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Altered Cast Technique

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Presentation on theme: "Altered Cast Technique"— Presentation transcript:

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

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