Influence of Denture Cleansers on Dynamic Viscoelasticity of Soft Liners

Objectives: This study aimed to evaluate the influence of immersion in various types of denture cleansers on the dynamic viscoelastic properties of soft denture liners.
Methods: An acrylic permanent soft liner (Flexacryl Soft), silicone permanent soft liner (Sofreliner Tough Soft), and temporary soft liner (Shofu Tissue ConditionerII Soft) were analyzed. For cleansers, Labarraque D, Polident Enzyme, Quick denture cleaner, Sawayaka Correct W antibacterial, and distilled water were selected as hypochlorous acid, peroxide with enzyme, phosphoric acid, silver-based inorganic antibacterial agent types, and control, respectively. Five 2-mm-thick samples (30mm × 20mm) of each material were prepared for each cleanser. Samples were immersed in cleanser for one week at 23±2°C with the cleanser replaced every 12 h. The storage modulus (G’), loss modulus (G”), and loss tangent (G”/G’) of each material (n=5) were determined at 1 Hz and 37°C using a dynamic viscoelastometer. Loss tangent values were evaluated because they are considered more important than G’ or G”. Differences were compared using Student’s t-test.
Results: For the silicone permanent soft liner, no large differences were found between loss tangent values before (0.07±0.01) and after immersion in the cleansers (0.07±0.01 to 0.09±0.01). For the temporary soft liner and especially acrylic permanent soft liner, significant differences were found between loss tangent values before (0.23±0.01 and 0.19±0.02, respectively) and after immersion (0.19±0.00 to 0.35±0.05 and 0.54±0.01 to 0.64±0.27, respectively; p<0.05). G’ and G” for both permanent soft liners showed almost the same tendency as the loss tangent. However, these values for the temporary soft liner did not change significantly after immersion in peroxide with enzyme.
Conclusions: The viscoelasticity of silicone permanent soft liners is not affected by all denture cleansers. However, the acrylic permanent soft liners are deteriorated by all denture cleansers. The temporary soft liners could be cleaned by only peroxide with enzyme.