RPD Design I Flashcards
minimal tissue/tooth coverage is achieved via
Major connector with open design
avoiding plating teeth
each RPD component must ____
have a function
five big general design principles
- Keep it simple
- Maintain symmetry
- incorporate essential elements into the design
(retention guidance support stabilization) - Incorporate essential elements in each direct retainer
- Widely distribute design elements around the arch
- Avoid placing framework on occlusal contact areas
- consider likelihood of tooth loss
Retention elements
- direct retainer engaging the undercut
- friction from guide planes
- physical retention form denture base
C+1 rule
RPD needs Kennedy Class # + 1 = # of clasps needed
exception to C+1 rule
- Class IVs
- Class II w/out modification= only 2 clasps
Support is from
- primary rests
- auxilary rests (indirect retainers)
- denture base (for distal extensions)
- RPD components above the survey line
- some maxillary major connectors
guidance/stabilization is from
- including opposing surfaces
2. placed on many teeth
support for aker’s arm is from
- ⅓ of retentive arm that’s above the survey line
- rest
- reciprocal arm
for questionable prognosis teeth use mandibular bar or plate?
plate- allows for adding teeth
select ___ retainer in anterior abutment of a tooth supported area
stress releasing
presence of a fulcrum line determines:
- choice and design of direct retainer (ie. stress releasing_
- requirement of an indirect retainer
nature of tissue support determines
- type of denture base
- need for future reline
esthetic consideration determines
anterior clasp design
steps for RPD design
- review diagnostic date
- survey diagnostic cast
- formulate RPD design
- draw design on cast (diagnostic then surveyed cast) and lab Rx
review diagnostic data for
- quality of soft tissue support
- quality of perio support for remaining teeth (C/R ratio)
- examine mounted diagnostic cast for occlusal scheme, centric contact and inter-occlusal space.
survey diagnostic casts orders
- survey duplicate of diagnostic cast
- survey duplicate of definitive cast (after fixed prostheses were delivered)
- survey both teeth and tissue
determining the RPD design sequence
- select ideal major connector
- identify axis of rotation for class 1 and 2
- determine teeth for direct retainer
- determine teeth for indirect retainer (class 1 and 2)
- determine teeth for auxiliary rest
6 determine specific direct retainer types
determining factors for selecting major connectors
- maxillary arch classification
- mandibular floor of the mouth depth
- arch configuration (teeth missing or no)
- anatomical factors (ie. tori)
- perio condition of remaining teeth
- quality of soft tissue
at some point make a flash cards for the summary of major connectors on slides 21 and 22
ss
in max arch, the border of major connector should be at least ___ mm form FGM.. otherwise ___
in max arch, the border of major connector should be at least 6 mm form FGM.. otherwise plate teeth
in mandibular arch, the border of major connector should be at least ___ mm form FGM.. otherwise ___
in mandibular arch, the border of major connector should be at least 3 mm form FGM.. otherwise plate teeth
border of the major connector should run ____ to the gingival margins
parallel
for class 1 put one clasp on each____
terminal abutment
determining teeth for indirect retainers
- teeth located as far from the fulcrum line as possible
- indirect retainer should be perpendicular to the fulcrum line
- usually an auxiliary rest
- most commonly on canines or first premolars
- avoid incisors
- class 1s usually require two indirect retainers
teeth for auxiliary rests
- put on abutments next to edentulous areas that don’t have direct retainers
- put on long segments of major connector that doesn’t have a direct retainer
- on each end of anterior segment of mandibular lingual plate
determination of specific direct retainer types
- location and amount of tooth undercuts
- presence and location of soft tissue interference when selecting infra-bulge clasps
- tooth condition (existing restorations)
- occlusal contact
- esthetic consideration
steps for drawing an RPD design
- draw all rests (primary, indirect, auxiliary)
- draw direct retainer
- locate and draw all acrylic resin retention elements
- draw major connector outline
- draw minor connectors to connect all unattached components
- finish drawing major connector
for class III fulcrum= indirect retainer= use \_\_\_ direct retainers impression method is \_\_\_ denture base is \_\_\_
fulcrum= nonexistent indirect retainer=nonexistent use simple direct retainers impression method is less critical denture base is not critical (short=metal, long=combined)
mandibular lingual bar vs. plate
bar is best… pts. like it
plate is used more bc there are more indications
CC = “”
“Aker” “Simple Clasp”
primary direct retainers for class III
CC or infrabulge
class III special situation (undercut location) clasps
embrasure clasp
ring clasp
hairpin clasp
cast circumfrential clasps disadvantage
non stress breaking
poor esthetic
could create occlusal interference
limited adjustability
infrabulge clasp indications
esthetic conserns class II or II survey line, when akers is not indicate
invrabulge clasp advantage
good esthetics
minimal tooth coverage
Infra bulge clasp design
- I bar
- must keep distal rest and reciprocal arm
- approach tooth starting 4mm away from FGM
- cross FGM at 90deg angle
- reciprocal arm is similar to CC
infrabulge contraindications
- inadequate vestibular depth
- deep soft/hard tissue undercuts
- high frenum attachment
ring clasps indication
medially tipped isolated molars class II survey line
ring clasp disadvantage
extensive tooth coverage
hairpin clasps indications
class II survey line
hair pin clasp disadvantage
extensive tooth coverage
food trap!!!
embrasure clasps indication
tooth supported without a mod space
extremely narrow mod space
embrasure clasp disadvantages
extensive tooth coverage
extensive tooth modification
retainer/rests not widely spread
class 1 survey line use:
posterior =
anterior=
class 1 survey line use: posterior =CC anterior= I bar
class II survey line use:
posterior =
anterior=
class 2 survey line use: posterior =ring or hairpin anterior=mod. T or T clasp
class III survey line use: posterior = tooth modification surveyed crown anterior= I bar
class III survey line use: posterior = tooth modification surveyed crown anterior= I bar
palatal strap
design requirement =
indication=
contraindication=
design requirement = at least 1mm thick and 8mm wide indication=short span class III contraindication= large tori
palatal bar
design requirement =
indication=
contraindication=
design requirement = 2-3mm thick indication= very short span class III contraindication=mesial to 2nd pmolar
AP Strap
design requirement =
indication=
contraindication=
design requirement = less than 1mm thick at least 8mm wide anterior terminate at anterior abutment in rug valley posterior terminates at vibrating line
indication= class 1 with less ideal support few remaining teeth inadequate retainer compromised anterior
Palatal strap
design requirement =
indication=
contraindication=
design requirement = less than 1mm thick partial or full coverage variable anterior termination posterior terminates at vibrating line
indication= class 1 with less than ideal support few remaining teeth inadequate retainer compromised anterior
U shaped
design requirement =
indication=
contraindication=
design requirement = more than 1mm thick terminate at the junction of vertical ridge and horizontal plate indication= inoperable tori gaging patient
contraindication=
avoid if possible
lacks rigity
lingual bar
design requirement =
indication=
contraindication=
design requirement =
5mm tall x 2.5 mm thick
half pear shape
at least 3mm from gingival margin
indication=
8mm depth of floor of the mouth
first choice for major connection
contraindication=
lingual plate indication
lingual plate
design requirement =
indication=
contraindication=
design requirement = covers cingulum up to proximal contact supported by rest on both sid lingual plate only distal posterior abutment indication= insufficient vest depth compromised anterior teeth missing anterior teeth furure anterior tooth loss not ideal support most frequently used monor lingual tori
