Lab 2 Flashcards
List the stages in cobalt chrome partial denture constructions
- Primary impressions
- Technician casts models ands surveys casts
- Clinical designs dentures, prepares tooth and takes a secondary impression
- Technician casts models and constructs metal framework
- Clinical try in metal framework, add wax rims and record occlusion
- Technician articulates models and sets up teeth
- Clinically try the models for aesthetics and occlusion
- Fit denture and review
Why do we take primary impressions
- Treatment planning
- Surveying and denture design
- Construction of special trays
What do we need to record on primary impressions?
We need accurate impressions of:
- Teeth- especially abutment teeth
- Soft tissues including denture bearing areas and sulcus depth
list the stages in impression taking
- Tray selection
- Tray modification
- Impression taking with border moulding
- Assessment of completed impression
Describe the ideal tray for primary impression taking
- Ideally a few mm of space around all teeth
- All denture bearing area including teeth should be covered by tray
- The tray should extend to approx 2mm short of sulcus depth
Name the 2 types of trays we can use
- Box trays; for patients with teeth
2. Edentulous tray: for patients without teeth
How do we insert the tray into the mouth to take an impression
Rotate the tray into position retracting one corner of the mouth using fingers or a mirror
How would we position the impression tray into the mouth
Position the tray over the teeth holding lips and cheeks out of the way
What would we ask the patient to do when we are taking an impression of the lower arch
Get the patient to lift their tongue through the middle of the tray
How would you position yourself and the patient when taking a lower denture
Position yourself so that the height of the patients mouth is at your elbows height
Patient should be sitting upright and you should be infront of the patient
How would you position yourself and the patient when taking an upper denture
Position yourself so that the height of the patients mouth is at your elbows height
Patient should be slightly reclined and you should be behind them
When would we need to modify by ADDING material to our impression tray
- It is too short of the depth of the sulcus in areas where a flange may be required for denture
- It doesn’t cover all the teeth
- There is an excessive amount of space where edentulous saddles are
When would we need to modify by removing material from our impression tray
We will need to trim the tray if the tray is over extended
Over extensions often impede the full seating of the tray when tried in
How do we ensure we have good borders on the labial/buccal side when taking an impression
You need to GENTLY manipulate lips and cheeks to mould border of the impression
How do we ensure we have good borders on the lingually when taking an impression
Patient is asked to perform movements of the tongue like protrusion, side to side, touch roof to mouth
What do we need to check for when assessing out completed impression
Check for:
- Accurate impressions of teeth- no drags/ blows on teeth
- Full extent of potential mucosal area for denture extension recorded
- Sulcuses/ frenal an muscle attachments recorded
- Alginate in adherent to tray
What don’t we need to worry about when assessing our completed impression
- Air blows in mucosal areas
2. Seeing the tray through the alginate
How do we tell the technician where the special tray needs to be extended to
We take an indelible pencil and draw a line 2mm fro the full sulcus depth on the inside of the impression surface to let the technician know here to extend the tray to
Who do we use box trays for
For patients with teeth
What materials can we use to make primary impressions
- Silicone putty
2. Red Compound
Give 2 specific examples of when we might modify our impression trays
- When we want to record the sulcus depth
- When we have large edentulous areas and are using alginate we want the alginate to be the same width the way round so we can modify the tray to make sure the alginate will be the same width
