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 two-part liquid silicone composition or a silicone-like TPE material (e.g., preferably SEBS and/or VERSAflex thermoplastic elastomer). 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.