Direct Retainer

Question 1

Def, direct retainer

Answer 1

Resistance to tissue away movement ( vertical displacement of RPD) by vertical dislodging force.

Question 2

RPD retained in place by:

Answer 2

1-direct retainer *resist vertical tissue away movement of denture.
2-indirect retainer *resist rotational tissue away movement in free end saddle.

Question 3

intracoronal retainer ex; ….

extracoronal retainer ex …..

Answer 3

internal attachment

clasps, external attachment

Question 4

Parts of clasp assembly

Answer 4

Circumferential clasp
Reciprocating arm
Distal occlusal rest and seat
Proximal plate

Question 5

Def , Attachments

Answer 5

any attachment has (projection and depression ) projection → called patrix, depression → called matrix.

Question 6

Clasps def

Answer 6

Is a Component of RPD used to resist vertical tissue away movement by dislodging force of RPD

Question 7

type of survey line

Answer 7

1-medium survey line → at middle of teeth
2-diagonal survey line → near to occlusal surface at near zone and near to gingival surface at far zone
3-high survey line→ near to occlusal surface (more undercut area)
4-low survey line → near to gingival surface (less undercut area )
*Undercut areas near to saddle → called near zone, away from saddle → called far zone

Question 8

Best survey line ….

Answer 8

medium and diagonal for clasp retention

Question 9

components of clasp

Answer 9

1-rest.
2-reciprocal arm. * Rigid place on or above height of contour
* Functions:
1-reciprocation → counteract /resistance to tipping force generated by retentive arm of the clasp. 2-bracing.
Note: * give reciprocation during insertion and removal of denture, but after that give bracing. 3-retentive arm. * Tapered from its origin toward its tip.
*Consist of
a-body : * rigid above height of contour
b-shoulder:
* rigid (limited flexibility ), above height of contour
c-retentive terminal: * flexible, below height of contour * engage undercut give retention
* passive at rest and be active during dislodging force 4- proximal plate ( minor connector )

Question 10

Requirement /quality of clasp affected by some factors

Answer 10

1-retention 2-support
3-stability 4-reciprocation
5-encirclement 6-passivity

Question 11

retention
* Should be

Answer 11

minimal to resist dislodging force

Question 12

Factors affecting of retention:

Answer 12

1- depth of retentive undercut
2- extent of clasp below survey line
3- flexibility
* Increase flexibility, decrease retention

Question 13

Factors affecting flexibility

Answer 13

1-length → increase length, increase flexibility
2-diameter → increase diameter, decrease flexibility
3-taper → increase tapering ,increase flexibility
4-cross section → round cross section more flexible than half

5-matrial → (chrome-cobalt alloy has higher modulus of elasticity than gold). So more rigid and less flexible.

Question 14

support
Done by rests (occlusal, cinglum, incisal),to

Answer 14

resist tissue ward movement

Question 15

stability
* All component of clasp are rigid except

Answer 15

retentive terminal is flexible

Question 16

encirclement
* Clasp should encircle tooth by more than

Answer 16

180°to avoid tipping force or orthodontic movement to tooth.

Question 17

passivity
* Clasp is completely passive except

Answer 17

during dislodgement

Question 18

Classification of Clasps

Answer 18

1-occlusally approach (circumferential clasp)(suprabulge clap) *Originate from oclussal to engage undercut below height of contour
2-gingivally approach clasp (bar clasps) (infrabulge clasp)
*Originate from gingival origin to engage undercut below height of contour

Question 19

Occlusally approach clasp types

Answer 19

1-aker, simple circlet clasp

2-reverse aker (reverse circlet clasp

3-double aker (embrasure clasp)(butterfly clasp)

4-ring clasp

5-extended arm clasp

6-combination clasp

7-RPA clasp

Question 20

clasp of choice as full fill all requirement (support, stability, reciprocation,
encirclement) than other types of clasps.

Answer 20

aker, simple circlet clasp

Question 21

aker, simple circlet clasp , Use …undercut, away from saddle

Answer 21

0.01

Question 22

aker, simple circlet clasp is rigid clasp. So mostly used in…

Answer 22

-tooth supported RPD ‘‘bounded saddle’

Question 23

aker, simple circlet clasp , not used in free end saddle except usage of

Answer 23

stress breaker

Question 24

reverse aker , used in

Answer 24

distal extension as it is stress breaking

Question 25

reverse aker used if i

Answer 25

Infrabulge clasp is contraindicated

Question 26

double aker (embrasure clasp)(butterfly clasp) Indications

Answer 26

used in intact side (no edentulous area ) as in class II, III, IV where connected by major connector act as cross arch stabilization

Question 27

ring clasp Begin near to saddle extend lingually to distal rest, then buccal to engage mesiobuccal undercut in ….

*May begin buccaly to surround tooth to engage mesiolingual undercut in …

Answer 27

maxillary isolated molar.

mandibular isolated

Question 28

ring clasp , Indication

Answer 28

isolated molar in long span edentulous area.

Question 29

extended arm clasp , Indications

Answer 29

1-splint of weak periodontally abutment.
2-if abutments has no undercuts.

Question 30

extended arm clasp , Advantages

Answer 30

increase length lead to increase flexibility. So it act as stress breaking like action clasp

Question 31

combination clasp
Description:

Answer 31

Consist of cast metal clasp and wrought wire retentive arm
If use gold. So wrought wire incorporated in wax pattern of metal frame work If use high melting co-cr. So wrought wire soldered to cast metal

Question 32

combination clasp , Advantages

Answer 32

it is flexible due to:
1-its material ‘‘fibrill structure’‘
2-cross section ‘‘round cross section’’ So it is stress breaking action

Question 33

combination clasp , indications

Answer 33

1-distal extension
2-weak peridontally affected abutment

Question 34

RPA clasp
Description:

Answer 34

R→ mesial occlusal rest (advantages)
P→ proximal plate more relieved at gingival third
A→ modified aker arm

Question 35

RPA clasp advantages

Answer 35

is stress breaking like action clasp

Question 36

RPA clasp indication

Answer 36

distal extension when contraindicate usage of RPI clasp

Question 37

Jackson clasp
Description:
Indications:

Answer 37

Description: wrought wire clasp originate from lingual cross occlusal surface to use 2 buccal undercut (mesial and distal) ,,Flexible clasp,,

Indications: in premolar and molar removable orthodontic appliance and temporary RPD.

Question 38

Gingivally approach clasp (bar clasps)
Def:

Answer 38

clasps originate from gingivally direction to engage undercut

Question 39

Gingivally approach clasp (bar clasps) , rule of use + contraindications

Answer 39

Rule of use:
1-not impinge on soft tissue, has relief on free gingival margin
2-has gradual tapering
3-its vertical portion should be cross free gingival margin at 90°

Contraindications:
1-insufficient vestibular depth
2-soft tissue undercut
3-gingival recession

Question 40

Gingivally approach clasp (bar clasps) types

Answer 40

1-simple I bar clasp

2-RPI clasp

3- T-shaped gingivally approach clasp

5- Y-shaped clasp

6-ball and socket

Question 41

-RPI clasp

Answer 41

R → mesial occlusal rest
P → proximal plate contact almost proximal surface of abutment
I → I bar engage midbuccal undercut.

Question 42

Compare between gingivally approach clasp and occlusally approach clasp

Answer 42

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