Douglas R Duane, Steinhauer Tad J, Wee Alvin G
Southern Illinois University of Dental Medicine, Alton, IL 62002, USA.
J Prosthet Dent. 2007 Apr;97(4):200-8. doi: 10.1016/j.prosdent.2007.02.012.
There is little agreement in the dental literature as to how much color difference constitutes an acceptable shade mismatch or how much color difference is considered perceivable to observers. Most studies attempting to determine perceptibility and acceptability of tolerances for shade mismatches have been conducted under in vitro conditions that are not applicable to clinical scenarios.
The goal of this study was to determine valid acceptability and perceptibility tolerances for shade mismatch in an actual clinical scenario using spectroradiometric instrumentation.
A test denture was fabricated that allowed 10 maxillary left central incisors of varying shade mismatch with the right central incisor to be interchanged within the denture base. A spectroradiometer was used to determine the CIELAB coordinates and color differences (DeltaE) between the right central incisor and the interchangeable left central incisor denture teeth. The interchangeable denture teeth ranged uniformly from 1 DeltaE unit (visually undetectable) to greater than 10 DeltaE units (an obvious shade mismatch). The test denture with each of the interchangeable teeth was modeled by a subject to 28 dentists in a clinical setting. For each of the interchangeable teeth, dentist observers were asked if they could see a difference between the central incisors and, if so, whether the difference was acceptable. A Probit regression analysis was used to predict acceptability and perceptibility tolerances with 95% confidence limits.
The predicted color difference at which 50% of the dentist observers could perceive a color difference (50/50 perceptibility) was 2.6 DeltaE units. The predicted color difference at which 50% of the subjects would remake the restoration due to color mismatch (clinically unacceptable color match) was 5.5 DeltaE. Acceptability and perceptibility color tolerances at the 50/50 level were significantly different (P<.05), as their 95% confidence limits did not overlap.
Tolerances for perceptibility were significantly lower than tolerances for acceptability for shade mismatch between 2 denture teeth.
牙科文献中对于多大的颜色差异构成可接受的比色不匹配，或者多大的颜色差异被观察者视为可察觉，几乎没有一致的看法。大多数试图确定比色不匹配公差的可察觉性和可接受性的研究都是在体外条件下进行的，这些条件不适用于临床情况。
本研究的目的是使用光谱辐射测量仪器在实际临床情况下确定比色不匹配的有效可接受性和可察觉性公差。
制作了一副测试假牙，该假牙允许10颗上颌左侧中切牙与右侧中切牙存在不同程度的比色不匹配，并可在假牙基托内互换。使用光谱辐射仪确定右侧中切牙与可互换的左侧中切牙假牙牙齿之间的CIELAB坐标和颜色差异（ΔE）。可互换的假牙牙齿的颜色差异均匀地从1个ΔE单位（视觉上不可察觉）到大于10个ΔE单位（明显的比色不匹配）。在临床环境中，由一名受试者为28名牙医模拟带有每颗可互换牙齿的测试假牙。对于每颗可互换牙齿，询问牙医观察者他们是否能看出中切牙之间的差异，如果能看出，差异是否可接受。使用概率回归分析预测可接受性和可察觉性公差，并给出95%置信限。
预测50%的牙医观察者能够察觉到颜色差异（50/50可察觉性）时的颜色差异为2.6个ΔE单位。预测50%的受试者会因颜色不匹配（临床上不可接受的颜色匹配）而重新制作修复体时的颜色差异为5.5个ΔE。50/50水平的可接受性和可察觉性颜色公差显著不同（P<0.05），因为它们的95%置信限不重叠。
两颗假牙牙齿之间比色不匹配的可察觉性公差显著低于可接受性公差。
