All Partial denture Q's

Question 1

what 2 approaches can be used to establish occlusion

Answer 1

conformist

re-organised

Question 2

at what stage does the occlusion need to be established by

Answer 2

between masters and jaw reg

Question 3

what materials can be used to establish occlusion. How effective? (3)

Answer 3

1. wax wafer - easy but innaccurate/deform easily
2. Wax record block & wax
   Easy and quick. Can see if natural teeth meet. Can mis-record due to wax causing jaw to deviate on closing . Can’t separate once recorded
3. Wax record block and bite recording paste. Easy
   Can separate once recorded
   Can see if natural teeth meet
   Some bounce due to material

Question 4

what should happen if there are no index teeth

Answer 4

OVD and FWS should be measured

Question 5

how should an impression be taken for a partially dentate patient with bilateral free end saddles

Answer 5

use impression compound for the free end saddles, then place an appropriate adhesive then take alginate on top (alginate wash imp)

Question 6

instructions for technician if casts CAN’T be hand articulated

Answer 6

Please pour up primary impression in dental stone and construct study model.
Construct special tray with spacer (1-2 sheets of wax depends on master impression material) with handles/ finger rests etc.
Please return models with special tray
Please construct primary record block for a preliminary jaw registration (base can be wax, shellac or light cure acrylic)

Question 7

instructions for technician if casts CAN be hand articulated

Answer 7

Please pour up primary impression in dental stone and construct study model.
Construct special tray with spacer (1-2 sheets of wax depends on master impression material) with handles/ finger rests etc.
Please return models with special tray

Question 8

what should be completed prior to master impression stage

Answer 8

Survey to decide the path of insertion
Survey to decide undercuts etc
Do you need to modify teeth to produce rest seats, guide plains and undercuts (Dr Cross lecture)
Draw the design on the laboratory work card

Question 9

how can a special tray be modified

Answer 9

try in mouth,
if too far extended - trim
if too little extension - add greenstick

Question 10

what instructions are given to a technician following master impressions
- what should be completed prior taking a master impression

Answer 10

Please pour up impression and construct model
cobalt chrome needs improved stone
Please construct wax record block
Specify base
Have they got your design?
Did you remember to prepare occlusal rests/guide planes before taking impression?

Question 11

what are the aims of a jaw registration

Answer 11

buccal/labial contours of wax record block
lip support
Incisal plane
Posterior plane
Occlusal vertical dimension
Intermaxillary relationship to articulate casts
Tooth shade and mould

Question 12

what does it mean if a trial/registration drops/ is easily displaced

Answer 12

overextended

too much lip support

Question 13

name some important reference points to use during a jaw registration

Answer 13

Dento-facial midline
Inter-pupillary line
Ala-tragus line
Curvature of lower lip
Smile line
Gingival margins of existing anterior teeth

Question 14

what instructions are given to a technician following a jaw resistration to tooth trial

Answer 14

Please articulate casts to registration provided
Please set up teeth for wax trial or please construct metal framework or Metal wax Trial
Depends on the complexity of the denture/ occlusion/ tooth position

Question 15

what instructions are given to a technician following a jaw registration to CoCr/tooth trial

Answer 15

please construct a CoCr framework and wax up for tooth trial

Question 16

what instructions are given to a technician following a tooth trial

Answer 16

please proces in acrylic resin

Question 17

what instructions should a patient be given following denture delivery

Answer 17

What instructions will you give? 
Insertion / removal
Coping with new dentures
Pain
Denture cleansing
Speech 
Eating
Refer to clinic patient information leaflet

Question 18

what changes can the patient expect with new dentures

Answer 18

speech affected - practice
eating - strange but practice
pain - pressure

Question 19

when to clean a denture

Answer 19

after eating, before bed and in morning

never worn at night

Question 20

how to wash a denture

Answer 20

over a sink full of water

using a soft toothbrush and non perfumed soap - washing up liquid

Question 21

how should a denture be soaked

Answer 21

using tablet once daily
eg Milton
no more than 10 minutes (bleach denture)
soak overnight in plain water

Question 22

name some aspects of pre-prosthetic surgery

Answer 22

Pre-prosthetic Surgery:
Remove retained roots / unerupted teeth
Remove pathology
Improve contours of edentulous areas –by reducing bony prominences andhyperplastic soft tissue
Eliminate prominent fraenal attachments

Question 23

what aspects of tooth prep can be carried out (4)

Answer 23

Tooth preparation:
Provide rest seats
Establish guide surfaces
Modify unfavourable survey lines
Create retentive areas

Question 24

purpose of a rest seat

Answer 24

Rest seat preparation:
Produce favourable tooth surface forsupport
Prevent interferencewith occlusion
Reduce prominence of the rest

Question 25

how are rest seats made on anterior teeth

Answer 25

Rest seats on anterior teeth Maxillary teeth – a well-developedcingulum allows prep to stay within enamel. Use a cylindrical diamond stone with a rounded tip.

Question 26

what rest seat should be used on a mandibular anterior

Answer 26

Mandibular teeth – Lingual surface too vertical and cingulum too poorly developed to avoid penetrating enamel. Incisal rest seats used.

Question 27

how should rest seats be used on a posterior tooth

Answer 27

Reduce marginal ridge Rests should be saucer-shaped to allow some horizontal movement and dissipation of occlusal forces Rest seat should be deep enough to allow a rest of at least 1mm thick If no space occlusally for a clasp to extend buccally from an occlusal rest, the preparation must be extended as a channel on to the buccal surface

Question 28

what is a guide plane

Answer 28

Guide planes are two or more parallelaxial surfaces on abutment teeth, which limit the path of insertion of a denture. They may occur naturally, but more often need to be prepared. - prepped by allowing tooth surfaces to become parallel with one another

Question 29

what can guide planes provide

Answer 29

Increased stability Reciprocation Prevention of clasp deformation Improved appearance

Question 30

guidelines for guide plane prep

Answer 30

Guide surface should extend vertically 3mm but be kept as far from the gingival margin as possible Not more that 0.5mm enamel should be removed

Question 31

Describe the kennedy classification | what does it describe

Answer 31

Class I – Bilateral free-end Class II – Unilateral free-end Class III – Unilateral bounded Class IV – Anterior bounded (crossing the midline) describes anatomical classification that describes the number and distribution of edentulous areas present. It does not describe the type of support required.

Question 32

define support

Answer 32

term used to describe the RESISTANCE of a denture to OCCLUSALLY DIRECTED LOAD

Question 33

define the craddock classifications

Answer 33

``` I. = Tooth – Teeth provide a HARD tissue resistance to occlusal loading II. = Mucosa – A LARGE coverage provides resistance to occlusal loading III. = Tooth & Mucosa – A combination of HARD tissue and LARGE coverage when there are reduced number of teeth and large edentulous saddles. ```

Question 34

how does tooth support work

Answer 34

Transmits load via the periodontal membrane. Allows the supported denture base to feel like the natural dentition. Is more comfortable for the patient. Protects the soft tissue from trauma. Is likely to stay in close contact with its supporting structures over a period of time.

Question 35

how does mucosal support work

Answer 35

Must cover as large an area as possible. Reduction of the occlusal table Allows the denture base to move slightly. Possible damage to adjacent gingival margins

Question 36

name examples or rests and their adv/dis

Answer 36

- incisal rests - lower anteriors, poor aesthetics, interfere with occlusion, NEVER on wear facets. - cingulum rests - prep required unless prominent cingulum, canines/ incisors, good aesthetic, less rotational forces

Question 37

how does an RPI work | name its components

Answer 37

``` The rest mesially acts as an axis of rotation. As the proximal plate and I bar rotates downwards and mesially around the axis of rotation during occlusal load. The I bar and proximal plate disengage from the tooth/undercuts, thus avoiding potentially traumatic torque. -Rest (occlusal) Mesial of the tooth Rounded on the impression surface Proximal plate (Adjacent to saddle) guide surface of 2-3mm undercut to permit movement I-bar clasp (Gingivally approaching) Greatest prominence of the tooth contour ```

Question 38

cobalt chrome denture adv/dis

Answer 38

- saddles/denture teeth attached to denture base - stronger in thin section, less bulky, high flexural strength - high abrasion resistance - tooth support using occlusal rests as part of framework - minimise gingival margin coverage, favourable design features - radiopaque - limited scope to make adjustments - difficult to repair - high thermal conductivity

Question 39

acrylic denture adv/dis

Answer 39

- saddles/teeth part of base - need adequate thickness of material, not vulnerable to # - vulnerable to abrasion - thermal insulator - not usually radiopaque - simple procedure to add on - easy to replace components

Question 40

purpose of a rest | where should they be placed to maximise function

Answer 40

support denture against apically directed load Rests are often placed on the OCCLUSAL surface of a tooth since this will direct occlusal forces down the long axis (root) of the abutment teeth. The default position to place a rest for a BOUNDED saddle is IMMEDIATELY adjacent to the saddle. Additional rests may be incorporated. The default position may have to be changed depending on the opposing dentition.

Question 41

where should rests be placed on a tooth adjacent to a free end saddle

Answer 41

eg mesial of tooth adjacent to saddle

Question 42

how is mucosal support achieved

Answer 42

Mucosal support is dependent upon as large an area possible of mucosa being covered. However since soft tissue is compressible it is inadvisable to the base with 3mm of the gingival margins are this will place pressure at the tooth and tissue gingival attachment

Question 43

define retention

Answer 43

RESISTANCE of a denture to LIFTING AWAY from the tissues (VERTICAL DISLODGING FORCEs).

Question 44

how can retention be achieved

Answer 44

-mechanical - clasps -muscular forces - control -physical forces adhesion - force of saliva on mucosa/denture cohesion - forces within saliva

Question 45

define direct retention | define indirect retention

Answer 45

- resistance to vertical displacement of denture | - resistance to rotational displacement of denture

Question 46

name 2 types of clasp and examples of each

Answer 46

occlusally approaching clasp - single arm/circumferential/ring clasp gingivally approaching clasp - i bar clasp

Question 47

how is indirect retention achieved

Answer 47

The retention obtained by the extension of a partial denture base to provide the fulcrum of a class II lever. [The retainer(s) providing direct retention lie between the fulcrum and that part of the denture which is subject to the displacing force].

Question 48

why would a plate be used in a denture - width - design preference - negative aspects

Answer 48

plate is thinner in cross section but can still retain rigidity. mucosal supported designs covers gingival margins - OH concern

Question 49

why would a bar be used in a denture | - measurements required

Answer 49

8mm - 3mm from gingival margin, 4mm for bar, 1mm above raised functional depth of FoM. needs to be thick in cross section - 2mm

Question 50

what is a minor connector | guidance

Answer 50

components that stem from the major connector eg rests - be rigid - finish above the survey line - cross gingival margin at right angles - cover as little gingival tissue as poss

Question 51

example of maxillary CoCr shape connectors

Answer 51

palatal plate, mid palatal plate, anterior plate, horseshoe plate/bar, anterior/posterior bar (ring)

Question 52

examples of maxillary acrylic connectors

Answer 52

anterior, mid palatal, full coverage, horseshoe, posterior palatal, spoon, modified spoon, every

Question 53

examples of mandibular CoCr connectors

Answer 53

lingual bar, dental bar, lingual plate, sublingual bar, lingual bar with dental bar (continuous), labial bar

Question 54

how to cope with a flabby ridge

Answer 54

both mucocompressive and mucostatic impression needed take normal impression with medium body PVS, cut impression from flabby ridge area. Place light body PVS here and retake impression. For master imps, cut window out of special tray, take mucostatic imp then use lightbody PVS - minimal pressure and displacement

Question 55

ideal properties of a denture base material

Answer 55

-lightweight (low density) -dimensionably stable -not sensitive to pH of mouth (not sensitive to oral fluids) -abrasion resistance -thermal conduction high YM -high softening temperature non toxic/irritant colour/trnaslucency

Question 56

stages of acrylic polymenrisation

Answer 56

- activation of initiator (free radicals) - heat to 72 degrees, self cure - initiation - benzoyl peroxide - propagation - growth of polymer chain - termination

Question 57

acrylic powder constituents

Answer 57

- benzoyl peroxide - initiator - Pmma particles - pigments - plasticiser - quick dissolving of monomer - co-polymer - improve mech props

Question 58

acrylic liquid constituents

Answer 58

- methacrylate monomer - inhibitor - hydroquinone (prolong shelf life) - co-polymer - improve mech props

Question 59

how to restore a excessive FWS in worn dentures

Answer 59

1. occlusal pivots/restore occlusal surface with autopolymerising acrylic resin 2. replica technique