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CONTENTS
 Hydrocolloids.
 Sol-Gel Transformation.
 Agar Agar
Introduction
Uses
Composition
Preparation
Types
Mani...
HYDROCOLLOIDS
HYDROCOLLOID are lyosol basically
consists of gelatin particles
suspended in water and water is the
dispers...
Solvent and Solute
Solution
single phase, which
means a homogenous
mixture, where the solute
exists as small molecules
or ...
SOL-GEL TRANSFORMATION
 Hydrocolloids can exist in 2 different forms – SOL
and GEL.
 Sol – has the appearance & characte...
6
BRUSH HEAP
STRUCTURE
It occurs in two ways.
1. By temperature changes:
 Gelation is brought about by a reversible process. E.g.
Agar. The fibr...
2. By chemical change
 Conversion of sol to gel is brought about by chemical
reaction, the fibrils thus formed are held t...
AGAR - AGAR
9
 1925 – Alphous Poller – Negacol.
 Modified & introduced in dental
profession as Dentacol in 1928.
 Agar is an organic ...
USES OF AGAR:
1. Widely used at present for cast
duplication .
2. For full mouth impression without deep
undercuts .
3. As...
COMPOSITION
 Water - 84 % - dispersion medium
 Agar - 13 - 17 % - gelling agent, dispersed
phase
 Borates - 0.2 - 0.5% ...
COMMERCIAL BRANDS
 Acculoid / Cartrilloid (Van R)
 Sugident (Lactona)
 Cohere / SuperBody / SuperSyringe (Ghingi-pak)
...
PREPARATION OF AGAR
 Cleanliness, maintenance, and care of the conditioner
and strict adherence to time and temperature a...
 The conditioner is turned on.
 Thirty minutes should be allowed for the water to reach
the desired temperatures before ...
TYPES OF AGAR
1. Heavy bodied – in poly tubes or flex
skins
2. Medium bodied
3. Regular bodied
4. Light bodied – in syring...
MANIPULATION
The following steps are recommended
 Heat in water at 100° C (212° F) for 8 - 10 minutes.
 Store in water a...
 In the meantime, tray material is tempered,
water soaked outer layer is soaked with a dry
guaze before placing to ensure...
 Excess is trimmed and impression is stored in 2 %
potassium sulfate, controls water volume and has better
surface integr...
20
BOILING /
LIQUIFACTION
SECTION
• 1 0 mins in boiling water (1 0 0 c)
• Every time material is reliquified, 3
mins should b...
PROPERTIES
1. Gelation Temperature - after boiling for 8
minutes, the material should be fluid enough to
be extruded from ...
3. Flexibility - 4% to 15%. Materials with low flexibility
can be accommodated in areas of undercuts by
providing somewhat...
6. Distortion during gelation
 Contraction occurs during physical change from
sol to gel.
 If the material is held rigid...
IMPRESSION TECHNIQUES
 Full arch impression
 Sectional arch impression
Sectional arch impression techniques follows
same...
LAMINATE TECHNIQUE: - [Schwartz (1951)]
 It is a modified procedure using both reversible and
irreversible hydrocolloid. ...
 The agar is injected around the preparation and the mixed
alginate is promptly seated on top of the agar. The alginate
s...
ADVANTAGES
 Agar provides tissues details and solidifies
when it comes in contact with alginate
prepared in water at 70°F...
WET FIELD TECHNIQUE
 In this, tooth surfaces are purposely left wet and
areas are actually flooded with warm water.
 The...
ADVANTAGES OF AGAR
1. Helps in preparing dies accurately.
2. Good elastic property and reproduces
most undercut areas.
3. ...
DISADVANTAGES
Does not flow properly.
Cannot be electroplated.
Due to heat , it may be painful.
Tears relatively easil...
Alginate
32
 The word Alginate comes from ‘Algin’ which is a
peculiar mucous extract yielded by certain brown
seaweed.
 Alginates ar...
COMPOSITION
1. Ester salt of alginic acid (sodium or potassium
or triethanolamine alginate) – 15 % - dissolves
in water an...
6. phosphate – 2 % - retarder and Delays gelation by
reacting with calcium sulphate in preference to
soluble alginate to f...
USES
1. Complete denture prosthesis & orthodontics
2. Mouth protectors
3. Study models and working casts
4. Duplicating mo...
COMMERCIAL BRANDS
 Coe Alginate (GC America)
 Integra (Kerr)
 Jeltrate (Dentsply Caulk)
 Zelgan (DPI)
 Kalginate, Sup...
CHEMISTRY The alginate when mixed with water becomes a
sol. Gelation occurs by a chemical reaction .
 The simplest and t...
 Production of Calcium alginate is delayed by the
addition of soluble salts acting as retarder like
sodium or potassium p...
MANIPULATION
 Fluff or aerate the powder by inverting the
container with the lead on several times –
ensures uniform dist...
41
42
•Powder is added to liquid to wet the powder
with water and to reduce entrapment of air.
•One scoop of pre-dispensed po...
 Mix by hand spatulation / mechanical
spatulation with or without vacuum vigorously
for smooth creamy mix with minimum vo...
 Filled tray is held passively and motionlessly and
material is left for 2 -3 minutes, till it becomes firm
because of ad...
 Tray should separated immediately suddenly with a jerk -
to avoid rocking and possible deformation of impression.
 Exce...
46
47
 If allowed to remain for longer time, alginate
dehydrates and damaging changes take place in the
surface of stone.
 The...
 Manual Technique
A mixing time of 45 seconds to 1 minute is
sufficient .Mixing should result in a smooth creamy
mix that...
 Automated Technique
A variety of mechanical devices are available for
spatulating the alginate impression material. The
...
PACKAGING
 Alginate is supplied as a powder i.e. packaged in bulk
in a sealed screw top plastic container or hermetically...
SHELF LIFE
 Alginate impression material deteriorates rapidly at
elevated temperatures by depolymerisation of the
alginat...
POURING THE CAST
 The pouring of the cast should start from one end of
arch. Afterwards it is placed in a humidator while...
ADVANTAGES
 Easy to manipulate
 Comfortable for patient
 Economical
 Viscosity and setting time can be altered.
 Hydr...
PROPERTIES1. Taste & odor: variety of colors and flavors.
2. Flexibility : 14% at a stress of 1000 gm/cm2.
3. Elastic reco...
4. Reproduction of tissue details : lower than agar.
ADA Sp. Requires material to reproduce a line that
is 0.075 mm width....
MIXING
TIME
WORKING
TIME
SETTING
TIME
TYPE 1
(fast set)
45 sec 75 sec 1-2.0
mins
TYPE 2
(normal
set)
60 sec 120 sec 2-4.5
...
CONTROL OF SETTING TIME
 Lengthening the setting time is better accomplished by reducing
the temperature of the water use...
CONTROL OF GELATION TIME
 The gelation time is measured from the beginning of
the mixing until gelation occurs. It must a...
 Gelation time is best regulated by the amount
of retarder added during manufacturing.In
another way the clinician can sa...
COMPATIBILITY WITH
GYPSUM
 Gypsum casts is not compatible with both type of
hydrocolloid impression. To ensure maximum su...
2. Incorporating a plastic hardener or accelerator in
the material by the manufacturer. Potassium
titanium fluoride is mos...
LATEST ADVANCES
 MODIFIED ALGINATES:
1. In the form of a sol, containing the water. A reactor of
plaster of Paris is supp...
3. ALGINOT
 it is an extremely cost-effective, reliable
alternative.
 High quality material that delivers accuracy and
p...
4. SILGINAT(Kettenbach LP)
 It is a medium viscosity addition-curing elastomeric
polyvinyl silioxane impression material ...
5. SILGINAT FOIL BAG ALGINATE
SUBSTITUTE MATERIAL
 Quantity Foil Bag - (362 mL)
 Working Time - 90 seconds
 Dispensing ...
6. STATUSBLUE(dmg america)
 StatusBlue is an efficient, clean and stable alginate alternative.
 A-silicone formula makes...
7. FREEALGIN MAXI
( Zhermack , inc)
 A-silicone, alginate alternative, fast setting, medium
viscosity for all alginate in...
8.POSITION™ PENTA™ QUICK VPS
ALGINATE REPLACEMENT
 Accurate, dimensionally stable preliminary
impressions that take less ...
 Quantity - Kit includes: 1 base paste – 300ml; 1 catalyst
– 60ml; 1 Penta™ cartridge, lavender; 6 Directed Flow
Impressi...
9.ANTISEPTIC ALGINATE
IMPRESSION MATERIAL
 Introduced by Tameyuki Yamamoto,
patented in 1990.
 An antiseptic containing ...
10. CAVEX COLOR CHANGE
 Material with color indications
avoiding confusion about setting time.
 Color changes visualizes...
11.LOW DUST ALGINATE
IMPRESSION MATERIAL Introduced by Schunichi in 1997.
 This composition comprises an alginate a gela...
 ADVANTAGES
Easy mixing
Excellent stone surface
Unsurpassed smoothness
Fine detail
 Packed in 1 lb poly- aluminium pouch...
ALGINATE
 Material changes colour signaling
when to carry out each stage of the
procedure
Purple – spatulate
Pink – load ...
13. ALGINMAX (FUNG INT.)
 High precision chromatic dental alginate.
 Excellent dimensional stability allows casting of
t...
77
 Specifically designed for use with
any automatic delivery and mixing
system, Kettosil incorporates all of
the advanta...
 Kettosil impressions can be poured 30 minutes
after removal from the mouth and up to 21 days
after impression taking.
 ...
 High Recovery From Deformation of 99.2% .
 No Wasted Material
Activated cartridges of Kettosil can be sealed by
leaving...
Agar Alginate
3)
Dimensional
accuracy
PROPERTIES
1) Flow
2) Elasticity
4)
Dimensional
stability
Excellent
Elastic
98.8%
Im...
5) Adhesion
With the tray
6) Compatibility
with Cast
Manipulation Special equipments No Special
equipments
Addition accept...
TYPES OF FAILURES
DISTORTION -Delayed pouring of impression.
-Movement of the tray during
seating.
- Early removal from mo...
BUBBLES - Early gelation
- Air incorporation
VOIDS - Excess moisture or
debris on tissues
ROUGH OR
CHALKY
STONE CAST
- Imp...
Alginate (Irreversible hydrocolloid):
 All the instrument i.e. rubber bowl, spatula are
sterilized or disinfected by spra...
 When it reached the lab, it is again cleaned with
water and stone cast is poured.
 For immersion technique, disinfectan...
CONCLUSION
 Success of alginate hydrocolloid impression
material since its emergence as an alternative to
reversible hydr...
REFERENCES Philip’s science of dental materials (11thEdition)-
Anusavice KJ
 Restorative Dental Materials (11thEdition)-...
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Agar alginate

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Agar agar & Alginate Impression Material

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  • Interesting post ! Coincidentally , if your company is wanting a ATF 4 (5320.4) , my assistant encountered a sample document here http://pdf.ac/1k3hn2
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Agar alginate

  1. 1. 1
  2. 2. CONTENTS  Hydrocolloids.  Sol-Gel Transformation.  Agar Agar Introduction Uses Composition Preparation Types Manipulation Properties Impression techniques.  Alginate Introduction Composition Uses Types Chemistry Manipulation Packaging Shelf Life Properties Latest advances  Types of Failure  Disinfection of impression material  Conclusion  Refrences 2
  3. 3. HYDROCOLLOIDS HYDROCOLLOID are lyosol basically consists of gelatin particles suspended in water and water is the dispersion medium .  Solution – uniformly dispersed solute and solvent e.g. salt in water – exist as a single phase Suspension – visible insoluble particles in solute e.g. dust in water Emulsion – visible insoluble liquid in liquid e.g. oil in water 3
  4. 4. Solvent and Solute Solution single phase, which means a homogenous mixture, where the solute exists as small molecules or ions in the solvent. Colloids Emulsion heterogeneous two-phase system, a dispersed phase of particles of at least sufficient size to be seen microscopically, dispersed in a medium. Hydrocolloids 4
  5. 5. SOL-GEL TRANSFORMATION  Hydrocolloids can exist in 2 different forms – SOL and GEL.  Sol – has the appearance & characteristics of a viscous liquid.  Gel – a jelly like elastic semi-solid – produced from sol by a process called GELATION – by formation of fibrils or chains or micelles of the dispersed phase which become interlocked – brush heap structure  GELATION – thus, the conversion of sol to gel . 5
  6. 6. 6 BRUSH HEAP STRUCTURE
  7. 7. It occurs in two ways. 1. By temperature changes:  Gelation is brought about by a reversible process. E.g. Agar. The fibrils are held together by secondary molecular forces. So that they break at slightly elevated temperature and become reestablished as the hydrocolloid cools to room temperature.  The temperature at which these changes occurs is the Gelation temperature.  The Gel is converted to sol when it is heated to a higher temperature which is known as Liquification temperature.  The temperature lag is known as hysterisis. 7
  8. 8. 2. By chemical change  Conversion of sol to gel is brought about by chemical reaction, the fibrils thus formed are held together by primary bonds and are unaffected by temperature. Hence they are called irreversible hydrocolloid e.g. Alginate.  Gel can be converted to sol (liquid) by heating, cooling a sol causes it to become a gel. Agar (hot) cool to 43 C Agar (cold) (Sol) heat to 100 c (gel) 8
  9. 9. AGAR - AGAR 9
  10. 10.  1925 – Alphous Poller – Negacol.  Modified & introduced in dental profession as Dentacol in 1928.  Agar is an organic hydrophilic colloid (polysaccharide) extracted from certain types of seaweed( kelp plant).  It is a sulphuric ester of a linear polymer of galactose. 10 INTRODUCTION
  11. 11. USES OF AGAR: 1. Widely used at present for cast duplication . 2. For full mouth impression without deep undercuts . 3. As tissue conditioner. 4. Was used for crown & bridge before the 11
  12. 12. COMPOSITION  Water - 84 % - dispersion medium  Agar - 13 - 17 % - gelling agent, dispersed phase  Borates - 0.2 - 0.5% - improves strength and retards setting of plaster or stones  K sulphate - 1 - 2% - it counters the retarding effect of borates and provide good surfaces on gypsum models/dies  Alkyl benzoates - 0.1 % - preservatives  Fillers like diatomaceous earth, clay, silica, wax, rubber, and inert powders for control of strength, viscosity and rigidity. 12
  13. 13. COMMERCIAL BRANDS  Acculoid / Cartrilloid (Van R)  Sugident (Lactona)  Cohere / SuperBody / SuperSyringe (Ghingi-pak)  Indentic (Cadco) SUPPLIED AS  solid gel in collapsible tubes (for impressions)  No. of cylinders in a glass jar (syringe material)  In bulk containers (for duplication) 13
  14. 14. PREPARATION OF AGAR  Cleanliness, maintenance, and care of the conditioner and strict adherence to time and temperature are mandatory.  The water pots should be clean and free of any foreign material, eg, wax, calcium deposits, and "scum" from the boiling water.  Conditioners stay clean.  Failure to keep the pots clean will result in temperature variations. 14
  15. 15.  The conditioner is turned on.  Thirty minutes should be allowed for the water to reach the desired temperatures before proceeding.  The boiling pot temperature should be maintained.  The water is brought to a boil, and boiling is continued for 10 minutes.  Tooth preparation – should be caries free , without undercuts( if present – should be filled with cements resins or composites)  The cervical margins should be distinct. 15
  16. 16. TYPES OF AGAR 1. Heavy bodied – in poly tubes or flex skins 2. Medium bodied 3. Regular bodied 4. Light bodied – in syringes 16 •Trays should be selected and tried in the patient's mouth before the impression material is placed in them. •There should be 3 mm of impression material around the teeth occlusally and laterally.
  17. 17. MANIPULATION The following steps are recommended  Heat in water at 100° C (212° F) for 8 - 10 minutes.  Store in water at 65° C (149° F) for 8-10 hours  Place in a tray at 65° C (149° F)  Temper in 46° C (115° F) water for 2 minute before taking the impression to increase the viscosity and pressure applied to the syringe material, also making comfortable for the patient.  The solution is taken directly from the storage compartment, is first ejected at the base of the preparation and then the remainder of the prepared tooth is covered. 17
  18. 18.  In the meantime, tray material is tempered, water soaked outer layer is soaked with a dry guaze before placing to ensure good union between tray and syringe material. The tray material is positioned with passive pressure.  ADA specifications no.11 specifies that gelation temperature must not be less than 37°C (98.6°F) or more than 45°C (113°F).  Gelation is accomplished by circulating cool water with a time not less than 5 minutes.  After gelation, impression is withdrawn in one piece, parallel to line of withdrawal of prepared tooth. 18
  19. 19.  Excess is trimmed and impression is stored in 2 % potassium sulfate, controls water volume and has better surface integrity in stone for 5 to 20 mins.  The potassium sulfate solution gives a harder surface to the stone die material.  The potassium sulfate should not be washed out of the impressions before the dies are poured.  The impression must be blown carefully; the impression should not be dehydrated, but an excessive amount of water or moisture should not be left in the impression.  Impression must be poured immediately after retrieval, and disinfected with iodophor, bleach or glutaraldehyde.  The cast should be kept in contact with impression for at least 30minutes, or preferably 60 minutes. 19
  20. 20. 20
  21. 21. BOILING / LIQUIFACTION SECTION • 1 0 mins in boiling water (1 0 0 c) • Every time material is reliquified, 3 mins should be added. this is because it is more difficult to break down the agar brush heap structure after a previous use. STORAGE SECTION • 65 – 68ºC Temp. is ideal. It can be Stored in the sol condition till needed. TEMPERING SECTION 46ºC for 2-10 mins with material loaded in the tray. CONDITIONING UNIT 21
  22. 22. PROPERTIES 1. Gelation Temperature - after boiling for 8 minutes, the material should be fluid enough to be extruded from the container. After tempering, the sol should be homogeneous and should set to a gel between 37" and 45" C when cooled. 2. Permanent deformation - The ANSI/ADA Specification requires that the recovery from deformation be greater than 96.5% (permanent deformation be less than 3.5%) after the material is compressed 20% for 1 second. 22
  23. 23. 3. Flexibility - 4% to 15%. Materials with low flexibility can be accommodated in areas of undercuts by providing somewhat more space for the impression material so it is subjected to a lower percentage of compression during removal. 4. Strength – compressive strength - 8000 g/cm2. tear strength - 800 to 900 g/ cm. Because agar hydrocolloid impressions are viscoelastic, the strength properties are time dependent, and higher compressive and tear strengths occur at higher rates of loading. 5. Compatibilty with gypsum - Agar is more compatible with gypsum model materials than alginates 23
  24. 24. 6. Distortion during gelation  Contraction occurs during physical change from sol to gel.  If the material is held rigidly in the tray , material will shrink towards the centre of its mass , thereby creating larger dies.  Since sol is the poor thermal conductor , rapid cooling may cause conc. Of stress near the tray where gelation first takes place.  Therefore water at 20 degree celcius is suitable for cooling. 24
  25. 25. IMPRESSION TECHNIQUES  Full arch impression  Sectional arch impression Sectional arch impression techniques follows same procedure as for full arch. Selected tray should cover the tooth and its adjacent two or more teeth.  Indication: 1. Working model for inlay preparation. 2. Single or more teeth preparation. 25
  26. 26. LAMINATE TECHNIQUE: - [Schwartz (1951)]  It is a modified procedure using both reversible and irreversible hydrocolloid. Tray hydrocolloid is replaced with a mix of chilled alginate that bonds syringe agar. Alginate sets by chemical reaction whereas agar by temperature change.  The equipment needed for taking an agar impression can be minimized by use of an agar-alginate, syringe- tray combination impression.  In this procedure a syringe type of agar in a cartridge is heated in boiling water for 6 minutes and stored in a 65'c water bath 10 minutes before use.  The tray alginate of the regular set type is mixed with 10% more water than normally recommended and it is placed in a tray. 26
  27. 27.  The agar is injected around the preparation and the mixed alginate is promptly seated on top of the agar. The alginate sets in about 3 mins, and the agar gels within this time as a result of being cooled by the alginate.  During the setting of the alginate and gelling of the agar a bond forms between them. The impression may be removed in about 4 minutes.  Since the hydrocolloid, not the alginate, is in contact with the prepared teeth, maximum detail will be reproduced.  bond together better than others, with tensile bond strengths ranging from 600 to 1100gm/cm2.  Values at the high end of the range resulted in cohesive failure of the agar, where as those at the low end produced adhesive failure between the agar and the alginate. It is therefore advisable to follow the manufacturer's suggestions for appropriate combinations. 27
  28. 28. ADVANTAGES  Agar provides tissues details and solidifies when it comes in contact with alginate prepared in water at 70°F, Preventing rapid gelation.  the elimination of water-cooled impression trays.  agar is more compatible with gypsum model materials than alginates.  the accuracy is acceptable.  Economical and simple.  Liquification and storage of agar not required  Decreased setting time (3minute). 28
  29. 29. WET FIELD TECHNIQUE  In this, tooth surfaces are purposely left wet and areas are actually flooded with warm water.  The syringe material is introduced quickly, liberally and in bulk to cover occlusal / incisal areas only.  While the syringe material is still liquid, tray material is seated, the hydraulic pressure of the viscous tray material forces the syringe material into areas to be restored.  This motion displaces the syringe material, blood and debris throughout the sulcus. 29
  30. 30. ADVANTAGES OF AGAR 1. Helps in preparing dies accurately. 2. Good elastic property and reproduces most undercut areas. 3. Good recovery from distortion. 4. Non hydrophobic. 5. Palatable and well tolerated. 6. Cheap. 7. Can be reused. 30
  31. 31. DISADVANTAGES Does not flow properly. Cannot be electroplated. Due to heat , it may be painful. Tears relatively easily. 31
  32. 32. Alginate 32
  33. 33.  The word Alginate comes from ‘Algin’ which is a peculiar mucous extract yielded by certain brown seaweed.  Alginates are based on anhydro-ß-d mannuronic acid or anhydro-P-D-guluronic acid.  S. Willium Wilding 1940s introduced.  Alginate was used as a substitute for agar when it became scarce during World War II (Japan was a prime source of agar)  Current status – alginate more popular than agar . 33
  34. 34. COMPOSITION 1. Ester salt of alginic acid (sodium or potassium or triethanolamine alginate) – 15 % - dissolves in water and reacts with calcium ions to form gel. 2. Calcium sulphate – 16 % - reacts with potassium alginate & forms insoluble calcium alginate 3. Zinc oxide – 4 % - filler and influences physical properties and setting time of the gel. 4. Potassium titanium fluoride/silicate or k sulphate – 3 % - gypsum hardener 34
  35. 35. 6. phosphate – 2 % - retarder and Delays gelation by reacting with calcium sulphate in preference to soluble alginate to form insoluble gel. 7. Glycol - small amount - To make powder dustless 8. Chemical indicators - small amount pH changes from alkaline to neutral to indicate different stages in manipulation Violet – during spatulation Pink - ready to load White - ready for insertion into mouth 9. Wintergreen/peppermint - trace amount 10. Disinfectants ( ammonia salts and CHX) - small amount 35
  36. 36. USES 1. Complete denture prosthesis & orthodontics 2. Mouth protectors 3. Study models and working casts 4. Duplicating models TYPES: Type I – Fast setting. Type II – Normal setting. 36
  37. 37. COMMERCIAL BRANDS  Coe Alginate (GC America)  Integra (Kerr)  Jeltrate (Dentsply Caulk)  Zelgan (DPI)  Kalginate, Supergel, Surgident, UnigelII, Vemog SUPPLIED AS: - Bulk containers - Pre-weighed packets for single impression - paste / paste system 37
  38. 38. CHEMISTRY The alginate when mixed with water becomes a sol. Gelation occurs by a chemical reaction .  The simplest and the popular method is reacting the soluble alginate with calcium sulphate to produce insoluble calcium alginate gel.  Chief ingredient is one of the soluble alginates which is a linear polymer of the sodium salt of anhydro-beta-d-mannuronic acid.  Calcium sulfate (Reactor) reacts with potassium or sodium alginate in an aqueous solution. 38
  39. 39.  Production of Calcium alginate is delayed by the addition of soluble salts acting as retarder like sodium or potassium phosphate, oxalate or carbonate. 2Na3PO4 + 3CaS04 Ca3(PO4) + 3Na2SO4  When supply of sodium phosphate is exhausted, calcium ions begin to react with potassium alginate to produce calcium alginate. K2Alg + CaSO4 + H2O K2SO4 + Ca Alginate.  ADA no 18 describes two types of alginates  Type I (fast setting) - 1 to 2 min  Type II (normal setting) - 2 to 4.5 minutes 39
  40. 40. MANIPULATION  Fluff or aerate the powder by inverting the container with the lead on several times – ensures uniform distribution.  A clean flexible plastic bowl, a clean wide bladed stiff metal / plastic spatula.  Tray selection : perforated metal rim lock tray or plastic tray with retentive holes.  An excess of saliva around the teeth should be removed -may cause bubbles in the interproximal areas and on the occlusal surfaces of the teeth. 40
  41. 41. 41
  42. 42. 42 •Powder is added to liquid to wet the powder with water and to reduce entrapment of air. •One scoop of pre-dispensed powder products is used with the amount of water specified by manufacturer (16g of powder to 38 ml of water) •Once the powder is moistened, rapid spatulation by swiping, or stropping against the side of the bowl. •A vigorous figure of 8 motion can also be used.
  43. 43.  Mix by hand spatulation / mechanical spatulation with or without vacuum vigorously for smooth creamy mix with minimum voids (mixing time 45sec- 1 min) .  Air bubbles can be minimized by careful application of the impression material to tooth and into vestibular area with finger pressure before placement of filled tray. 43
  44. 44.  Filled tray is held passively and motionlessly and material is left for 2 -3 minutes, till it becomes firm because of adequate maturation of chemical set.  The thickness of the gel between tray and the tissues should be 3 mm .  Working time 1 – 2 min 44
  45. 45.  Tray should separated immediately suddenly with a jerk - to avoid rocking and possible deformation of impression.  Excess material is trimmed .  The impression is washed in cold water to remove saliva stored in an environment of 100% humidity or covered with a damp napkin to prevent drying.  Impression should be poured within 10 mins for accuracy.  Cast should be separated from alginate impression as soon as the stone has reached the optimal stage of rigidity i.e. after 45 - 60 minute. 45
  46. 46. 46
  47. 47. 47
  48. 48.  If allowed to remain for longer time, alginate dehydrates and damaging changes take place in the surface of stone.  The mixing time also affects strength of the gel structure. The strength of gel can be reduced as much as 50% if mix is not complete.  Under mixing can lead to grainy mix which leads to reduced tissue detail reproduction.  Prolonged mixing results in weakened gel structure as fibrils once formed will be broken up. This will also lead to reduced working time 48
  49. 49.  Manual Technique A mixing time of 45 seconds to 1 minute is sufficient .Mixing should result in a smooth creamy mix that does not drip off the spatula, when it’s raised from the bowl. 49
  50. 50.  Automated Technique A variety of mechanical devices are available for spatulating the alginate impression material. The required quantity of powder and water are dispensed in a bowl. Spatulation is carried out until a smooth creamy mix of alginate is obtained. This results in a superior mix than obtained manually. 50
  51. 51. PACKAGING  Alginate is supplied as a powder i.e. packaged in bulk in a sealed screw top plastic container or hermetically sealed metal can. A plastic scoop and cylinder is provided .  Preweighed packets constructed of plastic or metal foil. it increase storage life and decrease moisture contamination.  Automatic mixing systems have been developed for paste/paste alginates. These systems consist of a mixing unit that mixes - an aqueous base paste – sodium alginate polyacrylic acid - an organic initiator paste - calcium sulphate- hemihydrate and sodium phosphate. 51
  52. 52. SHELF LIFE  Alginate impression material deteriorates rapidly at elevated temperatures by depolymerisation of the alginate constituent. Materials stored for one month at 65 degree Celsius are unstable for use as they do not set at all or set too rapidly for any practical use. Even at 54 degree Celsius there’s evidence of deterioration.  The ADA specification number 18 for alginate impressions specify that storage within original container for 1 week at 60 degree Celsius in a relative humidity of 100% the compressive strength of the gel should not be less than 0.255Mpa. 52
  53. 53. POURING THE CAST  The pouring of the cast should start from one end of arch. Afterwards it is placed in a humidator while stone hardens. Stone cast or die should be kept in contact with the impression preferably for 60 minutes or for a minimum of 30 minutes.  NEW METHOD A proper dental stone mixed with an accelerator is painted over the entire anatomic surface of the impression. A base is added only after the first application of stone sets. This method protects against volume change of the irreversible hydrocolloid impression material and distortion of the unsupported portions of the impression. 53
  54. 54. ADVANTAGES  Easy to manipulate  Comfortable for patient  Economical  Viscosity and setting time can be altered.  Hydrophilic nature allows small presence of water on the tissues without causing major inaccuracies in the impression. DISADVANTAGES  Distortion begins immediately after removal from the mouth .  Surface details and accuracies are poor.  Retention of alginate to non-perforated trays is inadequate. 54
  55. 55. PROPERTIES1. Taste & odor: variety of colors and flavors. 2. Flexibility : 14% at a stress of 1000 gm/cm2. 3. Elastic recovery : 97.3%  Permanent deformation is less if set impression is removed from mouth quickly.  The ANSI/ADA Specification requires that the recovery from deformation be more than 95% (or a permanent deformation of less than 5%) when the material is compressed 20% for 5 seconds at the time it would normally be removed from the mouth. 55
  56. 56. 4. Reproduction of tissue details : lower than agar. ADA Sp. Requires material to reproduce a line that is 0.075 mm width. 5. Strength : Compressive strengths – 5000-8000 gm/cm2 Tear strength - 350-700 gm/cm2 6. Dimensional stability: poor 7. Storage : cool, dry, tightly closed lid. 56
  57. 57. MIXING TIME WORKING TIME SETTING TIME TYPE 1 (fast set) 45 sec 75 sec 1-2.0 mins TYPE 2 (normal set) 60 sec 120 sec 2-4.5 mins 57
  58. 58. CONTROL OF SETTING TIME  Lengthening the setting time is better accomplished by reducing the temperature of the water used with the mix than by reducing the proportion of powder.  Reducing the ratio of powder to water reduces the strength and accuracy of the alginate.  The setting reaction is a typical chemical reaction, and the rate can be approximately doubled by a temperature increase of 10" C.  using water cooler than 18" C or warmer than 24" C is not advisable.  The clinical setting time is detected by a loss of surface tackiness. 58
  59. 59. CONTROL OF GELATION TIME  The gelation time is measured from the beginning of the mixing until gelation occurs. It must allow sufficient time for the dentist to mix the material, load the tray and place it in the patient’s mouth.  Once gelation starts the impression must not be disturbed because growing fibres will be fractured and impression would be sufficiently weakened.  Optimal gelation time - 3 – 4 mins at temperature of 200C.  ADA specification no:18 for alginate have described two types of alginate based on gelation time.  Type I (fast setting) : 1 – 2 minutes  Type II (normal setting) : gelation time 2.5 - 4 mins 59
  60. 60.  Gelation time is best regulated by the amount of retarder added during manufacturing.In another way the clinician can safely influence gelation time by altering the temperature of water used to mix the impression material.  Increase in temperature leads to a decrease in gelation time and vice versa. However using water cooler than 180C and warmer than 54 c is not recommended. 60
  61. 61. COMPATIBILITY WITH GYPSUM  Gypsum casts is not compatible with both type of hydrocolloid impression. To ensure maximum surface hardness, methods employed are : 1. Immersing the impression in a solution containing an accelerator for setting of gypsum products before pouring impression with gypsum. This acts by two ways (a) accelerates setting of gypsum. (b) Reacts with gel to produce a surface layer that reduces or prevents syneresis and eliminates the retarding action of the gel.  Potassium sulphate, Zinc sulphate, manganese sulphate, potash alum etc are chemicals usually used in hardening solutions. Most effective is 2% K2SO4 solution. 61
  62. 62. 2. Incorporating a plastic hardener or accelerator in the material by the manufacturer. Potassium titanium fluoride is most commonly used hardening agent. In general a hardening solution is not required unless specified by the manufacturer as most of the commercially available alginates contain a hardener in them. 62
  63. 63. LATEST ADVANCES  MODIFIED ALGINATES: 1. In the form of a sol, containing the water. A reactor of plaster of Paris is supplied separately. 2. Paste system, one containing the alginate sol, the second the calcium reactor. These materials are said to contain silicone and have superior tear resistance. 63
  64. 64. 3. ALGINOT  it is an extremely cost-effective, reliable alternative.  High quality material that delivers accuracy and performance.  Available in a faster set time to increase patient comfort and reduce chair time without compromising performance or working time.  The improved thixotropic consistency reduces slumping and displacement from the impression tray. Indications: Preliminary impressions, provisional crown and bridge impressions, study models, registration/opposing dentition impressions, impressions for orthodontic models, sports guards,64
  65. 65. 4. SILGINAT(Kettenbach LP)  It is a medium viscosity addition-curing elastomeric polyvinyl silioxane impression material with alginate-like consistency, specially developed for taking impressions of the opposing jaw, temporary crowns/bridges and fabricating splints.  The use of an A-silicone for opposing jaw impressions as well as for precision impressions and bite registration leads to an optimal standardized interaction.  Silginat is stable, has a low tear resistance and is easy to disinfect.  Quantity - Cartridge (38 mL)  Working Time - 76 - 90 seconds  Complete Set Time - 2 min 30 secs  Viscosity - Medium Body  Set Times Available - Regular Set 65
  66. 66. 5. SILGINAT FOIL BAG ALGINATE SUBSTITUTE MATERIAL  Quantity Foil Bag - (362 mL)  Working Time - 90 seconds  Dispensing Plug & Press Dispensing System  Complete Set Time - 3 minutes  Viscosity - Medium Body  Set Times Available - Regular Set 66
  67. 67. 6. STATUSBLUE(dmg america)  StatusBlue is an efficient, clean and stable alginate alternative.  A-silicone formula makes it quick and easy to take situation impressions for temporaries, model-cast dentures, orthodontic models, and opposing jaw models.  100% dust-free and cold disinfected, allowing for clean and safe impression taking and delayed pouring, or re-pouring of impressions.  Quantity - StatusBlue for Automix Guns Canister 7 (+1 FREE) 50ml Cartridges 16 Automix Tips  Working Time - 1:15  Dispensing - Gun  Complete Set Time - 1:45  Viscosity - Type Medium Bodied ( < 35mm)  Set Times Available - 1:45 67
  68. 68. 7. FREEALGIN MAXI ( Zhermack , inc)  A-silicone, alginate alternative, fast setting, medium viscosity for all alginate indications. Packaged for all automatic mixing machines.  1:1 mixing ratio.  Quantity - 6 X 380 mL Cartridge  base and catalyst 2 bayonet ring  Dispensing - Automatic Mixing Machine  Scent/ Flavor - Mangustan Flavour 68
  69. 69. 8.POSITION™ PENTA™ QUICK VPS ALGINATE REPLACEMENT  Accurate, dimensionally stable preliminary impressions that take less time.  The material offers a fast working and setting time, and is ideal for all typical alginate impression indications.  Multiple pour capabilities save time and money, no need to pour immediately, and no cleaning of bowls and spatulas.  it is dispensed at the touch of a button through 3M ESPE’s fully automated Pentamix™ 3 Automatic Mixing69
  70. 70.  Quantity - Kit includes: 1 base paste – 300ml; 1 catalyst – 60ml; 1 Penta™ cartridge, lavender; 6 Directed Flow Impression Trays (1 each size S, M, L, Upper and Lower)  Working Time - 1 min 10 sec (including mixing)  Dispensing - Automatic Mixer  Complete Set Time - 2 min 40 sec  Viscosity - Medium Bodied  Set Times Available - 3 min (Position Penta) and 2 min 40 sec (Position Penta Quick) 70
  71. 71. 9.ANTISEPTIC ALGINATE IMPRESSION MATERIAL  Introduced by Tameyuki Yamamoto, patented in 1990.  An antiseptic containing alginate impression material contains 0.01 to 7 parts by weight of an antiseptic such as glutaraldehyde and chlohexidine gluconate per 100 parts by weight of a cured product of an alginate impression material.  The antiseptic may be encapsulated in a microcapsule or clathrated in a cyclodextrin. 71
  72. 72. 10. CAVEX COLOR CHANGE  Material with color indications avoiding confusion about setting time.  Color changes visualizes the major decision points in impression making initially - white end of mixing time - violet end of setting time – pink to white  Other advantages of this material are improved dimensional stability (upto 5 days) Good tear and deformation resistance Dust free Smooth surface, optimum gypsum compatibility. 72
  73. 73. 11.LOW DUST ALGINATE IMPRESSION MATERIAL Introduced by Schunichi in 1997.  This composition comprises an alginate a gelation regulator and a filler as major components which further comprises sepiolite and a tetraflouroethylene resin having a true specific gravity from 2-3.  The material generates less dust, has a mean particle size of 1-40microns. 73
  74. 74.  ADVANTAGES Easy mixing Excellent stone surface Unsurpassed smoothness Fine detail  Packed in 1 lb poly- aluminium pouches to increase shelf life and reduce storage space.  2 scoops impression per pound.  Available in 2 forms – identic dustfree and kromaFaze 74
  75. 75. ALGINATE  Material changes colour signaling when to carry out each stage of the procedure Purple – spatulate Pink – load tray white – insert for impression  The color change is because of the indicator present: PHENOLPHTHALEIN  Total elapsed time from start to finish is just over 1 minute.  Impression can be kept over 100 hours without distortion or shrinkage by simply rinsing and enclosing in a plastic bag. 75
  76. 76. 13. ALGINMAX (FUNG INT.)  High precision chromatic dental alginate.  Excellent dimensional stability allows casting of the impressions even after 5 days (if impressions are correctly stored in sealed containers).  Dust free alginate and lead and cadmium free.  Excellent gypsum compatibility and biocompatibility.  Very high compressive strength and recovery from deformation.  Flavour – vanilla mint  Color – pale blue  Setting time – 3 min  Shelf life – 3 years 76
  77. 77. 77  Specifically designed for use with any automatic delivery and mixing system, Kettosil incorporates all of the advantages of polyvinyl siloxane for accurate, fast and easy impressions in any indication where an alginate would normally be used .  Excellent Dimensional Stability.   Extremely low linear dimensional change value of 0.20% comparable to polyvinyl siloxanes.  fullest possible recovery after removal from mouth, low shrinkage during setting 14. KETTOSIL
  78. 78.  Kettosil impressions can be poured 30 minutes after removal from the mouth and up to 21 days after impression taking.  Highly thixotropic properties for smooth, controlled flow under pressure while minimizing material slump and patient gagging.  Supplies bubble-free reproduction of surface detail and critical areas such as gingival crevices and occlusal grooves.  Reproduces every oral detail in stone study or opposing models. Perfectly defined margins. 78
  79. 79.  High Recovery From Deformation of 99.2% .  No Wasted Material Activated cartridges of Kettosil can be sealed by leaving unused material in the filler tip.  For the next impression, simply remove the previous tip, then dispense as per routine.  Total working time of 1 minute 20 seconds.  maintains accuracy, saves time and maximizes patient comfort. 79
  80. 80. Agar Alginate 3) Dimensional accuracy PROPERTIES 1) Flow 2) Elasticity 4) Dimensional stability Excellent Elastic 98.8% Imbibition and synersis Can record fine details Elastic 97.3% No dimensional changes Imbibition and synersis No dimensional changes 80
  81. 81. 5) Adhesion With the tray 6) Compatibility with Cast Manipulation Special equipments No Special equipments Addition accept addition Does not accept Tear strength Electroplating Can not be it can be Dipped in 2% K2SO4 Special perforated tray More compatible. needs perforated stock tray Dipped in 2% K2SO4 Less compatible 81 agar alginate
  82. 82. TYPES OF FAILURES DISTORTION -Delayed pouring of impression. -Movement of the tray during seating. - Early removal from mouth. - Improper removal from mouth. GRAINY IMPRESSION - Inadequate mixing - Prolonged mixing - Less water in mix TEARING - Inadequate bulk - Moisture contamination - Too early removal from mouth - Prolonged mixing 82 CAUSES
  83. 83. BUBBLES - Early gelation - Air incorporation VOIDS - Excess moisture or debris on tissues ROUGH OR CHALKY STONE CAST - Improper cleaning - Premature removal of cast - Improper manipulation of stone 83
  84. 84. Alginate (Irreversible hydrocolloid):  All the instrument i.e. rubber bowl, spatula are sterilized or disinfected by spraying with 0.5% NaOCl or 2% glutaraldehyde.  Spray technique - Rinse under tap water to clean saliva or organic debris. Trim excess alginate from non-critical areas to decrease amount of Microbial contamination. Spray the entire impression surface and the reverse side of the tray as well. It can be kept in a plastic bag or humidor for the recommended exposure time. .84 DISINFECTION OF IMPRESSION PROCEDURE MATERIALS
  85. 85.  When it reached the lab, it is again cleaned with water and stone cast is poured.  For immersion technique, disinfectant with short exposure time is selected to minimize distortion and deterioration of cast.  Aluminium sulfate treatment of alginate impression: After disinfection, the impression is sprayed with aluminium sulfate and kept for 90 seconds in a humidor. Casts produced have better details and surface smoothness than impression disinfected but untreated. 85
  86. 86. CONCLUSION  Success of alginate hydrocolloid impression material since its emergence as an alternative to reversible hydrocolloid was mainly due to its ease of manipulation , comfort to the patient and less cost .  But the facts like its dimensional instability, its incompatibility with gypsum and availability of better alternatives like elastomers which produce better surface detail has replaced it but still it is the impression material of choice in the field of dentistry. 86
  87. 87. REFERENCES Philip’s science of dental materials (11thEdition)- Anusavice KJ  Restorative Dental Materials (11thEdition)- Craig RG, Powers JM  Fundamentals of Fixed Prosthodontics (3rdEdition) – Shillngberg Jr HT et al  Contemporary fixed prosthodontics – Rosensteil  Textbook of Operative Dentistry – Sikri VK  Basic dental materials – 1st edition – manapallil JJ  Operative Dentistry Modern Theory and Practice (Indian ed. 1) - Marzouk MA, Simonton AL, Gross RD 87

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