Comparative study of water sorption, solubility, and tensile bond strength of two soft lining materials

Abstract

Statement of problem. Two soft denture lining materials with distinct chemical compositions were evaluated to determine whether these compositional variations manifest themselves in property differences. Purpose. This study evaluated and compared the water sorption, solubility, and tensile bond strength of a recently introduced silicone-based soft liner (Luci-sof) and a plasticized acrylic resin soft liner (Permasoft) using 2 processing techniques, laboratory-processed and autopolymerized at chairside, for the latter. Material and methods. For water sorption and solubility testing, 24 disks (45 mm in diameter and 1 mm in thickness) were prepared for each group, stored in distilled water at 37°C, and tested after 1, 4, and 6 weeks. The disks used for the first week were again tested after 4 and 6 weeks of continuous storage. Their weight was recorded and sorption and solubility were calculated using 2 methods. Two PMMA cylinders (25 mm in diameter, 25 mm in length), joined together by the soft liner, were used to determine the bond strength in tension at a loading rate of 2 mm/min after 48 hours and 12 weeks aging in distilled water. Results. Permasoft had higher solubility (1.50% ± 0.20% laboratory-processed and 1.42% ± 0.16% autopolymerized at chairside) and sorption (2.45% ± 0.36% laboratory-processed and 1.76% ± 0.08% autopolymerized at chairside) than Luci-sof (0.17% ± 0.09% solubility and 0.41% ± 0.17% sorption) after 6 weeks of aging. For tensile bond strength, there was no significant difference between each respective control and the 12-week bond strength for each material. However, Luci-sof (1.16 ± 0.27 MPa) had a significantly higher tensile bond strength than Permasoft (0.50 ± 0.18 MPa laboratory-processed and 0.44 ± 0.09 MPa autopolymerized at chairside). Conclusion. On the basis of lower water sorption and solubility and higher tensile bond strength, Luci-sof may provide better clinical success. (J Prosthet Dent 2000;83:356-61.)