1. Altered Cast Technique

2. Altered Cast Technique
Corrected Cast
Modified Cast
Destroyed Cast

3. Altered Cast Impressions
Impression of soft tissue if not captured in framework impression

4. Purpose
Improve adaptation of the denture base to the ridge to minimize movement during function
Equalize stress between ridge and abutments
Improve contours of peripheries

5. When 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

6. Impression Technique Framework must fit intraorally
Add tray to framework
1 mm wax relief
Heat and fully seat framework into wax

7. Check Seating on Cast and in Mouth
After tray added
Rests must be fully seated
Tissue stop contacts cast
No resistance as framework seated

8. Check Peripheries 2-3 mm short of vestibular No displacement when:
Pull on cheeks, lips
Patient activates tongue

9. Border Mold
Same as a denture

10. Altered Cast Impression
Remove wax spacer
Coat tray with adhesive

11. Altered Cast Impression
Polyvinyl siloxane
Carefully load tray -no material under rests, guideplanes, major connector
Seat with pressure ONLY over rests

12. No Pressure Over Tray
Will cause tissue compression

13. Remove & Inspect Impression
Fully seated
No material under rests or minor connectors

14. Send to Laboratory Lab Steps Section cast
Place retentive grooves in cast
Ensure no contact between impression material & cast
Sticky wax framework in place

15. Lab Steps Box impression
Seal retainer, major & minor connector borders
Pour new ridge areas in different color stone

16. 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

17. Next Step
Lab adds record base and occlusion rim to framework for jaw relation records