Prosthetics SS Flashcards
how can a denture be supported
by teeth
by mucosa
from tooth and mucosa
describe tooth borne dentures
Resistance to downward direction is placed on the teeth supporting this denture
Teeth are compressible and move in the PDL & mucosa is not compressed on biting
describe mucosa borne dentures
Resistance to downward direction is placed on the mucosa supporting this denture
Mucosa is compressed upon biting & dentures sinks into the gum
describe tooth and mucosa borne dentures
The occlusal rest acts as tooth borne and the free end saddle acts as mucosa borne
how is support gained
cingulum
tooth rests
incisal rests sometimes and onlays
what does every denture need
at least 3mm gingival clearance
what is a spoon denture used as
Used as a temporary measure to replace a small number of teeth
what is a saddle
addle is an edentulous area of the alveolar ridge
what types of saddles can we have
bounded
or free ended
define the path of displacement
vertical force directed away from the mucosa
why might dentures be loose
lack of retention/ bracing/ support
what is the survey line of the tooth
the maximum bulbosity of the tooth
what are the types of clasps
gingival approaching
occlusally approaching
what is bracing
resistance to a horizontal force
what do reciprocating arms have two major functions
resists denture moving horizontally
prevents tooth being pushed into the PDL as the denture is taken in and out and the retentive arm
what is indirect retention
esistance to rotational displacement in a tooth and mucosa borne denture
how do we achieve indirect retention
achieved by placing a rest perpendicular to the terminal hinge axis
describe occlusal rests
Rests act giving the tooth support and keeping the clasps in position
Sit on tip of the tooth and extend up to 1/3 of the occlusal surface
They are saucer shaped to allow resistance (but some movement) when moving laterally
They act on the long axis of the tooth & are clear of the occlusion
what is the horizontal depth required for Co/Cr
0.25mm
how does the clasp engage on the tooth
1/3 under the undercut
2/3 above the survey line
which tooth can we clasp
molars
how long does the clasp need to be
15mm
when do we use the RPI system
free ended lower saddles
what Kennedy class system is needed for RPI
for unilateral/bilateral free ended saddles
what is Kennedy class 1
bilateral free end saddle
what is Kennedy class 2
unilateral free end saddle
bounded saddle
Kennedy class 3
bounded saddle
what is Kennedy class 4
anterior bounded saddle
what are the four principles of co/cr dentures
- Avoid gingival coverage as this promotes plaque accumulation
- Provide a denture with good support
- Make sure the connector is rigid to distribute the loads evenly
- Keep it simple stupid!
what are the eight steps to co/cr dentures
Saddles Support Retention Bracing/ Reciprocation Guide planes Connectors Review points of design Review principles of design
how do we see which teeth to replace
aesthetics
masticatory forces
phonetics
prevention of drifitnt/overexfolatiation
what are disadvantages of saddles
plaque accumulation
trauma
pt tolerance
cost
where does the saddle extend to in the lower free end saddle
to the retromolar pad and the pear shaped pad
what does the saddle extend to in the upper arch
hamular notch
what is the RPI system
medial rest
distal guide plane
I bar
what type of clasps do we have
3 arm ring I bar T bar L bar
how do we create an undercut
using composite and the undercut must be 0.25mm
name some connectors in the upper arch
Anterior palatal bar Mid palatal bar Posterior palatal bar Horse shoe Palatal plate Ring (not suitable for free end saddles as not enough coverage to spread load and create suction
name some connectors in the lower arch
lingual bar sublingual bar lingual plate dental bar buccal bar
how much clearance do we need for a lingual bar
6mm minimum sulcus depth
how much clearance do we need for a sublingual bar
7mm
what are the ways to take an impression
muco displasie
muco satin
differential pressure
functional
what technique do we use nowadays for impressions
relatively muco static
why do we use relative much static
pt comfort
disadvantages of muco static
no border moulding
