prosthodontics

Question 1

cawood + Howell classification of ridge form

Answer 1

I = dentate
II= immediately post extraction
III = well rounded, adequate height + width
IV = knife edge, adequate height, inadequate width
V = flat ridge form, inadequate height + width
VI = depressed ridge form, basalar loss

Question 2

define retention

Answer 2

capacity of denture to resist displacement away from tissues - attempt to remove against long axis

Question 3

define stability

Answer 3

capacity of denture to resist movement whilst in contact with tissue - apply later finger pressure to dentures

Question 4

how to achieve RCP

Answer 4

close with tongue up + back

Question 5

for implant supported overdentures what else must you do on assessment with denture assessment

Answer 5

PPDs around implant

Question 6

3 traumatic complications of dentures

Answer 6

1. traumatic ulcer
2. inflammatory hyperplasia (denture granuloma) - leave denture out
3. extreme alveolar atrophy - flabby ridge

Question 7

3 types of denture stomatitis

Answer 7

I = pin point hyperaemia + diffuse inflammation
II = diffuse erythema of most denture baring area
III = granular inflammation or inflammatory papillary hyperplasia

Question 8

disadvantages of precision attachments

Answer 8

cost
maintenance 
weaken denture base
OH requirements 
increased load to abutments

Question 9

2 types of stud attachments in ISOD

Answer 9

ball attachments + locators

magnets

Question 10

why can c/c mislead into class III

Answer 10

maxillary absorbs labially first

mandibular absorbs lingual first

Question 11

what is good wettability

Answer 11

being sufficiently fluid

Question 12

2 non-elastic impression materials used

Answer 12

compound + ZnOE

Question 13

2 elastic impression materials used

Answer 13

alginate + silicones

Question 14

advantages + disadvantages to compound

Answer 14

\+ muco-compressive
\+ readapted
\+ combination with other materials 
\+ compatible with cast materials 
\+ used stock tray
- technique sensitive
- can't record undercuts
- not as accurate 
- internal strains as low thermal conductivity 
- needs waterbacth
- high TEX + shrinkage
- poor dimensional stability

Question 15

advantages + disadvantages of ZnOE

Answer 15

\+ accurate
\+ dimensionally stable 
\+ adapted
\+mucostatic
- not for undercut
- only sets in thin layer
- need special tray
- some patient allergic/burning
- water + heat reduce setting time

Question 16

advantages + disadvantages of alginate

Answer 16

\+ cheap
\+ non irritant
\+ stock or special tray
\+ detailed 
\+ records undercuts
\+ well controlled ST
- not dimensionally stable 
- poor teat resistance + strength 
- less detailed than elastomers

Question 17

how to record flabby ridge

Answer 17

cut whole out of special tray

used impression plaster

Question 18

what is c/c denture base made out of

Answer 18

poly-methyl-methacrylate (PMMA)

Question 19

3 types of porosity problems in acrylic denture

Answer 19

1. contraction porosity - generalised
2. gaseous porosity - localised
3. granular porosity - white + frosty

Question 20

how to avoid processing strains in acrylic denture

Answer 20

slow cooling

Question 21

space left for alginate in major imps for partial denture

Answer 21

3mm

Question 22

class I denture

Answer 22

bilateral free end saddle

Question 23

class II denture

Answer 23

1 free end saddle

Question 24

class III denture

Answer 24

bounded saddle

Question 25

Class IV denture

Answer 25

anterior bounded saddle

Question 26

what process allows detachment of casts from articulator for partial design

Answer 26

split-cast mounting

Question 27

where should rests seats ideally be placed

Answer 27

each side of saddle - stops sinking - indirect retention

Question 28

what is reciprocation

Answer 28

something to resist potential tooth movement caused by a clasp

Question 29

what is bracing used for

Answer 29

resist lateral forces when denture fully seated

Question 30

type of force applied to abutment teeth

Answer 30

torque

Question 31

process leading to rotation of lower free end saddled dentures

Answer 31

anterior tooth support, posterior mucoperiosteal supported

therefore more rapid ridge resorption posteriorly

Question 32

what is altered cast technique

Answer 32

mucocompressive impression of saddle area, taken after framework construction

for lower free end saddles

only works if framework retentive

Question 33

how long does co/cr clasp have to be

Answer 33

15mm - so flexible enough

if not possible make out of gold

Question 34

how much space is needed for lingual bar

Answer 34

8mm

Question 35

what is RPI system

Answer 35

R = medial rest
P = distal guiding Plate
I = infra bulge clasp - clasp comes in from gingival aspect + sits within the maximal conjecture of tooth 

used for distal abutments in lower free end saddles

during loading, I bar and plate disengage + no further damage to abutment

Question 36

techniques for improving lower free end saddle dentures

Answer 36

1. RPI
2. altered cast technique
3. fewer teeth - not past 6s
4. stress breaker design?

Question 37

how much undercut is needed for clasps

Answer 37

0.25mm

Question 38

advantages + disadvantage to skeletal connectors

Answer 38

better sensation

but needs to be thicker

Question 39

best indirect retention

Answer 39

as far away from axis as possible

Question 40

how many rests per teeth

Answer 40

1.5 rests to 1 tooth