HOSA Dental Terminology Practice

What is the defining feature of irreversible hydrocolloid?

1. It can be melted and reused

2. It cannot be reversed once set

3. It remains in a liquid form until applied

4. It requires specific temperature control

The correct answer is: It cannot be reversed once set

Irreversible hydrocolloid, commonly known as alginate, is characterized by its inability to return to a liquid state once it has set. This property is essential in dental applications, particularly for making impressions of teeth and oral structures. Once mixed with water and allowed to set, the hydrocolloid undergoes a chemical reaction that transforms it from a viscous liquid into a gel-like solid. This process is permanent, meaning that it cannot be melted or transformed back into liquid form without damaging the material. This quality is crucial because it ensures that the impression taken remains stable and retains the shape of the dental structures, which is essential for accurate casting and fittings in dental treatments. Understanding this feature distinguishes irreversible hydrocolloid from other materials that can be reused or remolded after setting.