Buliding treatment mechanics though bracket positioning

BUILDING TREATMENT
MECHANICS THROUGH
BRACKET POSITIONING
www.indiandentalacademy.com

I. Introduction
II. Various appliance system discussed
1. ALEXANDER DISCIPLINE.
2. ROTH.(Few variations suggested by
Bennet and mclaghlin)
3. M.B.T.
4. LINGUAL APPLIANCE.
5. BEGG APPLIANCE.
I. Various gauges used in bracket
positioning.
II. Common errors in bracket positioning.
III.Special considerations in bracket
positioning.
IV.Conclusion.
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In the past, the best results were achieved
by orthodontists who were the the best
wire benders.
The emphasis has changed since the
development of the pre-adjusted appliance
by Andrews.
The best results in the future will be
achieved by those orthodontists who are
best at accurate bracket positioning.
Introduction:

Orthodontic treatment is based upon
specific force applications to the
dentition, the maxilla and the mandible.
In order to obtain these forces in a fixed
appliance, orthodontic brackets are
attached to the teeth.

The brackets themselves produce no
force. They are merely handles for
attachment of the force producing agents.
However, brackets can effect the
directions of the force vectors when
torque, angulations, and in/out are built in
to the brackets.

He found that millimeter measurement
system for bracket positioning as used with
standard edgewise, was not satisfactory for
the pre-adjusted appliance.
Andrews measured 120 non orthodontic
normal models to establish the TIP,
TORQUE and IN/OUT measurements built
in to the pre-adjusted appliance .

Using that system for both large and small teeth
would not provide a consistent reference point for
expression of the three dimensional forces on each
tooth. For example, a bracket placed 5mm from
the incisal edge of an upper central incisor would
be located at a different position on the crown
for large versus small teeth.
This in turn would create a small difference in
the torque position and the thickness position of
the tooth.

Andrews therefore rightly chose the centre
of clinical crown as a horizontal reference
point, so that the expression of TORQUE
and IN/OUT compensation would be
consistent for both large and small teeth.

Andrews used the long axis of the clinical
crown a vertical reference, which was the
center of the middle developmental lobe of
the crowns from central incisor to second
bicuspid, and buccal grove of the first and
second molar crowns.

FIVE FACTORS WHICH
DEFINE ANY BRACKET
SYSTEM:
1. Bracket Type.
2. Placement Positions.
3. Angulations.
4. Torque.
5. In/Outs. www.indiandentalacademy.com

Following are the some Appliance
systems which have incorporated
bracket positioning variations in order
to achieve better treatment outcomes.
1.ALEXANDER DISCIPLINE.
2.ROTH.
3.M.B.T.
4.LINGUAL APPLIANCE.
5.BEGG APPLIANCE.www.indiandentalacademy.com

The system evolved around five factors related to
brackets:
 Bracket selection,
 Bracket height,
 Bracket angulations,
 Bracket torque,
 Bracket in-out.
The Concept of the Vari Simplex Discipline
1. ALEXANDER DISCIPLINE.

 Bracket selection
Each tooth has a particular
bracket that is most effective.
Twin Brackets (Diamond brackets)
Are used on large, flat-surfaced teeth—
maxillary central and lateral incisors. The
Diamond bracket is designed so that all the
horizontal lines are placed parallel to the
incisal edge of the tooth, and the rhomboid
design makes it possible to align the vertical
lines parallel to the long axis of the tooth.www.indiandentalacademy.com

The flat surfaces of maxillary centrals and
laterals permit full archwire engagement in
the twin brackets. The accessibility of
these teeth negates the usual difficulty in
tying twin brackets. Also, twin brackets on
the incisors allow 5-6mm of inter-bracket
width, which is sufficient for flexibility,
rotational control, and torquing ability.

Lang Brackets
Lang brackets were invented by
Dr. Howard Lang. Brackets with
Diamond design are placed on
large, round-surfaced teeth at the
corners of the arch such as
maxillary and mandibular cuspids Lang bracket.
A. When a Lewis or Steiner
bracket is completely tied
into a cuspid, there is a
tendency to flatten the
curvature of the archwire.
B. A Lang bracket avoids this
effect, while retaining the
rotation wing capability. A B

Lewis Brackets
It is prefered to use Lewis brackets on large,
round-surfaced teeth that are not at the curve of
the arch such as maxillary and mandibular
bicuspids and on small, flat-surfaced teeth such as
mandibular incisors.Using the basic Lewis design
with a wedge shape, which puts the tie wing close
to the tooth occlusally and far out gingivally. This
makes it easy to tie, to use as a hook for elastics,
and to keep clean.

Removing the interfering wing of Lewis bracket
on badly rotated tooth permits proper bracket
placement.

Other Attachments
Twin brackets with a convertible
sheath are used on maxillary and
mandibular first molars, which are
usually banded. The convertible
sheath is easily removed when second
molars are banded, converting the
attachment to a bracket.

Headgear tubes are placed occlusally on the
maxillary first molars.This position makes it
easier to see and to use them; it minimizes
food traps, oral hygiene problems, and
gingival impingement; and it eliminates
blockage when omega stops are used.
Twin bracket with convertible sheath on molar.www.indiandentalacademy.com

Bicuspid bracket height is the key (X on the chart below)
because its clinical crown height is so variable. Its normal
height is 4.5mm. The other bracket heights are calculated in
relation to X, as shown on the chart.
Maxillary Arch
Centrals X
Laterals X – 0.5mm
Cuspids X + 0.5mm
Bicuspids X
1st Molars X – 0.5mm
2nd Molars X – 1.0mm
Mandibular Arch
Centrals X – 0.5mm
Laterals X – 0.5mm
Cuspids X + 0.5mm
Bicuspids X
1st Molars X – 0.5mm

Bracket Height
Placing a bracket higher or lower affects the
amount of torque and angulations, and the
incisogingival position of the tooth. Obviously,
bracket height will vary to fit the clinical
crowns. Cusp tips vary, and that is a
consideration. If incisors have chipped edges
or mam-melons, the teeth should be
recontoured or the bracket height adjusted
before bracket placement.

An obvious deviation from these
measurements would be in an open bite
case. Since the treatment plan would be
to intrude the posterior teeth and extrude
the anterior teeth , increase the bracket
height on anterior teeth by 0.5mm and
decrease the bracket height on posterior
teeth by 0.5mm.

When banding bicuspids in extraction
cases, the band is seated more gingivally
on the side toward the extraction site,
Hence it is not necessary to angulate the
bracket. This provides adequate tip of
the bicuspid root into the extraction site,
which, combined with the 6° tip in the
cuspid, is sufficient to parallel the roots.

The mandibular first molars have a -
6° tipback built in to promote leveling
and to gain arch length. There is 0°
angulation on the mandibular second
molars, since these teeth rarely need to
be uprighted excessively. If necessary,
they can be uprighted by placing a
tipback bend in the archwire when
bending the omega stop.

FEW APPLIANCE SYSTEMS
WITH VARIATIONS IN
BRACKET PLACEMENT.

 Roth in 1975 evaluated the pre-
adjusted bracket system after he had used
it for 5 years.
 In 1981 he modified the appliance by
altering the amount of pre-adjustment built
into the brackets.
 His objectives were to have the teeth in
overcorrected positions at the end of
treatment when unbent, full-sized wires
were used.
2.ROTH

Some slight variations in bracket
placement are recommended for
the Roth set up; thus a flat
unbent rectangular, full sized
wire can be used as a finishing
wire rather than one with reverse
and compensating curves.

The key in determining bracket
height is the canines and
premolars(second premolars in
extraction case).
Ideally the center of brackets should
be placed at the maximum convexity
of the crowns of the posterior teeth.
(i.e center of clinical crown-LA
point. ) www.indiandentalacademy.com

Sometimes it is necessary to place the
brackets of the anterior teeth more
incisally in order to achieve the leveling
of the curve of spee.
A good guide is to make the tip of each
canine 1mm longer than that of the
adjacent lateral incisors. In addition the
maxillary central incisors should be
bracketed to be equal in height to the
maxillary laterals.www.indiandentalacademy.com

Individual bracket placement variations:
Maxillary first molar bands.
As the band is being seated, keep the slot
horizontal and level in relation to the
crown. The buccal cusps can be used as a
guide. Since the band will tend to be
seated more on the distal, 0o
of tip is
incorporated in the tube to avoid distal
root tip. www.indiandentalacademy.com

Maxillary second molar bands:
It is better to seat the band
slightly more occlusal.
This will help avoid a posterior
interference or fulcrum.

Mandibular first molar bands:
Using the band as a guide, keep the
slot approximately horizontal and
level in relation to the crown. The
buccal cusps can be used as a guide,
since a slight over correction of –3o
is
incorporated in the tube to prevent
excessive mesial crown tip.

Mandibular second molar bands:
It is better to seat the band slightly
more gingival .
Initially, if the slot is too occlusal, the
mandibular second molars tend to
roll in lingually when a significant
intrusive force is applied.

Mandibular second and first premolar bonds:
Center the bracket mesiodistally on
the prominent buccal developmental
ridge and centre the slot with the
maximum convexity of the crown.

Mandibular canine bonds:
From the occlusal, center the bracket
mesiodistally on the prominent buccal
developmental ridge.
Align the center of the slot with the widest
part of the canine (mesiodistally). This point
will vary depending on the size of the other
teeth and the size and shape of the canine
and it’s tip. The cusp tip is 0.5 to 1mm
higher occlusally than the rest of the
occlusal plane. www.indiandentalacademy.com

Mandibular incisor bonds:
Position the center of the slot so that
the incisal edge of each incisor is 0.5
to 1mm shorter gingivally than the
canine tip.
The lower six anterior brackets should
be slightly more incisal relative to the
L.A point, which will allow the
leveling of the curve of spee.www.indiandentalacademy.com

Align the center of the slot with
maximum convexity(Mesiodistally)
of the crown.This corresponds to
the center(occlusogingivally) of a
fully erupted normal sized
premolar.
Maxillary second and first premolar bonds:

Maxillary second and first premolar bonds:
The most common error is not
placing the brackets gingival
enough. Bennet and Mclaughlin
recommend to place the upper first
bicuspid bracket 0.5mm gingival to
the center of the clinical crown.www.indiandentalacademy.com

Evaluation of treated cases revealed that the
center of the clinical crown of the upper first and
second bicuspids was 0.5 mm occlusal to a line
connecting other clinical crown centers.

Maxillary canine bonds:
Align the center of the slot approximately
along the widest part of the canine
mesiodistally. Then make adjustment to
the height . The cusp tip is 1 to 1.5 mm
higher incisally than the rest of the
occlusal plane. Position the bracket
slightly more incisally relative to the L.A
point or center of the normal fully erupted
crown. www.indiandentalacademy.com

Maxillary lateral bonds:
Center of the slot should be in the
middle of the crown (mesiodistally).
With the small laterals the incisal
edge will align on the base of the
bracket. This will effectively give the
lateral more distal root tip, thus
allowing a small lateral to take up
more space in the arch.www.indiandentalacademy.com

The incisal edges of the maxillary
laterals and centrals should be on
the same level. This is 1 to 1.5mm
shorter than the maxillary canine
tip.

Maxillary central bonds:
The distance from slot to the incisal edge
should be the same as for the maxillary
laterals.
The slightly more incisal positioning of
these brackets will allow treating to a level
curve of spee with a flat archwire rather
than placing reverse and compensating
finishing curves.www.indiandentalacademy.com

In Situations requiring only maxillary
premolar extractions,maxillary first
and second molar tubes with 0o
anti-
rotation are used , which will allow
the maxillary molar to take up more
space in the arch and provide a better
fitting class II posterior occlusion.

In cases requiring the super
torque maxillary incisor
brackets, use a canine bracket
with slightly more (+3)torque.
This compensation will prevent
excess labial root torque to the
maxillary canine.

FOLLOWING ARE THE FEW
VARIATIONS OF BRACKET
PLACEMENT SUGGESTED BY
BENNET AND MCLAUGHLIN

If it is intended to treat to a class II
molar result (For example , following
loss of two upper premolars and no
lower premolar extractions), then better
occlusion can be obtained if upper first
and second molars are allowed to rotate
mesially. Occlusal adjustment may be
required at the end of the treatment to
ensure good lateral excursions.

These tubes have zero
distal rotation
compared 10o
in
normal prescription.
They are helpful when
treating to a class II
molar result www.indiandentalacademy.com

Placement of different canine brackets on
narrow Maxillary or Mandibular bone.
Some patients often has narrow arches, with upper
and lower canines blocked out buccally. Canine
brackets with –7o
upper torque and –11o
lower
torque are not helpful in correcting such problems
Canine brackets with zero torque encourage canine
roots to lie more in cancellous bone allowing easier
retraction.

Missing upper lateral incisors:
If lateral incisor is missing and it has been
decided to close the space, good torque control of
upper canine is needed, and to change the torque
from –7o
to +7o
the bracket is inverted 180o
.
This opposite torque helps to move the canine
roots palatally

Instanding upper lateral incisors
These teeth have special torque needs
during finishing and detailing. It may
be helpful to place a bracket rotated
through 180o
to give –10o
torque

In treating cases where an
anterior tooth has been
extracted(or missing), it is
helpful to vary the axial
position when bonding teeth
adjacent to extraction site.
This assists in achieving root
paralleling and reduces the
amount of wire bending
required during treatment.
Axial/paralleling variations:

Over correction of Axial rotation correction
can be achieved by offsetting the brackets
mesially or distally.
Interaction of bracket and arch wire to control rotations.
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Upper first molar bracket positioning
The vertical placement is decided
using the Bracket placement chart.
It is a common error to allow the
band to seat too gingivally at the
distal,causing excessive crown tip.www.indiandentalacademy.com

Correct positioning
Band seated more gingivally
when treating to a class II
molar relationship.
Mesio-distally the bracket
should straddle the buccal
grove.
Upper first molar bracket positioning

Lower first molar bracket positioning
RANGE
2.0MM- 3.5MM
CORRECT BAND POSITIONING
COMMON ERROR IS TO ALLOW
THE BAND TO SEAT TOO
GINGIVALLY AT THE MESIAL
ACCORDING TO BRACKET
PLACEMENT CHART

Upper second molar
In all cases upper second molar brackets
are placed 2mm from the occlusal
surface of the crown

Lower second molar
The second molar tube should
straddle the buccal grove of the lower
second molar
If the second molar tube is placed
too occlusally, a marginal ridge
discrepancy occurs.
It is a common error to allow first and
second molar bands to seat too
gingivally on the mesial aspect. This
causes tipping and marginal ridge
errors.

3.MBT
MBT Appliance system emphasizes on
its versatility and bracket positioning.

Design features:
Like other modern bracket systems , MBT system also
have been developed using computer aided design and
computer aided machining I.e CAD/ CAM System.
The resulting
brackets by CAD
process can have
torque in base ,
torque in face, or a
combination of
two. www.indiandentalacademy.com

IN/OUT specifications
NOTE : IN/OUT Feature of pre adjusted brackets are fully
expressed, because the arch wire lies snugly in the slot.
A premolar bracket which is 0.5 mm thicker
than normal brackets are used for the cases
with small upper second premolars.

TIP specifications
NOTE:TIP Features of the pre adjusted appliance is
almost fully expressed.
Upper and lower molar
attachments have 0o
tip.
When placed parallel to
the buccal cusps of the
molars, this delivers 5o
of tip in the uppers and
2o
of tip in the lowers

Versatility of MBT system:
1. Options for palataly displaced upper lateral incisors.(-10o
).
2. Three torque options for the upper canines(-7o
,0o
, +7o
).
3. Three torque options for the lower canines(-6o
, 0o
,+6o
)
4. Interchangeable lower incisor brackets-same tip and torque
5. Interchangeable lower premolar brackets-same tip and
torque
6. Use of upper second molar tubes on first molars in non HG
cases.
7. Use of lower second molar tubes for the upper first and
second molars of the opposite side, when finishing the
cases to a class II molar relationship.

Three torque options for the upper canines:
(-7o
, 0o
,+7o
)
Effective torque control of the upper canines is
necessary, because they are key elements in
mutually protected occlusion. By using various tip
and torque to the canines it is possible to position
the canine in such way that it will fulfill it’s role in
lateral excursions.

Three torque options for the lower canines:
(-6o
,0o
,+6o
)
In some deep bite cases it is necessary to
torque the canine crown labial and at the
same time maintain the canine roots in
alveolar bone.

Factors which govern the selection of canine brackets.
1.Arch form.
2.Canine prominence.
3.The extraction decision(tip control).
4.Overbite.
5.Rapid palatal expansion.
6.Agenesis of upper lateral incisors, where
space is to be closed.

Dogherty Guagewww.indiandentalacademy.com

INNOVATIONS OF M.B.T
1. SECOND PREMOLAR TUBES:
ADVANTAGES:
 Decreased occlusal
interference of the opposing
teeth,mainly in overbite and
class II cases.
 Comfortable to the patient.
 Decreased bracket failure.
 Decreased friction during
the sliding mechanics.www.indiandentalacademy.com

2. LOWER SECOND MOLAR MINI TUBES:
Helpful in cases where, the inter-occlusal
space and the gingival tissue do not allow the
placement of regular banded molar tubes or
bondable molar tubes.

4.Lingual appliance
Indirect bonding in laboratory procedure is
indispensable in lingual treatment because of the
variations of lingual tooth surfaces and the
limitation of human eyes and hands in accurate
bracket positioning.
There are three methods to set up bracket
positions in the laboratory that represent the
evolution of the lingual orthodontics in lab
procedures.
1. TARG(TORQUE ANGULATION REFERENCE
GUIDE)
2. CLASS (CUSTOMIZED LINGUAL APPLIANCE SET
UP SERVICE)
3. HIRO SYSTEM

The TARG
The TARG, despite the anatomic
variations of the lingual surfaces,
permits to bond brackets in the
laboratory at an accurate distance
from the occlusal edge of each
tooth with respect to horizontal
occlusal plane.www.indiandentalacademy.com

The tooth orientation is made with a
guage or torque blade. The model is
tipped on a swivel base until the long
axis of the labial face of tooth aligns
with the specific guage curvature at
the middle third of the tooth.
This orientation allows us to pre-program
torque and angulation(tip)before starting
the treatment www.indiandentalacademy.com

TARG (TORQUE ANGULATION REFERENCE GUIDE)
Developed by ORMCO

The TARG with the thickness measurement system.www.indiandentalacademy.com

The two blades of the thickness measurement
system. www.indiandentalacademy.com

The gap between properly oriented bracket
base and the tooth surface is filled with resin.www.indiandentalacademy.com

In case of crowding, the bracket
is decentered or rotated.www.indiandentalacademy.com

On the right incisor, the
bracket is moved distally
for overcorrecting.
On the lateral, the bracket
is bonded mesially to
begin correction of the
rotation.
Once the rotation is parially corrected, the bracket is re-centeredwww.indiandentalacademy.com

5. BEGG APPLIANCE.
Off-centering the bracket to
the rotated side will help to
overcorrect the rotations.
Anti-rotational effect is
achieved by raising the
flange of the bracket by
welding 0.010’’ligature
wire. www.indiandentalacademy.com

Modified placement of buccal
tubes and elastic hooks.www.indiandentalacademy.com

Close-up of modified placement of
buccal tubes and elastic hooks.
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Various gauges used for
bracket placement.

A. Micrometer for determining vertical
height.
B. Incisal rest arm controlled by
micrometer.
C. Plunger for separating bracket holding
arms.
D. Trigger for releasing bracket.
E. Calipers to measure mesiodistal width of
tooth at height of bracket.
F. Bracket holding arms.
G. Locking knob, released when rotating
Instrument for use on opposite arch.
H. Control knob for width-measurement
calipers.
I. Fiber-optic bundle In plunger for
attachment to light-curing unit.
Precision bracket placement instrument
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Labial slot machine. The labial surface of individual teeth
is oriented to a stationary arch wire slot position.

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0
0
2
Height Gauge Tweezer

Bracket Positioner J
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U
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T
2
0
0
0www.indiandentalacademy.com

J
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A
U
G
U
S
T
2
0
0
0
BRACKET POSITIONING
GAUGE FOR LINGUAL
APPLIANCE.

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2
0
0
1
GIK BRACKET POSITIONING GAUGE.
COLOR CODED
GAUGES WITH
VARIOUS
BRACKET
HEIGHTS.

Bracket Placement with the Preadjusted Appliance
1. Horizontal errors. Placing the bracket to the
mesial or distal of the vertical long axis leads to
undesirable tooth rotation. Such errors can be avoided by
visualizing the vertical long axis—directly from the
facial surface, or with a mouth mirror from the incisal or
occlusal aspect. Some orthodontists even draw a line on
the tooth to indicate the correct vertical long axis.
Horizontal bracket placement errors can
be avoided with careful technique.

2. Axial or paralleling errors. If the bracket wings
are not parallel to the long axis, the result will be
unwanted crown tipping. These errors can be
avoided in the same way as horizontal errors.
Axial or paralleling errors can be avoided
with careful placement technique.

3. Thickness errors. Leaving excess adhesive under
a portion of the bracket base or failing to conform
the base accurately to the contour of the tooth can
cause improper torque or rotation. This problem is
overcome by expressing all excess adhesive from
beneath the bracket during placement and by more
accurate contouring.
Excess adhesive beneath bracket base can
cause thickness and rotational errors.

4. Vertical errors. Improper vertical placement
can lead to extrusion or intrusion of teeth,
as well as to torque and in-out errors
Improper vertical placement can lead to extrusion
or intrusion and to torque and in-out errors.

Few Special Considerations

1. Partially erupted teeth. Young patients frequently have
partially erupted teeth on which it is difficult to locate the
centers of the clinical crowns. Because the apparent clinical
crown is foreshortened, the tendency is to place the bracket
too incisally or occlusally, especially with bicuspids and
lower second molars.
Partial eruption makes it difficult to visualize centers of clinical
crowns.
Gingival Concerns:

2. Gingival inflammation. This also causes
foreshortening of the clinical crown, and the
bracket again tends to be placed too incisally or
occlusally.
A. Typical patient with healthy gingivae. B. Same case with gingival
inflammation in upper right
quadrant, reducing apparent
length of clinical crowns.

3. Teeth with palatally or lingually displaced roots.
Gingival tissue covers a greater portion than normal
of the clinical crowns of such teeth, shortening the
clinical crown.The bracket would be placed too
incisally or occlusally.
Lingually displaced root (right) can make clinical crown
appear shorter.

4. Teeth with facially displaced roots. This
situation is often found with cuspids. The
clinical crown appears longer, making the
bracket placement too gingival.
Facially displaced root (right) can make
clinical crown appear longer.www.indiandentalacademy.com

Incisal or Occlusal Concerns
1. Incisal or occlusal crown fractures or tooth
wear. With such teeth, the apparent clinical crown
is shorter. The problem can be corrected by
restoring the crown to its proper length or by
estimating how long the crown was before the
fracture or wear.
Incisal crown fracture or
tooth wear makes it
difficult to visualize center
of clinical crown.

2. Crowns with long, tapered buccal cusps. Cuspids
or bicuspids with long, tapered cusps often do not
have adequate contact with the opposing teeth. If
the bracket is placed in the center of the clinical
crown, the adjacent marginal ridges will not be
aligned. Improper placement can be avoided by
selectively reducing the height of the cusp prior to
bonding.
With long, tapered buccal cusp, if bracket is placed in center of
clinical crown, adjacent marginal ridges will not be properly

Accurate bracket positioning is
essential, so that the built in
features of the bracket system can
be fully and efficiently expressed.
This helps in treatment mechanics
and improves the consistency of
the results.
Conclusion

Thank You!!

Buliding treatment mechanics though bracket positioning

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