The invention relates to a customized jig for an orthodontic appliance, to an assembly formed by the jig, a base and a bracket, and to the associated design methods. The customized jig is used to install a bracket-bearing base on a tooth, said base forming part of an orthodontic appliance. The invention is characterized in that: the jig is a cap that covers the tooth, covering the free edge thereof and at least portions of the front and rear surfaces of same; and the shape of the jig is such that it matches that of the base in at least one portion of at least one of the edges thereof. The invention also relates to an assembly formed by a customized base bearing a bracket and a customized jig of the type mentioned above, and to methods for designing one such jig.