of Operative dentistry.
5) Vimal Sikri, Textbook of Operative dentistry,
2nd edition.
6) Shirish kumar R, Srikumar GPV. Lasers and its
applications in Conservative dentistry- A Review.
Annals and essence of dentistry 2017;9(1):1-6.
.

61. 7) Khatavkar R, Hegde V. Lasers in Conservative
dentistry & Endodontics- An Overview. J dent Lasers
2008;2(1):1-18
8) K Amudhalakshmi et al, Lasers in Conservative
dentistry & Endodontics- A Review. IOSR J Dent
Med Sci 2016;15(9):125-130.
9) Ratnakar P et al. Lasers in Endodontics- A beginning
of new era. Indian J Stomatol 2010 :1(2);84-87.