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dental materials > restorative resin > Flashcards

restorative resin Flashcards

1
Q

used to restore and replace dental tissue lost through disease or trauma and to lute and cement crowns and veneers and other indirectly made or prefabricated dental devices

A

Dental resin-based composites

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2
Q

Dental resin-based composites three major components

A

a highly cross-linked polymeric matrix reinforced by a dispersion of glass, mineral, or resin filler particles
and/or short fibers bound to the matrix by coupling agents.

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3
Q

Dental resin-based composites compositions

A
  1. Resin matrix
  2. Fillers
  3. Coupling agents
  4. Activator-initiator system
  5. Inhibitors
  6. Optical modifiers
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4
Q

Based on a blend of aromatic and/or aliphatic dimethacrylate monomers such as:
* Bis-GMA (bisphenol-A glycidyl dimethacrylate)
* Urethane dimethacrylate (UEDMA)
* Triethylene glycol di-metacrylate(TEGDMA)

A

RESIN MATRIX

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5
Q

are employed to strengthen and reinforce composites as well as to reduce curing shrinkage and thermal expansion

A

Fillers

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6
Q

very hard, abrasive to opposing teeth or restorations, difficult to grind into very fine particles; thus, it is also difficult to polish

A

QUARTZ

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7
Q

not as hard thus, reducing the abrasiveness of the composite surface structure and improving its polishability

A

AMORPHOUS SILICA

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8
Q

provided by glasses and ceramics that contains heavy metals such as barium (Ba), strontium(Sr), and zirconium(Zr)

A

Radiopacity

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9
Q

Glasses and quartz provides

A

translucency

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10
Q

FUNCTIONS of FILLER PARTICLES

A
  1. Reinforcement
  2. Reduction of polymerization shrinkage/contraction
  3. Reduction in thermal expansion and contraction.
  4. Control of workability/viscosity.
  5. Decreased water sorption.
  6. Imparting radiopacity
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11
Q
  • Bonds filler particles to resin matrix
    • This allows the more flexible polymer matrix to transfer stresses to the higher-modulus (more rigid and stiffer) filler particles.
A

COUPLING AGENT

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12
Q

most commonly used coupling agent

A

Organosilanes (γ-methacryloxypropyl trimethoxysilane)

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13
Q

monomethacrylate and dimethacrylate monomers polymerize by the addition polymerization

A

ACTIVATION/INITIATION SYSTEM

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14
Q

Activator – UV light, visible blue-light
Initiator - Camphorquinone

A

LIGHT ACTIVATED RESIN

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15
Q

Activator - tertiary amine(N,N-dimethyl-p-toluidine)
Initiator - benzoyl peroxide

A

CHEMICALLY ACTIVATED RESIN

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16
Q

First composites were cured by

A

cold curing

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17
Q

○ Allows operator to complete both insertion and contouring before curing initiated
○ Not as sensitive to oxygen inhibition

A

ADVANTAGES of curing

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18
Q

FACTORS INVOLVED IN PHOTOCURING

A
  1. CURING LAMPS (LED, QTH, PAC, AL)
  2. DEPTH OF CURE AND EXPOSURE TIME
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19
Q

○ Have to be placed incrementally(2mm)
○ Tendency to shrink towards light source
○ Hand-held devices contains short-rigid light guide

A

LIMITATIONS of photocuring

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20
Q
  • They are formulated to set up very slowly when mixed via the self-cure mechanism. The cure is then accelerated on “command” via lightcuring promoted by the amine/ CQ combination.
    • are intended for any situation that does not allow sufficient light penetration to produce adequate monomer conversion—for example, cementation of bulky ceramic inlays.
A

DUAL-CURED RESIN

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21
Q

added to resin systems to minimize or prevent spontaneous or accidental polymerization of ○ monomers.
* Butylated hydroxytoluene (BHT)

A

INHIBITOR

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22
Q
  • To match the appearance of the teeth(visual coloration and translucency)
    • Metal oxides – Shading (pigments)
    • Titanium dioxide and aluminum oxide – increase opacity
A

OPTICAL MODIFIERS

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23
Q

IMPORTANT PROPERTIES OF COMPOSITES (10)

A
  1. Low polymerization shrinkage
  2. Low water sorption
  3. Coefficient of thermal expansion similar to tooth structure
  4. High fracture resistance
  5. High wear resistance
  6. High radiopacity
  7. High bond strength to enamel and dentin
  8. Good color match to tooth structure
  9. Ease of manipulation
  10. Ease of finishing and polishing
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24
Q

CLASSIFICATION OF RESIN-BASED COMPOSITE

A

Based on filler particle:
* Macrofilled / Conventional
* Microfilled
* Small particle-filled
* Hybrid
* Nanofilled
Based on Manipulation:
* Flowable
* Condensable (Packable)

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25
Q
  • Developed during 1970s
    • Ground quartz as filler material
    • Size: 10 – 100 µm
    • Filler loading: 70–80 wt% or 60-65vol%
A

Macrofilled Composite / Traditional / Conventional

26
Q

properties of Macrofilled Composite / Traditional / Conventional

A
  • ↑ Compressive strength
    • ↑ modulus of elasticity
    • ↑ tensile strength
    • ↓ water sorption
    • Polymerization shrinkage approximately 2vol%
    • ↓ thermal expansion
    • ↑ Hardness
      * radiolucent
27
Q

rough surface, tendency to discolor, poor resistance to occlusal wear, does not bond chemically to tooth structure
* Class II (stress bearing restorations)

A

Clinical disadvantage of Macrofilled Composite / Traditional / Conventional

28
Q
  • Colloidal silica as inorganic filler
    • Size: 0.01 – 0.1µm
    • Concept entails reinforcement of the resin by means of filler, yet this composite exhibit a smooth surface similar to that obtained with unfilled direct-filling acrylic resin
    • Physical and mechanical properties are inferior to traditional composites
      Filler loading: 50wt% or 30-40vol%
A

Microfilled Composite

29
Q

properties of Microfilled Composite

A
  • ↑ water sorption
    • ↑ coefficient of thermal expansion
    • ↓ elastic modulus
    • Weak bond between prepolymerized particles to resin
    • ↓ tensile strength
    • Wear resistant
      * Smoother finish
30
Q
  • Preferred for restoring smooth surface caries(CIII & CV)
    • ↑ chipping on stress bearing areas
    • For aesthetic restoration of anterior teeth, non stress bearing areas, subgingival areas
A

Clinical considerations of Microfilled Composite

31
Q
  • Developed to an attempt to achieve the surface smoothness of microfilled and yet retain or improve on the physical and mechanical properties of traditional restoration
    • Size: 0.1- 10µm
    • Filler loading 80wt% or 60-65vol%
      * Quartz or glasses that contains heavy metals as fillers
      * Most superior physical and mechanical properties
A

Small Particle-filled Composites

32
Q

properties of Small Particle-filled Composites

A
  • ↑ compressive strength and elastic modulus
    • ↑ Tensile strength
    • Coefficient of thermal expansion is lesser than other composite
    • Improved surface smoothness and wear resistance
    • Radiopaque
33
Q

formulated with mixed filler systems containing both microfine (0.01 to 0.1 μm) and fine (0.1 to 10 μm) particle fillers in an effort to obtain even better surface smoothness than that provided by the small particle composites while still maintaining the desirable mechanical properties.

A

Hybrid Composites

34
Q

Indicated for class 1and 2 sites (stress bearing) and anterior restorations (class 3 & 4)

A

Small Particle-filled Composites clinical considerations

35
Q
  • 2 kinds of filler particles:
    ○ Colloidal silica
    ○ Glasses containing heavy metals
    • Filler loading: 75-80wt%
    • Size: 0.4 – 1.0 µm(glasses)
    • Superior physical and mechanical properties than traditional and small particle-filled composite
    • Exhibit a smooth “patina-like” surface texture
      * Radiopaque
A

properties of Hybrid Composites

36
Q

○ Stress-bearing restorations
○ Anterior restorations

A

Clinical Considerations of Hybrid Composites

37
Q
  • Size: 0.005-0.1µm
    • Good physical properties and improved esthetics
    • Highly polishable
A

Nanofill Composites

38
Q
  • derived from the inclusion of elongated, fibrous filler particles (100μm) that causes the uncured resin to be stiff and resistant to slumping yet moldable under the force of amalgam condensers (“pluggers”).
    • More viscous to afford a “feel” of insertion
    • Class I, II(MOD), VI
    • High depth of cure
    • Low polymerization shrinkage
    • Radiopacity
      * Low wear rate
A

Condensable (Packable) Composite

39
Q
  • modification of the small-particle composite and hybrid composite
    • low viscosity a reduced filler loading
    • Cervical lesions, pediatric restorations, pit and fissure sealant
    • Low modulus of elasticity
    • High polymerization shrinkage
      * Low wear resistance
40
Q
  • Composites with glass ionomer components
    • Light-cured
    • Superior physical characteristics to glass ionomers but inferior to composites
      * Release fluoride
41
Q

MANIPULATION of composites

A
  1. Etching
  2. Rinsing and drying
  3. Bonding
  4. Curing
  5. Pulpal protection
  6. Insertion of Composites
  7. Curing
  8. Finishing and polishing
42
Q
  • Whenever both enamel and dentin tissues are mechanically cut, especially with a rotary instrument, a layer of adherent grinding debris and organic film known as a ______ is left on their surfaces and prevents strong bonding.
A

SMEAR LAYER

43
Q
  • Dr. Michael Buonocore (1955)
    • 30%-50% Phosphoric acid (37% most common)
      ○ removes the smear layer and about 10 microns of enamel to expose enamel rods to create a honeycomb-like, high energy retentive surface
    • Dissolution of enamel/dentin results to microporosities
A

ENAMEL ETCHING

44
Q
  • 1979 , Fusayama introduced the total-etch concept wherein both dentin and enamel are etched simultaneously.
    • It substantially increased the retention of the restoration while not damaging the pulp.
      * exposes a microporous network of collagen fibers suspended in water.
A

DENTIN ETCHING

45
Q
  • Etched dentin must be ___ to form a hybrid layer.
    • If insufficient water is present, the collagen network will collapse and produce a relatively impermeable layer that prevents resin infiltration and subsequent hybridization
      * If too much water remains resin infiltration cannot fully replace the water in the collagen network and, consequently, sets the condition for later leakage into those location
46
Q

ETCHING TIME :
RINSING:
DRYING:

A

15 – 20 SECS
20 SECS thoroughly with a stream of water
* Enamel must be dried completely with warm air until it takes on a white, frosted appearance.
* Dentin, in contrast, cannot withstand such aggressive drying. In the total-etch technique, a dentin bonding agent and primer must be used that are compatible with both moist dentin and moist enamel

47
Q

If contamination occurs, the surface should be etched again for 10 SECS

A

TRUE. ETCHED SURFACES MUST BE KEPT CLEAN

48
Q

FACTORS THAT AFFECTS ADHESIVE BONDS

A
  1. Surface energy and wetting
  2. Interpenetration (formation of a hybrid zone)
  3. Micromechanical interlocking
  4. Chemical bonding
49
Q
  • designed to provide a sufficiently strong interface between restorative composites and tooth structure to withstand mechanical forces and shrinkage stress.
A

DENTAL BONDING AGENTS

50
Q

2 TYPES OF BONDING

A
  1. Micromechanical interlocking, chemical bonding with enamel and dentin, or both
  2. Copolymerization with the resin matrix of composite materials
51
Q
  1. Adequate removal or dissolution of the smear layer from enamel and dentin
  2. Maintenance or reconstitution of the dentin collagen matrix
  3. Good wetting
  4. Efficient monomer diffusion and penetration
  5. Polymerization within tooth structure
  6. Copolymerization with the resin composite matrix
A

REQUIREMENTS of bonding

52
Q

DENTAL BONDING SYSTEM COMPOSITION:

A
  1. etchants
  2. resin monomers
  3. solvents
  4. initiators
  5. inhibitor
  6. Fillers
  7. sometimes other functional ingredients such as antimicrobial agents
53
Q

are solutions containing hydrophilic monomers dissolved in a solvent such as acetone, ethanol, or water.

54
Q

If a primer has the ability to both etch and prime, it is categorized as a

A

self-etching primer

55
Q

○ __ can ionize acidic monomers as well as re-expand the collapsed collagen network
○ __ and __ have better miscibility with relatively hydrophobic monomers, and their “water-chasing” ability facilitates water removal

A

water
ethanol and acetone

56
Q

fill the interfibrillar space of the collagen network, creating a hybrid layer and resin tags to provide micromechanical retention upon polymerization.
* __ layers also should prevent fluid leakage along the restorative material’s margin
* It must be HYDROPHOBIC so that fluid will not be allowed to permeate through the intermediate layer
* But also be HYDROPHILLIC, to diffuse into the hydrophilic, primer wetted dentin

57
Q

Similar initiator systems are used in both adhesives and restorative composites

58
Q

POLIMERIZATION CAN BE INITIATED BY:
○ ________: photosensitizer (camphorquinone) and initiator (tertiary amine)
○ ____: chemical initiator (benzoyl peroxide)
○ ____

A

Photoinitiator system
self-cure system
dualcure initiator system

59
Q
  • Silica particles (40 nm)
    • functions of silica particles (2)
A

filler particles
1. To produce higher bond strength
2. To modify adhesive viscosity to a thicker, pastier consistency that prevents oxygen inhibition, thus promote bond strength, and reduce shrinkage stress

60
Q

OTHER INGREDIENTS
* ___ – desensitizer
* __ and __ are used as antimicrobials
* __ - prevent secondary caries
* __ and __ - prevent collagen degradation

A

GLUTARALDEHYDE
MDPB and parabene
Fluoride
Benzalkonium chloride and chlorhexidine

61
Q

CLASSIFICATIONS OF CURRENT BONDING SYSTEM

A
  • Etch-and-Rinse Adhesives
    • Self-etch adhesives

dental materials (7 decks)

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