Pre adjusted edgewise appliance (2)

SEMINARSEMINAR
ONON
PRE ADJUSTED EDGEWISEPRE ADJUSTED EDGEWISE
APPLIANCEAPPLIANCE
www.indiandentalacademy.com

For over a 100 years Orthodontists
have followed a classic guideline given
by ANGLE.
– The mesiobuccal cusp of the upper
permanent molar should rest on the
mesiobuccal groove of the lower first
permanent molar.

Lawrence F. Andrews noted
that too many post treated
models had obvious
inadequacies, despite the
acceptable molar relationships
as described by Angle.

120 non orthodontic models were aquired from
1960 to 1964:
– Had never had any orthodontic treatment
– Pleasing in appearance
– Had a bite that looked generally correct
– Would not benefit from orthodontic treatment

These 120 models were compared with
1150 treated cases which he
collected from orthodontists all over
USA
– The best in treatment results and the
best in nature revealed the differences
between the right and wrong, which gave
birth to the SIX KEYS OF OPTIMAL
OCCLUSION

1. MOLAR RELATIONSHIP:
• When Angle described about molar
relationship he stated that The
mesiobuccal cusp of the upper first
permanent molar should rest on
mesiobuccal groove of the lower first
permanent molar.
• But non orthodontic models consistently
demonstrated that "Distal surface of the
distobuccal cusp of the upper first molar
occluded with the mesial surface of the
mesiobuccal cusp of the lower second
molar".

As seen in the diagram, closer
the distobuccal cusp of the
upper first molar occluded with
mesial surface of the
mesiobuccal cusp of the lower
second molar the better the
opportunity for normal
occlusion.

2. CROWN ANGULATION
The Mesiodistal tip of the crown.
• The degree of crown tip is the
angle between the long axis of the
crown & a line drawn 90 degrees
from occlusal plane.
• "Positive" when gingival portion is
distal to incisal portion.
• All the non orthodontic models had
a distal angulation of the gingival
portion of the crown.
– ie Positive reading

3. CROWN INCLINATION
Labiolingual or Buccolingual
inclination
• Formed by a line 90 degree to
occlusal plane & a line tangent to
bracket site.
• "Positive" when gingival portion
of tangent line is lingual.
"Negative" when gingival portion
of tangent line is labial or buccal

4. ROTATIONS
• The fourth key to normal
occlusion is that the teeth
should be free of rotations

5. TIGHT CONTACTS
• The fifth key is that the contact
points should be tight, ie no
spaces.
• Without exceptions contact points
in the non orthodontic models
were tight.

6. OCCLUSAL PLANE
• The planes of occlusion found in the
non orthodontic models ranged from
flat to slight curve of spee
• Andrew believes that a flat plane
should be the treatment goal as a form
of overtreatment since there is a
natural tendency for the curve of spee
to deepen with time.

Some landmarks givenSome landmarks given
by Andrew:by Andrew:

Andrews plane: The surface or plane on
which the mid transverse plane of every
crown in an arch will fall when teeth are
optimally positioned.

CLINICAL CROWN:
The amount of crown that can be
seen intraorally or with a study
cast

Facial Axis Of The
Clinical Crown (FACC):
• For all the teeth except molars, the
most prominent portion of the
central lobe on the facial surface of
each crown
• For molars, buccal groove that
separates the 2 large facial cusps.

Facial axis point (FA point)
• The point on the facial axis that separates the
gingival half of the clinical crown from the
occlusal half

MEASUREMENTSMEASUREMENTS

• After determining the 6 keys of
occlusions Andrew made certain
measurements in the non orthodontic
models which helped in the
development of a fully programmed
appliance.

• The measurement were made with
Protractor with adjustable readout
arms, Boley gauge & template of
circles.

The measurements made
are:
• Bracket area
• Vertical contour
• Angulation
• Inclination
• Maxillary molar offset
• Horizontal contour
• Facial prominence
• Curve of spee

The average findings for
the maxillary teeth are:
• Angulation:

• Inclination:

• Maxillary molar offset:

• Crown prominence:

Findings for the
mandibular teeth were:
• Angulation:

• No offset was needed for mandibular
molar because the middle &
mesiobuccal cusps are equal in
prominence.
• The curve of spee ranged from flat
to 2.5 mm.

• This study revealed consistencies in the
position, morphology & relative facial
prominence for the crown of each tooth
type with an arch except for incisor
inclination.
• The differences in the incisor inclination
were attributed to interjaw disharmony.
• Thus special considerations must be given
in the bracket design to correlate the
inclination of incisors with interjaw
relationship.

After making the measurements,
Andrew compared the 120 non-
orthodontic models with the treated
1150 models.
– ie best in nature vs best in treatment.
• Comparison were made particularly in
relation to the 6 keys of optimal
occlusion:

KEY I - Inter-arch
relationship:
• In 80% of the treated models, Distal
marginal ridge of maxillary I molar
did not occlude with mesial marginal
ridge of mandibular II molar.
Whereas in the non orthodontic
models, that relationship was optimal.

KEY II - Angulation:
• In 91 % of the treated models, The
crowns had one or more teeth whose
angulation differed from those of
optimal sample.

KEY III - Inclination:
Inter incisal FACC –
• In optimal- more than 180 degrees in
78%
• In treated - Less than 180 degrees in
81.5%

KEY IV - Rotation:
Rotations were evident in 67% of
post treated cases.
KEY V - Tight contacts:
Spaces were seen in 43% of post
treatment casts.
KEY VI - Curve of spee:
More than 2.5 mm in 56% of post
treatment casts.

• These evidence showed that only few
post treatment results met the six
key standards.
• So a quarter century of research
done by Andrew, devoted to naturally
optimal & treated occlusions has
yielded not only the six keys, but also
several principles fundamental to the
concept of fully programmed
appliance.

They are:
• Each normal tooth type is similar in
shape from one individual to another.
• The size of normal crowns within a
dentition has no effect on their
optimal angulation, inclination or
prominence of their facial surface.

• Most individuals have normal teeth
regardless of whether their occlusion is
flawed or optimal.
• Jaws must be normal & correctly related
to permit the teeth to be correctly
positioned & related.
• Dentitions with normal teeth and in jaws
that are or can be correctly related can be
brought to optimal occlusal standards.

NORMALITY –NORMALITY –
ABNORMALITY -ABNORMALITY -
OPTIMALITYOPTIMALITY

Abnormality:-
• Individuals with abnormal jaws &
teeth fall into this category.
– For example cleft palate, peg
laterals, etc.
• Treatment for this group always
needs a multi disciplinary
approach.

Naturally Optimal:-
• Group with normal teeth & jaws who
require no orthodontic treatment
– 120 non orthodontic models can be
included in this group.

Normal malocclusion:-
• Group with malocclusion which can be
treated to Optimal standards.
So both the naturally optimal & the
normal malocclusion fall under the
same category where they are
differentiated only through the
6 keys of optimal occlusion.

• When the normal tooth types are
similar in shape & require similar
positions for occlusions to be optimal,
why should a clinician spend so much
of their time making virtually
identical bends in identical wires
each time, striving to estimate the
requirement for effective tooth
guidance?

• It seemed feasible to design an appliance
that could be readily applied to normal
teeth with normal malocclusions & direct
them to optimal goals.
• When correctly sited, the brackets would
be designed to provide the guidance needed
with few wire bends.
• The development of this appliance resulted
partly from the 6 keys of optimal occlusion
and partly from detailed analysis of
limitations of edgewise appliance.

SHORTCOMINGS OFSHORTCOMINGS OF
EDGEWISEEDGEWISE
APPLIANCEAPPLIANCE

• The edgewise appliance designed by Angle
is " Non programmed" because of the
bilaterally symmetric design.
• If located on the F A point & the FACC &
used with unbent archwire, the brackets
would cause the Inclination of the facial
plane of each crown to be at 90 degrees to
occlusal plane,
• the occluso gingival positions of each
crown to be irregular,
• all crowns to have equal facial prominence
& angulation of the FACC of each crown to
be at 90 degree to the occlusal plane.

The major shortcomings of edgewise
appliance are:
• Bracket bases are perpendicular to bracket stem
• Bracket bases are not contoured
occlusogingivally
• Slots are not angulated
• Bracket stems are of equal faciolingual thickness
• Maxillary molar offset not built in.
• Bracket siting techniques are unsatisfactory.

1. Perpendicular bases
The base of the non -
programmed bracket is
perpendicular to the
stem. This feature can
cause problems for the
slot inclination &
occluso gingival position.

The effect when the
brackets are aligned
with unbent arch
wire. Dotted lines
represents the
required ideal
position.

2.Bases not contoured
occlusogingivally:
Occluso gingivally the
bracket is flat but the
facial surface of a crown
is curved. So when such a
bracket is being attached
to the crown it can
unintentionally be rocked
occlusally or gingivally.

There will be
irregular slot siting
in each arch caused
by vertically flat
based brackets.
Only a part of the
bracket will be
touching the crown.

• This diagram shows
the effect of the
irregularly placed
brackets. The
dotted line indicates
the optimal tooth
position required.

3. Slots not angulated:
The bracket slots of
the edgewise
brackets are non
angulated.

• When the vertical
components of the
brackets are sited
parallel to FACC & base
point sited at FA point,
the angle of the slot
vary to many different
angulation

• This diagram shows
the effects when the
brackets are placed
without slot
,angulation. Dotted
line indicates the ideal
requirement

4.Stems of equal
prominence:
• Distance between
bracket base &
center of slot is
same in each
brackets.

Therefore when the
brackets are
placed they
become as
irregular in the
facial prominence
as the crown

• With the unbent
archwire the facial
surface of each
crown becomes
equidistant from
the embrasure line,
which is
undesirable.

5.Maxillary molar offset
not built in:
• Since the maxillary molar
offset is not built in, the
midsagittal plane of the slot
is angular to the mid sagittal
plane of the crown.
• This will lead to rotational
effect of the molars.
• First order bends will have to
be installed into the archwire
to accommodate these
differences.

6. Unsatisfactory
landmarks:
Most of the authors & practitioners
seldom agreed about which landmarks
are best for bracket siting and each
required a different wire bending

INDIVIDUALIZEDINDIVIDUALIZED
BRACKETS-BRACKETS-
BRACKET SITING-BRACKET SITING-
SLOT SITINGSLOT SITING

• The concept of forming a fully
programmed appliance is that "when the
brackets were correctly sited on the
crowns, they would be as malpositioned as
the teeth.
• Such an appliance, when used with
progressively larger unbent archwires,
would flex each archwire only to a
diminishing extent that the slots & the
teeth remained incorrectly positioned,
until gradually the teeth, slots & wires
become aligned or STRAIGHT".

This involved,
• Whether bracket could be
individualized or customized
• Developing a scientific bracket
technique
• Determining where the slot must be
placed for each tooth type.

l. Individualized or customized
brackets:
• should we use a universal bracket system
for all the individuals or should we use
brackets that are customized for every
individual according to his tooth type &
treatment plan.

• If individualized or universal
brackets could produce satisfactory
results without wire bending for a
high percentage of patients, then it
would be the obvious choice.

2. Bracket siting:
A suitable bracket site has three criteria:
• there will not be any interference with
either gingiva or with opposing teeth
during occlusion.
• Angulation & inclination of the crown at
the bracket site will have a consistent
angular relationship to the plane of each
tooth's occlusal surface at all times & to
the occlusal plane of arch when the teeth
are optimally positioned.
• The middle of each bracket must share
the same plane or surface when the teeth
in an arch is optimally positioned.

• The site that meets
these requirements is
the area in immediate
proximity to Crown’s FA
point, which always falls
on the Andrew’s plane
when the teeth are
optimally positioned.

• Therefore the
ideal place for
bracket siting will
be the mid point of
FACC on the FA
point

3.Slot siting:
• Accurate bracket siting is of limited
value unless each bracket positions
it's slot with equal accuracy at a site
that would allow it to passively
receive an unbent archwire when
teeth are optimally positioned.

• Crown prominence from
embrasure line differ
from each tooth type,
with prominence in molar
being the maximum

• Therefore when an
appliance is designed, it
should be designed in such
a way that the distance
between the embrasure
line & slot target point
should be equal for all
teeth in an arch

Fully programmedFully programmed
standard bracketsstandard brackets

• The standard brackets are the one
which are designed to guide the teeth
without any wire bending.
• But translation or bodily movement
cannot be done with standard brackets.
• There is one standard bracket for each
tooth type, except incisors which has 3
and molar has 2.

The fully programmed standard
bracket include:
• Slot siting features
• Convenience features
• Auxiliary features

l. Slot siting features:
There are 8 slot siting features for
the standard brackets:

Feature 1:
Mid transverse plane of
slot, stem & the crown
must be in the same
plane.
In the diagram the mid
transverse plane is
represented in dotted
line

Feature 2 :
• The base of the
bracket for each tooth
type must have the
same inclination as the
facial plane of the
crown at FA point

Feature 3 :
• Each bracket's inclined
base must be Contoured
occluso gingivally to
match the curvature of
the crown.

• These 3 features eliminate the need
for 1 st & 2nd order bends to deal
with occlusogingival disharmony in
slot siting, 3 rd order bends for
inclination & other bends to deal with
inherent side effects of wire
bending.

Feature 4 :
Mid sagittal plane of
slot, stem & crown
must be the same.

Feature 5 :-
Plane of the bracket
base at it's base point
must be the same as
the facial plane of the
crown's FA point.

In all the crowns, this plane bears 90
degree to mid sagittal plane, whereas
in molars it is 100 degree due to
unequal facial prominence of molar
cusps.

Feature 6 :
• The base of the bracket
must be contoured to
match the mesiodistal
radius of the area of the
crown it is designed to fit.

Feature 7 :-
• The vertical components
of the bracket should be
parallel to one another.

• The bracket's horizontal components
are superior & inferior sides of the
bracket stems.
• When these components are sited
equidistant from the crown's gingva &
cusp tip, the base point of the bracket
will be in line with the F A point.

Feature 8 :
• Within an arch, all slot points must
have the same distance between
them & the crown's embrasure line.
• This factor eliminates the first
order wire bends to accommodate
for varying crown prominence.

2.Convenience features:
• Convenience features are the
designes incorporated into the
brackets that facilitates use by
orthodontists or promotes comfort
for the patients, but does not
contribute to the biological aspect of
treatment.

• Gingival tie wings are
designed to extend
laterally so that there
will not be any gingival
impingement

• The facial surface of the
incisor & canine brackets
are designed parallel to
their bases which in turn
are parallel to crown.
• This feature is incorporated
for Lip comfort

3. Auxillary features:
• Contribute to the biological aspect of
treatment, but not involved in slot
siting.
– Eg : Power arms, hooks, facebow tubes,
etc...

• The following are the prescriptions
for fully programmed standard
brackets:

MAXILLARY BRACKETS:
Class II – Angulation : 5 degrees
Inclination : 2 degrees
Prominence : 1.8 mm
Class I - Inclination : 7 degrees
Class III - Inclination : 12 degrees
Central incisors:

Lateral incisors:
Inclination : -2 degrees
Prominence : 2.25 mm
Class I - Inclination : 3 degrees
Class III - Inclination : 8 degrees

Angulation : 11 degrees
Prominence : 1.4 mm
Prominence : 1.5 mm
Canine:
First & Second Premolars

First & Second molars
Class I – Angulation : 5 degrees
Prominence : 1 mm
Offset : 10 degrees
Class II - Angulation : 0 degrees
NO offset

MANDIBULAR BRACKETS:
Inclination : 4 degrees
Prominence : 2.3 mm
Class I - Inclination : -1 degrees
Class III - Inclination : -6 degrees
Central and lateral incisors:

Canine:
Inclination : 4
degrees
Prominence : 2.3 mm

Premolars:
First Premolar:
Prominence : 1.6 mm
Second Premolar:

Molars:
First molar:
Prominence : 1 mm
Second molar:

• The incisors have 3 different types
because the inclination range for incisors
was greater than any teeth mainly because
of skeletal class I, class II & class III
discrepancies.
• For maxillary molars, 2 different types are
given for class I and
class II.

FULLY PROGRAMMEDFULLY PROGRAMMED
TRANSLATIONTRANSLATION
BRACKETSBRACKETS

The fully programmed translation
brackets have all the qualities of
standard brackets plus a Power arm
& three additional slot siting
features which helps in translation:
– Counter Rotation
– Counter Mesio distal tip
– Counter Bucco lingual tip

1.Counter rotation:
The slot siting feature counteracts the
tooth rotation during translation & then
overcorrects.
This feature when coupled with flexing of
the archwire counteracts the tooth
rotaion caused by the mesial or distal
force during mesial or distal movement

When a mesial force is
applied, the resultant
Rotation moment M is
counteracted by counter
moment CM produced by
rotated slot & flexed
archwire.

• When translation is
complete, the
rotated Slot
provides rotation
overcorrection.

3 categories of translation brackets are
there for counter rotation:
• Minimum : 2 degree slot
rotation
• Medium : 4 degree slot
rotation
• Maximum : 6 degree slot
rotation

2.Counter Mesiodistal tip:
• This is the slot siting feature that
counters mesial or distal tipping
during translation & overcorrects.

• Mesial slot length "a" is
less than the distance
between the bracket &
the tooth's center of
resistance.

• So when a mesial force
is applied to the
bracket, the counter
moment CM & moment
M are out of balance &
teeth ends up tipping

• Even when a power arm
is introduced, there is
imbalance since the
length of the power arm
is shorter than the
distance between the
center of resistance &
the bracket.

• When slot angulation is
increased, CM is equal to M
and results in Translation.
• This is because when both
power arm & slot are
activated, the Combined
width of both is equal to
the distance between the
slot & center of resistance.

3.Counter Buccolingual
tip:
• This slot siting feature is
only for maxillary molars
that counteracts the
Buccolingual tip during
translation & then
overcorrects.
• This is achieved by giving
more negative inclination
than the standard -9
degrees.

The altered values for various tooth types in
the fully programmed translation brackets:

MAXILLARY BRACKETS:
• Maxillary canine:
Medium translation:
Angulation: 14 [11 + counter M-D tip 3]
Rotation: 4
Inclination: - 7
Maximum translation:
Angulation: 15 [11 + counter M-D tip 4]
Rotation: 6
Inclination: - 7

First premolar:
• Angulation: 5 [2 +
counter M-D tip 3]
• Rotation: 4
• Inclination: - 7

Maxillary second premolar:
Minimum translation:
Angulation: O[ 2 + counter M-D tip of -2]
• Rotation: 2
Medium translation:
Angulation: -1 [ 2 + counter M-D tip of -3]
Rotation: 4
Maximum translation
Angulation: -2 [ 2 + counter M-D tip of -4]
Rotation: 6

Maxillary first & second
molars:
• Minimum translation:
• Angulation: 3[ 5 + counter M-D tip of -2]
Rotation: 12[10 + counter rotation 2]
Inclination: -13[-9 +counter buccolingual
Tip of-4]
• Medium translation:
• Angulation: 2[ 5 + counter M-D tip of -3]
Rotation: 14 [10+4]
• Inclination: -14[-9 + -5]
• Maximum translation:
• Angulation: 1[ 5 + counter M-D tip of-4]
Rotation: 16[10 + 6]
• Inclination: -15 [-9 + -6]

Mandibular canine:
Medium translation:
• Angulation: 8[ 5 + counter M-D tip of 3]
Rotation: 4[ 0 + Counter rotation 4]
Inclination: -11
• Angulation: 9[ 5 + counter M-D tip of 4]
Rotation: 6[0 + 6]
• Inclination: -11

First premolar:
Angulation: 5[2 + counter M-D tip 3]
Rotation: 4[0 + 4]
Inclination: -17

Second premolar:
• Angulation: 0[2 + counter M-D tip -2]
Rotation: 2[ 0+2]
Medium translation:
Angulation: -1[2 + counter M-D tip -3]
Rotation: [ 0+4]
Inclination: -22
Angulation: -2[2 + counter M-D tip-4]
Rotation: 6[0 + 6]
Inclination: -22

Mandibular first molar
• Angulation: 0[2 + counter M-D tip -2] Rotation:
2
• Angulation: -1 [ 2 + counter M-D tip of -3]
Rotation: 4
• Angulation: -2[2 + counter M-D tip -4]
Rotation: 4
• Inclination: -30www.indiandentalacademy.com

Mandibular second molar:
• Angulation: 0[2 + counter M-D tip -2] Rotation: 2
• Angulation: -1 [2 + counter M-D tip -3] Rotation: 4
• Angulation: -2[2 + counter M-D tip -4] Rotation: 6

FULLY PROGRAMMEDFULLY PROGRAMMED
APPLIANCEAPPLIANCE
PRESCIRPTI0NPRESCIRPTI0N

• Selecting the most suitable set of
straight wire brackets for each
tooth in an arch begins with deciding
which teeth must be moved
mesiodistally & how far they must be
moved.
• The next step is to determine
whether these teeth should be
tipped or translated.

The teeth to be translated will need
translation brackets
- Minimum, medium or maximum
depending upon the teeth to be
moved.
The other teeth may need only
standard brackets.

• To make these distinctions, a measure of
the discrepancy between the size of the
teeth & space available for them within
the existing arch is to be calculated.
• Then add or subtract the amount of space
that would result from any proposed
changes which can be achieved without
mesial or distal movement.
• The result would give the interim core
discrepancy - ICD.

• Andrew gave 12 possibilities for
maxillary arch & 11 for the
mandibular arch.
• Depending upon the value of lCD, he
made 3 types of natural divisions-
Spaced, classic & crowded.
• The prescriptions were extraction or
non extraction depending upon the
discrepancy.

The following prescriptions were given
by Andrew for each situations:-
- S indicates standard brackets,
- 1 indicated minimum translation
brackets,
- 2 indicates medium &
- 3 indicated maximum translation
brackets.

TYPE SPACED:
• 3 Subtypes - All
non extraction
Subtype 0 to 4 mm
Advance molars & premolars
0 to 2 mm per side

• Subtype 5 to 8 mm
• Advance molars &
premolars 2.5 mm
to 5 mm per side

Subtype 9 to 14 mm
premolars
4.5 to 7 mm per side

TYPE CLASSIC [zero space]
• 1 Subtype - Non extraction
• 1 Alternative - extraction
Subtype - Non extraction
Some tooth repositioning is required
Angulation, inclination, rotation, Tipping,
intrusion or extrusion.
Alternate - extraction of first
premolars

TYPE CROWDED:
• 6 extractions & 1 non extraction.
Subtype 0 to 6 - non extraction
Molars, premolars & canines tipped
distally to neutralize ICD

Alternate - exactly 6 mm.
• Extraction of first
premolars
• Translate molars 3 mm
mesially
• Premolar & canines 3 mm
distally

Subtype 7 to 8mm
premolars
premolars
• Retract canines

Subtype - 9 to 10mm
premolars

Subtype -11 to 13mm
premolars

Subtype 14 mm
• Extraction of
first premolars
• Retract only the
canines

Alternate 14 mm
• Only for Maxillary arch.
• When class II molar
relation is left unchanged

Even though this series of brackets given
by Andrew, were used initially, they are
not used now because of the following
disadvantages:

• Undesirable force vectors, especially tip
of the canines are increased in the early
stages of treatment.
• When light forces are used, the
overcorrection built into extraction series
brackets is not necessary.
• There is a need for substantially increased
band & bracket inventory, or else a need to
weld brackets at the chairside with
inherent possibilities of inaccuracy.

• It is always better to have a
universal system of bracket
prescription instead of some 12
prescriptions.
• These disadvantages gave rise to lot
of modifications in the prescriptions
in the following years.

Pre adjusted edgewise appliance (2)

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