Removable Denture Design

Question 1

What is the Kennedy classification for a denture that has a unilateral free end saddle

Answer 1

Kennedy class 2

Question 2

A denture with a single bounded saddle would be which Kennedy classification

Answer 2

Class 3

Question 3

Define support in relation to dentures

Answer 3

Support is the resistance to occlusally directed loads

Question 4

What are the three craddock classifications

Answer 4

1.tooth borne
2. Mucosa borne
3. Tooth and mucosa borne

Question 5

How much load can a healthy tooth potentially carry

Answer 5

It’s own load plus one and a half of similar teeth

Question 6

How should occlusal load be directed though a tooth

Answer 6

Through the long axis

Question 7

What is the function of rests in relation to support

Answer 7

They resist vertical seating forces

Question 8

The default positions a rest is immediately adjacent to a saddle area, what design would this not apply in

Answer 8

This is only when it is a bounded saddle. In a freee end saddle, the rest should be placed on the mesial of the abutment tooth

Question 9

Define retention in relation to denture

Answer 9

Retention is used to describe the resistance of a denture to lifting away from the tissues
Resistance to vertical dislodging forces

Question 10

How do clasps work on dentures to provide retention?

Answer 10

To be effective as a retainer, the clasp is placed below the bulbous part of the tooth.

The tip of the clasp flexes as the patient is inserting and removing the denture clasp, it deform over the bulbosity of the tooth and comes to rest in the undercut.

When it is in the undercut it is passive and not applying pressure onto the tooth

Question 11

What size of undercut do we need for CoCr clasp?

Answer 11

0.25mm

Question 12

Why do we need a reciprocating arm on denture clasps?11

Answer 12

This is because we need to have an opposing element to the retentive clasp arm to prevent the clasp from acting on the tooth.

While the clasp is deforming during insertion and removal, it is applying a small horizontal load onto the tooth which if not opposed could cause the tooth to move slightly.

Reciprocating arm is resisting that horizontal load.

Question 13

What is the function of minor connectors

Answer 13

Join components such as the rests to the major connector, they transfer functional stresses to and from the abutment teeth

Question 14

How do major connectors provide indirect retention

Answer 14

They resist movement about the axis of rotation

Question 15

What is the RPI

Answer 15

RPI is a stress relieving clasp system.

It looks at protecting the abutment tooth - so when compressing of the mucosa on the free end saddle occurs, no torque is applied to the tooth preventing breakdown of the PDL and loss of that tooth.

Question 16

What components make up an RPI clasp

Answer 16

Mesial rest
Proximal plate
Gingivally approaching I bar clasp

Question 17

Define the common path of displacement

Answer 17

The common path of displacement occurs 90 degrees to the occlusal plane

Question 18

What is the path of insertion

Answer 18

The path of insertion is the direction that the denture is inserted and removed by the patient

Question 19

What type of material is impregum

Answer 19

Polyether

Question 20

What is the recommend casting thickness for a cobalt chrome framework

Answer 20

0.5mm

Question 21

What are the primary stress bearing areas in an upper denture

Answer 21

Hard palate and residual alveolar ridge

Question 22

Name three limiting structures in an upper denture

Answer 22

Labial frenum
Buccal frenum
Hamular notch

Question 23

Name three limiting structures in an upper denture

Answer 23

Labial frenum
Buccal frenum
Hamular notch

Question 24

What are the functions of a posterior palatal seal

Answer 24

Aids in retention
Prevents food accumulation
Compensation for polymerisation shrinkage

Question 25

How does a posterior palatal seal reduce the tendency for a gag reflex

Answer 25

Because it prevents formation of a gap between the denture base and the soft palate during functional movement

Question 26

What are the main stress bearing areas in a lower denture

Answer 26

Buccal shelf
Residual alveolar ridge

Question 27

Name three limiting structures in a lower denture

Answer 27

Lingual frenum
Retromolar pad
Pterygomandibular raphe

Question 28

Name three areas that should be relived on a lower denture

Answer 28

Mylohyoid ridge
Mental foramen
Genial tubercle

Question 29

Why do we need to relive the mental foramen on a lower denture

Answer 29

In case it lies close to the residual alveolar ridge and it could lead to paraestheisa

Question 30

What is the resistance to vertical forces directed towards the mucosa?

Answer 30

Support

Question 31

The resistance to horizontal forces provided by ridgid components of the denture is?

Answer 31

Bracing

Question 32

Function, anatomical constraints, hygiene, ridgitiy and patient acceptance all influence the choice of what?

Answer 32

Connector

Question 33

This resits pivotal movement of a denture through the hinge axis of the clasp tips?

Answer 33

Indirect retention

Question 34

The principle of horizontal resistance to a tooth movement that may occur during clasp engagement

Answer 34

Reciprocation

Question 35

List 4 properties a clasp on a denture should have

Answer 35

Strength
Malleability
Modulus of elasticity
High proportional limit