HOSA Dental Terminology Practice

Which rubber base is known for its excellent dimensional stability?

1. Polysulfide

2. Polyether

3. Polyvinylsiloxane

4. Silicone

The correct answer is: Polyvinylsiloxane

Polyvinylsiloxane is recognized for its excellent dimensional stability, making it a preferred choice in dental applications. This material maintains its shape and accuracy over time, which is crucial for creating precise dental impressions. Dimensional stability is important in dentistry because any distortion during the impression-taking process can lead to inaccurate casts and ultimately affect the fit of restorations such as crowns, bridges, and dentures. Polyvinylsiloxane achieves its stability due to its chemical composition and the way it cures, providing consistent and reliable results. This characteristic is particularly advantageous in scenarios requiring long-term storage of impressions before they are poured, as the impression does not shrink or expand significantly with time. The other options, while useful in certain applications, do not match the dimensional stability provided by polyvinylsiloxane. Polysulfide, for example, is known for its flexibility and tear resistance but can undergo dimensional changes over time. Polyether is also a good material but may not offer the same level of stability and can be influenced by humidity. Silicone may not have ideal dimensional stability compared to polyvinylsiloxane when it comes to precise dental impressions. Hence, polyvinylsiloxane stands out in the context of this question.