A supernumerary tooth that closely resembles the adjacent tooth is termed supplementary. A case to which a mandibular right first molar was replaced by a supplementary third premolar is presented. Recurrent caries under a crown on the first molar necessitated removal of the crown,so that only the roots remained. The roots were extracted, and the supernumerary tooth was moved orthodontically into a favorable arch position. A 6-month followup revealed no changes in the position of the tooth.