title: Clinical, imaging and genetic analysis of double bilateral radix entomolaris.
abstract: BACKGROUND
  Anatomy describes that first mandibular molars have two roots: 1 mesial, with 2 root canals, and 1 distal, with 1 root canal. The presence of three roots in these teeth is uncommon. Root anatomical variations have an impact, especially in endodontic, where the highest rates of nonsurgical treatment failures are due to the inability to identify and access roots and/or accessory canals. The aim of this research is to report a case of double three-rooted mandibular first molar through clinical, imaging and genetic analysis.
  
  
  METHODS
  Using a panoramic radiography, the presence of three roots in teeth 36 and 46 was diagnosed in a female patient. Additionally, it was indicated a cone beam computed tomography. Moreover, leukocyte genomic DNA was obtained from a blood sample of the patient to determine her ethnicity through analysis of mitochondrial DNA haplogroups using polymerase chain reaction-length restriction fragment polymorphism (PCR-RFLP).
  
  
  RESULTS
  Both molars had three roots, 1 mesial (M), 1 distolingual (DL), also known as radix entomolaris (RE), and a distovestibular (DV). For both teeth, M root had 2 canals, and DV and DL roots presented just 1 canal. Mitochondrial DNA analysis determined presence of haplogroup C, corresponding to Amerindian ethnicity.
  
  
  CONCLUSIONS
  The presence of RE is uncommon. This case report contributes to describe this rare anatomical variation. To our knowledge, this is the first molecular-genetic study applied to dental anatomy and gives basis to develop future research in the area.
authors: C A
authors: CA
authors: Rodríguez-Niklitschek
authors: Departamento de Odontología Integral Adultos, Facultad de Odontología, Universidad de La Frontera, Temuco, Chile. gonzalo.oporto@ufrontera.cl.
authors: G H
authors: GH
authors: Oporto
authors: I
authors: I
authors: Garay
authors: L A
authors: LA
authors: Salazar