Development of SWA

Question 1

Who started pre-adjusted appliance

Answer 1

Andrews

Question 2

What did Andrews do?

Answer 2

• 120 non ortho models
• ideal occlusion
• Andrew’s 6 keys of normal occlusion
• Norms and standard deviation
• Measured in-out, tip, torque
• build into bracket

Question 3

Andrews 6 Keys

Answer 3

1) Correct torque
2) Correct tip
3) No rotations
4) No spacing or crowding
5) Flat COS
6) Cl. I molar rs

Question 4

3 reference points for brackets

Answer 4

1) Center of clinical crown
2) Long axis of clinical crown
3) Thickness of clinical crown

Question 5

How was in-out, torque, tip incorporated in brackets

Answer 5

1) In-out - thickness of bracket base
2) Torque in base
3) Tip - into face of bracket

Question 6

Advantages

Answer 6

• Reduced wire bending
• Allow for sliding mechanics
• Straight archwire after alignment of arch
• Less technique sensitive

Question 7

Disadvantages

Answer 7

• Exo/Non-exo brackets increase inventory
• Torque not fully expressed
• Biological and anatomical variations

Question 8

Amount of archwire play

Answer 8

10deg of play between 19x25ss in 0.022” slot

Question 9

What are bends for

Answer 9

To overcome:

• bonding error
• anatomical difference
• skeletal discrepencies

Question 10

Roth differences to Andrews

Answer 10

• no separate exo brackets
• more torque on Ui esp. impt for incisor retraction
• more canine tip for cupsal guidance to achieve functional occlusion
• more torque on Mx molars to prevent P hanging cusp (non working side interference)
• U3 more tip less torque
• L3 more tip

Anterior brackets more incisorly placed than Andrews’ FACC

Question 11

MBT differences

Answer 11

• more torque Ui
• more Li crown torque (minimise proclination of Li)
• less tip to reduce anchorage
• more torque in L molar region to prevent rolling in during SC