Extra-Coronal Provisional Restorations Flashcards
What are the 4 stages of indirect restorations?
- Preparation
- Temporisation
- Impressions and registration
- Cementation
What does the tooth prep results in?
Compromises aesthetics in smile line
Degrades tooth function - occlusion reduction and destabilises occlusion
Exposed dentine - tooth sensitivity
What characteristics should a provisional restoration have?
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
What are desirable characteristics of provisional materials?
- 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
What are the two types of provisional restorations?
Custom formed
“Bespoke” to individual situations
Preferable
Can be technically demanding
Preformed
Standard shapes and sizes
Adjust to fit chairside
What material is used for custum resin provisional crowns?
what are examples
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
When should the provisional crowns be made?
and why?
Make before impressions for definitive restoration are taken
Helps check that tooth prep is satisfactory
Undercuts
Sufficient reduction
What tool can be used to measure if reduction is sufficient?
svensen gauge
What type of impression is used for provisional crowns?
what materials can be used?
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
What are the steps to making a provisional restoration?
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- Sectional impression
- Prepare tooth for chosen restoration
- Syringe bis-acrylic composite resin material onto bracket table or mixing pad
I. Ensure its mixed
II. Monitor setting - Syringe material into sectional impression of tooth that has been prepared
- Relocate impression in the mouth
I. Ensure fully seated
II. “click” over bulbosity of remaining teeth - Remove before complete polymerisation
- Remove completely
- Remove flash and ledges
High speed and/or polishing discs - Confirm tooth preparation
Svensen gauge - Check marginal fit and occlusion in situ
Adjust if required (ideally outside the mouth) - Check aesthetics
- 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
How is occlusion guidance (anterior/incisal) produced on crowns? (toothwear case)
Diagnostic wax up
Articulated study models
FaceBow registration required
What do the lab produce for the next patient visit if patient needs occlusion restored?
Duplicate waxed-up cast
Construct vacuum-formed mould/stent/template over duplicate cast
For patients that need occlusion guidance what must be done after preparing the teeth?
o Use vacuum formed mould to produce custom-formed provisional restorations to new occlusion and appearance
How can the provisional crown be adjusted?
trim with bur
or
addition of composite
How can guidance created on provisionals be transferred to definitive?
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
How can gingival contours be established?
Use provisional restorations to achieve satisfactory emergence profile for definitive restoration
Apart from resin, what are the other options for provisional crowns?
- preformed provisional crowns (can be tooth coloured or metal)
- preformed malleable composite crowns
- composite
What are the types of tooth coloured preformed provisional crowns?
Polycarbonate (Directa)
Clear-plastic crown forms
- filled with composite
What are the types of metal preformed provisional crowns?
aluminium
stainless steel
What are the problems with preformed provisional crowns?
Unlikely to fit accurately
Large bank of crowns needed (expensive)
When are preformed provisional crowns useful?
Useful for situations where no impression taken prior to tooth preparation or damage
What are the steps for Polycarbonate (Directa) preformed provisional crowns?
10
- Select shell slightly larger than preparation
- Trim back (with pink stone in straignt handpiece) until
Correct preparation dimension
Seats fully over tooth preparation
Not bedding into gingivae - Fill shell (with trim or protemp)
- Seat over tooth
- Allow polymerisation
- Remove
- Check fit
- Trim/Tidy if necessary
- Cement with Temporary luting cement (e.g. Tempbond)
- Cut off tag NOTE: If overbuilt – blanching of gingivae occurs
What are the steps to clear plastic provisional crowns?
9
- Select and trim until fit
- Pierce hole at cusp tip/canine tip/incisal angle (no air bubbles)
- Fill with bis-acrylic composite resin
- Seat over tooth
- Allow setting
- Remove from tooth
- Remove plastic crown form
- Check margins and occlusion
- Adjust if necessary
- Cement with temporary cement
What teeth can polycarbonate and clear plastic be used for?
anteriors
premolars
What teeth can metal preformed crowns be used for?
posterior
What must be done with metal crowns and how?
Remove any ledges and sharp margins to avoid soft tissue trauma
use crimping device
What can be used to remove a provisional restoration?
WAMkey
Safe Relax/Anthrogyr
Sliding hammer
How is a preformed malleable composite crown used?
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
How is composite used as a provisional restoration?
veneer cases
spot bonded
What is conventional bridgework temporisation?
Similar to custom-formed provisional crowns
Diagnostic wax up of replacement tooth
What are alternatives to conventional bridgework temporisation?
Acrylic removable partial denture
Essix retainer with pontic (prosthetic tooth)
Edentulous space and only provisional crowns on prepared teeth
What is advice given to patient and why?
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
