This document discusses metals and alloys used in dentistry. It defines key terms related to the mechanical properties of metals like ductility, hardness, strength and elasticity. It describes how alloys are classified based on their composition and properties. Common alloys used in dentistry include noble metal alloys like gold-based and palladium-based alloys, and base metal alloys like nickel-chromium and cobalt-chromium alloys. The document traces the history of alloy use and development in dentistry from gold to newer alloys that are stronger, cheaper and better suited for applications like metal-ceramic restorations and removable partial dentures.
One of the welding processes that used in Engineering field is the brazing. Soldering is similar to the brazing but there are several differences.
Thanks for the colleagues who give this slides to publish.
One of the welding processes that used in Engineering field is the brazing. Soldering is similar to the brazing but there are several differences.
Thanks for the colleagues who give this slides to publish.
1.Introduction
2.Historical perspective
3.Classification
4.Desirable properties
5.Functional mechanical properties
6.Alloys for
A]. All Metal Prosthesis
B]. Resin – Veneered Metal Restoration
7. High noble and noble alloys for Metal- Ceramic Prosthesis
8. Alternative Technologies for fabricating prosthesis
Biological Hazards and precautions – risks of dental laboratory
technician
10. Guidelines for selection and use of base metals for crown and
bridge applications.
11. Partial denture alloys and guidelines for selection
12. Alternatives technologies for fabricating prosthesis
13. Recent advancements
Base-Metal-Alloys used in dentistry..pptxKalpanaNunia1
Dentists should be aware of the corrosion properties and biocompatibility of any alloy they use.
In the absence of detailed data on corrosion for an alloy, use of high-noble and noble alloys of single-phase microstructure will minimize biologic risk.
Patients with Ni allergy may have sensitivity for cobalt. Such patients should be tested to rule out allergy before giving Co-Cr restoration.
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.
Dental casting alloys/ rotary endodontic courses by indian dental academyIndian dental academy
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.
PRESENTATION ON GOLD ALLOYS USED IN DENTISTRY. USEFUL FORALLBRANCHES OF DENTISTRY SPECIALLY PROSTHODONTICS AND CONSERVATIVE DENTISTRY. INCLUDES VARIOUS CATEGORIES OF ALLOYS AND THEIR ADVANTAGES, DISADVANTAGES, USES ETC.
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.
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!
MANAGEMENT OF ATRIOVENTRICULAR CONDUCTION BLOCK.pdfJim Jacob Roy
Cardiac conduction defects can occur due to various causes.
Atrioventricular conduction blocks ( AV blocks ) are classified into 3 types.
This document describes the acute management of AV block.
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.
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
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
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
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
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
2. Ductility: the ability of a material to withstand permanent
deformation under a tensile load without rupture; ability of a
material to be plastically strained in tension.
Malleable : capable of being extended or shaped with a
hammer or with the pressure of rollers.
Vickers hardness number: (VHN) a measure of hardness
obtained with a diamond pyramidal indenter with a square
base and an angle of 136. VHNis proportional to the ratio of
the applied load to the area of the indentation. Devised in the
1920’s by engineers at Vickers, Ltd. in the United Kingdom
3. Modulus of elasticity : in metallurgy, the coefficient found by
dividing the unit stress, at any point up to the proportional
limit, by its corresponding unit of elongation (tension) or
strain. A ratio of stress to strain. As the modulus of elasticity
rises, the material becomes more rigid
Tensile stress : the internal induced force that resists the
elongation of a material in a direction parallel to the direction
of the stresses
Proportional limit : that unit of stress beyond which
deformation is no longer proportional to the applied
4. Corrosion resistance :A material's ability to resist deterioration
caused by exposure to an environment .
Elongation at break also known as fracture strain, is the ratio
between changed length and initial length after breakage of
the test specimen. It expresses the capability of a material to
resist changes of shape without crack formation
Sag resistance: the resistance to flow of a one-inch plug of
uncured sealant after being placed on a vertical plane.
yield strength : the strength at which a small amount of
permanent (plastic) strain occurs, usually 0.1% or 0.2%, and
most frequently measured in MPa or psi
5. INTRODUCTION
In dentistry, metals represent one of the three
major classes of materials used for the
reconstruction of damaged or missing oral
tissues. Although metals are readily
distinguished from ceramics and polymers.
6. An opaque lustrous chemical
substance
that is a good conductor of heat and
electricity and, when polished, is a
good reflector of light.
- The Metals Handbook
(1992)
7. An alloy is a substance with metallic
properties that consists of two or more
chemical elements, at least one of
which is a metal.
The Metals Handbook (1992)
8. PROPERTIES
Exhibits a luster
Good thermal and electrical
conductors
High fracture toughness (KIc)
Ductile
Malleable
The Metals Handbook (1992)
9. Highly resistant to corrosion and
oxidation (Noble metals e.g. gold,
iridium, osmium, palladium, platinum,
rhodium, and ruthenium)
Most metals have a “white”
appearance (e.g., aluminium, silver,
nickel, palladium, tin, and zinc.) Non
white metal e.g. Gold and Copper
The Metals Handbook (1992)
10. CLASSIFICATION
HIGH MELTING
HEAVY METALS
LIGHT METALS
NOBLE METALS
( HEAVY METALS)
BRITTLE DUCTILE
www.bpc.edu
11. ALLOYS
A crystalline substance with metallic
properties that is composed of two or
more chemical elements, at least one
of which is a metal.
Pure metals are rarely used in
dentistry because they are weaker
than they are when mixed with other
metals.
APPLIED DENTAL MATERIALS –McCABBES AND WALLS
12. CLASSIFICATION
ADA CLASSIFICATION OF THE DENTAL
CASTING ALLOY:
• High noble alloys “precious metals”
◦ at least 60% noble. 40% of which is gold. The
remaining 40% is base metal
Noble alloys(semiprecious)
◦ at least 25% noble (no gold requirements). 75%
base metal
Base metal alloys
◦ Less than 25% noble
13. National Bureau of Standards
Type I (Soft, Vickers hardness number
[HV] between 50 and 90)
Type II (Medium, HV between 90 and
120)
Type III(Hard, HV between 120 and
150)and
Type IV (Extra Hard, HV ≥150).
APPLIED DENTAL MATERIALS –McCABBES AND WALLS
14. ALLOY TYPES BY
DESCRIPTION
A) CROWN AND
BRIDGE ALLOYS
1. Noble metal alloys:
i)Gold based alloy -
type III and type IV
gold alloys , low gold
alloys
ii) Non-gold based alloy-
Silver -palladium alloy
2. Base metal alloys:
i) Nickel-based
alloys
ii) Cobalt based
alloys
3. Other alloys:
i) Copper-zinc with
Indium and nickel
ii) Silver-indium with
palladium
B) METAL CERAMIC
ALLOY
. Noble metal alloys
for porcelain
bonding:
i) Gold-platinum -
palladium alloy
ii) Gold-palladium-silver
alloy
iii) Gold-palladium
alloy
iv) Palladium silver alloy
v) High palladium alloy
2. Base metal alloys
for porcelain
bonding:
i) Nickel -chromium
alloy
C) REMOVABLE
PARTIAL DENTURE
ALLOY
Although type-IV noble
metal alloy may be
used, majority of
removable partial
framework are made
from base metal
alloys:
1. Cobalt-chromium alloy
2. Nickel-chromium
alloy
3. Cobalt-chromium-nickel
alloy
4. Silver-palladium
alloy
5. Aluminum -bronze
15. Classification of alloys for All-Metal restorations, metal ceramic restorations, and
frameworks for removable partial dentures.
Alloy type All-metal Metal-ceramic Removable partial
dentures
High noble Au-Ag-Cu-Pd Au-Pt-Pd Au-Ag-Cu-Pd
Metal ceramic alloys Au-Pd-Ag (5-12wt%
Ag)
Au-Pd-Ag (>12wt%Ag)
Au-Pd (no Ag)
Noble Ag-Pd-Au-Cu Pd-Au (no Ag) Ag-Pd-Au-Cu
Ag-Pd Pd-Au-Ag Ag-Pd
Metal-ceramic alloys Pd-Ag
Pd-Cu
Pd-Co
Pd-Ga-Ag
Base Metal Pure Ti Pure Ti Pure Ti
Ti-Al-V Ti-Al-V Ti-Al-V
Ni-Cr-Mo-Be Ni-Cr-Mo-Be Ni-Cr-Mo-Be
Ni-Cr-Mo Ni-Cr-Mo Ni-Cr-Mo
Co-Cr-Mo Co-Cr-Mo Co-Cr-Mo
Co-Cr-W Co-Cr-W Co-Cr-W
16. ALLOY TYPE BY MAJOR ELEMENT: Gold-based, palladium-based,
silver-based, nickel-based, cobalt-based and titanium-based
.
ALLOY TYPE BY PRINCIPAL THREE ELEMENTS: Such as
Au-Pd-Ag, Pd-Ag-Sn, Ni-Cr-Be, Co-Cr-Mo, Ti-Al-V and Fe-Ni-
Cr.
(If two metals are present, a binary alloy is formed; if three
or four metals are present, ternary and quaternary alloys,
respectively, are produced and so on.)
ALLOY TYPE BY DOMINANT PHASE SYSTEM: Single
phase [isomorphous], eutectic, peritectic and intermetallic.
17. HISTORY AND ITS
PRESPECTIVE
THE LOST-WAX PROCESS(1905)
"investment casting", "precision casting",
or cire perdue in French
Presented by Taggart
First used in dentistry for Inlay fabrication
A duplicate metal structure is cast from wax
model or a copy of the wax model
Examples: Taggart cast inlay (1907)
: Cave of the Treasure in Israel
http://en.wikipedia.org/wiki/Lost-wax_casting
18. Use of Gold made it more expensive
Performance compromised
Not good aesthetics
APPLIED DENTAL MATERIALS –McCABBES AND WALLS
19. Co-Cr replacement to Gold
(1933)
Used as base metal for removable partial
denture
Lighter in weight
Greater stiffness(elastic modulus)
Cheaper than gold alloy
PHILLIPS DENTAL MATERIALS
20. Porcelain-Fused-to-Metal
Process (1959)
platinum and palladium were added into
gold alloy
Lowered the coefficient of thermal
expansion
Increased biocompatibility with porcelain
Thermally compatible metal-porcelain was
made
PHILLIPS DENTAL MATERIALS
21. The Gold Standard (1971)
Response to the increasing price of
gold introduced following changes:
1. Gold was replaced with palladium.
2. Palladium eliminated gold entirely.
3. Base metal alloys with nickel as the
major element eliminated the
exclusive need for noble metals
The United States abandoned the gold
standard in 1971.
APPLIED DENTAL MATERIALS –McCABBES AND WALLS
22. The Medical and Dental
Devices Act (1976)
Dental industry became under control of the
FDA
Dental alloy for prosthesis was classified as
passive implants
Manufactures were required to have a
quality system
-Organizations engaged in preparing standards for dental
materials ( George Corbley Paffenbarger )
23. Desirable Property of Dental
casting alloy
Biocompatible : The material must
tolerate oral fluids and not release any
harmful products into the oral
environment.
Should have good corrosion
resistance
Good tarnish resistance
APPLIED DENTAL MATERIALS –McCABBES AND WALLS
24. Non-allergic
Good aesthetics
Must have adequate thermal
properties to tolerate
Melting range should be low enough
to form smooth surface with the mould
walls
Economic and easily available
APPLIED DENTAL MATERIALS –McCABBES AND WALLS
25. NOBLE METALS
Periodic table of the element shows
eight noble metals gold, the platinum
group metals (platinum, palladium,
rhodium, ruthenium, iridium, osmium),
and silver.
26. GOLD
Oldest dental restorative materials
Used since 4000 years
Phoenician used gold wire to bind
teeth
Etruscan and then roman used gold
strip to make fixed bridges
Atomic number is 79
Au – symbol
27. Gold content:
Traditionally the gold content of dental
casting alloys have been referred to in terms
of:
Karat
Fineness
Karat:
It is the parts of pure gold in 24 parts of alloys.
For Eg: a) 24 Karat gold is pure gold
b) 22 Karat gold is 22 parts of
pure gold and remaining 2 parts of
other metal.
The term Karat is rarely used to describe gold
content in current alloys.
Fineness:
Fineness of a gold alloy is the parts per
thousand of pure gold. Pure gold is 1000 fine.
Thus, if ¾ of the gold alloy is pure gold, it is
said to be 750 fine
28. OCCURANCE
The metal occurs often in free
elemental (native) form, as nuggets or
grains in rocks, in veins between two
rocks and in alluvial deposits. Less
commonly, it occurs in minerals as
gold compounds, such as
with tellurium as calaverite, sylvanite
and krennerite
29. PROPERTIES
Dense
Soft
Ductile
Most malleable : 1 gram can be
beaten into 1 square meter
Lustre
Most corrosion resistant
30. USES
Dental wires to support mobile tooth
by Romans , Greeks , Arabs (5th
century BC to 11th century AD)
Reduce and fix fractured mandible
during world war
Filling teeth with gold foils
Inlay and onlay
Crown and bridges
31. GOLD CASTING ALLOYS:
ADA specification No. 5 classify dental gold casting
alloys as:
1. High Gold Alloys Type I
Type II
Type III
Type IV
2.Low Gold Alloys
3. White Gold Alloys
INLAY GOLD ALLOY
CROWN AND BRIDGE ALLOY
32. CASTING GOLD ALLOYS
TYPE 1 GOLD ALLOY
Soft
Strength – 50 to 90 HV
Casting subjects to very slight strength
34. PROPERTY
Hardness (VHN) 50–90
Modulus of elasticity (GPa) 80
Tensile strength (MPa) 250
Proportional limit (MPa) 120
Elongation at break (%) 35
Melting range (ºC) 950–1100
35. USES
Inlay ( class 1, III , V cavities)
Electroforming
Gold foil for direct restoration
Telescopic crown
36. TYPE II
COMPOSITION
Gold (Au) 75%
Silver (Ag) 12%
Copper (Cu) 10%
Platinum/ palladium (Pt/Pd) 02
Zinc (Zn) 1%
37. PROPERTY
Hardness (VHN) 90-120
Modulus of elasticity (GPa) 80
Tensile strength (MPa) 340
Proportional limit (MPa) 200
Elongation at break % 25
Melting range (ºC) 900-980
38. USES
These are used for conventional inlay or
onlay restorations subject to moderate
stress, thick three quarter crowns,
pontics and full crowns. These are
harder and have good strength.
39. TYPE III
COMPOSITION
Gold (Au) 70%
Silver (Ag) 14%
Copper (Cu) 10%
Platinum/ palladium (Pt/Pd) 05
Zinc (Zn) 1%
40. PROPERTY
Hardness (VHN) 120 -160
Modulus of elasticity (GPa) 85
Tensile strength (MPa) 360
Proportional limit (MPa) 290
Elongation at break % 20
Melting range (ºC) 900-1000
41. USES
Inlays subject to high stress and for
crown and bridge in contrast to type I
and type II
42. TYPE IV
COMPOSITION
Gold (Au) 65%
Silver (Ag) 09%
Copper (Cu) 15%
Platinum/ palladium (Pt/Pd) 10%
Zinc (Zn) 1%
43. PROPERTY
Hardness (VHN) 150-230
Modulus of elasticity (GPa) 100
Tensile strength (MPa) 750
Proportional limit (MPa) 500
Elongation at break % 8
Melting range (ºC) 870-950
44. USES
These are used in areas of very high
stress, crowns and long span bridges. It
has lowest gold content of all four type
(Less than 70%) but has the highest
percentage of silver, copper, platinium
and Palladium. It is most responsive to
heat treatment and yield strength but
lowers ductility.
45. Comparative properties of
casting gold alloys
Hardness , Proportional limit , Strength
Type IV > Type III > Type II > Type I
Ductility and Corrosion resistance
Type I > Type II > Type III > Type IV
46. LOW GOLD CONTENT ALLOY
SILVER PALLADIUM ALLOY
Contains no gold
25% palladium
Contains small quantity of copper, zinc,
indium
Low density that affects the castability
Low ductility,
less corrosion resistance
47. Property Ag/Pd Gold (type
3)
Hardness (VHN) 120–220 120–
160
Modulus of elasticity (GPa) 80–95 85
Proportional limit (MPa) 250 290
Elongation at break (%) 3–25 15–
25
Melting range (ºC) 900–1100 900–
1000
Density (g cm−3) 11–12 15–16
48. METAL CERAMIC ALLOYS
The main function of metal-ceramic
alloys is to reinforce porcelain, thus
increasing its resistance to fracture.
49. REQUIREMENT
1.They should be able to bond with
porcelain
2.Its coefficient of thermal expansion
should be compatible with that of
porcelain
3.Its melting temperature should be
higher than the porcelain
4.It should not stain or discolor
porcelain
50. The Gold-Platinum-Palladium (Au-Pt-Pd)
System:
This is one of the oldest metal ceramic alloy
system. But these alloys are not used widely
today because they are very expensive.
COMPOSITION
Gold – 75% to 88%
Palladium – Upto 11%
Platinum – Upto 8%
Silver – 5%
Trace elements like Indium, Iron and Tin for porcelain bonding.
51. Gold-Palladium-Silver (Au-Pd-Ag) System:
These alloys were developed in an attempt to overcome
the major limitations in the gold-platinum-palladium system
(mainly poor sag resistance, low hardness & high cost)
Two variations on the basic combination of gold, palladium
and silver were created and are identified as either high-silver
or low-silver group.
Composition (High Silver Group):
Gold – 39% to 53%
Silver – 12% to 22%
Palladium – 25% to 35%
Trace amount of oxidizable elements are added for porcelain
bonding.
52. Composition (Low Silver Group):
Gold – 52% to 77%
Silver- 5% to 12%
Palladium – 10% to 33%
Trace amounts of oxidizable elements for porcelain
bonding.
53. Gold-Palladium (Au-Pd) System:
This particular system was developed in an attempt to
overcome the major limitations in the Au-Pt-Pd
system and Au-Pd-Ag system. Mainly-
-Porcelain discoloration.
-Too high coefficient of thermal expansion &
contraction.
COMPOSITION
Gold – 44% to 55%
Gallium – 5%
Palladium – 35% to 45%
Indium & Tin – 8% to 12%
Indium, Gallium and Tin are the oxidizable elements
responsible for porcelain bonding.
54. Palladium-Silver (Pd-Ag) System
This was the first gold free system to be introduced in the
United States (1974) that still contained a noble metal
(palladium). It was offered as an economical alternative
to the more expensive gold-platinum-silver and gold-palladium-
silver (gold based) alloy systems.
Composition: (available in two compo.)
1. Palladium – 55% to 60% Silver – 25% to 30%
Indium and Tin
2. Palladium – 50% to 55% Silver – 35% to 40%
Tin (Little or no Indium)
Trace elements of other oxidizable base elements are
also present.
55. BASE METAL ALLOYS
-Nickel based
-Cobalt based
Alloys in both systems contain chromium as the second largest
constituent.
A classification of base metal casting alloys
Base metal
Casting alloy
Removable
Partial denture
Co-Cr
Co-Cr-Ni
Ni-Cr
Co-Cr-Mo
Surgical
Implant
Ni-Cr
Fixed
Partial denture
56. Cobalt-chromium alloys
These alloys are also known as ‘satellite’
because they maintained their shiny,
star-like appearance under different
conditions.
They have bright lustrous, hard, strong
and non-tarnishing qualities.
57. The chemical composition of these
alloys specified in the ISO Standard
for Dental Base Metal Casting is as
follows:
Cobalt main constituent
Chromium no less than 25%
Molybdenum no less than 4%
Cobalt + nickel + chromium no less
than 85%
58. COMPOSITION
Cobalt - 55 to 65%
Chromium - 23 to 30%
Nickel - 0 to 20%
Molybdenum - 0 to 7%
Iron - 0 to 5%
Carbon - upto 0.4%
Tungsten, Manganese, Silicon and Platinum
in traces
59. The main purpose of the chromium is
to further harden the alloy by solution
hardening and also to impart corrosion
resistance.
Silicon – Increases ductlity
Molybdenum and beryllium refine the
grain structure and improve the
behaviour of base metal alloys during
casting
60. Carbon – controls the brittleness and
ductility
These alloys are also known as
‘satellite’ because they maintained
their shiny, star-like appearance under
different conditions
61. The Cobalt-Chromium alloys have
replaced Type IV gold alloys because
of their lower cost and adequate
mechanical properties. Chromium is
added for tarnish resistance since
chromium oxide forms an adherent
and resistant surface layer.
62. PHYSICAL PROPERTY
lighter in weight – lesser density
8 to 9 gms/cm3.
Fusion temperature: The casting temperature
of this alloy is considerably higher than that
of gold alloys. 1250oC to 1480oC.
63. A.D.A. specification No. 14 divides it into
two types, based on fusion temperature
(which is defined as the liquidus
temperature)
Type-I (High fusing) – fusing temperature greater
than 1300oC
Type-II (Low fusing)– fusing temperature lower
than 1300oC
64. Mechanical Properties:
Yield strength: It is higher than that of gold alloys.
710Mpa (103,000psi).
Elongation: Ductlity is low ranges from 1 to 12%.
These alloys work harden very easily, so care must
be taken while adjusting the clasp arms of the partial
denture
Hardness: 432 VHN.
Thus, cutting, grinding and finishing is difficult.
65. Modulus of elasticity: 22.5103Mpa. Due to high modulus
of elasticity casting can be made more thinner, thus
decreasing the weight of the R.P.D. Adjustment of clasp
is not easy.
Tarnish and corrosion resistance: Formation of a layer of
chromium oxide on the surface of these alloys prevents
tarnish and corrosion in the oral cavity.
Solutions of hypochlorite and other compounds that are
present in some denture-cleaning agents will cause
corrosion in such base metal alloys.
Even the oxygenating denture cleansers will stain such
alloys.
Therefore, these solutions should not be used for cleaning
cobalt-chromium base alloys.
66. Casting Shrinkage: The casting shrinkage is much
greater than that of gold alloys (2.3%), so limited
use in crown & bridge.
The high shrinkage is due to their high fusion
temperature.
Porosity: As in gold alloys, porosity is due to
shrinkage and release of dissolved gases which is
not true in case of Co-Cr alloys.
Porosity is affected by the composition of the alloys
and its manipulations.
67.
68. APPLICATIONS:
1. Denture base
2.Cast removable partial denture framework.
3. Surgical implants.
4. Car spark plugs and turbine blades.
69. Nickel-chromium (Ni-Cr) System
The major constituents are nickel and chromium, with
a wide array of minor alloying elements.
The system contains two major groups:
-Beryllium free (class 1)
-Beryllium (class 2)
Of the two, Ni-Cr-Beryllium alloy are generally
regarded as possessing superior properties and
have been more popular
70. The chemical composition of these alloys
specified in the ISO Standard for Dental
Base Metal Casting Alloys:
Nickel main constituent
Chromium no less than 20%
Molybdenum no less than 4%
Beryllium no more than 2%
Nickel + cobalt + chromium no less than 85%
71.
72. NICKEL-CHROMIUM
BERYLLIUM FREE
ALLOYS
Composition:
Nickel – 62% to 77% Chromium –
11% to 22%
Boron, molybdenum, Niobium,
columbium and tantalum (trace
elements).
73. Advantages
1. Do not contain beryllium which is
harmful to technician and patient
2. Low cost
3. Low density means more casting
per ounce
74. Disadvantages
1.Cannot use with Nickel sensitive patients.
2.Cannot be etched. (Cr doesn’t dissolve
in acid)
3. May not cast as well as Ni-Cr-Be alloys
4.Produces more oxide than Ni-Cr-Be
alloys.
75. NICKEL-CHROMIUM-BERYLLIUM
ALLOY
Composition:
Nickel – 62% to 82%
Chromium – 11% to 20%
Beryllium – 2.0%
Numerous minor alloying elements
include aluminum, carbon, gallium, iron,
manganese, molybdenum, silicon, titanium
and /or vanadium are present
76. Advantages
1. Low cost
2. Low density, permits more
casting per ounce.
3. High sag resistance
4. Can produce thin casting
5. Poor thermal conductor
6. Can be etched to increase
retention
77. Disadvantages
1.Cannot use with nickel sensitive patients
2.Beryllium exposure can harmful to technicians and
patients.
3. Proper melting and casting is a learned skill.
4. Bond failure more common in the oxide layer.
5. High hardness (May wear opposing teeth)
6. Difficult to solder
8. Difficult to cut through cemented castings
78. TITANIUM
Titanium is called “material of choice” in dentistry.
This is attributed to the oxide formation property
which forms basis for corrosion resistance and
biocompatibility of this material. The term 'titanium'
is used for all types of pure and alloyed titanium.
79. PROPERTY
-Resistance to electrochemical degradation
- Biological response
-Relatively light weight
-Low density (4.5 g/cm3)
-Low modulus (100 GPa)
-High strength (yield strength = 170-480 MPa;
ultimate strength = 240-550 MPa)
-Passivity
-Low coefficient of thermal expansion (8.5 x
106/°C)
-Melting & boiling point of 1668°C & 3260°C
80. USES
Commercially pure titanium is used for
dental implants, surface coatings,
crowns, partial dentures, complete
dentures and orthodontic wires
81. STEEL
Steel is an alloy of iron and carbon in which
the carbon content is less than 2%.
Carbon content makes it brittle
One phase consists of a very dilute solid
solution of carbon in iron (up to 0.02% C),
called ferrite. The other phase is a specific
compound of iron and carbon with formula
Fe3C, called cementite. The mixture of
ferrite and cementite is termed pearlite
82. Eutectic refers to the behaviour of an alloy
of two mutually insoluble metals during
crystallization.
Alloys with greater concentrations of carbon
are called hypereutectoid alloys and those
with smaller carbon contents, hypoeutectoid
alloys.
The hypereutectoid alloys contain relatively
greater amounts of cementite while the
hypoeutectoid alloys contain greater
amounts of ferrite.
Cementite is a very hard, brittle material
whilst ferrite is softer and more ductile
83. SATINLESS STEEL
In addition to iron and carbon the stainless
steels contain chromium which improves
corrosion resistance. This is achieved by
the passivating effect in which the
chromium exposed at the surface of the
alloy is readily oxidized to form a tenacious
surface film of chromic oxide.
Nickel is also present in many stainless
steels. It contributes towards corrosion
resistance and helps to strengthen the alloy.
84. sufficient quantities of these two metals are
incorporated, the austenitic structure
remains even at room temperature.
One of the most commonly used stainless
steels contains 18% chromium and 8%
nickel (termed 18/8 stainless steel).
18/8 stainless steels are used in
applications where heat hardening is not
necessary, for example, for noncutting
instruments, wires and occasionally as
denture bases
85. When smaller quantities of chromium and
nickel are incorporated into steel it is
possible to produce an alloy which has
adequate corrosion resistance but which
can be hardened by heat treatment., 12%
chromium and little or no nickel. is capable
of forming a martensitic stainless steel.
This type of alloy is commonly used to
construct cutting instruments and probes.
86. Stainless steel denture bases
Formed from very thin pressed/rolled
sheets of wrought stainless steel.
The wrought stainless steel sheets have
high values of modulus of elasticity and
proportional limit. This enables sufficient
rigidity to be achieved with a very thin sheet
of material.
Conducts heat through metallic plates thus
ensuring the patient retains normal reflex
reaction to hot and cold
87. 1. THE JOURNAL OF PROSTHETIC DENTISTRY VOLUME 94
NUMBER 1
2. Glossary of prosthodontic terms – 2005
3. Phillips science of dental materials 11th edition – Aunacavice
4. The Use of Gold in Dentistry-J. A. Donaldson
5. Gold Alloys, Uses and Performance-Helmut Knosp
6. APPLIED DENTAL MATERIALS –McCABBES AND WALLS
7. Internet