Temporisation

Question 1

What is a provisional restoration?

Answer 1

A prosthesis that is designed to enhance aesthetics, stabilisation and/or function for a limited period of time, after which it is to be replaced by a definitive prosthesis

Question 2

What is a temporary restoration?

Answer 2

One that has a limited and predetermined lifespan

Question 3

What is a transitional restoration?

Answer 3

Considered as something that is not planned for the longterm but should serve, with modifications (e.g. for aesthetics, occlusal or periodontal changes), for a more extensive period of time, compared to a temporary solution

Question 4

Functions of provisional restorations?

Answer 4

Protection
Maintain tooth position
Aesthetic
Diagnosis
Mastication
Assess tooth reduction
Facilitate plaque control - cleansable
Informed consent
Provide coronal seal between RCT appts
Assess prognosis
Control/customise emergence profile

Question 5

When to use provisional restorations?

Answer 5

Whenever there is going to be a period of time between preparation and placement of the definitive restorations and there are concerns regarding tooth protection/aesthetics/occlusal/periodontal problems

• Routine indirect restorations
• Immediate tooth replacement
• Replacing indirect restorations
• Replace tooth after implant placement
• Planning aesthetic, occlusal or periodontal changes prior to definitive restoration placement

Question 6

Diagnostic uses of provisional restorations?

Answer 6

Aesthetic trials - confirm tooth shape/dimensions before definitive crown fabrication, easier to reshape and trim provisional restorations

Occlusal trial - confirm pt’s ability to tolerate new occlusion prior to lab making definitive restorations

Periodontal changes - used to replace overhanging restorations causing inflammation/recession or after crown lengthening surgery. Kept in place until periodontal tissues have been stabilised

Question 7

Materials for temporisation/provisional restorations - features of polymethyl methacrylate?

Answer 7

Polymethyl methacrylate (PMMA)

• Self/chemical cure
• Good aesthetics, strength and wear resistance, easy to repair/augument
• Significant exotherm and polymerisation shrinkage, strong smell, free monomer can cause pulpal/gingival reactions

Question 8

Materials for temporisation/provisional restorations - features of polyethyl methacrylate (PEM)? (snap)

Answer 8

Self/chemical cure
Lesser exotherm and shrinkage
Poorer aesthetics, strength, wear resistance

Question 9

Materials for temporisation/provisional restorations - features of bis-acrylic composites?

Answer 9

(Pro-temp - used most of the time)
Most commonly self/chemical cure but can get dual cure
Contains Bis-GMA, TEGDMA
Good aesthetics, better colour stability, good wear resistance in adequate thickness
Difficult to repair, weak in thin sections

Question 10

What is direct composite mostly used for?

Answer 10

Adhesive preparations (veneers, minimal preps) to maintain occlusal contacts/improve aesthetics 
Placed without bonding agent (spot etch technique)

Question 11

Features of preformed crowns (aluminium, stainless steel, polycarbonate)?

Answer 11

Useful if you don’t have a pre op impression
Difficult to control marginal adaptation
Often require a lot of chairside modification

Question 12

Features of CAD-CAM filled composites?

Answer 12

Digital dentistry
Intra-oral scans of preparations sent to milling unit (in clinic or technician’s lab)
Composite/PEEK/PMMA milled and fitted
V accurate provisionals

Question 13

Examples of temporary luting cements?

Answer 13

Zinc oxide eugenol (temp bond)
Eugenol free zinc oxide cement (temp bond NE) - Useful if using a resin based luting cement as eugenol can inhibit polymerisation of uncured resins
Temporary resin cements: translucent for cementing veneers, aesthetic trial
Rare cases - zinc polycarboxylate cement to help retain unretentive provisionals

Question 14

What are the direct temporisation techniques?

Answer 14

Preformed crowns
With use of matrices
Direct composite placement
Direct syringe

Question 15

Features of preformed crowns?

Answer 15

Range of different sizes
Polycarbonate (white) for anterior teeth
Aluminium/stainless steel for posteriors
Require trimming or crimping around the margins to provide adequate marginal coverage
Can be relined with resin (PMMA/PEM or Bis-acryl) to improve fit to prep

Question 16

Negatives of preformed crowns?

Answer 16

Difficult to assess margin adaptation interproximally, may need considerable adjustments

Question 17

Steps to placing a stainless steel/aluminium preformed crown?

Answer 17

Choose suitable size
Trim and crimp margins to improve seating
Option to reline with PMMA/PEM/Bis-acryl to improve fit
Check occlusion
Cement into place
Remove excess

Question 18

Steps to placing a polycarbonate (directa) crown?

Answer 18

Choose suitable size
Trim margins to improve seating
Shape to improve appearance
Reline with PMMA/PEM/Bis-acryl to improve fit. Trim excess
Check occlusion
Cement into place
Remove excess

Question 19

Provisionals made from matrices?

How to take and materials used?

Answer 19

Pre-op impressions in silicone or alginate taken of tooth before prep
- Alginate: cheap, dissipates exotherm better
- Silicone: more expensive, re-usable - can give it to the pt
Can take impression of a wax up of the tooth or use an essix retainer/suck-down matrix
If seated carefully, normally quite minimal adjustments

Coat tooth with vaseline - allow you to remove it easily
Bis-acryl (protemp) placed into impression and then seated onto prep, remove at rubbery stage, before it can lock into undercuts
Adjust margins and finish/polish

Question 20

Direct composite placement - Spot etch technique?

Answer 20

Use of phosphoric acid etch at one spot in the centre of the tooth (rinse/dry) and then directly applying a bulk of composite without bonding agent = easy to remove with a probe

Question 21

Direct composite placement - Malleable composites?

Answer 21

Easier handling allows them to be moulded over the tooth and then light cured

Question 22

When are direct composite methods used?

Answer 22

In adhesive preparations where there is minimal tooth reduction (veneer prep, gold onlay preps, resin-bonded bridge preps that require temporisation)

Question 23

What to do if your matrix does not fit or you dont have access to a preformed crown?
Materials used for this?

Answer 23

Direct syringe - material placed around tooth, starting at margins
PMMA/PEM easier than Bis-Acryl as they slump less

Question 24

Features of indirect provisionals?

Answer 24

Can be made before crown prep appointment by taking impressions for study models
Some initial reduction can be done on model and then some provisionals made, these are relined chairside to fit preps
May start off with direct provisionals until indirect are made

Question 25

When don’t you need a provisional?

Answer 25

Preparations in enamel or non-occluding surfaces
Quick lab turnover time
Use of CAD/CAM in office milled restorations

Question 26

Why are provisionals important?

Answer 26

Protect tooth and can test new occlusal schemes and aesthetics

Question 27

What is the go to provisional material?

Answer 27

Bis-acryl (Pro-temp)

Question 28

What to do if the provisional is always breaking?

Answer 28

Relieve inside of pre-op impression to increase bulk of provisional material, then trim chairside

Question 29

How to solve marginal gaps?

Answer 29

Reline/repair provisional
Ensure adequate adaptation of pre-op impression, place silicone around necks of teeth and in tray
Light bonded silicone on tooth and putty in the tray to improve accuracy

Question 30

How to solve wrong occlusion?

Answer 30

Ensure impression is fully seated when making provisionals

Question 31

What to do if you can’t remove your provisional?

Answer 31

Vaseline on tooth and remove it in rubbery stage to prevent it locking in undercuts

Question 32

Can you join adjacent provisionals?

Answer 32

Yes but embrasure must be cleared and OHI demonstrated (Interdental brush fit)