Lip and perioral soft tissue changes after bracket bonding using 3-D laser scanner / 대한치과교정학회지

OBJECTIVE: The aim of this study was to evaluate the lip and perioral soft tissue changes after bracket bonding. METHODS: The soft tissue changes in 45 adult patients (age greater than 18 years and less than 29 years) without severe skeletal discrepancy were evaluated using three-dimensional images acquired with a laser scanner before and after bracket bonding was performed using 4 types of labial orthodontic brackets. RESULTS: Among the statistically significant changes in distance observed for the landmarks, the biggest change was observed in forward movement. The landmarks on the lateral sides also showed significant changes. While the landmarks on the upper lip showed significant upward movement, those on the lower lip showed significant downward movement. However, the changes were smaller for the landmarks on the upper lip (average, 0.87 mm) than for the landmarks on the lower lip (average, 1.21 mm). The type of bracket used did not significantly affect the soft tissue changes. CONCLUSIONS: These findings will help predict soft tissue changes after bracket bonding for orthodontic treatment.

Influence of the angles and number of scans on the accuracy of 3D laser scanning / 대한치과교정학회지

OBJECTIVE: To investigate whether the accuracy of 3D laser scanning is influenced by the angles and number of scans. METHODS: Using a 3D laser scanner, 10 manikins with facial markers were scanned at 7 horizontal angles (front view and at 20degrees, 45degrees, and 60degrees angles on the right and left sides). Three-dimensional facial images were reconstructed by 6 methods differing in the number and angles of scans, and measurements of these images were compared to the physical measurements from the manikins. RESULTS: The laser scan images were magnified by 0.14 - 0.26%. For images reconstructed by merging 2 scans, excluding the front view; and by merging 3 scans, including the front view and scans obtained at 20degrees on both sides; several measurements were significantly different than the physical measurements. However, for images reconstructed by merging 3 scans, including the front view; and 5 scans, including the front view and scans obtained at 20degrees and 60degrees on both sides; only 1 measurement was significantly different. CONCLUSIONS: These results suggest that the number and angle of scans influence the accuracy of 3D laser scanning. A minimum of 3 scans, including the front view and scans obtained at more than 45degrees on both sides, should be integrated to obtain accurate 3D facial images.

A proposal of soft tissue landmarks for craniofacial analysis using three-dimensional laser scan imaging / 대한치과교정학회지

Three-dimensional (3-D) laser scans can provide a 3-D image of the face and it is efficient in examining specific structures of the craniofacial soft tissues. Due to the increasing concerns with the soft tissues and expansion of the treatment range, a need for 3-D soft tissue analysis has become urgent. Therefore, the purpose of this study was to evaluate the scanning error of the Vivid 900 (Minolta, Tokyo, Japan) 3-D laser scanner and Rapidform program (Inus Technology Inc., Seoul, Korea) and to evaluate the mean error and the magnification percentage of the image obtained from 3-D laser scans. In addition, soft tissue landmarks that are easy to designate and reproduce in 3-D images of normal, Class II and Class III malocclusion patients were obtained. The conclusions are as follows; scanning errors of the Vivid 900 3-D laser scanner using a manikin were 0.16 mm in the X axis, 0.15 mm in the Y axis, and 0.15 mm in the Z axis. In the comparison of actual measurements from the manikin and the 3-D image obtained from the Rapidform program, the mean error was 0.37 mm and the magnification was 0.66%. Except for the right soft tissue gonion from the 3-D image, errors of all soft tissue landmarks were within 2.0 mm. Glabella, soft tissue nasion, endocanthion, exocanthion, pronasale, subnasale, nasal alare, upper lip point, cheilion, lower lip point, soft tissue B point, soft tissue pogonion, soft tissue menton and preaurale had especially small errors. Therefore, the Rapidform program can be considered a clinically efficient tool to produce and measure 3-D images. The soft tissue landmarks proposed above are mostly anatomically important points which are also easily reproducible. These landmarks can be beneficial in 3-D diagnosis and analysis.

A study of facial soft tissue of Korean adults with normal occlusion using a three-dimensional laser scanner / 대한치과교정학회지

Developments in computer technology have made possible the 3-dimensional (3-D) evaluation of hard and soft tissues in orthodontic diagnosis, treatment planning and post-treatment results. In this study, Korean adults with normal occlusion (male 30, female 30) were scanned by a 3-D laser scanner, then 3-D facial images formed by the Rapidform 2004 program (Inus Technology Inc., Seoul, Korea.). Reference planes in the facial soft tissue 3-D images were established and a 3-D coordinate system (X axis-left/right, Y axis-superior/inferior, Z axis-anterior/posterior) was established by using the soft tissue nasion as the zero point. Twenty-nine measurement points were established on the 3-D image and 43 linear measurements, 8 angular measurements, 29 linear distance ratios were obtained. The results are as follows; there were significant differences between males and females in the nasofrontal angle (male: 142 degrees, female: 147 degrees) and transverse nasal prominence (male: 112 degrees, female: 116 degrees) (p < 0.05). The transverse upper lip prominence was 107 degrees in males, 106 degrees in females and the transverse mandibular prominence was 76 degrees in both males and females. Li-Me' was 0.4 times the length of Go-Me' (mandibular body length) and the mouth height was also 0.4 times the width of the mouth width. The linear distance ratio from the coronal reference plane of FT, Zy, Pn, ULPm, Li, Me' was -1/-1/1/0.5/0.5/-0.6 respectively. The 3-D facial model of Korean adults with normal occlusion were be constructed using coordinate values and linear measurement values. These data may be used as a reference in 3-D diagnosis and treatment planning for malocclusion and dentofacial deformity patients and applied for 3-D analysis of facial soft tissue changes before and after orthodontic treatment and orthognathic surgery.