Endodontic infection or physical trauma of a developing tooth might lead to unusual situation for root development.Two cases are presented. Both cases involved immature mandibular second premolars with infected pulps. In the first case, the tooth was treated by apexification, whereas revascularization procedures were performed in the second case. Interestingly, a separated root tip was observed with the main root at the initial presentation of case 2.At recall after apexification, a separate root tip was observed apically to the main root end, and root development continued in case 1. In the second case, the separate root displayed continuing root formation, but the main root did not gain root thickness or length.These cases revealed that Hertwig's epithelial root sheath and stem cells from the apical papilla can be separated from the main tooth structure by an external force or iatrogenic factors and thereafter produce a separate root tip.