Supernumerary teeth develop in addition to the normal dentition and are a therapeutic challenge for pedodontists, orthodontists and oral surgeons alike. Therefore, interdisciplinary treatment concepts are needed for the benefit of the patient. In the present, two-parted literature review on supernumerary teeth, current classification, associated complications, diagnostic steps and different therapeutic approches are presented and discussed. Supernumerary teeth are diagnosed in the primary and permanent dentition. Supernumerary incisors, canines, premolars, and molars, as well as distomolars and mesiodentes can be seen according to the location of the supernumerary teeth. Furthermore, based on the morphology of the supernumeraries four different types can be differentiated: conical, tuberculate, supplemental, and odontoma. Supernumerary teeth often remain asymptomatic, and are only diagnosed incidentally during a routine dental visit on radiographs (often intraoral). Nevertheless, various complications have been reported in the literature for supernumerary teeth such as disturbed eruption, malpositioning/rotation, root resorption of neighbouring teeth, and development of dentigerous cysts in impacted supernumeraries. Root resorption of neighbouring teeth can be radiographically diagnosed in up to 22.8% of the cases.