4. E ARCH
Basic design : Had rigid framework
to which teeth has been tied so that
they could be expanded to arch form
dictated by the appliance
Bands were placed only on molar
teeth and a heavy labial archwire
extended around the arch
End of the wire was threaded and a
small nut placed on the threaded
portion of the arch allowed archwire
to be advanced so that arch
perimeter increased
5.
6. PIN AND TUBE APPLIANCE
First appliance that employed a
bracket and used bands on most
of the teeth
Angle placed bands on other
teeth apart from molars and used
a vertical tube on each tooth into
which a soldered pin from a
smaller archwire was placed
Tooth movement was
accomplished by repositioning the
individual pins at each
appointment
7. RIBBON ARCH APPLIANCE
Angle modified the tube on each tooth to provide
a vertically positioned rectangular slot behind the
tube
A ribbon arch of 10 X 20 gold wire was placed
into the slot and held with pins
Was an immediate success primarily because the
archwire was small enough to have good spring
qualities and was quite efficient in aligning
malposed teeth
Poor control of root position
8.
9. BEGGS APPLIANCE
Begg’s adaptation took three forms
He replaced the precious metal ribbon arch with
high strength 16 mil stainless steel wire ( 1930 )
He retained the original ribbon arch bracket but
turned it upside down so that the bracket slot
pointed gingivally rather than occlusally
He added auxiliary springs appliance for control
of root position
10.
11.
12. EDGEWISE APPLIANCE
Angle re oriented the slot from vertical to
horizontal and inserted a rectangular wire rotated
90 degrees to the orientation it had with the ribbon
arch
Dimensions of the slot were altered to 22 x 28
mils and a 22 x 28 precious metal wire was used
These dimensions arrived after excessive
experimentation did not allow excellent control of
crown and root position in all three planes of
space
13. Rectangular brackets with gingival and
occlusal wings were soldered to bands
This appliance soon became the most popular
appliance in the U.S., as it was the first to
move teeth in all three planes of space
simultaneously,
14.
15.
16. PREADJUSTED EDGEWISE/
STRAIGHTWIRE APPLIANCE
From his extensive measurements, Andrews
determined the average tip and torque angles and
in/out dimensions of the labial surface of each tooth
relative to a flat labial arch wire plane, coined the
“Andrews’ Plane”
When each pre adjusted bracket was precisely
positioned at the midpoint of each tooth’s facial axis,
the brackets formed the Straight-Wire Appliance
He also developed a series of extraction brackets
which include anti-tip and anti rotation components not
found in the Standard SWA prescription
60. Failure at 3 interfaces
Between the bracket base and
bonding material (preferred site)
Within the bonding material
itself
Between the bonding material
and enamel surface
69. DISADVANTAGES
Staining and discoloration
Poor dimensional stability
Friction between plastic bracket and archwire
Using a metal slot can solve the 2nd and 3rd
problems
72. DISADVANTAGES
Brittle/easily fractureds
Loss of parts of brackets
Cracking when torque forces are applied
Increased friction(can be reduced by
incorporating a metal slot)
Wear of opposing teeth
Enamel damage during debonding
73. TYPES OF BRACKETS
METAL
Stainless steel
Co Cr
Titanium
Gold
CERAMIC
PLASTIC
LINGUAL
SELF LIGATING
81. Stiffness: Resistance to deformation
Formability: Amount of permanent deformation
that a wire can withstand before failing
Resilience: Energy storage capacity of wire,
combination of strength and springiness
Range: Distance the wire behaves elastically
before it deforms
Strength= Stiffness x Range
84. PRECIOUS METALS
Used in the first half of twentieth century
Gold alloy with platinum, palladium, copper were
used
Advantages
• High ductility
• Inert nature and corrosion resistance - so did not
form toxic products with saliva
• Variable stiffness- by heat treatment
• High resilience
• Ease of soldering
85. Disadvantages
Elastic force delivery much less
Greater cost compared to other base metal
wires
Have minimal use currently
86. STAINLESS STEEL
A typical formulation for orthodontic use
is“18-8” SS, containing approximately 18%
chromium and 8% nickel. Also contains Fe,
and C
The properties can be controlled by cold
working and annealing
87. Properties
High stiffness
Better strength
Corrosion resistance
Can be soldered and welded for the fabrication
of complex appliances
Malleable and ductile
Low springback
Less surface friction
Space closure favourable due to stiffness and
low surface friction
88. COBALT CHROMIUM
Developed during the 1950s as Elgiloy
Composition:
Cobalt – 40-45% –
Chromium – 15-22% –
Nickel – for strength and ductility –
Iron, molybdenum, tungsten and titanium to
form stable carbides and enhance hardenability.
89. NICKEL TITANIUM
Useful during the initial orthodontic alignment.
Ni 55%, Ti 45%
Can apply a light force over a large range of
activations so used in Alignment and levelling
stage of treatment
Nitinol (Ni, nickel; Ti, titanium; NOL, Naval
Ordnance Laboratory) – first Nickel Titanium alloy
developed for space program
90. Shape memory
Superelasticity
Good springback
More range
More formability
Martensite at low temperature and high
pressure/stress
91. Shape memory
Ability of material to remember its original
shape after being plastically deformed while in
the martensitic form.Certain shape is set at an
elevated temperature , above martensite-
asutenite transition temperature. When the
alloy is cooled it can be transitionally
deformed Heated enough to regain the
austenitic structure Original shape is restored
Thermal reaction
92. Superelasticity
Reversible strain wire can withstand due to
martensite- austenitic phase transition
Transition to martensitic in response to
stress./Mechanical reaction
96. Offers a highly desirable combination of
strength, springiness and formability.
Modulus of elasticity less than SS but more
than Ni Ti
Excellent choice for auxiliary springs and for
intermediate and finishing archwires
Especially rectangular wires for the late
stages of edgewise treatment
102. CATENARY CURVE
Catenary Curve
Premolar-canine-incisor segment of the arch
very nicely for most individuals
For all patients, the fit is not as good
103. BRADER ARCHFORM
Based on a trifocal ellipse.
The anterior segment closely approximates
the anterior segment of a catenary curve
Gradually constricts posteriorly
More closely approximate the normal position
of the second and third molars
Notas do Editor
High strength
Low stiffness
High range
Low formability
