Edward H. Angle was a pioneering orthodontist who developed concepts of occlusion and malocclusion classification in the late 1800s. He opposed extracting teeth for orthodontic treatment. Several orthodontists further developed his ideas, creating new appliances like the Edgewise and Begg appliances to improve control of tooth movement and occlusion. In the 1970s, Larry Andrews identified characteristics of ideal occlusion from studying untreated ideal bites. He developed the preadjusted edgewise appliance and "Six Keys of Occlusion" to achieve optimal occlusion without wire bending. Ronald Roth built on Andrews' work by incorporating the temporomandibular joint.

2. Edward H. Angle
Extractions for crowding were common until late
1800s
As a prosthodontist, Edward H. Angle developed the
concept of occlusion

3. Edward H. Angle
Gave the first clear and simple classification of
malocclusion
The upper first molars were the key to occlusion

4. Defined the line of occlusion
as a smooth catenary curve
passing through the central
fossa of each upper molar and
across the cingulum of upper
canine and incisor teeth
Best esthetics are achieved
when the patient had an ideal
occlusion
Strongly opposed extractions

5. ANGLE’S E ARCH (1904)
Bands on molar teeth
Heavy archwire with threaded ends, ligated to
teeth
Delivered heavy interrupted force
Capable of tipping movement only

6. Pin & Tube (1910)
Bands were placed on other teeth with a vertical tube
on each tooth
A soldered pin from a smaller arch wire was
placed, and position changed every visit
Theoretically capable of great precision, yet
impractical in clinical use

7. Ribbon arch (1915)
The first appliance to use a true bracket
Provided vertical rectangular slot
Gold ribbon 10 x 20 archwire was used
Good spring qualities
Efficient alignment
Poor control of root position
due to high resiliency of wire
Poor control of mesiodistal tip

9. Edgewise (1928)
A 0.022 x 0.028 slot was oriented horizontally
A 0.022 x 0.028 rectangular precious archwire rotated
90° to the orientation it had with the Ribbon
appliance.
Excellent control of crown & root position in all three
planes

10. Edgewise
Non-programmed appliance

11. Edgewise appliance
Required bends in the
archwire in 3D:
First order
Second order
Third order

12. Edgewise appliance
Treatment phases:
Correction of interarch relationship, leveling and
alignment
Opening or closing spaces
Finishing

13. Edgewise appliance
Advantages:
Precision
Mechanical simplicity
Cleanliness
Versatility
Disadvantages
Lack of system and number of variants
Dependence on wire bending
Friction
Anchorage demands

14. Edgewise
Modifications to Edgewise (Partially programmed):
Angle: angulation of brackets on the band
Jarabak and Fizzel: “building treatment into the
appliance” Incorporation of tip and torque
Holdaway: increase bracket angulation next to
extraction site
Raising upper lateral base: To eliminate need for offset
bend

15. Charles Tweed
Reintroduced tooth extraction
due to facial esthetics and occlusal
stability
Philosophy: malocclusion was
genetically determined due to
tooth and jaw mismatch in sizes
Adapted the edgewise appliance
for extraction treatment
Used the subdivision approach for
anchorage control by moving the
canines distally then retracting
the incisors

16. Charles Tweed
Modified Edgewise appliance by using the 0.022” in
different widths
Double width for anteriors, intermediate for PM, twin
slot in 6s, tubes on 7s

17. Reymond Begg
 At first a follower of Angle’s
non-extraction
 After cases of poor profile
esthetics and relapse, he
advocated for tooth extraction
 Philosophy: tooth size
reduction is required to
compensate for dietary
changes

18. The Begg appliance (1956)
Modified from the ribbon arch to get
better control of root position:
Narrower slot, so less friction
Replaced the precious metal with 0.016
round SS
Turned the bracket upside down so it
pointed gingivally
Added auxiliary springs to control root
position
Based on the use of light forces and tipping
teeth
Differential force concept: The force
required to tip a tooth is less than the force
required to move it bodily. The tooth
crowns are initially tipped into their
desired position using intermaxillary
elastics. The roots are then uprighted as a
separate procedure using auxiliary springs

19. Treatment stages:
Stage I:
Alignment and leveling
Closure of spaces
Overcorrection of rotations
Overcorrection of OB and OJ
Correction of inter arch relationships
Stage II:
All extraction spaces closed
The objectives achieved in stage 1 maintained
Stage III:
Correction of tooth angulations and inclinations
The objectives achieved in stage 1 and 2 maintained
The Begg appliance (1956)

21. Begg appliance
Advantages:
Systemic approach of stages
Better anchorage
Lack of friction
Free tipping
Speed of tooth movement
Differential tooth movement
Minimal wire binding through use of auxiliaries
Minimal post-treatment relapse

22. Begg appliance
Disadvantages:
Emphasis on extractions
Reliance on elastics
Complexity in finishing
Oral hygiene difficulties
Breakages
Lack of precision
Lack of flexibility

23. Larry Andrews
Developed preadjusted edgewise
based on his “6 keys of occlusion”
Studied 120 subjects with ideal occlusion
with no history of orthodontic treatment
His appliance eliminated the need for
wire bending
Proper bracket position allows the teeth
to be placed with a straight wire into an
occlusal contact with an excellent
mesiodistal inclination (tip) and excellent
faciolingual inclination (torque)
The brackets placed at the midpoint of
the facial axis of the clinical crown
(FACC)

24. Andrews’ 6 keys of occlusion
(1972)
Correct interarch relationship.
Correct crown Angulation (Tip).
Correct crown Inclination (Torque).
No Rotations.
Tight Contacts.
Flat Curve of Spee.

25. Andrews’ 6 keys of occlusion
Interarch relationships:
The distal surface of the distobuccal cusp of the
upper first permanent molar made contact and
occluded with the mesial surface of the mesiobuccal
cusp of the lower second molar. The mesiodistal cusp
of the upper first permanent molar fell within the
groove between the mesial and middle cusps of the
lower first permanent molar
Canines and premolars occlude in a cusp-embrasure
way buccally, and cusp-fossa lingually

26. Andrews’ 6 keys of occlusion
1. Improper molar relationship.
2. Improved molar relationship.
3. More improved molar
relationship.
4. Proper molar relationship.

27. Andrew’s 6 keys
Crown angulation:
Angulation (or tip) of the long axis of the crown, not
to angulation of the long axis of the entire tooth.
The gingival portion of the long axis of each crown
was distal to the incisal portion.
Varied between teeth types
Consistent within one type

28. Andrews’ 6 keys of occlusion
Crown angulation (tip)— long axis of crown
measured from line 90 degrees to occlusal plane.

29. Andrews’ 6 keys of occlusion
The degree of tip of incisors determines the amount
of mesiodistal space they consume and, therefore, has
a considerable effect on posterior occlusion as well as
anterior esthetics

30. Andrews’ 6 keys of occlusion
Crown inclination:
Labiolingual or buccolingual inclination of the long
axis of the crown, not to the inclination of the long
axis of the entire tooth.
Anterior teeth: labial crown inclination
Upper posteriors (canines to molars):
Lingual crown inclination. Similar
for canines and premolars and was
slightly increased in molars.
Lower posteriors (canines to molars):
Lingual crown inclination
progressing distally

31. Andrews’ 6 keys of occlusion
Crown inclination is determined by the resulting angle
between a line 90 degrees to the occlusal plane and a line
tangent to the middle of the labial or buccal clinical
crown.

32. A, Improperly inclined
anterior crowns result in all
upper contact points being
mesial, leading to improper
occlusion.
B, Demonstration, on an
overlay, that when the
anterior crowns are properly
inclined the contact points
move distally, allowing for
normal occlusion.

33. Andrews’ 6 keys of occlusion
Relationship between tip and torque:
The more we torque the anterior portion of an upper
rectangular arch wire, a proportional amount of
mesial tip of the anterior crowns is lost.
The ratio is approximately 4:1. For every 4 degrees of
lingual crown torque, there is 1 degree of mesial
convergence of the gingival portion of the central and
lateral crowns

34. Andrews’ 6 keys of occlusion
This relationship is called
The wagon wheel effect

35. Andrew’s 6 keys
Rotations
Teeth should be free of undesirable rotations
Rotated posterior teeth would occupy more space
Tight contacts
No spaces
Tooth size discrepancy should be corrected, so that
space closure would not affect occlusion

36. Andrews’ 6 keys of occlusion
Curve of Spee
The goal is to achieve a
flat occlusal plane
(overcorrection)
Deep occlusal plane
makes it impossible to
achieve ideal occlusion

37. The Straight Wire Appliance
Theoretical basis:
Most individuals have normal teeth regardless of occlusal
type
The size of normal crowns has no effect on their ability to
achieve optimal occlusion
Jaws must be normal and correctly related to allow teeth to be
correctly positioned and related
Dentitions with normal teeth in jaws that are correctly related
can be brought to optimal occlusal standards

38. SWA
Brackets were positioned in the centre of clinical
crown
Clinically, using the standard
appliance showed difficulties.
The roller-coaster effect:
Deepening of the anterior over bite
and creation of a lateral open bite
during space closure.
To overcome these difficulties Andrews introduced
different sets of brackets

39. SWA Prescriptions
Anterior bracket sets were introduced for different skeletal
patterns to facilitate the establishment of a normal incisor
relationship:
1. Set S: for Class I malocclusions (ANB between 1 and 5)
2. Set A: for Class II skeletal patterns (ANB more than 5)
3. Set C: for Class III skeletal patterns (ANB less than 1)

40. Translation brackets: compensate for the unwanted tooth
movements that occurred during closure of extraction
spaces
The bracket sets of molars, premolars and canines had
increased tip and anti-rotation according to how much
translation of the tooth was expected
T1: Minimum
T2: Medium
T3: Maximum
T4 brackets are molar brackets without the five degrees of
tip in the standard prescription
SWA Prescriptions

41. Ronald Roth
Recognized the importance of
Andrew’s concept, but only in
harmony with properly functioning
temporomandibular joint
Incorporated “The six keys to normal
occlusion with mandible in
gnathologic centric relation”
Introduced the repositioning splint to
find CR

42. Ideal Functional Occlusion
Coincident CR and CO
Occlusal forces directed down the long axis of teeth.
0.005” between the anterior teeth in occlusion.
In lateral excursion and protrusion the incisors and
canines disocclude the posterior teeth.
Protrusion with dis-occlusion of posterior teeth.
Working side ‘canine guided’
Non-working

43. Roth’s modifications
Overcorrection, due to:
High relapse
Compensate for play between archwire and the
bracket
Curve of Spee deepens after treatment
Teeth adjacent to extraction site tend to rotate and
tip towards the extraction site (rollercoaster effect)
As teeth in the buccal segments settle they will rotate
and tip mesially, so by overcorrection they will settle
better than teeth that are already mesially inclined
As band spaces close, there is a corresponding loss of
torque of the anterior teeth

44. Roth’s prescription
One appliance fits all
Available in 0.018”, 0.022” slots
Bracket positioning: Andrew’s FA point is the
reference:
Incisors: more incisally
Lower canines: more gingivally

46. Bennett-Mclaughlin
Higher torque
Deliver light continuous force
Decreased tip for anterior teeth
Design :
Standard
Mid-size
Clarity

47. MBT
Bracket design :
Mid-size metal brackets
Rhomboidal shape
Torque in base
The 0.022 not the 0.018 slot
Thicker 0.5 mm bracket on upper second premolar if
they are small

48. MBT
Versatility of bracket system: to avoid wire binding
Bracket positioning
Anchorage control early in treatment
Group movement where possible
Canine laceback: retraction, prevent mesial
movement
correct midline, protect flexible archwire
Bendback: to prevent mesial movement

49. Peter Kesling
Combined Begg’s light forces and
anchorage control with edgewise’s
better finishing in the Tip-edge
system
Relies on free tooth tipping during
the initial phase of treatment.
Using rigid rectangular archwires to
upright teeth later

50. The Tip-Edge appliance
This has been achieved by
designing a narrow preadjusted
edgewise bracket with wedges
removed from each side of the
archwire slot, which allow the
bracket to tip up to 25°
mesiodistally
As the bracket tips, the width
of the slot increases

51. The Tip Edge Appliance

52. Advantages:
Permits tooth tipping in early
stages of treatment
Progressive torque application
Improved precision and finishing
Versatility is increased
Expresses all the treatment built
into the bracket
Overtreatment
The Tip Edge Appliance

53. The Tip Edge Appliance
Disadvantages:
A relatively poor rotational control due
to narrow single wing bracket
Friction (due to elastomeric ligation)
Dependence on intermaxillary elastics
Relative complexity in finishing stage
Rigid design
Dependence on extraction treatment

54. Thank you