This document provides an overview of the lost wax casting technique used in dentistry. It discusses the history of casting, outlines the key steps including preparation of a die, wax pattern fabrication, spruing, investing, burnout and casting. The objectives of casting are to heat the alloy quickly to melt it completely, prevent oxidation during heating, and produce a casting with sharp details by forcing the molten metal into the mold. Successful casting depends on attention to detail and consistency of technique at each step.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Dental casting investment: A material consisting primarily of an allotrope of silica and a bonding agent. The bonding substance may be gypsum (for use in lower casting temperatures) or phosphates and silica (for use in higher casting temperatures). (GPT 8)
Indian Dental Academy: will be one of the most relevant and exciting
training center with best faculty and flexible training programs
for dental professionals who wish to advance in their dental
practice,Offers certified courses in Dental
implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic
Dentistry, Periodontics and General Dentistry.
Introduction
CERAMICS : An inorganic compound with non-metallic prosthesis typically consisting of oxygen and one or more metallic or semi-metallic elements that is formulated to produce the whole part of a ceramic based dental prosthesis. – GPT 7.
The word Ceramic is derived from the Greek word “keramos”, which literally means ‘burnt stuff’, but which has come to mean more specifically a material produced by burning or firing.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Dental casting investment: A material consisting primarily of an allotrope of silica and a bonding agent. The bonding substance may be gypsum (for use in lower casting temperatures) or phosphates and silica (for use in higher casting temperatures). (GPT 8)
Indian Dental Academy: will be one of the most relevant and exciting
training center with best faculty and flexible training programs
for dental professionals who wish to advance in their dental
practice,Offers certified courses in Dental
implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic
Dentistry, Periodontics and General Dentistry.
Introduction
CERAMICS : An inorganic compound with non-metallic prosthesis typically consisting of oxygen and one or more metallic or semi-metallic elements that is formulated to produce the whole part of a ceramic based dental prosthesis. – GPT 7.
The word Ceramic is derived from the Greek word “keramos”, which literally means ‘burnt stuff’, but which has come to mean more specifically a material produced by burning or firing.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.
VR與AR技術於醫療領域的可能性及案例分析 (VR & AR Technologies in Medical Applications)宇軒 黃
【跨 X 創 產業小聚】#6
VR技術引爆超世代教學革新:從醫療與教育出發
VR and AR Technologies in Medical Applications
據美國研究機構報告,AR/VR的醫療健康市場到2020年將達25.4億美元,主要來自模擬訓練及康復治療。在未來的健康醫療教育融入虛擬及擴增實境應用中,又可以達到什麼境界?
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Recent advances in dental porcelain materials / cosmetic dentistry coursesIndian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.
Indian Dental Academy: will be one of the most relevant and exciting training
center with best faculty and flexible training programs for dental
professionals who wish to advance in their dental practice,Offers certified
courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry,
Prosthetic Dentistry, Periodontics and General Dentistry.
Lost Foam Casting (LFC) Process is most economical Foundry Molding Technology today which a green technology. It saves 25 to 40% in totality. We provide you Turnkey Project support.
Cement refers to the commodities that are produced by burning mixtures of limestone and other
minerals or additives at high temperature in a rotary kiln, followed by cooling, finish mixing, and
grinding. This is the manner in which the vast majority of commercially-important cementations
materials are produced in the United States. Cements are used to chemically bind different
materials together. The most commonly produced cement type is "Portland" cement, though
other standard cement types are also produced on a limited basis.
Cement plants produced 99.8 million metric tons of cement. Worldwide production accounted
for about 2.5 billion metric tons. As with most large manufacturing industries, by-product
materials are generated. These industrial by-product and waste materials must be managed
responsibly to insure a clean and safe environment.
Steel mills, also known as steelworks, are industrial factories that specialize in the production of steel. They typically smelt down iron and carbon, mixing the two together in a specific ratio to create steel.
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
3. GUIDED BY :
Dr. AJAY SAXENA Dr. MANOJ CHANDAK
(Prof. & Guide) (H.O.D & Prof.)
Dr .Pradnya Nikhade Dr. N. U Manwar
(Prof.) (Prof.)
Dr. Anant Heda Dr. Anuja Ikhar
(Reader) (Reader)
Presented by Dr. Abhilasha dass
4. CCoonntteennttss
Introduction
History
Preparation of a die
Wax Pattern fabrication
Sprue Former
Reservoir
Casting Ring liner
Investing
Burnout
Lost wax Technique
Crucibles
Casting
Casting machines
Cleaning of casting
Take home message
4
5. 5
Sr.no. Learning objective Domain Level Criteria
1 Steps in casting procedure Cognitive Must know All
2 Preparation of a die Cognitive Must know All
3
Wax Pattern fabrication
Cognitive Must know All
4 Sprue former Cognitive Must know All
5 Casting Ring liner Cognitive Must know All
6 Investing Cognitive Must know All
6. 6
7 Burnout Cognitive Must know All
8 Lost wax Technique Cognitive Must know All
9 Crucibles cognitive Must know All
10 Casting machines cognitive Must know All
11 Finishing & polishing cognitive Must know All
7. IInnttrroodduuccttiioonn ::
Casting is the process by which a wax pattern
of a restoration is converted to a replicate in a
dental alloy. The casting process is used to
make dental restorations such as inlays, onlays,
crowns, bridges and removable partial
dentures.
In dentistry the resulting casting must be an
accurate reproduction of the wax pattern in
both surface details and overall dimension.
7
8. Reproducing the wax up in metal with
predictable results has always been a
challenge.
Small variation in investing or casting can
significantly effect the quality of the final
restoration.
Successful castings depend on attention
to detail and consistency of technique.
8
9. HHiissttoorryy
In approximately 500 BC, the Etruscans produced bridges made
of soldered gold bands.
The most ancient dental prosthesis fabricated from gold wire was
found in Egypt and dated as far back as 2500 BC.
Copper was cast in Mesopotamia about 3000 B.C.
The oldest dental castings were gold inlays found in teeth from
the natives of Ecuador in about first Century AD.
11th Century A.D→ Theophilus → Described lost wax technique,
which was a common practice in jewelry.
9
10. 10
• The renaissance craftsman and sculptor Benvenuto Cellini
(1500-1571) in his autobiography described his method of
casting in both gold and bronze by coating his finely detailed
wax model with a reinforced refractory shell.
• 1558 → B. Cellini → attempted use of wax and clay for
preparation of castings.
11889988- Dr. Philbrook demonstrated the 1st cast gold inlay in the
Dental Society.
1903 Lentz cast occlusal surfaces to banded gold crowns by the
lost wax method of mould formation but apparently did not apply
his technique to the fabrication of cast inlays.
11. 11990077- Introduction of lost wax technique by W.H Taggart.
11991100 Van Horn introduced a different method of
compensation recommending that the wax pattern be
invested at a temperature equal to mouth temperature.
1928 The low heat casting technique was finally abandoned
when Coleman published his research paper No.32 for the
United States National Bureau of Standards in which he
demonstrated the great shrinkage which occurred when
investment is cooled after heating.
11
12. Weinstein in 11992299 found that adding boric acid to
customary investment mixtures prevented the shrinkage.
Sweeney, Paftenbarger ((11993300--3333)) studied use of
cristobalite as a refractory in dental casting investment
and found that a cristobalite based investment (75%
cristobalite & 25% plaster) heated to temperatures
between 400ºC and 800ºC produced dimensionally
accurate castings.
11994422-Sonder- recognised thermal expansion of
investment was greatly inhibited by rigid metal casting
ring- advocated lining with soft asbestos.
12
13. 11993344- Classification of gold based casting
alloys.
Goldberg ((11993377)) recommended the use of the
wax with 0.1% Contraction for the direct
technique and the wax with 0.38%
contraction for the a patterns made on a die
at room temperature in the indirect
technique.
13
14. • 11994455- George D. Estes, introduced the vacuum investing
technique to prevent formation of air bubbles on the surface
of the wax.
• 11994499-- Moore and Walt developed phosphate bonded
investment
• 11995500-development of resin veneers for gold alloys
1959 –Asgar & Peyton stated that flaring should
occur at the sprue/ wax pattern junction.
1959 - Strickland et al stated the importance of the
type, shape location & direction other than the size
of the sprue .
14
15. 1959 - Morrison and Warmick reported the findings of
ethyl silicate refractory material for dental use.
• 11996688-Pd based alloys alternatives for gold
• 11997711- Ni based alloys alternatives for gold
• 11998800’’ss-Introduction of all-ceramic technology
Moore ((11999933)) discovered by the addition of chlorides to
investments he could obtain a thermal expansion of as
much as 1.1% from quartz based investment.
15
16. DDeeffiinniittiioonn
Casting is defined as something that has been cast
in a mold, an object formed by the solidification
of a fluid that has been poured or injected into a
mold.(GPT)
“Casting is the process by which a wax pattern of
a prepared tooth is fabricated and converted to
its metallic replica”(Rosenteil)
16
17. OObbjjeeccttiivveess ooff ccaassttiinngg ::
1) To heat the alloy as quickly as possible
to a completely molten condition.
2) To prevent oxidation by heating the
metal with a well adjusted torch .
3) To produce a casting with sharp details
by having adequate pressure to the well
melted metal to force into the mold.
17
19. DDiiee
• Defined as the positive reproduction of the form of the prepared
tooth in any suitable substance in which inlays, crowns & other
restorations are made.
IDEAL REQUIREMENTS
• Accurate reproduction of the fine details
• Dimensional accuracy
• Good strength & hardness
• Ease of use
• Abrasion resistance
• Relatively inexpensive
19
20. PPRREEPPRRAATTIIOONN OOFF MMAASSTTEERR DDIIEE ::
Commonly used die materials-
Type IV gypsum product - 0.1%
(setting expansion)
Type V gypsum product - 0.3% (setting
expansion)
Disadvantage- Susceptibility to abrasion
20
21. Means to increase abrasion
resistance of die :
-Silver plating
-Coating surface with die
hardener
- Adding die hardener to
gypsum
21
22. DDiiee ssppaacceerr
Used to provide relief space for cement.
Applied within 0.5mm of the preparation finish line to provide relief
for the cement luting agent.
Example- resins (most commonly used)
- model paint
- colored nail polish
- thermoplastic polymers
dissolved in volatile solvents.
22
23. DDiieessttoonnee//iinnvveessttmmeenntt ccoommbbiinnaattiioonn
In this, die material and investment medium have a
comparable composition
Divestment – a commercially
available gypsum bonded material .
Divestment is mixed with colloidal silica and die is made
from this mix & wax pattern is constructed.
Advantage- It eliminate possibility of distortion
of wax pattern while removing it from die .
23
25. 25
ELECTROFORMED DIES :
These dies have high strength, hardness &
excellent abrasion resistance.
First step – Treating the surface of impression
material so that it conducts electricity. This process
is referred as METALLIZING.
PROCESS : A thin layer of metal, such as silver
powder, is deposited on the surface of impression
material.
Example : Bronzing powder
aqueous suspensions of silver powder
powdered graphite
27. WWaaxx ppaatttteerrnn ffaabbrriiccaattiioonn
27
- It is contouring of wax
pattern into desired shape and
form.
- All aspects of final
restoration are incorporated
into the wax pattern
- Shortest time should elapse
between the time the pattern is
removed from the die & the
time
it is invested.
28. WWaaxx TTeecchhnniiqquuee
28
A) DIRECT
Wax pattern is made
directly inside the
mouth, as in inlay
case.
Type-1 medium wax.
Exceptionally
demanding procedure.
B) INDIRECT
Wax pattern is made on
the
die.
Type -2 soft wax.
More commonly used
technique.
30. SSpprruuee
Part of casting that acts as a channel for the
molten metal to flow into the mold cavity after
the wax has been eliminated.
PURPOSE:
To form a mount for the wax pattern & fix the
pattern in space so a mold can be made.
To create a channel for elimination of wax
during burn out.
To form channel for ingress of molten alloy .
To compensate for alloy shrinkage during
solidification.
30
33. FUNCTION:
Facilitate flow of molten metal from crucible
to mold.
Store additional metal & prevent shrinkage
porosity.
May be used as handle to remove wax
pattern.
33
38. SSPPRRUUIINNGG TTEECCHHNNIIQQUUEE
DIRECT : sprue former provides direct connection
between pattern area & the sprue base/crucible
former area.
A basic weakness of direct Spruing is the potential for
suck-back porosity at the junction of restoration and the
Sprue.
INDIRECT: connector/ reservior bar is positioned
between pattern & the crucible former.
Indirect Spruing offers advantages such as greater
reliability & predictability in casting plus enhanced control
of solidification shrinkage .The Connector bar is often
referred to as a “reservoir .
38
39. SSpprruuee ffoorrmmeerr
The sprue is attached to a crucible
former, usually
made of rubber, which constitutes the
base of the
casting ring during investing.
May be metal , plastic or rubber
The exact shape of the crucible former
depends on the type of casting machine
used.
With most modern machines, the crucible
former is tall to allow use of a short sprue
and allow the pattern to be positioned
near the end of the casting ring.
also referred to as a sprue former
39
40. Crucible formers/ Sprue formers are
basically of 2 types---
a) Steep-sided cone: used with metal
when casted using centrifugal casting
force.
b) Shallow cone: used to cast metal
using stream/air pressure
40
41. RREESSEERRVVOOIIRR
Piece of wax attached to the sprue about 1mm away
from the pattern ,as a enlarged round mass or a
connector bar between the wax pattern sprue former.
41
43. SSUURRFFAACCEE TTRREEAATTMMEENNTT OOFF
CCOOMMPPLLEETTEEDD WWAAXX PPAATTTTEERRNN
Before the wax pattern is invested, it
should be cleaned of any debris, grease,
oils and separating medium.
43
47. CCaassttiinngg rriinngg && lliinneerr
The casting ring serves as a container for
the investment while it sets & restricts
setting expansion of the mold.
47
Metal casting
ring
Sprue base or
Crucible former
Ring liner
48. CCaassttiinngg RRiinngg
They are available as-
1) Shapes - Round
- Oval
2) Complete rings
I) - Rigid
- Metal (stainless steel)
- Plastic
II) Flexible - Rubber
3) Split rings
I) metal
II) plastic
48
49. CCaassttiinngg RRiinngg CCoonnssiiddeerraattiioonnss ::
1) The internal diameter of casting ring
should be 5-10mm greater than the widest
measurement of the pattern and about 6
mm higher.
2) For single crown/inlay - small rings as
used. Diameter - 32 mm
3) For large fixed partial denture –
63mm round/oval shaped casting ring are
used 49
50. CASTING RING
LINERS
ASBESTOS
LINERS
NON ASBESTOS
LINERS
CELLULOSE PAPER
AL-SILICATE CERAMIC
50
Asbestos:- carcinogenic potential makes it a biohazard.
Functions of a liner
Affords greater normal expansion in the
investment
The absorbed water causes a semi hygroscopic
expansion
Thickness – not less than 1mm
51. LLiinneerr tteecchhnniiqquuee
A)DRY LINER TECHNIQUE - tacked in
position with sticky wax.
B)WET LINER TECHNIQUE - lining ring is
immersed in water & excess water is shaken
off.
The liner is cut to fit the inside diameter of
the casting ring with no overlap and 3mm
short of the top and bottom of the ring , this
serves to lock the investment within the ring
& equalize expansion.
51
53. RRIINNGGLLEESSSS CCAASSTTIINNGG TTEECCHHNNIIQQUUEE
With the use of higher-strength, phosphate-bonded
investments, the ringless technique has become
quite popular.
The method uses a paper or plastic casting ring
and is designed to allow unrestricted expansion.
53
54. Crucible formers and cone-shaped plastic rings for a
ringless casting system.
The crucible former and plastic ring are removed
before wax elimination, leaving the invested wax
pattern.
The systems are designed to achieve expansion that
is unrestricted by a metal ring.
54
55. IInnvveessttiinngg
Process by which the sprued wax pattern is
embedded in a material called an investment.
OR
A ceramic material that is suitable for forming a
mould into which a metal or alloy is cast.
The operation of forming a mold is known as
INVESTING
55
57. While the wax pattern is air drying,
the appropriate amount of distilled
water (Gypsum Bonded
investments), colloidal silica special
liquid (Phosphate Bonded
investments) is dispensed.
Powder should be weighed before
mixing it with liquid.
The liquid is added to clean dry
mixing bowl, and the powder is
gradually added to the liquid using
care and caution to minimize air
entrapment.
57
58. PPaaiinntt ooffff tteecchhnniiqquuee
Wet investment material
is gently painted over a
complex wax pattern by
the use of sable hair brush,
covering it completely .
58
59. Poured into the ring thinly
from a height (20-30)cm at
a slight angle from
bottom to the top of a ring
59
61. 61
Allow the investment to set
(45 – 60) min before
burnout procedure
commences
Place invested ppaatttteerrnn iinn aa
hhuummiiddaattoorr iiff bbuurrnnoouutt pprroocceessss iiss
ddeellaayyeedd..
62. METHODS OF INVESTING:
A) HAND INVESTING
B) VACCUM INVESTING
Advantages of vacuum investing
• The amount of Porosity in the investment is
reduced
• The texture of cast surface is smoother with
better detail reproduction
• The tensile strength is greatly increased
62
65. •When the investment has set,
the "skin" at the top of the ring
is trimmed off.
•The rubber crucible former is
removed, and any loose particles
of investment are blown off.
•The ring is then placed in the furnace
for the recommended burnout schedule
65
66. BBUURRNN OOUUTT
• Elimination of the wax
pattern from the mold of set
investment is referred to as a
burnout.
• Ring may be placed on a
raised object within the oven
to completely eliminate the
wax & form a cavity into
which the molten metal is
cast.
• Oven is preheated to approx.
400 degree C for 20 mins.
• Temperature raised slowly to
700 degree C for 30 mins.
66
67. a) For gypsum investment.
500 degree c - hygroscopic expansion
tech.
700 degree c - thermal expansion
tech.
b) For phosphate investment 700 - 1030
degree c
c) Ethyl silicate bonded investment- 1090
degree c
67
68. The ring should be maintained long
enough at the maximum temperature
(“heat soak”) to minimize a sudden drop
in temperature upon removal from the
oven.
Such a drop could result in an incomplete
casting because of excessively rapid
solidification of the alloy as it enters the
mold.
68
69. If materials used during the casting process didn't
shrink or expand, the size of the final cast
restoration would be the same as the original wax
pattern. The management of dimensional changes is
complex, but can be summarized by the equation:
wax shrinkage + metal shrinkage = wax
expansion + setting expansion +
hygroscopic expansion + thermal expansion
.
69
70. CCaassttiinngg
Casting of an alloy into the mold space
uses 2 basic requirements:
A) Heat source – to melt the alloy
B) Casting force – to force molten alloy
into mold
70
71. Casting force > surface tension of alloy
+ resistance offered by gas in the
mold
This can be done by use of following
different type of force-
Vacuum force
Air or Gas Pressure
Centrifugal force
71
72. Melting temp of pure gold –1063⁰c
Melting temp of gold alloy-924-960⁰c
Melting temp of base metal alloy-1155-1304⁰c
72
73. A) Heat Source: Different types of materials
and method are used as heat source to melt
alloy. Two basic modes are by using
1) Torch flame–
Gas air
Gas oxygen
Air acetylene
Oxygen acetylene.
hydrogen oxygen generator
2) Electricity
73
74. MMEETTHHOODDSS OOFF MMEELLTTIINNGG AALLLLOOYY
A)TORCH
MELTING
-For low
temperature
metals
-Mixture of
natural/artificial
gas, oxygen/tank
gas –oxyacetylene
Less faster than
electric heating but
more faster than
resistance heating.
B) ELECTRIC MELTING
-For higher temperature
metals.
electric resistance
melting, induction
melting.
melts alloy faster,& can
be easily over heated
74
75. 75
Two type of torch tips:
1.Multi-orifice
2.Single-orifice
Zones of the blow torch flame:
Zone 1 - colorless zone /Non combustion zone
Zone 2 – Combustion zone
Zone 3 – Reducing zone
Zone 4 - oxidizing zone
76. MMeellttiinngg mmeetthhooddss
Gas air torch: -Gas-air torch is used to
melt conventional noble metal alloys
(used for inlays, crown and bridge) whose
melting points less than 1000⁰c
76
77. GGaass ooxxyy ttoorrcchh::
Used to melt metal
ceramic alloys of higher temperature
up to 1200⁰c
The tip of torch is available as
single orifice/multiorifice. The
oxygen pressure is adjusted to10-
15 psi.
The flame is directed onto metal
with the nozzle of the torch about
1.5 cm away from the metal.
Complete fluid should be obtained
within 30 second at which point
the metal is poured into the
mould.
77
78. OOxxyy aacceettyylleennee ttoorrcchh ::
The actual production of flame can be done by
adjusting the pressure and flow of individual gases .
commonly advised pressure for acetylene nozzle
is 3.5 N/cm2 and oxygen nozzle 7-10 N/cm2
one part of acetylene + 2 and half part of oxygen
The best results are obtained when flame is used
with a distance of 10cm between the face of blow
torch nozzle and the base of crucible.
If distance is reduced to –
- 7.5 mm -slight porosity
- 5 mm -increased porosity due to occluded H2
gas
78
79. CCRRUUCCIIBBLLEESS ::
The Melting of alloy requires a crucible to act
as a platform on which the heat can be
applied to the metal.
79
Clay
Quartz Carbon
80. 1. Clay - High noble & noble metal types
2. Carbon - High noble crown and bridge
alloys also for higher fusing gold-based
metal ceramic alloys.
3. Quartz - Higher fusing, gold based metal ceramic
alloy & palladium alloys.
4. Zirconia – alumina -High fusing alloys of any type :
specially for alloys that have a high melting
temperature or are sensitive to carbon contamination.
(Alloys like High Pd,Pd - Ag ,Ni based or Co based
are included in this category)
80
81. 81
• The crucibles used with noble metal alloys should
not be used for melting base metal alloy
•Crucible should be discarded if it contains large
amount of oxides and contaminants from previous
metals
•Sufficient mass of alloy must be present to sustain
adequate casting pressure---
6gm is typically adequate for premolar and anterior
casting
10gm is adequate for molar casting
83. AAiirr PPrreessssuurree ccaassttiinngg mmaacchhiinnee
Alloy is melted in the hollow left by the crucible
former by torch flame and then air pressure is
applied through a piston.
Carbon dioxide, carbon monoxide or nitrogen
gas can be used.
Pressure of 10-15 psi is usually applied.
84. VVaaccccuumm ccaassttiinngg mmaacchhiinnee
Vaccum is applied through the base beneath the casting
ring and the molten alloy can be drawn into the mold by
NEGATIVE PRESSURE. In this case, the material is
sucked upwards into the mold by a vacuum pump. The
mold in an inverted position from the usual casting
process, is lowered into the flask with the molten metal.
85. CENTRIFUGAL CCAASSTTIINNGG MMAACCHHIINNEE
85
This machine makes use of centrifugal force to thrust the liquid
metal into the mold.
Centrifugal casting is a method of casting parts having axial
symmetry. The method involves pouring molten metal into a
cylindrical mold spinning about its
axis of symmetry. The mold is kept rotating till the metal has
solidified.
Mold material like steels, Cast irons, Graphite may be used.
86. Centrifugal casting is carried out as
follows:
•The mold wall is coated by a refractory
ceramic coating
•Starting rotation of the mold at a
predetermined speed.
•Pouring a molten metal directly into the
mold
•The mold is stopped after the casting has
solidified.
•Extraction of the casting from the mold.
86
87. DDiirreecctt ccuurrrreenntt aarrcc mmeellttiinngg mmaacchhiinnee
The alloy is vacuum
melted & cast by
pressure in an argon
atmosphere.
Direct current arc is
produced between 2
electrodes
Alloy & water cooled
tungsten electrode.
The temperature within
the arc exceeds 4000
˚c, the alloy melts
very quickly.
Disadvantage- alloy can
become overheated.
87
90. VVaaccuuuumm
oorr pprreessssuurree-- aassssiisstteedd
ccaassttiinngg mmaacchhiinnee
Titanium & its alloys require
vacuum arc heating argon
pressure casting machines.
The melting point of
commercially pure titanium is
1671˚c.
In such high temperature ,
either a graphite or water
cooled copper crucible is
used.
To prevent absorption of
gases in its molten state,
titanium is cast in the
protective atmosphere of
argon or in vacuum.
90
94. SSaannddbbllaassttiinngg ::
The casting is held in a sandblasting
machine to clean the remaining
investment from its surface.
94
95. CClleeaanniinngg tthhee ccaassttiinngg
• After the casting has solidified the ring is
removed and quenched in water. This
leaves the cast metal in annealed
condition resulting in a porous, soft,
granular investment that is easily
removed .(Gold alloys)
• Often the surface of casting appears dark
with oxides and tarnish, such a film can be
removed by process called pickling.
95
96. PPiicckklliinngg
Heating a discolored casting in an acid.
Mask the dark/tarnished appearance of adherent oxide.
Solution used-
1.(50%) dil HCL,
2. (50%) dil Sulphuric acid,
Others –ultrasonic device.
96
97. Disadvantages of hydrochloric acid :
It is a health hazard
Fumes from the acid are likely to corrode the clinic and
laboratory metal furniture
Dilute hydrochloric acid should not be used unless
necessary neutralizing solutions are immediately at hand
It causes irreversible tissue injury.
Ultrasonic pickling can be carried out while the
prostheses is sealed in a Teflon container
Best method of pickling- the casting is placed in a test
tube and acid is poured
97
99. TTrriimmmmiinngg && ppoolliisshhiinngg ::
The casting is trimmed , shaped and smoothen
with suitable burs or stones.
The sprue is sectioned off with a cutting disc.
White stone ,rubber wheels, rubber disks, and
fine grit are included in the finishing and polishing
agents
99
100. IInnssppeeccttiioonn && ffiinniisshhiinngg ooff ccaassttiinngg
A) Inner surface ( which will be in contact with the
prepared surface of the tooth)should be carefully
examined under higher magnification & illumination for
any discrepancy.
B) Tiny air bubbles in the investment create very minute
nodules on the inner surface, which interfere with the
fitting of the casting.
100
101. C) Improper coating of inner surface of a narrow wax
pattern with investment material may result in
entrapment of large volume of air.
This will result in large nodule over the metal blocking the
whole inner surface.
101
In 1907- Dr. Willam H. Taggart of Chicago, advocated the use of lost- wax technique.
1932- Classification of gold based casting alloys into type1,2,3,4 by national bureau of standards. This was accepted by ANSI/ADA sp.no.5.
In 1907- Dr. Willam H. Taggart of Chicago, advocated the use of lost- wax technique.
1932- Classification of gold based casting alloys into type1,2,3,4 by national bureau of standards. This was accepted by ANSI/ADA sp.no.5.
Device is more commonly used for melting base metal alloys.