resin modified GIC and compomers Flashcards
What material come under glass ionomers
resin modified GIC
glass carbomer
Glass polyvinyl phosphonates
cermets and miracle mix
what comes under resin composites
glomers
polyacid modified composites or compomers
ormocers
Resin modified GIC
like GIC but addition of water miscible monomer hydroxyethylmethacrylate (HEMA) and photo inisiator
how does resin midified GIC set
acid base reaction and photopolymerisation
bonding system resin modified GIC
shares GIC chemical bond to untreated dentine/enamel, no need to bonding system
vitremer
glass ionomer cement plus HEMA
- with photo initiators and encapsulated iniator setting reaction
setting reaction of viremer
dissolution gelation hardening light cure polymerisation
what does the addition of OH group in resin do
increases the immiscibility in water making RMGIC less hydrophobic than coventiional resin composites
composition of polyacid modified resin compootie
fluoride releasing glass (instead or the normal filler)
Polymerisiing resin
what is the polymerising resin for polyacid modified resin composite composed of
ethylele urethan dimethacrylate(UDMA)
photo initiator
resin monomer modified with carboxylate side chains
how does polyacid modified resin composite release fluoride
restoration will abrorb water from the environment and then the proton is free to move through material
- attacks basic releasing glass
- get fluoride release from the polymerising resin
(they need to absorb water before they release fluoride)
what is the fluoride releasing glass in polyacid modified resin composites
strontium fluoride
trends in the dental market
amalgam use declines, aesthetec direct restorative materials will increase in use
caries rates may fall with fluoride toothpaste
tooth loss will occur later in life
compsoite and water
hydrophobic so needs bonding system
adv of composite
aesthetic
durable
safe
dis of composite
composite shrinkage
tehcninique sensitve
requires a bonding
glass ionomer cements
relatively durable
insoluble
fluoride releasing
aesthetic -ish
dis of GIC
not as aesthetic
susceptible to wear
- due to large particle size
GIC compositon
fluoroaluminosilicate glass
polymeric acid
water
tartaric acid
how is GIC formd
acid base reaction where metal cations form salt bridges with ionised carboyylate acids group on high molecular weight polyacids
what is the powder part of GIC
fluro alumínio silicte glass
freeze dried polyacrylic acid
pigments
liquid part of GIC
polyacrylic
tartaric acid
distllled water
phases of acid base reaction of GIC
1) Dissolution
- acidic attack of glass surface
2) Gelation
- early cross linking by Ca2+
3) Hardening
- substitution of Ca2_ by Al3+
acid base reaction sequence GIC
- carboxylic acid residues of polymer chains will release their proton and therefore will ionise in the presence of water
- basic glass is available to react with the proteins
- acidic attack of glass particle surface liberating some of the surface cations
- Metal ions are released from the surface of the glass
- start to form salt bridges, adjacent carboxylic acid residues stabilised by the charge on the cations
the end result is a composite biomaterial of acid degraded glass particles set in a cross linked hydrogen matrix
properties attributed to glass ionomer cements (ad and dis)
- Adhesion to mineralised tooth tissues (GIC is water based)
- F- release and associated protection against caries
- antibacterial activity?
- set without exotherm and no shrinkage
- biocompatible
- may be radiopaque
Bu relatively poor aesthetics (less translucent than normal tooth tissue) poor wear resistance, brittle, no command set (once components mixed they start to set), technique sensitive
clinical uses of GIC
1) restoration of deciduous primary teeth
2) class V restorations in permanent teeth
3) erosion/abrasion
4) fissure sealants
5) atraumatic restorative treatment
6) luting cements
7) cavity bases
Contra indicated for highly loaded sites eg cuspal or incisal edge, or where aesthetics are important (can see GIC)
