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Impression Materials

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1. The function of impression material is to make a positive copy of an oral structure. True/ False. The function is to make a negative copy, when it is filled with stone; the stone makes the positive copy.
   

2. What can impressions be used on?  A single tooth or the entire mouth.
   

3. What are types of rigid impression materials? Compounds, Plaster, ZOE
   

4. A compound thermoplastic does what in respect to temperature? Softens & hardens.
   

5. A compound has what type of reaction? Physical
   

6. What type of impression is taken using a compound? Edentulous
   

7. Plaster has what type of reaction? Chemical
   

8. Plaster is used to take what type of impression? Edentulous
   

9. ZOE consists of: 2pastes
   

10. Zoe has what type of reaction? Chemical
    

11. Zoe is used for what type of impression? Edentulous
    

12. With ZOE contact with water accelerates: the reaction (setting time) and shortens the working time.
    

13. Non rigid impression materials are: elastic or elastometric
    

14. Hydrocolloid impression materials are: water based.
    

15. Sol= liquid
    

16. Reversible hydrocolloid: changes from sol to gel and back with regards to temperature. Physical reaction
    

17. Irreversible hydrocolloid:  goes from sol to gel by means of chemical reaction. Will not change back.
    

18. What is composed of seaweed and kelp? Alginate
    

19. What type of hydrocolloid is alginate? Irreversible hydrocolloid
    

20. What type of reaction occurs in alginate? Chemical
    

21. The process by which alginate is set? Gelation
    

22. Warm water will affect the set/work time of alginate how? Warm water will shorten it.
    

23. High water to powder ratio means that: there is too much water and not enough powder.
    

24. Alginate is flexible but not perfectly elastic. True / False
    

25. A low water to powder ratio means that the alginate mix will be thicker and have lower flexibility, but will be stronger.
    

26. What will happen if the alginate impression is left in the mouth longer than the set time? The impression will be less likely to tear.
    

27. An increase in the water to powder ratio will have what affect on deformation of alginate? It will increase the deformation and mix will be soupy.
    

28. Alginate will be stronger if a thicker mix is used but what will decrease if this is done? Accuracy of the impression.
    

29. Agar is what type of hydrocolloid? Reversible with respect to temperature.
    

30. Agar is similar to alginate but has better what? Surface detail
    

31.  Describe Polysulfide Rubber impression material: 2 tubes (base & accelerator), poor patient acceptance (stinks and stains), chemical reaction, sensitive to temperature and water.
    

32. Silicone Rubber Impression Materials: Not popular today, poor wettability (material itself is hydrophobic), reprosil is an addition type.
    

33. Polyether Rubber Impression Material, what has the shortest working time of all? Impregum.
    

34. Polyether Rubber impression Material what is the stiffest material? Rubber

Disclaimer: These notes were copied and pasted from files sent to me by Andrea.  They have not been reviewed for errors. You are responsible for checking out the information to verify the accuracy. This site, Amy Nieves and Andrea are not responsible for typographical errors.