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Removable Prosthodontics > Denture choice and design > Flashcards

Denture choice and design Flashcards

1
Q

What is an overdenture/onlay or overlay denture?

A

Denture used where the natural crown for AB teeth is not complete

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2
Q

What are transitional dentures?

A

When you want to make a denture but you know some teeth need extracting within the expected lifetime of the denture

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3
Q

What are immediate dentures and immediate addition dentures?

A

This is a new denture placed in mouth immediately after a tooth is extracted

Immediate addition - where a patients existing denture has an extra tooth added and is fitted imm after extraction

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4
Q

What are temporary dentures

A

A denture used for a short time before permanent denture is made

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5
Q

What is a diagnostic denture

A

tests if patient can tolerate something new (commonly a change in kaw relationship or change in tooth position) or to see if pt can tolerate a denture at all

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6
Q

What are obturators

A

a denture that has an extra piece of acrylic that blocks a hole in the palate (specialist skills needed)

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7
Q

2 materials that dentures are made of

A

Acrylic and CoCr

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8
Q

What factors do you need to consider when choosing which type of denture?

A

Time available - acrylics quicker (can make them fit if impression incorrect)

Yours and technicians skills - CoCr more difficult

Costs - to you and pt (time and money)

Pts choice and expectations - pts preferences guided by dentist

Pts prev denture experience - which denture has worked for them before, how is current denture regarding support, retention, stability

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9
Q

Outline of steps for CoCr RPD design

A
  1. Survey cast - choose/limit POI - consider natural or artificial GPs
  2. S (saddle areas)
  3. S (support - tooth and mucosa)
  4. R (retention - direct and indirect)
  5. R (reciprocation)
  6. C (connectors - major and minor)

CHECK ALL CLASPS RECIPROCATED AND EVERYTHING CONNECTS

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10
Q

How can guide planes and POI be utilised when designing dentures?

A

Choose POI = diff to path of common displacement (right angles to occlusal surface)

Survey cast

Identify favourable and un-favourable undercuts

Identify natural and artificial guide planes

Art GP - flatten contours of AB teeth using burs = parallel sides = limit POI = more retentive, aesthetics of ant teeth (black tri.), function

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11
Q

S - saddle
What is Kennedy Class I

A

Bilateral free end saddles

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12
Q

S - saddle
What is Kennedy Class II

A

Unilateral free end saddles

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13
Q

S - saddle
What is Kennedy Class III

A

Bounded saddles

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14
Q

S - saddle
What is Kennedy Class IV

A

Anterior bounded saddle that crosses midline

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15
Q

What is a modification in kennedy classification

A

Main classification is allocated using most posterior saddle and then however many other saddles there are determines the number of modifications

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16
Q

S - support
What are the key features of rests used for support?

A

Rest on each end of a saddle
Distribute them evenly around the arch - table with 4 legs
Rest on teeth that healthy
Ensure no occlusal interference - enough space and clearance - PREPARATIONS

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17
Q

R - retention (direct)
What is used for direct retention
List the parts of the assembly of this

A

Clasps
System:
-Rests (occlusal)
-Clasp arm (tapered and thinner at the end)
-Reciprocal arm (same length throughout and thicker)
-Minor connector

18
Q

What does a reciprocal arm do?

A

Prevents unwanted tooth mvmt

19
Q

How do clasps and reciprocal arms work

A

Sit passive in undercut and terminal third only engages undercut on AB teeth when denture removed as resists movement

Reciprocal arm engages with tooth throughout and does not move

20
Q

What are the different types of clasps

A

Occlusally approaching - circumferential
Gingivally approaching - anterior teeth
Ring - (recip wraps buccal to lingual)
Lateral

21
Q

How do you choose no of clasps and where to place them
One disadvantage

A

Depends on teeth missing and pattern of tooth loss
Adjacent to the saddles and spread evenly around arch
2 clasps needed - diagonally opposites sides of arch to spread out

Increases risk of caries

22
Q

R - retention (indirect)
What is indirect retention and what is used

A

Rests added
Usually for free-end saddles

-Aim to prevent the FW rotating around an axis which is formed across the AB teeth that are clasped

-Denture rests on teeth or mucosa can resists rotation

23
Q

What are the different types of rests?

A

Occlusal
Cingulum

24
Q

R - reciprocation
What can be used to provide reciprocation for clasp assemblies for posterior teeth and what can be used for anterior teeth?

A

Plate/arm for posterior teeth
Plate with rest/rest only for anterior teeth

25
Q

C - connectors (major)
Different types of upper major connector - which is most commonly used

A

Palatal strap
Palatal plate
Anterioposterior bar
Palatal horseshoe
Combo of chrome and acrylic

Most common:
Anteroposterior bar - relives some of the palate for improved taste

26
Q

Different types of lower major connectors and most commonly used and why?

A

Lingual bar
Sublingual bar
Dental bar
Lingual plate

Most common:
Lingual bar - frees gingival margin for comfort and health purposes compared to plates - need enough sulcus space - 8mm

27
Q

How do you plan for tooth position in CoCr metal dentures?
Which teeth do we usually do this for?

A

Plan ahead - decide where teeth are going to go before making metal framework

Tooth try-in before master impression - set teeth in wax bases on primary cast and let pt see in mouth

Jaw registration - articulate primary casts first

Only for teeth that pt can see in mirror (upper anteriors)

28
Q

Can you adjust or tri/polish a CoCr metal framework?

A

Strong metal alloy so used in thin sections - not enough thickness for major adjustments (thus any errors in impressions or jaw reg poses problems)

Difficult to trim and polish chairside:-
-trimming - maybe with diamond bur
-polishing - softer bur needed for finishing
-FW may overheat w use of burs
-any sharp edges due to trimming may cause trauma

29
Q

What needs to be done properly in order to make an accurate framework?

A

Articulate casts properly - to design occlusal scheme, rests and denture teeth

Block out undercuts properly - on master casts so that fw seats in the mouth first time

Survey properly - ensure natural tooth undercuts present for clasps

Take accurate master impressions - must not distort

Cast master impressions accurately - may affect rests and fit of fw

30
Q

What needs to be assessed to ensure fw is correct?

A
  1. Is it same as design
  2. Are features placed correctly e.g. clasps in undercuts and major connectors in correct position (not too low or high in sulcus)
  3. Damage during polishing or over polishing - distort clasps or teeth change in shape
  4. How strong is the fw - too thin/bends easily? Porosity (lead to fracture)?
31
Q

What metal is CoCr alloy free of to avoid allergy

A

Nickel
Beryllium

32
Q

If you cant save the whole tooth but you save what can and use a denture to replace the missing parts of the tooth e.g. if natural tooth cannot be restored to full size (using crown or composite) - what is this called?

Why would you want to keep tooth?

A

Overdenture, overlay/onlay denture

If you want to retain bone

33
Q

What is an overdenture? What kind of situations are they useful for?
Why would you want to keep or use roots as the abutment?
What can be used on the AB teeth?

A

Partial or complete dentures that completely covers at least one tooth or root - ‘overdenture abutment’
Useful for teeth that cannot be restored to cull crown height but want to keep tooth to retain bone

Root provides denture support and sometimes retention (only if gold coping with precision attachment involved)

‘Domed’ root face (w or w/o RCT). Metal copings can be used but needs RCT. Short crowns can be used.

34
Q

Indications for overdentures

A

Very few teeth in arch (especially upper)
Extreme tooth wear (restorations not possible)
Hypodontia cases (teeth small or mis-shaped)
Cleft palate cases (tooth position compromised)
Transition to complete dentures (can extract roots later after got used to wearing complete denture)

35
Q

Advantages of overdentures

A

Support - eff use of small number of teeth
Preserves alveolar bone
Stability - better than complete dentures
Retention - excellent with precision attachments
Proprioception - preserved PDL
Appearance - can be improved (tooth shape and position)
Masticatory efficiency - better than complete dentures
Psychological - pt not rendered edentulous

36
Q

Disadvantages of overdentures

A

Complex treatment required - if RCTs needed (unsuccessful RCT then XLA needed), rubber dam placement difficult

Increased risk of caries and perio disease - can pt keep teeth and overdenture clean to increase longevity of potential ABs

Soft tissue support - where tooth or root remains –> flange becomes bulky = issues anteriorally (POI needs careful consideration if bony undercuts present - follow direction of bone)

Time and cost - use of precision attachments

37
Q

Transitional denture definition

A

Acrylic partial to which teeth are added over a period of time until it becomes a complete denture

38
Q

What do you need to consider when choosing material of denture? (Acrylic vs CoCr)

A

How long do you want denture to last?
Will things change sig over next few months e.g. bone remodelling (happens due to time)? future tooth loss (acrylic)? natural teeth changing shape due to restorative tx?

39
Q

Advantages of acrylic dentures

A

Easy to modify - remove or add acrylic
Quicker to make - compared to CoCr FW
No metal components needed - (unless clasping teeth) –> pts may not like metal sensation, allergies or aesthetics so acrylic is best
Cheaper to make - BUT may not last as long as metals
Ideal for temporary dentures - lower costs, quicker to make, easier modifications before definitive denture is made

40
Q

Advantages of CoCr dentures

A

Improved stability and comfort - tooth support possible
Better retention - clasps on CoCr more efficient, POI can be limited through guide planes, rests provide indirect retention
Lightweight - stronger, so thinner sections so less bulky (best for lower dentures due to tongue space)
Hygienic designs - connectors that avoid gingival margins –> preserve perio health
Better thermal conductivity - pt aware of temp sensation etc
Less likely to break - major connector rigid (BUT clasps can break easily)
Reduces chances of denture stomatitis - due to framework design and major connector choice

Removable Prosthodontics (3 decks)

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