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The Chrome Study of Chinese Teeth in Vivo and Shade Guide in Sichuan

Author: ChenLing
Tutor: ChaoYongLie
School: Sichuan University
Course: Clinical Stomatology
Keywords: Natural teeth Nine regions Color measurement Custom shade guide Shade guide Color selection Digital technique
CLC: R783.3
Type: PhD thesis
Year: 2005
Downloads: 162
Quote: 2
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Abstract


Color is an important aspect of restoration and esthetic dentistry, since Clark proposed the color of restorative dentistry in 1931; color has been a hot spot in the research of restorative dentistry. In the prosthetic applications, color selection for restorations on visual comparison of the remaining teeth with the aid of commercially available shade guides as the color standard, therefore, it is necessary for us to analyze the color of nature teeth and evaluate the association between nature teeth and shade guides. The early researches about measurement of nature teeth and shade guides are located the middle part of teeth or the cervical, middle, incisal parts of teeth, the results represent the corresponding positions. Because of the surface variation of monochromatic characteristics and color distribution across the surface of natural teeth and commercially available shade guides, color should be measured by scanning several areas on each surface. In this study the color of Chinese human in Sichuan natural teeth were measured quantitatively with a spectroradiometer (PR-650) in nine positions, in order to have a basic understanding of the database (hue, lightness, chroma, transparence) of normal maxillary incisors and the influence of age, sex, positions. Also, by the measurement of VITAPAN shade guide and the custom shade guide with metal substrate, we know the coincidence between the two shade guides and the natural teeth and the color effects of metal-porcelain crown made by metal substrate, trying to offer a theory base for instruction of color selecting and color matching in clinic. We also applying the digital image technique to measure the color of natural teeth and shade guide, to evaluate the reliability of the technique.The results showed that:1. The incisors color was symmetrical.2. The chroma of nine positions of incisors was different from each other. L* H~0 of V region is the highest, Ⅰ , Ⅲ region are the lowest; the highest a* , b*, C* in Ⅰ , Ⅲ region.3. The transparence of incisors was symmetrical, the transparence of incisorsin nine regions were different in longitudinal (cervical, middle, incisal), and discriminative in transverse (middle), the incisal regions are highest, the cervical regions are lowest.4. The color wasn’t related to sex in this study.5. The color was related to age, these effects including: the chroma L* and a* of incisors in nine regions were related to age negatively, and b* was related to age positively. Moreover, the effects aren’t consistent in nine regions.6. The 95% normal range of Chinese maxillary incisors in Sichuan were: L*: 56.0521-83.3341, a*.- 1.2568-6.7303, b*: 8.5781-26.1633, C*.-10.1175~27.704, H°: 1.1076-1.4373, Y: 25.2421-63.9535, x: 0.3391-0.3757, y: 0.3460-0.3743.7. The color spaces of VITAPAN shade guide and custom shade guide were narrower than that of natural teeth, the shade guide were short of higher lightness and higher saturation (red and yellow) shade tabs.8. The color difference of homonymy shade tabs between the custom shade guide and VITAPAN shade guide was more than 1.5 units, and can be conscious by the human eyes.9. Employing two methods to evaluate the color of duplicated restorations: the satisfaction of doctors and patients and the color difference value, the two methods both showed that the custom shade guide was better than VITA shade guide.10. By analyzing the color value measured by Canon digital camera under three different light source, the results showed color was related to light source. The color difference between the shade guide and the spectroradiometer value under standard D light source was the lowest.11. By analyzing the natural teeth’s color value measured by Canon digital camera under standard D light source, there was a high correlation between the chroma value coming from digital camera and the value from spectroradiometer (r=0.799).

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CLC: > Medicine, health > Oral Sciences > Oral orthotics > Repair correction of dental defects
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