Treatment of a class I malocclusion Flashcards
Class I incisor relationship
Lower incisor
occludes at or below the upper incisor cingulum plateau
Class I incisor malocclusion
Crowding
Spacing
Displaced teeth
Aetiology of crowding
Imbalance in:
- jaw size
- tooth size
- arch perimeter
Repairing crowding
- Expansion
- Distal movement
- Enamel stripping
- Extraction
Expansion
Commonest direction is widening top of arch
Can also bring incisors forward
Limited amount of reduction in canine region
Problems with expansion
Relapse
Fenestration of labial plate
Aesthetics
Expansion to treat crowding
The “Schwarz Appliance”
-doesn’t work
Expansion in lower arch is very limited, will just relapse
Some scope for doing it in upper arch
Studies of mandibular expansion
Average expansion = 3.7mm
Average relapse = 2mm
Conclusion: expansion of arches using removable appliances not very stable
Quad helix
Quite efficient
Damon system
There are limits to what is stable and can be reapired by moving incisors forward
Non-extraction “Arch Development”
Only 10% long-term success
But premolar extractions
-only 30% long-term success
Limits of expansion
3mm across back of arch
0mm canine region
2mm bringing incisors forward
Fenestration of labial plate
??
Aesthetics
Should have been non-extraction - retruded lips
Should have been extraction - protruded incisors and full lips
Distal movement of buccal segments
Retract U6 (and 7 if erupted)
Retract premolars and canine
Align canine
How to achieve distal movement - upper arch
Headgear (+ URA, TB, or FA)
Non-compliance appliances
Temporary Anchorage Devices
How to achieve distal movement - lower arch
Lip bumper
-does not work
URA
Upper removable appliance
Non-compliance appliances
Pendulum appliance
Distal jet
Mid-palatal implants
Quite difficult to take out as they are osseo-integrated
Temporary anchorage devices
Screwed into bone, taken out afterwards
Distal movement of upper segments used if
Well-aligned lower arch
Half-unit class II molars
Co-operative patient
Enamel stripping/ interproximal reduction (IPR)
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
Types of spacing
Upper midline diastema
Generalised spacing
Missing teeth
Extractions
Most common
Midline diastema
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
Generalised spacing
May be a restorative problem
Missing lateral incisors
Open space
-restorative replacement
Close space
Open or close the space?
Malocclusion
Molar relationship
Space present
Malocclusion if missing upper lateral incisors
Class II incisors -close space Class III incisors -open space (not always, but often)
Displaced teeth
Most common displaced tooth is upper permanent canine
Displaced maxillary canines
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
Displaced canines: palatal impaction
- Leave in situ, monitor
- Extract
- Expose and align
- Transplant
Displaced canines: buccal impaction
Closed exposure (attach gold chain) Open exposure (apically repositioned flap
