title: 3D assessment of mandibular growth based on image registration: a feasibility study in a rabbit model.
abstract: BACKGROUND
  Our knowledge of mandibular growth mostly derives from cephalometric radiography, which has inherent limitations due to the two-dimensional (2D) nature of measurement.
  
  
  OBJECTIVE
  To assess 3D morphological changes occurring during growth in a rabbit mandible. Methods. Serial cone-beam computerised tomographic (CBCT) images were made of two New Zealand white rabbits, at baseline and eight weeks after surgical implantation of 1 mm diameter metallic spheres as fiducial markers. A third animal acted as an unoperated (no implant) control. CBCT images were segmented and registered in 3D (Implant Superimposition and Procrustes Method), and the remodelling pattern described used color maps. Registration accuracy was quantified by the maximal of the mean minimum distances and by the Hausdorff distance.
  
  
  RESULTS
  The mean error for image registration was 0.37 mm and never exceeded 1 mm. The implant-based superimposition showed most remodelling occurred at the mandibular ramus, with bone apposition posteriorly and vertical growth at the condyle.
  
  
  CONCLUSIONS
  We propose a method to quantitatively describe bone remodelling in three dimensions, based on the use of bone implants as fiducial markers and CBCT as imaging modality. The method is feasible and represents a promising approach for experimental studies by comparing baseline growth patterns and testing the effects of growth-modification treatments.
authors: Department of Oral Sciences, University of Otago, P.O. Box 647, Dunedin 9054, New Zealand.
authors: I
authors: I
authors: Kim
authors: Robotic System Laboratory (LSRO), Swiss Federal Institute of Technology in Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors: M E
authors: ME
authors: Oliveira
authors: Department of Oral Sciences, University of Otago, P.O. Box 647, Dunedin 9054, New Zealand.
authors: W J
authors: WJ
authors: Duncan
authors: Department of Oral Sciences, University of Naples Federico II, 80131 Naples, Italy.
authors: I
authors: I
authors: Cioffi
authors: Department of Oral Sciences, University of Otago, P.O. Box 647, Dunedin 9054, New Zealand.
authors: M
authors: M
authors: Farella
mesh_terms: D000818:Animals; D002508:Cephalometry; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008334:Mandible / Q000000981:diagnostic imaging* / Q000254:growth & development; D011817:Rabbits