Retention in RPD's

Question 1

What is meant by retention?

Answer 1

erm used to describe the resistance of a denture to LIFTING AWAY from the tissues (vertical dislodging forces)

Question 2

In what 3 ways can mechanical retention be achieved?

Answer 2

• mechanical means
• muscular means
• physical means

Question 3

What ways can a denture be mechanically retained?

Answer 3

by clasps

Question 4

How can a denture be retained by muscular force?

Answer 4

-shape of the denture

Question 5

How can a denture be retained by physical forces?

Answer 5

Coverage of the mucosa

Question 6

How does coverage of the mucosa lead to physical retention?

Answer 6

Forces of adhesion between the saliva and mucosa

Forces of cohesion between the saliva particles and denture base

Creation of a peripheral seal to try and achive suction to keep the denture in place

Question 7

In what kind of dentures is it harder to gain suction in mucosal coverage?

Answer 7

Metal

Question 8

What are the 2 classifications of retention?

Answer 8

Direct

Indirect

Question 9

What is direct retention?

Answer 9

Resistance to vertical displacement of the denture

Question 10

What is indirect retention?

Answer 10

Resistance to rotational displacement of the denture

Question 11

Where should direct retention ideally be?

Answer 11

As close to the saddle area as possible

Close to the base, adjacent to abutment teeth

In an ideal situation it would be interproximally but not realistic

Question 12

What are guide planes?

Answer 12

Two or more parallel axial surfaces of abutment teeth

Found close to the base and parallel to the path of insertion Provide supplementary retention

Question 13

What is a clasp?

Answer 13

A metal arm that, when in position, contacts the tooth preventing removal of the denture base

Question 14

Where are claps placed in order to be effective as a retainer?

Answer 14

Below the bulbous part of the tooth i.e. in an undercut

Question 15

How are the bulbous portions of teeth identified?

Answer 15

By surveying

Question 16

What are the 2 ways that clasps can approach an undercut?

Answer 16

Occlusally approaching

Gingivally approaching

Question 17

Describe occlusally approaching claps.

Answer 17

Get to the undercut via over the bulbosity of the tooth

Question 18

Describe a gingivally approaching clasp.

Answer 18

Tends to come from the sulcus onto the tooth

Question 19

Which kind of clasp is more aesthetically pleasing?

Answer 19

Gingivally approaching because most of it is below the lip line

Question 20

Clasps work most effectively when in conjunction with what?

Answer 20

A rest (supporting component)

Question 21

Describe the reciprocation feature of clasps.

Answer 21

Each clasp will have an opposing element to the retentive clasp arm to prevent pressure from the clasp acting on the tooth

Question 22

What can altering the path of insertion do?

Answer 22

Utilise undercuts and therefore create a point of retention

Question 23

What is the ideal number of retainers you would have on an arch and what format should they take?

Answer 23

3 in the biggest triangle as possible

Question 24

What is the stress relieving clasp system (RPI) used to describe and where/when is it used?

Answer 24

Used to describe the components around the abutment tooth in a free-end saddle to prevent stress on this tooth

Question 25

What components make up the RPI system?

Answer 25

-mesial rest -proximal guide plate -gingivally approaching I-bar clasp

Question 26

I-bar clasps