An orthodontic appliance 10 comprises at least one of an upper element 10 and/or a lower element 12 which takes the form of an active appliance, preferably a retainer, for adjusting the positions and/or orientations of a patients teeth. The element(s) 10, 12 also include(s) at least one engagement member 18, the engagement member 18 being positioned such that, in use, it is engagable with an occlusal surface of an opposing element, an engagement member associated therewith or an occlusal surface of a tooth. Said opposing element preferably comprises the other of the upper 10 or lower 12 element. In such an arrangement the interaction between the engagement members 18 urges the lower element 12, and thus the mandible, towards a desired position relative to the upper element 10, and thus the maxilla. The application also teaches forming the upper and lower elements, i.e. retainers, of the orthotic either through vacuum forming or through 3D printing using a computer model of a patients teeth.
