Correction of mild to moderate skeletal discrepancies (camouflage) Alignment of teeth Correction of rotations Centreline correction Overbite and overjet reduction Closure of spaces/creating spaces Vertical movements of the teeth (extrusion/intrusion)

Made of stainless steel with prewelded attachments: cleats or tubes Requires space prior to placement so requires a separator visit

Fixed Appliance Flashcards by Roisin Mousa

What is a fixed appliance

An appliance which is fixed to the teeth and cannot be removed by the patient

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What does a fixed appliance consist of

brackets, bands, archwires and auxillaries

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What are the features of fixed appliances

o 3D control
o Complex tooth movements
o Control of root
o Less dependant on compliance
o Requires excellent oral hygiene
o Risk of iatrogenic damage
o Poor intrinsic anchorage

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What are the features of removable appliance

o Simple tooth movements (tipping/tilting)
o No control over root movement
o Greater compliance required
o Less risk of iatrogenic damage
o Good instrinic anchorage - due to baseplate covering palate

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When do we use fixed

Correction of mild to moderate skeletal discrepancies (camouflage)
Alignment of teeth
Correction of rotations
Centreline correction
Overbite and overjet reduction
Closure of spaces/creating spaces
Vertical movements of the teeth (extrusion/intrusion)

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What are andrew’s 6 keys

Tight approximal contacts with no rotation
Class 1 incisors
Class 1 molars
Flat occlusal plane or slight curve of spee
Long axis of the teeth have slight mesial inclination except the lower incisors
The crowns of the canines back to the molars have a lingual inclination

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What are andrew’s 6 keys

Tight approximal contacts with no rotation
Class 1 incisors
Class 1 molars
Flat occlusal plane or slight curve of spee
Long axis of the teeth have slight mesial inclination except the lower incisors
The crowns of the canines back to the molars have a lingual inclination

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What is the 7th key of occlusion

Bolton’s ratio
relates to tooth proportions, sizes and formation so everything fits together

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What are the components of a fixed appliance

bracket/tube
band
archwire
modules
auxillaries
anchorage components
force generating components

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What are the components of the bracket

bracket slot
tie wing
bracket base

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What are the different bracket materials

stainless steel, CoCr, Ti, Au

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What does the bracket prescription determine

o Bracket prescription determines the tip, torque and in/out control
o MBT prescription used

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How are brackets bonded on

o Acid etch technique
o Used for brackets and tubes but not bands
o Photoinitiation reaction using light cure 440-480nm wavelength of light
o Utilises micromechanical retention
o The brackets come in sealed pods and they have a dot marker which is a clinical indicator to help with orientation, they go towards the gingiva distally
o Don’t want much flash  caries risk

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What are bands

Made of stainless steel with prewelded attachments: cleats or tubes
Requires space prior to placement so requires a separator visit

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Where are orthodontic bands placed

Tend to be placed only on posterior teeth due to aesthetics
Also consider use if needing to involve heavily restored teeth with not enough enamel to bond to
Orthognathic patients will often have terminal molars banded as they are more robust and harder to dislodge

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How are bands bonded

GI cement

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What are the various arch wire materials

stainless steel
niti
cocr
beta titianium
composite/glass

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What are the features of stainless steel wire

o Working archwires to slide teeth
o Used for moving teeth
o Low friction
o Formable so can put archwire bends and loops

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What are the features of nickel titanium wire

o Flexible
o Light continuous force - wire tries to return to original shape
o Shape memory - wants to return to original shape and cannot bend
o Higher friction than stainless steel- undesirable, slower tooth movement
o Start with round NiTi then onto rectangular Niti then stainless steel

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How do force generating components work

Teeth move by utilising the energy stored in the elastic or spring
sliding mechanism utilised

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What are the different force generating components

elastic power chain
niti coils
intra-oral elastics
active ligature

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What are elastic power chains

 Elastic chain running from hook to appliance on anterior tooth to posterior tooth and it helps pull the buccal segment together
 Elastic loses its properties so the elastic chain will only be 50% as active weeks later so by the time they come back, the elastic needs to be replaced

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What are ni-ti coils

Still have elastic memory but in coil form so when we stretch the coil and works continuously to close the space
Better than elastic as elastic properties degrade

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What are intra-oral elastics

 Can be used for class 3 or class 2 malocclusions
 The patient changes them at home
 Provides specific direction of force and helps guide teeth into ideal position

Where are intra oral elastics placed for class 3

anterior tooth on lower jaw (usually canine) attached to posterior tooth on upper jaw (usually a 6)

Where are intra oral elastics placed for class 2

anterior tooth on upper jaw (usually a canine) attached to a posterior tooth on lower jaw (usually a 6) Useful for reducing OJ and OB at the same time

What is anchorage

resistance to unwanted tooth movement

What theory is anchorage based on

newton’s third law which is every force has an equal but opposite reactionary force

What is simple anchorage

o This is one tooth against the other o E.g trying to move back a canine against a molar o The molar has a bigger root surface therefore the canine will move more than the molar and so the molar is the anchor

What is compound anchorage

More than one tooth used as the anchor Trying to increase the size and surface area against the tooth we are trying to move

What is reciprocal anchorage

Equal forces in both directions E.g diastema closure, two central incisors are of equal weighting and so will move the same way

What are the types of anchorage

absolute anchorage cortical anchorage intermaxillary anchorage headgear

What is absolute anchorage

This is defined as no movement of the anchorage unit (hence zero anchorage loss) as a consequence of the reaction forces applied to move teeth

What is absolute anchorage

This is defined as no movement of the anchorage unit (hence zero anchorage loss) as a consequence of the reaction forces applied to move teeth

How can absolute anchorage be obtained

use of ankylosed teeth or implants

What are temporary anchorage devices

non-osseointigrating mini screw

Why are TADs useful

Revolutionised notoriously difficult cases e.g hypodontia cases Can be placed into interradicular bone and placed in the palate Can be used in the palate when there is a moderate anterior open bite and you are trying to prevent a surgical treatment pathway

What is cortical anchorage

Cortical plates provide increased resistance to tooth movement

What is an example of cortical anchorage

transpalatal arch

How does cortical anchorage work

It moves the roots torwards the cortical plate to dercease the tendency of the molars to move mesially in response to orthodontic force Nance button uses palatal vault for more anchorage reinforcement

What is intermaxillary anchorage

Defined as anchorage in which the resistance units situated in one jaw are used to effect tooth movement in the opening jaw Uses intra-oral elastics

What is headgear

Can be used for anchorage reinforcement Not used much anymore Comes with risk of ocular injuries hence safety mechanisms must be ensured

What is retention

maintaining the final tooth position with a passive orthodontic appliance

What are features with high relapse potential

o Diastema/space closure o Rotations o Palatally ectopic canines o Proclination of lower incisors o Anterior open bite o Instanding upper lateral incisors

What are the 2 types of removable retainers

PFR hawley

What are the features of PFR

Variety of materials and thicknesses Can include prosthetic tooth for aesthetics Well tolerated Usually 2 wks full time wear and then night only there after

How does hawley retainer work

Labial bow to control incisors and canines Not well tolerated in the lower arch

What are the indications of fixed retainers

* Spaced closure * Diastema * Proclination of lower labial segment * Periodontal cases * Ectopic canines * Isntanding upper 2s

What are the features of bonded wire retainer

* Requires careful monitoring and interdental cleaning * Ensure composite attachments intact and sound * Refer back to the orthodontist if any problems

What are the main risks of fixed appliance

Decalcification Root resorption Relapse Enamel Wear

What is the average root resorption

on average 1mm of root length per teeth, importance of pre-op radiograph to ensure adequate root length prior

What increases risk of root resorption

 Higher risk roots are narrow/tapered roots  Spindly roots  Shorter roots

Describe the patient journey

assessment/diagnosis tx plan commence tx routine adjustments

How long does the average ortho case take

18-24 months

How long does a hypodontia & orthognathic case take

24-30 months

How long does a hypodontia & orthognathic case take

24-30 months

How often are routine adjustments made

4-8 wks

What are the initial problems encountered

o Pain o Mucosal irritation o Ulceration o Appliance breakage