Week 1 - RPD

Question 1

Reasons for Dentures

Answer 1

1. Improving appearance
2. improve speech
3. restoring masticatory function
4. maintaining oral tissue health
5. improving patient social well being and boosting self confidence
6. promote patient compliance
7. Protect and stabilize remaining teeth
8. in response to the patient’s wish

Question 2

What are the Types of removable partial Dentures

Answer 2

1. Non metal dentures
   - PMMA (polymethyl methacylate) - most popular
   - Polyamide (nylon)
   - Acetal resins
   - Aryl ketone polymers (AKP)
2. Metal base RPD (cast partial denture)
   - OMMA + metal alloys (CO-Cr, Type 4 gold, titanium)

Question 3

what are General Requirements of RPD

Answer 3

• restore appearance
• restore masticatory function
• needs to be comfortable and spread the forces evenly
• retain in position during function
• prevent dental arch from collapsing
• maintaining health of original teeth and soft and hard tissue,
• restore the vertical dimension of the jaw

Question 4

Define abutment

Answer 4

a natural tooth or dental implant that stabilizes a fixed or removable dental prosthesis

Question 5

Define edentulous

Answer 5

the absence of teeth

Question 6

Define support

Answer 6

A foundation on which a dental prosthesis rests or holds up (resistance against vertical force towards tissues) - resistance from up and down movement

Question 7

define Stability

Answer 7

quality of a prosthesis to be firm, stable or constant and to resist displacement by functional horizontal, or rotational stresses

• resistance from side to side movement

Question 8

Define interim or provisional denture

Answer 8

a dental prosthesis used for a short period of time for reasons of aesthetics, mastication, occlusal support, convenience, or conditioning the patient to accept a definite prosthetic

• trial period for the patient trying the dentures

Question 9

Abutment

Answer 9

A tooth or an implant that serves to support and/or retain a prosthesis

Question 10

Define Height of contour (HOC)

Answer 10

the greatest circumference at a selected position position determined by a surveyor

• most bulbous part

Question 11

Define undercut

Answer 11

In an abutment tooth there is a portion of the tooth that lies between the height of the contour and the gingiva. In other structure in any depression that interferes with the path of placement of a denture

• areas under the most bulbous part of the tooth - there shouldn’t be any ridged components in the undercut - undercuts used to gain retention (if flexible)

Question 12

Define angle of cervical convergence (ACC)

Answer 12

angle viewed between a vertical rod contacting a height of contour and the surface of the tooth cervical to the point

Question 13

What is the major connector (lingual plate)

Answer 13

primary structure that connects all parts of the denture and distributes forces across the arch (in upper dentures its usually a palatal plate and in lower dentures its often a lingual bar

connects the parts of prosthesis located in one side of arch to those on the opposite side

Question 14

where should the major connector be located

Answer 14

• away from moveable tissue
• no impingement on gingival tissue or oral mucosa
• clear from bony and soft tissue during placement and removal

Question 15

what is the minor connector

Answer 15

small metal structures that connect individual parts of the denture (e.g. rests, clamps) to the major connector

Question 16

What is the occlusal rest

Answer 16

Small extensions that sit on natural teeth to provide support and prevent the denture from sinking into the gums

Question 17

What is a retentive clasp

Answer 17

component which provides direct retention by engaging an undercut on the abutment tooth, preventing displacement of the RPD

Question 18

What is a reciprocal clasp

Answer 18

component which counteracts the force exerted by the retentive clasp.
Its usually on the buccal or lingual surface (non undercut) on the opposite side of the tooth from the retentive clasp

Question 19

What is a guide plate

Answer 19

flat surface on an RPD framework that ensures a single, definite path of placement
Prevents lateral movement of the denture

Question 20

What is a saddle mesh

Answer 20

Metal lattice structure within the edentulous saddle area which provides retention for the denture base

Question 21

what is a direct retainer

Answer 21

components of an RPD that directly engages the abutment tooth to prevent displacement
- prevents denture from coming off
e.g. clasp on the posterior abutment teeth

Question 22

what is an indirect retainer

Answer 22

a component that helps prevent rotation or lifting of the denture by using leverage
- usually placed opposite to the edentulous space
e.g. lingual rest on anterior teeth to prevent lifting

Question 23

what is a base

Question 24

what compresses in the oral cavity

Answer 24

soft tissue

will compress more than on the tooth side causing the tooth to be pulled backward causing gaps and the denture to not fit properly (getting more loose)

Question 25

What are the 3 rotation of distal extensions of RPD

Answer 25

A = rotation around the fulcrum line passing through the most posterior abutment B = rotation about a longitudinal axis formed by crest of residual ridge C = rotation around a vertical axis located in the centre of the arch

Question 26

What are the 2 types of RPD based on support

Answer 26

1. Tooth support 2. Tooth tissue support

Question 27

What is a class 1 - Bilateral Denture

Answer 27

Class 1 - Bilateral - Missing teeth in the posterior regions on both sides of the arch - Edentulous areas located posterior to all remaining teeth - Denture is supported by remaining anterior teeth and soft tissues

Question 28

What is a class 2 unilateral denture

Answer 28

- Missing teeth in the posterior region on one side of the arch - Edentulous area located posterior to all remaining teeth but only on one side

Question 29

What is a class 3 - unilateral denture

Answer 29

- A single missing tooth or multiple missing teeth in a space with teeth present both anteriorly and posteriorly - Unilateral edentulous area bounded by anterior and posterior natural teeth

Question 30

What is a class 4 - a single but bilateral denture

Answer 30

- edentulous area located anterior to remaining teeth (crossing the midline) - A large anterior space with no teeth in the midline - Must be a single edentulous space; if there are posterior missing teeth it becomes a class 3 as soon as you put a modification on class 4 it becomes a class 3 - no modification for class 4

Question 31

What is the class of a denture determined by

Answer 31

most posterior edentulous area (area with no teeth)

Question 32

What determines the modification number

Answer 32

number of additional edentulous areas

Question 33

can class 4s have a modification

Answer 33

no

Question 34

What is border molding

Answer 34

shaping the borders of the impression to create an accurate impression of the vestibule ensuring a proper seal and stability of the denture framework - recommended for both primary ad final impressions

Question 35

What is a cast partial denture

Answer 35

a metal based denture metal dentures are the most stable

Question 36

What is the most stable and common cast partial denture

Answer 36

cobalt-chromium

Question 37

what part of the retentive clasp should be under the height of contour for ideal retention

Answer 37

only the last 1/3 of the retentive clasp - wouldn't be able to remove it otherwise

Question 38

where would the retentive clasp arm be placed for maximum retention

Answer 38

as close to the gums as possible

Question 39

Rotation of the distal extension of a RPD mainly occurs in both tooth tissue support dentures - true or false

Answer 39

distal extension base (i.e., when the denture extends beyond the last abutment tooth and rests on the edentulous ridge), rotation can occur due to the difference in support from teeth and soft tissues.