Direct retainers and clasps for removable partial dentures. Elements of the direct retainer. Theory of the clasp-parts and function

Question 1

Describe the direct retainer

Answer 1

• Component of RPD that prevents dislodgement

- Consists of clasp assembly or precision attachments

Question 2

Intracoronal direct retainer

Answer 2

• Receptacle built into crown for abutment tooth

- Insert attached to RPD

Question 3

Extracoronal direct retainer function

Answer 3

Claps engage in undercuts to prevent dislodgment

Question 4

Type of clasps according to material

Answer 4

• Cast(bar-infrabulge, Circumferential)

- Wrought(circumferential)

Question 5

Type of clasps according to undercut

Answer 5

Supra bulge

Infrabulge

Question 6

Function of direct retainers

Answer 6

• Retention(dislodgement)
• Support
• Stability(horizontal forces)
• Passivity(retentive forces only —When dislodging forces prevent)

Question 7

Retentive arm function

Answer 7

Engages in undercut on abutment for retention

Question 8

Retentive arm made up of

Answer 8

• Retentive clasp arm(not flexible and located above HOC)

- Retentive terminal(Flexible and located below HOC)

Question 9

Reciprocal arm function

Answer 9

• On side of tooth opposite retentive arm
• Counteracts forces of retentive arm
• Above HOC

Question 10

Shoulder of direct retainer function

Answer 10

• Connects body to clasp terminals

- Stabilisation against horizontal displacement

Question 11

Body of direct retainer function

Answer 11

Connects rests and shoulders to minor connector