Bridges (fixed partial dentures) Flashcards

1
Q

5 parts of planning for missing teeth (5)

A
Need a predictable and durable solution
Consider the need for transitional restorations
Build-in contingency planning
High pt expectations
Realistic tx plan
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2
Q

Restorative options for replacing missing teeth (3)

A
RPD
-tooth supported partial denture
-removed and replaced by pt
Bridges
-conventional bridge
-permanently retained by other teeth
-cannot be removed by denture
Implants
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3
Q

Describe removable partial dentures (4)

A

Replace whole dento-alveolar complex
Non destructive
Fully reversive
Effective permanent or transitional option

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4
Q

Describe implants (3)

A

Replace teeth
Can replace bone/ soft tissue with grafts
Surgical option with higher morbidity

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5
Q

Success rate for implants (1)

A

predictable >90%

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6
Q

What do bridges replace? (1)

A

Teeth only

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7
Q

Prognosis of bridges (2)

A

Destructive

Unpredictable long-term prognosis

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8
Q

Design of choice for bridges (1)

A

Single-unit adhesive cantilevered

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9
Q

Clinical examination for replacing missing teeth (7)

A
Occlusal relationship - guidance?
Inter-occlusal space
Centre line
Lip smile line
Position of teeth present 
Shape and position of potential abutments
Restorative and vitality status of teeth
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10
Q

Radiographic examination for replacing missing teeth (+ study models + vitality tests) (6)

A
Position of normal anatomical features
Pathological conditions
Periapical status of abutment teeth
Alveolar support of abutment teeth
Root remnants and foreign bodies
Alveolar height and width
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11
Q

Using panoramic radiograph vs intra-oral periapical to examine missing teeth (5)

A
Panoramic radiograph
-distortion in the horizontal plane
-shadowing of incisor region
Intra-oral periapical better
-using paralleling technique
-to check individual teeth
-to assess alveolar bone width
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12
Q

Aspects of design criteria (10)

A
  1. Periodontal support
    - abutment teeth need to have adequate bony support
    - perio condition must be stable
  2. Occlusal loading
    - magnitude and direction of forces
    - peeling effect if abutment is put under tensile load
  3. Conservation of tooth tissue
    - adhesive bridges important for this. Minimal or no reduction
  4. Cleansability
    - ensure we can use Tepes/ superfloss
  5. Appearance
    - esp. in anterior region. Greying of teeth with metal adhesive section
  6. Rigidity (of retainer/ connector)
    - reduce flexion
  7. Quality of abutments
    - endo, heavily restored not good choices
  8. Number of abutments
  9. Choice of adhesive lute
    - can’t use luting cement for adhesive bridges
  10. Contingency planning
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13
Q

Retention of bridges is achieved by (4)

A

Full coverage retainers
-prep of abutment tooth is a FGC, PFM or all-ceramic
Adhesive retainers
-prep of abutment tooth is minimal and involves palatal and proximal surfaces only

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14
Q

Use of fixed-fixed abutments (1)

A

The bridge spans from one abutment to another with the pontic in between
Abutment-pontic-abutment

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15
Q

Use of cantilevered abutments (1)

A

The bridge is retained by one abutment only

Abutment-pontic

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16
Q

Periodontal support (3)

A

Perio disease history not so important
Current and future periodontal health are critical
Maintenance of periodontal health

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17
Q

Types of occlusal loading (6)

A
Functional
Para-functional loads
Lateral excursive movements
-canine guidance
-group function
-interferences
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18
Q

Metals used for bridges (3)

A
All cast metal
-base metal or (better) 60% gold
All ceramic
-zirconia, lithium disilicate
Metal-ceramic
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19
Q

Choice of abutments depends on (4)

A

Tooth position
Crown shape
Restorative status
Endodontic status

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20
Q

Poor abutment teeth (3)

A

Maxillary lateral incisors
Tilted incisor teeth (unfavourable pulp chamber morphology)
Root-filled teeth

21
Q

What is the bridge design of choice and why? (6)

A

Single tooth, fixed-cantilevered
-e.g. upper lateral cantilevered off a canine
More retentive than fixed-fixed counterparts
Pontic allowed to move with abutment
Reduced shear forces on pontic
Debond leads to cleansable surfaces
Risk of caries eliminated

22
Q

Describe best case for adhesive bridges (3)

A

Single tooth replacement
Fixed to only one carefully selected abutment
Cantilevered

23
Q

Framework design for adhesive bridges (6)

A
Retainer thickness and configuration
Bonding area: maximise
Wrap-around
Occlusal extension of metalwork (e.g. on premolars)
Connector design
Length of span
24
Q

Retainer thickness and configuration (2)

A

Retainers for molars 0.8mm thick
Greater if retainer not joined over occlusal surface
-thickness provides rigidity

25
Q

Bonding area (2)

A

Maximum enamel bonding
Extension of metal work as far occlusogingivally and circumferentially around tooth as is possible
-downside is metal shine through

26
Q

Wrap-around maximum (1)

A

180 degrees

-mesial and distal groove

27
Q

Occlusal / palatal extension of metalwork (3)

A
  1. Full palatal coverage with no tooth prep (maximise SA/ minimise prep)
  2. Reduced palatal coverage with tooth prep (finish 1-3mm short of incisal edge)
    Posterior occlusal coverage to
    -resist displacement apically or laterally
    -increase rigidity of framework
    -greater surface area for bonding
28
Q

Connector design (4)

A

Significant width and height required
Need to resist bending of alloy
Must avoid putting adhesive lute under tensile loading
Height of connector at least 50% height of pontic

29
Q

Length of span (2)

A

Ideally one tooth replacement
Longer spans not contra-indicated but tooth prep and framework design should be planned to reduce potential debonding stresses on retainer

30
Q

Tooth prep features (5)

A
Axial tooth prep
Grooves
Occlusal rest seats
Intracoronal prep
Cantilevered resin bonded bridges
31
Q

Axial tooth prep (3)

A

Increases area for bonding
Increases resistance and retention form
Minimal reduction with chamfer finish

32
Q

Grooves (4)

A

Provide > resistance form to lateral displacement
May help > retention form
> structural rigidity of metal framework after cementation
Use of 2 grooves (1mm deep) per abutment significantly > resistance to debonding forces for both anterior and posterior bridges

33
Q

Occlusal rest seats (3)

A

Allow transmission of occlusal forces along long axis of tooth
Provide resistance form
Possibly limit shear forces to cement lute

34
Q

Intracoronal prep (3)

A

Joining of mesial and distal rest seats of retainer over occlusal surface to form occlusal bar to improve rigidity of retainer
Enhances retainer’s resistance to deformation
Improves resistance form and increase SA for bonding

35
Q

What cements to use (4)

A

Always use an adhesive lute
Self-cure composite lute (e.g. RelyX Unicem)
-non adhesive
-REQUIRES: in combination with bonding system
-requires etched metal substrate
Anaerobic adhesive lutes - Panavia
-opaque
-specific adhesion to metal retainers
4-Meta adhesive lutes (methacylate based e.g. Calebra?)
-specific bonding to metal and ceramic retainers

36
Q

Types of alloys for adhesive bridges (3)

A
Nickel chromium (cheap! so very common)
-can be electrolytically etched
-very rigid
-work very well with composite luting systems
Gold alloys
-cannot be etched
-not as rigid as Ni/Cr
-need sandblasting
-need specific adhesive systems
Ceramics (e.g. Zirconia, lithium disilicate)
-experimental
-more aesthetic
37
Q

Survival of metal vs non-metal framework - 5-year (2)

A

Metal framework 88%

Non-metal framework 84%

38
Q

Choice of abutments for adhesive bridges (4)

A

Tooth position
Crown shape
Restorative status
Endodontic status

39
Q

Quality of adhesive bridge abutments depends on (5)

A
Endodontic status and prognosis
-elective endo not unheard of
Restorative status
-if heavily restored, maybe conventional bridge better
Quality of bonding substrate
Anatomical shape
Retention/ resistance form
40
Q

Poor abutment teeth for adhesive bridges (3)

A

Maxillary lateral incisors
Tilted incisor teeth
Root-filled teeth (not never, but best avoid - dry, brittle, prone to fracture)

41
Q

Resin bonded bridges 5 year survival (1)

A

88%

Pjetersson et al SR 2008

42
Q

Reasons for failure of resin bonded bridges (3)

A
Debonding
-failure of bond
-lack of rigidity leading to a "peel effect"
Caries under retainer
Aesthetic failure
-show through of retainer
43
Q

What are double abutments for adhesive bridges? (2)

A

2 adjacent teeth as abutments - NOT required

44
Q

What are fixed-fixed adhesive bridges? (3)

A

Adhesive retainers with intermediate pontics
Generally not recommended
Only exception is the mandibular incisors, where the ‘peel-dislodgement’ effect is less
Minimal palatal and proximal preparation of two abutment teeth

45
Q

What’s better, cantilevered RBB or fixed-fixed RBB (2)

A

Cantilevered siginificantly better success

Reason - debond of fixed-fixed

46
Q

Why do fixed-fixed adhesive bridges fail? (4)

A

Significant stresses applied to retainers of fixed-fixed resin-bonded bridges because of differential tooth movements between abutments during functional and parafunctional tooth contacts
These forces tend to push one of the abutments away from the pontic
Tensile stress of the cement
Debonding of an abutment and caries under the retainer

47
Q

Which patients are most suitable for adhesive bridges? (1)

A

Fairly intact dental arches: only 1 or 2 missing teeth, don’t want to resort to an RPD
Case selection v important

48
Q

Adhesive bridges synonyms (4)

A

Resin-bonded bridges
Bonded bridges
Maryland bridges
Rochette bridges

49
Q

Fixed partial denture =

A

Conventional bridge work