Faltermeier Andreas, Behr Michael, Müssig Dieter
Department of Orthodontics, University Medical Center of Regensburg, Regensburg, Germany.
Am J Orthod Dentofacial Orthop. 2007 Jul;132(1):5.e13-6. doi: 10.1016/j.ajodo.2006.10.014.
An undesirable effect of plastic brackets is their discoloration after a short time in the oral cavity. The objective of this study was to investigate the influence of the filler level of plastic brackets on color stability after exposure to food dyes or ultraviolet (UV) light.
Three bracket groups were produced with silicon dioxide as the filler: an unfilled urethane-dimethacrylate (UDMA) bracket, a UDMA bracket with filler content of 35% by volume, and a UDMA bracket with filler level of 70% by volume. All brackets were exposed for 72 hours to UV light in an aging device with a xenon lamp to simulate natural daylight or to food dyes (cola or tea). Color measurements were made with a spectrophotometer according to the CIE Lab* system, and color changes (DeltaE*) were computed.
Greater exogenous discoloration was observed by raising the filler level of UDMA brackets. Almost all investigated polymer brackets showed clinically acceptable color stability during in-vitro exposure to colorants. However, almost all brackets seemed more yellow after UV light treatment.
Silicon-dioxide filler-reinforced UDMA brackets showed an obvious trend for increased exogenous discoloration when filler level was raised. Highly filled brackets were less susceptible to endogenous discoloration caused by UV light.
塑料托槽的一个不良影响是在口腔中短时间后会变色。本研究的目的是调查塑料托槽的填料含量对暴露于食用色素或紫外线（UV）光后颜色稳定性的影响。
以二氧化硅为填料制备了三组托槽：无填料的聚氨酯二甲基丙烯酸酯（UDMA）托槽、填料含量为35%（体积）的UDMA托槽和填料含量为70%（体积）的UDMA托槽。所有托槽在带有氙灯的老化装置中暴露于紫外线72小时，以模拟自然日光或暴露于食用色素（可乐或茶）。根据CIE Lab系统用分光光度计进行颜色测量，并计算颜色变化（ΔE）。
提高UDMA托槽的填料含量可观察到更大的外源性变色。几乎所有研究的聚合物托槽在体外暴露于着色剂期间都表现出临床上可接受的颜色稳定性。然而，几乎所有托槽在紫外线处理后似乎更黄。
二氧化硅填料增强的UDMA托槽在填料含量增加时显示出明显的外源性变色增加趋势。高填料含量的托槽对紫外线引起的内源性变色不太敏感。
