Provisional Restorations Flashcards
What is the definition of a provisional?
A prosthesis designed to enhance esthetics, stabilization and/or function for a limited period of time after which it is to be replaced by a definitive prosthesis
What is a provisional used for?
Used to assist in determination of the therapeutic effectiveness of a specific treatment plan or the form and function of the planned definitive prosthesis
Many aspects of Fixed Prosthodontics require a __________ restoration to be fabricated indirectly in a dental lab.
definitive
What is the advantage of digital dentistry when it concerns provisionals?
With the advent of Digital Scanning and milling in the office, provisionals are then not needed as the patient leaves the office with a cemented definitive restoration.
What are the main functions of a provisional restoration?
- Prevent Sensitivity
- Prevent Drifting
- Allow tissues to heal
- Return function to dentition
- Esthetics
- Diagnostic evaluations
What are the requirements of a quality provisional?
- Pulpal protection
- Positional Stability
- Occlusal Function
- Ability to Clean
- Marginal Integrity
- Strength and Retention
- Esthetics and Phonetics
What do provisional restorations protect the prepared teeth from?
- Protect against plaque and saliva
- Protect against irritating and painful stimuli (temp changes, chemicals/fluids)
- Protect against abrasion or breakage of prepared tooth
What is important for positional stability of a provisional?
- Proximal contacts
- Occlusal Contacts
- Inter-abutment stability with a bridge
What is another term for a provisional?
temporary
A provisional will prevent _________ drifting of the prepared and/or adjacent teeth
lateral
When a patient comes back in for a crown seat appointment and tells you the temporary fell off a week and a half ago, anticipate…
adjustments which will need to be made to counter the tooth movements that likely occurred
A provisional with open contacts will allow…
food and debris to impact in between
What does a too open proximal contact on provisional with food/debris impaction lead to?
- leads to short term discomfort and pain
- leads to periodontal inflammation and possibility of too much bleeding to be able to seat the crown
Without appropriate contacts on your provisional, there is a good chance the teeth will…
shift collapsing the vertical between your preparation and opposing.
- results in extrusion
What can occur with the crown from the lab if extrusion occurs with the temporary?
- When trying to seat your definitive crown, the crown will be high resulting in more adjustment than desired.
- With too much adjustment, the material can be thinned and therefore weaker, or the anatomy is destroyed making your crown incapable of functioning appropriately in the occlusal scheme of the patient.
If the temporary is too ____, there will be pain, possible loss of the temporary, or a breakage of the temporary.
high
Time and care should be spent to ensure the temporary has what features?
contact, but appropriately shaped to allow function of temporary, while protecting the tooth
What should the occlusal contacts be on a provisional?
- Ideal centric occlusal contacts
- Lateral and Protrusive guidance where appropriate (anterior teeth)
- No contact in lateral or protrusive on posterior teeth
How should the provisional interact with the peridontium?
- Non-impinging margins
- Physiologic contours, emergence profiles, embrasures, and proximal contacts
- Smooth surface texture and finish
- All these lead to optimum periodontal health and predictable crown delivery
What does the margin of a provisional need to look like?
- Fit as close to the finish line of the tooth as possible
- Shape the contour to make is smooth, undetectable with an explorer with a smooth surface finish
- Seal the provisional at the margin to prevent pain, sensitivity or dislodgement.
The provisional emergency profile is…
flat or slightly concave NOT convexed or bulging
What does a rough margin of a provisional do?
- Leads to plaque accumulation and gingival inflammation
- Bleeding gums leads to very challenging impressions or crown seating.
Why does a temporary need adequate thickness?
Strength
- Temp must withstand forces without breaking or dislodgement
What are the characteristics of Bisacryl?
- Bisacryl material we use in this lab and in the clinic.
- Easy to use and easy to trim and polish
- Is a brittle material which can fracture if occlusal load is too strong and if material is too thin.
Why is adequate tooth reduction necessary?
Need adequate thickness of material for strength
How should the esthetics and phonetics be for a provisional?
- Maintain phonetics (proper tooth length, position, contours)
- Facial lip support
- Proper tooth form and appearance
- Tooth shade compatible with remaining teeth
- Provisionals can be a preview of final restorations to enhance patient acceptance.
How do you fabricate an interim provisional?
- Material is placed in a matrix while in a fluid state.
- Matrix is placed on tooth and allowed to solidify
- Matrix is trimmed and polished while material continues to harden
- Must continually place temporary on preparation or temporary will not fit!
- Most interim materials shrink as they solidify!!
Most interim materials shrink as they ________
solidify
How do you fabricate a direct interim?
- Create matrix prior to preparation (putty, vacuum, other)
- Prepare tooth
- Place temp material in matrix and seat in mouth
- Remove, trim and adjust.
- Cement
The ________ forms the external portions of the interim while the ____________forms the internal of the interim
matrix
preparation
What are the two types of interim restorations?
External surface forms
—Pre-fabricated (preformed) crowns (singles)
—Custom Fabricated molds (multiples)
Directly on tooth versus Indirectly on a cast
What are the different types of prefabricated crowns?
- Aluminum or tin-silver
- Stainless steel
- Polycarbonate shells
- Cellulose acetate shells
- VLC moldable crowns
Pre-fabricated crown provisionals must be lined with…
auto-polymerizing resin
Pre-fabricated crown provisionals are limited to…
single units
When is it the best time to use a pre-fabricated crown provisional?
Best when patient in your office with crown off and lost or broken tooth with not enough tooth to make a traditional matrix form
When do you use a custom molded interim?
- Less time consuming
- Can be used for singles but required for multiple units
- Improved contours and esthetics
- Simulated planned restorations when used with diagnostic wax up.
What is the direct technique for custom molded interims?
-Convenient
-Time required for fabrication – routine restorations
What is the indirect technique for custom molded interims?
-Patient Comfort
-If presence of multiple undercuts, allows you to see this before it gets stuck in patient mouth
-Great of long span bridges or multiple units
-Can be fabricated ahead of time in advance of the tooth prep appointment.
When do you use lab fabricated “shell” provisionals?
Typically used for multiple units or full arch provisionals
What are the characteristics of lab fabricated “shell” provisionals?
-Shell is thin and will be relined in the mouth
-Made prior to preparations
-Saves time on big cases
-Not cheap!! Can be several hundred dollars
-Can also mill temporary shells in office with some systems
What are the currently used materials for provisional restorations?
acrylic resins
—Poly Methyl Methacrylate (PMMA) Jet Acrylic Powder/liquid formulations
Bis-acryl composite resin
—Bis-GMA containing materials
—Chemically activated
—Light activated as well
What are the advantages of polymethyl methacrylate (PMMA)?
- good marginal fit
- good strength
- good polishability
- durability
What are the disadvantages of polymethyl methacrylate (PMMA)?
- high exotherimc head increase
- low abrasion resistance
- free monomer toxic to pulp
- high volumetric shrinkage
What are the advantages of bis-acryl composite?
- good marginal fit
- low exothermic heat increase
- good strength
- low shrinkage
- good surface hardness and abrasion resistance
- good biocompatibility, color stability and patient acceptance
- can light cure
What are the disadvantages of bis-acryl composite?
- surface hardness
- less stain resistance
- limited shade selection
- limited polishability
- brittle
- no rubbery stage
- high cost
What material do most practices use for provisionals?
bis-acryl composite resin
Unreacted free monomer of PMMA is…
toxic
Polymerization of PMMA is ____________ and there is ______________ upon
polymerization and cooling
EXOTHERMIC
SHRINKAGE
What is the chemical reaction of PMMA (jet acrylic)?
Chemical conversion of monomer to biologically inert polymer is through a chain reaction
What are the properties associated with monomer (PMMA)?
chemical or allergic irritation
What are the properties assocaited with the set material (PMMA)?
- Exothermic reaction
- Volumetric shrinkage
- Increased strength due to polymerization
What are the properties assocaited with the polymer/powder (PMMA)?
- With proper amount we have strength and handling
- Too little powder – loss of strength
- Too much powder – poor handling and adaptation
What happens with too much PMMA powder?
poor handling and adaptation
What happens with too little PMMA powder?
loss of strength
_________ materials are the most used materials for provisionals.
Bis-Acryl
What are possible problems with interim restorations?
-Time to fabricate
-Length of time temp is required in the mouth
-Materials are good but not great
-Managing deficiencies (Relining, Repairing)
How do you treat fractures surfaces of provisional restorations?
- Grind to expose a fresh surface
- Roughed this fresh surface
- Composite flowable resin to repair
What are the types of of provisional cements?
- eugenol (zinc oxide eugenol/temp bond)
- non-eugenol (polycarboxylate cement/ultratemp, glass-ionomer/smart temp, resin cement/telio)
What are the properties of zinc oxide eugenol (temp bond)?
-Low Strength
-Eugenol is a sedative for tooth
-Eugenol can inhibit resin polymerization
What are the properties of polycarboxylate cement (ultratemp)?
-Low strength cement
What are the properties of glass-ionomer based cement (smart temp)?
Longer term temporary use
What are the properties of resin cement (telio)?
Translucent
What is the process for mixing cements?
- Mix equal parts of base and catalyst on mixing pad with spatula
- Some temp cements come with mixing tip!
Re-check occlusion after cementation because…
the cement thickness sometimes inhibits full seating of the provisional
Provisionals _________ the prepared tooth during crown fabrication
protect
Provisionals need to simulate the natural tooth as much as possible with…
occlusion and proximal contacts all while being gentle to the gingiva
