ORTHODONTICS

1. LASER AND ORTHODONTICS: THE MEETING POINT
BY: DR AGHIMIEN AO.
Orthodontic unit, Dept. of preventive dentistry.
University Of Benin Dental School
Nigeria

2. OUTLINE
Introduction/Definition
Historical Perspective Of Laser
Physics Of Laser
Basic Component Of A Laser Machine
Characteristics Of Laser
Classification Of Laser
Tissue Interaction Of Laser
Safety Precaution During Laser Irradiation
Application Of Laser In Orthodontics
Direct Orthodontic Clinical Application
Adjunctive Orthodontic Clinical Application
Laboratory Orthodontic Laser Application
Conclusion
References

3. INTRODUCTION/DEFINITION
LASER is an acronym for “ light amplification by stimulated emission of
radiation".
Its use has enabled orthodontist to address the challenges associated
with some of the conventional methods of orthodontic treatment.
These include direct chair side clinical orthodontic procedures,
adjunctive orthodontic and laboratory procedures.

4. HISTORICAL PERSPECTIVE OF LASER
• The theoretical basis of LASER
was based on the theory of
wavelength (Zur Theorie der
Strahlung) postulated by Albert
Einstein in 1917.

5. Schawlow and Town discovered
LASER however, it was not until
1960 that Maiman of Hughes
research laboratories built the
first working LASER….Ruby Laser.
Schawlow was Town’s brother in-
law
Schawlow

6. In 1985, Paghidiwala, tested the erbium-doped solid state
laser (Er:YAG) on dental hard tissue.

7. THE PHYSICS OF LASER
The term Laser is self explanatory. It describes the whole process of
light generation.
It involves transforming various forms of energy into a specialized form
of ‘’optical’’ energy.
Specialized materials are used to transform this various of energy.
Though the initial energy are of low wavelength they are further
amplified.

8. Basic component parts of LASER
1. Active/gain/laser medium:
Gas-argon, CO2
Liquid-
Semi-conductor (diode)-Gallium, arsenide, aluminium, indium
Solid-state (solid crystal or glass matrix)- Nd:YAG, Er:YAG
Stimulation of the laser medium causes one of its electrons to drop
from a higher energy state (Q1) to a lower energy state (Q2), releasing
light energy – a process referred to as stimulated emission of
radiation.

9. The stimulated emission of photon by an excited atom, which triggers the release of a
subsequent photon is responsible for the generation of coherant, monochromatic and
collimated form of light or LASER.

10. 2. Pump/energy source: F-A-C-E
Flash light
Arc light
Chemical reaction
Electrical discharge
The amplified light from the laser machine is what is referred to as the
laser beam.

11. 3. Optical resonator/cavity:
Laser produced by the active medium is bounce back and forth through
the laser cavity with two mirrors at both ends. The proximal mirror
have some reflective property which allow some laser to escape to
target tissue.
4. Delivery system: dependent on the wavelength of the laser. It
could be
 quartz fiber-optic
 flexible hollow waveguide
 an articulated arm (incorporating mirrors)
 a hand-piece containing the laser unit

12. Characteristics of laser beam
a. Monochromatic: one color of energy hence, a single wavelength
b. Directional: collimation…..intensely focused energy beam which
interacts with the target tissue. They do not diverge
c. Coherent: wavelength is of same size and shape

13. Classification of laser
1) According to the mode of emission
2) According to Power
3) According to the Emitting Material i.e. laser medium
4) According to tissue acted upon
5) According to clinical uses
6) According to mode of transmission
7) According to thermal interactions of tissue
8) According to their harmful effect

14. 1. Based on the mode of emission:
a. fractionating- periodic alternations of the laser energy being on and
off, similar to a blinking light.
b. Continuous wave- laser energy is emitted continuously as long as
the laser is activated—and produces constant tissue interaction
c. Pulsed- Free-running pulse emission occurs with very short bursts
of laser energy due to a flash lamp pumping mechanism

15. 2. According to Power
a. High power: These lasers increase tissue kinetic energy and produce
heat. As a result, they leave their therapeutic effects through thermal
interactions.
b. Medium power: These lasers leave their therapeutic effects without
producing significant heat.
c. Low power: These lasers have no thermal effect on tissues and
produce a reaction in cells through light, called photo-biostimulation or
photo-biochemical reaction. Output power of these lasers is less than
250 mW, e.g. diode laser.

16. 3. Based on the Emitting Material
a. Gas lasers—Argon, CO2 lasers
b. Solid state lasers—Nd:YAG, Er:YAG, Ho: YAG
c. Semiconductors—Diode lasers.

17. 4. According to tissue acted upon
a. Soft tissue laser ( LLLT):
low energy wavelength, cuts tissue by coagulation, vapourization and
carbonization
Seal capillaries and nerve endings
Resultant painless post-operative procedures
Soft tissue heal faster
b. Hard tissue laser:
longer wavelength, cuts the tissue by ablation,
Cut into bone and teeth
Prepare tooth surfaces before bonding
repair certain worn down dental restorations.

18. 5. Classification of lasers based on their clinical uses
Laser type Wavelength Main current clinical uses
Argon 488, 514.5 nm Curing, soft tissue desensitization
Diode 800-830, Soft tissue, periodontics
950-1010 nm
Nd: YAG 1064 nm Soft tissue, periodontics,
desensitization, analgesia, tooth
whitening, and endodontics
Er: YSGG 2.79 μm (2,790nm) Hard tissue
Er: YAG 2.94 μm (2,940nm) Hard tissue
CO2 10.6 μm (10,600nm Soft tissue, desensitization
Key:
Nd: YAG: Neodymium: yttrium-aluminium-garnet, Er: YSGG: Erbium doped yttrium
scandium gallium garnet

19. 6. According to mode of transmission
a. Glass fibre-optic system-CO2 Laser
b. Mirror system: Nd: YAG, Argon, He-Ne laser, Diode lasers

20. 7. Classification based on thermal interactions of tissue
Temperature (°C) Tissue effects
a. 42-45 Hyperthermia (transient)
b. >65 Desiccation, protein denaturation
and coagulation
c. 70-90 Tissue welding
d. >100 Vaporization
e. >200 Carbonization and charring

21. 8. Based on harmful effect of laser
Class I: Low-powered lasers that are safe to view
Class IIa: low-powered visible lasers.
Do not cause damage unless one looks directly along the
beam for longer than 1,000 s
Class IIb:
Low-powered visible lasers.
Dangerous when viewed along the beam for longer than 0.25 s

22. Class IIIa: These are medium-powered lasers that are not dangerous
when viewed for less than0.25 s
Class IIIb: These are medium-powered lasers that are dangerous when
viewed directly along the beam for any length of time
Class IV: These are dangerous high-powered lasers that can cause
damage to the skin and eyes. Even the reflected or radiated beams are
dangerous. Most of the lasers used for medical and dental purposes are
in this category.

23. Wavelengths of dental laser

24. Tissue interaction of laser
Transmission and reflection have no
effect on the target tissue.
There is undesirable transfer of
energy to non-target tissue when
scattering occurs.
Of great importance is the
absorption
Laser require chromophore to
absorb it. Intra-orally they include
melanin, water and haemoglobin.

25. Precautions before and during irradiation:-
a) Glasses for eye protection.
b) Prevent inadvertent irradiation.
c) Protect patients throat, oral tissues.
d) Use wet gauze packs to avoid reflection from shinny metal surfaces.
e) Ensure adequate high speed evacuation.

26. Laser selection in orthodontics
Factors that guide selection
1. Procedure specificity
2. Ease of operation
3. Portability
4. Cost
The most common lasers used in dentistry today are the CO2 laser, the
Nd:YAG laser, the erbium lasers (Er:YAG and Er,Cr:YSGG). However, the
large size and cost of CO2 and Nd:YAG laser makes it difficult to use in
orthodontics.

27. Why orthodontist prefer the diode
laser
A. No risk of damage to adjacent tooth structure
B. Excellent hemostasis
C. Dry-field operation
D. Light contact of the fiber tip with tissue
E. Proprioceptive feedback
F. Portability
Its wavelengths is easily absorbed by melanin (soft tissue pigmentation)
and hemoglobin, and poorly absorbed by enamel and water.

28. Laser application in orthodontics
A. DIRECT CLINICAL APPLICATION
1. Acceleration of tooth movement
2. Bone remodeling,
3. Enamel etching prior to bonding
4. Debonding of ceramic brackets
5. Pain reduction during orthodontic force application
6. Prevention of enamel demineralization.

29. B. ADJUNCTIVE CLINICAL APPLICATION
1. Gingivectomy
2. Gingivoplasty
3. Frenectomy
4. Soft tissue exposure prior to traction

30. LASER ANALGESIA DURING ORTHODONTIC FORCE APPLICATION
Commonly used lasers are the low-level laser therapy (LLLT) GaAlAs
diode laser, localised CO2 laser
Prevent temperature rise above 36.5°C in target tissue.
Has non-thermal and bio-stimulatory effects.
Affect the synthesis, release and metabolism of serotonin
acetylcholine centrally and prostaglandins and histamines peripherally.
NB: some studies in the literature have shown that LLLT offers no
significant pain reduction after separation or placement of arch wires.

31. LASER ACCELERATED TOOTH MOVEMENT
Induction of the receptor activator of the nuclear factor-kappa B
(RANK) and RANKL (Fujita et al., 2008).
Stimulating osteoclastic and osteoblastic cell proliferation and
function
Commonly used laser is the GaAlAs diode laser

32. LASER-ASSISTED BONE
REGENERATION
Two principles
a. Cellular proliferation
b. Cellular differentiation into committed precursors
This could possibly inhibits relapse and reduces the retention
period by accelerating bone regeneration in the mid-palatal
suture after RME.
LLLT has positive effects on wound healing through acceleration
of bone regeneration and stimulation of trabecular osteoid tissue
formation.

33. LASER ENAMEL ETCHING DURING BONDING PROCEDURES
Conventional Method
Acid-etching with 37%phosphoric acid leaves a rough micro-fissured
surface
Shortcomings:
a. Susceptibility of the enamel to long term acid attack in the future
b. High prevalence of white spot lesion among orthodontic patient.
Poly-acrylic acid etching and sand blasting were also investigated to
overcome these shortcomings.

34. Mechanism of laser-etching
There is thermal induced changes of the enamel.
Resultant localised melting of the hydroxyl-apatite and ablation of
enamel.
Laser etching produces a fractured, uneven surface and open dentin
tubules, which is ideal for adhesion.

35. Advantages of laser etching
 Painless
 Nil vibration hence, no smear layer
 Acid resistant surface- by altering the Ca-PO3 ratio, reduces the
carbonate-to-phosphate ratio, reduces water and organic component
content thereby forming more stable and less acid soluble
compounds. This reduce acid attack is very promising to the
orthodontist.
 Time saving: Nil water spraying, nil drying.
Er-YAG, Nd:YAG, Cr:YSGG.
NB: some researchers believe that Nd-YAG etching produce lower bond
strength

36. Laser curing of light-cured materials
Conventional methods include the use of light emitting diode (LED), plasma
arc, quartz-tungsten-halogen (QTH).
SHORTCOMINGS:
a. QTH light intensity depreciate overtime which becomes less optimal for
curing
b. light produced by QTH devices has a wide wavelength range, including
both ultraviolet and visible lights necessitating the use of special filters
to select blue light for emission.
c. Longer curing period of between 20-40 sec for QTH and LED however,
with plasma arc this was reduced to about 2-4 sec but with resultant
reduced bond strength.

37. Advantages of laser-assisted curing
The peak of argon laser emission (488nm) matches well with the
photo-initiator, camphorquinone
Curing is 4 times faster
Possible higher bond strength
Lower pump chamber temperature increase with less thermal risk of
pulp damage.
NB: High cost of argon laser has made it impossible for routine usage.
The portability and affordability has made diode lasers better choice.

38. Laser bonding to porcelain
37% phosphoric acid not suitable for bonding to porcelain surface
Conventional 9.6% hydrofluoric acid when used stand the risk of
damaging teeth and adjacent soft tissue.
However, with laser:
No risk of potential gingival burn
Acceptable bond strength
Upon bracket debonding no need to re-polish the porcelain
Shorter etching time.
Nd:YAG can be used.

39. Laser-assisted acid resistance of
enamel to prevent white spot lesion
Orthodontic patients on fixed therapy are faced with the risk of enamel
decalcification
Conventional preventive measures:
Daily fluoride mouth rinse: Possible burn out
Use of fluoride releasing composite resin conventional RMGic: these
adhesives result in lower bond strength.
Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP).

40. Mechanism of laser-assisted acid resistance
Surface melting
Partial fusion and recrystallization of enamel prism thereby sealin g
up the enamel surfaces
Changes in enamel organic matrix
Resultant effects include:
Decreased enamel demineralization
Decreased loss of tooth structure
reduced threshold pH at which dissolution occurred by about a factor
of five.
NB: The treatment is carried out the area susceptible to caries.

41. Laser-assisted ceramic bracket
debonding
Complications of conventional ceramic brackets debonding;
From using debonding pliers
Enamel fracture: because the debonding strength of ceramic bracket
is greater than that of enamel. Ceramic brackets also have low
fracture toughness
Enamel cracks
Ingestion of brackets fragments: ceramic brackets are brittle
Damaged to the eye: as the bracket fractures and scatters
From using ultrasonic and electro-thermal devices
Damage to pulp from the heat generated

42. Laser debonding
Ceramic brackets absorbs the wavelength thereby softening the resin.
Advantages:
No enamel tear nil bracket failure
Nil pain
Less debonding force
Less chair side time

43. LASER MINOR SURGERIES
ADVANTAGES
1. Coagulates blood vessels
2. Seals lymphatic
3. Sterilizes the wound during ablation, reducing the risk of blood-borne
transmission of disease
4. Maintains a clear and clean surgical field.
5. Topical anesthesia commonly used
6. Less post-operation discomfort
7. Minimal swelling
8. Suturing not required
9. Few analgesia required
10. Less wound contraction, less scaring

44. Disadvantages
Not cost effective
Less tactile strength especially for non-contact laser e.g. erbium laser
Tissue desiccation
Poor wound healing

45. Adjunctive clinical applications
1. Gingivectomy:
Indications
a. For Establishing Tooth Proportionality before Bracket Placement
b. Crown lengthening
c. Crown height asymmetries
Advantages
a. Because the soft-tissue laser seals the incision as it is made, brackets can
be placed immediately after the procedure, and healing of the tissue
follows.
b. Ideal bracket positioning is achieved

46. 2. Gingivoplasty: to recontour the gingival when there is inflammation
3. Frenectomy: in managing mid-line diastema
4. Fibrotomy (pericision): less invasive than the conventional
circumferential supracrestal fibrotomy (CSF) hence, easily accepted by
patients.
5. Exposure of TAD’s
6. Exposure of unerupted teeth

47. Laboratory procedures
Laser welding:
Conventional methods include:
Pressure welding
Spot welding
With laser welding there is greater mechanical strength.

48. Others
1. Laser scanning: for soft-tissue scanning and a valuable tool with
ease of application and creation of 3D images.
2. Laser fluorescence: Laser light induced fluorescence can be used as
a diagnostic method for detection of enamel caries at an early
stage. This is invaluable for detecting white spot lesions

49. In summary…laser in orthodontics

50. Conclusion
The speculations, hypothesis and theories of yesterday for an excellent
tomorrow is available today.
If it must become our routine orthodontic tool for tomorrow we must
be ready to accept and develop on the knowledge today.

51. References
1. Fujita S, Yamaguchi M, Utsunomiya T, Yamamoto H, Kasai K. Low-energy laser stimulates tooth
movement velocity via expression of RANK and RANKL. Orthod Craniofac Res 2008;11:143-55.
2. Avinash KM, Juhi A, Preeti B, Mohd YA. LASERS: Revolutionary Advancement in Orthodontics. J.
Dent. Sci and Oral Rehab. 2014;5(3):133-138.
3. Fornaini C, Merigo E, Vescovi P, Lagori G, Rocca JP. Use of laser in orthodontics: applications and
perspectives. Laser Therapy 22.2: 115-124
4. Sehrish A, Rayees A, Mehnaz R. Recent advances in laser technology. IOSR-JDMS. 2015:83-87
5. Nalcaci R, Cokakoglu S. Lasers in orthodontics. Eur J Dent 2013;7:119-25.
6. Arjun Karra, Mohammadi Begum, “Lasers in orthodontics,” Int J Contemp Dent Med Rev, vol. 2014,
Article ID 041014, 2014.