uses of laser have been increased with time

1. LASER IN CONSERVATIVE DENTISTRY
&
ENDODONTICS

2. CONTENTS
• Introduction
• Classification
• LASER wavelength in dentistry
• Working principle
• Characteristic of a laser beam
• Dental laser delivery system
• Tissue response to LASER
• LASER wavelength used in dentistry
• Applications of LASER in dentistry
• Laser hazards and safety
• Conclusion

3. INTRODUCTION
• LASER is an acronym for Light Amplification by Stimulated Emission of
Radiation.
• A device that emits light through a process of optical amplification
based on the stimulated emission of electromagnetic radiation.
• In dentistry, laser provides a precise and effective way to perform
many dental procedures. The potential for laser dentistry to improve
dental procedures rests by allowing for treatment of a highly specific
area of focus without damaging surrounding tissues.

4. Theodore Maiman
Maiman’s laser, based on a synthetic ruby crystal grown by
Dr. Ralph L. Hutcheson was first operated on 16th May 1960
at the Hughes Research Labs Malibu, California.

5. CLASSIFICATION
WAVELENGTH
ARGON 514 nm
KTP 532 nm
DIODE 803, 810, 940, 980, 1064 nm
Nd: YAG 1064 nm
Nd: YAP 1340 nm
CO2 10,600 nm
1. Soft tissue laser

6. Er, Cr: YSGG 2780 nm
Er: YAG 2940 nm
2. Hard and soft tissue lasers
3. Photopolymerization lasers
ARGON 488 nm
4. Bleaching / tooth whitening lasers
KTP 532 nm
DIODE 803, 810 – 980 nm
5. Caries detection lasers
DIODE 655 nm
6. Dentin desensitization
Er: YAG 2940 nm
Er, Cr: YSGG 2780 nm
CO2 10,600 nm

7. LASER wavelengths in dentistry

8. Working principle of LASER
• Usually, light follows the principle of “spontaneous emission” but laser
machine follows on “stimulated emission”.

9. When a photon strikes an atom
Electrons within the atom jump to a higher energy level.
Thus, this atom is now pumped to an excited state.
Thus, this atom is unstable now and will try to return to its resting state.
Releasing the stored energy in the form of emitted photons.
This type of emission is known as Spontaneous emission.
1. Spontaneous emission

10. When a photon strikes an atom
Electrons within the atom jumps to a higher energy level.
Thus, this atom is now pumped to an excited state.
If an atom in the excited state is struck by a photon of identical energy as the photon to be emitted.
It triggers the decay of excited electron to a lower energy state.
Thus, the result of stimulated emission in two photons of identical wavelength travelling in the same direction.
The spontaneous emission of a photon by one atom will stimulate the release of a second photon in a second atom
and these two photons will trigger the release of two more photons. These four then yield eight, eight yield sixteen
and so on.
In a small space at the speed of light, this photon chain reaction produces a brief intense flash of monochromatic
and coherent light which is termed as ‘laser’ and this process is called “light amplification”.
2. Stimulated emission (in LASER)

11. CHARACTERISTICS OF A LASER BEAM
1. Monochromatic
- one specific wavelength of light (one specific color)
- the wavelength of light is determined by the amount of energy
released when the electron drops to a lower orbit.
2. Coherent
- “organized”
- indicates that the light waves produced by a laser have a specific form
of electromagnetic energy and are in phase with one another.

12. 3. Collimated
- All the emitted waves are parallel and the beam divergence is very
low, ensuring a constant size and shape of the beam.
- This property is important for good transmission through delivery
systems.
4. Intense in nature

13. DENTAL LASER DELIVERY SYSTEMS
1. Hollow tube delivery system:
• A flexible hollow tube having an interior mirror finish.
• The laser energy is reflected along the hollow tube and exits
through a handpiece at the surgical end, with the beam striking the
tissue in a noncontact mode (i.e., without directly touching the tissue).

14. 2. Glass fiberoptic delivery system:
• A flexible glass fiberoptic cable in various
diameters, with sizes ranging from 200 to
1000 µm.
• Although the glass fiber is encased in a
resilient sheath, it cannot be bent into a sharp
angle.
• This fiber fits into a handpiece with the bare
end protruding.
• This system can be used in both contact and
noncontact modes.

15. TISSUE RESPONSE TO LASERS
The light energy from a laser beam can have different interac tions with
the target tissue depending on two principal factors:
1. Wavelength of the laser used
2. Optical properties of the target tissue

16. These two variables determine the following responses
• Reflection: The laser beam reflects or redirects itself away from the tissue surface
and have no effect on the target tissue.
• Absorption: This depends on tissue characteristics such as water content and level
of pigmentation and on laser wavelength and emission mode.
• Transmission: There is no effect on the target tissue since it transmits the laser
energy through itself. This depends on the wavelength of the laser employed.
• Scattering: This process weakens the energy of the beam and produces no useful
biological effect. Scattering can cause heat transfer to the adjacent tissues and
consequent thermal damage.

18. LASER WAVELENGTHS USED IN DENTISTRY
1. ND:YAG
• Solid active medium containing a crystal of yttrium- aluminum-garnet
doped in neodymium Wavelength: 1064 nm (invisible beam in the infrared
range)
• First laser designed exclusively for dentistry
• Fiberoptically delivered in a pulsed mode and is most often used in contact
with the tissue.
• The pulsed Nd:YAG laser is ideal for soft-tissue procedures and root canal
sterilization.

19. 2.DIODE
• We can change wavelength.
• Solid-state semiconductor laser that uses a combination of aluminum, gallium, and
arsenide that converts electric energy into light energy
• Wavelength: 800-980 nm
• Fiberoptically delivered in a continuous or pulsed mode and used commonly in
contact with the tissue
• Poorly absorbed by tooth structure; hence, soft-tissue surgery can be safely
performed in close proximity to dental hard tissues
• Advantage of being compact, portable, and economical.
• Diode laser light is well absorbed by pigmented tissues and is a good soft-tissue
surgical laser indicated for precision cutting and coagulation of gingiva.

20. 3.Co2 LASER
• Gas-active medium laser
• Wavelength: 10,600 nm
• Delivered through a hollow tube system via a handpiece and cannot be delivered in a
fiberoptic
• Highly absorbed by both hard and soft tissues and has a shallow depth of penetration
• Not suitable for hard tissues due to the deleterious thermal absorptive effect on the
pulp
• The wavelength of a CO, laser is ideal for soft tissues and especially useful in cutting
dense fibrous tissue.

21. 4.ER:YAG AND ER,CR:YSGG
• Er:YAG is a solid active medium crystal containing yttrium-aluminum-garnet that is doped
with erbium.
• Wavelength:
Er:YAG: 2940 nm
Er, Cr:YSGG: 2790 nm
• Delivered through a fiberoptic system in a pulsed mode.
• These wavelengths cannot be easily transmitted along the glass fiber, thus making this
system less flexible and expensive.
• These wavelengths have the highest absorption in water and have a high affinity to
hydroxyapatite. The vaporization of water from dental hard tissues causes the tissue to
virtually explode away
• They are ideal for hard-tissue cutting and drilling

22. 5. ARGON
• Active gas medium containing argon
• Two emission wavelengths:
• 488 nm. Blue in color
• 514 nm. Blue-green in color
• Delivered through a fiberoptic system in a continuous as well as a pulsed mode
• The 488-nm emission is the exact wavelength needed to activate camphoroquinone.
• This laser is used to cure light-activated composites, light-activated impression materials, and
light-activated bleaching gels
• The 514-nm wavelength has the highest absorption in hemoglobin and is used for its good
hemostatic capabilities

23. APPLICATIONS OF LASERS IN CONSERVATIVE
DENTISTRY
• Caries detection
• Caries prevention
• Caries Removal and cavity preparation.
• Restoration removal
• Etching of enamel and dentin
• Photopolymerization
• Treatment of dentinal hypersensitivity
• Bleaching

24. Caries Detection
• Lasers can be used to detect incipient carious lesion which cannot be
diagnosed clinically and radiographically.
• Lasers used for caries detection:
• Quantitative Laser Fluorescence(QLF)
• Infrared Laser Fluorescence Technique using DIAGNOdent.
• Optical Coherence tomography

25. Quantitative Laser Fluorescence
• Used for detection of smooth surface and fissure caries at an early stage.
• In this method tooth is illuminated by a beam of blue-green light(448nm) from argon laser.
• After exposure, enamel produces yellow flouorescence.
• These florescent images are captured using a color video camera & analysed in software
• Demineralized area appears- darker images against the florescent background of sound enamel
• Demineralized tissues absorb dyes like fluorol TGA, Sodium Fluorescence.

26. DIAGNOdent
• When the laser irradiates the tooth, the light is absorbed by organic and inorganic
substances present in the dental tissues, as well as by metabolites such as
bacterial porphyrins.
• These porphyrins showed some fluorescence after excitation by red light
• The Diagnodent is able to find cavities that other dental instruments can miss.
ADVANTAGES
90% success to diagnose pit and fissure caries.
 Non invasive and painless
 Safe, no X RAY Exposure

27. Optical Coherence Tomography
• Detect & diagnose very early stages of disease in teeth.
• Early demineralization, remineralization, recurrent caries, tooth and
restorative failures can be imaged and monitored in real time on
computer monitor.

28. Caries prevention
• 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 acid soluble compounds
• further reducing susceptibility to acid attack and caries.

29. Caries Removal and cavity preparation
• several laser types with similar wavelengths in the middle infrared
region of the electromagnetic spectrum are being used commonly for
cavity preparation and caries removal.
• Laser assisted cavity preparation
Lasers cut at a point of their tip
To be used with up and down motion
Rough edges that need hand instruments such as excavators to carry
away the ablation products
Removes smear layer
Lasers commonly used for cavity preparation are:CO2 Laser,Nd:YAG
Laser ,Er:YAG Laser

30. Restoration removal
• The Er: YAG laser is capable of removing cement, composite resin and
glass ionomer
• The Er: YAG laser is incapable of removing gold crowns, cast
restorations and ceramic materials
• Ultrashort and short pulsed lasers (USPLs) could be used an
alternative conservative means to remove restorative materials so as
to retain the protective dentin as much as possible.

31. Etching of enamel and dentin
• Laser etching has been evaluated as an alternative to the acid etching
of enamel and dentine.
• Lasers used for etching of enamel are:CO2 Laser,Nd:YAG Laser,Er:YAG
Laser
• The Er:YAG laser produces micro-explosions during hard tissue
ablation result in microscopic and macroscopic irregularities.
• These micro-irregularities make the enamel surface micro retentive
and they may offer a mechanism of adhesion without acid-etching.

32. Photopolymerization
• The argon laser at 488nm (blue) is used.
• as the wavelength of the light which is emitted by this laser is optimal
for the initiation of polymerization of the composite resins.
• The argon wavelength activates camphorquinone, a photoinitiator
that causes polymerisation of the resin composites.

33. Treatment of dentinal hypersensitivity
• This is a very common clinical issue and lasers have been used to reduce
dentin hypersensitivity by irradiation of dental hard tissues.
• for example : Er:YAG, Nd:YAG & He-Ne
• Mode of action:
• The Nd:YAG and CO 2 lasers have been thought to occlude the dentinal
tubules, thereby reduced dentin sensitivity.
• The Nd:YAG lasers can be combined with fluoride varnish to produce an
effective protocol for treating dentin hypersensitivity

34. Bleaching
• Lasers also used in bleaching of vital and non vital tooth
• The lasers is used to enhance the bleaching material
• To bleach teeth with lasers, a photo-activated bleaching agent is
applied, and a laser activates the agent, initiating a chemical reaction
that breaks down stains within the tooth enamel.

35. APPLICATIONS OF LASERS IN ENDODONTICS
I. VASCULAR VITALITY ASSESSMENT OF PULP
• Traditional vitality assessment methods such as heat, cold. and electric pulp testers
assess neural vitality and often alse-positive errors. As the histologic assessment of
pulpal status is not feasible clinically, a tool to assess the vascular flow of the pulp
would be very useful.
• Laser Doppler flowmetry (LDF) is an accurate method to assess the blood flow in a
microvascular system .

36. II. PULP CAPPING AND PULPOTOMY
• A more conservative form of pulp therapy in comparison to pulpectomy.
• Pulp capping is recommended when the exposure is 1.0 mm or less and especially when
the patient is young
• Pulpotomy is recommended in immature permanent teeth, where pulpectomy is not
advised.
• The most commonly used agents for both the procedures are calcium hydroxide and
mineral trioxide aggregate (MTA).
• The use of a laser in these procedures leads to a potentially bloodless field as the laser has
the ability to coagulate and seal small blood vessels.
• The laser tissue interactions make the treated wound surface sterile and also improve the
prognosis of the procedure.

37. • Melcer et al described the hemostatic effect of a CO2 laser on exposed pulp tissues in
dogs
• While Ebihara et al showed that Nd:YAG lasers facilitated pulpal healing after irradiation.
• In clinical trials, Moritz et al showed significant superior success rates with a CO2 laser-
aided pulp capping procedure.
• Various studies assessing the effect of CO₂ and Nd:YAG lasers on irradiated pulp found no
damage in tissues underlying the laser-ablated tissues.
• There was the presence of secondary dentin and a regular odontoblast layer.
• Wound healing of irradiated pulps seemed to be better than that of controls.

38. III. DISINFECTION OF ROOT CANALS
• The ability of bacterial pathogens to persist after shaping and cleaning is one of the main
reasons for endodontic failures.
• Studies have assessed the role of CO₂ and Nd:YAG lasers in root canals and found evidence
of dentinal tubule disinfection.
• Other lasers such as XeCl laser, Er:YSGG, Er:YAG, diode, Nd:YAP and argon have been used
for this purpose.
• The laser is delivered into the root canal system with the help of thin fiberoptics (200 µm)
as in the case of Nd:YAG, Er:YSGG, argon, and diode lasers
• A hollow tube is employed for this purpose in CO₂ and Er:YAG lasers.

39. • Goodis et al concluded that there are several limitations with the intracanal use of lasers.
The laser beam that is emitted from the tip of the fiberoptic is directed vertically
downward into the root canal and not laterally into the dentinal tubules which is further
compromised by the inherent curvature present in the root canals. Thus, it is not possible
to laser irradiate all the dimensions of the canal system completely.
The inadvertent transmission of the laser into the periradicular region while irradiating the
apical third of the root canal system is potentially dangerous in the areas around the
apices of teeth close to the mental and mandibular foramen
Laser has an effective method to kill microorganisms
Used in adjunct to traditional means of shaping and cleaning

40. IV. OBTURATION
• Thermoplasticized gutta-percha obturation systems are one of the most efficient
methods in achieving a fluid impervious seal.
• Softening of the gutta-percha has been attempted with various lasers.
• These include argon, CO₂, Nd:YAG, and Er:YAG.

41. V. APICAL SURGERY
• Apical surgery including apical resection is indicated when the previously performed
root canal therapy fails and nonsurgical means are inadequate to ensure the
complete removal of the pathologic process.
• The potential for using lasers is on the basis of the following observations:
Ability of lasers to coagulate and seal small blood vessels, thereby enabling a
bloodless surgical field
Sterilization of the surgical site
Potential of lasers (Er:YAG) to cut hard dental tissues without causing elaborate
thermal damage to the adjoining tissues

42. • Miserendino successfully treated an apical abscess using a CO2 laser. When this laser
was applied to patients having apicectomies
• Later Ebihara proved the ability of Er:YAG lasers to prepare apical retrograde cavities
similar to ultrasonic

43. LASERS HAZARDS
• Effect on Eyes
• Effect on skin and other tissues
• Environmental Hazards
• Electrical Hazards

44. Effect on Eyes
• Primary ocular injury which might result from a laser accident is retinal or coronal
damage.
• Retinal injury is possible with emission in the visible (400-780nm) and near
infrared(780-1400nm) wavelengths
• May cause "Scotoma" (Loss of vision in the path of visual field; Blind Spot)

45. Effect on skin and other tissues
• laser induced damage to skin and other non-target tissue(Oral
tissue)can result from thermal interaction of radiant energy with
tissue proteins
• Elevation of temperature above 370C causes cellular enzymes and
proteins destruction and coagulation necrosis which affect the
metabolic process
• Final result is Thermal necrosis of the tissues.

46. Environmental Hazards
• It is also called "Non-beam Hazards" as it is not resulting from direct
exposure to laser beam
• It involves the potential inhalation of air borne biohazards materials
that may be released as a result of surgical application of lasers
• This aerosols by-products may contain viruses, bacteria or chemicals
• Example: chemical hazards

47. Electrical hazards
• Most laser systems involve high current electrical supplies
• There are several hazards that may be potentially lethal such as:
-Electrical shock hazards
-Fire or explosion hazards.

48. Laser safety
• Personal Protective Equipment (PPE)
All people within dental treatment room must wear protective eye
wear including the patient.
Eyewear used specifically with particular wavelength of laser
radiation to prevent occular damage.
• TYPE OF EYE SHIELD TO BE USED
CO₂ laser - clear glass or plastic
Nd: YAG- goggles with green tint
Argon lasers: amber-orange colors

49. SKIN PROTECTION
• A double layer of saline saturated surgical towels, sponges, or lap
pads should be used to protect all exposed skin and mucous
membrane of the Patient outside the surgical field.
• Draping should be moistened time to time to prevent drying

50. CONTROL OF AIRBORNE CONTAMINATION
• Controlled by ventillation, evacuation and adequate suction.
• Laser filtration masks used to prevent air borne contamination
ELECTRICAL CONTROLS
• Operating area must be dry to avoid electrical hazard.
• Control panel and electrical power unit protected from splashing.

51. CONCLUSION
• Lasers represent a phenomenal change in dentistry, and in the future the
laser may be just as common place as the dental handpiece in the dental
office.
• Although much more scientific research- especially clinical research is
needed.
• When used efficaciously and ethically, lasers are an exceptional modality of
treatment for many clinical conditions that dentists treat on daily basis.
• But laser has never been the "magic wand" that many people have hoped
for. It has got its own limitations.
• However, the futures of dental laser are bright with some of the newest
ongoing researches.

52. REFERENCES
• GROSSMAN'S ENDODONTIC PRACTICE,14TH EDITION
• Sturdevant's ART AND SCIENCE OF OPERATIVE DENTISTRY Second
South Asia Edition
• Shirish kumar R, Srikumar GPV. Lasers and its applications in
Conservative dentistry- A Review. Annals and essence of dentistry
2017
• https://www.researchgate.net/publication/280094187_Laser_safety_
in_dental_practice

53. THANK YOU