zinc oxide eugenol Flashcards
temporary cementation material
powder-liquid systems (Kalzinol)
paste systems (temp bond)
non-hardening paste-paste systems (trial-opotow)
temporary restorative material
powder-liquid system (kalzinol, IRM)
pre mixed paste (coltozol, weak)
linings
powder-liquid systems (kalzinol, IRM) only under amalgam restorations
ZOE material in paediatric dentistry
IRM
zinc oxide p
main reactive chemical, white powder, tasteless, odourless and insoluble in water and alcohol. has slight antiseptic effect. 69%
rosin p
all ZOE products contain rosin.
to reduce brittleness (adds compressive strength). decreases solubility
increases setting and working time, provides a smoother mixture with better consistency 29%
zinc acetate or other salt p
accelerator (improves strength) 0.1-8%
zinc stearate p
plasticiser 1%
eugenol l
main reactive chemical, reacts with zinc oxide 85-95%
olive or cotton seed oil l
modifies viscosity
masks the taste of eugenol
5-15%
acetic acid l
accelerator
0.1-2%
manipulation
Use a cooled, clean, dry glass mixing slab or a paper pad
Shake the bottle containing powder before use.
Dispense the powder and liquid in a ratio of 3:1 on the slab, Ensure that the
liquid is kept separate from the powder until mixing commences.
Incorporate successive small portions of powder into the liquid and mix it
thoroughly with a stainless steel spatula.
Continue adding increments of powder until a putty like consistency is
obtained (should be able to manipulate or roll into a cylinder between
fingers without it sticking to gloves or instruments).
Increments are incorporated over a 30-second period until a desired
consistency of mix is achieved.
Use a stainless steel instrument like an amalgam-packer or a flat plastic,
dipped into a little ZOE powder or use a moist cotton wool pellet to press
the material into the cavity.
setting reaction
In the first reaction hydrolysis of Zinc Oxide to its hydroxide takes place.
Water is essential for the reaction.
ZnO + H2O=> Zn(OH) 2
The reaction proceeds as an Acid-base reaction.
Zn(OH)2 + 2HE ZnE2 + 2H2O
[Zinc hydroxide] [Eugenol] - [Zinc eugenolate]
The reaction of Zinc Oxide with eugenol results into the formation of zinc
eugenolate chelate.
Zinc eugenolate is easily hydrolysed by moisture.
The chelate formed is an amorphous gel that adds strength to the set
cement.
Setting time: 4-5 mins
mechanical properties
poor: breaks down during amalgam condensation or occlusal load - must be used in thickness or more than 2mm
biocompatibility
neutral pH- bactericidal-sedating effect on the pulp - cytotoxic if applied directly to the pulp
mode of retention
poor chemical adhesion to tooth structure - cavity should be technically retentive - leading to unnecessary removal of tooth structure
solubility
high solubility in water, it hydrolyses leaving a soft zinc hydroxide which slowly washes away
indication of ZOE
pulpectomy
pulpotomy
contraindications of ZOE
direct placement on an exposed pulp (results in pulp necrosis)
under a resin compiste materials, it affects the polymerisation setting reaction of resin composite and other material that contain polymerisable monomer
where a resin composite - contains material may be used in future
temporary restoration in non-retentive cavities
advantages
inexpensive
good and long track record
adequate mechanical properties
poor thermal and electrical conductor
neutral pH
bactericidal
sedating effect on the pulp
setting time is 4-5 minutes - increased working time
good marginal seal of the restoration
disadvantages
does not bond to tooth tissue or restorative material
it inhibits polymerisation
discolouration of future composite resin
soluble in the mouth
it irritates oral mucosa, can cause ulcers
it is not anti-cariogenic
low compressive strength
difficult to mix
opaque
