Application of three-dimensional laser scanning-based maxillofacial soft tissue reconstruction in orthodontic treatment / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a convenient and rapid method for constructing a digital model of the maxillofacial soft tissue based on three-dimensional laser surface scanning to allow direct and accurate observation of the soft tissue changes in the course of orthodontic treatment.</p><p><b>METHODS</b>The point cloud data of three-dimensional laser scanning of the maxillofacial region were acquired from a healthy woman with Angle Class I occlusion, who maintained a horizontal Frankfort plane during scanning with the scanner placed at a distance of 80 cm. The scanning was repeated twice after wearing the dental cast for an Angle Class I occlusion. The three-dimensional digital model of the maxillofacial soft tissue was constructed based on the point cloud using GeoMagic10.0 software.</p><p><b>RESULTS</b>The high-resolution three-dimensional model of the maxillofacial soft tissue reconstructed allowed accurate observation of the distinct facial anatomical landmarks and represented directly the soft tissue changes in the process of orthodontic treatment by merging the models. Using the analytic tool provided by the software, this model also allowed direct quantitative measurement of the nasolabial angle and the distances from the esthetic plane to the upper lip, labral inferior, and mentolabial sulcus, which were 111.86°, -3.57 mm, -2.54 mm, and 3.95 mm before orthodontic treatment as compared to 114.31°, -2.73 mm, -1.06 mm, and 3.46 mm during treatment, and 116.53°, -0.15 mm, 0.64 mm, and 3.11 mm after the treatment, respectively.</p><p><b>CONCLUSION</b>Three-dimensional laser surface scanning enables accurate and rapid construction of the digital model of the facial soft tissues, which may provide valuable assistance in orthodontic treatment.</p>

Effect of microwave plasma parameters on the surface modification of denture base resins / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the working parameters of the microwave plasma for surface modification of denture base resins.</p><p><b>METHODS</b>Using orthogonal test method, 80 specimens of denture material were divided into 16 groups for testing. At the gas flow of 13.7 cm3/min, the specimens were tested under the working condition of different microwave powers (100, 150, 200 and 250 W), different gasses (oxygen, air, argon, oxygen and argon mixture), different gas pressure (0.4, 0.6, 0.8, and 1 kPa), and varying processing time (1, 2, 5, and 8 min). Each group of specimens was treated with the microwave plasma and the contact angles were confirmed by scanning electron microscopy.</p><p><b>RESULTS</b>The pictures of instantaneous droplet morphology were obtained from each group of samples, and the values of contact angle were measured. The contact angle was 68.86 degrees in the untreated group, and the angles of several treated groups were 48.15 degrees , 40.7 degrees and 32.76 degrees, showing a statistically significant variation of the contact angle after the treatment.</p><p><b>CONCLUSION</b>Processing time of 8 min, microwave power at 100 W, total pressure in the chamber at 0.8 kPa, and the presence of oxygen constitute the optimal condition of microwave plasma for surface modification of denture base resins. Under these conditions, the smallest contact angle of the denture base resins is 34.58 degrees, suggesting a good effect of surface modification.</p>

Construction of the digital models of masseter and temporal muscles with three-dimensional laser scanning / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore a new method for establishing digital models of the masseter and temporal muscles and superficial soft tissue using three-dimensional laser scanning technique.</p><p><b>METHODS</b>One adult male cadaveric head without malformation was dissected to expose the superficial portion of the masseter and temporalis. Multiple aspects of the sample were scanned with three-dimensional laser scanning system, and the point clouds of the masseter and temporal muscles were generated. The specimen was scanned again after the masseter and temporal muscles had been removed. The digital model of the muscles was reconstructed with the point clouds using Geomagic software, and the morphology of the muscle model was observed and measured.</p><p><b>RESULTS</b>The 3-D digital models of the masseter and temporal muscles with the anatomical characteristics were reconstructed based on the point clouds using Geomagic 8.0 software.</p><p><b>CONCLUSION</b>The digital model of the muscles can vividly demonstrate the muscle contours, which provides a basis for morphological study and biomechanical analysis of the muscles.</p>