Tweed philosophy 2 /certified fixed orthodontic courses by Indian dental academy

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 Introduction :

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History and evolution of the edgewise appliance.
Dr.E.H.Angle, Dr. Charles Tweed, Dr.Levern
Merrifield---contributions to the development of
edgewise appliance
The Tweed philosophy
The Tweed technique
The Tweed Merrifield philosophy
The Tweed Merrifield technique
Conclusion

Dr.Edward Hartley Angle
 The edgewise arch

mechanism was the brain
child of this master
technician.
 By the time of
Dr.Tweed,1930,with the
introduction of milled
brackets, S.S ligature
wires it had evolved into a
precision appliance, that
demanded accurate fitting
and placement of bands
and attachments on
teeth.

Introduction
 The edgewise arch mechanism/appliance was

Dr Angle’s last and greatest contribution to
orthodontics ,after almost a lifetime devoted to
improvement of orthodontic appliances.

 Described it to Fedrick Noyes:
“all you can do is push, pull or turn a tooth. This
appliance is as fine as I can make it. I have
given you the appliance. Now for God’s sake
use it.”

 Edgewise mech was designed to place teeth

into Angle’s concept of line of occlusion:
“the line with which in form and position according
to type, the teeth must be in harmony if in
normal occlusion.”

 Angle believed that there could be only one true
line of occlusion and it must be the same as the
architectural line on which the denture
apparatus was constructed.

 This ideal line was intended not only to govern

the length and breadth of the dental arches, but
also the size and pattern of each tooth cusp and
inclined plane composing these arches.

 Laber : the best the orthodontist can do is
to secure the normal relationship of teeth
and correct general form of the arch,
leaving the finer adjustments of individual
typal form to be worked out by nature
through her forces, which must in any
event triumph finally.


 Angle’s theory:
At last here was an appliance with which all
necessary tooth movements, such as restoration
of normal arch form, correction of all rotations
and all en mass movements of teeth necessary
for normal cuspal relationships could be
achieved.
He was absolutely correct when his treatment
techniques were adhered to closely and no
concern was raised to the resultant bimaxillary
protrusion that was the usual aftermath of such
treatment procedures.

Angle’s philosophy of treatment
 Based on the then prevalent assumption that ,if

cuspal interdigitation of teeth were made normal,
stimulation by function would result in growth of
basal bone structures.
 Little or no thought was given to the inclination
of the mandibular incisor teeth or to normal
mesiodistal rel of teeth and their respective jaw
bases and head structures.
 It was assumed function would take care of such
matters.
 Extraction of teeth for orthodontic therapy wasn’t
even an option .

 Research proved otherwise:
The theory that stimulation by function
could and would result in growth of
maxillary and mandibular basal bones
discarded. No scientific evidence found to
indicate that it was possible to grow bones
beyond their genetic potential.


HISTORY : EVOLUTION OF
EDGEWISE
APPLIANCE


E.H. Angle – Graduation 1878, experienced
many technical problems and frustrations in
treatment which irritated, motivated and inspired
him to develop a standard appliance. His
obsession for order motivated him to create the
Angle System 1887 : this ultimately resulted in
the multi banded edgewise appliance 5yrs before
his death.
5 properties that appliance must have

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SIMPLE
: must push ,pull and rotate teeth
STABLE
: must be fixed on the teeth
EFFICIENT : must be based on NEWTON’S 3RD LAW
and anchorage
 DELICATE : must be accepted by the tissues and must
not cause inflammation and soreness
 INCONSPICUOUS : esthetically acceptable

The standard appliance used by
Angle
Basic components of
the standard
appliance used by
Angle:
Traction screw,
jack screw,
attachment tubes,
band material
lever wire,
arch wire,wrench

DEVELOPMENT OF EDGEWISE
APPLIANCE :
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ANGLE E-ARCH
PIN & TUBE
RIBBON ARCH APPLICANCE
EDGEWISE APPLIANCE.
EVOLUTION OF EDGEWISE BRACKETS:
1)
2)
3)
4)
5)

SINGLE WIDTH BRACKET
SIAMESE BRACKET
LEWIS BRACKET
STIENER BRACKET
BROUSSARD BRACKET

E-arch
 In the late 1800s the orthodontic appliance was

some sort of rigid framework to which the teeth
were tied so that they could be expanded to the
arch form dictated by the appliance.

 E-arch was an improvement on this basic

design.
 It employed crown movement of teeth with
simple anchorage.
 Brass wire ligature and stationary anchorage
in the molar area were used to expand all the
teeth into normal occlusion

 Bands were placed on molar teeth and

heavy labial arch wire extended around
the arch. The end of the wire was
threaded and a small nut placed on the
threaded portion of the arch allowed the
archwire to be advanced so that the arch
perimeter increased.
 Individual teeth were simply ligated to this
E-arch.

E-arch appliance


Basic E-arch


 The heavy archwire was supplied in 4 designs:
1. Basic E-arch used with baker’s anchorage
2. Ribbed E-arch used in expansion by tying
brass ligatures to arch wire
3. E-arch without threaded ends that fit into the
molar sheaths, used with attachment for high
pull headgear.
4. E-arch with hooks in maxillary wire ,used to
move entire maxillary dentition distally.

Ribbed E-arch


E-arch with headgear


 Advantage:
Simplicity

 Disadvantge:
Can deliver only heavy intermittent forces
Capable of only tipping teeth to new
position, no precise tooth positioning
possible.
Correction of axial inclination of teeth cant be
accomplished.

 Angle concluded from his failures that it
was necessary to bodily move teeth.


Pin and tube appliance
 To overcome the inability of E-arch to

perform precise tooth positioning, Angle
placed bands on other teeth and used
vertical tubes on each tooth into which
soldered pins from a smaller arch wire
was placed .
 With this appliance tooth movement was
accomplished by repositioning the
individual pins at each appointment.

 Orthodontist had to

expertly solder pins, fit
pins perfectly into tubes
on the bands, remove the
pins, move the pins along
the archwire, solder pins
again and fit pins once
again into tubes on
bands..to bring about
tooth movement.



 Disadvantage:
1. Relatively heavy base arch wire used, so

spring quality poor and small adjustments were
needed which were difficult to make
2. Construction and adjustment very difficult
3. Though theoretically great precision in tooth
movement is possible, impractical for clinical
use.
Neverthless it was the first appliance with
mechanism for root movement.

Ribbon arch appliance(1915)
 Angle modified the tube on each tooth to provide
a vertically positioned rectangular slot behind
the tube…i.e,brackets with vertical slot.
 Thus brackets were introduced with this new
appliance.
 Gold ribbon arch wire was placed into the slot
and held with brass pins.
 Had good spring qualities and efficient in
aligning malposed teeth.

Ribbon arch appliance


Disadvantage:
 not suitable for enmass tooth movement.
 Mesial and distal tipping bends could not
be incorporated into the archwire.
 Poor root positioning control
 Resiliency of the arch wire did not allow
generation of the moments necessary to
torque roots to a new position.

Edgewise appliance
(introduced 1928)
 To overcome the deficiencies of his

previous appliances, Angle changed the
form of the bracket in the ribbon arch
appliance. He placed the slot in the
centre and oriented the slot from vertical
to horizontal and inserted a rectangular
wire rotated 900 to the orientation the wire
had with the ribbon arch bracket
(hence the name edgewise)

Edgewise appliance


 Edgewise bracket

when formed
consisted of 3 walls
within the bracket.
 0.022 x0.028..
 Soft gold originally
which tended to
deform easily
 Slot oriented
horizontally.

 EDGEWISE APPLIANCE
metal bracket …. slot in center, placed in
horizontal plane 0.022 x 0.028” rectangular
wire in narrow/ edgewise position
Unique feature  rectangular wire in
rectangular slot  twisting / torquing forces
could be imparted to control the axial
inclination of teeth
So possible to move teeth in all 3 planes of
space with a single arch wire.

Evolution of edgewise brackets
 Single width brackets:
0.050 inch wide and soldered to gold
band material.
because of the narrow width, the bracket
by itself was ineffective for tooth rotation.
so gold eyelets were soldered at appropriate
positions on the band..ligature tied from eyelet
to archwire to effect rotations…needed repeated
tying.
time consuming and inefficient.

 Two brackets on a single tooth.
the two brackets were placed so as to
effect rotation of tooth.


 TWIN BRACKET: (siamese twin brackets)
Swain..originator of the idea.
two edgewise brackets joined together on
common base.
0.05 inch distance b/t the two.
initially used only on centrals and molars.
later narrower width brackets for other
teeth.:4 types:
extra wide, standard, intermediate and junior.

 Advantage of twin bracket:
1. effective for rotation correction.
2. greater axial control
3. incorporates positive control:once tooth
has been derotated mere tying of wire
to bracket with ligature maintains the
tooth in its corrected position.

 Disadvantage:
because of the increased width of the twin
bracket, the amount of wire available b/t
brackets on the arch decreased.
Adverse effect on inherent resiliency of archwire.
also in closing loop arch wires and second order
bends,decreased interbracket span interferes
with amt of closing action that can be attained.

 Lewis bracket:
another approach to address problem of
rotation correction
soldered auxilary rotation arms that
abutted against the bracket,thus offering
lever arm to deflect archwire and derotate
the tooth.


 Steiner brackets:
Flexible rotation arms incorporated…so did
not depend entirely on resiliency of
archwire for tooth rotation.

 Broussard bracket:
addition of 0.0185 x0.046 vertical slot to
accept a doubled 0.018 auxillary wire.

Dr.Charles.H.Tweed


CHARLES H.TWEED : Graduated from an
improved Angle course in 1928 at the age of 33yr.

Helped Dr.Angle in publishing an article in the dental
Cosmos.
Returned to Arizona and in Pheonix established the First
pure edgewise speciality practice in U.S. For the next 2yr with
Dr.Angle’s advise followed edgewise technique .
Dr.Angle urged his dear student to :
1. Dedicate his life to the development of the edgewise appliance
2. To make every effort to make orthodontics as an specialty within the
dental profession.
Following advise Dr.Tweed instigated the first orthodontic specialty
law in the U.S.. In 1929 first law limiting the practice of orthodontics to
specialists was passed ; Dr.Tweed received certificate no1. in Arizona
to become the first certified specialist in orthodontics in the U.S.


 Aug 11, 1930, Angle died at age of 75yr.
 Tweed held to Angle’s conviction that one must never

extract teeth, but this lasted for only 4yrs.In 1932 published
article in Angle orthodontist “reports of cases treated with
Edgewise Arch mechanism.”
 What he observed in his patients during retention was so
discouraging for him that he almost gave up practice. He
devoted the next 4yr studying his successes and failures.he
made a most important observation:
 Lack of harmony in facial contour was in direct proportion to
the extent to which the denture had been displaced mesially
into protrusion.
 Upright mandibular incisors frequently were related to post
treatment facial balance and succesful treatment.
To position mandibular incisors upright ,he concluded one
must prepare anchorage and extract teeth.

 He selected failed cases and treated them
with premolar extractions.
 Was called a traitor ,faced critisism.
 In 1940 he produced case reports of the
retreated cases.


 Tweed made considerable effort to place
mandibular incisors at 90 +/- 5 deg to MP
without resorting to removal of teeth. In
some cases this was achieved by over
expansion of dental arches , but too often
at the expense of impacting both
Unerupted 2nd and 3rd molars. The
aftermath of such treatment was relapse
and damage to investing tissue.

Importance of identifying growth
trends of patients
1.Type A growth trends :
middle and lower face are growing forward and
downward in unision with no change in the ANB angle.
growth is aprroximately equal in both vertical and
horizontal dimensions.
if molar relationship is class II and the ANB exceeds
4.5deg its type A subdiv growth trend. It is better to place
the patient on Kloehn cervical Headgear to restrain
maxillary growth.
Prognosis is good because the point B is moving
forwards as the maxillary denture is moved posteriorly.

 Type B growth trend :
the middle face is growing forward more rapidly
than the lower, ANB increases in size with
growth.
if ANB is <4 deg prognosis is fair,one may
expect reasonably good facial changes and
good occlusion.
if ANB 7-12 deg prognosis poor.
Growth of the middle and lower face is
predominantly in the vertical dimension.

 Type C growth trend:
the lower face is growing forward and downward
more rapidly than the middle face, with a
decrease in the size of the ANB.
prognosis very good from the point of view of
facial esthetics.
But during retention one has to observe for any
lingual tipping of mandibular incisors or labial
tipping of maxillary incisors. Prolonged retention
may be required depending on the type of
perioral musculature.
Regardless of the size of the FMA , when the
growth is mostly in the horizontal direction the
growth trend is type C subdivision

TWEEDS CONTRIBUTIONS:
a) Emphasized the 4 objectives of orthodontic treatment
with emphasis & concern for facial esthetics.
1.the best balance and harmony of facial lines
2.Stability of dentures after treatment
3.Healthy mouth tissues
4.An efficient chewing mechanism

b) Developed the concept of uprighting teeth over basal
bone with emphasis on the mandibular incisors

c) Made the extraction of teeth for orthodontic correction
acceptable & popularized extraction of 1st pre molar.

d)

Enhanced the clinical application of cephalometrics.

e. Developed diagnostic facial triangle to make

cephalometrics a diagnostic tool as well as a guide in
treatment & evaluation of treatment results.
1. the normal range of inclination of the mandibular
incisors to MP was 90+/- 5deg. (IMPA)
2. when he was working on why he could not make his
unfavorable patiens beautiful like his favorables even
with identical treatment,
he found out that the FMA was the difference
(recognised the importance of different growth trends)
norm=25 deg, range=16-35deg; extraction of
teeth was more necessary in patients with
FMA >30deg.
3. 3rd angle FMIA was 65 deg. the size of the FMIA was
found crucial in creating satisfactory facial esthetics
with orthodontic treatment.

Tweed’s diagnostic facial triangle


f. Developed concepts of orderly treatment
procedures & introduced anchorage
preparation as a major step in treatment
g.Developed a fundamentally sound
consistent pre orthodontic guidance
program using & popularizing serial
extraction of primary & permanent teeth.

 Angle gave orthodontics the Edgewise
bracket ,but Tweed gave the speciality the
appliance.
 The TWEED PHILOSOPHY was born.
 He devoted 42yrs of his life from 1928 till
his death on Jan 11,1970 to the
advancement of edgewise appliance.


Levern Merrifield
LEVERN MERRIFIELD
1953 : took TWEED course
1960 : selected by
Dr.Tweed to be codirector
and continue his work on
edgewise appliance.
1970 : Director  study of
orthodontic dentistry &
development of
edgewise appliance

Merrifield’s contributions
A.Diagnostic concepts:
Introduced diagnostic analyses which allow
clinicians to determine whether and when
extractions are necessary, if indicated which teeth
to be extracted.
1. The dimensions of the dentition :anterior
limit ,posterior limit ,lateral limit and vertical
limit exists..these limitations must be
recognised and treatment designed to conform
to these limitations when normal muscle
balance exists.

Merrifield’s diagnostic concepts
2.Recognise the dimensions of the dentition and treat for
maximum facial harmony and balance :
essentially 3 factors affect facial balance:
 Position of teeth
 Skeletal pattern
 Soft tissue thickness : total chin thickness and upper
lip thickness must be equal
Careful consideration of these factors will enable
the clinician to determine whether dental
compensation will improve facial balance.

Upper lip thickness and total chin
thickness
If the total chin
thickness is lesser than
upper lip thickness, the
anterior teeth must be
positioned upright
further to facilitate a
more balanced facial
profile because lip retraction
follows tooth retraction

Some measurements to judge facial balance:

1.

Profile line

2.

On frontal view vermilion border of the lower lip should bisect the distance
between the bottom of the chin and the ala of the nose.

3.

FMIA : Tweed believed this angle was significant in establishing balance
and harmony of the lower face. Related to FMA.
For FMA 22-28 deg, FMIA 68deg
Standard : FMA 30 deg ; FMIA 65deg.
dental compensation for a high FMA requires additional uprighting of
flared mandibular incisors..visa versa.

4.

Z – angle : indicative of soft tissue profile and more responsive to maxillary
incisor retraction than FMIA
70-80 deg normal range
75-78 deg ideal, depending on age and gender.

Profile line in a balanced face
 When facial balance
is present, the ideal
relationship of profile
line is to be tangent to
the chin and the
vermillion border of
both the lips and
should lie in the
anterior 1/3rd of the
nose.

Profile line in a face not in balance


Merrifield’s Z-angle and FMIA
Z- angle :
70-80 deg range
75 -78 deg ideal
Maxillary incisor
retraction of 4mm
allows 4mm of lower lip
retraction and 3mm of
upper lip response

Merrifield’s diagnostics concepts
5.Skeletal factors in facial balance: (cranial disharmony )
FMA,IMPA,SNA,SNB,ANB,
Ao-Bo,Occlusal plane angle,
PFH,AFH,facial height index (0.69),facial height
change ratio
Merrifield and Gebeck reported a 2:1 increase in PFH
compared to AFH in successfully treated class II patients.
6.Jim Gramling’s probability index:
observed that in successfully treated class II patients
FMA was controlled , FMIA increased,
IMPA reduced , Z-angle increased , AO-BO reduced
mandibular incisor position was corrected.

Probability index suggests that the
following pre treatment conditions might be
necessary for Class II treatment success :
FMA should be 22-28 deg .
ANB should be 6 deg or less .
FMIA should be greater than 60 deg .
Occlusal plane should be 7 deg or less .
SNB should be 80 deg or more .

Differential diagnosis analysis system
Cranio facial Analysis :
Vertical component :
FMA :22-28 deg
AFH/PFH ratio : 0.65 to 0.75
Occlusal Plane to FH
Horizontal component:
SNB
ANB
Z-angle

Differential diagnosis analysis system

3. Total space analysis: 3 parts:
a. Anterior space discrepancy analysis:
anterior tooth arch surplus/deficit :space available in mandiular arch
from canine to canine and sum of mesiodistal dimension of six
anterior teeth….+…
cephalometric discrepancy (the amount of space required to upright
the mandibular incisors for optimum facial balance)
b. Mid arch discrepancy :
mid arch tooth discrepancy = diff b/t
available midarch space and mesio distal width of 1st
premolar, 2nd premolar,1st molar, space required to level curve of
spee.
+
occlusal disharmony : measure distance b/t maxillary premolar
buccal cusp to embrasure b/t mandibular 1st and 2nd premolar.
(difficulty factor of 2)

Merrifield’s differential diagnostic
analysis system
c. Posterior space analysis:
Posterior tooth arch discrepancy:
space available = distal of mandibular first
molar to ant border of ramus along occlusal
plane.
required space = sum of mesio distal width of
2nd molar and 3rd molars.
Most easily recognisable sign of post space
deficit is late 2nd molar eruption.

Merrifield’s treatment concepts
1.Directional control during treatment
2.Sequential tooth movement
3.Sequential mandibular anchorage
preparation
4.Organisation of treatment into four orderly
steps that have specific objectives.


Seventh objective of treatment
1. Clinician must position and arrange teeth for maximum
2.
3.
4.
5.
6.
7.

facial and dental esthetics.
Functional efficiency
Health of teeth,jaws,joints and surrounding tissue.
Stability.
Harmonize correction with growth in growing patients.
Position the dentition so that it is in state of continual
harmony with its environment.
The clinical objectives must be pursued in an ethical,
moral and compassionate manner with overriding
concern for public welfare.

The TWEED philosophy and
technique


Tweed philosophy
1.That practically all malocclusions are
characterized by a forward placement of
teeth in relation to their basal bones.
Malocclusion is but a symptom of failure in
growth of the bones upon which the
alveolar processes which form the bony
support of the teeth is built.


Under normal conditions ,i.e normal growth
of the basal bones have occurred
Erupting teeth
under influence of muscular forces and ant
component of occlusal forces

Teeth are located in proper position on
basal bones that the predetermined plan
of occlusion called for.

If there is retardation in forward growth of the jaws
during growth period
Erupting teeth
Under the influence
of muscular forces
and ant component
are guided to locations where there is a balance of
force play up on them.
But the basal bone has failed to grow forward to
harmonize with this plan
So teeth get placed too far forward in relation to the
basal structures.( noticed in incisors)

Tweed philosophy contd.
2)That the establishment and maintenance of
stable anchorage is the fundamental factor in
successful orthodontic treatment and should be
the initial concern of the operator.
 This is the outstanding feature of Dr.Tweed’s
philosophy and all other features are built around
it.
 His first efforts in treatment were always directed
toward establishing a firm anchorage from which
to work.
 This anchorage is not visualized in terms of
passive stabilization but rather in the form of
dynamic resistance.

 He believed any clinical orthodontist who
wants to routinely create excellent facial
changes for their patients, will recognise the
importance of and will prepare anchorage
routinely in their practices.


 The degree to which anchorage should be
prepared will vary considerably.

 Unless one is purposely wanting to move the

mandibular buccal segments forward or to move
point B downward and backward for some
specific reason, the terminal mandibular molars
must always be upright to prevent their being
elongated when class II intermaxillary force is
used.




Classified anchorage preparation into THREE
categories :
1. First degree anchorage preparation:
minimal anchorage preparation required.
applicable in : malocclusions with ANB 0-4deg ,facial
esthetics are good, total discrepancy does not exceed
10mm. True class III or Psuedo class III cases.
mandibular anchor molars uprighted /maintained in their
upright positions to prevent being elongated by Class II
elastics.
The direction of pull of the elastics in function, will not
exceed
90 deg when related to the long axis of the terminal
molars.

2.Second degree anchorage preparation:
necessary for malocclusions in which ANB > 4.5 deg
facial esthetics demand that point B
moved anteriorly and point A posteriorly.
class II cases, accompanied by type A, type A subdivision
type B, type B subdiv growth trends.
anchor prep:
When 2nd molars erupted they are always banded.
Mandibular terminal molars tipped more distally so that
their distal marginal ridges are at gum level.
the direction of pull of class II elastics rel to long axis of
terminal molars should be greater than 90 deg during function, so that
terminal molars will be further depressed rather than elongated.

3.Third degree anchorage preparation :
total anchorage preparation necessary in severe
malocclusions where total discrepancy 14- 20mm ,ANB
doesn’t exceed 5 deg.
class I cases with exceedingly irregular teeth, bimax
case with mesially inclined teeth.
anchor prep:
Jigs required
all 3 posterior teeth- 2nd molar, 1st molar ,2nd premolar
tipped to distoaxial inclinaiton to such a degree that
distal marginal ridges of the terminal molar below gum
level

3)That the teeth, like inanimate objects, best resist
the force of displacement when tipped to the
angulation that offers the most advantageous
mechanical resistance against the pull of
dislodging forces.
They are ultimately best stabilized when they
overlie the basal ridge of bone comprising that
portion of the body of the mandible and maxillae
from which the alveolar processes take their
origin.

 Teeth tipped to a
angulation that offers
the most
advantageous
mechanical
resistance against the
dislodging for force of
the elastics.


 It was believed at that time that-“An undisturbed
tooth affords the best resistance to movement.”

 Tweed-It is impossible to band a tooth that’s in
tight contact with a neighbor and have it
undisturbed.

 Reatin –when teeth are tipped distally as during

Anchor prep, osteoid tissue is laid down adjacent
to mesial surface of the tooth being moved
distally. This new calcified bundle bone doesnt
enhance the resistance to tooth movement when
force is applied ;eg. Class II elastics.

 Why are the stakes of the tent slanted such that
the pull of the tent ropes against the stake would
not exceed 90deg?
Ans: If the stakes are positioned too vertically into
the ground, when a strong wind blows, the
stakes will be pulled upward and toward the tent
and the tent will be uprooted.The stakes should
be positioned at an angle which will draw them
deeper in to the ground by the pull of the tent
ropes

 Using this simple mechanical principle, Dr.Tweed
said anchorage preparation is mechanical in
nature.(he saw it from a mechanical point of view
than physiological)
 If the teeth in the buccal segments of the
mandibular denture are positioned upright, and
terminal molars tipped back like tent stakes, so
that the pull of the intermaxillary elastics, when
related to the long axes of terminal molars ,does
not exceed 90deg when the mouth is functioning,
the entire mandibular denture will be more stable
and better able to resist forward displacement.

 But if we leave the anchor molars in their
undisturbed mesially inclined positions,the
action of class II elastics being upward
and forward, the terminal molars will be
elevated and uprooted.


 If this is allowed to occur, it will be
followed by excessive depression of the
mandibular incisors, with a drastic and
unecessary alteration of the occlusal
plane…the FMA will open up and point B
will drop downward and backward as the
entire mandibular denture is tipped and
displaced forward into protrusion.

 In the use of intermaxillary force, it was
Dr.Tweed’s contention that the teeth in the
anchorage denture must be placed in distal
axial inclination if they are to be expected to
resist forward and occlusal strain of elastics.


 The incisors in the anchor denture must
be adjusted in lingual axial inclination to
give their added support against forward
movement of the entire anchorage base.

 This is aptly termed
DYNAMIC ANCHORAGE.

Dynamic stationary anchorage
 In the use of intermaxillary
force, it was Dr.Tweed’s
contention that the teeth
in the anchorage denture
must be placed in distal
axial inclination if they are
to be expected to resist
forward and occlusal
strain of elastics.
 The incisors in the anchor
denture must be adjusted
in lingual axial inclination
to give their added
support against forward
movement of the entire
anchorage base.

 Also teeth must also have adequate foundational
support.
 The mandibular incisors are the most difficult to
retain permanently in perfect alignment.
 Dr.Tweed carried these teeth lingualy and placed
them such that their roots are overlying the bony
ridge arising from the mental area of the body of
the mandible.
“placing the incisors on the ridge”
 When so relocated incisors showed no tendency
of returning to positions of malocclusion than do
buccal teeth.

 So important did Dr.Tweed consider this factor
to be that it became his primary objective in
treatment and all other dental units in both
dentures are subsequently adjusted to
harmonize with such repositioned incisors.

 The 1st molars which were looked upon as the
key teeth in treatment became factors of
secondary importance in routine corrective
treatment!!!!

4)That teeth are most readily moved when
their property and power of mechanical
resistance has been primarily reduced.


 When teeth that are to be moved are

found to be at an angulation that they offer
mechanical resistance to movement, it is
best to change their angulation to such
form that this mechanical resistance to
movement is reduced to a minimum.

 This way anchorage is conserved and
tooth movement favored


Class II div 1

 Maxillary incisors usually flared

—this establishes a most
effective stationary anchorage
against their lingual movement
by class II elastics..instead of
being moved lingualy they will
make a fine anchorage …strain
the mandibular prepared
anchorage.
 When teeth that are to be
moved are found to be at an
angulation that they offer
mechanical resistance to
movement, it is best to change
their angulation to such form
that this mechanical resistance
to movement is reduced to a
minimum

 Lingual tipping of incisors

brought about by flattened and
slightly broadened 0.018 s.s
(levelling stage)

 0.020 wire-pot belly loop distal
to brackets of canines,

 slight expansion and

flattening; exaggerated curve
of spee placed in the archwire
to prevent elongation of incisor
teeth as they are tipped
lingually


5)That 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.


 Usually one forgets that the denture has
its component parts arranged on two
planes of space. The incisors are placed
in transverse or coronal plane while the
buccal segments are on the
anteroposterior or sagittal plane.


 So when using tip-back bends in the
buccal segments and lingual torque in the
incisor segment, the purpose of which
modification is to effect distal crown
tipping
the degree of tip-back force must
harmonize with the degree of lingual
torque in incisor region ,else one force will
work against the other.

6) When teeth are placed in positions of
mechanical advantage to resist forces
acting on them… Nature being an expert
mechanic herself….offers biological
compensations and adjustments…that
more than counterbalance the loss of
bone stability that results from the initial
tooth movement made for the purpose of
establishing these adjustments of
mechanical advantage.

 Biologist’s studies on the effect of tooth

movement on the bony walls of the alveolar
process: (physiological viewpoint) :
Anchorage was best conserved by the least
amount of tooth movement possible in the areas
desired for resistance of force application.

It was expected to preserve the original bony
trabeculae of alv process, on belief that
undisturbed formation was most resistant to
subsequent attack upon it by appliance
adjustment.

 In the Tweed technique, teeth are shifted for

establishing distal and lingual axial inclination
and to move the mandibular incisors onto the
ridge.

 When properly prepared and bound together by
proper edgewise archwire adjustments, this
anchorage unit is far more stable than the
anchorage arranged according to the idea of
biologists.

 This is both mechanical and biological (the new bone

formation taking place coincidental to the tooth changes)
in action.

 When the molar and premolar teeth are in distal axial

inclination and archwire tied into the brackets, forward
tipping of any of these units, that may subsequently take
place ,will exert a downward pressure on the tooth next in
line mesially.
 Resistance to downward pressure on a tooth is believed
to be the greatest of all resisting power because
functional demands require this to be so.

 Hence by adjusting the teeth like in tweed technique this
power will be called into action for anchorage purposes.


 Resistance to
downward pressure
on a tooth is believed
to be the greatest of
all resisting power
because functional
demands require this
to be so.


7) If malocclusion is a manifestation of
forward positioning of the teeth in relation
to their basal bones, then the dental units
will best resist such forward displacement
when the buccal teeth are in distal axial
position and incisor teeth in lingual axial
position.


 The natural forces acting on the dentition have a

constant propelling force acting upon the denture
and this tends to forwardly tip the crowns.

 Such action is made more easy and effective if
buccal teeth are in exaggerated mesial axial
inclination and incisors in labial inclination.

 Therefore this force will be best resisted by

placing the buccal teeth in distal axial inclination
and the incisor teeth in lingual axial inclination .

 In this Tweed technique we place teeth in such
strategic positions.


8) by Robert H.W.Strang ,Will M.Thompson
Every malocclusion exemplifies a denture
that is stabilized by balanced muscular
forces and this muscular balance must be
preserved in treatment if stability in the
end result is to be attained .


 A deformed denture is maintained in its state by
balancing forces emanating from its
environmental muscles.
 There is a muscular balance inherent to each
particular denture/dentition.
 To have a stable result in addition to placing
teeth over their osseous foundation, one must
aim to preserve muscular balance present in
original malocclusion.

1.That practically all malocclusions are
characterized by a forward placement of
teeth in relation to their basal bones
2)That the establishment and maintenance
of stable anchorage is the fundamental
factor in successful orthodontic treatment
and should be the initial concern of the
operator.

3)That the teeth, like inanimate objects, best
resist the force of displacement when
tipped to the angulation that offers the
most advantageous mechanical
resistance against the pull of dislodging
forces.
4)That teeth are most readily moved when
their property and power of mechanical
resistance has been primarily reduced.

5)That 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.


6) When teeth are placed in positions of
mechanical advantage to resist forces
acting on them… Nature being an expert
mechanic herself….offers biological
compensations and adjustments…that
more than counterbalance the loss of
bone stability that results from the initial
tooth movement made for the purpose of
establishing these adjustments of
mechanical advantage.

7) If malocclusion is a manifestation of
forward positioning of the teeth in relation
to their basal bones, then the dental units
will best resist such forward displacement
when the buccal teeth are in distal axial
position and incisor teeth in lingual axial
position.


8. Every malocclusion exemplifies a denture
that is stabilized by balanced muscular
forces and this muscular balance must be
preserved in treatment if stability in the
end result is to be attained .


 Dr.Tweed did not make major changes
from how Dr.Angle used edgewise
appliance.
 He moved the teeth using the same arch
wire modifications that were taught to him
by Dr.Angle, however he used certain
modifications/bends in a much more
exaggerated form and much more
frequently.


 He used round arch wires more often.
 He used newly adjusted archwires b/t
appointments during treatment than
maintaining the original archwire from start
to finish.This allowed accurate control of
tooth movement


THE TWEED TECHNIQUE


Tweed technique
Dr.Tweed divides his treatment routine into three phases :
1.Anchorage preparation : consists of 2 procedures
a) placing the mandibular incisors over their basal bone
and giving them a lingual axial inclination by virtue of
lingual tipping AND
rearranging the axial positions of the buccal teeth,
including the second molars, if possible to best resist any
forward displacement ,. This is done by giving a distinct
distal axial inclination ,gaining complete bracket seating in
every tooth and then finally binding all the component
elements of the denture into one unit by firmly tying back
the arch wire to the molar sheath.

TWEED TECHNIQUE
step 1:ANCHORAGE PREP contd.
b) Changing the axial inclination of the
maxillary teeth especially the incisors, to
render their resistance to distal movement
less effective ,particularly in class II div I.


TWEED TECHNIQUE:STEP 2
2. Enmass movement whereby
malrelationship of the two dentures is
corrected and normal inclined plane
adjustment gained.


Tweed technique : step 3
3. Establishing correct denture form and
completing treatment objectives.


Tweed technique—in brief
1.All teeth banded with bracket bands (staples)

Light round wire 0.016 used for gaining universal bracket
engagement
(levelling =teeth brought to common horizontal level)

any faulty bracket placement corrected


Step I
 Gaining universal bracket

engagement.
 Levelling
 molar tipping bends 45 deg
placed.
no attempt made to gain space
for blocked out teeth till
resilient 0.021x0.025 wire and
class III elastics can be used
to avoid forward movement of
teeth crowns.
space should always be
gained by distal movemet of
tooth crowns.

2. Upper and lower 0.018 s.s adjusted to engage all brackets.
archwire formation:
req length of wire…arch form given…circular molar loop stop
made…wire place in molar sheaths,canine markings,central
and midline markings made.
canine curves given,incisors segment curved to confirm
curvature of the denture.
passive adjustment to buccal teeth;no bends
molar tipping bends 45 deg placed.
no attempt made to gain space for blocked out teeth till
resilient 0.021x0.025 wire and class III elastics can be used to
avoid forward movement of teeth crowns.
space should always be gained by distal movemet of tooth
crowns.
Archwire tied to all brackets (2-3weeks)
Retied till bracket engagement gained

3. 0.02 round wire formed and bracket
engagement gained.(6weeks)
4 .Resilient edgewise archwire 0.021x0.025
used for bringing about tooth movements
fabricaiton:
markings made…bent to ideal arch form
no bayonet bends given now


 Resilient edgewise archwire

0.021x0.025
used for bringing about tooth
movements
 in maxillary wire- moderate lingual
torque given in canine and buccal
segment; in the mandibular strong
lingual torque given in the buccal
segment.
in the incisor segment of both either
lingual or labial crown torque
depending on what will gain passive
bracket engagementproper deg of tip
back bend given in anchor molar.
Wire shaped in incisor and canine
region; again torque checked for
harmony.
markings for bayonet bends
made,bends palced
15 deg distal tip + lingual bend( to
prevent rotaiton due to lingual torque
in buccal segment) placed at anchor
molar.
thus universal bracket engagement
is gained.

5. No more tooth movement tried till class III
elastics can be used, for this anchorage
must be prepared in the maxiallry denture
first.
maxillary denture anchor preparation:
All teeth banded…0.018 adjusted (6week)
0.020 adjusted..20deg distal tiping bend at
anchor molar (6-9weeks)..


 0.021x0.025 wire…marked

lingual torque in buccal
segments placed, slight lingual
torque in anterior segment
placed,20 deg distal tip bend
(anchor molar)…very mild
distal tip bends at canine,
premolar and 1st molar area.
hooks placed on archwire for
occipital anchorage
(to avoid forward root
movement due to distal tip
bend and lingual torque)….6-9
weeks


Maxillary anchor preparation
0.025x0.028 stabilizing wire ….first passive
bracket engagement gained by placing the same
deg if tip back bends and lingual torque as in the
previous wire..strong tip back bend + lingual
bend in anchor molar area…
next appointment tip back bends stepped up…
anchor tip back bends stepped up…torque in
incisor segment increased…torque in buccal
segmetns increased to be in harmony with
anterior torque..headgear to be worn atleast
10hr in night.
MAXILLARY ANCHORAGE PREP complete .

 Mandibular archwire: mandibular anchor
preparation:


Mandibular anchor preparation
 0.021x0.025 ….10 deg tip back

canine ,premolar and molar area
placed…greater tip back placed at
anchor molar….lingual torque
increased in incisor area…balance
b/t distal tip in buccal segment and
lingual torque in anterior segment
maintained
 keeping in mind the fact that
movement of incisor roots ,under
the influence of lingual torque is
more easily and quickly effected
than is the distal and lingual tipping
of tooth crowns in the denture
under the influence of the
intermaxiallry elastics…it is
considered good to maintain
incisor lingual torque at a lesser
degree than distal tiping bends. if
required the torque can later be
stepped up.

class III elastic hooks soldered on
archwire (occlusal surface)
two kinds of class III elastics
given-light and heavy..day time
and night time wear.(patient
warned about the chinless
expression that may be
observed…transient and will
disappear when class II elastics
are subsequently used to move
maxillayr teeth distally)
Unless the class III elastics are
worn steadily the mandibualr
teeth roots will move forward
instead of their crowns moving
distally….if head gear not worn,
the maxillary anchorage will be
weakened and forward
displacement of teeth will take
place…so patient co-operation
very important.

 Mandibualr anchor prep continued: Distal tipping

bends stepped up once in 6weeks…lingual torque
proportionately stepped up…new wire used if
deformed.
 Mandibular anchorage and correct denture locaiton
may be considered satisfactorily established when
the incisor roots overlie the basal ridge and their
crowns exhibit a distinct lingual axial inclinaiton
and
 when the canine, premolar and molar teeth are in
distinct distal axial inclination .
 the distal axial inclination of anchor molars should
be greater than other buccal teeth.

Step II
6. Enmass movement to produce normal
inclined plane relationship:
.


0.0215x0.028 that is in use in the
maxiallry arch when class III
elastics
were worn are replaced by
0.021x0.025 resilient wire…
harmonious tip
back bends given. lingual torque
and lingual molar bends
duplicating the
ones in previous heavy wire
given.. molar stops and
intermaxiallry elastic
hooks soldered…tied to brackets
to remain passive for 3
weeks....active
tip back bends are now
given...lingual torque increased
slightly in incisor
area…class II elastics applied…
occipital anchorage
discontinued

mandibular anchorage watched
carefully…molar tie ligatures
retied at every appointment…
at any sign of anchorage
giving away...tip back bends,
lingual torque, lingual bend
increased in anchor molar…
in other teeth proportionately
tip back bens and torque
increased….
still if
anchor loss occurs…occipital
anchorage applied to
mandibular denture.


TWEED – MERRIFIELD
PHILOSOPHY


The appliance
 Simplicity, efficiency,comfort
hygeinic,versatality,esthetic.


 Neutral (no tip ,torque or inout) 0.022 slot dimension

 Posterior bands
 Anterior mesh pads
 With single ,double width

0.022 brackets on six anterior
teeth
 Intermedeate single width
brackets on premolar bands
 Twin brackets on 1st molar
 Heavy 0.022 edgewise tubes
with mesial hooks on 2nd molar
bands









Arxhwires:
0.017 x0.022
0.018 x0.025
0.019 x0.025
0.020 x 0.025
0.0215 x0.028 inches

 Different wire dimensions allow greater versatality and

allow sequential application of forces at diff stages.
 Objective is to enhance tooth movement and control with
proper edgewise wire.

Auxiliaries used:
 Elastics
 Directionally oriented headgear:
high pull J-hook headgear
straight pull J- hook headgear
 Patient compliance imperative


1 order bends
st

 Knowledge of action and interaction and
reaction of teeth to bends crucial.

 Action and reaction of 1st order bends bring
about contraction or expansion

 Interaction of the 1st order bends can affect
3rd

2 order bends
nd

In mandibular arch:
 These used in the posterior segment of
mandibular arch are antagonistic to teeth in
anterior segment.
 If proper directional control not used, and care
not taken in application of these bends in a
sequential manner…vertical control of anterior
teeth will be lost.
 These apply labial crown torque on the
incisors..which is not desirable. This fact must
be given careful consideration during archwire
fabrication.

2 order bends
nd

 In maxillary archwire:
 Second order bends in the posterior

segment are complementary to teeth in
the anterior segment…
 The reaction of the tipping forces
produced by the 2nd order bends in the
posterior segment intrudes the maxillary
incisors and gives a lingual root torque
effect to these teeth.

2nd order bends


3 order bends
rd

 Mandibular arch:
 3rd order bend reaction in mandibular archwire is







complementary to all teeth.
Objective is to place some degree of lingual
crown torque on all mandibular teeth.
Posterior and anterior segment work together in
action, reaction and interaction.
Ideal 3rd order bends in mandibular segment:
Incisor : -7deg
Canines : -12 deg
2nd premolars and molars : -20 deg

 Maxillary arch:
 Conversely 3rd order bends here are antagonistic.
 Anterior segment needs no torque (0 deg) or slight
lingual root torque.
 Posterior segment needs lingual crown torque:
 Canines and 1st premolar : -7 deg
 Second premolars
: -12 deg

 Application of opposite torque force simultaneously in diff
segments of same arch not wise.

 In the maxillary arch it is best to apply active 3rd order

bends sequentially and in only one direction at a time.

 Using Tweed’s concepts as foundation

Merrifield developed force systems to
simplify the use of edgewise appliance:
 Tweed used 12 sets of archwires during
treatment of a patient ; reduced to 4-5 sets
 Merrifield’s sequential directional force
technology.
 Directionally controlled precision arch wire
manipulation.

TWEED MERRIFIELD
PHILOSOPHY
Essentialy 5 concepts compose the

Essentialy 5 concepts compose the
philosophy:
1) Sequential appliance placement
2) Sequential/individual tooth movement
3) Sequential mandibular anchorage preparation
4) Directional force including control of vertical
dimension which will enhance mandibular
response
5) Proper timing of treatment

1) Sequential applaince placement :
 1st premolar extraction case: 2nd molars, 2nd premolars,
canines banded, centrals banded/bonded ; 1st molars left
unbanded
Advantage : Less traumatic
Easier
Less time consuming
Allows greater efficiency in arch wire
action (longer inter bracket span in posterior
seg)
Larger dimension wire can be applied that is
less subject to distorsion.
 Once banded teeth respond to the force of arch wire
additional teeth banded , sequence :
After 1st appointment  maxillary 1st molars banded
After 2nd appointment  mandibular 1st molars banded
At 3rd/4th appointment lateral incisors bonded

 Initial archwires

placed
 1st molars not banded


2) Sequential tooth movement:
Tweed had advocated enmass tooth
movement
Advantage : Rapid and precise tooth
movement because they
are moved individually/in
small units

Sequential tooth movement


3) Sequential mandibular anchorage
preparation: developed by MERRIFIELD
“10 – 2” system.
Tweed : Enmass anchor preparation;all
compensation bends placed at one
time in the archwire and class III elastics
used for support ----result :
Labially flared and intruded
mandibular incisors

Merrifield technique –
`10 – 2’ Force systems(10 ten teeth used as
anchor units to tip 2 teeth)
+
High pull head gear for support rather
than class-III elastics
Tooth movement is controlled, sequential and
precise….mandibular anchorage can be
prepared quickly and easily by tipping only two
teeth at a time to their anchor prepared position.

10 -2 force system
 10-2-6
 First molar tipped
tipped to Anchor
prepared position


 Initial step of SMAP : IInd molar is tipped to its






desired anchorage prepared position.
Space closed b/t Ist and IInd molars
Compensating bend placed mesial to the IInd
molar to maintain its tip
Ist molar is tipped to anchor prepared position.
Compensating bend placed mesial to molar to
maintian tip
IInd premolar tipped distally to APP.

Tweed- merrifield philosophy contd.
4) Directional force : hallmark of modern
Tweed-Merrifield edgewise treatment is
use of directional force to move teeth.
Controlled forces which place teeth in the most
harmonious relationship with their environment


 Critical to employ force system that controls the
mandibular posterior teeth and maxillary anterior
teeth

 Control of vertical dimension crucial for the
upward and forward force system to be a reality
 to control vertical dimension we should control the
Mandibular plane, palatal plane and occlusal
plane.


Upward and forward force system
 Resultant force vector

of all forces should be
upward and forward,
giving opportunity for
favourable skeletal
change, especially in
dento alveolar
protrusion class II
malocclusion correction


Upright mandibular incisors allows
maxillary incisors moved up and
back
 Mandibular incisors

upright over basal
bone needed so that
the maxillary incisors
can be moved distally
and superiorly


Downward and backward force
system
 If point B is allowed to

move down, mandibular
incisors are tipped off the
basal bone and maxillary
incisor drops down and
back instead of being
moved up and back.

 This leads to a patient

with lengthened face, a
gummy smile,
incompetent lips and a
more recessive chin.


5. Timing of treatment:
Treatment should be initiated at the time
when treatment objectives can be most
readily accomplished.
This may mean interceptive in the mixed
dentition, or waiting for second permanent
molar eruption before starting active
treatment.

STEPS OF TREATMENT
with Tweed – Merrifield Technique


STEPS OF TREATMENT
CLASSIC TWEED MERRIFIELD
EDGEWISE DIRECTIONAL FORCE
TREATMENT can be organised into four
force systems :
1) Denture preparation
2) Denture correction
3) Denture completion
4) Denture recovery

1.DENTURE PREPARATION
(apporx 6 months)
OBJECTIVES:
a) Leveling
b) Individual tooth movement and rotation
correction
c) Retraction of both maxillary and
mandibular canines
d) Preparation of terminal molars for stress
resistance

DENTURE PREPARATION
continued..
Technique –
sequential banding/bonding of teeth
0.018 x 0.025” resilient mandibular arch wire
0.017 x 0.022” resilient maxillary arch wire
- loop stops flush with second molar tubes
- Mandibular 2nd molar 150 effective distal tip
- Maxillary 2nd molar 50 effective distal tip

DENTURE PREPARATION
continued..
-2nd premolar offset bend mesial to 2nd premolar
bracket placed to prevent canines from
expanding
- 3rd order bends passive in both upper and lower
- High pull J-hook head gear used to retract
maxillary and mandibular canines
After 1st month terminal molar tip increased to
maintain an effective 150 tip as tooth tip distal
- Maxillary 1st molars banded, J hook head gear
continued for canine retraction

Denture preparation
 Initial archwires
0.017 x 0.022 resilient
maxillary arch wire
0.018 x0.025 resilient
mandibular arch wire
J-hook hook head gear for
canine retraction.

 Maxillary molars
Banded after 1st
month of treatment
 Arches getting
levelled off
 Canine retraction
with J-hook
headgear continued

DENTURE PREPARATION
continued
As canines retract and arches are levelled ,the
lateral incisors are ligated
Power chain force used to aid canine retraction
At each visitarch wires removed co-ordinated, checked for
1st,2nd 3rd order bends and religated
- Canine retraction continued with power
chain and HG force

Denture preparation
 Canine retraction
continued:
using J-hook
headgear and power
chain


End of Denture preparation
 Terminal
molar anchorage:
The mandibular
terminal molar should
be tipped to
anchorage
prepared position at
the end of denture
preparation.

END OF DENTURE PREP
 Full dentition bracketed and leveled
 Canines retracted , all rotations corrected
 Mandibular terminal molars tipped distally
into anchor prepared position


MERRIFIELD MODIFICATION in
denture prep
Mandibular arch 
 Start with 0.016” with incisal curvature,
bent-in loop stops flush with molar tube
 200 distal tip for 2nd molar (Tweed-150)
 If progress slow use 0.018” wire
Maxillary arch
 Distal tip 100 (Tweed-50)
 0.018” and 0.020” arch wires inserted about 1 month
after their counter parts in their mandibular arch in
contrast to simultaneous placement of maxillary and
mandibular arch wires in classic Tweed technique

2.DENTURE CORRECTION
MANDIBULAR ARCH
OBJECTIVES:
1. Retraction and up-righting of lower
incisors to their planned positions
2. Completion of space closure
3. Achievement of posterior and mid arch
axial inclinations that will permit proper
functional co-ordination with the maxillary teeth

Denture correction :space closure
 Mandibular wire:

0.019 x0.025 with 6.5mm
vertical loop distal to
lateral incisor bracket.
 Maxillary archwire:
0.020 x0.025 with 7mm
vertical loop.
 Loop stops immediately
distal to brackets of first
molars
 Loop stop in mandiblar
arch wire incorporates a
compensation to maitain
15deg terminal molar tip

Denture correction
 Closing loop application:
maxillary and mandibular
closing loops are used to
close spaces mesial to
the distalized canines
 Vertical support in
maxillary rch through J
hook HG (hook b/t central
and lateral)
 Vertical support for
mandibular anteriro teeth
through anterior vertical
elastics

Denture correction: space closure
complete
 After space closure is
complete, mandibular
arch is level,curve of
occlusion in maxillary
arch maitained and
the terminal molars
remain
tipped to an
anchorage prepared
position.

SEQUENTIAL MANDIBULAR
ANCHORAGE PREPARATION
 Sequential tooth movement concept Arch wire exerts active force on only 2
teeth, while remaining passive to other
teeth in the arch. Thus, remaining teeth
act as stabilizing anchor units as 2 teeth
are tipped.(“10-2” anchorage system)


1 step of SMAP
st

SMAP is initiated
during Denture prep
of treatment by
tipping 2nd molar to
150 distal inclination


Mandibular anchorage preparation
 After space closure in
mandibular arch one
checks to make sure the
arch is level and 2nd
molars are tipped to
15deg distal inclination
(Readout)

 10-2-6…first molar
tipped to its anchrage
prepared position

 0.019 x0.025 archwire with loop

stops flush agianst 2nd molar tubes
fabricated.

 1st and 3rd order ideal bends are
incorporated

 Gingival hooks for high pull J hook
HG soldered distal to central
incisor bracket.

 To tip 1st molar into APP,10deg

distal tip placed 1mm mesial to 1st
molar brackets.
 Compensating bend to maintian
15deg 2nd molar tip placed just
mesial to loop stop.


 10-2-6:
 The second molars are now part of anchor
unit /stabilizing unit and the first molars are the
two teeth which receive the action of directional
forces and archwire.

 After 1 month arch wire removed, readout
should show 5-80 distal inclination of 1st molars,
2nd molars should continue 150 read out

Mandibular anchorage preparation
 Second premolar is tipped to its
anchorag
prepared position.
10-2-5.

 Third and final step of SMAP –
50 distal tip 1mm mesial
to 2nd premolar bracket,
compensating bend
between 2nd premolar and 1st
molar to maintain 1st molar in
APP


SEQUENTIAL MANDIBULAR
ANCHORAGE PREPARATION
continued….
 At end of MAP, read-out will show :
2nd molar = 150 distal axial inclination
1st molar = 5-80
2nd premolar = 0-30


CLASS II FORCE SYSTEMS
 A different system of forces may be used
in patients with end-on or full cusp class II
dental relationship.
 A final diagnostic decision made and
treatment planned based on – the ANB
rel, maxillary posterior space analysis and
patient co-operation…using the following
guidelines:

1. If the maxillary 3rd molar is missing or if ANB<= 5deg

and patient is cooperative… best prognosis. If 3rd molar
erupting then its best to remove it to facilitate distal
movement of maxillary teeth.

2.

If patient is cooperative, has a mild class II dental rel,
normal vertical skeletal pattern, ANB 5-8deg and
normally erupting 3rd molars…then advantageous to
extract 2nd molars.

3.

If ANB >10deg, poor patient cooperation, 3rd molars
present…after maxillary and mandibular first premolar
extraction space closure, either first molar extraction or
surgical correction considered.( poor prognosis)

Correction of class II dental
relationships
Mandibular anchor prepared.
 Mandibular 0.0215x0.028 stabilizing
archwire fabricated with ideal first, second
and third order bends. Wire passive to all
brackets. Gingival spurs soldered distal to
lateral incisor brackets. Wire seated and
ligated. Terminal molar tied tightly to loop
stop.

2 molar distalization0.020x0.025
 Maxillary archwire
nd







wire with closed helical bulbous
loops bent flush against the
second molar tubes.
Ideal 1st, 2nd and 3d order bends
placed.
Molar segment 7 deg lingual
crown torque
Gingival spur soldered to
archwire distal to 2nd premolar
bracket.
Gingival high pull Headgear
hooks soldered distal to central
incisor brackets.
Class II “lay on “ hooks with
gingival extention for anterior
vertical elastics soldered distal
to lateral incisor brackets.


2 molar distalization
nd

 Closed helical bulbous

loops opened 1mm on
each side and arch wire
ligated in place.
 Class II elastics of 8
ounces worn.
 Anterior vertical elastics
worn
 High pull headgear worn.


 In about a month time the maxillary 2nd
molar moves distally.helical bulbous loop
reactivated until second molars have a
class I dental relationship.


Class II force system:denture
correction: maxillary 1st molar
distalization
 Coil spring 1.5 times

distance b/t molar and
premolar bracket
trapped mesial to
1stmolar bracket.
 E –chain from distal
bracket of 1st molar to 2nd
molar.
 Class II elastics,
headgear,anterior vertical
elastics worn.

Class II force system:denture
correction: maxillary 1st molar
distalization
 Maxillary first molar
distalization
 1st molars moved
distally overcorrected
into an class I dental
relationship.


Class II force system :Denture
correction : maxillary 2nd premolar
and canine distalization
 Spur distal to 2 premolar
nd

removed.
 The coil spring is moved
mesially and compressed
b/t the lay on hook distal
to lateral incisor and
canine bracket.
 Subsequently the 2nd
premolars and canines
are moved
distally with elastic chains
and head gear force.


By four months of active treatment, with monthly
reactivation, posterior teeth should attain an
overcorrected class I rel.
Mandibular anchorage not strained if sufficient
maxillary posterior denture area available and
anterior vertical elastics worn.


Denture correction:
Maxillary Anterior space closure

 0.020x0.025 maxillary arch





wire with 7mm closing loops
distal to lateral incisors.
Ideal 1st, 2nd and 3rd order
bends placed.
Gingival headgear hooks
soldered distal to central
incisors.
Closing loops opened 1mm
per visit by cinching the loop
stops to the molar tube.
Milder 4-6 ounce class II
elastics used instead of 6-8
ounces. Anterior vertical
elastics and maxillary head
gear worn.


Maxillary anterior space closure
 After all maxillary

space is closed…
denture correction
completed …denture
ready for next step
DENTURE
COMPLETION.


Denture completion
Mini treatment of malocclusion:
The orthodontist repeats the
force systems that are necessary, until the
original malocclusion is overcorrected:

 Ideal 1st,2nd,3rd order bends placed in 0.0215x 0.028”

resilient arch wires.
 Cephalogram traced to determine final mandibular incisor
position and any minor control of palatal, occlusal and
mandibular planes that may be needed.
 Visual examination done for evaluation of lip line,
maxillary incisor rel ,cusp seating, artistic positioning,
need for lingual root torque of upper incisor .

Denture completion
Maxillary and mandibular
stabilizing archwires,
along with proper
elastics and headgear
force used to complete
orthodontic treatment.


 At end of denture completion








following characteristics should be
readily observed:
Incisors must be aligned.
Occlusion overcorrected to class I
rel.
Anterior teeth edge-edge rel,
minimal incisal guidance.
Maxillary canines and 2nd premolars
locked tightly into class I rel.
Mesiobuccal groove of maxillary 1st
molar must occlude in mesiobucal
groove of mandibular first molar.
Distal cusp of first molar and
second molars must be slightly out
of occlusion.
All spaces must be closed tightly
from 2nd premolars forward.


Denture recovery

One must not strive for ideal final results at end
of treatment, the ideal result will occur after all
treatment mechanics discontinued and after
uninhibited function and other environmental
influences, active in post-treatment period,
stabilize and finalize the teeth positions.

When all bands removed retainers placed this

crucial recovery phase begins.
In this stage, forces involved are those of
surrounding environment, primarily muscles and
periodontium.

Denture recovery
concept of over correction:
if mechanical corrective procedures barely
achieve normal relationships of teeth , relapse is
inevitable…certain changes effected during
treatment will tend to revert toward their original
position.
Tweed- Merrifield posterior disclusion :
This is achieved at the end of treatment
Called as Tweed occlusion is a transient occlusion
state
characterized by disclusion of second molars.

 The mesiolingual cusp of the maxillary first molar is seated in the
central fossa of the mandibular first molar with the mesial inclined
plane of the mesial cusp of the maxillary first molar contacting the
distal inclined plane of the mesial cusp of the mandibular first .

 This allows the muscles of mastication to exert the greatest force on
primary chewing table in the midarch area.

 The slightly intruded distally inclined maxillary and mandibular second
molars now can reerupt to healthy functional occlusion without trauma or
premature contact

 Transient occlusion:

Occlusion must be over
treated to a
class I relaitonship.
 The anterior teeth should
be edge to edge.
 The canines, premolars
and 1st molars must have
solid class I relationship.
 The second molars must
be tipped out of
occlusion.

Final occlusion is
characterized by the
teeth settling into their
most efficient , healthy
and stable positions.


 All bands, except of 1st molars and canines removed,

archwire ligated in both arches
 Mandibular arch :canines ligated to each other
 Maxillary arch, power chain placed from canine bracket to
other,after7days remaining bands removed.

 Muscles of deglutition, mastication and facial expression

are actively involved in determining the final stable ,
esthetic relationship of teeth referred to as functional
occlusion.
 Each individuals own oral environment will determine the
ultimate position of the dentition.Thus overtreatment
allows patient the opportunity for maximal stability and
functional efficiency

Conclusion
Edgewise technique is more than just the

application of headgear forces to cuspids.

It is a group of integrated force systems designed

to place the teeth, individually and collectively, in
positions of physiologic and esthetic harmony with
their environment.

It is designed to achieve individualized tooth

movements and precision to each patient, to
achieve functional occlusion and optimal
esthetics, to shorten treatment duration through
use of sophisticated force systems.

It respects the dimensions of the denture
.

One must discard the idea that a bracket
manufacturer can determine what is best
for orthodontic patients.


Tweed philosophy 2 /certified fixed orthodontic courses by Indian dental academy

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Tweed philosophy 2 /certified fixed orthodontic courses by Indian dental academy