What are some of the types and common causes of failures encountered with the alginate impression materials?
The most common dental impression errors include:
- Poor Tray Selection.
- Inadequate Impression Material Mixing.
- Surface Contamination.
- Poor Margin Detail.
- Internal Bubbles.
- Marginal Tears.
- Choosing the Wrong Impression Material.
- Rushing the Impression.
What is syneresis and imbibition?
In dentistry, syneresis is the expulsion of water or other liquid molecules from dental impression materials (alginate for example) after an impression has been taken. The opposite process of syneresis is imbibition, meaning, a material that absorbs water molecules from the surrounding.
What is weeping or syneresis?
Syneresis is the expulsion (or weeping) of liquid from a gel. It is sometimes a desired result, as in gel filtration. Often it is undesired, such as when the liquid seeps out of pie filling or puddles form on the top of yogurt or margarine.
What is the effect of syneresis and imbibition to the impression made?
Alginate impression materials have low volume stability, since they first undergo expansion, and then shrink over time [5]. In addition, hydrocolloid impression materials develop syneresis and imbibition, which cause water depletion and dimensional changes [6,7].
Why curved spatula is used for alginate mixing?
Curved spatula This is similar to straight spatula but the only difference is that it has a slightly curved blade which helps in mixing the content of the bowl by pressing against the walls of the bowl.
What is the mixing time for alginate?
1 minute
The mixing time for regular alginate is 1 minute and the time should be carefully checked because both undermixing and overmixing affects the strength of the set impression. Fast-set alginate powder should be mixed with water for 45 seconds.
What is Syneresis gel?
Syneresis is spontaneous contraction of a gel, accompanied by expulsion of liquid from the pores. This occurs even if evaporation is prevented and the gel is immersed in liquid.
What is the function of Syneresis?
Syneresis is the process in cheese manufacture whereby the whey component of milk is expelled following curd formation. Factors that interfere with syneresis affect the moisture content and quality of the final product.
What is syneresis gel?
What happens in syneresis or weeping of gel?
On allowing a gel to stand for a long time, it shrinks and loses all its liqiud content. The shrinking of gel is called synresis or weeping.
What’s meant by Imbibition?
Medical Definition of imbibition : the action or process of assimilating, taking into solution, or taking in liquid especially : the taking up of fluid by a colloidal system resulting in swelling.
How do you prevent syneresis and imbibition in alginate?
[10] The impression should then be covered in a damp gauze/napkin to prevent syneresis (generally, not recommended to place in water, which would cause imbibition-expansion). Excess unsupported alginate should be removed with a sharp knife.