Final Impressions for Complete Dentures

Polyvinyl Siloxanes Polyvinyl Siloxanes Addition Reaction SiliconeAddition Reaction Silicone

• Hydrophobic • Newer materials more hydrophilic

– Similar to Polysulfides & Polyethers

• Flow– Thixotropic– Require pressure to flow

Polyvinyl Siloxanes Polyvinyl Siloxanes Addition Reaction SiliconeAddition Reaction Silicone

• Good dimensional stability• Excellent elastic recovery• Excellent dimensional

accuracy• Material of choice

Wax Spacer RemovalWax Spacer Removal

• After border molding, remove wax spacer

• Do not dislodge border molding

Custom TraysCustom Trays

• Smooth sharp surfaces of border molding or tray

Effect of Sharp BordersEffect of Sharp Borders

Custom TraysCustom Trays

• Place holes in tray to allow release of hydraulic pressure

AdhesiveAdhesive• Paint inside of tray &

border molding • Allow to dry 7-15 minutes

Final ImpressionsFinal Impressions

• Dry tissues with 2x2 gauze folded in cotton pliers

Tissue RestTissue Rest

• Leave dentures out 24 hours – Tissue recovery

• Use low viscosity polyvinyl siloxane material – Use adhesive

Tray 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

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____________________________________________________

TOTALTOTAL1313 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____________________________________________________

TOTALTOTAL1313 99 1010 32 32

Final ImpressionsFinal Impressions

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

• Ensure tray is centered & properly oriented

Tissue ManipulationTissue ManipulationMaxillaMaxilla

• Slight manipulation of cheeks, lips

• Patient moves mandible to side to side for maxillary impression

Tissue ManipulationTissue ManipulationMandibleMandible

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

forward & side to side

Impressions Videos

Final Impressions

Two Mirror Impression Technique

Set TimeSet Time

• Most polyvinyl siloxane materials set within 6 minutes

Evaluating Impression Video

Post-palatal SealPost-palatal Seal

• Compensates for polymerization shrinkage away from palate

• Enhances retention

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

Post-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)

Boxing Final ImpressionsBoxing Final ImpressionsRationaleRationale

• Superior hardness of cast surface• Provides land area & preserves

peripheral role• Minimizes trimming

Trimming the CastTrimming the Cast

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

Boxing Impression Video