What is the setting reaction of GIC?
Chemistry and setting reaction. All GICs contain a basic glass and an acidic polymer liquid, which set by an acid-base reaction. The polymer is an ionomer, containing a small proportion – some 5 to 10% – of substituted ionic groups. These allow it to be acid decomposable and clinically set readily.
How does zinc oxide-eugenol set?
Zinc oxide eugenol (ZOE) is a material created by the combination of zinc oxide and eugenol contained in oil of cloves. An acid-base reaction takes place with the formation of zinc eugenolate chelate. The reaction is catalysed by water and is accelerated by the presence of metal salts.
What substance is the catalyst for zinc oxide-eugenol impression material?
The fillers are mainly zinc oxide, titanium dioxide, or zinc sulfate. The catalyst or accelerator contains lead dioxide, hydrated copper oxide or organic peroxide as a catalyst, sulfur and dibutyl phthalate as a plasticizer, and other nonessential fillers. It is set by a condensation polymerization reaction.
Why do we apply Vaseline after GIC restoration?
Similarly petroleum jelly also impedes the fluoride release, but to a very less extent. We suggest that in situations where the fluoride release property is more important than other properties it is better to coat the GIC with petroleum jelly or leave the restoration without any coating.
Is GIC radiopaque?
All base, liner, and core formulations of glass ionomer under investigation were more radiopaque than dentin. All restorative and luting formulations of glass ionomer under investigation were less radiopaque than dentin and therefore should be avoided as bases or liners.
What is the setting time of GIC?
Setting of Glass-Ionomer Cements Glass-ionomers set within 2–3 min from mixing by an acid-base reaction.
How does GIC release fluoride?
Fluoride release from GICs restorations following a continuous uptake process increases the fluoride concentration in saliva and in adjacent hard dental tissues. Thus, continuous small amounts of fluoride surrounding the teeth decreases demineralization of the tooth tissues.
What factors influence the setting time of zinc oxide-eugenol pastes?
1. A higher temperature and humidity shortened the initial setting time of all paste. 2. A higher temperature and humidity shortened slightly the time interval between a initial and a final setting time of all paste.
How long does glass ionomer take to set?
2–3 min
Glass-ionomers set within 2–3 min from mixing by an acid-base reaction. The first step is a reaction with hydrated protons from the polyacid at basic sites on the surface of the glass particles.
What is fusion temperature of impression compound?
Two types of impression compounds are available – Type 1 which is low fusing with a fusion temperature of approximately. Above 45°C and Type 2 which is high fusing with a fusion temperature of approximately above 70°C. It is manipulated in a temperature controlled water bath or air bath or open flame.
What factors influence the setting time of zinc oxide eugenol pastes?
Why petroleum jelly is applied over GIC?
Is GIC radiopaque or radiolucent?
How long does glass ionomer release fluoride?
By means of a fluoride sensitive electrode, the fluoride release from disk-shaped specimens was determined periodically over 3 years. The glass ionomer cement released the most fluoride (1.54 +/- 4 microg/cm2 after 1 year and 248 +/- 7 microg/cm2 after 3 years).
How can you reduce the setting time of zinc oxide eugenol?
How do you prolong the setting time of ZOE material?
Factors controlling setting time: Increasing the mixing time. Increasing accelerator paste while mixing. Addition of inert oils & waxes during mixing to reduce hardness like: olive oil. Increasing base paste while mixing.