Quartz 4

F3 Temporizations

12 min read

Temporization1

  • Interim restoration/provisional restoration

Definition from The Glossary of Prosthodontic Terms

temporization: to establish esthetics, occlusal stability, and function for a limited time in preparation for the definitive prosthesis; to verify therapeutic outcome and patient acceptance before the definitive prostheses; syn, PROVISIONALIZATION

Principles of temporization2

Just like the principles of tooth preparation there are also factors that need to be considered during the fabrication of a temporary restoration.

Biologic

  • Protect pulp
  • Maintain periodontal health
  • Provide occlusal compatibility
  • Maintain tooth position
  • Protect against fracture

Mechanical

  • Resist functional loads
  • Resist removal forces
  • Maintain interabutment alignment

Esthetic

  • Easily contourable
  • Color compatibility
  • Translucency
  • Color stability

Detailed principles of temporization3

Biological Factors

  • Protect pulp (if it is still present)

    • Removal of tooth structure can lead to sensitivity if the dentin tubules are exposed to the oral environment
      • For endodontically treated teeth, the focus shifts to preventing bacterial ingress into the canal system.

  • Periodontal health

    • A suitably shaped temporary restoration is required to ensure periodontal health.
    • Appropriate contour shape, and smoothness
    • Appropriate interproximal contacts

  • ==Margins: Margins must be sealed, smooth, and well-contoured to be cleansable and prevent soft tissue injury. Overhangs and open margins must be avoided.==

    • ==Contour: Over-contoured crowns can trap plaque and make cleaning difficult, while under-contoured crowns can cause gingival injury.==

  • Occlusal Compatibility and tooth position

    • Loss of temporary crown can lead to either supra-eruption of the opposing tooth or tilting of the opposing tooth ==or drifting of adjacent teeth into the prepared space. This movement can prevent the final crown from seating correctly, requiring significant chairside adjustments or a complete remake.==

  • Protect against fracture

    • Protect unsupported tooth structure (more for overlays)

Patient Instructions

  • Patients must be informed that the restoration is temporary and held with weak cement.
  • Advise them to avoid sticky or hard foods on that side.
  • Instruct them on proper flossing: pass the floss through the contact point, then pull it out from the side rather than pulling it back up through the contact, which could dislodge the crown.

Mechanical factors45678

  • Resist functional loads
    • Chewing/daily function
    • In complete crown preparation if there is sufficient reduction the temporary material should withstand oral stresses.
    • Provisional restoration for cracked tooth
  • Resist removal forces
    • In complete crown preparation, the retentive factors such as parallel preparation
  • and the luting action of the temporary cement.
    • Instruct patient to not chew sticky foods, can continue to floss, but they are to PULL THE FLOSS THROUGH THE SIDE, and not back through the contacts.

Aesthetic factors9

  • Anterior teeth
    • Accurate shade matching
      • (e.g., using different shades of Luxatemp like A2 or A3) and selecting appropriately colored cements.
    • Appropriate shape
      • The shape should be lifelike. This can be achieved by using a putty key of the original tooth (if it was well-shaped) or a diagnostic wax-up.
  • Complex treatment plans
    • May use long term interim restorations to let patient “try out” the proposed treatment
    • Especially important for large changes to the incisal edges or palatal contour (s, f, th, etc sounds)

Example10

Alternative reasons for long-term temporaries: cracked teeth11

Note

A provisional restoration can be placed on a cracked tooth as an immediate measure to hold it together and protect it, especially when there isn't enough time for a full crown preparation appointment.

  • Numerous proposed management strategies:
    • Single vs multi-staged
    • Direct vs indirect
    • Cuspal coverage?
  • One of potential treatments: Full crown
    • However preferable to start with crack investigation and restoration with composite core prior to crown. Otherwise potential unwanted stress concentration.
    • Thus we are now in “multi-staged treatment”
    • How long do we wait: ranges from 1 week to 6 months.
    • Extracoronal splinting via orthodontic bands, or temporary crowns
    • Tooth with uncertain prognosis: is it worth it?

Temporary materials12

Selection of temporary restoration material depends on several factors:

  • Anticipated load
  • Prosthesis design
  • Span length
  • Duration of provisional restoration

Ideal properties13

  • Adequate strength
  • Abrasion resistant
  • Biocompatible
  • Non-irritant
  • Dimensional stability
  • Ease of contouring and polishing
  • Good aesthetics
  • Convenient handling
    • Working time
    • Setting time
    • Application
    • Easily modifiable

Material categories and types14

  • Custom and prefabricated
  • Direct vs indirect
    • ==Direct: Fabricated entirely in the patient’s mouth.==
    • ==Indirect: Fabricated in a dental lab on a cast.==
    • ==Direct-Indirect: A combination where a shell is made in the lab and then relined in the mouth.==

Choices for custom temporary restorations

  • Polymethyl methacrylate (PMMA)
  • Polyethyl methacrylate (PEMA)
  • Bisacryl composite resin
  • Light-cured composite resin

Fabrication techniques15

Direct Fabrication

  • Eliminates the need of an alginate impression and cast (not entirely…)

  • However technique sensitive

  • PMMA is not suitable due to exothermic reaction and polymerization shrinkage

  • Can be subdivided into “custom” or “preformed” method.

  • Advantages

    • Can be completed in a single visit.
    • Eliminates the need for a separate impression of the prepared tooth for the lab.

  • Disadvantages

    • Technique-sensitive.
    • Potential for pulpal irritation from exothermic heat and monomer release with certain materials (like PMMA).
    • Fit can be compromised due to polymerization shrinkage.

Indirect Fabrication16

  • More accurate

Direct-Indirect Fabrication

  • A shell is formed using the indirect method which is relined chairside to fit the preparation.
  • Reduces chairside time
  • Less heat generation

Direct Fabrication: Preformed Method17

  • A premade mould which must be relined to fit on the prepared tooth.
  • Available forms:
    • Polycarbonate
    • Cellulose acetate
    • Aluminum
    • Tin-silver
    • Nickle-chromium

Polycarbonate Crowns18

  • Colour stable restoration, but only available in 1 shade (can be modified using the lining material)
  • Forms part of the provisional restoration
  • Bonds to PEMA
  • Procedure

    • Select correct crown form based on morphology and mesial-distal width

    • Adjust height until passively fitting

    • Lubricate tooth with petroleum jelly to protect from monomers and prevent bonding of the acrylic to the tooth.

    • Mix PEMA and apply to crown when PEMA loses its gloss

    • Fit crown on tooth, and immediately remove the excess from the margins

    • Once the material is in rubbery phase (2 minutes) remove and reseat the crown to prevent thermal irritation and ensure the crown can be removed later

      • . This repeated removal and reseating also prevents the crown from locking into any undercuts.

    • After 5 minutes when material is fully set, the material can be adjusted and cemented with temporary cement

    • Check occlusion

Acetate Strip Crowns19

  • Does not bond to acrylic

  • Only used to provide shape to the provisional restoration (the crown form needs to be removed)

  • Procedure

    • Trim and adapt the clear form to the tooth.
    • A small vent hole can be poked in an accessible area (e.g., incisal edge) to allow excess material and air to escape.
    • Fill the form with composite resin and seat it on the tooth.
    • Light-cure the composite.
    • Remove the acetate form by cutting or prying it off.
    • Finish and polish the composite temporary.

Metal Crowns20

  • Available in molar and premolar forms

  • More suited for children

  • Very strong

  • Easily adjusted

  • Luted with cement

  • Will form part of the final provisional restoration

  • Procedure:

    • Selected the correct crown based of morphology and mesiodistal width
    • Adjust mesiodistal width with pliers
    • Can adjust the height using scissors or pliers

  • The crown can be lined with PEMA or cemented directly with temporary cement if the fit is adequate.

Direct Fabrication: Custom Method21

  • Requires a mold

    • Silicon or Clear thermoplastic material

  • Mold can be constructed intra-orally with silicon, or can be done on a cast of the teeth. (Allows wax up to change the morphology of the existing tooth)

  • Advantages

    • Easy to apply
    • Can be done in same visit
    • Can incorporate wax up modifications
    • Cheapest

  • Disadvantages

    • Inferior mechanical properties
    • Optimal fit is compromised

  • Fit is compromised as there is no dedicated space for cement.

    • More clinical time

Indirect Fabrication16

  • Advantages

    • Superior mechanical properties
    • Patient not exposed to uncured monomers (allergies)
    • No heat from polymerizing resins
    • Better fit
      • in comparison direct luxatemp restorations are removed when semi-set
    • Better finish and polish
    • Less clinical time
    • Incorporates wax-up modifications
    • Possibility of metal reinforcement

  • Allows the use of materials not suitable for direct intraoral use (e.g., heat-cured PMMA).

  • Disadvantages

    • Time consuming (lab turn around time)
    • Additional cost
    • More suitable for extensive restorations (long term temporaries)

Indirect-Direct Fabrication22

  • Advantages
    • Superior mechanical properties
    • Better finish and polish
    • Incorporates wax-up modifications
  • Disadvantages
    • Additional laboratory cost
    • More time consuming than indirect technique (shells likely need some sort of adjustment)

Indirect-Direct Procedure Overview23

Indirect

  • Stone model is conservatively prepared in the laboratory with supragingival margins
  • Provisional restoration is constructed in the laboratory with the aid of template

. The tooth on the model is under-prepared by the lab technician, meaning the shell will be slightly larger than the final preparation.

Direct

  • Provisional restoration is tried in the mouth and adjusted accordingly
  • Relined with suitable material

Info

The internal surface of the shell is relined with a suitable material (e.g., PEMA) and seated on the actual tooth preparation. After setting, the relined provisional is trimmed, polished, and cemented.

Specific Temporary Materials2425

Polymethyl methacrylate (PMMA)

Advantages:

  • High strength
  • Colour stability
  • Can be characterized
  • Easily smoothed
  • Easily repaired
  • Low cost

Disadvantages:

  • Highly exothermic
  • Significant polymerization shrinkage (21%!)
  • Monomer release toxic to pulp
    • Unpleasant odor
  • Low abrasion resistance

Clinical consideration

The highly exothermic (heat-releasing) reaction makes PMMA less safe for direct intraoral use, and its high polymerization shrinkage can lead to distortion and poor marginal fit if used directly.

PMMA Can be used in indirect or direct-indirect method

Polyethyl methacrylate (PEMA)26

Advantages:

  • Easily polished
  • Minimal exothermic heat increase (compared to PMMA)
  • Low shrinkage
  • Can be characterized
  • Easily repaired
  • Low cost
  • Moderate strength

Disadvantages:

  • Surface hardness (weaker than PMMA)
  • Strength
  • Durability
  • Fracture toughness
  • Unpleasant odor

Can be used in direct method for single crowns, or in the direct-indirect reline method

Bisacryl composite resin272829

Example: Luxatemp.

Advantages:

  • Low exothermic reaction
  • Minimal polymerization shrinkage
  • Ease of application via cartridge system
  • Can be smoothed or polished
  • Can be characterized

Disadvantages:

  • Brittle
  • Difficult to repair
  • Does not bond to polycarbonate crowns
  • High cost

Ideal for direct methods for single crowns

Light cured composite resin30

Advantages:

  • Controlled setting (light cured)
  • Highly aesthetic
  • Can be characterized
  • Easily polished and smoothed

Disadvantages:

  • Brittle
  • Transparent template required for light cure
  • Can be time consuming
  • High cost

Single unit restorations in the direct method. Can also be used to repair open margins in bisacryl composite crowns.

Clinical tip for repair

To repair an open margin on a bis-acryl temporary, it is best to first cement the temporary with temporary cement, remove any excess cement from the defect, and then add and cure flowable composite to seal the margin.

Can also be fabricated in the indirect method

Temporary cements31

Objectives

  • Provide adequate seal
  • Retain provisional restoration
  • Minimal solubility
  • Adequate handling and mixing
  • Adequate working and setting time
  • Cleansable
  • Biocompatible with pulp/gingiva
  • Compatible with restorative materials
  • Allows for restoration removal

Types32

  • Zinc-oxide eugenol cement
  • Eugenol free cement
  • Polycarboxylate cement (harder cement)
  • Tempbond clear (aesthetic)

Considerations33

  • Zinc-oxide eugenol cement is most commonly used
  • High strength cements should be avoided as it can cause damage during the removal of the temporary restoration.
    • Can be used when there is lack of retention in tooth preparation
    • Long span restorations
    • Parafunctional activities
  • Eugenol may act as a plasticizer of methacrylate resins
    • Thus could reduce bond strengths of permanent resin cements

Eugenol and resin cements

==The eugenol in traditional ZOE cements can act as a plasticizer and inhibit the polymerization of permanent resin cements. Therefore, a eugenol-free temporary cement should be used if the final restoration will be bonded with a resin cement.==

  • Thus can use eugenol free cements

Application procedure3435

  1. Mix the base and activator
  2. Apply a small quantity just short to the margin
    • A very thin layer should be applied to the internal surfaces of the crown.
  3. Seat the crown and hold tightly (or ask patient to bite over a cotton roll)
  4. Remove the excess with an explorer and dental floss
    • ==This should be done once the cement reaches a rubbery or partially set stage. Pass dental floss through the interproximal contacts before the cement fully sets to clear the embrasure spaces.==
  5. Make sure no cement is left in the gingival sulcus
  6. Occlusion should be checked and adjusted after cementation

Info

The slight thickness of the cement layer may make the crown slightly high, requiring minor occlusal adjustment.

Footnotes

  1. Original PDF page 3: F3 Temporization, p.3 ↩

  2. Original PDF page 4: F3 Temporization, p.4 ↩

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  30. Original PDF page 33: F3 Temporization, p.33 ↩

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  35. Original PDF page 38: F3 Temporization, p.38 ↩

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