BDS4 dickie bridges Flashcards

1
Q

indications bridges?

A
  • Function and stability
  • Appearance
  • Speech
  • Psychological reasons
  • favourable abutment angulation
  • favourable occlusion
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2
Q

contra-indications bridges?

A
  • Poor oral hygiene
  • High caries rate
  • Periodontal disease
  • Large pulps (conventional bridge)
  • uncooperative pt
  • Prognosis of abutment poor
  • Length of span too great
  • Degree of restoration (how much of tooth is left after preparation)
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3
Q

what is retainers?

A

The extracoronal or intracoronal restorations that are connected to the pontic and cemented to the prepared abutment teeth

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4
Q

what is a pier?

A

An abutment tooth which stands between and is supporting two pontics, each pontic being attached to a further abutment tooth

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5
Q

what is a unit? and for example what would a bridge with 2 retainers and one pontic be?

A

Either a retainer or a pontic

  • e.g. A bridge with two retainers and one pontic = 3 unit bridge
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6
Q

what are types of bridge designs?

A

conventional or adhesive/resin retained
- fixed-fixed
- cantilever

fixed moveable bridge

hybrid bridge

spring cantilever bridge

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7
Q

what is a cantilever bridge?

A

This type of bridge has a retainer (or retainers) at one side of the pontic only

  • can be either conventional or adhesive/resin retained
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8
Q

what is a fixed-fixed bridge?

A

This type of bridge has a retainer at each end with a pontic in the middle joined by rigid connectors.

  • can be either conventional or adhesive/resin retained
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9
Q

what are advantages of resin bonded bridgework?

A
  • Minimal or no preparation
  • Less costly
  • Less surgery time
  • Can be used as a provisional restoration
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10
Q

what are disadvantages of resin bonded bridgework?

A
  • Metal shine-through
  • Chipping pocelain
  • Can debond (High chance of it debonding again)
  • Occlusal interferences
  • No trial period possible
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11
Q

what are indications for resin bonded bridgework?

A
  • Young teeth (Less destructive)
  • Good enamel quality
  • Minimal occlusal load
  • Good for single tooth replacement
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12
Q

what are contraindications for for resin bonded bridgework?

A
  • Insufficient or poor quality enamel
  • Long spans
  • Heavy occlusal force e.g. Bruxist
  • Poorly aligned, tilted or spaced teeth
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13
Q

what must you do with study models for resin bonded bridgework and what may you consider

A
  • mounted on semi-adjustable articulator with facebow registration
  • may consider diagnostic wax-ups
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14
Q

when to use a direct resin bonded bridge?

A
  • Very useful in emergency situation
  • If tooth needs to be extracted immediately
  • If tooth has been lost traumatically
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15
Q

what are considerations in regards to existing restorations in abutment teeth?

A
  • firstly need sound enamel

composite - ok but might need to consider replacing prior to prep

amalgam - compromised bond to chemically cured composite cement so consider replacing

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16
Q

what is supra gignival chamfer finish line for bridge?

A

0.5mm

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17
Q

how do you do a minimal prep anterior preparation?

A
  • Occlusal contact reduction,
  • Cingulum undercut removal only
  • Chamfer margin (0.5mm supra-gingival)
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18
Q

how do you do a heavier preparation anterior prep?

A

0.5mm palatal reduction(NOTE – metal retainer wing should be 0.7mm thick)
Cingulum rest
+/- Proximal grooves
Chamfer margin (0.5mm supra-gingival)

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19
Q

how do you do posterior preparation?

A
  • Occlusal rests
  • 180º wrap-around with chamfer finish line (0.5mm supra-gingival)
  • +/- Proximal grooves
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20
Q

why must you fit bridge as quickly as possible?

A

Minimise over-eruption and tooth movement

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21
Q

what is treatment of retainer?

A

try in
- fit and aesthetics

chairside micro-etching with 50 micron aluminium oxide particles (sandblast)
- should have been done by technician

clean retainer
- ultrasonic bath if required
- use ethanol to ‘degrasse’ if required (reduced surface tension)

apply chemically (or dual cure) cure composite luting cement just prior to placement of restoration after tooth treatment

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22
Q

how would you go about the treatment on the tooth prior to placing retainer?

A
  • Prophylaxis
  • Isolate with dental dam
  • Etch tooth: 37% ortho-phosphoric acid (some preparations are 40%)
  • Wash & dry
  • Apply primer (A and B mixed together) for 30 seconds
  • Air dry for 2 seconds
  • No need to cure (unlike for direct composite restorations)
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23
Q

after treatment of tooth what do you do?

A

Fit retainer (coated with luting cement) to abutment tooth/teeth

Remove excess cement

Oxygen inhibitor (Oxyguard II) placed around cement margins for 3 minutes
- Wash off

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24
Q

what do you do post-cementation?

A

check occlusion
- confirm pontic does not have excessive occlusal forces applied

demonstrate to patient how to clean around and underneath the bridge
- superfloss
- interdental brushes

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25
Q

what are advantages of a conventional fixed-fixed bridge?

A
  • Robust design
  • Maximum retention and strength
  • Can be used in longer spans
  • Laboratory construction straightforward
26
Q

what are disadvantages of a conventional fixed-fixed bridge?

A
  • Preparation difficult (parallel tooth preparations needed)
  • Preparation must be minimally tapered
  • Common path of insertion for abutments
  • Removal of tooth tissue (danger to pulp)
27
Q

what are advantages of a cantilever bridge?

A

Conservative design
- Compared to fixed-fixed conventional design

Laboratory construction straightforward

No need to ensure multiple tooth preparations are parallel

28
Q

what are disadvantages of a conventional cantilever bridge?

A
  • Short span only
  • Rigid to avoid distortion
  • Mesial cantilever preferred
29
Q

what is a solution to fixed-fixed designs when abutment teeth are not parallel?

A

fixed moveable bridge
- retainers with separate paths of insertion the bridge is united by a moveable connector

30
Q

what is a fixed-moveble bridge?

A

This type of bridge has a rigid connector usually at the distal end of the pontic and a moveable connector mesially
- Allows some vertical movement at the mesial abutment tooth

31
Q

what are advantages of conventional fixed-moveable bridge?

A
  • Preparations don’t require a common path of insertion
  • Each preparation designed to be retentive independent of others
  • More conservative of tooth tissue
  • Allows minor tooth movement
32
Q

what are disadvantages of conventional fixed-moveable?

A
  • Length of span limited
  • Laboratory construction more complicated
  • Possible difficulty in cleaning beneath moveable joint
  • Can’t construct provisional bridge
33
Q

what is a hybrid bridge?

A

one retainer is conventional preparation the other retainer is minimal preparation (adhesive/ resin retained/ resin bonded)

34
Q

what is spring cantilever bridge?

A

One pontic attached to the end of a metal arm that runs across the palate to a rigid connector on the palatal side of a retainer

35
Q

what are advantages of conventional spring cantilever bridge?

A
  • Useful if spacing present between upper incisors
  • Where adjacent teeth are unrestored
  • Where a posterior tooth would provide a suitable abutment (i.e. already has a crown/large direct restoration)
36
Q

what are disadvantages of conventional spring cantilever bridge?

A
  • Can only be used to replace upper incisor teeth
  • Difficult to clean beneath palatal connector
  • May irritate the palatal mucosa
  • Difficult to control movement of pontic, due to springiness of metal arm and displacement of palatal soft tissues
37
Q

how do you evaluate abutment?

A

Must be able to withstand the forces previously directed to the missing teeth

Supporting tissues should be healthy and free of inflammation

Crown to root ratio
- length of tooth coronal to alveolar crest compared to length of root embedded in bone. Optimum ratio 2:3. (Minimum ratio 1:1)

38
Q

what are types of pontic designs?

A
  • wash through
  • dome shaped
  • modified ridge lap
  • ridge lap pontic (full saddle pontic)
39
Q

what are types of materials for conventional bridges?

A
  • All metal
    Gold
    Nickel/Cobalt chromium?
    Stainless steal
  • Metal ceramic
  • All ceramic
    Zirconia
    E.g. LAVA and Procera®
    Lithium disilicate
    E.g. - E.max
  • Ceromeric
    BelleGlass™
    Vectris®
    Targis® Vectris®
40
Q

when would you especially use gold material for conventional bridges?

A

lower posterior area

41
Q

what is most common material for conventional bridges?

A

metal ceramic

42
Q

what is properties of LAVA?

A
  • 3-4 unit fixed bridge (max span)
  • withstand occlusal forces
  • good aesthetics
  • similar reduction to MCC
43
Q

what are properties of zirconia?

A
  • preps on casts scanned (straumann)
  • milled
  • +/- feldspathic (layer) porcelain on top
44
Q

what does a vaccum formed stent allow during construction of a bridge?

A
  • checking of reduction during tooth prep
  • construction of provisional bridge
45
Q

what must you aim for when doing a conventional bridgework prep?

A

parallelism of tapered surface of each prep

  • it is doing same side of both abutments one after other instead of whole abutment then other abutment
46
Q

what do you use for definitive cementation for all metal conventional bridge work and metal ceramic bridgework?

A
  • aquacem (GI luting agent)
  • RelyX luting (RMGI luting agent)
47
Q

what do you use for a definitive cementation for an adhesive/resin bonded/resin retained bridgwork?

A
  • panavia 21 (anaerobic duel cure resin cement with 10-MDP)
48
Q

when should you use distal cantilevers and why?

A

avoid if possible

concern that occlusal forces on pontic will produce leverage forces on abutment tooth causing it to tilt

49
Q

when may you consider a distal cantilever?

A
  • may consider distal cantilever from premolar abutment if unopposed or opposed by a denture
50
Q

why do you use cantilevers more anteriorly?

A

arch of dentition makes it so that occlusal forces on a fixed-fixed will lead to abutment pulling pontics in diff directions leading to debonding of 1 surface and then plaque gets trapped underneath a wing causing caries

51
Q

why do you want a fixed-fixed on posterior teeth

A
  • more likely as you want to spread occlusal load over several teeth
52
Q

what does sandblasted do?

A

creates small indentations on fitting surface

53
Q

when is there a higher risk of failure for bridges?

A
  • when abutment tooth is smaller than pontic
54
Q

what does overtaper result in?

A

reduced retention

55
Q

what is degree of taper for fixed-fixed?

A

5-7 degrees

56
Q

why is mesial cantilever preferred?

A
  • reason is when patients occlude they are more likely to bite onto posterior teeth before anterior ones
57
Q

what is properties of zirconia and lithium disilicate?

A

ceramic is more likey to fracture than metal
- zirconia - stronger but poorer aesthetic
- lithium disilicate - weaker but better aesthetic

58
Q

what does a wash through pontic do?

A

give patient extra occlusal contact to bite on
more for a lower molar and is for function not appearance

59
Q

when is ovate pontic used?

A
  • for pts with good OH but want best aesthetic result.
  • pushes down onto gingiva and gives look of pontic piercing out of gum
60
Q

what is difference between adhesive and conventional by how they look?

A

adhesive has a metal wing because of minimal prep
conventional has another crown on top of abutments as it requires significant prep

61
Q
A