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Module 5 > Removable Pros > Flashcards

Removable Pros Flashcards

1
Q

List some examples of major connectors

A

Mid Palatal Bar
Anterior Bar
Posterior Bar
Skeletal or ring design

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2
Q

What are partial dentures most commonly made for?

A

To facilitate appearance, speech and mastication

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3
Q

What are the other reasons that partial dentures may be made?

A

Maxfax defects (due to palatal cancer) or cleft palate
- congenital hole between mouth and nose/air sinus
- needs blocked off to avoid food/drink passage into the nose or lispe

Prevention of:
- tooth wear - spreading load
- unwanted tooth movement - overerupt, drift, tilt
- lateral tongue spread

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4
Q

What is the health gain of partial dentures?

A

Appearance
Masticatory function
Speech
Craniofacial function - jaw joint, facial expression
Societal function
Self-esteem

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5
Q

What is the Kennedy Classification System 1925?

A

A classification system used to classify edentulous saddles for partial dentures

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6
Q

What is a Kennedy Class I?

A

Bilateral free-end saddle

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7
Q

What is Kennedy Class II?

A

Unilateral free-end saddle

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8
Q

What is a Kennedy Class III?

A

Single-bounded saddle, not crossing the midline

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9
Q

What is a Kennedy Class IV?

A

Single bounded saddle, crossing the midline

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10
Q

With modifications, which saddle influences the main classification?

A

The most posterior saddle

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11
Q

Can Kennedy Class IV have modifications?

A

No

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12
Q

What must be dealt with before dentures are made?

A

Caries
Perio disease
Angular chelitis
Denture stomatitis

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13
Q

What is the purpose of 1st imps?

A

To establish the denture bearing area

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14
Q

What are record blocks used for?

A

Used to record the occlusion/bite when posterior teeth are missing

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15
Q

In which cases might an occlusion visit not be necessary?

A

If there are enough index teeth - this can be assessed on the study models.

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16
Q

What instrument can be used in the lab to carry out jaw registration?

A

An articulator

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17
Q

What are the different types of articulator?

A
  • Study models / Simple Hinge
  • Plane line
  • Average value
  • Semi-adjustable
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18
Q

What does surveying study casts do?

A

It establishes:

  • the path of insertion/removal of denture
  • areas of undercuts - may stop the denture from being seated
  • areas that are useful for holding/clasping the denture in place.
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19
Q

Which type of denture requires a casting to be made?

A

CoCr based dentures

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20
Q

What are the checks that you would carry out at the “try in” stage?

A

Extensions
Adaptation
Retention
Occlusion
Appearance

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21
Q

How do you test the fit a chrome framework?

A

Must be precision fit - use a probe between the tooth and the casting to check that there isn’t any big spaces

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22
Q

In order, what are the clinical/lab stages in the construction of partial dentures?

A
  1. Assessment (clinic)
  2. 1st Imps (clinic)
  3. Pour casts + construct record blocks if req (lab)
  4. Occlusion if req (clinic)
  5. Jaw reg + design of partial dentures (lab)
  6. 2nd imps (clinics)
  7. Casting + setting of teeth in wax (lab)
  8. Try in stage + retry if necessary (clinic)
  9. Processing of dentures (lab)
  10. Fit (clinic)
  11. Review/Ease (clinic)
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23
Q

What are the primary and secondary support areas of the upper jaw?

A

Primary - basal bone
Secondary - ruggae and tuberosities

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24
Q

Which area of the upper jaw does NOT contribute to support?

A

Denture border

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25
Q

Which 2 structures in the upper jaw occasionally require denture relief?

A

Midline suture and incisive papilla

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26
Q

What are the primary and secondary support areas of the lower jaw?

A

Primary - buccal shelf and pear shaped pad
Secondary - ridge crest and genial tubercles

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27
Q

Which area of the lower jaw does NOT contribute to support of the denture?

A

Labial ridge incline

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28
Q

Which 2 structures in the lower jaw occasionally require denture relief if prominent?

A

Prominent genial tubercles
Prominent mental tubercles

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29
Q

What might you observe if there is excess FWS?

A

Pt may be over closed

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30
Q

What might you observe if there is inadequate FWS?

A

Pt may not be able to put their lips together, bite propped open

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31
Q

What is denture retention?

A

The resistance to displacement of the denture away from the ridge at rest

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32
Q

What is denture stability?

A

The ability of a denture to resist displacement at functional stresses

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33
Q

What is denture support?

A

The resistance of vertical movement of a denture towards the ridge

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34
Q

What is denture adaptation?

A

The degree of fit between a prosthesis and supporting structures

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35
Q

If the mandibular posterior teeth on a denture are positioned too lingual, what can happen?

A

The tongue can displace the denture

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36
Q

Primary 1st imps are used to construct study models.

What are these study models used for in the construction of partial dentures?

A

Treatment planning
Examination of occlusion
Determination of path of insertion and denture design - surveying
Construction of special trays

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37
Q

Primary 1st imps are used to construct study models.

What are these study models used for in the construction of complete dentures?

A

Treatment planning
Construction of special trays

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38
Q

When recording 1st imps, how much space should there be between the tray flange and teeth/denture bearing area?

A

Ideally should be ~4mm between the tray flange and teeth/denture bearing area

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39
Q

If the stock tray is underextended, what can you use to modify the tray?

A

High-viscosity materials such as:

Greenstick/wax
- to increase length of impression/sulcus depth

Putty in edentulous saddle areas
- to maintain a more successful impression of the denture bearing area
- trim putty to allow ~3mm clearance from remaining teeth

Thermoplastic red composition in edentulous (saddle areas)

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40
Q

What material do you use for taking denture impressions?

A

Commonly alginate

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41
Q

For partial dentures, when do you take 2nd imps?

A

After denture design and any necessary tooth prep

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42
Q

When prescribing to the lab for a special tray, what must you request?

A

3mm spacer to create space for the alginate to flow into

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43
Q

When is a 3mm spacer not required for a special tray?

A

If the pt has a resorbed ridge.

However, the impression must be taken with a bulkier impression material such as zinc oxide eugenol as alginate does not work well in thin section.

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44
Q

What material would you used to form your custom made special tray that would be used to take 2nd imps?

A

Light-cured acrylic resin - blank sheets

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45
Q

With replica complete dentures, what would you use to take your 2nd imps?

A

You would use a replica of the previous denture as the tray

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46
Q

Before taking 2nd imps what must you check?

A

The extensions of the tray - should be ~2mm short of the sulcus depth to allow for border moulding

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47
Q

What do mould stops help with?

A

Help to position the tray, maintain spacing for the impression material and allow consistent positioning of the tray

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48
Q

What can mould stops be made of?

A

Greenstick

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49
Q

How would you disinfect your impressions?

A

Rinse in running water to remove saliva, blood, debris

Disinfect for 2 minutes in 10,000ppm (1%) sodium hypochlorite or sodium dichloroidocyanurate (Actichlor) solution

Note the time that the impression is to be removed from the solution and rinsed

Rinse thoroughly after 2 mins (having put clean gloves on)

Cover alginate impression in damp napkin

Label and place in a plastic laboratory bag

On lab prescription indicate that impressions have been disinfected - signed by supervising clinician

Take to lab ASAP for casting

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50
Q

What concentration of sodium hypochlorite would you use for disinfecting?

A

(1%) - 10,000ppm

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51
Q

How many actichlor tablets would you use in 1 litre for disinfection?

A

10 tablets per litre

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52
Q

Why must you keep the alginate impression in a damp napkin?

A

To prevent SYNERESIS (loss of fluid - drying out of the alginate)

Don’t submerge in water - can cause IMBIBITION (uptake of fluid - swelling of alginate)

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53
Q

What is a critical abutment tooth?

A

If the tooth is lost then it convert the saddle from a ‘bounded saddle’ to a ‘free end saddle’

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54
Q

What are the 3 different flange designs?

A

Full flange
Part flange
Flangeless

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55
Q

What might impact your decision on flange design?

A

Ridge shape
Undercuts into sulcus area

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56
Q

What is a major connector?

A

A plate/bar that:
- Unites partial denture saddles
- Provides bracing - resistance to lateral movements
- Provides indirect retention
- Acts as a splint

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57
Q

List 6 different types of major connectors for the lower jaw?

A

PMMA lingual plate
CoCr lingual plate
Lingual bar
Dental bar
Sub-lingual bar
Swinglock denture

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58
Q

List 8 different types of major connectors that can be used for the upper jaw?

A

PMMA plate
Horseshoe plate
Anterior palatal bar (CoCr)
Mid palatal bar (CoCr)
Posterior palatal bar (CoCr)
Ring design
Spoon denture
T denture

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59
Q

What is an advantage of a dental bar?

A

More hygienic - free’s up lingual mucosa and gingival margins

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60
Q

What crown height is required for a dental bar?

A

9mm crown height
- 5mm for bar
- 2mm above and below to keep clear of the gingival margin and incisal edge

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61
Q

What depth of lingual sulcus is required for a sub-lingual bar?

A

5mm

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62
Q

What are the dimensions of a sublingual bar?

A

2mm height
4mm width

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63
Q

When are sublingual bars used?

A

Kennedy Class IV cases

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64
Q

What depth of lingual sulcus is required for a lingual bar?

A

7mm
- 3.5mm for bar
- 3.5mm for gingival margins for hygiene and comfort

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65
Q

What is the advantage of a split lingual plate?

A

Avoids metal shine through

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66
Q

When is a swinglock denture used?

A

Only when labial undercuts are present

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67
Q

What are the properties of CoCr in comparison to acrylic?

A

Thinner, stronger, and heavier than acrylic

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68
Q

What must the width be of a mid-palatal bar?

A

~7-12mm

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69
Q

What are minor connectors?

A

A connecting component between the major connector or the base of a partial denture and other units such as clasps and rests.

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70
Q

What is the purpose of a striking plate?

A

Minimises the risk of a denture fracturing

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71
Q

What is denture retention dependent on?

A

Film of saliva between the denture and tissues (quality and amount)

Adaptation of the denture

Good border seal - created by physical forces from saliva between denture base and mucous membrane, and the muscle activity of the lips, cheeks and tongue

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72
Q

How can you improve denture retention?

A

Add direct retainers (clasps engaging undercuts of teeth)

Precision attachments - lock and key

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73
Q

Should clasps be passive or active?

A

Must be passive in order to flex to enter and be removed from an undercut.

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74
Q

Where is the point of action of a clasp?

A

Point of action is the tip of the clasp

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75
Q

Where must the terminal 1/3 of the clasp engage?

A

Below the survey line

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76
Q

What should denture clasps always be opposed by to prevent tooth movement?

A

A reciprocal component - ie. an extension of the base plate or an opposing clasp arm

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77
Q

What are the 2 different styles of clasp?

A

Occlusally approaching clasp
Gingivally approaching clasp

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78
Q

How does an occlusally approaching clasp compare to a gingivally approaching clasp?

A

An occlusally approaching clasp is:
- More rigid
- More efficient bracing component preventing lateral movements
- May be less aesthetic

Whereas, a gingivally approaching clasp is:
- More retentive
- More efficient due to push type ‘trip action’
- Less visible, more aesthetic
- More hygienic as covers less tooth structure

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79
Q

Why is adequate space required for an occlusally approaching clasp?

A

So that there is no occlusal interference

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80
Q

What are the different styles of ring clasps?

A

Ring clasps - used for critical abutment teeth
3 arm clasps

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81
Q

What are the 3 different styles of gingivally approaching clasp?

A

T roach clasp - canines and premolars (used more anteriorly)

I bars

L bars

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82
Q

List the different materials that can be used for clasps

A

Cast CoCr
Wrought Stainless Steel
Gold
Thermoplastic copolymer (e.g. Dental D)

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83
Q

What undercut depth do Cast CoCr clasps engage?

A

0.25mm

84
Q

What undercut depth do wrought SS clasps engage?

A

0.5mm

85
Q

What undercut depth do gold clasps engage?

A

0.75mm

86
Q

What is the RPI system?

A

A system used for free-end saddles to reduce stress on the abutment tooth and more evenly spread the load

It involves a:
- Mesial rest
- Distal guiding plane
- I-shaped retentive clasp (ie. I bar)

87
Q

When would you opt for using a replica technique?

A

When there is a history of successful denture wear with no major pathological changes and no major design changes required

88
Q

How would you take replica 1st imps?

A

Using self-supporting putty in a disposable impression tray

89
Q

In what cases may you need to modify the denture prior to 1st replica imps?

A

If under extended - adjust with greenstick

If chrome palate - must thicken up the chrome part of the palate with wax before replicating it

90
Q

What must you do if you are replicating a denture that is overextended?

A

Replicate as normal and prescribe on lab card for shellac to be shorter than normal in that specific area

This can be easily adjusted chairside prior to taking 2nd imps

91
Q

How might you fix minor faults, air blows, or wrinkles in the replica impression?

A

By use of light bodied material (perfecting paste)

92
Q

In complete denture making, why do we record 2nd imps before occlusion?

A

To ensure occlusal blocks are as stable and firm as possible before recording occlusion

93
Q

In partial denture making, why do we record occlusion before taking 2nd imps?

A

To enable us to design the denture considering interocclusal space and to plan for any tooth modification needed to be undertaken prior to taking 2nd imps

94
Q

What impression material can you use to record replica 2nd imps for a complete denture if the ridge is atrophic?

A

Wash impression using a light bodied silicone material - Rapid liner or Aquasil

95
Q

If the ridge is atrophic, what impression technique can you use and why?

A

The closed mouth technique

To avoid occlusal errors such as open bite

96
Q

What is mucosal support gained from?

A

Saddles and connectors

97
Q

What are the disadvantages of mucosal support?

A

Degree of compressibility to mucosa so when loaded the pt may feel denture movement

98
Q

What is tooth support gained through?

A

Use of PDL
Force transmitted through tooth to PDL and ultimately underlying bone

99
Q

What additional components can provide tooth support?

A

Occlusal/cingulum rests

Onlays

Overdenture abutments

Connectors

100
Q

What must you do to an overdenture abutment prior to providing an overdenture?

A

Dome/restore it to provide a smooth rounded surface - must sit 1mm above gingival margin

101
Q

What is the purpose of indirect retention?

A

Prevents displacement of saddle away from ridge by extension of the denture

102
Q

How can indirect retention be achieved with a removable prosthesis?

A

By placing:

The clasp axis as close as possible to the saddle

The indirect retainers as far as possible from the saddle

103
Q

List some different indirect retainers

A

Cummer arms - provides bracing
Lingual plate connector - bracing
Continuous clasp with lingual bar
Occlusal rests
Anterior palatal arm and bar
Posterior palatal bar
Extension of palatal coverage
Dental bar
Embrasure hooks

104
Q

List the 4 denture components and their functions:

A

Saddle:
- Retention
- Support
- Bracing

Connector:
- Support
- Indirect Retention
- Bracing

Clasp:
- Retention
- Support
- Bracing

Rests:
- Support
- Indirect Retention

105
Q

What materials can be used to make denture teeth?

A

Acrylic-based (majority use)
Porcelain based
Composite resin based
Combinations

106
Q

What are the 3 different types of acrylic based teeth?

A

Types:
Senator
Vivodent
Orthotype

107
Q

What are the features of vivodent acrylic based teeth?

A

More expensive
Harder
Longer lasting
Light reflects better
Don’t bond well to acrylic base

108
Q

What shade guide is most commonly used in DDH?

A

The Vita standard shade guide

109
Q

What 2 classifications can be used to help choose mould of the teeth?

A

Leon Williams Classification
- square
- tapered
- oval

Frush and Fisher Classification
- men: square/angular teeth
- women: curved and rounded teeth

110
Q

How can denture teeth be arranged? (4)

A

NN - necks normal
SS - slightly spaced
CC - crossed centrals
TT - twisted tips

111
Q

What biometric guides can you use to assist with tooth positioning?

A

Use incisive papilla - remains static with bone resorption when teeth are lost

On average tips of incisors are 5.5mm anterior to incisive papilla

Horizontal = ~5.5mm
Vertical height = ~7mm

112
Q

What tool can be used to check tooth position?

A

Alma Gauge

113
Q

Which factors will determine the amount of incisal overjet/overbite?

A

Skeletal class
Smile line

114
Q

Which tool is used to measure the occlusal plane?

A

Foxs Guide Plane

115
Q

When might you opt for cuspless teeth?

A

When its difficult to get a reproducible jaw relationship

116
Q

Where should you position the lower denture teeth?

A

On the crest of the ridge to ensure stability

117
Q

Where should you position the upper denture teeth?

A

Slightly buccally to the ridge without compromising the border seal

118
Q

What would you aim for your occlusal plane to be?

A

Parallel to the ala-tragus line

119
Q

How might you achieve balanced occlusion and balanced articulation?

A

By setting up the teeth on an articulator, using compensating curves:
- Curve of Spee
- Bilateral Curve of Wilson

120
Q

What is the ICP?

A

Intercuspal position:

The maximum contact point of contact between opposing teeth.

Dictated by tooth relationships - vary throughout life

121
Q

What is the RCP?

A

Retruded contact position:

Guided occlusal relationship when the condyles are at their most retruded position in the joint cavities

Dictated by the condyles - reproducible position

122
Q

In what partial denture cases must you record occlusion?

A

No posterior teeth
Worn-down index teeth
Premature contact on closure - false index
Limited space for prosthesis placement

123
Q

What do free-end saddle partial dentures require?

A

Indirect retention - to prevent the denture from lifting/moving in function and subsequent trauma to soft tissues

124
Q

What can reduced mandibular support result in?

A

Trauma to the denture bearing area
Instability of denture
Bone resorption of the ridge

125
Q

How can optimum mucosal support be achieved in a free-end saddle situation?

A

Reduce load of denture bearing area by reducing the number of denture teeth - remove 7s or premolar

Cover the maximum area with the denture saddles to spread the load

Extend onto areas that are best able to take the load - e.g. primary stress bearing areas like the buccal shelf of the mandibular ridge

Use natural teeth for support where possible
- occlusal rest
- cingulum rest

126
Q

What problems can occur with tooth/mucosal-supported dentures?

And how might these problems be resolved?

A

Instability on occlusal loading and torque on abutment teeth - can jeopardise the health of the tooth

Can use special impression techniques for free end saddles to reduce the likelihood of these problems occurring
- Altered cast technique
- Stress breaker technique

127
Q

What is the altered cast technique?

A

A functional impression that involves recording the saddle areas under load

Using this technique will:
- Increase stability
- Reduce stress on abutment tooth/teeth
- More predictable occlusion

128
Q

What is the stress breaker technique?

A

Where part of the denture is cut away to allow the saddles to seat further down to tissues without adding additional strain

This technique is not used frequently

129
Q

When deciding on the path of insertion for free-end saddles, which direction will you likely have to tilt the cast?

A

Forward

130
Q

Which is normally the clasp of choice in a free-end saddle situation?

A

A gingivally approaching clasp on a premolar tooth - less trip action and less likely to cause wrenching action on abutment tooth

131
Q

When checking the occlusal plane what are your 2 reference lines?

A

Ala-tragus line
Intra-pupillary line

132
Q

What is the purpose of the post dam?

A

To aid retention - by creating atmospheric pressure under the denture

133
Q

What depth should you prescribe the post dam to be?

A

0.5mm

134
Q

What are the 3 different types of post dam?

A

Heat cured
Cold cured
High impact

135
Q

Where should your post dam sit?

A

At the junction of the hard and soft palate

136
Q

Where are the most common sites of plaque/calculus build up and why?

A

Buccal aspect of U6s
Lingual aspect of lower anteriors

As this is where the major salivary glands exit

137
Q

How does plaque/calculus form on the denture?

A

Pellicle layer is formed by salivary proteins and bacterial products

Oral debris (mucin, food, desquamated epithelial cells) and microorganisms (bacteria and fungi) can adhere to the pellicle layer

Then the plaque flora matures - if left can turn to calculus.

138
Q

What is the bacterial flora present in denture plaque build up?

A

S.aureus, e.coli, alpha strep, spirochetes and more

Fusobacterial sulphur products - leads to halitosis

139
Q

Why do dentures favour candida (fungal) activity?

A

Acidic environment under the denture

Fit surface of denture not exposed to cleansing effect of saliva

Acrylic is porous and rough - collates debris/fungi more easily

140
Q

What are ideal properties of denture cleaners?

A

Cheap
Easy to use
Effective removal of deposits
Bactericidal and Fungicidal
Harmless to denture materials
Non-toxic

141
Q

What is the best way to clean dentures?

A

Mechanical clean:
- plain soap and soft brush
- do not use toothpaste - too abrasive

Chemical clean:
- Alkaline peroxides (Steradent)
- Alkaline Hypochlorites (Milton or Dentural)
- Use cold water with chemical cleaners

142
Q

What might record blocks be reinforced with?

A

Shellac or cured/heat-cured acrylic base plates

143
Q

Where can support be achieved through?

A

Teeth
Mucoperiosteum

144
Q

What is the disadvantage to mucosal support?

A

There is a degree of compressibility to mucosa

When loaded the pt. may feel movement of the denture

145
Q

Where is tooth support gained through/from?

A

Gained through the PDL.

Gained from:
- occlusal/cingulum rests
- onlays
- overdenture abutments
- connectors

146
Q

How can you gain indirect retention?

A

Continuous clasp with lingual bar
Occlusal rests
Cummer arms
Anterior palatal arm + bar
Posterior palatal bar
Extension of palatal coverage
Dental bar
Lingual plate connector
Embrasure hooks

147
Q

What is a clasp axis?

A

An axis formed through 2 clasps on opposing sides of the arch - it is formed through the active part of the clasp (terminal 1/3 of clasp)

Where there is more than one clasp on one side of the arch:
- the major clasp axis (where the main pivot point is) = the closest to the free-end saddle
- the remaining clasp axis is known as the minor clasp axis

The part of the denture distal to the major clasp axis will resist rotation by the use of an indirect retainer

148
Q

What FWS should you aim for?

A

2-4mm

149
Q

How do you calculate the FWS?

A

RVD - OVD = FWS

150
Q

How far should the lower denture extend into the retromolar pad area?

A

1/3 into the retromolar pad area

151
Q

When selecting a stock tray for impressions, how much space should you ideally have between the denture bearing area and the tray to allow space for the impression material?

A

2mm

152
Q

What does pre-packing the palate avoid?

A

Air blows

153
Q

Tissue stops can sometimes be used with special (spaced) trays.

What is the purpose of tissue stops?

A

Ensure thickness of impression material
Help localise the tray during imp taking

154
Q

What is the purpose of finger rests on special trays?

A

To ensure the tray is fully seated posteriorly
To ensure more even distribution of pressure to the tissues
To help stabilise the tray in the mouth

155
Q

Which areas of the mucosa will experience more movement under loading and pressure?

A

Thick areas of mucosa will experience more movement under loading and pressure than thinner areas of mucosa

156
Q

What impression techniques can be used to facilitate discrepancies in mucosal thickness causing denture movement/rocking?

A

Mucocompressive and Mucostatic impression techniques

Both techniques can be used in conjunction with one another to facilitate different areas

157
Q

Which impression technique would you use to facilitate a better denture fit in function?

A

Mucocompressive impression technique

158
Q

Which impression technique would you use to facilitate a better denture fit at rest

A

Mucostatic impression technique

159
Q

How might you avoid compression of fibrous tissue during impression recording?

A

2 stage technique:
- mucostatic impression for the anterior part
- mucocompressive impression for the posterior part

or

Single stage technique with a perforated tray and low viscosity material
- can use if fibrous ridge isn’t too severe
- exert as little pressure as possible

160
Q

List 4 displacive forces on the denture

A

Gravity
Muscle activity
Sticky foods
Function

161
Q

List 2 interfacial forces on the denture

A
  1. Interfacial surface tension
  2. Interfacial viscous tension
162
Q

What is interfacial surface tension?

A

The tension generated when a thin layer of fluid is present between 2 parallel planes of rigid material

Happens as a result of an air seal being formed at the edge of a rigid material.

Relies on wetting of the denture

163
Q

What is interfacial viscous tension?

A

The force holding 2 parallel planes together that is due to the viscosity of the interposed liquid (e.g. saliva)

Relies on good quality plentiful saliva

164
Q

What is adhesion?

A

The physical attraction of unlike molecules for each other

Saliva - mucous membrane
Saliva - denture base

The larger area covered, the greater the adhesion.

165
Q

What is cohesion?

A

The physical attraction between similar molecules - eg. salivary film

166
Q

What is the neutral zone?

A

An existing zone where the outward forces of the tongue are balanced by the inward forces of the cheeks

167
Q

Why is the neutral zone important?

A

As placing teeth in this zone will increase stability, retention and comfort

168
Q

What other aids are available to facilitate denture retention/stability?

A

Denture fixative seal (Seabond)
Adhesives (Fixadent or Polygrip)
Valves
Implant anchors

169
Q

What is a reline?

A

New fit surface for an existing denture/part of an existing denture

Can be done chairside

170
Q

What are the 3 types of reline?

A

Temporary (coe-comfort)
Soft - provides cushioning
Permanent - resilient

171
Q

What are temporary liners used for?

A

Tissue conditioning - grossly ill-fitting dentures
Post immediate dentures
After implant surgery

172
Q

When are soft liners used?

A

Useful for those with:
- Parafunctional habits
- Very atrophic ridges
- Cancer/cleft lift pts (obturators)

173
Q

What are the disadvantages of soft liners?

A

Plasticiser leaches
Deteriorates with time
Harbours microorganisms

174
Q

What are the different soft lining materials that are available?

A

Heat cured acrylics
Self cured acrylics - coe-soft
Heat cured silicones - Molloplast B
Self cured silicones

175
Q

What is a denture rebase?

A

Replacing the entire base material of an existing denture

Mostly done in the lab

176
Q

Before taking impressions for a rebase, what must you do to the current denture?

A

Remove all undercuts from the denture using an acrylic bur

177
Q

What does a dental implant consist of?

A

Implant
Abutment
Abutment screw
Restoration screw

178
Q

What medical conditions may contraindicate implant placement?

A

Chemoradiotherapy - osteoradionecrosis

Polypharmacy - dry mucosa = implant failure

Immunosuppression - failure of healing between bone and implants

Alendronic acid/bisphosphonates - risk of MRONJ

Cardiac issues - surgical risks, bleeds

Mental health issues - unable to cope, consent/capacity issues

Diabetes - increased failure rate

Thyroxine - increased failure rate

179
Q

What DH aspects may contraindicate implant placement?

A
  • Poor OH
  • Perio disease - poor prognosis
  • Uncontrolled caries - poor prognosis
  • Status of other teeth
  • Dental anxiety - long/complex tx
  • Status of pre-existing implants
  • Bruxism - increased failure rate
180
Q

Under what conditions are pts offered implants on the NHS?

A

H&N cancer
Severe hypodontia
Significant trauma
Cleft palate

181
Q

What are the different types of implants?

A

System, tapered, platform, co-axis
Narrow, regular, or wide
Angle of emergence

182
Q

When should have osseointegration occurred following implant placement?

A

~3 months following implant placement

183
Q

What are the 4 different types of implant overdenture abutments?

A
  1. Locator (TM) abutments
  2. Ball abutments
  3. Gold bar
  4. CAD-CAM Titanium bar
184
Q

What are the 4 different types of implant overdenture abutments?

A
  1. Locator (TM) abutments
  2. Ball abutments
  3. Gold bar
  4. CAD-CAM Titanium bar
185
Q

List 4 post-implant treatment complications

A
  1. Peri implant mucostitis
  2. Peri-implantitis
  3. Loose/fractured components
  4. Late implant failure
186
Q

How does peri-implantitis differ from peri-implant mucostitis?

A

Peri-implantitis involves crestal bone loss whereas peri-implant mucostitis doesn’t.

187
Q

Which flange design would you choose in the case of a surgical extraction?

A

Full flanged to maximise seal and retention of the denture

188
Q

How long should IR dentures be kept in after extraction?

A

24 hrs

189
Q

Why is a facebow used?

A

To record the relationship of the maxilla to the TMJ

190
Q

What can happen to alginate impression if left in the sterilising solution for over a long period of time?

A

Imbibition

191
Q

What can happen to an alginate impression if f not kept in a sealed bag with wet napkins?

A

Synerisis

192
Q

How is injection moulding carried out?

A

The flask and injector in place

The clamp handle is turned and the piston pushes the resin into the mould

Resin escaping the mould at the bottom indicates that the mould is full.

193
Q

How is dough packing carried out?

A

The acrylic dough is placed in the mould

The mould is closed and squeezed together in a clamp

The excess that comes out the side of the flask is known as flash

194
Q

What are the advantages of injection moulding over dough packing?

A

No flash minimising open bite when fitting the denture

No trial pack

Less handling of the material

Less pressure when injecting material

195
Q

What are the disadvantages of injection moulding over dough packing?

A

Need to add a sprue
Extra training
Expense of equipment
Difficult to de-flask
Technique sensitive

196
Q

What causes contraction porosity?

A

A lack of pressure on the acrylic resin

  • not enough resin to fill the mould
  • or failure to apply enough pressure when clamping the flasks
197
Q

What does contraction porosity look like?

A

Small holes through the denture

198
Q

What is gaseous porosity caused by?

A

Wrong curing cycle
- too much heating when processing the denture

199
Q

Where will the porosity be observed in the denture?

A

Within the thickest part of the denture

200
Q

What do you use to measure the OVD?

A

Willis bite gauge

201
Q

Why would you want to avoid having a really thick soft lining?

A

As it will weaken the denture as there is less acrylic

202
Q

What scientific term is used to describe the change in length of a specimen?

A

Strain

203
Q

What scientific term is used to describe the force to flatten a cylinder?

A

Compression

204
Q

What scientific term is used to describe the elongation of a specimen?

A

Tensile

205
Q

What is the term used to describe the hardness of a material?

A

Surface hardness

206
Q

What is the force applied to the mid beam to fracture it?

A

Flexural force

Module 5 (1 decks)

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