14. Altered Cast
Transcript of 14. Altered Cast
Altered Cast TechniqueAltered Cast Technique
Altered Cast TechniqueAltered Cast Technique
• Corrected Cast
• Modified Cast
• Corrected Cast
• Modified Cast
Altered Cast ImpressionsAltered Cast Impressions
• Impression of residual ridge
• Custom impression tray attached to the framework
• Impression of residual ridge
• Custom impression tray attached to the framework
PurposePurpose
• Impression is used to modify master cast
• More accurate relationship between abutments & ridge
• Equalize stress between ridge and abutments
• Correct peripheral adaptation
• Impression is used to modify master cast
• More accurate relationship between abutments & ridge
• Equalize stress between ridge and abutments
• Correct peripheral adaptation
When NeededWhen Needed
• Framework most likely adjusted
• Class I & II - relationship most N.B.
• Extensive Class III & IV cases
• Tooth mobility + compressible mucosa
• Less necessary in maxilla
• Framework most likely adjusted
• Class I & II - relationship most N.B.
• Extensive Class III & IV cases
• Tooth mobility + compressible mucosa
• Less necessary in maxilla
Impression TechniqueImpression Technique
• Well Fitting Framework
• Place relief over ridge– 1 mm wax relief
– Separator (Alcote)
– Heat and fully seat framework
• Well Fitting Framework
• Place relief over ridge– 1 mm wax relief
– Separator (Alcote)
– Heat and fully seat framework
Check SeatingCheck Seating
• If not seated, remove, repeat– Rests fully seated
– Tissue stop contacts cast
– Metal adjacent abutment contacts cast
– No resistance as framework seated
• If not seated, remove, repeat– Rests fully seated
– Tissue stop contacts cast
– Metal adjacent abutment contacts cast
– No resistance as framework seated
Check PeripheriesCheck Peripheries
• 2-3 mm short of vestibular
• No displacement when: – Pull on cheeks, lips
– Patient activates tongue
• 2-3 mm short of vestibular
• No displacement when: – Pull on cheeks, lips
– Patient activates tongue
Border MoldBorder Mold
• Simulate final denture border• Simulate final denture border
Make Altered Cast ImpressionMake Altered Cast Impression
• Ensure tray is well retained by framework
• Remove wax spacer
• Coat tray with adhesive
• Wait 10-15 minutes
• Ensure tray is well retained by framework
• Remove wax spacer
• Coat tray with adhesive
• Wait 10-15 minutes
Altered Cast ImpressionAltered Cast Impression
• Polyvinyl siloxane– Light or medium body
• Carefully load tray• No material under rests,
g.p.’s, max. major connector, etc.
• Seat with pressure over rests
• Polyvinyl siloxane– Light or medium body
• Carefully load tray• No material under rests,
g.p.’s, max. major connector, etc.
• Seat with pressure over rests
No Pressure Over GridworkNo Pressure Over Gridwork
• Fulcruming or tissue compression
• Spring back and lack of tissue contact
• Fulcruming or tissue compression
• Spring back and lack of tissue contact
a
spring-backpressure
Remove & Inspect ImpressionRemove & Inspect Impression
• Absence of voids
• Minimal burnthrough
• Covers supporting tissues
• Fully seated, etc.
• Absence of voids
• Minimal burnthrough
• Covers supporting tissues
• Fully seated, etc.
Send to LaboratorySend to Laboratory
• Lab Steps– Section residual ridge from cast
– Ensure no contact between impression & cast
– Place retentive grooves in cast
– Sticky wax in place
• Lab Steps– Section residual ridge from cast
– Ensure no contact between impression & cast
– Place retentive grooves in cast
– Sticky wax in place
Lab StepsLab Steps
– Box impression
– Ensure water tight seal
– Seal retainer, major & minor connector borders
– Pour new ridge areas in different color stone
– Box impression
– Ensure water tight seal
– Seal retainer, major & minor connector borders
– Pour new ridge areas in different color stone
Problems with the Altered Cast Technique
Problems with the Altered Cast Technique
• If tray is added carelessly, it can alter passive relationship
• Excess impression material under framework
• If inadequately sealed, stone over teeth, can’t articulate model
• If tray is added carelessly, it can alter passive relationship
• Excess impression material under framework
• If inadequately sealed, stone over teeth, can’t articulate model
Record Base for Wax SetupRecord Base for Wax Setup
• Place Denture Base– Hard baseplate wax
• Easier to remove during processing
• Can melt or distort
– Acrylic resin• Harder to remove• More rigid and stable for jaw
relation
• Place Denture Base– Hard baseplate wax
• Easier to remove during processing
• Can melt or distort
– Acrylic resin• Harder to remove• More rigid and stable for jaw
relation
Jaw Relation RecordsJaw Relation Records
• Mount Casts on Articulators– Facebow / Earbow Record
• Maxilla to hinge axis
– Centric Record• Maxilla to mandible position
– Protrusive Record• Program articulator for excursions
• Mount Casts on Articulators– Facebow / Earbow Record
• Maxilla to hinge axis
– Centric Record• Maxilla to mandible position
– Protrusive Record• Program articulator for excursions