Irreversible Irreversible Hydrocolloid Hydrocolloid Irreversible Irreversible Hydrocolloid...
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Transcript of Irreversible Irreversible Hydrocolloid Hydrocolloid Irreversible Irreversible Hydrocolloid...
Student ____________________
Preliminary Alginate Impressions
Date / / Initials_______ Instructor #_____
Unacceptable Correctable Acceptable Student
Unacceptable Correctable Acceptable Instructor __________
Accurate recording of all critical anatomy
Material properly mixed as indicated by impressions
Minimum of voids
Trays properly selected and centered over the ridges
Minimal areas where trays have contacted tissues
Diagnostic Cast Evaluation
Date / / Initials_______ Instructor #_____
Unacceptable Correctable Acceptable Student
Unacceptable Correctable Acceptable Instructor __________
No significant bubbles or flaws in stone
Base approximately parallel to ridge and approximately l/2 inches thick (minimum)
Evidence of a dense stone surface
Clean and well trimmed
Includes all anatomical surfaces
Student ____________________
Preliminary Alginate Impressions
Date / / Initials_______ Instructor #_____
Unacceptable Correctable Acceptable Student
Unacceptable Correctable Acceptable Instructor __________
Accurate recording of all critical anatomy
Material properly mixed as indicated by impressions
Minimum of voids
Trays properly selected and centered over the ridges
Minimal areas where trays have contacted tissues
Diagnostic Cast Evaluation
Date / / Initials_______ Instructor #_____
Unacceptable Correctable Acceptable Student
Unacceptable Correctable Acceptable Instructor __________
No significant bubbles or flaws in stone
Base approximately parallel to ridge and approximately l/2 inches thick (minimum)
Evidence of a dense stone surface
Clean and well trimmed
Includes all anatomical surfaces
Selection of a Stock TraySelection of a Stock TraySelection of a Stock TraySelection of a Stock Tray• 5 -7 mm between tray & tissues – Bulk for strength & accuracy of material– Just short of vestibule – Slightly beyond vibrating line
• 5 -7 mm between tray & tissues – Bulk for strength & accuracy of material– Just short of vestibule – Slightly beyond vibrating line
Stock Tray Selection Stock Tray Selection Stock Tray Selection Stock Tray Selection • Compound on peripheries if needed • Extension only to provide coverage of critical
anatomy • Not for displacing vestibular tissues
• Compound on peripheries if needed • Extension only to provide coverage of critical
anatomy • Not for displacing vestibular tissues
Pre-Measure MaterialPre-Measure Material Pre-Measure MaterialPre-Measure Material
• Infection control – Do not take
containers to your operatory
– Do not handle containers with contaminated gloves/hands
• Infection control – Do not take
containers to your operatory
– Do not handle containers with contaminated gloves/hands
Handling the MaterialHandling the MaterialHandling the MaterialHandling the Material
• Do not leave containers open in a humid environment –Humidity & high temperatures cause
deterioration
• Do not leave containers open in a humid environment –Humidity & high temperatures cause
deterioration
Use Separate BowlsUse Separate BowlsUse Separate BowlsUse Separate Bowls
• Gypsum can cause acceleration of setting of alginate
• Alginate contamination can decrease strength of casts
• Gypsum can cause acceleration of setting of alginate
• Alginate contamination can decrease strength of casts
AlginateAlginate
StoneStone
Measuring AlginateMeasuring AlginateMeasuring AlginateMeasuring Alginate
• Fluff the powder before measuring
• Ensure no large voids
• Fluff the powder before measuring
• Ensure no large voids
Measuring AlginateMeasuring AlginateMeasuring AlginateMeasuring Alginate
• Do not tap the scoop more than once or twice–Compacts the powder
– Thicker mix
• Do not tap the scoop more than once or twice–Compacts the powder
– Thicker mix
PreparationsPreparationsPreparationsPreparations
• Measuring by weight is more accurate than by volume
• Ratio of 1 scoop powder : 1 measure water
• 3 scoops of powder is sufficient for most arches
• Measuring by weight is more accurate than by volume
• Ratio of 1 scoop powder : 1 measure water
• 3 scoops of powder is sufficient for most arches
Regulating Set TimeRegulating Set TimeRegulating Set TimeRegulating Set Time
• Regulate with water temperature
• Water/powder ratio can affect tear strength & viscosity
• Regulate with water temperature
• Water/powder ratio can affect tear strength & viscosity
Mixing AlginateMixing AlginateMixing AlginateMixing Alginate
• Mix for up to 45 seconds
• Smooth creamy consistency
• No lumps or powder should remain
• Mix for up to 45 seconds
• Smooth creamy consistency
• No lumps or powder should remain
Making the ImpressionMaking the ImpressionMaking the ImpressionMaking the Impression
• Wipe alginate onto the occlusal surfaces of any teeth
• Wipe alginate onto the occlusal surfaces of any teeth
Making the ImpressionMaking the ImpressionMaking the ImpressionMaking the Impression
• Don't bottom out on the teeth or the residual ridge–Distort the tissue or move teeth
– Stone leaks between alginate & tray & produces distorted cusp
• Don't bottom out on the teeth or the residual ridge–Distort the tissue or move teeth
– Stone leaks between alginate & tray & produces distorted cusp
Making the impressionMaking the impressionMaking the impressionMaking the impression
• Wait to remove impression until the material is firm
• Approximately one minute after initial set
• Wait to remove impression until the material is firm
• Approximately one minute after initial set
RemovalRemovalRemovalRemoval
• Lift lip up to break the seal against tissues
• Several drops of water
• Remove rapidly, to prevent significant permanent deformation
• Lift lip up to break the seal against tissues
• Several drops of water
• Remove rapidly, to prevent significant permanent deformation
Impression StorageImpression StorageImpression StorageImpression Storage
• Wrap in a damp towel –Wring to eliminate excess water
• Pour within 12 minutes – Minimizes distortion
• Support impression by handle or tray until cast poured
• Wrap in a damp towel –Wring to eliminate excess water
• Pour within 12 minutes – Minimizes distortion
• Support impression by handle or tray until cast poured
Evaluating Irreversible Evaluating Irreversible Hydrocolloid ImpressionsHydrocolloid Impressions
Evaluating Irreversible Evaluating Irreversible Hydrocolloid ImpressionsHydrocolloid Impressions
• Properly mixed
• Smooth surface
• Properly mixed
• Smooth surface
Evaluating Irreversible Evaluating Irreversible Hydrocolloid ImpressionsHydrocolloid Impressions
Evaluating Irreversible Evaluating Irreversible Hydrocolloid ImpressionsHydrocolloid Impressions
• Tray centered over ridge• Tray centered over ridge
Evaluating Irreversible Evaluating Irreversible Hydrocolloid ImpressionsHydrocolloid Impressions
Evaluating Irreversible Evaluating Irreversible Hydrocolloid ImpressionsHydrocolloid Impressions
• No significant tissue/tooth contact• No significant tissue/tooth contact
Evaluating Irreversible Evaluating Irreversible Hydrocolloid ImpressionsHydrocolloid Impressions
Evaluating Irreversible Evaluating Irreversible Hydrocolloid ImpressionsHydrocolloid Impressions
• No-large voids in the impression• No-large voids in the impression
Evaluating Irreversible Evaluating Irreversible Hydrocolloid ImpressionsHydrocolloid Impressions
Evaluating Irreversible Evaluating Irreversible Hydrocolloid ImpressionsHydrocolloid Impressions
• All critical anatomy recorded –Hamular notches–Retromolar pads–Vestibules, etc.
• All critical anatomy recorded –Hamular notches–Retromolar pads–Vestibules, etc.
DisinfectionDisinfectionDisinfectionDisinfection
• Rinse the impression• Place in zip lock bag, pour in
disinfectant to cover all surfaces• Seal for 10 minutes• Remove and rinse prior to
pouring stone
• Rinse the impression• Place in zip lock bag, pour in
disinfectant to cover all surfaces• Seal for 10 minutes• Remove and rinse prior to
pouring stone
Mixing StoneMixing StoneMixing StoneMixing Stone
• Weigh powder
• Measure water
• Vacuum mix– Less time to complete than
hand mixing – Stronger cast
• Weigh powder
• Measure water
• Vacuum mix– Less time to complete than
hand mixing – Stronger cast
Two pour techniqueTwo pour techniqueTwo pour techniqueTwo pour technique
• Pour stone into impression
• Wait for stone to set (~ 30 minutes)
• Invert impression with set first pour onto base stone
• Superior surface strength
• Pour stone into impression
• Wait for stone to set (~ 30 minutes)
• Invert impression with set first pour onto base stone
• Superior surface strength
Two Pour TechniqueTwo Pour TechniqueTwo Pour TechniqueTwo Pour Technique
• Use vibrator & flow the stone into the impression slowly
• Modulate speed of pouring by tilting the tray back and forth
• Use vibrator & flow the stone into the impression slowly
• Modulate speed of pouring by tilting the tray back and forth
Two Pour TechniqueTwo Pour TechniqueTwo Pour TechniqueTwo Pour Technique
• If impression fills too quickly-voids
• To delay filling:– Tilt impression in opposite direction of
the flow of the stone– Reduce speed of vibrator
– Press impression less firmly against
vibrator
• If impression fills too quickly-voids
• To delay filling:– Tilt impression in opposite direction of
the flow of the stone– Reduce speed of vibrator
– Press impression less firmly against
vibrator
Two Pour TechniqueTwo Pour TechniqueTwo Pour TechniqueTwo Pour Technique
• Leave rough areas on the exposed surface of the stone–Helps attach base
• Leave rough areas on the exposed surface of the stone–Helps attach base
Two Pour TechniqueTwo Pour TechniqueTwo Pour TechniqueTwo Pour Technique
• Make a patty of stone
• Invert impression with the first pour onto the base
• Adapt new stone to the existing stone
• Make a patty of stone
• Invert impression with the first pour onto the base
• Adapt new stone to the existing stone
Two Pour TechniqueTwo Pour TechniqueTwo Pour TechniqueTwo Pour Technique
• Trim excess stone from the base with the spatula while the stone is still soft
• Trim excess stone from the base with the spatula while the stone is still soft
Two Pour TechniqueTwo Pour TechniqueTwo Pour TechniqueTwo Pour Technique
• Separate impression from cast after 30 minutes
• Separate impression from cast after 30 minutes
Trimming CastsTrimming CastsTrimming CastsTrimming Casts
• Model moist for trimming–Debris from trimmer will not
attach
• Model moist for trimming–Debris from trimmer will not
attach
Trimming CastsTrimming Casts Trimming CastsTrimming Casts
• Soak the model by immersing– in slurry water
– just base of cast contacting tap water
• Soak the model by immersing– in slurry water
– just base of cast contacting tap water
Trimming CastsTrimming CastsTrimming CastsTrimming Casts
• Prolonged immersion in tap water can lead to erosion of the cast
• Prolonged immersion in tap water can lead to erosion of the cast
Trimming Trimming DiagnosticDiagnostic Casts CastsTrimming Trimming DiagnosticDiagnostic Casts Casts
• Cast should be minimum of 10-12mm (.5 inch) in thinnest part
• Trim the base on the model trimmer parallel to ridges
• Leave the mucous membrane reflection intact for making a custom tray
• Cast should be minimum of 10-12mm (.5 inch) in thinnest part
• Trim the base on the model trimmer parallel to ridges
• Leave the mucous membrane reflection intact for making a custom tray
a
10-12mm
a
10-12mm
Trimming Trimming MasterMaster Casts CastsTrimming Trimming MasterMaster Casts Casts
a
3mm
3mm
LandArea
10-12mm
a
3mm
3mm
LandArea
10-12mm
• Boxed and trimmed with a 3mm wide by 3mm deep land area
• Aids in processing of acrylic
• Diagnostic casts (no land area) – Used for making custom trays
– Land area omitted so material is easier to trim & remove from the
cast
• Boxed and trimmed with a 3mm wide by 3mm deep land area
• Aids in processing of acrylic
• Diagnostic casts (no land area) – Used for making custom trays
– Land area omitted so material is easier to trim & remove from the
cast