RPD DESIGN - INDIRECT RETENTION

Question 1

What is the definition of indirect retention

Answer 1

resistance to ROTATIONAL DISPLACEMENT of the denture

Question 2

Why may a saddle pivot

Answer 2

Think about a free end saddle:
when sticky foods displace the saddle in the common path of displacement, the tips of the clasp engage to prevent the denture from being removed but this is the only mechanical resistance to the movement so the saddle pivots around the clasp

Question 3

Why may a saddle pivot in the maxilla

Answer 3

due to gravity

Question 4

Why does adding a indirect retainer help in resisting the rotational displacement

Answer 4

w If you add an indirect retainer then this retainer becomes the fulcrum of movement of the saddle in an occlusal direction causing the clasp to move up the tooth, engage the undercut and thus resist the tendency for the denture to pivot

Question 5

What is the fulcrum in indirect retention

Answer 5

the retainer - a component which obtains support

Question 6

What is the resistance generated by

Answer 6

clasp

Question 7

What is the effort trying to remove the denture

Answer 7

the displacing force

Question 8

To obtain indirect retention where must a clasp be placed

Answer 8

between the saddle and indirect retainer

Question 9

How do you figure out where to put an indirect retainer

Answer 9

Look at the clasp axis - require something perpendicular to the clasp axis as the clasp axis is the axis of rotation

Question 10

If there is more than one clasp axis which do you use

Answer 10

ou look at the clasp axis closer to the saddle in question

Question 11

What can indirect retention be provided by

Answer 11

w Major connectors
	w Minor connectors
	w Rest 
	w Saddle 
	w Denture base 
NOT CLASPS

Question 12

Why saddles is indirect retention particularly important for

Answer 12

for free end saddles or very long bounded saddles