Glass ionomer cement (GIC) was developed to combine properties of silicate and polycarboxylate cements. It sets via an acid-base reaction between fluoroaluminosilicate glass powder and polyacrylic acid liquid. The setting reaction forms a matrix of hydrated calcium and aluminum polysalts surrounding unreacted glass particles. GIC has advantages like aesthetics, fluoride release, and chemical bonding to tooth structure. However, its early formulations had limitations like opacity, discoloration over time, and moisture sensitivity during setting. Modifications to GIC include resin-modified, cermet, compomer, and giomer to improve properties while maintaining benefits like fluoride release.
A number of theories have been put forward for impressions. each having its own advantage and disadvantage.
Different spacers guide and aid in in making the desired impression with adequate pressure in the desired region of the arch in maxilla and mandible. different materials are used for spacers depending on the need.
direct filling gold... material aspect, types, condensation, cavity design, modifications. detaied seminar for post gradutes.... any doubts or suggestions contact dr.mb@hotmail.com
Introduction
Classification
Composition
Properties Of GIC
Clinical Application Of GIC & GIC In Endodontics
Contraindication Of GIC
Types Of GIC
Recent Advances
Conclusion
References.
A number of theories have been put forward for impressions. each having its own advantage and disadvantage.
Different spacers guide and aid in in making the desired impression with adequate pressure in the desired region of the arch in maxilla and mandible. different materials are used for spacers depending on the need.
direct filling gold... material aspect, types, condensation, cavity design, modifications. detaied seminar for post gradutes.... any doubts or suggestions contact dr.mb@hotmail.com
Introduction
Classification
Composition
Properties Of GIC
Clinical Application Of GIC & GIC In Endodontics
Contraindication Of GIC
Types Of GIC
Recent Advances
Conclusion
References.
GIC is the Direct Aesthetic restorative material hsving a variety of Applications in Dentistry. Most important properties are F release and chemical bonding with tooth structure. In this presentation Dr Rashid covers all the aspects of GIC.
All details about the dental cements
Introduction
Definitions
Ideal properties
Classification
Based on Ingredients & Application(craig)
Based on Bonding mechanism(william O’Brien)
Based on setting reaction (Anusavice)
Silicate cement
Zinc phosphate cement
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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.
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
Rasamanikya is a excellent preparation in the field of Rasashastra, it is used in various Kushtha Roga, Shwasa, Vicharchika, Bhagandara, Vatarakta, and Phiranga Roga. In this article Preparation& Comparative analytical profile for both Formulationon i.e Rasamanikya prepared by Kushmanda swarasa & Churnodhaka Shodita Haratala. The study aims to provide insights into the comparative efficacy and analytical aspects of these formulations for enhanced therapeutic outcomes.
Basavarajeeyam is an important text for ayurvedic physician belonging to andhra pradehs. It is a popular compendium in various parts of our country as well as in andhra pradesh. The content of the text was presented in sanskrit and telugu language (Bilingual). One of the most famous book in ayurvedic pharmaceutics and therapeutics. This book contains 25 chapters called as prakaranas. Many rasaoushadis were explained, pioneer of dhatu druti, nadi pareeksha, mutra pareeksha etc. Belongs to the period of 15-16 century. New diseases like upadamsha, phiranga rogas are explained.
Here is the updated list of Top Best Ayurvedic medicine for Gas and Indigestion and those are Gas-O-Go Syp for Dyspepsia | Lavizyme Syrup for Acidity | Yumzyme Hepatoprotective Capsules etc
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2. Background
Developed in attempt to combine the favorable
properties of silicate cement and
polycarboxylate cement.
Was introduced in 1972 by Wilson and Kent.
The first introduced GIC was opaque, limited
shade selections, mixing and handling
problems and technique sensitivity.
3. Silicate Cements
It was introduced in~1870 as direct aesthetic
restoration [historical type]
Supplied form : Powder & Liquid
Composition:
Powder: Fluoro- calcium- aluminum- silicate
glass (ion leach-able glass )
Liquid: Aqueous solution of phosphoric acid
4. Setting Reaction
It is an acid base reaction
Base + Acid
Salt + Water
It is a surface reaction
cored structure
Advantages :
Aesthetic [glass content]
Anticariogenic [fluoride content]
9. Powder
Fluoro-aluminosilicate glass prepared with
fluoride fluxes.
Type II (restorative material) is generally coarser
than that of type I (Luting agent).
Glass is thermally treated to form the powder,
the quality of the setting reaction can be partially
controlled by the thermal handling.
melting temp.
more rapid setting rate
10. Liquid
The major component of the liquid is water.
35-65% aqueous solution of various polyacids.
Most common polyacids, polyacrylic acid or
copolymers of acrylic, Maleic acid or acrylic and
Itatonic acid.
Itatonic acid tends to reduce the viscosity,
Tartaric acid in small amount improves working
and setting characteristics.
11. Some manufacturers freeze or vacuum dry the
polyacids and copolymers, to incorporate them
with the cement powder rather than the liquid.
this was an attempt to ensure the accuracy of
the P/L ratio, and avoid the thickening of the
liquid with storage.
Hydrous Cement
Anhydrous Cements
Semihydrous cements
12. Setting Reaction
A typical acid base reaction
Metal + Acid = Salts (exothermic)
Powder+liquid
acid soluble glass reacts
with the polyacids releasing Al, Ca, Na, F ions.
Ca and Al polysalts are formed.
The salts Hydrate to form a gel matrix, while the
unreacted glass particles act as fillers
surrounded by the gel.
13. Set cement consist of unreacted glass
surrounded by silica gel bonded together by a
matrix of hydrated Ca and Al-polysalts.
Fluoride ions are not integral part of the
matrix formation, they are available for
clinical release without compromising the
structure of the cement.
14. Stages of Setting
Reaction
I. Decomposition: acid attack and release of metal
ions from glass.
II.Migration: ions move into the aqueous phase. at
this stage the cements has a shiny glossy
appearance.
15. III.Gelation: Ca-poly-acrylate primary
components. the cement at this stage starts to
become rigid and has an opaque
appearance(because of the large difference in
the refractive index between the glass particle &
the matrix). clinical set, polishing and finishing
postponed 24 hrs.
at this stage the cement has to be protected from
dryness and moisture.
16. IV. Post-set hardening: ions become bound to
polyacid chains, Al-polyacrylate becomes
dominant component.
V.Maturation: increase cross-linking gives greater
physical properties, the cement becomes
resistant to acid attack and desiccation. increase
translucency.
at this stage the cement can be finished &
polished.
18. Role of Water
Water plays a crucial role in the setting reaction
of glass-ionomer cement.
It act as a reaction medium.
Facilitate the formation of the hydration of the
salts and enable the cross-linking to progress
properly.
19. Amount of available water is crucial, if it varies
the results can be catastrophic:
Excess water: contamination will dilute the
metal ions in soluble form and result in
increased opacity and decreased strength and
hardness of the final cement.
Water loss during setting: desiccation of the
hydrogel disrupts the cement structure during
maturation resulting in crazing and cracking of
the final cement.
21. Manipulation:
The P/L ratio of GIC is critical.
P/L ratio is 3:1 by weight.
Must be mixed within 45 sec.
the resulting mix must have a surface gloss or
it will not adhere.
Pre-capsulated form is available.
22. Care of the liquid: In order to preserve the amount
of water inside the liquid
1)Dispense the liquid just before mixing
2)Reseal the bottle immediately
3)Discard the last third of the liquid
Use cool glass slab(not below the dew point in
order not to change the water content)
24. Mixing over large area (for heat dissipation) with
plastic spatula
Isolation of the cavity
Application of calcium hydroxide liner
Conditioning of cavity wall
Bulk insertion of the G.I.
Coating of the G.I. surface with cavity varnish
Finishing &polishing
25. Properties
Biological Properties:
G.I. is mildly irritant to the pulp due to:
Mild exothermic setting reaction
Mild acidic irritation of polycarboxylic acid
Rapid rise to neutrality within 24 hrs.
Difficult penetration of the large acid molecules
inside the dentinal tubules.
26. Anti-cariogenic property due to
Fluoride release from G.I. to tooth
Recharging ability
It is recommended in patients with high
caries index.
27. Mechanical
Properties:
Compressive strength: fairly high up to 200 MPa.
Flexural strength: fairly low 5 to 40 MPa.
Shear strength: fairly low 3 to 5 MPa.
Coefficient of thermal expansion similar to tooth
structure.
Dimensional changes: shrinks on setting, expand
with water sorption.
28. The strength and hardness are lower than those
of the silicate cements.
low toughness and less wear resistance when
compared with resin composite.
The strength of G.I. depends on:
1)Powder/Liquid
2)Protection of G.I. against dryness & moisture in
the initial set stage
29. During setting very sensitive to water but once
it sets it is characterized with a very low
solubility, the lowest of the available dental
cements.
30. Esthetic & Optical
Properties
Tooth colored restoration, acceptable esthetic
but not as good as the resin composite.
G.I. is radio-opaue by the addition of barium to
the glass powder.
31. Bonding TO Tooth
Structure
GIC share the adhesive potential of the
polycarboxylate cement.
They appear to bond primarily to the inorganic
component (Ca) of the tooth st. by initial hydrogen
bonding, forming a metal ion bridges.
Good isolation to avoid contamination and
moisture, smear layer should be removed and the
cement should be used when its in its glossy stage.
32.
33. Clinical Uses for GIC
Type I cement:
luting agent or liner
The film thickness is 20µm.
Type II cement: Class V erosion/caries
Temporary rest (caries control)
Class II, III, IV(dentin margins)
The film thickness is 45µm.
34. Type III cement: Pit & Fissure sealant.
The film thickness is25-35µm
Type IV cement: for core build up in high stress
bearing areas.
The film thickness is 45µm or more
Type V cement:
for liner & bases
35. Modifications
PURPOSE:
1 )To improve the mechanical properties
2 )To decrease the moisture sensitivity
The modification is done either to the powder or
to the liquid.
36. TYPES OF MODIFICATIONS:
1)METAL G.I. MIXTURE (MIRACLE MIX):
G.I. powder +Amalgam alloy powder
It was not successful
2) CERMET:
Precious metal e.g. silver is sintered to the G.I.
37. Cermet
Cermet can be used
as:
1)Core build up
2)Deciduous
posterior restorations
Properties of cermet :
1)Higher mechanical
properties
2)More opaque
3)Less fluoride
release
38. Resin-modified GIC
Glass ionomer cement in which the acid-base
setting reaction has been supplemented by a
polymerization reaction of added resin
components.
the following criteria must be fulfilled:
the acid base reaction must be critical to the
setting reaction.
must contain fluoroaluminosilicate glass,
polymeric carboxylic acid and water.
39. A hydrophilic monomer as HEMA is grafted to
the aqueous polycarboxylic acid copolymer
liquid
1)The monomer should be hydrophilic to
avoid separation of the resin from the liquid.
2)Initiator activator system for light & or
chemical curing of HEMA should be included.
40. Setting reaction:(supplied as powder&liquid)
1)Acid base reaction
2)Light polymerization of HEMA
3)Chemical polymerization of HEMA
Hybrid ionomer can be used as:
1)Lining under composite restorations
2)Anterior restorations Class III & V
41. Compomer
( Polyacid Modified Composite Resin):
It is a modified C.R.( C.R.+G.I.)
Composition:
1)Dimethacrylate oligomer with two carboxylic
groups.
2)Ion leachable glass filler.
3)Partially silanated to allow for bonding of filler to
matrix&leaching out of fluoride from the filler.
42. Setting reaction:( supplied as one paste)
1)Light polymerization of the oligomer(major)
2)Acid base reaction(minor;it occurs only inside the
patient`s mouth)
Properties:
1)High translucency as C.R.
2)Improved mechanical properties as C.R.
3)Chemical bonding to tooth but less than G.I.
43. GIOMER
It is again a mixture of C.R.+ G.I,but with surface
or fully pre-reacted glass ionomer.
Setting reaction:(supplied as one paste) light
polymerization of the oligomer
Properties:
Its properties are intermediate between C.R. & G.I.