Fixed Appliances in Orthodontics 1 Flashcards
What are the types of movement in fixed appliances?
Tipping Bodily movement Rotation Torque Vertical movements: extrusion and intrusion
What are the problems with fixed appliances?
Enamel demineralisation
Root resorption - 0-1mm of root apex, reduces long-term prognosis
Periodontal problems - gingivitis/hyperplasia
Unwanted tooth movements
Pulp devitalisation
Soft tissue lacerations
Allergies
What are the positives of using fixed appliances?
Good tooth alignment - corrects rotations, controlled tipping and torque control
Good space closure (bodily movement)
Excellent tooth alignment in planes
What are the components of the fixed appliance?
Brackets
Molar tubes/bands
Arch wires
Auxiliaries
What are the components of the bracket?
Tie wings on the corners and slots down the centre
Which wire is used for the intital movement of teeth?
Ground arch wire - fully engaging the slot around the wire
What is the slot diameter size?
0.022x0.028’’
What is the max dimension wire used?
what happens if it exceeds this?
0.019x0.024
If bigger then will jam the slot, creating friction so high that the tooth cannot move
Which wire is used for initial tooth alignment?
Round wires
How are rectangular wires different?
0.019x0.025
Full 3D control
What are rectangular wires used for?
Space closure and final alignment
What are the different bracket materials?
Metal - SS
Ceramic
Plastic
Why is the bracket base a mesh?
To increase SA and retention
What 3 different aesthetic brackets are there?
Ceramic
Lingual SS
Plastic
What is the problem with plastic brackets?
Fracture
Discolouration
Distortion
What are the problems with ceramic brackets?
Fracture
Debonding - ceramic remnants left of the teeth
Abrasion to other teeth - can only be used in upper teeth so that cant wear lowers
Increased friction - treatment takes longer
Cost
What’s the problems with lingual appliances?
Difficult technique
Cost
Traumatic to tongue
What are the components of lower molar tubes?
Single tube for archwire and hook for auxilaries
What are the components of upper molar tubes?
Additional hook for headgear
Hook for auxillaries
What is used to place molar band on tooth?
Aquagem
How long do you place separator on tooth before fitting molar band? Why place separators?
Place sepeartors for 1 week
More comfortable for patient
Easier for operator
More accurate band selection
How are molar tubes placed on tooth?
direct bond - just stick on top
What are the problems with molar tubes?
Difficult isolation from moisture - more likely to debond
problem with wire if debonds
Cant use with headgear
Don’t need to use separaors
What is the function of archwires?
Active archwire - move the teeth with wire: light forces and flexible
Passive archwire - move teeth along the wire- rigid
What are active archwires?
Nickel titanium - for alignment
What are passive archwires?
Stainless steel, for bodily movement of teeth
How is the force applied to an individual tooth controlled?
By varying the cross-sectional diameter and form of the arch wire and materials
Why is flexible wire better at the initial stages of treatment?
flexible and good resistace to permanent deformation so that displaced teeth can be aligned without the application of excesive forces
In later stages why use a rigid wire?
They engage the wire slot fully, and provide fine control over tooth position while resisting the unwanted effects of other forces e.g. elastic traction
What are the properties of NiTi?
Flexible and elastic, can distort and bounce back
Super-elastic
heat-activated
What are the cross-sectional dimensions for round and rectangular wires?
Round: 0.010’‘-0.020’’
Rectangular: 0.019x0.025
What are the 3 ways of attaching arch wires?
Modules
Wire ligatures quick ties, tie arch wire into bracket more tightly
Self-ligating brackets
What are auxillaries?
What are they used for?
Springs and elastics to close spaces
What are the different elastics?
Elastic bands
Powerchain - elastic chain betweent the teeth
Zing string (power thread) - used when have impacted tooth, want to pull it out slowly
E-links
Traction ligatures - module on the end of stainless steel wire to close space as module contracts and closes the space
What are the different springs used?
Push coil/coil spring - make space, can be SS or NiTi
Closing coil/retraction spring - to close the gap - NiTi has a more continuous level of force
What is in the fixed appliance kit?
Weingarts - gripping archwires Tucker Light wire pilers cutters Crown shears Distal end cutters
