Indirect Retention

Question 1

What is indirect retention?

Answer 1

Any component of a partial denture which lies above the survey line and is placed on the opposite of the clasp axis of the denture to the saddle area

Question 2

Why is indirect retention important with regards to clasps?

Answer 2

Makes them function as intended by acting through a lever action to become new rotational axis of displacement

Question 3

Why are DES most likely to benefit from indirect retention?

Answer 3

They are most prone to displacement in function

Question 4

Describe how to make indirect retention and clasps effective

Answer 4

Put clasp close to the saddle but indirect retention far from the saddle

Question 5

TRUE OR FALSE

Clasps provide most to indirect retention if they are further from the DES

Answer 5

FALSE

When more than one rotational clasp axis is present, the closest to the saddle contributes most to indirect retention

Question 6

Name 2 ways to provide indirect retention

Answer 6

1. Rests (cingulum or occlusal)

2. Embrasure hooks

Question 7

What is reciprocation?

Answer 7

Resistance to displacement of tooth by laterally directed forced from retentive clasps as they move up and over bulbosity

Question 8

Describe how reciprocation works with a clasp

Answer 8

• Reciprocal arm sits on opposite side of tooth than clasp
• When clasp moves up the tooth it pushes the tooth the opposite way in absence of reciprocal arm
• Reciprocal arm prevents this push so more force has to be exerted to move clasp over maximum bulbosity

Question 9

What is bracing?

Answer 9

Resistance to displacing forces acting in antero-posterior and lateral directions when the denture is fully seated

Question 10

How is bracing achieved?

Answer 10

Rigid components of the denture in contact with teeth or alveolar ridges