Non-customized dental treatment trays used to provide a desired treatment are formed from elastomeric silicone or silicone-like material. They may be molded from a silicone composition or a non-silicone thermoplastic elastomer (TPE), such as SEBS and/or VERSAflex. The silicone composition can be a thermoset material formed by curing a two-part composition. The dental treatment trays possess high adaptability, flexibility, softness, and elastic elongation while also exhibiting resiliency in order to readily conform to the ridges, depressions and contours of a person's teeth during use. The trays possess a greater ability to adhere to a person's teeth compared to non-elastomeric thermoplastic materials. Due to their high adaptability and conformability, the non-customized dental trays behave like a semi-custom dental tray when placed over conformed to a person's teeth, particularly when used in combination with a sticky, viscous treatment composition.