p.6
Clinical Properties and Depth of Cure in Composites
What happens if the curing time is extended too much?
Extending the curing time too much does not add anything except for heat.
p.2
Functions and Types of Fillers in Composites
What are the advantages of using glass and quartz fillers?
Best properties, high hardness & erosion resistance, color stability, bind best to matrix.
p.4
Physical Properties of Composite Materials
What are the handling properties or textures of composites?
Composites can be categorized as all-purpose, flowable (e.g., fissure sealants), and packable.
p.7
Clinical Properties and Depth of Cure in Composites
Why do we add light cured composites in 2mm increments?
To ensure proper curing within the 2-2.5mm depth of cure.
p.3
Classification of Composites by Filler Particle Size
What are the sizes of fillers in composites and their characteristics?
Sizes include Mega (higher fracture toughness, higher stiffness, low thermal expansion, less polishable, more superficial stains), Macro, Midi, Mini, Micro (highly polishable, less superficial stains, more flexible, increased thermal expansion), and Nano.
p.1
Composition and Definition of Resin Composite
What is the definition of a resin composite?
A resin composite is a 3D structure made of two different materials with an interface, consisting of a continuous phase and a dispersed phase.
p.2
Functions and Types of Fillers in Composites
How does adding filler improve the properties of composite materials?
By decreasing the volume of the resin matrix.
p.3
Functions and Types of Fillers in Composites
What are the different shapes of fillers in composites?
Shapes include irregular with rounded edges, irregular with sharp edges, spherical, and porous.
p.3
Initiator Systems in Composite Materials
What is the role of chemical initiators in composite materials?
Chemical initiators allow reactions to occur, while photoinitiators are activated by light to form free radicals.
p.4
Fabrication Techniques for Composites
What are the modes of cure for composites?
Composites can be light cured, chemically cured, or dual cured (light + heat or chemical + heat).
p.6
Clinical Properties and Depth of Cure in Composites
Which type of curing shows better color stability?
Chemical cured shows better color stability than light cured.
p.1
Initiator Systems in Composite Materials
What role does the initiator system play in resin composites?
The initiator system starts the polymerization reaction and is activated with blue light, initiating the polymerization of the resin matrix.
p.3
Mechanical Properties of Composites
What are the modes of loading for fillers in composites?
1) Homogenous (all fillers the same), 2) Heterogenous (fillers of different size & shape), 3) Sintered (compacting a solid mass by heating).
p.1
Composition and Definition of Resin Composite
What components make up the matrix of a resin composite?
The matrix consists of pigments, an initiator system, polymerized dimethacrylate, a coupling agent, and fillers.
p.4
Classification of Composites by Filler Particle Size
What are the types of filler loading in composites?
Filler loading in composites can be categorized into homogenous filled composites and heterogenous filled composites (blended).
p.7
Clinical Properties and Depth of Cure in Composites
What factors affect light attenuation in composites?
Filler size, filler concentration, opacity, pigments/shades, tooth structure, and distance from light source.
p.6
Mechanical Properties of Composites
What is the effect of higher filler content on compressive strength?
Higher filler content leads to brittleness.
p.6
Mechanical Properties of Composites
What factors affect the hardness of composite materials?
Factors include hardness of fillers, filler loading, and degree of polymerization.
p.1
Functions and Types of Fillers in Composites
What is the function of the coupling agent in resin composites?
The coupling agent bonds to both the filler and the matrix, typically using silane to enhance adhesion.
p.1
Physical Properties of Composite Materials
What happens to the polymer used in resin composites when water is absorbed?
The absorbed water can attack the coupling agent and lead to slow failure of the composite.
p.6
Mechanical Properties of Composites
How does the modulus of elasticity compare between microfilled and fine particles hybrid composites?
Microfilled composites have a lower modulus of elasticity compared to fine particles hybrid composites.
p.3
Composition and Definition of Resin Composite
How does zirconium compare to heavy metal glass in composites?
Zirconium is harder than heavy metal glass but should be coated with silica to attach to the matrix; it is not as hard as quartz.
p.2
Biocompatibility of Dental Materials
What effect does water sorption have on composite materials?
It can cause expansion and affects the coupling agent.
p.5
Clinical Properties and Depth of Cure in Composites
What are the setting times for chemically-cured composites?
3-5 minutes from the start of mixing
p.5
Thermal Properties of Composite Materials
What is the coefficient of thermal expansion's effect on marginal percolation?
If not matched, it leads to marginal percolation.
p.4
Physical Properties of Composite Materials
How are working and setting times related to light-cured composites?
The working and setting times of light-cured composites are related to the application of the light beam.
p.2
Clinical Properties and Depth of Cure in Composites
What is a main problem associated with polymerization shrinkage?
It can pull apart bonding leading to marginal failure.
p.2
Mechanical Properties of Composites
What is the significance of fracture toughness in composite materials?
It indicates the resistance of the material to fracture.
p.2
Composition and Definition of Resin Composite
What is the function of TEG-DMA in composites?
Diluents, more filler loading, increased flexibility, decreased brittleness
p.5
Mechanical Properties of Composites
What techniques can decrease polymerization stresses?
Incremental technique, composite inlays, curing modes
p.4
Classification of Composites by Filler Particle Size
What are the classifications of composites by filler particle size?
Composites can be classified into hybrid composites, which include midi-hybrid (midi & micro), mini-hybrid (mini + micro), and nano-hybrid (nano + mini/midi).
p.1
Ideal Requirements for Direct Aesthetic Restorations
What are the ideal requirements for direct aesthetic restorations?
1) Bonding to enamel & dentin 2) Colour matching, translucency & same refractive index 3) Insoluble in saliva & oral fluids 4) Smooth surface 5) Acceptable mechanical properties 6) Coefficient of thermal expansion similar to tooth structure 7) Good marginal integrity 8) Not irritant to pulp & gingival tissues 9) Cariostatic (release fluoride) 10) Easily placed & repaired 11) Minimal dimensional change on setting 12) Adequate radiopacity.
p.2
Mechanical Properties of Composites
What is the elastic modulus of a rigid material?
A rigid material has a high elastic modulus and cannot absorb shock.
p.2
Functions and Types of Fillers in Composites
What is a disadvantage of silica (colloidal) fillers?
Decreased properties compared to quartz.
p.5
Mechanical Properties of Composites
What are some adverse effects of polymerization shrinkage?
Debonding, staining, recurrent caries
p.5
Biocompatibility of Dental Materials
What are the adverse effects of water sorption in composites?
Decreased hardness and decreased wear resistance
p.7
Clinical Properties and Depth of Cure in Composites
What are two options to improve curing of composites?
Decrease increment thickness or increase curing time.
p.3
Composition and Definition of Resin Composite
What are the characteristics of heavy metal glass in composites?
Heavy metal glass is radiopaque, consists of fine particles, has good polishability, wear resistance, low cost, is soluble, and is difficult to attach to the matrix.
p.6
Mechanical Properties of Composites
What are some factors affecting wear in composite materials?
Factors include filler volume, particle size, fillers hardness, tooth position in the arch, porosity, degree of polymerization, coupling agent, and method of finishing.
p.6
Clinical Properties and Depth of Cure in Composites
What is the consequence of under-curing composite materials?
Under-curing compromises material strength.
p.1
Functions and Types of Fillers in Composites
Why is the filler important in resin composites?
Fillers provide viscosity to the composite; without them, the composite acts as a weak point.
p.5
Thermal Properties of Composite Materials
Which type of composite has a higher thermal diffusivity?
Fine particles & hybrid composites
p.5
Composition and Definition of Resin Composite
What are some components of the matrix that contribute to solubility?
Residual monomer or oligomer, incomplete polymerization, alcohol
