Manuals_files/CD Manual 12.pdf - Removable Prosthodontics

Final Impressions - 25
Boxing and Pouring Final Impression
Boxing of a final impression should be:
1. Quick and easy with consistent results
2. Provide support and preserves flange contours
3. Compatible with cast material and impression material
4. Inexpensive
5. Avoid excessive trimming
The right side at the arrow is prepared correctly, with a 6 mm land area which is
horizontal, with approximately 2-3mm of the periphery expose. The left side at the arrow
is prepared incorrectly so that stone will lock around the rigid tray. Don’t cut the alginate
back too deeply below the peripheral role, or the impression will be difficult to remove.
At the posterior border of the impression, make sure the denture is cut back to the vibrating
line (recheck before cutting). The edge of the posterior border should show about 1
mm above the alginate in this area to ensure that the posterior border can be detected on
the master cast. If the impression is perfectly continuous with the alginate, it will not be
possible to discern the posterior border of the denture.
Criteria for Master Casts
! No significant bubbles or flaws in stone
! Includes all anatomical surfaces of final impressions
! Posterior border of maxillary cast clearly demarcated
! Includes 3-4 mm. land area
! Base approximately parallel to ridge and approximately l/2 inches thick (minimum)
! Evidence of a dense stone surface
! Clean and well trimmed (no dried slurry on casts)