Lab 2

Question 1

List the stages in cobalt chrome partial denture constructions

Answer 1

1. Primary impressions
2. Technician casts models ands surveys casts
3. Clinical designs dentures, prepares tooth and takes a secondary impression
4. Technician casts models and constructs metal framework
5. Clinical try in metal framework, add wax rims and record occlusion
6. Technician articulates models and sets up teeth
7. Clinically try the models for aesthetics and occlusion
8. Fit denture and review

Question 2

Why do we take primary impressions

Answer 2

1. Treatment planning
2. Surveying and denture design
3. Construction of special trays

Question 3

What do we need to record on primary impressions?

Answer 3

We need accurate impressions of:

1. Teeth- especially abutment teeth
2. Soft tissues including denture bearing areas and sulcus depth

Question 4

list the stages in impression taking

Answer 4

1. Tray selection
2. Tray modification
3. Impression taking with border moulding
4. Assessment of completed impression

Question 5

Describe the ideal tray for primary impression taking

Answer 5

1. Ideally a few mm of space around all teeth
2. All denture bearing area including teeth should be covered by tray
3. The tray should extend to approx 2mm short of sulcus depth

Question 6

Name the 2 types of trays we can use

Answer 6

1. Box trays; for patients with teeth

2. Edentulous tray: for patients without teeth

Question 7

How do we insert the tray into the mouth to take an impression

Answer 7

Rotate the tray into position retracting one corner of the mouth using fingers or a mirror

Question 8

How would we position the impression tray into the mouth

Answer 8

Position the tray over the teeth holding lips and cheeks out of the way

Question 9

What would we ask the patient to do when we are taking an impression of the lower arch

Answer 9

Get the patient to lift their tongue through the middle of the tray

Question 10

How would you position yourself and the patient when taking a lower denture

Answer 10

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

Question 11

How would you position yourself and the patient when taking an upper denture

Answer 11

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

Question 12

When would we need to modify by ADDING material to our impression tray

Answer 12

1. It is too short of the depth of the sulcus in areas where a flange may be required for denture
2. It doesn’t cover all the teeth
3. There is an excessive amount of space where edentulous saddles are

Question 13

When would we need to modify by removing material from our impression tray

Answer 13

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

Question 14

How do we ensure we have good borders on the labial/buccal side when taking an impression

Answer 14

You need to GENTLY manipulate lips and cheeks to mould border of the impression

Question 15

How do we ensure we have good borders on the lingually when taking an impression

Answer 15

Patient is asked to perform movements of the tongue like protrusion, side to side, touch roof to mouth

Question 16

What do we need to check for when assessing out completed impression

Answer 16

Check for:

1. Accurate impressions of teeth- no drags/ blows on teeth
2. Full extent of potential mucosal area for denture extension recorded
3. Sulcuses/ frenal an muscle attachments recorded
4. Alginate in adherent to tray

Question 17

What don’t we need to worry about when assessing our completed impression

Answer 17

1. Air blows in mucosal areas

2. Seeing the tray through the alginate

Question 18

How do we tell the technician where the special tray needs to be extended to

Answer 18

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

Question 19

Who do we use box trays for

Answer 19

For patients with teeth

Question 20

What materials can we use to make primary impressions

Answer 20

1. Silicone putty

2. Red Compound

Question 21

Give 2 specific examples of when we might modify our impression trays

Answer 21

1. When we want to record the sulcus depth
2. 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