Development of supernumerary premolars in the mandible after orthodontic extraction - A case report

Supernumerary premolars are relatively rare and the etiology of supernumerary tooth formation is complicated and has not yet been well known up to now. The present case documents a case of supernumerary premolars developing in the mandibular premolar region after extractions of the first premolars for orthodontic treatment in an Asian boy. What is special is that they positioned exactly where the extracted premolars used to be. Theoretical considerations for the development of them are postulated from the perspectives of tooth development and engineered tooth regeneration. Residual dental epithelial cells and mesenchyme cells in the alveolar fossas after orthodontic extraction of young permanent premolars may have the potential to proliferate, recombine and interact with each other leading to the development of supernumerary teeth under the inductive microenvironment of alveolar fossas.