A mouthguard (200) comprising: a base portion (210); an inner wall (212) extending from an inner edge (214) of the base portion; and an outer wall (216) extending from an outer edge (218) of the base portion, wherein an internal angle (234a-e) between the base portion and at least a portion of the outer wall is less than 90 degrees and an internal angle (232a-e) between the base portion and at least a portion of the inner wall is less than 90 degrees for gripping teeth of a wearer.