title: Lingual concavities in the mandible: a morphological study using cross-sectional analysis determined by CBCT.
abstract: BACKGROUND
  Lingual undercuts are common in the edentulous mandible and pose the risk of perforating the lingual cortical bone during insertion of dental implants, which may lead to hemorrhage or infections of the parapharyngeal space. The aim of our study was to determine the occurrence and extent of lingual undercuts in the molar and premolar/canine region of the mandible.
  
  
  METHODS
  We analyzed 716 cross-sections of the edentulous molar region and 215 cross-sections of the edentulous first premolar/canine region. Mandibular morphology was classified into a U-configuration (undercut), P-configuration (parallel), and C-configuration (convex), depending on the shape of the alveolar ridge. Depth of the lingual concavity, concavity angle, and further parameters were measured to describe the mandibular morphology.
  
  
  RESULTS
  Lingual undercuts had a prevalence of 68% in the molar region. The prevalence was significantly higher in the second molar region (90%) than in the first molar region (56%). A deep position of the inferior alveolar nerve close to the basal cortical bone was significantly associated with the presence of lingual undercuts.
  
  
  CONCLUSIONS
  Lingual undercuts are a frequent in the edentulous mandible. Cross-sectional analysis of three-dimensional radiographs provides the opportunity to determine a lingual undercut and to prevent complications of perforating the lingual cortical bone.
authors.affiliation: Department of Oral and Maxillofacial Plastic Surgery and Interdisciplinary Department of Oral Surgery and Implantology (Head: Professor. J.E. Zöller, MD, DMD), University of Cologne, Kerpenerstr. 62, 50931 Cologne, Germany.
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Nickenig
authors.affiliation: Department of Prosthodontics, University Hospital Erlangen, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Wichmann
authors.affiliation: Department of Prosthodontics, University Hospital Erlangen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Eitner
authors.affiliation: Department of Oral and Maxillofacial Plastic Surgery and Interdisciplinary Department of Oral Surgery and Implantology (Head: Professor. J.E. Zöller, MD, DMD), University of Cologne, Kerpenerstr. 62, 50931 Cologne, Germany.
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Zöller
authors.affiliation: Department of Oral and Maxillofacial Plastic Surgery and Interdisciplinary Department of Oral Surgery and Implantology (Head: Professor. J.E. Zöller, MD, DMD), University of Cologne, Kerpenerstr. 62, 50931 Cologne, Germany. Electronic address: mattheskreppel@yahoo.de.
authors.forename: Matthias
authors.initials: M
authors.lastname: Kreppel
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000539:Alveolar Process / Q000000981:diagnostic imaging; D019412:Anatomy, Cross-Sectional / Q000379:methods; D001641:Bicuspid; D002508:Cephalometry / Q000379:methods; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D000071538:Cortical Bone / Q000000981:diagnostic imaging; D003724:Dental Arch / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007576:Jaw, Edentulous, Partially / Q000000981:diagnostic imaging*; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging*; D008340:Mandibular Nerve / Q000000981:diagnostic imaging; D008875:Middle Aged; D008963:Molar; D012189:Retrospective Studies; D055815:Young Adult
keywords: CBCT; Lingual undercuts; Mandible; Molar region; Morphology