final impressions

Final Impressions for Complete Dentures

Final Impressions for Complete Dentures

Potential Impression MaterialsPotential Impression MaterialsPotential Impression MaterialsPotential Impression Materials

• Irreversible Hydrocolloid –Hydrophilic but viscous

– Stock tray distorts vestibular tissues

• Irreversible Hydrocolloid –Hydrophilic but viscous

– Stock tray distorts vestibular tissues


• Zinc oxide & eugenol – Fast set

–Rigid (undercuts difficult),

– Poor taste

• Zinc oxide & eugenol – Fast set

–Rigid (undercuts difficult),

– Poor taste


• Polysulfides – Poor taste

– Poor dimensional stability

– Poor elastic recovery

• Polysulfides – Poor taste

– Poor dimensional stability

– Poor elastic recovery


• Silicones –Addition reaction

–Acceptable taste

–Dimensionally stable

– Elastic recovery

• Silicones –Addition reaction

–Acceptable taste




• Polyethers – Poor taste



– Expensive

• Polyethers – Poor taste



– Expensive

Polyvinyl Siloxanes Polyvinyl Siloxanes Addition Reaction SiliconeAddition Reaction Silicone


• Hydrophobic

• Newer materials more hydrophilic – Similar to Polysulfides & Polyethers

• Flow– Thixotropic– Require pressure to flow

• Hydrophobic

• Newer materials more hydrophilic – Similar to Polysulfides & Polyethers

• Flow– Thixotropic– Require pressure to flow



• Good dimensional stability

• Excellent elastic recovery

• Excellent dimensional accuracy

• Material of choice

• Good dimensional stability

• Excellent elastic recovery

• Excellent dimensional accuracy

• Material of choice

Wax Spacer RemovalWax Spacer RemovalWax Spacer RemovalWax Spacer Removal

• After border molding, remove wax spacer

• Do not dislodge border molding

• After border molding, remove wax spacer

• Do not dislodge border molding

Custom TraysCustom TraysCustom TraysCustom Trays

• Smooth sharp surfaces of border molding or tray

• Smooth sharp surfaces of border molding or tray

Effect of Sharp BordersEffect of Sharp BordersEffect of Sharp BordersEffect of Sharp Borders

Custom TraysCustom TraysCustom TraysCustom Trays

• Place holes in tray to allow release of hydraulic pressure

• Place holes in tray to allow release of hydraulic pressure

AdhesiveAdhesiveAdhesiveAdhesive• Paint inside of tray &

border molding

• Allow to dry 7-15 minutes

• Paint inside of tray & border molding

• Allow to dry 7-15 minutes

Final ImpressionsFinal ImpressionsFinal ImpressionsFinal Impressions

• Dry tissues with 2x2 gauze folded in cotton pliers

• Dry tissues with 2x2 gauze folded in cotton pliers

Tissue RestTissue RestTissue RestTissue Rest

• Leave dentures out 24 hours – Tissue recovery

• Use low viscosity polyvinyl siloxane material –Use adhesive

• Leave dentures out 24 hours – Tissue recovery

• Use low viscosity polyvinyl siloxane material –Use adhesive


• Enough material to replace wax spacer

• Load quickly - viscosity

• Avoid bubbles when loading tray

• Enough material to replace wax spacer

• Load quickly - viscosity

• Avoid bubbles when loading tray


• Cover all border molding with impression material

• Cover all border molding with impression material

Tray InsertionTray InsertionTray InsertionTray Insertion

• Insert side of tray against commissure of mouth & rotating the tray into place while pulling outward on the commissure of the contralateral side

• Insert side of tray against commissure of mouth & rotating the tray into place while pulling outward on the commissure of the contralateral side

Subsurface VoidsSubsurface Voids

Tech.Tech. Dentist Dentist

AA BB CC TOTAL TOTAL

F-BF-B 33 22 11 66 EvenEven 44 33 66 1313 B-FB-F 66 44 33 1313____________________________________________________

TOTALTOTAL 1313 99 1010 32 32

Subsurface VoidsSubsurface Voids

Tech.Tech. Dentist Dentist

AA BB CC TOTAL TOTAL

F-BF-B 33 22 11 66 EvenEven 44 33 66 1313 B-FB-F 66 44 33 1313____________________________________________________

TOTALTOTAL 1313 99 1010 32 32


• Seat tray front to back - use gauze over holes in tray

• Ensure tray is centered & properly oriented

• Seat tray front to back - use gauze over holes in tray

• Ensure tray is centered & properly oriented

Tissue ManipulationTissue ManipulationMaxillaMaxilla

Tissue ManipulationTissue ManipulationMaxillaMaxilla

• Slight manipulation of cheeks, lips

• Patient moves mandible to side to side for maxillary impression

• Slight manipulation of cheeks, lips

• Patient moves mandible to side to side for maxillary impression

Tissue ManipulationTissue ManipulationMandibleMandible

Tissue ManipulationTissue ManipulationMandibleMandible

• Hold tray in position & have patient:– Pucker lips

– Lift & move tongue forward & side to side

• Hold tray in position & have patient:– Pucker lips

– Lift & move tongue forward & side to side

Impressions VideosImpressions Videos

Final Impressions

Two Mirror Impression Technique

Final Impressions

Two Mirror Impression Technique

Set TimeSet TimeSet TimeSet Time

• Most polyvinyl siloxane materials set within 6 minutes

• Most polyvinyl siloxane materials set within 6 minutes

Evaluating Impression VideoEvaluating Impression Video

Evaluation of BordersEvaluation of BordersEvaluation of BordersEvaluation of Borders

• Material should not be more than l mm thick over border molding (otherwise it was not fully seated)

• Material should not be more than l mm thick over border molding (otherwise it was not fully seated)

Post-palatal SealPost-palatal SealPost-palatal SealPost-palatal Seal

• Compensates for polymerization shrinkage away from palate

• Enhances retention

• Compensates for polymerization shrinkage away from palate

• Enhances retention

Post-palatal Seal Post-palatal Seal Post-palatal Seal Post-palatal Seal

• Mark post-palatal seal with indelible stick – Glandular area & vibrating line

• Place impression in mouth, line transfers to impression

• Mark post-palatal seal with indelible stick – Glandular area & vibrating line

• Place impression in mouth, line transfers to impression

Post-palatal SealPost-palatal SealPost-palatal SealPost-palatal Seal

• Disinfect

• Refresh the line with new indelible stick

• Prescribe a mechanical post-palatal seal

• Pour impression in Type III stone (ie. Microstone)

• Disinfect

• Refresh the line with new indelible stick

• Prescribe a mechanical post-palatal seal

• Pour impression in Type III stone (ie. Microstone)

Boxing Final ImpressionsBoxing Final ImpressionsRationaleRationale

Boxing Final ImpressionsBoxing Final ImpressionsRationaleRationale

• Superior hardness of cast surface

• Provides land area & preserves peripheral role

• Minimizes trimming

• Superior hardness of cast surface

• Provides land area & preserves peripheral role

• Minimizes trimming

Boxing ImpressionBoxing ImpressionTrimming AlginateTrimming Alginate

Boxing ImpressionBoxing ImpressionTrimming AlginateTrimming Alginate

Pour the ModelPour the ModelPour the ModelPour the Model

Trimming the CastTrimming the CastTrimming the CastTrimming the Cast

Trimming the CastTrimming the CastLand Area = 4mm WideLand Area = 4mm Wide

Trimming the CastTrimming the CastLand Area = 4mm WideLand Area = 4mm Wide

Boxing Impression VideoBoxing Impression Video

final impressions

Technology