Removeable appliances Flashcards
how can forces be applied on a removeable applaince
spings
bows
screws
name 7 advantages of removable appliances
easy to clean
good anchorage (resistance to unwanted tooth movements)
can move blocks of teeth
cheap
less chairside time than fixed appliances
less inventory
easy to adjust
name 6 disadvantages of removable appliances
dependant on pt cooperation only tipping movement- less than fixed lower RA difficult to wear Retention difficult- especially lower due to tongue and teeth which tend to tip linually speech may be affected technician assiatance
define anchorage
way of resisting movement of a tooth using different techniques
which tooth movements can a RA achieve
tipping space maintenance bite opening crossbite correction single tooth movement
what are the components of a removable appliance?
Baseplate
Activation
Retention
Anchorage- usually basplates
name 3 materials used to make RA
stainless steel
Eligiloy
Acrylic- polymerising polymethyl methacrylate
what material is a baseplate usually made out of
acrylic
what is the function of a baseplate
hold all components together
can add bite planes- for bite opening
what can be added to a baseplate
biteplanes- for bite opening
how does an anterior bite plane work and what does it reduce
no posterior occlusion, allowing posterior teeth to erupt
can reduce overbite
how does a posterior bite plane work and what can it correct
no anterior occlusion, allowing them to erupt
correct anterior open bite and can push a tooth /over the bite’
what 3 things is force dependant on
length of wire
radius of wire
elastic modulus (stiffness) of wire
what happens to the force if the length of wire in increased
light force with longer length
if the length of a wire is doubled, how much is the force reduced by?
8X
if the diameter of a wire is double, by how much does the force increase by
16X
Length of wire is restricted by amount of space in the mouth, how can you overcome this
add coils
name 6 methods of tooth movements (activation)
palatal springs buccal canine retractors z springs T springs Bows Screws
what type of movement is a palatal spring used for
mesio-distal and buccal
what is in place to stop the palatal spring coming away from the baseplate
guard wire
which direction does a buccally placed canine retractor move teeth
palatally and distally
what is a z spring made from
stainless steel
how is a buccal canine retractor activated
winding up coil or adjusting anterior arm
how is the length of a z spring increased
double cantilever
how is a z spring placed
perpendicular to palatal surface otherwise slides incisally and intrudes
which direction does a t spring move teeth and which teeth
buccally
usually canine and premolars
what can active bows be used for
retract proclined incisors
name an appliance that can be used to retract proclined incisors
roberts retractor
in which direction do screws move teeth?
labio-linguallly
what are disadvantages of using screws for activation
expensive
bulky
how does a screw transmit forces
via acrylic contacting the teeth
what can be used for retention
Adams clasps/cribs
Southend Clasps
Labial Bows- anterior retention
what can be used for anterior retention
labial bows
how can anchorage be provided
other teeth
baseplate
what equipment is used to fit an appliance
Adams pliers
Marker
Measuring device
Acrylic trimmer
how long should a pt usually wear a RA
24 hours- only remove for cleaning and contact sport
Which type of activation does a pt have control of?
Screws- adjust themselves with key
how much tooth movement should be expected in first review
1mm in 2-3 weeks of fit
what causes palatal inflamamtion
poor OH, fungal and bacterial infection
what can cause excessive tilting of teeth
spring not at correct point of contact so excessive forces on teeth
