Week 5 PP - Midterm Review

Question 1

What are the types of impression materials available?

Answer 1

-Alginate (irreversible hydrocolloid)
- Agar (reversible hydrocolloid)
-Bite registration using PVS * *

Question 2

What types of impression trays are available (list at least 3)?

Answer 2

Full trays/stock trays
Sextant Tray - quick tray
Triple Tray * *

Question 3

To prevent impression material peeling away from the tray during separation, what can be done?

Answer 3

add adhesive to tray
use perforated trays

Question 4

Dr. Sait additionaly asked you to take elastomeric impression vs using wax that will record centril occlusion, what type of impression will you take?

Answer 4

Polysiloxane material - referred to as PVS, known as elastomeric impression.

Question 5

Why are you looking into a mouth prior to taking impression?

Answer 5

to access oral cavity health status
to determine tray sizes

Question 6

Should the impression tray fit loose or tight?

Answer 6

Loose

Question 7

Upon reviewing C.O you determined that patient
has a moderate bony growth like tori present L -Q 3.
To make the tray more comfortable during
impression taking, what material should you use and
why?

Answer 7

Utility wax - add it to left lingual edge of tray (soften tray rim)

Question 8

What type of alginate mix time should you use for your patient? What chemical ingredient controls setting time?

Answer 8

Mix time is 45 seconds

The temperature of water can affect setting time - cool water allows for more mix time

**

Question 9

What chemical ingredient within alginate makes the material thick?

Answer 9

Zinc Oxide

Question 10

What chemical ingredient within the alginate prevents material from breaking apart when removing from the mouth?

Answer 10

Potassium Titanium

Question 11

Due to patient strong gag reflex, what techniques should you use during appointment?

Question 12

Explain technique for placing impression on mandibular.

Question 13

Explain technique for placing impression on maxillary.

Question 14

How should impression tray be seated: anterior to posterior or posterior to anterior? and Why?

Question 15

Just seconds before seating maxillary tray in
your patients’ mouth, she grabs your hand and tells
you “STOP, I am not ready” What should you do?

Question 16

Both impressions had been taken, what IPC steps
should be done prior pour and what office space will
be used to pour them?

Question 17

Impression criteria for Study Models - what is a MUST?

Answer 17

-Tray is seated fully (bone height fully visible)
-Proper extension over mandible retromolar area is present
-Proper extension over maxillary tuberosity area
-Sharp anatomical detail is present throughout (palate, frenum, gingival, margin outline)

Question 18

What are study models used for?

Answer 18

Used to evalute patient bite, shape of teeth, surrounding tissue

Question 19

What additional tools are available to help with diagnosis?

Answer 19

Face Bow & Articulator

Question 20

What are Preliminary Impressions used in preparation of?

Answer 20

-pre-treatment and post treatment records
-study and diagnostic casts
-in the fabrication of mouth guards (night guards & sport guards)
-whitening trays
-provisional coverage (temp restorations)
-orthodontic appliances
-custom impression trays

Question 21

What is the thickening agent of alginate?

Answer 21

Potassium Alginte - derived from brown algae

Question 22

What is the reactor that promotes gel formation in alginate?

Answer 22

Calcium Sulfate

Question 23

What ingredient in alginate slows down the setting process?

Answer 23

Trisodium Phosphate

Question 23

A filler that improves the rigidity and resistance of the gel in Alginate

Answer 23

Diatomaceous Earth

Question 23

What creates the bulk to the alginate material?

Answer 23

Zinc Oxide

Question 23

What provides strength to alginate?

Answer 23

Potassium Titanium

Question 24

Describe how irreversible hydrocolloid material should be stored and handled

Answer 24

-deteriorates rapidly at elevated temperatures and in the presence of moisture

-material should be stored at cool temperatures and never in an area in which temp may be high. The lid of the container sshould be replaced promptly once dispensed to avoid exposure to humidity

It is recommended that alginate impressions be wrapped in a moist paper towel and poured within manufacturer’s instructions.

Question 25

How should alginate material be prepared?

Answer 25

The mixed material should appear smooth, creamy & shiny. Inadequately mixed material is weaker, and is grainy, and takes much less accurate impression than properly mixed material.

There should be no dry alginate powder left within the mixing bowl or on the spatula after mixing. There should also not be visible graininess in the mixed material.