Fixed Appliances Flashcards
What are spot welded brackets?
The base and body are made separately and then stuck together
What are injection moulded brackets?
The base and bracket are moulded together in a jig
What are the 3 orders of movement built into brackets?
1st order - in/out
2nd order - tip
3rd order - torque
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
What is acid etchant?
37% o-phosphoric acid
What is the failure rate of molar bands?
5%
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
What are the reasons for bonding second molars?
- anchorage
- overbite reduction
- orthognathic surgery
- expansion
What are methods of active space closure?
- powerchain
- NiTi closing coil
- burman lig
- e links
- closing loops
- intra oral elastics
- push coil
What can powerchain be used for?
- closing spaces
- maintain closed spaces
- retraction of teeth
- traction on impacted teeth
- derotate teeth
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
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
What is the benefit of quick ligatures other elastomeric modules?
- improved cleaning
- full engagement of wire/bracket
- reduced friction
What can cause dilaceration of a root?
- previous trauma
* present during development
What is dilaceration of a root?
Curve to the tip of the root
What are the phases of fixed appliance treatment?
- Anchorage planning
- Level and align teeth
- Overbite reduction
- Overjet reduction
- Space closure
- Finishing and detailing
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
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
What are commonly used bracket prescriptions?
MBT
Roth
Andrew’s
Damon
What are the 3 orders of a bracket prescription?
1st order - in out
2nd order - tip
3rd order - torque
Why etch teeth prior to bonding?
Stronger micro mechanical bond
Exposes crystalline structures of the enamel
Why is the bracket base meshed?
To increase the bond strength
Allows composite to flow into the mesh
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
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
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
