title: Continued development of the root separated from the main root.
abstract: BACKGROUND
  Endodontic infection or physical trauma of a developing tooth might lead to unusual situation for root development.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Conservative Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Il-Young
authors.initials: IY
authors.lastname: Jung
authors.forename: Eui-Seong
authors.initials: ES
authors.lastname: Kim
authors.forename: Chan-Young
authors.initials: CY
authors.lastname: Lee
authors.forename: Seung Jong
authors.initials: SJ
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D056624:Apexification / Q000379:methods; D001641:Bicuspid / Q000473:pathology; D002126:Calcium Hydroxide / Q000627:therapeutic use; D002648:Child; D003751:Dental Fistula / Q000628:therapy; D003790:Dental Pulp Necrosis / Q000628:therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008768:Methylmethacrylates / Q000627:therapeutic use; D009805:Odontogenesis / Q000502:physiology*; D010485:Periapical Periodontitis / Q000628:therapy; D012387:Root Canal Filling Materials / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000379:methods; D012828:Silicones / Q000627:therapeutic use; D019227:Tooth Apex / Q000254:growth & development*; D014092:Tooth Root / Q000254:growth & development*; D015035:Zinc Oxide-Eugenol Cement / Q000627:therapeutic use
chemical_list: D008768:Methylmethacrylates; D012387:Root Canal Filling Materials; D012828:Silicones; D015035:Zinc Oxide-Eugenol Cement; C029584:calcium hydroxide, iodoform, silicone oil drug combination; C031667:IRM cement; D002126:Calcium Hydroxide