Orthodontic Appliances Flashcards
there are two types of functional appliances, what are they?
removable
fixed
what are removable appliances?
orthodontic appliances (braces) which are not attached to the teeth and can be removed for cleaning and sporting activities
what are the different types of removable appliances?
conventional removable appliances
removable functional appliances
removable retainers
aligner treatment
what are the 4 key components of conventional removable appliances?
B - baseplate
A - active component
R - retentive components
A - anchorage
what do active components include?
springs - e.g. Z springs
screws - e.g. midpalatal screw
bows - e.g. labial bows
the force produced by the component is dependent on what?
length of wire
radius (diameter) of wire
elastic modulus (stiffness) of wire
the force delivered by springs is worked out by what formula?
F = E.d.r4/L3
What does the formula for the force delivered by springs stand for?
F = force
E = stiffness of wire
D = deflection of wire
R = radius of wire
L = length of spring
if you increase the length of wire, what happens to the force?
lighter force exerted
if you double the diameter of the wire, what happens to the force?
x 16 increase in force
if you double the length of the wire, what happens to the force?
x 8 reduction in force
the larger the diameter of the wire, the more/less deflection is required?
less
what does retentive components include?
southend clasps
adams clasps
delta clasps
ball ended clasps
what is the baseplate?
made of acrylic
holds the components together
can incorporate bite planes (posterior and anterior)
provides anchorage for the appliance
what is the purpose of an anterior bite plane?
Prevents posterior teeth from making contact
Good for patients who grind and clench their teeth
Reduces muscle activity
Overcomes deep overbite
Helps with TMD
Permits further eruption of posterior teeth
Permits intrusion of anterior teeth
what is the purpose of a posterior bite plane?
Corrects anterior open bites
Permits further eruption of anterior teeth
Permits intrusion of posterior teeth
what is anchorage?
the resistance to unwanted tooth movements
how would you increase anchorage?
clasping more teeth
moving only one or 2 teeth at a time
using lighter forces