Extra-Coronal Provisional Restorations Flashcards

1
Q

What are the 4 stages of indirect restorations?

A
  1. Preparation
  2. Temporisation
  3. Impressions and registration
  4. Cementation
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2
Q

What does the tooth prep results in?

A

 Compromises aesthetics in smile line
 Degrades tooth function - occlusion reduction and destabilises occlusion
 Exposed dentine - tooth sensitivity

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3
Q

What characteristics should a provisional restoration have?

A

 Have good marginal fit
 Be well contoured
 E.g. no overhangs
 Cleansable and maintainable by patient (no gingivits means fit of crown will be good)
 Establish and/or maintain dental aesthetics
 Prevent sensitivity
 Prevent microleakage/bacterial leakage
 Confirm that tooth preparation is adequate
 No OVD changes (unless desired)
 Prevent drifting or tilting of prepared teeth
 Preserve or improve function

 Additional uses:
 Isolation for RCT
 Matrix for core build-up

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4
Q

What are desirable characteristics of provisional materials?

A
  • Non-irritant
  • Low temperature rise during setting (no exothermic expansion)
  • Dimensionally stabile
  • Adequate working time
  • Adequate setting time
  • Adequate strength and wear resistance
  • Good aesthetics
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5
Q

What are the two types of provisional restorations?

A

Custom formed
 “Bespoke” to individual situations
 Preferable
 Can be technically demanding

Preformed
 Standard shapes and sizes
 Adjust to fit chairside

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6
Q

What material is used for custum resin provisional crowns?

what are examples

A

Chemically cured bis-acrylic composite resin

 Protemp Plus (3M ESPE)
 Integrity Temp-Grip (Dentsply)
 Customisable - fits tooth prep internally and reproduces contact points and occlusion externally

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7
Q

When should the provisional crowns be made?

and why?

A

Make before impressions for definitive restoration are taken
 Helps check that tooth prep is satisfactory
 Undercuts
 Sufficient reduction

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8
Q

What tool can be used to measure if reduction is sufficient?

A

svensen gauge

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9
Q

What type of impression is used for provisional crowns?

what materials can be used?

A

sectional impression

Materials:
 Addition cured silicone putty (e.g. President)
 Can be disinfected and kept by patient or clinician; Can be reused; Resistant to tearing
 Alginate
 Cheaper;
 Cannot be reused or kept
 Softened modelling wax
 Easy to adjust and smooth; Cheap; Unsuitable for deep undercuts; Distorts; Cannot be reused

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10
Q

What are the steps to making a provisional restoration?

12

A
  1. Sectional impression
  2. Prepare tooth for chosen restoration
  3. Syringe bis-acrylic composite resin material onto bracket table or mixing pad
    I. Ensure its mixed
    II. Monitor setting
  4. Syringe material into sectional impression of tooth that has been prepared
  5. Relocate impression in the mouth
    I. Ensure fully seated
    II. “click” over bulbosity of remaining teeth
  6. Remove before complete polymerisation
  7. Remove completely
  8. Remove flash and ledges
    High speed and/or polishing discs
  9. Confirm tooth preparation
     Svensen gauge
  10. Check marginal fit and occlusion in situ
     Adjust if required (ideally outside the mouth)
  11. Check aesthetics
  12. Cement provisional restoration using temporary luting cement
    * E.g. TempBond NE (Kerr Dental) - Non-eugenol temporary cement material
    * Trim away excess
    * Margins
    * Interdentally
    * Dental floss
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11
Q

How is occlusion guidance (anterior/incisal) produced on crowns? (toothwear case)

A

 Diagnostic wax up
 Articulated study models
 FaceBow registration required

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12
Q

What do the lab produce for the next patient visit if patient needs occlusion restored?

A

 Duplicate waxed-up cast
 Construct vacuum-formed mould/stent/template over duplicate cast

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13
Q

For patients that need occlusion guidance what must be done after preparing the teeth?

A

o Use vacuum formed mould to produce custom-formed provisional restorations to new occlusion and appearance

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14
Q

How can the provisional crown be adjusted?

A

trim with bur
or
addition of composite

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15
Q

How can guidance created on provisionals be transferred to definitive?

A

 Impressions of provisionals in-situ and opposing teeth
 Mount master casts on semi-adjustable articulator
 Place unset acrylic on incisal table
 Reproduce lateral and protrusive movements
 Technician constructs definitive restorations
 Constantly checks again excursive movements
 Guided by custom-formed incisal table
 Simultaneous contact between restorations/opposing teeth and incisal pin/guidance table

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16
Q

How can gingival contours be established?

A

Use provisional restorations to achieve satisfactory emergence profile for definitive restoration

17
Q

Apart from resin, what are the other options for provisional crowns?

A
  • preformed provisional crowns (can be tooth coloured or metal)
  • preformed malleable composite crowns
  • composite
18
Q

What are the types of tooth coloured preformed provisional crowns?

A

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

19
Q

What are the types of metal preformed provisional crowns?

A

aluminium
stainless steel

20
Q

What are the problems with preformed provisional crowns?

A

Unlikely to fit accurately
Large bank of crowns needed (expensive)

21
Q

When are preformed provisional crowns useful?

A

Useful for situations where no impression taken prior to tooth preparation or damage

22
Q

What are the steps for Polycarbonate (Directa) preformed provisional crowns?

10

A
  1. Select shell slightly larger than preparation
  2. Trim back (with pink stone in straignt handpiece) until
    Correct preparation dimension
    Seats fully over tooth preparation
    Not bedding into gingivae
  3. Fill shell (with trim or protemp)
  4. Seat over tooth
  5. Allow polymerisation
  6. Remove
  7. Check fit
  8. Trim/Tidy if necessary
  9. Cement with Temporary luting cement (e.g. Tempbond)
  10. Cut off tag NOTE: If overbuilt – blanching of gingivae occurs
23
Q

What are the steps to clear plastic provisional crowns?

9

A
  1. Select and trim until fit
  2. Pierce hole at cusp tip/canine tip/incisal angle (no air 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
  9. Adjust if necessary
  10. Cement with temporary cement
24
Q

What teeth can polycarbonate and clear plastic be used for?

A

anteriors
premolars

25
Q

What teeth can metal preformed crowns be used for?

A

posterior

26
Q

What must be done with metal crowns and how?

A

Remove any ledges and sharp margins to avoid soft tissue trauma

use crimping device

27
Q

What can be used to remove a provisional restoration?

A

 WAMkey
 Safe Relax/Anthrogyr
 Sliding hammer

28
Q

How is a preformed malleable composite crown used?

A

 Moulded over tooth to desired shape
 Partially light cured
 2-3 secs
 Otherwise – difficult to remove
 Remove then completely cure outside of mouth
 Check fit
 Adjust if necessary
 Cement

29
Q

How is composite used as a provisional restoration?

A

veneer cases
spot bonded

30
Q

What is conventional bridgework temporisation?

A

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

31
Q

What are alternatives to conventional bridgework temporisation?

A

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

32
Q

What is advice given to patient and why?

A

Patient to maintain good OH
 Brushing 2-3x daily
 Interdentally cleaning 1-2x daily
 CAUTION WITH FLOSS - may pull out provisional restoration

Otherwise:
 Gingival inflammation
 Increased:
 GCF
 Bleeding
 Poor moisture control for definitive impressions
 Inadequate cement lute placement