robbypowell's version from 2016-12-10 20:20

composites cont.

Question Answer
T/F: Research shows that indirect composites have greater durability and wear resistance to direct compositesFalse (To date, clinical studies have not demonstrated that use of indirect composite restorations offer superior clinical durability or enhanced wear resistance over that observed when using conventional, direct placed composites.)
T/F: Post-cure heated composites (indirect) could offer greater biocompatibility than direct compositesTrue? (Research also demonstrated that the biocompatibility of post-cure heated composite is greater as the post-cure temperature and duration of heating increase.)
_____-reinforced composites have polyethylene fibers encased in a photo-curable mixture of composite-like materialsfiber-reinforced
Fiber-reinforced composites have _______ fibers encased in a photo-curable mixture of composite like materialsPolyethylene
T/F: Research has shown that weave pattern of fiber-reinforced composites can affect the properties of the materialFalse (seems to be more marketing ploy at this stage)
In what application are Fiber-reinforced composites proposed to be indicated?pontic area support for “all composite bridges”
What is the deficiency (disadvantage) of fiber-reinforced composites?only the resin directly over the fibers benefits from the enhanced properties. Material breakage typically occurs in areas adjacent to the fibers, where the resin was not supported.
How do flowable composites' composition differ from conventional composites?markedly lower filler content (much less viscous and more fluid, allowing them to better adapt to the irregular confines of a cavity preparation.) (lower filler content --> greater shrinkage)
T/F: Flowable composites will tend to wear, stain, fatigue, and break at a greater frequency than will conventional compositesTrue (lower filler content)
T/F: Flowable composites will tend to shrink more during curing than conventional compositesTrue (lower filler content)
3 indications of flowable compositesveneer cements, cavity lining agent (for packable composites), & PRR/sealants
What is the proposed clinical benefit (problem addressed) by packable composites?obtaining consistent, well-formed interproximal contact areas
What is the difference in composition of packable composites from conventional composites?significantly higher in filler loading
Use of packable composites should be restricted to _____ teeth; why?Posterior; high filler loading tend to make them unesthetic and difficult to polish
T/F: In areas of high stress loading, packable composite can be used as a high strength substrateTrue
T/F: In areas of high stress loading, flowable composite can be used as a high strength substrateFalse (this describes packable composite)
Future composites would likely differ most in the decrease or elimination of _______. This would be accomplished by changes in the _____ component.Shrinkage; Resin component (also the ability to bulk fill and negation of the need for incremental placement)

Setting reaction

Question Answer
What is the extent of monomer conversion which can be expected under the best of oral curing conditions, and the bioavailability of unused C=C?60% to 65% (under best conditions in the mouth); remaining uncured C=C units could be either attached to the polymer network (as pendent methacrylate groups), or could be attached to unreacted monomer units then leach out having biological impact on patient
There is some post-cure reaction... cure levels reach a maximum after ___ hours, but most has occurred after what period?max 24 hrs; most occurred 15-20 min
Why should we caution patients from placing full occlusal force on a freshly-placed composite until at least 12 to 24 hours.Max strength (of post-cure) isn't reached until 24 hrs (HOWEVER most curing has happened with 15-20 minutes)
What is the mechanism holding together incremental thicknesses of composite?Covalent bonds! between O-inhibted~ C=C of first increment and newly reacting increment

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