Prosthodontics

Question 1

What is meant by the term “saddle” in RPDs?

Answer 1

the teeth being replaced

Question 2

What is a Kennedy Class I?

Answer 2

Bilateral free end saddles

Question 3

What is a Kennedy Class II?

Answer 3

Unilateral free end saddle

Question 4

What is a Kennedy Class III?

Answer 4

Bounded saddle

Question 5

What is a Kennedy Class IV?

Answer 5

Anterior bounded saddle that crosses the midline

Question 6

How do you determine what Kennedy Class an arch falls under if there is multiple saddle areas?

Answer 6

Most posterior saddle determines Kennedy Classification

Question 7

What is meant by the term “support” in RPDs?

Answer 7

the resistance of the denture to occlusally directed load

Question 8

What support classification is used in RPDs?

Answer 8

Craddocks Classifications
- Class 1 = tooth borne
- Class 2 = mucosa borne
- Class 3 = tooth & mucosa borne

Question 9

What is meant by the term “retention” in RPDs?

Answer 9

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

Question 10

What are some methods of retention used in RPD design?

Answer 10

• clasps
• soft tissue undercuts
• adhesion (eg maxillary plates over hard palate)
• path of insertion
• precision attachments/implants

Question 11

What is meant by the term “indirect retention” in RPDs?

Answer 11

Resistance of a denture to rotational displacement

Question 12

What is meant by the term “reciprocation” in RPDs?

Answer 12

Prevention of a clasp arm moving the clasped tooth (eg tilting/tipping)

Question 13

What is meant by the term “major connector” in RPDs?

Answer 13

Part of denture that connects all the components together

Question 14

What is meant by the term “minor connector” in RPDs?

Answer 14

Connects rests, clasps and bracing arms to major connector

Question 15

What connector design is this?

Answer 15

Palatal strap

Question 16

What connector design is this?

Answer 16

plate design

Question 17

What can you use to record the inter-occlusal record during a jaw-reg?

Answer 17

• bite registration paste (usually polyvinyl siloxane)
• wax wafer

Question 18

Why is bite registration paste sometimes a better option for recording inter-occlusal record compared to wax wafer technique?

Answer 18

Wax wafer can sometimes prop occlusion open

Question 19

What area of a treatment plan does construction of RPDs fall under?

Answer 19

Reconstructive phase

Question 20

What are the clinical stages in RPD construction?

Answer 20

• primary impressions
• mount & survey study casts
• design denture
• tooth prep if required
• master impressions
• jaw registration
• tooth trial
• delivery
• review

Question 21

What can be involved in “mouth preparation” prior to creation of RPD?

Answer 21

• pre-prosthetic surgery
• periodontal treatment
• orthodontic treatment
• tooth preparation
• fixed pros
• endodontics
  ETC

Question 22

When preparing pt mouth for a new RPD, what may be involved as a part of pre-prosthetic surgery?

Answer 22

• remove retained roots/unerupted teeth
• remove any pathology
• reduction of bony prominences
• eliminate prominent frenal attachments

Question 23

Why is tooth preparation sometimes required before taking master impressions?

Answer 23

• provide rest seats
• establish guide surfaces
• create undercuts / retentive areas

Question 24

Why might rest seats need to be prepared?

Answer 24

• prevent interference with occlusion
• reduce prominence of the rest
• produce favourable tooth surface for support

Question 25

How deep should rest seats ideally be?

Answer 25

Deep enough to allow a rest of at least 1mm thick

Question 26

What are guide planes?

Answer 26

2 or more parallel axial surfaces on abutment teeth, which limit the path of insertion of a denture

Question 27

What are the pros of guide planes?

Answer 27

- increased stability - reciprocation - prevention of clasp formation - improved appearance

Question 28

How can undercuts/retentive areas be created on abutment teeth?

Answer 28

- addition of composite - tooth surface reduction

Question 29

Give a brand name of PVS:

Answer 29

Extrude

Question 30

In which patients is polyether unsuitable to use for impression taking?

Answer 30

Pt with severe undercuts - polyether sets rigidly

Question 31

Give example of a brand name of polyether material?

Answer 31

Impregum

Question 32

In which patients is impression compound a good option to use for impressions?

Answer 32

Edentulous pts

Question 33

List the procedural steps involved at the master impression stage of RPD production:

Answer 33

- try in special tray & trim peripheries if overextended - modify peripheries with greenstick - modify free end saddles with green stick - apply adhesive & use alginate/polyether/PVS for impression - border mould when impression seated - disinfect & place in sealed back

Question 34

What has likely happened if you receive framework trial from lab, the framework fits the cast BUT does not fit the patient?

Answer 34

impression error

Question 35

What is the technique used to create a cobalt chromium RPD base?

Answer 35

LOST WAX TECHNIQUE - base design created on cast in wax - cast placed in mould & put into furnace - wax melts away and is replaced by molten CoCr - mould allowed to cool & is removed - metal base casting is now sandblasted with aluminium

Question 36

At what temperature does Cobalt Chromium alloy melt at?

Answer 36

1400 degrees celcius

Question 37

WHY must we record the occlusion in the production of RPDs?

Answer 37

Must know the position of the teeth in relation to each other as: - try to keep occlusion same for pt after denture fitted - facilitates denture design (eg heavy contacts noted) - ensure loading forces are directed in the correct direction

Question 38

What can be used to record the OVD?

Answer 38

- Willis bite gauge - Dividers

Question 39

What problems may cause record block to be displaced when trying it in?

Answer 39

- overextension into peripheries - too much lip support

Question 40

When reference points/lines are important to note at jaw reg stage?

Answer 40

- midline - canine line - inter-pupillary line to guide incisal plane - ala-tragus line - smile line - incisal level

Question 41

What materials can artificial teeth for RPDs be composed of?

Answer 41

- acrylic - porcelain

Question 42

How do acrylic / porcelain teeth on an RPD differ from each other?

Answer 42

Acrylic - chemical bond with denture base - silent during function - easily trimmed/customised - low abrasion resistance Porcelain - mechanical attachment with the denture base - natural appearance - noisy in function - brittle - high abrasion resistance

Question 43

What instructions might you provide to the patient at the RPD delivery stage?

Answer 43

- how to insert/remove denture - denture cleaning instructions - wear instructions (eg take out overnight) - OHI of remaining teeth

Question 44

What information/warnings may you give to the patient at RPD delivery stage?

Answer 44

- excess saliva initially - speech difficulties - eating discomfort initially - soreness, continue to wear denture if possible so at rv appt we can see where to reduce acrylic

Question 45

Pt comes back to see you for a RPD review appointment, they complain that they are experiencing pain over the entire denture bearing area, what is likely to be the problem?

Answer 45

None/not enough free way space - pt may also complain of discomfort in MoM and TMJ

Question 46

Pt comes back to see you for a RPD review appointment, they complain that the denture becomes displaced easily when talking & protruding tongue, what is likely the problem?

Answer 46

Overextension into lingual sulcus

Question 47

Why is tooth support better than mucosal support for RPDs?

Answer 47

Tooth support - transmits load via PDL - feels more like natural dentition - more comfortable - protects soft tissues from trauma Mucosa support - may cause reduction of occlusal table - allows denture base to move around

Question 48

Describe the method of an RPD achieving mechanical retention:

Answer 48

Engaging tooth undercuts via - clasps - guide surfaces

Question 49

Describe the method of an RPD achieving physical retention:

Answer 49

Via existing forces of: - adhesion = surface forces of saliva on denture & mucosa - cohesion = forces within saliva, viscosity - atmospheric pressure Determined by closeness of adaptation to tissues

Question 50

Describe the method of an RPD achieving muscular retention:

Answer 50

Dependent on the patients muscular control

Question 51

What is the difference between direct and indirect retention of an RPD?

Answer 51

Direct = resistance to vertical displacement of denture Indirect = resistance to rotational displacement of denture

Question 52

What type of clasp is pictured here?

Answer 52

Gingivally approaching I-bar clasp

Question 53

What is the ideal "pattern of retention" ?

Answer 53

Triangular pattern of retention

Question 54

What makes a bar connector superior to a plate connector?

Answer 54

Less mucosal coverage with bar connection

Question 55

What should the minimum thickness of a lingual bar be?

Answer 55

2mm thick

Question 56

Name the mandibular connectors listed here:

Answer 56

1. Lingual bar 2. Lingual plate 3. Dental bar 4. Sublingual bar 5. Labial bar (uncommon)

Question 57

Where should a lingual bar be positioned in relation to the gingival margin?

Answer 57

At least 3mm below gingival margin

Question 58

How much space is usually require on lingual mandibular surface for use of a lingual bar connector in RPD design?

Answer 58

8mm - sits 3mm from gingival margin - bar 4mm thick - 1mm clearance to FoM

Question 59

When is an RPI system typically used?

Answer 59

Free-end saddle designs to prevent stress on the last abutment tooth

Question 60

What effects are associated with edentulism?

Answer 60

- loss of masticatory function - appearance issues - self esteem issues - general health effects - poorer quality of life - speech problems

Question 61

What clinical effects are observed as a result of edentulism?

Answer 61

- ridge resorption - soft tissues changes to lip & chin - reduction in face height

Question 62

Why might complete dentures not be a good option for parkinsons patients?

Answer 62

complete dentures require good neuro-muscular control

Question 63

What denture history is relevant to obtain when a pt attends your practise requiring new ones?

Answer 63

- age of current dentures - what age did they start wearing dentures - how many denture sets have they had - what they like/dislike about their current dentures - how long have they had their current set of dentures

Question 64

What medical history may cause complete dentures to be contraindicated?

Answer 64

- neuromuscular problems - strokes - dementia - epilepsy - polypharmacy may cause dry mouth

Question 65

A diabetic patient wears complete dentures, what condition are they more at risk of developing?

Answer 65

candida infections