Dental OSCE (Objective Structured Clinical Examination) Practice Exam

Which of the following statements about hydrophilic impression materials is true?

1. They absorb water, causing expansion

2. They are the most accurate impression materials

3. They can lead to better retention

4. They are not affected by humidity

The correct answer is: They absorb water, causing expansion

Hydrophilic impression materials are designed to interact favorably with moisture, which is integral to their function in capturing dental impressions. The statement that they absorb water, causing expansion, accurately reflects the behavior of these materials. Because they are hydrophilic, they have an affinity for water and can absorb it when exposed to moist environments, leading to expansion. This characteristic allows them to capture fine details of the intraoral structures more effectively in wet conditions, making them particularly useful in scenarios where saliva or blood might be present. On the other hand, while hydrophilic materials can be very accurate, the assertion that they are the most accurate impression materials is not universally true, as accuracy can depend on various factors including technique and specific material used. The idea that they can lead to better retention is more context-dependent and does not universally apply to all hydrophilic materials. Lastly, being affected by humidity is a fundamental characteristic of hydrophilic materials, conflicting with the statement that they are not affected by humidity at all. Therefore, the statement regarding water absorption and expansion is the most accurate depiction of the properties of hydrophilic impression materials.