lecture 4

Question 1

composite resins

Answer 1

esthetic direct restorative
curved by visible light
excellent outcomes

Question 2

primary benefit of composite resisns

Answer 2

combination of esthetics and ease of placement

Question 3

composite resins are a hybrid material of what and what

Answer 3

organic phase (resin) and inorganic phase (filler)

Question 4

components of composite resin

Answer 4

organic resin phase
inorganic filler phase
bonding agent
visible light iniator

Question 5

role or resin

Answer 5

helps processing and handling (high viscosity and cannont be used alone).

Question 6

role of filler

Answer 6

helps modulus and wear resistance

Question 7

what is curing

Answer 7

crosslinking to make more stiff and stronger

Question 8

what is crosslinking

Answer 8

joining polymers with covalent linkages

Question 9

more cross links means….

Answer 9

longer working time
increase modulus
stiff and stronger material

Question 10

filler

Answer 10

silica or zirconia inorganics
50-80% weight in composites
has surface OH’s
higher filler = increase modulus, viscosity, strength, decrease shrinkage

Question 11

why are fillers small

Answer 11

teeth are nano composites
so smaller fillers have better wear properties
better polishing and finishing

Question 12

what does coupling agent do

Answer 12

binds to inorganic filler so it can bind to organic resin

Question 13

what does coupling agents use on fillers to bind

Answer 13

OH groups

Question 14

polymerization shrinkage

Answer 14

density change from monomer to polymer
double bond polymerization
measured by dillatemeter
important for direct composite restoratives

Question 15

polymerization shrinkage causes what

Answer 15

stress on tooth structure

microleakages leading to secondary caries

Question 16

glass ionomer cements 2 components cements

Answer 16

acidic polymer in aquous solution (polyacid)

basic glass

Question 17

glass ionomer cements

Answer 17

cured by acid base reaction
releases flouride
good adhesion to tooth surface
salt bridges created slide can bind to 3 groups

Question 18

basic glass

Answer 18

alumniaflourosilicate glass

ground into 45 micrometer particles

Question 19

glass ionomer cement components

Answer 19

polyacid
basic glass
water
modifiers

Question 20

curing setting rxn step 1

Answer 20

polyacid reacts with basic glass

Question 21

curing setting rxn step 2

Answer 21

not all glass is consumed in rxn

Question 22

curing setting rxn step 3

Answer 22

salt bridges will form between poly acid and basic glass

Question 23

setting reaction glass ionomer step 1

Answer 23

condition dentin- cleans smear layer, leaves smear plug.

Question 24

setting reaction glass ionomer step 2

Answer 24

GI mix applied –>acid matrix dissolves glass –> glass releases ions

Question 25

how glass ionomer cement differ from composites

Answer 25

no coupling agent needed

F-released

Question 26

what is released during the setting of this reaction

Answer 26

sodium and flouride

Question 27

microtags

Answer 27

important for forming mechanical bonds as opposed to chemical bonds. ( needs rough Surface area)

Question 28

adhesives

Answer 28

based on composite chemistry
contains acidic groups to promote binding
dimethylcrylates cured by visible light
unfilled or lightly filled
bind to enamel

Question 29

composites are hydro____ while adhesives are hyrdo_____

Answer 29

hydrophobic

phobic/phillic

Question 30

differences between adhesives and composites

Answer 30

need less filler to decrease viscosity.

Question 31

hydrophilic modifiers promote ______

Answer 31

bonding

Question 32

enamel/dentin is hydro______

Answer 32

philic

Question 33

how sealants differ from composites

Answer 33

no filler needed

low viscosity which makes flowing into pits easy

Question 34

oxygen inhibition layer

Answer 34

oxygen interfere with radical polymerization
so at surface of composites or sealants, unpolymerized material must be removed
(build up and cure in layers)