irs-t lab communication Flashcards
What information needs to be sent to the lab?
Working impression
Impression of opposing dentition
Inter-occlusal record
Pre op impression
Shade
Type and design of restoration
What are problems with shade taking?
Your colour perception
Lighting conditions
Translucency of tooth
What shade guide do you use?
Vita 3D shade guide
Increase/decrease in value and chroma
1. Determine value (M shades- all the same hue)
2. Determine chroma
3. Determine hue (yellow- L, red- R)
How do you record characterisation?
Charts/tick boxes
Records intensives, opalescent, characterisation
Or take photograph
Why is a diagnostic wax up useful?
Helps you and patient to see what’s possible
Allows planning and communication
Helps decide aesthetics, occlusion, tooth reduction, restoration type/design and treatment plan
How do we do a diagnostic wax up?
Produce study models
Mounted on articulated in ICP if conforming or CR if reorganising
Build up proposed restorations in wax
Can be used to identify problems w proposed plan or discuss tx w patient
1. Trim models
2. Locate together in correct occlusal relationship
3. Glue plastic pieces to models to mount using disposable hinge
4. Use modelling wax to build up
5. Wax up can be duplicated for better or communication
6. Stent can be produced on duplicate to allow direct build ups
What materials are used for impression taking?
Silicones (addition/condensation cured)- addition usually as more stable
Polyethers
Polysulphides
Reversible hydrocolloids
What kind of addition cured silicones are there?
Putty
Cartridge delivered-
Medium (aka mono phase)
Light
Ultra light
What needs to be considered when taking impressions?
Control of dimensional stability
Flow of material into surface detail
Control of material in tray/mouth
What are impression properties dependent on?
Amount of filler
Higher filler content= easy control, good dimensional stability but poor surface detail
Opposite for low filler content
Ideally- lower so take more care when controlling
What is used to take an impression?
2 materials
- putty (heavy body for bulk)
- wash (light body for detail
OR medium body (sometimes in special tray
How is an impression taken?
Twin mix- putty in tray and light bodied around teeth
Two stage- putty impression, then remove, cut away detail of teeth and large undercuts, fill w light body and reseat
Two stage w space- above + space over teeth when taking putty impression so less cutting
Mono phase- in stock/special tray
How can you check the quality of impressions?
Look for air blows, drag and complete impression
Impressions that are primarily putty and in thin session won’t flex enough
