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7/29/2019 Lab 1- Prostho II
1/11
1st
lab of prosthodontics
Salam bataineh
3esam al- 3alam
10-14 2 2013
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prosto lab 1 ""
~~ Partial denture ~~
This semester we have 12 week absence without excuse allowed for 2
section . on the lab please always wear ur lab coat, name tags & bring all
ur instrument.
* fabrication of complete denture :
Just to remind you on complete denture steps we need clinical & lab
procedures :
.1- history examination
2- take a primary impression by using impression compound,
alginate & butty silicon by stock tray on appropriate size for
patient.
3-study cast made by plaster "gypsum type 2".
4-individual tray , or called (custom or especial tray).
5-secondry or final impression made by : { ZOE , plaster ,
elastomeric impression material like condensation silicon
polyether [ a specific material on dentistry that made to be
work on wet environment but its expensive ] & polysulfide ,
impression plaster " gypsum type 1 " its accurate but rigid
material we can solve this problem by adding water to matrial
after it set to take it out from the tray or teeth if it stick on
the undercut for example } .
6-border molding by { green stick or impression compound }
they are two material different on color but mainly they differ
by fusing temperature mean at temp. where the material
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become soft so we can mix green stick with impression
compound .
Note** these materials are rigid or elastic, some of them set
by heat(thermoplastic) others by chemical reaction. But
especial material needed for some cases like patient with
undercuts so I must use a material go & set under them also be
flexible that I can remove like alginate or butty silicon which
set chemically but I am a student & I make a lot of mistakes so
I need a material that can be reused like thermoplastic
material "impression compound" & so on
7-secondry or master cast poured by using dental stone
"gypsum type 3 "
8-base plate + occlusal rim ( wax rim ) = record block
9-teeth selection & mounting the upper & lower cast in the
articulator according to jaw relationship then teeth sitting
10-try in stage to make sure of esthetic, function, phonetics,
occlusion
11- fabrication ( dewaxing, packing, deflasking, finishing &
polishing ) / insertion / recall visit
**these steps need about five to seven clinical visits
Partial denture :
Patients with 1 or 2 missing teeth or with one remaining
tooth for example all need something like dentures but bcz of
teeth present on mouth it called partial denture as you know
we have temporary(interim) or permanent(definitive) & they
become in different designs according to the missing teeth onthe jaws .
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-we have to follow same sequence of complete denture but you
can avoid doing some steps like on patient with one central
incisor missing on upper jaw no need for secondary impression
bcz it will be same to primary impression bcz on central incisorI am not worry about sulcus & no need for border molding !!
also no need for all jaw records exactly like in complete
denture or tray in stage for example so here I can make a
partial denture on one or two visit ~~ but on class I mod 1 in a
patient with two canine for example all steps needed.
** so steps for partial denture depend on remaining teethstructure
*1* here in partial denture we have some extra steps just on
doing the metal frame we will learn about them later.
*2* undercuts [ every patient with teeth have undercuts ]
-Note: so elastomers used on primary & secondary impression
but on the case we mention before who have just two caninesimpression compound can be used under tissue & elastomers
under canines on same tray !!
*3* in the lab before possessing we have to make clasp
[stainless steal orthodontic wire with 0.7 0.8 diameter]
Some differences b/t
partial & complete
denture :
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*4* impression is poured within minutes on stone instead of
plaster bcz its stronger or we can use 50% plster + 50% stone
- plaster used on primary cast :
[gypsum type 1] : 100g plaster need 60ml water
[gypsum type 2] : 100g plaster need 50ml water
-secondary cast :
[gypsum type 3 ] : 100g plaster need 30ml water
[gypsum type 4 ] : 100g plaster need 20ml water " called dental
stone "
The harder the gypsum product the less water used &
vise versa
how to make an impression ??
1. we have several types of trays for upper jaw which
include the palate & lower jaw which have tongue space
also there are perforated used to make the handling ofimpression material easier& nonperforated tray also
different sizes {we must leave about 5-7mm b/t teeth
& tray always}
2.we use utility wax if tray is under extended & usually
to make sharp angels on tray more soft by cover trayborder with it.
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3.fill tray with the material used alginate for example
mixed usually 3 scope enough for upper jaw & 2 scope
enough for lower jaw .
4. put alginate on occlusal surface of teeth before
entering tray on mouth.
5.tray inserted on patient mouth on lower jaw with
slight pressure then make slight movement for lip &
check to make functional movement of muscles &
frenums then rase the tongue then move mandible rt &
lf to record sublingual tissue.
** to accelerate sitting time we use hot water & to
decrease sitting time we use cold water never change
powder/water ratio.
6.remove the tray from the mouth on one movement.
7. for upper teeth we follow same steps but upper lip &
cheeks can be moved by dental mirror also its very
important to make sure that tray is extended beyond
the vibrating lines.
8.impression poured in stone as we Saied before &
when it set we make a base.
9.the cast is ready now to fabricate a removable
partial denture.
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Material used :
Last semester we talked about how complete dentures get
their retentive nature via many things one of them isperipheral seal, the case with partial dentures are different;
we cant have a peripheral seal in them and the reason behind
this is that in complete dentures the borders (flanges) go all
the way from suclus to suclus and to the post-dam area so air
cant escape.
In partial dentures the need of having wires or clips are to
create a seal to the denture, the company provides us with
wires in these forms.
We need to use specialized tools to bend these wires, they are
called Orthodontic Pliers. Orthodontists have many designs
for these pliers if not hundreds , each design to accommodate
each function .
What characterizes the pliers are the geometric shape of the
peaks, we have conical shape , pyramidal and triangular and
many other shapes . Sometimes we have three peaks,
sometimes we have peaks of the same shape ( e.g. two peaks ,
two triangular . ) sometimes we have them different from each
other ( one conical and one triangular ) and so on , so there are
lots of shapes to accommodate the need to make the designyou want .
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However the most common types of pliers we use in dentistry
are actually two: Loop forming Pliersand Adams Universal
Pliers(named after the dentist who made it; Philip Adam).
During this semester we are going to work with the first one;
the loop forming wires but in the next year we will be working
with Adams pliers during orthodontic training.
Before we start using the loop forming pliers we have to know
how they work, looking at their peaks you can notice that one
of the peaks is sharp and one is conical. If I bend the wire
toward the sharp edge Ill get a sharp bend depending on how
much force you applied. Also if you bend toward the conical
edge Ill get a curve (loop) depending on how much force you
applied.
Adams pliers (two pyramidal peaks shape) produces a right
angle bend which is much easier to do with this tool than with
the loop forming pliers.
Depending on where you put the wire: down at the junction or
toward the tip, how acute the curve is or how wide the curve is
the wire will be affected. If I put it at the tip Ill have a
bigger curve than if I put it at the junction down.
In orthodontics they make a 360 loop (spiral) curve, but in
Prosthodontics we dont do that do you know why? In
orthodontics they make these spirals to make springs in order
to make teeth a little mobile when applying the orthodontic
treatment. In Prosthodontics we dont want teeth to move we
want them to be firm. So each one has its own objective.
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When you cut the wires without paying attention to a proper
way the wire might bounces off and hit your eye or cause
permanent injury, you have to either cover the both ends or
point the wire under the table ( or your lab coat ) so no one willget hurt . The wires themselves they have a diameter of 0.7-
0.8, they are made out of stainless-steel
Done by: salam AL-bateineh