Objective: The objective was to provide a literature review on perceptibility and acceptability thresholds in dentistry and corresponding recommendations.Overview: A literature review on visual thresholds included findings on the judgments of the color and appearance of tooth-, gingiva-and skin-colored restorative dental materials. Discrepancies in study design contributed to inconsistencies in the research findings of some studies. These differences are related to (a) number of observers and inclusion criteria, (b) specimen number and size, (c) color measurement instrument and the setup and formulas used, (d) psychophysical experiment, (e) data processing (fitting method), and (f) % perceptibility or % acceptability values. A straightforward, consistent and practical model for the clinical and research application and interpretation of visual thresholds and recommended protocols for threshold research were provided. Conclusions: Visual thresholds are of paramount importance as a quality control tool and guide the evaluation and selection of dental materials and their clinical performance. Although clinical shade matching conditions and method are rarely controlled, research on visual thresholds, especially when aiming to set standards for the profession, must be carefully planned and executed. Clinical Significance: Perceptibility and acceptability thresholds define visual match or mismatch of color, translucency, and whiteness in dentistry. Clinical and research findings cannot be fully interpreted in terms of real-life relevance without comparison with perceptibility and acceptability tolerances.

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The color of 15 red wines from several wineries within the renowned wine-producing region Rioja (Northern Spain) was measured by spectrophotometric and spectroradiometric techniques and was visually assessed in a pair-comparison experiment by a panel of 10 experienced observers having normal color vision. Correlation between instrumental color measurements made by spectrophotometric and spectroradiometric techniques was very low, as expected from major differences in the experimental conditions employed (different illumination, path lengths and glass effects). Spectroradiometric measurements at the center of the wine sampler and at positions displaced 1 cm in the horizontal and vertical directions were quite different, mainly because of an increase of the lightness L*, the average color differences between them being high (3.5 and 2.6 CIELAB units, respectively). A 50% acceptance percentage resulted for a color difference of 2.8 CIELAB units, using a reference anchor-pair of wine samples with 4.0 CIELAB units. Thus, a value around 3.0 CIELAB units should be considered a preliminary estimate of the acceptable tolerance by the human eye for red wines poured in standard wine samplers.