e-Skills CD COURSE ASSIGNMENT
In this task, we would
like to ask you to make some decisions concerning the development of the
learning content for your own online or blended learning course project. Having
in mind what you have learned in chapters of our course "eLearning Content
Development"' please describe succinctly the course you are planning as
guided by the following questions. If you do not have a concrete course project
yet, you can either work together with a colleague to ascertain appropriate learning
content for a much desired eLearning course in your institution, or pretend to
have a project and sketch how you would do it.
1.
Course
Description
Give a very short description of the
course you are planning (if you are not planning a course, make it a fictional
one);
!
Course Title: Metal Casting Technique
INTRODUCTION
It is increasingly important to have metal based removable
dentures giving the problems associated with acrylic based dentures. When you
place acrylic and metal based dentures side by side the preference of dental
patient is likely going to tilt towards metal based dentures. Many advantages
can be adduced for this which includes strength, good tissue compatibility
and better heat conductivity all of which accounted for preference for metal
based dentures. The several advantages of metal based fixed and removable
prostheses are getting popular among dental patients especially with constant
development in metal technology which has continued to produce metal alloys
that are friendlier with oral tissues and help in reducing cost and time
required to produce dental prostheses.
Fabrication of metallic appliances demand a number of
skills which will enable a dental lab technologist to fabricate alloys of
different kinds using different machines, materials, techniques, and hand
tools. This course will help the participants to master a number of these techniques
which are listed below.
Course Description:
It is a common knowledge that over ninety percent of dental patients in
developing countries use acrylic based dentures. However, acrylic dentures
are fraught with a lot of deficiencies most of which metal based prostheses
may address. This course will make participants proficient in the fabrication
of removable metallic dentures and fixed restorations and teach participants
the techniques for the manipulation of metal alloys and to understand the
equipment required for this procedure. Participants will be exposed to the
latest techniques and equipments and materials in the metallurgy of dental
prostheses. Participants will be shown the step-by-step techniques required
for fabricating metallic crowns and bridges, and skeletal metal framework for
removable dentures. There shall be an opportunity for participants to engage
with experts in the design and fabrication of metallic fixed and removable
prostheses and be able to produce own single full metallic framework.
Participants who successfully completed the course and satisfied the course
examiners will go home with the prestigious
certificate of the MEDILAG CONSULT the consultancy arm the College of
Medicine of the University of Lagos, Lagos, Nigeria.
LEARNING
OBJECTIVES
This course will empower the participants to become master
metal technologist and therefore shall be able to:
1.
Understand the principles of fabricating full
crowns and bridges and metallic framework
2.
Understand partial denture design
3.
Understand the principles of spruing
4.
Understand different investment materials and
their uses
5.
Understand model preparation techniques
6.
Produce own skeletal metal frame for either
full upper or lower arch
7.
Understand the techniques for metal
fabrication for different dental prostheses
8.
Identify different tools, machines and
materials used for metal fabrication
LEARNING OUTCOMES
Participants will:
1.
Be able to carry-out metal casting methods
from pouring impression to final production of a skeletal metal framework.
2.
Fabricate full skeletal metal framework and a
metal crown.
3.
Be able to operate induction and centrifugal
casting machines
4.
Produce own metal frame.
Course Modules
1.
Pouring
of impression
2.
Die
Preparation
3.
Model
Preparation
4.
Partial
denture design-Skeletal Frame design.
5.
Types
of wax, Wax work and spruing and
principles of making sprues
6.
Carving
technique
7.
Debbublisation
8.
Investment
Technique and material management
9.
Burnout
technique-Use of burn-out oven
10.
Casting
methods-Using induction and centrifugal casting machines and de-casting
method.
11.
Sand
blasting Technique
12.
Finishing-Trimming
and Polishing techniques
13.
Managing
a goal getting dental lab
Planned
mode of learning (full online, f2f+online, CBT, etc.?): This course will be
implemented online and through face to face. It is therefore divided into
part I and II. Online module (Part I)
shall consist of contents for online delivery while the lab module (Part II)
shall consist of modules taught through face to face contact with course
participants at our dental lab at the college of medicine of the University
of Lagos.
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2. Target
Group
Does the target group have any previous knowledge about working
with computers? What internet skills do they have? Do you have any
pre-requisite for your course? How does this influence your content
development?
!
Target
Group: Licensed
dental lab technologist, and postgraduate dental surgeons who are preparing
for national and west African professional examinations.
Pre-requisite
for target participants: Participants are
expected to have prior knowledge of the use of computer for video
conferencing. The knowledge of the use of Skype is expected otherwise support
shall be given during pre-course preparations. Every participant will be
required to open Skype account and share addresses with course tutor and
fellow students and invite one another as friends on Skype network.
Assessment of students shall be on the competences acquired in metal casting techniques
not on the technology used in course implementation. No language requirement
is necessary as target group are all English speakers.
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3. Technological
Infrastructure & Study Location of Target Group
What technical equipment does your target group use? Do the
participants learn at home or at work? How does this influence your content
development (not many animations or expensive screen design, …)?
!
Participants will
need their personal computers and similar devices to participate in online
modules but the face to face module which will take place in the College
dental lab will require the use of dental equipment, materials and hand tools
the cost of which has been included in the course fee.
Online course shall
be scheduled and time table forwarded to participants who will be expected to
hook on to the Skype network. In order to participate on this course personal
computers (PC) should have webcam. Through video conferencing tutor will
deliver lectures on the online modules and chat function shall be used for
participants to ask questions.
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4a Financial
and Human Resources at your Institution
What financial and personal
resources do you have at your disposal to help with the preparation of content?
How does this influence your content development?
!
All course
materials and equipment is available at the LUTH/CMUL dental laboratory. The
cost for the use of these materials is embedded in the course fee. However, a
written approval from the management is required for the dental lab to be
used.
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4b. Methodology/Pedagogy:
Methodology: Lectures,
discussions, and hands-on.
Pedagogy: Instructivist
and socio-constructivist
4c. Course Duration: Three days requiring a
minimum of six (6hrs) commitment per day.
4d. Learner’s
Progress Check
Are you planning to test your
learners? Will you provide tests/ quizzes or individual/group activities in
your course? Will you make these tests as pre-requisite before they enter
another chapter in your module? Or will the tests / activities just serve as
guide or add-ons in your module? (Give
examples of tests / activities that you are planning in your module, if any)
!
Assessment:
Formative 30% of course work; Summative 70% of course work
Summative assessment shall be on essay submitted summarizing the
learning experiences for each module and the metal frame cast by the
participant.
Formative shall be students’ participation on the course namely: answer
to question, group work, attendance at both online and face to face meetings,
and contribution to online discussions.
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4e. Practical
task: Sketch one screen of your eLearning content!
Try to compose one
screen for your learners. This could be any screen from your course project.
Think of a side-bar with
information (a glossary perhaps or a picture), think of the text, the
graphics, animations,
pictures …
Describe the screen or
(even better) try to visualize it in a word-file or a power point slide or in
this document.
NOTE: See the
attachment for answer to 4e above.
Introduction
The foundation of fabricating most dental prostheses is by
obtaining an impression of the mouth (negative replica of the oral cavity)
which consists of the teeth, the mucosa and other adjoining tissues from which
a model (Positive) replica of the mouth is obtained.An impression is necessary
because the mouth is a small space to conveneiently carryout most procedures
for diagnosis and treatment of most oral
diseases. Fabrication of conservative and restorative prostheses is mostly and
smoothly possible outside the mouth. Therefore, an impression of the mouth is
necessary but this is not just what a dental lab technologist needs to achieve
a good fabrication of an oral appliance. The impression needs to be cast in
stone plaster. Other harder materials are used for other purposes e.g. densite
used for fabricating metallic appliances. Impression could also be poured in
refractory material so as to obviate the need for duplication later on. Model
obtained from an impression forms the foundation of laboratory procedures for
the manufacture of dental appliances for restorative, conservative, treatment
and re-alignment of badly angulated teeth in the mouth.
Materials and
Equipment
·
Impression in dental trays-Stock or special
trays which could be made in different materials like metal and plastic
- · Plaster Bowl
- · Dental hand spatula (or mechanical spatulator)
- · Measuring cup
- · A jar of water and measuring jar
- · Vibrator
Step-by-step
Technique- Impression must be received from the dental surgery.
1.
Wear protective gloves and facemask for handling
so as to prevent infection and material spill when casting the impression and the
oral fluid getting on your face.
2.
Carefully handle impression and rinse it under
slow running tap and dip in 50% hypochlorite solution to sterilise against
cross infection.
3.
Inspect and ascertain if impression covers all
the necessary areas and if satisfied drain off water on impression surface by
blowing air on the impression.
4.
Place impression tray on impression rack with
the posterior end raised up to prevent distortion.
5.
Measure a 20ml of water into a plaster bowl and
gradually sieve about fifty grammes (50g) of stone plaster into the bowl until
completely soaked by water in the bowl and spatulate by circular movement only
either by mechanical means or manually by the use of dental spatula until
creamy and homogeneous paste is achieved. Note measure of stone powder is often
done by experience and varies either it is lower or upper arch that is been
treated.
6.
If an upper impression place a little of the
stone paste in the palatal area of the impression and switch on the mechanical
vibrator until filled to the periphery of the impression. If lower stone paste
is placed at the most posterior end and tray lowered towards anterior end until
filled to the peripheral areas.
7.
Allow to stand until stone attained full setting
time which is not more than fifteen minutes for a regular setting stone
plaster.
Decasting Method.
Once satisfied that the stone is fully set by feeling if it
is no longer warm as setting of stone plaster is an exothermic reaction
decasting procedure is initiated.
1.
Clear off all impression material that flew
through the perforation in the impression tray.
2.
Place your wax knife between the tray and the
impression material from the posterior end of the tray and gradually lift the
model off the tray.
3.
Continue this until the model is fully recovered
from the stock tray
4.
Cut excess stone material with plaster cutter
and if necessary use model trimming machine (Note model trimming could be more
that this as the purpose a model is made vary and should determine how this
should be done).
Don’ts
·
Do not wash or blow impression too hard to avoid
distortion.
·
Do not apply pressure on the impression when
casting e.g. if dental spatula is used to scoop stone plaster on the impression
·
Do not make a thin mix, so follow manufacturer’s
instruction on water/powder ratio to avoid weak model.
·
Do not place the posterior end of an impression
resting on bench top in order to forestall lifting and eventual distortion.
·
Lift stone model gently to forestall breaking
standing teeth on the model.
Benefits
Making impression of the mouth and getting a model out of it
is necessary as the mouth is a small place where most procedure cannot take
place because of the inconveniences of dental patients opening his mouth for
too long and that most procedures involving restorations have to pass through
the rigours of laboratory procedure which cannot be possible in the mouth. For
example making an acrylic denture is not possible in the mouth and hence a
measurement of the mouth is necessary for lab technologist to separately
manufacture this prosthesis.
Conclusion
Making model is important and the sequences of making a
dental model have to be followed strictly otherwise result may amount to a
waste of time and resources. Although some treatment and diagnosis of oral
diseases may take place at chair side but most appliances is done in the dental
lab. The foundation of all dental prosthesis make for patient is the model.
Casting techniques for production of dental model is therefore very essential
to restoring good oral health
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