INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

TWEED- MERRIFIELD
EDGEWISE
PHILOS...
CONTENTS
 HISTORY

OF EVOLUTION

 ANGLE’S

VIEW’S
- Angle’s concept of an appliance
- Disadvantages
 TWEED PHILOSOPHY
-...
- Drawback of his philosophy
 TWEED – MERRIFIELD PHILOSOPHY
- Merrifield’s additional contributions
- Four premises of th...
 APPLICATION

OF PHILOSOPHY INTO

PRACTICE
- Five concepts of the treatment philosophy
- Sequential banding and bonding
-...
- Directional force application
- Proper timing of treatment
- Incorporation of first, second , third order bends
- Force ...
 CONCLUSION

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ANGLE
TWEED
MERRIFIELD
LEGACY
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EDWARD HARTLEY ANGLE
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8
ANGLE’S INSPIRATION
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E ARCH APPLIANCE
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10
PIN AND TUBE APPLIANCE
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11
RIBBON ARCH APPLIANCE
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12
EDGEWISE APPLIANCE
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EVOLUTION OF THE
EDGEWISE
CONCEPT
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ANGLE’ VIEWS


HIS CONCEPT OF AN APPLIANCE



DRAWBACKS

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ANGLE’S CONCEPT OF AN APPLIANCE






SIMPLE- push, pull, rotations
STABLE - fixed to teeth
EFFICIENT- provide anchor...
The ribbon arch was not capable
of an en masse tooth movement.
hence this became
his motivation.
The edgewise bracket came...
The archwire was held in position
first by a brass ligature and later
by delicate stainless steel
ligature.The archwire wa...
ANGLE’S EDGEWISE PHILOSOPHY
Incorporated the
NON-EXTRACTION PROTOCOL
therefore closing of spaces in
the posterior segments...
Anteroposterior correction was
difficult to accomplish.
proclination of anterior teeth
was common.
crowns tended to tip me...
Angle found a capable man in
Tweed to continue where
he had left .
Hence the legacy of the edgewise
appliance passed over ...
TWEED
PHILOSOPHY

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22
CHARLES H.TWEED
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23


BRIEF OVERVIEW OF THE CHANGES HE
INTRODUCED



DIAGNOSTIC FACIAL TRIANGLE
ANCHORAGE PREPARATION
GROWTH TRENDS
TWEED PH...
Tweed would over the course of
time revolutionise edgewise
philosophy in a most radical way
Although initially called the
...
He became a legacy for all to follow with his
concept of:
extractions
 uprighting of teeth over basal
bone.
 application...
DIAGNOSTIC FACIAL TRIANGLE

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27
Diagnostic Facial Triangle
angles considered where:


frankfort mandibular plane angle / fma ( 25
degrees)



mandibular...


frankfort mandibular incisor angle / fmia (65
degrees)



point a – nasion – point b / ANB( o to 5
degrees)

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ANCHORAGE PREPARATION
FIRST DEGREE ANCHORAGE PREPARATION
Anchorage preparation not critical
when anb ranges from 0 to 4 de...
SECOND DEGREE ANCHORAGE
PREPARATION
Anchorage preparation necessary as ANB is above
4.5 degrees and facial esthetics not g...
THIRD DEGREE OR TOTAL
ANCHORAGE PREPARATION
ANB not greater than 5 degrees
and bimaxillary protrusion.

Distal tipping of ...
GROWTH TRENDS
TYPE A GROWTH TREND


Characterised by middle and lower face
growing downward in unison with no change
in A...
TYPE A SUBDIVISION


Molar relationship class ii with ANB greater
than 4.5 degrees.



Restrain maxillary growth with Kl...
TYPE B GROWTH TREND


anb 6 to 12 degrees



middle facial height growth faster than lower
facial height.



prognosis ...
TYPE C GROWTH TREND


lower face grows faster than middle face.



mandibular incisor lingual tipping or maxillary
incis...
TYPE C SUBDIVISON


when growth is predominantly horizontal with
a decreased fma angle.



little vertical growth occurs...
HIS PHILOSOPHY :


position and arrange teeth for
maximal facial and dental esthetics and
functional efficiency.



heal...


maximise compensation for less than normal growth
patterns.



position the dentition so that it is in a continual sta...
DRAWBACKS OF THE TWEED
PHILOSOPHY


he concentrated on the antero-posterior & vertical
trend of growth on the basis of wh...


mandibular anchorage was prepared with
class iii elastics and with all compensation
bends placed in arch wire at one ti...
Tweed named Levern Merrifield
as his successor to guide the
rapidly expanding and
successful Tweed study course
in Tucson ...
TWEED- MERRIFIELD
PHILOSOPHY

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LEVERN MERRIFIELD
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









HIS ADDITIONAL CONTRIBUTION
FOUR PREMISES
BROAD PARAMETERS OF THE
PHILOSOPHY
DIFFERENTIAL DIAGNOSIS
FACI...
Merrifield introduced the Tweed Merrifield
philosophy by adding a seventh objective



all clinical objectives must be pu...
the Tweed Merrifield is based on four fundamental
pillars or
premises. they are:


an anterior limit exists.the teeth mus...
broad parameters of the Tweed-Merrifield
philosophy include:



assessing the dimensions of the lower face.



total spa...


sequential tooth movement.



sequential mandibular anchorage
preparation.
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DIFFERENTIAL DIAGNOSIS



facial disharmonies



dental disharmonies



cranial disharmonies



environmental disharmo...
FACIAL DISHARMONIES
THREE FUNDAMENTAL FACTORS
INFLUENCE FACIAL BALANCE:


positions of teeth



skeletal pattern



sof...


tooth position plays a fundamental role in
facial balance.



maxillary incisor position is directly related to
positi...
upper lip thickness is measured
from the greatest curvature of
the labial surface of the central
incisor to vermilion bord...
 total

chin thickness is measured horizontally
from nb line extended to soft tissue pogonion.



UPPER LIP = TOTAL CHIN...
z angle
ideally the z line must be tangent to the chin and the vermilion border
of both lips and should bisect the nose.it...
fmia angle

the fmia should correspond to
an angle of 65 degrees .

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CRANIAL DISHARMONIES

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SNA : 80- 84 DEGREES
pfh
SNB : 78- 82 DEGREES
ANB : 1- 5 DEGREE
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AO- BO : 0-4 MM

x 100 = 69% o...


occlusal plane to frankfort horizontal plane: 8-12
degrees



facial height index
pfh x 100 = 69% of afh.
afh
a range ...
facial height change ratio:

facial height change was assessed during the
course of treatment.

a ratio of two times as mu...
DENTAL DISHARMONIES
TOTAL SPACE ANALYSIS
DIVIDED INTO THREE PARTS:


anterior



midarch

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 ...
ANTERIOR SPACE ANALYSIS

measurement taken from mandibular canine to
canine.also mesiodistal diameter of six anterior
teet...
total chin thickness must equal upper lip
thickness.hence soft tissue balance obtained.


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63
thus the sum of anterior tooth arch surplus or
deficit,lateral
headfilm discrepancy and soft tissue
imbalance is combined ...
MIDARCH SPACE ANALYSIS


includes mandibular first molars and first and
second premolars.



available midarch space: di...


occlusal disharmony: articulate the casts and
use maxillary first premolar as
reference.measure mesially or distally fr...
POSTERIOR SPACE ANALYSIS

measured from the distal of mandibular first
molar to anterior border of ramus along the
occlusa...
variables to be taken into account when
assessing posterior space are:



rate of mesio-occlusal migration of
mandibular ...


time of cessation of ramus resorption.



gender



age.

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the tweed merrifield appliance is
essentially consists of .022
edgewise slots with


double width brackets on the six ant...
APPLICATION OF
PHILOSOPHY INTO PRACTICE

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71









FIVE CONCEPTS OF THE TREATMENT
PHILOSOPHY
SEQUENTIAL BANDING AND BONDING
SEQUENTIAL TOOTH MOVEMENTS
SEQUENT...


DIRECTIONAL FORCE APPLICATION



PROPER TIMING OF TREATMENT



INCORPORATION OF FIRST , SECOND
AND THIRD ORDER BENDS
...


FORCE SYSTEMS:
DENTURE PREPARATION



DENTURE CORRECTION



DENTURE COMPLETION



DENTURE RECOVERY



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

.022 tubes with mesial hooks on the second
molars.

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TWEED MERRIFIELD EDGEWISE APPLIANCE
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

Tweed initally used 12 sets of
archwires.Merrifield reduced it to four to five
sets of arch wires
the dimensions of wir...
FIVE CONCEPTS OF TREATMENT
PHILOSOPHY



sequential banding or bonding.



sequential tooth movement.



sequential man...


directional force application.



proper timing of treatment.
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SEQUENTIAL BANDING OR
BONDING
the terminal molars are banded,the second
premolars and canines.incisors can be either
bande...


longer interbracket length for the
archwire.hence creates a power storage in
the wire that accomplishes the objectives
...
maxillary molars are banded after one month.

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82


Mandibular molars banded after second visit.
Lateral incisors can be banded or bonded depending on
progress.
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SEQUENTIAL TOOTH MOVEMENT
en masse tooth movement not done.
 teeth moved individually or in small units.





advantag...
SEQUENTIAL MANDIBULAR
ANCHORAGE PREPARATION


instead of class iii elastics Merrifield opted for high
pull gear for ancho...
DIRECTIONAL FORCES
This concept led to the evolution of Merrifield’s
‘ sequential directional force
technology’

direction...
 the resultant vector of all force systems must be upward and

forward so that the oppurtunity tfor favourable skeletal c...


for this to be a reality, vertical control is
critical.

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88
TIMING OF TREATMENT
treatment must be initiated at a time when the
treatment objectives can be readily
accomplished.


...
INCORPORATION OF FORCE
SYSTEMS INTO THE PHILOSOPHY

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FIRST ORDER BENDS

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91




these bends provide for bucco-lingual movements of
teeth
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bends are incorporated in the ...
 these

bends provide for expansion or
contraction of the arch as the need arises.

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SECOND ORDER BENDS

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94


these bends provide for mesio-distal tipping of teeth as and when
required.



bends are incorporated in the arch wire...


bends made in the posterior segment of the
mandibular arch are antagonistic to anterior
teeth



labial flaring and in...


second order bends made in the posterior
segment of the maxillary arch are
complimentary to that of anterior segment.

...
THIRD ORDER BENDS

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98
third order bends are given to effect root torque,be it buccal or lingual.

two ribbon arch pliers are utilised.one to hol...


in the mandibular arch,incorporation of torque
is complimentary to the anterior and posterior
segments

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

in the maxillary arch,third order bends prove to be
antagonistic as little or no torque is required in the
anterior seg...


therefore active third order bends are given in
posterior segments sequentially and only in
one direction at any given ...
Evaluation of torque by holding with ribbon arch plier.
Torqued segment will at an angulation .
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FORCE SYSTEMS


Denture preparation



Denture correction



Denture completion



Denture recovery

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DENTURE PREPARATION
OBJECTIVES







leveling
individual tooth movement and rotation
correction
retraction of both ma...


this stage requires approximately six
months.



.017x.022 maxillary arch wire.



.018x.025 mandibular arch wire.
ww...
loop stops must be flush with the second molar tubes.
mandibular second molar receives a 15 degree effective distal tip.
m...
high pull headgear incorporated to retract the canines.
adverse effect: canines tend to expand out of the alveolar trough ...
as canines retract and arches level,lateral incisors can
be banded or bonded.
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109
Power chains can be used to retract the
canines.
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110






at end of denture preparation:
all dentition must be fully bracketed and
levelled.
canines should be retracted.
...
DENTURE CORRECTION



continuation of sequential mandibular
anchorage preparation.



the class ii force system.
www.ind...
spaces closed with maxillary and mandibular closing
loops supported by j hook headgear attached to
hooks soldered between ...
arch wire changes
 maxillary: .020x.025 with 6.5mm vertical
loops.
 mandibular: .019x.025 with 6mm vertical
loops.

www....


loop stops immediately distal to brackets of first molars.



loop stop in mandibular archwire incorporates compensati...
end objectives prior to mandibular anchorage preparation would be :
obtain space closure in both arches.
maintain curve of...


level mandibular arch.



maintain 15 degree distal tip of second molar.
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117
SEQUENTIAL MANDIBULAR
ARCH PREPARATION


employs a 10-2 anchorage system.
advantages:



quick controlled response



s...




after checking that :
the mandibular arch is level.

the second molars are tipped to a 15 degree
angulation.

www.in...
a readout is obtained whereby the mandibular
archwire is removed and a plain archwire is inserted
into the second molar tu...
the second step of sequential mandibular
preparation is now initiated.


another .019x .025 archwire is fabricated with
l...
10 degree distal tip placed 1mm mesial to first premolar brackets.
a compensating bend placed to maintain 15 degree tip at...
the third and final step of mandibular anchorage preparation is
initiated.


a 5 degree distal tip placed mesial to secon...


the second molar become part of stabilising
unit.first molar is the recipient of directional
forces.



for ideal resp...
the second premolars now become the
recipients of the
10-2 system.
 again arch wire is at angulation to second
premolar b...


at the end readout must show:



second molars at 15 degree



first molars at 5 to 8 degree



second premolars at ...
end objectives of treatment of class i
malocclusion are:


complete space closure in both arches.



sequential anchorag...


enhanced curve of occlusion in the maxillary
arch.



class i intercuspation of canines and
premolars.

www.indiandent...


mesiobuccal cusp of maxillary first molar
should fit into mesiobuccal groove of
mandibular first molar.



the distal ...
CLASS II FORCE SYSTEM
applicable for cases with an end-on or full
step class ii relationship of the buccal
segments.



...
GUIDELINES FOLLOWED IN TREATING



if anb <5 degree and maxillary third molars
missing, class ii force systems work best ...


anb is 5 to 8 degrees,class ii cusp
relationship,cooperative patient. extraction of
second molars is advantageous.the f...


anb > 10 degrees ,patient compliance is
questionable,first molar removal or surgical
correction should be considered.

...
maxillary : .020x.025 with closed bulbous loops bent
flush against the second molar tubes.
mandibular: .021x.028 stabilisi...
CLASS II FORCE SYSTEM
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135
after the force system is employed for a month or so


the bulbous loops are activated again to 1 mm.



.030 sliding ji...
after four months of treatment with monthly
reactivation, an over treated class i
relationship is achieved.


refabricate...


class ii forces reduced to 4 to 6 oz.anterior
elastics and headgear to be used in
conjunction with elastics.
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COMPLETION OF THE CLASS II FORCE SYSTEM

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139
DENTURE COMPLETION



maxillary and mandibular archwires progressed to .021x .o28.



light class ii elastics maintained...


progress cephalogram and tracings done to
evaluate final mandibular incisor positions
and minor control of palatal,occl...


tracings would also reveal requrement of
lingual root torque in maxillary incisors.



force systems are repeated if o...


after over correction,final artistic bends and
cusp seating forces given to provide quality
and detail.

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END OBJECTIVES



incisors must be aligned.



occlusion overtreated to class i relationship.



anterior teeth must be...


mesiobuccal cusp of maxillary first molar
must occlude in the mesiobuccal groove of
mandibular first molar.

www.indian...


distal cusps of first and second molars must
be out of occlusion.



all spaces must be closed tight from second
premo...
DENTURE RECOVERY



all treatment mechanics are discontinued to enable ideal results.



all bands except for canines an...


canines ligated to each other in mandibular
arch.



for the maxillary arch ,power chains given for
canines.

www.indi...


after seven days, remaining bands removed
and retainers placed.



recovery occurs during this period when
function se...
CONCLUSION
‘ NOTHING WORTHWHILE EVER DEPARTS’

It firmly stood the test of time.
Modifications were made from time to time...
THANK YOU

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151
REFERENCES


Graber and Vanarsdall 2nd and 3rd editions



Clinical Orthodontics – Charles Tweed

www.indiandentalacadem...
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153
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Tweed merrifield edgewise phylosophy /certified fixed orthodontic courses by Indian dental academy

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Transcript of "Tweed merrifield edgewise phylosophy /certified fixed orthodontic courses by Indian dental academy "

  1. 1. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com TWEED- MERRIFIELD EDGEWISE PHILOSOPHY www.indiandentalacademy.com 1
  2. 2. CONTENTS  HISTORY OF EVOLUTION  ANGLE’S VIEW’S - Angle’s concept of an appliance - Disadvantages  TWEED PHILOSOPHY - Brief overview of changes - Diagnostic facial triangle - Growth trends www.indiandentalacademy.com 2
  3. 3. - Drawback of his philosophy  TWEED – MERRIFIELD PHILOSOPHY - Merrifield’s additional contributions - Four premises of the philosophy - Differential diagnosis: facial dental cranial environmental www.indiandentalacademy.com 3
  4. 4.  APPLICATION OF PHILOSOPHY INTO PRACTICE - Five concepts of the treatment philosophy - Sequential banding and bonding - Sequential tooth movements - Sequential mandibular anchorage preparation 10 – 2 system Cl – ii force systems www.indiandentalacademy.com 4
  5. 5. - Directional force application - Proper timing of treatment - Incorporation of first, second , third order bends - Force systems Denture preparation Denture correction Denture completion Denture recovery www.indiandentalacademy.com 5
  6. 6.  CONCLUSION www.indiandentalacademy.com 6
  7. 7. ANGLE TWEED MERRIFIELD LEGACY www.indiandentalacademy.com 7
  8. 8. EDWARD HARTLEY ANGLE www.indiandentalacademy.com 8
  9. 9. ANGLE’S INSPIRATION www.indiandentalacademy.com 9
  10. 10. E ARCH APPLIANCE www.indiandentalacademy.com 10
  11. 11. PIN AND TUBE APPLIANCE www.indiandentalacademy.com 11
  12. 12. RIBBON ARCH APPLIANCE www.indiandentalacademy.com 12
  13. 13. EDGEWISE APPLIANCE www.indiandentalacademy.com 13
  14. 14. EVOLUTION OF THE EDGEWISE CONCEPT www.indiandentalacademy.com 14
  15. 15. ANGLE’ VIEWS  HIS CONCEPT OF AN APPLIANCE  DRAWBACKS www.indiandentalacademy.com 15
  16. 16. ANGLE’S CONCEPT OF AN APPLIANCE      SIMPLE- push, pull, rotations STABLE - fixed to teeth EFFICIENT- provide anchorage DELICATE - accepted by tissues INCONSPICUOUS - esthetic www.indiandentalacademy.com 16
  17. 17. The ribbon arch was not capable of an en masse tooth movement. hence this became his motivation. The edgewise bracket came into existence in 1928.the bracket slot was placed horizontally with a rectangular slot having an .022 by .028 inch dimension. www.indiandentalacademy.com 17
  18. 18. The archwire was held in position first by a brass ligature and later by delicate stainless steel ligature.The archwire was gold archwire. The new design provided more accuracy and a more efficient torquing mechanism. www.indiandentalacademy.com 18
  19. 19. ANGLE’S EDGEWISE PHILOSOPHY Incorporated the NON-EXTRACTION PROTOCOL therefore closing of spaces in the posterior segments was a problem. www.indiandentalacademy.com 19
  20. 20. Anteroposterior correction was difficult to accomplish. proclination of anterior teeth was common. crowns tended to tip mesially. www.indiandentalacademy.com 20
  21. 21. Angle found a capable man in Tweed to continue where he had left . Hence the legacy of the edgewise appliance passed over from Angle to Tweed with these last words.. ‘ I HAVE FINISHED MY WORK,IT IS AS PERFECT AS I CAN MAKE IT.’ www.indiandentalacademy.com 21
  22. 22. TWEED PHILOSOPHY www.indiandentalacademy.com 22
  23. 23. CHARLES H.TWEED www.indiandentalacademy.com 23
  24. 24.  BRIEF OVERVIEW OF THE CHANGES HE INTRODUCED  DIAGNOSTIC FACIAL TRIANGLE ANCHORAGE PREPARATION GROWTH TRENDS TWEED PHILOSOPHY DRAWBACK OF HIS PHILOSOPHY     www.indiandentalacademy.com 24
  25. 25. Tweed would over the course of time revolutionise edgewise philosophy in a most radical way Although initially called the ‘traitor of Angle’, by his advocacy of first premolar extractions which was deemed a heresy back then…….. www.indiandentalacademy.com 25
  26. 26. He became a legacy for all to follow with his concept of: extractions  uprighting of teeth over basal bone.  application of cephalometrics.  diagnostic facial triangle.  anchorage preparation.  serial extraction in mixed dentition.  growth trends  www.indiandentalacademy.com 26
  27. 27. DIAGNOSTIC FACIAL TRIANGLE www.indiandentalacademy.com 27
  28. 28. Diagnostic Facial Triangle angles considered where:  frankfort mandibular plane angle / fma ( 25 degrees)  mandibular incisor plane angle / impa ( 90 degrees) www.indiandentalacademy.com 28
  29. 29.  frankfort mandibular incisor angle / fmia (65 degrees)  point a – nasion – point b / ANB( o to 5 degrees) www.indiandentalacademy.com 29
  30. 30. ANCHORAGE PREPARATION FIRST DEGREE ANCHORAGE PREPARATION Anchorage preparation not critical when anb ranges from 0 to 4 degrees and facial esthetics is good. Terminal mandibular molars must be just upright to prevent elongation by class ii elastics. www.indiandentalacademy.com 30
  31. 31. SECOND DEGREE ANCHORAGE PREPARATION Anchorage preparation necessary as ANB is above 4.5 degrees and facial esthetics not good. Distal ridge of terminal molars must be tipped to gum level and direction of class ii elastics must be greater than 90 degrees so as to further depress it. www.indiandentalacademy.com 31
  32. 32. THIRD DEGREE OR TOTAL ANCHORAGE PREPARATION ANB not greater than 5 degrees and bimaxillary protrusion. Distal tipping of terminal second molars to below gum level.First molars and second premolars also distally tipped to augment anchorage. www.indiandentalacademy.com 32
  33. 33. GROWTH TRENDS TYPE A GROWTH TREND  Characterised by middle and lower face growing downward in unison with no change in ANB.  If ANB not more than 4.5 degrees,no treatment indicated. www.indiandentalacademy.com 33
  34. 34. TYPE A SUBDIVISION  Molar relationship class ii with ANB greater than 4.5 degrees.  Restrain maxillary growth with Kloehn headgear .  Prognosis is good.  Treatment completed in 15 to 21 months. www.indiandentalacademy.com 34
  35. 35. TYPE B GROWTH TREND  anb 6 to 12 degrees  middle facial height growth faster than lower facial height.  prognosis poor.  all four first premolar extraction and kloehn headgear  treatment time 36 to 42 months. www.indiandentalacademy.com 35
  36. 36. TYPE C GROWTH TREND  lower face grows faster than middle face.  mandibular incisor lingual tipping or maxillary incisor labial flaring can occur.  cuspid to cuspid lingual bar with maxillary retainer given.  prognosis excellent  Treatment time 10 to 15 months. www.indiandentalacademy.com 36
  37. 37. TYPE C SUBDIVISON  when growth is predominantly horizontal with a decreased fma angle.  little vertical growth occurs. www.indiandentalacademy.com 37
  38. 38. HIS PHILOSOPHY :  position and arrange teeth for maximal facial and dental esthetics and functional efficiency.  health of teeth,jaws,joints, surrounding tissues must be maintained.  stability  harmonise correction of normal growth processes. www.indiandentalacademy.com 38
  39. 39.  maximise compensation for less than normal growth patterns.  position the dentition so that it is in a continual state of harmony with its environment. www.indiandentalacademy.com 39
  40. 40. DRAWBACKS OF THE TWEED PHILOSOPHY  he concentrated on the antero-posterior & vertical trend of growth on the basis of which he formulated the growth trends.  en masse tooth movement did not necessarily translate into precison and control. www.indiandentalacademy.com 40
  41. 41.  mandibular anchorage was prepared with class iii elastics and with all compensation bends placed in arch wire at one time resulting in labially flared and intruded mandibular incisors as a sequelae. www.indiandentalacademy.com 41
  42. 42. Tweed named Levern Merrifield as his successor to guide the rapidly expanding and successful Tweed study course in Tucson , Arizona. the pitfalls of the Tweed philosophy where to be rectified by him and was subsequently known as the ‘ TWEED-MERRIFIELD PHILOSOPHY’ www.indiandentalacademy.com 42
  43. 43. TWEED- MERRIFIELD PHILOSOPHY www.indiandentalacademy.com 43
  44. 44. LEVERN MERRIFIELD www.indiandentalacademy.com 44
  45. 45.         HIS ADDITIONAL CONTRIBUTION FOUR PREMISES BROAD PARAMETERS OF THE PHILOSOPHY DIFFERENTIAL DIAGNOSIS FACIAL DENTAL CRANIAL ENVIRONMENTAL www.indiandentalacademy.com 45
  46. 46. Merrifield introduced the Tweed Merrifield philosophy by adding a seventh objective  all clinical objectives must be pursued in an ethical ,moral and compassionate manner with an over riding concern for the public’s welfare. www.indiandentalacademy.com 46
  47. 47. the Tweed Merrifield is based on four fundamental pillars or premises. they are:  an anterior limit exists.the teeth must not be placed forward of basal bone.  a posterior limit exists.  a lateral limit exists. any position beyond this results in a relapse.  a vertical limit exists. facial balance and harmony can be lost as result. www.indiandentalacademy.com 47
  48. 48. broad parameters of the Tweed-Merrifield philosophy include:  assessing the dimensions of the lower face.  total space analysis.  assessing areas of skeletal,facial and dental disharmony.  directional control during treatment www.indiandentalacademy.com 48
  49. 49.  sequential tooth movement.  sequential mandibular anchorage preparation. www.indiandentalacademy.com 49
  50. 50. DIFFERENTIAL DIAGNOSIS  facial disharmonies  dental disharmonies  cranial disharmonies  environmental disharmonies www.indiandentalacademy.com 50
  51. 51. FACIAL DISHARMONIES THREE FUNDAMENTAL FACTORS INFLUENCE FACIAL BALANCE:  positions of teeth  skeletal pattern  soft tissue thickness www.indiandentalacademy.com 51
  52. 52.  tooth position plays a fundamental role in facial balance.  maxillary incisor position is directly related to position of mandibular incisors. this can be diagnosed by equating the upper lip measurement to that of the lower chin. www.indiandentalacademy.com 52
  53. 53. upper lip thickness is measured from the greatest curvature of the labial surface of the central incisor to vermilion border of www.indiandentalacademy.com upper lip. 53
  54. 54.  total chin thickness is measured horizontally from nb line extended to soft tissue pogonion.  UPPER LIP = TOTAL CHIN www.indiandentalacademy.com 54
  55. 55. z angle ideally the z line must be tangent to the chin and the vermilion border of both lips and should bisect the nose.it should proceed to join the www.indiandentalacademy.com 55 frankfort plane at an angle of 75 to 78 degrees.
  56. 56. fmia angle the fmia should correspond to an angle of 65 degrees . www.indiandentalacademy.com 56
  57. 57. CRANIAL DISHARMONIES www.indiandentalacademy.com 57
  58. 58. SNA : 80- 84 DEGREES pfh SNB : 78- 82 DEGREES ANB : 1- 5 DEGREE www.indiandentalacademy.com AO- BO : 0-4 MM x 100 = 69% of afh. afh 58
  59. 59.  occlusal plane to frankfort horizontal plane: 8-12 degrees  facial height index pfh x 100 = 69% of afh. afh a range of 65 to 75% was found to be acceptable. www.indiandentalacademy.com 59
  60. 60. facial height change ratio: facial height change was assessed during the course of treatment. a ratio of two times as much pfh increase than afh increase during treatment was ideal for correction of class ii div 1 and dentoalveolar protrusions. www.indiandentalacademy.com 60
  61. 61. DENTAL DISHARMONIES TOTAL SPACE ANALYSIS DIVIDED INTO THREE PARTS:  anterior  midarch www.indiandentalacademy.com  posterior 61
  62. 62. ANTERIOR SPACE ANALYSIS measurement taken from mandibular canine to canine.also mesiodistal diameter of six anterior teeth taken. the difference gives idea of surplus or deficit.   lateral head film discrepancy taken into account. It is the amount of space required to position the mandibular incisors for facial balance. www.indiandentalacademy.com 62
  63. 63. total chin thickness must equal upper lip thickness.hence soft tissue balance obtained.  www.indiandentalacademy.com 63
  64. 64. thus the sum of anterior tooth arch surplus or deficit,lateral headfilm discrepancy and soft tissue imbalance is combined to estimate the anterior discrepancy. each of the values is assigned a difficulty factor. www.indiandentalacademy.com 64
  65. 65. MIDARCH SPACE ANALYSIS  includes mandibular first molars and first and second premolars.  available midarch space: distal of canine to distal of first molar.to this add the space required to level the curve of spee. www.indiandentalacademy.com 65
  66. 66.  occlusal disharmony: articulate the casts and use maxillary first premolar as reference.measure mesially or distally from buccal cusp of maxillary first premolar to embrasure between mandibular first and second premolars.measurement done on both sides and averaged.  The averaged value is then doubled and added to midarch difficulty. www.indiandentalacademy.com 66
  67. 67. POSTERIOR SPACE ANALYSIS measured from the distal of mandibular first molar to anterior border of ramus along the occlusal plane. this measurement must take into consideration the age and gender of the patient as well. www.indiandentalacademy.com 67
  68. 68. variables to be taken into account when assessing posterior space are:  rate of mesio-occlusal migration of mandibular first molar.  rate of resorption of anterior border of ramus.  time of cessation of molar migration. www.indiandentalacademy.com 68
  69. 69.  time of cessation of ramus resorption.  gender  age. www.indiandentalacademy.com 69
  70. 70. the tweed merrifield appliance is essentially consists of .022 edgewise slots with  double width brackets on the six anterior teeth.  intermediate single width brackets on premolars.  twin brackets on the first molars. www.indiandentalacademy.com 70
  71. 71. APPLICATION OF PHILOSOPHY INTO PRACTICE www.indiandentalacademy.com 71
  72. 72.       FIVE CONCEPTS OF THE TREATMENT PHILOSOPHY SEQUENTIAL BANDING AND BONDING SEQUENTIAL TOOTH MOVEMENTS SEQUENTIAL ANCHORAGE PREPARATION: 10 – 2 SYSTEM CL II FORCE SYSTEMS www.indiandentalacademy.com 72
  73. 73.  DIRECTIONAL FORCE APPLICATION  PROPER TIMING OF TREATMENT  INCORPORATION OF FIRST , SECOND AND THIRD ORDER BENDS www.indiandentalacademy.com 73
  74. 74.  FORCE SYSTEMS: DENTURE PREPARATION  DENTURE CORRECTION  DENTURE COMPLETION  DENTURE RECOVERY  www.indiandentalacademy.com 74
  75. 75.  .022 tubes with mesial hooks on the second molars. www.indiandentalacademy.com 75
  76. 76. TWEED MERRIFIELD EDGEWISE APPLIANCE www.indiandentalacademy.com 76
  77. 77.  Tweed initally used 12 sets of archwires.Merrifield reduced it to four to five sets of arch wires the dimensions of wire commonly used were : .017X .022  .018X .025  .019X .025  .020X .025  .021X .028  www.indiandentalacademy.com 77
  78. 78. FIVE CONCEPTS OF TREATMENT PHILOSOPHY  sequential banding or bonding.  sequential tooth movement.  sequential mandibular anchorage preparation. www.indiandentalacademy.com 78
  79. 79.  directional force application.  proper timing of treatment. www.indiandentalacademy.com 79
  80. 80. SEQUENTIAL BANDING OR BONDING the terminal molars are banded,the second premolars and canines.incisors can be either banded or bonded. advantages :  less traumatic to patient.  easier and less time consuming for the orthodontist www.indiandentalacademy.com 80
  81. 81.  longer interbracket length for the archwire.hence creates a power storage in the wire that accomplishes the objectives rapidly.  orthodontist can insert a wire of larger dimension that is less subject to bracket engagement distortion. www.indiandentalacademy.com 81
  82. 82. maxillary molars are banded after one month. www.indiandentalacademy.com 82
  83. 83.  Mandibular molars banded after second visit. Lateral incisors can be banded or bonded depending on progress. www.indiandentalacademy.com 83
  84. 84. SEQUENTIAL TOOTH MOVEMENT en masse tooth movement not done.  teeth moved individually or in small units.    advantages : more rapid tooth movement. more precision involved. www.indiandentalacademy.com 84
  85. 85. SEQUENTIAL MANDIBULAR ANCHORAGE PREPARATION  instead of class iii elastics Merrifield opted for high pull gear for anchorage preparation.  the 10-2 system was incorporated to better augment anchorage. ten teeth were used as anchors to tip two teeth. advantage: no labial flaring of mandibular incisors. no intrusion.   www.indiandentalacademy.com 85
  86. 86. DIRECTIONAL FORCES This concept led to the evolution of Merrifield’s ‘ sequential directional force technology’ directional forces are defined as controlled forces which place the teeth in the most harmonious relationship with their environment. www.indiandentalacademy.com 86
  87. 87.  the resultant vector of all force systems must be upward and forward so that the oppurtunity tfor favourable skeletal change is enhanced.  such a system requires that the mandibular incisor be upright over the basal bone so that the maxillary incisor can be moved distally www.indiandentalacademy.com and superiorly. 87
  88. 88.  for this to be a reality, vertical control is critical. www.indiandentalacademy.com 88
  89. 89. TIMING OF TREATMENT treatment must be initiated at a time when the treatment objectives can be readily accomplished.    interceptive treatment in mixed dentition serial extractions in mixed dentition waiting for second molar eruption diagnostic discretion is paramount. www.indiandentalacademy.com 89
  90. 90. INCORPORATION OF FORCE SYSTEMS INTO THE PHILOSOPHY www.indiandentalacademy.com 90
  91. 91. FIRST ORDER BENDS www.indiandentalacademy.com 91
  92. 92.   these bends provide for bucco-lingual movements of teeth www.indiandentalacademy.com bends are incorporated in the horizontal plane . 92
  93. 93.  these bends provide for expansion or contraction of the arch as the need arises. www.indiandentalacademy.com 93
  94. 94. SECOND ORDER BENDS www.indiandentalacademy.com 94
  95. 95.  these bends provide for mesio-distal tipping of teeth as and when required.  bends are incorporated in the arch wire in the vertical plane as tipwww.indiandentalacademy.com back bends. 95
  96. 96.  bends made in the posterior segment of the mandibular arch are antagonistic to anterior teeth  labial flaring and intrusion are the sequelae if all bends are placed at one go. www.indiandentalacademy.com 96
  97. 97.  second order bends made in the posterior segment of the maxillary arch are complimentary to that of anterior segment. www.indiandentalacademy.com 97
  98. 98. THIRD ORDER BENDS www.indiandentalacademy.com 98
  99. 99. third order bends are given to effect root torque,be it buccal or lingual. two ribbon arch pliers are utilised.one to hold the wire.the other to incorporate the desired torque. www.indiandentalacademy.com 99
  100. 100.  in the mandibular arch,incorporation of torque is complimentary to the anterior and posterior segments www.indiandentalacademy.com 100
  101. 101.  in the maxillary arch,third order bends prove to be antagonistic as little or no torque is required in the anterior segment and hence any torque in this region is undesirable when torque given in posterior segments. www.indiandentalacademy.com 101
  102. 102.  therefore active third order bends are given in posterior segments sequentially and only in one direction at any given time. www.indiandentalacademy.com 102
  103. 103. Evaluation of torque by holding with ribbon arch plier. Torqued segment will at an angulation . www.indiandentalacademy.com 103
  104. 104. FORCE SYSTEMS  Denture preparation  Denture correction  Denture completion  Denture recovery www.indiandentalacademy.com 104
  105. 105. DENTURE PREPARATION OBJECTIVES     leveling individual tooth movement and rotation correction retraction of both maxillary and mandibular canines. preparation of terminal molars for stress resistance. www.indiandentalacademy.com 105
  106. 106.  this stage requires approximately six months.  .017x.022 maxillary arch wire.  .018x.025 mandibular arch wire. www.indiandentalacademy.com 106
  107. 107. loop stops must be flush with the second molar tubes. mandibular second molar receives a 15 degree effective distal tip. maxillary second molar receives 5 degree distal tip from wire distal to loop. www.indiandentalacademy.com 107
  108. 108. high pull headgear incorporated to retract the canines. adverse effect: canines tend to expand out of the alveolar trough as they get retracted. remedy: place a second premolar offset bend mesial to second premolar bracket. www.indiandentalacademy.com 108
  109. 109. as canines retract and arches level,lateral incisors can be banded or bonded. www.indiandentalacademy.com 109
  110. 110. Power chains can be used to retract the canines. www.indiandentalacademy.com 110
  111. 111.     at end of denture preparation: all dentition must be fully bracketed and levelled. canines should be retracted. all rotations corrected. mandibular terminal molars must be tipped to terminal anchorage position. www.indiandentalacademy.com 111
  112. 112. DENTURE CORRECTION  continuation of sequential mandibular anchorage preparation.  the class ii force system. www.indiandentalacademy.com 112
  113. 113. spaces closed with maxillary and mandibular closing loops supported by j hook headgear attached to hooks soldered between maxillary and mandibular central incisors. www.indiandentalacademy.com 113
  114. 114. arch wire changes  maxillary: .020x.025 with 6.5mm vertical loops.  mandibular: .019x.025 with 6mm vertical loops. www.indiandentalacademy.com 114
  115. 115.  loop stops immediately distal to brackets of first molars.  loop stop in mandibular archwire incorporates compensation to maintain 15 degree molar tip. www.indiandentalacademy.com 115
  116. 116. end objectives prior to mandibular anchorage preparation would be : obtain space closure in both arches. maintain curve of occlusion in maxillary arch. www.indiandentalacademy.com 116
  117. 117.  level mandibular arch.  maintain 15 degree distal tip of second molar. www.indiandentalacademy.com 117
  118. 118. SEQUENTIAL MANDIBULAR ARCH PREPARATION  employs a 10-2 anchorage system. advantages:  quick controlled response  supported by high pull head gear worn on vertical spurs soldered distal to mandibular lateral incisors. www.indiandentalacademy.com 118
  119. 119.   after checking that : the mandibular arch is level. the second molars are tipped to a 15 degree angulation. www.indiandentalacademy.com 119
  120. 120. a readout is obtained whereby the mandibular archwire is removed and a plain archwire is inserted into the second molar tube and a readout is obtained. www.indiandentalacademy.com 120
  121. 121. the second step of sequential mandibular preparation is now initiated.  another .019x .025 archwire is fabricated with loop stops bent flush against second molar tubes.  headgear hooks soldered distal to lateral incisors. www.indiandentalacademy.com 121
  122. 122. 10 degree distal tip placed 1mm mesial to first premolar brackets. a compensating bend placed to maintain 15 degree tip at terminal molar. thus archwire is passive to second molar and crosses first molar at a 10 degree angle. www.indiandentalacademy.com 122
  123. 123. the third and final step of mandibular anchorage preparation is initiated.  a 5 degree distal tip placed mesial to second premolar brackets.  www.indiandentalacademy.com 123 compensating bend placed in embrasure between second premolar and first molar.
  124. 124.  the second molar become part of stabilising unit.first molar is the recipient of directional forces.  for ideal response a high pull headgear applied to anterior vertical spurs. www.indiandentalacademy.com 124
  125. 125. the second premolars now become the recipients of the 10-2 system.  again arch wire is at angulation to second premolar bracket.  www.indiandentalacademy.com 125
  126. 126.  at the end readout must show:  second molars at 15 degree  first molars at 5 to 8 degree  second premolars at 0 to 3 degree . www.indiandentalacademy.com 126
  127. 127. end objectives of treatment of class i malocclusion are:  complete space closure in both arches.  sequential anchorage preparation in mandibular arch. www.indiandentalacademy.com 127
  128. 128.  enhanced curve of occlusion in the maxillary arch.  class i intercuspation of canines and premolars. www.indiandentalacademy.com 128
  129. 129.  mesiobuccal cusp of maxillary first molar should fit into mesiobuccal groove of mandibular first molar.  the distal cusps of these teeth should be discluded as those of second molars. www.indiandentalacademy.com 129
  130. 130. CLASS II FORCE SYSTEM applicable for cases with an end-on or full step class ii relationship of the buccal segments.    corrections will be based on: anb relationship maxillary posterior space analysis patient cooperation. www.indiandentalacademy.com 130
  131. 131. GUIDELINES FOLLOWED IN TREATING  if anb <5 degree and maxillary third molars missing, class ii force systems work best with a cooperative patient. www.indiandentalacademy.com 131
  132. 132.  anb is 5 to 8 degrees,class ii cusp relationship,cooperative patient. extraction of second molars is advantageous.the force system will then distalize the maxillary arch in extraction space. www.indiandentalacademy.com 132
  133. 133.  anb > 10 degrees ,patient compliance is questionable,first molar removal or surgical correction should be considered. www.indiandentalacademy.com 133
  134. 134. maxillary : .020x.025 with closed bulbous loops bent flush against the second molar tubes. mandibular: .021x.028 stabilising archwire with loop stop 0.5 mm short of molar tube. www.indiandentalacademy.com 134
  135. 135. CLASS II FORCE SYSTEM www.indiandentalacademy.com 135
  136. 136. after the force system is employed for a month or so  the bulbous loops are activated again to 1 mm.  .030 sliding jigs are fabricated and placed on maxillary archwire such that distal eyelet contacts mesial bracket of maxillary first molars and the mesial eyelets are midway between canine and www.indiandentalacademy.com premolar brackets. 136
  137. 137. after four months of treatment with monthly reactivation, an over treated class i relationship is achieved.  refabricate maxillary arch wire with 6.5 mm closing loops distal to lateral incisors. closing loops opened 1mm per visit. www.indiandentalacademy.com 137
  138. 138.  class ii forces reduced to 4 to 6 oz.anterior elastics and headgear to be used in conjunction with elastics. www.indiandentalacademy.com 138
  139. 139. COMPLETION OF THE CLASS II FORCE SYSTEM www.indiandentalacademy.com 139
  140. 140. DENTURE COMPLETION  maxillary and mandibular archwires progressed to .021x .o28.  light class ii elastics maintained  critical study of individual tooth arrangement as well as inter arch relations done. www.indiandentalacademy.com 140
  141. 141.  progress cephalogram and tracings done to evaluate final mandibular incisor positions and minor control of palatal,occlusal and mandibular planes. www.indiandentalacademy.com 141
  142. 142.  tracings would also reveal requrement of lingual root torque in maxillary incisors.  force systems are repeated if orthodontist not satisfied. www.indiandentalacademy.com 142
  143. 143.  after over correction,final artistic bends and cusp seating forces given to provide quality and detail. www.indiandentalacademy.com 143
  144. 144. END OBJECTIVES  incisors must be aligned.  occlusion overtreated to class i relationship.  anterior teeth must be edge to edge.  maxillary canine and premolars must lock tightly into class i www.indiandentalacademy.com relationship. 144
  145. 145.  mesiobuccal cusp of maxillary first molar must occlude in the mesiobuccal groove of mandibular first molar. www.indiandentalacademy.com 145
  146. 146.  distal cusps of first and second molars must be out of occlusion.  all spaces must be closed tight from second premolars forward. www.indiandentalacademy.com 146
  147. 147. DENTURE RECOVERY  all treatment mechanics are discontinued to enable ideal results.  all bands except for canines and first molars are removed. www.indiandentalacademy.com  first molars ligated to canines in upper and lowerarches. 147
  148. 148.  canines ligated to each other in mandibular arch.  for the maxillary arch ,power chains given for canines. www.indiandentalacademy.com 148
  149. 149.  after seven days, remaining bands removed and retainers placed.  recovery occurs during this period when function settles the teeth into their most efficient ,healthy and stable positions. www.indiandentalacademy.com 149
  150. 150. CONCLUSION ‘ NOTHING WORTHWHILE EVER DEPARTS’ It firmly stood the test of time. Modifications were made from time to time. But the appliance remained… while others vanished beneath the sands of time. www.indiandentalacademy.com 150
  151. 151. THANK YOU www.indiandentalacademy.com 151
  152. 152. REFERENCES  Graber and Vanarsdall 2nd and 3rd editions  Clinical Orthodontics – Charles Tweed www.indiandentalacademy.com 152
  153. 153. www.indiandentalacademy.com 153

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