Mouth Preparation and Master Casts Flashcards
What is phase I of patient treatment?
– Relief of pain & infection
– Collection of diagnostic data (Diagnostic cast, Diagnostic mounting)
– Develop treatment plan/Design RPD
– Patient education & motivation
– Occlusal equilibration
What is phase II of patient treatment?
– Removal of deep caries, temporary restorations
– Extraction of non-retainable teeth
– Preprosthetic surgery: tuberosity reduction, etc.
– Periodontal treatment, Plaque control
– Interim prosthesis: function, esthetics
– Occlusal equilibration, may need changes after extractions
What is phase III of patient treatment?
– Definitive endodontic treatment
– Definitive restorative treatment
* Surveyed crowns, if needed
* Fixed partial dentures, if appropriate
– Occlusal plane correction
What is phase IV of patient treatment?
– Construction RPD
What is phase V of patient treatment?
– Post-insertion care
– Periodic recall
– Continued plaque control
What is involved in mouth preparation?
- Relief of pain & infection
- Caries removal
- Extractions, Preposthetic surgery
- Periodontal treatment, plaque control
- Occlusal equilibration
- Endodontics
- Definitive Restorative Treatment
- Occlusal plane correction
- Enameloplasty for RPD
What do you draw on the diagnostic cast?
- preliminary design of RPD
- identify tooth modification areas
How do you decide what tooth modifications need to be made?
– according to RPD diagnostic cast design
– QA Worksheet
What are the steps for an enamoplasty for RPD?
- Develop Guide Planes
- Enlarge embrasure for minor connectors
- Lower Height of Contour
- Create undercuts if needed
- Prepare rest seats
Where are guide planes that you develop on the proximal side of teeth?
adjacent to edentulous areas
What are guide planes for on the ML side of teeth?
stress-release clasps ML minor connector
What is the guide planes for on the lingual side of teeth?
reciprocal clasp
What should the height of contour be lowered for on the tooth?
– Proximal 2/3 Circumferential retentive clasp
– Reciprocal clasp
– Lingual Guide Plate
What is the sequence to confirm that preps are parallel to path of insertion?
- Prepare guiding planes
- Enlarge embrasures for minor connectors
- Reposition the survey line to reduce interferences to framework placement and enable most ideal clasp placement
When doing an undercut preparation what is contraindicated?
Sloped buccal &/or lingual surface
When doing an undercut preparation what is indicated?
slightly insufficient retentive undercut with vertical buccal & lingual surfaces
When would you do an undercut preparation?
Used when slightly insufficient retentive undercut
How do you check adequacy of the occlusal/embrasure rest seats?
– Patient close into beading wax
– Measure thickness of wax (Caliper)
* At least 1mm
What should you do if you are unable to attain adequate depth within enamel for the rest seat?
Remove small amount of opposing tooth structure
– Be sure to remake impression of opposing arch
When do you do a rest seat preparation?
After adequate preparation for GP, Survey line alterations
What is the preferred technique for class III RPD impression technique?
Custom tray/elastomeric material
- not border molded
- medium-bodied PVS
What are the different options for a class III RPD impression technique?
- Alginate/stock tray
- Alginate/custom tray
- Custom tray/elastomeric material
What is an important source of RPD support?
residual ridge
What is the broad-stress distribution concept?
- Distribute occlusal forces over as many teeth & as much soft tissue as possible
- Not overload teeth or tissue
- Increased stability & retention
- Less frequent reline
What is the main problem with tooth-tissue supported RPDs?
Due to the lever effect of the distal extension base, occlusal pressure is concentrated on the distal end of the base
The periodontal membrane allows for ______ mm movement with a tooth-tissue supported RPD
0.25 +/- 0.1
The muco-periosteum allows for ____ mm movement with a tooth-tissue supported RPD
2.0 +
What is the solution for tooth-tissue supported RPDs?
- Equalize support derived from tissue and teeth
- To distribute load to both the natural and artificial dentition & minimize base movement
What are the different techniques for extension RPD impression?
- Custom tray/elastomeric material
- Corrected (Altered) Cast technique
What is the corrected (Altered) Cast technique for extension RPD impression?
– Two-step (Dual) impression
* Step one: Impression of teeth & residual ridge
* Step two: Impression of residual ridge areas using framework
What is the Custom tray/elastomeric material technique for extenstion of RPD impression?
– Border-molded tray
– One-step impression
What does Step one: Impression of teeth & residual ridge for an altered cast impression entail?
– Alginate/stock tray or Alginate/custom tray
– Framework fabricated on 1st cast
* Framework less precise than with elastomeric impression
What does Step two: Impression of residual ridge areas using framework for an altered cast impression entail?
– Sectional trays added to framework
– Border-molded
– Elastomeric material
What errors are the altered cast impressions prone to?
operator error
*Lift of distal framework during residual ridge impression
*Framework on final cast not oriented the same as in the mouth
What are the steps for an altered/corrected cast?
*Residual ridge removed
from 1st cast
*Retentive dovetails created
*Framework/impression luted to altered cast
*Cast & impression boxed
*Residual ridge areas poured with yellow stone
*Final cast
Is there a significant difference between the custom tray/elastomeric material and the corrected (Altered) Cast technique?
No
Which technique is more prone to operator error: custom tray/elastomeric material or corrected (Altered) Cast technique?
altered cast procedure
What are the steps for a one-step impression: custom tray?
- Fabricate tray on working/diagnostic cast
- Apply separating medium to cast
- Tray extensions
- Wax spacer placed over tray outline
- Tray stops
- Aluminum foil over wax spacer
- Triad tray material adapted over foil/spacer
- Polymerize
- Add finger rests to tray surface over edentulous areas
- Add handle
- Determine final tray extension at
impression appointment - Border mold distal extension residual ridge areas
_____ mm coronal to vestibule depth in both dentate & edentulous areas for a custom impression tray
2-3
The wax spacer for a custom impression tray should be ___ mm over teeth and ____ mm over residual ridge
~3 mm over teeth
~1.5 mm over residual ridge
What are tray stops for a custom impression tray?
3 widely spaced openings in wax spacer
* 3 mm openings
How do you determine the final tray extension at impression appointment?
– PIP tray flanges: extension & outer surface
– Do border molding movements
– Areas where PIP removed, shorten or thin tray
What are the different elastomeric impression materials?
– Polysulfide: High tear strength, pour within 1 hour
– PVS: Hydrophobic, adequate tissue detail
What are the steps to survey a master cast?
– Determine path of insertion
Equalize undercut
– Mark abutment height of contour
– Measure & mark retentive
undercut
How do you determine the path of insertion when surveying?
- Guide planes parallel, Equalize undercut
Where should you mark abutment height of contour?
- Facial & Lingual
What do you need to do to a master cast?
survey
tripod lateral sides of cast
