System Of Design

Question 1

What are the alternatives treatments to partial dentures?

Answer 1

No treatment
Conventional bridge
Resin-bonded (Maryland) bridge
Implants retained prostheses

Question 2

What GDC standard is important when informing patient?

Answer 2

Montgomery consent - 2.2

Question 3

Why do clinicians design the denture and not technicians?

Answer 3

We have seen the patient:

Patient story & expectations
Condition of teeth & periodontium/oral health
Assessment of current dentures (if any)
Assessment of occlusion
More complete understanding of alternatives
To give clear cost information (GDC Standard 2.4)

Question 4

What are the key principles of partial denture design

Answer 4

Replace lost teeth & tissues, restoring function, speech, & aesthetics
Minimize damage to adjacent teeth, restorations & tissues
Designed with periodontal health in mind

Question 5

What are the components of a CrCo partial denture?

Answer 5

Major Connector (lingual bar) – connects parts

Cingulum rest (Support & indirect retention)

Acrylic tooth restoring natural tooth

Pink acrylic restoring lost mucosa & bone

Occlusal rest (Support)

(Ring) clasp (Retention)

Question 6

What do the rests aim to do?

Answer 6

Avoid denture sinking into tissue

Question 7

What do clasps engage in?

Answer 7

The undercut of the tooth

Question 8

What is a saddle?

Answer 8

An area of oral mucosa where teeth are being replaced

Question 9

What is craddock class 4? (added later)

Answer 9

Implant borne

Question 10

What is craddock class 5? (added later)

Answer 10

Implant and mucosa borne

Question 11

What is the craddock claddification?

Answer 11

Classifies how the saddle is loaded

Question 12

What is Kennedy classification?

Answer 12

Classifies by position of saddles

Question 13

What is Kennedy class 3?

Answer 13

Single bounded saddle not crossing the midline

Question 14

What is Kennedy class 4?

Answer 14

Single bounded saddle crossing the midline

Question 15

What happens if there is more than 1 edentulous saddle present?

Answer 15

Modifications
Use the most posterior saddle to define the main Kennedy classification

Question 16

What does modification 1 mean?

Answer 16

One other saddle present

Question 17

What class cannot be the main class if there is a modification?

Answer 17

Class 4 as any modification will be posterior to the midline

Question 18

What is PEEK?

Answer 18

Poly ether ether ketone
Alternative to CoCr
Thin and strong
Expensive
Used for allergies to metal

Question 19

What is flexible denture material made off?

Answer 19

Nylon
Very bad (porous)

Question 20

Why is gold not used?

Answer 20

Expensive

Question 21

What does a major connector connect?

Answer 21

Connects all the components

Question 22

What do minor connectors connect?

Answer 22

Rests, clasps and bracing arms

Question 23

What are the common mandibular major connectors?

Answer 23

Acrylic plate
Lingual bar
Lingual plate

Question 24

What are the common maxillary major connectors?

Answer 24

Acrylic plate
Mid palatial bar/ strap
Anterior palatial bar (horseshoe)
Ring

Question 25

Why is a lingual bar good?

Answer 25

Not close to teeth therefore good for PD tissues

Question 26

Why is a lingual plate good?

Answer 26

Prevents rocking good for space <8mm Splints pd anterior teeth

Question 27

Why should the denture be surveyed? (I.e. surveyor or digital surveying)

Answer 27

Help us choose retentive elements (clasps) Path of insertion (and removal) of denture

Question 28

What is retention?

Answer 28

Resistance of the denture to vertical displacement (lifting away from the tissues)

Question 29

What method is used for retention?

Answer 29

Clasps

Question 30

What is indirect retention?

Answer 30

Resistance to rotational displacement around a fulcrum axis *fulcrum axis = the line of rotation – it is an imaginary line between the most posterior rest seats on the end of each arch

Question 31

What classes is indirect retention seen mostly?

Answer 31

Class 1 and 2

Question 32

What components give indirect rentention?

Answer 32

Occlusal and incisal rests Connectors

Question 33

What is used to give support?

Answer 33

Occlusal rests Cingular rests Incisal rests

Question 34

What must sometimes happen for rests to be inserted? And what happens if there is inadequate support?

Answer 34

Sometimes we must prepare rests seats with a drill as we have insufficient occlusal space for a rest Inadequate support: denture sinks into the tissues and traumatizes them

Question 35

What does a high arched palate provide?

Answer 35

Better horizontal resistance

Question 36

What is reciprocation of dentures?

Answer 36

Reciprocal arm of clasp prevents movement of clasped tooth

Question 37

What is given to the technician regarding the denture?

Answer 37

The design sheet which you have provided

Question 38

What should the width of a mid palatial bar be between?

Answer 38

7-12mm

Question 39

What are the steps of designing as denture?

Answer 39

Consider; 1. Saddle(s) 2. Support 3. Retention 4. Indirect retention 5. Bracing 6. Connectors 7. Review & simplify

Question 40

What is support?

Answer 40

“The resistance of the denture to occlusally directed load” Resist movement TOWARDS the soft tissues, (vertical downwards) Craddock classifications

Question 41

What type of saddle has a craddock class 3?

Answer 41

free end saddle

Question 42

What type of saddle has a craddock class 1?

Answer 42

bounded

Question 43

Where should support (rests) be placed in a RPD?

Answer 43

as close as possible to a bounded saddle on the mesial side of the abutment in a free-end saddle

Question 44

What will happen if the rest is placed distally?

Answer 44

the tooth will want to tilt distally

Question 45

When preparing an anterior tooth clasp what can be used instead of cutting tooth?

Answer 45

add composite instead

Question 46

Why are incisal rests less common now?

Answer 46

due to apperance

Question 47

What are the methods of direct retention?

Answer 47

* Clasps * Soft tissue undercuts * Adhesion (maxillary plates) * Friction * Path of insertion muscle control

Question 48

Why should the extension of the saddle have the max surface area possible?

Answer 48

increasing the footprint of the saddle and spreading the load more widely

Question 49

In what pattern should the clasps be placed to increase max retention?

Answer 49

triangular

Question 50

What is the RPI system and why is it used?

Answer 50

Type of Clasp. Allows the free saddle to rotate slightly without damaging the soft tissues or abutment tooth

Question 51

What does bracing/reciprocation aim to do? | what are they both provided by?

Answer 51

bracing - resistance against horizontal displacing forces acting on the denture base **provided by major connectors and flanges** reciprocation - counteracts the tipping forces created by the clasps during denture placement and removal. **provided by reciprocal clasp arm and connectors**

Question 52

What plate materials can be used?

Answer 52

PMMA CoCr

Question 53

What are the saddle choices?

Answer 53

flanged (flange goes directly into sulcus) gum-fitted/ open-face

Question 54

What are the disadvantages to each saddle choice?

Answer 54

flanged if taking out many teeth, the buccal plate may fracture gum-fitted no retention from sulcus difficult to clean any alveolar resorption leaves a space

Question 55

In partial denture construction a pin dam improves...

Answer 55

improves adaptation to underlying tissues

Question 56

What is the minimum length of a CoCr occlusally approaching clasp?

Answer 56

15mm

Question 57

The RPI is a stress relieving clasp system that works by

Answer 57

eliminating axial rotation (torque) from the distal of the abutment tooth

Question 58

What is the distance for a mandibular lingual bar indicated?

Answer 58

at least 8mm from the floor of the mouth to the gingival margin