Interim Restorations

Question 1

What are the 6 uses of interim restorations?

Answer 1

ØEsthetics
ØFunction 
ØPrevent Sensitivity
ØDrifting 
ØTissue Health
ØDiagnostics

Question 2

• 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.
• Used to assist in determination of the therapeutic effectiveness of a specific treatment plan or the form and function of the planned definitive prosthesis.
• Essential to Fixed Prosthodontic treatment since restorations are fabricated indirectly in the laboratory.

Answer 2

Interim restoration

Question 3

What are the 7 biomechanical requirements of interim restorations?

Answer 3

• Pulpal protection
• Positional stability
• Occlusal function
• Cleansability
• Marginal integrity
• Strength and retention
• Esthetics / Phonetics

Question 4

T/F: A provisional will prevent lateral drifting of the prepared and/or adjacent teeth

Answer 4

True

Question 5

Do you want a convex or concave emergence profile on the margin of interim restorations?

Answer 5

Concave

Question 6

While in a ______ state, the mixed resin fills the cavity formed by a mold, and then solidifies producing a rigid restoration.

Answer 6

fluid

Question 7

ØCustom direct interim crown is removed from the matrix, and then shaped and polished.

Answer 7

Direct Technique

Question 8

_____ mold: one part forms external contour of crown or FPD; the other forms the internal or tooth / tissue-contacting surface.

Answer 8

•Two-part mold

Question 9

\_\_\_\_\_\_ form
•Pre-fabricated (preformed) crowns
•Single crowns only
•Custom-fabricated molds
•Single or multiple unit restorations

Answer 9

External surface form

Question 10

\_\_\_\_\_\_ crown forms
•Aluminum or tin-silver
•Nickel-chrome or stainless steel
•Polycarbonate shells
•Cellulose acetate shells
•VLC moldable composite crowns

Answer 10

ØPrefabricated crown forms

Question 11

_______ Crown Forms

1) Limited to single units
2) Must be lined with auto polymerizing resin
3) Considerable modification (internal relief, axial recontouring, occlusal adjustment) may be required
4) Can manipulate resin to prevent “locking in”
5) First-visit emergency when crown is missing.

Answer 11

Pre-fabricated crown forms

Question 12

_____ molded crown

1) Less time consuming
2) Must be used for multiple units (FPD)
3) Improved contours and esthetics
4) Simulates planned restoration (when used in combination with diagnostic waxing).

Answer 12

Custom molded crown

Question 13

______ technique
•Made intra-orally directly on patient
1)Convenience
2)Time required for fabrication –routine restorations

Answer 13

Direct Technique

Question 14

______ technique
•Made in laboratory on a cast of the prepared teeth
1)Patient comfort / allergies
2)Presence of multiple undercuts
3)Long span FPD or multiple units
4)Indirect Provisionals can be fabricated in advance of the tooth preparation appointment; use of auxiliaries

Answer 14

Indirect Technique

Question 15

______ crown :
•Vacuum-formed matrix
•Silicone putty matrix
•Alginate or VPS impression

Answer 15

Custom molded crown

Question 16

____ polish:wetpumice / muslin wheel; dry tin oxide (Acrilustre) on muslin wheel

Answer 16

PMMA

Question 17

______ polish: rubber abrasives, polishing paste, or unfilled resin glaze

Answer 17

Bis-acryl resin

Question 18

The following are Desirable Properties and Characteristics of ________ for Interim Restorations

1) Convenient handling
2) Biocompatibility
3) Dimensional stability during polymerization
4) Ease of contouring and polishing
5) Flexural strength and abrasion resistance
6) Appearance (translucence; color; color stability)
7) Patient acceptance
8) Chemical compatibility with luting agents

Answer 18

Polymer Resins

Question 19

:1)Poly(methyl methacrylate) (PMMA)

2) Poly(R’ methacrylates) (R’ = ethyl, vinyl, isobutyl)
3) Powder / Liquid (chemically activated; “cold cure”)

Answer 19

ØAcrylic Resins

Question 20

1) Multifunctional dimethacrylate composite resins
i. Bis-GMA / Bis-EMA / Urethane dimethacrylate
2) Chemically-Activated
3) Dual-Activated (chemical / VL)
4) Visible Light-Activated

Answer 20

ØBis-Acryl Composite Resins:

Question 21

ØThe chemical conversion of monomer to a biologically inert polymer by chain reaction.
ØUnreacted free monomer is toxic(esp. MMA)
ØInadequate polymerization results in poor mechanical properties.
ØPolymerization reaction is exothermic, and there is shrinkage upon polymerization and cooling.

Answer 21

Free radical polymerization

Question 22

• ________: formation of a free radical by decomposition of an initiator(due to “activator ”)
• Benzoyl peroxide + 3o amine / heat (MMA)
• Camphoroquinone+ blue light-490nm (VLC composite)

Answer 22

Activation

Question 23

•Process of adding molecules in growing chain

Answer 23

Propagation(growth)

Question 24

• Growing chains randomly combine; stop growing

* Polymerization is completed

Answer 24

Termination

Question 25

:process of adding molecules in the growing chain •Physical properties of rigidity and strength develop •Setting material ↑density and exothermia, causing polymerization contraction. •↑ Temperature during propagation promotes: •greater polymerization and •removal of unconverted monomer •Composites: additional VLC ↑ polymerization, strength

Answer 25

Propagation

Question 26

* Growing chains randomly combine * Material becomes rigid –able to finish / polish (≈5 minutes) * Desirable to convert all free monomer to polymer before termination * (Does not COMPLETELY happen) * Composites: additional VLC ↑ polymerization, strength

Answer 26

Termination

Question 27

Properties associated with _______: •Chemical / allergic irritation •Physical properties of set material •Exothermic heat of reaction& volumetric shrinkage •Strength of mass •As MW (size) of monomer ↑(ethyl, isobutyl, etc.), exothermia, shrinkage, and strength ↓ •Composites: UDMA can affect resilience, toughness to counteract brittleness

Answer 27

MONOMER

Question 28

Properties associated with ______ (Powder): •Increase in filler content→ •Greater strength •Less exothermia and less shrinkage •Too much filler → poor handling •Composites: size / shape of particles affects density, strength, surface finish

Answer 28

POLYMER

Question 29

``` ØADVANTAGES •Good marginal fit •Good transverse strength •Polishes well •Durability / color stability ØDISADVANTAGES •Toxic monomer •High exothermia •High volumetric shrinkage(8%) •Low abrasion resistance ```

Answer 29

PMMA

Question 30

can generate temperatures of 70 oC or higher in the pulp chamber as material goes through polymerization. •Free monomer contact with tissues → chemical burns, allergic reactions. •Monomer vapor is harmful. A volumetric shrinkage of ~8%occurs on polymerization. •A 2% reduction in crown diameter results in a high marginal discrepancy. •Results when polymerization occurs off the tooth.

Answer 30

PMMA

Question 31

``` ADVANTAGES •Less exothermia •Less shrinkage ØDISADVANTAGES •Toxic monomer •Poor:•Surface hardness •Transverse strength •Durability •Fracture toughness •Color stability ```

Answer 31

Poly(R’methacrylate)

Question 32

``` ØADVANTAGES •Good marginal fit •Low exothermia •Low shrinkage •Good surface hardness and abrasion resistance •Good biocompatibility, color stability, and patient acceptance ØDISADVANTAGES •Limited polishability •Improved surface finish w/ resin glaze •No doughy/rubbery stage •↑ Cost•Brittleness ```

Answer 32

Bis-Acryl Resins

Question 33

* Time required for fabrication * Time the interim is required to function in the mouth•Materials available for fabrication * Management of deficiencies•Reline / modification / repair * Treatment of the fractured or defective surfaces * Grinding to expose fresh surfaces; removing enough to provide adequate thickness and ability to complete re-seating of restoration * Roughening / sandblasting / bonding agent * Composite –flowable composite resin

Answer 33

Bis-Acryl Resins

Question 34

______ cements (Temp Bond)•Low strength•Sedative (obtundant) and bactericidal•Inhibition of resin polymerization

Answer 34

Zinc Oxide –Eugenol

Question 35

_____ cement w/ plasticizers (Ultratemp) | •Low strength final cement

Answer 35

Polycarboxylate

Question 36

cement –modified (Smart Temp) | •Longer-term use

Answer 36

Glass ionomer-based

Question 37

______(modified low strength) (Te l i oCS Link) •Especially helpful for planned bonded-ceramic restorations •Translucent

Answer 37

Resin Cement

Question 38

•Equal amounts of base and catalyst are mixed together on a mixing pad.•The material is mixed with a small spatula until homogenous.•Mixing Syringe is also available

Answer 38

Provisional cementation