This document describes the evolution and components of the Tweed-Merrifield edgewise appliance for orthodontic treatment. It started with Dr. Angle's ribbon-arch bracket in 1916 but was modified in 1925 into the edgewise bracket with a horizontal slot orientation. The modern appliance uses 0.022" slots with different bracket widths. It incorporates archwires of various sizes, as well as first, second, and third order bends to control tooth movement. Additional auxiliaries like elastics and headgear are also used.

1. THE TWEED-MERRIFIELD
EDGEWISE APPLIANCE
THE BRACKETS AND THE TUBES
ARCHWIRES
FIRST,SECOND, AND THIRD ORDER
BENDS
THE AUXILLARIES
www.indiandentalacademy.com

2. THE EVOLUTION OF THE EDGEWISE
BRACKET
 It started in 1916, in the form of ribbon-
arch bracket as devised by Dr.E.H.Angle.
 Although it became very popular at that
time,- deficiencies:-
 It could not control tooth movement in all
three planes.
 Root control was not up to expectations
www.indiandentalacademy.com

3.  Modify the bracket – in 1925 – the Edgewise
bracket.
 Slot orientation was changed from vertical to
horizontal,
Rectangular wire oriented 90° to the orientation
it had in the ribbon arch.
 Initially referred to as “open face” or
“tiebracket”.
 Slot – soft gold with a 0.022” x 0.028”.
www.indiandentalacademy.com

4. The appliance has all the characteristics-
 Simplicity
 Efficiency
 Comfort
 Hygienic
 Esthetic
www.indiandentalacademy.com

5. Neutral 0.022” edgewise slots with double width
brackets on the six anterior teeth, intermediate
single width brackets on premolar teeth, twin
brackets on first molars, 0.022” tubes with mesial
hooks on second molars.
Lingual hooks on molars and lingual cleats on
premolars.
No tips, torque, or any variation in thickness in
bracket or the neutral slot.
www.indiandentalacademy.com

6. ARCHWIRES
 Resilient edgewise arch wires
 0.017” x 0.022”, 0.018” x 0.025”, 0.019” x
0.025”, 0.020” x 0.025”, 0.0215” x 0.028”.
www.indiandentalacademy.com

7. FIRST, SECOND, THIRD ORDER BENDS
 SECOND ORDER BENDS
 In mandibular A/w – antagonistic to
anterior teeth
 In maxillary A/w – complementary to the
anterior segment.
FIRST ORDER BENDS
Affect expansion or
contraction
www.indiandentalacademy.com

8.  Objective – some degree of lingual crown torque in
mandibular teeth & maxillary posterior teeth ; and
some degree of lingual root torque in maxillary
anterior teeth.
Third order bends in mandibular A/W :-
 Incisors: -7°
 -Canines & 1st
premolars : -12°
 2nd
premolars & molars :- -2°
Third order bends in maxillary A/W :
 Incisors: 0°
 Canines & 1st
premolars : -7°
 2nd
premolars & molars :- -12°
THIRD ORDER BENDS
www.indiandentalacademy.com

9. AUXILLARIES
 Elastics and headgear
www.indiandentalacademy.com

10. AUXILLARIES
 Elastics and headgear
www.indiandentalacademy.com