fixed appliances

Question 1

What is an fixed appliance and what does it consist of

Answer 1

An appliance which is fixed to the teeth and cannot be
removed by the patient that consists of; brackets, archwires and auxillaries

Question 2

What are the differences between fixed and removable appliances

Answer 2

Fixed gives complex tooth movements and 3D control of teeth whereas URA only provide simple tooth movements such as tipping

Fixed aplliances allow the control of root movement whereas URA give none

Fixed appliances are less dependant on Pt compliance compared to URA

Fixed has a risk of iatrogenic damage whereas URA have less of a risk

Fixed appliances give poor intrinsic anchorage whereas URA gives good intrinsic anchorage

Question 3

When would you use fixed appliances

Answer 3

Correction of mild to moderate skeletal discrepancies

Alignment of teeth

Correction of rotations

Correction of centrelines

Overbite/jet reduction

Closure/creation of spaces

Vertical movement of teeth

Question 4

What is the main Tx goal of ortho

Answer 4

To achieve andrews six keys

Question 5

What are Andrews 6 keys

Answer 5

Tight approximal contacts with no rotations

Class 1 incisors

Class 1 Molars

Flat occlusal plane or slight curve of spee

Long axis of tooth slight mesial inclination, exceot from the lower incisors

The crowns of the canines back to the molards have a lingual inclination

Question 6

what are the components of a fixed appliance

Answer 6

Bracket/ Tube

Band

Archwire

Modules

Auxillaries

Anchorage components

Force generating components

Question 7

What are the components of a bracket

Answer 7

Bracket slot

Tie wings

Bracket base

Question 8

What materials are normally used for brackets

Answer 8

Metal- SS, CoCr, Ti, Au

Polymers

Ceramics

Question 9

How are brackets/tubes bonded to teeth

Answer 9

Composite via acid etch technique

Question 10

How are molar bands bonded to teeth

Answer 10

GI

Question 11

What materials commonly used for arch wires

Answer 11

SS

NiTi

CoCr

Question 12

What are the properties of a NiTi arch wire that makes it good

Answer 12

Flexible

Light continous force

Shape memory
-returns to its og shape and cannot bend

Higher friction than SS

Question 13

What are the properties of a SS archwire that makes it good

Answer 13

Low friction to slide teeth

Formable
-bends and loops

Question 14

What are the force generating components in fixed appliances

Answer 14

Elasatic power chain

NiTi coils

Intra-oral elastics

Active ligatures

Question 15

What different forms of anchorage are there im fixed appliances

Answer 15

Simple

Compound

Reciprocal

Question 16

What is simple anchorage

Answer 16

Pits one tooth against another as they move together

the resistance of the anchorage unit to tipping is utilized to move another tooth with the anchorage tooth combined root surface area two times that of the teeth to be moved

Question 17

What is compound anchorage

Answer 17

the type of anchorage where more than one tooth with greater anchorage potential are used to move a tooth/group of teeth with lesser support

Question 18

What is reciprocal anchorage

Answer 18

the resistance offered by two malposed units, when the dissipation of equal and opposite forces tends to move each unit towards a more normal occlusion

Question 19

How is absolute anchorage achieved

Answer 19

Temporary anchorage devices (TADS)
-Non osseointegrating mini screw

Question 20

What do cortical plates provide

Answer 20

increased resistance to tooth movement and maintains intermolar width

Question 21

What features have a high relapse potential

Answer 21

Diastema/ space closure

Rotations

Palatally ectopic canines

Proclination of lower incisors

Anterior open bite

Instanding upper lateral incisors

Question 22

When would a fixed ortho retainer be used

Answer 22

Space closure

Diastema

Proclination of lower labial segment

Perio cases

Ectopic canines

Instanding upper 2’s

Question 23

What are the main risks of fixed appliances

Answer 23

Decalcification

root resorption

Relapse

Question 24

What is true is true in relation to torque and fixed appliances

Answer 24

Torque is the angulation of the tooth in a bucco-lingual direction