Lasers

1. HEENA SHARMA
LASERS

2. LASER HISTORY
 In 1917, Albert Einstein published ideas on stimulated
emission radiation.

3.  Based on the Albert Einstein’s theory of spontaneous
and stimulated radiation, Miaman in 1960 develops
the Ist prototype of laser by using crystal of ruby as
the active medium that emit a coherent radiation
light, when stimulated by energy.
 In 1961, the first gas laser was described by Javan et
al.
 The application of laser in dental tissues was
reported by Stern, Sognnaes and Goldman in 1964.

4. INTRODUCTION
 L LIGHT
 A AMPLIFICATION
 S STIMULATED
 E EMISSION
 R RADIATION
 Laser is a device that utilizes the natural oscillations
of atoms or molecules between energy levels for
generating coherent electromagnetic radiations
usually in the ultraviolet, visible or infrared regions of
the spectrum.

5.  Light
 It is the form of electromagnetic energy that behaves
as a wave and a particle unit of energy called as
photon.
 Normal light appears white due to combination of seven
basic colors.
 Laser light on the other hand is monochromatic
(specific colour), and each wave is identical in physical
size and shape.
 Amplification
 It takes place inside the laser, identifying the
components of laser instrument shows how laser light is
produced. The centre of the laser is called the Laser
cavity.

6.  Active medium:
 Is composed of the chemical elements, molecules or
compounds.
 Lasers are generically named after the material of the
active medium that can be a container of gas such as
 canister of CO2 gas.
 a solid crystal of yttrium, aluminium and garnet (YAG).
 a solid state semiconductor such as diode laser.

7. Pumping Mechanism:
 It surrounds the active medium such as flash lamp
strobe device, electrical circuit, electrical coil or similar
source of energy that pumps energy into the active
medium.
 When this pumping mechanism pumps the energy
into the active medium then energy is absorbed by the
electrons in the outermost shell of active medium’s
atoms.

8. Optic resonator
 It is the arrangement of mirrors, forming the standing
wave cavity resonator for the light wave.
 Mirror can be flat or spherical.

9.  Stimulated Emission
 This is the process by which laser beam is produced inside
the laser cavity.
 It was proposed by Albert Einstein in 1916 that when
smallest unit of energy is absorbed by electrons of an atom,
a brief excitation occurs.
 Photon travelling in the path of exited atom having same
excitation energy level that would result in the release of 2
quanta or coherent wave of 2 photons.
 These photons in turn are then able to energise more atoms
in a geometric progression which further cause the emission
of additional identical photons resulting in an amplification of

10.  Radiation
 It refers to light waves produced by the laser as a
specific form of electromagnetic energy.
 Very short wavelength of approx. 350nm are termed as
ionizing and are able to penetrate biologic tissue
deeply.
 They can produce charged atoms and molecules that
pose a mutagenic effect on cellular DNA.
 The wavelength greater than 350 nm cause excitation
and heating of tissue.

11. Mode Of Emission
 Continuous
 The energy is emitted constantly as long as laser is
activated.
e.g. CO2 and Diode laser
 Pulsed
 Gated : it is a variation of continuous wave mode.
 Periodic alteration in the delivery of laser light is seen,
which is achieved by electronic/ mechanical shutter.
 This helps to limit undesirable residual thermal damage
seen with continuous mode.

12.  Free Running
 In this mode, large peak of energy is emitted within
microsecond followed by long period in which laser is
off.
 It is pulsed due to the pumping mechanism within the
laser.
 Undesirable thermal damage is low in this mode.
e.g. Nd: YAG, Er: YAG and ER: Cr: YSGG.

13. Laser Effect On Tissues
 Laser interact with tissue by the following mechanisms:
Reflection
Transmission
Scattering
Absorption

14. Reflection:
The beam bounces off the tissue with no effect in target
tissue. This can be dangerous as it can be directed to
any unintentional object such as eyes, so wavelength
specific safety glasses with side shields are
recommended.
Transmission
Laser energy passes directly through the tissue without
any effect on it. But it is highly dependent on wavelength
of laser light.

15. Scattering
It occurs when the light energy bounces from molecule
to molecule within the tissue. It distribute the energy
over a large volume of tissue, dissipating the thermal
effect.
 It can cause heat transfer to tissues adjacent to the
surgical site and unwanted damage could occur.
 Absorption
 The amount of energy absorbed by the tissue
characteristics such as pigmentation, water content and
on laser wavelength.
 The principal laser tissue interaction is photothermal.
 Absorbed light energy gets converted to heat and can
lead to warming, coagulation or excision and incision of

16. Tissue Temperature
 As the laser energy is transferred to the tissue, its
temperature begins to increase.
 Target tissue effects in relation to temperature:
Tissue Temperature Observed Effect
37-50 Hyperthermia
60-70 coagulation, protein
denaturation
70-80 welding
100-150 vaporization, ablation
> 200 carbonization

17. Classification of Lasers
 On the basis of its light spectrum
 UV light: 100-400nm
not used in dentistry.
 Visible light: 400-750nm
Most commonly used in dentistry ( Argon, Diagnodent
laser)
 Infrared light: 750-10000nm, most dental lasers are in
this spectrum.

18.  On the basis of material used:
 Gas : CO2
 Liquid : not so far in clinical use.
 Solid: Diodes, Nd: YAG, Er: Cr: YSGG, Er: YAG.
 On the basis of hardness:
 Soft laser: are of cold energy emitted as wavelengths,
which stimulate cellular activity.
e.g. Helium-neon, Gallium- arsenide.
 Hard lasers : Can cut both soft and hard tissues.
e.g. Argon laser, CO2, Nd: YAG.

19. Lasers commonly used in
dentistry
 Argon laser – 488 – 530 nm
 CO2 laser – 10600nm
 Diode lasers - 630 – 980 nm
 Nd: YAG lasers – 1064 nm
 Er: YAG laser - 2940 nm

20. ARGON LASER
 Soft tissue incisions and ablations
 Caries detection
 Composite curing
 Also FDA approved to be used in
bleaching.
 Bactericidal to perio-pathogens

21. CO2 lasers
 CO2 LASER is a LASER based on
gas mixture that contains CO2,
helium, nitrogen, some hydrogen,
water vapour and xenon.
 Hydrogen and water vapour can
help to
reoxidise carbon monoxide, formed
in
discharge of CO2 LASER.
 The depth of LASER incision is
proportional to the power setting
and duration of exposure

22.  CO2 LASER is used with power setting of 5-15 watts, either
in pulsed mode or continuous mode.
CLINICAL USE
 More soft tissue water loving.
 Less depth of penetration.
 Mostly used to treat superficial mucosal lesions such as
apthus ulcer lesions, dentin hypersensitivity .
 Depigmentation,
 Implant soft tissue surgery
 Frenectomy
 Gingivectomy

23. PRECAUTIONS
 Should avoid contact with hard tissue, especially tooth
structure.
DISADVANTAGES
 Root surface notching
 Charing
 Delayed wound healing

24. DIODE LASER
 Most commonly used soft
tissue laser.
 It is a active medium LASER
manufactured from
semiconductors, using
combinations of aluminium,
gallium, arsenide crystals.
 These semiconductors get
activated or pumped when an
electrical current passed
through it.

25.  Which then produces an elliptical shaped display of
monochromatic light.
 This light is then focussed into a very small thread of
light and directed into fibreoptic which then carries it to
the target tissue.
 The semiconductor diode available in 3 different
wavelength
 810- 830 nm
 940 nm
 980 nm
 Both 810-830 and 980 nm wavelength may used for
nonsurgical periodontal therapy.

26. CLINICAL APPLICATIONS
 Soft tissue ablation and incision.
 Sub gingival curettage.
 Bacterial decontamination.
 Caries and Calculus Detection.
 Gingivectomy
 Frenectomy
 Depigmentation
ADVANTAGE
 Portable instrument because of its small size.

27. Precaution
 Should avoid contact with hard tissue, as it may
cause damage to root cementum and bone during
subgingival curettge.
DISADVANTAGE
 Tissue penetration is less than Nd: YAG LASER.
 Charring.

28. Nd: YAG lasers
 It has a solid active medium
garnet crystal combined with
yttrium and aluminium doped
with neodymium ions.
Meyer in 1985 modified an
opthalmic Nd: YAG LASER for
dental use.

29. CLINICAL USE
 Excellent soft tissue laser
 Has more penetration depth.
 Is more hemoglobin and melanin loving.
 Used for the treatment of dentinal hypersensitivity
 Removal of granulation tissue.
 Lesion ablation
 Incisional and excisional biopsies of both benign and
malignant lesion.
 Bleaching
 Deepithelization reflection of periodontal flaps.
 Depigmentation.

30. Precaution
 should avoid hard tissue contact.
DISADVANTAGE
 Tissue penetration from LASER may cause thermal
damage 2-4 mm below surface wound, causing
underlying hard tissue damage.

31. Er: YAG lasers
 It is an active medium of solid
crystal of yttrium, aluminium,
garnet that is doped with
erbium.
 It is a hard tissue laser.
 Well absorbed by the soft and
hard tissue.

32. Clinical applications
 Approved by AAP best for
 Peri-implantitis
 Root surface debridement
 Resective osseous surgeries
 Cavity preperation of incipient caries.
PRECAUTIONS
It must be used with adequate water spray when cutting
hard tissues

33. Recent Advances
Waterlase
 It is a revolutionary device that uses laser energised
water to cut and ablate soft and hard tissues.
 Periowave, a photodynamic disinfection system uses
nontoxic dye along with low intensity lasers enable
singlet oxygen molecules to destroy bacteria.

35. CLINICAL APPLICATIONS
Procedure Power
Cavity preperation 3.5- 4.5 W
Access cavity preperation 6 W
Root canal shaping &
sterilization
1.5- 2.5 W
Gingivectomy, Frenectomy 1.5- 3 W
Periodontal pocket sterilization 1- 1.5 W
Osteotomy & bone harvesting 1.5- 3 W
Bone contouring 1.5- 3 W

36. Lasers in Non- Surgical Periodontal
Therapies
Sulcular Debridement with Fibre-optic Laser
 It is done before any instrumentation even probing.
 Its main objective is to affect the bacteria within the
sulcus.
 To reducing the risk of bacteremia caused from
instrumentation.
 To lower the microbe count.

37.  The fibre is placed within the sulcus and swept vertically
and horizontally against the tissue wall away from the
tooth, with smooth flowing motion for 7-8 seconds on
the lingual aspect then on buccal aspect of each tooth.
Decontamination
 It removes biofilm within the necrotic tissue of the
pocket wall.
 It uses a rapid, gliding, multidirectional motion with tip of
the fibre in constant contact with the pocket wall.

38.  Coagulation
 It also causes coagulation by sealing the capillaries of the
healthy tissues.
 Soft tissue lasers are a good choice in bacterial reduction
and coagulation.
 LASER in Calculus removal
 Er: YAG is mainly used for the calculus removal due to the
minimal thermal changes seen on the root surfaces.
 Chen RE et al (2002) reported that the erbium group of
lasers have shown a significant bactericidal effect against P.
gingivalis, actinobacillus actinomycetemcomitans.
 Reduction of interleukins and pocket depth was also noted.

39. Lasers in Surgical Therapies
 Osseous Surgery
 Lasers provide an advantage over conventional
instruments due to lack of vibrations of hand piece, that
increase surgical precision.
 It also improves the comfort of both patient and doctor
by markely reducing the noise and eliminating the
vibrations associated with bone cutting.
 Er: YAG laser is safe and useful for bone removal or
recontouring when used concomitantly with saline

40. Gingivectomy and Gingivoplasty
 Lasers are attracted by specific chromophores.
 The non-inflammed, fibrotic gingiva is treated with
diode and Nd:YAG.
 When the gingiva is hyperaemic and inflammed, less
power is needed because of high amount of
chromophore in the tissue.
 For fibrotic tissue, more power is needed to incise as it
has less chromophore.

41. Gingivectomy
Frenectomy
Depigmentation Treatment of Aphthous
Ulcers

42.  Frenectomy
 lasers such as Nd: YAG, Er: YAG, CO2 enable
minimally invasive soft tissue procedures.
 Free Gingival Graft
 gingival recession is the most common problem that
involves the mandibular anterior teeth due to broad
muscle pull.
 Treatment of this by using lasers with free gingival
graft minimizes the post operative complications.

43.  Lasers and Implants
 Gingival enlargement is relatively common around
implants when, they are loaded with removable
prosthesis.
 Lasers can be used for the treatment of peri- implantitis.
 Er: YAG laser due to its bactericidal and
decontamination effect can be used in maintenance of
implants.
 Some researchers have also suggested that Er:YAG
laser can be used to prepare holes for the implant
placement in the bone in order to achieve faster
osteointegration of placed implant.
 It also produces less tissue damage as compare to

44. other procedures that can be done with lasers cane be:
 Depigmentation
 Crown lengthening
 Vestibuloplasty
 Deepithelization of reflected periodontal flap.
 Operculectomy.

45. Advantages of Lasers
 Has great hemostasis
 Bactericidal effect
 Minimal wound contraction
 Cause less pain
 Can cut, ablate and reshape the tissues more easily as
compare to conventional scalpel
 Less time consuming

46. CONCLUSION
 With the advancement in technology in dentistry, lasers
appear as an alternative or adjunctive to conventional
mechanical periodontal treatment.
 Currently, among the different lasers available, Er:YAG
possess the characteristics suitable for dental
treatment, due to its dual ability to ablate soft and hard
tissues with minimal damage.
 In addition, it also possess bactericidal effects, ability to
remove plaque and calculus make it a promising tool for
periodontal treatment.