RPDs lecture 4

Question 1

what two Kennedy classes have the least potential for rotation and destructive forces?

Answer 1

Kennedy class III and IVs

Question 2

support points of the lever around which rotation occurs?

Answer 2

fulcrum

Question 3

what does the fulcrum line pass through?

Answer 3

the two most distal rests

Question 4

what is the purpose of the combination clasp?

Answer 4

flexibility of the rough wire arms limit the torquing effect= limit rotation.
you will have a cast reciprocal clasp arm and wrought wire retentive clasp arm

Question 5

advantages of the combo clasp?

Answer 5

flexible, adjustable, better esthetics due to lower position on tooth surface (.02)

Question 6

disadvantages of the combo clasp?

Answer 6

uncessecary distal torque
may be distorted by patient manipulation
may distort with function.

Question 7

what class lever do we want?

Answer 7

second class
R and E are on same side of F

Question 8

why mesial rest on distal extension abutments?

Answer 8

M rests creates least force on the abutment.

increased abutment movement.

Question 9

what is the purpose of the mesial rest?

Answer 9

changes fulcrum. goes from class I lever to Class II

Question 10

what is indirect retention use for?

Answer 10

prevent rotation in the sagittal plane

Kennedy I and II

Question 11

what is the first choice for kennedy class I or II?

Answer 11

infrabulge bar clasp

Question 12

indications for a bar clasp?

Answer 12

tooth supported RPDS
mod spaces
Distal extension cases with appropriate undercut

Question 13

contraindications for bar clasps?

Answer 13

severe bucal/lingual tilt
soft tissue undercuts within 3 mm of gingival margin

shallow buccal vestibule
prominent buccal frenum

Question 14

how deep of a vestibule is needed for bar clasps?

Answer 14

3-4 mm

Question 15

where do you put the guide planes/

Answer 15

place on ALL proximal tooth surfaces adjacent to the edentulous spaces.
2-3 mm in height occlusogingivally and facial- lingual palatally

Question 16

where should the undercut be on a guide plane?

Answer 16

below to permit disengagement of the proximal plate under functional loading of the saddle

Question 17

how thick should the proximal guide plate be?

Answer 17

1-1.5 mm thick

portion near the gingival tissue is relieved and highly polished

Question 18

what is the point of the proximal plates?

Answer 18

provide horizontal stability
reunite and stabilize arch
increase retention (secondary due to parallelism)
PROVIDE RECIPROCATION and ENCIRCLEMENT
distribute the occlusal forces
provide guidance

Question 19

where SHOULDN’T you place I bar?

Answer 19

NOT in distobuccal undercut!!!!!

place in midfacial or slightly MB .01 undercut.

Question 20

describe the modified T bar?

Answer 20

mesio occlusal rest/mc
distal GUIDE PLANE
modified T bar engaging the DISOTFACIAL .01 undercut

Question 21

Why would you use a SUPRABULGE clasp?

Answer 21

if there is bony/soft tissue undercuts APICAL to the FGM in the first 3 mm tf tissue
if you have SHALLOW vestibule
if patient has medical problems