Fixed appliances in ortho Flashcards
Non-orthodontic norms (study)
120 sets models • local dentists • orthodontists • university department Straight teeth Pleasing appearance Bite seemed correct Did not need orthodontic treatment
Patients had never had ortho treatment (study)
1150 study models of orthodontically
treated patients who had exceptionally
good results.
Comparison of non-orthodontic norms & good orthodontic results
6 keys to normal occlusion
- molar relationship
- crown angulation (tip)
- crown angulation (torque)
- no rotations
- tight contacts
key 6 - flat curve of Spee
Key 1
Class I molars
Mesio-buccal cusp of upper molar sits in buccal groove of lower molar
Key 2
Roots tipped distally
- 5 degrees for upper first molars
- 11 degrees on upper canine
- 5 degree on upper central
Key 3
Angle of tooth buccolingually (torque)
Key 4
Rotated molars can use more space, rotated incisors can use less space
Key 5
No crowding
No spacing
Key 6
Flat occlusal plane
Straight wire appliance
Built-in tip values (done by angle of slot
Built-in torque values (angle of bracket)
Built-in in-out values (different bracket incisors)
-for each individual tooth
Main stages of treatment
Levelling and alignment ◦ Space closure ◦ Overjet reduction, ◦ centreline correction Additional stages: ◦ Overbite correction ◦ Crossbite correction ◦ Finishing and detailing
Levelling and aligning stage 1
Vertically (levelling) Bucco-lingually Mesio-distally -need initial canine retraction for bucco-lingual alignment Correct rotations
Choice of initial archwire
Titanium alloys - round wires -NiTi!! -beta titanium (TMA) -superelastic (-stainless steel multistrand)
Problem of tip in canine brackets
Crown moves forward, incisors extrude, bite deepens
Canine lacebacks
Ligature wire under archwire
Prevents canine crown moving mesially
Posterior teeth can move forward
