title: Validation of a computer modelled forensic facial reconstruction technique using CT data from live subjects: a pilot study.
abstract: BACKGROUND
  Human forensic facial soft tissue reconstructions are used when post-mortem deterioration makes identification difficult by usual means. The aim is to trigger recognition of the in vivo countenance of the individual by a friend or family member. A further use is in the field of archaeology. There are a number of different methods that can be applied to complete the facial reconstruction, ranging from two dimensional drawings, three dimensional clay models and now, with the advances of three dimensional technology, three dimensional computerised modelling. Studies carried out to assess the accuracy of facial reconstructions have produced variable results over the years. Advances in three dimensional imaging techniques in the field of oral and maxillofacial surgery, particularly cone beam computed tomography (CBCT), now provides an opportunity to utilise the data of live subjects and assess the accuracy of the three dimensional computerised facial reconstruction technique.
  
  
  OBJECTIVE
  The aim of this study was to assess the accuracy of a computer modelled facial reconstruction technique using CBCT data from live subjects.
  
  
  METHODS
  This retrospective pilot study was carried out at the Glasgow Dental Hospital Orthodontic Department and the Centre of Anatomy and Human Identification, Dundee University School of Life Sciences. Ten patients (5 male and 5 female; mean age 23 years) with mild skeletal discrepancies with pre-surgical cone beam CT data (CBCT) were included in this study. The actual and forensic reconstruction soft tissues were analysed using 3D software to look at differences between landmarks, linear and angular measurements and surface meshes.
  
  
  CONCLUSIONS
  There were no statistical differences for 18 out of the 23 linear and 7 out of 8 angular measurements between the reconstruction and the target (p<0.05). The use of Procrustes superimposition has highlighted potential problems with soft tissue depth and anatomical landmarks' position. Surface mesh analysis showed that this virtual sculpture technique can be objectively assessed using the distance between the meshes. This study found that the percentage of faces with less than ±2.5mm error ranged from 56% to 90%. This may be improved if Procrustes superimposition could be applied to all the mesh points rather than specific landmarks.
authors: Orthodontics, Medical School, MVLS College, University of Glasgow, United Kingdom.
authors: Laura J
authors: LJ
authors: Short
authors: Paediatric Dentistry and Orthodontics, Faculty of Dentistry, University of Hong Kong, Hong Kong. Electronic address: bkhambay@hku.hk.
authors: Balvinder
authors: B
authors: Khambay
authors: Oral & Maxillofacial Surgery, Medical School, MVLS College, University of Glasgow, United Kingdom.
authors: Ashraf
authors: A
authors: Ayoub
authors: Centre of Anatomy and Human Identification, University of Dundee, United Kingdom.
authors: Caroline
authors: C
authors: Erolin
authors: Centre of Anatomy and Human Identification, University of Dundee, United Kingdom.
authors: Chris
authors: C
authors: Rynn
authors: Centre of Anatomy and Human Identification, University of Dundee, United Kingdom.
authors: Caroline
authors: C
authors: Wilkinson
mesh_terms: D000293:Adolescent; D000328:Adult; D003198:Computer Simulation; D054893:Cone-Beam Computed Tomography; D005145:Face / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D005260:Female; D018732:Forensic Anthropology; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D010865:Pilot Projects; D012189:Retrospective Studies; D055815:Young Adult
keywords: 3D computerised modelling method; Accuracy; Cone-beam CT; Forensic facial reconstruction; Forensic science; Live subjects