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BDS3 Operative Dentistry > Provisional Extra Coronal Restoration > Flashcards

Provisional Extra Coronal Restoration Flashcards

1
Q

What is a Extra-coronal provisional restoration?

A
  • A restoration provided to patient between tooth prep and fit of an indirect restoration
  • Should be of high-quality of failures can occur which can lead to problems
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2
Q

What do Extra-coronal provisional restorations have a role in?

A
  • Immediate and long term health of the tooth and the supporting structures like PDL
  • Success of definitive restorations
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3
Q

What are the clinical stages for indirect restoration?

A
  • Preparation
  • Temporisation
  • Impressions and registrations
  • Cementation

Success of each stage dependent on success of preceding stage

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4
Q

What are the characteristics of provisional restorations during tooth preparation?

A
  • Compromise the aesthetics in smile line as we have cut away tooth tissue
  • This degrades tooth function via occlusion reduction and destabilisation of occlusion
  • Occlusal and IP reduction causes exposed dentine which leads to sensitivity
  • Also can compromise coronal seal of RCT’d teeth in some cases
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5
Q

What should the provisional restoration have (characteristics)?

A
  • Have good marginal fit
  • Be well contoured e.g. no overhangs
  • Cleansable and maintainable for patient for optimum home care
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5
Q

What happens if the provisional restorations is poorly fitted and poorly contoured?

A
  • Patient is unable to clean it properly
  • Can lead to caries
  • Can lead to gingival inflammation
  • Can lead to poor moisture control and gingival overgrowth which affects the master impressions and so affects final restoration
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5
Q

What must provisional restorations do?

A
  • Establish or maintain dental aesthetics by mimicking the original tooth or definitive restoration
  • Prevent sensitivity
  • Allow optimum home care
    • Prevent plaque build up and caries
    • Maintain gingival health and contour
  • Prevent microleakage/bacterial leakage which preserves tooth vitality (pulpitis)
  • Confirm tooth prep is adequate
  • Give occlusal stability (No OVD change and prevent drifting or tilting of prepared teeth)
  • Preserve or improve function (mastication/speech)
  • Isolation of RCT
  • Matrix for core build up
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6
Q

What are the desirable materialistic characteristics of provisional restorations?

A
  • Non irritant to pulp and periodontal tissues
  • Low temp rise during setting
  • Dimensionally stable
  • Adequate working time
  • Adequate setting time
  • Adequate strength and wear resistance
  • Good aesthetics
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7
Q

What are the types of Provisional restorations?

A
  • Custom formed
  • Preformed
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8
Q

What is a custom provisional restorations?

A
  • Bespoke to individual situations
  • Preferable
  • Can be technically demanding
  • Fits tooth prep internally
  • Reproduces contact points and occlusion externally
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9
Q

What are preformed provisional restorations?

A
  • Standard shapes and sizes
  • May fit but most likely not
  • Adjust to fit when on chairside
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10
Q

What material are custom provisional restorations made of?

A
  • Usually chemical cured bis-acrylic composite resin
  • Protemp plus
  • Integrity Temp-Grip (Dentsply)
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11
Q

When are custom provisional restorations done?

A
  • Made before impressions for definitive restorations are taken
  • Help check tooth prep is satisfactory with no undercuts and sufficient reduction (use Svensen gauge)
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12
Q

How to check the degree of preparation?

A
  • Use a Svensen gauge
  • Once tooth prepared and constructed custom provisional restoration then can use the gauge
  • Will show how much you have reduced the tooth so can show if you have underprepared the tooth
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13
Q

How are custom resin provisional restorations made?

A
  • Do a sectional impression as a full arch impression is unneccessary and difficult to re-seat
  • Use Addition cured silicone putty (president material)
  • Can use Alginate or Softened modelling wax
  • Alternative is Custom vacuum-formed plastic mould (stent) which is made on study model and/or diagnostic wax up in advance
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14
Q

Why do we use Addition cured silicone putty as the first choice for taking a custom resin provisional impression?

A
  • Can be disinfected and kept by patient or clinician
  • Can be reused so useful if problem with provisional restoration and new needs to be made
  • Resistant to tearing
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15
Q

Why can alginate and Softened modelling wax be used for impressions of custom provisional but not the first choice?

A

Alginate
- Cheaper than addition cured silicone putty
- But cannot be reused or kept

Softened modelling wax
- Easy to adjust and smooth
- Cheap
- But unsuitable for deep undercuts
- It distorts
- Cannot be reused

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16
Q

What is the method for making custom resin provisional restoration?

A
  1. Sectional impression
  2. Prepare tooth for chosen restoration
  3. Syringe bis-acrylic composite resin material onto bracket table or mixing pad (ensure it is mixed and monitor the setting)
  4. Syringe material into sectional impression of tooth that has been prepared
  5. Relocate impression in mouth (ensure fully seated and ‘click’ over bulbosity of remaining teeth
  6. Remove before complete polymerisation (Rubbery and fully polymerised material difficult to remove from undercuts)
  7. Remove completely
  8. Remove flash and ledge (use highspeed or polishing discs)
17
Q

What are some issues that can occur when removing the sectional impression from tooth?

A

May stay on tooth
- Gently ease off with instrument beneath contact points
- Otherwise it sets in undercuts

May be removed with the impression
- Leave to completely set

18
Q

How can provisional restorations be useful in cases of tooth wear?

A
  • Can be used to re-establish tooth shape
  • Help pilot occlusion and aesthetics
19
Q

Can provisional restorations be used for establishing anterior/incisal guidance?

A
  • Use a diagnostic wax up
  • Use articulated study models
  • Ensure a FaceBow registration is done
  • Then can produce crown for guidance
20
Q

What are the lab instructions for the custom provisional restoration if you are changing guidance and occlusion?

A
  • Study model and articulate cast
  • Duplicate the waxed-up cast
  • Construct vacuum-formed mould/stent/template
21
Q

What does the Patient trial consists of?

A
  • Wear until happy with form and function
  • Adjust/alter and trim with bur, addition of composite, reassess
22
Q

What is the method when making provisional crowns for tooth wear cases?

A
  1. Obtain mounted study casts
  2. Lab
    - Produce diagnostic wax up
    - Duplicate cast
    - Construct vacuum stent over duplicate cast
  3. Carry out tooth prep if required
  4. Use stent and provisional material to produce provisional restorations
  5. Patient wear Provisionals for trial period
  6. Reassess Aesthetics/ Occlusion
  7. If satisfactory then definitive restorations if not make alterations and reassess further
23
Q

How can the guidance created for the Provisionals be used for the definitive restorations?

A
  1. Create a customised formed incisal guidance table
    - Take impressions of provisionals in-situ and opposing teeth
    - Mount casts on semi-adjustable articulator
    - Place unset acrylic on incisal table
    - Reproduce lateral and protrusive movements
    - Use light cure to set the acrylic once done
    - Definitive restorations now the same as provisional
24
Q

What can you do if aesthetics need to be changed for provisional restorations

A

Minor change - Chairside using burs or addition of provisional material or composite

Extensive changes - Replace provisional restorations and go again with lab

25
Q

What is an important soft tissue that is vital for aesthetics?

A
  • Gingival contours important for aesthetics
  • Can use provisional restorations to shape for gingival contours important for definitive restorations
26
Q

What preformed provisional crowns are available?

A

Tooth coloured
- Polycarbonate (Directa)
- Clear plastic crown forms (filled with composite)

Metal
- Aluminium
- Stainless steel

  • Different shaped/morphologies and sizes
27
Q

What are some problems with preformed provisional crowns?

A
  • Unlikely to fit accurately (Cervically/Occlusally/ Interdentally) - need to adjust
  • Large bank of crowns needed to accomodate patients which is costly
28
Q

When are preformed provisional crowns useful?

A
  • Useful in situations where no impression taken prior to tooth preparation or damage
  • E.g. trauma cases
29
Q

What are the polycarbonate crowns (Directa, JS Dental Manufacturing Inc)?

A
  • Available for 35+ years
  • Tooth coloured shells
  • Only for anteriors and premolars
30
Q

What is the method for preformed provisional crowns?

A
  1. Select shell slightly larger than preparation
  2. Trim cervical aspect back until
    • Correct prep dimension
    • Seats fully over tooth prep
    • Not bedding into gingivae (pink stone in straight handpiece)
  3. Fill shell with Trim or Protemp
  4. Seat over tooth
  5. Allow polymerisation
  6. Remove
  7. Check fit
  8. Trim/tidy if needed
  9. Cement using temporary luting cement e.g. Tempbond
  10. Cut off tag

** If overbuilt then blanching of gingivae occurs

31
Q

What are clear plastic provisional restorations?

A
  • Clear plastic crowns
  • Thin and easy to trim with scissors
32
Q

What is the method for clear plastic provisional restorations?

A
  1. Select and trim until fit
  2. Pierce hole at cusp tip/canine tip/incisal angle
    • Air escapes
    • No bubbles
  3. Fill with bis-acrylic composite resin
  4. Seat over tooth
  5. Allow setting
  6. Remove from tooth
  7. Remove plastic crown form
  8. Check margins and occlusion
    • Adjust if necessary
  9. Cement with temporary cement
33
Q

What are metal preformed crowns?

A
  • Used for posterior teeth
  • Can be aluminium or stainless steel
  • Remove any ledges and sharp margins as this can cause soft tissue trauma
  • Difficult to adjust but can use crimping device to help mould the margins
34
Q

What can you do if you are replacing a old crown?

A
  • Can use/modify original crown for temporary of new
  • May need partially sectioned/relined
  • Try and preserve original crown as much as poss
35
Q

What instruments can be used to remove Old crowns?

A
  • WAMkey
  • Safe Relax/Anthrogyr
  • Sliding hammer
36
Q

What are preformed malleable composite crowns?

A
  • Soft crowns, easily mouldable to tooth prep
  • E.g. Protemp crown temporisation material
37
Q

What is the method for Preformed malleable composite crown?

A
  1. Moulded over tooth to desired shape
  2. Partially light cured (2-3 secs Otherwise – difficult to remove)
  3. Remove then completely cure outside of mouth
  4. Check fit
  5. Adjust if necessary
  6. Cement
38
Q

What are 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
- Meta

39
Q

What is conventional bridgework temporisation?

A
  • Similar to custom-formed provisional crowns
  • Diagnostic wax up of replacement tooth

Alternatives;
- Acrylic removable partial denture
- Essix retainer with pontic (prosthetic tooth)
- Edentulous space and only provisional crowns on prepared teeth

40
Q

What advice should you give to patient after provisional restorations placed?

A
  • Maintain good OH
  • Brush 2-3X daily
  • Interdentally 1-2X daily
  • Caution with floss as may pull out provisional
41
Q

What can bad OH lead to?

A
  • Increased GCF
  • Increased bleeding
  • Poor moisture control for definitive impressions
  • Inadequate cement lute placement

BDS3 Operative Dentistry (5 decks)

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