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.
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
There have been several changes since inception in the field of dental ceramics. Need for newer materials with improved aesthetics, flexural strength and optical properties made it necessary for introduction of advanced technology in fabrication of dental ceramics.
Gypsum Products commercially available are hemihydrate form of calcium sulfate. Gypsum products used in Dentistry are broadly classified into 5 types
Type 1- Impression Plaster
Type 2- Model Plaster
Type 3- Dental stone
Type 4- Die Stone high strength low expansion
Type 5- Die Stone high Strength High Expansion
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.
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
There have been several changes since inception in the field of dental ceramics. Need for newer materials with improved aesthetics, flexural strength and optical properties made it necessary for introduction of advanced technology in fabrication of dental ceramics.
Gypsum Products commercially available are hemihydrate form of calcium sulfate. Gypsum products used in Dentistry are broadly classified into 5 types
Type 1- Impression Plaster
Type 2- Model Plaster
Type 3- Dental stone
Type 4- Die Stone high strength low expansion
Type 5- Die Stone high Strength High Expansion
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.
Gypsum products-a topic of dental materials for dental students....
lots of knowledge...includes classification,uses,manufacturing processes etc.
COURTESY: My college friends....
brief description about pressable ceramicsCONTENTS: • Introduction • Definition For Dental Ceramics • Definition For Pressable Ceramics • History • Various All Ceramic Systems • Classification • Pressable Ceramics • History • Generation Of Pressable Ceramics • Cerestore – Development Fabrication Advantage Disadvantage 2
3. IPS Empress - Materials And Composition Special Furnace Fabrication Advantage Disadvantage IPS Empress 2- INDICATION Properties Fabrication Method Advantage Disadvantage IPS Emax Press - Microstructure Composition Properties OPC 3G- Development Indication Properties 3
4. INTRODUCTION There have been significant TECHNOLOGICAL advances in the field of dental ceramics over the last 10 years which have made a corresponding increase in the number of materials available. Improvements in strength, clinical performance, and longevity have made all ceramic restorations more popular and more predictable 4
5. DEFINITION FOR DENTAL CERAMICS⁶ An inorganic compound with non metallic properties typically consisting of oxygen and one or more metallic or semi metallic elements (e.g ;Aluminium, Calcium, Lithium, Mangnesium, Potassium, Sodium, Silicon, Tin , Titanium And Zirconium)that is formulated to produce the whole or part of a ceramic based dental prosthesis 5
6. DEFINITION FOR PRESSABLE CERAMICS ⁶ • A ceramic that can be heated to a specified temperature and forced under pressure to fill a cavity in a refractory mold 6
7. HISTORY OF DENTAL CERAMICS ⁶ • 1789-first porcelain tooth material by a French dentist De Chemant • 1774- mineral paste teeth by Duchateau in England • 1808-terrometallic porcelain teeth by Italian dentist Fonzi • 1817- Planteu introduced porcelain teeth in US • 1837- Ash developed improved version of porcelain teeth 7
8. • 1903 – Dr.Charless introduced ceramic crowns in dentistry he fabricate ceramic crown using platinum foil matrix and high fusing feldspathic porcelain excellent esthetics but low flexural strength resulted in failure • 1965- dental aluminous core Porcelain by Mclean and Huges • 1984- Dicor by Adair and Grossman 8
9. 9
10. VARIOUS ALL CERAMIC SYSTEMS Aluminous core ceramics Slip cast ceramics Heat pressed ceramics Machined ceramics Machined and sintered ceramics Metal reinforced system 10
11. MICROSTRUCTURAL CLASSIFICATION⁵ Category 1: Glass-based systems (mainly silica) Category 2: Glass-based systems (mainly silica) with fillers usually crystalline (typically leucite or a different high-fusing glass) a) Low-to-moderate leucite-
Soldering and welding are the integral part of dentistry specially in prosthodontics and crown and bridge procedure. it is also used in implant supported prosthetic.
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.
Gypsum products-a topic of dental materials for dental students....
lots of knowledge...includes classification,uses,manufacturing processes etc.
COURTESY: My college friends....
brief description about pressable ceramicsCONTENTS: • Introduction • Definition For Dental Ceramics • Definition For Pressable Ceramics • History • Various All Ceramic Systems • Classification • Pressable Ceramics • History • Generation Of Pressable Ceramics • Cerestore – Development Fabrication Advantage Disadvantage 2
3. IPS Empress - Materials And Composition Special Furnace Fabrication Advantage Disadvantage IPS Empress 2- INDICATION Properties Fabrication Method Advantage Disadvantage IPS Emax Press - Microstructure Composition Properties OPC 3G- Development Indication Properties 3
4. INTRODUCTION There have been significant TECHNOLOGICAL advances in the field of dental ceramics over the last 10 years which have made a corresponding increase in the number of materials available. Improvements in strength, clinical performance, and longevity have made all ceramic restorations more popular and more predictable 4
5. DEFINITION FOR DENTAL CERAMICS⁶ An inorganic compound with non metallic properties typically consisting of oxygen and one or more metallic or semi metallic elements (e.g ;Aluminium, Calcium, Lithium, Mangnesium, Potassium, Sodium, Silicon, Tin , Titanium And Zirconium)that is formulated to produce the whole or part of a ceramic based dental prosthesis 5
6. DEFINITION FOR PRESSABLE CERAMICS ⁶ • A ceramic that can be heated to a specified temperature and forced under pressure to fill a cavity in a refractory mold 6
7. HISTORY OF DENTAL CERAMICS ⁶ • 1789-first porcelain tooth material by a French dentist De Chemant • 1774- mineral paste teeth by Duchateau in England • 1808-terrometallic porcelain teeth by Italian dentist Fonzi • 1817- Planteu introduced porcelain teeth in US • 1837- Ash developed improved version of porcelain teeth 7
8. • 1903 – Dr.Charless introduced ceramic crowns in dentistry he fabricate ceramic crown using platinum foil matrix and high fusing feldspathic porcelain excellent esthetics but low flexural strength resulted in failure • 1965- dental aluminous core Porcelain by Mclean and Huges • 1984- Dicor by Adair and Grossman 8
9. 9
10. VARIOUS ALL CERAMIC SYSTEMS Aluminous core ceramics Slip cast ceramics Heat pressed ceramics Machined ceramics Machined and sintered ceramics Metal reinforced system 10
11. MICROSTRUCTURAL CLASSIFICATION⁵ Category 1: Glass-based systems (mainly silica) Category 2: Glass-based systems (mainly silica) with fillers usually crystalline (typically leucite or a different high-fusing glass) a) Low-to-moderate leucite-
Soldering and welding are the integral part of dentistry specially in prosthodontics and crown and bridge procedure. it is also used in implant supported prosthetic.
Gypsum products/certified fixed orthodontic courses by Indian dental academy Indian 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 provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
Orthodontic wires 1 /certified fixed orthodontic courses by Indian dental aca...Indian 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 provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
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.
Classification of impression materials انواع مواد الطبعDenTeach
خاص بمادة Dental material
تقسيمة مختصرة ملمة بأنواع المواد المستخدمة في اخذ طبعة للفم والاسنان
SUBJECTIVE:- Dental Material
CHAPTER:- Impression Material
تمت مشاركته عبر: د. أحمد طه
Creative Safety Supply shares how you best to proceed with a Lockout Tagout scenario, ensuring the highest level of safety for your workers and employees. Are you following these standardized safe steps? https://www.lean-news.com/tools-continuous-improvement/
If you want to see some LOTO accessories, equipment and devices used to ensure compliance with standard safe identification, shutdown and maintenance of a defect piece of equipment, than read through this slide deck.
Dentalcasting alloys/certified fixed orthodontic courses by Indian dental aca...Indian 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.for more details please visit
www.indiandentalacademy.com
Die materials and technique of fabrication/cosmetic dentistry course by India...Indian 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.
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.
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.
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.
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.
A comprehensive lecture by Dr Rashid Hassan covering all the aspects of different types of model and die materials. Easy ti understand ans recall.
For video lectures on different topics of Dental Materials visit and follow Dr Rashid Lectures on Dental Materials (dmbydrrashid) on Facebook.
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
Die materials in fpd /certified fixed orthodontic courses by Indian dental ac...Indian 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.
Luting agents for fixed prosthodontics/ orthodontic course by indian dental a...Indian 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.
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
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.
Pickling is heating the discolored casting in an acid.
The best pickling solutions for gypsum bonded investments is a 50% hydrochloric acid solution.
The hydrochloric acid aids in the removal of any residual investment, as well as of the oxide coating.
The disadvantage of hydrochloric acid is that the fumes from the acid are likely to corrode laboratory metal furnishings. In addition, these fumes are a health hazard and should be vented via a fume hood.
A solution of sulfuric acid may also be more advantageous in this respect.
Ultrasonics are also useful for cleaning the casting.
TERMINOLOGY
DESIRABLE QUALITIES
CLASSIFICATION
GYPSUM PRODUCTS
RESIN DIE MATERIALS
ELECTROFORMED DIE
AMALGAM DIE
METAL SPRAYED DIE
SILICOPHOSPHATE DIE
DIE SYSTEMS
RECENT ADVANCES
CONCLUSION
REFERENCES
Gypsum products /certified fixed orthodontic courses by Indian dental academy Indian 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 provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
00919248678078
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
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 Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
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
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Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
2. Gypsum Products
Used extensively in dentistry to make dental models.
Obtained from natural gypsum rock (dihydrate form
of Calcium sulfate CaSO4 . 2H2O)
CaSO4 . 1/2H2O + 1 1/2 H2O
CaSO4 . 2H2O +
3900 cal/g mol
3. Dental Models
Three-dimensional reproductions of the teeth
and the surrounding soft tissue of a
patient’s
maxillary and mandibular arches.
Also referred to as study casts.
http://practicon.com/images/products/1_40132_FS.jpg
4. Use of Dental Models
Diagnosis for a fixed or removable
prosthetic.
http://www.summitdentalarts.com/media/7796/plaster-cast.gif
Diagnosis of orthodontic treatment.
Visual presentation of dental
treatment.
http://upload.wikimedia.org/wikipedia/commons/f/f1/Steg_ok_2a.jpg
Making of custom trays.
Making of orthodontic appliances.
http://roguedentalsolutions.com/web/wp-content/gallery/
photo-gallery/pauls-work-007.jpg
5. Ideal Requirements
Should have:
- Sufficient strength to prevent accidental
breakage.
- Sufficient hardness to avoid surface damage
during use.
Should produce fine details and sharp margins
of the impression.
6. Should show little dimensional change on
setting and remain dimensionally stable.
Should be compatible with the impression
materials. (No interaction between the
impression surface and the model surface)
Should have good color contrast with the other
materials being used.
Should be cheap and easily used.
10. Model plaster: commonly called plaster of Paris, is
used primarily for pouring preliminary impressions
and the making of diagnostic models.
Dental stone: for use as a working model when a
more durable diagnostic cast is required. Examples
are in the making of custom trays and orthodontic
appliances.
11. High‑strength stone: also known as densite or
improved dental stone. Its strength, hardness,
and dimensional accuracy make it ideal to
create the dies used in the production of
crowns, bridges, and indirect restorations.
http://heraeus-dental.com/media/webmedia_local/image/650/Internet_Gipse_650_g_res_650.jpg
13. Chemical Reaction
Gypsum
Plaster
D Stone
high-strength DS
Mix water
37-50
28-32
19-24
Required water
18.6
18.6
18.6
The chemical reaction takes place
the amount of water needed.
Excess water
18-31
9-13
0-5
determine
Water thick mix, difficult to handle, trap air
bubbles but the set gypsum usually strong.
Water Thinner mix, porous easily handle, but
the set gypsum is inferior.
14. W/P Ratio for DS and
High Strength DS
Crystal shapes and concentration play a major
role in W/P ratio needed to obtain a workable
consistency.
15. Mechanism of Setting
Different solubility between CaSO4 . 2H2O &
CaSO4 . 1/2H2O.
CaSO4 . 1/2H2O + H2O
Supersaturation
Nucleation process ( needle-like crystals)
Bonding between contacting crystals
Final
cohesion.
17. Effect of Spatulation
Definite effect on the setting time and setting
expansion.
amount of spatulation
setting time
http://www.whipmix.com/img/Product_img/vacuum_mixing.jpg
18. Effect of Temperature
Temp. of the mixing water as well as the temp.
of the environment affect the setting time in
one of two ways:
1. Change in the solubility of CaSO4 . 2H2O &
CaSO4 . 1/2H2O.
- solubility ratio
setting time.
slow the reaction
20. 2. Change in the Ion mobility:
- Temp.
sol. & mobility of Ca++ & SO4-reaction rate
setting time.
- at 100°C
rate of reaction decreased and
the the setting time is lengthened.
21. Effect of Humidity
When humidity reaches 70% and above:
the moist convert CaSO4 . 1/2H2O into CaSO4 .
2H2O which will act as extra centers of nucleation,
thus accelerating the reaction.
Further contamination
CaSO4 . 1/2H2O
amount of available of
retarding the reaction.
22. Effect of Colloidal
Systems & PH
Agar and alginate retard the reaction
(potassium sulfate).
High pH accelerate the reaction, while low pH
retard the reaction.
23. Properties
Setting time: the time required for the reaction to
be completed (final setting time).
Final setting time: when the material can be
removed from the impression without distortion.
Initial setting time: the time required to reach a
certain arbitrary stage of firmness in their setting
process.
working time.
25. Viscosity
more voids are observed in cast made of stones
with higher viscosity.
Material
Viscosity (cp)
high strength DS
A
21,000
B
29,000
C
50,000
D
54,000
E
101,000
Impression Plaster
23,000
26. Compressive
Strength
Water
Compressive strength.
Wet strength: with some or all the excess
water present in the specimen.
Dry strength: with all the excess water drive
out.
Dry C.S is almost twice the wet C.S.
8.8% excess water is in the hardened stone.
28. Surface Hardness and
Abrasion Resistance
After setting occur the C.S remain constant tell
all the excess water evaporate from the surface,
after which it increase.
Hardness increase at higher rate than C.S.
Attempts have been made to increase the
hardness of gypsum products.
Impregnating with epoxy or MMA, oils,
colloidal silica.
29. Production of Details
ADA specification requires type I & II
reproduce a groove 75 µm in width, type III, IV
& V reproduce a groove 50 µm in width.
Gypsum Vs Epoxy.
Elastomeric impressions.
Contaminations.
30. Setting Expansion
The % of setting expansion varies from one type
to another.
Plaster 0.2% to 0.3%.
Low to moderate-strength DS 0.15% to 0.25%.
High-strength DS 0.08% to 0.10%.
High-strength high expansion DS 0.10% to 0.20%.
31. almost 75% of the expansion observed during
the first 24 hrs occurs at the first hour of
setting.
Machine mixing.
W/P ratio.
chemicals.
hygroscopic expansion.
http://www.whipmix.com/img/Product_img/vacuum_mixing.jpg
32. Manipulation
The powder is added to the water and allowed
to settle for 30 sec.
Mixing can be done by hand spatulation or by
mechanical spatulation.
Pouring requires care to avoid trapping air.
Once poured it has to be allowed to set for 45
to 60 min.
33.
34. Other Die Materials
Silico Phosphate Cement: Hard but shrink on setting.
Amalgam: Amalgam reproduces fine details but has
some disadvantages:
Should be packed against rigid impression materials.
Needs a long time to reach maximum strength.
Needs a separating medium.
Has high thermal conductivity so it cools the wax
pattern rapidly, which may lead to pattern
distortion.
35. Acrylic resin and other polymeric materials:
They have high abrasion resistance and they
are harder than gypsum but their shrinkage
during polymerization leads to inaccuracy.
Epoxy die: Epoxy die is very toxic and it
shrinks during polymerization.
36. Metal sprayed die:
Bismuth tin metal sprayed
directly on impression to form metal shell then
the gypsum is directly poured in it.
Electroplated die: Silver plated die is used
with rubber impression materials but is not
used with impression compound.
Copper plated die is used with impression
compounds.