Original article
Facial soft-tissue analysis of Korean adults with normal occlusion using a 3-dimensional laser scanner

https://doi.org/10.1016/j.ajodo.2005.08.038Get rights and content

Introduction: Developments in computer technology have made the 3-dimensional (3D) diagnosis of facial soft tissues possible, opening the window for 3D soft-tissue evaluation in orthodontic treatment planning and posttreatment results. Methods: Korean adults (30 men, 30 women) with normal occlusion were scanned with a 3D laser scanner, and 3D facial images were made with the Rapidform 2004 program (Inus Technology, Seoul, Korea). Reference planes in the facial soft tissues of the 3D image were established, and a 3D coordinate system (X-axis, left/right; Y-axis, superior/inferior; Z-axis, anterior/posterior) was established; 29 measurement points were assigned on the 3D image, and 39 linear measurements, 8 angular measurements, and 29 linear distance ratios were obtained. Results: Significant differences between the sexes were found in nasofrontal angle (men, 142°; women, 147°) and transverse nasal prominence (men, 112°; women, 116°) (P <.05). Transverse upper lip prominence was 107° in the men and 106° in the women, and transverse mandibular prominence was 76° in both sexes. The distance between lower lip vermilion border (Li) and Me′ was 0.4 times mandibular body length (Me′ - Go′), and mouth height was also 0.4 times the mouth width. The linear distance ratios from the coronal reference plane to fronto-temporal point, zygomatic point, pronasale, upper lip point, labrale inferior, and soft-tissue menton were −1, −1, 1, 0.5, 0.5, and −0.6, respectively. Conclusions: These data could be guidelines for the 3D evaluation of the facial image, because the 3D facial model constructed by the averaged coordinate values could be a template for orthodontic diagnosis and treatment planning.

Section snippets

Material and methods

Thirty men and 30 women, aged 21 to 27 years, were screened with lateral cephalometric measurements and clinical examinations at Yonsei dental college. All subjects had Class I skeletal and bilateral Angle Class I first molar and canine relationships. They had no facial asymmetry, protrusion, craniofacial disorders, or previous or current orthodontic treatment. The subjects were compared with the Korean norms from the Korean Association of Orthodontics and the Korean normal facial form reported

Results

The 3D coordinate values of the landmarks (X, Y, Z) were acquired by using the coordinate system, with N′ as the zero point. The X-coordinate values of the Tra, En, Ex, ULP, Ch, and Go′ were farther from the sagittal reference plane in the men than in the women (P <.05). There were statistically significant differences in the Y-coordinate values of all measurements between the sexes except Tri and FT (P <.05). All landmarks except G and FT, located in the forehead area, were farther from the

Discussion

Many 3D capturing instruments enable orthodontists to acquire various 3D images of the facial soft tissues. In this study, we used a 3D laser scanner (Vivid 900), which is easy to use and less time-consuming than CT, and has self-calibration and auto-image distortion correction ability.3, 4, 5, 6 The subject’s head posture was fixed to NHP. Ferrario et al17 reported that 3D measurement values were not sensitive to head posture. However, a consistent posture was reported to be quite important,

Conclusions

The facial soft tissues of Korean adults with normal occlusion were analyzed by using a 3D laser scanner, and an average 3D facial soft-tissue model of Korean adults with normal occlusion was obtained. The averaged values of the 3D angles and ratios are applicable for making an orthodontic diagnosis and comparing the facial soft tissues before and after treatment. When we compared the values between sexes, the size difference was large, but the shape difference was small.

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    This study has been supported by the Craniofacial Deformity Center of Yonsei University.

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