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
The application of laser in dental tissues was
reported by Stern, Sognnaes and Goldman in 1964.
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
It is the form of electromagnetic energy that behaves
as a wave and a particle unit of energy called as
Normal light appears white due to combination of seven
Laser light on the other hand is monochromatic
(specific colour), and each wave is identical in physical
size and shape.
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
6. Active medium:
Is composed of the chemical elements, molecules or
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
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
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
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
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
The energy is emitted constantly as long as laser is
e.g. CO2 and Diode laser
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
It is pulsed due to the pumping mechanism within the
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:
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
Laser energy passes directly through the tissue without
any effect on it. But it is highly dependent on wavelength
of laser light.
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
It can cause heat transfer to tissues adjacent to the
surgical site and unwanted damage could occur.
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
60-70 coagulation, protein
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
Infrared light: 750-10000nm, most dental lasers are in
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.
20. ARGON LASER
Soft tissue incisions and ablations
Also FDA approved to be used in
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
reoxidise carbon monoxide, formed
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.
More soft tissue water loving.
Less depth of penetration.
Mostly used to treat superficial mucosal lesions such as
apthus ulcer lesions, dentin hypersensitivity .
Implant soft tissue surgery
Should avoid contact with hard tissue, especially tooth
Root surface notching
Delayed wound healing
24. DIODE LASER
Most commonly used soft
It is a active medium LASER
combinations of aluminium,
gallium, arsenide crystals.
These semiconductors get
activated or pumped when an
electrical current passed
25. Which then produces an elliptical shaped display of
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
810- 830 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.
Caries and Calculus Detection.
Portable instrument because of its small size.
Should avoid contact with hard tissue, as it may
cause damage to root cementum and bone during
Tissue penetration is less than Nd: YAG LASER.
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
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.
Incisional and excisional biopsies of both benign and
Deepithelization reflection of periodontal flaps.
should avoid hard tissue contact.
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
It is a hard tissue laser.
Well absorbed by the soft and
32. Clinical applications
Approved by AAP best for
Root surface debridement
Resective osseous surgeries
Cavity preperation of incipient caries.
It must be used with adequate water spray when cutting
33. Recent Advances
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
Cavity preperation 3.5- 4.5 W
Access cavity preperation 6 W
Root canal shaping &
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
Sulcular Debridement with Fibre-optic Laser
It is done before any instrumentation even probing.
Its main objective is to affect the bacteria within the
To reducing the risk of bacteremia caused from
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.
It removes biofilm within the necrotic tissue of the
It uses a rapid, gliding, multidirectional motion with tip of
the fibre in constant contact with the pocket wall.
It also causes coagulation by sealing the capillaries of the
Soft tissue lasers are a good choice in bacterial reduction
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
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.
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
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
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
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:
Deepithelization of reflected periodontal flap.
45. Advantages of Lasers
Has great hemostasis
Minimal wound contraction
Cause less pain
Can cut, ablate and reshape the tissues more easily as
compare to conventional scalpel
Less time consuming
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