SILADENT Zirkon BioStar Instrucciones De Uso página 9

Depending on the size and complexity of the individual restoration, firing programs with quicker heating rates
may also be selected. Some dental sintering furnaces have fixed firing curves which cannot be altered.
The user must check whether the above heating rates are achievable with the furnace being used and are tole-
rated by the specific restorations without any distortion or crack formation, and define individual settings.
As the temperature measurement in every furnace can give somewhat different results, it may possibly be neces-
sary in an individual case to adjust the specific furnace temperature by carrying out a test firing cycle.
Massive drops in temperature when opening the sintering furnace should be avoided, as opening the heated
furnace can have a negative effect on both the furnace and the sintered products, damaging the restoration. The
temperatures vary according to furnace type. With our zirconia products, avoid opening the furnace at tempera-
tures above 200°C. Please refer to the instructions provided by the furnace manufacturer.
Dental frameworks and crowns made of zirconium oxide should be fired in a furnace which is only used for
these products. If additionally restorations made of other ceramic materials are fired or if liquid ceramics are
baked in the same furnace, this may impede the sintering behavior or result in localized discolouration. If the
firing of different materials in the same furnace cannot be avoided, then an empty firing cycle at maximum
temperature is recommended before firing zirconium oxide ceramics.
Facing of the frameworks
Crowns and bridge frameworks made of Zirkon BioStar materials may be faced with standard facing ceramics for
frameworks made of zirconium oxide. The facings passed by the respective manufacturers for zirconium oxide
are adapted regarding the thermal expansion coefficient and the material bonding.
Please consult the descriptions of the manufacturers of the facing material for information regarding whether
thermal or chemical pretreatment of the sintered construction is recommended before facing.
Finishing after final sintering
If any finishing of the sintered structures is required, they should always be cooled using water and very little
pressure applied during finishing to avoid the zirconium oxide undergoing a phase change from tetragonal to
monoclinic. It is the tetragonal crystal structure that gives zirconium oxide its high strength. Localized working
of the zirconium oxide can create so much pressure or temperature peaks that a phase change takes place. Zir-
conium oxide in the monoclinic phase has a different density to that in the tetragonal phase and thus also diffe-
rent refraction properties and shade effects.
Information on storage and shelf life
There is no empirical evidence on the life span of presintered dental blanks. However, no change in their mate-
rial properties is anticipated if they are stored properly, even for long periods. The blanks should not be exposed
to direct sunlight. A maximum shelf life therefore cannot and need not be defined. However, as a general pre-
caution, the dental blanks should be processed and the final sintering completed within three years of manufac-
ture.
The minimum wall thicknesses for crown and bridge frameworks and sintering program heating rates given in
the instructions for use have been tested many times in practice and have proven satisfactory. However, it may
be necessary due to unusual framework size or unequal material concentrations to adjust the processing condi-
tions to the specific restoration. Therefore simply adhering to the listed parameters cannot guarantee accurate
results.
Disposal of material residues
Remains of the blanks and, of course, also sintered parts made of Zirkon BioStar materials are categorized as
chemically completely inert and are not subject to any special disposal stipulations.
Secondary effects
Such as allergies to zirconium dioxide may very rarely occur.
Reciprocal actions
unknown
Reactions
In case of known incompatibilities and allergies to contents of the zirconium dioxide.
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