Reproducibility of facial soft tissue landmarks on facial images captured on a 3D camera

Objective: Fast and non-invasive systems of the three-dimensional (3D) technology are a recent trend in orthodontics. The reproducibility of facial landmarks is important so that 3D facial measurements are accurate and may be applied clinically. The aim of this study is to evaluate the reproducibility of facial soft tissue landmarks using a non-invasive stereo-photogrammetry 3D camera.Material and methods: Twenty-four soft tissue landmarks on 3D facial images captured using a VECTRA-3D dual module camera system for full face imaging (Canfield Scientific Inc, Fairfield, NJ, USA) were viewed and analysed using Mirror software on 30 adult subjects (15 males and 15 females, in the age range of 20-25 years). The landmarks were identified, recorded and measured twice on each 3D facial image by one examiner after a 2-week interval. Intra-class correlations and paired t-test or Wilcoxon Rank test were performed for each landmark to assess intra-examiner reproducibility.Results: Intra-class correlation coefficients for all 24 landmarks ranged from 0.68 to 0.97, indicating moderate to high reliability and reproducibility of all facial soft tissue landmarks. Paired t-tests and Wilcoxon Rank test also revealed that there were no significant differences in all 24 facial soft tissue landmarks measurements (p = 0.17 - 0.99).Conclusion: The results indicated that the reproducibility of identification of landmarks by one operator on facial images captured using a VECTRA-3D camera was acceptable. This device may be useful in treatment planning and may provide accurate information in making clinical decisions. However, it is suggested that further studies on inter-examiner reproducibility should be undertaken.