Tweed merrifield edgewise appliance

THE TWEED -MERRIFIELD
EDGEWISE APPLIANCE
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I-Historical prospective-Evolution of appliance
-Charles Tweed
-Levern Merrifield
II-Diamention of dentition
III-Diagnosis -Identification and classification
-Facial disharmony
-Dental disharmony
-Cranial disharmony
-Environmental disharmony

IV- Differential diagnosis
-Facial
-Dental
-Cranial
V-Tweed Merrifield edgewise appliance.
-Brackets,Tubes
-Archwires
-1st,2nd,3rd order bends
VI- Treatment with tweed merrifield appliance
-Sequential app placement
-Sequential tooth movt
-Sequential mand,anch,prep.

-Directional force
-Timing of treatment
VII-Steps of treatment
-Denture prep.
-Denture correction
-Sequential mand anch prep.
Class II force system
-Denture completion
-Denture recovery

Introduction
Crowded,irregular and protruding teeth have
been a problem since antiquity,and attempts to
correct this disorder go back to 1000 B.C.
Dr.Edward H Angle is known
as ‘father of Orthodontics’.

THE ANGLE SYSTEM
- Edward H Angle introduced ‘Angle System’ in 1888
The technical problems and frustrations in
treatment,motivated and inspired Angle to develop a
standard appliance.
An orthodontic appliance must have five
properties.
* Simplicity-It must push or pull teeth.
* Stability - It must be fixed to teeth
* Efficiency-It must be based on Newtons 3rd law
and anchorage

*Delicacy-It must be accepted by tissues and shouldn’t
cause any inflammation
*Inconspicuousness-It must be esthetically acceptable
He disigned a standard appliance composed of a
specific number of basic components
This universal application enabled practitioners
to treat more patients at a higher level of excellence and
at less cost.
It was biginning of relationship between
manufacturers,suppliers,and orthodontist;it was the
Angle System www.indiandentalacademy.com

Basic components of Angle’s standard appliance
Traction screws,attachment screws, lever wires,band
materials,archwire and wrench.

The E Arch Appliance 1907
With the use of E Arch in conjunction with the
high pull head gear,the protruding maxillary anterior
teeth were retracted into spaces provided by the
extraction of permanent first premolar teeth.
- Use of Jack screw is discontinued
- He used a heavy,ideal expansion
arch attached by solder to two first
molar clamp bands.

- Brass ligature wire and stationary anchorage in the
molar area is used to expand all the teeth into normal
occlusion.
- It employed crown movements of teeth and simple
anchorage.

Angle discontinued extracting teeth,for the most
part, when he began using inter maxillary elastic
forces and Baker anchorage.
- He used a maxillary E Arch with threaded ends and
intermaxillary elastics.

-This permitted teeth of both arches to be correctly
oriented into proper occlusion without extraction.
- The maxillary dentition was retracted and the
mandibular dentition was moved forward.
- But the correction of the axial relationship of the the
teeth could not be accomplished.
- Angle concluded from his failure that it was
necessary to move teeth bodily to produce stable
results.

THE PIN AND TUBE APPLIANCE.
- It was the first appliance to move teeth bodily.
- Angle developed the pin and tube appliance in order
to move the teeth bodily.

- However,the ideal arch of the E Arch appliance had
to be sacrificed so that each teeth could be moved with
the pin and tube attachment .
- The arch wires altered as tooth movement was carried
out,always progressing towards ideal arch form.
- The Pin and Tube appliance was difficult appliance to
manipulate and precise and delicate maneuvers had to
be carried out with each appointment.Also the patients
were required to come into office for activation every
few days.

THE RIBBON ARCH APPLIANCE
-As the pin and tube appliance was difficult to
use,Angle in 1915 developed the Ribbon Arch
appliance.

-Brackets were introduced with this appliance.
-It was a much simpler appliance to construct and
activate.
-It was characterized by vertical slot.
-The teeth were free to move along the arch wire like
a string of beads.
-The Ribbon Arch appliance was not generally
suitable for en masse movement of teeth.

- Anterior teeth could be retracted only at the expense
of anchorage provided by the posterior teeth.
- Mesial and distal tipping bends couldn’t be
incorporated into the archwire and premolar teeth
couldn’t be moved bodily.

THE EDGEWISE APPLIANCE 1928
- To overcome the past difficulties and for better
possibilities Angle changed the form of brackets by
locating the slot in the center of and placing it in a
horizontal plane instead of vertical plane.

- The archwires are held in place first by a brass
ligature and later by a delicate stainless steel wire
ligature.
- The new Edgewise bracket consisted of a rectangular
box with three walls with in the the bracket,0.022 inch
by 0.028 in dimension.
- Its slot opened horizontally.
- This new design provided more
accuracy and more efficient torquing
mechanism.

CHARLES. H. TWEED
- He is the first certified specialist in Orthodontics in the
United states.
- He graduated from an improvised
Angle course in 1928
- He instigated passing of the first
Orthodontic Speciality Law in the
United states.

Tweed’s many contributions to the speciality
established a benchmark in orthodontic treatment and
thoughts.
- He developed the concept of uprighting teeth over
basal bone with emphasis on the mandibular incisors.
- He made the extraction of teeth for Orthodontic
correction acceptable and popularized the extraction
of the first premolars.
- He enhanced the clinical application of
cephalometrics

- He developed the diagnostic facial triangle to make
cephalometric a diagnostic tool and a guide in
treatment and in the evaluation of treatment results.
- He developed a concept of orderly treatment
procedures and introduced anchorage preparation as a
major step in treatment.

- He developed a fundamentally sound and consistent
pre orthodontic guidance program using and
popularizing serial extraction of primary and
permanent teeth.
Charles Tweed,one of the orthodontics most
brilliant innovators devoted 42 years of his life from
1928 to 1970 to the advancement of the edgewise
appliance.

LEVERN MERRIFIELD
In 1960, Tweed selected his student Levern
Merrifield,from Pona city, Oklahoma,to continue his
work on the edgewise appliance.
Merrifield has devoted the past
45 years of his life for study of
Orthodontic diagnosis and the use
of edgewise appliance.

Merrifield’s contributions have been popularized;
include the following-
1. The fundamental concept of dimentions of dentition.
Differential diagnostic concepts.
2. Diamentions of lower face.
3. Total space analysis.
4. Guidelines for space management decisions to
achieve the following.
* Facilitate maximal orthodontic correction
* Define areas of skeletal, facial and dental
disharmony.

Treatment concepts
5. Directional control during treatment.
6. Sequential tooth movement.
7. Sequential mandibular anchorage preparation
8. The organization of of treatment into four orderly
steps that have specific objectives.

Merrifields innovations give the modern orthodontist a
more accurate,reliable,precise,efficient and practical
protocol of diagnosis and treatment.It allows the
clinician ti do the following…
- Define objectives for the face,dentition,and skeletal
pattern
- Properly diagnose the malocclusion
- Use the edgewise appliance to reach the
predetermined objectives efficiently.

This universally accepted objectives enabled the
clinician to position and arrange the teeth for maximal
facial and dental esthetics;functional efficiency;health of
the teeth,jaws,joints;and surrounding tissues and stability.
Orthodontist must position and arrange the teeth in the
immature patient to harmonize the correction with
normal growth process,maximize the compensation for
less than normal patterns,and position the dentition so that
it is in a continual state of harmony with its environment.
The clinical objectives must be pursued in an
ethical,moral,and compassionate manner with an
overriding concern for the public welfare.

Tweed merrifield edgewise appliance

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