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BDS3 - Operative Dentistry > provisional extra-coronal restorations > Flashcards

provisional extra-coronal restorations Flashcards

1
Q

what are the clinical stages of provisional extra coronal restorations

A
  • Preparation
  • Temporisation
  • Impressions and registration
  • Cementation
  • Success of each stage is dependent on success of preceding stage
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2
Q

why is tooth preparation not ideal

A
  • compromises aesthetics in smile line
  • occlusion reduction in function
  • destabilises occlusion
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3
Q

what should provisional restorations do

A
  • have a good marginal fit
  • be well contoured
  • cleansable and maintained by patient
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4
Q

what happens if we have a poorly fitting contoured provisona

A
  • patient unable to clean = caries, periodontal disease
  • poor moisture control
  • gingival overgrowth
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5
Q

what must provisionals do

A
  • establish and/or maintain dental aesthetics, mimicking either the original tooth or a definitive restoration
  • prevent sensitivty
  • allow ‘optimum home care’
  • prevent micro leakage
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6
Q

what are some additional uses of provisional restorations

A
  • isolation for RCT

- matrix for core build-up

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7
Q

what are desirable characteristics of provisional materials

A
  • non-irritant
  • low temperature rise during setting
  • dimensionally stable
  • adequate working time
  • adequate setting time
  • adequate strength and wear resistance
  • good aesthetics
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8
Q

what are the different types of provisional restorations

A
  • Custom formed

* Preformed

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9
Q

which type of provisional restorations are preferred

A
  • customer formed
  • can be technically demanding however
  • fits better and looks better
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10
Q

what materials are used for custom provisional restorations

A
  • typically made out of composite

- chemically cured bis-acrylic resin

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11
Q

why is composite good to use for provisionals

A
  • customisable = can add to it or take away

- easy to adjust

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12
Q

what is a svensen gauge

A
  • pincers to clamo over restoration and needle slide up the ruler to show how thick it is
  • can use temporary restoration to check how much tooth you have removed
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13
Q

what type of impression do we take for temporary restorations

A
  • sectional impression

- don’t need full arch

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14
Q

what materials are used for an impression

A
  • addition cured silicone putty = ‘President’
  • alginate
  • softened modelling wax
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15
Q

why is president a good impression

A
  • can be disinfected
  • can be reused
  • resistant to tearing
  • doesn’t shrink of expand over time
  • mainly used
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16
Q

what are the properties of softened modelling wax

A
  • easy to adjust and smooth
  • cheap
  • unsuitable for deep undercuts
  • distorts
  • cannot be reused
  • easy to use
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17
Q

how are custom made vacuum formed stents made

A
  • sectional impression
  • prepare tooth for chosen restoration
  • syringe bi-acrylic composite resin into bracket table or mixing pad
  • syringe material into sectional impression of tooth that has been prepared
  • relocate impression in the mouth
  • remove completely
  • remove flash and ledges
  • confirm tooth preparation
  • check marginal fit and occlusion in situ
  • check aesthetics
  • cement provisional restoration with temporary luting cement
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18
Q

how full do you fill the impression with Protemp

A
  • 3/4 full
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19
Q

what pressure is used to seat temporary restoration

A
  • finger pressure
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20
Q

when may we need to reestablish occlusion and aesthetics

A
  • loss of original tooth form = from wear

- for guidance

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21
Q

what type of guidance is preferable

A
  • canine
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22
Q

how do we form guidance

A
  • produce on crowns
  • diagnostic wax-up = take upper and lower impressions of patient with toothier
  • articulated study models = on articulators
  • Facebow registration required if changing occlusion
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23
Q

what do we do once guidance and aesthetics are satisfactory

A
  • lab duplicates waxed-up cast
  • construct vacuum formed stent
  • prepare teeth in next visit
  • patient trial
24
Q

what articulator is commonly used

A
  • semi-adjustable articulator
25
Q

how do we record the lateral and protrusive movement

A
  • place unset acrylic on the incisal table of the articulator
  • reproduce the lateral and protrusive movements on it
26
Q

what do we do if it is a high aesthetic demand case

A
  • alter provisional restorations = minor changes at chair side
  • extensive changes = replace provisional restoration
27
Q

how do we establish gingival contours

A
  • use provisional restorations to achieve satisfactory emergence profile for definite restorations
  • when providing implants can use provisional restoration to hold gingiva around tooth
28
Q

what is the emergence profile

A
  • shape that the tooth takes after it comes off the implant as it comes out of gingival
29
Q

what happens if the emergence profile is flat

A
  • the gingival would collapse in the way and wouldn’t look as aesthetic
30
Q

what happens if the emergence profile mimics the natural tooth

A
  • want to make sure provisional pushes the gingival out a little bit to mimic contour of gingival around a natural tooth
31
Q

what are the two variations of preformed provisional crowns

A
  • tooth coloured = polycarbonate

- metal = aluminium, stainless steel

32
Q

why do we need a large bank of different provisional shapes and sizes of preformed crowns

A
  • because there is so much variation in patients
33
Q

what are the problems with preformed provisional crowns

A
  • unlikely to fit accurately

- large bank of crowns needed = expensive

34
Q

when can preformed provisional crowns be used

A
  • good for situation where no impression is taken prior to tooth preparation or damage
  • good for when we are put on the spot and need a provisional restoration = trauma cases
35
Q

what are polycarbonate crowns used for

A
  • mainly for anteriors and premolars
36
Q

what is the method for placing preformed provisional crowns

A 
•	1 - Select shell slightly larger than preparation
•	2 - Trim back until 
- Correct preparation dimension
- Seats fully over tooth preparation
- Not bedding into gingivae
- Adjust to get some degree of fit around margins 
•	3 - Fill shell
•	Trim or Protemp
•	4 - Seat over tooth
•	5 - Allow polymerisation
•	6 - Remove
•	7 - Check fit
•	8 - Trim/Tidy if necessary
•	9 - Cement
37
Q

how are clear plastic crowns placed

A
  • Select and trim until fit
  • Pierce hole at cusp tip/canine tip/incisal angle
  • Fill with bis-acrylic composite resin
  • Seat over tooth
  • Allow setting
  • Remove from tooth
  • Remove plastic crown form
  • Check margins and occlusion
  • Cement with temporary cement
38
Q

what are metal preformed crowns used for

A
  • posterior teeth
39
Q

what are some problems with metal preformed crowns

A
  • cause trauma to soft tissues
  • difficult to adjust
  • very rarely do in adult dental setting
40
Q

how do you remove an old crown

A
  • with a WAMkey
  • safe relax/Anthrogyr
  • sliding hammer
41
Q

how does a safe relax/anthrogyr work

A
  • automated version of sliding hammer
  • handpick to connect to handpiece
  • pull handpiece up to hear it clock and engage
  • press foot pedal to hear steady tapping
  • little wires go under Pontic of bridges to get them off as well
42
Q

how does a sliding hammer work

A
  • metal rod with weight sliding up and down on it
  • different heads for it
  • put hook round margin of crown and slide weight up crown and it bashes against top of crown
  • taps of crown in occlusal direction
43
Q

what is good about preformed malleable composite crowns

A
  • they are soft
  • easy to mould to tooth prep
  • shaped like a tooth but not set yet so can mould it
44
Q

how are preformed malleable composite crowns placed

A 
•	Moulded over tooth to desired shape
•	Partially light cured
•	2-3 secs
- If any longer than this then difficult to remove 
•	Otherwise – difficult to remove
•	Remove then completely cure outside of mouth
•	Check fit 
•	Adjust if necessary
•	Cement
45
Q

what is a spot bonded temporary veneer

A
  • Divide tooth into 9 square and in middle put little bit of bond and basically add composite bit by bit onto labial surface of tooth to build up a veneer then cure it
  • Last a few weeks
  • Not as bonded as usual, but don’t want that as want to just be able to place excavator under it and flick it off
46
Q

what are the properties and what are the stages for indirect provisional restorations

A
  • Lab made (usually acrylic)
  • Low shrinkage intra-orally
  • More accurate
  • High strength
  • Time and cost consuming
  • Used long-term
  • Examples of used materials: Composite, Acrylic, Metal
  • Lab will make something more accurate than you would chairside
  • Acrylic higher strength than soft composite material s
  • Problems
  • Because you now added extra layer of complexity to treatment plan so more visits and lab time required so costs more time and money
47
Q

what can be used as provisional replacement of missing teeth

A
  • conventional bridgework temporisation
  • acrylic removable partial denture
  • Essix retianer with Pontic
48
Q

what is a conventional bridgework temporisation

A
  • similar to custom-formed provisional crowns

- diagnostic wax-up of replacement tooth

49
Q

what is a conventional bridge

A
  • two crowns with a retainer
50
Q

what can you do if you don’t want to use a conventional bridge

A

put two temporary crowns on abutment teeth and fill edentulous space with temporary denture or essex retainer with pontic which is basically a mouthguard

51
Q

what can happen if you leave edentulous spaces

A
  • teeth can tilt into that space

- not ideal

52
Q

how are resin bonded bridges made

A
  • not a lot of prep
  • provide a little denture in the space as there is nothing for a provisional bridge to hold onto
  • or a Essix retainer
53
Q

what is the best method for provisional replacement of missing teeth if doing implant work

A
  • probably best to use little denture or Essix retainer
54
Q

why do patients need to be cautious with floss with provisional restorations

A
  • may pull it out
  • need to pull floss out in a forward direction rather then pulling it down as more likely to dislodge provisional restoration
55
Q

what happens if patient doesnt maintain good OH

A
  • gingival inflammation
56
Q

why is gingival inflammation a problem for definitive restorations

A
  • bleeding
  • poor moisture control for definitive impressions
  • inadequate cement lute placement

BDS3 - Operative Dentistry (7 decks)

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