Polyvinyl siloxane

Polyvinyl Siloxane (PVS), also known as addition silicone, is a highly accurate, dimensionally stable, and elastic impression material used in dentistry for making precise dental impressions. Its properties make it ideal for a wide range of dental restorations, including crowns, bridges, and dental implants. PVS materials are favored for their ability to reproduce fine details, ease of use, and patient comfort.

Composition and Properties

Polyvinyl siloxane is a type of silicone rubber composed of a base paste and a catalyst paste. When these two components are mixed, a cross-linking reaction of vinyl and siloxane groups occurs, leading to the material's setting. This reaction is not inhibited by the presence of moisture, which makes PVS materials advantageous over other impression materials like condensation silicone and polyether.

PVS materials exhibit excellent elastic recovery and dimensional stability, meaning they can be removed and reinserted without distortion. They also have a very low shrinkage rate upon setting, which contributes to their accuracy in impression making. Additionally, PVS impressions can be disinfected without losing dimensional stability, allowing for safe handling and transportation to dental laboratories.

Clinical Applications

Polyvinyl siloxane is used in various dental procedures, including:

• Crown and Bridge Impressions: PVS is ideal for creating detailed impressions for crown and bridge fabrications due to its accuracy and dimensional stability.
• Dental Implant Impressions: The material's ability to capture fine details makes it suitable for implant dentistry, where precision is crucial.
• Orthodontic Appliances: PVS impressions are used to create models for orthodontic appliances, ensuring a comfortable and accurate fit.
• Diagnostic Models: Dentists use PVS to create diagnostic models for treatment planning and patient education.

Advantages and Disadvantages

Advantages:

• High dimensional stability and accuracy
• Excellent elastic recovery
• Hydrophobic nature allows for better detail reproduction in moist environments
• Long shelf life and working time

Disadvantages:

• Higher cost compared to other impression materials
• Hydrophobicity can make it difficult to use in extremely wet conditions without proper moisture control
• Some patients may be allergic to components in the material

Handling and Storage

To ensure the best results with PVS, it is important to follow proper handling and storage guidelines. The base and catalyst should be stored at room temperature and away from direct sunlight. Mixing should be done according to the manufacturer's instructions to achieve the correct consistency and working time. Once mixed, the material should be used immediately to avoid premature setting.

Conclusion

Polyvinyl siloxane represents a significant advancement in dental impression materials, offering unparalleled accuracy and stability. Its use in various dental applications underscores its importance in modern dentistry. However, its successful application requires attention to detail in handling and patient management, especially in terms of moisture control and allergy considerations.