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.