| Why are orange and white tongues supplied ? |
The Krystal Casting Tongue
- produced to eliminate the effects of excessive die stone expansion. The orange tongue is provided for use during casting the impression
and the white tongue for use in retaining the model and die sections in the SnapLok tray.
To accommodate the initial expansion of the die stone the
orange Krystal Casting tongue has been produced at a calculated thickness, which is bigger
than the white working tongue. The result is that the slot produced in the model has a
slightly over all larger dimension than the white working tongue, this difference in size
has the effect of 'absorbing' the die stone expansion. |
| After I have removed the model from the tray why can't I
re-insert the tongue so that its back edge is flush with the back edge of the tray ? |
When die stone sets its expands in all directions by a
pre-determined amount. The slot in the model into which the tongue fits is no exception.
Because the die stone has expanded, the slot in the model is too narrow to accept the full
thickness of the tongue. The orange Krystal casting tongue has been supplied to prevent
this occurrence and should be used every time an impression
is cast in a Krystal tray. |
I sometimes have difficulty in removing the tongue, for the
first time, from the set model. Is there any way in which I can make the removal and
insertion of the tongue easier?
|
The tightness of the tongue in the set model
is usually due to three reasons, firstly, a white working tongue has been used when
casting an impression instead of an orange casting tongue; secondly, excessive
expansion of the die stone caused by incorrect mixing of powder and liquid. The remedies are quite simple; in the first case ensure that an
orange Krystal casting tongue is used during casting the impression; secondly, die
stone should always be mixed in accordance with the instructions of the manufacturer to
ensure that only the designed expansion takes place.
However, because not all die stones are mixed to the
correct ratios, SnapSlip - Model Release Spray has been introduced to
make removal of the tongue easier. SnapSlip is simply sprayed onto all surfaces of the
tongue and Krystal tray - SnapSlip will stay resident on the surfaces and provide a
none-intrusive lubricant to facilitate removal and reinsertion of the tongue and
model. |
| Why, after I have removed the model from the tray can I not
obtain the perfect plane of the bottom of the tray and the bottom of the model? |
This is due to the expansion of the die stone.
When the sectioned model is replaced into the Krystal Tray a light,
but firm, tap of the base of the tray onto the work bench will ensure that all of the
segments have been correctly reseated and will also help with the correct
re-insertion of the white working tongue.
It is recommended that all models be sectioned in the canine area
to accommodate the effect of die stone expansion. Our research has found that
this will assist in the correct reseating of models in the Krystal Model Tray. |
Why should I remove the base of the Krystal Model Tray
after articulating the model and not re-use the tray ?
|
The Krystal tray has been specifically designed as a 'use once'
tray in order to avoid the problems found with both closed and open bottom trays.
a. Open bottomed trays do not retain the
liquid pour without the addition of a loose 'clip-on' base tray, and even then there is
the danger of seepage and subsequent flash on the base of the model. In addition, these
trays/models will require a separating medium to be applied before they can be
articulated.
b. Closed bottomed trays retain the
liquid pour of die stone but, after the model has been removed from the tray do not allow
visual checks that the die segments have been correctly re-seated in the tray possibly
because of retention of foreign matter within the mouldings. In addition, a closed bottom
tray does not allow the die segments to be easily removed from the tray by applying
pressure to the base of the segments.
c. A single use tray does not
require any additional transit pieces to transport the model and the work to the dentist.
What the dentist receives is virtually a solid model with the work in place, exactly as
the technician saw it and worked on.
d. Re-usable trays may well
have damage to the inside walls which can cause undue retention of the model within the
tray and also do little to assist in the prevention of cross-infection.
In fact, recent studies carried out amongst many dental
laboratories have shown that only about 20% of the so-called re-usable model trays are
ever returned to the laboratories by the dental practices thus making them expensive
disposable trays! |
| Why does the Krystal Model Tray use a central tongue and
not external clips or wings? |
When the Krystal Model Tray was designed much consideration was
given to the retention of the sectioned dies. External clips through the walls of the tray
were considered too difficult to insert and remove; external wings were found to be too
bulky and fiddly to fit and also produced a physical barrier between the technician and
the all important marginal areas. The central tongue was found to be the ideal solution in
that it gave full internal peripheral retention of the sectioned dies without making a
step around the external perimeter of the tray and does not
produce any barrier between the technician and the work. Re-insertion of the
tongue after the die stone has set, and expanded, was also found to be easier than trying
to re-insert clips through the walls of a tray into a slot that had closed as a result of
expansion of the die stone. |
| When I have a model with only one single
unit why does the model section 'click' when pushed from underneath with
the tongue in position? |
There are insufficient number of saw cuts in
the model arch which allows an uneven percentage die stone expansion. See Instruction
for Use |
| Can I obtain any technical help if I require it? |
Yes, either e-mail technical queries
with your question giving us a day time telephone number or fax us on
++44(0)1903 242811 and we will reply as soon as possible. |
