chemical type for example a blend of two thermoplastics having different molecular weights examples of specific polymers include polyacrylics polyvinyls polyvinyl alcohols and the like an example of a suitable polymeric material is a durable fade proof acrylic that retains its shape and color for at least four five years another example is made of a very pliable soft custom injected silicone another example is a polymeric material compatible with home office based bleaching techniques such as the material used to make an osap device and materials that can be molded into a ready made semi universal trial version which may be suitable for patients who cannot endure having their impressions taken in addition the trial version is an inexpensive way to test a particular patients 39 tolerance to oral therapy another example is the material used in the device known under the trade designation saga this device consists of a hard acrylic shell laminated to a soft vinyl liner another example is the acrylic material bruxeze u2122 that softens in hot water to provide a combination of comfort strength and retention and which is used in the adjustable pm positioner u2122 an appliance that fits over all maxillary and mandibular teeth another example are the materials used in the device known as somnoguard u00ae ap which consists of an upper and a lower tray each made of two materials the outer tray shells consist of solid clear and transparent medical grade.