Outcome 4 - Composite Flashcards
Organic definition
Derived from an animal or plant source
Inorganic definition
Compounds that are not derived from a living source, usually from a mineral source
Resin definition
A soft organic compound, usually an exudate from a plant source
Polymerization definition
To cause a simple resin to change into another form, usually one that has a stronger molecular structure, thus hardening the material
Photo polymerization definition
Polymerization caused by an exposure to a concentrated light source
Auto polymerization definition
Polymerization caused by chemical reaction
Micro-mechanical retention definition
a material locking into a structure through microscopic voids or tags
Chemical adhesion definition
Materials creating a molecular bond to each other during polymerization process, for example, layers of composite resin restorative material will chemically adhere to each other and become one solid mass
Pros of Composite Resin
-esthetically pleasing
-able to withstand the oral environment
-sufficient strength to withstand occlusal forces
(not as strong as amalgam or gold but often that superior strength is not necessary)
The components of composite resin include:
-Organic Resin Matrix
-Inoranic Filler Particles
-Coupling Agent
-Pigments
What is the Organic Resin Matrix?
a material called BIS-GMA, compromised of demethacryate with additives to allow polymerization, is the main component of the resin matrix
BIS-GMA is a viscous liquid that is not strong enough to be used on its own as a restorative material
What is the purpose Inorganic Filler Particles?
These particles add the strength, body, and light reflection qualities necessary to transform BIS-GMA into a restorative material.
What are the most common fillers in Composite?
Common fillers are quartz, glass, and silica
How much filler in Composite?
The amount of filler present in the composite restorative material as well as the size of filler particles vary from product to product
How are Composites classified?
Classified by particle size and percentage of filler particles in the total product.
Macrofilled
Microfilled
Hybrid
Flowable
Sealant
What is a Macrofilled composite?
Contain the largest inorganic filler particles and are of superior strength
What is Microfilled composite?
Contain the smallest inorganic filler particles and have superior esthetics with excellent smoothness and light reflection qualities.
What is Hybrid composite?
Most often used today.
Contain a mixed range of particle sizes and have a high wear resistance and excellent shading capabilities
What is Flowable Composite?
Are supplied as a hybrid or nanofilled composite with enough filler to make them wear resistant. Material is designed to flow into more conservative preparations.
What are sealant composites?
Resemble flowable composites
Require no preparation with the handpiece or hand cutting instruments. They are applied to the etched enamel surface
What is the Coupling Agent in Composite resin?
This additive is necessary to bond the filler particles to the resin matrix to prevent settling. The filler particles are coated with an organosilane compound, simply referred to as silane. The organic portion bonds the resin matrix and the silane portion bonds with the inorganic fillers, holding all components together.
What are the Pigments in Composite resin?
Composite resins are designed to blend with tooth strucutre. Manufactures add pigments to match various tooth colours, ususally from an inorganic substance.
Biocompatibility of Composite Resin
There is no controversy regarding the biocompatibility of the material, as it contains no hazardous components.
Is Composite Resin Mechanically Stable and Durable?
Although not as strong as a metal restoration, advances in the chemical composition of the material, as well as cavity preparation and placement techniques have enabled dentists to use composite resin in a large variety of restorative situations.
Is Composite Resin resistant to corrosion and chemicals?
Composite resin is basiclaly a plastic material, so it is resistant to corrosion and deterioration in the moist and acidic oral environment.
Is Composite Resin dimensionally stable?
The composite resin material has an expansion and contraction factor that is more simmilar to tooth structure than amalgam.
There is still some concerns with excessive contraction of the restoration in cold environments, but ongoing research into manipulation of the chemical composition of the material and compatible bonding materials is reducing the microleakage factor.
Does Composite Resin have minimal thermal and electrical conductivity?
The thermal conductivity of composite resin is less than that of metal restorations, but the placement technique must be very precise. Variations from the recommended restorative protocol can lead post-placement sensitivity, even though the material does not readily conduct thermal sensation.
Is Composite Resin Esthetically pleasing?
- is available in a wide variety of shades
- the shade guide that accompanies the material enables the dental team to match the restoration to the surrounding tooth structure very closely. Finishing and polishing procedures can also create luster and light reflection similar to that of enamel.
Is Composite Resin Easy to Manipulate?
Is supplied as a paste that can easily conform to the contours of a cavity preparation. There are two methods of hardening the material after placement: either by chemical reaction or exposure to a hand-held light. The contouring, finishing and polishing procedures vary with differeny brands and operators, but time and cost are usually reasonable.
Does Composite Resin Adhere to Tooth Tissues?
There are many bonding techniques available to allow composite resin restorations to adhere to the remaining tooth structure. This remains one of the main advantages of this material.
Is Composite Resin Tasteless and Odorless?
Is tasteless and not at all unpleasant in the oral environment. It is smooth and easily cleaned by the patient.
Is Composite Resin Easy to Repair and Clean?
Repair of fractured restorations is possible in some cases by adding material
Is Composite resin Cost Effective?
The placement cost of a composite resin retoration is higher than that of an amalgam restoration. This is due to the material cost, longer chair time required or placement and cost of finishing and polishing materials not required in amalgam dentistry. Most patients will still find the composite resin restoration within their budget, but others may opt for amalgam in posterior situtations for financial reasons.
The two methods for achieving polymerization are:
light curing (photo-polymerization) or auto-curing (auto-polymerization)
What does light curing involve?
Exposure of the composite resin to a high intesity blue light. The blue wavelength of light is most effective for polymerization and is created by a combination of halogen light and a tungesten refraction device
What does Auto-curing involve?
involves mixing catalyst and base materials to initiate a chemical reaction
How long to light-cure composit resin?
The exact exposure time for complete polymerization depends on the manufacturer’s directions, the thickness of each layer of composite being placed and the shade of the material. Most manufacturers recommend between 20 and 60 seconds of exposure per layer. If the dentist places a layer of material thicker than that recommended, the light exposure time will need to be increased.
Does darker shades of composite resin require more or less light curing time?
Darker shades of composite require longer curing times to allow the light to fully penetrate the material.
When are auto-polymerized materials recommended?
Auto-polymerized materials are recommended when it’s unclear if the light will be able to fully reach all aspects of the restoration.
What is Acid Etch or Tooth Conditioner
Acid etch or tooth conditioner is a material composed of 10-37% phosphoric acid. It is supplied as either a gel or a liquid. The acid dissolves the mineral component of the tooth structure on a microscopic level to create tags and pores into which bonding materials can flow. The tags and pores create micro- mechanical retention for the composite resin restorations.
What is a Bonding Resin?
Placed after acid etch and primer. May also be called adhesive or unfilled resin, as it is almost pure BIS-GMA. The bonding resin is thicker and more viscous than the primer, so it would have difficulty flowing into the microscopic pores and tages. The bonding resin is attracted to the primer and so is pulled more deeply into the etched surface than if the primer was not used. One layer is usually all that is necessary
Does composite bonding systems require curing?
Some bonding systems require light curing after the placement of bonding resin, while others utilize a chemical-cure reaction by mixing base and catalyst resins.
Placement of Composite Resin
The BIS-GMA in the composite will molecularly bond to the BIS-GMA of the adhesive resin, so the composite is held into the tooth preparation by micro-mechanical retention.
