combo of extension for maximum coverage within tissue tolerance (light pressure or intimate contact with moveable loosely attached tissues in vestibules. Refined w/ minimum of pressure using light body.
Maxillary tray requirements
2-3 mm periphery
rest of tray 1-2mm
10mm long x 15 mm wide handle stright down from ridge
What area of maxillary is not recorded at rest?
posterior palatal seal area
How do you adjust tray to posterior palatal seal area?
1. mark middle of vibrating line
2. ID hamular nothch
3. extend 2-3 mm beyond line
tray compound melting temp?
Preferred impression material?
free flowing, light body, polysulfide
8-10 minute polymerization time
pour within 1 hour
Good impression factors
1. smooth well defined peripheries
2. max extension
3. even pressure
4. initmate tissue contact
How do you record highly mobile hypertrophic tissue with minimum displacement?
window tray impression technique
usually with pts w/ combination syndromedo not remove because ridge is usually knife edged-> tissues cushion and rarely impinge on interocclusal space
window tray technique:
1. outline mobile tissue on cast
2. custom tray has window over mobile area
3. handle middle of palate
4. border mold/polysulfide as usual
Mobile tissue recorded with Zn Oxide material Krex
What material is used to record highly mobile tissue?
window tray technique using Zn Oxide (Krex) over mobile tissues
Lab tasks for 3rd clinical appointment
1. box impressions
2. pour master casts in stone
3. trim, index mark master cast
4. make record bases with occlusion rims
Master cast features
1. 4-6mm land
2. 2-3mm depth of peripheral roll
3. base 15-20mm thick
4. trim, mark
5. notch for future remount
What are the primary support areas of mandible? why?
buccal shelf: parallel to occlusal plane and dense bone that is relatively resistant to resorption
retromolar pad: constant, unchanging, doesn't resorb from denture use. Contains glandular tissue, lower margin of pterygomandibular raphe, fibers of buccinator, superior constrictor and temporalis tendon
what determines length of lingual flange of mandibular denture?
mylohyoid: muscular floor of mouth
extending onto retromylohyoid space improves dentrue stability and retention.