Albert Einstein (1917)– Theory of
Javan (1961) – HeNe Continuous
mode of laser
Patel (1964) – CO2 Laser
Shfir (1977) – First documented
use in OMFS
Anderson RR & Parrish JA
(1983) – Selective Photothermolysis
COMPONENTS OF LASER
The inner part of laser, or the components of laser, are as follows:
B) Two mirrors- one at each end of optical cavity
(C) Excitation sources
(D) Cooling system
(E) Focusing lenses
(F) Other controls
LASER CAVITY/RESONATOR CAVITY
Actual optical cavity can be of different shapes and
Cylindrical or rectangle (simplest design)
Elliptical– rod and lamp at the ellipse foci
Circular– rod and lamp parallel to one other
Optical cavity is constructed of a reflecting or
for e.g. ceramic or polished metal.
Core of the cavity comprised of chemical elements, molecules or compounds is called active medium.
- Most lasers are named after the substance that is used to create the actual laser light –
Lasant can be a gas, a crystal or a solid-state semiconductor;
Neon gas in He:Ne laser
Argon ions in argon laser
Gas molecules in CO2 laser
Although these characteristic elements or molecules are the main source of laser there may be
other ingredients with in the resonator cavity that assist in the alteration of the quantum
state of the species.
E.g in CO2 laser helium and nitrogen assist in the process of activation and deactivation
• One at each end of optical cavity, placed parallel to each other.
• One mirror is reflective, which allows photons to be reflected back and forth to allow further
• The other mirror is partially transmissive thus allowing light of sufficient energy to exit the
The mirrors are separated by a fixed distance (d) forming a Fabry-Perot interferometer.
Principle of interference- Two or more waves simultaneously penetrate some material, forms a
combined wave. Resulting a larger wave.
Constructive interference – when the waves are in phase
Destructive interference – when waves not in phase
Dielectric mirrors: alternative layers of high refractive index materials, such as titanium
oxide, and low refractive index material, such as silicon oxide. These materials are deposited on
a glass substrate and each layer is designed to be one quarter of the wavelength thick.
Alternating pattern of high and low RI materials– light waves are reflected from
successive surfaces and undergoes phase change equivalent to one half wavelength on
reflection from high RI materials, But no phase change occurs on reflection from low RI
materials; thus all the reflected rays are interfered constructively, and light in this particular
wave length is kept inside the laser chamber and rest leak out of the system.
Depending on the number of layers in the mirror – 20 or more layers – the reflectance is 100%
for atleast one particular wave length
This applies to the energy or excitation level of a laser medium.
The energy possessed by the lasant at a given time is related directly to the application of
external or internal energy from a source.
Electrical discharge – CO2 laser, He:Ne, Krypton
Chemical reaction –
External high powered radiant source as xenon or krypton flash lamp – Nd:YAG, Ruby laser.
Alternating magnetic fields – X-ray lasers
Excitation sources - either a flash lamp strobe device or an electrical coil, which provides energy into active
This causes a process called OPTICAL PUMPING, in which energy is driven into the resonant chamber. This
energy is used to change the energy level or quantum state.
GENERATION OF LASER ENERGY-
Certain laser medium or LASANT with in the resonator space is energized by internal or external
energy to produce an excited population of atoms, molecules and rare gases (SPECIES). The energy with
in the resonator reaches a population inversion in which the greatest cohort of species is in an excited
state and in which photos are emitted and amplified within a laser cavity. The radiant energy is released
as a laser beam.
Distinctive features laser light are-
1. Monochromatic- one specific colour, thus of a single wavelength
2. Coherent- each wavelength is identical in physical size and shapes
3. Collimate- photons can be collimated into an intensely focused energy beam that interacts with the
As the photons are produced, they continue to travel within the laser chamber, exciting more atoms, which
then produce additional photons.
The intensity of energy increases within the laser chamber as the chain reaction continues. This is called
amplification of the laser beam.
When the laser cavity is opened, a beam of light of a singular wavelength is released from the chamber
and delivered as laser beam.
The smallest unit of energy is absorbed by the electrons of an atom or molecule (of the active medium),
creating a short excitation; then a quantum is released, a process called spontaneous emission. The mirrors
at each end of the active medium return the photons back and forth to permit the emission of the laser
Depending on how the laser active medium is energized, the laser photonic emission can occur inherently
in a continuous wave (CW) or free-running pulsed (FRP) emission mode.
CW means that energy is emitted constantly for as long as the laser is activated.
A “gated” or “super-pulsed” laser is a variation of CW.
The length of each pulse is called “pulse width” or “pulse duration”.
On the other hand, FRP is a characteristic seen in lasers whose pulses have peak powers in the 1000w
It refers to the light waves produced by laser as a specific form of electromagnetic energy. The very
short wavelength below approximately 300nm is called ionizing. Non ionizing radiations are those with
wavelengths larger than 300nm and they have lesser frequency and less photon energy. They cause
excitation and heating of tissues with which they interact. All dental lasers are non-ionizing.
NON - IONISINGIONISING
The wavelength used in medicine and dentistry generally ranges from 193 to 10.600nm, representing a broad
spectrum from ultraviolet to the far infra-red range.
1. Fiber optic delivery system: use optic strands, by and large made of quartz,
2. Hollow Fiber: Er: YAG and CO 2 lasers utilize a hollow tube with reflective internal walls
which transmit laser energy along its internal axis.
3. Articulated arm delivery system: This delivery system utilizes a progression of verbalized
mirrors (generally 7) associated one to each other, prompting transmission of vitality.
Disadvantage: requires a precise system for alignment of mirrors.
4. Handpieces-close contact and non-contact handpiece
TYPES OF LASER LIGHT DELIVERY
Energy density (Fluency)-
Energy density is defined as energy (Joules) per square centimetre of spot size (J/cm2).
The laser beam spot size can be focused or defocused. Depending on the degree of beam focus, the
laser beam spot size can be altered and fluency will accordingly change.
Effect of distance of laser beam on the spot-size at
target tissue surface Effect of focused and defocused laser beam on
The exposure time is the amount of time the operator keeps the laser light directed at the
The time allowed for the energy to be absorbed by the target tissue and dissipate is the
thermal relaxation time.
When the fluence, or the energy given to a particular area , is greater than the tissue
vaporisation threshold, and the pulse width is less than the thermal relaxation time of tissue,
the tissue is vaporised with each pulse and no significant and no thermal damage occurs
beyond the site of laser impact.
This was first theorised by Anderson and Parrisch in 1983.
The action of lasers on dental tissues and bacteria depends on the absorption of laser by tissue
chromophores (water, apatite minerals and various pigmented substances) within the target tissue.
The principle action of laser energy on tissue is photo-thermal, and any mechanisms may be
secondary to this process or may be totally independent.
In general, lasers have four different interactions with the tissues.
1. Photo-thermal interaction
2. Photo-chemical interaction
3. Photo-mechanical interaction
4. Photo-electrical interaction
1. Photo-thermal interaction-
This occurs with high powered lasers. The radiant energy absorbed by tissue substances are
transformed into heat energy, which produce the tissue effect.
2. Photo-chemical interaction-
The basic principle of photochemical process is that specific wavelengths of laser light are
absorbed by naturally occurring chromophores, which are able to induce certain biochemical
3. Photo-mechanical interaction-
This includes photo-disruption or photo-dissociation and photo-acoustic interactions. In
photo-acoustic effects, the pulse of laser energy on the dental tissues can produce a shock
wave. When this shock wave explodes the tissue, it creates an abraded crater.
4. Photo-electrical interaction–
This includes photo-plasmolysis, which describes how the tissue is removed through formation
of electrically charged ion.
Lasers used in dental practice can be classified into several categories according to:
(1)the range of wavelength,
(2) the lasing medium, such as gas laser and solid laser
(3) tissue penetration - soft tissue and hard tissue lasers
(4) The risk related to laser application, and
(5) potential hazards.
CLASSIFICATION OF LASERS
The most commonly used nowadays are the following.
Developed by Patel in 1964
Emits light in the invisible mid infrared portion of the spectrum at a wavelength of 10600 nm.
Uses a mixture of carbon dioxide, nitrogen, and helium as its medium.
Excited by a high-voltage electrical current.
Invisible, a red helium-neon laser is often used in parallel, as an aiming beam.
Chromophore that absorbs the carbon dioxide wavelength is water
The depth of penetration can be as shallow as 0.2 mm, with very little scatter, reflection, or transmission.
Used ideally for soft tissue incision and ablation, sub-gingival curettage, superficial lesions and removal
CARBON DIOXIDE LASERS
ADVANTAGES OF CO2 LASER
1. Sterile surgical field, bactericidal, viricidal
2. Minimal cicatrix formation
3. Access to difficult areas by reflection
4. Ability to coagulate, vaporize and incise
5. Good haemostasis
6. Reduced local tissue trauma and edema
7. Precise delivery of energy to diseased tissue vis microscopes
8. Reduced pain – neuron sealing, decreased pain mediator release.
9. Minimized tumor cell dispersion by lymphatic sealing.
Erbium: YAG (Er: YAG) laser
An active medium of a solid crystal of yttrium aluminium garnet that is doped with erbium.
For facial resurfacing
Incision and ablation of soft tissue.
The presumed advantage of the Er: YAG laser system is its ability to remove superficial skin
ER: YAG LASERS
ER, Cr: YSGG LASERS
• (Er,Cr):YSGG (yttrium scandium gallium garnet) laser - (2.780nm).
• Active medium of a solid crystal of yttrium scandium gallium garnet that is doped with erbium
• There is absence of melting, charring and carbonization.
• Absorption in water is two to three times lower than Er:YAG laser
• Thermal effects on the tissue are much higher if not administered correctly.
• The erbium wavelengths have a high empathy for hydroxyapatite and the highest absorption
of water compared to other dental laser wavelengths.
• This is the preferable laser for treatment of dental hard tissue, but also, in contact mode with
special surgical tips, it can be used to cut soft tissues.
• Bactericidal effects, which can sterilize the area,
• Analgesic effect on the target tissues, similar to the Nd:YAG devices.
• Erbium laser energy applied to bone releases growth factors that enhance regeneration of
The difference between CO2 and Er:YAG laser lies in their differing absorption coefficients:
Er:YAG lasers are much more strongly absorbed in the water. On the other hand, CO2 lasers
show very high absorption on the tissue surface.
Developed by Bridges in 1964.
Delivers a green-blue light beam in the 488- or 514-nm range, placed in the visible spectrum.
Active medium -argon gas that is energized by a high-current electrical discharge.
It is fibre optically delivered with fibre diameter 300μm in continuous wave and gated pulsed
Because the argon beam is highly absorbed by hemoglobin and melanin, it has excellent
Neither wavelength is well absorbed in dental hard tissues or in water.
These lasers are useful in the treatment of-
• pigmented lesions,
• vascular anomalies and
• soft tissue incisions and ablations.
Neodymium: Yttrium -Aluminium-Garnet (Nd: YAG)
Geusic and coworkers in 1964, with wavelength of 1064 nm
It belongs to invisible near- infrared portion of the electromagnetic spectrum.
A flashlamp is used as the energy source to activate Nd: YAG crystal
Nd: YAG with a very long pulse duration (90-150µs) penetrates water upto 6mm depth before
it is attenuated to 10% of its original strength.
Energy is scattered rather than absorbed.
Used as a contact laser scalpel or ablation tool, with excellent hemostasis and cutting abilities
ND: YAG LASERS
Excellent for the treatment of-
• vascular lesions
• intraoral and extraoral pigmented lesions
• achieving hemostasis.
• open TMJ arthroplasty,
• malignant lesion excision,
• black and blue tattoo pigment removal,
With ND: YAG laser procedures anesthesia is required in less than 50% of cases.
The wide-spread belief that Nd:YAG lasers have the highest penetration depths in the soft
tissue is only partly correct.
A study conducted at the RWTH Aachen proved that a free-running pulse Nd:YAG laser has a
penetration depth of approximately 0.1mm to 0.3mm, whereas a continuous wave mode
Nd:YAG laser has a penetration depth of up to 6mm.
State of the art in lasers for dentistry. Gutknecht N.
Journal of the laser and health academy Vol.2008;No3/1.
This laser is a modified version of the Nd: YAG laser.
With the addition of a frequency- doubling crystal, this laser
emits laser light at the 532-nm wavelength
Used in the treatment of vascular and pigmented lesions, tattoo
removal, blepharoplasty, and some endoscopic procedures
• Wavelength range from about 800nm to 980nm, 1-10W power
• Solid active medium laser that includes semi-conductor crystals using some combination of
aluminium or indium, arsenic and gallium.
• The light energy is placed at the starting of the near-infrared portion of the invisible non-
• Employs a flexible optic fibre (300μm diameter) to deliver the treatment beam to the desired
• They run in either CW or pulsed mode.
• Diode laser is one of the most versatile with regard to the number of possible treatments
options and can be effectively used in the field of soft tissue surgery.
In oral surgery, these machines can be used in numerous clinical procedures,
• soft tissue surgery,
• second stage implant recovery, in peri-implantitis,
• sub-gingival curettage etc.
• Disinfects the treated area.
• Ease of operation, the sub-millimetre dimension and their extreme compactness.
The holmium: yttrium-aluminum-garnet (Hol:YAG) laser emits laser light at 2140 nm
Extensively used in endoscopic orthopedic surgery.
It is also extensively used in the TMJ for lysis of adhesions and sculpting of fibrocartilaginous
HOL: YAG LASER
The Q-switched ruby laser produces visible, pulsed red
light at the 694-nm wavelength
To treat some pigmented lesions and tattoos effectively.
The slightly longer wavelength allows for greater depth
of penetration and is more effective in the removal of
Q-SWITCHED RUBY LASER
This laser produces yellow visible light in the 400- to 1000-nm range
pigmented and hemopigmented lesions, tattoo removal.
photodynamic cancer therapy,
ablation of salivary gland and kidney stones,
FLASHLAMP-PUMPED PULSED DYE (FLPPD)
At wavelengths of 511 and 578 nm,
Effective in treating hemangiomas such as port-wine stains or
large superficial telangiectasias,.
used to ablate some pigmented lesions such as lentigines,
ephelides, lentiginous nevi, and tattoos
COPPER VAPOR LASER
These lasers emit ultraviolet light at 193 to 351 nm,
Active medium- Halide gas
It is currently used for keratotomy to reshape corneal tissues and to correct poor vision.
Cloth saturated with water around the field
Laser resistant drapes for personnel, anesthetic circuit.
LASER SAFETY IN SURGERY AND ANESTHESIA
Alcohol as a part field is to be avoided
If not the alcohol should vaporize completely before draping.
Protection of patient’s throat and delicate oral tissues from accidental beam impact
Use of wet gauze packs or towels to avoid reflection from shiny metal surfaces
Adequate high speed evacuation should be used to capture laser plume, which is biohazard
The surgical beam should be tested for alignment prior to each use of the machine.
No instruments are passed across the intended path of laser.
Speed of movement of the laser beam over the target tissue in order not to occur thermal
• Exposure of bone to heating at levels equal to or more than 47°C is reported to include
cellular damage leading to osseous resorption.
• Inflammable agents like ether and cyclopropane is absolutely contraindicated in laser
• Instead halothane, enflurane, isoflurane and sevoflurane
• If surgery along the airway – helium and oxygen can be used
• When used to remove viral lesions (warts) the fumes can carry viral particles so proper face
mask is a must.
• Also the fumes can have carcinogens.
Even if eyes closed it can penetrate the eye lids
Only normal saline is used to lubricate the eye,
petroleum based is avoided.
Avoid alcohol preparation
Hairs near the field can ignite. It can be kept moist.
Etching and disfigurement of enamel
Dental splints fabricated from laser resistant material.
Red rubber, PVC, silicon – red rubber is overall better.
Tubes wrapped with metallic foil – mucosal injury
Wrapped with metallic tape of copper or silver.
Silver anode sheet that has spongy water-absorbant material outside and adhesive inside
Ceramic coated endotracheal tube by Xomed (Florida)
Norton and Devos endotracheal tubes , Porch tube are used through oropharynx or trachea.
Cuffed metallic tubes are available.
Water is injected in to the cuff to inflate
1. Post signs that lasers are being used at all possible entry
2. Eye shields must be worn by all personnel at all times
3. Safety shields must be used
4. A bucket of sterile water should be immediately available in
the operating room
5. Credentialing of surgeons for the use of each type of laser and
laser apparatus is needed.
6. Short bursts, intermittent lasing, and changing from area of
the lesion to other sequentially
7. Cooled irrigation to keep the tissues from heating
The advantages of lasers in comparison to other conventional dental equipment are reported
by various authors include:
● Increased coagulation
● Reduction in bacteraemia
● Tissue surface sterilization
● Faster healing response
● Decreased swelling, oedema and scarring
● Reduced pain and discomfort after
● Minimally invasive surgical procedures, compared to conventional techniques;
● Increased patient acceptance
● Reduced surgical time.
ADVANTAGES OF LASERS-
COMPLICATIONS OF LASERS-
1. Herpes Simplex
4. Eye and Teeth Injuries
Soft Tissue Clinical Applications-
The most popular and effective lasers nowadays for soft tissue procedures are CO2, Nd:YAG and Diode
There are many categories of soft tissue procedures that can be treated by lasers, such as
• gingivectomy and gingivoplasty,
• de-epithelialization of reflected flaps,
• second stage exposure of dental implants,
• sub-gingival debridement curettage,
• incisional and excisional biopsies of both benign and malignant lesions,
• removal of granulation tissue,
• coagulation of free gingival graft donor site,
• irradiation of apthous ulcers,
• removal of diseased tissue around the implants etc.
FACIAL SKIN RESURFACING
1. Photo damage: Dyschromias & Rhytides
2. Atrophic (depressed) scars : Post acne
Mechanism: Thermal ablation of Epidermis & papillary dermis
a) Single pass CO2
b) Modulated Er : YAG
An additional 0.5 mm should be added to a normal margin to allow for the lateral zone of necrosis
associated with laser action.
Fibroma of the right cheek (left) and removal of the lesion using Er: YAG laser with X-Runner handpiece
Fibroma of the hard palate (left) and removal of the lesion using Er: YAG laser with X-Runner handpiece
3 weeks after surgery
Leukoplakia of the right cheek
3 weeks Post-op
Leukoplakia of the alveolar ridge (left) and removal using Er: YAG laser
6 weeks Post-op
The results study confirmed that treatment of leukoplakia by Er: YAG laser had less edema, post-
operative bleeding and pain, in comparison to the conventional surgical methods of treatment such as
The procedure was easily tolerated and postoperative pain was low or absent.
Evaluation of Er:YAG laser for surgical treatment of precancerous lesion
Clinical cases of soft-tissue surgery with X-Runner in QSP mode.
Gabrić Pandurić D, Katanec D, Filipović Zore I
Journal of the laser and health academy
Exposure of an impacted tooth (soft tissue impaction) can be done using Laser HF, (Gingivectomy mode
975nm, 3W, CW).
Hard Tissue Clinical Applications
• removal of impacted teeth under bone,
• osseous re-contouring,
• implant and bone osteotomies,
• bone grafting,
• jaw continuity defects,
• removal of inflammatory tissues around implants,
• crown lengthening,
• uncovering of permanent teeth for orthodontic purposes etc.
Erbium (Er) family of lasers can be the lasers of choice.
Er lasers use extremely short pulse durations and can easily ablate layers of calcified tissue with
minimal thermal effects.
Removal of the cortical plate of the maxilla using Er: YAG laser (X-Runner, QSP mode, 750 mJ, 10 Hz, 10
ml/ min) to show the implant within the sinus and to allow implant removal
Er:YAG laser usage for preparation of the dental implant site in the lateral part of the right
Comparison between Er: YAG laser (lateral implants) and scalpel for second stage surgery
3 days Post-op
Holmium laser fiber with aluminium case over quartz fiber proved suitable for removal of fragmented synovium
within the TMJ.
It also replaced cautery instruments used for hemostasis, synovectomy and anterior release procedures.
Low level laser therapy
LLLT works through photo biomodulation, which is based on metabolic activation through
through stimulation of the cellular respiratory chain in mitochondria that in turn increases
vascularization and enhances the supply of oxygen in hypoxic cells.
Photodynamic therapy (PTD) is currently being evaluated for the treatment of head and neck,
skin, intra-abdominal, and other types of cancers.
carbon dioxide laser and other lasers have also been used in the micro anastomosis of nerve and
vascular tissue with some success.
• Reviewed the effectiveness of PDT in the treatment of early SCC of the head and neck, with
similar response rate to surgery.
• The treatment is relatively easy to perform, can be repeated and has minimal scarring.
65 year old female with T2 SCC of lower lip and vestibule.
PDT- 2 days prior to surgery 2mg/kg of porfimer sodium was injected iv and laser at 639 nm wavelength
and light dose of 50 J/cm2 was used
As Dr Theodore Maiman, the inventor of the first laser stated:
“The medical application of the laser is fascinating for two reasons. It is optimistic mission on
the one hand while, on the other, it counteracts the original impression of the laser being a
1. Fonseca, oral and maxillofacial surgery, vol. 1
2. Clinics of North America, LASERS in OMFS, vol.16, May2004
3. Fundamentals of LASER dentistry, Kripa Johar
4. Theodoros Tachmatzidis, Nikolaos Dabarakis ,Technology of Lasers and Their Applications
in Oral Surgery: Literature Review, BALKAN JOURNAL OF DENTAL MEDICINE ISSN
5. Dragana Gabrić, Advanced Applications of the Er:YAG Laser in Oral and Maxillofacial
Surgery, A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2, chapter 34
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