RPD 12

Question 1

what are indications for rotational path PRDPs in the SAGGITAL PLANE?

Answer 1

MX/MN class IVs without mod spaces where visible clasping in NOT an option

MN CLASS III where medially tipped molar abutments and bilateral edentulous segments

Question 2

what are indications for FRONTAL plane?

Answer 2

MX /MN Class IIs (lateral path)

CLASS IIIs (unilateral) with NO mod spaces (lateral path)

Question 3

what are design considerations for rotational path PRDPs?

Answer 3

• not a straight path of placement
• eliminates anesthetic clasps (K IVS)
• Rigid Retainers (struts or plates) engage undercuts (.01)
• LITTLE TOLERANCE FOR ERROR

Question 4

what are the advantages of rotation path PRDS?

Answer 4

• Minimize the # of clasps
• improved esthetics
• improved cleanliness
• MINIMAL tooth preparation (except for medially tipped molars, MX canines in Kennedy IVs)
• Can be sued in the ABSENCE of facial undercuts (Kennedy IVs)
• Distortion of retentive components is unlikely (rigid plates vs. clasps)
• Preservation of arch integrity (avoid embrasure clasps)

Question 5

what are the two exceptions to minimal tooth preparations?

Answer 5

medially tipped molars

MX canines in Kennedy IVs

Question 6

what are the disadvantages?

Answer 6

• adjustment of retentive components is difficult (plates vs. clasps)
• Less tolerance for error
• Requires well prepared rest seats
• Deep facial tissue undercut contraindicated

Question 7

what happens if you have a deep facial undercut?

Answer 7

CONTRAINDICATED

Question 8

when can you use a lateral path of placement?

Answer 8

• Class IIs, IIIs, without modification spaces.
• palatal or lingual plating (struts) engage .01 undercuts on fully dentate side.
• Occlusal rests is connected to the retentive plating or struts

Question 9

Describe the lateral path of placement?

Answer 9

no reciprocal element is required. (passive rotational placement)

• rest (1st engages initially to stabilize)
• retentive plate or sturt (2nd) rotates into the undercut without deformation or pressure on abutment teeth

Question 10

How would you design a MN class III with medially tipped molars?

Answer 10

place retention on the molar (.01); no clasps

specifically designed occlusal rests

-extended occlusal (channel) rests for the MN molar abutments. depth is 1.5-2 mm

Floor of the rest is PERPENDICULAR to the long axis of the tooth.

the length should extend > the FL dimension of the abutment tooth

Question 11

describe the occlusal rests for extended MN molar abutments?

Answer 11

asymmetric outline (encirclement)

bilaterally parallel walls; facial and lingual walls are parallel

intimate contact of rest and minor connector

Question 12

how do you place these?

Answer 12

first engage the rest, then the plate, rotate down to clasp on opposing side

Question 13

Does the retentive plate or sturt rotate into the undercut with deformation?

Answer 13

NO! it doesn’t

Question 14

describe the PA path of placement

Answer 14

rests engage initally to stabalize.

• retentive plate or strut then rotate into undercut without deformation
• no horizontal force on the abutment tooth= no requirement for reciprocation

Question 15

do you need reciprocation for the rotational things?

Answer 15

no, because there is no horizontal force on the abutment teeth