altered cast technique corrected cast modified cast destroyed cast corrected cast modified cast...
TRANSCRIPT
Altered Cast TechniqueAltered Cast Technique
Altered Cast TechniqueAltered Cast Technique
• Corrected Cast
• Modified Cast
• Destroyed Cast
• Corrected Cast
• Modified Cast
• Destroyed Cast
Altered Cast ImpressionsAltered Cast Impressions
• Impression of soft tissue if not captured in framework impression
• Impression of soft tissue if not captured in framework impression
PurposePurpose
• Improve adaptation of the denture base to the ridge to minimize movement during function
• Equalize stress between ridge and abutments
• Improve contours of peripheries
• Improve adaptation of the denture base to the ridge to minimize movement during function
• Equalize stress between ridge and abutments
• Improve contours of peripheries
When NeededWhen Needed
• Mandibular distal extensions (Class I & II)
• Extensive edentulous spans
• Any case where periphery is distorted & needs correction
• Less necessary in maxilla due to major connector contact with palate
• Mandibular distal extensions (Class I & II)
• Extensive edentulous spans
• Any case where periphery is distorted & needs correction
• Less necessary in maxilla due to major connector contact with palate
Impression TechniqueImpression Technique
• Framework must fit intraorally
• Add tray to framework– 1 mm wax relief
– Heat and fully seat framework into wax
• Framework must fit intraorally
• Add tray to framework– 1 mm wax relief
– Heat and fully seat framework into wax
Check Seating on Cast and in MouthCheck Seating on Cast and in Mouth
• After tray added– Rests must be fully seated
– Tissue stop contacts cast
– No resistance as framework seated
• After tray added– Rests must be fully seated
– Tissue stop 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
• Same as a denture• Same as a denture
Altered Cast ImpressionAltered Cast Impression
• Remove wax spacer
• Coat tray with adhesive
• Remove wax spacer
• Coat tray with adhesive
Altered Cast ImpressionAltered Cast Impression
• Polyvinyl siloxane• Carefully load tray
-no material under rests, guideplanes, major connector
• Seat with pressure ONLYover rests
• Polyvinyl siloxane• Carefully load tray
-no material under rests, guideplanes, major connector
• Seat with pressure ONLYover rests
No Pressure Over TrayNo Pressure Over Tray
• Will cause tissue compression• Will cause tissue compression
Remove & Inspect ImpressionRemove & Inspect Impression
• Fully seated
• No material under rests or minor connectors
• Fully seated
• No material under rests or minor connectors
Send to LaboratorySend to Laboratory
• Lab Steps– Section cast
– Place retentive grooves in cast
– Ensure no contact between impression material & cast
– Sticky wax framework in place
• Lab Steps– Section cast
– Place retentive grooves in cast
– Ensure no contact between impression material & cast
– Sticky wax framework in place
Lab StepsLab Steps
– Box impression
– Seal retainer, major & minor connector borders
– Pour new ridge areas in different color stone
– Box impression
– Seal retainer, major & minor connector borders
– Pour new ridge areas in different color stone
Potential Problems with the Altered Cast Technique
Potential Problems with the Altered Cast Technique
• Framework not seated either during impression (material under rest, gp) or when being poured will result in an RPD that won’t fit properly on teeth/tissues
• Stone leaking over teeth during pouring makes articulation impossible
• Framework not seated either during impression (material under rest, gp) or when being poured will result in an RPD that won’t fit properly on teeth/tissues
• Stone leaking over teeth during pouring makes articulation impossible
Next StepNext Step
• Lab adds record base and occlusion rim to framework for jaw relation records
• Lab adds record base and occlusion rim to framework for jaw relation records