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

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

TWEED- MERRIFIELD
EDGEWISE
PHILOSOPHY

1

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

2

- Drawback of his philosophy
 TWEED – MERRIFIELD PHILOSOPHY
- Merrifield’s additional contributions
- Four premises of the philosophy
- Differential diagnosis:
facial
dental
cranial
environmental

3

 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

4

- Directional force application
- Proper timing of treatment
- Incorporation of first, second , third order bends
- Force systems
Denture preparation
Denture correction
Denture completion
Denture recovery

5

 CONCLUSION


6

ANGLE
TWEED
MERRIFIELD
LEGACY

7

EDWARD HARTLEY ANGLE

8

ANGLE’S INSPIRATION

9

E ARCH APPLIANCE

10

PIN AND TUBE APPLIANCE

11

RIBBON ARCH APPLIANCE

12

EDGEWISE APPLIANCE

13

EVOLUTION OF THE
EDGEWISE
CONCEPT

14

ANGLE’ VIEWS


HIS CONCEPT OF AN APPLIANCE



DRAWBACKS


15

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

SIMPLE- push, pull, rotations
STABLE - fixed to teeth
EFFICIENT- provide anchorage
DELICATE - accepted by tissues
INCONSPICUOUS - esthetic

16

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.

17

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.

18

ANGLE’S EDGEWISE PHILOSOPHY
Incorporated the
NON-EXTRACTION PROTOCOL
therefore closing of spaces in
the posterior segments was a
problem.


19

Anteroposterior correction was
difficult to accomplish.
proclination of anterior teeth
was common.
crowns tended to tip mesially.


20

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.’

21

TWEED
PHILOSOPHY


22

CHARLES H.TWEED

23



BRIEF OVERVIEW OF THE CHANGES HE
INTRODUCED



DIAGNOSTIC FACIAL TRIANGLE
ANCHORAGE PREPARATION
GROWTH TRENDS
TWEED PHILOSOPHY
DRAWBACK OF HIS PHILOSOPHY







24

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……..

25

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



26

DIAGNOSTIC FACIAL TRIANGLE


27

Diagnostic Facial Triangle
angles considered where:


frankfort mandibular plane angle / fma ( 25
degrees)



mandibular incisor plane angle / impa ( 90
degrees)

28



frankfort mandibular incisor angle / fmia (65
degrees)



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


29

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.

30

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.

31

THIRD DEGREE OR TOTAL
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.

32

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.

33

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.

34

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.

35

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.

36

TYPE C SUBDIVISON


when growth is predominantly horizontal with
a decreased fma angle.



little vertical growth occurs.


37

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.

38



maximise compensation for less than normal growth
patterns.



position the dentition so that it is in a continual state
of harmony with its environment.

39

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.

40



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.


41

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’

42

TWEED- MERRIFIELD
PHILOSOPHY


43

LEVERN MERRIFIELD

44











HIS ADDITIONAL CONTRIBUTION
FOUR PREMISES
BROAD PARAMETERS OF THE
PHILOSOPHY
DIFFERENTIAL DIAGNOSIS
FACIAL
DENTAL
CRANIAL
ENVIRONMENTAL

45

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.

46

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.

47

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

48



sequential tooth movement.



sequential mandibular anchorage
preparation.

49

DIFFERENTIAL DIAGNOSIS



facial disharmonies



dental disharmonies



cranial disharmonies



environmental disharmonies

50

FACIAL DISHARMONIES
THREE FUNDAMENTAL FACTORS
INFLUENCE FACIAL BALANCE:


positions of teeth



skeletal pattern



soft tissue thickness


51



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.

52

upper lip thickness is measured
from the greatest curvature of
the labial surface of the central
incisor to vermilion border of
upper lip.

53

 total

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



UPPER LIP = TOTAL CHIN

54

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
55
frankfort plane at an angle
of 75 to 78 degrees.

fmia angle

the fmia should correspond to
an angle of 65 degrees .


56

CRANIAL DISHARMONIES


57

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

x 100 = 69% of afh.
afh
58



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.

59

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.

60

DENTAL DISHARMONIES
TOTAL SPACE ANALYSIS
DIVIDED INTO THREE PARTS:


anterior



midarch

 posterior

61

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.

62

total chin thickness must equal upper lip
thickness.hence soft tissue balance obtained.



63

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.

64

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.

65



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.

66

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.

67

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.

68



time of cessation of ramus resorption.



gender



age.


69

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.

70

APPLICATION OF
PHILOSOPHY INTO PRACTICE


71










FIVE CONCEPTS OF THE TREATMENT
PHILOSOPHY
SEQUENTIAL BANDING AND BONDING
SEQUENTIAL TOOTH MOVEMENTS
SEQUENTIAL ANCHORAGE
PREPARATION:
10 – 2 SYSTEM
CL II FORCE SYSTEMS

72



DIRECTIONAL FORCE APPLICATION



PROPER TIMING OF TREATMENT



INCORPORATION OF FIRST , SECOND
AND THIRD ORDER BENDS

73



FORCE SYSTEMS:
DENTURE PREPARATION



DENTURE CORRECTION



DENTURE COMPLETION



DENTURE RECOVERY




74



.022 tubes with mesial hooks on the second
molars.


75

TWEED MERRIFIELD EDGEWISE APPLIANCE

76



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



77

FIVE CONCEPTS OF TREATMENT
PHILOSOPHY



sequential banding or bonding.



sequential tooth movement.



sequential mandibular anchorage
preparation.

78



directional force application.



proper timing of treatment.

79

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

80



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.


81

maxillary molars are banded after one month.


82



Mandibular molars banded after second visit.
Lateral incisors can be banded or bonded depending on
progress.

83

SEQUENTIAL TOOTH MOVEMENT
en masse tooth movement not done.
 teeth moved individually or in small units.





advantages :
more rapid tooth movement.
more precision involved.

84

SEQUENTIAL MANDIBULAR


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.





85

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.


86

 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
and superiorly.

87



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


88

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.

89

INCORPORATION OF FORCE
SYSTEMS INTO THE PHILOSOPHY


90

FIRST ORDER BENDS


91





these bends provide for bucco-lingual movements of
teeth

bends are incorporated in the horizontal plane .

92

 these

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


93

SECOND ORDER BENDS


94



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



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.

96



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


97

THIRD ORDER BENDS


98

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.

99



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


100



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.


101



therefore active third order bends are given in
posterior segments sequentially and only in
one direction at any given time.


102

Evaluation of torque by holding with ribbon arch plier.
Torqued segment will at an angulation .

103

FORCE SYSTEMS


Denture preparation



Denture correction



Denture completion



Denture recovery


104

DENTURE PREPARATION
OBJECTIVES







leveling
individual tooth movement and rotation
correction
retraction of both maxillary and mandibular
canines.
preparation of terminal molars for stress
resistance.

105



this stage requires approximately six
months.



.017x.022 maxillary arch wire.



.018x.025 mandibular arch wire.

106

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.

107

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.

108

as canines retract and arches level,lateral incisors can
be banded or bonded.

109

Power chains can be used to retract the
canines.

110







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.

111

DENTURE CORRECTION



continuation of sequential mandibular
anchorage preparation.



the class ii force system.

112

spaces closed with maxillary and mandibular closing
loops supported by j hook headgear attached to
hooks soldered between maxillary and mandibular
central incisors.

113

arch wire changes
 maxillary: .020x.025 with 6.5mm vertical
loops.
 mandibular: .019x.025 with 6mm vertical
loops.


114



loop stops immediately distal to brackets of first molars.



loop stop in mandibular archwire incorporates compensation to
maintain 15 degree molar tip.

115

end objectives prior to mandibular anchorage preparation would be :
obtain space closure in both arches.
maintain curve of occlusion in maxillary arch.

116



level mandibular arch.



maintain 15 degree distal tip of second molar.

117

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.

118





after checking that :
the mandibular arch is level.

the second molars are tipped to a 15 degree
angulation.


119

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.

120

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.

121

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.

122

the third and final step of mandibular anchorage preparation is
initiated.


a 5 degree distal tip placed mesial to second premolar brackets.



123
compensating bend placed in embrasure between second premolar
and first molar.



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.


124

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


125



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 .

126

end objectives of treatment of class i
malocclusion are:


complete space closure in both arches.



sequential anchorage preparation in
mandibular arch.

127



enhanced curve of occlusion in the maxillary
arch.



class i intercuspation of canines and
premolars.


128



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



the distal cusps of these teeth should be
discluded as those of second molars.

129

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.

130

GUIDELINES FOLLOWED IN TREATING



if anb <5 degree and maxillary third molars
missing, class ii force systems work best with
a cooperative patient.


131



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.


132



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


133

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.

134

CLASS II FORCE SYSTEM

135

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
premolar brackets.

136

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.


137



class ii forces reduced to 4 to 6 oz.anterior
elastics and headgear to be used in
conjunction with elastics.

138

COMPLETION OF THE CLASS II FORCE SYSTEM


139

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.


140



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


141



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



force systems are repeated if orthodontist not
satisfied.


142



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


143

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
relationship.

144



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


145



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



all spaces must be closed tight from second
premolars forward.

146

DENTURE RECOVERY



all treatment mechanics are discontinued to enable ideal results.



all bands except for canines and first molars are removed.



first molars ligated to canines in upper and lowerarches.

147



canines ligated to each other in mandibular
arch.



for the maxillary arch ,power chains given for
canines.


148



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.

149

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.

150

THANK YOU


151

REFERENCES


Graber and Vanarsdall 2nd and 3rd editions



Clinical Orthodontics – Charles Tweed


152


153

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

Recomendados

Recomendados

Más contenido relacionado

La actualidad más candente

La actualidad más candente (20)

Destacado

Destacado (17)

Similar a Tweed merrifield edgewise phylosophy /certified fixed orthodontic courses by Indian dental academy

Similar a Tweed merrifield edgewise phylosophy /certified fixed orthodontic courses by Indian dental academy (20)

Más de Indian dental academy

Más de Indian dental academy (20)

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