department_of_orthodontics_.

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INTRODUCTION TO FIXED APPLIANCE.
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Appliances that are fixed or fitted onto to the
teeth by the operator & cannot be removed by the
patient at will are called fixed appliance.
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Advantages:Can do complex tooth movement
Better control over tooth movement
Better control of anchorage & extraoral force can
be used in conjunction with fixed Eg: Head gears.
Doesnot require pt co-operation
Better aligning, detailing & finishing of the
occlusion
Disadvantages:Difficult to maintain good oral hygiene
More time consuming to fix & adjust
More conspicous and not esthetically pleasing
Requires special training of the operator
Patient visit the orthodontist at regular intervals
Comparatively expensive
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Various tooth movement brought about by
fixed appliances: Tipping
Bodily movement
Torquing
Uprighting
Rotations
Extrusion & Intrusion
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Tipping:- Here the crown moves in the
direction of force around a fulcrum in the
apical region of the root. Root apex moves
in opposite direction.
Bodily movement:- Equal movement of both
the crowns as well as the root in the same
direction.
Torquing:- Root movement in the labial or
lingual direction
Uprighting:- refers to mesio-distal
movement of the roots.
Extrusion & Intrusion:- refer to Vertical
movements of teeth along their long axis.
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History:The irregular position of teeth has been a problem for some
individuals since the beginning of time. Attempts to correct
this disorder go back to at least 1000BC.
1850 AD:- The first texts which systematically described
orthodontics appeared. Dr. Norman Kingsley was among the
first to use extraoral force to correct protruding teeth.
1890's AD:- Dr. Edward Angle "The father of Modern
Orthodontist'' was one of the first to emphasize occlusion in
the natural dentition. His interest in creating proper occlusion
in natural teeth created the specialty of orthodontist.
1900'AD:- With a concept of normal occlusion established by
Angle, orthodontist began to enable into the treatment of
malocclusion and not just the straightening of teeth.
1940'AD:- Cephalometerics radiographs were developed
which allowed the orthodontist to see how he bones of the
face contributed to malocclusion.
1970's AD:- Surgical technique developed which allowed oral
surgeons to perform surgery on patients who did not have
the ability to grow any longer.
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PRESENT ORTHODOMTICS:Uses a combination of extraoral forces to align teeth as well
as growth modification, surgery and extractions to
accomplish 3 goals.
Create the best occlusal relationship
Create acceptable facial esthetics
Create a stable occlusal result
DIFFERENT TECHNIQUES:The edgewise arch mechanism was Edward.H.Angles last and
greatest contribution to orthodontics.
The edgewise mechanism was designed to allow the
orthodontist to place the teeth into Angles concept of the
'line' of occlusion' defined as
''the line with which in form and position according to type,
the teeth must be in harmony if in normal occlusion.''
The evolution of this appliance and its recommended use can
be traced by following Angle's earlier works in appliance
design.
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ANGLE E Arch:
The simple E.ARCH which was used
primarily for tipping tooth crowns into
proper alignment, was the first in a long
series of Angle appliances. It was the first
to utilize stationary anchorage or bodily
control of first permanent molar teeth,
which were fitted with clamp bands. The
expansion arch was threaded to form a
traction screw arrangement attached to the
buccal of the anchor bands.
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The shortcomings of this approach became apparent to Angle
and he set about to device a means for more individual tooth
control. The pin and tube appliance by which the tooth roots
could be brought into proper axial relationship with the
crowns was a logical consquence. This was the first appliance
developed by angle that employed a bracket and used bands
on most of teeth. However despite it potential versatility,
difficulties were encountered with the actual manipulation of
the technique. Noyes commented that the pin and tube
appliance demanded such a high degree to skill to obtain
proper parallelism b/w the tubes & pins on the archwire that
few would be able to master the technique. Soldering &
unsoldering the pins at each adjustment was time consuming
and tedious. The appliance design made rotational
adjustments most difficult
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RIBBON ARCH APPLIANCE
The ribbon arch appliance introduced in 1915, was the next step in
the evolution of took alignment devices. It was actually the first
bracket as such to be used in an orthodontic appliance. It obviously
was a great step forward and in fact was a testament to the genius
of Angle insofar as the light wire technique of P. Raymound Begg of
Australia was built around this bracket. Begg and his co-workers
modified it only slightly. Both the Begg technique and the ribbon
arch technique require a locking pin for attachment of the archwire
to the bracket.
One of the main advantages of the ribbon arch appliance is that it
alones rotations to be readily accomplished. It also offers control of
buccolingual and labiolingual movements and both incisogingival
and occlusogingival movements are possible. The primary short
using of the ribbon arch appliance as originally developed was that
it made mesiodistal axial movements difficult to obtain. This
inability to achieve distal tipping movements of buccal segments
proved to be a serious handicap. Experience showed, furthermore
that the size of the ribbon arch itself did not provide the stability
thought necessary for stabilization or anchorage of the posterior
teeth. It should be noted that the original ribbon arch technique , as
developed by angle, was non-extraction oriented, in
contradistinction to the current usage of the ribbon arch bracket in
the Begg technique for both extraction and non-extraction
treatment.
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To overcome the deficiency of ribbon arch
Angle re-oriented the slot from vertical to
horizontal and inserted a rectangular wire,
rotated 900 to the orientation it had with
ribbon arch thus the name edge wise.
Preajusted edge wire (straight wire) – tip
and torque pre adjusted into wire.
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Raymond Begg received his training in orthodontics from Angle school
during the early 1900's the later returned to Australia in 1925 and practised
the edgewise technique. In the mean time Begg modified the Angle's ribbon
arch technique & introduced the Begg light wire differential force technique.
This appliance used the concept of differential force and tipping of teeth
rather than bodily movement. Begg appliance used high strength stainless
steel wire along with a number of auxillaries and springs to achieve the
desired tooth movement.
Treatment using Begg appliance is carried out in 3 different stages.
Stage one
- concerned with alignment, correction of crowding,
rotation correction, closure of anterior space and
achieving an edge – edge anterior bite .
Stage two
- Remaining extraction spaces are closed while
maintaining the previous corrections that have been
achieved.
Final Stage
- Uprighting and torquing is carried out to achieve normal
axial inclination of teeth.
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The straight wire technique is a recent modification
of the edgewise appliance introduced by
L.F.Andrews in the 1970's, based on his 6 keys to
normal occlusion. The basic concept was to
programme the bracket to have the first, second
and third order components so that the wire need
not have any complex bending as required in
edgewise appliance.Hence it is called Preadjusted
Edgewise Appliance. This technique made it
possible to substantially reduce the wire bending
required and also enabled good finishing of
cases.
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The lingual orthodontic technique was
introduced in 1976 by Craven Kurz. In this
technique the brackets are placed on the
palatal & lingual aspects of the teeth. Both
the edgewise and Begg principles can be
employed in treatment. Lingual appliances
are highly esthetic but have the
disadvantage of poor access and difficulty
in speech and maintaining the oral hygiene.
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The origin of orthodontic bonding dates to 1955 with the
publication of the original work by Buonocore who
demonstrated improved retention of methyl methacrylate
resins to enamel after 30sec application of 85%
orthophosphoric acid. In 1965 Newman reported on the use
of epoxy adhesives for the bonding of orthodontic
attachments to teeth. He was the first to use the acid etch
technique for this purpose. The last major development was
by Bowens who developed a bisGMA resin that proved to the
more stable than the previous resins. Currently available
bonding resins are based on Bowen's bisGMA resin. .
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Advantage:More esthetically acceptable.
Easier oral hygiene maintenance.
Partially erupted teeth can also be bonded.
Risk of caries is eliminated.
Proximal stripping is possible.
Less chair side time.
Proximal areas are available for restoration.
Disadvantage:It is a weak attachment
Risk of enamel demineralization
Enamel fracture can occur during debonding
More boding failure
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Types:Direct Bonding
Indirect Bonding
Steps:Polish the teeth with pumice powder to remove pellicle.
Etching 35-50% of buffered orthophosphoric acid for 30 –
50sec.
Wash the etchant
We can visudisc a frosty white appearance
Apply sealent on the tooth surface.
Hold the bracket in reverse tweezer, apply sealant and
adhesive over the bracket and selfcure or light cure it.
Position the bracket and press to remove the excess material
which has to be removed to avoid white spots on tooth.
After sometime apply arch wire
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Banding involves the use of thin stainless steel
strips called bands that are pinched tightly around
the teeth and then cemented to the teeth. The
stainless steel tape is available in different width
and thickness to suit different teeth. While the
molar band material is wider and stiffer, the
anterior band material is relatively thinner and
narrower in width. The outer surface of the band
material is smooth and glassy while the inner
surface is comparatively rough and dull, so as to
aid in retention of the cement.
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Indications for banding
In cases of posterior teeth banded
attachments resists occlusal forces.
It is preferable to band a tooth that requires
buccal as well as lingual attachments.
Band are better likely to resist heavy forces,
as in the case of extraoral devices such as
head gears.
Although it is possible the band attachments
on teeth that have porcelain or gold
restorations or crowns banding is preferred in
these cases.
It is preferable to use banded attachments
whenever they are likely to contact the
opposing dentition when the joins are closed.
Steps in banding
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Separation of teeth
Tight contacts should be broken using tooth separators prior to
band pinching.
Different type of separators used are:
Ring separator
Dumbbell separator
Brass wire separator
Keslings spring separator.
Selection of band material
Pinching of the band
using a band pinching pliers, the band is tightly drawn around the
tooth to form a ring. The bent portion is spot welded and the
gingival margins of the bank are trimmed to conform to the contour
of the gingival margin
Fixing the attachment.
Attachments include brackets for the anterior teeth and buccal or
molar tubes for the posterior teeth.
Cementation of the band.
During cementation, adequate moisture control is necessary by
means of saliva ejectors and cotton roles. Cements used
are
zincpolycarboxylate, zincphosphate, glass ionomer cement etc.
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COMPONENTS
ACTIVE COMPONENTS
Arch wires
Springs
Elastics
Separators
PASSIVE COMENTS
Bands
Brackets
Buccal Tubes
Lingual Attachments
Lock pins
Ligature wire
ARCH WIRES:They can bring about various tooth movements through the
medium of brackets and buccal tubes which act as handles on
the teeth.
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Ideal Requirements
Spring back:- measures how far a wire can be deflected with
out causing permanent deformation.
Stiffness:Formability:- Wires exhibit high formability so as to bend the
arch wires into disired configuration as coils,loops etc.
Resilience:- The amount of force the wire can withstand
before permanent deformation.
Bicompatibility environmental stability
Joinability
Friction
Classification of arch wire
I Based on material used
Gold and Gold allays
Stainless steel
Nickel titanium alloys
Beta titanium
Cobalt chromium nickel alloys
Optiflex arch wires.
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II
Based on cross section
Round
Square
Rectangular
Multiistranded.
Gold & gold alloys :- Prior to 1940, gold was extensively used
in the manufacture of orthodontic wire.
Stainless Steel:- Austenitic stainless steel referred to as 18/8
is used to make orthodontic arch wire.
Nickel Titanium alloys:- (Nitinol) have super elasticity and
but reduced formability and cannot be soldered or welded.
Beta:- titanium:- (T.M.A wires)
Cobalt chromium nickel alloy(Elgiloy)
Optiflex arch wires:- made of clear optical fibers and are
highly esthetic with high resilience
Multithreaded arch wires:- can be trusted or coaxial in form
and have increased flexibility.
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Begg called it as engine of appliance, made up of latex rubber.
Types:Class I – Molar to canine (intraarch)
Class II – lower molar to upper canine
Class III upper molar to lower canine
Box elastic – to correct antr open bite
Cross elastic – used in begg's appliaice
Transpalatal elastic – to correct molar crossbite
Elastic chains – Available as long chains if interconnected rings used in
closure of space
Elastic thread – made up if corex of latex rubber and surrounded by a sleave
of woven silk used to derotate of tooth.
Elastic Modules – Made of 2 elastic rings separated to close space and for
derotation of teeth
Ligating ring's – Archwires can be secured to the brockets using small
electrometric rings called lighting rings.
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Uprighting springs : Used to move root
is a mesial or distal direction
Torquing Springs : Move root in a
lingual or palatal creation
Open coil springs : Compressed b/o
two teeth to open up space b/o them.
Closed coil springs : stretched b/w
teeth to close space
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BANDS
The attachment like brackets and molar
tubes are soldered or welded over these
bands which are cemented in position
around the teeth.
Band sizes
thickness width
(inches) (inches)
Incisor
0.003
0.125
Canine
0.003
0.150
Premolar
0.004
0.150
Molar
0.005
0.180
0.180
Act as handless the transmit the force from the active components
to the teeth. Brackets have one or more slots that accept the arch
wire.
Edgwise type of brackets
Has horizontal slot facing labially. Also called as rectangular slots as
they accept wires of rectangular cross section with larger dimension
being horizontal
Ribbon arch brackets:
Has vertical slot facing the Occlusal or gingival direction. Slot is
narrow m-d and are used in begg fixed appliance.
Weldable and bondable brackets
Brackets that are bonded directly over the enamel and those that
are weldable or soldered over the bands.
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Metallic brackets
Can be recycled and sterilized, resist deformation
and fracture.But unesthetic and cause staining of
teeth.
Ceramic brackets
Are dimensionally stable and do not distort in oral
cavity but are brittle and fracture.
Plastic brackets:
Available in tooth coloured or transparent forms
but undergo discoloration and their slots tend to
distort.
Buccal Tubes:
Can be round or rectangular in cross section. May
have sometimes double or triple tubes. These
additional tubes are for additional arch wires and
for face bow insertion.
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Are fixed on lingual aspect and are required
for engaging elastics
Eg: lingual buttons
Lingal cleats,
Eyelets
Ball end look
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Are soft stainless steel wires of 0.009-0.011 inches diameter and
are used to secure the arch wire to the brackets usually necessary in
edgewise type of brackets.
Lock pins:
Used to secure the arch wire to brackets with vertical slots such as
ribbon arch brackets and usually made of brass.
Conclusion
Fixed appliance is thus an extragenous method to correct both
skeletal and dental malocclusion but though being uncomfortable to
patient can bring esthetic and functional satisfaction.
Reference:
GRABER
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