title: Registration accuracy in the integration of laser-scanned dental images into maxillofacial cone-beam computed tomography images.
abstract: BACKGROUND
  A precision 3-dimensional (3D) head model can be fabricated by integrating a digital dental model into a maxillofacial 3D image. The integration requires accurate registration of 2 image modalities. The aims of this study were to determine the registration errors for implementation of laser-scanned dental images into cone-beam computed tomography (CBCT) scan data and to examine the influence of the registration area on the accuracy of registration.
  
  
  METHODS
  The CBCT scans were obtained from 30 adults, and the maxillofacial 3D images were reconstructed. Maxillary and mandibular dental casts were taken from the same subjects and scanned with a 3D laser scanner. The laser-scanned maxillary and mandibular dentition images were incorporated into the CBCT images of each arch in 3 ways according to the registration area: only the buccal surfaces, only the lingual surfaces, and both the buccal and lingual surfaces. Surface-based registration was performed by using an iterative closest point algorithm, and its errors were evaluated by measuring the 3D Euclidean distances between the surface points on the 2 images.
  
  
  RESULTS
  The registration errors ranged from 0.27 to 0.33 mm. The mandibular arch did not show significant differences in registration errors according to the selected area for the registration. The maxillary arch, however, showed significant differences according to the registration area. When the lingual surfaces only were used for registration, the errors were greater than for the other 2 methods. The errors were least when both the buccal and lingual surfaces were used for registration.
  
  
  CONCLUSIONS
  The results of this study indicate that accuracy in the integration of laser-scanned dental images into the maxillofacial CBCT images increases when a broad area is used for registration.
authors.affiliation: School of Dentistry, Chonnam National University, Gwangju, Korea.
authors.forename: Hoon
authors.initials: H
authors.lastname: Noh
authors.forename: Wael
authors.initials: W
authors.lastname: Nabha
authors.forename: Jin-Hyoung
authors.initials: JH
authors.lastname: Cho
authors.forename: Hyeon-Shik
authors.initials: HS
authors.lastname: Hwang
mesh_terms: D000328:Adult; D000465:Algorithms; D003198:Computer Simulation; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003724:Dental Arch / Q000033:anatomy & histology; D005147:Facial Bones / Q000033:anatomy & histology*; D005260:Female; D005881:Gingiva / Q000033:anatomy & histology; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000592:standards*; D007568:Jaw / Q000033:anatomy & histology*; D007834:Lasers; D008297:Male; D008334:Mandible / Q000033:anatomy & histology; D008437:Maxilla / Q000033:anatomy & histology; D003765:Models, Dental; D012984:Software; D014070:Tooth / Q000033:anatomy & histology*; D055815:Young Adult