Resilient liners for dentures

Abstract

The maximum Shore A hardness of ten resilient relining materials was determined after curing and at intervals after storage in distilled water at 25° C. Products plasticized with alcohol had a rapid increase in hardness, while other acrylic resin polymers or copolymers plasticized with oily liquids showed less rapid changes in hardness when stored in water. The resilient liners fell into two groups, one having maximum Shore A hardness values between 50 and 65 and the other having values from 84 to 89. The flow of liner materials under a load was indicated by the difference between the maximum and stable Shore A hardness values. The silicone rubber liners had no flow, while most of the acrylic resin liner materials had a moderate amount of flow. The weight change percentages demonstrated that none of the materials were stable when stored in water at room temperature. The Flexene liner lost weight continuously with storage time after 4 days in water. Soft Line and Soft Oryl were the most stable of the plastic materials; the remainder of the plastic liners and the silicone rubber liners had greater weight increases. On the basis of the experimental data, a limited evaluation of the resilient liners was presented. Additional studies of physical properties and clinical evaluations of their significance will eventually indicate the materials most desirable to produce specific results.