IMPRESSION MATERIALSAlginate
Synthetic ElastomersImpression Compound
DR. HIRA RAZAB.D.S
IDEAL PROPERTIES OF AN IMPRESSION MATERIAL
• Accuracy and detail reproduction• Dimensional stability• Manipulation: ease of handling , short setting
time, long working time• Cost effective• Pleasant taste and non-toxic• Compatible with plaster• Tear resistant• Resistant to disinfectants
CLASSIFICATION
HIGHImpression compound
Putty Elastomers
MEDIUMRegular Elastomers
LOWImpression Plaster
Impression Paste [ Zinc Oxide Eugenol]Hydrocolloids [ Agar and Alginate]
Light Body Elastomers
ACCORDING TO 1 - VISCOSITY
ELASTIC • SYNTHETIC ELASTOMERS
POLYSULPHIDES , SILICONES , POLYETHERS
• HYDROCOLLOIDS REVERSIBLE: AGAR IRREVERSIBLE: ALGINATE
RIGID• IMPRESSION PLASTER• IMPRESSION PASTE [ZINC OXIDE
EUGENOL]
THERMOPLASTIC
2- ELASTIC PROPERTIES
• IMPRESSION COMPOUND
• IMPRESSION WAXES
MODELLING/IMPRESSION COMPOUND• Classified as a highly viscous, mucocompressive,
thermoplastic impression material• Types: Type 1: low fusing (impression materials: sheet and stick) Type 2: high fusing (impression trays)• Composition
COMPONENT EXAMPLE FUNCTION
THERMOPLASTICMATERIAL 47%
NATURAL OR SYNTHETIC RESIN OR WAXES
CHARACTERIZES SOFTENING TEMPERATURE
FILLER TALC INCREASES VISCOSITY AND DECREASES THERMAL CONTRACTION
LUBRICANT STEARIC ACID IMPROVES FLOW PROPERTIES
• Sheet /Cake form1. colors: grey, green, red2. softened using a water bath at a temperature of 55-60°C if the conditioning time is too long or if its re-used,
stearic acid can leach out3. Uses 1- primary impression of edentulous arch 2- primary impression of kennedy’s class 1 and 2 [2 piece impression technique] 3- modification of stock tray [borders, palatal vault,postdam]
4- impression of maxillofacial defect for fabrication of obturator [2 piece impression technique]
Under extended tray – thin edge of unsupported impression of the posterior lingual sulcus
• Stick form [ tracing compound]1. colors: grey ,green ,red: indicates fusing temp2. softened with bunsen burner and tampered with
warm water before placing in patient’s mouth.3. Uses 1- border moulding of custom tray for final
impression of edentulous arch: creates peripheral and postdam seal
2- border moulding of custom tray for kennedy’s class 1 and 2
3- modification of stock tray 4- recording impressions of single crowns [copper
ring technique , now superseded by use of silicone]
Modification of impression tray for high palatal vault
• Properties1. Thermoplastic2. Viscous/ muco-compressive3. Poor conductor of heat4. Flows above mouth temperature, sets at mouth
temperature. ( cool water can be sprayed on tray while its in mouth)5. High co-efficient of thermal expansion, hence shrinkage on
cooling and after removal• Advantages1. Can be re-used in same patient there’s a risk of leaching out of stearic acid and change in
flow and properties 2. Possible to make additions3. Non-irritant
4. Mucocompressive5. Good adhesion with tray6. Supports itself if tray is short7. Pouring maybe done within an hour
• Disadvantages1. Risk of burning mucosa2. Difficult to handle, requires skill and experience3. Surface details can not be recorded4. Distorted on removal from undercuts5. Takes time for center to be softened or set 6. Poor dimensional stability
Disinfection with immersion in 0.5 percent hypochlorite , iodophor or gluteraldehyde
Rinse and pour within an hour.
Question:- can cake form be used in custom tray?
ALGINATE• Classified as Elastic ,Irreversible Hydrocolloid
impression material• Composition MATERIAL FUNCTION
SODIUM/POTASSIUM ALGINATE
REACTANT; DISSOLVES IN WATER CONVERTS FROM SOL TO GEL ON CROSSLINKING
GYPSUM [CALCIUM SULPHATE DIHYDRATE]
PROVIDES CA IONS FOR CROSSLINKING OF ALGINATE CHAINS
TRISODIUM PHOSPHATE INCREASES WORKING TIME[RETARDER]
FILLER[DIAMOTACEOUS EARTH]
CONTROLS VISCOSITY , STRENGTH AND ELASTICITY
REACTION INDICATOR COLOR CHANGE ON SETTING
POTASSIUM SULPHATE ORPOTASSIUM ZINC /TI FLUORIDE
COUNTERS INHIBITING EFFECT OF ALGINATE ON SETTING OF GYPSUM ,INCREASING SURFACE HARDNESS
FLAVORING AGENT
• Setting reaction
• Na alginate + CaSO4 [sol] ---> Ca alginate + Na2SO4 [gel]
1. Alginate + water sol form2. Calcium from gypsum is released which cross-links K/Na Alginate
[flexible gel]3. As reaction proceeds, elastic properties develop , viscosity increases,
and color changes4. Role of Sodium Phosphate:• it increases the working time by reacting with calcium ions[ to form
CaPO4] , thereby denying supply of calcium to react with alginate. • setting starts after all the trisodium phosphate has reacted with
calcium ions
There is a well-defined working time during which there is change in viscosity.
1. Fast set alginate: Working time: 1- 2 minutes Setting time: 1.5-3 minutes 2. Normal set alginate
Working time: 3-5 minutes Setting time: 3-5 minutes Controlling the setting 1. Altering W/P ratio[not advised]2. Temperature of water3. Amount of retarder [by manufacturer]Q’s4. Which substance will be less in a fast set alginate?5. Which substance will be less in a less viscous alginate?
• Available as1. Powder in container2. Pre-weighed powder in sachets3. Paste type in 2 viscosities: tray and syringe4. Dustless or Dustfree Alginate
• Silica present in the dust which rises from the can after fluffing alginate powder is a health hazard.
• Dustless alginate powder coated with glycol which bind particles together
• Caution!• Store below 54°C ,in a cool dry place, airtight Humidity and high temperatures can
deteriorate the powder , therefore containers should be kept close
• Keep separate bowls for alginate and gypsum. Gypsum accelerates the setting of alginate,
while contamination of gypsum with alginate affects strength
Alginate Syringe Technique
• USES
1. Impressions of partially dentate arch Removable prosthesis Fixed prosthesis Diagnostic casts Orthodontic appliances Indirect Restorations Bleaching tray Night guard/splint/mouth protectors for atheletes
2. Primary and Secondary impressions of edentulous arch
3. Duplicating material
4. Impression of maxillofacial defect
Q’s What is the ideal impression material for fixed prosthesis? What other material is used as duplicating material?
• Advantages1. Hydrophilic : compatible with stone and saliva/blood2. Elastic enough to be drawn over the undercuts, but tears over the
deep undercuts3. Low viscosity[mucostatic]: records surface details4. Ease of mixing & manipulation5. Setting can be controlled with temperature of water6. Cheap7. Pleasant taste and color8. Non-toxic and non-irritant9. No risk of burning mucosa10. Can be used in stock tray11. Good shelf life
They are good for only one pour per impressionThey can reproduce subgingival contours and anatomy but tear upon removal
• Disadvantages:1. Low tear strength especially in thin section (deep undercuts interproximal and subgingival and sulcular areas)2. Viscoelastic3. Inability to produce fine details4. Poor dimensional stability (dehydration and imbibition]5. Distortion may occur if tray not held immobile during setting.6. Can not be refined/ reused7. Messy to work with8. Can not support itself (modification of tray often required )9. Single pour10. Incompatibility with some gypsum materials[SYNERESIS]11. Pour asap
Gelation takes place next to tissues due to their warmth and any movement of the tray will result in movement of unset portion of alginate in relation to the set portion. This will induce internal stresses that are released on removal of the impression ,leading to distortion.
Under extended tray – thin edge of unsupported impression of the posterior lingual sulcus and RM pad
Add wax or modeling compound in the tuberosity & palatal area for maxillary, or in the lingual flanges for a mandibular impression.
• A maxillary impression taken with combination of impression compound in the distal extension areas and overall alginate impression. Alginate has been cut off on one side to show its thickness.
TWO PIECE IMPRESSION TECHNIQUE
in the presence of deep undercuts (bilateral
lingually tilted premolars) alginate may be stressed beyond its elastic limit on removal.
open inter-dental spaces should be occluded with soft wax prior to inserting the loaded tray,
otherwise the impression material will flow beneath the contact points and lock the impression in place and distortion will occur upon removal.
• Mixing and Manipulation of Alginate
• Mechanical mixing with Alginator• ensures that the alginate mix is the same each time they are
mixed. Mixing time is 60 seconds for manual spatulation and 15 seconds for mechanical.
• Mixing and Manipulation
• 1) Read the directions on the side of the alginate container to identify manufacturer's dispensing and manipulation suggestions.
• 2) Determine if your alginate mix is normal or fast set.• 3) Shake the container two or three times to ensure an even
distribution of contents• 4) Place 2-3 scoops of powder in rubber bowl followed by
corresponding 2-3 measures of water at room temp ( powder in water ensures wetting of powder)• 5) Overfill the scoop with powder, and tap the scoop with the
side of the spatula. Scrape the excess from the scoop with the spatula. Dump scoop into bowl
• 6) Use three scoops for the maxillary arch and three measures of water and two scoops for the mandibular arch
• 7) Mixing should be rapid with wide bladed spatula for 45sec -1min
• 8) Swipe against walls, reducing air bubbles and encouraging a smooth creamy consistency.
(Figure of 8) it should not drip off the spatula when lifted from the bowl • 9)The tray must be filled with the impression material up to
the tray borders and any excess unsupported material (over-filled tray) at the periphery must be removed with the mixing spatula to avoid gag
• 10)The surface of the alginate is smoothed with a wet gloved finger. This reduces entrapment of air against teeth
POWDER IN WATER
Smooth and Creamy mix Not granular or lumpy!
• CARE OF IMPRESSION!!1- Dimensional changes
Alginate impressions must be poured as soon as possible ,or a maximum 10-15 minutes delay
Dehydration occurs on exposure to air leading to shrinkage. Imbibition occurs if immersed in water and disinfectants
This is avoided by 1- pouring immediately2-placing it in 100 percent humid atmosphere [humidor]or3- wrapping in wet/disinfectant soaked paper towel and
sealed plastic bag for 10 minutes at max.
2-Syneresis: mucinous exudate given off by alginate retards setting of
gypsum which leads to chalky /soft cast surface and inaccuracy
this is avoided by 1-immersing impression in a solution of accelerator or using
alginate which already has accelerator [KSO4 or KTiFl] 2- pouring immediately
MAKING IMPRESSION
1. Explain the procedure to the patient
2. Tray Selection: Perforated or Rim-lock stock tray that covers
the postdam and peripheries and has 3-5mm space between mucosa and tray
Tray Modification: Extend with wax or compound as required ,eg postdam, palatal surface,distal extension,borders
Adhesive on plastic tray and nonperforated tray recommended
3. Place the patient upright on headrest with arch parallel to floor [ better to take mandible first]
4. As material is mixed , ask patient to rinse with cool water to eliminate saliva and mucin, reducing surface tension and air bubbles
5. Place some material on occlusal surfaces of teeth, abutments, palate vault and rugae and sulci to avoid air entrapment/voids
6. Retract the cheek away from you and rotate tray into mouth from side near you and insert the tray
Stand behind (for maxillary) and in front of the patient (for mandibular) impression. Retract the cheek with the tray and with your free hand and rotate the tray in the mouth.
7. Centralize the tray ,then seat the tray first on side away from you, then anteriorly while retracting the lip, then side near you
8. Tray shouldn’t be pressed too deep, leaving room for thickness of material over occlusal surfaces
9. Functional movements done before start of setting time
10. Hold tray immobile till it sets, with fingers on right and left premolar areas. (Only light finger pressure to avoid internal stresses)
11. Break seal by retracting lips and cheeks /or using air syringe in buccal sulcus and remove with one quick snap along long axis of teeth
one quick snap allows elastic recovery, and prevents tear or detachment. Impressions are less distorted with relatively high but brief forces than with lower, repeated forces for longer times.
12. Wash with cold water or dust with plaster to remove thick saliva, dry and inspect for anatomical landmarks ,abutments, residual ridge etc
RETRACT SOFT TISSUES
HOLD THE TRAY GENTLY
BREAK SEAL BEFORE REMOVAL
13. disinfection with 1% sodium hypochlorite(household bleach 1:10 dilution) or 2% glutaraldehyde solutions for 10 min [spray form recommended]
Others: iodophor, chlorhexidine,phenol
14. Impression should be hung up, rather than laying on bench so that the heels are not put under weight of impression, neither should they come in contact with hard surface.
15. Rinse ,slightly blow air and pour asap or wrap in disinfectant soaked paper towel in a sealed
LABELLED plastic bag or place in 100 percent humid environment[humidor] for not
more than 10-12 minutes.Before pouring, rinse with water to remove disinfectant.Avoid placing in heat or sunlight
FAULTS IN ALGINATE IMPRESSION
SHORT WORKING OR SETTING TIME
1. HIGH WATER TEMPERATURE2. INCOMPLETE SPATULATION3. LOW W/P RATIO4. IMPROPER STORAGE OF ALGINATE POWDER5. USING TAP WATER
DISTORTION 1. MOVEMENT OF THE TRAY DURING SETTING CAUSING STRAINS2. PREMATURE REMOVAL OF TRAY3. NO QUICK REMOVAL OF TRAY4. UNDUE FINGER PRESSURE DURING SETTING5. DELAY IN POURING6. IMPRESSION PLACED ON BENCH WITH HEELS TOUCHING
TEARING 1. INCREASED W/P RATIO:THIN MIX2. PREMATURE REMOVAL OF TRAY3. SLOW RATE OF REMOVAL OF IMPRESSION FROM MOUTH4. PRESENCE OF DEEP UNDERCUTS5. INADEQUATE MATERIAL IN TRAY6. INADEQUATE SPACE IN TRAY7. EXPIRED MATERIAL
DETACHMENT 1. USE OF NONPERFORATED TRAY WITHOUT ADHESIVE
LOSS OF DETAIL 1. INADEQUATE MIXING:GRAINY MIX 2. PREMATURE REMOVAL OF TRAY3. MUCINOUS SALIVA FILLS IN MINUTE TISSUE FOLDS AND
WRINKLES
CONSISTENCY/GRAINY MIX
1. INCORRECT W/P RATIO2. INADEQUATE MIXING OR WATER ADDED TO POWDER3. HOT WATER FOR MIXING REDUCES MIXING TIME
UNDEREXTENDED 1. INADEQUATE MATERIAL IN TRAY2. UNDEREXTENDED TRAY
DIMENSIONAL CHANGES 1. DELAY IN POURING[IMBIBITION AND SYNERESIS]
POROSITY/VOIDS/PITS 1. AIR ENTRAPMENT DURING MIXING2. AIR ENTRAPMENT ON RUGAE,SULCI,PITS AND FISSURES OF
TEETH LEADING TO BLOW HOLES3. INCORRECT W/P RATIO4. EXCESSIVE SALIVA
POOR STONE SURFACE:ROUGH OR CHALKY
1. FAILURE TO SEPARATE THE CAST AFTER AN HOUR2. EXCESS WATER LEFT ON IMPRESSION SURFACE3. SURFACE BLOW HOLES ON IMPRESSION [BLEBS ON CAST]4. SYNERESIS
Other errors in impression maybe due to • incorrect technique ,for-eg failure to centralize
tray, over-seating • Incorrect size of tray leading to
underextended or overextended impression, entrapment of tongue
DETACHMENT FROM TRAY
LOSS OF TISSUE DETAILS DUE TO MUCINOUS SALIVA
SYNTHETHIC ELASTOMERS
• They were developed mainly for industrial uses
• Now most widely used impression materials due to better accuracy,tear resistance and
dimensional stability as compared to hydrocolloids
1. POLYSULPHIDES/ MERCAPTAN RUBBER BASE/THIOKOL2. CONDENSATION SILICONES3. ADDITION SILICONES/ POLYVINYL SILOXANES4. POLYETHER
• Elastomers are supplied as 2 component paste system or a paste and liquid system
• Set by polymerization reaction to form crosslinked chains
• Four viscosity classes 0 Putty [only in silicones] 1 Heavy-bodied 2 Medium/Regular-bodied 3 Light-bodied
POLYSULFIDE/MERCAPTAN RUBBER BASE
• Also known as thiokol impression materials• Composition Base Paste: polysulphide prepolymer plasticizer for viscosity filler (Ti02 and Zinc) for viscosity sulphur and silica for strength Catalyst Paste: Lead dioxide as reactor sulphur as catalyst oil stearic acid as retarder
• Setting reaction: Condensation polymerisationBy-product : WaterContinued reaction after apparent settingColor change: grey-brownReaction accelerated by an increase temperature and moisture • Working time: 5-7 min• Setting time: 8-12 minutes
• Viscosity heavy-bodied regular -bodied light-bodied Heavy-bodied is more dimensionally stableIt also has less reactive groups, hence produce fewer byproducts
• Viscoelastic optimize elastic recovery with one swift pull should not be used where large and multiple undercuts
are present [96.5% recovery]• Most flexible• Highest tear strength• Hydrophobic: less hydrophobic than condensation
silicone and but more hydrophobic than alginate. it can bear some moisture• Accuracy: excellent detail reproduction with custom tray space in custom tray: 1.5-3mm Adhesive required • Relatively cheap
• Dimensional stability is better than hydrocolloids, but inferior to polyether and addition silicones
Factors affecting dimensional stability 1. Viscoelastic2. Continued setting reaction causing shrinkage3. Evaporation of water(by-product) causing shrinkage
• Pouring of cast is delayed for 7-15minutes to allow for elastic recoil
should be done within 30min- 1hour to minimize dimensional changes
Unlike alginate, cast surface is smoother as elastomers do not retard setting of gypsum
CLINICAL USES
• Clinical Uses1. Crown and bridge with light-bodied injected on
abutment and heavy-bodied loaded in special tray
2. Final impression of edentulous arch with light-bodied in spaced custom tray
3. Corrected final impression of partial denture: Altered Cast Technique
Use diminished with availability of other elastomers
• Disadvantages:1. Stain clothes2. Messy to work with3. Bad smell and bad taste4. Long setting time5. Hydrophobic6. Prone to dimensional changes compromising
accuracy7. Needs custom tray and adhesive to avoid distortion8. Allergic reaction in patients allergic to latex gloves9. Health hazard: Lead toxicity [controversial] lead free polysulphides available now
• Advantages1. Accuracy and fine details in custom tray2. Highest tear resistance2. Long working time3. Most flexible [easy to remove from undercuts]4. Moderately hydrophilic5. Cheaper than other elastomers6. Only radio-opaque material (lead oxide)
POLYETHER
• Supplied as two-paste system • Composition Base paste[large tube] prepolymer, silica as filler and plasticizer Catalyst[ small tube] sulphonate as initiator, silica and oil• Viscosities: Heavy, regular and light-bodied
• Sets by addition polymerisation with no by-products
• Working time: 2.5 minutes Setting time: 4.5 minutes
Advantages:1. Moderate elastic recovery [better than polysulphides]2. Accuracy : detail reproduction [inferior to some addition silicones]3. Low tear resistance4. Maybe used with stock tray
5 Good dimensional stability in low humid conditions
6 Hydrophilic to give void-free impressions : high wettability of oral tissues and compatible with stone
7 Impression should be poured in 2 hours. If kept dry, it maybe poured up to 1 week
• Disadvantages
1. Sets as rigid or stiff , hence poses difficulty in removal from severe undercuts
This can produce deformation,extrude mobile teeth or break teeth on cast while separating from impression.This is resolved by
-blocking undercuts in mouth prior to impression - using newer formulations with reduced silica content
2. Short working time[ improved in newer formulation]
3. Allergy to sulphonic acid catalyst system
Blocking undercuts prior to impression
4. Absorption of water in humid conditions Prolonged immersion in disinfectant should be
avoided. Spray form is preferred.
5. Bitter taste objectionable to patients
6. Expensive
7. Adhesive required
8. Can not be re-poured due to relative stiffness
• Clinical applications:1. Crown and bridge[ light-bodied and heavy
bodied, or regular-bodied as monophase]2. Final impression of edentulous arch in spaced
custom tray [ border moulding with regular-bodied and wash with light-bodied]
3. Final impression of partially dentate arch with regular-bodied
5. Bite registration6. Inlays and onlays7. Stiffness and good wettability facilitate the use
of polyether for impression of implant abutments to pick up copings
BORDER MOULDING WITH POLYETHER
FINAL IMPRESSION OF EDENTULOUS ARCH
• Contraindications1. Mobile teeth2. When taking impression with addition
silicones, polyether shouldn’t be used for border moulding of custom tray
SILICONE IMPRESSION MATERIALS
SILICONE IMPRESSION MATERIALS CONDENSATION SILICONES ADDITION SILICONES
(POLYVINYLSILOXANE)
DISPENSATION 2-PASTE SYSTEM ORPASTE AND LIQUID[CATALYST]
2 PASTES- MANUAL MIXING OR AUTOMIXING GUN
CONSISTENCIES DEPENDING ON FILLER
LIGHT-BODIED AND PUTTY LIGHT-BODIED, MEDIUM-BODIED, HEAVY-BODIED, PUTTY
COMPOSITION BASE PASTE: POLYDIMETHYLSILOXANE PREPOLYMER AND FILLER SILICA
CATALYST PASTE OR LIQUID:ALKYL SILICATE AS CROSSLINKING AGENT, TIN COMPOUND AS CATALYST, OIL-BASED DILUENTS
BASE:SILICONE PREPOLYMER WITH SILANE TERMINAL GROUPFILLER
CATALYST:SILICONE PREPOLYMER WITH VINYL TERMINAL GROUPSFILLERPLATINUM COMPOUNDRETARDER
SETTING REACTION
CONDENSATION POLYMERISATIONBY-PRODUCT: ETHYL ALCOHOL
ADDITION POLYMERISATIONNO BYPRODUCTEVOLUTION OF HYDROGEN GASCOUNTERED BY PALLADIUM ABSORBER
WORKING TIMESETTING TIME
3 MINUTES6-8 MINUTES
2-4.5 MINUTES3-7 MINUTESCHILLING THE PASTES BEFORE USE EXTENDS WORKING TIME
ELASTIC RECOVERY HIGHBETTER THAN POLYSULPHIDES AND POLYETHER
EXCELLENT[99-100%]LESS FLEXIBIBLE THAN C-SILICONE AND POLYSULPHIDE,SO REMOVAL MAY BE DIFFICULT
TEAR RESISTANCE LOW-MODERATELESS THAN POLYSULFIDES
LOW-MODERATELESS THAN POLYSULFIDES
AFFINITY WITH WATER VERY HYDROPHOBIC:DRY FIELD REQUIREDPROBLEM OF BLOW HOLES IN IMPRESSION AND LOW WETTING BY STONE LEADING TO BUBBLESUSE SURFACE ACTIVE SPRAY/WETTING AGENT ON TISSUES TO INCREASE AFFINITY WITH TISSUES AND GYPSUM
HYDROPHOBIC
HYDROPHILIC :ADDITION OF WETTING AGENT IN FORMULATION
ACCURACY AFFECTED BY PRESENCE OF MOISTUREACCEPTABLE WITH STOCK TRAY
EXCELLENT WITH HYDROPHILLIC TYPE ALLOWING BUBBLE FREE STONESGOOD WITH STOCK TRAY
POURING THE CAST AS SOON AS POSSIBLE, WITHIN FIRST 30 MINUTES
UPTO 1 WEEK;PREVIOUSLY, DELAY OF 1HOUR WAS ADVISED TO ALLOW ESCAPE OF GAS WHICH RESULT IN PITTING OR VOIDS IN CAST SURFACE.
INHIBITION BY LATEX /RUBBER GLOVES
NONE SULPHUR COMPOUND [DITHIOCARBAMATE ]IN LATEX GLOVES REACTS WITH CATALYST AND RETARDS SETTING.USE DITHIOCARBAMATE FREE GLOVES OR VINYL GLOVES
DIMENSIONAL CHANGES
•EVAPORATION OF ALCOHOL BY PRODUCT AND CONTINUED SLOW SETTING [SHRINKAGE]•LESS THAN ALGINATE BUT MORE THAN POLYSULPHIDES•POUR AS SOON AS POSSIBLE AND USE TWO STEP PUTTY-WASH TECHNIQUE
LESS POLYMERISATION SHRINKAGE
HEALTH HAZARD NON-TOXICACCIDENTAL SPLASHES CAN CAUSE IRRITTAION AND BLISTERING OF EYES
CONTACT DERMITITS IF MIXING DONE WITHOUT GLOVES
USES FIXED PROSTHESISPARTIAL DENTURECOMPLETE DENTUREWetting agent required
FIXED PROSTHESISPARTIAL DENTURECOMPLETE DENTUREBITE REGISTRATION
CUSTOM TRAY SPACE OF 1.5-3MMADHESIVEPUTTY-WASH TECHNIQUE ELIMINATES USE OF CUSTOM TRAY
SPACE OF 1.5-3MMADHESIVECAN BE USED WITH BOTH STOCK AND CUSTOM TRAY
SMELL /TASTE PLEASANT PLEASANT
COST MOST EXPENSIVE
MULTIPLE POURS POSSIBLE
• Clinical applications:
1. Crown and bridge: Light body on abutment to record details and heavy-bodied/putty to support it in tray or
with regular bodied used in both cases[ monophase]2. Initial impression of edentatulous arch with putty Final impression with Light body in border-moulded spaced
custom tray3. Final impression for partial denture [kennedy’s class 1-2] in
custom tray including altered cast technique.4. Impression for Inlays and onlays5. Bite registration paste [addition silicone only]6. Impression for Implant7. Impression of maxillofacial defect
FINAL IMPRESSION OF EDENTULOUS ARCH
IMPRESSION FOR FIXED PROSTHESIS
IMPROVING FIT OF DISTAL EXTENSION BASE BY ALTERED CAST TECHNIQUE
BITE REGISTRATION PASTE ( PVS light bodied)
IMPRESSION OF MIDDLE EAR
IMPRESSION OF PALATAL DEFECT
COMPARISON OF ELASTOMERIC PROPERTIES
ELASTIC RECOVERY
ACCURACY FLEXIBILITY[EASE IN REMOVAL FROM MOUTH]
TEAR STRENGTH
POLYSULFIDE MODERATE GOOD HIGHEST HIGHEST
POLYETHER MODERATE GOODBETTER THAN POLYSULPHIDE AND C-SILICONES
LOWESTMOST STIFF
LOW
CONDENSATION SILICONES
HIGH GOOD MODERATE LOW TO MODERATE
ADDITION SILICONES
EXCELLENT[HIGHLY ELASTIC]
EXCELLENT[HIGHLY ELASTIC]
MODERATE LOW TO MODERATE
PUTTY-WASH IN STOCK TRAY
MULTIPLE POURS
DIMENSIONAL STABILITY
HYDROPHILIC/HYDROPHOBIC
POLYSULFIDE CUSTOM TRAY TO AVOID DISTORTION
LOWWATER BY-PRODUCT30-60 MIN
MODERATE
POLYETHER YES HIGH IN LOW HUMID CONDITIONSUPTO 1 WEEK
HYDROPHILIC
CONDENSATIONSILICONE
YES
LOWALCOHOLPOUR WITHIN30 MIN
HYDROPHOBIC
ADDITIONSILICONE
YES POSSIBLE, DUE TO BEING DIMENSIONALLY STABLE AND RELATIVELY FLEXIBLE
HIGHUPTO 1 WEEK
HYDROPHOBICHYDROPHILIC
• Disinfection Impression with elastomers are rinsed and then
disinfected with immersion in 2% gluteraldehyde or sodium hypochlorite [1:10] for 10 minutes without loss of accuracy.
Polyether, being hydrophilic, may undergo changes if immersion is longer than 10minutes.
Alternately, polyether can be sprayed by 2% gluteraldehyde, wrapped in disinfectant soaked paper towel and placed in sealed plastic bag for 10 minutes.
The impression is rinsed, dried and poured.
On the authority of Ibn Umar, may Allah be pleased with both of them, who said: The Messenger of Allah (peace and blessings of Allah be upon him) took hold of my shoulder and said, ‘Be in the world as if you were a stranger or a traveller along the path.” And ibn Umar would say, “If you survive till late afternoon, do not expect [to be alive in] the morning. If you survive till morning, do not expect [to be alive in] the late afternoon. Take from your health before your sickness and your life before you death.”(Recorded in al-Bukhari)
Special Precautions!1: For patients who have thick and ropy salivation: a) with LA in guaze anesthesize the palatal salivary glands to avoid
mucous secretions
b)ice cold water rinse
c)bicarb soda rinse
2. For patients who have excessive saliva a) cold water rinse b)cotton roll in floor of mouth and opposite to maxillary 1st
molar ;remove just before impression
c)tandem technique
2. Hypergag reflex/ RetchingExaggerated gag reflex can frustrate both the patient and
the dentist. It can also compromise the treatment plan, procedures and even wearing dentures
It may be so severe that even examination becomes difficult
Retching may also induce salivation.Management1. Reassurance and kind handling.2. Upright position of the patient and stand at the back3. Record lower impression first4. Avoid overloading the tray 5. Distract patient’s mind – talking, raising one foot etc.
6. Posterior palate sprayed or infiltrated with LA ( Posterior 3rd of tongue may also need to be
sprayed)7. Drugs: Sedatives Antihistamines Parasympathetic depressants 8. Impression material with minimum flow.9. Desensitization: patient touches the back of
palate with toothbrush and over weeks,the brush is placed further back until it touches soft palate without causing retching.