Article

A proposal for soft tissue landmarks for craniofacial analysis using 3-dimensional laser scan imaging.

Department of Orthodontics, College of Dentistry, Yonsei University, Seoul, South Korea.
World journal of orthodontics 02/2006; 7(1):7-14. pp.7-14
Source: PubMed

ABSTRACT To evaluate the accuracy of the 3-dimensional laser scanner and to propose reproducible soft tissue landmarks in the 3-dimensional facial images.
A mannequin head was preliminarily scanned 6 times to calculate scanning errors. Mean errors in the linear measurements from the scanned images and the actual mannequin head were assessed and the magnification rate of the scanned images was calculated. The soft tissue landmarks were defined in the mannequin head and the patients with normal, Class II, and Class III malocclusions. The reliability and the reproducibility were investigated by comparing the x-, y-, and z-coordinate of each landmark gained from repeated landmarking procedure.
Scanning errors were 0.16 mm in the x axis, 0.15 mm in the y axis, and 0.15 mm in the z axis. The mean error of scanned image was 0.37 mm and the magnification rate was 0.66%. In the four 3-dimensional images, the standard deviations in the localization of all landmarks were less than 1.0 mm in the x, y, and z axes.
The laser scanner is a useful tool for understanding the 3-dimensional facial structure, and the soft tissue landmarks proposed in this study were considered highly reproducible and reliable.

0 0
 · 
0 Bookmarks
 · 
22 Views
  • Source
    Article: Reproducibility of facial soft tissue landmarks on 3D laser-scanned facial images.
    A M Toma, A Zhurov, R Playle, E Ong, S Richmond
    [show abstract] [hide abstract]
    ABSTRACT: The three-dimensional (3D) measuring technology is useful to inspect facial shape in three planes of space (X, Y, and Z). Recent work has been directed to analyse craniofacial morphology using facial soft tissue landmarks to identify facial differences among population. The reproducibility of facial landmarks is almost necessary to ensure accurate 3D facial measurements. The aim of this study is to assess the reproducibility of facial soft tissue landmarks using laser-scan 3D imaging technology. Facial landmarks were assessed for 30 15(1/2)-year-old British-Caucasian children (15 males and 15 females). The sample was recruited from the Avon Longitudinal Study of Parents and Children (ALSPAC). The 3D facial images were acquired for each subject using two high-resolution Konica/Minolta laser scanners. Twenty-one facial landmarks (63 X, Y, and Z coordinates) were identified and recorded on each 3D facial image by two examiners. The reproducibility of landmarks identification at 2-week interval was assessed for one of the examiners (intra-examiner). In addition, the reproducibility of landmarks was assessed between the two examiners (inter-examiner). Using Bland-Altman plots, both intra- and inter-examiner assessments had evaluated landmarks reproducibility in three dimensions for the sample divided by gender. The reproducibility of the 3D-coordinates for each landmark was considered under three categories (< 0.5 mm, < 1 mm, and >1 mm) for both intra- and inter-examiner reproducibility assessments. The distribution of coordinates at the three levels of reproducibility show the following percentages: intra-examiner: < 0.5 mm (38%), < 1 mm (51%), >1 mm (11%); inter-examiner: < 0.5 mm (35%), < 1 mm (48%), >1 mm (17%). Generally, 10 landmarks were reproducible to less than 1 mm for both intra- and inter-examiner reproducibility assessments. The Labiale Superius was the most reproducible and Palebrale Superius was the least reproducible landmark. Some landmarks showed greater reliability in certain planes of space; the Glabella was more reliable in the Z than the Y axis. Gender differences were found; Subnasale was more reproducible in the Y-axis in males compared with females. The reproducibility of facial landmarks should be considered in the three planes of space. The majority of X-Y-Z coordinates taken to the 21 facial landmarks were reproducible to < 1 mm which is clinically acceptable. The accuracy of landmarks identification ranged from 0.39 to 1.49 mm. The reliability in identification depends on the clarity and definition of each landmark as well as gender characteristics. The different landmarks reproducibility should be considered when evaluating changes related to growth and healthcare interventions.
    Orthodontics and Craniofacial Research 02/2009; 12(1):33-42. · 1.65 Impact Factor
  • Source
    Chapter: Alternatives to Radiation Investigations in Orthodontics
    Shazia Naser-Ud-Din
    02/2012; , ISBN: 978-953-51-0196-3
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

3-dimensional facial images
 
3-dimensional facial structure
 
actual mannequin head
 
calculate scanning errors
 
Class III malocclusions
 
four 3-dimensional images
 
landmarking procedure
 
linear measurements
 
mannequin head
 
mean error
 
Mean errors
 
reproducibility
 
reproducible soft tissue landmarks
 
Scanning errors
 
soft tissue landmarks
 
useful tool
 
x axis
 
y axis
 
z axes
 
z axis
 

Hyoung-Seon Baik