Advantages of LED Light Curing Units Over Conventional Halogen Lights in Orthodontics

PRESENT DAY ORTHODONTICS
INVOLVES LESS OF WIRE BENDINGS, AND
STRESSES ON PRECISED BRACKET
POSITIONING FOR THE BETTER
TREATMENT OUTCOMES.
INTRODUCTION:
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The introduction of acid etch
bonding technique by Buonocore
(1955) has led dramatic changes in
the practice of orthodontics.

Though the chemically cured
composite was previously employed
for bracket bonding, it failed to provide
the orthodontist with ample time to
accurately position the brackets on the
enamel surface before polymerisation.

THIS PAPER PRESENTATION HEIGHLIGHTS THE
ADVANTAGES OF LIGHT EMMITING DIODE
COMPOSITE CURING LIGHT (LED) OVER COMMONLY
USED QUARTZ –TUNGSTEN-HALOGEN(QTH) LIGHTwww.indiandentalacademy.com

UV Light
(Health Hazardous, Out Dated)
Methods of light curing:

Absorption range of photo initiator is in the
blue region of the spectrum of light having
wavelengths between 400-500nm.www.indiandentalacademy.com

PLASMA -ARC
white light.
Electric current light arc between two electrodes
Ionizes surrounding Xenon gas Spark

LASER
LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION.
COLLIMATION
COHERENCE
MONOCHROMATIC IONIZED ARGON GAS
Production of
Laser.

Introduction of initiator like camphoroquinone
to the composite, entertained the orthodontists
to light cure it, and provided sufficient working
time before the material was set.
ADVANTAGES OF LIGHT CURING:

ADVANTAGES OF LIGHT CURING:
 Less toxic and less toxicity- as there is no
residual unpolymerized resin left out.
 Superior bond strength-When compared
to the direct bond adhesives.
 Light curing may be useful in situations
in which a quick set is required. For
example in placing an attachment on a
palatally impacted maxillary canine after
surgical uncovering.

Enough working time:
 Provides adequate time for placement of
difficult bracket positions such as on
premolars, enables the operator to recheck
the bracket position with the mouth mirror.
 Reduces the wastage of adhesive
material.
 Reduced flash helps in preventing plaque
accumulation.

QTH ASSEMBLY:
Fracture of light
carrying fibers
Cable vulnerable to
damage.
Decreased Power
output
EARLIER Q.T.H ASSEMBLY:

PRESENT DAY Q.T.H ASSEMBLY
More of
components
incorporated
in the hand-
piece itself.

Although halogen –light curing unit are the
most common type used to cure orthodontic
adhesives, this technology has several
drawbacks.
 Halogen bulbs have a limited effective
lifetime. Approximately 40-100Hrs.
 High temperatures produced cause a
gradual degradation of the halogen bulb,
reflector, filter reducing the intensity of
light output and thus the unit’s
effectiveness in curing.

 Improper maintenance.
 Delay in replacement of filter and halogen
bulb in regular basis.
 Complex assembly of the curing unit.
Many dental halogen light curing units do not
reach the maximum power output specified by
the manufacturers. Due to:

THE ADVENT OF “LED”:
Recent advances in technology like high
intensity Xenon arch light curing units, and
Laser light curing units, have their own
advantages of reducing curing time. These
devices however are more complex and more
costly compared to halogen and the recent LED
curing lights.
LED’s are semi-conducting materials that
transform current in to light of a specific
wavelength. They are much smaller and lighter
than the conventional bulb.www.indiandentalacademy.com

Design of LED:

Physics In Brief
P N
When the semiconductor material is forward
biased, energy difference in the P-Side and
N-side is created. This energy difference is
given up in the form of heat and photons.www.indiandentalacademy.com

GC E -
Light™

LCD Screen, Key board,
and Memory compartment.
Bar code sensor

Advantages of LED:
 LED’s are smaller in size compared to the
conventional bulbs.
 They provide shock resistance, as there is
no filament to be damaged.
 Low power consumption.

 Portable and cordless devices are
available.
 LED’s have lifetime more than 10,000Hrs
and experience little degradation of high
output over the time. (This is a distinct
advantage over halogen).
 LED’s require no filter to produce blue
visible light.

 The spectral output of this blue light
falls mainly within the absorption spectrum of
the camphoroquinone photo initiator (400-
500nm) of most dental composites supplied.
 Depth of curing is significantly greater
than that of the conventional halogen.
 Sleek design also provides the connection to
Internet and bar code sensor to avail the
information regarding the adhesive used.

Conclusion….
Although there is no significant differences in
compressive strength, flexural strength, or modulus
of elasticity were found between, composites
polymerized with halogen units and those cured
with LED units, further studies has to be conducted
to confirm the clinical bond strengths of LED cured
adhesives with various bracket bases.

Advantages of LED Light Curing Units Over Conventional Halogen Lights in Orthodontics

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Advantages of LED Light Curing Units Over Conventional Halogen Lights in Orthodontics