Evaluation of viscoelastic properties, hardness, and glass transition temperature of soft denture liners and tissue conditioner

Abstract

Soft denture liners and tissue conditioners are widely used for the denture patients to cushion masticatory force and condition abused tissues, respectively. This study assessed methods for the evaluation of the viscoelasticity and glass transition temperature (T g) of the silicone permanent soft liner, acrylic permanent soft liner, and tissue conditioner. Three rheological parameters of storage modulus (E′), loss modulus (E″), and loss tangent (tan δ), T g , and hardness were determined using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and the Shore A0 hardness test. Five specimens were measured for each material. The time-temperature superposition principle was applied to produce master curves of E′, E″, and tan δ for the tested materials at a reference temperature of 37 °C. The acrylic permanent soft liner and tissue conditioner exhibited viscoelastic behavior and sensitivity to frequency, especially at lower frequencies. The silicone permanent soft liner showed elastic behavior and was frequency-independent. T g for the acrylic permanent soft liner was higher than that for the tissue conditioner, which in turn was higher than that for the silicone permanent soft liner for both DMA and DSC. In DMA, a higher frequency led to higher T g values. A positive linear relationship was found between Shore A0 hardness and E′ values, but not E″ and tan δ values. Shore hardness reflects elasticity, but not viscosity. The results of the present study can be used to improve methods for evaluating the viscoelasticity and T g of soft denture liners and tissue conditioners.

Comparison of Mechanical Properties of Three Tissue Conditioners: An Evaluation In Vitro Study

“…For instance, GC Tissue Conditioner exhibited an increase in hardness from 19.0 to 50 Shore A after 14 days, while FITT 1.2/1 increased from 11.1 to 33.4 Shore A during the same period. These findings emphasize the importance of material selection based on the desired hardness, which may vary depending on the specific clinical situation [ 31 ].…”

Analyzing SHORE A hardness to assess the durability of soft denture lining materials

“…This issue is particularly evident in the lower arch, making the prostheses adaptation more challenging than the maxillary one. Users of complete mandibular dentures often experience poor retention and stability [5] To enhance the quality of life and offer functional and aesthetic advantages of complete dentures, lining materials are commonly used [6][7][8]. They can be categorized based on their chemical structures: hard liners, typically made of PMMA, and soft denture liners (SDL), which include plasticized acrylic resins, vinyl resins, rubber-based materials, and silicone rubbers.…”

Deeper insights into the thermal properties of epoxy thermoset resins using torsion measurements

“…DSC and DMA are often used for measuring the T g of epoxies and are the methods of focus in this study. 2,4,[7][8][9] Dilatometry and TMA can be used to understand the thermal expansion properties of epoxy materials and assist in the precise calculation of the coefficient of thermal expansion. [10][11] These analysis methods have been used extensively in previous studies to characterize epoxy thermoset materials for a variety of applications, especially DSC, DMA, and TMA.…”

“…Generally, the thermal and mechanical properties of epoxies are typically measured using a combination of techniques including differential scanning calorimeters (DSC), dynamic mechanical analyzers (DMA), dilatometers, thermomechanical analyzers (TMA), thermogravimetric analyzers (TGA), 4–6 and durometers. DSC and DMA are often used for measuring the T g of epoxies and are the methods of focus in this study 2,4,7–9 . Dilatometry and TMA can be used to understand the thermal expansion properties of epoxy materials and assist in the precise calculation of the coefficient of thermal expansion 10–11 …”