Properties Of Soft Lining Materials Research Articles

Evaluation of rheological properties of soft lining materials with different composition under various temperatures

PurposeThe aim of this in vitro study was to evaluate the changes the rheological properties of some soft lining materials, to compare the rheological properties and viscoelastic behaviour at different temperatures.Materials and methodsFive soft lining materials (acrylic and silicone based) were used. the storage modulus (G’), loss modulus (G”), tan delta (tan δ) and complex viscosity (η’) were chosen and for each material, measurements were repeated at 23, 33 and 37 °C, using an oscillating rheometer. All data were statistically analyzed using the Mann Whitney U test, Kruskal Wallis test and Conover’s Multiple Comparison test at the significance level of 0.05.ResultsSoft lining materials had different viscoelastic properties and most of the materials showed different rheological behavior at 23, 33 and 37 °C. At the end of the test (t¹5), at all the temperatures, Sofreliner Tough M had the highest storage modulus values while Visco Gel had the highest loss Tan delta values.ConclusionsThere were significant changes in the rheological parameters of all the materials. Also temperature affected the initial rheological properties, and polymerization reaction of all the materials, depending on temperature increase.Clinical implicationsTemperature affected the initial rheological properties, and polymerization reaction of soft denture liner materials, and clinical inferences should be drawn from such studies conducted. It can be recommended to utilize viscoelastic acrylic-based temporary soft lining materials with lower storage modulus, higher tan delta value, and high viscosity in situations where pain complaint persists and tissue stress is extremely significant, provided that they are replaced often.

Effect of denture cleansers on chemical and mechanical behavior of selected soft lining materials

Objectives The aim of this investigation was to determine the effect of storage in disinfectants and artificial saliva on a series of commercial soft lining materials for dentures. Changes in mechanical properties and the nature of chemicals released into these solutions were studied. Methods Four soft lining materials were studied (Vertex Soft ® and Villacryl Soft ®, both of which are plasticized acrylics; Molloplast B ® and Mollosil ®, both of which are silicone elastomers). All were cured according to manufacturers’ instructions, and then cylindrical specimens (6 mm height × 10 mm diameter) prepared. These were stored under various conditions then loaded in uniaxial compression and the stress measured at a strain corresponding to a 10% deformation to determine Young's modulus. Storage involved exposure either to the following disinfectants: 2% aqueous chlorhexidine gluconate, 2% aqueous sodium hypochlorite, Corega Tabs ® cleansing tablets or 3% aqueous hydrogen peroxide; or to artificial saliva. For the latter, storage involved either immersion in artificial saliva at 37 °C for the whole study, or immersion for 16 h a day and dry at room temperature for the next 8 h each day. GC/MS was used to determine species leached into these solutions. Results The acrylic materials Villacryl Soft and Vertex Soft became less elastic on storage for up to 28 days whereas the silicone materials Molloplast B and Mollosil, showed no change in elastic properties. Various compounds were found to be released from these materials, including EGDMA, methyl methacrylate and dibutyl phthalate. Generally, the silicones were more stable than acrylics, releasing smaller amounts of the various eluants. In all cases, amounts eluted were well below permitted exposure limits. Significance Practical denture cleansing agents affect the properties of soft lining materials, reducing their elastomeric character, acrylics being more adversely affected than the silicones. These changes are associated with the loss of various chemicals, including plasticizers and monomers, from the soft lining materials.

Comparative Study of Water Sorption and Solubility of Soft Lining Materials in the Different Solutions

In this study, two acrylic based materials and three silicone rubber soft lining materials were investigated to determine the percentage of absorption and solubility in artificial saliva, distilled water, and denture cleanser. In addition, the effect of denture cleanser on surface properties of soft lining materials was also evaluated. For sorption and solubility testing, 75 discs (50 mm x 0.5 mm) were prepared and divided into 5 groups with 15 samples in each group. The specimens were stored in different solutions, and tested after 1, 4, and 16 weeks. Analysis of variance was used to find the significant differences between the materials at all time intervals. The acrylic resin soft lining materials had higher solubility (3.432% Visco-gel in artificial saliva) and absorption (3.349% Visco-gel in distilled water) than Molloplast-B after 16 weeks of aging. The greatest hardness and color change were shown in the acrylic soft lining materials.

Effects of cyclic loading on viscoelastic properties of soft lining materials.

The cyclic loadings during mastication supposedly accelerate degradation of soft lining materials. The purpose of this study was to investigate the effects of cyclic loading on viscoelastic properties of soft lining materials. Two plasticized acrylics, two silicones and one isoprene-based monomer contained elastomer were selected. Cylindrical-shaped specimens, 10 mm X 10 mm phi, were prepared. Twenty specimens were subjected to cyclic loading in a water bath at 37 degrees C; another twenty specimens were without cyclic loading. The viscoelastic properties were measured using a creep-meter. The cyclic loading significantly decreased the heights of the two materials, the instantaneous elastic displacements of one acrylic liner and the viscous flows of three materials. The cyclic loading affected mainly delayed deformations. Therefore, cyclic loading was a useful method for evaluating the durability of soft lining material.

The influence of soft lining materials on pressure distribution

Several soft lining materials are available at present that differ in physical and mechanical properties. To examine the feasibility of soft lining materials used as so-called “tissue conditioners,” the properties of soft lining materials were investigated by using a static creep test and a pressure distribution test. Six typical materials were used. The pressure on the testing plate was distributed uniformly on the soft lining materials. The soft lining material acted as a cushion for the external forces. However, the variation of pressures increased with time in the cases of Hydro-cast and Softone materials, but decreased with time in the case of Coe-comfort material.

A mechanical analysis of the physical bonding properties of soft lining materials to PMMA

The bonding properties of soft liners to acrylic denture bases are characterized by their variable resistance to external loading. This resistance depends on the nature of the load, the chemistry and mode of polymerization of the liner, and the topography of the acrylic surface to which the liner is applied. The results obtained indicate that heat-curing acrylic soft liners are superior to silicone rubber materials; and that light smoothing of the acrylic surface prior to processing the liner has a beneficial effect on bonding.

Composition and properties of soft lining materials for acrylic dentures : J. Dent., 9 (1981) 210–223.

Composition and properties of soft lining materials for acrylic dentures : J. Dent., 9 (1981) 210–223.

Composition and properties of soft lining materials for acrylic dentures

Although soft lining materials are inadequate to their requirements their use is widespread. This paper comprises a summary and the conclusions of a comprehensive investigation of these materials which has been undertaken in an attempt to determine which are the better materials and how they may be evaluated. A representative selection of thirteen commercially available soft lining materials was analysed. These, together with four experimental materials, were subjected to laboratory investigation of their water absorption and water solubility; their visco-elastic properties and the effect on these properties of bonding the materials to poly(methyl methacrylate); their rupture properties; their wettability and their effect on the growth of Candida albicans. An attempt was made to relate these properties to the chemical composition of the materials.

Characterization of the rupture properties of denture soft lining materials.

Rupture properties of soft lining materials are characterized by their resistance to tearing. The energy necessary for their rupture depends upon rate of deformation, temperature, and conditions of storage or use. After storage in water for six months, some silicone rubber materials are no stronger than irreversible hydrocolloid materials.