An orthodontic arch wire stop (20, 170, 200, 300, 320, 340, 400) for attaching to an arch wire (50, 202), the arch wire stop (20, 170, 200, 300, 320, 340, 400) comprising: a body (26, 174, 208, 306, 326, 343, 402); the body (26, 174, 208, 306, 326, 343, 402) having first and second, spaced apart arm portions (40, 42, 178, 180, 220, 222) connected to each other; the first arm portion (40, 178, 220) including a first jaw portion (44, 226, 350) having a first inner, arch wire-gripping surface (78, 268, 346); the second arm portion (42, 180, 222) including a second jaw portion (46, 230, 352) having a second inner, arch wire-gripping surface (80, 270, 348); the first and second inner gripping surfaces (78, 80, 268, 270, 346, 348) being disposed opposite one another in spaced relation, the space between the first and second inner gripping surfaces (78, 80, 268, 270, 346, 348) defining a station (48, 232, 342) for receiving the arch wire therein, at least a portion of the arch wire receiving station (48, 232, 342) being sized smaller than the arch wire (50, 202); the body (26, 174, 208, 306, 326, 343, 402) further including an entranceway (70, 252) defined between the first and second arm portions (40, 42, 178, 180, 220, 222), the entranceway (70, 252) providing access to the arch wire receiving station (48, 232, 342); characterised in that the body is made of a shape memory material having a shape reset temperature range within which the shape memory material is capable of deforming significantly from a memorized shape of the shape memory material and a shape recovery temperature range within which the shape memory material is capable of recovering the memorized shape; the first and second arm portions (40, 42, 178, 180, 220, 222) being movable outwardly away from each other when the temperature of the shape memory material of the body (26, 174, 208, 306, 326, 343, 402) lies within the shape reset temperature range and remaining spread apart as long as the temperature of the shape memory material lies below the shape recovery temperature range, so as to allow admission of the arch wire (50, 202) through the entranceway (70, 252) into the arch wire receiving station (48, 232, 342); the first and second inner gripping surfaces (78, 80, 268, 270, 346, 348) engaging the arch wire (50, 202) and applying opposing gripping forces against the arch wire (50, 202) so as to substantially prevent displacement of the arch wire stop (20, 170, 200, 300, 320, 340, 400) relative to the arch wire (50, 202) in a mesial and a distal direction, when the arch wire (50, 202) is seated within the arch wire receiving station (48, 232, 342) and the temperature of the shape memory material of the body (26, 174, 208, 306, 326, 343, 402) lies within the shape recovery temperature range. a body (26, 174, 208, 306, 326, 343, 402); the body (26, 174, 208, 306, 326, 343, 402) having first and second, spaced apart arm portions (40, 42, 178, 180, 220, 222) connected to each other; the first arm portion (40, 178, 220) including a first jaw portion (44, 226, 350) having a first inner, arch wire-gripping surface (78, 268, 346); the second arm portion (42, 180, 222) including a second jaw portion (46, 230, 352) having a second inner, arch wire-gripping surface (80, 270, 348); the first and second inner gripping surfaces (78, 80, 268, 270, 346, 348) being disposed opposite one another in spaced relation, the space between the first and second inner gripping surfaces (78, 80, 268, 270, 346, 348) defining a station (48, 232, 342) for receiving the arch wire therein, at least a portion of the arch wire receiving station (48, 232, 342) being sized smaller than the arch wire (50, 202); the body (26, 174, 208, 306, 326, 343, 402) further including an entranceway (70, 252) defined between the first and second arm portions (40, 42, 178, 180, 220, 222), the entranceway (70, 252) providing access to the arch wire receiving station (48, 232, 342); characterised in that the body is made of a shape memory material having a shape reset temperature range within which the shape memory material is capable of deforming significantly from a memorized shape of the shape memory material and a shape recovery temperature range within which the shape memory material is capable of recovering the memorized shape; the first and second arm portions (40, 42, 178, 180, 220, 222) being movable outwardly away from each other when the temperature of the shape memory material of the body (26, 174, 208, 306, 326, 343, 402) lies within the shape reset temperature range and remaining spread apart as long as the temperature of the shape memory material lies below the shape recovery temperature range, so as to allow admission of the arch wire (50, 202) through the entranceway (70, 252) into the arch wire receiving station (48, 232, 342); the first and second inner gripping surfaces (78, 80, 268, 270, 346, 348) engaging the arch wire (50, 202) and applying opposing gripping forces against the arch wire (50, 202) so as to substantially prevent displacement of the arch wire stop (20, 170, 200, 300, 320, 340, 400) relative to the arch wire (50, 202) in a mesial and a distal direction, when the arch wire (50, 202) is seated within the arch wire receiving station (48, 232, 342) and the temperature of the shape memory material of the body (26, 174, 208, 306, 326, 343, 402) lies within the shape recovery temperature range.