fixed appliances Flashcards
definition of fixed appliances
An appliance which is fixed to the teeth and cannot be removed by the patient
Consists of brackets, bands, archwires and auxillaries
Precision tooth movers
fixed vs removable appliances
tooth movements
fixed - 3D
removable - simple
fixed vs removable appliances
root movement
fixed - control over, able to do complex tooth movement
removable - no control over root
fixed vs removable appliances
pt compliance
fixed - no dependent
removable - dependent on
fixed vs removable appliances
OH level
fixed - needs excellent
removable - can be taken out to aid OH
fixed vs removable appliances
risk of iatrogenic damage
fixed - greater
removable - less
fixed vs removable appliances
intrinsic anchorage
fixed - poor
removable - good (baseplate)
when to use fixed appliance
7
Correction of mild to moderate skeletal discrepancies
* Camouflage (accepting underlying mild skeletal discrepancy and trying to get class I incisor relationship)
Alignment of teeth
Correction of rotations
Centreline correction
Overbite and overjet reduction
Closure of spaces/ creating spaces
Vertical movements of teeth (extrusion/intrusion)
tx goal
andrew’s 6 keys
Tight approximal contacts with no rotations.
Class I incisors.
Class I molars
Flat occlusal plane or slight curve of Spee.
Long axis of the teeth have a slight mesial inclination except the lower incisors.
The crowns of the canines back to the molars have a lingual inclination.
andrew’s 6 keys
Tight approximal contacts with no rotations.
Class I incisors.
Class I molars
Flat occlusal plane or slight curve of Spee.
Long axis of the teeth have a slight mesial inclination except the lower incisors.
The crowns of the canines back to the molars have a lingual inclination.
7 components of a fixed appliance
Bracket/tube
Band –* good if heavily restored/MIH for bonding, good robust end point of appliance
*
Archwire – changed at most visits, depending on prescription
Modules / doughnuts –* bands that are changed every visit*
Auxiliaries – chains etc
Anchorage components
Force generating components – coils, springs etc
molar bands and molar tubes
used for
good if heavily restored/MIH for bonding, good robust end point of appliance
molar tube – more discreet and less harsh than molar bands, for particular tooth – not universal
most commonly used type of archwire
straight wire
in/out/tip/torque already built in, no need for wirebending
3 components of brackets
Bracket slot
Tie wings
Bracket base
materials brackets can be made of
3
Metal
SS, CoCr, Ti, Au
Polymers
Ceramics
molar bands
made of and how to place
Stainless steel with prewelded attachments
* Tubes or cleats
Require space before placement
* Separator visit
bonding ortho appliances to teeth
2 types
Composite via acid etch technique
* Used for brackets and tubes NOT bands
* Photo-initiation reaction using light cure 440-480nm wavelength of light
* Micromechanical retention
Glass Ionomer
* For molar bands
composite via acid etch bonds
ortho brakets and tubes to teeth
Photo-initiation reaction using light cure 440-480nm wavelength of light
Micromechanical retention
glass ionomer bonds
molar bands only
composite applied to brackets how
can get pre-coated brackets - less flash, more efficient but £££
or apply one by one from composite tube
etch system options for ortho
one system etch and bond - less concern over isolaation (no need ti wash/dry in between) so more efficient
so seperate etch and bond system not preferred
materials for archwires
various materials, shapes and sizes
Stainless Steel (SS)
Nickel Titanium (NiTi)
Cobalt Chromium (CoCr)
Beta-Titanium (TMA)
Composite/glass
nickel titanium properties as an archwire
4
Flexible
Light continuous force
Shape memory
* Return to original shape
* Cannot bend
Higher friction than SS
stainless steel properties as an archwire
2 main
**Working archwires to slide teeth (low friction) **
Formable
* Archwire bends
* Loops
force generating components of fixed appliances can be
4
Teeth move by utilising the energy stored in the elastic or spring
Sliding mechanics
* elastic power chain
* NiTi coils
* Intra-oral elastics
* Active ligature
anchorage is
resistance to unwanted tooth movement
newton’s 3rd law:Every force has equal but opposite reactionary force
newton’s 3rd law
Every force has an equal but opposite reactionary force
first aspect of ortho tx planning is
anchorage
plan carefully to avoid unnecessary complications
simple anchorage
1 larger tooth and 1 smaller tooth so smaller tooth moves
compound anchorage
Inc SA size against tooth going to move – inc movement of smaller tooth area
less unwanted tooth movement, more favourable
reciprocal anchorage
equal weighting so move at same rate
e.g. for Diastema
absolute anchorage
High anchorage demanding case but v imp that no unwanted tooth movement - Hard
options:
* Temporary anchorage devices (TADS)
* Non osseointegrating mini screw
* Major development in orthodontics
* Anchorage control
* Tooth movement mechanics
5 options for absolute anchorage
- Temporary anchorage devices (TADS)
- Non osseointegrating mini screw
- Major development in orthodontics
- Anchorage control
- Tooth movement mechanics
cortical anchorage
Cortical plates provide ↑ resistance to tooth movement
Maintains Intermolar width
e.g. Using transpalatal arch, palatal nance button
anchorage options
6
simple
compound
reciprocal
absolute
cortical
intermaxillary
headgear in fixed appliances
use is in decline
Must ensure appropriate safety mechanisms
* Written and verbal instructions
retainers
Appliances designed to prevent relapse
* Fixed
* Removable
Must be stressed at consent stage of treatment lifelong retention required
retention is
maintaining the final tooth position with a passive orthodontic appliance
lifelong retainers - fixed or removable
malocclusion features with high relapse potential
6
- Diastema/ space closure
- Rotations
- Palatally ectopic canines
- Proclination of lower incisors
- Anterior open bite
- Instanding upper lateral incisors
removable retainers
Pressure formed retainers Clear overlay retainers)
* Variety of materials and thickness
* Can include prosthetic tooth for aesthetics
Well tolerated !
Retainer wear pattern for removable pressure formed retainer
* Varies between clinicians
*2 weeks full time wear except for eating and drinking, night only thereafter
or Straight to nights only *
Hawley is old metal removable retainer
fixed orthodontic retainers
used for what situs esp
higher relapse situ, need enough space and clearnace
- Spaced closure
- Diastema
- Proclination of lower labial segment
- Periodontal cases
- Ectopic canines
- Instanding upper 2’s
For some Orthodontists all cases
fixed ortho retainers
made of
require
Bonded wire retainer - can be lab made (better) or chairside
Requires careful monitoring and interdental cleaning
* Ensure composite attachments intact and sound
* Refer back to orthodontist if problems
main risks of fixed appliances
3
Decalcification
Root Resorption
Relapse
enamel in fixed appliances due to
From opposing brackets
Higher risk with ceramic brackets
5 stages in the pt journey of fixed appliance tx
Assessment & diagnosis
* Treatment aims
Treatment plan
Commence treatment
* Average case 18-24months
* Hypodontia case 24-30 months
* Orthognathic case 24-30 months
Routine adjustments
* Every 4-8 weeks
retention
intial problems encountered in fixed appliance tx
4
- Pain
- Mucosal irritation
- Ulceration
- Appliance breakage
role of GDP in fixed appliance pt management
6
- Continue to see patient for routine care and check ups
- Reinforce OHI and Diet advice
- Liaise with orthodontist if concerns
- Make appliance safe in case of an “orthodontic emergency”
- Snipping of jaggy wire
- Removal of loose component
