Measurement and correlation analysis of vermilion and facial skin color / 中国组织工程研究

BACKGROUND: Prosthesis simulation is critical for maxillofacial defects caused by maxillofacial tumor and trauma. Few studies have been reported on the vermilion color, much less the correlation between facial skin color and vermilion color. OBJECTIVE: To collect thecolorimetric values of human vermilion and facial skin, so as to determine the colorimetric value range and its relevance.. METHODS: The colorimetric values of vermilion and facial skin in 202 volunteers were measured by Japanese Konica Minolta CM-700d spectrophotometer, L* (brightness), a* (from –a* (green) to +a* (red)), b* (from –b*(yellow) to +a* (blue)) values were surveyed and calculated, and then analyzed with CIELAB color system. The correlation betweencolorimetric values of the vermilion and cheek skin color was analyzed.RESULTS AND CONCLUSION: For the vermilion color in 202 volunteers, L* value was 53.25±3.42, a* value was 11.19±1.70, and b* valuewas 8.77±2.12; for the cheek skin color, L* value was 61.87±3.59, a* value was 7.21±1.29, and b* value was 12.98±1.64. L* value of thevermilion was negatively correlated with its a* value, positively correlated with its b* value, positively correlated with L* value of cheek skin andnegatively correlated with a* value of the cheek skin. a* value of the vermilion was positively correlated with a* value of the cheek skin. b*value of the vermilion was positively correlated with b* value of the cheek skin. L* value of the cheek skin was positively correlated with b*value of the vermilion, and negatively correlated with its a* value. a* value of the cheek skin was negatively correlated with b* value of thevermilion, and negatively correlated with its b* value. In summary, we preliminarily determine the colorimetric value range of the facial skin andvermilion, as well as their relevance, which provide a basis for prosthesis production and choice of colors in clinic.

Research on color differences between enamel and dentin of natural teeth / 第二军医大学学报

Objective To investigate the color differences of enamel and dentin of natural teeth, so as to lay a foundation for reducing the color differences of natural dentin and core of all ceramic restorations. Methods X-rite Color i7 Spectrophotometer was used to examine the chroma value and chromatic difference (δE) of enamel and dentin of natural teeth (thickness 0. 9 mm, 0. 6 mm and 0. 3 mm, n = 30). Results The L* values (lightness) of enamel and dentin increased with the decrease of slice thickness, and the a* values (red-green) and b* values (yellow-blue) decreased with the decrease of slice thickness (P<0. 05). The absolute L*, a* and b* values of the dentin were significantly greater than those of enamel of same thickness (P<0. 05). There were great color differences between enamel and dentin of different thicknesses, with the mean δE values within a range of 5. 303-13. 109. The color difference gradually increased with the thickness increase of enamel and dentin. The δE value of the enamel and dentin of the same thickness was 5. 115 (0. 9 mm), 5. 855 (0. 6 mm), and 6. 053 (0. 3 mm), respectively. Conclusion There is noticeable color difference between the enamel and dentin of natural teeth, and the difference increases with the increase of their thickness difference. The dentin has a more yellowish color and less lightness compared with the enamel. So each laminate of all ceramic restorations needs a shade selection for all ceramic restorations, and more attention should be paid on the color matching of natural dentin and core ceramic laminate.

Profiles of irregular bleeding induced by low-dose hormone therapy and Chinese formulated herbs products / 中国医学科学院学报

<p><b>OBJECTIVE</b>To compare profiles and related factors of irregular bleeding induced by different types of low-dose hormone therapy (HT) and a Chinese formulated herbs products.</p><p><b>METHODS</b>Applied with open-labeled, randomized, and clinical trial design, 136 postmenopausal women were assigned into four groups: group A: estradiol valerate (E2 V) 1 mg/d + medroxyprogesterone acetate (MPA) 2 mg/d; group B: conjugated equine estrogen 0.45 mg/d + MPA 2 mg/d; group C: tibolone 1.25 mg/d; group D: a Chinese formulated herbs product (Kuntai) 4# tid. Each subject took element calcium 400 mg/d and vitamin D 200 IU/d concomitantly. Modified Kupperman scores were assessed on baseline and every 3 months thereafter and irregular bleeding was recorded on menopausal diary every day. The duration of this study was 1 year. Results The efficacies were similar in three HT-managed groups, but was better than in group D, although the latter was also effective in alleviating menopausal symptoms. Hazard ratio (HR) of irregular bleeding was 1.00 in group C, 2.43 in group A (95% CI: 1.08-5.46), 3.12 in group B (95% CI: 1.42-6.88), and 0.73 in group D (95% CI: 0.26-2.04). Most cases initially experienced bleeding in the first 3 months but such initiation was a bit later in group C. Endometrium, as detected by B-mode ultrasound, increased approximately 1 mm in HT groups, while it was a bit thicker in group C. Long periods in reproductive age and short time since menopause were high risk factors for irregular bleeding.</p><p><b>CONCLUSION</b>Profiles of irregular bleeding in 3 commonly used types of low-dose HT are different and some factors such as long period in reproductive age and short time since menopause may contribute to bleeding initiation.</p>

Reliability of an improved measurement system used in three-dimensional reconstruction of stomatognathic system by cutting and scanning layer-by-layer / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To reconstruct 3D shape of edentulous jaw by using improved measurement system and to analyze the precision of this method.</p><p><b>METHODS</b>Standard edentulous jaw models were measured with a improved measurement system by cutting and scanning layer-by-layer, and the 3D shape of the models was reconstructed by image processing with specialty software. Ten cubic plaster modes were reconstructed by the same way, data of every border before and after reconstruction were measured and analyzed.</p><p><b>RESULTS</b>Data of edentulous jaw models were obtained. The errors in ten cubic before and after reconstruction were not significantly different (P > 0.05), data measured in horizontal plane were not significantly different (P > 0.05), and data measured in altitude direction were significantly different (P < 0.01), data measured after reconstruction were less than before, the error was (0.09 +/- 0.08) mm.</p><p><b>CONCLUSION</b>The improved cutting and scanning measurement system can be fit for the 3D reconstruction of stomatognathic system with high precision.</p>