Alginate

Question 1

Components of alginate

Answer 1

1. Soluble alginate (Na/K alginate)
   Dissolves in water to react with Ca ions
2. Calcium sulfate dihydrate
   Provides Ca ions to create insoluble Ca-alginate gel
3. Sodium phosphate
   Retarder, slows setting of reaction by reacting initially with Ca ions before alginate.
4. Fillers - diatomaceous earth
   For gel texture, strength and stiffness
5. Pigments, flavouring, colour indicators for setting time, disinfectants
6. Fluoride - accelerant for setting of dental stone when poured. –> hard, dense cast.

Question 2

Alginate critique

Answer 2

Size of tray - All anatomical features and teeth present, tray not showing through the impression
Mix - no air bubbles or voids, no powder left behind
Amount -
Teeth recorded past CEJ.
Extends into the sulci, soft tissues captured - buccal and lingual rolls.
Retromolar pad and maxillary tuberosity captured
Palatal extension past hard palate-soft palate junction

Removal - removed correctly, no tears
Time - smooth surface, no streaks

Question 3

Patient needs to retake impression

Answer 3

Apologise
Explain why need to retake - the impression did not come out as clear as we wanted
Identify what went wrong and what we will rectify this time
Emphasise to pt - it’s because we want the best fit for the nightguard/denture/appliance to be constructed.

Question 4

Patient with history of gagging

Answer 4

Listen and acknowledge concerns
Ask about previous experience - what the previous dental operator did, known techniques for helping the situation
Suggest some techniques if not discussed - salt on palate, back of tongue/topical anaesthetic spray
Implement the techniques while taking impression
Make sure not to overload tray in posterior region. Sit patient upright with head slightly tilted forward.
- can pre-empt emit bag out of patient’s sight
- can make water warmer so it sets faster
After that, ask what went well and what could’ve been improved
Record in patient’s notes for future reference.