Fundamentals of RPD Design Flashcards
which kennedy classification cannot have a modification space?
four
tooth tissue supported (2)
kennedy class 1
kennedy class 2
tooth supported (2)
kennedy class 3
kennedy class 4 (single edentulous area crossing the midline)
whats next (4)
survey the cast and draw/carve orientation (tripod) lines
draw heights of contour
evaluate possible guide planes
identify undercuts
what is opposing (2)
natural teeth or denture
super erupted teeth
lets take this info and make an RPD (6)
Major Connectors
* Minor Connectors
* Rests
* Retentive Clasps
* Reciprocal clasps/plates
* Indirect retainers
mandibular RPD major connectors (2)
lingual plate
lingual bar
5 reasons to lingual plate
- Opposing a maxillary denture
- Inadequate space for a bar (8mm needed)
- Anticipate loss of additional teeth
- Mandibular tori
- Aid in lateral and rotational stability
maxillary major connectors (4)
palatal strap
AP strap
anterior palatal strap
full palatal coverage
if the major connector is not plating the lingual surfaces of the max teeth the frame needs to be at least
6 mm away from the gingival margin
minor connectors
portion of the RPD framework that connects the major connector to
-the clasp assembly
-indirect retainer
-denture base
in a kennedy class 3 RPD the rests of the RPD are located….
A. Away from the edentulous area on the on the teeth adjacent to the edentulous area
B. Toward the edentulous area on the teeth adjacent to the edentulous area
C. As far away from the edentulous area as possible
D. Rest seats should not be located on the teeth next to the edentulous area.
RPD Rests
* Need approx – mm of inter-occlusal clearance
* – the buccal/lingual width
* Edentulous area bordered by teeth on anterior and posterior
- Rests located — the edentulous space
* Free end distal extension
- Rest located — from the edentulous area
1.5
1/3
toward
away
How many retentive clasps would typically be utilized in a kennedy class 1 RPD design?2
3
4
5
Number of clasps Necessary (4)
1: 2 clasps
2: 3 clasps
3 & 4: 4 calsps
of clasps =
kennedy class + 1 with a max of 4 clasps
how to alter the retentiveness of a clasp? (6)
- Clasp length
- Clasp diameter
- Clasp taper
- ½ round or round
- Material
- Amount of undercut engaged
retentive clasps (2)
infrabuldge
suprabuldge
infrabuldge
(3)
suprabuldge
(2)
I bar clasp
T and 1/2 T clasp
Y clasp
cast circumferential clasp (1/2 round and round)
wrought wire (combination clasp)
Infrabuldge clasps
advantages (2)
contraindications (3)
esthetic
more retentive
- Excessive soft tissue undercut
- Lack of vestibular depth (min 4 mm)
- Inability to place the terminus at the gingival 1/3
infrabuldge clasps
best utilized on a sound abutment tooth adjacent to a free end edentulous area provided the tooth is tall enough and provides relief (undercut( gingival to the distal guide plate
suprabuldge clasps
* Circumferential
* 1/2 round or round cast
* Best utilized
* ½ round -
* round -
Tooth supported RPDs
Tooth/Tissue supported RPDs
Wrought Wire Clasps (Combination)
Best used on Tooth/Tissue Supported RPDs when the abutment tooth is compromised and an ideal guide plane is not present
THE REST SEAT IN THIS SENARIO WILL BE TOWARD THE FREE END DISTAL EXTENSION
what if i dont have any undercut (3)
surveyed crown
place a divot
place a composite
When an RPD is completely seated, what is the function of the reciprocal clasp?
A. To aid in retention by applying force from the lingual
B. To counter-balance the force applied by the retentive clasp when it is in the
designated undercut
C. It serves no purpose when fully seated
reciprocal clasps
* The reciprocal clasp is utilized to …
* The “Action Distance of Stern” is that distance that the in which the …
- Approx –mm
* Located on all teeth that have a retentive clasp
counterbalance the forces applied by the retentive clasp as it passes over the height of contour
retentive clasp is reciprocated.
3-5
which kennedy class will never have an indirect retainer?
Indirect Retainer
* Occlusal, incisal, or cingulum
* Located on …
* Located — to the primary fulcrum line which extend through the most posterior abutments
* Resists the RPD’s tendency to move or rotate in an — direction
tooth-tissue supported RPDS (Class | and Il)
anterior
occlusal
RPD IMPRESSION TECHNIQUES
* — Impressions
* — impressions
* NOTE: PDL of abutment has a vertical displacement of – mm and the gingival tissue on the residual ridge has a vertical displacement of approx – mm.
Static
Functional
0.25
2
RPD impression methods (3)
metal stock ttray w alginate (never plastic)
custom tray, bolder mold, PVS impression
corrected (altered) cast impression
-only on mandibular kennedy class 1 or 2
when to consider
* Mandibular distal extensions (Class | & Il)
* Extensive edentulous spans
* Any case where the periphery is distorted & needs correction (overextended ridge area
* Framework — doesn’t make contact with the ridge intraorally
* Not used in the maxilla due to major connector contact with the palate
tissue stop
impression technique
framework must fit the mout hand be passive
add tray to framework
– mm wax relief
1
check seating on cast and in mouth
after tray is added (2)
rests must be fully seated also the major connector
no resistance to seating
check peripheries
* tray must be – mm short of the vestibular extent
* No displacement when:
-
-
2-3
Pulling on the cheeks and lips
Patient activates the tongue
border molding
same techniques as for a complete denture
corrected cast impression (2)
remove wax spacer
coat tray with adhesive
corrected cast impression
* Use — body impression material
* Carefully load tray
-no material under rests, guide planes, major connector
* Seat with pressure ONLY
over the —, NOT on the —
light
rests
saddle
no pressure over tray
will cause
tissue compression
remove and inspect impression no material under — - remove excess material if present
impression detail is correct
rests or minor connectors
lab steps (4)
- Section cast-remove extensions
- Place retentive grooves or holes in the master cast
- Ensure no contact between impression material /tray& cast
- Sticky wax framework in place against the teeth
box the master cast with the
RPD framework/impression attached and pour the new edentulous ridges in yellow stone
add — to the framework if the metal stops dont contact the cast
duralay tissue stops
potential problems with the corrected cast technique (2)
- A framework not seated either during the impression (material under rest, plate) or when being poured will result in an RPD that won’t fit properly on teeth/tissues
*Stone leaking over teeth during pouring makes articulation impossible
