An introductory and simple guide assembled by dental students and reviewed by Dr. Hasannin Al-Namel. our seminar about impression trays used in prosthodontics
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
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An introductory and simple guide assembled by dental students and reviewed by Dr. Hasannin Al-Namel. our seminar about impression trays used in prosthodontics
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
A IDEA ABOUT IMPRESSION MATERIALS OF PROSTHODONTICS. I STUDY ABOUT IMPRESSION MATERIALS & MAKE THIS PPT . I THINK IT WILL BE HELPFUL TO STUDENTS OF UNDERGRADUATE IN PRE-CLINICAL STUDY.
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A dental impression is a negative imprint of hard (teeth) and soft tissues in the mouth from which a positive reproduction (cast or model) can be formed. It is made by placing an appropriate material in a stock or custom dental impression tray which is designed to roughly fit over the dental arches. Impression material is of solid or semi-solid nature when first mixed and placed in the mouth. It then sets to become an elastic solid (usually takes a few minutes depending upon the material), leaving an imprint of person's dentition and surrounding structures of the oral cavity
Similar to Impression materials for complete denture (20)
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
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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
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
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.
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.
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.
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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
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.
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
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
Acute scrotum is a general term referring to an emergency condition affecting the contents or the wall of the scrotum.
There are a number of conditions that present acutely, predominantly with pain and/or swelling
A careful and detailed history and examination, and in some cases, investigations allow differentiation between these diagnoses. A prompt diagnosis is essential as the patient may require urgent surgical intervention
Testicular torsion refers to twisting of the spermatic cord, causing ischaemia of the testicle.
Testicular torsion results from inadequate fixation of the testis to the tunica vaginalis producing ischemia from reduced arterial inflow and venous outflow obstruction.
The prevalence of testicular torsion in adult patients hospitalized with acute scrotal pain is approximately 25 to 50 percent
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
2. DEFINITION:
A dental impression is defined as the negative record of the
tissues of the mouth . It is used to reproduce the form of the
teeth and surrounding tissues.
3. Requirements of impression material
Must be a semi-liquid material that will flow and adapt itself around the
structure of interest.
It must set and harden into a solid that is rigid enough to be removed
from the mouth without becoming deformed.
Copy details accurately
Dimensional stability after removal from the mouth
Appropriate working time (from the start of mix)
Appropriate time to harden in the mouth (setting time)
Bio-compatibility/Aesthetic, odor/taste
Chemically compatible with material used to pour cast
4. classification
There are many types of classification, the most common classification
used in complete denture construction is based on type of impression
and area of use
Primary
Impression compound
Alginate
Secondary
ZOE impression paste
Elastomers for CD
Plaster of paris
5. PRIMARY IMPRESSION
The primary impression, taken in an edentulous stock tray, is needed to
record enough detail for a special tray to be made. The primary
impression should reproduce :
1. Sulcus depth
2. Sulcus width along the entire periphery
3. Certain anatomical landmark which indicates the correct extension of the
special tray (eg maxillary tuberosity and retromolar pads.
It is usually taken in impression compound or impression plaster (not
suitable if undercuts present).
6. Final impression
Objectives
To obtain an impression from which a retentive, stable and comfortable
denture base can be constructed.
To record as accurately as possible the shape of the mucosa overlying
the alveolar ridges and hard palate together with functional depth and
width of sulci.
7. Impression compound:
Impression compound is rigid,reversible
impression material sets by physical
change.
It softens on heating and hardens on
cooling.
It have a type I, type II, type III
Supplied as sheets,sticks,cakes and cones.
8. Applications:
Making preliminary impression of edentulous mouth.
For individual tooth impression.
To make a special tray.
Border moulding.
Composition: INGREDIENTS PARTS
resin 30
Copal resin 30
Carnauba wax 10
Stearic acid 5
Talc 75
9. Properties:
Glass transitional temperature =39 degree centigrade.
Fusin temperature=43.5 degree centigrade.
They are poor conductors of heat.
Coefficient of Linear Expansion is high.
Good dimensional stability.
Low flow.
Fine reproduction of detail.
10. Advantages:
Material can be reused several times.
Inaccurate portions can be remade without having to remake the entire
impression.
Accuracy can be improved by flaming surface material.
Disadvantages:
Distortion due to poor dimensional stability.
Compress soft tissue while making impression.
Difficult to remove if there are undercuts.
Difficult to record details because of high viscosity.
11. ALGINATE
Its an irreversible elastic hydrocolloid
It is a mucous extract yielded from certain brown sea weeds
Types
type 1 – fast setting
type 2- normal setting
12. Applications
Used for impression making;
• when there are undercuts
• in mouth with excessive flow of saliva
• For impression to make study models and
working casts
• For making preliminary impression
• Managing Hyperplastic or Flabby Tissue
(Unsupported Movable Tissue)
• Management of Severely Resorbed
Mandibular Ridge
13. Applications
Primary impressions of maxillary
arch with the palatal defect and the mandibular arch recorded
using Alginate impression material
14. composition
INGREDIENTS FUNCTIONS
Sodium or pottasium alginate-
15%
React with calcium ion
Calcium sulphate(reactor) -
16%
React with potassium alginate
Zinc oxide -
4%
Acts as filler
Potasium titanium flouride -
3%
Gypsum hardener
Diatomacous earth -
60%
Acts as filler
Sodium phosphate(retarder) -
2%
React with calcium sulphate
Colouring and flavouring
agents
Wintergreen, orange etc.
15. PROPERTIES OF ALGINATE
Alginate has pleasant taste and smell
It is highly flexible
Good elasticity and elastic recovery
Fine reproduction of tissue detail
Compressive strength
– ranges from 0343-70 mpa
Tear strength- 350-700gm/cm2
Dimensionally stable
Poorly adheres to the tray
Biological properties- inhalation of
silica particles cause health hazards.
16. Properties:
Mixing time
fast setting - 45 sec
normal setting- 60sec
Working time –
fast setting – 1min
normal setting – 2 min
17. Advantages
Easy to mix and manipulate
Low cost
Comfortable to patient
Hygienic
Good surface detail even in presence of saliva
Accuracy if properly handled
Minimum requirement of equipment
Disadvantage
It cannot be corrected
Poor dimension stability
Poor tear strength
Distortion may occur if not properly handled
18. IMPRESSION PLASTER
INDICATIONS:
• Impression plaster used to record final impression for completely
edentulous arch.
PROPERTIES
higher water/powder ratio (approximately 0.60) than is normally used for
modelling plasters.
The fluid mix is required to enable fine detail to be recorded in the
impression and to give the material mucostatic properties.
Freshly mixed plaster is too fluid to be used in a stock impression tray and
is normally used in a special tray, constructed using a 1–1.5 mm spacer.
Before casting a plaster model in a plaster impression, the impression must
be coated with a separating agent (soap), otherwise separation is
impossible.
19. IMPRESSION PLASTER
CONT.
ADVANTAGES
It capable of recording soft tissues in the uncompressed state. Due to
fluidity
There is a very intimate contact between the impression material and
the tissues.
minimal dimensional change on setting,
very accurate impression which may be difficult to remove.
DISADVANTAGES
very dry sensation after having impressions recorded.
not suitable for use in any undercut situations (rigid material).
20. ZINC OXIDE EUGENOL IMPRESSION
PASTE:
Applications:
Cementing and insulating medium.
Temporary filling.
Root canal filling material.
Bite registration paste.
Impression material for
edentulous patients.
Temporary relining material
for dentures.
21. Available as:
base paste(white in colour)
Accelerator or reactor or catalyst paste(red in colour)
Composition:
Base paste Accelerator paste
Zinc oxide-87% Eugenol-12%
Fixed vegetable oil or mineral
oil-13%
Gum-50%
Filler(silica)-20%
LANOLIN-3%
Resinous balsam-10%
Accelerator solution (calcium
chloride)-5%
22. Factors controlling setting time:
Particle size of zinc oxide powder.
Longer mixing time, shortens setting time.
High atmospheric temperature and
humidity accelerate setting.
Setting can be delayed by cooling
mixing slab, spatula or adding small
amount of retarder or oils or waxes.
Properties:
Good consistency and flow.
Detail reproduction.
Rigid and having good strength.
Good dimensional stability.
23. Advantages:
It has enough working time to complete border moulding.
It can be checked in mouth repeatedly without deforming.
It registers accurate surface details.
It is dimensionally stable.
Does not require separating media since it does not stick to cast material.
Minor defects can be corrected.
Disadvantages:
Requires special tray for impression making.
Sticky in nature and adheres to tissues.
Burning sensation of eugenol causes tissue irritation.
Highly inelastic in nature.
24. NON-EUGENOL PASTES
NON-EUGENOL PASTE are developed to
overcome the burning sensation caused by
eugenol.
Bactericides and other medicaments are also
incorporated.
Used in eugenol irritant patients.
25. IMPRESSION WAXES
Impression waxes are rarely used to record complete impressions but are
normally used to correct small imperfections in other impressions,
particularly those of the zinc oxide/eugenol type.
They are thermoplastic materials which flow readily at mouth temperature
and are relatively soft even at room temperature.
They are applied with a brush in small quantities to ‘fill in’ areas of
impressions in which insufficient material has been used or in which an
‘air blow’ or crease has caused a defect.
26. ELASTOMERIC IMPRESSION MATERIAL
Classification
• A) according to chemistry
1) polysulfide
2) condensation polymerizing silicones
3) addition polymerizing silicon
4) polyether
• B) according to viscosity
1) light bodied(syringe consistency)
2) medium(regular)
3) heavy body(tray consistency)
4) very heavy(putty consistency)
27. 1.Polysulfide elastomeric impression
material
First elastomeric impression material to be introduced.
Supplied as
• Base paste (white)
• Accelerator (brown/grey)
• Available in 3 viscosities:
Light bodied, Medium bodied, Heavy bodied
28. COMPOSITION
A) Base paste
liquid polysulfide polymer – 80-85%
inert fillers - 16-18%
B) reactor paste
lead dioxide -60-68%
dibutyl phthalate -30-35%
sulphur -3%
retarders like magnesium stearate
29. Properties
Unpleasant order and colour
Material is extremely viscous and sticky and exhibits pseudoplasticity
Long setting time of 12.5min
High tear strength
Good flexibility
Excellent reproduction of surface detail
Hydrophobic- tissue should be thoroughly dried before making the
impression.
30. Clinical considerations when used
Used with custom trays
Allow 2mm thickness
Use tray adhesive
Setting time 10 min.
Have very good tear resistance.
31. advantages
1. Long working time.
2. Proven accuracy
3. High tear resistance.
4. Inexpensive to use
5. Less hydrophobic
6. Longer shelf life.
Disadvantages:
1. Must be poured with dental stone immediately.
2. Potential for significant distortion.
3. Odor is offensive.
4. Messy & stains clothes.
5. Second pour is less accurate.
32. SILICON RUBBER IMPRESSION
MATERIAL
Types
1-condensation silicones
2-addition silicones
Condensation silicones;
Also known as conventional
silicones.
Available in three viscosities
namely light,
medium bodied and heavy.
33. 1.CONDENSATION SILICONES
It was the first type of silicone impression material.
Also known as conventional silicones.
Composition;
Base paste
1-polydimethyl siloxane.
2-colloidal silica
Color pigments.
Accelerator
Stannous octoate
34. Properties:
1. Setting time – 8-9 min. Mixing time – 45 sec.
2. Excellent detail reproduction
3. Dimensional stability – high curing shrinkage.
4. Permanent deformation – 1-3 %
5. Tear strength – 3000gm/cm
6. Staffer & harder than polysulfide material.
7. Hydrophobic
8. Can be electroplated with silver & copper.
9. Shelf life - 2 yrs.
35. Advantages:
1. Adequate working & setting timer.
2. Pleasant odor & no staining.
3. Adequate tear strength
4. Hetter elastic properties on removal.
5. Less distortion on removal.
Disadvantages:
1. Adequate accuracy if poured immediately.
2. Poor dimensional stability.
3. Potential for significant distortion.
4. Putty-wash method is technique sensitive.
5. Slightly more expensive.
36. 2.ADITION SILICONES
Introduced after condensation silicones
Have better properties than condensation silicones.
Also known as poly vinyl siloxane.
38. Advantages:
1. Short setting time
2. Adequate tear strength
3. Extremely high accuracy
4. Minimal distortion on removal
5. Dimensionally stable even after 1 week
6. If hydrophilic, good compatibility with gypsum
Disadvantages:
1. Hydrogen gas may cause dimensional change.
2. Hydrophobic & hence requires a very dry field.
3. Expensive.
39. Polyether impression materials;
Good mechanical and compressive strength
comparing other elastomers.
Available in three viscosities.
Consist of base paste and catalyst.
Base Paste:
1. Imine terminated polymer(polyether)
2. Colloidal silica
3. Glycol ether or phthalate
Accelerator Paste:
1. Alkyl aromatic sulfonate
2. Colloidal silica
3. Plasticizers ( glycoether )
40. Properties:
1. Setting time: 8.3 min. Mixing time – 30 sec.
2. Dimensional stability is good.
3. Decreased flexibility – 3%
4. Hydrophilic
5. Activator paste can produce allergy if handled frequently.
6. Tear strength – 3000gm/cm
7. Shelf life > 2 yrs.
41. Advantages
1. Short working & setting time
2. Proven accuracy
3. Adequate tear strength
4. Hydrophilic
5. Long shelf life
6. Less distortion on removal
7. Good dimensional stability.
Disadvantages
1.Stiffness requires blocking of undercuts
2. Slightly more expensive
3. Multiple casts can’t be poured due to stiffness of the material.
42. Manipulation of Elastomers:
Manipulation of two paste systems
equal length of base & activator paste are taken.
Paper pad with graduations is provided by manufacturer.
Pastes are mixed till no streaks are present.
Tray coated with tray adhesive. Uniform two-layer coat is applied & allowed to dry.
The mixed material can either be taken in a syringe or loaded directly in the tray.
Manipulation of Putty Material:
Putty dispenser is supplied with scoops for dispensing.
Activator may be a liquid or paste.
Putty material is taken in a scoop & the activator is added. Usually the activator is of
different color
It is kneaded till no streaks are present.
Putty material is used with stock trays.