Operative materials Flashcards
What is the objective of cavity bases? (2)
- Replace lost tissues.
2. Avoid problems due to the treatment technique and complications from final restoration material behavior
What materials are used for cavity bases? (3)
- GIC
- eugenol cements, biodentin
- adhesives
+ composite resins
Whats the principal component of GIC?
Polyalkenoic acids
*bond calcium and phosphate of the tooth
GIC and adhesive?
not needed because it bonds chemically
What are the main components of GIC?
- Polyalkenoic acids
- water (50%)
- tartaric acid
- glass particles
What is the acid of GIC? (4)
Polyalkenoic acids:
- AC polyacrylic, polymaleic acid and itaconic acid
What type of reaction does GIC have?
acid-base chemical reaction
What components are part of the glass particles of GIC? (4)
it is the BASE
- crystals of Si, Al and F (calcium flouride)
What is tartaric acid in GIC?
Setting accelerators
What does the water do in GIC?
setting essential
What are the other components of GIC?
Radiopacifiers
pigments
resin reinforcers
What is the radiopacer component of GIC?
Silver
Zn oxide
OR barium glass
What is the pigment component of GIC?
aesthetics
What are the resin reinforcers of GIC?
Metals (dissued)
Light & self cured resins
Why are there light and self cured resins in GIC?
- Improve the mechanical and esthetic properties.
- Protect from moisture and drying: less moisture-sensitive.
- Facilitate handling: Longer working time
How are GICs classified? (3)
- Conventional
- Hybrid
- Compomers
What is the conventional GIC?
- acid base reaction
- mixed with water
What is hybrid GIC? (2)
- 2 independent reaction settings
* GIC with resin - photo or light curing
What are the 2 independent reactions of GIC?
- acid / base (common to all GIC)
- Photo
What is compomer GIC?
Mainly resin with GIC added
- considered resins not cements
- higher photo resin content
GIC and acid susceptibility?
- conventional GIC
- predisposed to acid erosion because GIC is inorganic
- less acid suspectibility in resin-modified GIC
What is conventional GIC used as?
- cement
- provisional restoration
Conventional GIC and occlusal forces?
Don’t expose to occlusal forces because it will break
Why are resins added to GIC? (3)
- To achieve less curing time.
- Less sensitive to handle in the initial setting phase.
- Get a surface that chemically joins the composite resins.
Photo/self curing resin properties? (3)
➢Hema (10%)
➢Setting: two independent reactions
➢The main features of the GIC are not altered
Indications of conventional and resin modified GIC?
- Fissure sealant
- cavity base
- cement
- direct restoration material
- not on cavities that receive direct occlusal forces
Why do we use conventional/resin modified GIC as a cement? (4)
- good chemical adhesion (good sealing)
- F release
(anticariogenic and desensitizing) - good viscosity
- low thickness.
Why do we use conventional/resin modified GIC as a direct restoration material?
• Class V cavities with a lack of enamel in the cavity margin
- abfraction (modulus of elasticity similar to dentin).
• To fill areas with undercuts in big restorations, if it is going to hold indirect
restorations*
Why do we use conventional/resin modified GIC as a fissure sealant?
Better adhesion to enamel than composite resin
BUT it goes away so use flowable composite instead now
What is the presentation of hybrid GICs?
capsules
to spatulate
clickers
Whats the sandwich technqiue?
Tooth - GIC - composite
Whats equia fil & equia coat?
- New generation of high strength glass ionomer
- nano-filler with high F release
- excellent to replace amalgam and composite class I, II, V
- in peds or geriatrics
- not sticky and easy to handle
Zn eugenol cement cavity base properties?
- antiseptic
- pulp irritant
- not used because not compatible with composite resin
- poor resistance
- not aeshtetic
Why is zn eugenol not comptaible with composite resins?
Eugenol inhibits polymerization of resin materials
What is Zn eugenol used for?
Temporary fillings
stepwise caries removal
What is stepwise caries removal procedure?
- Clean almost all the caries but leave a bit
- Cover with CaOH, then obturate with zinc eugenol cement
- after 8 weeks - removal + caries removal
- Didnt need to clean remaining caries as deep as with one step.
- the odontoblasts protect the pulp from the injury
- this is the only time we use zinc eugenol in restorative
Biodentine composition?
Calcium silicate based product:
- tricalcium silicate: regulates setting
- calcium carbonate: filler
- zirconium dioxide: radiopacity
- calcium chloride: accelerator
- water soluble polymer: reduces viscosity
Biodentine uses? (4)
- indirect pulp capping
- direct pulp capping
- direct restorations in deep cavities
- inlay/onlay
Biodentine properties (5)
- has to be covered by composite or indirect restoration
- good to replace dentin
- capsule and liquid. put liquid in capsule (powder)
- can be put directly on pulp exposure.
- wait 12 minutes thats the time it takes to set
Biodentine in normal cavity?
to replace dentin and then covered by composite
Biodentine in indirect restoration?
base on the floor (build up) then take impression for indirect
Biodentine in pulp exposure?
put directly on pulp
Cavity base with adhesive and RC function (2)
- seal (adhesive)
- give shape to floor of cavity (RC)
Cavity base with adhesive +RC? (2)
- used directly over deep
cavities : Self etch adhesives to prevent pulp exposure
or creating an altered hybrid layer
(hybridoide layer).
-Place the
RC, compomer or reinforced GIC as
artificial dentin on top
What is the hybridiodie layer? (2)
- demineralized area (orthophosphoric acid) that is not penetrated
by the adhesive . - Brittle :pressure differences in the pulp = postoperative pain
Why do we use self etch in cavity base (Adhesion +RC)?
The problem with using etch is if its left too long, it creates deeper microretentions than the adhesive can penetrate.
What is a compomer?
Composite resin containing small amounts of GIC
What is a compomer composed of?
➢ Glass particles (Filler particles similar to the powder of GIC
calcium-fluoro-alumino-silicate glass)
➢Composite particles (SI , Sr, Ba sulfate )
➢Polyalkenoic acid (not in aqueous solution ) modified by Bis-GMA and UDMA
➢Pigments to enhance the aesthetic
Disadvantages of using compomers?
- Etching and bonding is mandatory.
- Less wear resistant than conventional composite.
- Insignificant release of fluoride.
Compomer indications?
- same as composite
- Direct restoration material.
- To build up a core in fixed prosthodontics.
Compomer technique? (2)
- Same as composite resins (etch and adhesive).
- Only light curing
Composition of composite resins? (7)
- Resin matrix(organic content)
- Fillers (inorganic part)
- Coupling agents (Silane- bonds glass fillers to matrix).
- Activation systems.
- Pigments.
- Radiopacifiers.
- Optical modifiers
What does the composite resin matrix consist of?
- mostly Bis-GMA
* the monomer is diluted with a varying range of other monomers of lower molecular weight.
Bis-GMA in composite resin matrix?
- viscous alone
- mixed in different combinations with short chain monomers (ex. TEGDMA)
Describe bisGMAs chemical structure
aromatic core and 2 reactive links where polymerization occurs
Composite resins: the higher the molecular weight…
the higher the viscosity ,
difficult to manipulate and incorporate inorganic filler
Composite resins: the lower the molecular weight…
the more polymerization shrinkage
Composite resins organic matrix: which monomers have higher molecular weight? properties?
Bis-GMA + UDMA
- contraction 5-6%
- worse handling
- difficult inorganic filler addition
Which monomers are low molecular weight? (5)
- viscosity regulators, dilutants
- BIS-MA
- EDGMA
- TEGDMA
- MMA (most commonly used)
- D3MA (most commonly used)
- most composite resins mix methacrylate monomers
What is the purpose of fillers in composite resin? (5)
- Responsible for resin composites final characteristics.
- Mechanical properties
- Polymerization shrinkage
- Surface roughness
- Optical properties
The filler content of a composite is sometimes determined by…
the shape of the
filler
Composite resins: What happens if we have high % of fillers ? (2)
- Better mechanical properties and reduced
polymerization shrinkage. - Smaller particles : > filler content.
Composite resin: viscosity depends on…
- fluidity of the monomer
- % of filler incorporated
Composite resin: If the filler content increases,
> viscosity of the mixture because.. (2)
- > friction between particles
2. > particle surface to be wetted by the resin
Composite resin: Surface roughness or polishing is better if…
> Filler
< Particles size
How much filler is in flowable composite ?
More matrix than filler = more fluid
What are the different filler particles?
- Glass silica: macroparticle
- Non-glass silica particle: microparticle
- Colloidal silica and ziconium oxide: nanoparticle
Describe macroparticle fillers: (3)
- glass silica
- conventional composite resins or macro-particle ( 10-80 microns)
- nowadays triturated (1-10 microns)
Describe microparticle fillers: (3)
- nonglass silica
- less abrasive
- 0.01-1 micron (avg 0.04)
Describe nanoparticle fillers: (3)
- colloidal silica (20nm) and zironcium oxide (4-10nm)
- joined: nano-clusters (0.6-20nm) allows more filler content
Which composite resin filler isnt used anymore? why (4)
- glass silica
- too strong would wear down organic matrix and expose filler
- would wear on antagonist tooth
- eventually detach from matrix and create grooves in obturation
When do we use microparticle? (2)
- Used to restore anterior tooth (class IV)
- Last layer of the buccal wall of the tooth
What is the purpose of silane coupling agents in RC?
to improve adhesion of the resin to filler surfaces
What are the components of systems initiating polymerization in RC? (3)
Activation systems-
- heat (benzoyl peroxide),
- chemical (benzoyl peroxide and aromatic
amine) - photochemical (camphoroquinone and tertiary amine)
What are the additives in RC? (4)
- Stabilizers
- Dyes
- Optical modifiers/Pigments : provide fluorescence and opalescence
- Radiopaque fillers
What are the different ways to classify RC? (5)
- Fillers size
- Viscosity
- Polymerization system
- Aesthetic properties
- Indications
What are the different ways to classify RC by filler size? (4)
- Macroparticle: Small particle: 1 – 10µ. 70-80% inorganic filler
weight. - Microparticle: average size 0,04 µ. Use: anterior teeth
• Homogeneous 30-40% microparticles SiO2: viscous, poor resistance, good polishing
• Heterogeneous : micro particle + agglomerated pre-polymerized micro particles mixed
with resin and triturated: higher filler content composite (60-80%) with better properties. - Hybrid
- Nanoparticle: Isolated particles 5 -20 nm. Cluster
(nanoparticles aglglomarated, 1µ),low viscosity, high translucency
Describe hybrid composites:
- Filler particles are a mix of sizes and shapes: particles max 5µ + microfilled particles between them.
- 80% inorganic filler weight
- Universal composites: Used in post and ant
Almost all hybrid composites on the market now are …
Nanohybrid
- include nanparticles and nano clusters
Describe nanohybrid resins: (3)
• By reducing the size of the particles and increasing the total surface to be
wet by the resin it should increase viscosity but it doesn’t, because
nanoparticles do not behave like a solid they behave more like a
liquid.
• To increase the amount of fillers, the manufacturers form agglomeration
of nanoparticles or nanoclusters (having a size of about 1 micron), to give viscosity, color, opacity and radiopacity.
* we can fit more filler and not affect viscosity negatively
• Nanofillers can be incorporated into other composites improving
their properties (resistance to tensile strength, abrasion, marginal stability and provides a very good polishing).
Describe nanohybrid composites:
• Universal composites: superior esthetic and wear characteristics,
high polish-ability, and superior handling characteristics.
• They correspond to most composite resins current’s presentation and they are an evolution of the microhybrid
Hows are RC classified by viscosity?
1. Flowable: Low viscosity. Indications: • Class V or I –small- • As a base in big cavities. • Bulkfill: nanofilled, low contraction monomers. 4mm polymerization (translucency).
- Conventional: Medium viscosity.
- Packable: High viscosity. Stiffer, thicker feel. Disused
How are RC classified by polymerization system?
- Self cured: Chemical initiation. Benzoyl peroxide
- Light cured: - Photoinitiators: Camphorquinone
(427-491 nm)
Fenilpropanodione 430 nm. - Dual cure: Chemical initiation. + light cured.
What factors influence polymerization? (8)
- time
- composite color
- temp
- thickness (<2mm)
- filler type
- distance between light and composite
- quality of light
- contraction - depends on organic phase
What is conversion degree? (2)
- % of double bonds that have reacted
- best case = 70%
*monomers reacted forming polymers
Higher degree of conversion means…
Clinical behaviour is better
How is RC classified by aesthetic properties?
- By translucency
• Very translucent: clear composite/almost transparent: Incisal edges.
• Translucent: As enamel.
• Medium opacity. Composite body as dentin.
• Opaque: As dentin.
• Opaquers: To hide defects. - By its optical effect: Fluorescence or
opalescence - By its use in the stratification technique:
• Dentin, enamel, effects, opaquers, dyes
Whats are tints in RC? (4)
- resins with intense colarants to increase final aesthetics of restoration
- objective: reproduce morphological or chromatic characterics (white spots, lines, cracks)
- minimal use - small quantities at subsurface location (because not as resistant)
*always as second last later of composite
Clinical considerations that influence in the
selection of a composite?
• Location of the cavity
1. Occlusal , interpoximal, classes IV , VI classes . : Composite with
high inorganic filler content.
2. Aesthetic anterior restorations : Good polishing , suitable opacity
and fluorescence (nanohybrids or nanoparticle).
3. Cervical restorations: good polishing and flexure.
*class V/cervical use flowable then cover with conventional/hybrid
• Teeth colour
Other materials:
-Opacifiers
- Tints
What is the main property of new resin composites?
low shrinkage direct composites
What are the new resins? (3)
- silorane
- organically modiifed ceramic
- bulk fill technique
Describe silorane
• Reaction of siloxane and oxirane molecules. Patented by 3M - ESPE.
• Stress compensation achieved by opening/expanding
oxirane rings during polymerization instead of
contracting
• Requires specific adhesive bonding resin with LS Bond (3M
ESPE).
*Not compatible with other resins.
• The volumetric shrinkage is 1.7%.
- Most conventional composites shrink 3%-5% .
- 40-50% less volumetric changes than conventional ones.
Silorane mechanism (3)
Starts with the opening of the ring systems.
- Gains space and counteracts the loss of volume which occurs when the chemical bonds are formed.
- Yields a reduced volumetric shrinkage.
Describe organically modified resin matrix with ceramic: (3)
• Consists of organic (polymers) and inorganic (ceramic glasses)
network = advantages of both.
• Polymerization shrinkage decreases.
• Conflicting studies according to wear resistance,
adaptation and adhesion forces
What are the different organically modified resin matrix with ceramic?
CeramX (dentsply)
- low shrinkage through
pre-polymerized Ormocer matrix.
Admira (Voco)
- indicated for all resto classes
- suitable for composite inlays
- packable, non-sticky,
- high polishability.
- Ideal in allergy prone patients with its low monomer release.
What is organically modified resin matrix with ceramic also called?
Ormocers (ORganically MOdifed CERamic)
What must be considered in bulk-fill technique?
1) Polymerization shrinkage.
2) Polymerization depth and light penetration.
3) Prolonged working time.
4) Ensure quick & easy access to the light.
What is in the bulkfill composite? (3)
- photoiniciator ivocerin: - allows 4mm layers+ short polymerization time (Added to lucerna and camforquinone)
- sensitivity light filter: allows long working time for correct handling
- stress reliever: less shrinkage
Describe bulkfill compsoite:
• Allows placement of posterior restorations in single increment.
• The stress reliever increases marginal integrity and decreases polymerization shrinkage
• The light-sensitivity filter provides longer
working time (won’t polymerize quickly under ambient light, it is
easier to place than conventional composite )
• Manufactured with a polymerization booster for fast curing of up to 4 mm in 10 seconds.
What are the “other composites”?
Fiber reinforced composite FRC
Describe FRC (6)
• Combination of conventional dental composite and glass
fibers: improve level of strength, flexibility., > resistance to
occlusal load.
• 1-2 mm glass fiber silane-coated to join the resin matrix.
• Contraction varies depending on fiber direction - supposed to lay parallel to surface when the material is
condensed inside the cavity.
• Used in block as dentin replacement, but must be
covered by conventional because behave badly on surface.
• Good resistance to occlusal forces (when covered).
• Improvement in fracture resistance of the teeth and restorations..
FRC brand?
GC everX posterior
