The document discusses different types of dental plaster used for making dental models and prostheses, including their chemical composition, physical properties, and appropriate uses. It provides instructions for manually mixing dental plaster with the proper amount of water to achieve the desired hardness. Images and diagrams are included showing the materials, equipment, and process for mixing and using dental plaster.

1. Student
Teacher

2. FIG.1

3. Fig.3
Fig.2
Fig.4

7. They serve for the relief of the impressions And the
principal constituent one is the sulfate of calcium
Semi-hydrated β With the incorporation of additives.
It is in the habit of being made of white color.
Fig.5

8. For the model construction of study preparation of
the muffles in the construction of the total protheses.
Fig.6

9. It serves for the model construction, which they must
present high resistance to the compression and to the
graze. This plasters they are used for models
antagonists or for mobile protheses.
Fig.7

10. For the model construction, The resistance from
which to the compression And to the graze it is
particularly high. Minimal quantity of H2O, they are
the resistant mas and the dense mas of all.
Fig.8

11. There are extra hard of high hardness for stumps, But
with an expansion mas raised still. And also for
metallic protheses.
Fig.9

12.  All the plasters have the same chemical formula his
difference:
 It takes root principally in his physical properties.
 In the Stucco they are comparatively irregular and
porous.
 In others they are denser and of more regular form.
 This difference allows to have the same consistency
with less water in the cements stone and of great
resistance, That in the stucco.

14. Advantages Disadvantages
They do not need sophisticated They need a place fresh air to be
equipment for his manipulation. stored and without dampness.
Handling them adequately, there The properties are critical to obtain
can be achieved a complete, the physical results of agreement
smooth model and without with the type.
bubbles.
It is an economic product that one A vibrated excessive or inadequate
finds easily in the dental mechanic favors that the plaster
warehouse. catches bubbles.
It is compatible with all the
materials of impression of
odontologic use.

15. Material and equipment to realize
the manual mixture of the plaster
Plaster
Manometer Cup Spatula
Fig.10 Fig.11 Fig.12 Fig.13

16. To place in the container the necessary water, according to
the quantity of mixture that is needed to
prepare, remembering that to minor quantity of water for a
certain quantity of powder, major hardness of the plaster as
soon as it has set.
To beat energetically 1 min manually or 20-30 seconds with
food-mixer to the emptiness of plasters, the components
without adding not even any more powder any more does
not even water down, since this would cause weakness in
the plotted material.

17. To avoid the incorporation of air bubbles during the
mixture, to prevent the porosity, which he carries to the
appearance of weak points and superficial irregularities.
Not to change the relation plaster waters down once
begun the mixture, because a disorder takes place in the
crystals. If one adds water later they affect the cores of
crystallization, since different stages of hardening take
place and since not the whole mass crystallizes at the same
time, tensions are generated.

18. After finished the espatulado, places the material
before frague in the place where there is claimed that it
hardens, once fact this has to be kept the immobility of
the same one, since any movement during the work of
plotted causes faults and weak zones.
It is suitable to hope that the plaster has set completely
before submitting it to any manipulation.

19. To the 48 hrs of plotted it is considered that the plaster
has acquired his maximum hardness and
resistance, being variable the time according to the
relative dampness of the environment. Nevertheless for
common uses one can work on the plaster an hour after
this one has set, remembering that the resistance is
increasing in agreement with the step of the following
hours.

21. Barceló Santana, Federico Humberto (Materiales Dentales)
http://protesistadental.blogspot.com/2006/11/clasificacin-
de-yesos_116395478531374938.html
http://www.monografias.com/trabajos88/yesos-dentales-
utilizados-odontologia/yesos-dentales-utilizados-
odontologia.shtml
http://html.rincondelvago.com/materiales-
odontologicos.html
http://www.slideshare.net/DavidAizencop/clases-yesos-
presentation
http://frixdental.blogspot.com/2011/03/yesos-dentales.html