Framework Try in Flashcards
what are the tips for the framework try in
- the completed RPD must be passive
- should not exert forces on the teeth or soft tissues
- the tip of each retentive clasp should lie passively in a measured undercut
- short time between impression and frameowkr try in is desirable
- allow adequate time for appointment
what cast will the lab return the framework on
the duplicate or fitting cast
what is the order of prep for RPD
- patient
- preliminary impressions
- diagnostic casts
- mounted diagnostic casts
- practice tooth prep on dx cast then natural tooth prep on patients, survey cronws, custom tray, final impression
- master cast
- clinical procedures- fit framework
- mandibular distal extension RPDs
- altered cast impression
- record base
- jaw relation records
- set denture teeth
- trial insertion
- insert RPD and remount
what cast is block out and relief wax placed on
master cast
master cast is duplicated using
hydrocolloid
- one poured in stone
- one in high heat refractory material
the wax up of the RPD framework is completeted on what cast
refractory
describe the refractory cast
- wax relief and block out
- usually white and the material is high heat investment
what areas should be evaluation the fit of framework on master cast before appointment
- path of placement
-action of retentive and reciprocating arms - areas of interference/scraping of cast
- accuracy of seating
- evaluate external/ internal surfaces for proper finish and construction
describe the intraoral fit of framework
- armamentarium: good light, magnification, mirror and explorer
- fitting and occlusion
how should the framework fit to the teeth
- position direct retainers over abutments
- place fingers over rests and push along the path of placement
- framework should move smoothly with minimal resistance
- balanced resistance should exist
what is balanced resistance
- a more rigid retentive tip on one abutment than another will cause tilting
if the framework is not fully seated:
the retainers will not be passive and will exert forces against the teeth
what external surfaces of RPD should be evaluated
- rests
- major connector and minor connectors
- direct retainers
- indirect retainers
- external finish lines
what should the finish of the intaglio surface look like
- remove bubbles, blebs and artifacts
- surface should be smooth and free from irregularities
- surface is not highly polished
what are possible causes for framework misfit
- faulty impression technique
- faulty casts
- tooth movement
- casting inaccuracy
what is a faulty impression
- lack of uniform thickness of impression material
- intraoral distortion due to tray movement
- extraoral distortion due to faulty handling
what are faulty casts
- improper water to powder rati o
- improper spatulation
- failure to use double pour cast formation technique when making impressions in irreversible hydrocolloid
what is the concern with excessive time lapse from impression to framework try in appointment
tooth movement
what are examples of tooth movement due to occlusal disharmonies or periodontally involved teeth
- mesially inclined mandibular molars
- lone standing premolars
what is tooth movement due to
- excessive time lapse from impression to framework try in appointment
- tooth movement due to occlusal disharmonies/periodontically involved teeth
- recent extractions
what is casting inaccuracies from
- expansion of investment
- shrinkage of Ni-chrome alloys is 2.2 -2.4% during casting
how can you fit the RPD framework intraoraly
- adjust the framework
- adjust the direct retainers
- adjust the occlusion
what are common areas of framework interference
- internal surfaces of direct retainer shoulders
- internal surfaces of direct retainer bodies
- internal surfaces of minor connectors
- interdental papilla areas
what are other areas of framework interference
- reciprocating arms
- lingual plating
- soft tissue
what are disclosing material to identify interferences
- ney spray
- Kerr disclosing wax
- occlude
what is the procedure to locate interferences
- dry the framework
- place thin layer of indicating material
- insert framework along path of insertion
- apply finger pressure
- remove framework and note areas of interference
- adjust area of interference with a small bur or stone
- wipe framework clean and repeat procedure until the framework is seated
- evaluate contact of direct retainers and reciprocating arms
- check for wedging- mod spaces
- adjust the occlusion
what would tell you the framework is seated
- no space around rests and plating
- use air to visualize
the framework should seat without:
a click
what is the objective for adjusting the occlusion with the framework
assure that the same relationship exists in CR and eccentric functional movement with the framework in the mouth, as exists between the teeth when the framework is not present
how should you adjust the occlusion of the RPD framework
- adjust for CR
- maintain bulk of rests for strength
- opposing teeth may need modification
how much should the investment expand
as much as the metal shrinks
- 2.2-2.4%
