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Fixed Prostodontics > Interim Restorations > Flashcards

Interim Restorations Flashcards

1
Q

Use of Interim Restorations (6)

A

ØEsthetics
ØFunction
Ø Prevent Sensitivity
Ø Drifting
ØTissue Health
ØDiagnostics

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2
Q

Interim Restorations
•Definition:

A

• 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.

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3
Q

Interim Restorations
• Used to

A

• Used to assist in determination of the therapeutic
effectiveness of a specific treatment plan or the form and
function of the planned definitive prosthesis.

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4
Q

Interim Restorations
• Essential to Fixed Prosthodontic treatment since

A

restorations are fabricated indirectly in the laboratory.

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5
Q

• “Interim” or “provisional restoration”
• NOT “—-”

A

temporary

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6
Q

Interim Restorations
• Requirements:
(1)

A

• The same as for definitive
restorations, except for
longevity and sophistication of
color

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7
Q

Biomechanical Requirements:
(7)

A

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

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8
Q

Protect the Prepared Teeth
(5)

A

• Bacterial plaque and saliva
• Exposure to irritating and painful
stimuli
• Temperature changes; chemicals /
fluids
• Marginal leakage
• Abrasion or breakage of prepared tooth
surfaces

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9
Q

Positional Stability (Intra-arch /
Inter-arch)
(3)

A

• Proximal contacts
• Occlusal contacts
• Inter-abutment stability (FPD)

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10
Q

Positional Stability – Proximal Contact
• A provisional will prevent

A

lateral drifting of the prepared and/or adjacent teeth)

Tooth
migration
Inability to
seat final
crown
Excessive
contact
Excessive
adjustment

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11
Q

Open
proximal
contacts
(2)

A

Impaction of
food and
debris
Periodontal
inflammation/
bone loss

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12
Q

Inadequate
Occlusal contact
(Infra-occlusion)
(2)

A

Extrusion
Premature
occlusion on
crown

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13
Q

Proper
Occlusion

A

Mastication
Comfort
Positional
stability

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14
Q

Supraocclusion
(3)

A

Pain
Dislodgement
of the
provisional
Crack/
Breakage of
the provisional

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15
Q

Restore Masticatory Function and Occlusion (3)

A

• Centric occlusal contacts (anterior and posterior)
• Lateral and protrusive guidance where appropriate on anterior teeth.
• No contact in lateral and protrusive on posterior teeth.

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16
Q

Maintain Periodontal Health (4)

A

• Non-impinging margins
• Physiologic contours, emergence profiles, embrasures, and proximal
contact
• Smooth surface texture and finish
• Leads to optimum and predictable tissue health

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17
Q

• Fit:

A

as close to finish line of tooth as possible

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18
Q

• Contour:

A

smooth, undetectable with explorer; smooth surface finish

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19
Q

• Sealed to prevent

A

leakage and resultant pain / caries or dislodgement

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20
Q

Marginal Integrityr: undetectable with explorer
(3)

A

• Emergence Profile: flat or slightly concave – NOT convex bulge
• Rough, thick margin → plaque accumulation; gingival inflammation
• Hemorrhage complicates impressions, cementation

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21
Q

Strength and Retention
• Adequate thickness for strength
(2)

A

• Withstand forces without breaking or dislodgement
• Adequate tooth reduction is necessary

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22
Q

Strength and Retention
• Physical properties of dental materials
(2)

A

• Metal or resin
• PMMA vs Bisacryl Resin

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23
Q

Strength and Retention
• Adequate thickness for strength
(3)

A

• Withstand forces without breaking or dislodgement
• Adequate tooth reduction is necessary
• Connectors / pontic contours ↑ w/o gingival impingement

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24
Q

Strength and Retention
• Physical properties of dental materials
(2)

A

• Brittleness (fracture) – especially bis-acryl resins
• ↑ Wear

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25
Esthetics and Phonetics • Maintain phonetics through: (5)
• Proper tooth length, position, contours • Facial (lip) support • Proper tooth (pontic) form for appearance • Tooth shade compatible with remaining teeth • Preview of final restoration for patient acceptance
26
While in a fluid state, the mixed resin
fills the cavity formed by a mold, and then solidifies producing a rigid restoration.
27
Custom Interim – Direct Technique (4)
Molar is prepared for FGC. Resin injected into mold of unprepared tooth. Impression with resin re-seated onto prepared tooth; allowed to set. When removed, internal surface of provisional crown is seen
28
Custom Interim – Direct Technique
ØCustom direct interim crown is removed from the matrix, and then shaped and polished.
29
Interim Fabrication • Two-part mold:
one part forms external contour of crown or FPD; the other forms the internal or tooth / tissue-contacting surface.
30
external form (matrix)- internal form (tooth)-
custom.preformed direct/indirect technique
31
External Surface Form (2)
• Pre-fabricated (preformed) crowns -Single crowns only • Custom-fabricated molds -Single or multiple unit restorations
32
Technique of fabrication
• “Direct on tooth” versus “Indirect on cast”
33
Prefabricated crown forms (5)
• Aluminum or tin-silver • Nickel-chrome or stainless steel • Polycarbonate shells • Cellulose acetate shells • VLC moldable composite crowns
34
Custom molded crown or FPD forms: (3)
• Vacuum-formed matrix • Silicone putty matrix • Alginate or VPS impression
35
ØPre-fabricated Crown Forms (5)
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
36
ØCustom molded crown or FPD forms: (4)
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).
37
ØDirect Technique • Made
intra-orally directly on patient
38
ØIndirect Technique • Made
in laboratory on a cast of the prepared teeth
39
Direct Technique: indication (2)
1) Convenience 2) Time required for fabrication – routine restorations
40
ØIndirect Technique: indication (4)
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
41
Direct vs. Indirect Techniques • Combination Indirect-Direct technique
• Custom interim shell made in laboratory and relined intra-orally
42
Polymerization and Polishing Acrylic Resin (2)
• Warm water in pressure pot 20-25 psi (PMMA) • Increases polymerization; decreases porosity
43
• PMMA polish:
wet pumice / muslin wheel; dry tin oxide (Acrilustre) on muslin wheel
44
• Bis-acryl resin polish:
rubber abrasives, polishing paste, or unfilled resin glaze
45
The finish and polish must contribute to patient comfort and physiologic tissue health: (3)
• Tissue stabilization for esthetics • Final impression • Cementation of final restoration
46
Desirable Properties and Characteristics Polymer Resins for Interim Restorations (8)
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
47
Currently Available Materials ØAcrylic Resins: (3)
1) Poly(methyl methacrylate) (PMMA) 2) Poly(R’ methacrylates) (R’ = ethyl, vinyl, isobutyl) 3) Powder / Liquid (chemically activated; “cold cure”)
48
Currently Available Materials ØBis-Acryl Composite Resins: (4)
1) Multifunctional dimethacrylate composite resins i. Bis-GMA / Bis-EMA / Urethane dimethacrylate 2) Chemically-Activated 3) Dual-Activated (chemical / VL) 4) Visible Light-Activated
49
Free Radical Polymerization
ØThe chemical conversion of monomer to a biologically inert polymer by chain reaction.
50
ØUnreacted free monomer is
toxic (esp. MMA)
51
ØInadequate polymerization results in poor --- properties.
mechanical
52
Polymerization reaction is ---, and there is --- upon polymerization and cooling.
exothermic shrinkage
53
ØInitiation (2)
• Activation: • Free radical combines with monomer
54
• Activation: (3)
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)
55
Propagation (growth)
• Process of adding molecules in growing chain
56
Termination (2)
• Growing chains randomly combine; stop growing • Polymerization is completed
57
ØPropagation: process of adding molecules in the growing chain • Physical properties of (2) develop
rigidity and strength
58
• Setting material --- density and exothermia, causing
↑ polymerization contraction.
59
↑ Temperature during propagation promotes: (2)
• greater polymerization and • removal of unconverted monomer
60
Composites: additional (2)
VLC ↑ polymerization, strength
61
Termination • Growing chains randomly combine • Material becomes rigid – able to finish / polish (≈--- minutes)
5
62
Desirable to convert all free monomer to polymer before termination (2)
• (Does not COMPLETELY happen) • Composites: additional VLC ↑ polymerization, strength
63
• Inhibition: (3)
Reaction with eugenol, oxygen, hydroquinone will cause termination. • Where would contact with eugenol occur? • “Oxygen inhibited layer”?
64
Properties associated with MONOMER: (2)
• Chemical / allergic irritation • Physical properties of set material
65
Properties associated with MONOMER: • Chemical / allergic irritation • Physical properties of set material (4)
• 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
66
ØProperties associated with POLYMER (Powder): (3)
• Increase in filler content → • Too much filler → • Composites: size / shape of particles affects density, strength, surface finish
67
• Increase in filler content → (2)
- Greater strength - Less exothermia and less shrinkage
68
• Too much filler →
poor handling
69
Poly(methyl methacrylate) – PMMA ØADVANTAGES (4)
• Good marginal fit • Good transverse strength • Polishes well • Durability / color stability
70
Poly(methyl methacrylate) – PMMA Ø DISADVANTAGES (4)
• Toxic monomer • High exothermia • High volumetric shrinkage (8%) • Low abrasion resistance
71
Problems with PMMA (6)
• PMMA can generate temperatures of 70oC 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.
72
Poly(R’ methacrylate) – not used at UMKC (R’=ethyl, vinylethyl, isobutyl, etc. – Trim, Snap) ØADVANTAGES (2)
• Less exothermia • Less shrinkage
73
Poly(R’ methacrylate) – not used at UMKC (R’=ethyl, vinylethyl, isobutyl, etc. – Trim, Snap) Ø DISADVANTAGES (6)
• Toxic monomer • Poor: • Surface hardness • Transverse strength • Durability • Fracture toughness • Color stability
74
Bis-Acryl Resins (Composite) ØADVANTAGES (5)
• Good marginal fit • Low exothermia • Low shrinkage • Good surface hardness and abrasion resistance • Good biocompatibility, color stability, and patient acceptance
75
Bis-Acryl Resins (Composite) Ø DISADVANTAGES (4)
• Limited polishability - Improved surface finish w/ resin glaze • No doughy/rubbery stage • ↑ Cost • Brittleness
76
Problems associated with Interim Restorations (3)
• Time required for fabrication • Time the interim is required to function in the mouth • Materials available for fabrication
77
Problems associated with Interim Restorations • Management of deficiencies (2)
• Reline / modification / repair • Treatment of the fractured or defective surfaces
78
• Treatment of the fractured or defective surfaces (3)
• Grinding to expose fresh surfaces; removing enough to provide adequate thickness and ability to complete reseating of restoration • Roughening / sandblasting / bonding agent • Composite – flowable composite resin
79
cements: • Zinc Oxide – Eugenol cements (Temp Bond) (3)
• Low strength • Sedative (obtundant) and bactericidal • Inhibition of resin polymerization
80
• Non-eugenol cements: (3)
• Polycarboxylate cement w/ plasticizers (Ultratemp) • Glass ionomer-based cement – modified (Smart Temp) • Resin Cement (modified low strength) (Telio CS Link)
81
Polycarboxylate cement w/ plasticizers (Ultratemp)
• Low strength final cement
82
Glass ionomer-based cement – modified (Smart Temp)
• Longer-term use
83
Resin Cement (modified low strength) (Telio CS Link) (2)
• Especially helpful for planned bonded-ceramic restorations • Translucent
84
Provisional Cementation (2)
• 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

Fixed Prostodontics (19 decks)

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