Components of RPD Flashcards
two types of surfaces of rpd
polished surface
-external surface
tissue surface
-inner surface
type of denture teeth not recommended
porcelain
-very high abrasion resistance
types of material for denture teeth
-porcelain
-acrylic resin
-metal
-composite hybrids
standard material used for denture base
polymethyl methacrylate (PMMA)
common types of METAL framework
cobalt-chromium
nickel-chromium
gold alloy
titanium
most widely used cobalt-chromium
common types of NON-METAL framework
polyoxymethylene (POM)
polyamide/nylons
polyaryletherketone polymers (PAEK
-aryl ketone polymers (AKP)
-polyetherketone (PEEK)
process of metal framework fabrication
diagnostic cast -> fabricate custom tray -> perform final impression making -> master cast -> duplicate cast -> make preps on cast -> refractory cast -> wax pattern -> casting
parts of metal framework
major connector
minor connector
proximal plates
finishing lines
acrylic retention areas
rests
clasps/retainers
3 functional requirements
support (tissueward)
stability (side-to-side)
retention (away from mucosa)
thickness, width, and length to achieve rigid metal
thick, wide, short
modification on surface of metal that adds rigidity
corrugation/stippling
shape, width, thickness, and location of palatal bar
tear drop shape, 4-6mm width anteroposterior, 2-3mm thickness, mid palatal region
type of palatal bar that is combination of anterior and posterior bar, and indication
antero-posterior bar
-to avoid prominences
-less metal coverage
shape, width, thickness, and location of palatal strap
flat with a thick part, 8-12mm (can be wider but not narrower, 1.5mm on thickest portion 1mm on other parts, classified based on location
indication for palatal plate
if 8mm width of strap cannot be reached
stress breaking maxillary major connector
split maxillary major connector
clearance of maxillary connector from gingival margin
4-6mm
done to maxillary major connector to establish intimate contact with mucosa
beading
posterior border of maxillary major connector should not go beyond ___
vibrating line
T/F all major connectors should be polished
F maxillary major connector should not be polished
clearance of mandibular connector from gingival margin
3-4mm
component that provides stress bearing ability for mucosa
keratin
required functional depth for mandibular major connector
> = 7mm
clearance from major connector to gingival margin = 3-4mm
width of major connector = 4mm
T/F just like the maxi major connector, tissue side of mandi major connector should not be highly polished
F, should be to reduce accumulation of plaque
T/F just like the maxi major connector, mandi major connector should be in intimate contact with mucosa
F, need to have relief because no stress bearing area in lingual surface
(not applicable kapag bungi)
shape, width, thickness, and location of lingual bar
tear-drop (thick part sulcular, thin part gingival), 1.5mm, 4mm, 3-4mm away from gingiva
design used for mandibular major connector if functional depth is <7mm
linguoplate
characteristics of linguoplate
scallop-shaped
comes in contact short of cingulum
splinting effect (debatable)
need rests adjacent to plate (avoid slippage)
characteristic of mandi major connector integrated for patients with diastema
interrupted plate
type of mandi major connector when linguoplate is choice, but teeth are too far apart (tilted
continuous bar
(superior border in contact like plate, middle area is open to have benefits of bar)
modification of continuous bar where there is not enough clearance from gingival margin
dental bar
type of lingual bar that goes under the tongue and is oriented horizontally (lying down on sulcus)
sublingual bar
combination of lingual and labial bar and is used when only incisors remain
swing lock
stress breaking mandibular major connector
split mandibular major connector
connects the major connector to the peripheral components
minor connector/truss arms
definition of load in prostho
resistance to penetration of denture teeth to bolus of food during mastication
minimum thickness at junction for minor connector with rest
base metal: 1.5mm
titanium: 1.5mm
gold: 2.0mm
dimension of guide planes
2-3mm wide occlusogingivally
role of acrylic base
support
stability
replacement of lost bone and soft tissue
bind tooth to framework
what is the finishing line
clean transition between metal and base
function of tissue stop
maintains proper orientation of framework on cast during try-ins
types of acrylic retention areas
-meshwork/ridge (interlaced thin strips of metal, should extend 1/3 to 1/2 of edentulous space)
-open lattice (highly resorbed ridges, larger spaces for more acrylic)
-posts/pins (very small edentulous spaces
vertical vs horizontal external finishing lines
vertically oriented - for free end bases, whole distal extension made of acrylic, has flange (extension of base towards buccal and labial/palatal)
horizontally oriented - proximal plate continuous with finishing line, limited coverage
why must external and internal finish line not coincide
for bulk and greater strength
types of rests
occlusal
incisal
lingual
onlay
width of occlusal rest
1/3 of tooth buccolingually, 1/2 intercuspal
wider base to reinforce junction and attach to rest
clearance of occlusal rest to marginal ridge
1.5-2mm
shape of floor of occlusal rest
spoon-shaped
thickness of rest at deepest part
1-1.5mm
use #4 round bur
walls of rest seat are sloping to accommodate minimal movements that dissipate stress called
play
indication for onlay rest
tilted teeth
infraerupted teeth
outline form of incisal rest
saddle-shaped
cingulum rest are mainly placed on these teeth only
maxi canines
parts of clasp
retentive component
reciprocating component
rest
advantage of c-clasp over i-bar
bracing/stability
advantage of i-bar over c-clasp
superior retention
description for how retentive arm engages undercut
dragging action
parts of retentive arm
rigid thirds - thickest and widest, at suprabulge
semi-rigid - crosses survey line
flexible third - engages undercut/below survey line
purpose of reciprocal arm
-while the retentive arm is flexing, the reciprocal arm
should resist the pushing action
-above survey line
-rigid, not tapering
required vertical clearance for gingivally approaching clasp
5mm
why does i-bar have to originate one tooth away
for flexibility
minimum encirclement of clasp
180 degrees + 1 degree minimum
which components are direct retainers
clasps
which components are indirect retainers
rests
denture bases
what causes creation of fulcrum lines
rests
most favorable placement of undercut
junction of middle and gingival third
most favorable placement of reciprocal arm
middle third
6 principles of clasp design (RSSREP)
retention
stability
support
reciprocation
encirclement
passivity
