Dynamic viscoelastic properties of vinyl polysiloxane denture soft lining materials

Area of Science:

• Materials Science
• Biomaterials Engineering
• Dental Materials

Background:

• Vinyl polysiloxane (VPS) materials are used as denture soft liners.
• Understanding their dynamic viscoelastic properties is crucial for clinical performance.
• Water absorption can affect the mechanical behavior of these polymers.

Purpose of the Study:

• To investigate the dynamic viscoelastic properties of commercial VPS denture soft lining materials.
• To determine how wet storage affects complex modulus (E*) and loss tangent (tan delta).
• To establish optimal evaluation periods for material selection.

Main Methods:

• Seven VPS materials were tested.
• Rectangular specimens were subjected to dry and wet storage at 37°C.
• Dynamic viscoelastic properties (E* and tan delta) were measured using forced vibration at 1 Hz.
• Statistical analysis included one-way ANOVA and Bonferroni/Dunn's test (P < 0.01).

Main Results:

• All materials exhibited varied viscoelastic properties.
• Initial wet storage (1 day) increased E* and decreased tan delta.
• After 60 days of wet storage, E* and tan delta showed no significant changes.
• Stiffer materials (>30% filler) displayed elastic behavior (tan delta ~0.03).
• Softer materials (6% filler) showed viscous behavior (initial tan delta > 0.10) and were affected by water absorption.

Conclusions:

• Viscoelastic properties of VPS denture soft lining materials change significantly with water absorption.
• Evaluation after 60 days of wet storage is critical for accurate material selection.
• Material stiffness and filler content correlate with elastic and viscous behavior.