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PRDP, Final > 6. Rests and Rest Seats > Flashcards

6. Rests and Rest Seats Flashcards

1
Q

Rests and Rest Seats
Rest:
 “a rigid extension of a PRDP which contacts a remaining tooth in a prepared rest seat to transmit ____ and horizontal forces”

Rest Seat:
 “the prepared ____ in a tooth or restoration created to receive the occlusal, incisal, cingulum, or lingual rest” (GPT, 1999)

A

vertical

recess

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2
Q

 Primary rest
 Component of ____
retainer unit

 Secondary rest
 Additional rests used for ____ retention or extra support
 Used in ____ extension PRDP

A

direct
indirect
distal

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3
Q

Rests: Primary Purpose
 To provide ____ support for the PRDP
 Directs and distributes occlusal loads apically down the ____ of the abutment teeth (absorbed by PDL fibers)
 vertical stop: prevents ____ and over-displacement of underlying soft tissue
 maintains retentive ____ in proper position

A

vertical
long axis
injury
clasp

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4
Q 
Three Forms Of Rests
 Occlusal Rest 
-- \_\_\_\_ 
-- \_\_\_\_
-- \_\_\_\_
A

conventional
extended
overlay

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5
Q

Three Forms of Rests
 Lingual Rest
– ____
– ____

 ____ Rest

A

cingulum
ball
incisal

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6
Q 
Occlusal Rests
 “\_\_\_\_” triangular outline form with apex toward \_\_\_\_ of the occlusal surface
 It should be as \_\_\_\_ as it is wide
 Premolars: # \_\_\_\_ round bur
 Large molars: Can use #\_\_\_\_ round bur
A 
rounded
center
long
6
8
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7
Q

Occlusal Rest Seat Size Guidelines
 Size varies from ____ the M-D diameter
 ____ the cusp tip to cusp tip distance or ____ the B-L width of tooth

A

1/3 to 1/2
1/2
1/3

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8
Q

Occlusal Rest Seats
 The floor of the rest seat
– apical to the ____
– ____ with no sharp edges or line-angles

 The angle formed by the rest and the vertical minor connector from which it originates should be ____ than 90°

A

marginal floor
concave

less

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9
Q

Occlusal Rest Seat Preparation
• ____-shaped rest seat preparation
• The angle formed by the rest and the minor connector from should
be ____ than 90°
• The deepest part of the rest seat should be in ____ of prep

A

spoon
less
center

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10
Q

1.5 mm Thickness
• At least ____mm thick at thinnest point
• ____mm thick where it crosses the marginal ridge otherwise a potential for fracture of the rest exists as well as the resulting destructive settling of the PRDP into the gingival tissues

A
  1. 5

1. 5

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11
Q

Embrasure Clasp Rest Seat Preparation
Two adjacent occlusal rests for ____ clasps

Note: adequate tooth ____ to allow sufficient thickness for rests, ____ connectors and clasp arms

A

embrasure
reduction
minor

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12
Q

Occlusal Rest Seats
in Metal not Porcelain

Metal ceramic restorations for abutment teeth

Note: ____ preferred in force-bearing areas such as rest seats

A

metal

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13
Q 
Extended Occlusal Rest Seat Preparation
 Indicated in \_\_\_\_ teeth
 Splinting
 Tipped abutments to prevent further tipping
 Increased support and bracing

> ____ the M-D width of tooth
____ mm in depth

A

posterior
1/2
1.5 to 2

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14
Q

Extended Occlusal Rest

Extended rest on mandibular molar promotes ____ force direction

A

axial

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15
Q

CONVENTIONAL PRDP DESIGN
 Path of insertion ____ to occlusal plane
– To create favorable ____
– Easy to prepare guide planes
– ____
– Patients often seat PRDP using occlusal force

 All rests seat ____

A

perpendicular
undercuts
repeatable
simultaneously

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16
Q

Guiding Plane Path of Placement

Rests Seat ____

A

simultaneously

17
Q 
ROTATIONAL PATH PRDP
 When conventional PRDP will not work
 Compensate for lack of ideal tooth \_\_\_\_ or
contours
 \_\_\_\_ tipped molar
A

position

mesially

18
Q 
ADVANTAGES OF ROTATIONAL PATH PRDP
 Minimal use of \_\_\_\_
 Reduced \_\_\_\_ accumulation
 Reduced number of \_\_\_\_ clasp arms 
-- Reduced chance of \_\_\_\_
 Less tooth \_\_\_\_ than if utilizing precision attachments
 Improved esthetics
A 
clasps
plaque
flexible
distortion
reduction
19
Q

DISADVANTAGES OF ROTATIONAL PATH PRDP
 Technique sensitive
 Lab technician must understand the design principles
 Rest design may require ____ treatment prior to final prep
 Difficult to improve deficient ____
 Requires excellent ____ since blockout areas can be fairly large
 Requires manual dexterity

A

restorative
retention
oral hygiene

20
Q

DUAL PATH PRDP DESIGN
Gordon King, 1978

 First path:

  • - Approach of the framework to the teeth
  • - To gain access to ____

 Second path:
– ____ to seated position

 Framework cannot be removed without ____ out of undercuts

 Only ____ portion of framework required for retention

  • - Elimination of some clasp arms
  • - Improves cleansibility
  • - Improves esthetics
A

undercuts
rotated
rotating
small

21
Q

ROTATIONAL PATH DESIGN
 Rigid component of the framework acts as retentive component
– ____ connector
– proximal ____

 Contacts proximal tooth surface intimately below survey line at ____° tilt
 Must gain access by ____ into place
 A specially designed ____ is needed

A

minor
plate

0
rotating
rest

22
Q

Rotational Path of Placement
Extended Rest on Molar Seated ____

A true rotational path PRDP cannot be seated along a ____ path

A

first

straight

23
Q

Overlay Rest and Rest Seat
 Restoration of occlusal surface of abutment teeth by the PRDP framework

 Indications:
 Restoration of the occlusal plane 
 \_\_\_\_-erupted teeth
 Loss of \_\_\_\_
 Resistance to further \_\_\_\_ of tooth

 Rest seat is ____ to prevent further tipping
 Occlusal contacts established with opposing ____

A 
infra
OVD
tipping
beveled
dentition
24
Q

Cingulum Rest
 Indications: maxillary ____ and mandibular ____ teeth
 Only indicated on incisors when ____ are missing
 Preferred to an ____ rest on an anterior tooth
 Rest seat is in form of an inverted ____ shaped notch

A

anterior
incisors
incisal
U or V

25
Q

Cingulum Rest Seat

Inverted “____” shaped rest prepared with a cylindrical bur; all internal line angles are ____

A

V

rounded

26
Q

Cingulum Rest and Rest Seat
 Cingulum rest should be placed in a ____ rest seat that prevents gingival movement of the rest thereby causing labial movement of the tooth

A

positive

27
Q

Cingulum Rest Seat in Partially-veneered Cast Crown
 B-L: ____ “U” or “V”
 M-D: ____ “U” or “V”

A

concave

inverted

28
Q

Ball Rest and Rest Seat
 Indications: ____ teeth
 Ball shaped rest resembles small occlusal rest seat
– Allows ____ movements during function of distal extension PRDP
 Placed on the ____ half of a tooth at junction of ____ 1/3s
 ____ reduction required

• If dentin is exposed, preparation may be modified to accept an ____ or composite resin restoration

A 
anterior
rotational
M or D
middle and gingival
marginal ridge
amalgam
29
Q

Ball Rest Seat
 ____ inclined
 ____ internal form
 Prepared with # ____ round bur

A

apically
rounded
4 or 6

30
Q

Incisal Rests and Rests Seats
 Most frequently indicated on mandibular ____ teeth
 Successful if sound abutment tooth and a cast restoration is not ____
 Near ____ angles of abutment teeth

 Disadvantages:
 ____ forces generated against abutment teeth (least ____ of rests for anterior teeth)
 Unfavorable esthetics

A

anterior
indicated
incisal

tipping

31
Q

Incisal Rest Seat Preparation
 A small ____-shaped notch approximately ____mm from the proximal-incisal angle of the tooth
 Notch is ____ and extends slightly unto facial surface

M-D: ____
B-L: ____

A

v
1.5 to 2.0
concave
convex

32
Q

Rests Are Good
 Do not ____ the occlusion
 Be aware of ____ contacts
 Occlusion may affect choice of direct retainer and rest placement
 Evaluate occlusion before preparing all rests

A

destabilize

centric

PRDP, Final (21 decks)

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