A dental tray may include: a facial wall conforming to a facial dental arch of a wearer and having first and second ends； a first clip element coupled to and extending from the first end and configured to apply a first lateral pressure on a wearer's first tooth when it is inserted into the first clip； and a second clip element coupled to and extending from the second end and configured to apply a second lateral pressure on a wearer's second tooth when it is inserted into the second clip； wherein the front wall is formed of a first material having a first hardness, and each clip element is formed of a second material having a second hardness, the second hardness being greater than the first hardness.
