Treatment of a class I malocclusion

Question 1

Class I incisor relationship

Answer 1

Lower incisor

occludes at or below the upper incisor cingulum plateau

Question 2

Class I incisor malocclusion

Answer 2

Crowding
Spacing
Displaced teeth

Question 3

Aetiology of crowding

Answer 3

Imbalance in:

• jaw size
• tooth size
• arch perimeter

Question 4

Repairing crowding

Answer 4

1. Expansion
2. Distal movement
3. Enamel stripping
4. Extraction

Question 5

Expansion

Answer 5

Commonest direction is widening top of arch
Can also bring incisors forward
Limited amount of reduction in canine region

Question 6

Problems with expansion

Answer 6

Relapse
Fenestration of labial plate
Aesthetics

Question 7

Expansion to treat crowding

Answer 7

The “Schwarz Appliance”
-doesn’t work
Expansion in lower arch is very limited, will just relapse
Some scope for doing it in upper arch

Question 8

Studies of mandibular expansion

Answer 8

Average expansion = 3.7mm
Average relapse = 2mm
Conclusion: expansion of arches using removable appliances not very stable

Question 9

Quad helix

Answer 9

Quite efficient

Question 10

Damon system

Answer 10

There are limits to what is stable and can be reapired by moving incisors forward

Question 11

Non-extraction “Arch Development”

Answer 11

Only 10% long-term success
But premolar extractions
-only 30% long-term success

Question 12

Limits of expansion

Answer 12

3mm across back of arch
0mm canine region
2mm bringing incisors forward

Question 13

Fenestration of labial plate

Answer 13

??

Question 14

Aesthetics

Answer 14

Should have been non-extraction - retruded lips

Should have been extraction - protruded incisors and full lips

Question 15

Distal movement of buccal segments

Answer 15

Retract U6 (and 7 if erupted)
Retract premolars and canine
Align canine

Question 16

How to achieve distal movement - upper arch

Answer 16

Headgear (+ URA, TB, or FA)
Non-compliance appliances
Temporary Anchorage Devices

Question 17

How to achieve distal movement - lower arch

Answer 17

Lip bumper

-does not work

Question 18

URA

Answer 18

Upper removable appliance

Question 19

Non-compliance appliances

Answer 19

Pendulum appliance

Distal jet

Question 20

Mid-palatal implants

Answer 20

Quite difficult to take out as they are osseo-integrated

Question 21

Temporary anchorage devices

Answer 21

Screwed into bone, taken out afterwards

Question 22

Distal movement of upper segments used if

Answer 22

Well-aligned lower arch
Half-unit class II molars
Co-operative patient

Question 23

Enamel stripping/ interproximal reduction (IPR)

Answer 23

Abrasive metal strips or air-rotor stripping
Remove up to 0.25mm enamel from contact points
Much better to do stripping when they are already aligned, otherwise taking enamel away from wrong places

Question 24

Types of spacing

Answer 24

Upper midline diastema
Generalised spacing
Missing teeth

Question 25

Extractions

Answer 25

Most common

Question 26

Midline diastema

Answer 26

Upper 1/1 distally inclined with prominent labial frenum
-opens up space distally
-large potential for relapse
-removable appliance?
Upper 1/1 upright
-move bodily
-fixed appliance

Question 27

Generalised spacing

Answer 27

May be a restorative problem

Question 28

Missing lateral incisors

Answer 28

Open space
-restorative replacement
Close space

Question 29

Open or close the space?

Answer 29

Malocclusion
Molar relationship
Space present

Question 30

Malocclusion if missing upper lateral incisors

Answer 30

Class II incisors
-close space
Class III incisors
-open space
(not always, but often)

Question 31

Displaced teeth

Answer 31

Most common displaced tooth is upper permanent canine

Question 32

Displaced maxillary canines

Answer 32

Palatal impaction 85%
Buccal impaction 15%
-usually because not enough space for it
Diagnosis of position is not 100% accurate, CBCT suggests it may be 50:50

Question 33

Displaced canines: palatal impaction

Answer 33

1. Leave in situ, monitor
2. Extract
3. Expose and align
4. Transplant

Question 34

Displaced canines: buccal impaction

Answer 34

Closed exposure (attach gold chain)
Open exposure (apically repositioned flap