title: Methodology for Morphometric Analysis of Modern Human Contralateral Premolars.
abstract: OBJECTIVE
  This study aimed at developing a standard methodology for morphometric analysis and comparison of contralateral human premolar pulp space using microcomputed tomography (micro-CT) and semiautomated software. The primary objective was to establish a method to compare the complex and minute morphological internal volumes of contralateral premolar pulp spaces and determine their degree of similarity. The secondary aim was to introduce new methodology for selecting contralateral premolars for the study of biomaterials and techniques.
  
  
  METHODS
  Forty-one intact human premolar pairs (n = 82) extracted from 28 patients were scanned with micro-CT. Quantitative comparative evaluation was performed through geometric morphometric deviation analysis of the pulp spaces after mirroring, automatic alignment, and coregistration with semiautomated software. Geometric parameters compared included volume, surface, and surface over volume. Shape deviation analysis of transformed mean distances and root mean square errors was conducted.
  
  
  RESULTS
  The geometric parameters of the contralateral premolar pulp spaces had significantly higher similarity coefficients than random pairs (P < 0.001). The shape deviation analysis and transformed mean distances had significantly lower values for contralaterals compared with random pairs (P < 0.001). The contralateral geometries had a statistically significant narrower distribution in deviation when compared with random pairs (P < 0.001).
  
  
  CONCLUSIONS
  We present a methodology that sets a new standard for internal validation of the teeth to be used in ex vivo testing of endodontic materials and techniques. It also shows that the resolution of the CT scan is crucial and that studies using cone beam CT cannot be used for such studies.
authors.affiliation: From the *Faculty of Dentistry, Department of Biomaterials, Institute of Clinical Dentistry, University of Oslo; and †Cardiac Modeling, Simula Research Laboratory, Oslo, Norway.
authors.forename: Gaute Floer
authors.initials: GF
authors.lastname: Johnsen
authors.forename: Joakim
authors.initials: J
authors.lastname: Sundnes
authors.forename: Jonas
authors.initials: J
authors.lastname: Wengenroth
authors.forename: Håvard Jostein
authors.initials: HJ
authors.lastname: Haugen
mesh_terms: D000293:Adolescent; D000328:Adult; D001641:Bicuspid / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D002648:Child; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D066298:In Vitro Techniques; D008297:Male; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011861:Radiography, Dental / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult