Direct Retainers Part 1

Question 1

____ retention:–Mechanical from retaining elements on abutment teeth

Answer 1

Primary Retention

Question 2

____ retention:–Intimate contact of minor connector with guide planes–Intimate contact of denture base & maxillary major connector with underlying tissues

Answer 2

Secondary Retention

Question 3

______: •RPD component used to retain and prevent dislodgement

Answer 3

Direct Retainer

Question 4

•______ direct retainer
–Internal precision attachment: key/keyway
–Most esthetic
–Disadvantages: require crown, complex fabrication, & high maintenance

Answer 4

Intracoronal

Question 5

•________ direct retainer
–Clasp assembly
–More commonly used

Answer 5

Extracoronal

Question 6

–Retentive arm approaches undercut from above the survey line
–Circumferential, Akers, Circlet•Synonyms

Answer 6

Suprabulge

Question 7

_____–Retentive arm approaches undercut from below survey line
–Bar clasps

Answer 7

Infrabulge

Question 8

Which portion of the tooth is the reciprocal arm usually found on?

Answer 8

Lingual

Question 9

Which portion of the tooth is the retentive arm usually found on?

Answer 9

Buccal

Question 10

Which portion of the tooth is the rest usually found on?

Answer 10

Occlusal/Incisal

Question 11

______ lies on occlusal, lingual, incisal surface–Prevent tissueward movement of clasp

Answer 11

Rest:

Question 12

_____ components of direct retainer:
–Rigid component
–Above height of contour
–Reciprocal clasp, Lingual plate, Proximal plate, Guide plate (minor connectors)

Answer 12

Reciprocal components

Question 13

_____ components of direct retainer:
•Proximal 2/3
•Rigid portion, above height of contour

Answer 13

Retentive clasp arm

Question 14

_____ components of direct retainer:
•Distal 1/3
•Flexible•Below height of contour•Provides direct retention

Answer 14

Retentive terminal

Question 15

• Joins body of clasp to framework

* Rigid

Answer 15

Minor Connector

Question 16

• Component of bar clasp
• Connects clasp to framework
• Flexible minor connector
• Exception to rule

Answer 16

Approach arm

Question 17

–Resist vertical movement toward tissue

–Rests

Answer 17

Support

Question 18

–Resist horizontal displacement
–Areas above the survey line
–All rigid components of direct retainer

Answer 18

Stability

Question 19

The class assembly should provide Encirclement of more than ____ degrees
–May be continuous or broken
–Minimum of 3 points used
–Prevents tooth from moving away from the clasp

Answer 19

180

Question 20

–The component that contact tooth at same time or sooner than retentive clasp
–Remain in contact while retentive tip passes over height of contour
–Resist retentive tip lateral forces
–Requires parallel surface to path of insertion

Answer 20

Reciprocation

Question 21

–Components of direct retainer exert no force when fully seated

Answer 21

Passivity

Question 22

–Resists displacement of RPD away from supporting tissues
–Area below survey line: ideally in gingival 1/3
•Clasp arm tip: Terminal 1/3 below survey line

Answer 22

Retention

Question 23

_____ clasps should become active ONLY when disclosing forces are applied to them.
•Their ability to provide retention is based on the resistance of the metal to deformation.

Answer 23

Retentive

Question 24

If there is more length on the retentive clasp, is it more or less flexible?

Answer 24

More flexible

Question 25

If there is more diameter on the retentive clasp, is it more or less flexible?

Answer 25

Less flexible

Question 26

Is a round clasp or half-round clasp more flexible?

Answer 26

Round

Question 27

-material for clasps ‣Produce by drawing metal through dies of smaller diameter ‣Most flexible of all clasps

Answer 27

Wrought wire

Question 28

______ clasp: –Approaches undercut from above the survey line –“Pulls” toward occlusal to resist displacement

Answer 28

Circumferential clasp

Question 29

______ clasp: –Approaches undercut from below survey line–“Pushes” toward occlusal to resist displacement–Easier to seat, more difficult to remove than circumferential clasp

Answer 29

Bar clasp

Question 30

_____ clasp: •Must be rigid •Shaped different than flexible retentive clasp•Not tapered

Answer 30

Reciprocal Clasp

Question 31

______ is the means by which one part of the framework opposes the action of the retainer in function.

Answer 31

Reciprocation

Question 32

•Most logical clasp for tooth-supported RPD (Class III) •Advantages –Excellent stabilization, support, bracing –Easiest to design & construct –Easier to repair •Disadvantages –Covers more tooth surface: more conducive to caries by more plaque retention –Increases tooth circumference •May cause greater occlusal force exerted on tooth –More difficult to adjust

Answer 32

Circumferential clasp

Question 33

Clasp kept as_____ on crown as survey line permits –Less torquing action on tooth –Less interference with occlusion –If survey line is too high, enamel surface must be recontoured to lower the survey line –Survey line too low, Surveyed crown required

Answer 33

Low

Question 34

Should retentive clasp be whole round or half round?

Answer 34

1/2 round

Question 35

* In middle 1/3of tooth | * Above the survey line

Answer 35

–Proximal 2/3

Question 36

* In gingival 1/3•Below survey line | * Tip curves to occlusal

Answer 36

–Terminal retentive 1/3

Question 37

``` ____ clasp –Cast ½ round –Entire clasp in middle 1/3 –Above the survey line •If survey line too high, must recontour •Prepare surface parallel to path of insertion–No taper: Uniform width 1.5 –2.0 mm ```

Answer 37

•Reciprocal clasp

Question 38

* Circumferential clasp of choice Class III RPD | * Engage undercut remote from edentulous area

Answer 38

Circlet

Question 39

•2 circlet clasps joined at body •Used when retainer is necessary in a dentate area –Class III with no modification space –Class II with no modification space –Class IV •Requires heavy reduction of abutment teeth for adequate clasp bulk –Inadequate preparation, clasp fracture common

Answer 39

Embrasure Clasp

Question 40

•Engage undercut adjacent to edentulous area Class III RPD •Covers extensive tooth surface, increased caries risk •Difficult to fabricate •Indication: Mesially-tipped mandibular molar with mesiofacial undercut –½ T preferred for this situation, if no tissue undercut at approach arm •“Last choice” for mesially-tipped molars

Answer 40

Reverse Circlet (Hairpin Clasp)

Question 41

* Indication: Mesiolingually-tipped mandibular molars Class III RPD * Engage mesiolingual undercut * Auxiliary bracing arm for reciprocity * Additional occlusal rest: –support, prevent further mesial movement * Avoid if possible * Incorrect Ring clasp: No reciprocation No support

Answer 41

Ring Clasp

Question 42

•Indication: Retentive undercut adjacent to edentulous space –Class III RPD –Tooth-tissue supported RPD (Class I or II distal extension) –½ T bar clasp preferred, if no tissue undercut at approach arm •Difficult to obtain adequate occlusal clearance •Avoid, if possible

Answer 42

Reverse Circlet Clasp

Question 43

•Wrought round wire retentive clasp •Cast ½ round reciprocal clasp •Indication: Distal extension RPD(Class I & II) –Mesial rest not possible, distal rest must be used –Mesiofacial undercut •Wrought wire soldered to framework

Answer 43

Combination Clasp

Question 44

•Indication: –Class I, II RPDs–Mesiofacial retentive undercut•Circumferential retentive clasp–Cast ½ round (ALWAYS) except in periodontally compromised teeth, cast round.•Reciprocation:–Distal proximal plate–ML minor connector

Answer 44

RPC