PROBLEM TO BE SOLVED: To provide a synthetic resin material supplemented by providing a buccal concave groove formed on a buccal side surface and a lingual concave groove or a step portion formed on the lingual side surface, filling the concave groove or step portion and curing the same. There is provided an orthodontic appliance capable of preventing disengagement of the teeth and a method for correcting the orthodontic appliance. SOLUTION: An orthodontic appliance 1 made of a synthetic resin for orthodontically attaching to a patient's lower dental arch from above so as to orthodontic, and having a curved upper end surface of the lower dental arch. In an orthodontic appliance having a curved lower end surface 2 formed to fit, in addition to the curved lower end surface, the orthodontic appliance has a curved upper end surface 3 and a cheek of the curved upper end surface. The buccal side surface 4 extends downward from the side edge, and the lingual side surface 5 extends downward from the lingual side edge of the curved upper end surface. The lower side of the cheek side edge is located near the upper end of the buccal side surface. A buccal groove 6 is formed which is recessed in the vicinity, and a step 7 is formed by cutting out the vicinity of the lingual side edge in the vicinity of the upper end of the lingual side surface or is recessed in the lower vicinity of the lingual side edge. Form a lingual groove. [Selection diagram] Fig. 4【課題】頬側側面に形成した頬側凹溝と、舌側側面に形成した舌側凹溝又は段部を設け、これらの凹溝や段部に充填し硬化させることで補充した合成樹脂材料の離脱を防止可能にした歯列矯正器具とその修正方法を提供する。【解決手段】患者の下顎歯列弓に上方から着脱自在に装着して歯列を矯正する為の合成樹脂製の歯列矯正器具1であって、下顎歯列弓の湾曲状の上端面に適合するように形成された湾曲状の下端面２を有する歯列矯正器具において、歯列矯正器具は、湾曲状下端面の他に、湾曲状の上端面３と、この湾曲状上端面の頬側端縁から下方へ延びる頬側側面４と、湾曲状上端面の舌側端縁から下方へ延びる舌側側面５とを有し、頬側側面の上端近傍部に頬側端縁の下側近傍部へ凹入した頬側凹溝６が形成され、舌側側面の上端近傍部に舌側端縁の近傍部を切除した段部７又は舌側端縁の下側近傍部へ凹入した舌側凹溝を形成する。【選択図】図４
