rp Flashcards
Minimum… mm functional depth between the gingival margin and …. for lingual….
Minimum 8 mm functional depth between the gingival margin and FOM [3-4mm for vertical height of bar, 1-2mm from FOM, 4mm from gingival margin]
if <8mm depth/ inoperable ….. (present)
use lingual….
tori
lingual plate
major connector for maxillary arch
A-P Palatal Bar
A-P Palatal Bar is … mm from gingival margins and … to gingival margins or use A-P …?
6mm
parallel
strap
support definition for RPD
RESISTANCE to vertical forces directed towards the mucosa.
retention for RPD definition
Resistance to vertical dislodging forces away from mucosa.
bracing and stability of RPD -define
Resistance to horizontal, rotational and lateral forces.
EG OF bracing/stability component of RPD
Suprabulge bracing arm clasp, minor connectors, lingual plates/major connectors(cross-arch bracing) and properly contoured flanges in neutral zone for muscular stability
Circumferential clasps vs embrasure clasp
Circumferential clasps(known as Akers clasps) engage the tooth’s undercut area, using both buccal and lingual arms that originate from a common source.
Embrasure clasps, are designed for situations where there’s no edentulous space near the clasp site and engage the tooth from an embrasure (the space between teeth). KCII denture
lower major connectors:
1.lingual bar, 2.lingual plate, 3.sublingual bar, 4.labial bar, and
5.Continuous bar (consist of dental bar +lingual bar=kennedy’s bar] [6.Dental bar]
RPI system minimizes torque on abutment teeth by allowing…. of saddle into …. under occlusal loading without damaging ….. tooth by ….. retentive ….. terminus.
RPI system minimizes torque on abutment teeth by allowing vertical rotation of the saddle into the denture-bearing mucosa
under occlusal loading
without damaging the abutment tooth by disengaging retentive arm terminus.
What are direct retainers, and how do they function?
A: Direct retainers are metal components (clasp assemblies) that engage undercuts on abutment teeth to resist dislodgement.
What are the different types of clasps used in RPDs?
Circumferential (C-clasps)
I-bar
Ring clasp / Hairpin clasp
RPI system (Rest, Proximal plate, I-bar)
: What is a Circumferential clasp (C-clasp)?
A: A suprabulge clasp that encloses >180° of tooth and engages undercut away from the saddle.
What is an I-bar clasp?
: An infrabulge clasp that approaches undercut from the gingival direction—good for esthetics and stress relief.
What is the RPI system in RPDs?
A clasp system with Rest, Proximal Plate, and I-bar—commonly used in free-end saddles to minimize abutment torque.
Typical undercut engagement for cast and wrought clasps?
A:
0.25 mm for cast; 0.5 mm for wrought wire clasps.
What are key design principles of clasp assembly in RPDs?
Passive at rest, active during dislodgement; reciprocation to resist lateral forces; encirclement >180°; support via occlusal rest. Engage u/c (0.25 mm for cast clasps, 0.5 mm for wrought wire)
What is the function of indirect retainers?
A: Prevent rotational displacement of distal extension saddles around the fulcrum line; enhancing stability and preventing tipping.
How is frictional retention achieved in RPDs?
: Through parallel guide planes(proximal cm2) and minor connectors sliding along them during insertion/removal.
When is frictional retention most effective?
With a single path of insertion and precise lab work
What roles do adhesion and cohesion play in RPD retention?
A: Saliva-mediated physical forces (adhesion, surface tension, cohesion) help the denture stick to mucosa, contributing slightly to RPD retention.
How does muscular control contribute to RPD retention?
A: Tongue, lips, and cheek muscles stabilize and retain the denture—dependent on neuromuscular coordination.
Why is denture base adaptation important for RPD retention?
A: Accurate fit to soft tissues contributes to retention; functional impression techniques enhance adaptation, especially in distal extension areas.
