Fixed appliances in orthodontics theory and components Flashcards
Type of tooth movement
Tipping •Bodily movement • Rotation •Torque •Vertical movements -extrusion -intrusion (removable appliances can only tip)
Problems with fixed appliances
- Enamel demineralisation/caries
- Root resorption
- Periodontal problems
- Unwanted tooth movements
- Pulp devitalisation
- Soft tissue lacerations
- Allergies
Periodontal problems
Gingivitis
Gingival hyperplasia
-due to plaque build up because it is harder to maintain oral hygiene
Fixed appliances
• Good tooth alignment -corrects rotations -controlled tipping -torque control • Good space closure (bodily movement)
Fixed appliance components
Brackets
Molar tubes/ bands
Archwires
Auxiliaries
Brackets
Pre-adjusted edgewise brackets (stainless steel)
- tie wings
- slot
- bracket slot size is 0.022”x 0.028”
Round archwire
Initial tooth alignment
0.014
Rectangular archwire
Full 3 control
0.019” x 0.025”
Space closure and final alignment
-better control over tooth movement
Bracket materials
Metal - stainless steel
(Plastic)
Ceramic
(Gold)
Bracket base
Foil-mesh
-increase surface area and retention
Etch tooth (self-etching primer) and use composite to bond it on
Light cure once bracket is on
Bracket placement
Middle of tooth
Aesthetic brackets
Plastic
Ceramic
Lingual (SS)
Plastic brackets - problems
Fracture
Distortion (creep)
Discolouration
Ceramic bracket - problems
Fracture -in use -debonding Abrasion of other teeth Increased friction Cost
Ceramics
Use in upper arch only
Can be used in lower arch if there is no overbite
Lingual appliances
Difficult technique
Cost
Traumatic to tongue
Lower molar bands
Single tube for archwire
Hook for auxiliaries
Upper molar bands
Additional tube for headgear (round) - do not use for A/W
Hook for auxiliaries
32 sizes for each tooth
Separators
A week before they have their bands fitted 1 week More comfortable for px Easier for operator More accurate band selection -can be painful for teenagers
Molar tubes - direct bond
Difficult isolation from moisture - more likely to debond
Problem with wire if debonds
Can’t use with headgear
Archwires - function
Active archwires - move teeth with wire -light forces -flexible Passive archwires - move teeth along wire -rigid
Active archwires
Nickel-titanium (for alignment)
- super-elastic
- heat-activated
Passive archwires
Stainless steel (for bodily movement of teeth) -need to use something else e.g. auxiliary to move teeth
Stainless steel - elastic properties
Hooke’s law
Very little elastic deformation
Nickel titanium elastic properties
Superelastic properties
Archwires - cross-section
Round 0.01”x0.02
Rectangular wire 0.019”x0.025”
Attaching archwire
Elastic modules Wire ligatures (quick ties) Self ligating brackets -less friction on bracket (now been disproven) -trap door
Auxiliaries
Elastics
Springs
Elastics
Elastic bands Powerchain Zing string (powerthread) E-links Traction ligatures
Traction ligature
Module on a SS ligature
Elastics
Worn between top and bottom teeth
Named by malocclusion we are trying to correct
Power chain
Elastic chain in between the teeth
Put quick ties on first, powerchain on top
Occasionally used across spaces
Zing string
Elastic thread
Trying to pull a tooth more gently
E-links
TP orthodontics
Not used as much
Close space, like powerchain but long elastic above tooth
Springs
Push coil/ coil spring -stainless steel -nickel-titanium Closing coil/ retraction springs -nickel-titanium
Fixed appliances kit
Weingarts for gripping archwires
Tucker for tucking ends of quickties
Adams pliers for making bends in archwires or adjusting clasps on removable appliances
Light wire pliers/ cutters for cutting lights wires/ elastic
Crown shears for cutting ends of quickties
Distal end cutters for cutting end of archwires
Invisalign
Increasingly popular
Not on NHS
Can’t move teeth as much
Around 4.5k
What are the ways to manage anchorage with fixed appliances?
Only move one tooth per side Headgear Class II elastics Transpalatal arches Extend base plate of upper removable appliances Use large anchor unit Light forces Extraction of teeth
