Fixed Appliances Flashcards by Sophie Bicknell

What are spot welded brackets?

The base and body are made separately and then stuck together

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What are injection moulded brackets?

The base and bracket are moulded together in a jig

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What are the 3 orders of movement built into brackets?

1st order - in/out
2nd order - tip
3rd order - torque

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What is direct and indirect bonding?

Direct bonding - brackets are placed individually onto teeth

Indirect bonding - brackets are placed onto models in the lab and then transferred to teeth using a positioning tray

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What is acid etchant?

37% o-phosphoric acid

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What is the failure rate of molar bands?

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What is the bonding process?

isolate teeth using cheek retractor and suction
dry teeth - suction and air dry
place etchant
rinse etchant - water and suction
dry teeth - oil free compressed air and suction
place unfilled resin or primer
place bracket - mid point of the long axis of the clinical crown
remove excess flash
light cure - 10 second interspace

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What are the reasons for bonding second molars?

anchorage
overbite reduction
orthognathic surgery
expansion

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What are methods of active space closure?

powerchain
NiTi closing coil
burman lig
e links
closing loops
intra oral elastics
push coil

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What can powerchain be used for?

closing spaces
maintain closed spaces
retraction of teeth
traction on impacted teeth
derotate teeth

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Why may space closure be slow?

Patient factors
• biological response
• breakages
• missed appointments 
• nail biting 
• distorted wire / blocked tube
• poor OH - gingival bunching 
Operator factors
• too much or too little force
• too much friction 
• occlusal factors 
• angulation of roots

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What factors increase root resorption?

root shape - pipette roots, blunt roots
previous root resorption
elastic wear
prolonged treatment
rectangular wires - torque on teeth
nail biting
trauma
previous orthodontic treatment
long movement of tooth

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What is the benefit of quick ligatures other elastomeric modules?

improved cleaning
full engagement of wire/bracket
reduced friction

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What can cause dilaceration of a root?

previous trauma

* present during development

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What is dilaceration of a root?

Curve to the tip of the root

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What are the phases of fixed appliance treatment?

Anchorage planning
Level and align teeth
Overbite reduction
Overjet reduction
Space closure
Finishing and detailing

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What dietary advice would be given to a patient in fixed appliances?

avoid fizzy and acidic drinks
avoid sticky and hard foods
do not bite into foods, cut food up into small pieces
no chewing pens or nails
fruit juices and smoothies at meal times
water, milk and unsweetened tea or coffee in between meals

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Instructions to give patient on the placement of intra oral elastics?

where to place
how often to wear
practice inserting and removing
placement elastics daily for a new pair
if one snaps replace both for an equal force
only remove when brushing teeth and playing sports with a mouth guard
if you run out contact the practise for more
take a photo as a memory, if you do forget contact the practice so they can tell you how to wear

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What are commonly used bracket prescriptions?

MBT
Roth
Andrew’s
Damon

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What are the 3 orders of a bracket prescription?

1st order - in out
2nd order - tip
3rd order - torque

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Why etch teeth prior to bonding?

Stronger micro mechanical bond

Exposes crystalline structures of the enamel

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Why is the bracket base meshed?

To increase the bond strength

Allows composite to flow into the mesh

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What are the advantages of self ligating brackets?

full wire engagement
less chair side assistance needed
less chair side time
less appointments
improved OH
less friction

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What are the disadvantages of self ligating brackets?

practice needed
clips opening in between appointments
clips fracturing
no partial ligation
wire slides
cost
no evidence of faster alignment

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What are the advantages of plastic brackets?

More aesthetic

What are the disadvantages of plastic brackets?

* staining * lack of strength * deformation * lack of torque * poor abrasion resistance

What are the advantages of lingual brackets?

* aesthetics * easier bite opening and arch expansion * no labial decalcification

What are the disadvantages of lingual brackets?

* difficult to access * small bracket inter span- difficult rotational control * cost * sore to tongue * affects speech

What are the advantages of ceramic brackets?

* aesthetics * popular * better than plastic

What are the disadvantages of ceramic brackets?

* friction * harder than enamel - can cause wear * risk of enamel fracture on Debond * can be brittle and fracture * expensive * can have poor tie wings = difficult to place auxiliaries * increased friction

What are the 2 types of ceramic brackets?

Polycrystalline - more opaque | Monocrystalline - clear

What are the advantages of conventional edgewise brackets?

* provide good sliding mechanics * good finishing * can have prescriptions inbuilt

What are the disadvantages of conventional edgewise brackets?

* ignores biological variation * friction * time consuming - ligation * OH - elastomeric modules accumulate plaques

Why is GIC used to cement bands?

* fluoride releasing * adherent to enamel * sets when in contact with saliva

What are the advantages of molar bands?

* less technique sensitive * less chance of Debond compared to a bracket * increased stability * provide additional attachments e.g headgear, TPA, quad helix

What are the disadvantages of molar bands?

* separation needed prior to bands * less aesthetics * irritate gingiva * slower to bond than brackets * more appointments needed * increased cost * spaces can be present after Debond

What are the different types of separation prior to band placement?

Elastomeric seps Separating springs Brass wires

What are the advantages of elastomeric seps?

Easy to place Good separation Easy to remove

What are the disadvantages of elastomeric seps?

Uncomfortable 1 week between appointments Easily displaced

What are the advantages of separating springs?

Good for tight contacts Gentle separation Good for adults

What are the disadvantages of separating springs?

Awkward to remove 1 week between appointments Easily displaced

What are the advantages of brass wires for separation?

Good for tight contacts Comfortable Good long term

What are the disadvantages of brass wires for separation?

Uncomfortable to place Time consuming to place Difficult to remove

Why are molar bands used?

* restricted access and moisture control = difficult bonding * large restorations and lack of enamel = difficult bonding surface * used in conjunction with other appliances - headgear, quad helix, TPA * brackets can’t be bonded to amalgam, poor enamel, porcelain, fluorosis * if patient frequently breaks brackets

What effects do Class II elastics have?

* extrude lower molars - open bite * reinforce anchorage * mesial movement of lower buccal segment * distal movement of upper buccal segment * procline lower incisors

What are the components of a bracket?

* base * body * tie wings * hooks * vertical and horizontal slots * bracket identification - mesio distal

What are possible problems with a quad helix?

* band becomes loose - caries issue * tongue irritation * hypoplastic palatal mucosa * may become embedded * first molar can drop - which can reduce overbite * limited skeletal change

What is a quad helix used for?

Posterior expansion of maxillary teeth | Can be activated to achieve molar derotation

What are the advantages of sliding mechanics for space closure?

* minimal wire bending * less time consuming * easier to maintain arc form compared with closing loop

What are the disadvantages of sliding mechanics for space closure?

* high friction * possible uncontrolled tipping if in a light wire * loss of anchorage

What is a lingual arch used for?

* to hold the molars (anchorage) | * can be used as a space maintainer

How much is a quad helix expanded by?

1/2 tooth width either side

What are advantages of quad helix?

* can derotate molars * does not rely on patient co operation * good retention * can incorporate fixed appliances * more cost effective than URA * provide differential expansion

What thickness wire is used for a quad helix?

0.9mm SS

What factors can affect bond strength of a bracket?

* moisture control/contamination * etch not on tooth for long enough * enamel defect * restoration of tooth * composite not set

What should be checked prior to Debond?

* the brace hasn’t broken * no changes in tooth position * correct provisions for retainers * patient is happy * spaces closed

What are ceramic brackets made from?

Aluminium oxide - either mono crystalline or polycrystalline in

What is the composition of a niti wire?

52% nickel 43% titanium 3% copper

What is in self etching primer?

Methacrylated phosphoric acid esters

When would 4s be extracted?

Permit correction of more anterior crowding or a bigger overjet

Why would 5s be extracted?

If less anterior crowding or overjet is needed to be corrected