Removable Partial Dentures 101
Back to the Basics
Luther A. Ison, CDT
University of Minnesota School of Dentistry
Anterior-Posterior Palatal Strap Major connector
Lingual Bar Major Connector, Kennedy Class II
Palatal Strap Major connector
Dr. Nobel’s vulcanite/wrought wire partial
fabricated as second year dental student in 1940.
Lingual bars don’t touch tissue. 1x28 gauge relief wax
R.P.D. = Variation
Survey / Path of Insertion / Design
Retention
Guide Planes
Rests
Major Connector
Minor Connectors
Survey and design. Whose responsibility is it?
Good old communication; ain’t it great!
Retentive undercuts on both sides of the arch are
first requirement of Removale Partial Denture.
Changing the tilt will raise one side and lower the
opposite side.
Three Tripod Marks, circled in red, well
separated, and all in the same horizontal
plane.
Retention
Suprabulge
– Akers
– P.G.P.
– Reverse Akers
– Embrasure
Infrabulge
– I Bar
– Y Clasp
– Modified Y Clasp
Akers clasp assembly. Buccal retentive clasp
arm, lingual reciprocation(bracing) and mesial
occlusal rest.
I-Bar clasp assembly with retentive I-bar properly
positioned slightly to the mesial of center of tooth.
Lingual Plate Major Connector
Compromised RPD design trying to accommodate
retention of tooth #13. Too much stress placed on
#13 and #11 under function.
Teeth adjacent to free-end distal extensions take
more force under function, and require more
flexibility. P.G.P. wire clasp or RPI design may have
been a better choice for #3.
Ideal Crest of Cenvexity is at the Junction
of Cervical & Middle Third. WHY?
.010 Undercut gauge indicating area of retention.
Red mark indicating where the I bar will contact the
tooth ( from 0.0” to .010”). No tissue contact.
I-Bar clasp only conntacts the tooth from the
survey line to .01 undercut.
Retentive clasp arms must be occlusal to survey line
until terminating 4 mm engage the undercut.
Bracing / Reciprocation
Bracing Arm
Bracing Plate
Combination Occlusal Rest & Guide Plane
(R.P.I.)
Bracing arms and plate contact teeth occlusal to
survey line.
Lingual Plated Reciprication/bracing.
Mesial rest on # 28 providesindirect retention
Akers Clasp Assembly
I-Bar with lingual plate reciprocation & distal guide
plane
R.P.I. bracing – Mesial rest + Distal Guide Plane
Guide Planes
Proper blockout for guide planes.
Surveying Guide Plane.
Temporary removable partial denture. Acrylic left in
proximal undercuts will prevent denture from seating
in the mouth.
Distal Guide Plane
Occlusal Rests
-Support
Occlusal Rest may be a little deep
Rigid bracing arm and external acrylic finish line
Minor Connectors
Proper denture tooth esthetics should not be
compromised by poor partial design. This shows
what we’d like the tooth to look like.
Improper minor connector of I-bar compromises
setting of denture tooth. Move connector distally to
embrasure. (Framework technician not
communicating with denture dept.)
Major Connectors
Inadequate room for Lingual Bar. Should have been
lingual plate.
Lingual Bar Major Connector requires 4 mm space
from gingival margin to superior part of bar. Floor
of mouth requires 3 mm space from frenum to
inferior portion of bar.
Lingual Plate Major Connector. P.G.P. Clasps
Lingual Bars do not touch the tissue. 1 thickness
of 28 gauge relief provides the space necessary.
Edges of saddle relief form internal finish lines. Note tissue stop
and that saddle relief starts 1 mm from teeth.
Fit, finished and polished framework with clasps adjusted.
PGP clasps would have been more passive on abutments.
11 mm minimum space requirement for lingual bar =
lingual plate for this case for proper strength and
periodontal health.
Study/Design/ custom tray cast on left shows plenty of
space for lingual bar. Master cast on right shows
lingual was not impressioned to full extension. Altering
partial design in place of reimpressioning is
unacceptable.
Lingual bar positioned too close to teeth. Probably
should have been lingual plate.
