Reading: Intro to Composites Flashcards
Components of Silicate Cement
Acid-Soluble Glasses
Liquid contains: phosphoric acid, water, and buffering agent
Silicate Cement was recommended for…
1.
2.
- Small restorations in anterior teeth
- high caries activity
Average lifespan of silicate cement
4 yrs
How to tell if silicate cement is failing
- Discoloration
- Loss of contour
- Roughened Glass texture
_______ = rate of dimensional change of a material/unit change in temperature
Linear Coefficient of Thermal Expansion
If the linear coefficient of themal expansion ~~ LCTE of enamel
??? —higher/lower chance for creating voids at the jxn. of the material and tooth structure once temperatures change.
LOWER
TERM – the amount of water that a material absorbs over time per unit of surface area of water.
(H2O/Time)/Volume
Water Sorption
Materials with a higher filler content exhibit ____ water absorption values than materials with lower filler content
LOWER
TERM – refers to a material’s ability to resist surface loss as a result of abrasive contact with opposingtooth structure, restorative material, food boli, and toothbrush bristles.
Wear Resistance
Filler particle _____, ______, & _____ affect the potential wear of composites and other restorative materials
Size
Shape
Content
True or False?
The location of the restoration in the dental arch and occlusal contact relationships affect potential wear of materials
TRUE
The smoothness of the surface of the restorative material is especially needed with restorations near the ______ for good health
Gingiva
What two things of the filler determine the smoothness of the restoration and abiltity to be finished and polished?
- Size
- Composition
What type of composites are BEST for providing surface textures that are polishable, esthetic, and compatible with soft tissues?
- Nanohybrid
- Nanofill
Because of ________ fillers in composite materials, the restorations are radiopaque in radiographs
Barium
When viewing a radiograph–
Caries will be?
Composite will be?
Radiolucent
Radiopaque
Why must composites appear radiopaque-like on a radiograph?
To distinguish between carious lesions which are non-radiopaque!
When referring to the stiffness of a composite material—
The _____ the modulus of elasticity, the more rigid the composite material will be.
Higher
(and vice versa)
What microfill composite is best for a Class V restoration?
- Rigid Hybrid
- More Flexible Hybrid
More flexible hybrid
What can be used to potentially protecy the bonding interface from polymerization shrinkage effects
Stress breaking liners (with lower elastic modulus)
Although polymerization shrinkage cannot be avoided, you should use careful with –
1.
2.
- amount of material
- Intsertion point of the material
True or False?
Shrinkage does not usually affect preparations having all-enamel margins
True
True or False?
Shrinkage can result in a gap formation at the junction of the composite and root surface?
True
Force of composite polymerization >> initial bond strength of composite to dentin of the root
When placing a restoration on the root surface, what material should be used first if at all possible?
RMGI – release of fluoride
The ______ the C factor is, the greater the potential for bond distruption from polymerizing effects
HIGHER
What does C-Factor stand for
(# bonded surfaces)/ (#unbonded or free surfaces)
Internal stresses can be reduced by
- Soft-start or high intensity light?
- Incremental or bulk fill?
- RMGI and flowable or no liner?
- Soft-start polymerization
- Incremental
- Yes- use a stress breaking liner such as flowable composite or RMGI
If you INCREASE the amount of filler you will ________ the amount of shrinkage
DECREASE
Self - Cure Composite Properties (NO LIGHT OF ANY KIND)
- Mixture: _____&_____
- Mixing causes the risk for _____ ______ to occur
- Is working time restricted?
- Color Stability is lower or higher?
- Direction of shrinkage is where?
- Catalyst and Base
- Air Inclusions
- YES- also limits the finishing time before it sets
- Lower because of poor stability of tertiary amines
- Centralized towards center of mass
Light-Cured Composite Properties (VISIBLE light)
- Is working time increased or decreased?
- Is the color stability increased?
- Internal Porosity?
- Increased working time
- Color stability is increased
- LESS internal porosity
Plasma Arc Systems Properties (LED light)
- Is heat generation an issue?
- Is shrinkage increased or decreased?
- Efficiency, Portability, Durable?
- Yes - more stress
- Increased
- Yes yes yes
What is the MAIN advantage to using composite?
It’s ability to bond to tooth structure
Indications for composites (+)
Name 7
- Class I, II, III, IV, V, & VI restorations
- Core build ups
- Sealants and preventative resin restorations
- Esthetic enhancement procedures – partial veneers, full veneers, recontouring, diastema closure
- Cements
- Temporary Restorations
- Periodontal Splinting
If you are unable to completely isolate the field from liquids in the oral cavity, _______ should be used as a restorative material instead.
Amalgam
True or False?
Composite exhibits more wear resistance than amalgam
False – generally amalgam does
Name 3 contraindications to using composite
- Isolation
- Occlusion
- Operator Factors
Name 7 advantages to using composite
- Esthetics
- Conservation in tooth structure removal
- Less complex tooth preparations
- Insulating – low thermal conductivity
- Used universally
- Bonds to tooth structure – good retention, relatively low microleakage, and increased strength of remaining tooth structure
- Repairable
Name 5 disadvantages to using composite
- Gap Formation @ root surface from polymerization shrinkage
- More difficult, time-consuming, costly
- Technique sensitive
- May exhibit greater occlusal wear in areas of high occlusal stress or when all the tooth’s occlusal contacts are on teh composite material
- Has a higher LCTE – potential marginal percolation if inadequate bonding technique is used
Explain wedge placement and purpose
- Depresses interproximal soft tissues
- Shield the dam and soft tissues from injury during the procedure
- Produces separation of teeth to help compensate for the thickness of the matrix that will be used later
- Adequate wedging assists the eventual proximal contact restoration
Wedge placement should be placed in the _____ embrasure
Lingual
Problems with COMPOSITE PLACEMENTS:
- Poor isolation of operating area
- White line or halo adjacent to the enamel margin
- Voids
- Weak or Missing proximal contacts
- Inaccurate Shade
- Poor retention
- Contouring and finishing problems
The following list can contribute to –?
- Poor contouring of the matrix band
- Inadequate wedging
- Movement of matrix band
- Tackiness of composite
- Matrix band is too thick
Weak or Missing Proximal Contacts
Problems with shade selection may occur if —
1.
2.
- Tooth surface is not dried off
- Poor lighting
