Provisional Extra-coronal Restorations Flashcards
When might you need to place a provisional restoration?
In between preparation of the tooth and fabrication of the definitive restoration.
What characteristics are desirable for a provisional restoration?
Restore aesthetics and function of the tooth
Cover exposed dentine so the patient doesn’t get sensitivity
Prevent the coronal seal of a RCT from being compromised
Good marginal seal
Well contoured- no overhangs
Cleanable and maintainable by the patient
Prevent micro leakage
Occlusal stability- prevent drifting or tilting of prepared teeth, no OVD changes.
If the provisional restoration was not well contoured/had an overhang, what would happen?
Gingival inflammation- poor moisture control, gingival overgrowth
Caries
What are the characteristics of a desirable provisional material?
Non-irritant
Low temperature rise during setting
Dimensionally stable
Adequate working time
Adequate setting time
Adequate strength and wear resistance
Good aesthetics
Easily removed
What material is most often used for provisional crowns?
Protemp- chemically cured bis-acrylic composite resin.
Could also use integrity Temp-grip.
Text book also says Kalzinol and RMGI maybe? Check other lectures.
What material might you use to create your impression for fabrication of a temporary restoration?
Addition cured silicone putty
Alginate
Softened modelling wax- unsuitable for deep undercuts
You can also use a custom vacuum-formed plastic mould- made on study model and/or diagnostic wax up in advance.
Describe the method for provision of a provisional crown using putty impressions?
- Sectional impression using putty
- Prepare tooth for chosen restoration
- Syringe bis-acrylic composite resin material (Protemp) onto bracket table or mixing pad- ensure it is mixed well.
- Place Protemp into sectional impression of tooth that has been prepared
- Relocate impression in the mouth- ensure full seated, click over bulbosity of remaining teeth.
- Remove the impression when the material feels rubbery.
- Remove temporary- may come off within the impression or may stay on the tooth itself.
- Remove flash and ledges- high speed and/or polishing discs.
- Confirm tooth preparation- Swenson gauge.
- Check marginal fit and occlusal in situ.
- Check aesthetics
- Cement in provisional- use temporary luting cement TempBond NE.
- Remove excess cement and check occlusion.
How many impressions are required in total for a veneer, inlay or onlay?
Three.
- Primary impression for a guide
- Primary impressions to allow fabrication of a temporary
- Master impression for fabrication of the definitive restoration.
Describe the process of a toothwear case with regards to provision of an extra-coronal restoration?
- Primary impressions and mount the casts on a semi-adjustable articulator.
- Conduct wax up on the casts- show the patient this and check they’re happy.
- Duplicate the casts with the wax ups.
- Construct vacuum stent over the duplicate cast based on the wax up.
- Prepare the tooth.
- Use the stent and provisional material to produce provisional restorations.
- Patient wears provisionals for a trial period- check aesthetics, occlusion.
- If patient is happy, remove temporaries and take master impressions of the preparations.
- Master cast is mounted on articulator and technician constructs the definitive restorations.
- Remove temporaries and cement in definitive restorations.
Provisional restorations are important because they provide guidance. What does this mean?
You can make a custom incisal table once the patient is happy with the provisionals, which will ensure that all the occlusal contact are replicated in the definitive restorations.
Take impressions of the mouth with the temporaries in situ.
Ask the lab to mount the casts on an articulator and place soft acrylic on the articulator table, use this to reproduce lateral and protrusive movements.
What is the purpose of a diagnostic wax up?
Ensures patient is happy with aesthetics before trying in the temporaries.
Treatment planning for the clinician.
Technician can use it to replicate it in the definitive restoration.
Can be used to make the temporaries- take impression of the diagnostic wax up.
If the patient is not happy with the diagnostic wax up, what can be done at this stage?
Minor changes can be made chair side using burs and adding more provisional material or composite.
If major changes are required then replace the provisional restorations on the cast and start again.
Describe some of the problems associated with preform provisional crowns?
They are unlikely to fit accurately
Large bank of different shapes and sizes required
Costly
But they are useful in trauma cases where no impression can be taken prior to tooth preparation or damage.
What preformed provisional crowns are available?
Tooth coloured- polycarbonate or clear plastic crown forms filled with composite
Metal- aluminium or stainless steel .
Describe the procedure for provision of a preformed polycarbonate crown?
- Select shell slightly larger than the preparation
- Trim back until- correct preparation dimension, seats fully over preparation, not bedding into the gingivae.
- Fill shell with pro temp
- Seat over the tooth and allow polymerisation
- Remove
- Check fit
- Trim/tidy if necessary
- Cement using Tempbond
- Cut off tag NOTE if overbuilt