Evaluation of colour and hardness changes of soft lining materials in food colorant solutions

Abstract

The aim of this study was to measure the colour stability and viscoelastic properties of three commercially available soft lining materials in vitro, by exposing them to 3% erythrosine, tartrazine and sunset yellow solutions. The colour changes were determined using a computer controlled spectrophotometer. The colour change of three soft lining materials--Molloplast B, Flexor and Coe Super Soft--were determined after 1, 3 and 6 months storage in three different food colorant solutions. The colour changes of Molloplast B was not noticeable. Only the initial colour value of Flexor was significantly different from the other time interval colour measurements. On the other hand, the colour difference of Coe Super Soft was found to be significantly different at all comparative time interval measurements (P<0.05). According to Shore A hardness values, Molloplast B had an initial hardness of 44 in all three solutions, and there was a slight increase after 6 months. Flexor had an initial hardness of 39, at the end of 6 months the hardness changed a little. Coe Super Soft was fairly hard after processing and Shore A hardness was initially 89 which increased to 95 later on. According to these results, only the hardness values of Coe Super Soft showed a statistically significant difference when compared using Wilcoxon signed rank test at the P<0.05 level. As a conclusion, silicon type soft lining material seems to be more resistant to colour change and hardness than the acrylic type soft liners.

Effects of different food colorants and polishing techniques on color stability of provisional prosthetic materials

“…However, according to manufacturers, the concentration of a colorant in some food products may reach 3%. These colorants are soluble in water and as they have electrostatic charges on their molecules, they may stain surfaces 50) . Interestingly, there was no significant difference between the effects of distilled water and food colorant solution.…”

Basic evaluation on physical properties of experimental fluorinated soft lining materials

“…The application of soft lining materials with viscoelastic behavior close to that of mucosa has been reported to be preferable, compared to elastic materials such as silicone rubber-based soft lining materials in the clinical situation 1) . A hardness test, such as the Shore A hardness test has been employed by many researchers [14][15][16]24,25) . There was no significant difference between Shore A hardness of SR12F and MB.…”

“…In addition, the silicone rubber-based soft lining materials enhance the growth of fungi such as Candida albicans on the presence of saliva 13) . The materials are required to be minimally contaminated from the viewpoint of oral hygiene [14][15][16][17][18][19] . Fluorocarbon polymers have been applied to the dental field because of their excellent characteristics including chemical stability, water and oil repellency, and contamination resistance [20][21][22] .…”

Mechanical properties of experimental silicone soft lining materials

“…Although the experimental silicone elastomers with filler loadings of 6, 8 and 10 phr were found to have greater damping behavior and mechanical properties when compared with the commercial silicone soft lining materials, the SEM images in the previous study showed that the experimental silicone elastomers with filler loadings of 8 and 10 phr had high magnitude of silica agglomerates 11) . From this study, it was found that the experimental silicone elastomer with 6 phr silica loading had an acceptable viscosity to manipulate and had a comparable Shore A hardness to Molloplast-B 11,23) . In addition, lesser amounts of reinforcing fillers can reduce the cost of material production.…”

“…It was proposed that Shore A hardness of soft lining materials should be approximately 40 so that it does not injure the soft tissues and offers comfort to denture wearers. The most widely used heat-polymerized silicone soft lining material (Molloplast-B) was reported to have Shore A hardness 44 23) . In this study, the commercial soft lining materials (ST and RS) have higher Shore A hardness than the proposed value, therefore the experimental silicone elastomer with 6 phr silica loading (Shore A hardness 41.3) showed good potential for use as a soft lining material.…”