Edgewise technique

Evolution of technique
Primary edgewise
*as described by Angle in 1929
*fully banded technique-gold bands ,soldered soft
brackets
*flat ideal arch wire -to provide normal occlusion
*original arch was of .022 X .028 in.gold wire
*to be adapted passively to all malocclusion
*if space had to be made ,loops are soldered onto
main arch
*if space closure required , spurs & tie backs used
*involves all the teeth to be brought under control
so,treatment should be initiated after eruption of
canine & premolar
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Secondary edgewise
*to avoid the making archwires passive
*use of round wires in the initial stages
*gold was replaced by a more rigid alloy
*frequency of extractions increased
*bands with prewelded brackets
*in 1940s round .045in.tubes were also soldered on
the upper molars for a face bow

Tertiary edgewise or Tweed’s edgewise
*stressed on the importance of anchorage
preparation
*advocated the use of cl. III elastics & extraoral
traction
*vigorous forces were now employed
*space closure was done by simple vertical or
horizontal open loops bent into the archwire or by
push coil tie -backs

Tweed’s philosophy
Based on the following :-
a) Practically all malocclusions are characterized by a
forward adjustment of teeth in relation to their basal
bones --- this is due to deficiency between the
basal bone & tooth material
b) The establishment & maintenance of a stable
anchorage should be the initial concern of the
operator & is a fundamental factor in successful
orthodontic treatment
c) Teeth like inanimate objects ,best resist the force of
displacement when tipped to the angulation that
offers the most advantageous mechanical against
the pull of dislodging forces .they are best stabilized
when they overlie the basal bonewww.indiandentalacademy.com

d)Teeth are most readily moved when their property &
power of mechanical resistance has been primarily
reduced
e) All forces emanating from an orthodontic appliance
must be synchronized if they are to be most effective
in the mass stabilization or the mass movement of
teeth
f) Nature being an expert mechanic herself ,offers
biologic compensations & adjustments when teeth
are placed in position of mechanical advantage for
force resistance
g) The dental units will best resist forward displacement
when the buccal teeth are in mild distal axial position
& the incisor teeth are in mild lingual axial inclination
& overlying a substantial bony foundation
“placing the incisors on the ridge”

Every malocclusion exemplifies a denture that is
stabilized by balanced muscular forces & this
muscular balance must be preserved in treatment if
stability in the end result is to be accomplished
( Strang & Thompson )

Facial types
Tweed divided the facial types into following
types:-
TYPE A :-Maxilla & mandible show forward &
downward growth
-ANB angle remains the same
-Prognosis is good
-Treatment not indicated during mixed
dentition if ANB angle does not exceed 4.5
TYPE A Subdivision:- ANB angle greater than 4.5

TYBE B :- Maxilla & mandible grow downward &
forward with maxilla growing more rapidly
than mandible
- When ANB angle is 4.5 or less
prognosis is favorable
- Extraoral appliances should be
used immediately after extraction
TYBE B Subdivision :- ANB is large & found to
be increasing
-Undesirable growth trend,
treatment long & difficult

TYPE C :- -Maxilla & mandible grow downward &
forward with mandible growing more than
maxilla
-ANB increasing
-Growth is favourable & treatment is
facilitated by growth
TYPE C Subdivision :- mandible grows more than
maxilla but only to a little extent

Tweed’s Diagnostic facial triangle
Basis for diagnosis & treatment planning
Consists of the following :-
1) FMA –the Frankfort mandibular plane
angle
2) IMPA –the incisor mandibular plane
angle
3) FMIA – the Frankfort mandibular incisor
angle

Angle FMA IMPA FMIA
Visual 25 90 65
cephalometric 24.57 86.93 68.20
Range 15 – 36 76 – 99 56 – 80
For successful treatment triangle should be attainable
Aim should be to obtain:-
FMIA of 70° – 75° ( when FMA = 20 )
FMIA of 65° ( when FMA = 30)
When FMA is less than 20° -
FMIA should be more than 70° & IMPA should not
exceed 94°

He showed that in well balanced faces – IMPA was
90°±5°
For every degree that FMA was in excess of 25° .the
incisor mandibular angle IMPA would have to be
decreased by 1°
Treatment objectives :-
Facial balance & harmony
Stability of the post treatment dentition
Healthy oral tissues
Efficient mastication

Anchorage preparation
Stable anchorage –important to prevent forward movement of
mandibular denture when cl.II intermaxillary force is applied
On histological basis Brodie (1937) believes that the strongest
anchorage is provided by stable fixation of teeth –to allow as
little movement as possible
Tweed – anchor teeth best resist the dislodging forces when their
vertical axes are parallel to the direction which offers the most
advantageous mechanical resistance against the pull of
dislodging forces

Strongest anchorage is provided by tipping back the crowns of the
teeth so that they will have a disto-axial inclination that will resist
a forward pull
First & most important step in treatment - Anchorage preparation
If anchorage preparation is not done -the action of intermaxillary
elastics cause elevation of terminal molars & depression of
mandibular incisors.
Thus,canting of occlusal plane,
increase in FMA ,
point B drops downward & backward ,
entire mandibular denture is tipped & displaced forward into
protrusion

Classification of anchorage preparation
First degree- minimal anchorage preparation,
-applicable to all malocclusion with ANB =0
to 4 ,
-total discrepancy does not exceed 10
mm,
-terminal molars must be uprighted & or
maintained in an upright position to
prevent their being elongated when cl. II
intermaxillary force is used .

Second degree-for malocclusions with ANB more than
0° to 4°
-facial esthetics requires to move point
B anteriorly & point A posteriorly i,e
cl. II cases
-usually accompanied by type A, type A
subdiv.,type B & type B subdiv.
-degree of distal tipping of mandibular
molars more severe than first degree
anch.prep. –they should be tipped so
that their distal marginal ridges are at
gum level

Third degree –severe discrepancy cases –14-20mm or
more
-ANB does not exceed 5°
-generally cl.I bimaxillary cases
-sliding jigs are necessary
-2nd
,1st
molars & 2nd
premolar must be
tipped to such an extent that the distal
marginal ridges are below the gum level
also called total anchorage preparation

Ideal arch form-
orthodontic arch is the form
which moulds the dental
arch with every bend
reflected in the position of
the teeth
Angle “ if an archwire is placed
in brackets with uniform slot
depths,it must take the form
of the outline of the buccal &
labial surfaces of the teeth”
Unique alignment of upper
lateral incisor –thinner labio-
lingually & short crown
length

Contact points lie on an ellipsoid curve
There is a straight line from canine to mesio buccal
cusp of first molar,but the beyond that it curves
inward progressively
Bonwill-Hawley diagram is widely used to decide arch
form

Bonwill-Hawley diagram is widely used to decide arch
form
General pattern –decided by studying the original
models & of the muscle behavior of the patient rather
than based upon widths of teeth themselves

Three orders of tooth movement
Movements necessary to bring the teeth into the line
of occlusion –first ,second ,third orders
First order bends-
-horizontal change relative to the line of occlusion
-also called in -out bends
-do not alter the horizontal plane of the wire
-the action & reaction of these bends affect
expansion or contraction
-used to move individual teeth
-the interaction of bends can affect the third order
position of the teeth if expansionary forces are used

Second order bends
-represent a vertical
change
-also called
tip/angulation
-used to tip posterior
teeth mesially or
distally-may be
tip back or tip forward
bends

Third order bends
-torsional change (with the line of occlusion
serving as axis)
-also called torque or inclination movement
-used to obtain axial changes in the bucco-
lingual or
labio-lingual root & crown axis on one or
more teeth
There are two types of torque
1)passive
2)active

Tweed summarised his philosophy on which his
appliance therapy is based:-
i) Normal occlusion is best maintained with the mandibular
incisors in their normal axial inclination when related to the F-H
plane approx. 65°(FMIA)
ii) The ultimate in balance & harmony of facial esthetics is
achieved only when the mandibular incisors are positioned over
the basal bone
iii) The normal relationship of the mandibular incisors to their
basal bone is the most reliable guide in diagnosis & treatment
of cl. I ,cl. II &bimaxillary protrusion cases and also in
attainment of balance & harmony of facial profile & permanence
of tooth position

General plan of treatment
Treatment divided into 3 phases:-
a)Anchorage preparation
b)Distal enmasse movement of maxillary buccal
segments
c)Establishing correct denture form & completing
treatment objectives
Anchorage preparation involves:-
1) placing mandibular incisors upright
2) changing axial inclinations of the maxillary incisors,
to make them less resistance to distal movement
3) changing the axial inclinations of buccal teeth to a
more distal axial inclination

Extaction treatment
a)Leveling of arches
.o18 in. wire with molar
stops /tie back spurs at
the molar tube & distal tip
back bends in posteriors
cl. III elastics & headgear
Working arches U/L .019 X .
025 in. with mild second
order bends
Uprighting of canines-horizontal
loops soldered mesial to
second premolars

Uprighting of canines-horizontal loops soldered mesial
to second premolars
Canine bracket is not engaged in the wire

Anchorage preparation
.021 X .028 stabilization wire
with mild second order
bends in upper arch
.019 X .028 in working wire in
lower arch with tip back
bends & sliding jigs to bear
pressure on 2nd
premolar
bracket
cl. III elastics are worn
Once anchorage preparation
done – reverse the
mechanics
cl. II elastics are worn

Distal movements of canines & incisors
U/L .019 X .025 archwires with second order bends &
open coil springs compressed mesial to canines are
inserted
cl. III elastics aid in distal movement of mandibular canine
Headgear applied to upper arch aids in upper canine retraction

Incisor retraction
Using .019 X .025 archwire with closed Bull loop distal
to canine –activated 1mm every 3 wks.
Mandibular incisors are retracted to an FMIA of 65° in
cl.I cases & 70° in cl.II cases
Maxillary incisor retraction completed –heavier .021 X .
027 in.wire ,reduced posterior to lateral incisors &
passed free of canine
Strong lingual root torque in upper anteriors for bodily
retraction

Stops are soldered 3mm mesial
to 2nd
premolar brackets
Coil springs compressed
against the stops

Correction of cl. II relationship
Now , mand.arch -.021 X .028 in.
max.arch -.019 X .025 in. with accentuated tip
back bends
Mand. arch tied back to receive cl. II elastics –continued
till normal cusp relation is achieved

Completion procedure
Final space closure & detailed tooth positioning -.019
X .026 in. max. & mand.ideal arches ,coil springs
compressed mesial to 2nd
molar tubes until space
closure is completed
Vertical elastics are used for seating cusps if bite is
open

cl. II div.1 –non-extraction treatment
 Preparation of anchorage in the lower arch
 Preparation of anchorage in the upper arch
 Distal enmasse movement of maxillary arch
 Detailed positioning of teeth
ANCHORAGE PREPARATION
Initial leveling & alignment - .016 or .018 round wires
Working arch wire .019 X .025 in. with coordinated tip
back bends
cl. III intermaxillary hooks soldered mesial to canine
Loop stops are made mesial to molar tubes but the
archwire not tied to molar anchor teeth

Upper arch is stabilized -.021 X .028 in.wire with mild tip
back bends
Intermediate pull headgear mesial to canine is used to
augment the anchorage - min. 14 hrs./day
Distal pull by headgear –twice as much as mesial pull
on the arch by cl. III elastics
During day – light cl. III
During night –heavy cl. III
Distal tip back bends increased slightly every 2-3 wks.

Stabilization arch -.021 X .028 in. wire with same
degree of tip back bends as in working archwire
Passive in mandibular incisor region
Total time required – aprrox. 4 mons.
Anchorage preparation in upper arch
Excessive inclination of the proclined upper incisors is
reduced by using .018 in. round wire
Important – this provides unfavorable stationary
anchorage & resist distal / lingual movement of the
teeth
Heavy stabilization wire with mild second order bends is
placed

Enmasse distal movement of maxillary arch
Upper arch wire -.021 X .028 in. reduced distal to
lateral incisors
Mild lingual crown torque if incisors are proclined
Intermaxillary hooks on archwire –patient put on cl. II
elastics
Watch out for mandibular anchorage –any signs of
mobility ,increase the tip back bends
After 3 wks. –tip back bends in the maxillary arch are
increased ,stronger elastic force is applied until
normal relation of teeth attained
Mild palatal root torque in anteriors
Continue till incisors in edge –edge relation & posteriors
in good occlusion

Detailed positioning of teeth
Proper seating of cusps is obtained by fitting correlated
U & L ideal arches carrying vertical spurs for vertical
elastics between them

Bimaxillary dentoalveolar protrusion
Two types of cases:-
1)Axial inclinations of all the teeth in the arch inclined
abnormally forward (both in cl.I & cl. II cases ),
Dental arches are more or less well aligned
2) Axial inclinations of teeth in buccal segments fairly
upright ,irregular & crowded
Steps in treatment:-
 Anchorage preparation in lower arch
 Anchorage preparation in upper arch
 Extraction of four premolars
 Multiple loops .016 in. archwire U/L used for
alignment
 Space closure done using looped archwirewww.indiandentalacademy.com

Treatment of cl.III malocclusion
Objective:-
1)To correct abnormal buccolingual inclination of all
posterior teeth in both arches
2)Constrict the mandibular arch which is too broad
3)Expand the maxillary arch which is too narrow
4)Move maxillary arch forward enmasse ,using
mandibular arch as stationary anchorage

Steps in treatment
Initial .016 in. round wires
After 2 wks. ,.021X .027 in. U/L ideal arches
Brass wire hooks mesial to canine
Mandibular archwire is bent considerably narrower than the ideal &
torque is placed in the buccal segment
Step forward 2nd
order bends placed in maxillary posterior segment
(direct opp.of tip back bends)
Intermaxillary elastics from lingual of maxillary molar to hook
mesial to mandibular canine
When cross bite is corrected –archwires are reshaped to the ideal
Treatment continued until the maxillary teeth have moved forward
enmasse into occlusion with teeth in mandibular arch.

Edgewise technique

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