title: Morphological changes in the crown of mandibular molars with an additional distolingual root.
abstract: OBJECTIVE
  The mandibular molars typically have two roots placed mesiodistally, but they occasionally have an additional distolingual (DL) root. This study was to determine the morphological characteristics of the crown of such mandibular molars.
  
  
  METHODS
  Radiographic records and study models were collected from a Korean population (n=86 patients). Each molar was assigned to either the experimental group (i.e. with a DL root) or the control group (i.e. without a DL root; n=41 patients) based on the radiographic findings. The intercuspal distances of the first permanent molars (total, n=100; control/experimental, n=50/50) and primary second molars (46, 23/23), and the largest buccolingual/mesiodistal widths of those molars and primary first molars (42, 21/21) were measured for molars with and without a DL root. In addition, the correlation between the existence of a sixth cusp and a DL root was examined.
  
  
  RESULTS
  The crowns of first permanent and primary second molars with DL roots had significantly larger intercuspal distances between the distobuccal-distolingual cusp tips and a larger distal-area buccolingual width than those without the DL root (t-test; p<0.05). There was no significant correlation between the existence of a sixth cusp and the presence of a DL root.
  
  
  CONCLUSIONS
  The existence of a DL root was associated with larger buccolingual dimensions, especially in the distal area.
authors.affiliation: Department of Pediatric Dentistry, College of Dentistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752, Republic of Korea.
authors.forename: Ki Rim
authors.initials: KR
authors.lastname: Kim
authors.forename: Je Seon
authors.initials: JS
authors.lastname: Song
authors.forename: Seong-Oh
authors.initials: SO
authors.lastname: Kim
authors.forename: Seung Hye
authors.initials: SH
authors.lastname: Kim
authors.forename: Wonse
authors.initials: W
authors.lastname: Park
authors.forename: Heung-Kyu
authors.initials: HK
authors.lastname: Son
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging; D008963:Molar / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000473:pathology; D009811:Odontometry / Q000379:methods; D016300:Radiography, Bitewing; D011862:Radiography, Panoramic; D056910:Republic of Korea; D014057:Tomography, X-Ray Computed; D019228:Tooth Crown / Q000002:abnormalities / Q000473:pathology*; D014092:Tooth Root / Q000002:abnormalities* / Q000000981:diagnostic imaging; D014094:Tooth, Deciduous / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000473:pathology; D055815:Young Adult