Color Changes Caused by Reduction on the Dentin Shade Composite Thickness

Abstract

This study determined the reduction threshold in thickness of the dentin shade composite necessary to result in perceptible and acceptable color changes on simulated restorations. Three composite systems (Charisma Diamond, IPS Empress Direct, and Filtek Z350 XT) were evaluated using cylinder-shaped specimens built-up with dentin and enamel shades. The opacity of the composites was assessed using 1.0 mm thick specimens over black and white backgrounds. A baseline color was established for each system by combining 1.0 mm thick enamel shade with 3.0 mm of dentin shade cylinders over a dark background (n = 9). Then, the color changes (∆E 00 ) caused by sequential 0.1 mm reductions on dentin shade cylinders were calculated. Opacity changes on dentin shade cylinders and combined enamel-dentin pair cylinders were also assessed after each thickness reduction. Polynomial regression was performed with averages of ∆E 00 as a function of thickness of dentin shade cylinders; and acceptability (∆E = 1.77) and perceptibility (∆E = 0.81) thresholds were calculated. Linear regressions were also performed for ∆E 00 as function of opacity of dentin shade cylinders and combined enamel-dentin pair of cylinders. Except for Charisma, enamel shades presented the lowest opacity than dentin one. Perceptible and acceptable color changes were observed for dentin shade cylinders thinner than 2.0-2.4 mm and 1.1-1.4 mm, respectively, were used. No difference among the composite systems was observed. In conclusion, reductions on dentin shade composite lower than 0.6-mm did not yield perceptible color changes, and clinically significant color changes only were observed within reductions higher than 1.6-mm.

Analysis of the color matching of universal resin composites in anterior restorations

“…26 The results from the present study showed 28 Furthermore, the optical behavior of a restoration in the anterior or posterior segment of the dental arcade is different, once the improper level of translucency in anterior restorations can be more affected by the dark background of the oral cavity, resulting in grayish restorations. 17,29 Another parameter that was previously demonstrated to be efficient for color evaluation in a more practical way is the visual scoring. 11,12 The scores found for the composites tested in the present study are positively correlated to the photographic evaluation, once the highest scores demonstrated were also for OC (from 2.73 to 2.87, it means, obvious mismatch) while all the other groups presented lower scores (from 1.13 to 1.83, meaning very good match and not so good match, respectively).…”

“…A recent study concluded that CIEDE 2000 formula reflected the color differences perceived by the human eye better than CIELab 28 . Furthermore, the optical behavior of a restoration in the anterior or posterior segment of the dental arcade is different, once the improper level of translucency in anterior restorations can be more affected by the dark background of the oral cavity, resulting in grayish restorations 17,29 …”

Is it possible to determine the optical properties of resin composites with clinical spectrophotometers?

“…Such measurements have been undertaken using various methods, but with questionable validity. [4][5][6][7][8][9] Laboratory spectrophotometers have been widely used to characterize the optical properties of restorative materials, especially opacity. [4][5][6] Opacity is expressed as an index, calculated from the difference between successive measurements against black and white backgrounds.…”

“…[4][5][6][7][8][9] Laboratory spectrophotometers have been widely used to characterize the optical properties of restorative materials, especially opacity. [4][5][6] Opacity is expressed as an index, calculated from the difference between successive measurements against black and white backgrounds. The rationale is that an object must be opaque if the difference between these two measurements is small.…”

<p>Color stability of Lucirin-photo-activated resin composite after immersion in different staining solutions: a spectrophotometric study</p>

“…Teeth have a complex, layered structure, and their colors are the net result of a combination of colors from each layer. [10][11][12] For example, dentin is far more opaque and intensely colored than is enamel. 13,14 As such, the color-matching procedure is both challenging and important, 7,9,[15][16][17] especially given the increased emphasis on the appearance of patients seeking dental treatment.…”